Preauthorization of CT and MRI examinations: assessment of a managed care preauthorization program based on the ACR Appropriateness Criteria and the Royal College of Radiology guidelines.

Purpose: To evaluate computed tomography (CT) and magnetic resonance imaging (MRI) utilization patterns before and after the implementation of a preauthorization program based on the ACR Appropriateness Criteria((R)) and the guidelines of the Royal College of Radiologists.
Materials and Methods: All CT and MRI requests received at the preauthorization center and CT and MRI examinations actually performed were identified by our health care service's centralized computerized database between January 1, 2000, and December 31, 2003. The obligatory preauthorization of CT and MRI requests was established for CT in September 2001 and for MRI in February 2002. All ambulatory CT and MRI examination requests sent for approval during the study period by most of our health care physicians were included in the study. The preauthorization program model is presented, and multiple parameters were evaluated from January 2000 to December 2003, before and after preauthorization was established.
Results: Before preauthorization was required, the CT and MRI utilization rates were constantly increasing by 20% and 5% per year for CT and MRI, respectively. After preauthorization was implemented, CT and MRI annual performance rates decreased from 25.9 and 7 examinations per 1,000, respectively, in 2000 to 17.3 and 5.6 examinations per 1,000, respectively, in 2003. The decreases in the utilization of MRI and CT imaging between 2001 and 2003 were 9% (12,129 compared with 11,070 MRI examinations) and 33% (81,223 compared with 57,204 CT examinations), respectively, resulting in substantial, statistically significant cost savings. The deferral rate ranged from 7.5% to 12.2% (mean = 9.8%) for CT and 13.9% to 21.4% (mean = 17%) for MRI. Deferred cases in CT were most commonly in neuroradiology, musculoskeletal radiology, and CT angiography (ranges of deferred cases 9% to 12%, 11% to 12%, and 10% to 12%, respectively). Deferred cases in MRI were most commonly in abdominal and chest radiology (ranges of deferred cases 32% to 37% and 20% to 31%, respectively). Computed tomography was more commonly utilized inappropriately by pediatric professions, and MRI was more commonly utilized inappropriately by medical subspecialty professions.
Conclusion: Preauthorization of CT and MRI requests results in a substantial decrease in utilization of these modalities with reduction in imaging costs.