INFLUENCE OF MAGNETIC-RESONANCE-IMAGING ON DIAGNOSIS AND THERAPEUTIC INTENTION

Rationale and Objectives. We assessed the contribution of magnetic res onance (MR) imaging to diagnostic and therapeutic decision making. Met hods. In a before-after observational study, we collected information from clinicians before and after patients were given MR examinations. We studied 406 cases selected from consecutive referrals to a single M R imaging facility in Manitoba between November 1, 1991, and October 3 0, 1992, for diagnosis of suspected brain, spinal column, or large-joi nt disorder. We examined changes in diagnoses, changes in clinician di agnostic confidence, and changes in therapeutic intentions after MR ex aminations. Results. Overall, MR imaging findings contributed to a cha nge in referring physicians' diagnoses or diagnostic confidence in 76% of the cases. Referring physicians reported a change in provisional d iagnosis in 42% of the cases. In 67% of these cases, the referring phy sician's provisional diagnosis was ruled out by normal examination fin dings; in the remaining 33% of the cases, an alternate diagnosis was o ffered by the consulting radiologist. In the 58% of the cases in which the provisional diagnosis was not altered by MR imaging findings, cli nical confidence in the provisional diagnosis increased in 46% of the cases and decreased in 12% of the cases. Management plans were reporte d to be altered in 54% of the cases; in 24% of the cases, therapeutic intentions changed from lower to higher levels of intervention. Conclu sion. Although MR imaging had a substantial influence on clinicians' d ecisions concerning diagnoses, the influence of MR imaging findings on therapeutic decision making, and therefore on patients' health status , was more moderate.