Search

Background Most radiologists reporting CT colonography (CTC) do not undergo compulsory performance accreditation, potentially lowering diagnostic sensitivity. Purpose To determine whether 1-day individualized training in CTC reporting improves diagnostic sensitivity of experienced radiologists for 6-mm or larger lesions, the durability of any improvement, and any associated factors. Materials and Methods This prospective, multicenter cluster-randomized controlled trial was performed in National Health Service hospitals in England and Wales between April 2017 and January 2020. CTC services were cluster randomized into intervention (1-day training plus feedback) or control (no training or feedback) arms. Radiologists in the intervention arm attended a 1-day workshop focusing on CTC reporting pitfalls with individualized feedback. Radiologists in the control group received no training. Sensitivity for 6-mm or larger lesions was tested at baseline and 1, 6, and 12 months thereafter via interpretation of 10 CTC scans at each time point. The primary outcome was the mean difference in per-lesion sensitivity between arms at 1 month, analyzed using multilevel regression after adjustment for baseline sensitivity. Secondary outcomes included per-lesion sensitivity at 6- and 12-month follow-up, sensitivity for flat neoplasia, and effect of prior CTC experience. Results A total of 69 hospitals were randomly assigned to the intervention (31 clusters, 80 radiologists) or control (38 clusters, 59 radiologists) arm. Radiologists were experienced (median, 500-999 CTC scans interpreted) and reported CTC scans routinely (median, 151-200 scans per year). One-month sensitivity improved after intervention (66.4% [659 of 992]) compared with sensitivity in the control group (42.4% [278 of 655]; difference = 20.8%; 95% CI: 14.6, 27.0; P < .001). Improvements were maintained at 6 (66.4% [572 of 861] vs 50.5% [283 of 560]; difference = 13.0%; 95% CI: 7.4, 18.5; P < .001) and 12 (63.7% [310 of 487] vs 44.4% [187 of 421]; difference = 16.7%; 95% CI: 10.3, 23.1; P < .001) months. This beneficial effect applied to flat lesions (difference = 22.7%; 95% CI: 15.5, 29.9; P < .001) and was independent of career experience (≥1500 CTC scans: odds ratio = 1.09; 95% CI: 0.88, 1.36; P = .22). Conclusion For radiologists evaluating CT colonography studies, a 1-day training intervention yielded sustained improvement in detection of clinically relevant colorectal neoplasia, independent of previous career experience. Clinical trial registration no. NCT02892721 © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Pickhardt in this issue. An earlier incorrect version appeared online and in print. This article was corrected on February 28, 2022.

Purpose To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography Materials and Methods Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling. Results Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively). Conclusion Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification. © RSNA, 2017 Online supplemental material is available for this article.

Objective: To assess the effect of expected abnormality prevalence on visual search and decision-making in CT colonography (CTC)., Methods: 13 radiologists interpreted endoluminal CTC fly-throughs of the same group of 10 patient cases, 3 times each. Abnormality prevalence was fixed (50%), but readers were told, before viewing each group, that prevalence was either 20%, 50% or 80% in the population from which cases were drawn. Infrared visual search recording was used. Readers indicated seeing a polyp by clicking a mouse. Multilevel modelling quantified the effect of expected prevalence on outcomes., Results: Differences between expected prevalence were not statistically significant for time to first pursuit of the polyp (median 0.5 s, each prevalence), pursuit rate when no polyp was on screen (median 2.7 s(-1), each prevalence) or number of mouse clicks [mean 0.75/video (20% prevalence), 0.93 (50%), 0.97 (80%)]. There was weak evidence of increased tendency to look outside the central screen area at 80% prevalence and reduction in positive polyp identifications at 20% prevalence., Conclusion: This study did not find a large effect of prevalence information on most visual search metrics or polyp identification in CTC. Further research is required to quantify effects at lower prevalence and in relation to secondary outcome measures., Advances in Knowledge: Prevalence effects in evaluating CTC have not previously been assessed. In this study, providing expected prevalence information did not have a large effect on diagnostic decisions or patterns of visual search.

