A Novel Automatic Approach for Calculation of the Specific Binding Ratio in [I-123]FP-CIT SPECT.

Mahmudur G M Rahman,Muhammad M Islam,Tetsuya Tsujikawa,Hidehiko Okazawa

doi:10.3390/diagnostics10050289

Mahmudur G M Rahman, Muhammad M Islam + Show 2 more

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https://doi.org/10.3390/diagnostics10050289

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Abstract

A fully automatic method for specific binding ratio (SBR) calculation in [123I]ioflupane single-photon emission computed tomography (SPECT) studies was proposed by creating volumes of interest of the striatum (VOIst) and reference region (VOIref) without manual handling to avoid operator-induced variability. The study involved 105 patients (72 ± 10 years) suspected of parkinsonian syndrome (PS) who underwent [123I]ioflupane SPECT. The 200 images from our previous study were used for evaluation and validation of the new program. All patients were classified into PS and non-PS groups according to the results of clinical follow-up. A trapezoidal volume of interest (VOIt) containing all striatal intensive counts was created automatically, followed by VOIst setting using the previous method. SBR values were calculated from the mean values of VOIst and VOIref determined by the whole brain outside of VOIt. The low count voxels in the VOIref were excluded using an appropriate threshold. The SBR values from the new method were compared with the previous semi-automatic method and the Tossici–Bolt (TB) method. The SBRs from the semi- and fully automatic methods showed a good linear correlation (r > 0.98). The areas under the curves (AUCs) of receiver operating characteristic analysis showed no significant difference between the two methods for both our previous (AUC > 0.99) and new (AUC > 0.95) data. The diagnostic accuracy of the two methods showed similar results (>92%), and both were better than the TB method. The proposed method successfully created the automatic VOIs and calculated SBR rapidly (9 ± 1 s/patient), avoiding operator-induced variability and providing objective SBR results.

Highlights

Delineation of degenerative changes in the nigrostriatal dopaminergic neurons is a useful pathologic biomarker for differentiation of movement disorders [1]
Decline of dopamine transporter (DaT) expression was used for evaluation of the striatal neurodegenerative status in cases of parkinsonian syndrome (PS) or dementia with Lewy body (DLB). [123 I]ioflupane (FP-CIT), the most common DaT ligand for single-photon emission computed tomography (SPECT), is usually used for evaluation of this degenerative alteration [2,3,4,5,6]
Diagnostics 2020, 10, 289 accurately, the volume of interest of the striatum (VOIst ) and the reference region (VOIref ) should be created appropriately because specific binding ratio (SBR) values are determined by the count–concentration ratio of these two regions

Summary

Introduction

Delineation of degenerative changes in the nigrostriatal dopaminergic neurons is a useful pathologic biomarker for differentiation of movement disorders [1]. Decline of dopamine transporter (DaT) expression was used for evaluation of the striatal neurodegenerative status in cases of parkinsonian syndrome (PS) or dementia with Lewy body (DLB). [123 I]ioflupane (FP-CIT), the most common DaT ligand for single-photon emission computed tomography (SPECT), is usually used for evaluation of this degenerative alteration [2,3,4,5,6]. A quantitative assessment along with visual observation improves the diagnostic accuracy of DaT-SPECT imaging [7,8,9,10,11]. The specific binding ratio (SBR) calculated from the ratio of the striatal specific to non-specific binding in the brain is commonly used as a quantitative index of parkinsonian syndrome. Since the manual method often causes operator-induced variability in quantification, several automatic and semi-automatic methods were proposed to acquire better reproducibility and diagnostic accuracy [12,13,14,15,16,17,18,19]

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