Technetium-99m hexamethylpropylene amine oxime leucocyte scintigraphy in the differential diagnosis of cerebral abscesses.

The diagnosis of brain abscess is often difficult, as the clinical symptoms are not specific. Computed tomography (CT) and magnetic resonance imaging (MRI) are highly sensitive, but different cerebral lesions, especially neoplasms, can have the same ring-like contrast enhancement. Brain abscess is a severe illness requiring rapid diagnosis to choose the most appropriate therapy. Technetium-99m hexamethylpropylene amine oxime (HMPAO)-labelled leucocyte scintigraphy is commonly used to detect an inflammatory process. The aim of this study was to present the results obtained with leucocyte scintigraphy in 65 patients with intracranial mass lesions and clinical findings compatible to or suggestive of brain abscess. The final diagnosis, based on surgery, clinical findings and stereotatic puncture, was brain abscess in 17 patients, primary brain neoplasm in 22, brain metastasis in 16, lymphoma in 2, cysticercosis in 2, hematoma in 2 and cerebral infarction in 4. 99mTc-HMPAO leucocyte scintigraphy was positive in all abscess cases. The scan was negative in the rest of the patients examined, with the exception of one lesion, which was finally diagnosed as a tumour (1 false-positive). All patients who did not have false-negative scans were treated with steroids. The sensitivity, specificity and diagnostic accuracy of leucocyte scintigraphy was 100%, 97.8% and 98.4%, respectively. In conclusion, in our experience, leucocyte scintigraphy is a valuable aid in the differential diagnosis between abscess and neoplasm.