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Igarashi K, Imai K, Matsushima S, Yamauchi-Kawaura C, Fujii K. Development and validation of the effective CNR analysis method for evaluating the contrast resolution of CT images. Phys Eng Sci Med 2024; 47:717-727. [PMID: 38451464 PMCID: PMC11166862 DOI: 10.1007/s13246-024-01400-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/04/2024] [Indexed: 03/08/2024]
Abstract
Contrast resolution is an important index for evaluating the signal detectability of computed tomographic (CT) images. Recently, various noise reduction algorithms, such as iterative reconstruction (IR) and deep learning reconstruction (DLR), have been proposed to reduce the image noise in CT images. However, these algorithms cause changes in the image noise texture and blurred image signals in CT images. Furthermore, the contrast-to-noise ratio (CNR) cannot be accurately evaluated in CT images reconstructed using noise reduction methods. Therefore, in this study, we devised a new method, namely, "effective CNR analysis," for evaluating the contrast resolution of CT images. We verified whether the proposed algorithm could evaluate the effective contrast resolution based on the signal detectability of CT images. The findings showed that the effective CNR values obtained using the proposed method correlated well with the subjective visual impressions of CT images. To investigate whether signal detectability was appropriately evaluated using effective CNR analysis, the conventional CNR analysis method was compared with the proposed method. The CNRs of the IR and DLR images calculated using conventional CNR analysis were 13.2 and 10.7, respectively. By contrast, those calculated using the effective CNR analysis were estimated to be 0.7 and 1.1, respectively. Considering that the signal visibility of DLR images was superior to that of IR images, our proposed effective CNR analysis was shown to be appropriate for evaluating the contrast resolution of CT images.
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Affiliation(s)
- Kengo Igarashi
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20, Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan.
| | - Kuniharu Imai
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20, Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
| | - Shigeru Matsushima
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20, Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
| | - Chiyo Yamauchi-Kawaura
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20, Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
| | - Keisuke Fujii
- Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, 1-1-20, Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
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Mishra S, Mishra S, Regmi S, Gupta V. A comparative study of low voltage, low contrast cerebral computed tomography angiography with iterative reconstruction and conventional cerebral computed tomography angiography. Neuroradiol J 2024; 37:221-228. [PMID: 38148622 DOI: 10.1177/19714009231224412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023] Open
Abstract
BACKGROUND Cerebral computed tomography angiography (CTA) has revolutionized the diagnosis of neurovascular emergencies. Strategies to reduce radiation, a concern for cancer, involve tube voltage and current reduction but with increased noise and inferior image quality. Hence, the objective of the study was to evaluate the quality of images obtained through low-dose radiation and low-contrast volume CTA with an iterative reconstruction (IR) technique versus standard CTA without IR. METHODS This prospective trial involved 100 adults requiring cerebral CTA for cerebrovascular diseases. They were split into two groups: one with 120 kVp tube voltage and 80 mL contrast using filtered back projection, and the other with 80 kVp and 30 mL contrast with IR. Evaluation criteria included attenuation values, signal-to-noise ratio, contrast-to-noise ratio, and subjective assessments. RESULTS Compared to 120 kVp, 80 kVp showed higher vessel attenuation in the internal (272.91 ± 30.59 vs 405.52 ± 53.08; p < .001) and middle cerebral artery (247.55 ± 29.84 vs 372.55 ± 49.02; p < .001) regions. Brain parenchymal attenuation at the centrum semiovale was lower with 80 kVp (29.12 ± 1.87 vs 24.78 ± 2.94; p < .001), accompanied by higher noise. Signal-to-noise ratio (p < .001) and contrast-to-noise ratio (p < .05) were lower at 80 kVp. Image quality didn't significantly differ, and radiation exposure reduced significantly by 70% in the 80 kVp group, suggesting its diagnostic feasibility. CONCLUSIONS The 80 kVp protocol for CTA of the cerebral vessels combined with lower contrast volume produces images with similar image quality with significant radiation effective dose and total iodine dose reduction. The 80 kVp protocol holds significant promise for replacing the standard 120 kVp protocol in cerebral CTA.
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Affiliation(s)
- Saurav Mishra
- Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research, India
- Department of Radiodiagnosis and Imaging, Vayodha Hospital, Nepal
| | - Sandeep Mishra
- Department of Neurosurgery and Neuro-intervention, Neo Multispecialty Hospital, India
| | - Sabina Regmi
- Department of Anesthesia and Intensive care, Neo Multispecialty Hospital, India
| | - Vivek Gupta
- Department of Radiodiagnosis and Imaging, Postgraduate Institute of Medical Education and Research, India
- Department of Neuro-interventional Radiology, Fortis Hospital, India
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Dieckmeyer M, Sollmann N, Kupfer K, Löffler MT, Paprottka KJ, Kirschke JS, Baum T. Computed Tomography of the Head : A Systematic Review on Acquisition and Reconstruction Techniques to Reduce Radiation Dose. Clin Neuroradiol 2023; 33:591-610. [PMID: 36862232 PMCID: PMC10449676 DOI: 10.1007/s00062-023-01271-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/24/2023] [Indexed: 03/03/2023]
Abstract
In 1971, the first computed tomography (CT) scan was performed on a patient's brain. Clinical CT systems were introduced in 1974 and dedicated to head imaging only. New technological developments, broader availability, and the clinical success of CT led to a steady growth in examination numbers. Most frequent indications for non-contrast CT (NCCT) of the head include the assessment of ischemia and stroke, intracranial hemorrhage and trauma, while CT angiography (CTA) has become the standard for first-line cerebrovascular evaluation; however, resulting improvements in patient management and clinical outcomes come at the cost of radiation exposure, increasing the risk for secondary morbidity. Therefore, radiation dose optimization should always be part of technical advancements in CT imaging but how can the dose be optimized? What dose reduction can be achieved without compromising diagnostic value, and what is the potential of the upcoming technologies artificial intelligence and photon counting CT? In this article, we look for answers to these questions by reviewing dose reduction techniques with respect to the major clinical indications of NCCT and CTA of the head, including a brief perspective on what to expect from current and future developments in CT technology with respect to radiation dose optimization.
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Affiliation(s)
- Michael Dieckmeyer
- Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Nico Sollmann
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany
| | - Karina Kupfer
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Maximilian T. Löffler
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Freiburg im Breisgau, Germany
| | - Karolin J. Paprottka
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jan S. Kirschke
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- TUM-Neuroimaging Center, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Thomas Baum
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
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Dissaux B, Cheddad El Aouni M, Ognard J, Gentric JC. Model-Based Iterative Reconstruction (MBIR) for ASPECT Scoring in Acute Stroke Patients Selection: Comparison to rCBV and Follow-Up Imaging. Tomography 2022; 8:1260-1269. [PMID: 35645390 PMCID: PMC9149901 DOI: 10.3390/tomography8030104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND To compare a model-based iterative reconstruction (MBIR) versus a hybrid iterative reconstruction (HIR) for initial and final Alberta Stroke Program Early Ct Score (ASPECT) scoring in acute ischemic stroke (AIS). We hypothesized that MBIR designed for brain computed tomography (CT) could perform better than HIR for ASPECT scoring. METHODS Among patients who had undergone CT perfusion for AIS between April 2018 and October 2019 with a follow-up imaging within 7 days, we designed a cohort of representative ASPECTS. Two readers assessed regional-cerebral-blood-volume-ASPECT (rCBV-ASPECTS) on the initial exam and final-ASPECTS on the follow-up non-contrast-CT (NCCT) in consensus. Four readers performed independently MBIR and HIR ASPECT scoring on baseline NCCT. RESULTS In total, 294 hemispheres from 147 participants (average age of 69.59 ± 15.63 SD) were analyzed. Overall raters' agreement between rCBV-map and MBIR and HIR ranged from moderate to moderate (κ = 0.54 to κ = 0.57) with HIR and moderate to substantial (κ = 0.52 to κ = 0.74) with MBIR. Overall raters' agreement between follow-up imaging and HIR/MBIR ranged from moderate to moderate (κ = 0.55 to κ = 0.59) with HIR and moderate to almost perfect (κ = 0.48 to κ = 0.82) with MBIR. CONCLUSIONS ASPECT scoring with MBIR more closely matched with initial and final infarct extent than classical HIR NCCT reconstruction.
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Affiliation(s)
- Brieg Dissaux
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Groupe d’Étude de la Thrombose Occidentale GETBO (Inserm UMR 1304), Université de Bretagne Occidentale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France
| | - Mourad Cheddad El Aouni
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
| | - Julien Ognard
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Laboratoire de Traitement de l’Information médicale—LaTIM (Inserm UMR 1101), Université de Bretagne Occidentale, 5 Avenue Foch, CEDEX, 29200 Brest, France
| | - Jean-Christophe Gentric
- Service d’Imagerie Médicale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France; (M.C.E.A.); (J.O.)
- Groupe d’Étude de la Thrombose Occidentale GETBO (Inserm UMR 1304), Université de Bretagne Occidentale, CHU de la Cavale Blanche, Boulevard Tanguy Prigent, CEDEX, 29609 Brest, France
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Kayun Z, Karim M, Muhammad N, Aljewaw O, Chew M, Harun H. Implication of applying iterative reconstruction on Low Contrast Detectability in CT brain examination. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sherif FM, Said AM, Elsayed YN, Elmogy SA. Value of using adaptive statistical iterative reconstruction-V (ASIR-V) technology in pediatric head CT dose reduction. THE EGYPTIAN JOURNAL OF RADIOLOGY AND NUCLEAR MEDICINE 2020. [DOI: 10.1186/s43055-020-00291-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
With widespread use of pediatric head CT, it is critically important to protect patients from radiation hazards, using reduced dose CT techniques. In this regard, adaptive statistical iterative reconstruction-V (ASIR-V) algorithm can decrease image noise, generating CT images of reasonable diagnostic quality with less radiation. The objective of this study was radiation dose assessment, quantitative and qualitative evaluation of reduced dose pediatric head CT using ASIR-V 60% and 80% reconstruction.
Results
Retrospective analysis was performed on two groups of pediatric head CT examinations, a reduced dose CT examination group with ASIR-V reconstruction (ASIR group) (n = 27) and a standard dose CT examination group without ASIR reconstruction (non-ASIR group) (n = 14). The average effective dose (ED) of ASIR group was significantly lower than that of the non-ASIR group (1.04 ± 0.1 mS vs 3.48 ± 0.45 mS; p = 0.001). Quantitative analysis revealed comparable results of signal to noise ratio (SNR) and contrast to noise ratio (CNR) of ASIR and non-ASIR groups (p > 0.05). Qualitative evaluation of resulting images by two readers revealed comparable results of both ASIR and non-ASIR groups (p > 0.05) with excellent inter-reader agreement (κ = 0.97). Both quantitative and qualitative assessment demonstrated better ASIR-V 80% than ASIR-V 60% reconstructed images.
Conclusion
ASIR-V algorithm is a promising technology for effective dose reduction of pediatric head CT with preservation of diagnostic image quality.
