This version of this article includes supplemental content. Patient information: See related handout on stroke and transient ischemic attack , written by the authors of this article. Stroke can be categorized as ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. Awakening with or experiencing the abrupt onset of focal neurologic deficits is the hallmark of ischemic stroke diagnosis. Taking a detailed history and performing ancillary testing will usually exclude stroke mimics.
Curr Opin Neurol. Popular in: Stroke Stroke study findihgs mouth bacteria in brain clots. On the right the diffusion-perfusion mismatch Mri brain stroke findings adult indicated in blue. So hyperintensity means BAD news: dead brain. MCA infarction: on CT an area of hypoattenuation appearing within six hours is highly specific for irreversible ischemic brain damage. Earn up to 6 CME credits per issue. Monkeys: Past social stress impacts genes, health.
Polyester lace cami. CT Early signs of ischemia
The molar tooth sign. Harlequin appearance Harlequin appearance of the orbit represents the elevation of the superolateral angle of the orbit along with a flat frontal Door swings on a plain stroie [Figure 19A — C ]. The tau sign. Figure 3 A—B. Salt and pepper sign. MRI detected one possibly malignant primary brain tumor -- a low-grade glioma -- and one case of multiple cerebral metastases in a stroe who had previously been treated for lung cancer. Action Points Explain to interested patients Mri brain stroke findings adult this study suggests that incidental findings with brain MRI adulr to be common even in otherwise healthy adults. Histopathology of occluded arteries in moya moya disease shows endothelial hyperplasia and fibrosis without inflammatory reaction. The focus of the discussion is on the cause of the appearance of these signs, the reliability and sensitivity of the signs, and the differential diagnoses to be considered when they are encountered on imaging. Some sequences for example, diffusion-weighted Mri brain stroke findings adult are particularly useful for detecting abnormalities in the first few hours after ischemic stroke. This sign has been traditionally considered as highly specific for tindings.
Hemorrhage on MR images can be quite confusing.
- Ever wonder if an MRI, which is often given to those suspected of having a stroke, can actually miss evidence of the stroke?
- MRI is a test that produces very accurate pictures of the brain and its arteries without x-rays or dyes.
This version of this article includes supplemental content. Patient information: See related handout on stroke and transient ischemic attack , written by the authors of this article.
Stroke can be categorized as ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. Awakening with or experiencing the abrupt onset of focal neurologic deficits is the hallmark of ischemic stroke diagnosis. Taking a detailed history and performing ancillary testing will usually exclude stroke mimics. Neuroimaging is required to differentiate ischemic stroke from intracerebral hemorrhage, as well as to diagnose entities other than stroke.
The choice of neuroimaging depends on its availability, eligibility for acute stroke interventions, and the presence of patient contraindications. Public education of common presenting stroke symptoms is needed for patients to activate emergency medical services as soon as possible after the onset of stroke. The symptoms of stroke can sometimes be misleading and misinterpreted by physicians and patients.
Family physicians are on the front line in their communities to recognize and manage acute cerebrovascular diseases. Accurate and prompt evaluation of cerebrovascular disease will increase eligibility of patients to receive acute therapy for stroke. Patients with an abrupt onset of a focal persistent neurologic deficit should be evaluated for stroke. Diagnostic tools, such as the Recognition of Stroke in the Emergency Room scale, can aid in stroke diagnosis. All patients with stroke should have urgent neuroimaging with computed tomography or magnetic resonance imaging.
Patients and family members should be educated about stroke symptoms and the need for urgent evaluation. Stroke can be subclassified by pathologic process and the vascular distribution affected. Defining the overall pathologic process is critical for decisions regarding thrombolysis, inpatient therapy, and prognosis. In the United States, 87 percent of all strokes are ischemic secondary to large-artery atherosclerosis, cardioembolism, small-vessel occlusion, and other or undetermined causes.
