Functional lung MRI for regional monitoring of patients with cystic fibrosis

<div><p>Purpose</p><p>To test quantitative functional lung MRI techniques in young adults with cystic fibrosis (CF) compared to healthy volunteers and to monitor immediate treatment effects of a single inhalation of hypertonic saline in comparison to clinical routine pulmonary function tests.</p><p>Materials and methods</p><p>Sixteen clinically stable CF patients and 12 healthy volunteers prospectively underwent two functional lung MRI scans and pulmonary function tests before and 2h after a single treatment of inhaled hypertonic saline or without any treatment. MRI-derived oxygen enhanced T₁ relaxation measurements, fractional ventilation, first-pass perfusion parameters and a morpho-functional CF-MRI score were acquired.</p><p>Results</p><p>Compared to healthy controls functional lung MRI detected and quantified significantly increased ventilation heterogeneity in CF patients. Regional functional lung MRI measures of ventilation and perfusion as well as the CF-MRI score and pulmonary function tests could not detect a significant treatment effect two hours after a single treatment with hypertonic saline in young adults with CF (p>0.05).</p><p>Conclusion</p><p>This study shows the feasibility of functional lung MRI as a non-invasive, radiation-free tool for monitoring patients with CF.</p></div

Comparison of CF patients to healthy volunteers.

<p>Comparison of CF patients to healthy volunteers.</p

Study protocol.

<p>Pulmonary function testing (spirometry and multiple breath nitrogen washout (MBW)) were performed 60 to 90 minutes prior to the pre treatment scan / 1^st scan. MRI was performed as follows: first, morphological images were assessed followed by phase contrast angiography (PCA) in the ascending aorta. Afterwards T1 mapping breathing room air and again after six minutes of 100% oxygen wash-in time was acquired. Regional Fractional Lung Ventilation MRI (FV) was then acquired under normoxic conditions. Then for assessment of pulmonary parenchymal perfusion, dynamic contrast enhanced (DCE) MRI was carried out followed by a morphological sequence post i.v. contrast. Afterwards inhalation treatment with hypertonic saline (HTS, treatment group) or no treatment (control group) was performed and the PFT (30 minutes after treatment) and MRI (2 h after treatment) were repeated. Healthy volunteers underwent one scan using the same functional lung MRI protocol, except for DCE-MRI and phase-contrast MRI.</p

Receiver operator characteristic analysis (ROC).

<p>Receiver operator characteristic (ROC) analysis with clinical diagnosis as the criterion showed the ability of functional MRI to discriminate young adults with CF from healthy volunteers. A: Room air T1 (cut point: 1200 ms; area under the curve (AUC) 0.89); B: Quartile coefficient of dispersion of fractional ventilation (cut point 0.351; AUC 0.89).</p

Patient cohort (CONSORT flow chart).

<p>Please note: For the control group a second visit of 4 patients of the treatment group were included resulting in 20 visits of 16 patients.</p

Receiver operating characteristics analysis.

<p>Receiver operating characteristics analysis.</p

Subject demographics.

<p>Subject demographics.</p

Comparison of a healthy volunteer and a CF patient.

<p>First row: healthy volunteer, second row: pre treatment, third row: post treatment; A: room air T1 map, oxygen enhanced T1 map and delta T1 map; B: Calculated perfusion map by using a pixel-by-pixel deconvolution analysis; C: Fractional ventilation map. Regarding the healthy volunteer values are homogeneously distributed throughout the whole lungs. In comparison to that in the CF patient values are lower and more heterogeneous distributed. Hypoventilated and hypoperfused areas can be seen in all three methods, most prominent in the right upper lobe. After treatment an improvement of ventilation and perfusion is not observed.</p

Incidentally discovered consolidation in the right upper lobe in a CF patient.

<p>A: T2-weighted; B: Fractional ventilation map; C: Calculated perfusion map; D: Room air T1 map; E: Oxygen enhanced T1 map; F: Delta T1 map.</p