“…In particular, this latter route was used in the determination of blood flow in tissues lacking an artery easy to cannulate, as in skeletal muscle [15], s.c. tissue [29], experimental tumours [13]. As for the liver blood flow, in addition to the well-known intra-arterial [20,22,24] and intraportal [7,8,22,24] routes, also the interstitial one was employed in both man [9,23,33,39] and experimental animals [18]. Our choice is due to the fact that we aimed at measuring the blood flow in liver metastases, and no other administration route would have supplied this particular tissue with the tracer.…”