Purpose [68Ga]Ga-PSMA-11 undergoes renal excretion, frequently leading to high levels of tracer activity in the bladder, which can mask nearby lesions. This study evaluated the feasibility of dynamic whole-body [68Ga]Ga-PSMA-11 PET/CT Patlak parametric imaging to reduce bladder signal interference, thereby improving visualization. Methods Eleven suspected prostate cancer patients underwent 60-minute dynamic PET/CT. SUV, Ki (Patlak slope), and V (Patlak intercept) parametric images were generated. Bladder-induced prostatic base obscuration was assessed via visual scoring (3-grade system). Signal-to-noise ratio (SNR) compared signal distributions in normal organs, lesions (primary, lymph node/bone metastases), and bladder. Correlations between Kimax, Vmax, and SUVmax were analyzed. Results V images significantly reduced bladder SNR (SNRV: 0.09 [0–0.89] vs. SNRSUV: 10.06 [7.95–12.14], p < 0.001) and signal volume (SVV: 10.93 ± 11.12 cm3 vs. SVSUV: 155.46 ± 95.18 cm3, p < 0.001), achieving a 93% volume reduction. Prostatic base obscuration occurred in 27% (3/11) of SUV images (score = 2), but was absent in V images (score ≤ 1); complete bladder signal void (score = 0) was observed in 18% (2/11) of V images. Both V and Ki images detected all primary prostate lesions (13/13), while metastasis detection rates were 91% (20/22) on V images and 95% (21/22) on Ki images. Lymph node metastases exhibited higher SNRV vs. SNRSUV (5.91 [3.94–8.91] vs. 5.42 [4.03–10.77], p = 0.031) and significantly higher Ki values compared to SUV (9.00 [4.53–14.53] vs. 5.42 [4.03–10.77], p = 0.002), indicating superior visualization on parametric images. Primary prostate SNRV was lower than SNRSUV (8.87 [6.88–17.33] vs. 13.45 [8.24–21.93], p = 0.028) but remained significantly higher than gluteal muscle values. Strong correlations existed between Kimax, Vmax, and SUVmax (rs = 0.758–0.924, p < 0.05). Conclusion Patlak V imaging significantly reduces bladder signal intensity and obscuration of adjacent areas in [68Ga]Ga-PSMA-11 PET/CT while maintaining lesion visibility. Concurrently, Patlak Ki imaging enhances visualization of malignant lesions, particularly lymph node metastases. Whole-body dynamic PET/CT Patlak analysis represents a promising approach for improving prostate cancer visualization.

Feasibility of dynamic whole-body [⁶⁸Ga]Ga-PSMA-11 PET/CT Patlak parametric imaging for reducing bladder signal interference and improving lesion visualization

期刊论文
发表日期：

2026年3月4日

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Mu Kong,
Zhiyong Quan,
Guiyu Li,
Jingyi Wang,
Min Wang,
Xiaoli Meng,
Tingting Han,
Yirong Wang,
Fei Kang,
Jing Wang

摘要

Purpose

[⁶⁸Ga]Ga-PSMA-11 undergoes renal excretion, frequently leading to high levels of tracer activity in the bladder, which can mask nearby lesions. This study evaluated the feasibility of dynamic whole-body [⁶⁸Ga]Ga-PSMA-11 PET/CT Patlak parametric imaging to reduce bladder signal interference, thereby improving visualization.

Methods

Eleven suspected prostate cancer patients underwent 60-minute dynamic PET/CT. SUV, Ki (Patlak slope), and V (Patlak intercept) parametric images were generated. Bladder-induced prostatic base obscuration was assessed via visual scoring (3-grade system). Signal-to-noise ratio (SNR) compared signal distributions in normal organs, lesions (primary, lymph node/bone metastases), and bladder. Correlations between Ki_max, V_max, and SUV_max were analyzed.

Results

V images significantly reduced bladder SNR (SNR_V: 0.09 [0–0.89] vs. SNR_SUV: 10.06 [7.95–12.14], p < 0.001) and signal volume (SV_V: 10.93 ± 11.12 cm³ vs. SV_SUV: 155.46 ± 95.18 cm³, p < 0.001), achieving a 93% volume reduction. Prostatic base obscuration occurred in 27% (3/11) of SUV images (score = 2), but was absent in V images (score ≤ 1); complete bladder signal void (score = 0) was observed in 18% (2/11) of V images. Both V and Ki images detected all primary prostate lesions (13/13), while metastasis detection rates were 91% (20/22) on V images and 95% (21/22) on Ki images. Lymph node metastases exhibited higher SNR_V vs. SNR_SUV (5.91 [3.94–8.91] vs. 5.42 [4.03–10.77], p = 0.031) and significantly higher Ki values compared to SUV (9.00 [4.53–14.53] vs. 5.42 [4.03–10.77], p = 0.002), indicating superior visualization on parametric images. Primary prostate SNR_V was lower than SNR_SUV (8.87 [6.88–17.33] vs. 13.45 [8.24–21.93], p = 0.028) but remained significantly higher than gluteal muscle values. Strong correlations existed between Ki_max, V_max, and SUV_max (r_s = 0.758–0.924, p < 0.05).

Conclusion

Patlak V imaging significantly reduces bladder signal intensity and obscuration of adjacent areas in [⁶⁸Ga]Ga-PSMA-11 PET/CT while maintaining lesion visibility. Concurrently, Patlak Ki imaging enhances visualization of malignant lesions, particularly lymph node metastases. Whole-body dynamic PET/CT Patlak analysis represents a promising approach for improving prostate cancer visualization.