Clinical determination of the affected vascular territory may aid rational evaluation and individualization of therapy. Combination of new higher cerebral dysfunction e. Pure motor or pure sensory symptoms, sensorimotor stroke, or ataxic hemiparesis; face-arm and arm-leg syndromes included. Information from reference 6. History and physical examination remain the pillars of diagnosing stroke.
Moderate to excellent 0. Fair to excellent 0. Poor to excellent 0. Information from references 4 , 8 , and 9. Physicians need to quickly assess persons with suspected acute ischemic stroke because acute therapies for stroke have a narrower time window of effectiveness than therapies for myocardial infarction.
The exact time of symptom onset is critical for determining eligibility for thrombolysis. However, a community-based study found that examiners agreed to the minute less than 50 percent of the time, 4 suggesting the need to corroborate time of symptom onset with a witness or known event.
Reliably distinguishing between intracerebral hemorrhage and ischemic stroke can only be done through neuroimaging. Both entities are characterized by acute onset of focal symptoms. Persons with intracerebral hemorrhage may have gradual worsening of symptoms after the abrupt onset, reflecting an increasing size of the hematoma. Persons with hemorrhage also may have a decreased level of consciousness. Subarachnoid hemorrhage presents differently from intracerebral hemorrhage and ischemic stroke.
Table 3 describes operating characteristics for several validated stroke diagnostic tools. No head-to-head trials have been performed to demonstrate improved patient outcomes using a validated stroke scale versus global clinical impression. Cincinnati Prehospital Stroke Scale Face, Arm, Speech Test Melbourne Ambulance Stroke Screen Recognition of Stroke in the Emergency Room scale 8. Information from references 8 , 9 , and 15 through Physicians need to consider a broad differential diagnosis when evaluating a patient presenting with a suspected stroke Table 4.
History of loss of consciousness, seizure activity, or postictal state 14 , May be related to alcohol intoxication, medication adverse effect, or other encephalopathy.
History of similar events, preceding aura and headache Reported incidence is 0. Presence of known cognitive impairment was one of two factors that independently predicted a stroke mimic in an Australian prospective study of patients admitted with suspected stroke Information from references 8 , 11 , 14 , and 20 through One potential area of confusion is among patients presenting with a symptom of dizziness. In a population-based study of adults older than 44 years presenting to the emergency department or directly admitted to the hospital with a principal symptom of dizziness, only 0.
The rates of overdiagnosis of stroke in studies of consecutive patients vary from 19 to 31 percent. Duration of symptoms distinguishes stroke from TIA, which has been traditionally defined as a focal ischemic neurologic event resolving within 24 hours.
Subsequent observations have shown that a majority of TIAs resolve within one hour. Figure 1 presents an algorithm for the diagnosis of acute stroke. Information from references 2 , 4 , and Lumbar puncture if subarachnoid hemorrhage suspected and head CT negative for blood. The primary purpose of neuroimaging in a patient with suspected ischemic stroke is to rule out the presence of other types of central nervous system lesions and to distinguish between ischemic and hemorrhagic stroke.
Figure 2 shows examples of intracerebral and sub-arachnoid hemorrhages on computed tomography CT scans. CT scans are considered sufficiently sensitive for detecting mass lesions, such as a brain mass or abscess, as well as detecting acute hemorrhage. However, CT scans may not be sensitive enough to detect an ischemic stroke, especially if it is small, acute, or in the posterior fossa i.
In other words, a normal CT scan does not rule out the diagnosis of ischemic stroke. Head computed tomography CT scans showing A intracerebral hemorrhages arrows and B subarachnoid hemorrhages arrows. Note that acute hemorrhage appears hyperdense white on a CT scan. Multimodal magnetic resonance imaging MRI sequences, particularly diffusion-weighted imaging, have better resolution than CT; therefore, they have a greater sensitivity for detecting acute ischemic stroke and show ischemic lesions in about one half of all cases of TIA.
