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Anhaus JA, Heider M, Killermann P, Hofmann C, Mahnken AH. A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems. Invest Radiol 2024; 59:526-537. [PMID: 38193772 DOI: 10.1097/rli.0000000000001055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
OBJECTIVES The aim of this study was to introduce and evaluate a new metal artifact reduction framework (iMARv2) that addresses the drawbacks (residual artifacts after correction and user preferences for image quality) associated with the current clinically applied iMAR. MATERIALS AND METHODS A new iMARv2 has been introduced, combining the current iMAR with new modular components to remove residual metal artifacts after image correction. The postcorrection image impression is adjustable with user-selectable strength settings. Phantom scans from an energy-integrating and a photon-counting detector CT were used to assess image quality, including a Gammex phantom and anthropomorphic phantoms. In addition, 36 clinical cases (with metallic implants such as dental fillings, hip replacements, and spinal screws) were reconstructed and evaluated in a blinded and randomized reader study. RESULTS The Gammex phantom showed lower HU errors compared with the uncorrected image at almost all iMAR and iMARv2 settings evaluated, with only minor differences between iMAR and the different iMARv2 settings. In addition, the anthropomorphic phantoms showed a trend toward lower errors with higher iMARv2 strength settings. On average, the iMARv2 strength 3 performed best of all the clinical reconstructions evaluated, with a significant increase in diagnostic confidence and decrease in artifacts. All hip and dental cases showed a significant increase in diagnostic confidence and decrease in artifact strength, and the improvements from iMARv2 in the dental cases were significant compared with iMAR. There were no significant improvements in the spine. CONCLUSIONS This work has introduced and evaluated a new method for metal artifact reduction and demonstrated its utility in routine clinical datasets. The greatest improvements were seen in dental fillings, where iMARv2 significantly improved image quality compared with conventional iMAR.
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Affiliation(s)
- Julian A Anhaus
- From the Siemens Healthineers, CT Physics, Forchheim, Germany (J.A.A., M.H., C.H.); Clinic of Diagnostic and Interventional Radiology, Philipps-University Marburg, Marburg, Germany (J.A.A., A.H.M.); and Infoteam Software AG, Bubenreuth, Germany (P.K.)
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Skawran S, Sartoretti T, Gennari AG, Schwyzer M, Sartoretti E, Treyer V, Maurer A, Huellner MW, Waelti S, Messerli M. Evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[ 18F]FDG PET/CT between 2007 and 2021. Br J Radiol 2023; 96:20220482. [PMID: 37751216 PMCID: PMC10646648 DOI: 10.1259/bjr.20220482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023] Open
Abstract
OBJECTIVES To evaluate the evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) PET/CT between 2007 and 2021. METHODS AND MATERIALS Data from all pediatric patients aged 0-18 years who underwent hybrid 2-[18F]FDG PET/CT of the body between January 2007 and May 2021 were reviewed. Demographic and imaging parameters were collected. A board-certified radiologist reviewed all CT scans and measured image noise in the brain, liver, and adductor muscles. RESULTS 294 scans from 167 children (72 females (43%); median age: 14 (IQR 10-15) years; BMI: median 17.5 (IQR 15-20.4) kg/m2) were included. CT dose index-volume (CTDIvol) and dose length product (DLP) both decreased significantly from 2007 to 2021 (both p < 0.001, Spearman's rho coefficients -0.46 and -0.35, respectively). Specifically, from 2007 to 2009 to 2019-2021 CTDIvol and DLP decreased from 2.94 (2.14-2.99) mGy and 309 (230-371) mGy*cm, respectively, to 0.855 (0.568-1.11) mGy and 108 (65.6-207) mGy*cm, respectively. From 2007 to 2021, image noise in the brain and liver remained constant (p = 0.26 and p = 0.06), while it decreased in the adductor muscles (p = 0.007). Peak tube voltage selection (in kilovolt, kV) of CT scans shifted from high kV imaging (140 or 120kVp) to low kV imaging (100 or 80kVp) (p < 0.001) from 2007 to 2021. CONCLUSION CT radiation dose in pediatric patients undergoing hybrid 2-[18F]FDG PET/CT has decreased in recent years equaling approximately one-third of the initial amount. ADVANCES IN KNOWLEDGE Over the past 15 years, CT radiation dose decreased considerably in pediatric patients undergoing hybrid imaging, while objective image quality may not have been compromised.
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Optimized Camera-Based Patient Positioning in CT: Impact on Radiation Exposure. Invest Radiol 2023; 58:126-130. [PMID: 35926075 DOI: 10.1097/rli.0000000000000904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate whether a 3-dimensional (3D) camera can outperform highly trained technicians in precision of patient positioning and whether this transforms into a reduction in patient exposure. MATERIALS AND METHODS In a single-center study, 3118 patients underwent computer tomography (CT) scans of the chest and/or abdomen on a latest generation single-source CT scanner supported with an automated patient positioning system by 3D camera. One thousand five hundred fifty-seven patients were positioned laser-guided by a highly trained radiographer (camera off) and 1561 patients with 3D camera (camera on) guidance. Radiation parameters such as effective dose, organ doses, CT dose index, and dose length product were analyzed and compared. Isocenter accuracy and table height were evaluated between the 2 groups. RESULTS Isocenter positioning was significantly improved with the 3D camera ( P < 0.001) as compared with visual laser-guided positioning. Absolute table height differed significantly ( P < 0.001), being higher with camera positioning (165.6 ± 16.2 mm) as compared with laser-guided positioning (170.0 ± 20.4 mm). Radiation exposure decreased using the 3D camera as indicated by dose length product (321.1 ± 266.6 mGy·cm; camera off: 342.0 ± 280.7 mGy·cm; P = 0.033), effective dose (3.3 ± 2.7 mSv; camera off: 3.5 ± 2.9; P = 0.053), and CT dose index (6.4 ± 4.3 mGy; camera off: 6.8 ± 4.6 mGy; P = 0.011). Exposure of radiation-sensitive organs such as colon ( P = 0.015) and red bone marrow ( P = 0.049) were also lower using the camera. CONCLUSIONS The introduction of a 3D camera improves patient positioning in the isocenter of the scanner, which results in a lower and also better balanced dose reduction for the patients.
