Per-patient Sensitivity Research Articles

Accuracy of CT Colonography for Detection of Large Adenomas and Cancers

Although recognition and curative treatment of both precursor adenomas and localized cancers are possible through early-detection, and regular screening reduces mortality from colorectal cancer, screening is largely underused. Reasons for underuse include performance drawbacks and issues of comfort, availability, and expense. Computed tomographic (CT) colonography is an alternative that provides minimally invasive, structural evaluation of the entire colorectum, and permits rapid imaging of the entire colorectum without sedation, and with few procedure-related complications. Its effectiveness in detecting asymptomatic colorectal lesions in previous studies is controversial, in large part because of differences in patient populations, imaging techniques, and radiologists' qualifications. This large prospective trial compared the accuracy of CT colonography in detecting histologically confirmed, large colorectal adenomas and cancers (≥10 mm in diameter), with findings on screening colonoscopy and histologic review, the reference standard. A total of 2600 asymptomatic patients 50 years of age or older scheduled to undergo routine colonoscopy were recruited at 15 clinical sites between 2005 and 2006. Lesions measuring 5 mm or more in diameter were identified by radiologists trained in CT colonography. The preparation for CT colonography included stool and liquid tagging, laxative purgation, and colonic insufflation. Examinations were performed with multidetector-row CT scanners with a minimum of 16 rows. Complete data were available for 2512 participants examined with CT colonography and colonoscopy on the same day. For adenomas and cancers ≥10 mm, the mean (± SE) per-patient estimates of several measured parameters were as follows: sensitivity (0.90 ±.06); specificity (0.86 ±.05), positive (0.23 ±.04) and negative (0.99 ± <.01) predictive values, and area under the receiver-operating-characteristic curve for CT colonography (0.89 ±.04). The estimated sensitivity of 0.90 for identifying patients with adenomas or cancers ≥10 mm indicates failure of CT colonography to identify large lesion(s) detected by colonoscopy in 10% of patients. The per-patient sensitivity for detecting lesions 6 to 9 mm in diameter was 0.78 ±.07. The per-polyp sensitivity for detecting lesions ≥10 mm was 0.84 ±.04. These data show that CT colonographic screening identified 90% of asymptomatic adults with adenomas and cancers ≥10 mm in diameter that were detected by screening colonoscopy. For smaller lesions (6 to 9 mm), the sensitivity was lower (78%).

Diagnostic Accuracy and Impact of Computed Tomographic Coronary Angiography on Utilization of Invasive Coronary Angiography

Computed tomographic coronary angiography (CTA), given its high negative predictive value, is a potential gatekeeper for invasive coronary angiography (ICA). Before CTA can be further accepted into clinical practice, its impact on healthcare resources needs to be better understood. We sought to determine the clinical impact of CTA on ICA referrals, CTA accuracy, and normalcy rate. To determine the impact of CTA, consecutive patients (n=7017) undergoing ICA before and after implementing a dedicated cardiac CT program were reviewed and compared with 3 other centers (n=11 508). To determine CTA accuracy, we evaluated consecutive CTA patients who underwent ICA. For normalcy rate, we identified patients with a low pretest probability for obstructive coronary artery disease. With the implementation of a cardiac CT program, the frequency of normal ICA decreased from 31.5% (1114 of 3538 patients) to 26.8% (932 of 3479 patients) (P<0.001). These findings were significantly different (P=0.003) from the 3 centers, in which normal ICAs were unchanged (30.0% [1870 of 6224 patients] to 31.0% [1642 of 5284 patients]). CTA had excellent per-patient sensitivity (99% [CI, 95% to 100%]), positive predictive value (92% [CI, 86% to 96%]) and negative predictive value (95% [CI, 72% to 100%]). Because of referral bias, specificity (64% [CI, 44% to 81%]) was low; however, the normalcy rate of CTA was 94% (CI, 90% to 97%). After adjusting for referral bias, the adjusted sensitivity was 90% (CI, 89% to 91%), and the adjusted specificity was 95% (CI, 94% to 96%), with positive and negative predictive values of 92% (CI, 91% to 93%) and 93% (CI, 92% to 94%), respectively. The clinical implementation of CTA appears to positively impact ICA by reducing the frequency of normal ICA. The operating characteristics of CTA support its potential role as a tool useful in ruling out obstructive coronary artery disease.

Does a computer-aided detection algorithm in a second read paradigm enhance the performance of experienced computed tomography colonography readers in a population of increased risk?