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Raslau FD, Escott EJ, Smiley J, Adams C, Feigal D, Ganesh H, Wang C, Zhang J. Dose Reduction While Preserving Diagnostic Quality in Head CT: Advancing the Application of Iterative Reconstruction Using a Live Animal Model. AJNR Am J Neuroradiol 2019; 40:1864-1870. [PMID: 31601574 DOI: 10.3174/ajnr.a6258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 08/21/2019] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Iterative reconstruction has promise in lowering the radiation dose without compromising image quality, but its full potential has not yet been realized. While phantom studies cannot fully approximate the subjective effects on image quality, live animal models afford this assessment. We characterize dose reduction in head CT by applying advanced modeled iterative reconstruction (ADMIRE) in a live ovine model while evaluating preservation of gray-white matter detectability and image texture compared with filtered back-projection. MATERIALS AND METHODS A live sheep was scanned on a Force CT scanner (Siemens) at 12 dose levels (82-982 effective mAs). Images were reconstructed with filtered back-projection and ADMIRE (strengths, 1-5). A total of 72 combinations (12 doses × 6 reconstructions) were evaluated qualitatively for resemblance to the reference image (highest dose with filtered back-projection) using 2 metrics: detectability of gray-white matter differentiation and noise-versus-smoothness in image texture. Quantitative analysis for noise, SNR, and contrast-to-noise was also performed across all dose-strength combinations. RESULTS Both qualitative and quantitative results confirm that gray-white matter differentiation suffers at a lower dose but recovers when complemented by higher iterative reconstruction strength, and image texture acquires excessive smoothness with a higher iterative reconstruction strength but recovers when complemented by dose reduction. Image quality equivalent to the reference image is achieved by a 58% dose reduction with ADMIRE-5. CONCLUSIONS An approximately 60% dose reduction may be possible while preserving diagnostic quality with the appropriate dose-strength combination. This in vivo study can serve as a useful guide for translating the full implementation of iterative reconstruction in clinical practice.
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Affiliation(s)
- F D Raslau
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.) .,Neurology (F.D.R.).,Neurosurgery (F.D.R.)
| | - E J Escott
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.).,Otolaryngology-Head and Neck Surgery (E.J.E.)
| | - J Smiley
- Laboratory Animal Resources (J.S.)
| | - C Adams
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.)
| | - D Feigal
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.)
| | - H Ganesh
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.)
| | - C Wang
- Biostatistics (C.W.), University of Kentucky, Lexington, Kentucky
| | - J Zhang
- From the Departments of Radiology (F.D.R., E.J.E., C.A., D.F., H.G., J.Z.)
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Chen CW, Chen PA, Chou CC, Fu JH, Wang PC, Hsu SH, Lai PH. Combination of Adaptive Statistical Iterative Reconstruction-V and Lower Tube Voltage During Craniocervical Computed Tomographic Angiography Yields Better Image Quality with a Reduced Radiation Dose. Acad Radiol 2019; 26:e233-e240. [PMID: 30195416 DOI: 10.1016/j.acra.2018.07.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/24/2018] [Accepted: 07/27/2018] [Indexed: 02/06/2023]
Abstract
RATIONALE AND OBJECTIVES To evaluate image quality and radiation exposure when using the adaptive statistical iterative reconstruction-V (ASIR-V) algorithm for reconstructing craniocervical computed tomographic angiography images acquired at 100 kVp. MATERIALS AND METHODS We randomly divided 121 patients into three groups: group A (conventional protocol), 120 kVp with filtered back projection; group B, 120 kVp with 50% ASIR-V; and group C, 100 kVp with 50% ASIR-V. All patients underwent scans in a 256-slice computed tomography (CT) scanner. Radiation dose (volume CT dose index), dose-length product, and effective dose, objective parameters such as arterial attenuation value, signal-to-noise ratio, contrast-to-noise ratio, and noise obtained at head, neck, and shoulder levels were compared among the groups. Subjective image quality was independently assessed by two radiologists, and interobserver reliability was assessed using kappa analysis. RESULTS The radiation dose in group C was the lowest (p < 0.01) with a 40% reduction in volume CT dose index, dose-length product, and effective dose values compared to group A, and group C showed higher arterial attenuation than either group A or B (p < 0.01). Additionally, signal-to-noise ratio and contrast-to-noise ratio were higher and noise was lower in groups B and C than group A. Group C had better subjective image quality than groups A and B (p < 0.05), and the interobserver reliability between the two radiologists was high (k = 0.783). CONCLUSION Compared to the conventional protocol, using 50% ASIR-V and the 100 kVp protocol during craniocervical computed tomographic angiography yields better objective and subjective image quality at lower radiation doses.
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Irimia A, Maher AS, Rostowsky KA, Chowdhury NF, Hwang DH, Law EM. Brain Segmentation From Computed Tomography of Healthy Aging and Geriatric Concussion at Variable Spatial Resolutions. Front Neuroinform 2019; 13:9. [PMID: 30936828 PMCID: PMC6431646 DOI: 10.3389/fninf.2019.00009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 02/05/2019] [Indexed: 12/21/2022] Open
Abstract
When properly implemented and processed, anatomic T 1-weighted magnetic resonance imaging (MRI) can be ideal for the noninvasive quantification of white matter (WM) and gray matter (GM) in the living human brain. Although MRI is more suitable for distinguishing GM from WM than computed tomography (CT), the growing clinical use of the latter technique has renewed interest in head CT segmentation. Such interest is particularly strong in settings where MRI is unavailable, logistically unfeasible or prohibitively expensive. Nevertheless, whereas MRI segmentation is a sophisticated and technically-mature research field, the task of automatically classifying soft brain tissues from CT remains largely unexplored. Furthermore, brain segmentation methods for MRI hold considerable potential for adaptation and application to CT image processing. Here we demonstrate this by combining probabilistic, atlas-based classification with topologically-constrained tissue boundary refinement to delineate WM, GM and cerebrospinal fluid (CSF) from head CT images. The feasibility and utility of this approach are revealed by comparison of MRI-only vs. CT-only segmentations in geriatric concussion victims with both MRI and CT scans. Comparison of the two segmentations yields mean Sørensen-Dice coefficients of 85.5 ± 4.6% (WM), 86.7 ± 5.6% (GM) and 91.3 ± 2.8% (CSF), as well as average Hausdorff distances of 3.76 ± 1.85 mm (WM), 3.43 ± 1.53 mm (GM) and 2.46 ± 1.27 mm (CSF). Bootstrapping results suggest that the segmentation approach is sensitive enough to yield WM, GM and CSF volume estimates within ~5%, ~4%, and ~3% of their MRI-based estimates, respectively. To our knowledge, this is the first 3D segmentation approach for CT to undergo rigorous within-subject comparison with high-resolution MRI. Results suggest that (1) standard-quality CT allows WM/GM/CSF segmentation with reasonable accuracy, and that (2) the task of soft brain tissue classification from CT merits further attention from neuroimaging researchers.
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Affiliation(s)
- Andrei Irimia
- USC Leonard Davis School of Gerontology, Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles, CA, United States
| | - Alexander S Maher
- USC Leonard Davis School of Gerontology, Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles, CA, United States
| | - Kenneth A Rostowsky
- USC Leonard Davis School of Gerontology, Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles, CA, United States
| | - Nahian F Chowdhury
- USC Leonard Davis School of Gerontology, Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles, CA, United States
| | - Darryl H Hwang
- Department of Radiology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - E Meng Law
- Department of Radiology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States.,Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States.,Faculty of Medicine, Nursing and Health Sciences, Central Clinical School, Monash University, Melbourne, VIC, Australia
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Hajdu SD, Daniel RT, Meuli RA, Zerlauth JB, Dunet V. Impact of model-based iterative reconstruction (MBIR) on image quality in cerebral CT angiography before and after intracranial aneurysm treatment. Eur J Radiol 2018; 102:109-114. [PMID: 29685523 DOI: 10.1016/j.ejrad.2018.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 03/04/2018] [Accepted: 03/05/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE To subjectively and objectively assess the impact of model-based iterative reconstruction(MBIR) on image quality in cerebral computed tomography angiography compared to adaptive statistical iterative reconstruction (ASIR). METHODS 107 patients (mean age: 58 ± 14 years) were included prior to (n = 38) and after (n = 69) intracranial aneurysm treatment. Images were acquired using a routine protocol and reconstructed with MBIR and ASIR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios in the internal carotid and middle cerebral arteries were compared between MBIR and ASIR using the Wilcoxon signed-rank test. Additionally, two neuroradiologists subjectively assessed noise, artefacts, vessel sharpness and overall quality using a semi-quantitative assessment scale. RESULTS Objective assessment revealed that MBIR reduced noise (p < 0.0001) and additionally improved SNR (p < 0.0001) and CNR (p < 0.0001) compared to ASIR in untreated and treated patients. Subjective assessment revealed that in untreated patients, MBIR improved noise reduction, artefacts, vessel sharpness and overall quality relative to ASIR (p < 0.0001). In the treated groups, noise and vessel sharpness were improved (p < 0.0001) with no change in artefacts on images reconstructed with MBIR compared to ASIR. CONCLUSION MBIR significantly improves noise, SNR, CNR and vessel sharpness in untreated and treated patients with intracranial aneurysms. MBIR does not reduce artefacts generated by metallic devices following intracranial aneurysm treatment.
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Affiliation(s)
- Steven David Hajdu
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Lausanne, Switzerland.
| | - Roy Thomas Daniel
- Department of Neurosurgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Reto Antoine Meuli
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean-Baptiste Zerlauth
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Vincent Dunet
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Lausanne, Switzerland
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Tang H, Yu N, Jia Y, Yu Y, Duan H, Han D, Ma G, Ren C, He T. Assessment of noise reduction potential and image quality improvement of a new generation adaptive statistical iterative reconstruction (ASIR-V) in chest CT. Br J Radiol 2017; 91:20170521. [PMID: 29076347 DOI: 10.1259/bjr.20170521] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE To evaluate the image quality improvement and noise reduction in routine dose, non-enhanced chest CT imaging by using a new generation adaptive statistical iterative reconstruction (ASIR-V) in comparison with ASIR algorithm. METHODS 30 patients who underwent routine dose, non-enhanced chest CT using GE Discovery CT750HU (GE Healthcare, Waukesha, WI) were included. The scan parameters included tube voltage of 120 kVp, automatic tube current modulation to obtain a noise index of 14HU, rotation speed of 0.6 s, pitch of 1.375:1 and slice thickness of 5 mm. After scanning, all scans were reconstructed with the recommended level of 40%ASIR for comparison purpose and different percentages of ASIR-V from 10% to 100% in a 10% increment. The CT attenuation values and SD of the subcutaneous fat, back muscle and descending aorta were measured at the level of tracheal carina of all reconstructed images. The signal-to-noise ratio (SNR) was calculated with SD representing image noise. The subjective image quality was independently evaluated by two experienced radiologists. RESULTS For all ASIR-V images, the objective image noise (SD) of fat, muscle and aorta decreased and SNR increased along with increasing ASIR-V percentage. The SD of 30% ASIR-V to 100% ASIR-V was significantly lower than that of 40% ASIR (p < 0.05). In terms of subjective image evaluation, all ASIR-V reconstructions had good diagnostic acceptability. However, the 50% ASIR-V to 70% ASIR-V series showed significantly superior visibility of small structures when compared with the 40% ASIR and ASIR-V of other percentages (p < 0.05), and 60% ASIR-V was the best series of all ASIR-V images, with a highest subjective image quality. The image sharpness was significantly decreased in images reconstructed by 80% ASIR-V and higher. CONCLUSION In routine dose, non-enhanced chest CT, ASIR-V shows greater potential in reducing image noise and artefacts and maintaining image sharpness when compared to the recommended level of 40%ASIR algorithm. Combining both the objective and subjective evaluation of images, non-enhanced chest CT images reconstructed with 60% ASIR-V have the highest image quality. Advances in knowledge: This is the first clinical study to evaluate the clinical value of ASIR-V in the same patients using the same CT scanner in the non-enhanced chest CT scans. It suggests that ASIR-V provides the better image quality and higher diagnostic confidence in comparison with ASIR algorithm.
