Sacroiliitis in patients with low backache with Normal Lumbosacral spine MRI

Abstract

The detection and characterization of sacroiliac lesions on MR imaging has been well established, but its presence during evaluation of low backache cases has not been fully analyzed. Aim: determine the presence of sacroiliitis in cases with low back ache found to have a normal lumbosacral spine MRI and analyze its prevalence and radiological patterns Patients and Methods: A diagnostic study recruit 72 patients, they referred for lumbosacral spine MRI (1.5 Tesla) unit (16 channel coil) in Al- Sader- Medical City between March and August of the last year. Patients with abnormal LSS MRI were excluded .Information was taken from all patients about past medical and surgical history. Patients with normal LSS MRI were further evaluated for SIJ fast spin echo MRI applying the following study protocol: FSE coronal T1 WI & T2 WI STIR if abnormal finding seen then intravenous contrast gadolinium-DTPA about 0.1 mmol/ kg of body mass was injected and rescanned 10 minutes after injection to rule out the existing sacroiliitis or other SIJ abnormalities. Results: 72 patients with mean age of 33.2 ± 10.11 years ,male to female ratio was (1:2.483), a small but significant number of patients with sacroiliitis seen in patients with normal LSS MRI, there was no significant statistical differences between patients with normal finding and those with sacroiliitis. Three-fifth of the patients show narrowing of the joint space and one fifth show widening. The study revealed that all the patients had articular erosion and one fifth of the patients showed bone marrow edema. Conclusions: Sacroiliac joint lesions accounts small but significant number of lower backache patients. The enforcement of the diagnostic value and utility of adding a single fat suppressed sequence of the lumbo-sacral region in the coronal plane; adds marginally to the scan time but increases the yield of identifying incidental or manifest sacroiliac involvement in all cases referred for MRI for low backache.