CT Colonography Virtual colonoscopy (or CT colonography) has proven to be a valid tool in identifying both primary and synchronous colonic lesions. Limited information is available regarding the performance of CT colonography for rectal cancer staging. In a study of 45 patients with low rectal adenocarcinomas, CT colonography with multiplanar reformation demonstrated 89% accuracy for T stage [27]. FDG-PET/CT Skull Base to Mid-Thigh Limited recent information is available regarding the performance of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT for local rectal cancer staging. In a study of 59 patients with rectal cancer, conventional FDG- PET/CT was found to be 73.5% accurate for T stage and to have a 64.3% sensitivity and 96.7% specificity for N stage [28]. In an evaluation of 44 pathologic and 19 control lymph nodes, the standardized uptake value (SUV)max and SUVmean were significantly higher in pathological lymph nodes than in control lymph nodes [29]. When used as a preoperative tool in advanced tumors, MRI has shown high diagnostic accuracy for both initial staging to determine surgical plan and determining resectability following neoadjuvant treatment [39-43]. Studies have shown MRI sensitivities ranging from 94% to 100% and specificities from 85% to 88% in assessment of the circumferential resection margin [44,45]. Hence, MRI is valuable in predicting complete resection with negative margins. In a multicenter cohort trial evaluating the use of high-resolution MRI with a phased-array coil in determining resectability, a total of 228 patients underwent curative-intent treatment based on the MRI characterization of tumor extent, with 95.6% of patients achieving margin-negative results [40]. High-risk MRI features (EMVI, extramural tumor depth >5 mm, T4 stage, involved circumferential resection margin) may correlate with a higher risk for distant metastases [46,47].
Staging of Colorectal Cancer. CT Colonography Virtual colonoscopy (or CT colonography) has proven to be a valid tool in identifying both primary and synchronous colonic lesions. Limited information is available regarding the performance of CT colonography for rectal cancer staging. In a study of 45 patients with low rectal adenocarcinomas, CT colonography with multiplanar reformation demonstrated 89% accuracy for T stage [27]. FDG-PET/CT Skull Base to Mid-Thigh Limited recent information is available regarding the performance of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT for local rectal cancer staging. In a study of 59 patients with rectal cancer, conventional FDG- PET/CT was found to be 73.5% accurate for T stage and to have a 64.3% sensitivity and 96.7% specificity for N stage [28]. In an evaluation of 44 pathologic and 19 control lymph nodes, the standardized uptake value (SUV)max and SUVmean were significantly higher in pathological lymph nodes than in control lymph nodes [29]. When used as a preoperative tool in advanced tumors, MRI has shown high diagnostic accuracy for both initial staging to determine surgical plan and determining resectability following neoadjuvant treatment [39-43]. Studies have shown MRI sensitivities ranging from 94% to 100% and specificities from 85% to 88% in assessment of the circumferential resection margin [44,45]. Hence, MRI is valuable in predicting complete resection with negative margins. In a multicenter cohort trial evaluating the use of high-resolution MRI with a phased-array coil in determining resectability, a total of 228 patients underwent curative-intent treatment based on the MRI characterization of tumor extent, with 95.6% of patients achieving margin-negative results [40]. High-risk MRI features (EMVI, extramural tumor depth >5 mm, T4 stage, involved circumferential resection margin) may correlate with a higher risk for distant metastases [46,47].