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Affiliation(s)
- Hui Tang
- 1 College of Medical Technology, Shaanxi University of Chinese Medicine, Xianyang, China
| | - Nan Yu
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Yongjun Jia
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Yong Yu
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Haifeng Duan
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Dong Han
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Guangming Ma
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Chenglong Ren
- 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Taiping He
- 1 College of Medical Technology, Shaanxi University of Chinese Medicine, Xianyang, China.,2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, China
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Blasel S, Alex S, Ackermann H, Tichy J, Berkefeld J, Wagner M. Low-Dose CCT to Exclude Contraindications to Lumbar Puncture : Benefits and Limitations. Clin Neuroradiol 2017; 29:117-123. [PMID: 28965126 DOI: 10.1007/s00062-017-0628-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 09/09/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND Low-dose cranial computed tomography (LD-CCT) based on iterative reconstruction has been shown to have sufficient image quality to assess cerebrospinal fluid spaces (CSF) and midline structures but not to exclude subtle parenchymal pathologies. Patients without focal neurological deficits often undergo CCT before lumbar puncture (LP) to exclude contraindications to LP including brain herniation or increased CSF pressure. We performed LD-CCT to assess if image quality is appropriate for this indication. METHODS A total of 58 LD-CCT (220 mA/120 kV) of patients before LP were retrospectively evaluated and compared to 79 normal standard dose cranial computed tomography (SD-CCT) (350 mA/120 kV). Iterative reconstruction used for both dose levels was increased by one factor for LD-CCT. We assessed the signal-to-noise (SNR) and contrast-to-noise ratio (CNR), the dose estimates and scored diagnostic image quality by two raters independently. Significance level was set at p < 0.05. RESULTS The inner and outer CSF spaces except the sulci were equally well depicted by the LD-CCT and SD-CCT; however, depiction of the subtle density differences of the brain parenchyma and the sulci was significantly worse in the LD-CCT (p < 0.0001). The SNR in the gray matter (9.35 vs. 10.61, p < 0.05) and white matter (7.23 vs. 8.15, p < 0.001) were significantly lower in LD-CCT than in SD-CCT with significantly lower dose estimates (1.04 vs. 1.69 mSv, respectively p < 0.0001). CONCLUSION The use of LD-CCT with a dose reduction of almost 50% is sufficient to exclude contraindications to LP; however, LD-CCT cannot exclude subtle parenchymal pathologies. Therefore, in patients with suspected parenchymal pathology, SD-CCT is still the method of choice.
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Affiliation(s)
- Stella Blasel
- Institute of Neuroradiology, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany.
| | - Sarah Alex
- Institute of Neuroradiology, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany
| | - Hanns Ackermann
- Institute of Biostatistics and mathematical Modelling, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Julia Tichy
- Institute of Neurology, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany
| | - Joachim Berkefeld
- Institute of Neuroradiology, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany
| | - Marlies Wagner
- Institute of Neuroradiology, Goethe-University Hospital Frankfurt, Schleusenweg 2-16, 60528, Frankfurt, Germany
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Harris MA, Huckle J, Anthony D, Charnock P. The Acceptability of Iterative Reconstruction Algorithms in Head CT: An Assessment of Sinogram Affirmed Iterative Reconstruction (SAFIRE) vs. Filtered Back Projection (FBP) Using Phantoms. J Med Imaging Radiat Sci 2017; 48:259-269. [PMID: 31047408 DOI: 10.1016/j.jmir.2017.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 04/05/2017] [Accepted: 04/11/2017] [Indexed: 11/25/2022]
Abstract
BACKGROUND Computed tomography (CT) is the primary imaging investigation for many neurologic conditions with a proportion of patients incurring cumulative doses. Iterative reconstruction (IR) allows dose optimization, but head CT presents unique image quality complexities and may lead to strong reader preferences. OBJECTIVES This study evaluates the relationships between image quality metrics, image texture, and applied radiation dose within the context of IR head CT protocol optimization in the simulated patient setting. A secondary objective was to determine the influence of optimized protocols on diagnostic confidence using a custom phantom. METHODS AND SETTING A three-phase phantom study was performed to characterize reconstruction methods at the local reference standard and a range of exposures. CT numbers and pixel noise were quantified supplemented by noise uniformity, noise power spectrum, contrast-to-noise ratio (CNR), high- and low-contrast resolution. Reviewers scored optimized protocol images based on established reporting criteria. RESULTS Increasing strengths of IR resulted in lower pixel noise, lower noise variance, and increased CNR. At the reference standard, the image noise was reduced by 1.5 standard deviation and CNR increased by 2.0. Image quality was maintained at ≤24% relative dose reduction. With the exception of image sharpness, there were no significant differences between grading for IR and filtered back projection reconstructions. CONCLUSIONS IR has the potential to influence pixel noise, CNR, and noise variance (image texture); however, systematically optimized IR protocols can maintain the image quality of filtered back projection. This work has guided local application and acceptance of lower dose head CT protocols.
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Affiliation(s)
- Martine A Harris
- Radiology Department, Mid Yorkshire Hospitals NHS Trust, Pinderfields General Hospital, Wakefield, UK.
| | - John Huckle
- School of Healthcare, Faculty of Medicine and Health, University of Leeds, Leeds, UK
| | - Denis Anthony
- School of Healthcare, Faculty of Medicine and Health, University of Leeds, Leeds, UK
| | - Paul Charnock
- Integrated Radiological Services Ltd., Liverpool, UK
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Chen GZ, Fang XK, Zhou CS, Zhang LJ, Lu GM. Cerebral CT angiography with iterative reconstruction at 70 kVp and 30 mL iodinated contrast agent: Initial experience. Eur J Radiol 2017; 88:102-108. [DOI: 10.1016/j.ejrad.2016.12.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 11/10/2016] [Accepted: 12/30/2016] [Indexed: 01/07/2023]
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Neuroimaging of Children With Surgically Treated Hydrocephalus: A Practical Approach. AJR Am J Roentgenol 2017; 208:413-419. [DOI: 10.2214/ajr.16.16870] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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16
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Kim HG, Lee HJ, Lee SK, Kim HJ, Kim MJ. Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children. Eur Radiol 2017; 27:3609-3617. [DOI: 10.1007/s00330-017-4733-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/13/2016] [Accepted: 01/02/2017] [Indexed: 11/25/2022]
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17
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Radiation dose reduction using 100-kVp and a sinogram-affirmed iterative reconstruction algorithm in adolescent head CT: Impact on grey-white matter contrast and image noise. Eur Radiol 2016; 27:2717-2725. [PMID: 27966043 DOI: 10.1007/s00330-016-4679-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 10/13/2016] [Accepted: 11/24/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVES To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. METHODS Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. RESULTS ED was 46% lower with 100- than 120-kVp (p < 0.001). GM-WM contrast was higher, and image noise was lower, on 100-kVp-S than 120-kVp at ST (p < 0.001). CNR of 100-kVp-S was higher than of 120-kVp (p < 0.001). GM-WM contrast of 100-kVp-S was subjectively rated as better than of 120-kVp (p < 0.001). There were no significant differences in the other criteria between 100-kVp-S and 120-kVp (p = 0.072-0.966). CONCLUSIONS The 100-kVp with sinogram-affirmed IR facilitated dramatic radiation reduction and better GM-WM contrast without increasing image noise in adolescent head CT. KEY POINTS • 100-kVp head CT provides 46% radiation dose reduction compared with 120-kVp. • 100-kVp scanning improves subjective and objective GM-WM contrast. • Sinogram-affirmed IR decreases head CT image noise, especially in supratentorial region. • 100-kVp protocol with sinogram-affirmed IR is suited for adolescent head CT.
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Yu WY, Ho TS, Ko H, Chan WY, Ong S, Hui FKH. Reducing cranial computed tomography effective radiation dose by 30% using adaptive iterative dose reduction. PROCEEDINGS OF SINGAPORE HEALTHCARE 2016. [DOI: 10.1177/2010105816651655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Introduction: The use of computed tomography (CT) imaging as a diagnostic modality is increasing rapidly and CT is the dominant contributor to diagnostic medical radiation exposure. The aim of this project was to reduce the effective radiation dose to patients undergoing cranial CT examination, while maintaining diagnostic image quality. Methods: Data from a total of 1003, 132 and 27 patients were examined for three protocols: CT head, CT angiography (CTA), and CT perfusion (CTP), respectively. Following installation of adaptive iterative dose reduction (AIDR) 3D software, tube current was lowered in consecutive cycles, in a stepwise manner and effective radiation doses measured at each step. Results: Baseline effective radiation doses for CT head, CTA and CTP were 1.80, 3.60 and 3.96 mSv, at currents of 300, 280 and 130–150 mA, respectively. Using AIDR 3D and final reduced currents of 160, 190 and 70–100 mA for CT head, CTA and CTP gave effective doses of 1.29, 3.18 and 2.76 mSv, respectively. Conclusion: We demonstrated that satisfactory reductions in the effective radiation dose for CT head (28.3%), CTA (11.6%) and CTP (30.1%) can be achieved without sacrificing diagnostic image quality. We have also shown that iterative reconstruction techniques such as AIDR 3D can be effectively used to help reduce effective radiation dose. The dose reductions were performed within a short period and can be easily achievable, even in busy departments.
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Affiliation(s)
- Wai-Yung Yu
- Department of Neuroradiology, National Neuroscience Institute, Singapore
| | - Thye Sin Ho
- Department of Neuroradiology, National Neuroscience Institute, Singapore
| | - Henry Ko
- SingHealth Centre for Health Services Research, SingHealth, c/o SingHealth Office of Research, Singapore
- SingHealth & Duke-NUS Academic Medicine Research Institute, Duke-NUS Medical School, Singapore
- NHMRC Clinical Trials Centre, University of Sydney, Sydney, Australia
| | - Wai-Yee Chan
- Department of Neuroradiology, National Neuroscience Institute, Singapore
| | - Serene Ong
- SingHealth & Duke-NUS Academic Medicine Research Institute, Duke-NUS Medical School, Singapore
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Schmid AI, Uder M, Lell MM. Reaching for better image quality and lower radiation dose in head and neck CT: advanced modeled and sinogram-affirmed iterative reconstruction in combination with tube voltage adaptation. Dentomaxillofac Radiol 2016; 46:20160131. [PMID: 27540625 DOI: 10.1259/dmfr.20160131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVES The aim of this study was to evaluate image quality and radiation dose in low-dose head and neck CT comparing two different commercially available iterative reconstruction algorithms: sinogram-affirmed iterative reconstruction (SAFIRE) and advanced modeled iterative reconstruction (ADMIRE) with fixed and automated tube voltage adaptation (TVA). METHODS CT examinations of 103 patients were analysed. 58 patients were examined on a single-source CT at fixed tube voltage of 120 kV and reconstructed with filtered back projection (FBP) and SAFIRE (Strength Level 3). 45 patients were examined in a single-source mode on a dual-source CT with automated TVA and reconstructed with FBP and ADMIRE (Strength Levels 2 and 3). Image noise was calculated in seven anatomical volumes of interest. Subjective evaluation of the CT images was performed using a four-grade scale. RESULTS Mean CT numbers of FBP and the corresponding iterative reconstruction did not differ significantly (p = 0.74-0.99). Image noise was lower with both iterative reconstruction techniques than with FBP (SAFIRE 3: -22.3%; ADMIRE 2: -14.9%; ADMIRE 3: -24.2%; all p < 0.05); hence, the signal-to-noise ratio and the contrast-to-noise values were higher. Subjective image quality revealed a more favourable result for the iterative reconstruction. ADMIRE 3 in combination with automated TVA showed 14.4% (p < 0.05) less image noise with a 7.5% lower radiation dose than SAFIRE 3 with fixed tube voltage. CONCLUSIONS Higher image quality at lower radiation dose can be achieved using ADMIRE in combination with automated TVA.
