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C Daniel Johnson

Publications and source records attributed to C Daniel Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Development of a cathartic-free colorectal cancer screening test using virtual colonoscopy: a feasibility study.

OBJECTIVE: The purpose of our study was to develop a method to subtract barium-labeled stool from the colon using a phantom and to evaluate the performance of the technique in a pilot human population. MATERIALS AND METHODS: A phantom containing 6-mm flat polyps and three types of simulated stool (homogeneous, moderately heterogeneous, and severely heterogeneous) mixed with barium was created, scanned, and tested using three stool subtraction algorithms but no cathartic. Thirty patients with suspected colorectal polyps were studied using stool tagging to determine which was the most effective stool subtraction algorithm. Colonoscopy was the reference standard. Examinations were evaluated blindly using the unsubtracted and 6 weeks later both the unsubtracted and subtracted data sets. RESULTS: A threshold of 200 H and expansion and convolution techniques were the most effective tools for subtracting stool and minimizing artifacts. When applied to the human population, sensitivities using the unsubtracted data sets were 90% (18/20) and 68% (26/38) for polyps > or = 1 cm and > or = 5 mm, respectively. Specificities were 100% (4/4) and 75% (3/4) for polyps > or = 1 cm and > or = 5 mm. For the stool-subtracted data sets, sensitivities were 90% (18/20) and 71% (27/38) for polyps > or = 1 cm and > or = 5 mm. Per patient sensitivities were 88% (15/17) and 77% (20/26) for > or = 1 cm and > or = 5 mm polyps. Specificities were 100% (4/4) for large polyps and 25% (1/4) for smaller polyps. CONCLUSION: Image processing tools combining thresholding, expansion, and convolution were the most useful for stool subtraction. Laxative-free colon examinations using barium for stool labeling can be performed at CT colonography with or without stool subtraction with high accuracy. Further study is warranted.

Algorithms↗
PubMed2007

Polyp measurement with CT colonography: multiple-reader, multiple-workstation comparison.

OBJECTIVE: The risk of invasive colorectal cancer in colorectal polyps correlates with lesion size. Our purpose was to define the most accurate methods for measuring polyp size at CT colonography (CTC) using three models of workstations and multiple observers. MATERIALS AND METHODS: Six reviewers measured 24 unique polyps of known size (5, 7, 10, and 12 mm), shape (sessile, flat, and pedunculated), and location (straight or curved bowel segment) using CTC data sets obtained at two doses (5 mAs and 65 mAs) and a previously described colonic phantom model. Reviewers measured the largest diameter of polyps on three proprietary workstations. Each polyp was measured with lung and soft-tissue windows on axial, 2D multiplanar reconstruction (MPR), and 3D images. RESULTS: There were significant differences among measurements obtained at various settings within each workstation (p < 0.0001). Measurements on 2D images were more accurate with lung window than with soft-tissue window settings (p < 0.0001). For the 65-mAs data set, the most accurate measurements were obtained in analysis of axial images with lung window, 2D MPR images with lung window, and 3D tissue cube images for Wizard, Advantage, and Vitrea workstations, respectively, without significant differences in accuracy among techniques (0.11 < p < 0.59). The mean absolute error values for these optimal settings were 0.48 mm, 0.61 mm, and 0.76 mm, respectively, for the three workstations. Within the ultralow-dose 5-mAs data set the best methods for Wizard, Advantage, and Vitrea were axial with lung window, 2D MPR with lung window, and 2D MPR with lung window, respectively. Use of nearly all measurement methods, except for the Vitrea 3D tissue cube and the Wizard 2D MPR with lung window, resulted in undermeasurement of the true size of the polyps. CONCLUSION: Use of CTC computer workstations facilitates accurate polyp measurement. For routine CTC examinations, polyps should be measured with lung window settings on 2D axial or MPR images (Wizard and Advantage) or 3D images (Vitrea). When these optimal methods are used, these three commercial workstations do not differ significantly in acquisition of accurate polyp measurements at routine dose settings.

Algorithms↗
PubMed2006

Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.

