Wael M. Shabana MD, Presenter: Nothing to Disclose

Blair MacDonald, Abstract Co-Author: Nothing to Disclose

Leonard Avruch MD, Abstract Co-Author: Nothing to Disclose

Ania Keilar MD, Abstract Co-Author: Nothing to Disclose

mesorectal lymph nodes are one of the major determinants of disease prognosis in rectal cancer. MRI has higher sensitivity in detecting lymph nodes in the mesorectum compared to endoscopic ultrasound. However the specificity is limited especially in the lymph nodes less than 5mm, where microscopic metastasis could be present. There are no prior reports describing theincidence of mesorectal lymph nodes in normal individuals. 

 in this prospective study, normal patients younger than 50 years of age, who were coming to MRI for non pelvic related imaging (hip pain, lower back pain etc..) as well volunteers with no known pelvic disease were recruited to participate .. Any patient with MRI evident disease was excluded from analysis. A T2 weighted BLADE sequence with 3mm slice thickness were performed in both axial and sagital plains. Both sequences were reviewed by at least 2 experienced radiologists with a third radiologist reading 15% of the cases. In case of disagreement between the two radiologists the third radiologist was consulted with consensus agreement of at least 2 out of the three radiologists to determine whether the lymph nodes were present or absent.

50 subjects enrolled in our study. Only 1 subject demonstrated a tiny lymph node and it was less than 2mm. All the other subjects had no mesorectal lymph nodes.

In normal individuals the incidence of mesorectal lymph nodes is 2% with max size of 2mm. . This pilot study suggests that in patients with rectal cancer, any measureable lymph nodes in the mesorectum should be reported as potentially abnormal.

.This pilot study suggests that in patients with rectal cancer, any measureable lymph nodes in the mesorectum should be reported as potentially abnormal l.

Shabana, W, MacDonald, B, Avruch, L, Keilar, A, Incidence of Mesorectal Lymph Nodes in Normal Individuals.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002314.html