Figure 4 depicts the time course of resolution of ischemic changes on diffusion-weighted MRI. A Noncontrast computed tomography CT scan showing two hypodense regions indicating old infarctions in the distribution of the left-middle cerebral long arrow and posterior cerebral arteries short arrow. B Diffusion-weighted magnetic resonance imaging scan obtained shortly after the CT reveals a new extensive infarction arrow in the right-middle cerebral artery distribution not evident on the CT.
Time course of diffusion-weighted imaging abnormalities. Diffusion-weighted imaging can detect ischemic stroke arrow in the very early period six-hour image. Lesions typically reach maximum intensity three to five days after stroke onset as shown in the hour image , then typically fade over one to four weeks abnormality still visible in seven-day image, but has disappeared in the day image. Diffusion-weighted MR imaging of the brain. Also, MRI scans cannot be performed on persons with certain types of implanted devices e.
Typically less available and can be done less quickly than CT; if patients are eligible for acute thrombolysis, MRI should only be conducted if it is as available as CT; treatment should not be delayed because of time needed to obtain an MRI. Less resolution than MRI, but sufficient to assess for ischemic stroke mimics such as a mass, abscess, or hemorrhage including subarachnoid ; detects subacute strokes of at least moderate size. Greater resolution than CT for all ischemic stroke mimics except for subarachnoid not as well studied ; diffusion-weighted imaging sequence detects acute, small strokes that may go undetected by CT, and can distinguish between acute and older strokes.
Contraindicated for anyone with metal in the body e. Unlike ischemic stroke and intracerebral hemorrhage, diagnosing subarachnoid hemorrhage requires a different diagnostic algorithm. The frequency of mis-diagnosis for subarachnoid hemorrhage can be as high as 50 percent on initial presentation.
Persons with suspected subarachnoid hemorrhage and a normal CT scan should undergo a lumbar puncture to detect bilirubin. Red blood cells can be found in a sub-arachnoid hemorrhage and a traumatic tap. Distinguishing between these two entities requires recognition that only within the human body do red blood cells break down into bilirubin.
Red blood cells in cerebrospinal fluid collected from a traumatic tap will break down into oxyhemoglobin, but not into bilirubin. Because the breakdown of red blood cells can take up to 12 hours, guidelines recommend that the lumbar puncture should wait until 12 hours after the initial onset of symptoms.
If subarachnoid hemorrhage is detected, the patient should immediately undergo angiography CT angiography, MRI angiography, or catheter angiography to look for an aneurysm. Guidelines recommend that persons having an acute stroke activate the emergency medical system by calling Such behavior accounts for up to two thirds of the delay to hospital admission. Numerous surveys have shown that there is considerable room for improvement in knowledge of stroke in the general population.
Already a member or subscriber? Log in. Address correspondence to Kenneth S. Reprints are not available from the authors. Author disclosure: Dr. The authors thank Dr. Jack Tsao for providing Figure 2 and Dr. James Smirniotopoulos for his assistance with Figure 3. The views expressed in this article are those of the authors and do not necessarily reflect the official position of the Department of the Navy, Department of Defense, Department of Veterans Affairs or the United States Government. Heart disease and stroke statistics— update: a report from the Ameri Statistics Subcommittee.
Classification of subtype of acute ischemic stroke.
Optic glioma arises from glial cells within the optic nerve and there is no clear separation between the nerve and the tumor; hence the tram-track sign is not seen in optic gliomas [ Figure 10B ]. MRI shows symmetric increased signal in the periventricular white matter, with initial sparing of the subcortical U fibers [ Figure 16B ]. Reversal sign This sign is seen on CT scan images and represents a diffuse decrease in the density of the cerebral hemispheres, with loss of gray-white differentiation and a relative increase in the density of the thalami, brainstem, and cerebellum [ Figure 7 ]. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Sagittal orientation: in a slice dividing the head into left and right halves. Mutation of the gene for pantothenate kinase 2 is the cause for the syndrome. The disease is progressive, with gait abnormality, quadriplegia, decerebration, and death by the age of 6 months to 4 years.
