Phantom and clinical assessment of small pulmonary nodules using Q.Clear reconstruction on a silicon-photomultiplier-based time-of-flight PET/CT system

Abstract

To evaluate the quantification accuracy of different positron emission tomography-computed tomography (PET/CT) reconstruction algorithms, we measured the recovery coefficient (RC) and contrast recovery (CR) in phantom studies. The results played a guiding role in the partial-volume-effect correction (PVC) for following clinical evaluations. The PET images were reconstructed with four different methods: ordered subsets expectation maximization (OSEM), OSEM with time-of-flight (TOF), OSEM with TOF and point spread function (PSF), and Bayesian penalized likelihood (BPL, known as Q.Clear in the PET/CT of GE Healthcare). In clinical studies, SUVmax and SUVmean (the maximum and mean of the standardized uptake values, SUVs) of 75 small pulmonary nodules (sub-centimeter group: < 10 mm and medium-size group: 10–25 mm) were measured from 26 patients. Results show that Q.Clear produced higher RC and CR values, which can improve quantification accuracy compared with other methods (P < 0.05), except for the RC of 37 mm sphere (P > 0.05). The SUVs of sub-centimeter fludeoxyglucose (FDG)-avid pulmonary nodules with Q.Clear illustrated highly significant differences from those reconstructed with other algorithms (P < 0.001). After performing the PVC, highly significant differences (P < 0.001) still existed in the SUVmean measured by Q.Clear comparing with those measured by the other algorithms. Our results suggest that the Q.Clear reconstruction algorithm improved the quantification accuracy towards the true uptake, which potentially promotes the diagnostic confidence and treatment response evaluations with PET/CT imaging, especially for the sub-centimeter pulmonary nodules. For small lesions, PVC is essential.

Impact of Bayesian penalized likelihood reconstruction on quantitative and qualitative aspects for pulmonary nodule detection in digital 2-[18F]FDG-PET/CT

“…Interestingly, we were still able to measure differences, although both OSEM and BSREM used point spread function modeling. Moreover, as described in previous phantom studies, BSREM improved the quantification accuracy especially for smaller (i.e., sub-centimeter) nodules 23 .…”

Enhancing the spatial resolution of hyperpolarized carbon‐13 MRI of human brain metabolism using structure guidance

“…We highlight the influence of the segmentation by applying the low-resolution (LR) segmentation (seg) to the high-resolution (HR) reconstruction the field of metabolic imaging, new methods improving resolution on PET are now used routinely on many scanners. 33,34 This paper demonstrates the potential of using 3D super-resolution techniques to enhance low resolution metabolic imaging with in silico, in vitro, and in vivo datasets.…”

“…Accurate measurements of lesion size are important for assessing treatment response and super‐resolution approaches could be used to assess the effects of chemotherapy or radiotherapy. In the field of metabolic imaging, new methods for improving resolution on PET are now used routinely on many scanners 33,34 . This paper demonstrates the potential of using 3D super‐resolution techniques to enhance low resolution metabolic imaging with in silico, in vitro, and in vivo datasets.…”

Small lesion depiction and quantification accuracy of oncological 18F-FDG PET/CT with small voxel and Bayesian penalized likelihood reconstruction

“…The BPL reconstruction can improve the lesion detectability and the quantification accuracy for small pulmonary nodules [ 11 – 13 , 23 ], metastases [ 24 – 26 ], and other tumors [ 27 ]. The improvement in the small lesion detection depended on the penalization factor, tumor size, contrast, and CNR [ 14 , 15 ].…”

“…To address these issues, Teoh EJ et al [ 11 ] suggested a higher SUV threshold in the interpretation. In another study, Wu Z et al [ 23 ] proposed a formula to calibrate SUV based on lesion size. Our results of the phantom and the patient study showed increasing the penalty to SVB1.0 could make the CR and lesion SUV comparable to that of the RVOSEM reconstruction group, which could be an alternative solution to address the concern on the elevated SUV.…”