Validation of Automated Perfusion‐Weighted Phase‐Resolved Functional Lung (PREFUL)‐MRI in Patients With Pulmonary Diseases

Abstract

BackgroundPerfusion‐weighted (Qw) noncontrast‐enhanced proton lung MRI is a promising technique for assessment of pulmonary perfusion, but still requires validation.PurposeTo improve perfusion‐weighted phase‐resolved functional lung (PREFUL)‐MRI, to validate PREFUL with perfusion single photon emission computed tomography (SPECT) as a gold standard, and to compare PREFUL with dynamic contrast‐enhanced (DCE)‐MRI as a reference.Study TypeRetrospective.PopulationTwenty patients with chronic obstructive pulmonary disease (COPD), 14 patients with cystic fibrosis (CF), and 21 patients with chronic thromboembolic pulmonary hypertension (CTEPH) were included.Field Strength/SequenceFor PREFUL‐MRI, a spoiled gradient echo sequence and for DCE‐MRI a 3D time‐resolved angiography with stochastic trajectories sequence were used at 1.5T.AssessmentPREFUL‐MRI coronal slices were acquired in free‐breathing. DCE‐MRI was performed in breath‐hold with injection of 0.03 mmol/kg bodyweight of gadoteric acid at a rate of 4 cc/s. Perfusion SPECT images were obtained for six CTEPH patients. Images were coregistered. An algorithm to define the appropriate PREFUL perfusion phase was developed using perfusion SPECT data. Perfusion defect percentages (QDP) and Qw‐values were calculated for all methods. For PREFUL quantitative perfusion values (PREFULQ) and for DCE pulmonary blood flow (PBF) was calculated.Statistical TestsObtained parameters were assessed using Pearson correlation and Bland–Altman analysis.ResultsQw‐SPECT correlated with Qw‐DCE (r = 0.50, P < 0.01) and Qw‐PREFUL (r = 0.47, P < 0.01). Spatial overlap of QDP maps showed an agreement ≥67.7% comparing SPECT and DCE, ≥64.1% for SPECT and PREFUL, and ≥60.2% comparing DCE and PREFUL. Significant correlations of Qw‐PREFUL and Qw‐DCE were found (COPD: r = 0.79, P < 0.01; CF: r = 0.77, P < 0.01; CTEPH: r = 0.73, P < 0.01). PREFULQ/PBF correlations were similar/lower (CF, CTEPH: P > 0.12; COPD: P < 0.01) compared to Qw‐PREFUL/DCE correlations. PREFULQ‐values were higher/similar compared to PBF‐values (COPD, CF: P < 0.01; CTEPH: P = 0.026).Data ConclusionThe automated PREFUL algorithm may allow for noncontrast‐enhanced pulmonary perfusion assessment in COPD, CF, and CTEPH patients comparable to DCE‐MRI.Level of Evidence 3Technical Efficacy Stage 2J. Magn. Reson. Imaging 2020;52:103–114.

Analysis of different image-registration algorithms for Fourier decomposition MRI in functional lung imaging

“…Various image registration algorithms for pulmonary FD-MRI have been described in the existing literature (2,3,9,11,12,14,19,28). In the current study, the performance of three different image-registration algorithms for FD-MRI was analyzed.…”

“…In the present study, symmetric-diffeomorphic registration was performed by ANTs with following settings: image dimensions = 2; update field variance in voxel space (weight) = 1; metric radius = 9; number of iterations per level = 50 × 25 × 25; smoothing = Gaussian ][|3,1. Several studies dealing with pulmonary FD-MRI have utilized ANTs for image registration (11–16).…”

Repeatability of dynamic 3D phase‐resolved functional lung (PREFUL) ventilation MR Imaging in patients with chronic obstructive pulmonary disease and healthy volunteers

“…Repeatability and validation studies of 2D PREFUL to reference standards have been performed to facilitate the use of 2D PREFUL in clinical routine. [20][21][22][23] Recently, 3D PREFUL has been developed to assess dynamic ventilation of the whole lung in an 8-minute acquisition, and the preliminary feasibility results in 16 study participants including patients with asthma, CF, and COPD have been presented. 24 However, the repeatability of ventilation parameters derived from 3D PREFUL, which is necessary to know prior to its use in clinical settings, has not been assessed.…”

Proton MRI of the Lung: How to Tame Scarce Protons and Fast Signal Decay

“…Ventilation 75 was validated in 12 patients with COPD and 14 patients with bronchiectasis with He‐3 MRI, CT, and PFT, 76 in 16 patients with asthma with He‐3 and PFT, 77 in 27 COPD patients with F‐19, 78 and in 20 CF patients and 20 healthy volunteers with PFT 79 . Free‐breathing MRI ventilation markers were found to correlate with PFT and ventilation defects agree with hyperpolarized MRI and F‐19.…”

“…A quantification method, borrowed from arterial spin labeling (ASL) imaging, was introduced, but further validation is pending 74 . A recent study demonstrated a good correlation to single photon emission computed tomography (SPECT) in addition to DCE in CTEPH patients 75 . [Correction added on March 18, 2020, after first online publication: The missing reference number was added in the preceding sentence.…”