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Toia GV, Mileto A, Wang CL, Sahani DV. Quantitative dual-energy CT techniques in the abdomen. Abdom Radiol (NY) 2022; 47:3003-3018. [PMID: 34468796 DOI: 10.1007/s00261-021-03266-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 02/06/2023]
Abstract
Advances in dual-energy CT (DECT) technology and spectral techniques are catalyzing the widespread implementation of this technology across multiple radiology subspecialties. The inclusion of energy- and material-specific datasets has ushered overall improvements in CT image contrast and noise as well as artifacts reduction, leading to considerable progress in radiologists' ability to detect and characterize pathologies in the abdomen. The scope of this article is to provide an overview of various quantitative clinical DECT applications in the abdomen and pelvis. Several of the reviewed applications have not reached mainstream clinical use and are considered investigational. Nonetheless awareness of such applications is critical to having a fully comprehensive knowledge base to DECT and fostering future clinical implementation.
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Affiliation(s)
- Giuseppe V Toia
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, Mailbox 3252, Madison, WI, 53792, USA.
| | - Achille Mileto
- Department of Radiology, Mayo Clinic, 200 First Street, SW, Rochester, MN, 55905, USA
| | - Carolyn L Wang
- Department of Radiology, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA, 98195, USA
| | - Dushyant V Sahani
- Department of Radiology, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA, 98195, USA
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Mussmann B, Hardy M, Jung H, Ding M, Osther PJ, Fransen ML, Greisen PW, Graumann O. Renal stone detection using a low kilo-voltage paediatric CT protocol - a porcine phantom study. J Med Radiat Sci 2021; 68:342-348. [PMID: 34159743 PMCID: PMC8656188 DOI: 10.1002/jmrs.523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 06/03/2021] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Reducing tube voltage is an effective dose saving method in computed tomography (CT) assuming tube current is not concurrently increased. Recent innovations in scanner technology now enable CT tube voltage reduction to 70 kV thereby increasing opportunities for dose reduction in paediatric patients, but it is unclear if the increased image noise associated with 70 kV impacts on ability to visualise renal stones accurately. The purpose was to assess detectability of nephrolithiasis using a bespoke paediatric phantom and low kV, non-contrast CT and to assess inter-observer agreement. METHODS Forty-two renal stones of different size and chemical composition were inserted into porcine kidneys and positioned in a bespoke, water-filled phantom mimicking a 9-year-old child weighing approximately 33kg. The phantom was scanned using 120 and 70 kV CT protocols, and the detectability of the stones was assessed by three radiologists. Absolute agreement and Fleiss' kappa regarding detectability were assessed. RESULTS The mean diameter of renal stones as measured physically was 4.24 mm ranging from 1 to 11 mm. Four stones were missed by at least one observer. One observer had a sensitivity of 93 and 95% at 70 and 120 kV, respectively, while the sensitivity for observers 2 and 3 was 98% at both kV levels. Specificity was 100% across readers and kV levels. Absolute agreement between the readers at 70 kV was 92% (kappa = 0.86) and 98% (kappa = 0.96) at 120 kV indicating a strong agreement at both kV levels. CONCLUSIONS The results suggest that lowering the kV does not affect the detection rate of renal stones and may be a useful dose reduction strategy for assessment of nephrolithiasis in children.
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Affiliation(s)
- Bo Mussmann
- Department of RadiologyOdense University HospitalOdenseDenmark
- Research and Innovation Unit of RadiologyUniversity of Southern DenmarkOdenseDenmark
- Faculty of Health SciencesOslo Metropolitan UniversityOsloNorway
| | - Maryann Hardy
- Research and Innovation Unit of RadiologyUniversity of Southern DenmarkOdenseDenmark
- Faculty of Health StudiesUniversity of BradfordBradfordUK
| | - Helene Jung
- Urological Research CenterDepartment of UrologyLillebaelt HospitalVejleDenmark
- Department of Regional Health ResearchUniversity of Southern DenmarkOdenseDenmark
| | - Ming Ding
- Department of Orthopaedic surgery and traumatologyOdense University HospitalOdenseDenmark
- Department of Clinical ResearchUniversity of Southern DenmarkOdenseDenmark
| | - Palle J. Osther
- Urological Research CenterDepartment of UrologyLillebaelt HospitalVejleDenmark
- Department of Regional Health ResearchUniversity of Southern DenmarkOdenseDenmark
| | | | | | - Ole Graumann
- Department of RadiologyOdense University HospitalOdenseDenmark
- Research and Innovation Unit of RadiologyUniversity of Southern DenmarkOdenseDenmark
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Zhang L, Li L, Feng G, Fan T, Jiang H, Wang Z. Advances in CT Techniques in Vascular Calcification. Front Cardiovasc Med 2021; 8:716822. [PMID: 34660718 PMCID: PMC8511450 DOI: 10.3389/fcvm.2021.716822] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 08/30/2021] [Indexed: 12/17/2022] Open
Abstract
Vascular calcification, a common pathological phenomenon in atherosclerosis, diabetes, hypertension, and other diseases, increases the incidence and mortality of cardiovascular diseases. Therefore, the prevention and detection of vascular calcification play an important role. At present, various techniques have been applied to the analysis of vascular calcification, but clinical examination mainly depends on non-invasive and invasive imaging methods to detect and quantify. Computed tomography (CT), as a commonly used clinical examination method, can analyze vascular calcification. In recent years, with the development of technology, in addition to traditional CT, some emerging types of CT, such as dual-energy CT and micro CT, have emerged for vascular imaging and providing anatomical information for calcification. This review focuses on the latest application of various CT techniques in vascular calcification.
