Blood Flow and Arterial Infusion by Implanted Port in In-111 Octreotide Therapy: Critical Overview
In-111-Octreotide infusion, via intrahepatic catheterization is well established technique in our Institution in hepatocellular carcinoma and neuroendocrine tumors treatment. In order to facilitate repetitive infusions of our patients, a method of implanted ports use, gave a simpler therapeutic way but also improved therapy results. Our aim is to show that radiopharmaceutical fluid flow through implanted port is rich; the absorbed dose in the tumor increased for best therapy results. Surgically implanted ports have been used in repetitive intra-arterial In-111 radiolabeled Octreotide infusions for 22 patients with hepatocellular carcinoma and similarly 18 patients with neuroendocrine tumors in a continuous base. A percutaneous implantation procedure facilitates safe and less invasive radiopharmaceutical infusions for the treatment. We have focused on the interventional techniques for percutaneous implantation of a vascular access device, consisting of an implantable port, to perform In-111 Octreotide infusions. Hepatic arterial infusion radiotherapy employs a hepatic artery catheter as a conduit to achieve a high concentration of radiolabeled agent to liver tumors. It is performed using less-invasive percutaneous image guided procedures. Various techniques were used to ensure high concentration of radiopharmaceutical in liver tumors, as there are many anatomical hepatic arterial variations and complicated blood flow patterns. These techniques are composed of arterial redistribution by embolization, percutaneous catheter placement, evaluation and management of flow patterns that reflect In-111 Octreotide distribution. Using fluid flow theory, we describe blood flow alterations that could be performed to obtain selective radiopharmaceutical distribution to the target area and avoid side effects caused by the accumulation of the radiolabeled agent into non tumor areas. By steady, laminar and disturbed flow equations, the rich distribution of our agent in the scintigraphy imaging of the tumor, by the implanted ports technique, can be explained. The factors affecting hepatic arterial flow in tumor feeding artery were analyzed. The patency rate of the hepatic artery was significantly higher in patients with catheter placement using fixed port method than those undergo fully interventional catheterization. A ratio of 5: 1 to 3: 1 flow increase was calculated through poiseuille flow and Reynolds number for circular pipe. We consider that in continuous therapy, it is important to use the simplest fixed port method for percutaneous catheter placement instead of interventional catheterization, in order to increase absorbed dose into tumor for best response of radionuclide therapy.
Assoc. Professor Maria Lyra Georgosopoulou
Radiation Physics Unit, National and Kapodistrian University of Athens, Athens, Greece.
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