Deployment and utilization of MR imaging in Michigan: observations of a statewide data base

Patterns of deployment and utilization of magnetic resonance (MR) imaging were studied with a Michigan Department of Public Health data base containing data regarding more than 218,000 patient visits. Michigan currently has 16 hospital-based fixed MR systems (magnets), 14 (13 operational) freestanding fixed magnets, and 11 (10 operational) mobile magnets operating at 45 host sites. The imaging volume for 1991 was approximately 127,000 procedures, with associated charges of $126,500,000. Central nervous system imaging accounted for 82.6% of procedure volume, with extremities accounting for another 12.9%. The average total charge per procedure ranged from $844 to $1,076, and the average professional charge per procedure ranged from $178 to $226. The annual throughput ranged from 1,356 to 7,480 procedures per magnet. Wide variation in many measures was observed both within and among hospital-based, freestanding, and mobile facility types. The use of computed tomography (CT) before MR imaging for the same diagnostic problem continues to be substantial (average, 44% for MR imaging of the head). Patterns of inpatient imaging and prior use of CT indicate that the technical benefit of mobile MR imaging should be investigated further.