MRI of osteomyelitis. Sensitivity and specificity of STIR sequences in comparison to contrast-enhanced T-1 spin echo sequences

Purpose: To evaluate the need for additional MR sequences including adminis tration of Gd-DTPA after inconspicuous Short-Tau Inversion-Recovery (STIR) sequence to exclude the diagnosis of osteomyelitis. Material and Methods: 1 12 MR examinations of 79 patients acquired for the detection of possible os teomyelitis were analyzed retrospectively. All examinations were performed at 0.5 T including STIR, T-1-weighted spin echo sequences (T-1 SE) before a nd after application of Gd-DTPA. Additionally, 93 T-2-weighted spin echo se quences were available. The examinations were analyzed by two experienced r adiologists. First, the STIR sequences were studied, followed by the T-1 SE images before and after administration of contrast material. Finally, the T-2-weighted images were evaluated. Diagnoses were confirmed by operation ( 22), biopsy (10), and follow-up (80). Results: In 53 cases osteomyelitis wa s diagnosed, while the remaining 59 cases suffered from another disease. Th e sensitivity of the STIR sequence was 100% while the specificity for osteo myelitis was 49.2%. The specificity increased to 79.7% by including T1SE im ages into the analysis and reached 83.1% after considering the contrast enh anced images. T-2-weighted images yielded no additional information. Conclu sion: The combination of STIR and T1SE images shows a high sensitivity and specificity for osteomyelitis, thus obviating the need for any additional e xaminations.