|LETTER TO THE EDITOR
|Year : 2016 | Volume
| Issue : 3 | Page : 420-421
18F-fluorodeoxyglucose positron emission/computed tomography in the diagnosis and follow-up of tuberculosis
Dhaval K Thakkar1, Vilas M Kulkarni1, Tanmayi V Kulkarni2, Amarjit Singh3, Venus Pagare4
1 Department of Radio-Diagnosis, Dr. D.Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
2 Department of Pathology, Dr. D.Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
3 Department of Radiology, Dr. D.Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
4 Department of Physiotheraphy, Dr. D.Y. Patil Medical College, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||17-May-2016|
Dhaval K Thakkar
Department of Radio-Diagnosis, Dr. D.Y. Patil Medical College, Pimpri, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Thakkar DK, Kulkarni VM, Kulkarni TV, Singh A, Pagare V. 18F-fluorodeoxyglucose positron emission/computed tomography in the diagnosis and follow-up of tuberculosis. Med J DY Patil Univ 2016;9:420-1
Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis (MTB), is a global pandemic and a leading infectious cause of morbidity and mortality worldwide. According to the World Health Organization (WHO) data, approximately 1.5 million deaths are attributed to TB annually, and one-third of the world's population is latently infected with MTB. India now boasts the dubious distinction of the highest TB burden in the world (WHO world TB data).
Tuberculosis control urgently requires accurate and prompt diagnosis to reduce disease transmission and burden. However, our diagnostic "toolkit" against TB remains woefully inadequate. The century-old tuberculin skin test (TST) has low specificity and sensitivity, and results are confounded by the previous administration of the BCG vaccine. The advent of the interferon-gamma release assays (IGRAs) has only partially ameliorated this situation, as though superior to the TSTs in some aspects, IGRAs have their own unique drawbacks.  Bacteriological confirmation is helpful in establishing the diagnosis in cases of smear-positive pulmonary TB and can also be used to evaluate treatment-response in such cases. However, in the case of extra-pulmonary/smear-negative disease, the diagnosis and evaluation of response-to-treatment depends heavily on clinical and/or radiological (chest X-ray) parameters. 
18F-fluorodeoxyglucose positron emission/computed tomography (18F-FDG PET/CT) is a functional imaging technique that monitors glucose metabolism in tissues; high FDG concentration on PET/CT represents increased cell glycolysis in activated macrophages, lymphocytes and granulocytes. It is being used as novel diagnostic method in pyrexias of unknown origin. Martinez et al. have recently performed a study to determine the ability of 18F-FDG PET/CT to evaluate therapeutic response to anti-TB treatment. The study was based on the hypothesis that 18F-FDG would accumulate in active granulomatous inflammation in TB, and this would subsequently reduce in response to anti-TB chemotherapy. Indeed, this was found to be the case in both pulmonary and extra-pulmonary TB. 
Importantly, the study concluded that the lack of 18F-FDG PET/CT accumulation in treated patients treated can be considered an indicator of positive response to treatment and sterilization of TB lesions. The authors suggest that patients in whom PET/CT does not show any improvement can be considered for a more aggressive diagnostic workup, including that for drug-resistant TB.  Therefore, we believe 18F-FDG PET/CT could be a new diagnostic and follow-up tool that can help fight "the white plague" of TB.
| References|| |
Belknap R, Daley CL. Interferon-gamma release assays. Clin Lab Med 2014;34:337-49.
Martinez V, Castilla-Lievre MA, Guillet-Caruba C, Grenier G, Fior R, Desarnaud S, et al.
(18)F-FDG PET/CT in tuberculosis: An early non-invasive marker of therapeutic response. Int J Tuberc Lung Dis 2012;16:1180-5.