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Chatzaraki V, Kubik-Huch RA, Thali M, Niemann T. Quantifying image quality in chest computed tomography angiography: Evaluation of different contrast-to-noise ratio measurement methods. Acta Radiol 2021; 63:1353-1362. [PMID: 34647842 DOI: 10.1177/02841851211041813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Contrast-to-noise ratio is used to objectively evaluate image quality in chest computed tomography angiography (CTA). Different authors define and measure contrast-to-noise ratio using different methods. PURPOSE To summarize and evaluate the different contrast-to-noise ratio calculation formulas in the current literature. MATERIAL AND METHODS A systematic review of the recent literature for studies using contrast-to-noise ratio was performed. Contrast-to-noise ratio measurement methods reported by the different authors were recorded and reproduced in three patients who underwent chest CTA in our department for exploring variations among the different measurement methods. RESULTS The search resulted in 109 articles, of which 26 were included. The studies involved 69 different measurements and overall, three different formula patterns. In all three, aorta and pulmonary arteries comprised the objects of interest in the numerator. In the denominator, standard deviation of the attenuation of the object of interest itself or of another background were used to reflect image noise. Some authors averaged the ratio values at different levels to obtain global ratio values. Using the object of interest itself for image noise calculation in the denominator compared to the usage of another background caused the most prominent variances of contrast-to-noise ratio between the two different protocols used for the reproduction of the measurements. CONCLUSION We recommend using the standard deviation of the attenuation of a background indicator as image noise rather than the object of interest itself for more reliable and comparative values. Global contrast-to-noise ratios based on averaging the values of different measurement levels should be avoided.
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Affiliation(s)
- Vasiliki Chatzaraki
- Institute of Radiology, Kantonsspital Baden, Baden, Switzerland
- Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | | | - Michael Thali
- Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Tilo Niemann
- Institute of Radiology, Kantonsspital Baden, Baden, Switzerland
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Solbak MS, Henning MK, England A, Martinsen AC, Aaløkken TM, Johansen S. Impact of iodine concentration and scan parameters on image quality, contrast enhancement and radiation dose in thoracic CT. Eur Radiol Exp 2020; 4:57. [PMID: 32915405 PMCID: PMC7486352 DOI: 10.1186/s41747-020-00184-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/12/2020] [Indexed: 12/11/2022] Open
Abstract
Background We investigated the impact of varying contrast medium (CM) densities and x-ray tube potentials on contrast enhancement (CE), image quality and radiation dose in thoracic computed tomography (CT) using two different scanning techniques. Methods Seven plastic tubes containing seven different CM densities ranging from of 0 to 600 HU were positioned inside a commercial chest phantom with padding, representing three different patient sizes. Helical scans of the phantom in single-source mode were obtained with varying tube potentials from 70 to 140 kVp. A constant volume CT dose index (CTDIvol) depending on phantom size and automatic dose modulation was tested. CE (HU) and image quality (contrast-to-noise ratio, CNR) were measured for all combinations of CM density and tube potential. A reference threshold of CE and kVp was defined as ≥ 200 HU and 120 kVp. Results For the medium-sized phantom, with a specific CE of 100–600 HU, the diagnostic CE (200 HU) at 70 kVp was ~ 90% higher than at 120 kVp, for both scan techniques (p < 0.001). Changes in CM density/specific HU together with lower kVp resulted in significantly higher CE and CNR (p < 0.001). When changing only the kVp, no statistically significant differences were observed in CE or CNR (p ≥ 0.094), using both dose modulation and constant CTDIvol. Conclusions For thoracic CT, diagnostic CE (≥ 200 HU) and maintained CNR were achieved by using lower CM density in combination with lower tube potential (< 120 kVp), independently of phantom size.
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Affiliation(s)
- Marian S Solbak
- Faculty of Health Sciences, Oslo Metropolitan University, Pilestredet 48, 0130, Oslo, Norway
| | - Mette K Henning
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway
| | - Andrew England
- School of Allied Health Professions, Keele University, Staffordshire, England
| | - Anne C Martinsen
- Faculty of Health Sciences, Oslo Metropolitan University, Pilestredet 48, 0130, Oslo, Norway.,Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway
| | - Trond M Aaløkken
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway.,Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Safora Johansen
- Faculty of Health Sciences, Oslo Metropolitan University, Pilestredet 48, 0130, Oslo, Norway. .,Department of Cancer Treatment, Oslo University Hospital, Oslo, Norway.
