Rectal carcinoma: thin-section MR imaging for staging in 28 patients

Area of Science:

• Radiology
• Oncology
• Surgical Pathology

Background:

• Rectal cancer staging is crucial for prognosis and treatment planning.
• Accurate assessment of extramural tumor infiltration depth is vital for determining surgical approach and adjuvant therapy.
• Thin-section magnetic resonance (MR) imaging offers high-resolution visualization of rectal anatomy.

Purpose of the Study:

• To evaluate the accuracy of thin-section MR imaging in preoperative assessment of extramural tumor infiltration depth in rectal cancer.
• To determine the correlation between MR imaging findings and histopathologic staging.
• To assess the utility of MR imaging in identifying tumors requiring preoperative adjuvant therapy.

Main Methods:

• A prospective study involving 28 consecutive rectal cancer patients.
• Preoperative thin-section MR imaging (0.6 x 0.6 mm in-plane resolution) was performed.
• Comparison of MR-based tumor staging and extramural invasion depth with histopathologic findings from resection specimens.

Main Results:

• MR imaging correctly indicated histopathologic tumor stage in all evaluable patients (n=25).
• Excellent agreement was observed between MR and histopathologic measurements of extramural tumor invasion depth (mean difference +0.13 mm).
• The mesorectal fascia and tumor relationship were clearly visualized in all cases, identifying extensive invasion in patients with positive circumferential resection margins.

Conclusions:

• Preoperative thin-section MR imaging is accurate for staging rectal cancer and assessing extramural tumor infiltration depth.
• This technique provides critical information for identifying T3 tumors.
• MR imaging aids in selecting patients who may benefit from preoperative adjuvant therapy to reduce the risk of incomplete excision.