Role of 18F-FDG PET/CT in the Assessment of Response to Antitubercular Chemotherapy and Identification of Treatment Endpoint in Patients With Tuberculosis of the Joints

Abstract

Aims The aim of this study was to explore the utility of 18F-FDG PET/CT in the assessment of response to antitubercular treatment (ATT) and identification of treatment endpoint. Patients and Methods Forty patients (mean age, 35.3 years; 27 men) with clinically, radiologically, and histopathologically proven joint tuberculosis prospectively underwent clinical, biochemical, and PET/CT evaluation at baseline and after ~6, 12, and 18 months of ATT. Two patients were lost to follow-up, and 1 defaulted treatment. The remaining 37 were followed up until complete response (CR) was achieved. Images were visually and quantitatively (SUVmax ratio and metabolically active disease volume [MV]) evaluated by 2 experienced nuclear medicine physicians. Results Knee (n = 18) and ankle (n = 7) were the most frequently involved sites. The median MV and SUVmax ratio at baseline were 85.10 mL and 7.21, respectively. Five patients had noncontiguous vertebral involvement, 12 had pulmonary lesions, 2 had abscesses, 6 had mediastinal, and 30 had local lymph nodal involvement. Complete response was seen in 1/39, 11/37, and 30/37 patients after 6, 12, and 18 months of ATT. Significant reductions in visual analog scale score, tenderness, joint swelling, SUVmax ratios, and MVs (Friedman test, P < 0.001) were seen after each follow-up. The median time-to-CR in skeletal lesions was significantly longer than extraskeletal lesions (591 vs 409 days; Wilcoxon signed-rank test, P < 0.001). Time-to-CR in joint lesions positively correlated with MV at first follow-up (Pearson = 0.452, P = 0.005) and negatively correlated with percentage change in MV (first follow-up from baseline) (Pearson = −0.620, P < 0.001). ROC analysis yielded a cutoff of ≤71% reduction in MV at first follow-up (80.8% sensitivity, 81.8% specificity) to predict extension of ATT beyond 12 months. Using ROC analysis at second follow-up, a cutoff of ≤12.67 mL (for CR) was derived and was validated in patients at the third follow-up, with an accuracy of 84.4%. Patients with CR in PET/CT maintained disease-free state during a mean follow-up of 271 days. Conclusions 18F-FDG PET/CT is an excellent tool in estimating total disease burden, assessing response to ATT and identification of treatment endpoint in joint tuberculosis.

Molecular Imaging of Tuberculosis

“…97 For peripheral bones, FDG PET/CT has a similarly good utility for response assessment, and patients who achieve complete metabolic response experience a durable cure. 98 CNS TB: The CNS is a rare but important cause of morbidity and mortality among patients with EPTB. The brain is an obligate user of glucose for metabolism.…”

“…CMR on EOT FDG PET/CT has an excellent correlation with sterilizing cure across several studies involving patients with PTB and EPTB. 93,98,108 On the other extreme is the progressive disease phenotype characterized by the persistence of all or some of the lesions seen on the baseline scan and the appearance of new lesions due to TB on the EOT FDG PET/CT. This pattern is not uncommon among patients who have completed ATT and are declared cured according to the standard of care based on the current clinical routine.…”

Solitary Chest Wall Tuberculosis Mimicking a Malignancy Demonstrated on FDG PET/CT

“…[1][2][3] FDG PET/CT has vital value in evaluating total disease burden and treatment response in tuberculosis patients. 4,5 However, FDG PET/CT image of tuberculosis in various sites may be misdiagnosed as malignant tumor. [6][7][8][9] Wang et al 10 reported a case of primary chest wall tuberculosis presenting as intense FDG uptake in the posterior pleural mass and adjacent muscle without rib involvement mimicking a malignancy.…”

“…Isolated tuberculosis of the chest wall is very rare 1–3 . FDG PET/CT has vital value in evaluating total disease burden and treatment response in tuberculosis patients 4,5 . However, FDG PET/CT image of tuberculosis in various sites may be misdiagnosed as malignant tumor 6–9 .…”