Objective: The objective of our study was to describe the characteristics of polyps viewed but then dismissed incorrectly by radiologists at endoluminal CT colonography (CTC), eye movements during these errors, and features provoking false-positive diagnoses., Materials and Methods: Forty-two radiologists viewed 30 endoluminal CTC videos, each depicting a polyp, while their eye movements were tracked. Half of the videos had computer-assisted detection (CAD), and half did not. Classification errors were defined when proven polyps were seen but dismissed. Eye movements during these errors and during correct polyp identifications were compared with multilevel modeling. Polyps were divided subsequently into "difficult to classify" and "easy to classify" using a classification error threshold of more than 15%. Polyp diameter, height, and subjective conspicuity and the proportion of time viewed were compared between groups., Results: Eye tracking revealed that 97% of false-negative polyp diagnoses were nonetheless preceded by the reader observing the polyp. The difficult polyps were significantly smaller than the easy polyps (mean diameter, 5.4 vs 8.2 mm, respectively p = 0.014) and were subjectively less conspicuous (median score, 4 vs 2; p = 0.0032). Readers spent proportionally less time viewing difficult polyps than viewing easy polyps (29.0% of the time they were on-screen vs 42.6%, respectively; p = 0.01) regardless of the presence of CAD., Conclusion: Even small and subjectively inconspicuous polyps attract reader gaze, but they are nonetheless ignored. These errors are made rapidly even with CAD. Efforts to improve reader performance at CTC should focus on decision making rather than detection alone.

Objectives: To quantify the incremental benefit of computer-assisted-detection (CAD) for polyps, for inexperienced readers versus experienced readers of CT colonography., Methods: 10 inexperienced and 16 experienced radiologists interpreted 102 colonography studies unassisted and with CAD utilised in a concurrent paradigm. They indicated any polyps detected on a study sheet. Readers' interpretations were compared against a ground-truth reference standard: 46 studies were normal and 56 had at least one polyp (132 polyps in total). The primary study outcome was the difference in CAD net benefit (a combination of change in sensitivity and change in specificity with CAD, weighted towards sensitivity) for detection of patients with polyps., Results: Inexperienced readers' per-patient sensitivity rose from 39.1% to 53.2% with CAD and specificity fell from 94.1% to 88.0%, both statistically significant. Experienced readers' sensitivity rose from 57.5% to 62.1% and specificity fell from 91.0% to 88.3%, both non-significant. Net benefit with CAD assistance was significant for inexperienced readers but not for experienced readers: 11.2% (95%CI 3.1% to 18.9%) versus 3.2% (95%CI -1.9% to 8.3%) respectively., Conclusions: Concurrent CAD resulted in a significant net benefit when used by inexperienced readers to identify patients with polyps by CT colonography. The net benefit was nearly four times the magnitude of that observed for experienced readers. Experienced readers did not benefit significantly from concurrent CAD.

Objective: We aimed to identify the effect of computer-aided detection (CAD) on visual search and performance in CT Colonography (CTC) of inexperienced and experienced readers., Methods: Fifteen endoluminal CTC examinations were recorded, each with one polyp, and two videos were generated, one with and one without a CAD mark. Forty-two readers (17 experienced, 25 inexperienced) interpreted the videos during infrared visual search recording. CAD markers and polyps were treated as regions of interest in data processing. This multi-reader, multi-case study was analysed using multilevel modelling., Results: CAD drew readers' attention to polyps faster, accelerating identification times: median 'time to first pursuit' was 0.48 s (IQR 0.27 to 0.87 s) with CAD, versus 0.58 s (IQR 0.35 to 1.06 s) without. For inexperienced readers, CAD also held visual attention for longer. All visual search metrics used to assess visual gaze behaviour demonstrated statistically significant differences when "with" and "without" CAD were compared. A significant increase in the number of correct polyp identifications across all readers was seen with CAD (74 % without CAD, 87 % with CAD; p < 0.001)., Conclusions: CAD significantly alters visual search and polyp identification in readers viewing three-dimensional endoluminal CTC. For polyp and CAD marker pursuit times, CAD generally exerted a larger effect on inexperienced readers., Key Points: • Visual gaze is attracted by computer-assisted detection (CAD) marks on polyps • Inexperienced readers' gaze is affected more by CAD than experienced readers. • CAD marks could mean that the unannotated endoluminal surface is relatively neglected. • Correct polyp identification is increased significantly by CAD.

