Article Figures & Data
Figures
- FIGURE 1.
Flowchart of included patients. Total of 222 of 300 patients in our institutional databases met inclusion criteria for analysis. We excluded 78 patients (incomplete availability of imaging data [n = 67], staging images provided as PSMA PET/MRI [n = 10], or staging images provided as choline PET/CT [n = 1]).
- FIGURE 2.
Examples of early (A–D) and late (E–H) [99mTc]Tc-PSMA-I&S SPECT/CT imaging. (A–D) In 74-y-old patient who had RP in 2004 and BCR in 2016 (PSA, 0.66 ng/mL), PSMA PET (A and B) shows local recurrence in right prostate fossa with intense PSMA expression (SUVmax, 12.7 [asterisk]); 4 h after [99mTc]Tc-PSMA I&S injection, SPECT/CT (C and D) morphologically identifies known local recurrent cancer (asterisk) but uptake is not above background, with overall score of 2. (E–H) In 66-y-old patient who had RP in 2012 and BCR in 2018 (PSA, 0.59 ng/mL), PSMA PET (E and F) shows right internal iliac lymph node metastasis with intense PSMA expression (SUVmax, 5.0 [arrow]); 18 h after [99mTc]Tc-PSMA-I&S injection, SPECT/CT (G and H) confirms metastasis with significant uptake above background (score 4, arrow).
- FIGURE 3.
Overall and size-dependent lesion-based detectability by early (≤4 h) vs. late (≥15 h) [99mTc]Tc-PSMA-I&S SPECT/CT imaging.
Tables
- TABLE 1.
Characteristics of 222 Patients Treated with RGS Between 2014 and 2020 at 2 Centers*
Parameter Early SPECT (≤4 h after injection; n = 44) Late SPECT (≥15 h after injection; n = 178) P Year of initial RP 2010 (2005–2013) 2014 (2010–2016) <0.001 PSA at RP (ng/mL) 10 (6–16) 9 (6–15) 0.8 Lymph node yield at RP 13 (8–20) 13 (8–20) 0.6 Positive lymph nodes at RP 0.6 0 32 (73) 115 (65) 1 3 (6.8) 19 (11) 2 3 (6.8) 9 (5.1) ≥3 2 (4.5) 5 (2.8) Unknown 4 (9.1) 30 (17) Surgical margin status 0.05 R0 29 (66) 130 (73) R1 9 (20) 41 (23) RX/NA 6 (14) 7 (3.9) RT after RP 0.1 No RT 15 (34) 59 (33) RT after RP 28 (64) 119 (67) NA 1 (2.3) 0 (0) Time from RP to SPECT (mo) 70 (22–128) 46 (22–88) 0.2 Age at PSMA RGS (y) 72 (65–75) 66 (61–70) <0.001 PSA before SPECT (ng/mL) 1.4 (0.7–3.0) 1.0 (0.5–2.0) 0.09 * Patients received [99mTc]Tc-PSMA-I&S SPECT/CT before surgery and presented with BCR after RP with histopathology-confirmed positive lesions at PSMA PET/CT.
NA = not assigned; RT = radiotherapy.
Qualitative data are number and percentage; continuous data are median and IQR.
- TABLE 2.
PSMA PET/CT and SPECT/CT Imaging Characteristics of 222 Patients with BCR After RP Treated with RGS Between 2014 and 2020 at 2 Centers Within Early and Late [99mTc]Tc-PSMA-I&S SPECT/CT Groups
Parameter Early SPECT (≤4 h after injection; n = 44) Late SPECT (≥15 h after injection; n = 178) P Lesions on PSMA PET 0.7 1 30 (68%) 94 (53%) 2 11 (25%) 53 (30%) 3 2 (4.5%) 16 (9.0%) 4 1 (2.3%) 7 (3.9%) ≥5 0 (0%) 8 (4.5%) Maximum lesion size on PET/CT (mm) 8 (7–12) 9 (6–12) 0.7 Maximum lesion SUV on PET 9 (6–17) 8 (5–16) 0.1 Ratio of maximum lesion SUV to background on PET 12 (7–22) 8 (5–16) 0.02 miTNM-Tr 0 (0%) 28 (16%) 0.01 miTNM-N1 34 (77%) 112 (63%) 0.1 miTNM-N2 10 (23%) 53 (30%) 0.5 miTNM-M1a 0 (0%) 15 (8.4%) 0.1 [99mTc]Tc-PSMA-I&S activity (MBq) 550 (416–702) 752 (695–786) <0.001 Corrected [99mTc]Tc-PSMA-I&S activity at time of SPECT (MBq) 488 (370–632) 99 (91–108) <0.001 Interval between [99mTc]-Tc-PSMA-I&S tracer injection and SPECT imaging (h) 1.0 (1.0–2.0) 18.0 (17.0–18.0) <0.001 Lesions on SPECT <0.001 0 33 (75%) 45 (25%) 1 9 (20%) 90 (51%) 2 1 (2%) 27 (15%) 3 1 (2%) 13 (7%) 4 0 (0%) 2 (1%) ≥5 0 (0%) 1 (1%) Maximum lesion size on SPECT/CT (mm) 11.5 (7.8–17.1) 9.0 (7.0–13.0) 0.07 Qualitative data are number and percentage; continuous data are median and IQR.
- TABLE 3.
Uni- and Multivariable Logistic Regression Models Regarding Visibility of Lesions in [99mTc]Tc-PSMA-I&S SPECT/CT Imaging
Univariable Multivariable Variable OR CI, 2.5% CI, 97.5% P OR CI, 2.5% CI, 97.5% P Gleason grade group at RP I–II Ref. III–V 0.34 0.74 2.42 0.3 pT stage at RP pT2 Ref. pT3a/b 0.65 0.34 1.21 0.2 pN stage at RP pN0/X Ref. pN1 0.53 0.27 1.05 0.07 Margin status at RP R0 Ref. R1 1.0 0.51 2.06 0.9 RT after RP No Ref. Yes 0.82 0.43 1.49 0.5 Time from RP to SPECT (continuous) 0.99 0.99 1.0 0.8 Age at SPECT (continuous) 0.99 0.95 1.03 0.6 PSA at SPECT (continuous) 1.21 1.03 1.47 0.03 1.25 0.99 1.66 0.09 Lesions on PET (continuous) 2.03 1.38 3.21 0.001 1.57 1.02 2.67 0.07 Maximum lesion size on PET (continuous) 1.13 1.05 1.22 0.002 1.06 0.97 1.17 0.2 Maximum lesion SUV on PET (continuous) 1.10 1.05 1.16 <0.001 1.15 1.07 1.27 <0.001 Activity of injected [99mTc]Tc-PSMA-I&S (continuous) 1.00 1.00 1.00 <0.001 0.99 0.99 1.0 0.6 Interval between injection and SPECT (continuous) 1.16 1.11 1.22 <0.001 1.27 1.17 1.40 <0.001 OR = odds ratio; RT = radiotherapy.
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