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. 2023 Mar;57(3):727-737.
doi: 10.1002/jmri.28343. Epub 2022 Jul 9.

Quantitative Assessment of Regional Pulmonary Transit Times in Pulmonary Hypertension

Jackson E Moore  1   2 , John W Cerne  1 , Ashitha Pathrose  1 , Manik Veer  1 , Roberto Sarnari  1 , Ann Ragin  1 , James C Carr  1 , Michael Markl  1   2
Affiliations

Quantitative Assessment of Regional Pulmonary Transit Times in Pulmonary Hypertension

Jackson E Moore et al. J Magn Reson Imaging. 2023 Mar.

Abstract

Background: Pulmonary hypertension (PH) contributes to restricted flow through the pulmonary circulation characterized by elevated mean pulmonary artery pressure acquired from invasive right heart catheterization (RHC). MRI may provide a noninvasive alternative for diagnosis and characterization of PH.

Purpose: To characterize PH via quantification of regional pulmonary transit times (rPTT).

Study type: Retrospective.

Population: A total of 43 patients (58% female); 24 controls (33% female). RHC-confirmed patients classified as World Health Organization (WHO) subgroups 1-4.

Field strength/sequence: A 1.5 T/time-resolved contrast-enhanced MR Angiography (CE-MRA).

Assessment: CE-MRA data volumes were combined into a 4D matrix (3D resolution + time). Contrast agent arrival time was defined as the peak in the signal-intensity curve generated for each voxel. Average arrival times within a vessel region of interest (ROI) were normalized to the main pulmonary artery ROI (t0 ) for eight regions to define rPTT for all subjects. Subgroup analysis included grouping the four arterial and four venous regions. Intraclass correlation analysis completed for reproducibility.

Statistical tests: Analysis of covariance with age as covariate. A priori Student's t-tests or Wilcoxon rank-sum test; α = 0.05. Results compared to controls unless noted. Significant without listing P value. ICC ran as two-way absolute agreement model with two observers.

Results: PH patients demonstrated elevated rPTT in all vascular regions; average rPTT increase in arterial and venous branches was 0.85 ± 0.15 seconds (47.7%) and 1.0 ± 0.18 seconds (16.9%), respectively. Arterial rPTT was increased for all WHO subgroups; venous regions were elevated for subgroups 2 and 4 (group 1, P = 0.86; group 3, P = 0.32). No significant rPTT differences were found between subgroups (P = 0.094-0.94). Individual vessel ICC values ranged from 0.58 to 0.97.

Data conclusion: Noninvasive assessment of PH using standard-of-care time-resolved CE-MRA can detect increased rPTT in PH patients of varying phenotypes compared to controls.

Level of evidence: 1 TECHNICAL EFFICACY: Stage 3.

Keywords: MR angiography; pulmonary hypertension; pulmonary transit time; thoracic; time-resolved contrast-enhanced MRA.

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References

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