Non‐Contrast‐Enhanced Functional Lung MRI to Evaluate Treatment Response of Allergic Bronchopulmonary Aspergillosis in Patients With Cystic Fibrosis: A Pilot Study

Abstract

BackgroundAllergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) patients is associated with severe lung damage and requires specific therapeutic management. Repeated imaging is recommended to both diagnose and follow‐up response to treatment of ABPA in CF. However, high risk of cumulative radiation exposure requires evaluation of free‐radiation techniques in the follow‐up of CF patients with ABPA.PurposeTo evaluate whether Fourier decomposition (FD) functional lung MRI can detect response to treatment of ABPA in CF patients.Study TypeRetrospective longitudinal.PopulationTwelve patients (7M, median‐age:14 years) with CF and ABPA with pre‐ and post‐treatment MRI.Field Strength/Sequence2D‐balanced‐steady‐state free‐precession (bSSFP) sequence with FD at 1.5T.AssessmentVentilation‐weighted (V) and perfusion‐weighted (Q) maps were obtained after FD processing of 2D‐coronal bSSFP time‐resolved images acquired before and 3–9 months after treatment. Defects extent was assessed on the functional maps using a qualitative semi‐quantitative score (0 = absence/negligible, 1 = <50%, 2 = >50%). Mean and coefficient of variation (CV) of the ventilation signal‐intensity (VSI) and the perfusion signal‐intensity (QSI) were calculated. Measurements were performed independently by three readers and averaged. Inter‐reader reproducibility of the measurements was assessed. Pulmonary function tests (PFTs) were performed within 1 week of both MRI studies as markers of the airflow‐limitation severity.Statistical TestsComparisons of medians were performed using the paired Wilcoxon‐test. Reproducibility was assessed using intraclass correlation coefficient (ICC). Correlations between MRI and PFT parameters were assessed using the Spearman‐test (rho correlation‐coefficient). A P‐value <0.05 was considered as significant.ResultsDefects extent on both V and Q maps showed a significant reduction after ABPA treatment (4.25 vs. 1.92 for V‐defect‐score and 5 vs. 2.75 for Q‐defect‐score). VSI_mean was significantly increased after treatment (280 vs. 167). Qualitative analyses reproducibility showed an ICC > 0.90, while the ICCs of the quantitative measurements was almost perfect (>0.99). Changes in VSI_cv and QSI_cv before and after treatment correlated inversely with changes of FEV1%p (rho = −0.68 for both).Data ConclusionNon‐contrast‐enhanced FD lung MRI has potential to reproducibly assess response to treatment of ABPA in CF patients and correlates with PFT obstructive parameters.Evidence Level4Technical EfficacyStage 3

Revised ISHAM-ABPA working group clinical practice guidelines for diagnosing, classifying and treating allergic bronchopulmonary aspergillosis/mycoses

“…A chest radiograph, not a chest CT, should be used during follow-up. While magnetic resonance imaging is radiation-free, the DECG did not routinely recommend its use as it has no significant diagnostic advantage over the readily available chest CT [ 94 – 96 ].…”

Radiological Diagnosis of Pulmonary Aspergillosis

“…This technique has been shown to generate ventilation-weighted and perfusion-weighted maps, without any contrast product injection or ventilation. 49 The technique has been validated against hyperpolarized 3He and dynamic contrast-enhanced MRI.…”

“…10) proved useful for monitoring treatment of ABPA in CF patients. 49 There are little data in the current literature about the use of MRI in the context of ABPA in people with asthma without CF. In children, a recent report found a good performance of MRI to assess structural abnormalities such as bronchiectasis and infiltrate.…”