MRI and CT of insufficiency fractures of the pelvis and the proximal femur.

OBJECTIVE: Pelvic and proximal femur insufficiency fractures are of increasing significance in our aging population, and cross-sectional imaging is challenging. The aims of this study were to compare the sensitivity of CT and MRI in detecting insufficiency fractures; to analyze the typical location, morphology, and combinations thereof in these fractures; to analyze imaging morphology; and to analyze associated clinical findings.

MATERIALS AND METHODS: MRI studies obtained at 1.5 T were analyzed in 145 patients with pelvic insufficiency fractures. In 64 of 145 patients, MRI and multidetector CT (MDCT) findings were compared. Imaging studies were analyzed by two radiologists; combined clinical history, findings from all imaging studies, and follow-up imaging studies served as the standard of reference.

RESULTS: In the subgroup undergoing both imaging techniques, MRI detected 128 of 129 (99%) fractures in 63 of 64 (98%) subjects, whereas CT detected only 89 of 129 (69%) fractures in 34 of 64 (53%) subjects. In particular, fractures at the femoral head and acetabulum were better detected with MRI. In the complete population, two or more fractures were found in 70.3% (102/145) of patients, and 89.2% (33/37) of patients with pubic insufficiency fractures had concomitant fractures at other locations. In 63 of 145 (43.4%) patients, a previous malignancy was found; in only 93 of 145 (64.1%) patients, the leading symptom responsible for the MRI examination was pain.

CONCLUSION: This study showed that MRI was substantially better than CT in detecting insufficiency fractures. In addition, two or more insufficiency fractures were frequently present, typical fracture combinations were found, and insufficiency fractures were frequently associated with malignant disease.