Purpose: To identify and compare key stages of the visual process in experienced and inexperienced readers and to examine how these processes are used to search a moving three-dimensional ( 3D three-dimensional ) image and their relationship to false-negative errors., Materials and Methods: Institutional review board research ethics approval was granted to use anonymized computed tomographic (CT) colonographic data from previous studies and to obtain eye-tracking data from volunteers. Sixty-five radiologists (27 experienced, 38 inexperienced) interpreted 23 endoluminal 3D three-dimensional CT colonographic videos. Eye movements were recorded by using eye tracking with a desk-mounted tracker. Readers indicated when they saw a polyp by clicking a computer mouse. Polyp location and boundary on each video frame were quantified and gaze data were related to the polyp boundary for each individual reader and case. Predefined metrics were quantified and used to describe and compare visual search patterns between experienced and inexperienced readers by using multilevel modeling., Results: Time to first pursuit was significantly shorter in experienced readers (hazard ratio, 1.22 [95% confidence interval: 1.04, 1.44]; P = .017) but other metrics were not significantly different. Regardless of expertise, metrics such as assessment, identification period, and pursuit times were extended in videos where polyps were visible on screen for longer periods of time. In 97% (760 of 787) of observations, readers correctly pursued polyps., Conclusion: Experienced readers had shorter time to first eye pursuit, but many other characteristics of eye tracking were similar between experienced and inexperienced readers. Readers pursued polyps in 97% of observations, which indicated that errors during interpretation of 3D three-dimensional CT colonography in this study occurred in either the discovery or the recognition phase, but rarely in the scanning phase of radiologic image inspection., (© RSNA, 2014.)

Background: Different methods of evaluating diagnostic performance when comparing diagnostic tests may lead to different results. We compared two such approaches, sensitivity and specificity with area under the Receiver Operating Characteristic Curve (ROC AUC) for the evaluation of CT colonography for the detection of polyps, either with or without computer assisted detection., Methods: In a multireader multicase study of 10 readers and 107 cases we compared sensitivity and specificity, using radiological reporting of the presence or absence of polyps, to ROC AUC calculated from confidence scores concerning the presence of polyps. Both methods were assessed against a reference standard. Here we focus on five readers, selected to illustrate issues in design and analysis. We compared diagnostic measures within readers, showing that differences in results are due to statistical methods., Results: Reader performance varied widely depending on whether sensitivity and specificity or ROC AUC was used. There were problems using confidence scores; in assigning scores to all cases; in use of zero scores when no polyps were identified; the bimodal non-normal distribution of scores; fitting ROC curves due to extrapolation beyond the study data; and the undue influence of a few false positive results. Variation due to use of different ROC methods exceeded differences between test results for ROC AUC., Conclusions: The confidence scores recorded in our study violated many assumptions of ROC AUC methods, rendering these methods inappropriate. The problems we identified will apply to other detection studies using confidence scores. We found sensitivity and specificity were a more reliable and clinically appropriate method to compare diagnostic tests.

Purpose: To determine the maximum rate of false-positive diagnoses that patients and health care professionals were willing to accept in exchange for detection of extracolonic malignancy by using computed tomographic (CT) colonography for colorectal cancer screening., Materials and Methods: After obtaining ethical approval and informed consent, 52 patients and 50 health care professionals undertook two discrete choice experiments where they chose between unrestricted CT colonography that examined intra- and extracolonic organs or CT colonography restricted to the colon, across different scenarios. The first experiment detected one extracolonic malignancy per 600 cases with a false-positive rate varying across scenarios from 0% to 99.8%. One experiment examined radiologic follow-up generated by false-positive diagnoses while the other examined invasive follow-up. Intracolonic performance was identical for both tests. The median tipping point (maximum acceptable false-positive rate for extracolonic findings) was calculated overall and for both groups by bootstrap analysis., Results: The median tipping point for radiologic follow-up occurred at a false-positive rate greater than 99.8% (interquartile ratio [IQR], 10 to >99.8%). Participants would tolerate at least a 99.8% rate of unnecessary radiologic tests to detect an additional extracolonic malignancy. The median tipping-point for invasive follow-up occurred at a false-positive rate of 10% (IQR, 2 to >99.8%). Tipping points were significantly higher for patients than for health care professionals for both experiments (>99.8 vs 40% for radiologic follow-up and >99.8 vs 5% for invasive follow-up, both P < .001)., Conclusion: Patients and health care professionals are willing to tolerate high rates of false-positive diagnoses with CT colonography in exchange for diagnosis of extracolonic malignancy. The actual specificity of screening CT colonography for extracolonic findings in clinical practice is likely to be highly acceptable to both patients and health care professionals. Online supplemental material is available for this article., (© RSNA, 2014.)

