Mosaic Perfusion

Figure 1. Definition

HRCT from a patient with HP shows areas of increased attenuation (ground-glass opacity) as well as areas of decreased attenuation (mosaic perfusion), best demonstrated in the right middle lobe. Note how the vessels appear abnormally small in the areas of decreased attenuation. This finding allows the confident diagnosis of mosaic perfusion.

Inspiratory and expiratory images can be used to verify mosaic perfusion of air trapping. Figures 2A and 2 B are inspiratory and expiratory images, respectively, at the same level from the same patient.

Figure 2A

Inspiratory HRCT image shows bilateral inhomogeneous lung opacity representing the combination of ground-glass opacity (areas of increased attenuation) and mosaic perfusion (areas of decreased attenuation).

Figure 2B

Expiratory HRCT image from same patient as figure 2A shows that the areas of decreased attenuation seen in Figure 2A have failed to increase in attenuation as they normally should with expiratory imaging: these areas remain "black".

Figures 3A and 3B show the value of inspiratory and expiratory images in demonstrating mosaic perfusion in subtle cases.

Figure 3A. Normal Inspiratory Image

Inspiratory HRCT image in a patient with HP shows no specific abnormality. Very slight decreased attenuation could be present at the right lung base, but this finding is not seen with confidence.

Figure 3B. Abnormal Expiratory Image

Expiratory HRCT image from the same patient as 3A shows marked decreased parenchymal attenuation in the right lung base, diagnostic of air trapping and strongly suggestive of a small airway inflammatory process. The patient was a bird owner, and HP was proven at surgical biopsy.

Return to Discussion--Mosaic Perfusion

TOP----Rad/Path Home Page