PURPOSE: To retrospectively evaluate small-bowel enhancement characteristics and the sensitivity, specificity, and interobserver agreement of computed tomographic (CT) findings by using histologic and endoscopic results as a reference standard in patients undergoing enteric phase CT enterography. MATERIALS AND METHODS: The institutional review board approved this retrospective HIPAA-compliant study, which included patients who consented to having their medical records used for research purposes. Enteric phase CT enterographic and ileoscopic findings with or without ileal histologic results were examined in 42 patients (24 women, 18 men). Enteric phase CT enterography was performed after 150 mL of intravenous contrast material was administered at 4 mL/sec, with a 45-second delay. Mural attenuation was measured in the distended and collapsed jejunal and ileal loops and in the terminal ileum. Two radiologists examined CT images for findings of Crohn disease. Mural attenuation for different bowel loops was compared by using a Student t test, with kappa statistics used to measure interobserver agreement and Pearson correleation coefficients used to compare visual and quantitative measures. RESULTS: Distended jejunal loops had significantly greater attenuation than distended ileal loops (113 HU vs 72 HU; P < .001). Attenuation of collapsed jejunal (134 HU) and ileal (108 HU) loops was greater than that of distended jejunal and ileal loops (P < .001). Terminal ileal enhancement was the most sensitive visual CT finding of Crohn disease for both radiologists. Mural thickening demonstrated the greatest interobserver agreement (kappa = 0.83). Visual enhancement and quantitative mural attenuation were significantly correlated (P < .003). CONCLUSION: At enteric phase CT enterography, jejunal attenuation is greater than ileal attenuation and collapsed bowel loops demonstrate greater attenuation than distended bowel loops. Mural hyperenhancement and increased mural thickness are the most sensitive CT findings of active Crohn disease.

Adult↗
PubMed2006

Abdominal CT as a predictor of outcome before attempted direct percutaneous endoscopic jejunostomy.

BACKGROUND: Direct percutaneous endoscopic jejunostomy (DPEJ) placement succeeds in 72% to 86% of attempts. Failure is most often because of inadequate transillumination or gastroduodenal obstruction. Even in failed cases, patients are exposed to the risks of anesthesia, exploratory percutaneous needle punctures, and the cost burden of suboptimal resource utilization. Hence, a preprocedure predictor of outcome would be useful. OBJECTIVE: To evaluate whether review of clinically available abdominal CTs can predict the outcome of subsequent DPEJ attempts. DESIGN: Retrospectively conducted blinded review of abdominal CTs performed within 30 days before attempted DPEJ. Objective anatomic features potentially pertinent to DPEJ success were scored, and a prediction of the anticipated procedural outcome was made. SETTING: A large tertiary referral center. PATIENTS: A total of 115 patients who underwent attempted DPEJ and who also had an abdominal CT in the preceding 30 days. MAIN OUTCOME MEASUREMENTS: Reviewer's overall prediction of success, 3 objective anatomic measurements. RESULTS: For the overall prediction of success, a CT performed poorly, with a sensitivity of 60%, a specificity of 53%, a positive predictive value of 71%, and a negative predictive value of 40%. Mean abdominal-wall thickness was significantly greater in the failures than the successes (27 vs 21 mm, P = .02), and just 39% of the procedures in patients with an abdominal-wall thickness >3 cm were successful. LIMITATIONS: Retrospective. CONCLUSIONS: Failed DPEJ attempts were associated with greater patient abdominal-wall thickness, and this should be taken into consideration before attempted DPEJ. Otherwise, review of existing abdominal CTs appears to have limited utility in predicting DPEJ outcome.

Abdominal Wall↗
PubMed2006

Crohn Disease: mural attenuation and thickness at contrast-enhanced CT Enterography--correlation with endoscopic and histologic findings of inflammation.

PURPOSE: To determine retrospectively if quantitative measures of small-bowel mural attenuation and thickness at computed tomographic (CT) enterography correlate with endoscopic and histologic findings of small-bowel inflammation and to estimate the performance of these measures in predicting inflammatory Crohn disease. MATERIALS AND METHODS: The institutional review board approved this HIPAA-compliant retrospective study, which was conducted with patient informed consent. CT enterography data in 96 patients (31 male patients and 65 female patients) who underwent ileoscopy with or without biopsy were examined for CT signs of active Crohn disease. The most highly enhancing segment of terminal ileum and a normal-appearing ileal loop were identified. After it was confirmed that semiautomated software could accurately measure mural attenuation and thickness, the selected terminal ileal and normal-appearing (control) ileal loops were examined (20 automated measurements at each location) to quantify mural attenuation and wall thickness. Results were compared with endoscopy and histology reports by using logistic regression analysis and receiver operating characteristic curves. RESULTS: Quantitative measures of terminal ileal mural attenuation and wall thickness correlated significantly with active Crohn disease (P < .001). Small-bowel wall thickness was not a significant factor after attenuation was taken into account. A threshold attenuation value with a sensitivity of 90% (18 of 20) for definite Crohn disease (compared with a sensitivity of 80% [16 of 20] for radiologist assessment) was selected. In patients who underwent ileal biopsy, threshold attenuation had a sensitivity identical to that of ileoscopy (81% [26 of 32]; 95% confidence interval: 64%, 93%) in predicting histologic inflammation. CONCLUSION: Quantitative measures of mural attenuation and wall thickness at CT enterography correlate highly with ileoscopic and histologic findings of inflammatory Crohn disease. Quantitative measures of mural attenuation are sensitive markers of small bowel inflammation.

