Integrating Contrast-Enhanced Dark-Light-Dark Sign and MRI Features for Rectal Cancer Lymph Node Diagnosis.

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Accurate preoperative diagnosis of lymph node metastasis (LNM) in rectal cancer is crucial for guiding treatment.
• Current diagnostic methods face challenges in reliably detecting LNM.

Purpose of the Study:

• To develop and validate an enhanced MRI model for predicting pathologic LNM (pLNM) in rectal cancer.
• To incorporate the dark-light-dark sign, tumor features, and ESGAR criteria into the enhanced MRI model.
• To compare the efficacy of the enhanced model against nonenhanced MRI, ESGAR criteria alone, and lymph node short-axis diameter.

Main Methods:

• A retrospective, two-center study involving patients with rectal cancer who underwent primary surgery.
• Development of enhanced and plain MRI models using logistic regression.
• Definition of the dark-light-dark sign: inner hypointense tumor, intermediate hyperintense rim, outer hypointense muscularis propria.
• Comparison of diagnostic performance using receiver operating characteristic curves.

Main Results:

• The enhanced MRI model achieved areas under the receiver operating characteristic curve (AUCs) of 0.89 (training set) and 0.83 (external test set).
• The enhanced model significantly outperformed lymph node short-axis diameter, ESGAR criteria alone, and the nonenhanced model (P < .001).
• Superior performance was noted in subgroups with lymph node short-axis diameters < 5 mm and pathologic T2 stage tumors.

Conclusions:

• Integrating tumor characteristics, particularly the dark-light-dark sign, with ESGAR status enhances preoperative LNM diagnosis in rectal cancer.
• The enhanced MRI model shows improved accuracy, especially for patients with small lymph nodes (< 5 mm) or T2 stage tumors.
• This advanced MRI approach offers better preoperative LNM prediction to guide clinical management.