Multiphase CT enterography evaluation of small-bowel vascular lesions.

OBJECTIVE: By use of multiphase CT enterography (CTE), small-bowel vascular lesions associated with gastrointestinal bleeding can be classified into three categories--angioectasias, arterial lesions, and venous abnormalities--on the basis of common morphology and enhancement patterns. This article will review the unique patterns of enhancement and lesion morphology seen on multiphase CTE and how those findings enable detection and characterization of specific lesions in many cases. CONCLUSION: Because of the high prevalence in nonbleeding patients and frequent multiplicity of angioectasias, determining the clinical benefit from their detection by multiphase CTE and endoscopy is problematic. Although arterial lesions are less commonly encountered clinically, their detection is critically important because of a high risk of life-threatening bleeding. Along with wireless capsule endoscopy and balloon-assisted endoscopy, multiphase CTE is a useful tool for the evaluation of patients with obscure gastrointestinal bleeding due to small-bowel vascular lesions.

Individualization of abdominopelvic CT protocols with lower tube voltage to reduce i.v. contrast dose or radiation dose.

OBJECTIVE: The purpose of this study was to validate an individualized approach to contrast-enhanced body CT using size-specific tube potential selection to reduce either i.v. contrast or radiation dose while maintaining diagnostic image quality. MATERIALS AND METHODS: With a validated noise insertion method and retrospective image quality assessment (scale 1-5, ≥ 3 acceptable), the lowest acceptable iodine contrast-to-noise ratio (CNR) was determined for 25 body CT examinations. Age-appropriate CT protocols with size-specific tube potential selection were then developed to accomplish two goals: i.v. contrast dose reduction for patients 50 years old and older and radiation dose reduction for patients younger than 50 years. After implementation, subjective and objective image quality metrics were retrospectively compared between the individualized scans and previous fixed-tube-potential scans. RESULTS: Diagnostically acceptable iodine CNR was achieved with use of up to 40% dose reduction from the baseline protocol. At this dose level, results of logistic regression analysis predicted 94% probability of acceptable image quality. With the individualized protocols that targeted this iodine CNR, 84 patients 50 years old and older had a mean i.v. contrast dose reduction of 26% (100.9 ± 20.7 mL vs 136.2 ± 24.9 mL; p < 0.001) with unchanged image quality scores (4.6 ± 0.5 vs 4.6 ± 0.4; p = 0.160). Thirty patients younger than 50 years had a mean radiation dose reduction of 41% (mean volume CT dose index, 11.6 ± 5.3 mGy vs 19.7 ± 7.8 mGy; p < 0.001) with acceptable but slightly reduced mean image quality scores (4.1 ± 0.4 vs 4.7 ± 0.4; p < 0.001). CONCLUSION: With the use of age-appropriate scan protocols and size-specific selection of tube potential, acceptable image quality can be maintained while i.v. contrast dose or radiation dose is substantially lowered.

Pilot study of detection, radiologist confidence and image quality with sinogram-affirmed iterative reconstruction at half-routine dose level.

OBJECTIVE: The objective of this study was to determine the effect of Sinogram-Affirmed Iterative Reconstruction (SAFIRE) on radiological detection, diagnostic confidence, and image quality at half-dose, contrast-enhanced abdominopelvic computed tomography. METHODS: Forty dual-source examinations were reconstructed using routine-dose with filtered back projection, half-dose filtered back projection, and half-dose SAFIRE. Three radiologists detected lesions in abdominopelvic organs, reporting findings of potential medical significance, diagnostic confidence, and image quality. RESULTS: There was greater than 78% concordance between full- and half-dose images ± SAFIRE, and no difference in the detection of lesions within organs between half-dose images ± SAFIRE (P = 0.22 - 1.0). Detection of potentially important findings varied by reader, but not between dose/reconstruction methods. Diagnostic confidence varied widely (P < 0.001 to P > 0.91). Sinogram-Affirmed Iterative Reconstruction significantly improved image quality in the pelvis (P ≤ 0.04). CONCLUSIONS: Half-dose images ± SAFIRE had organ-specific detections similar to routine-dose images. Sinogram-Affirmed Iterative Reconstruction improved image quality in the pelvis, but diagnostic confidence and image quality scores in the abdomen depended on the reader.

New concepts in intestinal imaging for inflammatory bowel diseases.

