Evaluation of meningioma aggressiveness by (99m)Tc-Tetrofosmin SPECT

Although meningiomas usually have a benign clinical course, atypical and malignant types of this brain tumor are associated with high recurrence rates and poor outcome; thus, DNA ploidy and S-phase -- as determined by DNA flow cytometry -- are useful indicators of their biological behavior. Brain single-photon emission computed tomography (SPECT) has been suggested as a potentially useful modality for the metabolic assessment of various brain tumors. This study evaluated whether (99m)Tc-Tetrofosmin ((99m)Tc-TF) uptake correlates with meningioma proliferative activity, as assessed by flow cytometry analysis.

Ten consecutive patients (3 males, 7 females, mean age 64.6 years) with a diagnosis of a symptomatic intracranial meningioma, planned to undergo surgery, were studied. Brain SPECT by (99m)Tc-TF was performed within a week prior to surgical excision and flow cytometric analysis was performed in the excised tissue. Tumoral radiotracer accumulation was first assessed visually. Semiquantitative image analysis was also performed, by calculating the lesion-to-normal (L/N) uptake ratio.

Benign meningiomas were diagnosed in 8/10 cases, the remaining 2/10 patients had anaplastic lesions. DNA aneuploidy was found in 2 lesions, the remaining tumors were diploid. There was a significant correlation between tracer uptake and the percentage of the cell fraction on S-phase (r=0.733, P=0.05). There was also a positive correlation between tracer uptake and the level of aneuploidy and tumor grade.

These results imply that (99m)Tc-TF brain SPECT may have the ability to discriminate benign meningiomas from malignant meningiomas pre-operatively, the tracer uptake being a likely indicator of their proliferative activity.