Abstract
P294
Introduction: To investigate the feasibility of a single 30-second deep-inspiration breath hold (DIBH) technique using a total-body PET scanner (uEXPLORER) and compare the DIBH, free-breathing-30s (FB-30s), and FB-5min PET/CT for the registration, subjective image quality assessment, and quantification of thoracic lesions.
Methods: A total of 145 patients were prospectively enrolled and underwent a routine FB-5min PET/low dose CT and the single 30-second attempted DIBH PET/ACCT. The FB-5min, FB-30s, and DIBH PET/CT were reconstructed. At the patient level, the mediastinal blood pool, upper and lower lung, liver, spleen, bone marrow standardized uptake value (SUV) were measured as background. The distances between the PET and CT of the liver domewere measured for registration quantification for FB-5min, FB-30s, and DIBH, respectively. At the lesion level, the number, size, location, maximal SUV (SUVmax), tumor-to-background ratio (TBR), MTV, and registration of thorax lesions were reported for each acquisition. The subgroup analysis of the relative lesion location regarding the upper and lower thorax was further performed. Statistical analysis was performed with the t-test, Mann-Whitney U-test, and chi-square test.
Results: A hundred and thirty (89.7%) patients successfully performed DIBH. The SUVmax and standard deviation (SD) of the liver, spleen, bone marrow, and mediastinal blood pool were not significantly different between the FB-30s and DIBH PET, and both were significantly larger than those in FB-5min. The SUVmax of the upper lung and lower lung in FB-5min were significantly lower than those in FB-30s (Lower Lung, SUVmax: 0.59 ± 0.19 vs. 0.66 ± 0.20; Upper Lung, SUVmax: 0.47 ± 0.15 vs. 0.54 ± 0.18), both were significantly higher than those in DIBH (Lower Lung, SUVmax: 0.44 ± 0.18; Upper Lung, SUVmax: 0.40 ± 0.15). The SD of the upper lung and lower lung were smallest in FB-5min and largest in FB-30s (FB-5min vs. FB-30s vs. DIBH; Lower Lung SD: 0.05 ± 0.03 vs. 0.08 ± 0.03 vs. 0.06 ± 0.05; Upper Lung SD: 0.04 ± 0.02 vs. 0.07 ± 0.03 vs. 0.05 ± 0.02). The SUVmax and SD of the upper lung were significantly lower than those of the upper lung in all acquisitions. At the lesion level, 54 patients with 94 lesions were identified in FB-5min, while 3 lesions (5.5%) were missed in FB-30s and one (1.9%) lesion was missed in DIBH. 53 patients with 90 lesions were detected in three acquisitions. Significantly higher SUVmax and lower MTV were shown in DIBH (SUVmax, median [Interquartile range, IQR]: 5.77 [3.70, 11.55]; MTV: 0.48 [0.27, 2.06]) than in FB-5min and FB-30s, but no significant difference in FB-5min and FB-30s (SUVmax: 4.96 [2.64, 9.86] vs. 4.53 [2.56, 9.67]; MTV: 0.79 [0.38, 2.44] vs. 0.85 [0.40, 2.35]). The TBRs were highest in DIBH and lowest in FB-30s (FB-5min vs. FB-30s vs. DIBH: 10.17 [5.30, 18.32] vs. 8.13 [4.34, 17.89] vs. 10.86 [7.75, 27.07]). The subgroup analysis showed the degrees of SUVmax increase and MTV decrease between DIBH and FB-5min were significantly higher for lesions in the lower thorax than in the upper thorax. No significant difference was found in PET/CT registration between FB and DIBH acquisitions.
Conclusions: The DIBH PET/CT technique is feasible in routine clinical practice and is more sensitive for quantitative measurements. This technique reduces the background lung uptake and the blurring effect of respiratory motion, thus improving the diagnostic confidence for thorax lesions.
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