Investigation for the development of the method of evaluating regional lung function in the upright position using vertically opened MR system.

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To determine the postural difference of diaphragmatic motion between the sitting and supine position, ten healthy men were examined using a vertically open 0.5-T MR system and an original sitting chair device and a special surface coil. Forty sequential MR images were obtained both in the sitting and supine positions during 2-5 respiratory cycles. The diaphragmatic excursions (D.E.) were measured on 3 diaphragmatic points of 6 sagittal planes for both positions. The difference of D.E.between the anterior and posterior parts of the diaphragm were also determined. D.E.in the supine position was significantly greater than that in the sitting position at 16 of the 18 points. In 5 of the 6 sagittal planes, the difference of DE between posterior and anterior points was significantly larger in the supine position than in the sitting position.In the preoperative lung cancer patients, D.E.in the supine position was significantly (p<0.5) greater than in the sitting position at 10 of the 12 points. D.E.in the postoperative lung was significantly (p<0.5) smaller than that in the pre-operative state at 5 of the 6 points(supine) and at 4 of the 6 points(sitting). In the patients with phrenic nerve paralysis, D.E.was significantly greater(p<0.5) in the sitting position at 5 of the 6 points. In addition, the decrease of diaphragmatic motion in patients with pulmonary emphysema was also demonstrated in both supine and sitting positions.MR imaging in the sitting position may provide the additional information about the mechanism of abnormal diaphragmatic motion caused by various diseases.