Multidetector CT enteroclysis: comparison of the reading performance for axial and coronal views

Visual search in abdominopelvic CT interpretation: accuracy and time efficiency between coronal MPR and axial images

RATIONALE AND OBJECTIVES

The objective of this study was to compare reader accuracy and time efficiency between coronal reformats of abdominopelvic computed tomography (CT) and axial images, by means of a visual search task.

MATERIALS AND METHODS

In this experimental crossover study, a novel visual search task, containing targets placed on actual CT images, was constructed to assess reader performance on both planes. Six trials were shown to participants in each plane, at a fixed time of 0.5 seconds per slice. The task was presented to 43 junior doctors. On each trial, participants were assessed for accuracy and confidence in finding the target on a five-point scale. Statistical analysis was performed using the Wilcoxon signed rank test, and Fleiss kappa.

RESULTS

Coronal images took 40% less time to view overall. No significant difference was found in reader accuracy or reader confidence between the two planes. Interrater agreement was observed as fair, across a very large number of raters (43).

CONCLUSIONS

Target identification in the coronal plane is extremely similar to the axial plane on abdominopelvic CT in this study and offers a substantial time benefit. A perceptual limit to visual processing of CT images may contribute to this similarity. Greater use of coronal reformats in day-to-day practice could substantially improve radiologist workflow.

Virtual enteroscopy using air as the contrast material: a preliminary feasibility study

BACKGROUND

There are no studies to date using air as an enteral contrast medium for small bowel expansion in virtual enteroscopy. We examine the feasibility of air as an enteral contrast medium for virtual enteroscopy to achieve small bowel expansion.

PATIENTS AND METHODS

Two volunteers and six patients were examined. The six patients included three with small bowel tumors, one with small bowel hemorrhage and two with suspected cases of post-operative small bowel stenosis. A duodenal tube was inserted under fluoroscopy and approximately 2000 ml air was administered prior to scanning. A 16-detector row computed tomography apparatus was used with 2-mm thick slices. Intravenous contrast material was administered to the patients, but not to the volunteers. Computed tomography scanning was performed two to three times until the air reached the colon. Two examiners reconstructed multi-planar reformation, volume rendering and virtual endoscopy. These images were compared with double balloon enteroscopic findings and/or resected specimens.

RESULTS

There were no complications associated with this examination. In the volunteers the difference between the circular folds of the jejunum and those of the ileum was clearly visualized on virtual endoscopy. Angiodysplasia (9 mm), gastrointestinal stromal tumor (15 mm) and arteriovenous malformation were clearly detected by virtual endoscopy. In contrast, one tumor could not be detected because of inadequate intestinal distension. In the two suspected cases of the stenosis, the lesion was not identified because stenotic lesions were not differentiated from normal peristalsis of the small bowel.

CONCLUSIONS

Air is a feasible enteral contrast material for virtual enteroscopy.

MRI scoring system including dynamic motility evaluation in assessing the activity of Crohn's disease of the terminal ileum

RATIONALE AND OBJECTIVES

We sought to investigate the value of a MRI scoring system including dynamic motility evaluation in the assessment of small bowel Crohn's disease activity.

MATERIALS AND METHODS

From March 2005 to December 2006, 52 patients with suspected Crohn's disease onset or relapse underwent MRI on a 1.5-T magnet. Bowel distention was achieved orally assuming a mean of 1.6 L of a polyethyleneglycol (PEG) preparation. Per-patient assessment of disease activity was based on a scoring system including evaluation of morphology and motility of the small bowel and perivisceral structures (true-FISP, cine-true-FISP, and HASTE T2W sequences) and dynamic assessment of parietal contrast enhancement (FLASH T1W sequence). Patients were included in three categories, using endoscopic biopsy as the standard reference: no activity/quiescent disease, mild activity, or moderate-to-severe activity. Patients without terminal ileum involvement were excluded from data analysis.

RESULTS

MRI allowed a detailed and panoramic evaluation of the small bowel in all subjects examined. MRI properly assessed 14 of 16 (87.5%) cases of no activity/quiescent disease, 12 of 14 (85.7%) cases of mild activity, and 15 of 15 (100%) cases of severe activity. Overall, activity score led to a per-patient misdiagnosis of disease activity in a nonsignificant proportion of subjects (4 of 45; 8.8%) (P > .05), determining two false-positive and two false-negative results of mild disease activity. Sensitivity, specificity, PPV, NPV, and overall accuracy in assessing disease activity were 93.1%, 87.5%, 93.1%, 87.5%, and 91.1%, respectively.

CONCLUSION

Accurate assessment of Crohn's disease activity is achieved by using an activity score providing an overall interpretation of MRI findings.

