VENTILATION-PERFUSION RADIONUCLIDE IMAGING IN CRYPTOGENIC FIBROSING ALVEOLITIS

There is increasing interest in ventilation perfusion (V/Q) imaging in cryptogenic fibrosing alveolitis because of the data these scans prov ide on the dynamic V/Q relationships in such patients undergoing singl e lung transplantation. However, the full spectrum of V/Q abnormalitie s in this disease is poorly defined. We therefore analysed the V/Q sca ns of 45 consecutive patients with advanced cryptogenic fibrosing alve olitis being considered for single lung transplantation. Scans were cl assified according to the presence, severity and degree of matching of defects in ventilation and perfusion images and the results were comp ared with the data obtained from lung function tests. Ventilation imag es showed defects in 13 (29%) and 'washout delay' in 15 (33%) patients ; 10 (22%) patients had asymmetric distribution of ventilation with on e lung receiving >60% of total ventilation. Perfusion images showed no rmal perfusion in 8 (18%), mild defects in 18 (40%) and major defects in 19 (42%) patients. The distribution of perfusion between lungs was significantly asymmetric in 20 (45%) patients. V/Q images were matched in 15 (33%), mildly mismatched in 15 (33%) and severely mismatched in 15 (33%) patients, but the degree of V/Q mismatch did not show a rela tionship to KCO, PaO2 or A-aO2 gradient. The appearances were atypical of pulmonary embolism in eight patients. V/Q images in cryptogenic fi brosing alveolitis show a diverse range of appearances and may mimic p ulmonary embolism. V/Q imaging complements the data obtained from lung function tests and is particularly useful in defining the differentia l function of each lung which is particularly important in the assessm ent of patients for single lung transplantation.