Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Ann Nucl Med. 2012 Jul;26(6):492-500. doi: 10.1007/s12149-012-0599-y. Epub 2012 Apr 11.
In dual-time-point PET/CT, early delayed scanning (D-1) just after the completion of whole body scanning (E) is easy to perform without additional radiation exposure and repositioning. Our aim was to assess the clinical value of D-1 compared with conventional delayed scanning (D-2).
Our institutional review board approved this retrospective study. Fifty-four patients with known or suspected colorectal cancer underwent (18)F-FDG PET/CT at our institution. The E scan at 1-h post-injection was followed by D-1 at 85 ± 7 min post-injection and D-2 at 124 ± 7 min post-injection. The clinical value of D-1 was evaluated by comparing diagnostic performance with D-2 for differentiating physiologic from pathological uptake and for staging colorectal cancer. Colonoscopic findings, histopathological results and clinical follow-up including radiological findings were used as reference standards.
Thirty-two, eight and 73 focal or short segmental FDG foci by physiologic processes in the colon/rectum, the small intestine and the ureter, respectively, noted in the E scan were evaluated in this study. Using D-1 and D-2, 14/32 (44%) and 17/32 (53%) in the colon/rectum, 5/8 (63%) and 8/8 (100%) in the small intestine, and 55/73 (75%) and 69/73 (95%) in the ureter, respectively, were accurately interpreted as physiologic with the change of intensity and/or shape/location. A significant difference between D-1 and D-2 was observed in the ureter, but not in the bowel. The 55 colorectal cancers were finally diagnosed in 52 patients. In the staging of colorectal cancer, there were no significant differences among the three scans in the lesion-based detectability, the patient-based sensitivity, specificity and accuracy for the identification of primary tumors, nodal and hepatic metastases, and dissemination.
Neither D-1 nor D-2 improved staging of colorectal cancer. However, delayed scans yielded information useful for differentiating physiologic uptake from pathological uptake and D-1 may provide comparable efficacy with D-2 in the bowel. Because of the ease of acquisition, the D-1 scan was considered a practical way to reduce false-positives in the abdomen and possibly helpful to avoid unnecessary additional invasive examinations, such as colonoscopy.
在双时相 PET/CT 中，在完成全身扫描（E）后立即进行早期延迟扫描（D-1），可避免额外的辐射暴露和重新定位，操作相对简单。我们的目的是评估 D-1 与常规延迟扫描（D-2）相比的临床价值。
本回顾性研究经机构审查委员会批准。54 例已知或疑似结直肠癌患者在我院行 18F-FDG PET/CT 检查。注射后 1 小时进行 E 扫描，然后在注射后 85±7 分钟进行 D-1 扫描，在注射后 124±7 分钟进行 D-2 扫描。通过比较 D-1 和 D-2 对区分生理性摄取和病理性摄取以及对结直肠癌分期的诊断性能来评估 D-1 的临床价值。以结肠镜检查结果、组织病理学结果和临床随访（包括影像学结果）作为参考标准。
在 E 扫描中，32 个、8 个和 73 个分别为结肠/直肠、小肠和输尿管的生理性过程中的局灶性或短节段 FDG 摄取灶。在本研究中，使用 D-1 和 D-2，分别有 14/32（44%）和 17/32（53%）在结肠/直肠、5/8（63%）和 8/8（100%）在小肠、55/73（75%）和 69/73（95%）在输尿管中被准确地解释为生理性，其摄取强度和/或形态/位置发生了变化。在输尿管中，D-1 和 D-2 之间存在显著差异，但在肠道中没有差异。55 例结直肠癌最终在 52 例患者中确诊。在结直肠癌分期中，三种扫描在检出病变、患者的敏感性、特异性和准确性方面，对原发肿瘤、淋巴结和肝转移及播散的识别均无显著差异。
D-1 和 D-2 均不能改善结直肠癌的分期。然而，延迟扫描可提供有助于区分生理性摄取和病理性摄取的信息，D-1 可能与 D-2 具有相当的效果。由于采集相对容易，D-1 扫描被认为是减少腹部假阳性的一种实用方法，并且可能有助于避免不必要的额外侵入性检查，如结肠镜检查。
