The time window of MRI of murine atherosclerotic plaques after administration of CB2 receptor targeted micelles: inter-scan variability and relation between plaque signal intensity increase and gadolinium content of inversion recovery prepared versus non-prepared fast spin echo.
Single fast spin echo scans covering limited time frames are mostly used for contrast-enhanced MRI of atherosclerotic plaque biomarkers. Knowledge on inter-scan variability of the normalized enhancement ratio of plaque (NER(plaque)) and relation between NER(plaque) and gadolinium content for inversion-recovery fast spin echo is limited. Study aims were: evaluation of (1) timing of MRI after intravenous injection of cannabinoid-2 receptor (CB2-R) (expressed by human and mouse plaque macrophages) targeted micelles; (2) inter-scan variability of inversion-recovery fast spin echo and fast spin echo; (3) relation between NER(plaque) and gadolinium content for inversion-recovery fast spin echo and fast spin echo. Inversion-recovery fast spin echo/fast spin echo imaging was performed before and every 15 min up to 48 h after injection of CB2-R targeted or control micelles using several groups of mice measured in an interleaved fashion. NER(plaque) (determined on inversion-recovery fast spin echo images) remained high (∼2) until 48 h after injection of CB2-R targeted micelles, whereas NER(plaque) decreased after 36 h in the control group. The inter-scan variability and relation between NER(plaque) and gadolinium (assessed with inductively coupled plasma- mass spectrometry) were compared between inversion-recovery fast spin echo and fast spin echo. Inter-scan variability was higher for inversion-recovery fast spin echo than for fast spin echo. Although gadolinium and NER(plaque) correlated well for both techniques, the NER of plaque was higher for inversion-recovery fast spin echo than for fast spin echo. In mice injected with CB2-R targeted micelles, NER(plaque) can be best evaluated at 36-48 h post-injection. Because NER(plaque) was higher for inversion-recovery fast spin echo than for fast spin echo, but with high inter-scan variability, repeated inversion-recovery fast spin echo imaging and averaging of the obtained NER(plaque) values is recommended.
te Boekhorst
B C M
BC
Department of Cardiology, University Medical Center, Utrecht, The Netherlands. b.c.m.teboekhorst@umcutrecht.nl
Bovens
S M
SM
van de Kolk
C W A
CW
Cramer
M J M
MJ
Doevendans
P A F M
PA
ten Hove
M
M
van der Weerd
L
L
Poelmann
R
R
Strijkers
G J
GJ
Pasterkamp
G
G
van Echteld
C J A
CJ
D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D015415:Biomarkers / Q000378:metabolism; D005682:Gadolinium / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D051379:Mice; D018345:Mice, Knockout; D008823:Micelles; D052250:Nitric Oxide Synthase Type III / Q000235:genetics; D058226:Plaque, Atherosclerotic / Q000378:metabolism / Q000473:pathology; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution
D001057:Apolipoproteins E; D015415:Biomarkers; D008823:Micelles; D043885:Receptor, Cannabinoid, CB2; D005682:Gadolinium; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse