Plaque imaging with CT coronary angiography:Effect of intra-vascular attenuation on plaque type classification

AIM: To assess the attenuation of non-calcified atherosclerotic coronary artery plaques with computed tomography coronary angiography (CTCA). METHODS: Four hundred consecutive patients underwent CTCA (Group 1: 200 patients, Sensation 64 Cardiac, Siemens; Group 2: 200 patients, VCT GE Healthcare, with either Iomeprol 400 or Iodixanol 320, respectively) for suspected coronary artery disease (CAD). CTCA was performed using standard protocols. Image quality (score 0-3), plaque (within the accessible non-calcified component of each non-calcified/mixed plaque) and coronary lumen attenuation were measured. Data were compared on a per-segment/per-plaque basis. Plaques were classified as fibrous vs lipid rich based on different attenuation thresholds. A P < 0.05 was considered significant. RESULTS: In 468 atherosclerotic plaques in Group 1 and 644 in Group 2, average image quality was 2.96 ± 0.19 in Group 1 and 2.93 ± 0.25 in Group 2 (P ≥ 0.05). Coronary lumen attenuation was 367 ± 85 Hounsfield units (HU) in Group 1 and 327 ± 73 HU in Group 2 (P < 0.05); non-calcified plaque attenuation was 48 ± 23 HU in Group 1 and 39 ± 21 HU in Group 2 (P < 0.05). Overall signal to noise ratio was 15.6 ± 4.7 in Group 1 and 21.2 ± 7.7 in Group 2 (P < 0.01). CONCLUSION: Higher intra-vascular attenuation modifies significantly the attenuation of non-calcified coronary plaques. This results in a more difficult characterization between lipid rich vs fibrous type.

Relation between Carotid Artery Plaques Characteristics as a Predictor of Haemodynamics Changes after Carotid Artery Stenting

Objectives: To study relationship between carotid artery plaques characteristics and haemodynamic changes after carotid stenting. Patients and Methods: This observational prospective (pilot) study included 20 patients—who underwent CAS. The study was carried out in Ain shams university hospitals—Railway hospital (ERMED) and Suez insurance hospital from December 2018 to February 2020. Inclusion criteria, Symptomatic (defined as amaurosis fugax, TIA, Minor stroke or Major stroke) stenosis > 70%. Asymptomatic stenosis > 80% (accidentally discovered during pre-operative assessment for CABG and during full assessment for irrelevant stroke). Results: Regarding to plaque character for degree of stenosis, calcification and ulceration revealed significantly higher degree of stenosis in hemodynamic events group (P = 0.024). On the other hand, that there was no statistically significant difference between the two groups as regard calcification, ulceration and lesion location. Conclusion: The study revealed that HI is a common occurrence following CAS procedures and significantly higher degree of stenosis in hemodynamic events group. Plaque shape, ulcerations hardly affect haeodynamic instability after carotid stenting.

Molecular imaging of plaques in coronary arteries with PET and SPECT

Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lu-men stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increas-ingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography （PET） and single photon emission computed tomography （SPECT） has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging tech-niques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coro-nary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed.

Atherosclerotic aortic plaques detected by transesophageal echocardiography

Objective To evaluate the predictive value of atherosclerotic aortic plaques in coronary artery disease (CAD). Methods In 50 patients with suspected coronary artery disease, transesophageal echocardiography was performed to examine their thoracic aortas 2 weeks before or after coronary angiography. In the cases of coronary angiography studied, stenosis of the coronary artery ≥50%was considered to be due to coronary artery disease, whereas the thickness of the intima ≥1.3 mm was taken to be the criteria for the presence of an atherosclerotic aortic plaque on the transesophageal echocardiographic test. Results Among the 50 patients, 37 cases were diagnosed as CAD and 13 cases were considered to be normal. The plaques of the thoracic aorta were observed in 34 cases in the CAD group and 3 cases in the normal group. The sensitivity and specificity of aortic plaques for CAD were 91.9%and 76.9%, respectively. The positive and negative predictive values of the aortic plaques for CAD were 91.9%and 76.9%, respectively. The accuracy was 88.0%. 80 percent of the patients with single-vessel disease had thoracic aortic plaques, 92 percent of the patients with two vessel disease and 100 percent of the patients with three vessel disease had thoracic aortic plaques. There was a significant difference in the thickness of aortic intimas between the normal group and the CAD group. Conclusions Detecting atherosclerotic plaques in the thoracic aorta with transesophageal echocardiography may be of great value in predicting the presence and extent of coronary artery disease.

The Thromboxane Receptor Antagonist S18886 influence the stability of atherosclerosis in ApoE Null Mice

Objectives To investigate whether thromboxane receptor antagonist S18886 inhibits infiltrating macrophages to vessel wall and influence the morphology of atherosclerotic plaque; The effective of S18886 compared to clopidegrol on the development of atherosclerosis, accumulation of lipid- filled macropha-ges in apoE null mice. Methods All mice were done cuffed common carotid artery and fed a Western-type atherogenic diet for 6 weeks from the day of surgery, at same time the therapy group mice were gavaged S18886 5 mg/Kg/day and clopidegrol respec- tively, the same volume water were gavaged as the placebo group. Results profound inhibition of lesion area growth after cuff of the right common carotid artery in mice with 5 mg/kg of S18886, markdely reduce intima to media ratio and intima to total wall area compare with clopidegrol or blank group; Macrophage infiltration into sites of arterial plaque was also markedly attenuated by ICAM-1 deficiency in the S18886 group, whereas inside the arterial wall plaque of placebo apoE null mice α-smooth muscle actin markedly attenuated. Treatment with 25 mg/kg/day clopidegrol reduced the level of ICAM-1 stai ning, both S18886 and clopidegrol didn't influence the α-smooth muscle actin inside plaque. Conclusions It was considered that the novel anti-thrombotic drug significant reduce macrophage infiltration in the sites of arterial plaque by ICAM-1 deficiency, S18886 not only reduce the size, but also stabilized the plaque.

Correlation between Carotid Plaque Characteristics without Operative Indication and Ischemic Stroke

Objective To access the correlations between characteristics of carotid plaque in MRI and ischemic stroke in patients with≤50%carotid artery stenosis.Methods A total of 43 patients with≤50%carotid artery stenosis were selected for ultrasound from September 2014 to February 2016.A further test using magnetic resonance(MR)black blood imaging examination were carried out to distinguish the anatomy of the vessel as well the composition of the atherosclerotic plaque with remarkable details.The relationship between carotid plaque characteristics in MRI and other risk factors of patients with ischemic stroke was analyzed by univariate and multivariate analysis.Results The mean follow-up time was 11.8 months.During the follow-up period,4 of the 43 individuals experienced an ipsilateral ischemic stroke.Kaplan-Meier survival analysis showed the mean ischemic stroke free survival of patients with coronary heart disease(CHD)was significantly shorter than that in patients without CHD,which were 12.1 months and 18.7 months respectively(P=0.029).The mean ischemic stroke free survival of patients with intra-plaque hemorrhage(IPH)was significantly shorter than that in patients without IPH,which were 14.3 months and 18.6 months respectively(P=0.001).COX regression analysis showed that coronary heart disease(HR=27.4;95%CI,1.6-464.3;P=0.022)and IPH(HR=18.2;95%CI,2.7-123.3;P=0.003)were independent risk factors for ischemic stroke.Conclusion For patients with carotid artery stenosis≤50%,IPH of carotid plaques and CHD are independent risk factors for ischemic stroke.