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Werner S, Bez C, Hinterleitner C, Horger M. Incidence of contrast-induced acute kidney injury (CI-AKI) in high-risk oncology patients undergoing contrast-enhanced CT with a reduced dose of the iso-osmolar iodinated contrast medium iodixanol. PLoS One 2020; 15:e0233433. [PMID: 32437415 PMCID: PMC7241755 DOI: 10.1371/journal.pone.0233433] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 05/05/2020] [Indexed: 12/18/2022] Open
Abstract
Objectives To determine the incidence of post-contrast acute kidney injury (PC-AKI) and presumed contrast-induced acute kidney injury (CI-AKI) following contrast-enhanced CT (CECT) with intravenous application of a reduced dose of the iso-osmolar contrast agent iodixanol in cancer patients with chronic kidney disease. Methods 198 oncology patients with a baseline estimated glomerular filtration rate (eGFR) <60ml/min/1.73m2 undergoing a total of 237 CECTs using a reduced dose of 60ml iodixanol were retrospectively analyzed. Statistical analysis was performed for the entire cohort and subgroups. The effect of additional risk factors on the occurrence of PC-AKI was evaluated. Results The overall PC-AKI incidence was 6.3%. Excluding patients with concurrent medical conditions known to directly and independently impact kidney function and patients with AKI preceding the CT-scan resulted in a presumed CI-AKI incidence of 3.8%. No permanent post-contrast worsening of renal function and no AKI treatment were required. Subgroups considering baseline eGFR yielded PC-AKI incidences of 4.6% (eGFR 45-60ml/min/1.73m2, n = 130), 7.4% (eGFR 30-45ml/min/1.73m2, n = 95) and 16.7% (eGFR <30ml/min/1.73m2, n = 12). Additional patient related risk factors did not show any significant effect on the occurrence of PC-AKI. Conclusions Low incidences of PC-AKI/CI-AKI suggest that a reduced dose of an iso-osmolar contrast agent is safe in high-risk oncological patients with impaired renal function.
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Affiliation(s)
- Sebastian Werner
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
- * E-mail:
| | - Christian Bez
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Clemens Hinterleitner
- Department of Internal Medicine II–Haematology, Oncology, Clinical Immunology and Rheumatology, University Hospital Tübingen, Tübingen, Germany
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
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Hsiao CC, Chen PC, Kuo PC, Ho CH, Jao JC. Assessment of image quality and dose in contrast-enhanced head and neck CT angiography of New Zealand rabbit. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2020; 28:739-750. [PMID: 32597826 DOI: 10.3233/xst-200669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
BACKGROUND Although computed tomography (CT) is a powerful diagnostic imaging modality for diagnosing vascular diseases, it is some what risky to human health due to the high radiation dosage. Thus, CT vendors have developed low dose computed tomography (LDCT) aiming to solve this problem. Nowadays, LDCT has gradually become a main stream of CT examination. OBJECTIVE This study aimed to assess the feasibility of LDCTAin an animal model and compare the imaging features and doses in two clinical scanners. METHODS Twenty-two New Zealand rabbit head and neck CTA images pre- and post-contrast agent injection were performed using256-sliceand 64-slice CT scanners. The tube voltages used in the 256-slice and the 64-slice CTA were 70 kVp and 80 kVp, respectively. Quantitative images indices and radiation doses obtained from CTA in these two scanners were compared. RESULTS More neck arterial vessels could be visualized in multi-planar reconstruction (MPR) CTA on the 256-slice CT scanner than on the 64-slice CT scanner. After contrast agent injection, all observed neck arterial vessels had higher CT numbers in 256-slice CTA than in 64-slice CTA. There was no significant difference in contrast-to-noise (CNR) of CTA images between these two scanners. CT dose index (CTDI) and dose length product (DLP) for the 256-slice CTA were lower than those for the 64-slice CTA. CONCLUSIONS Low dose CTA of rabbits with 70 or 80 kVp is feasible in a 256-slice or a 64-slice CT scanner. The radiation dose from the 256-slice CTA was much lower than that from the 64-slice CTA with comparable SNR and CNR. The technique can be further applied in longitudinal monitoring of an animal stroke model in the future.
