CT Chest, Abdomen, and Pelvis Most studies show comparable or improved sensitivity for detection of colorectal liver metastases with IV conventional extracellular gadolinium agent-enhanced MRI compared with CT [110,111]. Abdominal/pelvic CT with IV contrast has a high negative predictive value of 90% [112]. Detection of possible lung metastases is also an important part of the initial imaging evaluation of patients with colorectal carcinoma. The National Comprehensive Cancer Network recommends that patients with newly diagnosed colorectal cancer undergo staging chest CT, because staging chest CT has been shown to detect more lung metastases than chest radiography [119]. In a series of 74 patients with newly diagnosed rectal cancer who underwent both chest CT and chest radiography, 37% of patients with a normal chest radiograph had a lesion visible only on the chest CT, and 17% of these patients were found to have at least one pulmonary metastasis [119]. Among patients with potentially resectable liver metastases and a negative initial chest PET, additional imaging with a chest CT revealed pulmonary metastases in 5% of patients [120]. A potential pitfall of chest CT is the detection of small indeterminate pulmonary nodules that are not metastases [121]. In another study, approximately one-fourth of the indeterminate lesions on preoperative CT ultimately developed into metastases and 1 in 10 into other lung malignancies [122]. Chest CT examinations performed to evaluate for pulmonary metastases were typically performed with IV contrast material [121,123,124]. FDG-PET/CT Skull Base to Mid-Thigh Although there is some evidence to support the use of PET/CT in the local staging of patients with rectal carcinoma, the more common clinical application of PET/CT is in identifying nodal and distant metastases [125-127].
Staging of Colorectal Cancer. CT Chest, Abdomen, and Pelvis Most studies show comparable or improved sensitivity for detection of colorectal liver metastases with IV conventional extracellular gadolinium agent-enhanced MRI compared with CT [110,111]. Abdominal/pelvic CT with IV contrast has a high negative predictive value of 90% [112]. Detection of possible lung metastases is also an important part of the initial imaging evaluation of patients with colorectal carcinoma. The National Comprehensive Cancer Network recommends that patients with newly diagnosed colorectal cancer undergo staging chest CT, because staging chest CT has been shown to detect more lung metastases than chest radiography [119]. In a series of 74 patients with newly diagnosed rectal cancer who underwent both chest CT and chest radiography, 37% of patients with a normal chest radiograph had a lesion visible only on the chest CT, and 17% of these patients were found to have at least one pulmonary metastasis [119]. Among patients with potentially resectable liver metastases and a negative initial chest PET, additional imaging with a chest CT revealed pulmonary metastases in 5% of patients [120]. A potential pitfall of chest CT is the detection of small indeterminate pulmonary nodules that are not metastases [121]. In another study, approximately one-fourth of the indeterminate lesions on preoperative CT ultimately developed into metastases and 1 in 10 into other lung malignancies [122]. Chest CT examinations performed to evaluate for pulmonary metastases were typically performed with IV contrast material [121,123,124]. FDG-PET/CT Skull Base to Mid-Thigh Although there is some evidence to support the use of PET/CT in the local staging of patients with rectal carcinoma, the more common clinical application of PET/CT is in identifying nodal and distant metastases [125-127].