Terry S. Desser MD, Presenter: Nothing to Disclose

Daniel Jason Aaron Margolis MD, Abstract Co-Author: Nothing to Disclose

Andrew Shelton MD, Abstract Co-Author: Nothing to Disclose

Mark Welton, Abstract Co-Author: Nothing to Disclose

R. Brooke Jeffrey MD, Abstract Co-Author: Nothing to Disclose

Patients with rectal cancer routinely undergo preoperative CT to detect metastases. We hypothesized that a modified MDCT protocol could provide additional local staging information.

Patients referred for staging of known rectal masses underwent MDCT scanning using an abdomen-pelvis protocol modified to provided high-resolution images of the pelvis. 38 patients with rectal masses underwent a total of 45 rectal protocol MDCT scans. Of these patients, one refused surgery, two died prior to surgery, 3 had metastatic disease to the rectum on biopsy, and 7 are currently undergoing adjuvant therapy. The remaining 25 patients had surgery within one month following preoperative imaging studies. Endoscopic ultrasound (EUS) was performed in 14 of these patients. The pelvis was scanned in both arterial and portal venous phases during instillation of water into the rectum. Pelvic images were then retrospectively reconstructed at 1.25 mm slice thickness and 0.6 mm reconstruction interval with a 20-cm field-of-view and then imported onto GE advantage workstations for multiplanar reconstruction. Transmural extension of tumor was diagnosed when the outer rectal wall was nodular or obvious invasion was seen into adjacent organs or perirectal fat. CT T-staging (T T3) results were compared with endoscopic ultrasound and pathologic stages when available.

Pathologic stages in resected specimens were as follows: T1=3, T2=9, T3=8, T4=1; T0 (no residual tumor)= 3, Tx (indeterminate) = 1. CT provided the correct T stage (T ≤ T2 or T ≥ T3) in 15 (60%) and overstaged 9 patients (36 %). No patients with stage > T3 were understaged by CT. EUS correctly staged 7 (46%), overstaged 5 (33%), and understaged 2 (13%). CT overstages would have been minimized by restricting T3 classification to only those tumors with clear tongues of tumor extending into fat. Water instillation provided excellent distention of the lumen and good contrast with the enhancing rectal wall. Visualization of enlarged mesorectal lymph nodes and regional anatomy was superior to EUS.

MDCT can provide valuable information about local extent of rectal cancer.

Desser, T, Margolis, D, Shelton, A, Welton, M, Jeffrey, R, MDCT for Local Staging of Rectal Cancer: Comparison with Endoscopic Ultrasound.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408533.html