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Affiliation(s)
- Andrea I Schmid
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany
| | - Michael Uder
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.,2 Imaging Science Institute (ISI) Erlangen, Department of Radiology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany
| | - Michael M Lell
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.,3 Department of Radiology and Nuclear Medicine, Klinikum Nürnberg, Germany, Paracelsus Medical University
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Østerås BH, Heggen KL, Pedersen HK, Andersen HK, Martinsen ACT. Can use of adaptive statistical iterative reconstruction reduce radiation dose in unenhanced head CT? An analysis of qualitative and quantitative image quality. Acta Radiol Open 2016; 5:2058460116645831. [PMID: 27583169 PMCID: PMC4994404 DOI: 10.1177/2058460116645831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 03/30/2016] [Indexed: 11/30/2022] Open
Abstract
Background Iterative reconstruction can reduce image noise and thereby facilitate dose reduction. Purpose To evaluate qualitative and quantitative image quality for full dose and dose reduced head computed tomography (CT) protocols reconstructed using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). Material and Methods Fourteen patients undergoing follow-up head CT were included. All patients underwent full dose (FD) exam and subsequent 15% dose reduced (DR) exam, reconstructed using FBP and 30% ASIR. Qualitative image quality was assessed using visual grading characteristics. Quantitative image quality was assessed using ROI measurements in cerebrospinal fluid (CSF), white matter, peripheral and central gray matter. Additionally, quantitative image quality was measured in Catphan and vendor’s water phantom. Results There was no significant difference in qualitative image quality between FD FBP and DR ASIR. Comparing same scan FBP versus ASIR, a noise reduction of 28.6% in CSF and between −3.7 and 3.5% in brain parenchyma was observed. Comparing FD FBP versus DR ASIR, a noise reduction of 25.7% in CSF, and −7.5 and 6.3% in brain parenchyma was observed. Image contrast increased in ASIR reconstructions. Contrast-to-noise ratio was improved in DR ASIR compared to FD FBP. In phantoms, noise reduction was in the range of 3 to 28% with image content. Conclusion There was no significant difference in qualitative image quality between full dose FBP and dose reduced ASIR. CNR improved in DR ASIR compared to FD FBP mostly due to increased contrast, not reduced noise. Therefore, we recommend using caution if reducing dose and applying ASIR to maintain image quality.
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Affiliation(s)
- Bjørn Helge Østerås
- The Intervention Centre, Oslo University Hospital, Postbox 4950, Nydalen, 0424 Oslo, Norway; Institute of Clinical Medicine, University of Oslo, 0027 Oslo, Norway
| | | | | | | | - Anne Catrine T Martinsen
- The Intervention Centre, Oslo University Hospital, Postbox 4950, Nydalen, 0424 Oslo, Norway; Institute of Physics, University of Oslo, 0027 Oslo, Norway
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21
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Wenz H, Maros ME, Meyer M, Gawlitza J, Förster A, Haubenreisser H, Kurth S, Schoenberg SO, Groden C, Henzler T. Intra-individual diagnostic image quality and organ-specific-radiation dose comparison between spiral cCT with iterative image reconstruction and z-axis automated tube current modulation and sequential cCT. Eur J Radiol Open 2016; 3:182-90. [PMID: 27504476 PMCID: PMC4969238 DOI: 10.1016/j.ejro.2016.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 05/31/2016] [Indexed: 11/16/2022] Open
Abstract
Superiority of spiral versus sequential cCT in image quality and organ-specific-radiation dose. Spiral cCT: lower organ-specific-radiation-dose in eye lense compared to tilted sequential cCT. State-of-the-art IR spiral cCT techniques has significant advantages over sequential cCT techniques.
Objectives To prospectively evaluate image quality and organ-specific-radiation dose of spiral cranial CT (cCT) combined with automated tube current modulation (ATCM) and iterative image reconstruction (IR) in comparison to sequential tilted cCT reconstructed with filtered back projection (FBP) without ATCM. Methods 31 patients with a previous performed tilted non-contrast enhanced sequential cCT aquisition on a 4-slice CT system with only FBP reconstruction and no ATCM were prospectively enrolled in this study for a clinical indicated cCT scan. All spiral cCT examinations were performed on a 3rd generation dual-source CT system using ATCM in z-axis direction. Images were reconstructed using both, FBP and IR (level 1–5). A Monte-Carlo-simulation-based analysis was used to compare organ-specific-radiation dose. Subjective image quality for various anatomic structures was evaluated using a 4-point Likert-scale and objective image quality was evaluated by comparing signal-to-noise ratios (SNR). Results Spiral cCT led to a significantly lower (p < 0.05) organ-specific-radiation dose in all targets including eye lense. Subjective image quality of spiral cCT datasets with an IR reconstruction level 5 was rated significantly higher compared to the sequential cCT acquisitions (p < 0.0001). Consecutive mean SNR was significantly higher in all spiral datasets (FBP, IR 1–5) when compared to sequential cCT with a mean SNR improvement of 44.77% (p < 0.0001). Conclusions Spiral cCT combined with ATCM and IR allows for significant-radiation dose reduction including a reduce eye lens organ-dose when compared to a tilted sequential cCT while improving subjective and objective image quality.
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Key Words
- ASPECTS, Alberta Stroke Program Early CT score
- ATCM, automated tube current modulation
- Automatic tube current modulation
- DSCT, dual-source computed tomography
- FBP, filtered back projection
- HU, hounsfield units
- ICRP, International Commission on Radiological Protection
- IR, iterative image reconstruction
- Iterative reconstruction
- MDCT, multi-detector computed tomography
- NC, caudate nucleus
- ND, normally distributed data
- NI, non-inferiority analysis
- Organ-specific-radiation dose
- SNR, signal-to-noise ratios
- Sequential cranial CT
- Spiral cranial CT
- WM, white matter
- cCT, cranial CT
- cCT, cranial computed tomography
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Affiliation(s)
- Holger Wenz
- Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Máté E Maros
- Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Mathias Meyer
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Joshua Gawlitza
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Alex Förster
- Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Holger Haubenreisser
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Stefan Kurth
- Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Stefan O Schoenberg
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Christoph Groden
- Department of Neuroradiology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
| | - Thomas Henzler
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Germany
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Iterative Reconstruction for Head CT: Effects on Radiation Dose and Image Quality. Can J Neurol Sci 2016; 41:620-5. [PMID: 25373813 DOI: 10.1017/cjn.2014.11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Iterative reconstruction has been reported to reduce radiation dose in CT, while preserving and even improving image quality. The purpose of this study was to evaluate the effects of sinogram-affirmed iterative reconstruction (SAFIRE) on radiation dose reduction and image quality for noncontrast adult head CT and to compare SAFIRE with conventional filtered back-projection (FBP) reconstruction. METHODS Institutional review board approval was obtained for this retrospective analysis of head CT scans reconstructed with SAFIRE and/or FBP for 107 patients. Radiation dose parameters were recorded from scanner-generated CT dose reports. Signal-to-noise and contrast-to-noise ratios (SNR, CNR) were calculated from gray and white matter (GM, WM) attenuation measurements. Image noise, artifacts, GM-WM differentiation, small structure visibility, and sharpness were graded by two readers. Statistical analysis included the independent-samples t test for quantitative data, the related samples Wilcoxon signed-rank test for qualitative data, the coefficient of repeatability for intraobserver variation, and κ statistics for interobserver agreement. RESULTS Mean effective dose was significantly reduced with SAFIRE from 2.0 to 1.7 mSv (p<0.0001). SAFIRE also significantly improved GM SNR, WM SNR, and GM-WM CNR (p<0.0001). Significant reductions in image noise and posterior fossa artifact as well as improvements in GM-WM differentiation, small structure visibility, and sharpness were noted with SAFIRE (P<0.005). CONCLUSIONS SAFIRE for noncontrast adult head CT reduces patient radiation dose by 15% for the settings employed at our institution, while significantly improving multiple quantitative and qualitative measures of image quality.
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Low contrast detectability and spatial resolution with model-based Iterative reconstructions of MDCT images: a phantom and cadaveric study. Eur Radiol 2016; 27:927-937. [PMID: 27300195 DOI: 10.1007/s00330-016-4444-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/22/2016] [Accepted: 05/23/2016] [Indexed: 02/06/2023]
Abstract
OBJECTIVES To compare image quality [low contrast (LC) detectability, noise, contrast-to-noise (CNR) and spatial resolution (SR)] of MDCT images reconstructed with an iterative reconstruction (IR) algorithm and a filtered back projection (FBP) algorithm. METHODS The experimental study was performed on a 256-slice MDCT. LC detectability, noise, CNR and SR were measured on a Catphan phantom scanned with decreasing doses (48.8 down to 0.7 mGy) and parameters typical of a chest CT examination. Images were reconstructed with FBP and a model-based IR algorithm. Additionally, human chest cadavers were scanned and reconstructed using the same technical parameters. Images were analyzed to illustrate the phantom results. RESULTS LC detectability and noise were statistically significantly different between the techniques, supporting model-based IR algorithm (p < 0.0001). At low doses, the noise in FBP images only enabled SR measurements of high contrast objects. The superior CNR of model-based IR algorithm enabled lower dose measurements, which showed that SR was dose and contrast dependent. Cadaver images reconstructed with model-based IR illustrated that visibility and delineation of anatomical structure edges could be deteriorated at low doses. CONCLUSION Model-based IR improved LC detectability and enabled dose reduction. At low dose, SR became dose and contrast dependent. KEY POINTS • Model- based Iterative Reconstruction improves detectability of low contrast object. • With model- based Iterative Reconstruction, spatial resolution is dose and contrast dependent. • Model-based Iterative Reconstruction algorithms enable improved IQ combined with dose-reduction possibilities. • Improvement of SR and LC detectability on the same IMR data set would reduce reconstructions.
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Mangat J, Morgan J, Benson E, Båth M, Lewis M, Reilly A. A STUDY OF THE IMAGE QUALITY OF COMPUTED TOMOGRAPHY ADAPTIVE STATISTICAL ITERATIVE RECONSTRUCTED BRAIN IMAGES USING SUBJECTIVE AND OBJECTIVE METHODS. RADIATION PROTECTION DOSIMETRY 2016; 169:92-99. [PMID: 27103646 DOI: 10.1093/rpd/ncw084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 02/26/2016] [Indexed: 06/05/2023]
Abstract
The recent reintroduction of iterative reconstruction in computed tomography has facilitated the realisation of major dose saving. The aim of this article was to investigate the possibility of achieving further savings at a site with well-established Adaptive Statistical iterative Reconstruction (ASiR™) (GE Healthcare) brain protocols. An adult patient study was conducted with observers making visual grading assessments using image quality criteria, which were compared with the frequency domain metrics, noise power spectrum and modulation transfer function. Subjective image quality equivalency was found in the 40-70% ASiR™ range, leading to the proposal of ranges for the objective metrics defining acceptable image quality. Based on the findings of both the patient-based and objective studies of the ASiR™/tube-current combinations tested, 60%/305 mA was found to fall within all, but one, of these ranges. Therefore, it is recommended that an ASiR™ level of 60%, with a noise index of 12.20, is a viable alternative to the currently used protocol featuring a 40% ASiR™ level and a noise index of 11.20, potentially representing a 16% dose saving.
