Comparison of bone SPECT and MRI in diagnosis and follow-up of spinal tuberculosis

Abstract

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Objectives: This prospective study was aimed to compare whole body planar scintigraphy (WBS), SPECT and MRI in diagnosis and follow-up of patients with tuberculosis (TB) of spine.

Methods: Twenty-five consecutive adult patients with strong clinical suspicion of TB spine were included in the study. All patients underwent WBS, SPECT and MRI at presentation and during antitubercular treatment follows up (average 12 months, range 7 –18 months). All baseline and post treatment MRI, SPECT, and WBS studies were evaluated qualitatively and quantitatively. A ‘significant’ improvement was considered when there was > 50% decrease in the radiotracer uptake compared to baseline study for SPECT and WBS and complete resolution of intra-osseous vertebral lesions and associated soft tissue masses on MRI. ‘Mild’ improvement was considered when there was 20 to 50% decrease in uptake intensity for SPECT and WBS; and reduction of abnormal intraosseous signal intensity and soft tissue mass (either pre or para vertebral or epidural collection), on MRI. ‘No’ improvement was considered when there was no decrease in the uptake on SPECT and WBS and MRI showed persistent intraosseous signal abnormality and no decrease in the soft tissue mass. Final outcome was based on histopathology and or clinical follow-up.

Results: Both MRI and bone SPECT showed a sensitivity of 100%, while WBS showed 84% sensitivity for initial detection of disease. In addition, MRI detected soft tissue involvement in all patients whereas WBS detected 5 extra-vertebral skeletal lesions in two patients. However, WBS was normal in 4 patients in which both MRI and SPECT detected lesions. Post treatment response on MRI, SPECT and WBS studies is shown in table 1.

Conclusions: MRI and bone SPECT showed similar sensitivities in the initial detection and follow-up of vertebral lesions in TB spine. MRI better detects localised bony lesions and soft tissue lesion. WBS detects multifocal lesions in entire skeleton in one examination but has lower sensitivity for detection of spinal lesion compared to SPECT.

Comparison of WBS, SPECT and MRI