Abstract
ObjectiveTo calculate the specific binding ratio (SBR) appropriately in dopamine transporter (DAT) imaging, a method for extracting the striatal volume of interest (VOI) was developed.MethodsThis study included 200 patients (72 ± 10 years) who were suspected of parkinsonian syndromes (PS) or dementia with Lewy body (DLB). The patients were divided into three groups of PS with dopaminergic degeneration, DLB and non-PS after [123I]ioflupane (FP-CIT) SPECT and clinical follow-up. The image data were reconstructed with CT attenuation correction and scatter correction, and with only CT attenuation correction (CTAC). The new method extracted striatal VOI according to the high-level counts and the average striatum volume, and calculated SBR using the reference occipital counts. The SBR values for each patient were obtained using the Tossici-Bolt method (SBRBolt) and our method. Reproducibility of SBR calculation using our method was compared by two operators.ResultsThe mean SBR values for the PS and DLB groups were significantly different from that of the non-PS group with both methods. The coefficients of variation of the SBR were significantly smaller with the proposed method compared with those of SBRBolt (p < 0.001), except for the CTAC images. There were no differences in SBR between the two operators using our method. The diagnostic accuracies with our method for the PS and DLB groups were 98.4 and 96.0%, respectively.ConclusionOur new method for SBR calculation in the FP-CIT SPECT showed less coefficients of variation with high reproducibility, which would be useful for clinical diagnosis and in assessing the severity of diseases in follow-up studies.
Highlights
Dopamine transporter (DAT) imaging using [ 123I]ioflupane (FP-CIT) SPECT is widely used for clinical assessment of the nigrostriatal function in patients with parkinsonian syndromes (PS) [1,2,3,4]
Taking cut-off values of specific binding ratio (SBR) of 2.0 for ACSC and 1.8 for CT attenuation correction (CTAC), which were determined by receiver operating characteristic (ROC) analysis, the new method could distinguish the patient groups with a diagnostic accuracy of 98.4% for PS and 96.0% for dementia with Lewy body (DLB)
Since C voi is an average of heterogeneous regional counts affected by counts outside of the striatum including spillover, and partial volume effect (PVE) caused by inclusion of cerebrospinal fluid (CSF) space or other structures [20], [Cvoi/Cr − 1] in the TB method is not necessarily identical to the SBR values from other methods
Summary
Dopamine transporter (DAT) imaging using [ 123I]ioflupane (FP-CIT) SPECT is widely used for clinical assessment of the nigrostriatal function in patients with parkinsonian syndromes (PS) [1,2,3,4]. To evaluate presynaptic functional reduction of the striata, the specific binding ratio (SBR), a semi-quantitative value of FP-CIT accumulation, is calculated using various methods. Many quantitative methods have been proposed to assist with visual image interpretation in cases of movement disorder with parkinsonism because visual evaluation relies on the observer’s ability and may. Annals of Nuclear Medicine (2019) 33:14–21 the semi-quantitative values of the striatal tracer accumulation between patient groups and healthy subjects. The proposed method has a semi-automatic procedure with an easy and operator-friendly process for accurate measurement of SBR. After 1.5× expansion, the pixel size of each slice was 2.20 mm in a 128 × 128 matrix, and a 6.0-mm Gaussian filter was applied
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