Blood supply of pulmonary metastases.

There is a widely held belief that metastases to the lung (like primary lung tumors) are supplied by the bronchial arteries and that pulmonary neovascularization does not occur. In 17 human lungs, we have demonstrated, both in vitro and in vivo, pulmonary circulation to metastases. We have confirmed this in a series of animal studies in which we implanted tumors of various histologies into rats' tails and induced metastases from these tumors into the lungs. Forty-eight percent of these metastases had an entirely pulmonary circulation, 36% a primarily pulmonary circulation with a small bronchial component, and only 16% of metastases, located in the central one third of the lung, had an exclusively bronchial circulation. We have now shown that these supplying pulmonary vessels to metastases can be clearly demonstrated on thin-section computed tomography of the lungs. This may prove to be a helpful, noninterventional diagnostic criterion for distinguishing a primary from a metastatic lesion.