Evaluation of Healed Status in Tuberculosis of Spine by Fluorodeoxyglucose-positron Emission Tomography/Computed Tomography and Contrast Magnetic Resonance Imaging

BACKGROUND: The healed status (end-point of treatment) in tuberculosis (TB) spine is not defined; hence optimum antitubercular therapy (ATT) duration is unresolved. We, for the first time, prospectively evaluated the healed status in TB spine by fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) and contrast magnetic resonance imaging (MRI) with the objective to define end-point of treatment in TB spine. MATERIALS AND METHODS: Thirty seven patients of TB spine diagnosed on clinicoradio imaging/cytology/histologically/molecular methods were enrolled, treated and were evaluated radiologically, by contrast MRI and FDG-PET/CT at 9 months. ATT was stopped on contrast MRI-based healing or absence of FDG uptake on PET-CT. ATT was continued in active/resolving lesion. Repeat evaluation was done at 12, 18, 24, and 30 months till healing is demonstrated. In this research work, we got contrast MRI and FDG-PET/CT done for the patients from government institution free of cost, so patients did not have to bear the burden of cost of these investigations. RESULTS: Twenty-eight patients achieved healed status out of which 11 demonstrated healed status on contrast MRI and FDG-PET/CT both, 6 were MRI active (contrast enhancement) but FDG-PET/CT healed, 2 were MRI healed but FDG-PET/CT active (soft-tissue standardized uptake value <2.0), 9 patients were MRI incompatible due to stainless steel implants (n = 6), and in 3 patients MRI could not be done due to financial constraints and were declared healed on FDG-PET/CT. FDG-PET/CT showed healed bone lesion in 28/28 (100%) and on MRI 13/19 (68.42%), respectively. We had 6 patients whose spine was stabilized with stainless steel implants where MRI could not be performed, MRI was useful in 13/25 cases (52%) to demonstrate healed lesion. 7, 6, 6, 5, 1, 2, and 1 cases achieved healed status at 9, 12, 18, 24, 30, 36, and 48 months of ATT intake, respectively. CONCLUSIONS: FDG-PET/CT is more useful to demonstrate the healed status than MRI and is the only imaging to demonstrate healed status when MRI could not be performed due to metallic implants. All patients achieved healed status at variable length of ATT intake; hence TB spine should be treated by ATT till healed status (end-point of treatment) is demonstrated by FDG-PET/CT (absence of FDG uptake) or contrast MRI.