Adolescent↗
PubMed2006

Assessment of cardiovascular risk status at CT colonography.

PURPOSE: To retrospectively determine whether calcium scores of the abdominal aorta obtained during computed tomographic (CT) colonography relate to Framingham risk factors and clinical cardiac events. MATERIALS AND METHODS: The institutional review board approved the current HIPAA-compliant retrospective study and waived informed consent. Between 1995 and 1998, 480 patients underwent CT colonography; 467 patients were available for assessment. Calcium scores with a threshold attenuation value of 130 HU or greater were recorded for abdominal aorta (suprarenal, infrarenal, and aortic bifurcation regions and total). Patient histories were abstracted for established cardiac risk factors and subsequent cardiac events. Associations between calcium measurements and binary risk factors were assessed with Wilcoxon rank sum test; those with continuous risk factors, with Spearman rank correlation coefficient; and those with combined end points, with Cox proportional hazards model. RESULTS: Follow-up data were available for 467 patients with median age of 65 years (range, 34-83 years); 59% (275 of 467) were men. Nine patients had cardiac events subsequent to CT colonography. Results of proportional hazards regression analysis revealed a significant association between myocardial infarction or cardiac event-related death and calcium scores of the aortic bifurcation that exceeded 895, the value for the 75th percentile for this calcium variable (P < .01). Associations with established cardiac risk factors for all four calcium scores were significant (P < .05). Spearman rank correlation coefficients for associations between total calcium score and patient characteristics of age, number of pack-years of smoking, and systolic blood pressure were 0.51, 0.43, and 0.29, respectively (P < .001 for all). CONCLUSION: Aortic calcification scores at CT colonography are significantly associated with established cardiac risk factors and cardiac-related events. This screening information can be obtained without additional scanning or risk to the patient.

Adult↗
PubMed2006

CT colonography using 360-degree virtual dissection: a feasibility study.

OBJECTIVE: Using a 3D rendering technique called "virtual dissection," we sought to evaluate polyp and fold distortion using a colon phantom, estimate the polyp detection performance in humans, and estimate the added benefit of double interpretation and computer-aided diagnosis. MATERIALS AND METHODS: A colon phantom containing 144 polyps of varying sizes (5-12 mm) and shapes (flat, sessile, pedunculated) was scanned. Polyp shape and distortion at virtual dissection were categorized as flame, club, pea, or bizarre. Haustral fold distortion was graded. The CT colonography examinations in 20 consecutive patients (colonoscopically proven normal findings, n = 5; polyps > or = 1 cm, n = 17 in 15 patients) were blindly reviewed by three radiologists using the virtual dissection technique. The added benefits of double interpretation and computer-aided diagnosis were tabulated. RESULTS: Sessile polyps appeared flame (35/48 [73%]) or pea (11/48 [23%]) in shape. Flat polyps appeared flame-shaped (31/47 [66%]) or pea-shaped (16/47 [34%]). Pedunculated polyps were flame (15/45 [33%]), club (20/45 [44%]), or pea (6/45 [13%]) in shape. Axial distortion occurred along the longitudinal axis. The sensitivities of the three observers for polyps of 1 cm or more were 16/17 (94%), 14/17 (82%), and 15/17 (88%). The specificities were 5/5 (100%), 5/5 (100%), and 4/5 (80%). Sensitivities after double interpretation and computer-aided diagnosis improved but did not reach statistical significance. CONCLUSION: Although distortion of colonic structures exists at virtual dissection, it does so in recognizable patterns, so that sensitivity for polyp detection is not compromised.

Aged↗
PubMed2006

Occult colorectal polyps on CT colonography: implications for surveillance.

