Unilateral intracarotid injection of holmium microspheres to induce bilateral MRI-validated cerebral embolization in rats.
BACKGROUND
Cerebral embolization models have been hindered by the fact that delivery is predominantly one-sided and cannot be quantified easily. We have developed a model for bilateral cerebral micro-embolization. By using holmium microspheres, it is possible to quantify intracerebral delivery using MRI.


METHODS
To validate the quantification of holmium microspheres a phantom study was performed in which concentration of microspheres in solution was compared with the number of holmium-induced artifacts on MRI. After that identical microspheres were administered by unilateral injection in the carotid artery, while the opposite carotid artery was clamped. On post-injection MRI scans, intracerebral delivery and right/left distribution of the microspheres was determined.


RESULTS
In the phantom study it was shown that quantification by MRI is possible and that MRI artifacts represent single microspheres. In the rat brain, about one-third of the injected dose was consistently located on the contralateral side. The administration was reproducible regarding distribution and number of microspheres.


CONCLUSIONS
The use of holmium microspheres enables quantification of delivered dose as single microspheres induce artifacts on MRI. By clamping the contralateral carotid artery, one-third of the dose is diverted to the contralateral hemisphere.
Division of Perioperative Care and Emergency Medicine, University Medical Center Utrecht, mail stop, 3508 GA Utrecht, The Netherlands. f.delange@umcutrecht.nl
Fellery
F
de Lange
Jan M
JM
Dieleman
Erwin L A
EL
Blezer
Ralph J F
RJ
Houston
Cor J
CJ
Kalkman
J Frank W
JF
Nijsen
D000818:Animals; D002339:Carotid Arteries; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D007839:Functional Laterality / Q000502:physiology; D006695:Holmium; D007269:Injections, Intra-Arterial / Q000379:methods; D020766:Intracranial Embolism / Q000139:chemically induced* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008863:Microspheres; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results
D006695:Holmium