The diagnostic value of multiplanar reconstruction on MDCT colonography for the preoperative staging of colorectal cancer

Predictive value of lesion morphology in rectal cancer based on MRI before surgery

OBJECTIVE

To explore the relationship of MRI morphology of primary rectal cancer with extramural vascular invasion (EMVI), metastasis and local recurrence.

MATERIALS AND METHODS

This retrospective study included 153 patients with rectal cancer. Imaging factors and histopathological index including nodular projection (NP), cord sign (CS) at primary tumor margin, irregular nodules (IN) of mesorectum, MRI-detected peritoneal reflection invasion (PRI), range of rectal wall invasion (RRWI), patterns and length of tumor growth, maximal extramural depth (EMD), histologically confirmed local node involvement (hLN), MRI T stage, MRI N stage, MRI-detected extramural vascular invasion (mEMVI) and histologically confirmed extramural vascular invasion (hEMVI) were evaluated. Determining the relationship between imaging factors and hEMVI, synchronous metastasis and local recurrence by univariate analysis and multivariable logistic regression, and a nomogram validated internally via Bootstrap self-sampling was constructed based on the latter.

RESULTS

Thirty-eight cases of hEMVI, fourteen cases of synchronous metastasis and ten cases of local recurrence were observed among 52 NP cases. There were 50 cases of mEMVI with moderate consistency with hEMVI (Kappa = 0.614). NP, CS, EMD and mEMVI showed statistically significant differences in the negative and positive groups of hEMVI, synchronous metastasis, and local recurrence. Compared to patients with local mass growth, the rectal tumor with circular infiltration had been found to be at higher risk of synchronous metastasis and local recurrence (P < 0.05). NP and IN remained as significant predictors for hEMVI, and mEMVI was a predictor for synchronous metastasis, while PRI and mEMVI were predictors for local recurrences. The nomogram for predicting hEMVI demonstrated a C-index of 0.868, sensitivity of 86.0%, specificity of 79.6%, and accuracy of 81.7%.

CONCLUSION

NP, CS, IN, large EMD, mEMVI, and circular infiltration are significantly associated with several adverse prognostic indicators. The nomogram based on NP has good predictive performance for preoperative EMVI. mEMVI is a risk factor for synchronous metastasis. PRI and mEMVI are risk factors for local recurrence.

Radiologic T staging of colon cancer: renewed interest for clinical practice

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Factors associated with pericolic fat stranding of colon cancer on computed tomography colonography

Background

Pericolic fat stranding on computed tomography (CT) scans has been an important feature for staging colon cancer. However, the factors associated with pericolic fat stranding have not been elucidated to date.

Purpose

To determine factors associated with pericolic fat stranding of colon cancer on CT colonography (CTC).

Material and Methods

Overall, 150 patients with 155 colon cancer lesions were retrospectively assessed by two radiologists for pericolic fat stranding on CTC. Circumferential proportion of the tumor (CPtumor; <50%, 50–75%, and ≥75%), longitudinal length, depth of invasion (≤T2, T3, T4), lymph node and distant metastasis, and lymphovascular invasion were recorded. Univariate and multivariate logistic regression analyses were performed between pericolic fat stranding and each factor. Multi-group comparisons were performed for the CPtumor and depth of invasion.

Results

Pericolic fat stranding was identified in 57 lesions (36.8%). Univariate analysis revealed significant associations of pericolic fat stranding with all factors (P < 0.027), except for lymph node metastasis (P = 0.087). Multi-group comparisons revealed that pericolic fat stranding was more frequent with increasing CPtumor (P < 0.001); however, no significant differences were observed beyond subserosal infiltration (P = 0.225). Logistic regression analysis revealed the CPtumor (<75% vs. ≥75%; P = 0.008, <50% vs. 50–75%; P = 0.047) and longitudinal length (P = 0.001) as explainable variables.

Conclusion

Pericolic fat stranding identified on CT images of colon cancer is demonstrated more frequently with increasing circumferential proportion of the tumor and longitudinal length.

CT volumetric measurement of colorectal cancer helps predict tumor staging and prognosis

Purpose

To evaluate feasibility of CT colonography (CTC) volumetry of colorectal cancer (CRC) and its correlation with disease stage and patients’ survival.

