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Assessing Cortical Cerebral Microinfarcts on High Resolution MR Images
Published on: November 20, 2015
Comparative Analysis of Cortical Microinfarcts and Microbleeds using 3.0-Tesla Postmortem Magnetic Resonance Images
Atsushi Niwa1, Yuichiro Ii1, Akihiro Shindo1
1Department of Neurology, Mie University Graduate School of Medicine, Mie, Japan.
Abstract:
Microvascular lesions including cortical microinfarctions (CMIs) and cerebral lobar microbleeds (CMBs) are usually caused by cerebral amyloid angiopathy (CAA) in the elderly and are correlated with cognitive decline. However, their radiological-histopathological coincidence has not been revealed systematically with widely used 3-Tesla (3T) magnetic resonance imaging (MRI). The purpose of the present study is to delineate the histopathological background corresponding to MR images of these lesions. We examined formalin-fixed 10-mm thick coronal brain blocks from 10 CAA patients (five were also diagnosed with Alzheimer's disease, three with dementia with Lewy bodies, and two with CAA only) with dementia and six non CAA patients with neurodegenerative disease. Using 3T MRI, both 3D-fluid attenuated inversion recovery (FLAIR) and 3D-double inversion recovery (DIR) were examined to identify CMIs, and T2* and susceptibility-weighted images (SWI) were examined to identify CMBs. These blocks were subsequently examined histologically and immunohistochemically. In CAA patients, 48 CMIs and 6 lobar CMBs were invariably observed in close proximity to degenerated Aβ-positive blood vessels. Moreover, 16 CMIs (33%) of 48 were detected with postmortem MRI, but none were seen when the lesion size was smaller than 1 mm. In contrast, only 1 undeniable CMI was founded with MRI and histopathology in 6 non CAA patients. Small, cortical high-intensity lesions seen on 3D-FLAIR and 3D-DIR images likely represent CMIs, and low-intensity lesions in T2* and SWI correspond to CMBs with in vivo MRI. Furthermore, a close association between amyloid-laden vessels and these microvascular lesions indicated the contribution of CAA to their pathogenesis.
Insights
Cerebral amyloid angiopathy (CAA) contributes to microvascular lesions like cortical microinfarctions and cerebral lobar microbleeds. This study links MRI findings to histopathology, confirming CAA
Area of Science:
- Neurology
- Neuroradiology
- Pathology
Background:
- Microvascular lesions, including cortical microinfarctions (CMIs) and cerebral lobar microbleeds (CMBs), are common in elderly individuals with cerebral amyloid angiopathy (CAA).
- These lesions are associated with cognitive decline, but their direct correlation with magnetic resonance imaging (MRI) findings has not been systematically established.
- Understanding the radiological-histopathological basis of these lesions is crucial for accurate diagnosis and understanding disease progression.
Purpose of the Study:
- To systematically correlate histopathological findings of microvascular lesions with their appearance on 3-Tesla (3T) MRI.
- To investigate the role of cerebral amyloid angiopathy (CAA) in the pathogenesis of cortical microinfarctions (CMIs) and cerebral lobar microbleeds (CMBs).
- To delineate the specific MRI signatures of CMIs and CMBs using advanced imaging sequences.
Main Methods:
- Examination of formalin-fixed brain blocks from 10 dementia patients with CAA and 6 non-CAA neurodegenerative disease patients.
- Utilized 3T MRI with 3D-fluid attenuated inversion recovery (FLAIR), 3D-double inversion recovery (DIR), T2*, and susceptibility-weighted imaging (SWI) to identify CMIs and CMBs.
- Subsequent histological and immunohistochemical analysis of the brain blocks to confirm lesion presence and amyloid-beta (Aβ) deposition.
Main Results:
- In CAA patients, 48 CMIs and 6 CMBs were found in proximity to degenerated Aβ-positive blood vessels.
- 33% (16/48) of CMIs were detected by postmortem MRI, with smaller lesions (<1 mm) often missed.
- A significant association was observed between amyloid-laden vessels and microvascular lesions, indicating CAA's role in their development.
Conclusions:
- 3T MRI, particularly with FLAIR, DIR, T2*, and SWI sequences, can identify microvascular lesions like CMIs and CMBs.
- The presence of amyloid-laden vessels adjacent to these lesions strongly suggests CAA as a key contributor to their pathogenesis.
- This study provides a direct radiological-histopathological correlation, enhancing the understanding of microvascular changes in CAA.