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Affiliation(s)
- Lijie Zhang
- Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Lihua Li
- Department of Pathology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Guoquan Feng
- Department of Radiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Tingpan Fan
- Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Han Jiang
- Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Zhongqun Wang
- Department of Cardiology, Affiliated Hospital of Jiangsu University, Zhenjiang, China
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Petritsch B, Petri N, Weng AM, Petersilka M, Allmendinger T, Bley TA, Gassenmaier T. Photon-Counting Computed Tomography for Coronary Stent Imaging: In Vitro Evaluation of 28 Coronary Stents. Invest Radiol 2021; 56:653-660. [PMID: 33867450 DOI: 10.1097/rli.0000000000000787] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVES The aim of this study was to assess in-stent lumen visibility and quantitative image characteristics of different coronary stents using a novel photon-counting detector (PCD) computed tomography (CT) system in comparison to a state-of-the-art energy-integrating detector (EID) CT scanner. MATERIALS AND METHODS In this in vitro phantom study, 28 different coronary stents ranging from 2.25 to 4.5 mm lumen diameter were expanded into plastic tubes filled with contrast agent. Stent-containing plastic tubes were positioned in a custom-made emulsion-filled phantom, which was inserted into an anthropomorphic phantom simulating a medium-sized patient. Computed tomography scans were acquired parallel to the scanners' z axis using a novel cadmium telluride-based PCD CT system (SOMATOM CountPlus; Siemens Healthcare GmbH, Forchheim Germany), operating in 2 different modes (standard-resolution mode [SR] and ultra-high-resolution [UHR] mode), and a latest generation dual-source EID CT system (SOMATOM Force; Siemens Healthcare GmbH, Forchheim). CTDIvol-matched images were reconstructed with comparable convolution kernels and using the same reconstruction parameters. In-stent lumen visibility (in %), increase in in-stent attenuation (expressed as Δ in-stent CT attenuation), and image noise (in Hounsfield unit) were manually measured. Parts of the image analysis (in-stent lumen visibility) were additionally performed in an automated way. Differences were tested using Wilcoxon signed rank test. RESULTS The best in-stent lumen visibility was achieved with the PCD-UHR mode and the lowest noise levels with the PCD-SR mode. The median in-stent lumen visibility was significantly higher (P < 0.001) with PCD (SR, 66.7%; interquartile range [IQR], 63.3-72.3; UHR, 68.9%; IQR, 64.4-74.4) compared with EID (65.4%; IQR, 62.2-70.4). The Δ in-stent CT attenuation was significantly lower for PCD in both SR (78 HU; IQR, 46-108; P = 0.024) and UHR (85 HU; IQR, 59-113; P = 0.006) compared with EID (108 HU; IQR, 85-126). Image noise was significantly lower (P < 0.001) for PCD-SR (21 HU; IQR, 21-21) compared with EID images (25 HU; IQR, 24-25.0). CONCLUSIONS The PCD provides superior in-stent lumen visibility and quantitative image characteristics when compared with conventional EID.
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Affiliation(s)
| | - Nils Petri
- Internal Medicine I, University Hospital Würzburg, Würzburg
| | - Andreas M Weng
- From the Departments of Diagnostic and Interventional Radiology
| | | | | | - Thorsten A Bley
- From the Departments of Diagnostic and Interventional Radiology
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CT diagnostic reference levels based on clinical indications: results of a large-scale European survey. Eur Radiol 2021; 31:4459-4469. [PMID: 33449177 DOI: 10.1007/s00330-020-07652-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 11/27/2020] [Accepted: 12/18/2020] [Indexed: 01/02/2023]
Abstract
OBJECTIVES The objective of this study was to investigate the feasibility of defining diagnostic reference levels (DRLs) on a European basis for specific clinical indications (CIs), within the context of the European Clinical DRLs (EUCLID) European Commission project. METHODS A prospective, multicenter, industry-independent European study was performed to provide data on 10 CIs (stroke, chronic sinusitis, cervical spine trauma, pulmonary embolism, coronary calcium scoring, coronary angiography, lung cancer, hepatocellular carcinoma, colic/abdominal pain, and appendicitis) via an online survey that included information on patient clinical, technical, and dosimetric parameters. Data from at least 20 patients per CI were requested from each hospital. To establish DRLs, a methodology in line with the International Commission on Radiological Protection (ICRP) Report 135 good practice recommendations was followed. RESULTS Data were collected from 19 hospitals in 14 European countries on 4299 adult patients and 10 CIs to determine DRLs. DRLs differ considerably between sites for the same CI. Differences were attributed mainly to technical protocol and variable number of phases/scan lengths. Stroke and hepatocellular carcinoma were the CIs with the highest DRLs. Coronary calcium scoring had the lowest DRL value. Comparison with published literature was limited, as there was scarce information on DRLs based on CI. CONCLUSIONS This is the first study reporting on feasibility of establishing CT DRLs based on CI using European data. Resulting values will serve as a baseline for comparison with local radiological practice, national authorities when DRLs are set/updated, or as a guideline for local DRL establishment. KEY POINTS • First study reporting on the feasibility of establishing CT diagnostic reference levels based on clinical indication using data collected across Europe. • Only one-fourth of the hospitals had CT machines less than 5 years old. • Large dose variations were observed among hospitals and CT protocols were quite different between hospitals.