We prospectively determined whether computer-aided detection (CAD) could improve the performance characteristics of computed tomography colonography (CTC) in a population of increased risk for colorectal cancer. Therefore, we included 170 consecutive patients that underwent both CTC and colonoscopy. All findings >or=6 mm were evaluated at colonoscopy by segmental unblinding. We determined per-patient sensitivity and specificity for polyps >or=6 mm and >or=10 mm without and with computer-aided detection (CAD). The McNemar test was used for comparison the results without and with CAD. Unblinded colonoscopy detected 50 patients with lesions >or=6 mm and 25 patients with lesions >or=10 mm. Sensitivity of CTC without CAD for these size categories was 80% (40/50, 95% CI: 69-81%) and 64% (16/25, 95% CI: 45-83%), respectively. CTC with CAD detected one additional patient with a lesion >or=6 mm and two with a lesion >or=10 mm, resulting in a sensitivity of 82% (41/50, 95% CI: 71-93%) (p = 0.50) and 72% (18/25, 95% CI: 54-90%) (p = 1.0), respectively. Specificity without CAD for polyps >or=6 mm and >or=10 mm was 84% (101/120, 95% CI: 78-91%) and 94% (136/145, 95% CI: 90-98%), respectively. With CAD, the specificity remained (nearly) unchanged: 83% (99/120, 95% CI: 76-89%) and 94% (136/145, 95% CI: 90-98%), respectively. Thus, although CTC with CAD detected a few more patients than CTC without CAD, it had no statistically significant positive influence on CTC performance.

Abstract 5802: Whole-Heart Coronary Angiography using Volume Computed Tomography in Comparison to Conventional Coronary Angiography

This is an initial report on the use of the recently introduced whole-heart 320-slice computed tomography (CT) scanner for noninvasive coronary angiography compared with conventional coronary angiography (CCA). Whole-heart CT avoids overscanning and overranging as necessary for helical coronary CT acquisitions thereby significantly reducing the effective radiation dose. Twelve patients with suspected coronary artery disease (4 women, 8 men; mean age 64.6 ± 11 years) have undergone coronary CT angiography using a 320-slice scanner (Aquilion ONE, Toshiba; 0.35 s gantry rotation time, 120 kV, and 350 – 450 mA) prior to clinically indicated CCA. CT images were manually reconstructed in motion-free phases with 0.5-mm slice thickness and 0.25-mm slice increment. Independent blinded assessment of CT and CCA (using quantitative analysis) was performed to detect significant (at least 50%) diameter stenoses. Of the 12 patients, in 8 patients, single-heart beat CT acquisition was performed, resulting in an effective dose of 5.6 ± 1.1 mSv and an image reconstruction window length of 175 msec. In the other 4 patients, because of higher heart rates, 2 or 3 heart beats were used for acquisition, resulting in higher radiation exposure (on average 17 mSv) and the possibility to perform multisegment reconstruction with improved temporal resolution (88 and 58 msec image reconstruction windows, respectively). Per-patient sensitivity and specificity for CT compared to CCA were 100%. Per-vessel sensitivity and specificity were 88% and 95%, respectively. Intraindividual comparison of CT with CCA revealed a nonsignificantly smaller effective radiation dose (9.4 ± 7.2 mSv vs. 10.5 ± 5.3 mSv, p&lt;0.69) but significantly smaller contrast agent amount (80 ±0 ml vs. 107.3 ± 17.8 ml, p&lt;0.01) for 320-slice CT. Whole-heart CT significantly reduces the contrast agent amount compared to CCA while radiation exposure is reduced in patients with slow heart rates. This initial report also indicates that diagnostic accuracy of coronary CT angiography using up to 320 simultaneous detector rows remains high as compared with CCA as the reference standard.