Objective: CT colonography (CTC) is recommended after positive faecal occult blood testing (FOBt) when colonoscopy is incomplete or infeasible. We aimed to estimate the sensitivity and specificity of CTC for colorectal cancer and adenomatous polyps following positive FOBt via systematic review., Methods: The MEDLINE, EMBASE, AMED and Cochrane Library databases were searched for CTC studies reporting sensitivity and specificity for colorectal cancer and adenomatous polyps. Included subjects had tested FOBt-positive by guaiac or immunochemical methods. Per-patient detection rates were summarized via forest plots. Meta-analysis of sensitivity and specificity was conducted using a bivariate random effects model and the average operating point calculated., Results: Of 538 articles considered, 5 met inclusion criteria, describing results from 622 patients. Research study quality was good. CTC had a high per-patient average sensitivity of 88.8 % (95 % CI 83.6 to 92.5 %) for ≥6 mm adenomas or colorectal cancer, with low between-study heterogeneity. Specificity was both more heterogeneous and lower, at an average of 75.4 % (95 % CI 58.6 to 86.8 %)., Conclusion: Few studies have investigated CTC in FOBt-positive individuals. CTC is sensitive at a ≥6 mm threshold but specificity is lower and variable. Despite the limited data, these results suggest that CTC may adequately substitute for colonoscopy when the latter is undesirable., Key Points: • FOBt is the most common mass screening test for colorectal cancer. • Few studies evaluate CT colonography after positive FOBt. • CTC is approximately 89 % sensitive for ≥6 mm adenomas/cancer in this setting. • Specificity is lower, at approximately 75 %, and more variable. • CT colonography is a good alternative when colonoscopy is undesirable.

Objective: Eye tracking in three dimensions is novel, but established descriptors derived from two-dimensional (2D) studies are not transferable. We aimed to develop metrics suitable for statistical comparison of eye-tracking data obtained from readers of three-dimensional (3D) "virtual" medical imaging, using CT colonography (CTC) as a typical example., Methods: Ten experienced radiologists were eye tracked while observing eight 3D endoluminal CTC videos. Subsequently, we developed metrics that described their visual search patterns based on concepts derived from 2D gaze studies. Statistical methods were developed to allow analysis of the metrics., Results: Eye tracking was possible for all readers. Visual dwell on the moving region of interest (ROI) was defined as pursuit of the moving object across multiple frames. Using this concept of pursuit, five categories of metrics were defined that allowed characterization of reader gaze behaviour. These were time to first pursuit, identification and assessment time, pursuit duration, ROI size and pursuit frequency. Additional subcategories allowed us to further characterize visual search between readers in the test population., Conclusion: We propose metrics for the characterization of visual search of 3D moving medical images. These metrics can be used to compare readers' visual search patterns and provide a reproducible framework for the analysis of gaze tracking in the 3D environment., Advances in Knowledge: This article describes a novel set of metrics that can be used to describe gaze behaviour when eye tracking readers during interpretation of 3D medical images. These metrics build on those established for 2D eye tracking and are applicable to increasingly common 3D medical image displays.

Purpose: To establish the relative weighting given by patients and healthcare professionals to gains in diagnostic sensitivity versus loss of specificity when using CT colonography (CTC) for colorectal cancer screening., Materials and Methods: Following ethical approval and informed consent, 75 patients and 50 healthcare professionals undertook a discrete choice experiment in which they chose between "standard" CTC and "enhanced" CTC that raised diagnostic sensitivity 10% for either cancer or polyps in exchange for varying levels of specificity. We established the relative increase in false-positive diagnoses participants traded for an increase in true-positive diagnoses., Results: Data from 122 participants were analysed. There were 30 (25%) non-traders for the cancer scenario and 20 (16%) for the polyp scenario. For cancer, the 10% gain in sensitivity was traded up to a median 45% (IQR 25 to >85) drop in specificity, equating to 2250 (IQR 1250 to >4250) additional false-positives per additional true-positive cancer, at 0.2% prevalence. For polyps, the figure was 15% (IQR 7.5 to 55), equating to 6 (IQR 3 to 22) additional false-positives per additional true-positive polyp, at 25% prevalence. Tipping points were significantly higher for patients than professionals for both cancer (85 vs 25, p<0.001) and polyps (55 vs 15, p<0.001). Patients were willing to pay significantly more for increased sensitivity for cancer (p = 0.021)., Conclusion: When screening for colorectal cancer, patients and professionals believe gains in true-positive diagnoses are worth much more than the negative consequences of a corresponding rise in false-positives. Evaluation of screening tests should account for this.