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Abstract
Radiation dose in computed tomography (CT) has become a hot topic due to an upward trend in the number of CT procedures worldwide and the relatively high doses associated with these procedures. The main aim of this review article is to provide an overview of the most frequently used metrics for CT radiation dose characterization, discuss their strengths and limitations, and present patient dose assessment methods. Computed tomography dosimetry is still based on a CT dose index (CTDI) measured using 100-mm-long pencil ionization chambers and standard dosimetry phantoms (CTDI100). This dose index is easily measured but has important limitations. Computed tomography dose index underestimates the dose generated by modern CT scanners with wide beam collimation. Manufacturers should report corrected CTDI values in the consoles of CT systems. The size-specific dose estimate has been proposed to provide an estimate of the average dose at the center of the scan volume along the z-axis of a CT scan. Size-specific dose estimate is based on CTDI and conversion factors and, therefore, its calculation incorporates uncertainties associated with the measurement of CTDI. Moreover, the calculation of size-specific dose estimate is straightforward only when the tube current modulation is not activated and when the patient body diameter does not change considerably along the z-axis of the scan. Effective dose can be used to provide typical patient dose values from CT examinations, compare dose between modalities, and communicate radiogenic risks. In practice, effective dose has been used incorrectly, for example, to characterize a CT procedure as a low-dose examination. Organ or tissue doses, not effective doses, are required for assessing the probability of cancer induction in exposed individuals. Monte Carlo simulation is a powerful technique to estimate organ and tissue dose from CT. However, vendors should make available to the research community the required information to model the imaging process of their CT scanners. Personalized dosimetry based on Monte Carlo simulation and patient models allows accurate organ dose estimation. However, it is not user friendly and fast enough to be applied routinely. Future research efforts should involve the development of advanced artificial intelligence algorithms to overcome drawbacks associated with the current equipment-specific and patient-specific dosimetry.
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Affiliation(s)
- John Damilakis
- Received for publication June 30, 2020; and accepted for publication, after revision, August 18, 2020. From the Department of Medical Physics, School of Medicine, University of Crete, Crete, Greece
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Panetta D, Gabelloni M, Faggioni L, Pelosi G, Aringhieri G, Caramella D, Salvadori PA. Cardiac Computed Tomography Perfusion: Contrast Agents, Challenges and Emerging Methodologies from Preclinical Research to the Clinics. Acad Radiol 2021; 28:e1-e13. [PMID: 32220550 DOI: 10.1016/j.acra.2019.12.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/20/2019] [Accepted: 12/24/2019] [Indexed: 12/19/2022]
Abstract
Computed Tomography (CT) has long been regarded as a purely anatomical imaging modality. Recent advances on CT technology and Contrast Agents (CA) in both clinical and preclinical cardiac imaging offer opportunities for the use of CT in functional imaging. Combined with modern ECG-gating techniques, functional CT has now become a reality allowing a comprehensive evaluation of myocardial global and regional function, perfusion and coronary angiography. This article aims at reviewing the current status of cardiac CT perfusion and micro-CT perfusion with established and experimental scanners and contrast agents, from clinical practice to the experimental domain of investigations based on animal models of heart diseases.
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Precise and Automatic Patient Positioning in Computed Tomography: Avatar Modeling of the Patient Surface Using a 3-Dimensional Camera. Invest Radiol 2019; 53:641-646. [PMID: 29762259 DOI: 10.1097/rli.0000000000000482] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate the accuracy of a 3-dimensional (3D) camera algorithm for automatic and individualized patient positioning based on body surface detection and to compare the results of the 3D camera with manual positioning performed by technologists in routinely obtained chest and abdomen computed tomography (CT) examinations. MATERIALS AND METHODS This study included data of 120 patients undergoing clinically indicated chest (n = 68) and abdomen (n = 52) CT. Fifty-two of the patients were scanned with CT using a table height manually selected by technologists; 68 patients were automatically positioned with the 3D camera, which is based on patient-specific body surface and contour detection. The ground truth table height (TGT) was defined as the table height that aligns the axial center of the patient's body region in the CT scanner isocenter. Off-centering was defined as the difference between the ground truth table height (TGT) and the actual table position used in all CT examinations. The t test was performed to determine significant differences in the vertical offset between automatic and manual positioning. The χ test was used to check whether there was a relationship between patient size and the magnitude of off-centering. RESULTS We found a significant improvement in patient centering (offset 5 ± 3 mm) when using the automatic positioning algorithm with the 3D camera compared with manual positioning (offset 19 ± 10 mm) performed by technologists (P < 0.005). Automatic patient positioning based on the 3D camera reduced the average offset in vertical table position from 19 mm to 7 mm for chest and from 18 mm to 4 mm for abdomen CT. The absolute maximal offset was 39 mm and 43 mm for chest and abdomen CT, respectively, when patients were positioned manually, whereas with automatic positioning using the 3D camera the offset never exceeded 15 mm. In chest CT performed with manual patient positioning, we found a significant correlation between vertical offset greater than 20 mm and patient size (body mass index, >26 kg/m, P < 0.001). In contrast, no such relationship was found for abdomen CT (P = 0.38). CONCLUSIONS Automatic individualized patient positioning using a 3D camera allows for accurate patient centering as compared with manual positioning, which improves radiation dose utilization.
