LONGITUDINAL STRESS-FRACTURES OF THE TIBIA - MRI FEATURES IN 2 CASES

Longitudinal stress fractures of the tibia are a recognized but unusua l finding in long distance runners. Two cases are presented in which t he diagnosis on plain films and scintigraphy (in one case) was not evi dent. Both patients were referred for MRI. Coronal short tau inversion recovery (STIR) sequences demonstrated extensive hyperintense longitu dinal intramedullary signal changes in the tibia. T1-weighted spin-ech o scans showed corresponding but less extensive regions of reduced sig nal intensity. In one case, enhancement of this area was seen followin g i.v. dimeglumine-gadopentetate (Gd-DTPA). Adjacent soft-tissue abnor mality and periosteal reaction was seen in one case but in neither pat ient was a fracture line identified. Thin section CT with sagittal ref ormats demonstrated an irregular intracortical longitudinal lucent fra cture line which was distinct from the nutrient foramen, establishing the diagnosis.