Perveen Gazala, Arora Geetanjali, Damle Nishikant Avinash, Prabhu Meghana, Arora Saurabh, Tripathi Madhavi, Bal Chandrasekhar, Kumar Praveen, Kumar Rajeev, Singh Prabhjot
Department of Nuclear Medicine, AIIMS, New Delhi, India.
Department of Urology, AIIMS, New Delhi, India.
Indian J Nucl Med. 2018 Apr-Jun;33(2):112-117. doi: 10.4103/ijnm.IJNM_8_18.
Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is widely used for imaging of prostate cancer (PC) nowadays. However, appearance of bladder activity many a times hampers lesion detection vis-a-vis primary as well as regional nodes. We aimed to assess if early dynamic PET/CT can be a potential solution to this issue.
A total of 15 biopsy-proven PC patients who were referred to our department for Ga-PSMA PET/CT for staging/restaging were prospectively studied. Dynamic PET/CT was done with on table intravenous injection of 2-3 mCi (74-111 MBq) of the radiotracer. Dynamic images were acquired over the pelvis with a frame time of 1 min for 10 min. Static images of 2 min per bed position were acquired between 45 and 60 min after injection. A 3D volume of interest was plotted on the primary lesion, involved nodes if any, pelvic bones at involved and uninvolved sites, gluteal muscles, and bladder.
Six patients were referred for staging and 9 for restaging. Mean age of 15 patients was 66.7 years, median prostate-specific antigen level was 17.25 ng/ml (Range 0.05-218), mean Gleason score was 8. All patients showed high target to nontarget ratio in the early dynamic images comparable to that seen on the delayed images in different sites (prostatic primary: = 15 patients; lymph nodes: = 10 patients; bone: = 5 patients). All pathologic lesions showed tracer uptake within the first 3 min and reached maximum uptake during the dynamic study in last 3 min, indicating an increasing uptake pattern, whereas urinary bladder (UB) activity was insignificant within the first 3 min of dynamic imaging in all patients, reached maximum during last 3 min. SUV was significantly higher in primary lesions in the first 4 min compared to UB accumulation. Static images showed more tracer accumulation than dynamic images in primary, nodal, and bony lesions. However, all regional nodes seen on delayed static imaging also showed uptake on dynamic imaging.
Early dynamic imaging Ga-PSMA PET/CT can demarcate the primary tumor clearly due to nonaccumulation of bladder activity and appears to have comparable efficacy in detecting pelvic nodal sites as delayed imaging.
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（PSMA PET/CT）如今广泛用于前列腺癌（PC）的成像。然而，膀胱活动的出现多次妨碍了对原发灶以及区域淋巴结病变的检测。我们旨在评估早期动态PET/CT是否可能是解决此问题的潜在方法。
前瞻性研究了总共15例经活检证实为PC的患者，他们因Ga-PSMA PET/CT分期/再分期而转诊至我们科室。在检查台上静脉注射2 - 3毫居里（74 - 111兆贝可）放射性示踪剂后进行动态PET/CT检查。在骨盆区域采集动态图像，帧时间为1分钟，共采集10分钟。在注射后45至60分钟之间，每个床位采集2分钟的静态图像。在原发灶、如有受累的淋巴结、受累和未受累部位的骨盆骨、臀肌以及膀胱上绘制三维感兴趣区。
6例患者转诊进行分期，9例进行再分期。15例患者的平均年龄为66.7岁，前列腺特异性抗原水平中位数为17.25纳克/毫升（范围0.05 - 218），平均 Gleason评分8分。所有患者在早期动态图像中显示出高的靶与非靶比值，与不同部位延迟图像中的情况相当（前列腺原发灶：n = 15例患者；淋巴结：n = 10例患者；骨：n = 5例患者）。所有病理性病变在最初3分钟内显示示踪剂摄取，并在动态研究的最后3分钟达到最大摄取，表明摄取模式呈增加趋势，而在所有患者动态成像的最初3分钟内膀胱（UB）活动不明显，在最后3分钟达到最大值。与UB积聚相比，原发灶在最初4分钟内的SUV显著更高。静态图像在原发灶、淋巴结和骨病变中显示出比动态图像更多的示踪剂积聚。然而，延迟静态成像中看到的所有区域淋巴结在动态成像中也显示有摄取。
早期动态成像的Ga-PSMA PET/CT由于膀胱无活动积聚可清晰界定原发肿瘤，并且在检测盆腔淋巴结部位方面似乎与延迟成像具有相当的效果。