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Mackin D, Ger R, Gay S, Dodge C, Zhang L, Yang J, Jones AK, Court L. Matching and Homogenizing Convolution Kernels for Quantitative Studies in Computed Tomography. Invest Radiol 2019; 54:288-295. [PMID: 30570504 PMCID: PMC6449212 DOI: 10.1097/rli.0000000000000540] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The sharpness of the kernels used for image reconstruction in computed tomography affects the values of the quantitative image features. We sought to identify the kernels that produce similar feature values to enable a more effective comparison of images produced using scanners from different manufactures. We also investigated a new image filter designed to change the kernel-related component of the frequency spectrum of a postreconstruction image from that of the initial kernel to that of a preferred kernel. A radiomics texture phantom was imaged using scanners from GE, Philips, Siemens, and Toshiba. Images were reconstructed multiple times, varying the kernel from smooth to sharp. The phantom comprised 10 cartridges of various textures. A semiautomated method was used to produce 8 × 2 × 2 cm regions of interest for each cartridge and for all scans. For each region of interest, 38 radiomics features from the categories intensity direct (n = 12), gray-level co-occurrence matrix (n = 21), and neighborhood gray-tone difference matrix (n = 5) were extracted. We then calculated the fractional differences of the features from those of the baseline kernel (GE Standard). To gauge the importance of the differences, we scaled them by the coefficient of variation of the same feature from a cohort of patients with non-small cell lung cancer. The noise power spectra for each kernel were estimated from the phantom's solid acrylic cartridge, and kernel-homogenization filters were developed from these estimates. The Philips C, Siemens B30f, and Toshiba FC24 kernels produced feature values most similar to GE Standard. The kernel homogenization filters reduced the median differences from baseline to less than 1 coefficient of variation in the patient population for all of the GE, Philips, and Siemens kernels except for GE Edge and Toshiba kernels. For prospective computed tomographic radiomics studies, the scanning protocol should specify kernels that have been shown to produce similar feature values. For retrospective studies, kernel homogenization filters can be designed and applied to reduce the kernel-related differences in the feature values.
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Affiliation(s)
- Dennis Mackin
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Rachel Ger
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Skylar Gay
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Cristina Dodge
- Department of Diagnostic Imaging, Texas Children’s Hospital, Houston, TX 77030, USA
| | - Lifei Zhang
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jinzhong Yang
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - A. Kyle Jones
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Radiation Oncology Department, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Laurence Court
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Paolicchi F, Bastiani L, Negri J, Caramella D. Effect of CT Localizer Radiographs on Radiation Dose Associated With Automatic Tube Current Modulation: A Multivendor Study. Curr Probl Diagn Radiol 2019; 49:34-41. [PMID: 30704769 DOI: 10.1067/j.cpradiol.2018.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/15/2018] [Accepted: 12/31/2018] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To assess the influence of the CT localizer radiograph on the automatic tube current modulation system of 7 CT scanners produced by 4 different CT manufacturers. METHODS The influence of the localizer orientation, table height, tube current and tube potential values on the radiation dose of the related CT scan were evaluated. Images were acquired by using an anthropomorphic phantom positioned in the CT gantry isocenter as well as from -6 cm to +6 cm vertically to the isocenter. RESULTS Vertical movement of the CT table height affected the radiation dose in all scanners using anterior-posterior or a posterior-anterior localizer orientation albeit differently, depending on the manufacturer; only in 1/7 scanner no influence was observed. The latero-lateral localizer orientation proved to be more effective in limiting the influence of the vertical miscentering in all scanners. Changing localizer's tube voltage influenced the scan radiation dose in scanners produced by two manufacturers, while no significant effect was observed in scanners produced by the other two manufacturers. No significant dose variation was observed in 6/7 scanners when changing the localizer's tube current. CONCLUSION Localizer radiograph shows a significant influence on the radiation exposure but with different outcomes depending on the manufacturer of the CT scanner. Radiologists and radiographers should have a thorough understanding of these differences to assure patients the best examination in terms of radiation dose and image quality.
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Affiliation(s)
- Fabio Paolicchi
- Department of Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy.
| | - Luca Bastiani
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Jacopo Negri
- Department of Radiology, Macerata General Hospital, Macerata, Italy
| | - Davide Caramella
- Department of Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy
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Impact of Contrast Media Concentration on Low-Kilovolt Computed Tomography Angiography. Invest Radiol 2018; 53:264-270. [DOI: 10.1097/rli.0000000000000437] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Abstract
Progressive technological advancements in imaging have significantly improved the preoperative sensitivity for the detection of very small foci of regionally- or hematogenously-metastatic colorectal cancer. Unfortunately, this information has not translated to continued linear gains in patient survival, and might even result in the false-positive upstaging of some cases: these are two conundrums in the imaging of colorectal cancer. Both conundrums might be resolved by the widespread use of real-time imaging guidance during operative procedures. This might open the way for the widespread use of fluorodeoxyglucose PET/CT for the initial staging of patients with colorectal cancer.
