PET Scans Predict Efficacy of Multidrug-Resistant Tuberculosis Treatment in HIV Patients

With the lack of knowledge of tuberculosis--as well as in the practices, programs, and strategies used to combat the disease and coinfection with human immunodeficiency virus (HIV)--the spread of multidrug-resistant (MDR) tuberculosis poses a major problem for the healthcare community. New research, however, revealed that the use of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans could help to determine earlier if treatment for tuberculosis is working or if the disease is MDR.

The study's findings were published in the June 2011 issue of the Journal of Nuclear Medicine. Tuberculosis and HIV have been linked since the AIDS epidemic began. About 33.2 million people worldwide are living with HIV, and an estimated one-third of them are coinfected with tuberculosis. In 2008, the number of MDR tuberculosis cases reached between 390,000-510,000, or 3.6% of all incident tuberculosis cases. MDR tuberculosis is very difficult to treat and is frequently fatal.

"Early detection of drug resistance of tuberculosis allows the initiation of an appropriate treatment, which may significantly affect patient survival. Currently, more than two-thirds of patients with MDR tuberculosis die," said Mike Sathekge, MD, PhD, from the department of nuclear medicine, University of Pretoria (South Africa), and lead author of the study.

In the prospective pilot study, 24 patients with tuberculosis underwent 18F-fluorodeoxyglucose positron emission tomography (FDG PET) scans prior to receiving tuberculosis treatment--the standard triad: isoniazid, rifampicin, and ethambutol. After four months of treatment, the patients received another 18F-FDG scan to measure averaged maximum standardized uptake value (SUVmax)--which measures glucose metabolic activity--derived from early and delayed imaging, percentage change in SUVmax and number of involved lymph node basins.

The researchers discovered that SUVmax of involved lymph nodes, number of involved lymph node basins, and C-reactive protein levels assessed by the PET scan were significantly higher in nonresponders than responders. It was determined that a cutoff of five or more lymph node basins allowed for a separation of treatment responders and nonresponders.

According to Dr. Sathekge, "18F-FDG PET has the potential to become a valuable clinical adjunct to the already available genotypic and phenotypic tests in patients for whom such tests are not feasible, are inconclusive, or are too lengthy to be of clinical relevance."

Other involved in the study included researcher from the University Hospital Leuven (Leuven, Belgium), and the University Hospital Ghent (Ghent, Belgium).

Related Links:
University of Pretoria
University Hospital Leuven
University Hospital Ghent