In the last decade, multiple imaging technologies have been developed that improve visualization of the mucosal, mural, and perienteric inflammation associated with inflammatory bowel diseases. Whereas these technologies have traditionally been used to detect and stage suspected enteric inflammation, we review new, emerging roles in detecting clinically occult inflammation (in asymptomatic patients) and inflammatory complications, predicting response prior to therapy, assessing response after therapy, and enteric healing. We compare the relative performance of these technologies in detecting inflammation, focusing on their advantages and disadvantages and how they might complement each other. We also discuss their potential benefits for patients and clinical trials, reviewing technologic developments and areas of research that could provide important insights into the pathophysiology of inflammatory bowel diseases-related enteric inflammation.

Noise reduction to decrease radiation dose and improve conspicuity of hepatic lesions at contrast-enhanced 80-kV hepatic CT using projection space denoising.

OBJECTIVE: The purpose of this study was to investigate the combined potential of 80-kV CT and noise reduction using a projection space denoising algorithm to reduce radiation dose reduction or to improve the image quality of hepatic CT. MATERIALS AND METHODS: Twenty patients with 56 liver lesions underwent dual-energy (80 and 140 kV) contrast-enhanced hepatic CT. Low-dose 80-kV-only images (comprising 26-54% of the total radiation dose), low-dose 80-kV projection space denoising images (routine and sharper reconstruction kernel), and full-dose mixed-kilovoltage with projection space denoising images were evaluated by three radiologists for lesion conspicuity, image noise, and sharpness. Lesions were compared with full-dose images using 5-point scales (0 = no change, +2 = markedly better, and -2 = markedly worse). Quantitative conspicuity in the form of lesion-to-liver contrast-to-noise ratio (CNR), image noise, and image sharpness were measured. RESULTS: For all readers, the mean conspicuity rating of low-dose 80-kV projection space denoising images was better than that for full-dose images (mean conspicuity, 0.36-0.57; p < 0.001), with only 1.2% of lesions less conspicuous on 80-kV projection space denoising images. Eighty-kilovolt projection space denoising images reconstructed with a sharper kernel were subjectively similar to full-dose mixed-kilovoltage images comparing image noise (-0.054 to 0.018; p < 0.001 to p = 0.058) and sharpness (-0.64 to -0.09; p < 0.001 to p = 0.057). For 80-kV projection space denoising images with a sharper kernel, lesion-to-liver CNR was slightly higher than that for full-dose mixed-kilovoltage images (p < 0.001), whereas image sharpness and noise were unchanged (p = 0.74 and p = 0.02). CONCLUSION: Eighty-kilovolt imaging with noise reduction can simultaneously increase lesion conspicuity and facilitate radiation dose reduction and image quality improvement at contrast-enhanced hepatic CT.

Toward biphasic computed tomography (CT) enteric contrast: material classification of luminal bismuth and mural iodine in a small-bowel phantom using dual-energy CT.

OBJECTIVE: To develop dual-energy computed tomography methods for identification of hyperenhancing, hypoenhancing, and nonenhancing small-bowel pathologies. METHODS: Small-bowel phantoms simulating varying patient sizes and polyp types (hyperenhancing, hypoenhancing, and nonenhancing) contained bismuth suspension in the lumen. Dual-energy CT was performed at 80/140 kV and 100/140 kV. Computed tomographic number ratios (CT numbers at low/high kilovoltage) were calculated. Two radiologists evaluated polyp detection and conspicuity using bismuth-only, iodine-only, iodine-overlay, and mixed-kilovoltage displays. RESULTS: Computed tomographic ratios for bismuth and iodine did not overlap. For hyperenhancing and nonenhancing polyps at 80/140 kV, iodine-overlay display yielded higher detection rate (96%, 94%) and conspicuity score (3.5, 3.1) than mixed-kilovoltage images (88%, 68%; 1.5, 2.7). Mixed-kV images performed slightly better for hypoenhancing polyps (92%, 3.4 vs. <80%, <2.9). Similar results were observed at 100/140kV. CONCLUSIONS: Dual-energy CT and a bismuth-containing enteric contrast permitted simultaneous identification of hyperenhancing, hypoenhancing, and nonenhancing polyps over a range of patient sizes.

Computed tomography enterography detects intestinal wall changes and effects of treatment in patients with Crohn's disease.

