Arterial flow volume measurement using signal intensity gradient versus phase contrast

Determining blood flow in major cerebral arteries is crucial for understanding cerebrovascular diseases. This study focused on comparing flow volumes derived from the signal intensity gradient (SIG) of Time-of-flight magnetic resonance angiography (TOF-MRA), referred to as SIG volume, and two-dimensional phase-contrast MR (PC-MR) and assessing their correlation in both experimental and human studies. The SIG volume of TOF-MRA could be calculated based on the concept of SIG as velocity gradient correspondingly. This research encompassed an experimental study as well as a prospective cross-sectional study involving human participants. Flow volumes were measured in four varying-sized tubes using PC-MR and TOF-MRA in the experimental study. The internal carotid and vertebral arteries were examined in relatively healthy subjects and the data were prospectively collected. Pearson’s correlation coefficients and coefficients of determination (R²) were calculated, and Bland-Altman plots were used to assess the agreement between the two methods. In the tubal experiments (n = 80), the correlation coefficient of flow volumes measured by two modalities was 0.98, with an R² of 0.96 (p < 0.001). In the human study, 50 internal carotid and 49 vertebral arteries from 25 subjects (mean age ± standard deviation: 63.3 ± 11.5 y) were examined. The coefficient for the cerebral arteries was 0.93, with an R² of 0.87 (p < 0.001). Calculated SIG volumes of TOF-MRA were highly correlated with the blood flow volume from PC-MR in both tubal experiments and human studies on extracranial cerebral arteries. This study was registered at ClinicalTrials.gov (NCT04585971, Date of Registration: 2020-10-14).