A quality assurance protocol for reliable and reproducible multi-TI arterial spin labeling perfusion imaging in rat livers

To establish an arterial spin labeling (ASL) protocol for rat livers that improves data reliability and reproducibility for perfusion quantification.

This study used respiratory-gated, single-slice, FAIR-based ASL imaging with multiple inversion times (TI) in rat livers. Quality assurance measures included: (1) introduction of mechanical ventilation to ensure consistent respiratory cycles by controlling the respiratory rate (45 bpm), tidal volume (10 ml/kg), and inspiration: expiration ratio (I:E ratio, 1:2), (2) optimization of the trigger window for consistent trigger points, and (3) use of fit residual map and coefficient of variance as metrics to assess data quality. We compared image quality, perfusion maps, and fit residual maps between mechanically ventilated and non-ventilated animals, as well as repeated ASL measurements (session = 4 per animal) in two mechanically ventilated animals.

Perfusion measurements over multiple sessions in mechanically ventilated rats exhibited low perfusion data variability and high reproducibility both within and between liver lobes. Image quality and perfusion maps were significantly improved in mechanically ventilated animals compared to non-ventilated animals.

The implementation of mechanical ventilation and optimized quality assurance protocols enhanced the reliability and reproducibility of FAIR-based multi-TI-ASL imaging in rat livers. Our findings demonstrate these measures as a robust approach for achieving consistent liver perfusion quantification in preclinical settings.