Magnetic Resonance Imaging of Anorectal Neoplasms Girish Raghunathan, Koenraad J. Mortele  Clinical Gastroenterology and Hepatology  Volume 7, Issue 4, Pages 379-388 (April 2009) DOI: 10.1016/j.cgh.2009.01.014 Copyright © 2009 AGA Institute Terms and Conditions

Figure 1 Axial T2-weighted MRI with an endorectal coil. The mucosal/submucosal complex (black arrow) is seen as a relatively hyperintense structure when compared with the muscularis propria. MRI cannot resolve mucosa from submucosa. The muscularis propria appears as a thin hypointense line (white arrow). Note the intermediate signal intensity of the tumor (*) at 1 o'clock position. The hypointense muscularis propria is intact adjacent to the tumor: T1 rectal carcinoma. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 2 Endoanal MRI. (A) Axial T2-weighted image shows intermediate signal intensity internal sphincter (white arrow). (B) Coronal T2-weighted image shows intermediate signal intensity internal sphincter (white arrow) to be continuation of the circular muscle of the rectum, and the hypointense external sphincter (black arrow) surrounds the lower part of the internal sphincter. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 3 Axial T2-weighted MRI. Mesorectal fascia is seen as a thin hypointense line (arrows) surrounding the mesorectal fat and forms the resection margin in TME. In TME, the entire mesorectum including the fascia, nodes, and fat is removed. The white line represents the CRM. MRI is highly accurate in predicting the CRM. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 4 Endorectal MRI. Axial T2-weighted image shows T1 rectal tumor (*). The muscularis propria is intact and is seen as a hypointense line (arrow). Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 5 Endorectal MRI. T2-weighted image shows intermediate signal intensity T2 rectal tumor (*). The normally T2 hypointense muscularis propria is invaded by the tumor, thereby showing an intermediate signal (arrow). Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 6 Endorectal MRI. (A) Axial T2-weighted image and (B) coronal T2-weighted image show T3 rectal tumor. The hypointense muscularis propria has been disrupted, and strands of tumor tissue are seen extending into the mesorectal fat (arrows). Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 7 Endorectal MRI. (A) Axial T2-weighted, (B) axial T1-weighted post gadolinium enhanced images, and (C) sagittal T2-weighted images showing T4 rectal tumor. The tumor invades the prostate (arrows) and enhances post gadolinium administration. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 8 Axial (A) pre and (B) post gadolinium enhanced T1-weighted images show multiple enlarged (more than 5 mm) mesorectal lymph nodes (arrows), most of which lie in the mesorectal fat. N2 nodal stage. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 9 T1 anal carcinoma. (A) Axial T2-weighted image with an endoanal coil shows a soft tissue mass (arrow) in the lower anal canal. There is ill-defined stranding in the perirectal fat, which is an indirect sign of tumor extension. (B) Coronal T2-weighted image in the same patient. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 10 (A) Coronal T2-weighted and (B) T1-weighted post gadolinium enhanced images and (C) sagittal and (D) axial T2-weighted images show a large, eccentrically located, avidly enhancing mass (arrows) that originates from the external anal sphincter: malignant GIST. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions

Figure 11 Endoanal MRI. (A) Axial and (B) coronal T2-weighted images show a broad-based soft tissue mass arising from the anal canal wall (arrows); rectal carcinoid tumor was found after resection. Clinical Gastroenterology and Hepatology 2009 7, 379-388DOI: (10.1016/j.cgh.2009.01.014) Copyright © 2009 AGA Institute Terms and Conditions