Cost-effectiveness of unenhanced MR imaging vs contrast-enhanced CT of the abdomen or pelvis.

OBJECTIVE The purpose of this study was to compare the cost of unenhanced MR imaging with that of CT with high- or low-osmolality contrast agents for abdominal or pelvic imaging in patients at risk for nephrotoxic effects induced by contrast material. MATERIALS AND METHODS Using decision analysis, we evaluated direct medical care costs associated with the use of CT with high- or low-osmolality contrast agents vs MR imaging. We used data from a variety of sources and assumed that the three imaging techniques provide nearly equivalent diagnostic information. The base-case analysis assumed that patients were at low risk (i.e., 2%) for development of nephrotoxic effects. Nephrotoxic effects were defined as increases in the serum level of creatinine of 50% or more above baseline. Our analysis took the perspective of the hospital and used estimated hospital costs, not charges. Sensitivity analyses were performed on risk estimates for development of nephrotoxic effects and for the estimates of medical care costs. RESULTS For the base case, CT with a high-osmolality contrast agent is the least costly imaging strategy. When the risk of nephrotoxic effects exceeds 5% for high-osmolality contrast agents or 2.6% for low-osmolality contrast agents, then MR imaging is the preferred strategy. The model is relatively insensitive to treatment costs. CONCLUSION From a hospital's perspective, MR imaging of the abdomen or pelvis is cost minimizing in patients at high risk for nephrotoxic effects induced by contrast agents. Use of low-osmolality contrast agents must reduce the frequency of nephrotoxic effects in high-risk patients by at least 50% to be less costly than MR imaging.