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Affiliation(s)
- Chia-Chi Hsiao
- Department of Radiology, Kaohsiung Veterans General Hospital, Taiwan, R.O.C
| | - Po-Chou Chen
- Department of Biomedical Engineering, I-Shou University, Taiwan, R.O.C
| | - Pei-Chi Kuo
- Department of Biomedical Engineering, I-Shou University, Taiwan, R.O.C
| | - Chih-Hao Ho
- Department of Medical Imaging, Taipei City Hospital (Yangming Branch), Taiwan, R.O.C
| | - Jo-Chi Jao
- Department of Medical Imaging and Radiological Sciences, College of Health Sciences, Kaohsiung Medical University, Taiwan, R.O.C
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Aortic CT angiography using the double region of interest timing bolus technique: feasibility of 80 kVp scanning in lean patients. Int J Cardiovasc Imaging 2019; 35:2113-2121. [DOI: 10.1007/s10554-019-01660-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/26/2019] [Indexed: 12/27/2022]
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Mousavi Gazafroudi SS, Tavakkoli MB, Moradi M, Mousavi Gazafroudi SS, Yadegarfar G, Behjati M, Karimian M, Sajjadieh Khajouei A. Coronary CT angiography by modifying tube voltage and contrast medium concentration: Evaluation of image quality and radiation dose. Echocardiography 2019; 36:1391-1396. [PMID: 31215700 DOI: 10.1111/echo.14410] [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: 04/05/2019] [Revised: 05/22/2019] [Accepted: 05/26/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Currently, there is an increasing interest in noninvasive imaging of cardiovascular system such as computed tomography coronary angiography (CCTA). The risks of radiation-induced cancer and contrast-induced nephropathy (CIN) have always been regarded as concerns which increased demand for CCTA using reduced radiation dose and iodine intake. We aimed to evaluate the image quality and radiation dose of CCTA by modifying tube voltage and concentration of contrast media. METHODS The present study includes 105 patients who underwent CCTA for clinical indications. Specific inclusion and exclusion criteria in terms of patient's weight, body mass index, calcium score, and stenting were used. First group of patients scanned by 120 kV and 370 mg I/mL contrast medium, compared with second and third groups for which scanning was performed using 100 kV and 370 mg I/mL and 100 kV and 300 mg I/mL, respectively. Image quality was evaluated both subjectively and objectively. The effective dose and iodine intake were also measured. RESULTS Using low kV protocols led to radiation dose reduction up to 38% and applying low contrast medium concentration with consequent reduced iodine intake up to 21%. Moreover, there were significant differences in image quality of new scanning protocols. CONCLUSION Reduction in tube voltage with lowering of contrast medium concentration can reduce radiation dose and iodine intake with acceptable image quality.
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Affiliation(s)
| | | | - Maryam Moradi
- Radiology Department, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | - Ghasem Yadegarfar
- Epidemiology Department, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohaddeseh Behjati
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Karimian
- Anatomical Sciences Research Center, Kashan University of Medical Sciences, Kashan, Iran
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Double ROI Timing Bolus Technique to Perform Aortic CT Angiography With a 9-Second Contrast Injection Duration. AJR Am J Roentgenol 2019; 213:96-103. [PMID: 30917025 DOI: 10.2214/ajr.18.20766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE. The purpose of this study was to investigate the feasibility of a double ROI timing bolus technique for performing aortic CT angiography (CTA) with 40 mL of contrast medium over 9 seconds. SUBJECTS AND METHODS. A prospective study from February to July 2018 included 106 patients with clinical indications for evaluation of aortic aneurysm or dissection or suspected aortic disease. Forty-seven of these patients had undergone prior aortic CTA by the conventional method. The scanning speed for the double ROI timing bolus technique was calculated from the time-attenuation curves of the ascending and descending aorta by use of the timing bolus data to synchronize aortic flow. The conventional scan was obtained by injection of 1.7 mL of contrast medium per kilogram of body weight for 25 seconds. Enhancement of six points on the aortoiliac arteries and superior vena cava was measured. The t test was used to compare the values. RESULTS. Use of the double ROI timing bolus method significantly reduced the amount of contrast medium injected compared with the amount for the conventional method (40.0 mL vs 88.0 ± 9.4 mL, p < 0.001). Use of the method significantly increased aortoiliac enhancement (403.3 ± 76.0 HU vs 359.7 ± 61.5 HU, p < 0.001) and significantly decreased enhancement of the superior vena cava (118.9 ± 46.2 HU vs 239.2 ± 130.5 HU, p < 0.001) compared with the conventional method. In the group with prior CTA images available, the effective dose was significantly lower with the double ROI timing bolus than with the conventional method (8.3 ± 1.7 mSv vs 12.4 ± 3.2 mSv, p < 0.01). CONCLUSION. Use of the double ROI timing bolus method can dramatically reduce the amount of contrast medium used during aortic CTA while improving aortic enhancement and reducing radiation dose.
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