Detection of hemorrhage in acute cerebral infarction. Evaluation with spin-echo and gradient-echo MRI

Clinical significance of intracranial hemorrhage after thrombectomy detected solely by magnetic resonance imaging and not by computed tomography

BACKGROUND AND OBJECTIVE

Whether intracranial hemorrhage (ICH) detected using magnetic resonance imaging (MRI) affects the clinical outcomes of patients with large-vessel occlusion (LVO) treated with mechanical thrombectomy (MT) remains unclear. This study investigated the clinical features of ICH after MT detected solely by MRI.

METHODS

This was a retrospective analysis of patients with acute ischemic stroke and occlusion of the internal carotid artery or middle cerebral artery treated with MT between April 2011 and March 2021. Among 632 patients, patients diagnosed with no ICH using CT, with a pre-morbid modified Rankin Scale (mRS) score ≤ 2, and those who underwent MRI including T2* and computed tomography (CT) within 72 h from MT were enrolled. The main outcomes were the association between ICH detected solely by MRI and clinical outcomes at 90 days. Poor clinical outcomes were defined as mRS score > 2 at 90 days after onset.

RESULTS

Of the 246 patients, 29 (12%) had ICH on MRI (MRI-ICH(+)), and 217 (88%) were MRI-ICH(-). There was no significant difference between number of patients with MRI-ICH(+) experiencing poor (10 [12%]) and favorable (19 [12%]) outcomes. The mRS score at 90 days between patients with MRI-ICH (+) and MRI-ICH(-) was not significantly different (2 [1-4] vs. 2 [1-4], respectively). Higher age and lower ASPECTS were independent risk factors for poor outcomes, as shown by multivariate regression analysis. MRI-ICH(+) status was not associated with poor outcomes.

CONCLUSIONS

ICH detected by MRI alone did not influence clinical outcomes in patients with LVO treated with MT.

Magnetic resonance imaging versus computed tomography for detection of acute vascular lesions in patients presenting with stroke symptoms

BACKGROUND

Magnetic resonance imaging (MRI) is increasingly used for the diagnosis of acute ischaemic stroke but its sensitivity for the early detection of intracerebral haemorrhage has been debated. Computed tomography (CT) is extensively used in the clinical management of acute stroke, especially for the rapid exclusion of intracerebral haemorrhage.

OBJECTIVES

To compare the diagnostic accuracy of diffusion-weighted MRI (DWI) and CT for acute ischaemic stroke, and to estimate the diagnostic accuracy of MRI for acute haemorrhagic stroke.

SEARCH STRATEGY

We searched MEDLINE and EMBASE (January 1995 to March 2009) and perused bibliographies of relevant studies for additional references.

SELECTION CRITERIA

We selected studies that either compared DWI and CT in the same patients for detection of ischaemic stroke or examined the utility of MRI for detection of haemorrhagic stroke, had imaging performed within 12 hours of stroke onset, and presented sufficient data to allow construction of contingency tables.

DATA COLLECTION AND ANALYSIS

Three authors independently extracted data on study characteristics and measures of accuracy. We assessed data on ischaemic stroke using random-effects and fixed-effect meta-analyses.

MAIN RESULTS

Eight studies with a total of 308 participants met our inclusion criteria. Seven studies contributed to the assessment of ischaemic stroke and two studies to the assessment of haemorrhagic stroke. The spectrum of patients was relatively narrow in all studies, sample sizes were small, there was substantial incorporation bias, and blinding procedures were often incomplete. Amongst the patients subsequently confirmed to have acute ischaemic stroke (161/226), the summary estimates for DWI were: sensitivity 0.99 (95% CI 0.23 to 1.00), specificity 0.92 (95% CI 0.83 to 0.97). The summary estimates for CT were: sensitivity 0.39 (95% CI 0.16 to 0.69), specificity 1.00 (95% CI 0.94 to 1.00). The two studies on haemorrhagic stroke reported high estimates for diffusion-weighted and gradient-echo sequences but had inconsistent reference standards. We did not calculate overall estimates for these two studies. We were not able to assess practicality or cost-effectiveness issues.