Accuracy of CT Colonography for Detection of Large Adenomas and Cancers

Computed tomographic (CT) colonography is a noninvasive option in screening for colorectal cancer. However, its accuracy as a screening tool in asymptomatic adults has not been well defined. We recruited 2600 asymptomatic study participants, 50 years of age or older, at 15 study centers. CT colonographic images were acquired with the use of standard bowel preparation, stool and fluid tagging, mechanical insufflation, and multidetector-row CT scanners (with 16 or more rows). Radiologists trained in CT colonography reported all lesions measuring 5 mm or more in diameter. Optical colonoscopy and histologic review were performed according to established clinical protocols at each center and served as the reference standard. The primary end point was detection by CT colonography of histologically confirmed large adenomas and adenocarcinomas (10 mm in diameter or larger) that had been detected by colonoscopy; detection of smaller colorectal lesions (6 to 9 mm in diameter) was also evaluated. Complete data were available for 2531 participants (97%). For large adenomas and cancers, the mean (+/-SE) per-patient estimates of the sensitivity, specificity, positive and negative predictive values, and area under the receiver-operating-characteristic curve for CT colonography were 0.90+/-0.03, 0.86+/-0.02, 0.23+/-0.02, 0.99+/-<0.01, and 0.89+/-0.02, respectively. The sensitivity of 0.90 (i.e., 90%) indicates that CT colonography failed to detect a lesion measuring 10 mm or more in diameter in 10% of patients. The per-polyp sensitivity for large adenomas or cancers was 0.84+/-0.04. The per-patient sensitivity for detecting adenomas that were 6 mm or more in diameter was 0.78. In this study of asymptomatic adults, CT colonographic screening identified 90% of subjects with adenomas or cancers measuring 10 mm or more in diameter. These findings augment published data on the role of CT colonography in screening patients with an average risk of colorectal cancer. (ClinicalTrials.gov number, NCT00084929; American College of Radiology Imaging Network [ACRIN] number, 6664.)

Comparison of 6-18F-Fluorodopamine PET with 123I-Metaiodobenzylguanidine and 111In-Pentetreotide Scintigraphy in Localization of Nonmetastatic and Metastatic Pheochromocytoma

We compared functional imaging modalities including PET with 6-(18)F-fluorodopamine ((18)F-DA) with (123)I-metaiodobenzylguanidine ((123)I-MIBG) and somatostatin receptor scintigraphy (SRS) with (111)In-pentetreotide in nonmetastatic and metastatic pheochromocytoma (PHEO). We studied 25 men and 28 women (mean age +/- SD, 44.2 +/- 14.2 y) with biochemically proven nonmetastatic (n = 17) or metastatic (n = 36) PHEO. Evaluation included anatomic imaging with CT or MRI and functional imaging that included at least 2 nuclear medicine modalities: (18)F-DA PET, (123)I-MIBG scintigraphy, or SRS. Sensitivity of functional imaging versus anatomic imaging was assessed on a per-patient and a per-region basis. For this available cohort, on a per-patient basis overall sensitivity (combined for nonmetastatic and metastatic PHEO) was 90.2% for (18)F-DA PET, 76.0% for (123)I-MIBG scintigraphy, and 22.0% for SRS. On a per-region basis, overall sensitivity was 75.4% for (18)F-DA PET, 63.4% for (123)I-MIBG scintigraphy, and 64.0% for SRS. If available, (18)F-DA PET should be used in the evaluation of PHEO, because it is more sensitive than (123)I-MIBG scintigraphy or SRS. If (18)F-DA PET is not available, (123)I-MIBG scintigraphy (for nonmetastatic or adrenal PHEO) and SRS (for metastatic PHEO) should be the first alternative imaging methods to be used.

The Efficacy of Intravenous Contrast-enhanced 16-raw Multidetector CT Colonography for Detecting Patients With Colorectal Polyps in an Asymptomatic Population in Korea

The purpose of this study is to compare the sensitivity of computed tomography (CT) colonography (CTC) with that of colonoscopy for detecting patients with colorectal polyps in an asymptomatic screening population in Korea, thus to evaluate a possibility, whether CTC could be used as a screening tool for colorectal polyps. A total of 241 asymptomatic adults underwent intravenous contrast-enhanced CTC and colonoscopy successively on the same day. Bowel preparation was performed by 4 L of polyethylene glycol (n=172) or 90 mL of sodium phosphate (n=69). The CTC findings were released to the colonoscopists after the first examination of each segment, a procedure known as segmental unblinded colonoscopy, and were used as the reference standard. The diagnostic performance of CTC for colorectal polyps was calculated. The per-patient sensitivities of CTC were 68.5% (37/54) and 86.7% (13/15) for polyp > or = 6 and > or = 10 mm, inferior to those of colonoscopy, 92.6% (50/54) and 100% (15/15), respectively. The per-polyp sensitivities of CTC were 60.4% (61/101) and 72.7% (16/22) for polyp > or = 6 and > or = 10 mm, respectively. The low sensitivity of CTC was related with flat morphology. CTC detected only 37.5% (9/24) of flat polyps > or = 6 mm. Bowel preparation by sodium phosphate further decreased the positive predictive value and specificity than by polyethylene glycol. Screening by CTC with asymptomatic population was not promising in Korea despite using advanced CT technology (16-row detector). Bowel preparation was one of the key determinants of the specificity of CTC.

