MRI‐derived regional flow‐volume loop parameters detect early‐stage chronic lung allograft dysfunction

Abstract

Background Chronic lung allograft dysfunction (CLAD) is a major cause for the low long‐term survival rates after lung transplantation (LTx). Early detection of CLAD may enable providing medical treatment before a nonreversible graft dysfunction has occurred. MRI is advantageous to pulmonary function testing (PFT) in the ability to assess regional function changes, and thus have the potential in detecting very early stages of CLAD before changes in global forced expiratory volume during the first second (FEV1%) occur. Purpose To examine whether early stages of CLAD (diagnosed based on PFT values) could also be detected using MRI‐derived parameters of regional flow‐volume dynamics. Study Type Retrospective. Population 62 lung transplantation recipients were included in the study, 29 of which had been diagnosed with CLAD at various stages. Field Strength/Sequence MRI datasets were acquired with a 1.5T Siemens scanner using a spoiled gradient echo sequence. Assessment MRI datasets were retrospectively preprocessed and analyzed by a blinded radiologist according to the phase resolved functional lung MRI (PREFUL‐MRI) approach, resulting in fractional ventilation (FV) maps and regional flow‐volume loops (rFVL). FV‐ and rFVL‐based parameters of regional lung ventilation were estimated. Statistical Tests Differences between groups were compared by Mann–Whitney U‐test with a Bonferroni correction for multiple comparisons (n = 2). Results rFVL‐CC‐based parameters discriminated significantly between the presence or absence of CLAD (P < 0.003). Data Conclusion Using the contrast media‐free PREFUL‐MRI technique, parameters of ventilation dynamics and its regional heterogeneity were shown to be sensitive for the detection of early CLAD stages. Level of Evidence: 3 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2019;50:1873–1882.

3D phase‐resolved functional lung ventilation MR imaging in healthy volunteers and patients with chronic pulmonary disease

“…The agreement of the static ventilation parameter RVent between 2D and 3D is in correspondence with previously reported results in 6 healthy volunteers 18 . The potential of FVL analysis using 2D PREFUL has been demonstrated in 62 lung transplantation recipients 22 . To our knowledge, 3D PREFUL FVL have never been demonstrated in patients previously, and this is the first study to compare FVL‐derived parameters between 2D and 3D technique in healthy volunteers and patients with chronic pulmonary diseases.…”

“…For VDP RVent , voxels were identified as ventilation defect if the RVent value was below the 90th percentile of all RVent values, multiplied by a factor of 0.4, based on area under curve analysis of previously acquired 2D PREFUL data. For VDP CC , voxels with CC values below 0.9 were considered as voxels with ventilation defect 22 …”

Repeatability of Phase‐Resolved Functional Lung (PREFUL)‐MRI Ventilation and Perfusion Parameters in Healthy Subjects and COPD Patients

“…The regional ventilation (RVent) was calculated for each phase during normal tidal free breathing 20 . Also, a flow volume loop was created for every voxel inside the lung parenchyma and further correlated to a healthy reference flow volume loop by means of cross‐correlation, which resulted in a cross‐correlation (ccVent) map 27 . A healthy reference flow volume loop was defined as an average of a flow volume loop in a lung parenchyma region with high RVent values between the 75th and 95th quantile.…”

The current status and further prospects for lung magnetic resonance imaging in pediatric radiology

“…28) [4,[34][35][36], a further development of Fourier decomposition MRI [37], have been shown recently. This technique holds the promise to mature into a patient-friendly MRI spirometry test, with novel clinically relevant information to guide clinical decisionmaking and improve patient monitoring [38][39][40]. PREFUL MRI typically uses standard 1.5-T or 3-T MRI equipment and is based on a routine gradient echo fast low-angle shot (FLASH) sequence.…”