Physician Self-Referral for Diagnostic Imaging

One measure of the appropriateness of diagnostic imaging is the proportion of studies with normal results; too many normal studies implies excessive test ordering. Researchers used this metric to compare lumbar spine magnetic resonance imaging (MRI) ordered by two orthopedic practices of similar size in the same community. One practice owned the MRI equipment on which scans were performed (and thus derived financial gain from imaging); the other practice had no financial conflict of interest in MRI ordering and equipment. Physicians in both practices had similar training and years of experience.

Radiologists interpreted 250 consecutive lumbar spine MRIs from each group. A scan was considered positive if it showed substantial spinal stenosis,…