Materials and methods

CTC volumetry was performed for 126 patients who underwent preoperative CTC. Reproducibility of tumor volume (Tvol) between two readers was assessed. One-way ANOVA and ROC analysis evaluated correlation between Tvol and pTNM staging. ROC analysis compared diagnostic performance to predict pTNM staging between Tvol and radiologist. Kaplan-Meier test compared overall survival.

Results

Reproducibility among readers was excellent (interclass correlation = 0.9829). Mean Tvol showed an incremental trend with T stage and Tvol of pT4b stage was significantly larger than other stages (P<0.0001). Az value (0.780) of Tvol to predict pT4b stage was significantly larger than that (0.591) of radiologist (P = 0.004). However, Tvol was not significantly different according to pN stage. Az values (0.723~0.857) of Tvol to predict M1 or M1b were comparable to those (0.772~0.690) of radiologist (P>0.05). Smaller tumor burden (≤12.85cm³), ≤T3, N0, M0 stages, and curative surgery were significantly associated with patients’ longer survival (P<0.05).

Conclusion

CT volumetry has a limited value to predict N stage; however, it may outperform the radiologist’s performance when predicting pT4b and M1b stage and can be a useful prognostic marker.

Diagnostic Accuracy of CT for Local Staging of Colon Cancer: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this article is to determine the accuracy of CT in the detection of tumor invasion beyond the bowel wall and nodal involvement of colon carcinomas. A literature search was performed to identify studies describing the accuracy of CT in the staging of colon carcinomas. Studies including rectal carcinomas that were inseparable from colon carcinomas were excluded. Publication bias was explored by using a Deeks funnel plot asymmetry test. A hierarchic summary ROC model was used to construct a summary ROC curve and to calculate summary estimates of sensitivity, specificity, and diagnostic odds ratios (ORs).

CONCLUSION

On the basis of a total of 13 studies, pooled sensitivity, specificity, and diagnostic ORs for detection of tumor invasion beyond the bowel wall (T3-T4) were 90% (95% CI, 83-95%), 69% (95% CI, 62-75%), and 20.6 (95% CI, 10.2-41.5), respectively. For detection of tumor invasion depth of 5 mm or greater (T3cd-T4), estimates from four studies were 77% (95% CI, 66-85%), 70% (95% CI, 53-83%), and 7.8 (95% CI, 4.2-14.2), respectively. For nodal involvement (N+), 16 studies were included with values of 71% (95% CI, 59-81%), 67% (95% CI, 46-83%), and 4.8 (95% CI, 2.5-9.4), respectively. Two studies using CT colonography were included with sensitivity and specificity of 97% (95% CI, 90-99%) and 81% (95% CI, 65-91%), respectively, for detecting T3-T4 tumors. CT has good sensitivity for the detection of T3-T4 tumors, and evidence suggests that CT colonography increases its accuracy. Discriminating between T1-T3ab and T3cd-T4 cancer is challenging, but data were limited. CT has a low accuracy in detecting nodal involvement.

Usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer

PURPOSE

To demonstrate the usefulness of hydrogel-CT for detecting and staging of rectosigmoid colon cancer.

MATERIALS AND METHODS

Fifty-four patients with rectosigmoid colon cancers underwent routine CT without (n=27) and with (n=27) rectum distension using a sonographic gel. Rectum distensibility and tumor visualization were evaluated. T and N stages on CT independently recorded by two radiologists were correlated with pathologic staging. Staging accuracies were compared using Fisher's exact test. Diagnostic performances in differentiating <T3 from ≥T3 and N0 from ≥N1 were evaluated using areas under the receiver operating characteristic curves (AZ).

RESULTS

Rectum distensibility (3.52) and tumor visualization (3.70) were significantly more scored in the distended group than in the control group (1.44 and 2.04) (P<0.0001). Pathologic and CT staging were more correlated in the distended group in both reviewers. Accuracy for staging was higher in the distended group (T: 50-85.2%/N: 59.3-92.6%) than in the control group (T: 45.5-62.5%/N: 33.3-59.3%) without statistical significance except N staging for reviewer 2 (P=0.0091). AZ values for T and N staging in the distended group (T: 0.827-0.989/N: 0.858-0.980) were also higher than in the control group (T: 0.817-0.907/N: 0.544-0.654).

