Respiratory-gated PET imaging with reduced scanning time superior to ungated imaging for suspect malignancies
China: Respiratory-gating imaging with reduced acquisition time using the total-body PET (positron emission tomography)/CT (computed tomography) scanner is superior to ungated imaging and can be utilized in the clinic, says research published in European Radiology.
Respiratory gating in PET imaging can improve lesion presentation and detectability but requires a longer imaging time. Guobing Liu from the Shanghai Institute of Medical Imaging, Shanghai, China, and colleagues conducted the single-centre study to look into the performance of respiratory-gating imaging with reduced acquisition time using PET/CT scanner.
For this purpose, the authors analyzed data of 71 patients with suspect malignancies who underwent total-body 2-[18F]-fluoro-2-deoxy-D-glucose PET/CT for 15 min with respiration recorded studied. Four reconstructions were performed for each examination: Ungated-5, using data from the first 5 min; Ungated-15, using all coincidences; Gated-6 using data of the first 6 min with respiratory gating; and Gated-15, using all coincidences but with respiratory gating. Image quality was evaluated, lesions were quantified, and a comparison was drawn between both in four image sets.
The study led to the following findings:
- The authors found 390 lesions in the thorax and upper abdomen.
- Lesion detectability was remarkably higher in gated-15 (97.2%) than in ungated-15 (93.6%) and ungated-5 (92.3%) but comparable to Gated-6 (95.9%). For quantitative analyses, a total of 131 lesions were selected.
- Lesions in Gated-15 presented notably larger standardized uptake values, tumour-to-liver ratio, and tumour-to-blood ratio but smaller metabolic tumor volume than those in Ungated-15 and Ungated-5. These differences were more evident in small lesions and lesions from sites other than mediastinum/retroperitoneum. These indices were, however, comparable between Gated-6 and Gated-15.
- In gated images, higher but acceptable image noise was identified than in ungated images.
"Our findings revealed that the total-body PET scanner allows respiratory-gated imaging with clinically acceptable and reduced scanning time," the authors concluded.
Reference:
Liu, G., Chen, S., Hu, Y. et al. Respiratory-gated PET imaging with reduced acquisition time for suspect malignancies: the first experience in application of total-body PET/CT. Eur Radiol (2022). https://doi.org/10.1007/s00330-022-09369-z
