Virtual Computed Tomography Colonography (original) (raw)
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European radiology, 2015
To prospectively evaluate the radiation dose and image quality comparing low-dose CT colonography (CTC) reconstructed using different levels of iterative reconstruction techniques with routine-dose CTC reconstructed with filtered back projection. Following institutional ethics clearance and informed consent procedures, 210 patients underwent screening CTC using automatic tube current modulation for dual positions. Examinations were performed in the supine position with a routine-dose protocol and in the prone position, randomly applying four different low-dose protocols. Supine images were reconstructed with filtered back projection and prone images with iterative reconstruction. Two blinded observers assessed the image quality of endoluminal images. Image noise was quantitatively assessed by region-of-interest measurements. The mean effective dose in the supine series was 1.88 mSv using routine-dose CTC, compared to 0.92, 0.69, 0.57, and 0.46 mSv at four different low doses in the ...
European Radiology, 2015
Objective-To prospectively compare reduced-dose (RD) CT colonography (CTC) with standard-dose (SD) imaging using several reconstruction algorithms. Methods-Following SD supine CTC, 40 patients (mean age, 57.3 years; 17 M/23 F, mean BMI, 27.2) underwent an additional RD supine examination (targeted dose reduction, 70-90%). DLP, CTDI vol , effective dose, and SSDE were compared. Several reconstruction algorithms were applied to RD series. SD-FBP served as reference standard. Objective image noise, subjective image quality and polyp conspicuity were assessed. Results-Mean CTDI vol and effective dose for RD series was 0.89 mGy (median 0.65) and 0.6 mSv (median 0.44), compared with 3.8 mGy (median 3.1) and 2.8 mSv (median 2.3) for SD series, respectively. Mean dose reduction was 78%. Mean image noise was significantly reduced on RD-PICCS (24.3±19HU) and RD-MBIR (19±18HU) compared with RD-FBP (90±33), RD-ASIR (72±27) and SD-FBP (47±14 HU). 2D image quality score was higher with RD-PICCS, RD-MBIR, and SD-FBP (2.7±0.4/2.8±0.4/2.9±0.6) compared with RD-FBP (1.5±0.4) and RD-ASIR (1.8±0.44). A similar trend was seen with 3D image quality scores. Polyp conspicuity scores were similar between SD-FBP/RD-PICCS/RD-MBIR (3.5±0.6/3.2±0.8/3.3±0.6). Conclusion-Sub-milliSievert CTC performed with iterative reconstruction techniques demonstrate decreased image quality compared to SD, but improved image quality compared to RD images reconstructed with FBP.
The second ESGAR consensus statement on CT colonography
European Radiology, 2013
Objective To update quality standards for CT colonography based on consensus among opinion leaders within the European Society of Gastrointestinal and Abdominal Radiology (ESGAR). Material and methods A multinational European panel of nine members of the ESGAR CT colonography Working Group (representing six EU countries) used a modified Delphi process to rate their level of agreement on a variety of statements pertaining to the acquisition, interpretation and implementation of CT colonography. Four Delphi rounds were conducted, each at 2 months interval. Results The panel elaborated 86 statements.
Journal of Applied Clinical Medical Physics
Objective: To assess the radiation dose and image quality of ultra-low dose (ULD)-CT colonography (CTC) obtained with the combined use of automatic tube current (mAs) modulation with a quality reference mAs of 25 and sinogram-affirmed iterative reconstruction (SAFIRE), compared to low-dose (LD) CTC acquired with a quality reference mAs of 55 and reconstructed with filtered back projection (FBP). Methods: Eighty-two patients underwent ULD-CTC acquisition in prone position and LD-CTC acquisition in supine position. Both ULD-CTC and LD-CTC protocols were compared in terms of radiation dose [weighted volume computed tomography dose index (CTDI vol) and effective dose], image noise, image quality, and polyp detection. Results: The mean effective dose of ULD-CTC was significantly lower than that of LD-CTC (0.98 and 2.69 mSv respectively, P < 0.0001) with an overall dose reduction of 63.2%. Image noise was comparable between ULD-CTC and LD-CTC (28.6 and 29.8 respectively, P = 0.09). There was no relevant difference when comparing image quality scores and polyp detection for both 2D and 3D images. Conclusion: ULD-CTC allows to significantly reduce the radiation dose without meaningful image quality degradation compared to LD-CTC.
AGA future trends report: CT colonography
Gastroenterology, 2004
Since the initial introduction of CTC by Vining et al. in 1994 1 a number of studies have compared CTC with colonoscopy. Early reports typically involved small populations at high risk for colorectal pathology and used single-row scanners. In these studies, the perpolyp analyses showed that CTC was poor at detecting small lesions (sensitivity, 11%-55%) but slightly better for medium-sized (6 -9 mm) and large lesions (Ն10 mm) with sensitivities ranging from 34% to 82% and 50% to 91%, respectively. The per-patient sensitivity, although Abbreviations used in this paper: CT, computed tomography; CTC, computerized tomographic colonography.
