Novel Magnetic Resonance Imaging for Assessment of Bronchial Stenosis in Lung Transplant Recipients

Abstract

Bronchial stenosis in lung transplant recipients is a common disorder that adversely affects clinical outcomes. It is evaluated by spirometry, CT scan and bronchoscopy with significant limitations. We hypothesize that magnetic resonance imaging (MRI) employing both ultrashort echo time (UTE) scans and hyperpolarized (HP) 129Xe gas can offer structural and functional assessment of bronchial stenosis seen after lung transplantation. Six patients with lung transplantation-related bronchial stenosis underwent HP 129Xe MRI and UTE MRI. Three patients subsequently underwent airway stent placement and had repeated MRI at 4 week follow up. HP 129Xe MRI depicted decreased ventilation distal to the stenotic airway. After airway stent placement, MRI showed that low-ventilation regions had decreased (35% vs. 27.6%, P =0.006) and normal-ventilation regions increased (17.9% vs 27.6%, P = 0.04) in the stented lung. Improved gas transfer was also seen on 129Xe MRI. There was a good correlation between UTE MRI and independent bronchoscopic airway diameter assessment (Pearson correlation coefficient = 0.92). This pilot study shows that UTE and HP 129Xe MRI are feasible in patients with bronchial stenosis related to lung transplantation, and may provide structural and functional airway assessment to guide treatment. These conclusions need to be confirmed by larger studies.

Multireader Determination of Clinically Significant Obstruction Using Hyperpolarized 129Xe–Ventilation MRI

“…In this scenario, HP 129 Xe MR imaging seems a promising application to fill this gap. In particular, HP 129 Xe MRI may be idealy suited to evaluate regional interventions like bronchial stents, valves and bronchial thermoplasty (24).…”

In vivo methods and applications of xenon-129 magnetic resonance

“…They have the potential to detect lung abnormalities earlier than spirometry [168] , [169] and structural imaging [167] , [290] , allowing early intervention/therapy to mitigate further damage. Moreover, the sensitivity of 129 Xe ventilation imaging to therapy response [158] , [163] , [171] , [172] coupled with its high repeatability should enable clinical trials of novel therapeutics with small patient numbers, as has been demonstrated with 3 He ventilation MRI [291] , [292] . Crucially, the lack of ionising radiation associated with 129 Xe MR is important when considering repeated imaging, and allows safe longitudinal monitoring of disease progression and studies of therapeutic response.…”

“…In addition to early sensitivity, the non-ionising nature of 129 Xe ventilation MRI, coupled with its safety and tolerability in adults and children [21] , [22] , [23] , make it well suited for longitudinal follow-up post-intervention scans. 129 Xe ventilation MRI response to therapy has been demonstrated in: patients with asthma after bronchodilator inhalation [163] and bronchial thermoplasty [312] , children with CF after pulmonary exacerbation and subsequent treatment with intravenous antibiotics [170] , patients with CF after acute maximal exercise [313] , patients with bronchial stenosis after airway stent placement [171] , and a patient with adenocarcinoma after radiotherapy [172] . In a study monitoring response to antibiotics in children with CF, 129 Xe VDP showed the largest relative improvement of all outcome measures [170] , and 129 Xe ventilation MRI has been shown to be a sensitive method to assess longitudinal lung disease in children and adults with CF [158] , [314] .…”

Monitoring practices of chronic lung allograft dysfunction in pediatric lung transplantation

“…Advances in MR technology nowadays provide excellent parenchymal images sometimes rivaling CT, with recent studies showing that MRI can be used for CLAD detection and even differentiating between its stages 12,13 . It is also worth noting that uses beyond CLAD detection have been documented in LTx, namely assessing for bronchial or vascular stenosis 22 . Although none of the surveyed pediatric programs use MRI clinically for CLAD surveillance and detection, it is interesting that the majority of respondents agreed that there may be some utility in the future, probably due to an increasing interest in noninvasive and radiation‐free modalities, particularly in small children.…”