(3)He-MRI in follow-up of lung transplant recipients.

The aim of this study was to evaluate the possible contribution of (3)He-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 (3)He-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 (3)He-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 (3)He-MRI was good, although subjective evaluation of (3)He-MRI underestimated improvement in ventilation as obtained by pulmonary function tests. The (3)He-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 (3)He-MRI. In 2 of these 5 cases, (3)He-MRI indicated OB earlier than pulmonary function tests. The results support the hypothesis that (3)He-MRI may be sensitive for early detection of OB and emphasize the need for larger prospective follow-up studies.

Distribution of ventilation in lung transplant recipients: evaluation by dynamic 3He-MRI with lung motion correction.

RATIONALE AND OBJECTIVES: The ability of motion corrected dynamic 3He-magnetic resonance imaging (MRI) to discriminate distributional patterns of inhaled hyperpolarized 3He between different groups of lung transplant recipients was evaluated. METHODS: An ultrafast low-angle shot 2D sequence (temporal resolution 128 ms) was used for ventilation 3He-MRI of 11 single and 6 double lung transplant recipients. After digital motion correction, signal kinetics were evaluated in a tracheal and 7 pulmonary regions of interest. Results from grafts and native lungs as well as from normal and rejected grafts were compared with each other and to reference values from healthy subjects. RESULTS: In emphysema patients, median alveolar rise time, a parameter for increase of alveolar signal, was 0.28 seconds for the graft and 0.48 seconds for the native lung, in fibrosis patients its median was 0.46 seconds for the graft and 0.21 seconds for the native lung. In double lung recipients, alveolar rise time was 0.29 seconds in normal and clinically rejected grafts. CONCLUSIONS: Dynamic ventilation 3He-MRI discriminated normal lung grafts from diseased native lungs in single lung recipients. Graft rejection in double lung recipients could not be discriminated.