Lawal Ismaheel O, Ankrah Alfred O, Mokgoro Neo P, Vorster Mariza, Maes Alex, Sathekge Mike M
Department of Nuclear Medicine, University of Pretoria and Steve Biko Academic Hospital, Pretoria, South Africa.
Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Prostate. 2017 Aug;77(11):1205-1212. doi: 10.1002/pros.23379. Epub 2017 Jun 26.
Emerging data from published studies are demonstrating the superiority of Ga-68 PSMA PET/CT imaging in prostate cancer. However, the low yield of the Ge-68/Ga-68 from which Gallium-68 is obtained and fewer installed PET/CT systems compared to the SPECT imaging systems may limit its availability. We, therefore, evaluated in a head-to-head comparison, the diagnostic sensitivity of Ga-68 PSMA PET/CT and Tc-99m PSMA SPECT/CT in patients with prostate cancer.
A total of 14 patients with histologically confirmed prostate cancer were prospectively recruited to undergo Ga-68 PSMA PET/CT and Tc-99m HYNIC PSMA SPECT/CT. The mean age of patients was 67.21 ± 8.15 years and the median PSA level was 45.18 ng/mL (range = 1.51-687 ng/mL). SUVmax of all lesions and the size of lymph nodes with PSMA avidity on Ga-68 PSMA PET/CT were determined. Proportions of these lesions detected on Tc-99m HYNIC PSMA SPECT/CT read independent of PET/CT findings were determined.
A total of 46 lesions were seen on Ga-68 PSMA PET/CT localized to the prostate (n = 10), lymph nodes (n = 24), and bones (n = 12). Of these, Tc-99m HYNIC PSMA SPECT/CT detected 36 lesions: Prostate = 10/10 (100%), lymph nodes = 15/24 (62.5%), and bones = 11/12 (91.7%) with an overall sensitivity of 78.3%. Lesions detected on Tc-99m HYNIC PSMA SPECT/CT were bigger in size (P < 0.001) and had higher SUVmax (P < 0.001) as measured on Ga-68 PSMA PET/CT compared to those lesions that were not detected. All lymph nodes greater than 10 mm in size were detected while only 28% of nodes less than 10 mm were detected by Tc-99m HYNIC PSMA SPECT/CT. In a univariate analysis, Lymph node size (P = 0.033) and the SUVmax of all lesions (P = 0.007) were significant predictors of lesion detection on Tc-99m HYNIC PSMA SPECT/CT.
Tc-99m HYNIC PSMA may be a useful in imaging of prostate cancer although with a lower sensitivity for lesion detection compared to Ga-68 PSMA PET/CT. Its use is recommended when Ga-68 PSMA is not readily available, in planning radio-guided surgery or the patient is being considered for radio-ligand therapy with Lu-177 PSMA. It performs poorly in detecting small-sized lesions hence its use is not recommended in patients with small volume disease.
已发表研究中的新数据表明，镓-68前列腺特异性膜抗原正电子发射断层扫描/计算机断层扫描（Ga-68 PSMA PET/CT）成像在前列腺癌中具有优势。然而，用于获取镓-68的锗-68/镓-68产率较低，且与单光子发射计算机断层扫描（SPECT）成像系统相比，正电子发射断层扫描/计算机断层扫描（PET/CT）系统的安装数量较少，这可能会限制其可用性。因此，我们进行了一项直接比较，评估了Ga-68 PSMA PET/CT和锝-99m前列腺特异性膜抗原单光子发射计算机断层扫描/计算机断层扫描（Tc-99m PSMA SPECT/CT）在前列腺癌患者中的诊断敏感性。
前瞻性招募了14例经组织学确诊的前列腺癌患者，使其接受Ga-68 PSMA PET/CT和Tc-99m 次氮基三乙酸（HYNIC）PSMA SPECT/CT检查。患者的平均年龄为67.21±8.15岁，前列腺特异性抗原（PSA）水平中位数为45.18 ng/mL（范围=1.51 - 687 ng/mL）。测定了Ga-68 PSMA PET/CT上所有病变的最大标准化摄取值（SUVmax）以及具有PSMA亲和力的淋巴结大小。确定了在独立于PET/CT检查结果读取的Tc-99m HYNIC PSMA SPECT/CT上检测到的这些病变的比例。
在Ga-68 PSMA PET/CT上共发现46个病变，位于前列腺（n = 10）、淋巴结（n = 24）和骨骼（n = 12）。其中，Tc-99m HYNIC PSMA SPECT/CT检测到36个病变：前列腺=10/10（100%），淋巴结=15/24（62.5%），骨骼=11/12（91.7%），总体敏感性为78.3%。与未检测到的病变相比，Tc-99m HYNIC PSMA SPECT/CT检测到的病变在Ga-68 PSMA PET/CT上尺寸更大（P < 0.001）且SUVmax更高（P < 0.001）。所有大于10 mm的淋巴结均被检测到，而Tc-99m HYNIC PSMA SPECT/CT仅检测到28%小于10 mm的淋巴结。在单因素分析中，淋巴结大小（P = 0.033）和所有病变的SUVmax（P = 0.007）是Tc-99m HYNIC PSMA SPECT/CT上病变检测的显著预测因素。
Tc-99m HYNIC PSMA可能对前列腺癌成像有用，尽管与Ga-68 PSMA PET/CT相比，其病变检测敏感性较低。当无法轻易获得Ga-68 PSMA时，在规划放射性引导手术或考虑对患者进行镥-177 PSMA放射性配体治疗时，建议使用该方法。它在检测小尺寸病变方面表现不佳，因此不建议在疾病体积较小的患者中使用。
