Detection and quantification of acute reperfused myocardial infarction in rabbits using DISA-SPECT/CT and 3.0T cardiac MRI.
BACKGROUND
Necrosis avid tracer (123)I-hypericin ((123)I-HYP) enables hot-spot imaging on acute myocardial infarction (MI). We explored dual-isotope simultaneous acquisition single photon emission computed tomography/computed tomography (DISA-SPECT/CT) by using (123)I-HYP and standard (99m)Tc-sestamibi ((99m)Tc-MIBI), in comparison with cardiac magnetic resonance imaging (cMRI), autoradiography (AutoRx) and histomorphometry.


METHODS
Acute MI was induced by 90-min coronary artery occlusion and 24-h reperfusion in 9 rabbits. They were scanned with cMRI at 3.0T, followed by intravenous injections of (123)I-HYP, and 8h later, of (99m)Tc-MIBI. Then, they were imaged with DISA-SPECT/CT for detection and localization of MI. The excised heart was sectioned for AutoRx, triphenyltetrazolium chloride (TTC) histochemistry, and haematoxylin-eosin (HE) staining. DISA-SPECT/CT and cMRI were co-registered, and MI was compared between different modalities and techniques for correlation with ex vivo findings. Tracer/contrast uptakes were quantified on polar maps. One way-ANOVA and Bonferroni's tests were used for comparison of multiple techniques. Linear regression and Bland-Altman analysis were used to compare measurements of MI.


RESULTS
MI volumes were not significantly different as by (99m)Tc-MIBI-SPECT, (123)I-HYP-SPECT, cMRI and TTC (38.94 ± 13.97%, 37.76 ± 13.16%, 35.19 ± 12.53% and 33.26 ± 10.65%; p > 0.05). The MI areas were 41.13 ± 18.70%, 40.19 ± 18.45%, 38.23 ± 16.86%, 36.83 ± 16.70%, 36.16 ± 16.15% and 35.03 ± 14.75% on (99m)Tc-MIBI-SPECT, (123)I-HYP-SPECT, cMRI, AutoRx, TTC and HE. There was no significant differences between each of two techniques (p = 0.9). Tracer/contrast uptakes were well correlated ((123)I-HYP vs (99m)Tc-MIBI r(2) = 0.66; (123)I-HYP vs cMRI r(2) = 0.63; (99m)Tc-MIBI vs cMRI r(2) = 0.64). Infarct/normal myocardium activity ratio was 40/1 and 23/1 by AutoRx and γ-counting.


CONCLUSIONS
(123)I-HYP has shown pronounced necrosis-avidity, which proves complementary for imaging MI with potential clinical applicability for myocardial viability determination.
Theragnostic Laboratory and Radiology Section, Department of Imaging and Pathology, Biomedical Sciences Group, KU Leuven, Leuven, Belgium.
Yuanbo
Y
Feng
Marlein Miranda
MM
Cona
Kathleen
K
Vunckx
Yue
Y
Li
Feng
F
Chen
Johan
J
Nuyts
Olivier
O
Gheysens
Lin
L
Zhou
Yi
Y
Xie
Raymond
R
Oyen
Yicheng
Y
Ni
D000818:Animals; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging*; D015428:Myocardial Reperfusion Injury / Q000000981:diagnostic imaging; D011817:Rabbits; D017256:Technetium Tc 99m Sestamibi; D014057:Tomography, X-Ray Computed / Q000379:methods
D017256:Technetium Tc 99m Sestamibi
(123)I-hypericin; Autoradiography; MRI; Myocardial infarction; Rabbit model; SPECT