OBJECTIVE: Our purpose was to determine the prevalence of polyps that are invisible on CT colonography (CTC) in a population previously screened for colorectal neoplasms. Differences in the prevalence of occult polyps in various populations might help explain the discordant reported sensitivities for polyp detection in published reports of CTC. SUBJECTS AND METHODS: Seventy-five consecutive patients who had been previously screened for polyps underwent same-day colonoscopy and CTC. Many of the patients had personal histories of previous polypectomies and were undergoing surveillance colonoscopy. The scans were interpreted prospectively by an experienced radiologist. Polyps missed prospectively on CTC were analyzed retrospectively by three experienced radiologists and categorized as perception errors (visible in retrospect), technical errors (e.g., obscured by feces or fluid), or occult (invisible). RESULTS: Thirty polyps 5 mm or larger were found at colonoscopy, 18 of which were missed prospectively on CTC. Of the 18 missed polyps, 12 could not be identified in retrospect, even though they were located in clean, dry, well-distended colonic segments. These were classified as occult. Ten of the 12 occult polyps showed flat morphology on review of colonoscopy video recordings. Of the remaining six missed polyps, two were classified as perception errors, two as technical errors, and two as a combination of technical and perception error. CONCLUSION: In this population, colonographically occult polyps were common and accounted for more detection failures than perception errors and technical errors combined. The high prevalence of occult polyps may be explained by the fact that previous screening may have led to removal of easy-to-see polyps, creating a study population with a higher percentage of hard-to-see polyps.

Aged↗
PubMed2005

Nonradiologists as second readers for intraluminal findings at CT colonography.

RATIONALE AND OBJECTIVES: Multiple trials have documented wide interobserver variability between radiologists interpreting computed tomography colonography (CTC) exams. We sought to determine if nonradiologists could learn to interpret intraluminal findings at CTC with a high degree of sensitivity to determine if they could play a role as second readers in interpreting CTC exams. MATERIALS AND METHODS: Seven nonradiologists (five medical students, two radiologic technologists) undertook self-directed CTC training using a teaching file of 50 cases; thereafter, each reader blindly interpreted 50 cases with colonoscopic correlation (30 positive, 20 negative). Results were compared with a previously studied cohort of radiologists. The two technologists additionally repeated the exam after 6 weeks of clinical experience. RESULTS: The sensitivity of nonradiologists for small (5-9 mm) polyps, large (>9 mm) lesions, and cancers was similar to that of radiologists (0.45 versus 0.63, 0.74 versus 0.71, and 0.80 versus 0.88, respectively). After 6 weeks of clinical experience as second readers, the accuracy of one technologist significantly improved (from 74% to 90%, P = .008), whereas accuracy of the other tended toward improvement (from 74% to 86%%, P = .25). Nonradiologists detected, on average, 6/36 additional polyps (17%) missed by any radiologist, and the sensitivity of 5/7 nonradiologists was significantly greater than at least one of the radiologists (P = .05). CONCLUSION: Nonradiologists can perform similarly to radiologists in interpreting intraluminal findings at CTC, with nonradiologist performance improving even after experience with more than 100 cases. Skilled nonradiologists may play a vital role as a second reader of intraluminal findings or by performing quality control of examinations before patient dismissal.

Cohort Studies↗
PubMed2005

Imaging and cancer: research strategy of the American College of Radiology Imaging Network.

The American College of Radiology Imaging Network (ACRIN) is a cooperative group funded by the National Cancer Institute and dedicated to developing and conducting clinical trials of diagnostic imaging and image-guided treatment technologies. ACRIN's six disease site committees are responsible for developing scientific strategies and resultant trials within the framework of ACRIN's five key hypotheses: (a) Screening and early detection with imaging can reduce cancer-specific mortality. (b) Less invasive image-guided therapeutic methods can reduce the mortality and morbidity associated with treating cancer. (c) Molecular-based physiologic and functional imaging can improve the diagnosis and staging of cancer, thus improving treatment. (d) Functional imaging can portray the effectiveness of treatment earlier and more accurately, thus reducing mortality and improving the likelihood of a cure. (e) Informatics and other "smart systems" can improve the evaluation of patients with cancer, thus leading to better and more effective treatments. This article details ACRIN's research strategy according to disease site through the year 2007.

Breast Neoplasms↗
PubMed2005

CT colonography: unraveling the twists and turns.

