Cerebral amyloid angiopathy: Review of clinico‐radiological features and mimics

Abstract

Cerebral amyloid angiopathy (CAA) is an important cause of lobar intracerebral haemorrhage (ICH) in the elderly, but has other clinico-radiological manifestations. In the last two decades, certain magnetic resonance imaging (MRI) sequences, namely gradient-recalled echo imaging and the newer and more sensitive susceptibility-weighted imaging, have been utilised to detect susceptibility-sensitive lesions such as cerebral microbleeds and cortical superficial siderosis. These can be utilised sensitively and specifically by the Modified Boston Criteria to make a diagnosis of CAA without the need for 'gold-standard' histopathology from biopsy. However, recently, other promising MRI biomarkers of CAA have been described which may further increase precision of radiological diagnosis, namely chronic white matter ischaemia, cerebral microinfarcts and lobar lacunes, cortical atrophy, and increased dilated perivascular spaces in the centrum semiovale. However, the radiological manifestations of CAA, as well as their clinical correlates, may have other aetiologies and mimics. It is important for the radiologist to be aware of these clinico-radiological features and mimics to accurately diagnose CAA. This is increasingly important in a patient demographic that has a high prevalence for use of antiplatelet and antithrombotic medications for other comorbidities which inherently carries an increased risk of ICH in patients with CAA.

Interthalamic adhesion size in aging dogs with presumptive spontaneous brain microhemorrhages: a comparative retrospective MRI study of dogs with and without evidence of canine cognitive dysfunction

“…Because we could not corroborate our findings with histopathology, we can only speculate that the lesions we observed on MRI are indeed microhemorrhages. However, the shape, size and imaging characteristics we identified are consistent with previous reports of microhemorrhages in both humans and dogs (Jouvent, Puy & Chabriat, 2016;Ungvari et al, 2017;Murao, Rossi & Cordonnier, 2013;Bos et al, 2018;Sharma et al, 2018;Fulkerson et al, 2012;Hodshon, Hecht & Thomas, 2014;Kerwin et al, 2017). What could be causing microhemorrhages in dogs?…”

“…Therefore, we can reasonably hypothesize that the microhemorrhages in our cohorts might be the result of cerebral amyloid angiopathy. Similar microhemorrhages in people are characteristic for cerebral amyloid angiopathy, the diagnosis of which generally relies upon MRI findings and supporting clinical features (Sharma et al, 2018;Yamada, 2015;Boulouis, Charidimou & Greenberg, 2016;Smith, 2018). Indeed, according to the Boston criteria for diagnosing human cerebral amyloid angiopathy, supportive clinical data and MRI evidence of microhemorrhages, combined with the absence of any other identifiable cause for hemorrhage, supports a diagnosis of "probable cerebral amyloid angiopathy" in the dogs in our study (Yamada, 2015;Boulouis, Charidimou & Greenberg, 2016;Chardimou et al, 2017;Charidimou, 2015;Caetano et al, 2018).…”

“…or associated intracranial reason (e.g., tumor, inflammatory brain disease, etc.) for intracranial bleeding (Sharma et al, 2018;Yamada, 2015;Boulouis, Charidimou & Greenberg, 2016;Kerwin et al, 2017).…”

“…These microhemorrhages can also occur as a result of cerebral amyloid angiopathy, which is a specific cerebral vasculopathy of geriatric humans caused by the accumulation of β-amyloid protein in vessel walls of brain arterioles and capillaries. Microbleeds are often detected by MRI in geriatric human patients with a variety of underlying brain disorders, including Alzheimer's disease and cerebral amyloid angiopathy and in 5-15% of geriatric humans, as incidental findings (Jouvent, Puy & Chabriat, 2016;Ungvari et al, 2017;Murao, Rossi & Cordonnier, 2013;Bos et al, 2018;Sharma et al, 2018). Microbleeds in humans appear on MRI as circular, ovoid or "dot-like" parenchymal lesions, best identified with T2 Ã gradient echo or susceptibility-weighted MR sequences.…”

“…Microbleeds in humans appear on MRI as circular, ovoid or "dot-like" parenchymal lesions, best identified with T2 Ã gradient echo or susceptibility-weighted MR sequences. Although there is some variability in the literature concerning what constitutes a microhemorrhage, most reports include lesions that are less than 5.0 mm in diameter (Jouvent, Puy & Chabriat, 2016;Ungvari et al, 2017;Murao, Rossi & Cordonnier, 2013;Bos et al, 2018;Sharma et al, 2018). Pathologists have identified both cerebral amyloid angiopathy and cerebral microbleeds in geriatric dogs (Uchida, Nakayama & Goto, 1991;Shimada et al, 1992;Wegiel et al, 1995;Yoshino et al, 1996;Colle et al, 2000;Jakel et al, 2017;Rodrigues et al, 2018), and clinicians have described putative microhemorrhages in geriatric dogs undergoing MRI (Fulkerson et al, 2012;Hodshon, Hecht & Thomas, 2014;Kerwin et al, 2017).…”