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Affiliation(s)
- J Mangat
- Cardiac CT Department, Barts Heart Centre, Bartshealth NHS Trust, London, UK
| | - J Morgan
- Radiography Department, School of Health Sciences, City University, London, UK
| | - E Benson
- Medical Engineering and Physics Department, Kings College Hospital, London, UK
| | - M Båth
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg, Sweden Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - M Lewis
- Medical Physics Department, Guy's and St. Thomas' Hospital, London, UK
| | - A Reilly
- Department of Radiotherapy Physics, Altnagelvin Hospital, Londonderry, UK
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Larsson J, Båth M, Ledenius K, Thilander-Klang A. THE EFFECT OF ADAPTIVE STATISTICAL ITERATIVE RECONSTRUCTION ON THE ASSESSMENT OF DIAGNOSTIC IMAGE QUALITY AND VISUALISATION OF ANATOMICAL STRUCTURES IN PAEDIATRIC CEREBRAL CT EXAMINATIONS. RADIATION PROTECTION DOSIMETRY 2016; 169:115-122. [PMID: 26873712 DOI: 10.1093/rpd/ncv558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The purpose of this study was to investigate the effect of adaptive statistical iterative reconstruction (ASiR) on the visualisation of anatomical structures and diagnostic image quality in paediatric cerebral computed tomography (CT) examinations. Forty paediatric patients undergoing routine cerebral CT were included in the study. The raw data from CT scans were reconstructed into stacks of 5 mm thick axial images at various levels of ASiR. Three paediatric radiologists rated six questions related to the visualisation of anatomical structures and one question on diagnostic image quality, in a blinded randomised visual grading study. The evaluated anatomical structures demonstrated enhanced visibility with increasing level of ASiR, apart from the cerebrospinal fluid space around the brain. In this study, 60 % ASiR was found to be the optimal level of ASiR for paediatric cerebral CT examinations. This shows that the commonly used 30 % ASiR may not always be the optimal level.
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Affiliation(s)
- Joel Larsson
- Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden Section of Diagnostic Imaging and Functional Medicine, NU Hospital Group, SE-461 85 Trollhättan, Sweden
| | - Magnus Båth
- Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden
| | - Kerstin Ledenius
- Department of Radiology, Skaraborg Hospital, SE-541 85 Skövde, Sweden
| | - Anne Thilander-Klang
- Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden
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Fursevich DM, LiMarzi GM, O'Dell MC, Hernandez MA, Sensakovic WF. Bariatric CT Imaging: Challenges and Solutions. Radiographics 2016; 36:1076-86. [PMID: 27232505 DOI: 10.1148/rg.2016150198] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The obesity epidemic in the adult and pediatric populations affects all aspects of health care, including diagnostic imaging. With the increasing prevalence of obese and morbidly obese patients, bariatric computed tomographic (CT) imaging is becoming common in day-to-day radiology practice, and a basic understanding of the unique problems that bariatric patients pose to the imaging community is crucial in any setting. Because larger patients may not fit into conventional scanners, having a CT scanner with an adequate table load limit, a large gantry aperture, a large scan field of view, and a high-power generator is a prerequisite for bariatric imaging. Iterative reconstruction methods, high tube current, and high tube voltage can reduce the image noise that is frequently seen in bariatric CT images. Truncation artifacts, cropping artifacts, and ring artifacts frequently complicate the interpretation of CT images of larger patients. If recognized, these artifacts can be easily reduced by using the proper CT equipment, scan acquisition parameters, and postprocessing options. Lastly, because of complex contrast material dynamics, contrast material-enhanced studies of bariatric patients require special attention. Understanding how the rate of injection, the scan timing, and the total mass of iodine affect vascular and parenchymal enhancement will help to optimize contrast-enhanced studies in the bariatric population. This article familiarizes the reader with the challenges that are frequently encountered at CT imaging of bariatric patients, beginning with equipment selection and ending with a review of the most commonly encountered obesity-related artifacts and the technical considerations in the acquisition of contrast-enhanced images. (©)RSNA, 2016.
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Affiliation(s)
- Dzmitry M Fursevich
- From the Department of Diagnostic Radiology, Florida Hospital, 601 E Rollins St, Orlando, FL 32803
| | - Gary M LiMarzi
- From the Department of Diagnostic Radiology, Florida Hospital, 601 E Rollins St, Orlando, FL 32803
| | - Matthew C O'Dell
- From the Department of Diagnostic Radiology, Florida Hospital, 601 E Rollins St, Orlando, FL 32803
| | - Manuel A Hernandez
- From the Department of Diagnostic Radiology, Florida Hospital, 601 E Rollins St, Orlando, FL 32803
| | - William F Sensakovic
- From the Department of Diagnostic Radiology, Florida Hospital, 601 E Rollins St, Orlando, FL 32803
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Morel B, Bouëtté A, Lévy P, Antoni G, Chalard F, Blondiaux E, Ducou Le Pointe H. Optimization of the pediatric head computed tomography scan image quality: Reducing dose with an automatic tube potential selection in infants. J Neuroradiol 2016; 43:398-403. [PMID: 27083689 DOI: 10.1016/j.neurad.2016.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 10/30/2015] [Accepted: 03/05/2016] [Indexed: 11/28/2022]
Abstract
PURPOSE The objective of our study was to evaluate the impact of an automatic tube potential selection (ATPS) on the delivered dose and image quality in unenhanced head computed tomography (CT) scans of infants. MATERIALS AND METHODS Unenhanced head CT scans were acquired before and after the introduction of an ATPS in full automatic mode in two groups of 20 patients under one year of age. The delivered dose (CDTIvol) as the quantitative (contrast-to-noise ratio) and qualitative (based on the European CT criteria) image quality were compared on the supra- and infratentorial regions by three senior pediatric radiologists. Mann-Whitney and Fisher exact tests were performed. An interobserver Fleiss's kappa agreement was calculated for each criterion. RESULTS The use of an ATPS allowed a significant reduction in the delivered dose (-21%, p=0.0005) with no significant difference of the contrast-to-noise ratio in supra- (-5%, p=0.21) and infratentorial regions (+16%, p=0.96). In all cases, dose reduction was obtained with the same value of 100kV. It maintained a good qualitative image quality (e.g., differentiation between gray and white matter in supra-tentorial region: p=0.470). The interobserver Fleiss's kappa agreements were good to excellent. CONCLUSION ATPS is a tool that can significantly reduce the delivered dose by choosing the most appropriate tube voltage while maintaining image quality in unenhanced head CT scans of infants.
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Affiliation(s)
- Baptiste Morel
- Service de Radiologie, Hôpital Trousseau - Hôpitaux Universitaires de l'Est Parisien (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris, France.
| | - Aurélien Bouëtté
- Service de Radiologie, Hôpital Trousseau - Hôpitaux Universitaires de l'Est Parisien (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris, France
| | - Pierre Lévy
- Service de Santé Publique, Hôpital Tenon (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris & INSERM UMR S 1136, France
| | - Guillemette Antoni
- INSERM CESP Centre de Recherche en Epidémiologie et Santé des Populations, U1018, 94807 Villejuif, France
| | - François Chalard
- Service de Radiologie, Hôpital Trousseau - Hôpitaux Universitaires de l'Est Parisien (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris, France
| | - Eleonore Blondiaux
- Service de Radiologie, Hôpital Trousseau - Hôpitaux Universitaires de l'Est Parisien (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris, France
| | - Hubert Ducou Le Pointe
- Service de Radiologie, Hôpital Trousseau - Hôpitaux Universitaires de l'Est Parisien (Assistance Publique-Hôpitaux de Paris), Université Pierre et Marie Curie, Paris, France
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Mirro AE, Brady SL, Kaufman RA. Full Dose-Reduction Potential of Statistical Iterative Reconstruction for Head CT Protocols in a Predominantly Pediatric Population. AJNR Am J Neuroradiol 2016; 37:1199-205. [PMID: 27056425 DOI: 10.3174/ajnr.a4754] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/05/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE A statistical iterative reconstruction algorithm provides an effective approach to reduce patient dose by compensating for increased image noise in CT due to reduced radiation output. However, after a point, the degree to which a statistical iterative algorithm is used for image reconstruction changes the image appearance. Our aim was to determine the maximum level of statistical iterative reconstruction that can be used to establish dose-reduced head CT protocols in a primarily pediatric population while maintaining similar appearance and level of image noise in the reconstructed image. MATERIALS AND METHODS Select head examinations (brain, orbits, sinus, maxilla, and temporal bones) were investigated. Dose-reduced head protocols using an adaptive statistical iterative reconstruction were compared for image quality with the original filtered back-projection reconstructed protocols in a phantom by using the following metrics: image noise frequency (change in perceived appearance of noise texture), image noise magnitude, contrast-to-noise ratio, and spatial resolution. Dose-reduction estimates were based on CT dose index values. Patient volume CT dose index and image noise magnitude were assessed in 737 pre- and post-dose-reduced examinations. RESULTS Image noise texture was acceptable for up to 60% adaptive statistical iterative reconstruction for the soft reconstruction kernel (at both 100 and 120 kV[peak]) and up to 40% adaptive statistical iterative reconstruction for the standard reconstruction kernel. Implementation of 40% and 60% adaptive statistical iterative reconstruction led to an average reduction in the volume CT dose index of 43% for brain, 41% for orbit, 30% for maxilla, 43% for sinus, and 42% for temporal bone protocols for patients between 1 month and 26 years of age, while maintaining an average noise magnitude difference of 0.1% (range, -3% to 5%), improving the contrast-to-noise ratio of low-contrast soft-tissue targets and the spatial resolution of high-contrast bony anatomy, compared with filtered back-projection. CONCLUSIONS The methodology in this study demonstrates maximizing patient dose reduction and maintaining image quality by using statistical iterative reconstruction for a primarily pediatric population undergoing head CT examinations.
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Affiliation(s)
- A E Mirro
- From the Department of Biomedical Engineering (A.E.M.), Washington University, St. Louis, Missouri Department of Diagnostic Imaging (A.E.M. S.L.B., R.A.K.), St Jude Children's Research Hospital, Memphis, Tennessee
| | - S L Brady
- Department of Diagnostic Imaging (A.E.M. S.L.B., R.A.K.), St Jude Children's Research Hospital, Memphis, Tennessee.
| | - R A Kaufman
- Department of Diagnostic Imaging (A.E.M. S.L.B., R.A.K.), St Jude Children's Research Hospital, Memphis, Tennessee
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Guziński M, Waszczuk Ł, Sąsiadek MJ. Head CT: Image quality improvement of posterior fossa and radiation dose reduction with ASiR - comparative studies of CT head examinations. Eur Radiol 2016; 26:3691-6. [PMID: 26803506 PMCID: PMC5021717 DOI: 10.1007/s00330-015-4183-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 12/11/2015] [Accepted: 12/18/2015] [Indexed: 11/24/2022]
Abstract
Objectives To evaluate head CT protocol developed to improve visibility of the brainstem and cerebellum, lower bone-related artefacts in the posterior fossa and maintain patient radioprotection. Methods A paired comparison of head CT performed without Adaptive Statistical Iterative Reconstruction (ASiR) and a clinically indicated follow-up with 40 % ASiR was acquired in one group of 55 patients. Patients were scanned in the axial mode with different scanner settings for the brain and the posterior fossa. Objective image quality analysis was performed with signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Subjective image quality analysis was based on brain structure visibility and evaluation of the artefacts. Results We achieved 19 % reduction of total DLP and significantly better image quality of posterior fossa structures. SNR for white and grey matter in the cerebellum were 34 % to 36 % higher, respectively, CNR was improved by 142 % and subjective analyses were better for images with ASiR. Conclusions When imaging parameters are set independently for the brain and the posterior fossa imaging, ASiR has a great potential to improve CT performance: image quality of the brainstem and cerebellum is improved, and radiation dose for the brain as well as total radiation dose are reduced. Key Points •With ASiR it is possible to lower radiation dose or improve image quality •Sequentional imaging allows setting scan parameters for brain and posterior-fossa independently •We improved visibility of brainstem structures and decreased radiation dose •Total radiation dose (DLP) was decreased by 19 %
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Affiliation(s)
- Maciej Guziński
- Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556, Wrocław, Poland
| | - Łukasz Waszczuk
- Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556, Wrocław, Poland.
