Remote Diffusion-Weighted Imaging Lesions and Intracerebral Hemorrhage: A Systematic Review and Meta-Analysis.

BACKGROUND: Remote diffusion-weighted imaging lesions (RDWILs) in the context of spontaneous intracerebral hemorrhage (ICH) are associated with an increased risk of recurrent stroke, worse functional outcome, and death. To update current knowledge on RDWILs, we conducted a systematic review and meta-analysis of the prevalence, associated factors and presumed causes of RDWILs. METHODS: We searched Pubmed, Embase, and Cochrane up to June 2022 for studies reporting RDWILs in adults with symptomatic ICH of no-identified-cause, assessed by magnetic resonance imaging, and analyzed associations between baseline variables and RDWILs in random-effects meta-analyses. RESULTS: Eighteen observational studies (7 prospective), reporting 5211 patients were included, of whom 1386 had ≥1 RDWIL (pooled prevalence: 23.5% [19.0-28.6]). RDWIL presence was associated with neuroimaging features of microangiopathy, atrial fibrillation (odds ratio, 3.67 [1.80-7.49]), clinical severity (mean difference in National Institutes of Health Stroke Scale score, 1.58 points [0.50-2.66]), elevated blood pressure (mean difference, 14.02 mmHg [9.44-18.60]), ICH volume (mean difference, 2.78 mL [0.97-4.60]), and subarachnoid (odds ratio, 1.80 [1.00-3.24]) or intraventricular (odds ratio, 1.53 [1.28-1.83]) hemorrhage. RDWIL presence was associated with poor 3-month functional outcome (odds ratio, 1.95 [1.48-2.57]). CONCLUSIONS: RDWILs are detected in approximately 1-in-4 patients with acute ICH. Our results suggest that most RDWILs result from disruption of cerebral small vessel disease by ICH-related precipitating factors such as elevated intracranial pressure and cerebral autoregulation impairment. Their presence is associated with worse initial presentation and outcome. However, given the mostly cross-sectional designs and heterogeneity in study quality, further studies are needed to investigate whether specific ICH treatment strategies may reduce the incidence of RDWILs and in turn improve outcome and reduce stroke recurrence.

Can novel CT-and MR-based neuroimaging biomarkers further improve the etiological diagnosis of lobar intra-cerebral hemorrhage?

Lobar hematomas represent around half of all supratentorial hemorrhages and have high mortality and morbidity. Their management depends on the underlying cause. Apart from local causes such as vascular malformation, which are rare and can usually be easily excluded thanks to imaging, the vast majority of lobar hematomas equally frequently result from either hypertensive arteriolopathy (HA) or cerebral amyloid angiopathy (CAA). Distinguishing between CAA and HA is important for prognostication (risk of recurrence nearly sevenfold higher in the former), for decision-making regarding, e.g., antithrombotic therapies (for other indications) and for clinical trials of new therapies. Currently, a non-invasive diagnosis of probable CAA can be made using the MR-based modified Boston criteria, which have excellent specificity but moderate sensitivity against histopathological reference, leading to the clinically largely irrelevant diagnosis of "possible CAA". Furthermore, the Boston criteria cannot be applied when both lobar and deep MRI hemorrhagic markers are present, a not uncommon situation. Here we propose to test whether new CT and MR-based imaging biomarkers, namely finger-like projections of the hematoma and adjacent subarachnoid hemorrhage on acute-stage CT or MRI, and remote punctate diffusion-weighted imaging ischemic lesions on acute or subacute-stage MRI, have the potential to improve the performance of the Boston criteria. Furthermore, we also propose to test whether clinical-radiological biomarkers may also allow a positive diagnosis of HA to be made in lobar hematomas, which, if feasible, would not only further reduce the prevalence of "possible CAA" but also permit a diagnosis of HA and/or CAA to be made in the presence of mixed deep and lobar MRI hemorrhagic markers.

Diagnostic performance of dynamic 3D magnetic resonance angiography in daily practice for the detection of intracranial arteriovenous shunts in patients with non-traumatic intracranial hemorrhage.

Introduction: Identification of treatable causes of intracranial hemorrhage (ICH) such as intracranial arteriovenous shunt is crucial to prevent recurrence. However, diagnostic approaches vary considerably across centers, partly because of limited knowledge of the diagnostic performance of first-line vascular imaging techniques. We assessed the diagnostic performance of dynamic three-dimensional magnetic resonance angiography (dynamic 3D MRA) in daily practice to detect intracranial arteriovenous shunts in ICH patients against subsequent digital subtraction angiography (DSA) as reference standard. Methods: We reviewed all adult patients who underwent first-line dynamic 3D MRA and subsequent DSA for non-traumatic ICH between January 2016 and September 2021 in a tertiary center. Sensitivity, specificity, accuracy, positive and negative predictive values of dynamic 3D MRA for the detection of intracranial arteriovenous shunt were calculated with DSA as reference standard. Results: Among 104 included patients, 29 (27.9%) had a DSA-confirmed arteriovenous shunt [19 pial arteriovenous malformations, 10 dural arteriovenous fistulae; median onset-to-DSA: 17 (IQR: 3-88) days]. The sensitivity and specificity of dynamic 3D MRA [median onset-to-dynamic 3D MRA: 14 (3-101) h] for the detection of intracranial arteriovenous shunt were 66% (95% CI: 48-83) and 91% (95% CI: 84-97), respectively. The corresponding accuracy, positive and negative predictive values were 84% (95% CI: 77-91), 73% (95% CI: 56-90), and 87% (95% CI: 80-95), respectively. Conclusion: This study suggests that although first-line evaluation with dynamic 3D MRA may be helpful for the detection of intracranial arteriovenous shunts in patients with ICH, additional vascular imaging work-up should not be withheld if dynamic 3D MRA is negative. Comparative prospective studies are needed to determine the best imaging strategy to diagnose arteriovenous shunts after non-traumatic ICH.