Phantom and clinical evaluation of bone SPECT/CT image reconstruction with xSPECT algorithm

Abstract

Background: Two novel methods of image reconstruction, xSPECT Quant (xQ) and xSPECT Bone (xB), that use an ordered subset conjugate gradient minimizer (OSCGM) for SPECT/CT reconstruction have been proposed. The present study compares the performance characteristics of xQ, xB, and conventional Flash3D (F3D) reconstruction using images derived from phantoms and patients. Methods: A custom-designed body phantom for bone SPECT was scanned using a Symbia Intevo (Siemens Healthineers), and reconstructed xSPECT images were evaluated. The phantom experiments proceeded twice with different activity concentrations and sphere sizes. A phantom with 28-mm spheres containing a 99m Tc-background and tumor-to-normal bone ratios (TBR) of 1, 2, 4, and 10 were generated, and convergence property against various TBR was evaluated across 96 iterations. A phantom with four spheres (13-, 17-, 22-, and 28-mm diameters), containing a 99m Tc-background at TBR4, was also generated. The full width at half maximum of an imaged spinous process (10 mm), coefficients of variance (CV), contrast-to-noise ratio (CNR), and recovery coefficients (RC) were evaluated after reconstructing images of a spine using Flash 3D (F3D), xQ, and xB. We retrospectively analyzed images from 20 patients with suspected bone metastases (male, n = 13) which were acquired using [ 99m Tc]Tc-(H)MDP SPECT/CT, then CV and standardized uptake values (SUV) at the 4 th vertebral body (L4) were compared after xQ and xB reconstruction in a clinical setup. Results: Mean activity concentrations with various TBR converged according to increasing numbers of iterations. The spatial resolution of xB was considerably superior to xQ and F3D, and it approached almost the actual size regardless of the iteration numbers during reconstruction. The CV and RC were better for xQ and xB than for F3D. The CNR peaked at 24 iterations for xQ and 48 iterations for F3D and xB, respectively. The RC between xQ and xB significantly differed at lower numbers of iterations but were almost equivalent at higher numbers of iterations. The reconstructed xQ and xB images of the clinical patients showed a significant difference in the SUV max and SUV peak .

Bone Scintigraphy of Vertebral Fractures With a Whole-Body CZT Camera in a PET-Like Utilization

“…Overall, our phantom results agree with the conclusions achieved by previous studies planned on conventional Anger cameras, regarding the acceptable accuracy of SPECT SUV measurements (18,19), especially for volumes ≥10 ml (20) and when associated with CT-based methods enabling reduction in the partial volume effect (21)(22)(23). It is notable, however, that underestimation of SUVmax is less marked when using an alternative reconstruction method available from the manufacturer and which favors spatial resolution to a greater extent (i.e., 64 OSEM equivalent iterations and a kernel inter-iteration filter with a factor of only 0.125) (see Supplementary Figure).…”

Satisfied quantitative value can be acquired by short-time bone SPECT/CT using a whole-body cadmium–zinc–telluride gamma camera

“…Quantitative evaluation is essential for objectively evaluating SPECT uptake values. Techniques for the standardization of these values have been developed using advances in hardware and software 9 , 10 . Among such techniques, the standardized uptake value (SUV), originally used in positron emission tomography (PET), can be an appropriate representative index even for SPECT.…”

“…It is also utilized for benign lesions, such as in the evaluation of the clinical stage of antiresorptive agent-related osteonecrosis of the jaw 13 , or in the evaluation of osteoblastic activity in the epiphyseal growth plates of children 14 . Although instability or vulnerability may be associated with SUVs for SPECT in comparison with those for PET, it has been found to be acceptable in most conditions after phantom-base analysis for quality assessment 9 , 15 , 16 , or in clinical-based assessments such as test–retest repeatability 17 . Therefore, images acquired in a shorter time might be acceptable for clinical use when the variance of the SUV is within a specified allowance.…”

Evaluation of quantitative accuracy among different scatter corrections for quantitative bone SPECT/CT imaging

“…The effects of photon scatter by bone and the accuracy of scatter correction for bone SPECT/CT images in clinical practice can be simulated and investigated using a bone equivalent solution. Miyaji et al [ 40 ] validated the accuracy of a new reconstruction method for bone SPECT/CT (xSPECT Bone; Siemens Healthineers), using a K 2 HPO 4 solution, and Yoshii et al [ 41 ] developed a new phantom containing a K 2 HPO 4 solution that allows consideration of scatter and photon attenuation due to bone in 18 F-NaF PET/CT images.…”