Thermal-signature equivalence of breast tumors with heterogeneous perfusion in a modified Pennes bioheat model

TL;DR

This study uses a modified Pennes bioheat model to analyze how different internal tumor perfusion patterns affect surface temperature signatures in breast thermography, revealing limitations in distinguishing internal heterogeneity.

Contribution

It introduces a profile-distance framework to quantify when internal perfusion differences are detectable at the surface in breast thermography.

Findings

Surface temperature signatures are strongly smoothed by heat diffusion.

Tumor depth decreases surface distinguishability of perfusion patterns.

Increasing tumor size improves the ability to differentiate internal perfusion heterogeneity.

Abstract

Breast thermography provides a noninvasive and contact-free method for observing tumor-associated thermal anomalies. However, the extent to which surface temperature patterns reflect the internal physiology of a tumor remains an open question. In this study, we investigate a modified Pennes bioheat model for multilayer breast tissue containing a finite-sized tumor with spatially heterogeneous intratumoral perfusion. Rather than focusing solely on the internal temperature field, we examine how different perfusion patterns are projected onto thermal signatures at the breast surface. We introduce a profile-distance-based framework of thermal-signature equivalence to quantify when different intratumoral perfusion structures remain distinguishable at the surface and when they become effectively indistinguishable. The results show that uniform, rim-enhanced, necrotic-core, and anisotropic perfusion patterns can produce clearly different internal temperature distributions, but these differences are strongly smoothed by heat diffusion and thermal screening before reaching the surface. Tumor depth reduces the distinguishability of surface signatures, whereas increasing tumor size enhances it. These findings highlight a fundamental limitation of static breast thermography: a thermal anomaly detected at the surface does not necessarily guarantee a unique identification of intratumoral perfusion heterogeneity.