Evaluation of pontine visualization with single photon emission computed tomography using N-isopropyl-p-(I-123)iodoamphetamine in normal and pathological cases

Pontine visualization with single photon emission computed tomography (SPECT) using N-isopropyl-p-[I-123]iodoamphetamine (I-123 IMP) was evaluated in 99 cases including 46 cases of brain infarction, 25 of other cerebrovascular disorders and 28 of brain tumor and in 19 normal subjects. In each case, SPECT using a rotating gamma camera was started at 30 minutes after intravenous administration of 111 MBq of I-123 IMP. Transverse images were reconstructed parallel to the cantho-meatal line and displayed on films. Pontine visualization was visually classified into three grades: high radioactive accumulation confined to the pons with clear contour (Grade 3), faint accumulation with indistinct contour in the pontine region (Grade 1), the pontine accumulation was identified but its activity was less significant (Grade 2). The results showed that grade of the pontine accumulation was lower in pathological cases compared to normal subjects. Six cases of brain stem lesion demonstrated pontine accumulation of grade 1 in 4 cases and of grade 2 in 2 cases. Lower grade was also revealed in 29 cases of crossed cerebellar diaschisis (CCD). No significant correlation was observed between classified grade of pontine accumulation and maximum counts of reconstructed images. We concluded that SPECT could detect brain stem lesions and that lower accumulation in pons with CCD positive cases was thought to partially reflect the reduced blood flow and metabolism in the pontine nuclei. (author)