TY - JOUR
T1 - MRI Evaluation of Rectal Cancer
T2 - Staging and Restaging
AU - Moreno, Courtney C.
AU - Sullivan, Patrick S.
AU - Mittal, Pardeep Kumar
N1 - Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2017/5
Y1 - 2017/5
N2 - Magnetic resonance imaging (MRI) plays an important role in the staging and restaging of rectal cancer. Multiplanar high-resolution (≤3-mm section thickness) T2-weighted images are the primary sequences used for rectal cancer staging. No preprocedural bowel cleansing regimen, intravenous contrast material, nor endorectal coil is necessary. MRI is highly accurate for differentiating T1-T2 disease from T3 and T4 disease, an important distinction as patients with T3 and T4 tumors typically undergo preoperative neoadjuvant chemoradiation before resection. At MRI, the muscularis propria appears as a thin black line encircling the outer wall of the rectum, and tumor extension through this line indicates T3 disease. Further tumor extension into adjacent organs indicates T4 disease. Endorectal ultrasound is generally preferred to differentiate T1 (submucosal involvement) from T2 (extension into but no disruption of muscularis propria) disease. MRI is also accurate in the assessment of tumor involvement of the mesorectal fascia. Tumor involvement of the mesorectal fascia increases the likelihood of recurrence following resection. MRI is less accurate for determination of lymph node status, though heterogeneous signal intensity and irregular margins are suggestive of node positive disease. Approximately 10%-30% of patients who undergo preoperative chemoradiation experience a complete pathologic response that is defined as no residual tumor found at histopathologic analysis of the resected specimen. The addition of diffusion-weighted images to T2-weighted images improves the accuracy of restaging examinations for determination of complete pathologic responders.
AB - Magnetic resonance imaging (MRI) plays an important role in the staging and restaging of rectal cancer. Multiplanar high-resolution (≤3-mm section thickness) T2-weighted images are the primary sequences used for rectal cancer staging. No preprocedural bowel cleansing regimen, intravenous contrast material, nor endorectal coil is necessary. MRI is highly accurate for differentiating T1-T2 disease from T3 and T4 disease, an important distinction as patients with T3 and T4 tumors typically undergo preoperative neoadjuvant chemoradiation before resection. At MRI, the muscularis propria appears as a thin black line encircling the outer wall of the rectum, and tumor extension through this line indicates T3 disease. Further tumor extension into adjacent organs indicates T4 disease. Endorectal ultrasound is generally preferred to differentiate T1 (submucosal involvement) from T2 (extension into but no disruption of muscularis propria) disease. MRI is also accurate in the assessment of tumor involvement of the mesorectal fascia. Tumor involvement of the mesorectal fascia increases the likelihood of recurrence following resection. MRI is less accurate for determination of lymph node status, though heterogeneous signal intensity and irregular margins are suggestive of node positive disease. Approximately 10%-30% of patients who undergo preoperative chemoradiation experience a complete pathologic response that is defined as no residual tumor found at histopathologic analysis of the resected specimen. The addition of diffusion-weighted images to T2-weighted images improves the accuracy of restaging examinations for determination of complete pathologic responders.
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U2 - 10.1067/j.cpradiol.2016.11.011
DO - 10.1067/j.cpradiol.2016.11.011
M3 - Review article
C2 - 28089690
AN - SCOPUS:85009726054
SN - 0363-0188
VL - 46
SP - 234
EP - 241
JO - Current Problems in Diagnostic Radiology
JF - Current Problems in Diagnostic Radiology
IS - 3
ER -