Performance of a Previously Validated CT Colonography Computer-Aided Detection System in a New Patient Population

A computer-aided detection (CAD) system with high sensitivity in the detection of adenomatous polyps in varied CT colonography (CTC) data sets increases the utility of CAD in the clinical setting. The purpose of this study was to evaluate the standalone performance of an existing CAD system with a new set of CTC data from screening patients at an institution and geographic location different from those at which the CAD system was trained. CTC data were collected from the records of 104 patients undergoing screening for colorectal neoplasia. Most of the patients were at average risk, had CTC findings suggestive of polyps, and underwent colonoscopy. Patients underwent cathartic bowel preparation, were given an oral contrast agent, and underwent imaging in the prone and supine positions. The patients had 86 adenomas confirmed at same-day optical colonoscopy; 47 of these tumors were 10 mm in diameter or larger, and 39 measured 6-9 mm. The CTC data were analyzed with an existing CAD system for colonography that was trained with previously acquired data. In a previous non-polyp-enriched screening cohort, the standalone performance of the CAD system was 93.3% (28/30) sensitivity for adenomatous polyps 10 mm or larger, 51.1% (47/92) sensitivity for adenomas 6-9 mm, and a mean false-positive rate of 8.6 per patient. Sensitivity comparisons were made with findings in the previous study. The CAD system had per-polyp sensitivities of 91.5% (43/47; 95% CI, 78.7-97.2%; p = 1.0) for adenomas 10 mm or larger and 82.1% (32/39; 65.9-91.9%; p = 0.0009) for adenomas 6-9 mm. The per-patient sensitivities were 97.6% (40/41; 85.6-99.9%; p = 0.6) for patients with adenomas 10 mm or larger and 82.4% (28/34; 64.8-92.6%; p = 0.047) for patients with adenomas 6-9 mm. The mean and median false-positive rates were 9.6 +/- 9.6 and 7.0 per patient, respectively. Common reasons for CAD misses (false-negative findings) were the presence of adherent contrast medium, flat adenomas, and adenomas located on or adjacent to normal colonic folds. In a random sample, 72.5% (29/40) of false-positive findings were attributable to folds or residual feces. The CAD system evaluated has a high level of performance in the detection of adenomatous polyps with CTC data from a polyp-enriched cohort different from that used to train the system.

Diagnostic accuracy of MR colonography with fecal tagging

MR colonography (MRC) is a non-invasive method of examining the colon, but it is still only used in a few specialized centers on a daily basis. The purpose of this study was to evaluate the performance of MRC with improved fecal tagging vs. conventional colonoscopy (CC). Between March 2006 and February 2007, consecutive patients who received first-time referrals to CC were asked to participate in the study. Two days prior to MRC, a new contrast mixture (barium/ferumoxsil) was ingested together with four meals each day. Standard bowel cleansing was performed before CC. MRC was evaluated by two blinded observers. MRC results were compared with CC. A total of 56 patients were included. The per-polyp sensitivity was 85.7% for polyps 6-10 mm and 81.3% for polyps >10 mm. The per-patient sensitivity/specificity was 100%/80% for polyps >6 mm and 100%/91.4% for polyps >10 mm. MRC showed acceptable per-patient sensitivities, but the per-polyp sensitivities are still compromised by the fecal tagging. MRC may be implemented, but at the present time MRC with fecal tagging is not ready for widespread use, although it remains a very promising diagnostic tool.

Value of endorectal MRI and MRS in patients with elevated prostate-specific antigen levels and previous negative biopsies to localize peripheral zone tumours

To evaluate prospectively the role of endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) in detecting peripheral zone tumour in patients with total prostate-specific antigen (PSA) values>or=4 ng/ml and one or more negative transrectal ultrasound (TRUS) biopsy rounds. Fifty-four consecutive men (mean age 65.4+/-5.2 years, mean total PSA 10.8+/-7.5 ng/ml), underwent a combined MRI-MRS examination with endorectal coil. MRI included transverse, coronal, and sagittal T2-weighted and transverse T1-weighted fast spin-echo sequences. MRS data were acquired using a double spin-echo point resolved spectroscopy (PRESS) sequence. A 10-site scheme was adopted to evaluate the prostate peripheral zone. A peripheral prostatic site was classified as suspicious if low intensity signal was present on T2-weighted images and/or if the choline+creatine/citrate ratio was >0.86. Following MRI-MRS all patients were submitted to a standard 10-core biopsy scheme to which from one to three supplementary samples were added from suspicious MRI and/or MRS sites. In per-patient analysis findings were considered true-positive if biopsy positive patients were classified as suspicious, irrespectively of lesion site indication. Prostate cancer (PC) was detected in 17 of 54 patients (31.5%); median Gleason score was 6 (range 4-8). On a per-patient basis sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were respectively 100, 64.9, 56.7, 100, and 75.9% for MRI; 82.2, 70.3, 57.7, 92.9, and 75.9% for MRS; and 100, 51.4, 48.6, 100, and 66.7% for combined MRI-MRS. In all the 17 PC patients, combined MRI-MRS correctly indicated the sites harbouring cancer, whereas both MRI and MRS gave erroneous indications in two patients. The results of the present study show that MRI alone might be able to select negative patients in whom further biopsies are unnecessary. The combination of MRI and MRS might be able to drive biopsies in suspicious sites and increase the cancer detection rate. Further studies are required to confirm these data.

CT Colonography with Limited Bowel Preparation: Performance Characteristics in an Increased-Risk Population

To prospectively evaluate the sensitivity and specificity of computed tomographic (CT) colonography with limited bowel preparation for the depiction of colonic polyps, by using colonoscopy as the reference standard. Institutional review board approval and written informed consent were obtained. Patients at increased risk for colorectal cancer underwent CT colonography after fecal tagging, which consisted of 80 mL of barium sulfate and 180 mL of diatrizoate meglumine. Bisacodyl was added for stool softening. A radiologist and a research fellow evaluated all data independently by using a primary two-dimensional approach. Discrepant findings for lesions 6 mm or larger in diameter were solved with consensus. Segmental unblinding was performed. Per-patient sensitivity and specificity, per-polyp sensitivity, and number of false-positive findings were found (for lesions > or = 6 mm and > or = 10 mm in diameter). Per-patient sensitivities (blinded colonoscopy vs CT colonography) were tested for significance with McNemar statistics. Interobserver variability was analyzed per segment (prevalence-adjusted bias-adjusted kappa values [kappa(p)]). One hundred fourteen of 168 patients (105 men, 63 women; mean age, 56 years) had polyps, with 56 polyps 6 mm or larger and 17 polyps 10 mm or larger. Per-patient sensitivities were not significantly different for CT colonography (consensus reading) and colonoscopy (P > or = .070). Sensitivity of CT colonography for patients with lesions 6 mm or larger and 10 mm or larger was 76% and 82%, respectively, and specificity of CT colonography was 79% and 97%, respectively. Blinded colonoscopy depicted 91% (lesions > or = 6 mm) and 88% (lesions > or = 10 mm) of disease in patients. Per-polyp sensitivity for CT colonography was 70% (lesions > or = 6 mm) and 82% (lesions > or = 10 mm). Number of false-positive findings was 42 (lesions > or = 6 mm) and six (lesions > or = 10 mm). kappa(p) Was 0.88 (lesions > or = 6 mm) and 0.96 (lesions > or = 10 mm). CT colonography with limited bowel preparation has a sensitivity of 82% and specificity of 97% for patients with polyps 10 mm or larger.

Dual-source computed tomography coronary angiography: influence of obesity, calcium load, and heart rate on diagnostic accuracy

To prospectively investigate the diagnostic accuracy of dual-source computed tomography coronary angiography (CTCA) to diagnose coronary stenoses in relation to body mass index (BMI), Agatston score (AS), and heart rate (HR) as compared with catheter coronary angiography (CCA). Hundred and fifty consecutive patients (47 female, mean age 62.9 +/- 12.1 years) underwent dual-source CTCA without HR control. Patients were divided into subgroups depending on the median of their BMI (26.0 kg/m2), AS (194), and HR (66 b.p.m.). CCA was considered the standard of reference. Mean BMI was 26.5 +/- 4.2 kg/m2 (range 18.3-39.1 kg/m2), mean AS was 309 +/- 408 (range 0-4387), and HR was 68.5 +/- 12.6 b.p.m. (range 35-102 b.p.m.). Diagnostic image quality was found in 98.1% of all segments (2020/2059). Considering not-evaluative segments at CTCA as false-positive, overall per-patient sensitivity, specificity, positive, and negative predictive value were 96.6%, 86.8%, 82.6%, and 97.5%, respectively. High HR did not deteriorate diagnostic accuracy of CTCA. High BMI and AS were associated with a decrease in per-patient specificity to 84.1% and 77.8%, respectively, while sensitivity and negative predictive value remained high. Dual-source CTCA provides high diagnostic accuracy irrespective of the HR and serves as a modality to rule-out coronary artery stenoses even in patients with high BMI and AS.