| | - Marek J Sąsiadek
- Department of General Radiology, Interventional Radiology and Neuroradiology, Wroclaw Medical University, Borowska 213, 50-556, Wrocław, Poland
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Kamalian S, Lev MH, Gupta R. Computed tomography imaging and angiography - principles. HANDBOOK OF CLINICAL NEUROLOGY 2016; 135:3-20. [PMID: 27432657 DOI: 10.1016/b978-0-444-53485-9.00001-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The evaluation of patients with diverse neurologic disorders was forever changed in the summer of 1973, when the first commercial computed tomography (CT) scanners were introduced. Until then, the detection and characterization of intracranial or spinal lesions could only be inferred by limited spatial resolution radioisotope scans, or by the patterns of tissue and vascular displacement on invasive pneumoencaphalography and direct carotid puncture catheter arteriography. Even the earliest-generation CT scanners - which required tens of minutes for the acquisition and reconstruction of low-resolution images (128×128 matrix) - could, based on density, noninvasively distinguish infarct, hemorrhage, and other mass lesions with unprecedented accuracy. Iodinated, intravenous contrast added further sensitivity and specificity in regions of blood-brain barrier breakdown. The advent of rapid multidetector row CT scanning in the early 1990s created renewed enthusiasm for CT, with CT angiography largely replacing direct catheter angiography. More recently, iterative reconstruction postprocessing techniques have made possible high spatial resolution, reduced noise, very low radiation dose CT scanning. The speed, spatial resolution, contrast resolution, and low radiation dose capability of present-day scanners have also facilitated dual-energy imaging which, like magnetic resonance imaging, for the first time, has allowed tissue-specific CT imaging characterization of intracranial pathology.
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Affiliation(s)
- Shervin Kamalian
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Michael H Lev
- Division of Emergency Radiology and Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Rajiv Gupta
- Division of Neuroradiology, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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Xiao H, Liu Y, Tan H, Liang P, Wang B, Su L, Wang S, Gao J. A pilot study using low-dose Spectral CT and ASIR (Adaptive Statistical Iterative Reconstruction) algorithm to diagnose solitary pulmonary nodules. BMC Med Imaging 2015; 15:54. [PMID: 26576676 PMCID: PMC4647278 DOI: 10.1186/s12880-015-0096-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 10/25/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lung cancer is the most common cancer which has the highest mortality rate. With the development of computed tomography (CT) techniques, the case detection rates of solitary pulmonary nodules (SPN) has constantly increased and the diagnosis accuracy of SPN has remained a hot topic in clinical and imaging diagnosis. The aim of this study was to evaluate the combination of low-dose spectral CT and ASIR (Adaptive Statistical Iterative Reconstruction) algorithm in the diagnosis of solitary pulmonary nodules (SPN). METHODS 62 patients with SPN (42 cases of benign SPN and 20 cases of malignant SPN, pathology confirmed) were scanned by spectral CT with a dual-phase contrast-enhanced method. The iodine and water concentration (IC and WC) of the lesion and the artery in the image that had the same density were measured by the GSI (Gemstone Spectral Imaging) software. The normalized iodine and water concentration (NIC and NWC) of the lesion and the normalized iodine and water concentration difference (ICD and WCD) between the arterial and venous phases (AP and VP) were also calculated. The spectral HU (Hounsfield Unit ) curve was divided into 3 sections based on the energy (40-70, 70-100 and 100-140 keV) and the slopes (λHU) in both phases were calculated. The ICAP, ICVP, WCAP and WCVP, NIC and NWC, and the λHU in benign and malignant SPN were compared by independent sample t-test. RESULTS The iodine related parameters (ICAP, ICVP, NICAP, NICVP, and the ICD) of malignant SPN were significantly higher than that of benign SPN (t = 3.310, 1.330, 2.388, 1.669 and 3.251, respectively, P <0.05). The 3 λHU values of venous phase in malignant SPN were higher than that of benign SPN (t = 3.803, 2.846 and 3.205, P <0.05). The difference of water related parameters (WCAP, WCVP, NWCAP, NWCVP and WCD) between malignant and benign SPN were not significant (t = 0.666, 0.257, 0.104, 0.550 and 0.585, P > 0.05). CONCLUSIONS The iodine related parameters and the slope of spectral curve are useful markers to distinguish the benign from the malignant lung diseases, and its application is extremely feasible in clinical applications.
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Affiliation(s)
- Huijuan Xiao
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Yihe Liu
- The No.7 People's Hospital of Zhengzhou, 17 Jingnan 5th Road, Zhengzhou Economic and Technological Development Zone, Zhengzhou, Henan Province, 450000, China.
| | - Hongna Tan
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Pan Liang
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Bo Wang
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Lei Su
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Suya Wang
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
| | - Jianbo Gao
- The Department of Radiology, The First Affiliated Hospital of Zhengzhou University, No.1, East Jianshe Road, Zhengzhou, Henan Province, 450052, China.
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Iterative Reconstruction Leads to Increased Subjective and Objective Image Quality in Cranial CT in Patients With Stroke. AJR Am J Roentgenol 2015; 205:618-22. [PMID: 26295650 DOI: 10.2214/ajr.15.14389] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE The purpose of this study was to determine whether iterative reconstruction improves the quality of cranial CT (CCT) images of stroke patients. MATERIALS AND METHODS Fifty-one CCT studies of patients with infarction performed with either a low (260 mAs; n = 21) or standard (340 mAs; n = 30) dose were reconstructed with both filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with five strength levels (S1-S5). The resulting six image sets (one FBP and one each for SAFIRE levels S1-S5) were rated separately by two blinded radiologists in terms of conspicuity of infarcted areas on a 5-point scale. Noise and infarct-to-normal brain as well as medullary-to-cortical contrast-to-noise ratios (CNRs) were measured. Ratings, noise, and CNRs were intraindividually compared within the same dose group (Fisher exact test) and interindividually between the different dose groups (Wilcoxon-Mann-Whitney U test). RESULTS The strength level S4 showed the best conspicuity of infarcted areas. Compared with FBP, SAFIRE S4 statistically significantly (p < 0.01) reduced noise and improved CNRs without statistically significant differences in all subjective and objective criteria (p > 0.01) when the dose was reduced. Patients examined with a 260-mAs low-dose were exposed to a statistically significantly lower dose (1.77 vs 2.33 mSv; p < 0.01). CONCLUSION Iterative reconstruction (SAFIRE at strength level S4) leads to increased subjective and objective image quality in CCT and allows dose reduction (-24%) without losses in the demarcation of ischemic lesions.
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Ono S, Niwa T, Yanagimachi N, Yamashita T, Okazaki T, Nomura T, Hashimoto J, Imai Y. Improved image quality of helical computed tomography of the head in children by iterative reconstruction. J Neuroradiol 2015; 43:31-6. [PMID: 26519982 DOI: 10.1016/j.neurad.2015.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 07/28/2015] [Accepted: 07/29/2015] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND PURPOSE Iterative reconstruction (IR) offers noise reduction and improved image quality of computed tomography (CT). Our aim was to assess the imaging quality of non-contrast helical CT of the head in children using IR. MATERIALS AND METHODS This study recruited 78 consecutive children aged ≤5 years (range: from 3 months to 5 years; mean: 1.7 years) who underwent an emergent non-enhanced helical CT of the head with no abnormal findings. The acquired data were reconstructed using filtered back projection (FBP) and sinogram-affirmed IR (SAFIRE) with strength levels of 2 (IR2) and 4 (IR4). The imaging quality of FBP, IR2 and IR4 was scored by two experienced neuroradiologists in terms of the contrast between the gray-white matter junction and artifacts from the skull at the level of the semioval center, basal ganglia and fourth ventricle. FBP, IR2 and IR4 scores were compared at each slice level. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for FBP, IR2 and IR4 and were compared among the three reconstruction algorithms. RESULTS The score of IR2 and IR4 was significantly higher than that of FBP in terms of both the contrast between the gray-white matter junction and artifacts from the skull at each slice level (P<0.001). SNR and CNR on IR4 were the highest followed by those on IR2 and FBP (P<0.001). CONCLUSIONS IR may improve the image quality of helical CT of the head in children.
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Affiliation(s)
- Shun Ono
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
| | - Tetsu Niwa
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan.
| | - Noriharu Yanagimachi
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
| | - Tomohiro Yamashita
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan; Department of Radiology, Isehara Kyodo Hospital, 345, Tanaka, Isehara 259-1132, Japan
| | - Takashi Okazaki
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
| | - Takakiyo Nomura
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
| | - Jun Hashimoto
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
| | - Yutaka Imai
- Department of Radiology, Tokai University School of Medicine, 143, Shimokasuya, Isehara 259-1193, Japan
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Geyer LL, Schoepf UJ, Meinel FG, Nance JW, Bastarrika G, Leipsic JA, Paul NS, Rengo M, Laghi A, De Cecco CN. State of the Art: Iterative CT Reconstruction Techniques. Radiology 2015. [PMID: 26203706 DOI: 10.1148/radiol.2015132766] [Citation(s) in RCA: 398] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Lucas L Geyer
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - U Joseph Schoepf
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Felix G Meinel
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - John W Nance
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Gorka Bastarrika
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Jonathon A Leipsic
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Narinder S Paul
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Marco Rengo
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Andrea Laghi
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
| | - Carlo N De Cecco
- From the Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29425 (L.L.G., U.J.S., F.G.M., J.W.N., C.N.D.); Department of Radiology, Sunnybrook Health Sciences Centre, Toronto, Ont, Canada (G.B.); Department of Radiology, University of British Columbia, Vancouver, BC, Canada (J.A.L.); Department of Radiology, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (N.S.P.); and Department of Radiological Sciences, Oncology and Pathology, University of Rome Sapienza-Polo Pontino, Latina, Italy (M.R., A.L., C.N.D.)
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Improving head and neck CTA with hybrid and model-based iterative reconstruction techniques. Clin Radiol 2015; 70:1252-9. [PMID: 26227475 DOI: 10.1016/j.crad.2015.06.095] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/09/2015] [Accepted: 06/25/2015] [Indexed: 11/23/2022]
Abstract
AIM To compare image quality of head and neck computed tomography angiography (CTA) reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MIR) algorithms. MATERIALS AND METHODS The raw data of 34 studies were simultaneously reconstructed with FBP, HIR (iDose(4), Philips Healthcare, Best, the Netherlands), and with a prototype version of a MIR algorithm (IMR, Philips Healthcare). Objective (contrast-to-noise ratio [CNR], vascular contrast, automatic vessel analysis [AVA], stenosis grade) and subjective image quality (ranking at level of the circle of Willis, carotid bifurcation, and shoulder) of the five reconstructions were compared using repeated-measures analysis of variance (ANOVA) and post-hoc analysis. RESULTS Vascular contrast was significantly higher in both the circle of Willis and carotid bifurcation with both levels of MIR compared to the other reconstruction methods (all p<0.0001). The CNR was highest for high MIR, followed by low MIR, high HIR, mid HIR and FBP (p<0.001 except low MIR versus high HIR; p>0.33). AVA showed most complete carotids in both MIR-levels, followed by high HIR (p>0.08), mid HIR (p<0.023) and FBP (p<0.010), vertebral arteries completeness was similar (p=0.40 and p=0.06). Stenosis grade showed no significant differences (p=0.16). High HIR showed the best subjective image quality at the circle of Willis and carotid bifurcation level, followed by mid HIR. At shoulder level, low MIR and high HIR were ranked best, followed by high MIR. CONCLUSION Objectively, MIR significantly improved the overall image quality, reduced image noise, and improved automated vessel analysis, whereas FBP showed the lowest objective image quality. Subjectively, the highest level of HIR was considered superior at the level of the circle of Willis and the carotid bifurcation, and along with the lowest level of MIR for the origins of the neck arteries at shoulder level.
