Optimization of a Bayesian penalized likelihood algorithm (Q.Clear) for 18F-NaF bone PET/CT images acquired over shorter durations using a custom-designed phantom

Abstract

Background The Bayesian penalized likelihood (BPL) algorithm Q.Clear (GE Healthcare) allows fully convergent iterative reconstruction that results in better image quality and quantitative accuracy, while limiting image noise. The present study aimed to optimize BPL reconstruction parameters for 18F-NaF PET/CT images and to determine the feasibility of 18F-NaF PET/CT image acquisition over shorter durations in clinical practice. Methods A custom-designed thoracic spine phantom consisting of several inserts, soft tissue, normal spine, and metastatic bone tumor, was scanned using a Discovery MI PET/CT scanner (GE Healthcare). The phantom allows optional adjustment of activity distribution, tumor size, and attenuation. We reconstructed PET images using OSEM + PSF + TOF (2 iterations, 17 subsets, and a 4-mm Gaussian filter), BPL + TOF (β = 200 to 700), and scan durations of 30–120 s. Signal-to-noise ratios (SNR), contrast, and coefficients of variance (CV) as image quality indicators were calculated, whereas the quantitative measures were recovery coefficients (RC) and RC linearity over a range of activity. We retrospectively analyzed images from five persons without bone metastases (male, n = 1; female, n = 4), then standardized uptake values (SUV), CV, and SNR at the 4th, 5th, and 6th thoracic vertebra were calculated in BPL + TOF (β = 400) images. Results The optimal reconstruction parameter of the BPL was β = 400 when images were acquired at 120 s/bed. At 90 s/bed, the BPL with a β value of 400 yielded 24% and 18% higher SNR and contrast, respectively, than OSEM (2 iterations; 120 s acquisitions). The BPL was superior to OSEM in terms of RC and the RC linearity over a range of activity, regardless of scan duration. The SUVmax were lower in BPL, than in OSEM. The CV and vertebral SNR in BPL were superior to those in OSEM. Conclusions The optimal reconstruction parameters of 18F-NaF PET/CT images acquired over different durations were determined. The BPL can reduce PET acquisition to 90 s/bed in 18F-NaF PET/CT imaging. Our results suggest that BPL (β = 400) on SiPM-based TOF PET/CT scanner maintained high image quality and quantitative accuracy even for shorter acquisition durations.

The effect of Q.Clear reconstruction on quantification and spatial resolution of 18F-FDG PET in simultaneous PET/MR

“…Our clinical data analysis also indicated significantly improved SNR, SBR, noise level and visual assessment scores in Q.Clear ( β = 400) than in OSEM + TOF, which was in line with previously published studies [ 11 – 14 ]. Compared to OSEM + TOF, Q.Clear can achieve a complete convergence and more accurate lesion quantitation, which will improve the SUVmax, SNR, SBR values of PET/MR in patients with suspected primary and metastatic torso cancers.…”

“…Our findings were similar to previous studies on PET/MR using 68 Ga-prostate-specific membrane antigen (400–550) [ 1 ]. Previous studies on PET/CT suggested similar optimal β value of 350–400 ( 18 F-FDG) [ 12 , 15 , 16 ], 300–550 ( 18 F-fluciclovine) [ 17 ] and 300 ( 18 F-NaF) [ 14 ], 350 ( 68 Ga-labeled radiopharmaceuticals) [ 11 ], 400–550 ( 18 F-fluorocholine) [ 18 ]. While a few other studies of PET/CT suggested a higher β value of 500–750 [ 19 – 24 ], a study on the detection of sub-centimeter lesions suggested a β value of 200 [ 25 ].…”

The Impact of Total Variation Regularized Expectation Maximization Reconstruction on 68Ga-DOTA-TATE PET/CT Images in Patients With Neuroendocrine Tumor

“…The capability of BPL algorithm of shortening acquisition time was reported in several studies (16,17). A phantom and clinical study by Yang et al showed that TVREM could improve the lesion contrast and lower image noise of 68 Ga-PSMA-11 PET/CT compared to OSEM and enable a fast acquisition with 2 min/bed with preserved image quality (10).…”

New PET technologies – embracing progress and pushing the limits

“…Using BPL reconstruction in clinical studies enables improved lesion detection, and this has been shown in a wide variety of studies, for example, for 18 F-FDG in lung nodules [17,19], mediastinal nodes [20] and liver metastases [21]. PET imaging with other tracers also benefits from BPL reconstruction [17], for example, 68 Ga-PSMA [22,23], 68 Ga-DOTATOC [24], 68 Ga-RM2 [25], 90 Y-SIRT [26,27], 18 F-PSMA [28], 18 F-NaF [29], 68 Ga-citrate [30], 18 F-FACBC [31], 13 N-NH3 [32], 11 C-acetate [24] and 89 Zr-immuno-PET [33]. In addition, and perhaps most importantly, BPL is particularly advantageous in patients with high BMI [34,35], because they usually have the greatest background image noise where both the detection and quantification of small abnormalities are most problematic.…”