Double-Contrast MRI for Accurate Staging of Hepatocellular Carcinoma in Patients with Cirrhosis

The aim of this study was to evaluate the accuracy of a double-contrast MRI protocol in staging of hepatocellular carcinoma (HCC) in patients with cirrhosis. This cross-sectional study was performed at a tertiary liver care center. Forty-eight patients with cirrhosis underwent double-contrast MRI for clinical care and liver transplantation. For each MRI examination, superparamagnetic iron oxide was infused, and 2D T2*-weighted spoiled gradient-recalled echo and T2-weighted echo-train spin-echo MR images were obtained for assessment of phagocytic function. Immediately afterward, a low-molecular-weight gadolinium compound was injected, and 3D T1-weighted spoiled gradient-recalled echo images were acquired dynamically for assessment of vascularity. Two blinded radiologists independently reviewed all MR images and assigned per-lesion and per-patient cancer confidence scores to determine the American Liver Tumor Study Group tumor stage. The imaging-based cancer scores and tumor stages were correlated with pathology reports. Performance parameters were computed for imaging-based measurements. Of the 48 study subjects, 25 had HCC (three, T1; 18, T2; one, T3; one, T4a; two, T4b). In total, there were 37 HCC nodules. The accuracy of MRI in prediction of pathologic tumor stage was 81-85% depending on the radiologist. Per-patient and per-lesion sensitivity in the diagnosis of HCC were 96% and 81% for one radiologist and 96% and 89% for the other. A double-contrast MRI protocol has high accuracy in staging of HCC in patients with cirrhosis.

Influence of Heart Rate on the Diagnostic Accuracy of Dual-Source Computed Tomography Coronary Angiography

We evaluated the influence of heart rate on image quality and diagnostic accuracy of dual-source computed tomography (DSCT) coronary angiography. Multidetector computed tomography (MDCT) coronary angiography has demonstrated an inverse relationship between heart rate and image quality. Dual-source CT provides a higher temporal resolution. One hundred patients were studied by DSCT (DEFINITION, Siemens Medical Solutions, Forchheim, Germany). A contrast-enhanced volume dataset was acquired (two tubes, 120 kV, 400 mAs/rot, collimation 64 x 0.6 mm). Datasets were evaluated concerning the presence of significant coronary stenoses and validated against invasive coronary angiography. In 44 patients with a heart rate > or =65 beats/min, 566 of 616 coronary segments were evaluable (92%), whereas in 56 patients with a heart rate <65 beats/min, 777 of 778 coronary segments were evaluable (100%, p < 0.001). On a per-patient basis, 93% of patients (> or =65 beats/min) and 100% of patients (<65 beats/min) were considered evaluable. By classifying unevaluable segments as positive for stenosis, per-patient sensitivity was 95% (19 of 20) for heart rates > or =65 beats/min and 100% (22 of 22) for heart rates <65 beats/min. Specificity was 87% (21 of 24) versus 76% (26 of 34), and overall diagnostic accuracy was 91% (40 of 44) versus 86% (48 of 56). None of these differences were statistically significant. Similarly, no difference in diagnostic accuracy was found in per-vessel and -segment analyses. In 100 patients studied without beta-blocker pre-medication, DSCT demonstrated slightly lower per-segment evaluability for high heart rates but no decrease in diagnostic accuracy for the detection of coronary artery stenoses.

Combining dual-source computed tomography coronary angiography and calcium scoring: added value for the assessment of coronary artery disease

Objective:To prospectively investigate the diagnostic accuracy of dual-source 64-slice computed tomography coronary angiography (CTCA), calcium scoring (CS) and both methods combined for assessing significant coronary artery stenoses relative to conventional...