Computed tomography enteroclysis in the diagnosis of intestinal diseases

The role of computed tomography (CT) enteroclysis in the imaging of small bowel diseases is expanded with recent technological advances in multidetector CT system. Computed tomography enteroclysis is the examination of choice for patients with symptoms of intermittent small bowel obstruction, especially when there is a history of prior complex abdominal surgery, abdominal tumor, radiation therapy, and also in high grade obstructions with suspicion of extraintestinal internal fistula. Computed tomography enteroclysis is becoming the first-line modality for the evaluation of advanced and complicated small bowel Crohn disease. Computed tomography enteroclysis can also become an important complementary imaging technique to capsule endoscopy in the assessment of small bowel neoplasms and occult gastrointestinal hemorrhage. In this study, the technique and clinical applications of CT enteroclysis are reviewed; its advantages and limitations compared with the other imaging techniques and capsule endoscopy are discussed.

Four-section multidetector computed tomographic imaging of bowel obstruction: usefulness of axial and coronal plane combined reading

OBJECTIVE

To compare the diagnostic performance of axial and coronal views in multidetector-row computed tomography (MDCT) of patients with small-bowel obstruction (SBO) or large-bowel obstruction (LBO).

MATERIALS AND METHODS

Among 157 patients with clinical and radiographic findings of BO, 73 patients, who underwent MDCT and were found to have surgically proven SBO (49/73) or LBO (24/73), were retrospectively evaluated. Portal-enhanced MDCT was performed using 4 x 2.5-mm collimation; 3-mm-thick axial images were reconstructed with 2 mm of increment. Coronal views were reformatted using 3-mm-thick sections with 1 mm of increment. Three radiologists analyzed axial (session A), coronal (session B), and axial plus coronal images (session C) to identify the site, cause, and type of BO. To correlate surgical findings and MDCT results, the bowel was divided into duodenum, oral jejunum, aboral jejunum, oral ileum, aboral ileum, cecum/ascending colon, transverse colon, descending colon, and sigmoid colon/rectum. The mean diagnostic accuracy and the mean confidence score of each reader and each reading session were calculated.

RESULTS

The diagnostic accuracy of axial images was higher than that of coronal views (P = 0.014) in SBO, whereas no significant differences were found in LBO. The definition of the SBO cause was correctly assessed in 45 of 49 patients during session A, in 40 of 49 during session B, and in 45 of 49 during session C. In patients with LBO, the cause was correctly assessed in 21 of 24 patients during session A and in 22 of 24 patients during sessions B and C. All readers interpreted axial plus coronal images with a significantly higher confidence level than axial or coronal views alone, either for the detection of the site (P = 0.002) or for the identification of the cause (P < 0.001) of SBO and LBO.

CONCLUSION

The MDCT allowed accurate detection of the site and the cause of obstruction. In SBO, axial images yielded a higher diagnostic accuracy than coronal views, whereas in LBO, no differences were found between axial and coronal planes. The reading of axial plus coronal views significantly improved diagnostic confidence.

Unenhanced MDCT in Patients with Suspected Urinary Stone Disease: Do Coronal Reformations Improve Diagnostic Performance?

OBJECTIVE

The objectives of our study were to assess whether coronal reformations improve the diagnostic performance of MDCT in patients with acute flank pain and suspected urinary stone disease; and to determine if performing such reformations from 3-mm-thick sections is sufficient or if it is necessary to perform reformations from thinner sections.

MATERIALS AND METHODS

We included 147 consecutive patients (72 women and 75 men; mean age +/- SD, 58 +/- 18.1 years) with suspected urinary stone disease who underwent unenhanced MDCT. Scans were obtained with a 4 x 1 mm collimation and were reconstructed with a section thickness of 1.25 and 3 mm. We compared the diagnostic yield of 3-mm axial sections with that of coronal reformations reconstructed from 1.25- and 3-mm axial sections. Imaging data were evaluated in random order by two radiologists. The significance of the difference between the axial sections and coronal multiplanar reformations (MPRs) was tested for the number, size, and location of uroliths and for the presence of alternative diagnoses. The time required for review by both observers was recorded.

RESULTS

We found uroliths in 72 patients. There was no difference between 3-mm axial sections and coronal reformations from 1.25-mm sections with regard to the number of detected stones (n = 264 for both protocols), whereas coronal reformations from 3-mm sections revealed significantly fewer calcifications (n = 255, p = 0.016). Coronal reformations did not improve the localization of calcifications. Review time, however, was significantly shorter for coronal reformations than for axial sections (p = 0.001); however, coronal reformations were less sensitive than axial sections for the detection of additional findings suggestive of alternative diagnoses in 16 (30%) of 53 patients.