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Abstract
1. CT radiation dose optimization is one of the major concerns for the scientific community. 2. CT image quality is dependent on the selected image reconstruction algorithm. 3. Iterative reconstruction algorithms have reemerged with the potential of radiation dose optimization by lowering image noise. 4. Tube current is the most common parameter used to reduce radiation dose along with iterative reconstruction. 5. Tube potential (kV) is also used for dose optimization with iterative reconstruction in CT angiography protocols and small patients.
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Baskan O, Erol C, Ozbek H, Paksoy Y. Effect of radiation dose reduction on image quality in adult head CT with noise-suppressing reconstruction system with a 256 slice MDCT. J Appl Clin Med Phys 2015; 16:5360. [PMID: 26103494 PMCID: PMC5690139 DOI: 10.1120/jacmp.v16i3.5360] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 01/23/2015] [Accepted: 01/21/2015] [Indexed: 11/23/2022] Open
Abstract
The purpose of our study was to investigate the effect of iterative reconstruction (IR) as a dose reduction system on the image quality (IQ) of the adult head computed tomography (CT) at various low‐dose levels, and to identify ways of setting the amount of dose reduction. We performed two noncontrast low‐dose (LD) adult head CT protocols modified by lowering the tube current with IR which were decided in the light of a group of phantom studies. Two groups of patients, each 100 underwent noncontrast head CT with LD‐I and LD‐II, respectively. These groups were compared with 100 consecutive standard dose (STD) adult head CT protocol in terms of quantitative and qualitative IQ. The signal‐to‐noise ratio (SNR) of the white matter (WM) and gray matter (GM) and contrast‐to‐noise ratio (CNR) values in the LD groups were higher than the STD group. The differences were statistically significant. When the STD and the LD groups were compared qualitatively, no significant differences were found in overall quality. By selecting the appropriate level of IR 34%, radiation dose reduction in adult head CT can be achieved without compromising IQ. PACS number: 87.57.‐s
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Ultralow-dose CT of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction and model-based iterative reconstruction: 2D and 3D image quality. AJR Am J Roentgenol 2015; 204:563-9. [PMID: 25714286 DOI: 10.2214/ajr.14.12766] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE. The purpose of this article is to evaluate 2D and 3D image quality of high-resolution ultralow-dose CT images of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) in comparison with standard filtered backprojection (FBP). MATERIALS AND METHODS. A formalin-fixed human cadaver head was scanned using a clinical reference protocol at a CT dose index volume of 30.48 mGy and a series of five ultralow-dose protocols at 3.48, 2.19, 0.82, 0.44, and 0.22 mGy using FBP and ASIR at 50% (ASIR-50), ASIR at 100% (ASIR-100), and MBIR. Blinded 2D axial and 3D volume-rendered images were compared with each other by three readers using top-down scoring. Scores were analyzed per protocol or dose and reconstruction. All images were compared with the FBP reference at 30.48 mGy. A nonparametric Mann-Whitney U test was used. Statistical significance was set at p < 0.05. RESULTS. For 2D images, the FBP reference at 30.48 mGy did not statistically significantly differ from ASIR-100 at 3.48 mGy, ASIR-100 at 2.19 mGy, and MBIR at 0.82 mGy. MBIR at 2.19 and 3.48 mGy scored statistically significantly better than the FBP reference (p = 0.032 and 0.001, respectively). For 3D images, the FBP reference at 30.48 mGy did not statistically significantly differ from all reconstructions at 3.48 mGy; FBP and ASIR-100 at 2.19 mGy; FBP, ASIR-100, and MBIR at 0.82 mGy; MBIR at 0.44 mGy; and MBIR at 0.22 mGy. CONCLUSION. MBIR (2D and 3D) and ASIR-100 (2D) may significantly improve subjective image quality of ultralow-dose images and may allow more than 90% dose reductions.
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Brodoefel H, Bender B, Schabel C, Fenchel M, Ernemann U, Korn A. Potential of combining iterative reconstruction with noise efficient detector design: aggressive dose reduction in head CT. Br J Radiol 2015; 88:20140404. [PMID: 25827204 DOI: 10.1259/bjr.20140404] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE With further increase of CT numbers and their dominant contribution to medical exposure, there is a recent quest for more effective dose control. While reintroduction of iterative reconstruction (IR) has proved its potential in many applications, a novel focus is placed on more noise efficient detectors. Our purpose was to assess the potential of IR in combination with an integrated circuit detector (ICD) for aggressive dose reduction in head CT. METHODS Non-contrast low-dose head CT [190 mAs; weighted volume CT dose index (CTDIvol), 33.2 mGy] was performed in 50 consecutive patients, using a new noise efficient detector and IR. Images were assessed in terms of quantitative and qualitative image quality and compared with standard dose acquisitions (320 mAs; CTDIvol, 59.7 mGy) using a conventional detector and filtered back projection. RESULTS By combining ICD and IR in low-dose examinations, the signal to noise was improved by about 13% above the baseline level in the standard-dose control group. Both, contrast-to-noise ratio (2.02 ± 0.6 vs 1.88 ± 0.4; p = 0.18) and objective measurements of image sharpness (695 ± 84 vs 705 ± 151 change in Hounsfield units per pixel; p = 0.79) were fully preserved in the low-dose group. Likewise, there was no significant difference in the grading of several subjective image quality parameters when both noise-reducing strategies were used in low-dose examinations. CONCLUSION Combination of noise efficient detector with IR allows for meaningful dose reduction in head CT without compromise of standard image quality. ADVANCES IN KNOWLEDGE Our study demonstrates the feasibility of almost 50% dose reduction in head CT dose (1.1 mSv per scan) through combination of novel dose-reducing strategies.
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Affiliation(s)
- H Brodoefel
- 1 Department of Diagnostic and Interventional Radiology, University of Tübingen, Tübingen, Germany
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Na DG, Sohn CH, Kim EY. Imaging-based management of acute ischemic stroke patients: current neuroradiological perspectives. Korean J Radiol 2015; 16:372-90. [PMID: 25741200 PMCID: PMC4347274 DOI: 10.3348/kjr.2015.16.2.372] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 12/02/2014] [Indexed: 01/05/2023] Open
Abstract
Advances in imaging-based management of acute ischemic stroke now provide crucial information such as infarct core, ischemic penumbra/degree of collaterals, vessel occlusion, and thrombus that helps in the selection of the best candidates for reperfusion therapy. It also predicts thrombolytic efficacy and benefit or potential hazards from therapy. Thus, radiologists should be familiar with various imaging studies for patients with acute ischemic stroke and the applicability to clinical trials. This helps radiologists to obtain optimal rapid imaging as well as its accurate interpretation. This review is focused on imaging studies for acute ischemic stroke, including their roles in recent clinical trials and some guidelines to optimal interpretation.
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Affiliation(s)
- Dong Gyu Na
- Department of Neuroradiology, Head & Neck Radiology, Thyroid Radiology Human Medical Imaging & Intervention Center, Seoul 137-902, Korea
| | - Chul-Ho Sohn
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea
| | - Eung Yeop Kim
- Department of Radiology, Gachon University Gil Medical Center, Incheon 405-760, Korea
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Widmann G, Dalla Torre D, Hoermann R, Schullian P, Gassner EM, Bale R, Puelacher W. Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR. Int J Oral Maxillofac Surg 2015; 44:441-6. [PMID: 25680629 DOI: 10.1016/j.ijom.2015.01.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 01/15/2015] [Indexed: 10/24/2022]
Abstract
The influence of dose reductions on diagnostic quality using a series of high-resolution ultralow-dose computed tomography (CT) scans for computer-assisted planning and surgery including the most recent iterative reconstruction algorithms was evaluated and compared with the fracture detectability of a standard cranial emergency protocol. A human cadaver head including the mandible was artificially prepared with midfacial and orbital fractures and scanned using a 64-multislice CT scanner. The CT dose index volume (CTDIvol) and effective doses were calculated using application software. Noise was evaluated as the standard deviation in Hounsfield units within an identical region of interest in the posterior fossa. Diagnostic quality was assessed by consensus reading of a craniomaxillofacial surgeon and radiologist. Compared with the emergency protocol at CTDIvol 35.3 mGy and effective dose 3.6 mSv, low-dose protocols down to CTDIvol 1.0 mGy and 0.1 mSv (97% dose reduction) may be sufficient for the diagnosis of dislocated craniofacial fractures. Non-dislocated fractures may be detected at CTDIvol 2.6 mGy and 0.3 mSv (93% dose reduction). Adaptive statistical iterative reconstruction (ASIR) 50 and 100 reduced average noise by 30% and 56%, and model-based iterative reconstruction (MBIR) by 93%. However, the detection rate of fractures could not be improved due to smoothing effects.
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Affiliation(s)
- G Widmann
- Department of Radiology, Innsbruck Medical University, Innsbruck, Austria.
| | - D Dalla Torre
- Department of Craniomaxillofacial Surgery, Innsbruck Medical University, Innsbruck, Austria
| | - R Hoermann
- Department of Anatomy, Innsbruck Medical University, Innsbruck, Austria
| | - P Schullian
- Department of Radiology, Innsbruck Medical University, Innsbruck, Austria
| | - E M Gassner
- Department of Radiology, Innsbruck Medical University, Innsbruck, Austria
| | - R Bale
- Department of Radiology, Innsbruck Medical University, Innsbruck, Austria
| | - W Puelacher
- Department of Craniomaxillofacial Surgery, Innsbruck Medical University, Innsbruck, Austria
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Chen GZ, Zhang LJ, Schoepf UJ, Wichmann JL, Milliken CM, Zhou CS, Qi L, Luo S, Lu GM. Radiation dose and image quality of 70 kVp cerebral CT angiography with optimized sinogram-affirmed iterative reconstruction: comparison with 120 kVp cerebral CT angiography. Eur Radiol 2015; 25:1453-63. [PMID: 25636415 DOI: 10.1007/s00330-014-3533-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/15/2014] [Accepted: 11/20/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To evaluate radiation dose, image quality, and optimal level of sinogram-affirmed iterative reconstruction (SAFIRE) of cerebral CT angiography (CTA) at 70 kVp. METHODS One hundred patients were prospectively classified into two groups: Group A (n = 50), 70 kVp cerebral CTA with 5 levels of SAFIRE reconstruction (S1-S5); and Group B (n = 50), 120 kVp with filtered back projection (FBP) reconstruction. CT attenuation values, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured. Subjective image quality was evaluated. Effective dose (ED) was estimated. RESULTS CT attenuation and noise of the ICA and MCA in Group A were higher than those of Group B (all P < 0.001) while the SNRICA, SNRMCA, CNRICA, and CNRMCA of Group A at S4-5 were comparable to (P > 0.05) or higher than in Group B (P < 0.05). There was no difference in overall image quality between Group A S3-5 and Group B (P > 0.05). ED was 0.2 ± 0.0 mSv for Group A with 85 % ED reduction in comparison to Group B (1.3 ± 0.2 mSv). CONCLUSION Cerebral CTA at 70 kVp is feasible, allowing for substantial radiation dose reduction. SAFIRE S4 level is recommended for obtaining optimal image quality. KEY POINTS • 70 kVp cerebral CTA is feasible and provides diagnostic image quality. • 70 kVp cerebral CTA resulted in 85% effective dose reduction. • S4 level of SAFIRE is recommended for 70 kVp cerebral CTA.
