Persistent decline in longitudinal and radial strain after coronary microembolization detected on velocity encoded phase contrast magnetic resonance imaging.
OBJECTIVE
To use velocity-encoded phase contrast (PC) MRI in assessing the effect of coronary microembolization on longitudinal and radial myocardial strain.


METHODS
A combined X-ray and MR system (XMR) was used for selective left anterior descending artery catheterization and microinfarct assessment in swine (n = 6). The embolized area at risk was defined on perfusion MRI followed by administration of a 7500 count (size = 100-300 microm) of the embolic agent. Quantification of strain and microinfarction was performed at 1 h and 1 week using PC-MRI and delayed enhancement (DE) MRI, respectively. At postmortem, sliced hearts were stained to define microinfarction.


RESULTS
Baseline longitudinal and radial strain did not differ between area-at-risk and remote myocardium. The embolized territory (area at risk) showed significant decline in longitudinal strain from -11.5 +/- 3.2% to 1.8 +/- 2.5% at 1 h (P < 0.05) and -3.9 +/- 1.1% at 1 week (P < 0.05). Similarly, regional radial strain progressively declined from 23.6 +/- 2.5% at baseline to 12.5 +/- 3.7% at 1 h (P < 0.05) and 4.8 +/- 5.0% at 1 week (P < 0.01). The size of microinfarction was not significantly different between DE-MRI and histochemical staining.


CONCLUSIONS
PC-MRI is sensitive in assessing changes in regional longitudinal and radial strain after coronary embolization. Longitudinal and radial strain of the hyperenhanced patchy microinfarction demonstrates persistent decline over the course of 1 week.
Dicks
Demetrius L
DL
Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California 94143-2205, USA.
Carlsson
Marcus
M
Heiberg
Einar
E
Martin
Alastair
A
Saloner
David
D
Arheden
Hakan
H
Saeed
Maythem
M
D000818:Animals; D003287:Contrast Media; D004621:Embolization, Therapeutic / Q000009:adverse effects*; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006571:Heterocyclic Compounds; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007472:Iohexol; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008863:Microspheres; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology / Q000648:ultrastructure; D009942:Organometallic Compounds; D011859:Radiography; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013312:Stress, Physiological; D013552:Swine; D013997:Time Factors
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D007472:Iohexol; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate