Dr. Khaleel Ibraheem Mohson, Anas K. Awn
Abstract: Backgroundthe incidence of colorectal cancer has been increasing dramatically following thefinancial and economic advancements. Now, colorectal cancer is the third foremost cause of cancer deaths in both males and femalesin the United States.Many diagnostic tools had been emerging in the screening and early diagnosis of the disease including fecal occult blood and colonoscopy, but from a radiological viewpoint, Magnetic Resonance (MR) imaging is still by far the primary cross-sectional imaging modality used for preoperative local staging of rectal cancer, patient-follow up after rectal surgery and neoadjuvant chemotherapy due to its high spatial resolution and marked soft-tissue characterization. Objectivethe objective of this studyis to assess the role of MR imaging in recurrent rectal tumor detection, its site, signal characteristics and appearance on variable sequences and whether or not the tumor is resectable. Patients and method this is a retrospective study compromised of 50 patients, it was performed during the period of November 2016 to September 2017 in MR unit in the Oncology Teaching Hospital, Medical City Compound, where the patients were referred from the Oncology Clinic then their imaging findings were assessed by specialist radiologists. ResultsA review of the study that compromised of 50 patients with rectal cancer and underwent surgery, 20 were males and 30 were females, their age ranges between 28-85 years, 12 patients (24 %) showed no recurrence while the remaining 38 patients (76 %) showed recurrence. However, ofthe recurrent tumor patients, 12 had recurrence at ileoanal anastomosis site in which 5 had intramural (41 %), 5 hadextraluminal (41 %) and 2 patients had both intra- and extramural recurrence. While in patients with abdominoperineal resection, 9 had anterior local recurrence (34.6 %) and 7 cases of presacral regrowth were found (27 %), only 3 patients showed lateral pelvic wall muscular invasion (11.5 %). Also, lymph nodes recurrence was found in 7 patients mainly involving the mesorectal group (57 %). The obturator group involved in (28 %) and least infiltrated nodes were the inguinal group in (15 %). The results of theMR signal in corresponding to nearby pelvic muscles on T1 and T2 weighted images were isointense in 68 % and greater than in 32 %, while the enhancement pattern after intravenous Gadolinium is equal to ileum wall enhancement in 76 % and greater than in 24 %. ConclusionMR imaging is thepreferred imaging modality inevaluation and patient- follow up with suspicious recurrence after rectal malignancy surgery.Its value was demonstrated in characterization and diagnosis of pelvis lesion (s) by assessing their appearance on T1, T2 and fat suppression T2 MR sequences, as well as assessing their enhancement pattern after intravenous Gadolinium in fat suppression sequence.
Keywords: rectal tumor, recurrence pattern, MR imaging, Gadolinium fat suppression T1, pelvic muscles signal