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Affiliation(s)
- Nathan C Hall
- Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA; Diagnostic Imaging, Nuclear Medicine, Corporal Michael J. Crescenz VA Medical Center, 3900 Woodland Avenue, Philadelphia, PA 19104, USA; Department of Surgery, Division of Surgical Oncology, The Ohio State University Wexner Medical Center, 410 West 10th Avenue, Columbus, OH 43210, USA.
| | - Alexander T Ruutiainen
- Diagnostic Radiology, Corporal Michael J. Crescenz VA Medical Center, 3900 Woodland Avenue, Philadelphia, PA 19104, USA
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The Left Atrio-Vertebral Ratio: a new simple means for assessing left atrial enlargement on Computed Tomography. Eur Radiol 2017; 28:1310-1317. [PMID: 28956130 DOI: 10.1007/s00330-017-5041-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 08/12/2017] [Accepted: 08/17/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE The purpose of this study is to describe a new method to quickly estimate left atrial enlargement (LAE) on Computed Tomography. METHODS Left atrial (LA) volume was assessed with a 3D-threshold Hounsfield unit detection technique, including left atrial appendage and excluding pulmonary venous confluence, in 201 patients with ECG-gated 128-slice dual-source CT and indexed to body surface area. LA and vertebral axial diameter and area were measured at the bottom level of the right inferior pulmonary vein ostium. Ratio of LA diameter and surface on vertebra (LAVD and LAVA) were compared to LA volume. In accordance with the literature, a cutoff value of 78 ml/m2 was chosen for maximal normal LA volume. RESULTS 18% of LA was enlarged. The best cutoff values for LAE assessment were 2.5 for LAVD (AUC: 0.65; 95% CI: 0.58-0.73; sensitivity: 57%; specificity: 71%), and 3 for LAVA (AUC: 0.78; 95% CI: 0.72-0.84; sensitivity: 67%; specificity: 79%), with higher accuracy for LAVA (P=0.015). Inter-observer and intra-observer variability were either good or excellent for LAVD and LAVA (respective intraclass coefficients: 0.792 and 0.910; 0.912 and 0.937). CONCLUSION A left atrium area superior to three times the vertebral area indicates LAE with high specificity. KEY POINTS • Left atrial enlargement is a frequent condition associated with poor cardiac outcome. • Left atrial enlargement is highly time-consuming to diagnose on CT. • The left atrio-vertebral ratio quickly assesses left atrial enlargement. • A left atrial area > three times vertebral area is highly specific.
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Symons R, Pourmorteza A, Sandfort V, Ahlman MA, Cropper T, Mallek M, Kappler S, Ulzheimer S, Mahesh M, Jones EC, Malayeri AA, Folio LR, Bluemke DA. Feasibility of Dose-reduced Chest CT with Photon-counting Detectors: Initial Results in Humans. Radiology 2017; 285:980-989. [PMID: 28753389 DOI: 10.1148/radiol.2017162587] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Purpose To investigate whether photon-counting detector (PCD) technology can improve dose-reduced chest computed tomography (CT) image quality compared with that attained with conventional energy-integrating detector (EID) technology in vivo. Materials and Methods This was a HIPAA-compliant institutional review board-approved study, with informed consent from patients. Dose-reduced spiral unenhanced lung EID and PCD CT examinations were performed in 30 asymptomatic volunteers in accordance with manufacturer-recommended guidelines for CT lung cancer screening (120-kVp tube voltage, 20-mAs reference tube current-time product for both detectors). Quantitative analysis of images included measurement of mean attenuation, noise power spectrum (NPS), and lung nodule contrast-to-noise ratio (CNR). Images were qualitatively analyzed by three radiologists blinded to detector type. Reproducibility was assessed with the intraclass correlation coefficient (ICC). McNemar, paired t, and Wilcoxon signed-rank tests were used to compare image quality. Results Thirty study subjects were evaluated (mean age, 55.0 years ± 8.7 [standard deviation]; 14 men). Of these patients, 10 had a normal body mass index (BMI) (BMI range, 18.5-24.9 kg/m2; group 1), 10 were overweight (BMI range, 25.0-29.9 kg/m2; group 2), and 10 were obese (BMI ≥30.0 kg/m2, group 3). PCD diagnostic quality was higher than EID diagnostic quality (P = .016, P = .016, and P = .013 for readers 1, 2, and 3, respectively), with significantly better NPS and image quality scores for lung, soft tissue, and bone and with fewer beam-hardening artifacts (all P < .001). Image noise was significantly lower for PCD images in all BMI groups (P < .001 for groups 1 and 3, P < .01 for group 2), with higher CNR for lung nodule detection (12.1 ± 1.7 vs 10.0 ± 1.8, P < .001). Inter- and intrareader reproducibility were good (all ICC > 0.800). Conclusion Initial human experience with dose-reduced PCD chest CT demonstrated lower image noise compared with conventional EID CT, with better diagnostic quality and lung nodule CNR. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Rolf Symons
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Amir Pourmorteza
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Veit Sandfort
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Mark A Ahlman
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Tracy Cropper
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Marissa Mallek
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Steffen Kappler
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Stefan Ulzheimer
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Mahadevappa Mahesh
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Elizabeth C Jones
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Ashkan A Malayeri
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - Les R Folio
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
| | - David A Bluemke
- From the Department of Radiology and Imaging Sciences, National Institutes of Health Clinical Center, 10 Center Dr, Bethesda, MD 20892 (R.S., A.P., V.S., M.A.A., T.C., M. Mallek, E.C.J., A.A.M., L.R.F., D.A.B.); Siemens Healthcare, Forchheim, Germany (S.K., S.U.); and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Md (M. Mahesh)