AUTHORS' CONCLUSIONS

DWI appears to be more sensitive than CT for the early detection of ischaemic stroke in highly selected patients. However, the variability in the quality of included studies and the presence of spectrum and incorporation biases render the reliability and generalisability of observed results questionable. Further well-designed studies without methodological biases, in more representative patient samples, with practicality and cost estimates are now needed to determine which patients should undergo MRI and which CT in suspected acute stroke.

Imaging of hemorrhagic stroke

Neuroimaging by CT or MR is necessary for the detection of hemorrhagic stroke and provides important data regarding the cause of stroke. Serial changes in the CT and MR appearance of hematoma attributable to temporal evolution must be assessed to assure accurate diagnosis. Emerging evidence suggests that the use of MR imaging alone may be adequate for identifying hemorrhage in acute stroke patients and that GRE MR imaging is superior to both CT and conventional spin-echo MR imaging sequences for the detection of chronic microbleeds and hemorrhagic conversion of infarction.

Hemorrhagic stroke

Neuroimaging by CT or MR imaging is necessary for the identification of hemorrhagic stroke and provides information about its cause. The appearance of intracranial hematoma (ICH) on CT and MR imaging evolves over time and must be understood to facilitate accurate diagnosis. The cause of ICH varies by location. New evidence suggests that MR imaging alone may be adequate to identify hemorrhagic stroke in the acute setting, and that MR imaging is superior to CT for identification of chronic microbleeds and hemorrhagic conversion of infarction.

Frequency and risk factors for spontaneous hemorrhagic transformation of cerebral infarction

OBJECTIVE

Hemorrhagic transformation of cerebral infarction (HTI) occurs spontaneously but its frequency and risk factors are uncertain with mixed results in previous studies. We aimed to determine the overall frequency of and risk factors for HTI.

METHODS

We performed a systematic review according to Cochrane Collaboration methods of published reports of HTI with reliable, systematic follow-up with computed tomography or magnetic resonance imaging.

RESULTS

In all, 28 observational studies and 19 randomized controlled trials in stroke were identified that included follow-up imaging data. Problems with inconsistent definitions or small and biased patient populations limited detailed interpretation. The overall frequency of any HTI in untreated patients was 8.5% (95% confidence interval 7%-10%). Severe HTI (i.e., HTI accompanied by neurologic deterioration or parenchymal hematoma formation) occurred in 1.5% (95% confidence interval 0.8%-2.2%). The frequency of HTI increased markedly with increasing use of antithrombotic or thrombolytic drugs. Magnetic resonance imaging detected more HTI than did computed tomography. The published data were generally inadequate to undertake more detailed analysis of risk factors. However, in the 8 studies that did provide the information, HTI was associated with large infarcts, mass effect, hypodensity observed early after the stroke, and age older than 70 years, but not hypertension or cardioembolic stroke.

CONCLUSIONS

Severe HTI is uncommon in patients not receiving antithrombotic or thrombolytic agents. The methods used to assess the frequency of and risk factors for HTI, particularly a standard of definitions in future prospective studies, could be improved.

Diagnostic imaging for intracerebral hemorrhage

Magnetic resonance imaging (MRI) is an excellent tool for the diagnosis and evaluation of intracerebral hemorrhage with its unique specificity to hemoglobin degradation products in different stages. Computed tomography (CT) remains the diagnostic test of choice in the setting of acute intracerebral hemorrhage because of its exquisite sensitivity and specificity for small amounts of intracerebral hemorrhage (although there is emerging evidence that MRI may be as sensitive as CT). The effects of the biochemical evolution of intracerebral hemorrhage on the temporal MRI signal changes are described. This article discusses imaging features of the common causes of intracerebral hemorrhage.

Magnetic resonance imaging of cerebral hemorrhagic stroke

Despite a traditional perception of reliance on computed tomography and lack of acceptance of magnetic resonance imaging (MRI) for detecting acute hemorrhage, MRI appears to be used increasingly in hemorrhagic stroke. This review addresses the MRI findings of acute hemorrhagic stroke obtained using relatively new imaging techniques. These new techniques have resulted in more acute stroke patients undergoing MRI examination. New information about the frequency and appearance of hemorrhage is emerging: for example, approximately 15-26% of cases of acute cerebral infarctions appear to be complicated by intracerebral hemorrhage. The MRI appearances of hemorrhagic transformation of ischemic infarction, as well as acute hypertensive intracerebral hemorrhage, are discussed based on clinical, biochemical, and technical aspects.

