Colon cancer screening with virtual colonoscopy: promise, polyps, politics.

Virtual colonoscopy (CT colonography) promises to become a primary method for colorectal cancer screening and return radiologists to a major role in colon cancer prevention. Results from major centers in the United States show accuracy to be comparable to conventional colonoscopy for detection of polyps of significant size--that is, greater than 10 mm--with few false-positives. The advent of virtual colonoscopy has also heightened awareness of the natural history of colonic polyps, particularly in terms of identifying an appropriate target size for detection in colorectal screening programs. Small polyps (<10 mm) are often either hyperplastic on histology or are unlikely to progress to frank cancer in the patient's lifetime and are therefore of little clinical significance for the average adult. Thus, the rationale for detecting and removing each and every colonic polyp regardless of size has come under increasing scrutiny in the context of cost-benefit analysis of various test strategies for colorectal cancer screening. Virtual colonoscopy may allow patients to obtain reliable information about the status of their colonic mucosa noninvasively and thus make a more informed decision as to whether to proceed to conventional colonoscopy for polypectomy.

Periventricular leukomalacia: relationship between lateral ventricular volume on brain MR images and severity of cognitive and motor impairment.

PURPOSE: To evaluate the utility of lateral ventricular volume measurements in predicting motor and cognitive impairment severity in children with periventricular leukomalacia (PVL), with or without seizures. MATERIALS AND METHODS: The charts of children with spastic cerebral palsy and PVL documented on brain magnetic resonance (MR) images were reviewed. Affected children were grouped by motor and cognitive impairment severity and seizure disorder. An age-matched control group was established. Lateral ventricular volumes were measured on two-dimensional T2-weighted spin-echo MR images. Analysis of variance was used to identify significant differences in mean lateral ventricular volume between groups. Paired analyses of differences were performed with the Bonferroni t method. RESULTS: Thirty-six children (24 boys, 12 girls) with spastic cerebral palsy and PVL and 21 age-matched control subjects (14 boys, seven girls) were identified. Mean lateral ventricular volumes of the moderate and marked motor deficit groups were significantly larger than those of the control and mild motor deficit groups (F = 29.24; alpha = .01). Mean lateral ventricular volumes of all cognitive impairment groups were significantly larger than those of the control and no-cognitive-impairment groups (F = 21.101 alpha = .01). There was no difference in mean lateral ventricular volume between children with PVL with or without seizures. CONCLUSION: Lateral ventricular volume measurements can be used as quantitative markers of clinical impairment severity and as clinical outcome predictors before formal testing is possible.

A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps.

BACKGROUND: Virtual colonoscopy is a new method of imaging the colon in which thin-section, helical computed tomography (CT) is used to generate high-resolution, two-dimensional axial images. Three-dimensional images of the colon simulating those obtained with conventional colonoscopy are then reconstructed off-line. We compared the performance of virtual and conventional colonoscopy for the detection of colorectal polyps. METHODS: We prospectively studied 100 patients at high risk for colorectal neoplasia (60 men and 40 women; mean age, 62 years). We performed virtual colonoscopy immediately before conventional colonoscopy. We inserted a rectal tube and insufflated the colon with air to the maximal level that the patient could tolerate. We administered 1 mg of glucagon intravenously immediately before CT scanning to minimize the degree of smooth-muscle spasm and peristalsis and to reduce the patient's discomfort. RESULTS: The entire colon was clearly seen by virtual colonoscopy in 87 patients and by conventional colonoscopy in 89. Fifty-one patients had normal findings on conventional colonoscopy. In the other 49, we identified a total of 115 polyps and 3 carcinomas. Virtual colonoscopy identified all 3 cancers, 20 of 22 polyps that were 10 mm or more in diameter (91 percent), 33 of 40 that were 6 to 9 mm (82 percent), and 29 of 53 that were 5 mm or smaller (55 percent). There were 19 false positive findings of polyps and no false positive findings of cancer. Of the 69 adenomatous polyps, 46 of the 51 that were 6 mm or more in diameter (90 percent) and 12 of the 18 that were 5 mm or smaller (67 percent) were correctly identified by virtual colonoscopy. Although discomfort was not specifically recorded, none of the patients requested that virtual colonoscopy be stopped because of discomfort or pain. CONCLUSIONS: In a group of patients at high risk for colorectal neoplasia, virtual and conventional colonoscopy had similar efficacy for the detection of polyps that were 6 mm or more in diameter.

MRI and MRCP in pancreaticobiliary malignancy.

Ultrasonography and CT scanning have been the standard techniques for demonstrating pancreatic carcinoma, although MR and more recently even endoscopic ultrasound have shown excellent results. MRCP is a specialized MR technique that shows fluid containing structures in a 2D image display similar to direct ERCP findings. Accuracy of MRCP (sensitivity, specificity) equals or exceeds ERCP for both biliary and pancreatic duct morphology. MRCP does not provide information with regard resectability. MRI can be applied to pancreaticobiliary malignancies as conventional MR, as MR angiography/venography or as MR cholangiopancreatography (MRCP). The technique and applications of each method differ. Although all have been well documented in the literature, their clinical role when compared to other evolving technologies such as helical CT and endoscopic ultrasound is still evolving.

Biliopancreatic malignancy current diagnostic possibilities: an overview.

Modern imaging of pancreatic cancer remains a daily challenge both for detection and staging. Helical CT scanning, MRI, and more recently endoscopic ultrasound (EUS) all contribute. Demonstration of local vascular anatomy for assessing resectability is increasingly performed by non-invasive methods such as CT and MR angiography avoiding the need for traditional catheter angiograms. While a variety of primary tumors can occur in the pancreas ductal adenocarcinoma is by far the most important clinically accounting for c.80% of pancreatic neoplasms. Moreover, cancer of the pancreas presents more frequent and complex diagnostic imaging problems than carcinomas of the biliary tract and will form the focus of this discussion.