Purpose: To develop an eye-tracking method applicable to three-dimensional (3D) images, where the abnormality is both moving and changing in size., Materials and Methods: Research ethics committee approval was granted to record eye-tracking data from six inexperienced readers who inspected eight short (<30 seconds) endoluminal fly-through videos extracted from computed tomographic (CT) colonography examinations. Cases included true-positive and false-positive polyp detections from a previous study (polyp diameters, 5-25 mm). Eye tracking was performed with a desk-mounted tracker, and readers indicated when they saw a polyp with a mouse click. The polyp location on each video frame was quantified subsequently by using a circular mask. Gaze data related to each video frame were calculated relative to the visible polyp boundary and used to identify eye movements that pursue a polyp target as it changes size and position during fly-through. Gaze data were then related to positive polyp detections by readers., Results: Tracking eye gaze on moving 3D images was technically feasible. Gaze was successfully classified by using pursuit analysis, and pursuit-based gaze metrics were able to help discriminate different reader search behaviors and methods of allocating visual attention during polyp identification. Of a total of 16 perceptual errors, 15 were recognition errors. There was only one visual search error. The largest polyp (25 mm) was seen but not recognized by five of six readers., Conclusion: Tracking a reader's gaze during endoluminal interpretation of 3D data sets is technically feasible and can be described with pursuit-based metrics. Perceptual errors can be classified into visual search errors and recognition errors. Recognition errors are more frequent in inexperienced readers.

Purpose: To quantify the changes in reader performance levels, if any, during interpretation of computed tomographic (CT) colonographic data when a computer-aided detection (CAD) system is used as a second or concurrent reader., Materials and Methods: After institutional review board approval was obtained, 16 experienced radiologists searched for polyps in 112 patients, 56 of whom had 132 polyps. Each case was interpreted on three separate occasions by using an unassisted (without CAD), second-read CAD, or concurrent CAD reading paradigm. The reading paradigm and case order were randomized, with a minimal interval of 1 month between consecutive interpretations. The readers' findings were compared with the reference-truth interpretation. The mean per-patient sensitivity and mean per-patient specificity with CAD were compared with those achieved with unassisted reading. An increase in per-patient sensitivity was considered to be clinically more important than an equivalent decrease in specificity., Results: The mean per-patient sensitivity for identification of patients with polyps of any size increased significantly with use of second-read CAD (mean increase, 7.0%; 95% confidence interval [CI]: 4.0%, 9.8%) and concurrent CAD (mean increase, 4.5%; 95% CI: 0.8%, 8.2%). The mean per-patient specificity did not decrease significantly with use of second-read CAD (mean decrease, -2.5%; 95% CI: -5.2%, 0.1%) or concurrent CAD (mean decrease, -2.2%; 95% CI: -4.6%, 0.2%). With analysis restricted to patients with polyps 6 mm or larger, the benefit in sensitivity with second-read CAD remained (mean increase, 7.1%; 95% CI: 3.0%, 11.1%), whereas the increase with concurrent CAD was not significant (mean increase, 4.2%; 95% CI: -0.5%, 8.9%). Use of second-read CAD significantly increased the per-polyp sensitivity for polyps 6 mm or larger (mean increase, 9.0%; 98.3% CI: 4.9%, 12.8%) and polyps 5 mm or smaller (mean increase, 5.9%; 98.3% CI: 3.2%, 9.1%), but use of concurrent CAD increased the per-polyp sensitivity for only those polyps 5 mm or smaller (mean increase, 4.8%; 98.3% CI: 2.2%, 7.9%)., Conclusion: Use of second-read CAD significantly improves readers' per-patient and per-polyp detection. Concurrent CAD is less effective., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100354/-/DC1., (© RSNA, 2010)

Purpose: To determine objectively the current standard of reporting for studies of computer-aided detection (CAD) for computed tomographic (CT) colonography by systematically reviewing published articles., Materials and Methods: MEDLINE was searched to identify study articles meeting the inclusion criteria for describing CAD for CT colonography in human subjects. Data were extracted from eligible articles, grouped into five domains: technical description of CAD algorithm, description of subjects, acquisition of data, evaluation strategy used, and presentation of results. Primary studies were scored for each domain and overall findings plotted as star plots., Results: Although 21 (91%) of the 23 studies included presented technical details of the CAD algorithm, methodologic details used for model development and validity were generally poor. Investigators in six (26%) studies described the evaluation data set sufficiently for replication; investigators in eight (35%) studies described age and sex demographics for subjects in whom CAD was tested. Investigators in 11 (48%) studies presented polyps per subject. Investigators in 12 (52%) studies described the reference standard against which CAD was judged; 11 (48%) studies explicitly distinguished between development and evaluation data. In nine (39%) studies, the evaluation strategy used to test CAD could not be deduced at all. Description of subjects included for CAD development and evaluation was most poorly reported, with an average score per study of 33% in this domain., Conclusion: The reporting quality for studies of CAD for CT colonography is highly variable; key methodologic details needed for informed assessment of the generalizability of results are frequently omitted, for which a minimum data set based on the observations is proposed., ((c) RSNA, 2008.)