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Lell MM, Fleischmann U, Pietsch H, Korporaal JG, Haberland U, Mahnken AH, Flohr TG, Uder M, Jost G. Relationship between low tube voltage (70 kV) and the iodine delivery rate (IDR) in CT angiography: An experimental in-vivo study. PLoS One 2017; 12:e0173592. [PMID: 28319203 PMCID: PMC5358883 DOI: 10.1371/journal.pone.0173592] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 02/23/2017] [Indexed: 02/07/2023] Open
Abstract
Objective Very short acquisition times and the use of low-kV protocols in CTA demand modifications in the contrast media (CM) injection regimen. The aim of this study was to optimize the use of CM delivery parameters in thoraco-abdominal CTA in a porcine model. Materials and methods Six pigs (55–68 kg) were examined with a dynamic CTA protocol (454 mm scan length, 2.5 s temporal resolution, 70 s total acquisition time). Four CM injection protocols were applied in a randomized order. 120 kV CTA protocol: (A) 300 mg iodine/kg bodyweight (bw), IDR = 1.5 g/s (flow = 5 mL/s), injection time (ti) 12 s (60 kg bw). 70 kV CTA protocols: 150 mg iodine/kg bw: (B) IDR = 0.75 g/s (flow = 2.5 mL/s), ti = 12 s (60 kg bw); (C) IDR = 1.5 g/s (flow = 5 mL/s), ti = 12 s (60 kg bw); (D) IDR = 3.0 g/s (flow = 10 mL/s), ti = 3 s (60 kg bw). The complete CM bolus shape was monitored by creating time attenuation curves (TAC) in different vascular territories. Based on the TAC, the time to peak (TTP) and the peak enhancement were determined. The diagnostic window (relative enhancement > 300 HU), was calculated and compared to visual inspection of the corresponding CTA data sets. Results The average relative arterial peak enhancements after baseline correction were 358.6 HU (A), 356.6 HU (B), 464.0 HU (C), and 477.6 HU (D). The TTP decreased with increasing IDR and decreasing ti, protocols A and B did not differ significantly (systemic arteries, p = 0.843; pulmonary arteries, p = 0.183). The delay time for bolus tracking (trigger level 100 HU; target enhancement 300 HU) for single-phase CTA was comparable for protocol A and B (3.9, 4.3 s) and C and D (2.4, 2.0 s). The scan window time frame was comparable for the different protocols by visual inspection of the different CTA data sets and by analyzing the TAC. Conclusions All protocols provided sufficient arterial enhancement. The use of a 70 kV CTA protocol is recommended because of a 50% reduction of total CM volume and a 50% reduced flow rate while maintaining the bolus profile. In contrast to pulmonary arterial enhancement, the systemic arterial enhancement improved only slightly increasing the IDR from 1.5 g/s to 3 g/s because of bolus dispersion of the very short bolus (3s) in the lungs.
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Affiliation(s)
- Michael M. Lell
- Department of Radiology and Nuclear Medicine, Paracelsus Medical University, Nuernberg, Germany
- * E-mail:
| | - Ulrike Fleischmann
- Department of Radiology, Friedrich-Alexander University Erlangen, Erlangen, Germany
| | - Hubertus Pietsch
- MR and CT Contrast Media Research, Bayer Healthcare, Berlin, Germany
| | | | | | | | | | - Michael Uder
- Department of Radiology and Nuclear Medicine, Paracelsus Medical University, Nuernberg, Germany
- Imaging Science Institute (ISI) Erlangen, Erlangen, Germany
| | - Gregor Jost
- MR and CT Contrast Media Research, Bayer Healthcare, Berlin, Germany
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High-Pitch Low-Dose Whole-Body Computed Tomography for the Assessment of Ventriculoperitoneal Shunts in a Pediatric Patient Model: An Experimental Ex Vivo Study in Rabbits. Invest Radiol 2016; 50:858-62. [PMID: 26284435 DOI: 10.1097/rli.0000000000000195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE The aim of this study was to assess the diagnostic value of whole-body low-dose (LD) computed tomography (CT) for the detection of ventriculoperitoneal (VP) shunt complications in pediatric patients compared with radiographic shunt series (SS) in an ex vivo rabbit animal model. METHODS In the first step, 2 optimized LD-CT imaging protocols, with high pitch (pitch, 3.2), low tube voltages (70 kVp and 80 kVp), and using both filtered back projection and iterative reconstruction, were assessed on a 16-cm solid polymethylmethacrylate phantom regarding signal-to-noise ratio and radiation dose. Taking both radiation dose and signal-to-noise ratio into account, the LD-CT protocol (80 kVp; 4 mA; pitch, 3.2) was identified as most appropriate and therefore applied in this study.After identification of appropriate LD-CT protocol, 12 VP shunts were implanted in 6 rabbit cadavers (mean weight, 5.1 kg). Twenty-four mechanical complications (extracranial and extraperitoneal malpositioning, breakages, and disconnections) were induced in half of the VP shunts. Low-dose CT and conventional SS were acquired in standard fashion. Dose-area products (DAPs) for SS and LD-CT were collected; effective radiation doses for both SS and LD-CT were estimated using CT-Expo (v. 2.3.1.) and age-specific effective dose (ED) estimates. Qualitative scoring of diagnostic confidence on a 5-point Likert scale (1, very low diagnostic confidence; 5, excellent diagnostic confidence) and blinded readings of both SS and LD-CTs were performed. RESULTS Among the 24 VP shunt complications, LD-CT yielded excellent sensitivity and specificity for the detection of VP shunt complications (sensitivity, 0.98; specificity, 1; 95% confidence interval, 0.92-1) with excellent interobserver agreement (κ = 0.90). Shunt series yielded good sensitivity and specificity (sensitivity, 0.75; specificity, 1; 95% confidence interval, 0.58-0.92) with moderate interobserver agreement (κ = 0.56). No false-positive findings were registered. Compared with SS, LD-CT yielded significantly lower ED and DAPs (ED, 0.039 vs 0.062 mSv; DAP, 20.5 vs 26.3; P < 0.05). CONCLUSIONS In this experimental ex vivo pediatric patient model, LD-CT yields excellent sensitivity for the detection of VP shunt complications at higher diagnostic confidence and lower radiation exposure compared with SS.
