Mapping the Intratumoral and Peritumoral Microenvironment: Multilayered Shell ADC Analysis and Its Association with...

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Accurate assessment of invasive breast cancer aggressiveness is crucial for treatment planning.
• Multiparametric MRI offers potential for non-invasive biological marker evaluation.
• Understanding the peritumoral microenvironment's role in tumor progression is key.

Purpose of the Study:

• To explore associations between intratumoral and peritumoral apparent diffusion coefficient (ADC) measurements and biological markers in invasive breast cancer.
• To evaluate a novel peritumoral analysis approach using a multilayered concentric shell model.
• To correlate ADC ratios with histologic grade, Ki-67 index, lymphovascular invasion (LVI), and axillary metastasis.

Main Methods:

• Retrospective analysis of 68 invasive breast cancer patients using 1.5 T breast MRI.
• Volumetric tumor segmentation followed by peritumoral analysis using a segmentation-based, improved multilayered concentric shell model (0-2, 2-5, 5-10 mm).
• Calculation of normalized ADC (rADC) and intratumoral-to-peritumoral ADC ratios, correlated with biological parameters.

Main Results:

• Lower intratumoral ADC and intratumoral-to-peritumoral ADC ratios correlated significantly with higher histologic grade, increased Ki-67, and axillary metastasis (p < 0.05).
• The 0-2 mm peritumoral shell showed the strongest association with LVI and nodal involvement.
• A distance-dependent decrease in effect size was observed in more distal peritumoral layers.

Conclusions:

• The novel multilayered shell model effectively characterizes the peritumoral microenvironment's biological gradient.
• Intratumoral-to-peritumoral ADC ratios in the immediate 2 mm zone may serve as complementary imaging markers for tumor aggressiveness.
• These ADC-derived parameters show potential for preoperative risk stratification in a multiparametric breast cancer imaging framework.