3He-MRI in follow-up of lung transplant recipients

The aim of this study was to evaluate the possible contribution of He-3-MRI to detect obliterative bronchiolitis (OB) in the follow-up of lung transplant recipients. Nine single- and double-lung transplanted patients were studied by an initial and a follow-up He-3-MRI study. Images were evaluated subjectively by estimation of ventilation defect area and quantitatively by individually adapted threshold segmentation and subsequent calculation of ventilated lung volume. Bronchiolitis obliterans syndrome (BOS) was diagnosed using pulmonary function tests. At He-3-MRI, OB was suspected if ventilated lung volume had decreased by 10% or more at the follow-up MRI study compared with the initial study. General accordance between pulmonary function testing and He-3-MRI was good, although subjective evaluation of He-3-MRI underestimated improvement in ventilation as obtained by pulmonary function tests. The He-3-MRI indicated OB in 6 cases. According to pulmonary function tests, BOS was diagnosed in 5 cases. All diagnoses of BOS were also detected by He-3-MRI. In 2 of these 5 cases, He-3-MRI indicated OB earlier than pulmonary function tests. The results support the hypothesis that He-3-MRI may be sensitive for early detection of OB and emphasize the need for larger prospective follow-up studies.