CONCLUSION

Coronal reformations from MDCT do not improve urinary stone detection but may reduce evaluation time; however, there is the danger of missing additional findings. Coronal reformations reconstructed from thick (i.e., 3-5 mm) axial sections may result in reduced detection of small stones and should therefore be avoided.

[CT enteroclysis: a pictorial essay]

The objective of the CT-enteroclysis is to distend the entire small intestine equally and sufficiently using a nasojejunal probe and an enteroclysis catheter for administration of a neutral opacifying agent. Today this is the best radiological method available to explore the small intestine because of its good spatial resolution and the rapidity of the exam. It is a high-performance exam when searching for transmural and extramural pathologies, in particular small tumoral lesions. It remains less effective in the exploration of anomalies of the lumen's mucosal lining, contrary to videocapsule endoscopy and the double-balloon enteroscope. It has been recognized that the CT-enteroclysis is a high-performance examination that should replace the small-bowel follow-through exam. However, there are undeniable disadvantages: higher does of radiation, patient discomfort during placement of the enteroclysis catheter, false-positive results, long interpretation time, and the impossibility of exploring the endoluminal aspect of the intestinal mucosal lining. All radiologists should therefore become familiar with the problems involved with this exam and its signs and patterns, which are illustrated in this pictorial review.

MDCT diagnosis of appendicitis using only coronal reformations

The purpose of this study was to assess the feasibility of diagnosing appendicitis based on coronal reformations without the aid of transverse images. Abdominal and pelvic computed tomography (CT) scans of 53 patients (27 with appendicitis and 26 without appendicitis) were reviewed. All scans were obtained using a four-slice multi-detector row CT. The radiologists were not aware of the final diagnosis. Cases were reviewed for the visualization of the appendix and presence of appendicitis. All images were reviewed on picture archiving and communication systems. There were no false positives for diagnosing appendicitis when using either the transverse or coronal reformations. Appendicitis was not seen on the coronal images in one case, and there were no false negatives when transverse reformations alone were used. This difference was not statistically significant (p < 0.0001 for both modes of display). The sensitivity for diagnosing appendicitis based on the coronal images alone was 96%, the specificity was 100%, and the accuracy was 98%. Coronal reformations decreased the number of images reviewed by 19%. CT diagnosis of appendicitis based on the coronal images is accurate.

Multi-detector row CT of the small bowel: peak enhancement temporal window--initial experience

PURPOSE

To prospectively determine quantitatively and qualitatively the timing of maximal enhancement of the normal small-bowel wall by using contrast material-enhanced multi-detector row computed tomography (CT).

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the institutional review board. After information on radiation risk was given, written informed consent was obtained from 25 participants with no history of small-bowel disease (mean age, 58 years; 19 men) who had undergone single-level dynamic CT. Thirty seconds after the intravenous administration of contrast material, a serial dynamic acquisition, consisting of 10 images obtained 5 seconds apart, was performed. Enhancement measurements were obtained over time from the small-bowel wall and the aorta. Three independent readers qualitatively assessed small-bowel conspicuity. Quantitative and qualitative data were analyzed during the arterial phase, the enteric phase (which represented peak small-bowel mural enhancement), and the venous phase. Statistical analysis included paired Student t test and Wilcoxon signed rank test with Bonferroni correction. A P value less than .05 was used to indicate a significant difference.

RESULTS

The mean time to peak enhancement of the small-bowel wall was 49.3 seconds +/- 7.7 (standard deviation) and 13.5 seconds +/- 7.6 after peak aortic enhancement. Enhancement values were highest during the enteric phase (P < .05). Regarding small-bowel conspicuity, images obtained during the enteric phase were most preferred qualitatively; there was a significant difference between the enteric and arterial phases (P < .001) but not between the enteric and venous phases (P = .18).

CONCLUSION

At multi-detector row CT, peak mural enhancement of the normal small bowel occurs on average about 50 seconds after intravenous administration of contrast material or 14 seconds after peak aortic enhancement.

Multidetector-row computed tomography diagnosis of small bowel obstruction: can coronal reformations replace axial images?