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Comprehensive Comparison of Virtual Monoenergetic and Linearly Blended Reconstruction Techniques in Third-Generation Dual-Source Dual-Energy Computed Tomography Angiography of the Thorax and Abdomen. Invest Radiol 2016; 51:582-90. [DOI: 10.1097/rli.0000000000000272] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Influence of IV Contrast Administration on CT Measures of Muscle and Bone Attenuation: Implications for Sarcopenia and Osteoporosis Evaluation. AJR Am J Roentgenol 2016; 207:1046-1054. [PMID: 27556335 DOI: 10.2214/ajr.16.16387] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE The objective of our study was to characterize enhancement of muscle and bone that occurs on standardized four-phase contrast-enhanced CT. MATERIALS AND METHODS Two musculoskeletal radiologists reviewed standardized four-phase abdominal CT scans obtained with IV contrast material. The psoas area was measured, and the mean attenuation (in Hounsfield units) was recorded for the aorta, psoas muscles, posterior paraspinal muscles, and L4 vertebral body. CT attenuation measures were compared between anatomic regions and imaging phases with the paired t test; associations between measures were examined with the Pearson correlation coefficient (R). RESULTS The study included 201 patients (97 men, 104 women; mean age, 57.7 ± 12.5 [SD] years). Subject age was inversely correlated with unenhanced attenuation in the psoas muscles, posterior paraspinal muscles, and L4 (p < 0.001). The psoas muscles, posterior paraspinal muscles, and L4 enhanced significantly (p < 0.001) at all three contrast-enhanced phases. The greatest muscle enhancement was observed on delayed phase scans, whereas the greatest enhancement in L4 was seen on portal phase imaging. The unenhanced attenuation of the psoas muscles was significantly and negatively correlated with enhancement of the psoas muscles at the portal and delayed phases (p < 0.05 and p < 0.01, respectively), but these correlations were not seen for the posterior paraspinal muscles. Age was positively correlated with posterior paraspinal muscle enhancement at the portal and delayed phases in men (p < 0.05 and p < 0.01, respectively) but not in women. CONCLUSION Contrast enhancement of commonly measured muscle and bone regions is routinely observed and should be considered when using CT attenuation values as biomarkers of sarcopenia and osteoporosis. Furthermore, CT enhancement may be significantly influenced by age, sex, and unenhanced tissue attenuation.
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Application of an Advanced Image-Based Virtual Monoenergetic Reconstruction of Dual Source Dual-Energy CT Data at Low keV Increases Image Quality for Routine Pancreas Imaging. J Comput Assist Tomogr 2015. [PMID: 26196343 DOI: 10.1097/rct.0000000000000276] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To compare image quality on contrast-enhanced dual-energy computed tomography (DECT) during the pancreatic parenchymal phase of pancreatic masses between linearly-blended simulated 120 kVp images (routine) and advanced image-based virtual monoenergetic reconstructions at 55 keV. METHODS This was a retrospective evaluation of 24 nonconsecutive adults found to have a focal pancreatic mass on a multiphasic abdominal dual-source DECT (12 adenocarcinoma, 5 neuroendocrine, 7 cystic tumors). For pancreatic-parenchymal phase images, subjects had routine and 55 keV images reconstructed at the time of clinical evaluation. Quantitative evaluation by contrast-to-noise ratio and qualitative evaluations of image quality by (1) direct comparison of image pairs (preference) and (2) blinded assessment of image quality measures based on Likert scores were performed. RESULTS Mean patient weight was 205.8 ± 26.6 lbs. Mean pancreatic lesion contrast-to-noise ratio was significantly higher at 55 keV (6.8 ± 4.1) compared to the routine image series (5.8 ± 3.8; P = 0.0002). All 3 readers preferred the 55-keV images over routine blended images in 70.1% to 95.8% of cases. No significant differences were observed for subjective sharpness of the mass, visualization of internal mass structures, or image noise. CONCLUSIONS Use of a single advanced image-based virtual monoenergetic reconstruction at 55 keV in pancreatic DECT showed improved objective image quality and reader preference compared to routine images. As this image reconstruction can be incorporated into the scan protocol, this technique should be considered for routine clinical use.
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