Single photon emission computed tomography with 99mTc hexamethyl propylene amine oxime (HMPAO) and focal motor seizures.

The proper localization of regions of interest (ROIs) in Single Photon Emission Computed Tomography (SPECT) is an essential task. The limited spatial resolution makes it difficult to define regions by their structure. The particular problems are: 1) the difficulty to find the appropriate slice and its orientation in space; 2) the individual variation of the brain in dimension and shape. Referring to the basic work of Talairach and Szikla (1967), research is conducted to overcome these methodical problems in interpreting cranial computed tomography by using a proportional localization system. We analyzed four cases with focal motor seizures of different aetiology (tumour, hemorrhagic infarction, intracerebral hematoma, multifocal leukencephalopathy) by 99mTc HMPAO SPECT. The accumulation of the radiopharmacon was measured in ROIs which were delineated with the aid of the above mentioned system. The regions were selected in accordance to the autoradiographic study of penicillin induced epileptic seizures in animal experiments. Dependent on the severity of the clinical manifestation we were able to document the involvement of the supposed primary focus and of several related zones. We suggest that this approach should prove some usefulness in the examination of the interdependency of different brain areas.