CONCLUSION

Hydrogel-CT can provide better diagnostic performance for T and N staging of rectosigmoid colon cancer.

Impact of contrast-enhanced computed tomography colonography on laparoscopic surgical planning of colorectal cancer

AIM

To evaluate the impact of contrast-enhanced computed tomography colonography (CE-CTC) on laparoscopic surgery planning in patient with stenosing colorectal cancer.

MATERIALS AND METHODS

Sixty-nine patients with endoscopically proven colorectal cancer underwent CE-CTC, after incomplete conventional colonoscopy. Two experienced radiologists evaluated site, length, and TNM staging of colorectal cancers on three-dimensional double contrast enema-like views, 2D axial and multiplanar reconstructions. All the patients underwent colorectal resection and surgery bulletin, pathology of surgical specimens, and radiological follow-up at about 8 months were used as reference standard.

RESULTS

The detection rate of colorectal cancer was 100 % (75/75); CE-CTC allowed for a diagnosis of a synchronous colorectal cancer in five patients (7 %). CE-CTC correctly judged the site of the lesions in all the cases; clinically significant localization errors at conventional colonoscopy were noted in 3 out of 69 patients (4 %). Additional colonic polyps greater than 6 mm in diameter were found in 21 out of 69 patients (30 %); in two patients (3 %) the surgeon performed an enlarged colectomy to include synchronous polyps proximal to colorectal cancer. Sensitivity, specificity, PPV, NPV, and accuracy were for T1-T2 vs. T3-T4: 96 %, 71 %, 92 %, 87 %, and 91 %, respectively; for N: 94 %, 42 %, 64 %, 86 %, and 70 %; for M: 100 %, 100 %, 83 %, 100 %, and 97 %. There were no complications associated with CE-CTC.

CONCLUSION

Information given by CE-CTC concerning colorectal cancer location and synchronous colonic cancers and polyps changed the laparoscopic surgical strategy in almost 14 % of patients.

CT findings of gallbladder metastases: emphasis on differences according to primary tumors

Objective

To describe computed tomography (CT) features of metastatic gallbladder (GB) tumors (MGTs) from various primary tumors and to determine whether there are differential imaging features of MGTs according to different primary tumors.

Materials and Methods

Twenty-one patients who had pathologically confirmed MGTs and underwent CT were retrospectively enrolled. Clinical findings including presenting symptoms, type of surgery, and interval between primary and metastatic tumors were recorded. Histologic features of primary tumor and MGTs including depth of invasion were also reviewed. Imaging findings were analyzed for the location and morphology of MGTs, pattern and degree of enhancement, depth of invasion, presence of intact overlying mucosa, and concordance between imaging features of primary and metastatic tumors. Significant differences between the histologies of MGTs and imaging features were determined.

Results

The most common primary tumor metastasized to the GB was gastric cancer (n = 8), followed by renal cell carcinoma (n = 4) and hepatocellular carcinoma (n = 3). All MGTs (n = 21) manifested as infiltrative wall thickenings (n = 15) or as polypoid lesions (n = 6) on CT, similar to the features of primary GB cancers. There were significant differences in the morphology of MGTs, enhancement pattern, enhancement degree, and depth of invasion according to the histology of primary tumors (p < 0.05). Metastatic adenocarcinomas of the GB manifested as infiltrative and persistently enhancing wall thickenings, while non-adenocarcinomatous metastases usually manifested as polypoid lesions with early wash-in and wash-out.

Conclusion

Although CT findings of MGTs are similar to those of primary GB cancer, they are significantly different between the various histologies of primary tumors.

