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 bone SPECT/CT 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 in different activity concentrations and sphere sizes. A phantom with 28-mm spheres containing a 99mTc background and having tumor-to-normal bone ratios (TBR) of 1, 2, 4 and 10, were generated and its convergence property was evaluated across 96 iterations. A phantom with four spheres (13-, 17-, 22-, and 28-mm diameters), containing a 99mTc-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) of an imaged spine were evaluated with F3D, xQ and xB.Images from 20 patients with suspected bone metastases (male, n = 13) were acquired using 99mTc-(H)MDP SPECT/CT, then the CV and standardized uptake value (SUV) at the 4th vertebral body (L4) were compared with xQ and xB in a clinical setup. Results Mean activity concentrations with various TBR converged accordance to increasing numbers of iterations. Spatial resolution was improved in the order of xB, xQ and F3D regardless of the number of iterations 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 significantly differed between xQ and xB at lower numbers of iterations, whereas those of xQ and xB became almost equivalent at higher numbers of iterations. Significant differences in the clinical patients’ SUVmax and SUVpeak were observed in the reconstructed xQ and xB images. Conclusions The reconstructed xQ and xB images were more accurate than those conventionally reconstructed using F3D. Bone SPECT xB imaging offered essentially unchanged spatial resolution even when the numbers of iterations did not converge. The xB further enhanced SPECT image quality using CT data. Our findings provide important evidence for understanding the performance characteristics of the novel xQ and xB algorithms.

Purpose: The purpose of this study was to evaluate the detectability of the observers and motion detection software for blurred portable chest radiographies. Methods: The chest phantom radiographies of various blur sizes were obtained by moving the phantom using 4° slope. The phantom was moved in two directions, vertical (the upper and lower parts of the chest phantom were parallel to rails) and horizontal (the left and right parts of the chest phantom were parallel to rails). Six observers performed receiver operating characteristic (ROC) studies on blurred images. We used the results to compare detectability for vertical and horizontal blur by ROC analysis, and calculated sensitivity and specificity. In addition, the motion detection software was enabled during image acquisition, and the detectability was compared with that of the observers. Results: The average of the area under the ROC curve for the detection of blur in the vertical and horizontal directions for the observers were 0.918 and 0.943, respectively, and no significant difference was found depending on the direction. The motion detection software performed better than the observers in most of the sensitivity and specificity scores. Conclusion: The motion detection software could be a useful support tool for motion detection in portable chest radiography.

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) 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 SUVmax and SUVpeak. Conclusions The reconstructed xQ and xB images were more accurate than those reconstructed conventionally using F3D. The xB for bone SPECT imaging offered essentially unchanged spatial resolution even when the numbers of iterations did not converge. The xB reconstruction further enhanced SPECT image quality using CT data. Our findings provide important information for understanding the performance characteristics of the novel xQ and xB algorithms.

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Objectives To investigate whether the center-of-mass shift distance (CMSD) analysis on whole-body dynamic positron emission tomography (WBD-PET) with continuous bed motion was an objective index for discriminating pathological and physiological colorectal uptake in the lower abdominal region. Methods We retrospectively analyzed the CMSD in 39 patients who underwent delayed imaging to detect focal uptake that were difficult to determine as pathological and physiological on an conventional early PET (early) image reconstructed by five-phase WBD-PET images. The CMSD between each phase of WBD-PET images and between early to delayed (early–delayed) images were classified into pathological and physiological uptake groups based on endoscopic histology or other imaging diagnostics. The diagnostic performance of CMSD analysis on WBD-PET images was evaluated by receiver operator characteristic (ROC) analysis and compared to that of early–delayed images. Results A total of 66 focal uptake detected early image were classified into 17 and 49 pathological and physiological uptake groups, respectively. The CMSD on WBD-PET and early–delayed images in the pathological uptake group was significantly lower than that in the physiological uptake group (p < 0.01), respectively. The sensitivity, specificity, and accuracy in CMSD analysis on WBD-PET images at the optimal cutoff of 5.2 mm estimated by the Youden index were 94.7%, 89.4%, and 89.4%, respectively, which were not significantly different (p = 0.74) from those of early–delayed images. Conclusions The CMSD analysis on WBD-PET was useful in discriminating pathological and physiologicalcolorectal uptake in the lower abdominal region, and its diagnostic performance is comparable to that of early–delayed images. We suggested that CMSD analysis on WBD-PET images would be a new objective method to omit unnecessary additional delay imaging.