BACKGROUND & AIMS: The use of computed tomography enterography (CTE) in patients with Crohn's disease has increased. However, there is little data available on how radiologic parameters of active disease change during treatment with infliximab and whether these changes correspond to symptoms, serum biomarkers, or endoscopic appearance. METHODS: We performed a retrospective study of patients with Crohn's disease who had undergone serial CTE imaging while receiving infliximab. Lesions were defined as improved if their enhancement or length decreased without worsening of other parameters. Patients were grouped as responders (all lesions improved), partial responders (some lesions improved), and nonresponders (worsening or no changes in all lesions). Of the 63 patients identified (47% female), the median age was 37.7 years, the median disease duration was 7.6 years, and the median time between initial and first follow-up CTE was 356 days (interquartile range, 215-630). RESULTS: Of 105 lesions, 52 (49.5%) improved, 11 (10.5%) remained unchanged, and 42 (40.0%) worsened. Per patient, 28 (44.4%) were responders, 12 (19.0%) were partial responders, and 23 (36.5%) were nonresponders. The radiologic response had poor-to-fair agreement with symptoms, endoscopic appearance, and levels of C-reactive protein at time of second CTE (κ = 0.26, 0.07, and 0.30 respectively). CONCLUSIONS: Radiologic improvement was observed in 63.4% of patients with Crohn's disease who received infliximab therapy, despite a study design that was likely biased toward nonresponders. Radiologic response was not in good agreement with clinical symptoms, serum biomarkers, or endoscopic appearance; CTE might be used as a complementary approach to identify mural healing or inflammation not detected by other methods.

Prospective blinded comparison of wireless capsule endoscopy and multiphase CT enterography in obscure gastrointestinal bleeding.

PURPOSE: To compare the performance of multiphase computed tomographic (CT) enterography with that of capsule endoscopy in a group of patients with obscure gastrointestinal bleeding (OGIB). MATERIALS AND METHODS: This prospective HIPAA-compliant study was approved by the institutional review board and the institutional conflict of interest committee. All patients provided written informed consent. Two radiologists, blinded to clinical data and results of capsule endoscopy, interpreted images from CT enterography independently, with discordant interpretations resolved by consensus. Results were compared with those from a reference standard (surgery or endoscopy) and clinical follow-up. Sensitivity and 95% confidence intervals were calculated for each modality. RESULTS: Fifty-eight adult patients, referred for the evaluation of OGIB (occult, 25 patients [43%]; overt, 33 patients [57%]), underwent both tests. A small bowel bleeding source was identified in 16 of the 58 patients (28%). The sensitivity of CT enterography was significantly greater than that of capsule endoscopy (88% [14 of 16 patients] vs 38% [six of 16 patients], respectively; P = .008), largely because it depicted more small bowel masses (100% [nine of nine patients] vs 33% [three of nine patients], respectively; P = .03). No additional small bowel tumors were discovered during the follow-up period (range, 5.6-45.9 months; mean, 16.6 months). CONCLUSION: In this referral population, the sensitivity of CT enterography for detecting small bowel bleeding sources and small bowel masses was significantly greater than that of capsule endoscopy. On the basis of these findings, the addition of multiphase CT enterography to the routine diagnostic work-up of patients with OGIB should be considered, particularly in patients with negative findings at capsule endoscopy.

CT-enterography may identify small bowel tumors not detected by capsule endoscopy: eight years experience at Mayo Clinic Rochester.

BACKGROUND: Capsule endoscopy (CE) is widely accepted as the preferred diagnostic test in the evaluation of small bowel diseases. However, small bowel tumors (SBT) are sometimes missed by CE. Preliminary studies suggest that CT-enterography (CTE) may play a role in detecting SBT. AIMS: The purpose of this study was to compare the performance of CE and CTE in detecting SBT METHODS: This was a single center, retrospective study. Patients treated at the Mayo Clinic Rochester between January 2000 and December 2008 with a discharge diagnosis of SBT and negative initial esophagogastroduodenoscopy (EGD) and colonoscopy were identified through a search of the electronic medical records. Among 103 identified patients, 41 had undergone CE, CTE or both, and comprised our study group. The exact binomial sensitivity of CE and CTE in detecting SBT was calculated. Demographic characteristics, clinical presentation, results of diagnostic tests, and tumor characteristics were recorded for each patient. RESULTS: CTE and CE detected 38/41 (sensitivity 92.7%; 95% CI 80.1-98.5) and 8/27 (sensitivity 29.6%; 95% CI 13.8-50.2) of the SBT identified at Mayo Clinic Rochester, respectively. Seventeen patients had both CTE and CE. In this subgroup of patients, CTE detected SBT in 16/17 (sensitivity 94.1; 95% CI 72.7-99.9) and CE in 6/17 (sensitivity 35.3%; 95% CI 13.3-59). The matched paired difference in the sensitivity of two techniques in detecting SBT was statistically significant (P = 0.004). CONCLUSION: CTE may identify SBT not diagnosed by CE.

