EVALUATION OF PULMONARY VENTILATION AND DIAPHRAGMATIC MOVEMENT IN IDIOPATHIC SCOLIOSIS USING RADIOAEROSOL VENTILATION SCINTIGRAPHY

Regional distribution of lung ventilation and diaphragmatic movement w ere evaluated using a noninvasive scintigraphic method in patients wit h idiopathic scoliosis. Twenty-four non-smoking patients aged 20 +/- 9 years (mean +/- S.D.), all with a right convex dorsal curve (mean Cob b's angle of 65.1 +/- 26.4 degrees), underwent lung ventilation scinti graphy after inhalation of Tc-99(m)-labelled human albumin microsphere s. The distribution of the inhaled aerosol was assessed and scored bas ed on four scintigraphic patterns, ranging from homogeneous distributi on (score = 1) to diffuse severe hypoventilation (score = 4). Diaphrag matic movement, evaluated in 11 of the 24 patients, was assessed using an index (DM-Index) computed for each hemi-diaphragm by the normaliza tion and subtraction of two digital scans obtained during maximal insp iration and expiration respectively. The left lung, situated on the co ncave side of the scoliotic curve, showed a more uneven distribution o f ventilation (scintigraphic score: 2.62 +/- 1.17 vs 1.50 +/- 1.02, P < 0.01) and a reduced hemi-diaphragm movement (DM-Index: 29.2 +/- 4.0 vs 35.9 +/- 2.9, P < 0.001). A significant inverse correlation was fou nd between Cobb's angle and both the right and left DM-Index (r = -0.8 2 and -0.66 respectively). In a stepwise multiple-regression analysis, the scintigraphic score correlated significantly with the functional index of distribution of inspired gas (IDI) derived from the multiple- breath nitrogen washout curve (P = 0.02). We conclude that lung ventil ation scintigraphy provides information on the regional distribution o f ventilation and on diaphragmatic movement in idiopathic scoliosis. T he pulmonary function derangements in scoliotic patients were mainly l ocalized in the lung on the concave side of the scoliotic curve and we re related to the severity of the spinal curvature.