Dobos Nora, Rubesin Stephen E
Department of Radiology, MRI Learning Center, 1 Founders, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
Hematol Oncol Clin North Am. 2002 Aug;16(4):875-95. doi: 10.1016/s0889-8588(02)00032-1.
Colorectal carcinoma poses a serious public health threat. Detection in its early stages in the best predictor for long-term survival, which is the impetus for population-based screening programs. We believe that full-colon imaging by either DCBE or colonoscopy is necessary for colon cancer screening because flexible sigmoidoscopy, even if perfect, only detects 50% to 60% of colon cancers, a rate far worse than even the worst rate reported for single-contrast barium enema. Screening for colon cancer with flexible sigmoidoscopy is equivalent to performing a "left" mammogram for the detection of breast cancer. The role of CT colonography is still to be determined. When confronted with a symptomatic patient, barium enema is applied in conjunction with CT to detect primary colorectal carcinoma, to differentiate it from other benign and malignant processes involving the colon, and to assess for disease extent before surgery in selected high-risk patient populations. Pelvic MRI may be useful in the preoperative assessment of patients with rectal carcinoma as a means for assisting surgical planning. CT, MRI, and barium enema are used in postoperative follow-up for detecting local recurrence and distant spread. In response to known difficulty in discriminating between normal postoperative changes and tumor recurrence and in determining the nature of certain liver lesions, FDG-PET has been approved for the detection and localization of recurrent colorectal cancer in patients with rising CEA levels and indeterminate findings on standard imaging studies. Given its current promise of offering high sensitivity, specificity, and accuracy, the indications for PET may well expand in the future, but its final role in still to be determined.
结直肠癌对公众健康构成严重威胁。早期检测是长期生存的最佳预测指标，这也是开展基于人群的筛查项目的动力。我们认为，无论是采用双对比钡灌肠（DCBE）还是结肠镜检查进行全结肠成像，对于结肠癌筛查都是必要的，因为即使是完美的乙状结肠镜检查，也只能检测出50%至60%的结肠癌，这一比例甚至比单对比钡灌肠报告的最差比例还要低得多。用乙状结肠镜检查筛查结肠癌，就如同用“左侧”乳房X线摄影来检测乳腺癌一样。CT结肠成像的作用仍有待确定。对于有症状的患者，钡灌肠结合CT用于检测原发性结直肠癌，将其与涉及结肠的其他良性和恶性病变相鉴别，并在选定的高危患者群体中评估手术前的疾病范围。盆腔MRI对于直肠癌患者的术前评估可能有用，可作为辅助手术规划的一种手段。CT、MRI和钡灌肠用于术后随访，以检测局部复发和远处转移。鉴于在区分正常术后变化与肿瘤复发以及确定某些肝脏病变的性质方面存在已知困难，氟代脱氧葡萄糖正电子发射断层扫描（FDG-PET）已被批准用于检测癌胚抗原（CEA）水平升高且标准影像学检查结果不确定的患者复发性结直肠癌的检测和定位。鉴于其目前有望提供高灵敏度、特异性和准确性，PET的适应证未来很可能会扩大，但其最终作用仍有待确定。
