[Noninvasive imaging of vulnerable plaques and thromboses with PET/CT complex imaging technique].

OBJECTIVE: To investigate the feasibility of identifying the vulnerable plaque and predicting plague rupture and thrombus using by positron emission tomography/computed tomography angiography (PET/CTA). METHODS: Twenty-eight male New Zealand white rabbits were fed with hyper-lipid diet for 2 weeks before the balloon injury of the abdominal aorta.Then these rabbit were intermittently fed with hyper-lipid diet for 14 weeks, in order to trigger pharmaceutic the plague rupture and thrombus. PET/CTA scans of abdominal aorta were performed before and after the drug triggering, FDG uptake (standardized uptake value, SUV) was measured. Rabbits were euthanized to obtain data of pathology and histology. The parameters obtained by PET/CTA, pathology and histology were compared and the correlations were performed. RESULTS: The thrombosis was identified in 13 of 20 rabbits.Before the drug triggering, (18)F-FDG mean standardized uptake value (SUVmean) was higher in thrombotic arterial segments (defined as vulnerable plaque) (1.10 ± 0.19 vs 0.77 ± 0.11,P = 0.000); after the drug triggering, SUVmean was higher in thrombotic arterial segments, too (1.15 ± 0.26 vs 0.85 ± 0.17, P = 0.000). We use the ROC curve for SUVmean to predict plaque rupture and thrombosis. The area under the curve (AUC) was 0.898 (P = 0.000). The cutoff value was 0.882. CONCLUSIONS: Our findings indicated that (18)F-FDG PET/CTA, as a noninvasive imaging method, could be used to identify vulnerable plaques and predict thrombosis events.

Magnetic resonance imaging features of vulnerable plaques in an atherosclerotic rabbit model.

BACKGROUND: Noninvasive detection of vulnerable plaque has a significant implication for prevention and treatment of atherosclerotic diseases. The aim of this study is to investigate the difference between vulnerable plaques and stable plaques in magnetic resonance (MR) images. METHODS: Atherosclerosis was induced in twenty male New Zealand white rabbits by high cholesterol diet and balloon injury of the abdominal aorta. After baseline (pre-triggering) MR imaging (MRI) scan, the rabbits underwent pharmaceutical triggering with Russell's viper venom and histamine to induce atherothrombosis, followed by another MRI scan 48 hours later (post-triggering). Rabbits were euthanized to obtain pathological and histological data. The results of MRI were compared with those of pathology and histology. RESULTS: MRI showed that abdominal aorta of the rabbits had pathological change of atherosclerosis in different degrees. Seventy-five plaques were analysed, among which 14 had vulnerable thrombi and 61 stable. Thrombosis was identified in 7 of 11 rabbits by post-triggering MRI, the sensitivity and K value of MR in detection of vulnerable plaque was 71% and 0.803 (P < 0.05). MRI data significantly correlated with the histopathological data in fibrous cap thickness (r = 0.749) plaque area (r = 0.853), lipid core area (r = 0.900). Compared with stable plaques, vulnerable plaques had a significantly thinner fibrous cap ((0.58 ± 0.27) mm vs. (0.95 ± 0.22) mm), larger lipid core area ((7.56 ± 2.78) mm(2) vs. (3.29 ± 1.75) mm(2)), and a higher ratio of lipid core area/plaque area ((55 ± 16)% vs. (27 ± 17)%), but plaque area was comparable in two groups on MRI. The ratio of lipid core area/plaque area was a strong predictor of vulnerable plaques. CONCLUSION: MRI could distinguish vulnerable plaques from stable plaques in a rabbit model of atherothrombosis and may thus be useful as a noninvasive modality for detection of vulnerable plaques in humans.

Detection of vulnerable atherosclerotic plaque and prediction of thrombosis events in a rabbit model using 18F-FDG -PET/CT.

BACKGROUND: Detection of vulnerable plaques could be clinically significant in the prevention of cardiovascular events. We aimed to compare Fluorine-18 fluorodeoxyglucose ((18)F-FDG) uptake in vulnerable and stable plaques, and investigate the feasibility of predicting thrombosis events using Positron Emission Tomography/Computed Tomography (PET/CT) angiography. METHODS: Atherosclerosis was induced in 23 male New Zealand white rabbits. The rabbits underwent pharmacological triggering to induce thrombosis. A pre-triggered PET/CTA scan and a post-triggered PET/CTA scan were respectively performed. (18)F-FDG uptake by the aorta was expressed as maximal standardized uptake value (SUVmax) and mean SUV (SUVmean). SUVs were measured on serial 7.5 mm arterial segments. RESULTS: Thrombosis was identified in 15 of 23 rabbits. The pre-triggered SUVmean and SUVmax were 0.768 ± 0.111 and 0.804 ± 0.120, respectively, in the arterial segments with stable plaque, and 1.097 ± 0.189 and 1.229 ± 0.290, respectively, in the arterial segments with vulnerable plaque (P<0.001, respectively). The post-triggered SUVmean and SUVmax were 0.849 ± 0.167 and 0.906 ± 0.191, respectively in the arterial segments without thrombosis, and 1.152 ± 0.258 and 1.294 ± 0.313, respectively in the arterial segments with thrombosis (P<0.001, respectively). The values of SUVmean in the pre-triggered arterial segments were used to plot a receiver operating characteristic curve (ROC) for predicting thrombosis events. Area under the curve (AUC) was 0.898. Maximal sensitivity and specificity (75.4% and 88.5%, respectively) were obtained when SUVmean was 0.882. CONCLUSIONS: Vulnerable and stable plaques can be distinguished by quantitative analysis of (18)F-FDG uptake in the arterial segments in this rabbit model. PET/CT may be used for predicting thrombosis events and risk-stratification in patients with atherosclerotic disease.