Mri brain stroke findings adult. Introduction
Although intravenous administration of tissue plasminogen activator is the only proven treatment after acute ischemic stroke, there is always a concern of hemorrhagic risk after thrombolysis. Therefore, selection of patients with potential benefits in overcoming potential harms of thrombolysis is of great importance. Despite the practical issues in using magnetic resonance imaging MRI for acute stroke treatment, multimodal MRI can provide useful information for accurate diagnosis of stroke, evaluation of the risks and benefits of thrombolysis, and prediction of outcomes.
For example, the high sensitivity and specificity of diffusion-weighted image DWI can help distinguish acute ischemic stroke from stroke-mimics. Additionally, the lesion mismatch between perfusion-weighted image PWI and DWI is thought to represent potential salvageable tissue by reperfusion therapy.
However, the optimal threshold to discriminate between benign oligemic areas and the penumbra is still debatable. Signal changes of fluid-attenuated inversion recovery image within DWI lesions may be a surrogate marker for ischemic lesion age and might indicate risks of hemorrhage after thrombolysis. Clot sign on gradient echo image may reflect the nature of clot, and their location, length and morphology may provide predictive information on recanalization by reperfusion therapy.
However, previous clinical trials which solely or mainly relied on perfusion-diffusion mismatch for patient selection, failed to show benefits of MRI-based thrombolysis. Ischemic stroke is one of the major causes of death and disability. For the last few decades, many efforts have been made to improve the outcome of acute ischemic stroke treatment.
However, thrombolytic therapy is still the only proven treatment for patients following an acute ischemic stroke within 3 or 4. Multimodal magnetic resonance imaging MRI is useful for diagnosing ischemic stroke and for determining treatment strategies in the acute phase. Lesion mismatch profiles on MRI help us to assess potential risks and benefits of thrombolysis by providing information on salvageable tissue or ischemic lesion age.
While simply using a few parameters may be easily applicable, other valuable information for diagnosing stroke, determining the mechanism, and assessing the potential risks and benefits may be overlooked. Therefore, it is critical to understand the clinical implication of various imaging findings, and comprehensively consider them before deciding the treatment for acute stroke.
In this review, we discuss the clinical implication of various MRI findings, specifically focusing on 1 MRI for diagnosis of acute stroke and its mechanism, 2 MRI-based patient selection for reperfusion therapy, 3 MRI outcome measures, and 4 the practicality of using MRI for hyperacute stroke.
Diagnosis of stroke largely depends on clinical presentation. The lesions appear as hyperintense areas on DWI and as correlative hypointense areas on apparent diffusion coefficient ADC maps, even within 3 minutes of stroke onset. However, the small lesions located at the brain stem that present mild symptoms, especially ataxic hemiparesis or intranuclear ophthalmoplegia, could be invisible on initial DWI. Common stroke mimics, identified in a systematic review and meta-analysis of case series.
Many studies have attempted to unravel stroke pathomechanism by ischemic lesion topography on DWI. It has been reported that multiple lesions in the unilateral anterior circulation or small, scattered lesions in one vascular territory are related to large artery atherosclerosis Figure 2A, B. Fluid-attenuated inversion recovery FLAIR image demonstrate subacute or chronic ischemic lesions, which may help in classifying the subtype of index stroke.
DWI lesion patterns according to stroke subtypes. A Intracranial atherosclerotic stenosis, B extracranial atherosclerotic stenosis, C cardioembolism, and D aortic arch embolism. Cardioembolism can be suspected when patients exhibit acute multiple territorial lesions 21 or a single large cortical and subcortical lesion on DWI.
When the cerebral blood vessel is occluded, a complex series of pathophysiological events evolve in time and space. However, the surrounding part of the core still exhibits minimum blood flow supplied by collateral circulation, even when neuronal function has been suspended ischemic penumbra.
