Diagnostic Imaging of Thoracic-Abdominal-Pelvic Diseases: The Role for MRI as a High Diagnostic Yield, Safe and Cost-Effective Alternative to CT

Recommendations for the Practicing Radiologist: When and How to Use MRI

CT is an excellent modality for investigating many disease processes. However, there are two major factors that should be seen as rationales for migrating from CT to MRI for a number of fundamental indications for diagnostic body cross-sectional imaging. One is a growing appreciation of the potential risk of radiation exposure, particularly with the drive towards more diagnostic multiple-pass dynamic enhanced scans and higher resolution imaging. The other, and perhaps equally or more important, is that MRI should be seen as a primary diagnostic method for a growing number of common indications, particularly for liver, pancreas, kidney, bowel, gynecological, prostatic, and vascular diseases. It’s expected that the improved diagnostic yield of optimized MRI will be shown cost-effective in appropriate use, where favorable impact will be determined by showing that the total number of exams, time to correct diagnosis, number of unnecessary invasive diagnostic procedures, and inappropriately guided therapies are reduced through superior diagnostic sensitivity and specificity.

Indications for which CT should be considered a primary diagnostic method include patients with severe trauma, detection of renal and ureteric calculi, delineation of gastrointestinal perforation, for interventional procedure guidance, and for high-resolution depiction of interstitial lung disease.

Current practice for imaging patients with known or suspected intracranial or spinal neurological disorders has been increasingly oriented to using MRI for a primary imaging technique. A large potential impact on practice patterns would be expected from evaluating body imaging indications. Examples of common indications where alternatives to body CT should be recommended routinely include patients with known or suspected hepatobiliary, pancreatic, adrenal, and renal disease with the exception of renal calculi. For example, in patients who have had an unenhanced or single phase enhanced CT scan for initial assessment of disease and have been found to have a non-specific hepatic or pancreatic lesion, a multi-phase gadolinium-enhanced MRI should be preferred in place of a multi-phase CT study. Patients with right upper quadrant pain may be initially screened by abdominal ultrasound, and if non-diagnostic, a gadolinium-enhanced abdominal MRI is recommended. Similarly, female patients with gynecological or obstetrical concerns should be first imaged by ultrasound, followed by MRI if the sonographic examination is non-diagnostic.

Related Links for Reference and Educational Opportunities

General Reference

MRI Protocols

www.enhancedcme.com/assets/html/portal.html

Educational Opportunities for Radiologists

American College of Radiology – Classroom of the Future – Body MRI Mini-Fellowship Practicum: www.acr.org/EducationCenter/ACRFutureClassroom/details-bodymr.aspx

MRI Contrast Safety

September 2010 FDA safety warnings: