Three-Dimensional Heart Segmentation and Absolute Quantitation of Cardiac 123I-metaiodobenzylguanidine Sympathetic Imaging Using SPECT/CT

Shintaro Saito; Kenichi Nakajima; Takayuki Shibutani; Hiroshi Wakabayashi; Hiroto Yoneyama; Takahiro Konishi; Hiroshi Mori; Aki Takata; Seigo Kinuya

doi:10.17996/anc.23-00002

Three-Dimensional Heart Segmentation and Absolute Quantitation of Cardiac ¹²³I-metaiodobenzylguanidine Sympathetic Imaging Using SPECT/CT

Ann Nucl Cardiol. 2023;9(1):61-67. doi: 10.17996/anc.23-00002. Epub 2023 Oct 31.

Authors

Shintaro Saito¹, Kenichi Nakajima², Takayuki Shibutani³, Hiroshi Wakabayashi¹, Hiroto Yoneyama⁴, Takahiro Konishi⁴, Hiroshi Mori¹, Aki Takata¹, Seigo Kinuya¹

Affiliations

¹ Department of Nuclear Medicine, Kanazawa University, Kanazawa, Japan.
² Department of Functional Imaging and Artificial Intelligence, Kanazawa University, Kanazawa, Japan.
³ Department of Quantum Medical Technology, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
⁴ Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan.

Abstract

Background: A three-dimensional (3D) approach to absolute quantitation of ¹²³I-metaiodobenzylguanidine (MIBG) sympathetic nerve imaging using single-photon emission tomography (SPECT) / computed tomography (CT) is not available. Therefore, we calculated absolute cardiac counts and standardized uptake values (SUVs) from images of 72 consecutive patients with cardiac and neurological diseases using ¹²³I-MIBG SPECT/CT and compared them with conventional planar quantitation. We aimed to develop new methods for 3D heart segmentation and the quantitation of these diseases. Methods: We manually segmented early and late SPECT/CT images of the heart in 3D, then calculated mean (SUV_mean) and maximum (SUV_max) SUVs. We analyzed correlations between SUVs and planar heart-to-mediastinum ratios (HMRs), and between washout rates (WRs) derived from the SUVs and planar data. We also categorized WRs as normal or abnormal using linear regression lines determined by the relationship between SPECT/CT and planar WRs, and assessed agreement between them. Results: We calculated SUV_mean and SUV_max from all early and late ¹²³I-MIBG SPECT/CT images. Planar HMRs correlated with early and late SUV_mean (R²=0.59 and 0.73, respectively) and SUV_max (R²=0.46 and 0.60, respectively; both p<0.0001). The SPECT/CT WRs determined based on SUV_mean and SUV_max (R²=0.79 and 0.45, p<0.0001) closely correlated with planar WRs. Agreement of high and low WRs between planar WRs and SPECT/CT WRs calculated using SUV_max and SUV_mean reached 88.1% and 94.4% respectively. Conclusions: We found that sympathetic nervous activity could be absolutely quantified in 3D from ¹²³I-MIBG SPECT/CT images. Therefore, we propose a new method for quantifying sympathetic innervation on SPECT/CT images.

Keywords: Cardiac innervation imaging; Heart-to-mediastinum ratio; Neurodegenerative disease; Quantitation method; Standardized uptake value; Washout rate.