Feasibility of blood flow measurement by externally controlled dye delivery.
We are developing a new method of delivering substances locally and repeatedly in the retinal vasculature under external control. This delivery system is based on encapsulating the substance in heat-sensitive lipsomes, which are injected intravenously and lysed by a heat pulse delivered by a laser. The feasibility of using this system with dyes and creating a sharp dye front was tested in vitro and in vivo. The results indicate that the background fluorescence of intact liposomes is minimal but in contrast a dramatic increase in fluorescence is achieved where the dye is released. In vivo tests indicated that only the selected vascular branch fluoresced. Moreover, a sharp dye front could be obtained repeatedly and preserved over significant distances. The presence of a sharp dye front allowed measurements, in vitro, of blood velocity which correlated well (r = 0.985, P less than 0.001) with the average blood velocity values calculated from the known flow rate.
Zeimer
R C
RC
Applied Physics Laboratory, Department of Ophthalmology, University of Illinois College of Medicine, Chicago 60612.
Khoobehi
B
B
Peyman
G
G
Niesman
M R
MR
Magin
R L
RL
D000818:Animals; D004396:Coloring Agents / Q000008:administration & dosage*; D004337:Drug Carriers; D005240:Feasibility Studies; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D007275:Injections, Intravenous; D007834:Lasers; D008081:Liposomes; D010781:Photography; D011817:Rabbits; D012039:Regional Blood Flow; D012171:Retinal Vessels / Q000502:physiology*
D004396:Coloring Agents; D004337:Drug Carriers; D008081:Liposomes