PURPOSE OF REVIEW: The performance of CT colonography has varied widely among published studies to date. This paper reviews differences in indications, populations, technique, and radiologist visualization, to elucidate the key factors that may give rise to disparate results. RECENT FINDINGS: The role of CT colonography in screening asymptomatic patients is controversial. Studies employing subjects with known neoplasms generally report higher accuracy, while studies employing surveillance subjects report lower accuracy. Technical factors that appear to be associated with higher accuracy include meticulous bowel preparation and inflation, multidetector CT, combined two- and three-dimensional visualization, and radiologist experience and proclivity. Interobserver variability and practice guidelines remain significant issues for this developing technique. Interobserver variability may be reduced in the future by computer-aided detection algorithms or the routine use of skilled second readers. CT colonography is performed routinely for some indications, as it has demonstrated superior performance to noncolonoscopic screening alternatives. SUMMARY: The disparity in results of reported large-scale CT colonography studies in asymptomatic subjects may be explained in part by differences in patient population characteristics, CT technique, and interobserver variability. CT colonography exceeds the performance of nonendoscopic approaches to colorectal cancer screening. Continuing innovation will seek to improve endoluminal visualization, reduce interobserver variability, and improve patient acceptance.

Colonic Neoplasms↗
PubMed2004

Cost-minimization analysis of MRC versus ERCP for the diagnosis of primary sclerosing cholangitis.

Investigations examining the use of magnetic resonance cholangiography (MRC) for the diagnosis of primary sclerosing cholangitis (PSC) have described comparable accuracy when compared to endoscopic retrograde cholangiopancreatography (ERCP). The effectiveness of MRC based on overall cost, however, remains unknown. Our aim was to determine the average cost per correct diagnosis using MRC or ERCP as the initial testing strategy for the diagnosis of PSC. A decision analysis model was constructed employing diagnostic test parameters prospectively determined among 73 patients with clinically suspected biliary disease. ERCP was performed within 24 hours after MRC. Cost data were derived from average Medicare reimbursement fee schedules. The prevalence of PSC in the study cohort was 32%. The sensitivity and specificity of MRC for the diagnosis of PSC were 82% and 98%, respectively. The average cost per correct diagnosis of PSC was 724.00 US dollars for initial MRC (including the cost of ERCP following a negative MRC examination) versus 793.17 US dollars for initial ERCP. In the absence of biliary obstruction, the average cost per correct diagnosis of PSC was 549.64 US dollars with MRC versus 623.25 US dollars or ERCP. The average cost of managing post-ERCP-related complications among patients with PSC was 2902.20 US dollars (range, 1915.40-5031.54 US dollars). For ERCP to be the optimal initial test strategy, a prevalence rate of PSC greater than 45%, MRC specificity less than 85%, or reduction in the average cost per diagnosis to 538.30 US dollars would be required. In conclusion, MRC has comparable accuracy to ERCP and results in cost savings when used as the initial test strategy for diagnosing PSC.

Adult↗
PubMed2004

Understanding interpretive errors in radiologists learning computed tomography colonography.

RATIONALE AND OBJECTIVES: To determine if interpretive errors in the course of learning CT colonography are secondary to failures in detection or in characterization and determine the types of lesions frequently missed. MATERIALS AND METHODS: Fifteen radiologists completed an electronic CTC training module consisting of two parts: 1) a teaching file demonstrating the varied appearances of polyps, cancers, and pitfalls in interpreting exams; and 2) a test of 50 complete CTC datasets. Following review of each test case, radiologists were asked to indicate if and where a polyp was visualized. The module then showed each neoplasm (if any) located within the dataset. For false negative examinations, radiologists indicated if the lesion was not seen, was seen but interpreted as colonic wall or fold, or was seen but interpreted as stool or fluid. RESULTS: The average sensitivity for sessile, pedunculated, and flat polyps for these novice readers was 76%, 63%, and 32%, respectively. Average sensitivity for all morphologies of cancers (annular, polypoid, flat) was high (93%, 85%, 95%), with 8/11 missed cancers being secondary to failure in detection. The most frequently missed cancer was an annular constricting tumor (5/11). Overall, 55% (73/132) of errors were failures of detection and 45% (59/132) were errors in characterization. CONCLUSION: Radiologists learning CT colonography had slightly more errors of detection than characterization, but this difference was not statistically significant. Flat and pedunculated polyps and annular constricting cancers were the most frequently missed morphologies. Examples of these abnormalities should be emphasized in CTC training programs.

