The multiverse of mismatchness in neuroradiology for stroke assessment: a narrative review

Mismatch imaging has become a key concept in neuroradiology, offering valuable insights into the pathophysiology of cerebrovascular and oncological conditions. By highlighting discrepancies between neuroimaging parameters, mismatch-based algorithms have revolutionized diagnosis, treatment planning, and patient prognosis. In stroke-related clinical scenarios, the mismatch concept is now essential in identifying candidates for thrombolysis or estimating the stroke onset time. However, the increasing use of mismatched terminology can lead to confusion, particularly when the exact mismatch target or required imaging modalities are unclear. Concerning stroke evaluation, there is a wide range of computed tomography perfusion (CT) maps and MRI sequences that are currently used for describing and determining mismatch concepts. Apart from the well-known penumbra-core mismatch related to CTP, the combination of features of different MRI sequences has provided a wide range of mismatch scenarios, such as perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) mismatch, magnetic resonance angiography (MRA)/DWI mismatch, susceptibility-weighted imaging (SWI)/DWI mismatch, or the DWI/FLAIR mismatch. Each one of these mismatches has its own clinical and physiopathological meaning, ranging from time-to-onset stroke estimation to selection of endovascular procedures. This article explores the different mismatch concepts used for stroke evaluation, including other related, less-used ones, focusing on their underlying physiopathology, clinical relevance, and supporting scientific evidence, all from a practical and educational perspective. KEY POINTS: Question Mismatch imaging offers transformative diagnostic insights in stroke, yet consistent definitions and standardized methodologies are essential to fully realize its clinical potential. Findings Our study reviews mismatch paradigms, outlines their pathophysiological basis, and compares clinical implications, highlighting critical limitations and the need for standardized imaging methodologies. Clinical relevance Standardizing mismatch imaging enhances diagnostic accuracy, optimizes patient selection for therapies, and improves prognostic assessment, ultimately enabling more consistent and reliable clinical decision-making in stroke.