⁶⁸Ga-labeled prostate-specific membrane antigen (⁶⁸Ga-PSMA) PET/CT has a proven role in staging and restaging of prostate cancer (PCA). The aims of this study were to evaluate the association of intraprostatic ⁶⁸Ga-PSMA PET/CT findings and PSMA expression in immunohistochemical staining and generate a cutoff value for differentiation between normal prostate (PN) and PCA. Methods: The data of 31 patients (mean age, 67.2 y) who underwent prostatectomy and preoperative PET were retrospectively analyzed. On PET, focally increased uptake in the prostate was suggestive of tumor. A region of interest was placed on the suggestive area to generate an SUV_max; a similar region of interest was placed on adjacent visually PN. Both PCA and PN were stained with monoclonal anti-PSMA antibody (clone 3E6, 1:100, M3620). Results: All intraprostatic PCA lesions on PET could be confirmed histopathologically. In PN sections (n = 31), median staining intensity was mild, median percentage of stained cells was 20% ± 14.24%, and median immunoreactive score (IRS) was 1. In PCA sections (n = 31), median IRS was 3, median staining intensity was strong, and median percentage of stained cells was 80% ± 16.46%. The mean SUV_max (±SD) of PCA (14.06 ± 15.56) was significantly higher than that of PN (2.43 ± 0.63; P < 0.001). Receiver-operating-characteristic curve analyses of the SUV_max of PCA, validated by immunohistochemical staining in 62 tissue samples, showed the best cutoff to be 3.15 (sensitivity, 97%; specificity, 90%; area under curve, 0.987). Applied to multifocal PCA, it resulted in sensitivity and specificity of 87% and 97% respectively. The mean SUV_max of PCA and PN for an IRS of less than 2 (n = 26; 2.52 ± 0.64) was significantly lower than the mean SUV_max for an IRS of 2 or more (n = 36; 12.38 ± 15.02; P < 0.001). The mean SUV_max was significantly lower in PCA samples with fewer than 50% stained cells (n = 30; 2.81 ± 2.35) than in samples with 50% or more (n = 32; 13.34 ± 15.55; P < 0.001). There was no correlation between the SUV_max of PCA and Gleason score (P = 0.54). Conclusion: This study showed that SUV_max on ⁶⁸Ga-PSMA PET/CT correlates significantly with PSMA expression in primary PCA, enabling the detection of PCA with a high sensitivity and specificity.

⁶⁸ Ga标记的前列腺特异性膜抗原（⁶⁸ Ga-PSMA）PET / CT在前列腺癌（PCA）的分期和再分期中具有公认的作用。这项研究的目的是评估免疫组织化学染色中前列腺内⁶⁸ Ga-PSMA PET / CT结果与PSMA表达之间的关联，并为正常前列腺（PN）和PCA之间的分化产生一个临界值。方法：回顾性分析31例（平均年龄67.2岁）行前列腺切除术和术前PET检查的患者的资料。在PET上，前列腺摄取的局灶性增加提示肿瘤。将感兴趣的区域放置在提示区域上以生成SUV _max; 将相似的感兴趣区域放置在相邻的视觉PN上。PCA和PN均用单克隆抗PSMA抗体（克隆3E6，1：100，M3620）染色。结果： PET上所有前列腺内PCA病变均可通过组织病理学确认。在PN切片（n = 31）中，中度染色强度中等，染色细胞的中值百分比为20％±14.24％，中值免疫反应评分（IRS）为1。在PCA切片中（n = 31），中值IRS为3。 ，中值染色强度很强，染色细胞的中值百分比为80％±16.46％。PCA（14.06±15.56）的平均SUV _max（±SD）显着高于PN（2.43±0.63; P <0.001）。SUV的接收器操作特性曲线分析通过免疫组织化学染色在62个组织样本中验证的_最大PCA值的最佳截止值为3.15（灵敏度为97％；特异性为90％；曲线下面积为0.987）。应用于多焦点PCA，其敏感性和特异性分别为87％和97％。IRS小于2时PCA和PN的平均SUV _max（n = 26; 2.52±0.64）显着低于IRS为2或更高时的平均SUV _max（n = 36; 12.38±15.02; P < 0.001）。染色细胞少于50％的PCA样品（n = 30; 2.81±2.35）的平均SUV _max显着低于50％或更高的PCA样品（n = 32; 13.34±15.55; n = 32。P <0.001）。SUV _max的PCA与Gleason评分之间无相关性（P = 0.54）。结论：这项研究表明，在⁶⁸ Ga-PSMA PET / CT上的SUV _max与原发性PCA中的PSMA表达显着相关，从而能够以高灵敏度和特异性检测PCA。