Potential Value Of MR Colonography With Air Contrast Medium Enema In Detection Of Colorectal Tumors

Objectives1. To assess the feasibility and image quality of magnetic resonance colonography with air contrast medium enema.2. To assess the magnetic resonance colonography sensitivity about colorectal tumors.3. To assess the preoperative satging of colorectal cancer.Materials and Methods Collected30patients with positive fecal occult blood test, defecate character changing,abdominal mass in our hospital who underwent MRI from July2012and March2014including19male patients and11female patients, median age of52years(21-78years). All the patients had no contraindications to MRI and confirmed by colonoscopy and pathology.All the patients underwent bowel preparation the day before, muscle injected20mg scopolamine10minutes before the examination and immited1000-1300ml by transrectal then started to the examination.Using SSFSE and FIESTA order scaned all the colorectal coronary imaging tithin a breathhold and using T1WI, T2WI, DWI order scaned suspected diseased region transverse imaging and took sagittal scaning with rectal lesions.Observing the patients’ tolerance, analyzing the quality of bowel preparation and image. Calculating the detection sensitivity of colorectal tumor and the accuracy of preoperative stagingResults1. Feasibility and image quality of MR colonography:Air as a contrast medium is safe and free.All the patients completed MR Colonography examination and had no adverse reactions within24hours,which only had a little bit abdominal distention feeling during the test.194of240(80.83%) colonic segments were well distended and185of240(77.08%) colonic segments were well prepared.Ascending colon,hepatic flexure,transverse colon and splenic flexure segments are well distended than appendix descending colon,sigmoid colon and rectum segments,between which there was a significant difference by Chi-square test (x2=5.03,P<0.05).The most and least image artifacts were hepatic flexure, transverse (13.33%) and appendix, rectum (3.33%),respectively.2. Sensitivity of colorectal tumor examnation.Compared with fiber colonoscopy and pathology results, the sensitivity of MR colonography with air contrast medium as follows:sensitivity of tumors larger than10mm was91.42%(32/35); sensitivity of tumors between5mm and10mm was66.67%(6/9); the number of tumors smaller than5mm was only1(1/3)3. Preoperative staging of colorectal cancer.25colorectal cancer lesions are qualitative accurate positioning,for TNM staging,T staging and N staging the accuracy rates were76.67%(23/30),83.33%(25/30)and76.67%(23/30).<T2staging accuracy rate was80%(8/10); T3staging accuracy rate was83.33%(15/18); T4staging accuracy rate was100%(2/2).And NO staging the accuracy rate was78.58%(11/14); N1staging the accuracy rate was75%(9/12), N2staging the accuracy rate was75%(3/4).Sensitivity and specificity for lymph node involvement were81.25%(13/16) and78.58%(11/14) respectively. M staging accuracy rate was80%(4/5),MR Colonography detected4liver metastases, but1posterior peritoneum metastasis was missed.Conclusions①Air as a kind of safe and cheap contrast medium is acceptable for the patients, which has no adverse reactions.②MR Colonography with air contrast medium enema has advantages for good bowel expansion, high resolution of soft tissue and no radation which will be a potential method for the detection of colorectal tumors.③MR Colonography with air contrast medium enema has a accurate preoperative staging and evaluating tumor serosal invasion.lymph nodes and organ metastases.