Evaluating Two Respiratory Correction Methods for Abdominal PET/MRI Imaging

Abstract

Background: To evaluate two respiratory correction methods for abdominal PET/MRI images, further to analyse the effects on standard uptake values (SUVs) of respiratory motion correction. 17 patients with 25 abdominal lesions on 18F-FDG PET/CT were scanned with PET/MRI. PET images were reconstructed using end-expiratory respiratory gating and multi-bin respiratory gating. Meanwhile, full data and the first 3 minutes and 20 seconds of data acquired both without respiratory gating were reconstructed for evaluation. Five parameters, including the SUVmax and SUVmean in the lesions, the SUVmean and standard deviation (SD) in the background, and the signal-to-noise ratio (SNR) were calculated, and used for statistical comparisons. The differences in multi-bin respiratory gating and reconstruction of full data, relative to the reconstruction of the first 3 minutes and 20 seconds of data acquired, were calculated. Results: Compared with PET/CT, the longer scanning time of abdominal PET/MRI makes respiratory motion correction necessary. The multi-bin respiratory gating correction could reduce the PET image blur and increase the SUVmax (11.98%) and SUVmean (13.12%) of the lesions significantly (p = 0.00), which was much more effective than end-expiratory respiratory gating for abdominal PET/MRI. There was no significant difference in the increase in SUVmax between multi-bin respiratory gating correction and associated count loss with the correction (p=0.39), which was rarely reported by previous studies.Conclusion: The multi-bin respiratory gating is proposed as the default reconstruction method for abdominal PET/MRI. However, the respiratory gating correction with the PET counts loss would induce the falsely improvement for SUVmax of lesions.

Q.Clear Reconstruction for Reducing the Scanning Time for 68Gallium-DOTA-FAPI-04 PET/MR Imaging

“…For OSEM reconstruction, we adopted 28 subsets and 2 iterations. Respiratory bellows were fastened to the abdomen for respiratory monitoring, which was bene cial for abdominal and thoracic PET [21]. PET attenuation correction was implemented via MRAC, combining tissue segmentation and template matching methods [22].…”

“…Before comparisons, we applied a Levene's statistical test to the data distribution and variance. If the data distribution was normal and the variance was homogeneous, we performed a three-group comparison using a matched-pair randomized block design [21]. If either condition failed, we applied a Friedman nonparametric test [24].…”