Computer-Aided Detection (CAD) Using 360° Virtual Dissection: Can CAD in a First Reviewer Paradigm Be a Reliable Substitute for Primary 2D or 3D Search?

The purpose of this study was to evaluate the feasibility of a new computer-aided detection (CAD) software program as a first reviewer for detecting colorectal polyps when applied to 360 degrees virtual dissection image display. Forty-one consecutive patients who underwent imaging without oral contrast material for stool tagging from a teaching file database constituted the patient population for this feasibility study. Using CT colonography equipped with CAD software, reviewers evaluated each possible polyp detected by the software using virtual dissection images combined with axial and 3D endoluminal views and compared the results with optical colonoscopy, the reference standard. Two experienced radiologists blinded to the reference standard findings interpreted the CAD detections to be true or false. The false detections were reviewed and categorized. Sensitivities for polyps that were 6-9 mm were 78.3% (18/23) and 91.3% (21/23) for reviewers 1 and 2, respectively. For polyps > or = 1 cm, sensitivities were 94.9% (37/39) and 97.4% (38/39) for reviewers 1 and 2, respectively. Per-patient sensitivities for polyps > or = 6 and > or = 10 mm were 94.4% (34/36) and 95.1% (39/41) for reviewer 1 and 97.2% (35/36) and 97.6% (40/41) for reviewer 2, respectively. The average number of false detections per acquisition was 4.28. The average interpretation times were 4 minutes 26 seconds and 5 minutes 38 seconds for reviewers 1 and 2, respectively. Colorectal polyp detection using CT colonography equipped with CAD and virtual dissection as a first reviewer is feasible. Detection rates are similar to colonoscopy. Interobserver variability is low and interpretation times are short. False-positive detections per patient are few in number.

Two- versus Three-dimensional Colon Evaluation with Recently Developed Virtual Dissection Software for CT Colonography

This retrospective study was institutional review board approved; the requirement for informed patient consent was waived. The purpose of this study was to retrospectively compare a two-dimensional (2D) data interpretation technique with a three-dimensional (3D) colon dissection technique in terms of interpretation time and sensitivity for colonic polyp detection, with colonoscopy as the reference standard. Ninety-six patients (56 men, 40 women; mean age, 54.8 years) underwent colonoscopy and multidetector computed tomographic (CT) colonography on the same day. Two radiologists independently analyzed the data on a per-polyp and per-patient basis. The sensitivity of both approaches was compared by using the McNemar test. The time required to interpret CT colonographic data with each technique was also assessed. Compared with the conventional 2D colonic polyp detection method, primary 3D interpretation with use of virtual dissection software for CT colonography revealed comparable per-polyp (77% and 69% for two readers) and per-patient (77% and 73% for two readers) sensitivities and comparable per-patient specificity (99% and 89% for two readers) for the detection of polyps 6 mm in diameter or larger and involved a shorter interpretation time.

CT Colonography: False-Negative Interpretations

To retrospectively evaluate if false-negative interpretations at computed tomographic (CT) colonography are due to observer error. This study was HIPAA compliant and had institutional review board approval, with waiver of informed consent. An initial unblinded review of CT colonographic image data was used to generate reconciliation reports for all false-negative polyp candidates 6.0 mm or larger. These findings were then verified by two experienced readers. After reports from the original study and reconciliation reports were reviewed, errors were classified as observer (measurement or perceptual) errors, technical errors (eg, those caused by insufficient distention, fluid), or not reconcilable. Per-polyp and per-patient sensitivity values were calculated for adenomas 6.0 mm or larger in the original data set and again by assuming elimination of technical and observer errors. Of the original data set of 228 available polyps, 147 were adenomas; for this subgroup, the per-patient sensitivity was 70% and 68% at 10.0- and 6.0-mm thresholds, respectively. When all histologic types were considered, 114 polyps were false-negative findings. Of these, 53% (60 of 114) were attributed to observer-related errors, and 26% were attributed to errors classified as technical. After detailed retrospective reconciliation of individual polyps (so as to exclude any potentially correctable observer error), the per-polyp sensitivity of CT colonography for adenomas 10.0 mm or larger increased to 93%, and the per-patient sensitivity increased to 91%. When observer and technical errors were accounted for, eight (5.4%) of 147 adenomas 6.0 mm or larger could not be detected. If all technical errors and observer errors were scored as true-positive findings, the sensitivity for adenomas 6.0 mm or larger would have been 95% on both a per-polyp and a per-patient basis. The major contributor to error at CT colonography was observer perceptual error, while observer measurement error played a smaller role.