CT colonography in the diagnosis and management of colorectal cancer: Emphasis on pre- and post-surgical evaluation

This article addresses the use of computed tomographic colonography (CTC) for the diagnosis and management of colorectal cancer, focusing on presurgical evaluation of the colon proximal to an occlusive cancer and surveillance after cancer resection surgery. The key evidences accumulated in the literature and future work needed are summarized. CTC is a technically robust and the most practical method to evaluate the colon proximal to an occlusive cancer, which prevents colonoscopic examination past the occlusion, either before or after metallic stent placement. The high sensitivity of CTC for detecting cancers and advanced adenomas in the proximal colon can help prevent additional surgical procedures in patients showing negative results. However, the accuracy of CTC for distinguishing intramural cancers from adenomas is low, and the technique is limited in guiding management when a medium-sized lesion that do not show invasive features such as pericolic extension or nodal metastasis is found in the proximal colon. A maximal diameter ≥ 15 mm has been proposed as a criterion for surgical removal of proximal lesions. However, this needs to be verified in a larger cohort. In addition, the influence of presurgical CTC results on the current post-cancer resection colonic surveillance timeline remains to be determined. CTC can be readily added to the routine abdominopelvic CT in the form of contrast-enhanced CTC, which can serve as an effective stand-alone tool for post-cancer resection surveillance of both the colorectum and extracolonic organs. Although the accuracy of CTC has been demonstrated, its role in the current colonoscopy-based postoperative colonic surveillance protocols remains to be determined. Readers of CTC also need to be knowledgeable on the colonic lesions that are unique to the postoperative colon.

Contrast-enhanced computed tomography colonography in preoperative distinction between T1-T2 and T3-T4 staging of colon cancer

RATIONALE AND OBJECTIVES

To predict the T stage of nonrectal colon cancer using contrast-enhanced computed tomography colonography.

MATERIALS AND METHODS

Sixty-one patients with 67 nonrectal colon cancers consecutively underwent contrast-enhanced computed tomography colonography after an incomplete colonoscopy. Two readers evaluated wall deformity and perilesional fat abnormality on three-dimensional double contrast enema-like views and multiplanar reconstructions. Pathology was used as the standard of reference. McNemar, Fisher, and Cohen κ statistics were used.

RESULTS

At pathologic examination, we found the following stages: T1 (n = 5), T2 (n = 10), T3 (n = 41), T4a (n = 6), and T4b (n = 5). Intraobserver and interobserver reproducibilities were almost perfect for wall deformity (κ = 1.00 and κ = 0.88, respectively), substantial for perilesional fat abnormality (κ = 0.79 and κ = 0.74, respectively). Using the results of the more experienced reader, accuracy of wall deformity ≥50% (apple-core) alone for T ≥ 3 was 62 of 67 (0.93, 95% confidence interval [CI] 0.83-0.97) and that of perilesional fat abnormality alone was 37 of 67 (0.55, 95% CI 0.43-0.67) (P < .001). Predictive value for ≥ T3 of the association wall deformity ≥50% with perilesional fat abnormality was 22 of 22 (1.00, 95% CI 0.85-1.00), higher, but not significantly, than that of wall deformity ≥50% with normal perilesional fat 29 of 33 (0.88, 95% CI 0.72-0.97) (P = .148, Fisher exact test).

CONCLUSIONS

The presence of apple-core wall deformity, regardless of perilesional fat abnormality, is highly predictive of stage T3 or higher.

Diagnostic precision of CT in local staging of colon cancers: a meta-analysis

AIM

To determine the accuracy of computed tomography (CT) in detecting disease with invasion beyond the muscularis propria (MP) and malignant lymph nodes.

MATERIALS AND METHODS

A literature search of Ovid, Embase, the Cochrane database, and Medline using Pubmed, Google Scholar and Vivisimo search engines was performed to identify studies reporting on the accuracy of CT to predict the staging of colonic tumours. Publication bias was demonstrated by Funnel plots. The sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated using a bivariate random effects model and hierarchical summary operating curves (HSROC) were generated.

RESULTS

Nineteen studies fulfilled all the necessary inclusion criteria. The pooled sensitivity, specificity, DOR for detection of tumour invasion were 86% (95% CI: 78-92%); 78% (95% CI: 71-84%); 22.4 (95% CI: 11.9-42.4). Similarly, the values for nodal detection were 70% (95% CI: 63-73%); 78% (95% CI: 73-82%); 8.1(95% CI: 4.7-14.1). In the subgroup analysis, the best results were obtained in studies utilizing multidetector CT (MDCT).

