Multimodal data fusion: integrating PET/MRI and liquid biopsy for a holistic view of cancer biology

The systemic complexity and spatiotemporal heterogeneity of cancer demand diagnostic strategies beyond single modalities. The integration of positron emission tomography/magnetic resonance imaging (PET/MRI) with liquid biopsy offers a revolutionary paradigm for a comprehensive view of tumor biology. This approach synergizes PET/MRI’s high-resolution spatial information—covering anatomical, functional, and metabolic characteristics—with the systemic, dynamic molecular data from liquid biopsy, particularly circulating tumor DNA (ctDNA). This review systematically examines the principles of this synergy, analyzing multimodal data fusion strategies, clinical evidence, and future challenges. The central benefit of this fusion is the enhancement of clinical decision-making across the cancer care continuum: improving early diagnosis and localization, resolving spatial heterogeneity, enabling dynamic monitoring of treatment efficacy, and tracing drug resistance. Current evidence, though primarily from retrospective or proof-of-concept studies, strongly supports this potential. However, significant challenges persist in technical standardization, algorithmic development for integrating heterogeneous data, and the need for large-scale prospective validation. Propelled by advances in artificial intelligence, overcoming these hurdles will shift oncology from static diagnostics toward a new era of precision medicine, capable of dynamically mapping the entire tumor ecosystem to deliver truly individualized patient care.