19 Figure 3 . Contrast echocardiography in an HPS patient. In patients with intracardiac or intrapulmonary shunt, labeled albumin is taken up by the liver, brain, and kidney, allowing shunt extent to be quantified by means of the ratio between lung and brain radioactivity. Furthermore, the macroaggregated albumin method undervalues the presence of IPVDs. 8 Figure 4 .
Pulmonary angiography is the third method of discerning IPVDs.
2 Two patterns have been described, termed type I or diffuse, and type II or focal. In turn, the type I pattern has been subdivided into minimal and advanced classifications. I pattern shows normal vessels or diffuse and tenuous spider web vascular abnormalities. Advanced type I presents a spongy or blotchy appearance. The type II or focal pattern shows arteriovenous malformations similar to those observed in the Rendu-Osler syndrome of hereditary hemorrhagic telangiectasias.