Dextran-coated ultra-small, superparamagnetic, iron oxide particles (USPIO) have been proposed as magnetic resonance (MR) lymph node contrast agents. This thesis analyzed the topographic distributions of the pelvic and inguinal lymph nodes and quantified their spatial relations with the adjacent vascular system. We hypothesized that USPIO would facilitate identification of normal lymph nodes in a manner superior to that afforded by computed tomography or unenhanced MR, but using current clinically available scanners would be unlikely to identify microscopic nodal metastases. We have constructed a high quality nodal atlas describing probability distributions for lymph node number, size and position. Using this model, we then defined a generic three-dimensional nodal clinical target volume and a means of accurate delineation of this volume in a three-dimensional representation. This is the most quantitative assessment of the pelvic and inguinal lymphatics to date and will help to improve the successful targeting of lymph nodes for radiotherapy.

Dextran-coated ultra-small, superparamagnetic, iron oxide particles (USPIO) have been proposed as magnetic resonance (MR) lymph node contrast agents. This thesis analyzed the topographic distributions of the pelvic and inguinal lymph nodes and quantified their spatial relations with the adjacent vascular system. We hypothesized that USPIO would facilitate identification of normal lymph nodes in a manner superior to that afforded by computed tomography or unenhanced MR, but using current clinically available scanners would be unlikely to identify microscopic nodal metastases. We have constructed a high quality nodal atlas describing probability distributions for lymph node number, size and position. Using this model, we then defined a generic three-dimensional nodal clinical target volume and a means of accurate delineation of this volume in a three-dimensional representation. This is the most quantitative assessment of the pelvic and inguinal lymphatics to date and will help to improve the successful targeting of lymph nodes for radiotherapy.