Ben Eugene Paxton MD, Abstract Co-Author: Nothing to Disclose

Matthew Preston Lungren MD, Presenter: Nothing to Disclose

Sin-Ho Jung PhD, Abstract Co-Author: Nothing to Disclose

Peter George Kranz MD, Abstract Co-Author: Nothing to Disclose

Ramsey Khair Kilani MD, Abstract Co-Author: Medical Advisor, FrontRad Technologies

To determine if ownership of MR imaging equipment by ordering physicians predicts the likelihood of positive findings on lumbar spine MRIs, and to evaluate lumbar spine MRI pathology rates as a metric for MR imaging utilization behavior.

A retrospective review was performed of 500 consecutive diagnostic lumbar spine MRIs ordered by two separate referring physician groups serving the same geographic community; the first had financial interest in the MRI imaging equipment used (FI group), the second had no financial interest in the MRI imaging equipment used (NFI group). All studies were performed with identical protocols and interpreted by one subspecialty musculoskeletal radiology practice with no financial interest in imaging equipment. Final reports were reviewed and considered positive with: moderate or severe spinal canal stenosis, moderate or severe neuroforaminal narrowing, moderate or severe facet degenerative disease, disk protrusion contacting a nerve root, and osseous abnormalities. The percentage of negative studies in each group was calculated. Among the positive scans, the frequency of positive lesions per scan and relative frequency of each lesion was also calculated for each group. Fisher exact test was used for the binomial variables and Wilcoxon rank sum test was used for a continuous variable or ordered categorical variables. All p-values are two-sided.

Among the 500 lumbar spine MRIs reviewed (250 in FI group and 250 in NFI group), 163 were negative (106 in FI, and 57 in NFI); there were 86% more negative scans in the FI group than in the NFI group (p<0.0001). Among the positive scans, there was no significantly significant difference in the average total number of positive lesions per scan 3.93 for FI and 4.31 for NFI (p=0.9783).

Lumbar spine MRIs referred by physicians with a financial interest in the imaging equipment used were significantly more likely to be negative than those referred by physicians with no financial incentive. Among the positive studies, there was no statistically significant difference in total number of lesions per scan suggesting highly similar distribution and severity of disease between the two patient samples.

Financial interest in imaging equipment may have an impact on the imaging referral patterns of ordering physicians; imaging findings may serve as metric of comparative and appropriate utilization.

Paxton, B, Lungren, M, Jung, S, Kranz, P, Kilani, R, A Case Study in Lumbar Spine MRI and Physician Self-referral of Imaging.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11009567.html