Page 114 - Quantitative Imaging of Small Tumours with Positron Emission Tomography

[18F]DCFPyL PET repeatability Table 5.1: Patient and scan characteristics of the patients included in the repeatability analysis (n=10). Patient Characteristics Age (years) Initial Gleason score PSA at PET/CT (ng/mL) Length (cm) Weight (kg) PCa stage: Primary metastastic Biochemically recurrent Castration-resistant Analyzed lesion type: Bone Lymph node Intraprostatic Androgen Deprivation at PET/CT prior docetaxel Injected activity: Test (MBq) Injected activity: Retest (MBq) Uptake time: Test (min) Uptake time: Retest (min) Test-Retest diff. injected activity (MBq)b Test-Retest diff. uptake time (min)b Median Range 74 (61-79) 8 (6-9) 9 (1-2796) 178 (168-192) 88 (68-94) n % 2 20.0 3 30.0 5 50.0 n % 21 58.3 12 33.3 5 3a 8.3 n% 7 70.0 3 30.0 317 (280-331) 313 (254-341) 120 (118-153) 122 (111-149) 28 (8-63) 3 (0-22) atwo intraprostatic foci in one patient; b differences were not significant (p>0.05). Repeatability of Lesion-Level Metrics In total, 36 [18F]DCFPyL PET-avid lesions were analysed, including 21 bone lesions (58.3%), 12 lymph node metastases (33.3%), and 3 intraprostatic foci (8.3%). Descriptive values of the analysed PET parameters are shown in Table 5.2 (PSF-reconstruction data in Supplemental Table 1). The best repeatability was observed for SUVmean (RC 24.4%) and SUVpeak (RC 25.3%). SUVmax had poorer repeatability (RC 31.0%; Table 5.3), but the differences between repeatability of SUVs were not significant (p=0.06-0.60). Blood activity derived from a 1-slice and 5-slice VOI had a repeatability of 23.1% and 17.3%, respectively. Consequently, calculating TBR using 5-slice blood measurements had better repeatability compared to single-slice measurements (RC 31.7-37.3% versus 34.1-40.1%) and 113