Automatic image processing pipeline for tracking longitudinal vessel changes in magnetic resonance angiography

Background: Cerebral vessel diameter changes objectively and automatically derived from longitudinal magnetic resonance angiography (MRA) facilitate quantification of vessel changes and further modeling.

Purpose: To characterize longitudinal changes in intracranial vessel diameter using time-of-flight (TOF) MRA.

Study type: Retrospective longitudinal study.

Subject population: IN all, 112 pediatric patients, aged 9.96 ± 4.59 years, with craniopharyngioma from 2006-2011 scanned annually.

Field strength/sequence: 1.5T and 3T TOF MRA.

Statistical tests: Chi-square and Wilcoxon-Mann-Whitney tests.

Assessment: Manual measurements using interventional angiography was established as a reference standard for diameter measurements. Constant and linear quantile regression with absolute difference, percentage difference, and relative difference was used for outlier detection.

Results: Major vessels surrounding the circle of Willis were successfully segmented except for posterior communicating arteries, mostly due to disease-related hypoplasia. Diameter measurements were calculated at 1-mm segments with a median computed vessel diameter of 1.25 mm. Diameter distortion due to registration was within 0.04 mm for 99% of vessel segments. Outlier detection using quantile regression detected less than 4.34% as being outliers. Outliers were more frequent in smaller vessels and proximity to bifurcations (P < 0.001).

Data conclusion: Using the proposed method, objective changes in vessel diameter can be acquired noninvasively from routine longitudinal imaging. High-throughput analyses of imaging-derived vascular trees combined with clinical and treatment parameters will allow rigorous modeling of vessel diameter changes.

Level of evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1063-1074.