Viggo Blomlie MD, Presenter: Nothing to Disclose

Kaj Ericson MD, Abstract Co-Author: Nothing to Disclose

In a retrospective study, the potential of magnetic resonance (MR) imaging to detect stress-fractures of the lumbar pars interarticularis was investigated.

Thirty-two young athletic patients (23 men and 9 women) aged 7 to 19 years old (mean, 13,5) underwent MR examinations 1 to 52 weeks (mean, 12) after the onset of low back pain. Findings indicating bone marrow edema on T1- and T2-weighted fast spin-echo and, particularly, short inversion time inversion recovery (STIR) images were used to establish the diagnosis of a stress-fracture on MR imaging. Computed Tomography (CT) was used to confirm the diagnosis of a fracture and performed in all 32 patients within 0 to 38 days (mean, 6) after the MR examination. A visual evaluation was performed by 2 experienced radiologists non-blinded to clinical data.

Findings compatible with fractures were observed on STIR images in all 32 patients. On T1- and T2-weighted images however, bone marrow edema was difficult to detect and stress-fractures were therefore easily missed. The fractures of the pars interarticularis were seen at L5 in 31 (97 %) of the patients and at L4 in one patient. Fourteen (44%) of the 32 patients had bilateral fractures. CT confirmed the fractures in 29 (91%) of the 32 patients. In eight patients, CT disclosed additional fractures of the opposite pars interarticularis without accompanying bone marrow edema, probably reflecting older non-healed fractures.

MR imaging with STIR images can reliably detect stress-fractures of the lumbar pars interarticularis.

The potential of STIR imaging to detect stress-fractures of the lumbar pars interarticularis should be utilized in the MR examination of young athletic patients with low back pain.

Blomlie, V, Ericson, K, Stress Fractures of the Lumbar Pars Interarticularis: MR Appearance.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4428918.html