Spectrum CT with Isotonic Mannitol Gastrointestinal Hypotonic Radiography in the Staging of Rectal Carcinoma / 中国医学影像学杂志

ABSTRACT

Purpose To evaluate the diagnostic efficiency of spectral CT imaging combined with oral isotonic mannitol gastrointestinal hypotonic radiography in the diagnosis of preoperative T and N staging of rectal carcinoma. Materials and Methods Forty-seven patients with rectal cancer confirmed by surgery and pathology were included in this study, all the subjects underwent oral isotonic mannitol gastrointestinal hypotonic radiography prior to CT scan, then abdominal and pelvic plain and double-phase contrast-enhanced CT scan in the spectral imaging mode was performed, the optimal contrast-to-noise ratio imaging were got by the spectrum analysis software, then T-stage was evaluated and compared with pathological T-stage; N-stage was evaluated using both traditional method and the spectral curve method, and compared with pathological N-stage. Results ① All the 47 patients were able to successfully complete the examination and the rectal filling and lesion display were satisfactory; ② the best diagnostic accuracy of T-stage by the monochromatic images was 83.0% (39/47), which had a general correlation with pathologic results (Kappa=0.713, P<0.001); ③ the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of N-stage by the traditional method were 78.72%, 80.95%, 76.92%, 73.91% and 83.33%, respectively, which had a general correlation with pathologic results (Kappa=0.574, P<0.001); the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of N-stage by the Spectral curve method were 89.13%, 75.00%, 100.00%, 100.00% and 83.87%, respectively, which had a fair correlation with pathologic results (Kappa=0.772, P<0.001). Spectral curve method had higher Youden index for N-stage evaluation than traditional method (0.64 vs. 0.58). Conclusion Oral isotonic mannitol gastrointestinal hypotonic radiography can provide a good rectal background, and it is a safe and reliable method for rectal examination, when combined with spectrum CT imaging, it is able to display the detail of lesions and identity the homology of lymph nodes, which might help to make more accurate preoperative T, N staging of rectal carcinoma.