Direct and indirect strategies of deep-learning-based attenuation correction for general purpose and dedicated cardiac SPECT

• Published in: European journal of nuclear medicine and molecular imaging 2022-07, Vol.49 (9), p.3046-3060
• Main Authors: Chen, Xiongchao, Zhou, Bo, Xie, Huidong, Shi, Luyao, Liu, Hui, Holler, Wolfgang, Lin, MingDe, Liu, Yi-Hwa, Miller, Edward J., Sinusas, Albert J., Liu, Chi
• Format: Article
• Language: English
• Subjects: Accuracy; Advanced Image Analyses (Radiomics and Artificial Intelligence); Attenuation; Cardiology; Computed tomography; Deep Learning; Heart; Humans; Image Processing, Computer-Assisted - methods; Image reconstruction; Imaging; Medical imaging; Medicine; Medicine & Public Health; Neural networks; Nuclear Medicine; Oncology; Original Article; Orthopedics; Photopeak; Radiology; Scanners; Single photon emission computed tomography; Tomography; Tomography, Emission-Computed, Single-Photon - methods
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-022-05718-8

Purpose Deep-learning-based attenuation correction (AC) for SPECT includes both indirect and direct approaches. Indirect approaches generate attenuation maps (μ-maps) from emission images, while direct approaches predict AC images directly from non-attenuation-corrected (NAC) images without μ-maps. For dedicated cardiac SPECT scanners with CZT detectors, indirect approaches are challenging due to the limited field-of-view (FOV). In this work, we aim to 1) first develop novel indirect approaches to improve the AC performance for dedicated SPECT; and 2) compare the AC performance between direct and indirect approaches for both general purpose and dedicated SPECT. Methods For dedicated SPECT, we developed strategies to predict truncated μ-maps from NAC images reconstructed with a small matrix, or full μ-maps from NAC images reconstructed with a large matrix using 270 anonymized clinical studies scanned on a GE Discovery NM/CT 570c SPECT/CT. For general purpose SPECT, we implemented direct and indirect approaches using 400 anonymized clinical studies scanned on a GE NM/CT 850c SPECT/CT. NAC images in both photopeak and scatter windows were input to predict μ-maps or AC images. Results For dedicated SPECT, the averaged normalized mean square error (NMSE) using our proposed strategies with full μ-maps was 1.20 ± 0.72% as compared to 2.21 ± 1.17% using the previous direct approaches. The polar map absolute percent error (APE) using our approaches was 3.24 ± 2.79% ( R 2  = 0.9499) as compared to 4.77 ± 3.96% ( R 2  = 0.9213) using direct approaches. For general purpose SPECT, the averaged NMSE of the predicted AC images using the direct approaches was 2.57 ± 1.06% as compared to 1.37 ± 1.16% using the indirect approaches. Conclusions We developed strategies of generating μ-maps for dedicated cardiac SPECT with small FOV. For both general purpose and dedicated SPECT, indirect approaches showed superior performance of AC than direct approaches.