REGIONAL VENTILATION-PERFUSION MISMATCH IN INTERSTITIAL PNEUMONIA - CORRELATION BETWEEN SCINTIGRAPHY AND CT

Interstitial pneumonia is one of the many causes of a scintigraphic ve ntilation-perfusion (V/Q) mismatch. To evaluate the morphologic featur es of V/Q mismatched areas in patients with interstitial pneumonia, we correlated the findings on lung scintigraphy using Kr-81m and Tc-99m MAA with CT scan findings. Of 41 patients, 20 (49%) had a high V/Q mis matched areas. All of these areas corresponded to cystic air spaces sh own on CT, and most of them showed a honeycomb pattern. Ventilation-pe rfusion matched defects were seen in 23 patients (56%). The matched de fects corresponded to cystic air spaces (honeycomb or bullous changes) or lung attenuation changes of varying degrees on CT. Cystic air spac es with high V/Q mismatch are considered to be normally ventilated. To distinguish mismatched areas of interstitial pneumonia from areas of pulmonary embolism, it may be necessary to compare scintigraphic findi ngs with CT.