Characterization of the Infarct Pattern Caused by Vulnerable Aortic Arch Atheroma: DWI and Multidetector Row CT Study

Abstract

Background: Aortic arch atheroma (AAA) has been accepted as a possible embolic source in patients with ischemic stroke, especially cryptogenic stroke. However, despite its well-known role as a risk factor for stroke, research focused on the mechanism or characteristics of stroke caused by AAA is insufficient. In this study, we aimed to evaluate clinical and radiological characteristics including lesion pattern on DWI in acute stroke patients associated with vulnerable AAA detected by multidetector row computed tomography (MDCT). Methods: From September 2008 through May 2011, patients who presented with acute ischemic stroke and underwent MDCT were found in a prospective stroke registry. Patients without evident stroke etiology were included and classified by presence of vulnerable AAA. Vulnerable AAA was defined as (i) at least 6 mm thick adjacent to the aortic wall; (ii) ulcerated plaque, or (iii) soft plaque. Soft plaque was defined as the presence of clearly visualized area of hypoattenuation (<80 Hounsfield units) suggestive of thrombus. The patients without vulnerable AAA were classified as no/simple AAA group. The characteristics of diffusion-weighted MRI (DWI) lesions were analyzed in terms of the number and size of the lesions, and the involved vascular territories. Results: A total of 63 cryptogenic stroke patients were included in this study. Vulnerable AAA was observed in 15 (23.8%) patients. The patients with vulnerable AAA were older than those with no/simple AAA (p = 0.026). DWI analysis revealed that the vulnerable AAA group had a greater chance of having multiple and small lesions in multiple vascular territories that were mainly located in cortical and border-zone regions than the no/simple AAA group. Multiple logistic regression analysis showed that age (odds ratio 1.17; 95% confidence interval 1.02–1.34) and multiple small lesions in multiple vascular territories (odds ratio 33.18; 95% confidence interval 4.26–258.45) were independently associated with vulnerable AAA. Conclusion: Vulnerable AAA is independently associated with a DWI pattern characterized by multiple small scattered lesions in multiple vascular territories in conjunction with age. It may help determine stroke mechanism quickly and easily, and provide more information about the pathomechanism of vulnerable AAA-related stroke.

Evaluation of Cryptogenic Stroke With Advanced Diagnostic Techniques

“…[71][72][73] Aortogenic Embolic Source Evaluation TCD microembolism study showed that AAA has embolic potential, 74 and DWI patterns are characterized by multiple small scattered lesions in multiple vascular territories that are mainly located in cortical and borderzone regions. 75 These are in line with an autopsy study of cases with cerebral atheromatous embolism, which showed that atheromatous emboli containing mostly cholesterol crystals are associated with borderzone infarct, whereas large emboli containing fibrin are associated with large territory infarcts. 76 Therefore, additional workup to document aortogenic sources are recommended in elderly patients with vascular risk factor and infarct patterns associated with complex AAA; (1) multiple brain infarcts involving multiple vascular territories, 77 (2) small-sized infarcts, 65 and (3) location of cortical and borderzone region.…”

“…76 Therefore, additional workup to document aortogenic sources are recommended in elderly patients with vascular risk factor and infarct patterns associated with complex AAA; (1) multiple brain infarcts involving multiple vascular territories, 77 (2) small-sized infarcts, 65 and (3) location of cortical and borderzone region. 75 …”

An Approach to Working Up Cases of Embolic Stroke of Undetermined Source

“…AAA was considered as a cause of stroke if vulnerable AAA was observed on the TEE or MDCT. Vulnerable AAA was defined as aortic plaques in the ascending aorta or proximal arch that met ≥1 of the following criteria: (1) ≥4 mm of intima–media thickness on TEE or ≥6 mm of thickness adjacent to the aortic wall on MDCT or (2) ulcerated plaque or (3) mobile plaque on TEE or soft plaque on MDCT . We performed the TEE or transcranial Doppler ultrasound agitated saline test or MDCT to evaluate PFO.…”

“…Vulnerable AAA was defined as aortic plaques in the ascending aorta or proximal arch that met ≥1 of the following criteria: (1) ≥4 mm of intima-media thickness on TEE or ≥6 mm of thickness adjacent to the aortic wall on MDCT or (2) ulcerated plaque or (3) mobile plaque on TEE or soft plaque on MDCT. 9,10 We performed the TEE or transcranial Doppler ultrasound agitated saline test or MDCT to evaluate PFO. PFO was deemed present when 1 of following criteria was observed: (1) the passage of >3 microbubbles to the left atrium within 3 cardiac cycles after complete opacification of the right atrium on the TEE, (2) microembolic signals within 40 seconds after injection of agitated saline with microbubbles on the transcranial Doppler ultrasound, or (3) a distinct flap in the left atrium at the expected location of the septum primum or a continuous column of contrast material connecting both atria or jet of contrast material into the right atrium on the MDCT.…”

Complex Atheromatosis of the Aortic Arch: An Emerging Diagnosis in Cerebral Ischemia of Unknown Cause

“…In this study, advanced age and the low-density lipoprotein (LDL)cholesterol/high-density lipoprotein (HDL)-cholesterol ratio of 2.23 were substantially higher and closely associated with mobile and ulcerative aortic plaques. A study of 63 patients with cryptogenic stroke using diffusion-weighted MR imaging (DWI) and multidetector row CT revealed the presence of vulnerable aortic arch atheromatosis in 23.8% of the cases [16]. These patients had more risk of having a DWI pattern characterized by multiple, small, scattered lesions in multiple vascular territories [16].…”