Feasibility of diagnosing small bowel obstruction on multidetector-row computed tomography (MDCT) using coronal reformations alone is evaluated. Three radiologists with subspecialty training in abdominal imaging reviewed abdominopelvic CT of 67 patients in consensus. Thirty-four patients had surgically proven small bowel obstruction. The remaining 33 patients had CT for other reasons and had no intestinal obstruction. The images were displayed in either axial or coronal planes and were reviewed on separate days . Each CT was evaluated for the presence of small bowel obstruction and its etiology when applicable. Thirty-three (100%) of 33 patients were correctly diagnosed not to have intestinal obstruction on coronal images. Thirty-four (100%) of 34 patients were correctly diagnosed to have small bowel obstruction on both forms of image display. There were five patients where the final surgical diagnosis for the etiology of small bowel obstruction did not agree with the interpretation of either the coronal or axial images; however, in all five patients, the interpretations of axial and coronal images were similar. In only one patient, the etiology of small bowel obstruction based on the coronal images did not agree with that of axial images and the surgical result; however, the site of small bowel obstruction was correctly diagnosed. There were approximately 20% fewer images in the coronal reformation data set, and the radiologists found review of these images to be easier for localizing the zone of transition in small bowel obstruction. Very high diagnostic accuracy can be achieved based on coronal reformations alone, and this form of image display may potentially be substituted for the conventional axial images. Since there are fewer images to review when the studies are displayed in coronal plane, this may positively impact radiologist workflow.

Multislice CT enteroclysis in the diagnosis of bowel endometriosis

This prospective study aims to evaluate the efficacy of multislice computed tomography combined with colon distension by water enteroclysis (MSCTe) in determining the presence and depth of bowel endometriotic lesions. Ninety-eight women with symptoms suggestive of colorectal endometriosis underwent MSCTe; locations, number of nodule/s, size of the nodule/s and depth of bowel wall infiltration were determined. Independently from the findings of MSCTe, all women underwent laparoscopy. MSCTe findings were compared with surgical and histological results. Abnormal findings suggestive of bowel endometriotic nodules were detected by MSCTe in 75 of the 76 patients with bowel endometriosis. MSCTe identified 110 (94.8%) of the 116 bowel endometriotic nodules removed at surgery; 6 nodules missed at MSCTe were located on the rectum. MSCTe correctly determined the degree of infiltration of the bowel wall in all of the 34 serosal bowel nodules identified at MSCTe. In six nodules reaching the submucosa, the depth of infiltration was underestimated by MSCTe. MSCTe had a sensitivity of 98.7%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 95.7% in identifying women with bowel endometriosis. MSCTe is effective in determining the presence and depth of bowel endometriotic lesions.

Multidetector CT enteroclysis versus barium enteroclysis with methylcellulose in patients with suspected small bowel disease

The purpose of this study was to evaluate the diagnostic accuracy of multidetector-CT enteroclysis (MDCT-E) versus barium enteroclysis with methylcellulose (BE) in clinically selected patients with suspected small bowel disease. We prospectively studied 52 patients who underwent unenhanced and contrast-enhanced multidetector CT (16 rows) after administration of 2-2.5 l of methylcellulose by naso-jejunal tube. BE was performed after administration of barium 60% w/v (200-250 ml) and methylcellulose (1-2 l). Patients with radiological signs of Crohn's disease were classified into the following subtypes: active, fibrostenotic, fistulising/perforating, reparative or regenerative subtypes. Twenty-eight patients also underwent endoscopy. The radiological prevalent subtype was the active subtype. The sensitivity, specificity and diagnostic accuracy of MDCT-E versus BE was 83%, 100% and 89%, respectively. BE showed five false negative CT cases due to early Crohn's disease; endoscopy confirmed positive cases of the CT and the BE, but showed one false negative case of the BE. Together, MDCT enteroclysis and BE permitted the diagnosis of Crohn's disease in 30 patients, adhesions in one patient, lymphoma in two patients and carcinoid tumours in two patients. In conclusion, MDCT-E permits good representation of pathological patterns. Early stages of Crohn's disease are better evaluated by BE.

CT enteroclysis: technique and clinical applications

CT enteroclysis (CTE) has been gradually evolving with technical developments of spiral and multidetector row CT technology. It has nowadays become a well-defined imaging modality for the evaluation of various small bowel disorders. Volume challenge of 2L of enteral contrast agent administrated to the small bowel via a nasojejunal catheter ensures luminal distension, the prerequisite for the detection of mural abnormalities, also facilitating the accurate visualization of intraluminal lesions. CT acquisition is centered on small bowel loops, reconstructed in thin axial slices and completed by multiplanar views. Image analysis is essentially done in cine-mode on work-stations. CTE is of particular diagnostic value in intermediate or advanced stages of Cohn's disease, including the depiction of extraintestinal complications. It has become the imaging modality of choice for the localization and characterization of small bowel tumors. The cause and degree of low-grade small bowel obstruction is more readily analyzed with the technique of CTE than conventional CT. Limitations of CTE concern the assessment of pure intestinal motility disorders, superficial mucosal lesions and arteriovenous malformations of the small bowel, which are not consistently visualized. CTE should be selectively used to answer specific questions of the small bowel. It essentially contributes to the diagnostic quality of modern small bowel imaging, and therefore deserves an established, well-defined place among the other available techniques.