King C M, Reznek R H, Dacie J E, Wass J A
Department of Radiology, St Bartholomew's Hospital, London.
Clin Radiol. 1994 May;49(5):295-303. doi: 10.1016/s0009-9260(05)81790-8.
The localization of islet cell tumours presents a challenge to the radiologist and requires meticulous attention to detail in both technique and interpretation. As several imaging techniques are capable of demonstrating the tumour and none is absolutely accurate, a rational approach to the localization of these tumours requires a careful consideration of cost, sensitivity and the availability of special expertise. In almost all cases, initial imaging is performed with a combination of transabdominal ultrasound and CT. This will demonstrate the tumour and any hepatic metastases in about 40% of gastrinomas, 80% of insulinomas and almost all other functioning and non-functioning tumours. Where these tests are negative or equivocal, arteriography (which may be combined with ASVS) is the next line of investigation. If the tumour remains undetected, it is likely to be a small insulinoma or gastrinoma. Further investigation is dependent on local practice and the tumour type. Endoscopic ultrasound is rapidly emerging as a technique of high sensitivity in detecting small pancreatic tumours and may also demonstrate extrapancreatic gastrinomas. Transhepatic venous sampling and somatostatin receptor imaging have the advantage that they are not directly dependent on tumour size and they are particularly applicable to difficult cases where other imaging modalities are negative. TPVS is invasive and, while sensitive for insulinomas, is frequently unhelpful in gastrinomas. Somatostatin receptor scintigraphy, on the other hand, is more sensitive for gastrinomas. In future, MRI may prove to be at least as accurate as CT but as yet its exact role is uncertain. At the time of surgery, intraoperative ultrasound is a useful adjunct to palpation, and may avoid a standard distal pancreatectomy in patients with insulinoma.
胰岛细胞瘤的定位给放射科医生带来了挑战，在技术和解读方面都需要极其细致地关注细节。由于多种成像技术都能够显示肿瘤，但没有一种是绝对准确的，因此对这些肿瘤进行定位的合理方法需要仔细考虑成本、敏感性以及专业技术的可用性。在几乎所有情况下，初始成像采用经腹超声和CT相结合的方式。这将在约40%的胃泌素瘤、80%的胰岛素瘤以及几乎所有其他功能性和非功能性肿瘤中显示出肿瘤及任何肝转移灶。如果这些检查结果为阴性或不明确，动脉造影（可与动脉刺激静脉取血术联合使用）是下一步的检查手段。如果肿瘤仍未被发现，很可能是小的胰岛素瘤或胃泌素瘤。进一步的检查取决于当地的实际情况和肿瘤类型。内镜超声作为一种检测小胰腺肿瘤的高灵敏度技术正在迅速兴起，也可能显示胰腺外的胃泌素瘤。经肝静脉采血和生长抑素受体显像的优势在于它们不直接依赖于肿瘤大小，特别适用于其他成像方式为阴性的疑难病例。经皮经肝门静脉取血术具有侵入性，虽然对胰岛素瘤敏感，但对胃泌素瘤常常没有帮助。另一方面，生长抑素受体闪烁显像对胃泌素瘤更敏感。未来，磁共振成像可能证明至少与CT一样准确，但目前其确切作用尚不确定。在手术时，术中超声是触诊的有用辅助手段，对于胰岛素瘤患者可能避免进行标准的胰体尾切除术。