Appropriate patient selection at abdominal dual-energy CT using 80 kV: relationship between patient size, image noise, and image quality.

PURPOSE: To determine the computed tomographic (CT) detector configuration, patient size, and image noise limitations that will result in acceptable image quality of 80-kV images obtained at abdominal dual-energy CT. MATERIALS AND METHODS: The Institutional Review Board approved this HIPAA-compliant retrospective study from archival material from patients consenting to the use of medical records for research purposes. A retrospective review of contrast material-enhanced abdominal dual-energy CT scans in 116 consecutive patients was performed. Three gastrointestinal radiologists noted detector configuration and graded image quality and artifacts at specified levels-midliver, midpancreas, midkidneys, and terminal ileum-by using two five-point scales. In addition, an organ-specific enhancement-to-noise ratio and background noise were measured in each patient. Patient size was measured by using the longest linear dimension at the level of interest, weight, lean body weight, body mass index, and body surface area. Detector configuration, patient sizes, and image noise levels that resulted in unacceptable image quality and artifact rankings (score of 4 or higher) were determined by using multivariate logistic regression. RESULTS: A 14 × 1.2-mm detector configuration resulted in fewer images with unacceptable quality than did the 64 × 0.6-mm configuration at all anatomic levels (P = .004, .01, and .02 for liver, pancreas, and kidneys, respectively). Image acceptability for the kidneys and ileum was significantly greater than that for the liver for all readers and detector configurations (P < .001). For the 14 × 1.2-mm detector configuration, patient longest linear dimensions yielding acceptable image quality across readers ranged from 34.9 to 35.8 cm at the four anatomic levels. CONCLUSION: An 80-kV abdominal CT can be performed with appropriate diagnostic quality in a substantial percentage of the population, but it is not recommended beyond the described patient size for each anatomic level. The 14 × 1.2-mm detector configuration should be preferred.

Dual-energy and dual-source CT: is there a role in the abdomen and pelvis?

Dual-energy CT refers to the use of CT data representing two different energy spectra and allows for the possibility of differentiating and classifying tissue to obtain material-specific images. Dual-energy CT data can be acquired using various CT hardware platforms, with numerous approaches also existing for display of anatomic and material-specific dual-energy information. Dual-source CT refers to the use of two x-ray sources and two x-ray detectors mounted on a single CT gantry and can be used in either a dual-energy or single-energy mode. This article summarizes and reviews current and potential applications for dual-energy and dual-source CT in the abdomen and pelvis.

Prospective comparison of state-of-the-art MR enterography and CT enterography in small-bowel Crohn's disease.

OBJECTIVE: The objective of our study was to prospectively obtain pilot data on the accuracy of MR enterography for detecting small-bowel Crohn's disease compared with CT enterography and with a clinical reference standard based on imaging, clinical information, and ileocolonoscopy. SUBJECTS AND METHODS: The study group for this blinded prospective study was composed of 33 patients with suspected active Crohn's ileal inflammation who were scheduled for clinical CT enterography and ileocolonoscopy and had consented to also undergo MR enterography. The MR enterography and CT enterography examinations were each interpreted by two radiologists with disagreements resolved by consensus. The reports from ileocolonoscopy with or without mucosal biopsy were interpreted by a gastroenterologist. The reference standard for the presence of small-bowel Crohn's disease was based on the final clinical diagnosis by the referring gastroenterologist after reviewing all of the available information. RESULTS: All 33 patients underwent CT enterography and ileocolonoscopy, 30 of whom also underwent MR enterography. The sensitivities of MR enterography and CT enterography for detecting active small-bowel Crohn's disease were similar (90.5% vs 95.2%, respectively; p = 0.32). The image quality scores for MR enterography examinations were significantly lower than those for CT enterography (p = 0.005). MR enterography and CT enterography identified eight cases (24%) with a final diagnosis of active small-bowel inflammation in which the ileal mucosa appeared normal at ileocolonoscopy. Furthermore, enterography provided the only available imaging in three additional patients who did not have ileal intubation. CONCLUSION: MR enterography and CT enterography have similar sensitivities for detecting active small-bowel inflammation, but image quality across the study cohort was better with CT. Cross-sectional enterography provides complementary information to ileocolonoscopy.

