Detection of right to left shunt with first pass pulmonary perfusion imaging

The authors report the first pass pulmonary perfusion imaging in 7 cases of nonhaematological cyanosis with hypoxaemia. Three patients have pulmonary angiography, among them only one showing surgically proved multiple arteriovenous fistula in left lung, while the 2 with hepatic cirrhosis were normal. All patients using first pass pulmonary perfusion imaging were normal in the phase of first pass, but their whole body scans demonstrated that there was high radioactive uptake in the brain, spleen and kidneys. This confirmed the presence of intrapulmonary arteriovenous communications. These results proved that this method in noninvasive, highly sensitive and easy to perform. not only can it differentiate the intrapulmonary from intracardiac, functional from anatomic right to left shunts, but also can calcuate the shunting rate. It is especially valuable in detecting the presence of dilated intrapulmonary channels which are too small to be detected angiographically