Diagnostic performance of the specific uptake size index for semi-quantitative analysis of I-123-FP-CIT SPECT: harmonized multi-center research setting versus typical clinical single-camera setting

Abstract

Introduction The specific uptake size index (SUSI) of striatal FP-CIT uptake is independent of spatial resolution in the SPECT image, in contrast to the specific binding ratio (SBR). This suggests that the SUSI is particularly appropriate for multi-site/multi-camera settings in which camera-specific effects increase inter-subject variability of spatial resolution. However, the SUSI is sensitive to inter-subject variability of striatum size. Furthermore, it might be more sensitive to errors of the estimate of non-displaceable FP-CIT binding. This study compared SUSI and SBR in the multi-site/multi-camera (MULTI) setting of a prospective multi-center study and in a mono-site/mono-camera (MONO) setting representative of clinical routine. Methods The MULTI setting included patients with Parkinson’s disease (PD, n = 438) and healthy controls ( n = 207) from the Parkinson Progression Marker Initiative. The MONO setting included 122 patients from routine clinical patient care in whom FP-CIT SPECT had been performed with the same double-head SPECT system according to the same acquisition and reconstruction protocol. Patients were categorized as “neurodegenerative” ( n = 84) or “non-neurodegenerative” ( n = 38) based on follow-up data. FP-CIT SPECTs were stereotactically normalized to MNI space. SUSI and SBR were computed for caudate, putamen, and whole striatum using unilateral ROIs predefined in MNI space. SUSI analysis was repeated in native patient space in the MONO setting. The area (AUC) under the ROC curve for identification of PD/“neurodegenerative” cases was used as performance measure. Results In both settings, the highest AUC was achieved by the putamen (minimum over both hemispheres), independent of the semi-quantitative method (SUSI or SBR). The putaminal SUSI provided slightly better performance with ROI analysis in MNI space compared to patient space (AUC = 0.969 vs. 0.961, p = 0.129). The SUSI (computed in MNI space) performed slightly better than the SBR in the MULTI setting (AUC = 0.993 vs. 0.991, p = 0.207) and slightly worse in the MONO setting (AUC = 0.969 vs. AUC = 0.976, p = 0.259). There was a trend toward larger AUC difference between SUSI and SBR in the MULTI setting compared to the MONO setting ( p = 0.073). Variability of voxel intensity in the reference region was larger in misclassified cases compared to correctly classified cases for both SUSI and SBR (MULTI setting: p = 0.007 and p = 0.012, respectively). Conclusions The SUSI is particularly useful in MULTI settings. SPECT images should be stereotactically normalized prior to SUSI analysis. The putaminal SUSI provides better diagnostic performance than the SUSI of the whol...

Diffusion Tensor Imaging in Parkinson's Disease and Parkinsonian Syndrome: A Systematic Review

“…The best quantitative assessment on DAT-SPECT is to measure the striatal dopamine transporters binding ratio (SBR) in the left and right putamen and caudate nucleus. Studies have demonstrated substantial SBR signal loss in early PD patient relative to controls (151,152). Recent machine learning techniques (such as using the support vector machine, SVM) have shown that the SBR measures achieve high accuracies (97-100%) in predicting early PD (153,154).…”

Impact of age and sex correction on the diagnostic performance of dopamine transporter SPECT

“…One-hundred-and-twenty-two patients from clinical routine were recruited retrospectively from the database of the Department of Nuclear Medicine of the University Medical Center Freiburg. Data of these patients have been used previously to test the diagnostic performance of the specific uptake size index for semi-quantitative analysis of FP-CIT SPECT [ 43 ].…”

“…Hottest voxels analysis in large unilateral ROIs predefined in MNI space was used to compute the unilateral putamen SBR [ 43 ]. More precisely, the unilateral putamen SBR was calculated as mean scaled voxel intensity in the 10-ml hottest ROI voxels − 1.…”

Impact of the size of the normal database on the performance of the specific binding ratio in dopamine transporter SPECT

“…In addition, hottest voxels (HV) analysis was performed using large unilateral ROIs predefined in MNI space [30]. The ROIs for HV analysis were much bigger than the actual putamen volume in order to guarantee that all counts originating from the putamen were included.…”