Quantification analysis of 123I-IPT single photon emission computed tomography uptake in the striatum of parkinsonism with the standard magnetic resonance template

Abstract

This study evaluated the striatal specific binding ratio (SBR), the anterior to posterior ratio of the striatum (APR) and its reproducibility by employing a template-based registration (TBR) method using the coregistered to the standard T1 magnetic resonance (MR) template (SMRT) as a replacement for the MR image of each patient. The 123I-IPT single photon emission computed tomography (SPECT) images of 30 patients with Idiopathic Parkinson's disease (IPD) and 11 normal controls were analyzed. The region of interest (ROI) was positioned manually in the same slice showing the highest striatal activity using the manual ROI method, while the ROI were positioned automatically in the mid striatal slice of the SPECT image coregistered to the SMRT. The SBR obtained using the TBR method showed a strong correlation with those using the manual method in all groups: normal controls (r = 0.851, P = 0.001), early IPD (r = 0.841, P < 0.001), and severe IPD (r = 0.702, P = 0.007). The APR obtained by the TBR correlated with those using the manual method in only the early IPD (r = 0.72, P = 0.001), while those obtained using the manual method showed no correlation in the three groups (P > 0.05). The reproducibility (rmsCV) of the TBR method was 7.2% (normal controls, 5.2%; mild IPD, 4.2%; severe IPD, 10.8%), while the reproducibility of the manual method was 31% (normal controls, 19.7%; mild IPD, 21.7%; severe IPD, 46.2%). This shows that the use of 123I-IPT SPECT for assessing IPD is affected by the method used to position the striatal ROI. This study showed that the TBR method using the SMRT is useful in diagnosing the IPD and assessing the disease severity with a high reproducibility, indicating a possibility of using the TBR method as a good replacement for the manual method.