The neuronal function of some parts of the ischemic penumbra can recover when blood supply is restored, and goes through a dynamic change during the acute period of ischemic stroke.
PWI is a semi-quantitative method for evaluating brain perfusion - microcirculation in the capillary network. The variation of signal intensity is measured during 1 minute, serially with 1- to 2-second intervals by the echo-planar image technique.
From this data, time-concentration curves can be obtained at the tissue level, voxel-by-voxel Figure 3B. After deconvolution with arterial input functions, a deconvolved curve can be obtained Figure 3C , and various perfusion parameters can be calculated. CBF is a parameter usually taken at the height of deconvolved curve Figure 3C.
CBV is measured by the whole blood quantity within the target area area under the deconvolved curve; Figure 3C. Areas of decreased CBV correlate well with the final size of a cerebral infarction. MTT is the average time required for blood flow to enter the artery and maintain the inside of the cerebral artery. If an area with MTT delay shows increased CBV, that area may have received sufficient collateral circulation or may have been currently recanalized.
TTP is an indirect measurement of brain perfusion; therefore, it provides minimum information. Since a delay in TTP can occur in a patient with chronic carotid artery stenosis without acute infarction prolonged arrival time , TTP can also overestimate the hypo-perfused area in an acute infarction. Tmax is the time it takes for the tissue residue function to reach its maximum value.
Tmax is a sensitive parameter reflecting changes of brain tissue into an infarction and changes in the perfusion state. Tmax has also been used as a predictor of tissue viability in many studies as a non-physiological parameter of the capability of brain tissue to survive. Since this parameter is not influenced by scan duration, Tmax has the merit that sufficient scanning for a long time is possible so that contrast agent can reach all parts.
Recent studies have focused on the threshold for distinguishing a true penumbra from a benign oligemia. Although time-based perfusion variables are widely used methods assessing penumbra, there are still a lot of controversies on interpreting them. Previously, many different thresholds for Tmax representing the true penumbra area have been suggested. Taken together, these studies indicate that there is no established criterion to discriminate between benign oligemic area and the penumbra.
Although a number of studies have been conducted on Tmax threshold for that purpose, there are still a lot of controversies on the optimum criterion since the threshold value to determine the final infarction varies from study by study. Previously, PWI-DWI mismatch was used for patient selection in several clinical trials focusing on acute stroke treatment. The primary outcome measure was the attenuation of infarct growth using a ratio of geometric means.
These failures however, have reinforced the benefit of salvaging the penumbral tissue by thrombolysis, and the fact that HT risk should be considered when deciding to treat a patient via thrombolysis.
HT is a frequent, often asymptomatic event that occurs after acute ischemic stroke. It is thought to negatively influence the early clinical course and outcome of patients, particularly those receiving thrombolytic therapy.
Irrespective of other features, detection of any blood by CT in a patient with neurological deterioration qualified the patient for symptomatic HT. Several factors are known to be associated with HT, and the combination of clinical and imaging data helps identify patients at high risk of symptomatic HT.
The imaging data indicative of a large infarct 54 and early ischemic signs on CT are also widely used as exclusion criteria for thrombolytic therapy. However, the sensitivity and reproducibility of early ischemic signs on brain CT is poor. Although their presence on GRE has been suggested to be predictive of increased HT risk after treatment with tPA, 59 data from a large cohort study indicated that micro-hemorrhages were not an independent risk factor for early and symptomatic HT, irrespective of the number of microbleeds.
Considering the pathomechanism of HT, radiological markers that directly indicate blood-brain barrier permeability could predict HT after acute ischemic stroke. In fact, it has been shown that contrast-enhancement can predict tPA-induced hemorrhages in rat models. MRI markers predicting hemorrhagic transformation A Delayed gadolinium enhancement of the CSF space arrows ; B Parenchymal enhancement at post contrast T1-weighted image arrow and hemorrhagic transformation at the corresponding area at follow-up arrow.
