Tc-99m Ethambutol Scintigraphy with Single-Photon Emission Computed Tomography in Diagnosis of Tubercular Iliopsoas Abscess.

Very few imaging techniques can demonstrate the presence of Mycobacterium tuberculosis in vivo. Technitium-99m Ethambutol scintigraphy is one of them, although literature on the utility of this technique is scarce. We describe a patient with iliopsoas abscess showing increased uptake on Tc-99 m ethambutol scintigraphy which was later confirmed to be tubercular by the microbiological analysis of pus.

99mTc-Ethambutol Scintigraphy with Single-Photon Emission Computed Tomography/Computed Tomography in Vertebral Tuberculosis.

Vertebral tuberculosis (TB) is a common form of extrapulmonary TB. Here, the slow-growing Mycobacterium bacillus reaches the disc space through the hematogenous route and leads to various complications. Radiological imaging and histopathology have been the mainstay of diagnosis, but radionuclide imaging techniques using radiolabeled antitubercular drugs have rarely found space in the clinical domain. Here, we present a case of vertebral TB, where a technetium-labeled antitubercular drug, ethambutol, was synthesized and used for imaging the bacteria in vivo. Thus, we demonstrate a rarely used potentially specific agent for tuberculous-infection imaging, which can be produced in-house, and provides rapid results.

Antibiotic scintigraphy in tuberculosis: A new horizon?

Tuberculosis (TB) continues to be a major cause of death worldwide that can be effectively treated with timely diagnosis and treatment. With the advent of nuclear imaging techniques like 18Fluorine Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography (18F-FDG) PET/CT, the diagnosis of tuberculosis, particularly its extrapulmonary forms, has received great impetus in cases where microbiological confirmation cannot be achieved. Although detection of mycobacteria either by staining, culture or nucleic acid amplification techniques still form the gold standard of diagnosis, newer diagnostic techniques are always welcome in the field which can expedite clinical management. Use of radiolabeled antibiotics is one such evolving sphere which needs further research. Moving ahead from radiolabeled leukocytes, antibiotics are being increasingly focused upon to act as a vehicle to locate infectious lesions. Antibiotics like ciprofloxacin have been labeled with diagnostic radionuclides such as Technetium-99m (Tc-99m) and used to image many infectious diseases with encouraging results in TB. However, the nonspecific attributes of ciprofloxacin have hindered its growth to assist the diagnosis of TB. A novel approach would be to utilize ethambutol, a specific antitubercular agent, which has been found to be safe and effective in the diagnosis of TB in the available published studies. Ethambutol is known to be taken up specifically by tubercular lesions. This forms the basis of using Tc-99m labelled ethambutol for imaging TB lesions. An added advantage would be its ability to differentiate tubercular from malignant and fungal lung lesions that are the usual differentials in patients suspected of having TB. Most of the studies involving ethambutol have been done in skeletal TB and its validation in other forms of TB is still awaited. Recently the role of PET-CT has also been explored in human studies using 11C Rifampicin to study the antibiotic uptake in tubercular lesions. This review summarizes the available evidence regarding diagnosis of TB by radiolabeled antibiotic imaging to emphasize the need for accelerated research in the fight against TB.

99mTc-Ethambutol Scan with SPECT/CT in Knee Joint Tuberculosis.

Modalities for in vivo imaging of Mycobacterium tuberculosis are limited and inadequately studied. One such modality is 99mTc-ethambutol scintigraphy which has shown promising results for diagnosis of tuberculosis (TB). Ethambutol, one of the primary antitubercular drugs, is bacteriostatic which acts on the mycolic acid cell wall synthesis of the M. tuberculosis. However, literature on its utility is scarce. The few studies that exist have reported its sensitivity and specificity between 90%- 95% and 71%-85%. We present here a case demonstrating the role of 99mTc-ethambutol scan in knee joint TB.