[CT compared with SPECT in chronic recurrent pulmonary embolism: hyperdensities as signs of pulmonary artery hyperperfusion?].

UNLABELLED

Purpose of this study was to assess the aetiology of inhomogeneous lung parenchymal attenuation in patients with chronic pulmonary thromboembolism, presenting as sharply demarcated areas of increased and decreased density on computed tomography.

MATERIAL AND METHODS

In 52 patients with chronic pulmonary thromboembolism, computed tomography (CT) was compared with perfusion scintigraphy (including SPECT) and agreement was assessed: "good" (all hyperdense CT segments are perfused on scan), "moderate" or "poor" (one or two resp. three or more hyperdense CT segments are not perfused).

RESULTS

44 of the 52 patients showed an inhomogeneous pulmonary attenuation on CT. Correlation of hyperdense areas with perfused lung parenchyma was graded as "good" in 26 cases, "moderate" in 14 and "poor" in 4 cases. In 40 of these 44 patients, scintigraphy revealed additional perfusion defects in homogeneously lucent areas on CT. In 6 of 8 patients with entirely homogeneous lung density on CT, SPECT revealed perfusion defects.

CONCLUSION

In patients with chronic pulmonary thromboembolism, increased lung density on CT is caused by hyperperfused lung parenchyma distally to patent pulmonary arteries. SPECT proves to be more sensitive in diagnosing perfusion inhomogeneities.