Multi-phase CT enterography in obscure GI bleeding.

Multiphase CT enterography is a modification of conventional abdominal CT designed to optimize detection of abnormalities responsible for obscure GI bleeding. This imaging test appears to be complimentary to wireless capsule endoscopy in the evaluation of this difficult group of patients. A description of exam technique, findings, and discussion of results will be presented in this article.

Obscure gastrointestinal bleeding: evaluation with 64-section multiphase CT enterography--initial experience.

This retrospective HIPAA-compliant study was approved by the institutional review board and institutional conflict of interest committee. Patients gave informed consent for use of medical records. The purpose of the study was to retrospectively evaluate the findings depicted at computed tomographic (CT) enterography performed with a 64-section CT system and by using neutral enteric contrast material and a three-phase acquisition in patients with obscure gastrointestinal bleeding (OGIB). Twenty-two outpatients (11 men, 11 women; age range, 37-83 years) with OGIB underwent CT enterography. Findings were compared with capsule and traditional endoscopic, surgical, and angiographic findings. CT enterographic findings were positive for a bleeding source in 10 (45%) of 22 patients. Eight of 10 positive findings at CT enterography were also positive at capsule endoscopy or subsequent clinical diagnosis. CT enterography helped correctly identify three lesions undetected at capsule endoscopy. Study results suggest that multiphase, multiplanar CT enterography may have a role in the evaluation of OGIB.

Small-bowel imaging in Crohn's disease: a prospective, blinded, 4-way comparison trial.

BACKGROUND: With the introduction of new techniques to image the small bowel, there remains uncertainty about their role for diagnosing Crohn's disease. OBJECTIVE: To assess the sensitivity and specificity of capsule endoscopy (CE), CT enterography (CTE), ileocolonoscopy, and small-bowel follow-through (SBFT) in the diagnosis of small bowel Crohn's disease. METHODS: Prospective, blinded trial. SETTING: Inflammatory bowel disease clinic at an academic medical center. PATIENTS: Known or suspected Crohn's disease. Exclusion criteria included known abdominal abscess and non-steroidal anti-inflammatory drug (NSAID) use. Partial small-bowel obstruction (PSBO) at CTE excluded patients from subsequent CE. INTERVENTIONS: Patients underwent all 4 tests over a 4-day period. MAIN OUTCOME MEASUREMENTS: Sensitivity, specificity, and accuracy of each test to detect active small-bowel Crohn's disease. The criterion standard was a consensus diagnosis based upon clinical presentation and all 4 studies. RESULTS: Forty-one CTE examinations were performed. Seven patients (17%) had an asymptomatic PSBO. Forty patients underwent colonoscopy, 38 had SBFT studies, and 28 had CE examinations. Small-bowel Crohn's disease was active in 51%, absent in 42%, inactive in 5%, and suspicious in 2% of patients. The sensitivity of CE for detecting active small-bowel Crohn's disease was 83%, not significantly higher than CTE (83%), ileocolonoscopy (74%), or SBFT (65%). However, the specificity of CE (53%) was significantly lower than the other tests (P < .05). One patient developed a transient PSBO due to CE, but no patients had retained capsules. LIMITATION: Use of a consensus clinical diagnosis as the criterion standard-but this is how Crohn's disease is diagnosed in practice. CONCLUSIONS: The sensitivity of CE for active small-bowel Crohn's disease was not significantly different from CTE, ileocolonoscopy, or SBFT. However, lower specificity and the need for preceding small-bowel radiography (due to the high frequency of asymptomatic PSBO) may limit the utility of CE as a first-line test for Crohn's disease.

CT enterography: noninvasive evaluation of Crohn's disease and obscure gastrointestinal bleed.

CT enterography (CTE) is a noninvasive imaging test using neutral intraluminal contrast and intravenous contrast to evaluate the small bowel. Multiphasic imaging is used in evaluating obscure gastrointestinal bleeding (OGIB), and single-phase enteric imaging is used for all other indications, including Crohn's disease (CD). CTE findings of CD include bowel wall thickening, mucosal hyperenhancement, and mural stratification. CTE findings of angiodyplasias include a vascular tuft visible during arterial phase and an early draining mesenteric vein. Early studies indicate that CTE is superior to barium examination in the evaluation of CD and is complementary to capsule endoscopy in the evaluation of OGIB.

CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases.

Computed tomographic (CT) enterography combines the improved spatial and temporal resolution of multi-detector row CT with large volumes of ingested neutral enteric contrast material to permit visualization of the small bowel wall and lumen. Adequate luminal distention can usually be achieved with oral hyperhydration, thereby obviating nasoenteric intubation and making CT enterography a useful, well-tolerated study for the evaluation of diseases affecting the mucosa and bowel wall. Unlike routine CT, which has been used to detect the extraenteric complications of Crohn disease such as fistula and abscess, CT enterography clearly depicts the small bowel inflammation associated with Crohn disease by displaying mural hyperenhancement, stratification, and thickening; engorged vasa recta; and perienteric inflammatory changes. As a result, CT enterography is becoming the first-line modality for the evaluation of suspected inflammatory bowel disease. CT enterography has also become an important alternative to traditional fluoroscopy in the assessment of other small bowel disorders such as celiac sprue and small bowel neoplasms.

Retained Capsule Endoscopy in a Large Tertiary Care Academic Practice and Radiologic Predictors of Retention.

BACKGROUND: Capsule retention reported rates range between 1% and 13%. This study aims to determine the incidence of, risk factors for, and clinical outcomes of capsule retention in a large heterogenous cohort of patients and define cross-sectional imaging findings predictive of capsule retention. METHODS: A retrospective review of all capsule endoscopy (CE) examinations performed at our center from January 2002 to January 2013 was undertaken. Data on patient demographics, CE indication, findings, and details of management were analyzed. Radiologic images of patients with computed tomography scan performed 6 months before CE for patients with CE retention and for controls without CE retention but at high risk based on clinical computed tomography reports were examined by a gastrointestinal radiologist, blinded to history, and classified as worrisome based on the presence of stricture, partial obstruction, or small bowel (SB) anastomosis. RESULTS: Seventeen CE retentions (0.3%) occurred in 15 patients. Obscure gastrointestinal bleeding (47%) was the most common indication. Outcomes included surgical intervention (n = 10), endoscopic retrieval (n = 2), passing of capsule after treatment of inflammation (n = 3), passage after conservative measures for SB obstruction (n = 1), and loss to follow-up (n = 1). Patients with CE retention were more likely to have SB anastomoses (88% versus 23%) and partial obstruction (63% versus 38%) than patients with high-risk features for capsule retention who passed the capsule. CONCLUSIONS: In a tertiary care population without obstructive symptoms, capsule retention occurred in only 0.3% of cases. Review of surgical history and prior imaging for obstruction or SB anastomoses may help to reduce retention.

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.

A prospective randomized controlled study of erythromycin on gastric and small intestinal distention: implications for MR enterography.

OBJECTIVES: To assess if erythromycin increases gastric emptying and hence improves small intestinal distention during MR enterography. METHODS: Gastric, small intestinal, and large intestinal volumes were assessed with MR after neutral oral contrast (1350ml in 45min) and balanced randomization to erythromycin (200mg i.v., age 31±3y, 13 females), or placebo (37±3y, 13 females) in 40 healthy asymptomatic volunteers. Fat-suppressed T2-weighted MR images of the abdomen were acquired on a 1.5T magnet at standard delay times for enterography. Gastric, small, and large intestinal volumes were measured by specialized software. In addition, two radiologists manually measured diameters and percentage distention of jejunal and ileal loops. Treatment effects were evaluated by an ITT analysis based on ANCOVA models. RESULTS: All subjects tolerated erythromycin. MRI scans of the stomach and intestine were obtained at 62±2 (mean±SEM) and 74±2min respectively after starting oral contrast. Gastric volumes were lower (P<0.0001) after erythromycin (260±49ml) than placebo (688±63ml) but jejunal, ileal, and colonic volumes were not significantly different. However, maximum (76-100%) jejunal distention was more frequently observed (P=0.03) after erythromycin (8/20 subjects [40%]) than placebo (2/20 subjects [10%]). The diameter of a representative ileal loop was greater (P=0.001) after erythromycin (18.8±4.3mm) than placebo (17.3±2.8mm) infusion. CONCLUSIONS: After ingestion of oral contrast, erythromycin accelerated gastric emptying but effects on small intestinal dimensions were variable. In balance, erythromycin did not substantially enhance small intestinal distention during enterography using current standard delay times.