[Diffusion-weighted MR imaging in patients with rectal cancer: our initial experience]

Area of Science:

• Oncology
• Radiology
• Medical Imaging

Background:

• Accurate pre-surgical characterization of post-neoadjuvant residual tumor response in rectal cancer is crucial for treatment planning.
• Imaging techniques can guide therapeutic strategies or observation decisions in rectal cancer patients.

Purpose of the Study:

• To evaluate the role of diffusion-weighted magnetic resonance imaging (DWMR) in determining residual primary tumor (RPT) or complete pathologic response (CPR) after neoadjuvant therapy in rectal cancer (RC).
• To compare the diagnostic performance of visual and quantitative DWMR assessments against pathological anatomy as the gold standard.

Main Methods:

• Eighteen rectal cancer patients with medial/low tumors and positive lymph nodes underwent neoadjuvant treatment.
• Post-neoadjuvant DWMR was performed using visual and quantitative scales to measure apparent diffusion coefficient (ADC).
• Results were correlated with pathological anatomy findings.

Main Results:

• Pathological anatomy revealed RPT in 15 of 18 patients and CPR in 3.
• Visual DWMR detected RPT in 14/15 patients; quantitative ADC detected all RPT cases.
• Quantitative ADC detected all 3 CPR cases, while visual DWMR detected 2/3.

Conclusions:

• DWMR is a valuable tool for assessing post-neoadjuvant RPT and CPR in rectal cancer.
• Quantitative ADC assessment significantly enhances diagnostic accuracy compared to qualitative visual analysis.
• DWMR, particularly with quantitative ADC, improves the determination of treatment response in rectal cancer.