Evaluation of conductivity tensor image along the perivascular space in the brains of patients with cognitive impairments

Background The diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) index has been proposed as an imaging marker of impaired perivascular water transport across the Alzheimer’s disease (AD) continuum. Whether a conductivity-based ALPS derived from conductivity tensor imaging (CTI) provides a distinct physiological perspective remains to be explored. This work introduces the CTI-ALPS index. The purpose of this study was (1) to introduce the CTI-ALPS index and (2) to evaluate both the CTI-ALPS and DTI-ALPS indices in cognitively normal (CN) older adults, amnestic mild cognitive impairment (aMCI), and mild-to-moderate AD. Methods In this prospective cross-sectional study, 110 participants (CN, n = 30; aMCI, n = 52; AD, n = 28) underwent diffusion MRI ( b = 800 and 2,000 s/mm 2 ) and magnetic resonance electrical property tomography (MREPT)to calculate DTI-ALPS and CTI-ALPS, respectively. Diagnostic performance and correlation with cognitive function were evaluated. Results CTI-ALPS showed lower in AD but did not differ significantly across groups and demonstrated weaker associations with Mini-Mental State Examination (MMSE) scores. In age-adjusted ROC analyses for differentiating AD from CN, CTI-ALPS achieved modest discrimination, whereas DTI-ALPS provided slightly higher diagnostic performance. Conclusion CTI-ALPS demonstrated a non-significant trend towards a reduction in AD and modest diagnostic utility, with weaker clinical associations than DTI-ALPS in this cohort. As an initial exploratory study, conductivity-based ALPS may serve as a distinct physical contrast reflecting ionic physiological perivascular marker, alongside diffusion-based measures, and warrants further validation with larger, age-matched datasets and reproducibility-focused designs.