[Regional pulmonary function by 133Xe gas and 99mTc-MAA in 11 cases with lymphangiomyomatosis (LAM)]

The evaluation of the regional distribution of ventilation and perfusion was performed by 133Xe gas and 99mTc-MAA in 11 patients with LAM. We divided the lung images into six lung regions, the upper, middle, and lower lung fields of the left and right lungs, and classified the ventilation distribution pattern as one of three types according to the washout time. Prolongation of mean transit time (MTT) predominantly in the lower lung field was classified as type a, predominantly in the middle and upper lung fields as type b, and diffuse prolongation of MTT throughout the lung as type c. The classification included 16 cases of type b, four of type a, and two of type c. The 133Xe washout was predominantly delayed in the middle and upper lung fields in 73% of LAM cases. Pulmonary perfusion was reduced in the middle lung field and relatively increased in the lower lung field in comparison with healthy controls. A follow-up study of 133Xe gas lung scan was performed in three cases of type b. All the cases deteriorated and presented obstructive and restrictive disturbances without changes in the distribution pattern. These findings suggested that the washout type did not change with the progress of the stage of the disease.