CONCLUSION

Preoperative staging CT accurately distinguishes between tumours confined to the bowel wall and those invading beyond the MP; however, it is significantly poorer at identifying nodal status. MDCT provides the best results.

Are multiplanar reconstructions necessary in routine body computed tomography practice?: what is the published evidence?

OBJECTIVE

During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume.

CONCLUSIONS

Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

Staging chest radiography is not useful in patients with colorectal cancer

INTRODUCTION

International guidelines recommend a staging chest X-ray (SCXR) in patients with colorectal cancer to exclude pulmonary metastases. The SCXR is controversial, because evidence to support its use is insufficient. The aim of this study was to determine the value of the SCXR in patients with colorectal cancer.

PATIENTS AND METHODS

Between January 1992 and August 2006, data from all patients with colorectal cancer, who presented to the surgical clinic of the Maasland Hospital, were prospectively collected and analysed. The main outcome was the rate of pulmonary metastases on SCXR. The secondary outcome was the influence of SCXR on patient management.

RESULTS

Out of 1410 patients, 1057 had a chest X-ray before their operation. Median follow-up time was 4 years and 6 months (25th percentile 1 year and 7 months, 75th percentile 6 years and 11 months). Eight patients were excluded because follow-up data were incomplete. In 24 patients the chest X-ray was suggestive of malignancy; 9 of these patients actually had pulmonary metastases. Patient management was changed in 5 of them. Four patients were identified to have primary lung cancer. These data indicate a 0.86% detection rate of pulmonary metastases (confidence interval, 0.3-1.4%).

DISCUSSION

Our results show that SCXR has a low detection rate of pulmonary metastases and a small influence on patient management. In accordance with previous studies our data do not support the routine use of the SCXR in patients with colorectal cancer.

Preoperative staging of colorectal cancer: CT vs. integrated FDG PET/CT

Accurate preoperative staging is essential in determining the optimal therapeutic planning for individual patients. The computed tomography (CT) in the preoperative staging of colorectal cancer, even if controversial, may be useful for planning surgery and/or neoadjuvant therapy, particularly when local tumor extension into adjacent organs or distant metastases are detected. There have been significant changes in the CT technology with the advent of multi-detector row CT (MDCT) scanner. Advances in CT technology have raised interest in the potential role of CT for detection and staging of colorectal cancer. In recent studies, MDCT with MPR images has shown promising accuracy in the evaluation of local extent and nodal involvement of colorectal cancer. Combined PET/CT images have significant advantages over either alone because it provides both functional and anatomical data. Therefore, it is natural to expect that PET/CT would improve the accuracy of preoperative staging of colorectal cancer. The most significant additional information provided by PET/CT relates to the accurate detection of distant metastases. For the evaluation of patients with colorectal cancer, CT has relative advantages over PET/CT in regard to the depth of tumor invasion through the wall, extramural extension, and regional lymph node metastases. PET/CT should be performed on selected patients with suggestive but inconclusive metastatic lesions with CT. In addition, PET/CT with dedicated CT protocols, such as contrast-enhanced PET/CT and PET/CT colonography, may replace the diagnostic CT for the preoperative staging of colorectal cancer.

Accuracy of preoperative T-staging of gallbladder carcinoma using MDCT

OBJECTIVE

The objective of our study was to evaluate the performance of MDCT in the preoperative T-staging of gallbladder cancer and to determine whether adding multiplanar reconstruction (MPR) images to axial images can improve the accuracy of MDCT for the T-staging of gallbladder cancer.

MATERIALS AND METHODS

Two abdominal radiologists retrospectively reviewed by consensus axial images of portal phase MDCT scans of 118 patients who had pathologically confirmed gallbladder cancers; they then reviewed the axial and MPR images from 53 of the 118 patients who had undergone MPR imaging. Local disease spread was evaluated according to the TNM system, and the results were compared with the pathologic findings using the McNemar test. The MDCT performance to differentiate each T-stage was evaluated using Fisher's exact test.