Are dysplasia and colorectal cancer endoscopically visible in patients with ulcerative colitis?

Dysplasia and colorectal cancer (CRC) in ulcerative colitis (UC) develop via pathways distinct from sporadic CRC and may occur in flat mucosa indistinct from surrounding tissue. Surveillance guidelines, therefore, have emphasized the ;roach of periodic endoscopic examinations and systematic random biopsies of involved mucosa. Given the imperfect nature of this random approach, recent work has focused on improved surveillance techniques and suggests that neoplasia is endoscopically visible in many patients. To assess the endoscopic visibility of dysplasia and CRC in UC. This was a retrospective review that used the University of Chicago Inflammatory Bowel Disease Registry and the clinical administrative database. All cases of dysplasia or CRC in UC between November 1994 and October 2004 were identified. The approach to surveillance in these patients included both random biopsies at approximately 10-cm intervals throughout the involved colon and directed biopsies of polypoid lesions, masses, strictures, or irregular mucosa distinct from surrounding inflamed tissue. Findings on endoscopy were compared with pathologic findings from biopsy or surgical specimens. Visible dysplasia was defined as a lesion reported by the endoscopist that led to directed biopsy and that was confirmed by pathology. Invisible dysplasia was defined as dysplasia diagnosed on pathology but not described on endoscopy. Per-lesion and per-patient sensitivities were determined. Tertiary referral center. Database of patients with inflammatory bowel disease seen at the University of Chicago. Endoscopically visible neoplasia. In this database, there were 1339 surveillance examinations in 622 patients with UC. Forty-six patients were found to have dysplasia or CRC at a median age of 48 years and with median duration of disease of 20 years. Of these patients, 77% had pancolitis, 21% had left-sided colitis, and 2% had proctitis. These patients had 128 surveillance examinations (median 3 per patient; range, 1-9 per patient), and, in 51 examinations, 75 separate dysplastic or cancerous lesions were identified (mean, 1.6 lesions per patient; standard deviation, 1.3). Thirty-eight of 65 dysplastic lesions (58.5%) and 8 of 10 cancers (80.0%) were visible to the endoscopist as 23 polyps and masses, 1 stricture, and 22 irregular mucosa. The per-patient sensitivities for dysplasia and for cancer were 71.8% and 100%, respectively. The overall per-lesion and per-patient sensitivities were 61.3% and 76.1%, respectively. Retrospective review of clinical databases and medical records. Dysplasia and cancer in UC are endoscopically visible in most patients and may be reliably identified during scheduled examinations. Future surveillance guidelines should incorporate this information.

Detection of Bladder Tumors with Dynamic Contrast-Enhanced MDCT

In a small pilot study, we assessed whether early-phase dynamic contrast-enhanced MDCT can be used to detect bladder tumors and whether thin reconstruction improves the detection rate. Thirty-six patients (30 with 59 cystoscopy-proven bladder cancers and six with normal bladders) underwent dynamic contrast-enhanced MDCT of the pelvis and abdomen. Images were obtained from the symphysis pubis to the diaphragm 70 seconds after injection of 100 mL of contrast medium. McNemar test was used to compare sensitivity per patient, segment, and tumor and specificity per patient and segment for each of three reconstruction methods: 5-mm sections with no overlap (i.e., 5-mm axial images), 2.5-mm sections with 1.25-mm overlap (i.e., thin-section axial images), and 2.5-mm sections with 1.25-mm overlap and multiplanar reformation (MPR) (i.e., thin-section axial images with MPR). MDCT with a combination of thin, overlapped sections and MPR depicted all but one of 47 bladder tumors larger than 5 mm but only five of 12 tumors 5 mm or smaller. There were no false-positive findings. Per-tumor sensitivity was significantly better with thin-section images with MPR (90%) and thin-section images alone (86%) than with 5-mm axial images (80%) (p < 0.05). Per-segment sensitivity was significantly better with thin-section images with MPR (95%) and thin-section axial images alone (87%) than with 5-mm axial images (79%) (p < 0.05). Per-patient sensitivity and per-patient and per-segment specificity did not differ with the three methods. Dynamic contrast-enhanced MDCT of the pelvis shows promise for the detection of bladder tumors. Use of thin-section images with MPR and thin-section axial images alone had a significantly better rate of detection of bladder tumors than use of 5-mm axial images.