Optimization of iterative reconstruction parameters with attenuation correction, scatter correction and resolution recovery in myocardial perfusion SPECT/CT

• Published in: Annals of nuclear medicine Vol. 28; no. 1; pp. 60 - 68
• Main Authors: Okuda, Koichi, Nakajima, Kenichi, Yamada, Masato, Wakabayashi, Hiroshi, Ichikawa, Hajime, Arai, Hiroyuki, Matsuo, Shinro, Taki, Junichi, Hashimoto, Mitsumasa, Kinuya, Seigo
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 2014; Springer Nature B.V
• Subjects: Adult; Algorithms; Data processing; Female; Humans; Image Processing, Computer-Assisted - methods; Imaging; Male; Medicine; Medicine & Public Health; Multimodal Imaging; Myocardial Perfusion Imaging; Nuclear Medicine; Original Article; Phantoms, Imaging; Radiology; Scattering, Radiation; Signal-To-Noise Ratio; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Myocardial perfusion SPECT; Scatter correction; Ordered-subset expectation maximization; Attenuation correction; Depth-dependent resolution recovery
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/s12149-013-0785-6

Objective
The aim of this study was to characterize the optimal reconstruction parameters for ordered-subset expectation maximization (OSEM) with attenuation correction, scatter correction, and depth-dependent resolution recovery (OSEM
ACSCRR
). We assessed the optimal parameters for OSEM
ACSCRR
in an anthropomorphic torso phantom study, and evaluated the validity of the reconstruction parameters in the groups of normal volunteers and patients with abnormal perfusion.
Methods
Images of the anthropomorphic torso phantom, 9 normal volunteers and 7 patients undergoing myocardial perfusion SPECT were acquired with a SPECT/CT scanner. SPECT data comprised a 64 × 64 matrix with an acquisition pixel size of 6.6 mm. A normalized mean square error (NMSE) of the phantom image was calculated to determine both optimal OSEM update and a full width at half maximum (FWHM) of Gaussian filter. We validated the myocardial count, contrast and noise characteristic for clinical subjects derived from OSEM
ACSCRR
processing. OSEM with depth-dependent resolution recovery (OSEM
RR
) and filtered back projection (FBP) were simultaneously performed to compare OSEM
ACSCRR
.
Results
The combination of OSEM
ACSCRR
with 90–120 OSEM updates and Gaussian filter with 13.2–14.85 mm FWHM yielded low NMSE value in the phantom study. When we used OSEM
ACSCRR
with 120 updates and Gaussian filter with 13.2 mm FWHM in the normal volunteers, myocardial contrast showed significantly higher value than that derived from 120 updates and 14.85 mm FWHM. OSEM
ACSCRR
with the combination of 90–120 OSEM updates and 14.85 mm FWHM produced lowest % root mean square (RMS) noise. Regarding the defect contrast of patients with abnormal perfusion, OSEM
ACSCRR
with the combination of 90–120 OSEM updates and 13.2 mm FWHM produced significantly higher value than that derived from 90–120 OSEM updates and 14.85 mm FWHM. OSEM
ACSCRR
was superior to FBP for the % RMS noise (8.52 ± 1.08 vs. 9.55 ± 1.71,
p
 = 0.02) and defect contrast (0.368 ± 0.061 vs. 0.327 ± 0.052,
p
 = 0.01), respectively.
Conclusions
Clinically optimized the number of OSEM updates and FWHM of Gaussian filter were (1) 120 updates and 13.2 mm, and (2) 90–120 updates and 14.85 mm on the OSEM
ACSCRR
processing, respectively. Further assessment may be required to determine the optimal iterative reconstruction parameters in a larger patient population.