Diagnostic evaluation of stroke

Diagnostic testing in patients with ischemic stroke serves many purposes, including confirmation of the diagnosis and providing clues as to possible causes. Evaluation of the cerebral vasculature, the heart, the blood coagulation system, and selected other diagnostic tests may point to a mechanism of stroke which helps determine treatment and prognosis. With the recent advent of acute interventions for ischemic stroke, diagnostic testing is now an important component in the emergency management of stroke. In this article, the authors will review the standard approach to diagnostic testing for patients with ischemic stroke or transient ischemic attack, and new developments in neuro-imaging and their use in acute stroke assessment.

Utility of magnetic resonance imaging in acute intracerebral hemorrhage

The authors determine whether magnetic resonance imaging (MRI) during acute hospitalization for spontaneous intracerebral hemorrhage (ICH) provides new diagnostic information. ICD-9 codes were used to identify consecutive patients with spontaneous ICH at Hermann Hospital, Houston, Texas, between January 1995 and August, 1997. Two investigators employed rigorous criteria to determine whether the MRI findings led to a specific new diagnosis. Two hundred ninety-one patients met inclusion and exclusion criteria. Sixty-seven (23%) patients underwent brain MRI during the acute hospitalization. MRI provided a new diagnosis in 15 of these 67 patients (22%). Amyloid angiopathy and vascular malformation (four each) were the most frequently identified etiologies. The yield of MRI was low in basal ganglia and thalamic hemorrhage. Two of 23 (9%) patients with deep ICH and 13 of 44 (30%) patients with lobar and infratentorial hemorrhage had etiology determined by MRI. Timing of MRI did not affect yield.

Imaging of acute cerebral ischemia

Until recently, there was no efficacious treatment for acute cerebral ischemia. As a result, the role of neuroimaging and the radiologist was peripheral in the diagnosis and management of this disease. The demonstration of efficacy using thrombolysis has redefined this role, with the success of intervention becoming increasingly dependent on timely imaging and accurate interpretation. The potential benefits of intervention have only begun to be realized. In this State-of-the-Art review of imaging of acute stroke, the role of imaging in the current and future management of stroke is presented. The role of computed tomography is emphasized in that it is currently the most utilized technique, and its value has been demonstrated in prospective clinical trials. Magnetic resonance techniques are equally emphasized in that they have the potential to provide a single modality evaluation of tissue viability and vessel patency in an increasingly rapid evaluation.

Diffusion-weighted magnetic resonance imaging characteristics of hemorrhagic transformation in experimental embolic stroke

Diffusion-weighted magnetic resonance imaging (MRI) can detect ischemia within minutes of onset, but its ability to reliably detect hyperacute cerebral hemorrhage is unknown. The present study characterized diffusion-weighted, T2-weighted, and contrast-enhanced T1-weighted MRI appearances of hemorrhagic transformation within 5 hours of onset in experimental embolic stroke. Apparent diffusion coefficients and MRI signal characteristics were noted within corresponding regions of hemorrhage observed on gross pathology. Apparent diffusion coefficients were significantly increased within hemorrhagic lesions, but were still within the expected range for bland ischemia. The appearance of the hemorrhagic lesions on diffusion-weighted MRI was also very heterogeneous and not very useful for clinical screening. Other MRI modalities should be investigated, but computed tomography remains the only widely available clinical method of reliably detecting cerebral hemorrhage.

Computed tomography-negative acute thalamic hematoma

A case of acute thalamic hematoma not detected by computed tomography (CT) but unequivocally diagnosed by magnetic resonance imaging (MRI) is presented. A 79-year-old woman presented with acute left hemiparesis. The results of CT obtained on admission as well as on the seventh hospital day were negative for a hematoma. By contrast, serial MRIs exhibited chronological changes in the relaxation properties characteristics of acute hematoma in the thalamus. The case illustrates that contrary to widespread practice, CT cannot absolutely be relied on for the detection of acute intracerebral hematoma.