RESULTS

The sensitivities of the ability to differentiate the < or = T1 versus > or = T2 lesions, < or = T2 versus > or = T3 lesions, and < or = T3 versus T4 lesions were 79.3%, 92.7%, and 100%, respectively; the specificities were 98.8%, 86%, and 100%, respectively (p < 0.0001). The overall accuracy for the T-stage was 83.9%. In the 53 patients with MPR images, the combined reading of the axial and MPR images increased the diagnostic accuracy compared with axial image reading only from 71.7% to 84.9%, a statistically significant degree (p = 0.0233).

CONCLUSION

MDCT provided 83.9% accuracy in the diagnosis of the local extent of gallbladder carcinomas, thereby showing acceptable sensitivity and specificity. The addition of MPR images to the axial CT data increased the accuracy.

Incomplete colonoscopy in patients with occlusive colorectal cancer: usefulness of CT colonography according to tumor location

PURPOSE

We sought to evaluate the clinical usefulness of CT colonography (CTC) after incomplete conventional colonoscopy (CC) for occlusive colorectal cancer (CRC) according to the tumor location.

MATERIALS AND METHODS

Seventy-five patients with occlusive CRC underwent subsequent CTC immediately after incomplete CC. Fifty-nine patients had distal CRC and 16 had proximal colon cancer. Experienced radiologists prospectively analyzed the location, length, and TNM staging of the main tumor. The colorectal polyps in the remaining colorectum and additional extraluminal findings were also recorded. Sixty-seven patients underwent colorectal resection. We retrospectively analyzed the surgical outcome and correlated CTC and CC findings.

RESULTS

The overall accuracies of tumor staging were: T staging, 86%; N staging (nodal positivity), 70% (80%); and intra-abdominal M staging, 94%. Additional colonic polyps were found in 23 patients. Six synchronous carcinomas were detected (9%); three in the proximal colon and three in the distal colon of occlusion. Clinically significant localization errors at CC were noted in 8 patients (12%, 5 proximal colon cancers and 3 distal CRCs) and were corrected by CTC. After CTC, the surgeons modified the initial surgical plan in 11 cases (16%).

CONCLUSION

In occlusive CRC, CTC is not only useful in the evaluation of the proximal bowel, but can also provide surgeons with accurate information about staging and tumor localization. CTC is recommended when endoscopists encounter occlusive CRC, regardless of tumor location.

Volume CT: State-of-the-Art Reporting

OBJECTIVE

CT has undergone generational change that has led to true volume imaging. Interpretation of volume images requires interaction between the radiologist and the volume data sets. The aim of this review is to examine postprocessing options and the evidence in the literature for changing the process of reporting to digital volume reporting.

CONCLUSION

Diagnostic confidence and the accuracy of interpretation of volume CT images have increased with improvements in postprocessing techniques.

Computer-aided detection in CT colonography: initial clinical experience using a prototype system

Computer-aided detection (CAD) algorithms help to detect colonic polyps at CT colonography (CTC). The purpose of this study was to evaluate the accuracy of CAD versus an expert reader in CTC. One hundred forty individuals (67 men, 73 women; mean age, 59 years) underwent screening 64-MDCT colonography after full cathartic bowel cleansing without fecal tagging. One expert reader interpreted supine and prone scans using a 3D workstation with integrated CAD used as "second reader." The system's sensitivity for the detection of polyps, the number of false-positive findings, and its running time were evaluated. Polyps were classified as small (< or =5 mm), medium (6-9 mm), and large (> or =10 mm). A total of 118 polyps (small, 85; medium, 19; large, 14) were found in 56 patients. CAD detected 72 polyps (61%) with an average of 2.2 false-positives. Sensitivity was 51% (43/85) for small, 90% (17/19) for medium, and 86% (12/14) for large polyps. For all polyps, per-patient sensitivity was 89% (50/56) for the radiologist and 73% (41/56) for CAD. For large and medium polyps, per-patient sensitivity was 100% for the radiologist, and 96% for CAD. In conclusion, CAD shows high sensitivity in the detection of clinically significant polyps with acceptable false-positive rates.