CT screening for colorectal cancer

Diagnostic utility of whole body CT scanning in patients with unexplained weight loss

BACKGROUND

Unexplained weight loss is a non-specific complaint with myriad potential etiologies. Increasingly, whole body CT studies are being performed in patients with unexplained weight loss to exclude organic etiologies such as malignancy. Our study aims to assess the diagnostic accuracy and yield of whole body CT in these patients.

METHODS AND MATERIALS

Patients who had a whole body CT scan for investigation of unexplained weight loss as their primary complaint from 2009-2012 were retrospectively reviewed. CT scans were classified into 4 categories: (1) Definite/highly suspicious for underlying organic cause (2) Indeterminate for underlying organic cause (3) No findings accounting for weight loss and only incidental findings and (4) Normal study. Scan findings were correlated with the final diagnosis after all investigations. Univariate logistic regression was performed to determine associations between patient's baseline variables and positive CT scan findings.

RESULTS

Of 301 eligible patients during the study period, 101 patients were excluded due to known history of malignancy, inadequate follow-up or inadequate scan technique. 200 patients were included in the final analyses. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CT for organic pathology were 72.0%, 90.7%, 87.0%, 78.9% and 82.0% respectively. Additional symptoms, abnormal physical examinations, anemia, and raised tumor markers were significantly correlated with positive CT findings. Overall, the diagnostic yield of whole body CT scan for patients with unexplained weight loss was 33.5%.

CONCLUSIONS

Whole body CT imaging may be a useful investigation for the noninvasive workup of patients with unexplained weight loss, with diagnostic yield of 33.5% and good sensitivity, specificity, positive and negative predictive values for organic etiologies.

Intravenous contrast enhanced computed tomography colonoscopy in children with suspected colonic polyps

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of intravenous contrast enhanced computed tomographic colonoscopy (IVCTC) in the diagnosis of clinically suspected colorectal polyps in children, using conventional colonoscopy (CC) as the gold standard.

METHODS

This was a prospective study conducted between July 2008 and June 2010. 30 pediatric patients with history of rectal bleeding and clinically suspected to have colorectal polyps were enrolled. All of the patients underwent IVCTC followed by CC. 30 IVCTC and 31 CC were performed in 30 patients. The findings of IVCTC were compared with those of CC. Statistical analysis was performed to obtain diagnostic performance values of IVCTC on per polyp (sensitivity and positive predictive value) and per patient (sensitivity, specificity, positive predictive value and negative predictive value) basis.

RESULTS

By IVCTC, 63 polyps were detected in 28 patients of which 53 polyps were eligible for inclusion in the statistical analysis. 60 polyps were detected by CC in 28 patients of which 50 polyps were eligible for inclusion in the statistical analysis. The per polyp sensitivity and positive predictive values were 94% and 88.6% respectively. The per patient sensitivity, specificity, positive predictive value, and negative predictive values were 96.4, 50, 96.4, and 50% respectively. Twenty polyps, in 10 patients, were visualized only after intravenous contrast administration of which 5 polyps, in 5 patients, were likely to have been missed in the absence of the intravenous contrast injection as these polyps were submerged in fluid. Four patients would have had a false negative CTC examination if the intravenous contrast had not been injected; while in another patient, the number of polyps would have been underestimated.

CONCLUSION

CTC is capable of serving as a safe and efficient non-invasive tool for evaluating children with clinically suspected colorectal polyps. Administration of intravenous contrast improves the sensitivity of polyp detection on CTC.

The GI fluoroscopy suite in the early twenty-first century

Since the application of cross-sectional imaging to the examination of the gastrointestinal tract, dramatic changes have occurred in the modern gastrointestinal fluoroscopic suite. Besides the great decrease in use of fluoroscopy, the types of fluoroscopic examinations requested and performed nowadays are different from those of just 2 or 3 decades ago. This paper will review the recent history and the current uses of fluoroscopy in adults at the beginning of the twenty-first century, illustrated by case images and utilization data from a large academic medical center. Fluoroscopy survives because of its unique illustration of motility in real-time, its superior detection and accurate localization of leaks in post-operative patients, and its ability to provide immediate answers and targeted examinations tailored to the individual patient.

Small bowel hydro-MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?

PURPOSE

To assess the impact of an additional rectal enema filling in small bowel hydro-MRI in patients with Crohn's disease.

MATERIALS AND METHODS

A total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast-enhanced T1w three-dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal-to-noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25).

RESULTS

The terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false-negative diagnoses of terminal ileitis.

CONCLUSION

Our data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered.

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.

Dark lumen magnetic resonance colonography: comparison with conventional colonoscopy for the detection of colorectal pathology

BACKGROUND

The purpose of this study was to assess the feasibility and usefulness of a new magnetic resonance (MR) colonography technique for the detection of colorectal pathology in comparison with conventional colonoscopy as the standard of reference.

PATIENTS AND METHODS

A total of 122 subjects with suspected colorectal disease underwent "dark lumen" MR colonography. A contrast enhanced T1w three dimensional VIBE sequence was collected after rectal administration of water. The presence of colorectal masses and inflammatory lesions were documented. Results were compared with those of a subsequently performed colonoscopy.

RESULTS

MR colonography was found to be accurate regarding detection of clinically relevant colonic lesions exceeding 5 mm in size, with sensitivity and specificity values of 93%/100%.

CONCLUSION

Dark lumen MR colonography can be considered as a promising alternative method for the detection of colorectal disease. In addition, it allows assessment of extraluminal organs.