(HealthDay News) – Patients referred for magnetic resonance imaging (MRI) of the knee by physician groups with a financial interest (FI) in MRI equipment are significantly more likely to have negative images than those referred by physicians with no FI (NFI), according to a study published in the December issue of Radiology.

Matthew P. Lungren, MD, from the Duke University Medical Center in Durham, NC, and colleagues retrospectively reviewed consecutive diagnostic MRIs of the knee interpreted by one radiology practice between January and April 2009 to examine whether ownership of MRI equipment by ordering physicians affects the likelihood of positive findings. The rate of knee abnormalities seen with MRI was used as a metric to compare utilization.

The researchers found that 205 of the 700 examinations had negative results: 117 of 350 in the FI group and 88 of 350 in the NFI group (P=0.016). There were no significant differences between the referring groups in the mean total number of positive abnormality subtypes per image (1.52 for the FI group and 1.53 for the NFI group; P=0.96).

“MR images of the knee among patients referred by the FI group were significantly more likely to be negative than those among patients referred by the NFI group,” the authors write.

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