18F-FDG PET-CT在卵巢正常大小癌综合征诊断中的应用

  目的  卵巢正常大小癌综合征（NOCS）指的是盆腹腔广泛癌变，而卵巢正常大小的一种现象，通常是原发病变不明确，而常规影像学很难有阳性发现，本研究旨在探讨18F-FDG PET-CT在检出NOCS原发病变方面的作用。   方法  17例临床诊断NOCS女性患者均进行18F-FDG PET-CT的常规扫描及延迟显像；图像由两名核医学医生独立分析，其按诊断标准进行判断，1）卵巢以两次显像SUV≥3.0为诊断恶性病变的标准，其他脏器以发现局灶性代谢增高为诊断标准，浆膜代谢增高考虑为转移受累；2）以卵巢发现肉眼可见的代谢增高，胃肠道（尤其是胃壁）异常的局灶性增厚及肉眼可见的局灶性的代谢增高进行诊断；结果与剖腹探查病理结果或治疗随诊结果对照，判断18F-FDG PET-CT查找NOCS原发病灶的准确性。   结果  17例NOCS患者中，按标准其一诊断，18F-FDG PET-CT发现13例原发病变，9例卵巢癌，2例胃癌（均伴有双侧卵巢转移即krukenberg瘤），1例乙状结肠癌，1例腹膜血管肉瘤；漏诊1例胃癌及3例卵巢原发病变。因此PET-CT查找NOCS原发病变的检出率为76.5%，阳性预测值为100%。按照标准其二诊断，可另发现1例卵巢代谢略增高，SUVmax=2.5的病理最后诊断为卵巢癌，漏诊1例胃癌可见胃壁局限性轻度增厚、僵硬，按照标准2病变的检出率能提高至88.2%；11例卵巢原发病变的患者中7例检查前行肿瘤标志物检查，发现CA125均有不同程度的增高，胃肠道患者CEA及CA199有不同程度增高。   结论  对于NOCS的患者18F-FDG PET-CT能有效的查找原发病灶，减少剖腹探查的患者数量；在NOCS患者中原发卵巢癌是主要组成部分；NOCS患者多有不同程度的肿瘤标志物的升高，18F-FDG PET-CT和肿瘤标志物可更好的查找NOCS的原发病灶。胃癌尤其是黏液成分较高的胃癌易于腹腔转移并侵犯卵巢形成kruken? berg瘤，PET-CT则可以同时发现胃和卵巢的病变；原发于卵巢及胃壁的NOCS的原发病变不能以SUV值进行诊断，肉眼发现卵巢可见的代谢增高，胃壁发现僵硬及增厚，结合临床指标即应该考虑恶性病变的存在。 

Application of 18F-FDG PET-CT in the Diagnosis of Ovarian Cancer Syndrome

  Objective  To evaluate the value of 18F-FDG positron emission tomography-computed tomography (PET-CT) in detecting the primary cause of normal-sized ovarian cancer syndrome (NOCS).   Methods  A retrospective study on 17 NOCS female patients, who underwent whole-body PET-CT and pathologic examination at Beijing Army General Hospital during 2005 and 2010, was conducted. The interpretation criteria were as follows.Criterion 1: Ovaries with SUVmax ≥ 3.0 and any abnormal focal lesion with 18F-FDG uptake greater than the surrounding background activity of the organ being examined were interpreted as possible sites of the malignant disease. High uptake of serous membrane was interpreted as metastasis. Criterion 2: Visible high uptake and abnormal thickening and projections in the stomach wall were interpreted as possible sites of the malignant disease. The image interpretation of 18F-FDG PET-CT was based on the consensus of two nuclear medicine physicians.   Results  The result of interpretation criterion 1 showed that PET detected 13 occult primary tumors in 17 NOCS patients (detection rate of 76.5%), including ovarian cancer (n= 9), gastric cancer (n= 2) with ovarian metastasis (Krukenberg tumor), sigmoid colon carcinoma (n= 1), and peritoneal hemangiosarcoma (n= 1). Three patients with false-negative PET findings were diagnosed with ovarian cancer, and one was diagnosed with gastric cancer. The positive predictive value was 100%. The result of interpretation criteria 2 showed that one ovarian cancer with SUVmax of 2.5 was malignant. Moreover, gastric cancer without high uptake showed abnormal thickening of the stomach wall in CT. The detection rate was 88.2%. All 7 patients underwent tumor marker examinations before PET, which showed elevated serum CA125 levels.   Conclusion  PET-CT can be a valuable tool for identifying a subset of patients with NOCS. Ovarian cancer is the main component of all primary lesions in NOCS. Gastric tumor containing mucus or signet ring cell carcinoma which invades ovaries and causes Krukenberg tumor. PET-CT can simultaneously detect primary gastric cancer and ovarian metastasis. Moreover, SUV does not clearly indicate ovarian and gastric cancers. Thus, visual interpretation is very important. Elevated tumor markers can also be indicators of NOCS.