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Affiliation(s)
- Guo Zhong Chen
- Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, 210002, China
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Low-Dose Computed Tomography With Adaptive Statistical Iterative Reconstruction and Low Tube Voltage in Craniocervical Computed Tomographic Angiography. J Comput Assist Tomogr 2015; 39:774-80. [DOI: 10.1097/rct.0000000000000260] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Korn A, Bender B, Spira D, Schabel C, Bhadelia R, Claussen C, Ernemann U, Brodoefel H. Added value of integrated circuit detector in head CT: objective and subjective image quality in comparison to conventional detector design. Acad Radiol 2014; 21:1506-11. [PMID: 25201378 DOI: 10.1016/j.acra.2014.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/13/2014] [Accepted: 07/17/2014] [Indexed: 11/29/2022]
Abstract
RATIONALE AND OBJECTIVES A new computed tomography (CT) detector with integrated electric components and shorter conducting pathways has recently been introduced to decrease system inherent electronic noise. The purpose of this study was to assess the potential benefit of such integrated circuit detector (ICD) in head CT by comparing objective and subjective image quality in low-dose examinations with a conventional detector design. MATERIALS AND METHODS Using a conventional detector, reduced-dose noncontrast head CT (255 mAs; effective dose, 1.7 mSv) was performed in 25 consecutive patients. Following transition to ICD, 25 consecutive patients were scanned using identical imaging parameters. Images in both groups were reconstructed with iterative reconstruction (IR) and filtered back projection (FBP) and assessed in terms of quantitative and qualitative image quality. RESULTS Acquisition of head CT using ICD increased signal-to-noise ratio of gray and white matter by 14% (10.0 ± 1.6 vs. 11.4 ± 2.5; P = .02) and 17% (8.2 ± 0.8 vs. 9.6 ± 1.5; P = .000). The associated improvement in contrast-to-noise ratio was 12% (2.0 ± 0.5 vs. 2.2 ± 0.6; P = .121). In addition, there was a 51% increase in objective image sharpness (582 ± 85 vs. 884.5 ± 191; change in HU/Pixel; P < .000). Compared to standard acquisitions, subjective grading of noise and overall image quality scores were significantly improved with ICD (2.1 ± 0.3 vs. 1.6 ± 0.3; P < .000; 2.0 ± 0.5 vs. 1.6 ± 0.3; P = .001). Moreover, streak artifacts in the posterior fossa were substantially reduced (2.3 ± 0.7 vs. 1.7 ± 0.5; P = .004). CONCLUSIONS At the same radiation level, acquisition of head CT with ICD achieves superior objective and subjective image quality and provides potential for significant dose reduction.
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Affiliation(s)
- Andreas Korn
- Department of Diagnostic und Interventional Neuroradiology, University of Tübingen, Tübingen, Germany
| | - Benjamin Bender
- Department of Diagnostic und Interventional Neuroradiology, University of Tübingen, Tübingen, Germany
| | - Daniel Spira
- Department of Diagnostic und Interventional Radiology, Tubingen, Germany
| | - Christoph Schabel
- Department of Diagnostic und Interventional Radiology, Tubingen, Germany
| | - Rafeeque Bhadelia
- Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02115
| | - Claus Claussen
- Department of Diagnostic und Interventional Radiology, Tubingen, Germany
| | - Ulrike Ernemann
- Department of Diagnostic und Interventional Neuroradiology, University of Tübingen, Tübingen, Germany
| | - Harald Brodoefel
- Department of Diagnostic und Interventional Radiology, Tubingen, Germany; Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02115.
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Model-based iterative reconstruction for detection of subtle hypoattenuation in early cerebral infarction: a phantom study. Jpn J Radiol 2014; 33:26-32. [DOI: 10.1007/s11604-014-0376-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022]
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Yang CH, Wu TH, Chiou YY, Hung SC, Lin CJ, Chen YC, Sheu MH, Guo WY, Chiu CF. Imaging quality and diagnostic reliability of low-dose computed tomography lumbar spine for evaluating patients with spinal disorders. Spine J 2014; 14:2682-90. [PMID: 24650849 DOI: 10.1016/j.spinee.2014.03.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 02/11/2014] [Accepted: 03/04/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Computed tomography (CT) scans of the lumbar spine (CTLS) have demonstrated a higher level of accuracy than plain films and have been used to assess patients with spinal disorder when magnetic resonance imaging is not available. Nevertheless, radiation exposure remains a serious safety concern. Iterative reconstruction (IR) decreases the CT radiation dose for diagnostic imaging. However, the feasibility of using IR in CTLS is unclear. PURPOSE To evaluate the imaging quality and diagnostic reliability of CTLS with IR. STUDY DESIGN A prospective study. PATIENT SAMPLE All patients from outpatient departments who suffered from spinal disorders and were referred for CTLS. OUTCOME MEASURES In acquired CT images, the signal-to-noise ratio (SNR) of the dural sac (DS), intervertebral disc (IVD), psoas muscle (PM), and L5 vertebral body, the contrast-to-noise ratio between the DS and IVD (D-D CNR), and the subjective imaging qualities were compared across groups. Interobserver agreement was evaluated with kappa values. METHODS Patients receiving low radiation CTLS were divided into three groups. A 150 mAs tube current with 120 kVp tube voltage was used with Group A and a 230 mAs tube current with 100 kVp tube voltage with Group B. Intended end radiation exposure was 50% less than that of the control group. Tube modulation was active for all groups. The images of the two low-radiation groups were reconstructed by IR; those of the control group by filtered back-projection (FBP). RESULTS The SNRs of the DS, IVD, PM, BM, and D-D CNR of Group A were not inferior to those of the control group. All SNRs and D-D CNRs for Group B were inferior to those of the control group. Except for that of the facet joint, all subjective imaging ratings for anatomic regions were equivalent between Groups A and B. Interobserver agreement was highest for the control group (0.72-0.88), followed by Group A (0.69-0.83) and B (0.55-0.83). CONCLUSIONS Fifty percent tube current reduction combined with IR provides equivalent diagnostic accuracy and improved patient safety when compared with conventional CTLS. Our results support its use as a screening tool. With the tube modulation technique, further adjustments in weighting IR and FBP algorithms based on body mass index become unnecessary.
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Affiliation(s)
- Cheng-Hui Yang
- Department of Medical Imaging, Pojen General Hopsital, No.66, Guangfu N. Rd, Songshan Dist, Taipei City 10560, Taiwan; School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan
| | - Tung-Hsin Wu
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan
| | - Yi-You Chiou
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
| | - Sheng-Che Hung
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
| | - Chung-Jung Lin
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan.
| | - Ying-Chou Chen
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
| | - Ming-Huei Sheu
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
| | - Wan-Yuo Guo
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
| | - Chen-Fen Chiu
- School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St, Beitou Dist, Taipei City 11221, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No. 201, Sec. II, Shipai Rd, Taipei 11217, Taiwan
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Seibert JA. Iterative reconstruction: how it works, how to apply it. Pediatr Radiol 2014; 44 Suppl 3:431-9. [PMID: 25304701 DOI: 10.1007/s00247-014-3102-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/19/2014] [Indexed: 11/28/2022]
Abstract
Computed tomography acquires X-ray projection data from multiple angles though an object to generate a tomographic rendition of its attenuation characteristics. Filtered back projection is a fast, closed analytical solution to the reconstruction process, whereby all projections are equally weighted, but is prone to deliver inadequate image quality when the dose levels are reduced. Iterative reconstruction is an algorithmic method that uses statistical and geometric models to variably weight the image data in a process that can be solved iteratively to independently reduce noise and preserve resolution and image quality. Applications of this technology in a clinical setting can result in lower dose on the order of 20-40% compared to a standard filtered back projection reconstruction for most exams. A carefully planned implementation strategy and methodological approach is necessary to achieve the goals of lower dose with uncompromised image quality.
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Affiliation(s)
- James Anthony Seibert
- Department of Radiology, University of California Davis Medical Center, 4860 Y St., Ste. 3100, Sacramento, CA, 95817, USA,
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Low dose CT perfusion in acute ischemic stroke. Neuroradiology 2014; 56:1055-62. [PMID: 25252738 DOI: 10.1007/s00234-014-1434-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/16/2014] [Indexed: 02/04/2023]
Abstract
INTRODUCTION The purpose of this investigation is to determine if CT perfusion (CTP) measurements at low doses (LD = 20 or 50 mAs) are similar to those obtained at regular doses (RD = 100 mAs), with and without the addition of adaptive statistical iterative reconstruction (ASIR). METHODS A single-center, prospective study was performed in patients with acute ischemic stroke (n = 37; 54% male; age = 74 ± 15 years). Two CTP scans were performed on each subject: one at 100 mAs (RD) and one at either 50 or 20 mAs (LD). CTP parameters were compared between the RD and LD scans in regions of ischemia, infarction, and normal tissue. Differences were determined using a within-subjects ANOVA (p < 0.05) followed by a paired t test post hoc analysis (p < 0.01). RESULTS At 50 mAs, there was no significant difference between cerebral blood flow (CBF), cerebral blood volume (CBV), or time to maximum enhancement (Tmax) values for the RD and LD scans in the ischemic, infarcted, or normal contralateral regions (p < 0.05). At 20 mAs, there were significant differences between the RD and LD scans for all parameters in the ischemic and normal tissue regions (p > 0.05). CONCLUSION CTP-derived CBF and CBV are not different at 50 mAs compared to 100 mAs, even without the addition of ASIR. Current CTP protocols can be modified to reduce the effective dose by 50 % without altering CTP measurements.
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Notohamiprodjo S, Deak Z, Meurer F, Maertz F, Mueck FG, Geyer LL, Wirth S. Image quality of iterative reconstruction in cranial CT imaging: comparison of model-based iterative reconstruction (MBIR) and adaptive statistical iterative reconstruction (ASiR). Eur Radiol 2014; 25:140-6. [DOI: 10.1007/s00330-014-3374-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/09/2014] [Accepted: 07/22/2014] [Indexed: 11/30/2022]
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Effect of iterative reconstruction algorithms on peripheral MDCT angiography virtual histology plaque volumes: have we been overestimating disease burden? Clin Imaging 2014; 38:821-5. [PMID: 25069752 DOI: 10.1016/j.clinimag.2014.06.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 06/07/2014] [Accepted: 06/19/2014] [Indexed: 11/22/2022]
Abstract
Our objective was to compare plaque volumes of multidetector computed tomographic images reconstructed using adaptive statistical iterative reconstruction (ASIR), model-based iterative reconstruction (MBIR), and filtered back projection (FBP). We reviewed 25 patients for a total of 50 extremities imaged on the same scanner. Calcified plaque FBP volume (3468.2 ± 2634.8 mm(3)) was higher than ASIR (2548.1 ± 2166.5 mm(3)). Calcified plaque FBP volume was higher than MBIR (mean=2345.7 ± 1935.4 mm(3)). Our findings suggest that traditional FBP methods overestimate disease compared to newer reconstruction methods.
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