Perfusion as a biomarker of brain dysfunction in dementia (AD, DLB, FTD/PPA, PDD): comparison of CT, MRI (ASL/DSC/DCE), SPECT, and PET with interpretive pitfalls - a narrative review.

Authors

Katarzyna Sklinda, Jan Bocianski, Tadeusz Budlewski, Malgorzata Kobylecka, Malgorzata Dorobek, Andrzej Gorecki, Bartosz Mruk, Michal Błaszczak, Jerzy Walecki

Published in

Acta neurologica Belgica. Jul 29, 2026. Epub Jul 29, 2026.

Abstract

The term 'brain perfusion' is applied in clinical practice to a family of neuroimaging techniques that measure, in reality, quite different physiological quantities in the brain circulation. CT perfusion (CTP) and DSC-MRI track a contrast bolus to derive semi-quantitative haemodynamic parameters. ASL-MRI estimates cerebral blood flow (CBF) without contrast, but the result is sensitive to arterial transit time, haematocrit, and the patient's haemodynamic state on the day of the scan. DCE-MRI quantifies blood-brain barrier (BBB) permeability, a property of the neurovascular unit rather than a flow measurement. Perfusion SPECT provides a relative, normalisation-dependent CBF map that is distorted by cortical atrophy. [¹⁸F]FDG-PET reflects synaptic glucose metabolism, but not blood flow. Because these techniques answer different physiological questions, their results are not interchangeable, and applying a threshold or pattern derived from one modality to interpret another is methodologically unsound - yet this conflation occurs with regularity in clinical practice. This narrative review synthesises the clinical applications, diagnostic performance, and interpretive pitfalls of each technique in Alzheimer's disease (AD)/mild cognitive impairment (MCI-AD), dementia with Lewy bodies (DLB)/Parkinson's disease dementia (PDD), frontotemporal dementia (FTD)/primary progressive aphasia (PPA), and mixed dementia with vascular pathology. Recognised limitations include the narrative study design and the small number of head-to-head multi-modal studies in pathologically confirmed cohorts. A comparative table and practical minimum reporting elements are provided.

PMID:
42525357
Bibliographic data and abstract were imported from PubMed on 29 Jul 2026.

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