Colonic Neoplasms↗
PubMed2004

Comparison of the relative sensitivity of CT colonography and double-contrast barium enema for screen detection of colorectal polyps.

BACKGROUND & AIMS: In a population reflective of a screening setting, our aim was to compare the relative sensitivity and specificity of computed tomography (CT) colonography with double-contrast barium enema (DCBE) for detection of colorectal polyps and to assess the added value of double reading at CT colonography, using endoscopy as the arbiter. METHODS: This prospective, blinded study comprised 837 asymptomatic persons at higher than average risk for colorectal cancer who underwent CT colonography followed by same-day DCBE. Examinations with polyps > or =5 mm in diameter were referred to colonoscopy. RESULTS: CT colonography readers detected 56%-79% of polyps > or =10 mm in diameter. In comparison, the sensitivity at DCBE varied between 39% and 56% for the 31 polyps > or =1 cm. All of the readers detected more polyps at CT colonography than DCBE, but the difference was statistically significant for only a single reader (P = 0.02). Relative specificity for polyps > or =10 mm on a per-patient basis ranged from 96% to 99% at CT colonography, and 99%-100% at DCBE. Doubly read CT colonography detected significantly more polyps than DCBE (81% vs. 45% for polyps > or =1 cm [P = <0.01], and 72% vs. 44% for polyps 5-9 mm [P < or = 0.01]). CONCLUSIONS: Double-read CT colonography is significantly more sensitive in detecting polyps than single-read double contrast barium enema. DCBE was significantly more specific than CT colonography.

Aged↗
PubMed2004

AGA future trends report: CT colonography.

BACKGROUND & AIMS: Computed tomographic colonography (CTC) was first described more than a decade ago. Recent advances in imaging hardware and software and results of clinical trials based on new methods for performing and interpreting images suggest that CTC may now be assessed as a method for colorectal cancer screening. METHODS: The Research Policy Committee of the American Gastroenterological Association assembled a task force to review the results of recent clinical trials and quantitative mathematical models pertaining to CTC. The goal of the task force was to assess the current knowledge about CTC and to evaluate the issues that will define its impact. RESULTS: Limitations in evaluating the current state of CTC technology include a wide variation in results of clinical trials. There are as yet insufficient data on the use of CTC in routine clinical practice. Limitations in the use of quantitative mathematical models make predictions based on such models of limited value. The cancer risk and therefore clinical importance of small colorectal polyps detected by CTC and/or nonpolypoid neoplasia not detected by CTC remains largely unknown. CONCLUSIONS: CTC is attractive as a colon imaging modality. It is therefore anticipated that CTC will have a significant impact on the practice of gastroenterology. However, the magnitude of the impact is currently unknown. Whether the ongoing implementation of CTC will increase or decrease the number of referrals for colonoscopy or shift the procedure from colorectal cancer screening to therapeutic interventions (e.g., polypectomy) is unknown at the present time. Multidisciplinary collaboration between gastroenterology and radiology to promote effective implementation and ongoing quality assurance will be important.

Advisory Committees↗
PubMed2004

CT colonography with computer-aided detection: automated recognition of ileocecal valve to reduce number of false-positive detections.

The ileocecal valve (ICV) is a common cause of false-positive detections of polyps at computed tomographic (CT) colonography with computer-aided detection (CAD). The authors developed a CAD algorithm for differentiating the ICV from a true polyp and evaluated this algorithm by using two colonoscopy-confirmed CT colonography data sets. Data sets 1 and 2 consisted of the data obtained at CT colonographic examinations performed in 20 and 40 patients, respectively. Forty of these patients had at least one polyp 1 cm or larger. For data set 1, the proposed ICV recognition algorithm eliminated three of nine (33%; 95% confidence interval [CI]: 8%, 70%) false-positive CAD detections that were attributable to the ICV and none of the true-positive polyp detections. For data set 2, with use of identical parameters, the algorithm eliminated 11 of 18 (61%; 95% CI: 36%, 83%) false-positive detections that were attributable to the ICV and none of the true-positive detections. The thresholds used to recognize the ICV were a mean internal CT attenuation of less than -124 HU and a volume of greater than 1.5 cm(3). The proposed algorithm successfully recognized the ICV and eliminated it in some cases. This result is clinically important because, by reducing the frequency of a common cause of false-positive detections, this algorithm may improve the efficiency of physicians who use CAD.

Adult↗