Temporal and Multiinstitutional Quality Assessment of CT Colonography
American Journal of Roentgenology, 2008
Purpose-To investigate the variability of CT colonography (CTC) scan quality obtained within and between institutions by using previously validated automated quality assessment (QA) software that assesses colonic distention and surface area obscured by residual fluid. Methods-The CTC scans of 120 patients were selected retrospectively, 30 from each of 4 institutions. The bowel preparation included oral contrast for fecal and fluid tagging. Patients at one institution (Institution 4) drank ½ the amount of oral contrast compared to the patients at the other 3 institutions. Fifteen of the CTC scans were from the beginning of the protocol studied at each institution and 15 scans were from the same protocol acquired approximately one year later in the study. We used previously validated QA software to automatically measure the mean distention and residual fluid of each of five colonic segments (ascending, transverse, descending, sigmoid, and rectum). Adequate distention was defined as a colonic diameter of at least 2 cm. Residual fluid was determined by the percentage of colonic surface area covered by fluid. We compared how the quality varied across multiple institutions and over time within the same institution. Results-No significant difference in the amount of colonic distention amongst the 4 institutions was found (p = 0.19). However, the distention in the prone position was significantly greater than the distention in the supine position (p < 0.001). Patients at Institution 4 had about ½ the amount of residual colonic fluid compared to patients at Institutions 1-3 (p < 0.01). The sigmoid and descending colons were the least distended segments, and the transverse and descending colon contained the most fluid on the prone and supine scans, respectively. More recently acquired studies had greater distention and less residual fluid but the differences were not statistically significant (p=0.30 and p=0.96, respectively). Conclusion-Across institutions, a significant difference can exist in bowel preparation quality for CTC. This study reaffirms the need for standardized bowel preparation and quality monitoring of CTC exams to reduce poor CTC performance.
Computed tomography colonography and radiation risk: How low can we go?
2021
Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.
Noncathartic CT Colonography: Image Quality Assessment and Performance and in a Screening Cohort
American Journal of Roentgenology, 2013
OBJECTIVE-Cathartic bowel preparation is a major barrier for colorectal cancer screening. We examined noncathartic CT colonography (CTC) quality and performance using four similar bowel-tagging regimens in an asymptomatic screening cohort. SUBJECTS AND METHODS-This prospective study included 564 asymptomatic subjects who underwent noncathartic CTC without dietary modification but with 21 g of barium with or without iodinated oral contrast material (four regimens). The quality of tagging with oral agents was evaluated. A gastrointestinal radiologist evaluated examinations using primary 2D search supplemented by electronic cleansing (EC) and 3D problem solving. Results were compared with complete colonoscopy findings after bowel purgation and with retrospective unblinded evaluation in 556 of the 564 (99%) subjects. RESULTS-Of the 556 subjects, 7% (37/556) and 3% (16/556) of patients had 52 and 20 adenomatous polyps ≥ 6 and ≥ 10 mm, respectively. The addition of iodine significantly improved the percentage of labeled stool (p ≤ 0.0002) and specificity (80% vs 89-93%, respectively; p = 0.046). The overall sensitivity of noncathartic CTC for adenomatous polyps ≥ 6 mm was 76% (28/37; 95% CI, 59-88%), which is similar to the sensitivity of the iodinated regimens with most patients (sensitivity: 231 patients, 74% [14/19; 95% CI, 49-91%]; 229 patients, 80% [12/15; 95% CI, 52-96%]). The negative predictive value was 98% (481/490), and the lone cancer was detected (0.2%, 1/556). EC was thought to improve conspicuity of 10 of 21 visible polyps ≥ 10 mm. CONCLUSION-In this prospective study of asymptomatic subjects, the per-patient sensitivity of noncathartic CTC for detecting adenomas ≥ 6 mm was approximately 76%. Inclusion of oral iodine contrast material improves examination specificity and the percentage of labeled stool. EC may improve polyp conspicuity.
Reducing data size and radiation dose for CT colonography
American Journal of Roentgenology, 1997
U sing helical CT data and advanced imaging software, CT colonography provides a complete colorectal examination with minimal patient risk or discomfort. Unlike two-dimensional (2D) axial CT images that are perpendicular to the patient's midline, reformatted 2D CT colonography images are produced at cross sections and orthogonal angles to the colon midline. Threedimensional (3D) CT colonography is a perspective intraluminal imaging technique that simulates an endoscopic view. Preliminary results using CT colonography have been promising for detecting colorectal cancer and polyps 11-41. but clinical usefulness is limited by lengthy image processing times and data storage requirements.