[Value of time-shortened 18F-fluorodeoxyglucose total-body dynamic PET-CT scanning in the diagnosis of Takayasu arteritis].

Abstract

Objective: To investigate the value of short-term ¹⁸F-fluorodeoxyglucose (FDG) total-body (TB) dynamic PET(dPET)-CT scanning in the diagnosis of Takayasu arteritis (TA). Methods: A retrospective analysis was performed on 8 TA patients underwent dPET-CT scanning in the First Affiliated Hospital of Shandong First Medical University from March to October 2022, who met the diagnostic criteria for TA proposed by the American College of Rheumatology in 1990. Patients were divided into active inflammation and inactive inflammation groups according to National Institutes of Health (NIH) criteria. All patients underwent 1 h TB dPET scan and 2 h delayed scan, and 1 h static PET was reconstructed by dPET scan for 50-60 min, and nineteen regions of interest in the arterial wall were delineated for each patient. One hour dPET scan images were reconstructed into 10, 20, 30, 40 and 60 min K_i parameter images and compared with 1 h static and 2 h delayed PET images. The clinical data of patients in the active inflammation group and the inactive inflammation group were compared. The image quality of dPET and static PET at different scanning times [including lesion target ratio (TBR), lesion contrast-to-noise ratio (CNR)] and the detection rate of active lesions were compared. Results: A total of 152 branch vessels of 8 patients were included, including 3 males and 5 females, aged 21 to 40 years old. A total of 68 (89.5%) diseased blood vessels were detected in 4 patients in the active inflammation group, and a total of 50 (65.8%) diseased blood vessels were detected in 4 patients in the inactive inflammation group (P=0.001). The TBRs of dPET at 10, 20, 30, 40 and 60 min were 1.870 (1.301, 2.815), 2.991 (1.926, 4.265), 3.310 (2.308, 4.786), and 3.315 (2.333, 4.361), 2.986 (2.177, 4.344)), respectively. The CNRs were -0.799 (-1.356, 0.300), 0.691 (-0.212, 1.900), 1.563 (0.550, 2.778), 2.236 (1.012, 3.271), and 2.344 (1.324, 4.134), respectively. Both TBR and CNR gradually increased (both P_trend<0.001). Pairwise comparisons revealed that the dPET TBR at 30, 40, and 60 minutes and the dPET CNR at 40 and 60 minutes were all higher than those of the 1-hour static and 2-hour delayed PET, respectively (all P<0.001). The differences in the detection rates of diseased blood vessels between the active inflammation group and the inactive inflammation group at different scanning times of dPET, 1-hour static PET, and 2-hour delayed PET were all statistically significant (all P<0.05). Pairwise comparisons revealed that the detection rates of diseased blood vessels in the 30-and 40-minute dPET scans between the two groups of patients were 60.5% (46 lesions), 31.6% (24 lesions), 81.6% (62 lesions), and 44.7% (34 lesions), respectively. All were higher than 42.1% (32 pieces) and 9.2% (7 pieces) of 1-hour static PET (all P<0.05); the detection rates of diseased blood vessels in 40-minute dPET scans were both higher than 50.0% (38 lesions) and 30.3% (23 lesions) in 2-hour delayed PET scans (both P<0.001). Conclusions: It is feasible to shorten the time of dPET scanning for the assessment of arterial activity in TA patients, and parametric images with higher image quality and diseased blood vessels detection rate can be obtained by dPET scanning for 30 min.