Magnetic susceptibility artifacts distort ferromagnetic objects. Technically, shortening the echo-time, increasing the frequency matrix, and decreasing the slice thickness could reduce artifact size. On the other hand, magnetic susceptibility artifacts may also enhance the detection of red thrombi clots, which are ferromagnetic. As the composition, size, and site of clot occluding cerebral arteries are important factors for selecting the treatment strategy, GRE and SVS may be useful for treatment decisions.
Therefore, SVS is known as a marker with higher possibility of recanalization. Third, the clot length is typically used to quantify the thrombotic burden.
Clot presented on gradient echo image arrow with long segment A and tortuous vessel B. Physicians are frequently confronted with patients in whom the exact time of stroke symptom onset is not known, 74 and attempts have been made to use signal changes in FLAIR images as a kind of "tissue clock".
The water content rises due to vasogenic edema as the blood-brain barrier is disrupted, and occurs within 1 to 4 hours of stroke onset. In addition to the time from symptom onset, younger age and large ischemic lesion volume have been reported to be associated with high FLAIR signal intensity. For example, in a previous study it was reported that the inter-rater reliability of FLAIR change was only moderate, based on visual rating.
Table 1 introduces these major on-going clinical trials. On-going clinical trial to expand the time-window of intra-venous thrombolysis. One-third of acute ischemic strokes that have occurred within the therapeutic time window have been excluded because of mild or rapidly improving symptoms. MRI has been suggested as a tool to identify patients with minor stroke who may benefit from thrombolysis.
In patients that have experienced a minor stroke, a significant mismatch can persist for days and their symptoms may aggravate without recanalization therapy. Thus, only the inclusion of patients with minor stroke in future randomized controlled trials of intravenous thrombolysis will allow us to answer the question of whether thrombolysis is effective and safe in this group of patients.
Clinical trials evaluating the success of thrombolysis have relied on various outcome parameters to measure how well an ischemic vascular bed responds to treatment. However, as these clinical parameters are influenced by various confounders, including the lesion location or patient age, they do not directly demonstrate the treatment effect of salvaging the penumbral tissue. Currently, there is no consensus on how to determine infarct growth.
Two distinct measures for assessing recanalization have been used to evaluate the effectiveness of thrombolytic therapy. First, recanalization of the primary arterial occlusive lesion has been evaluated using the Arterial Occlusive Lesion AOL grading system. However, the use of multiple scales has resulted in some confusion and limits the comparison among studies. However, recanalization of the primary arterial occlusive lesion does not guarantee complete reperfusion of the downstream arterioles.
The TIMI definition, which has been used to describe flow in the coronary arteries, was adapted to evaluate the degree of reperfusion. While there are some limitations of angiography based scales, combining the scales with MR perfusion may be a good parameter for treatment outcome. It is important to ask whether MRI parameters are correlated with clinical outcomes.
In fact, it has been shown that early infarct growth within the first week can predict long-term clinical outcome after thrombolysis. Multimodal MRI reveals various useful parameters for deciding treatment routes of acute stroke Table 3. This technology is especially useful when stroke diagnosis is uncertain stroke-mimics , stroke onset is unclear wake-up or unwitnessed daytime strokes , or clinic-imaging mismatches exist. In addition, various new MRI advancements are actively under research, such as arterial spin labeling, techniques to measure collateral flows, computational flow dynamics, and high-resolution vessel-wall MRI.
These novel imaging biomarkers may be helpful in determining the treatment strategy for acute ischemic stroke. Multimodal imaging provides information that is useful for diagnosing ischemic stroke, selecting appropriate patients for thrombolytic therapy, and predicting the prognosis of ischemic stroke. Only depending on a single or a few parameters may not be sufficient, instead comprehensively combining the information from each MRI sequence i.
The authors have no financial conflicts of interest. National Center for Biotechnology Information , U.