MR rectum imaging with ultra sound gel as instrumental contrast media in tubulovillous adenoma
Bacground. Colorectal polyps are frequent and can be found in 10% of adults, most common in elderly with prevalence of 20% in age group of 60. Over 90% cases of cancer are being developed from benign adenomas. Colorectal cancer (CRC) is a significantly large cause of death right after bronchial cancer in males, and breast cancer in women. Therefore, a standpoint was adopted that the removal of polyps as precursor will prevent the development of colorectal area cancer. Polyps can occur as peduncular or sessile. Adenomas are grouped in three subtypes based on histological criteria: tubular, tubulovillous and villous. Villous adenomas are larger than others and show a higher level of dysplasia. The prevalence of adenomas increases with the patient’s age. Having in mind that the risk of malign adenoma transformation is 10 years average, and that small lesions have no clinical potential to turn into cancer, their removal would lead to unnecessary complications and additional costs. CRC risk grows both with the size and the number of adenomas. In patients who refuse polypectomy, we can expect cancer development in average of 5 years 4% and in 10 years 14%.
Case report. We present a patient with a years long history of rectal polyp. She has refused any treatment of polyp removal up so far. Due to stool problems, mostly constipation, occasional bleeding and falling out feeling, she has decided to remove the polyp. The polyp has been detected through colonoscopy and described as very risky for polypectomy due to its suspected malign appearance. We did rectum MR on 1.5T Siemens, so that the patient came with clean lumen into which we applied ultra sound gel with huge 60 ml syringe (no needle) simply and pain free with three fillings (total 180 ml of gel). We have concluded that the polyp was of uneven outline and stretched partially along the inner rectum wall without extra rectal infiltration into mesorectal area. After that, we performed endoscopic polypectomy according to peace meal method resection up to real muscular layer after adrenalin undermining. Pathohistological finding which was done in HE technique showed tubulovillous adenoma.
Conclusions. Rectal MR is a new, very reliable method of contemporary radiological imaging that gives better characterization of polyp tissue and of other tumours. It is currently the best imaging modality enabling very accurate evaluation and topographic ratio of tumour growth within the rectum wall and outside the wall, especially compared to mesorectal fascia. In addition, it is a very comfortable procedure without radiation. The application of ultra sound gel as intra luminal rectal contrast agent can distend the lumen and make an excellent contrast of lumen against the rectum wall and thus can better show polyps and tumours.