Background & Aims: In isolation, computer-aided detection (CAD) for computed tomographic (CT) colonography is as effective as optical colonoscopy for detection of significant adenomas. However, the unavoidable interaction between CAD and the reader has not been addressed., Methods: Ten readers trained in CT but without special expertise in colonography interpreted CT colonography images of 107 patients (60 with 142 polyps), first without CAD and then with CAD after temporal separation of 2 months. Per-patient and per-polyp detection were determined by comparing responses with known patient status., Results: With CAD, 41 (68%; 95% confidence interval [CI], 55%-80%) of the 60 patients with polyps were identified more frequently by readers. Per-patient sensitivity increased significantly in 70% of readers, while specificity dropped significantly in only one. Polyp detection increased significantly with CAD; on average, 12 more polyps were detected by each reader (9.1%, 95% CI, 5.2%-12.8%). Small- (< or =5 mm) and medium-sized (6-9 mm) polyps were significantly more likely to be detected when prompted correctly by CAD. However, overall performance was relatively poor; even with CAD, on average readers detected only 10 polyps (51.0%) > or =10 mm and 24 (38.2%) > or =6 mm. Interpretation time was shortened significantly with CAD: by 1.9 minutes (95% CI, 1.4-2.4 minutes) for patients with polyps and by 2.9 minutes (95% CI, 2.5-3.3 minutes) for patients without. Overall, 9 readers (90%) benefited significantly from CAD, either by increased sensitivity and/or by reduced interpretation time., Conclusions: CAD for CT colonography significantly increases per-patient and per-polyp detection and significantly reduces interpretation times but cannot substitute for adequate training.

Purpose: To assess the methodologic quality of available data in published reports of computed tomographic (CT) colonography by performing systematic review and meta-analysis., Materials and Methods: The MEDLINE database was searched for colonography reports published between 1994 and 2003, without language restriction. The terms colonography, colography, CT colonoscopy, CT pneumocolon, virtual colonoscopy, and virtual endoscopy were used. Studies were selected if the focus was detection of colorectal polyps verified with within-subject reference colonoscopy by using key methodologic criteria based on information presented at the Fourth International Symposium on Virtual Colonoscopy (Boston, Mass). Two reviewers independently abstracted methodologic characteristics. Per-patient and per-polyp detection rates were extracted, and authors were contacted, when necessary. Per-patient sensitivity and specificity were calculated for different lesion size categories, and Forest plots were produced. Meta-analysis of paired sensitivity and specificity was conducted by using a hierarchical model that enabled estimation of summary receiver operating characteristic curves allowing for variation in diagnostic threshold, and the average operating point was calculated. Per-polyp sensitivity was also calculated., Results: Of 1398 studies considered for inclusion, 24 met our criteria. There were 4181 patients with a study prevalence of abnormality of 15%-72%. Meta-analysis of 2610 patients, 206 of whom had large polyps, showed high per-patient average sensitivity (93%; 95% confidence interval [CI]: 73%, 98%) and specificity (97%; 95% CI: 95%, 99%) for colonography; sensitivity and specificity decreased to 86% (95% CI: 75%, 93%) and 86% (95% CI: 76%, 93%), respectively, when the threshold was lowered to include medium polyps. When polyps of all sizes were included, studies were too heterogeneous in sensitivity (range, 45%-97%) and specificity (range, 26%-97%) to allow meaningful meta-analysis. Of 150 cancers, 144 were detected (sensitivity, 95.9%; 95% CI: 91.4%, 98.5%). Data reporting was frequently incomplete, with no generally accepted format., Conclusion: CT colonography seems sufficiently sensitive and specific in the detection of large and medium polyps; it is especially sensitive in the detection of symptomatic cancer. Studies are poorly reported, however, and the authors propose a minimum data set for study reporting., (RSNA, 2005)