Solitary pulmonary nodule evaluation with Technetium-99m MIBI in tuberculosis-endemic area

¹ Dept of Internal Medicine, Tygerberg Academic Hospital, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa
² Dept of Nuclear Medicine, Tygerberg Academic Hospital, Faculty of Health Sciences, Stellenbosch University, Cape Town, South Africa

^* To whom correspondence should be addressed. E-mail: maceschuurmans{at}yahoo.com.

	Abstract

High prevalence of tuberculosis increases the odds for non-malignant solitary pulmonary nodules (SPN). Positron emission tomography (PET) using F-18 fluoro-deoxy-glucose is the method of choice to identify malignant SPNs requiring curative surgery but PET is not widely available. Technetium-99m-methoxy isobutyl isonitrile (MIBI) is inexpensive, widely available and shows increased uptake in malignant SPNs. The aim was to prospectively evaluate the diagnostic value of MIBI-Single Photon Emission Computed Tomography (SPECT) to distinguish between benign and malignant SPN in a tuberculosis-endemic area.

Forty-nine patients with radiologically indeterminate SPN (single lesion 6 cm in diameter) were prospectively evaluated with MIBI. The final diagnosis was established with bronchoscopy, fine needle aspiration, surgical resection or clinical follow-up for at least 2 years.

Twelve out of 13 malignant lesions (92%) showed increased uptake of MIBI while no uptake was observed in 33 out of 36 benign lesions (92%). MIBI uptake indicated malignancy with a sensitivity and specificity of 92%, respectively, and a negative predictive value of 97%.

In this tuberculosis-endemic area MIBI-SPECT evaluation of SPNs had a high negative predictive value. It therefore has the potential to prevent unnecessary surgical resections of benign nodules and serve as a low-cost alternative when PET is not available.