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Dating stroke radiology
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It may be of therapeutic and prognostic value to differentiate this hyperdense 'regular' thromboembolic focus from a calcified cerebral embolus. Within the first few hours, a number of signs are visible depending on the site of occlusion and the presence of collateral flow. Early features include:.
With time the hypoattenuation and swelling become more marked resulting in a significant mass effect. This is a major cause of secondary damage in large infarcts. As time goes on the swelling starts to subside and small amounts of cortical petechial hemorrhages not to be confused with hemorrhagic transformation result in elevation of the attenuation of the cortex. This is known as the CT fogging phenomenon 5.
Imaging a stroke at this time can be misleading as the affected cortex will appear near normal. Later still the residual swelling passes, and gliosis sets in eventually appearing as a region of low density with negative mass effect.
Cortical mineralization can also sometimes be seen appearing hyperdense. CT perfusion has emerged as a critical tool in selecting patients for reperfusion therapy as well as increasing the accurate diagnosis of ischemic stroke among non-expert readers four-fold compared to routine non-contrast CT 9.
Stroke: Endovascular management of ischaemic stroke - radiology video tutorial
It allows both the core of the infarct that part destined to never recover regardless of reperfusion to be identified as well as the surrounding penumbra the region which although ischemic has yet to go on to infarct and can be potentially salvaged.
CT perfusion may also demonstrate early evidence of associated crossed cerebellar diaschisis. These factors will be discussed further separately. See CT perfusion. Multiphase or delayed CT angiography is showing benefit either replacing CT perfusion or as an additional 4th step in the stroke CT protocol as it guides patient selection for endovascular therapy by assessing collateral blood flow in ischemic and infarct tissue.
MRI is more time consuming and less available than CT but has significantly higher sensitivity and specificity in the diagnosis of acute ischemic infarction in the first few hours after onset. Within minutes of arterial occlusion, diffusion-weighted imaging demonstrates increased DWI signal and reduced ADC values 4, At this stage, the affected parenchyma appears normal on other sequences, although changes in flow will be detected occlusion on MRA and the thromboembolism may be detected e.
If infarction is incomplete then cortical contrast enhancement may be seen as early as 2 to 4 hours This change continues to increase over the next day or two.
During the first week, the infarcted parenchyma continues to demonstrate high DWI signal and low ADC signal, although by the end of the first week ADC values have started to increase. T1 signal remains low, although some cortical intrinsic high T1 signal may be seen as early as 3 days after infarction Less common patterns of enhancement include arterial enhancement, encountered in approximately half of strokes and becomes evident after 3 days, and meningeal enhancement which is uncommon and is usually seen between 2 and 6 days Hemorrhage, most easily seen on susceptibility weighted imaging SWIis not a good indicator of age.
Although most commonly seen after 12 hours and within the first few days, it may occur earlier or as late as 5 days ADC demonstrates pseudonormalization typically occurring between days As ADC values continue to rise, infarcted tissue progressively gets brighter than normal parenchyma.
T2 fogging is also encountered typically between 1 and 5 weeks, most commonly around week 2 10, Cortical enhancement is usually present throughout the subacute period. T1 signal remains low with intrinsic high T1 in the cortex if cortical necrosis is present T2 signal is high.
Cortical contrast enhancement usually persists for 2 to 4 months Importantly if parenchymal enhancement persists for more than 12 weeks the presence of an underlying lesion should be considered Coronary care units are the cornerstone of post-myocardial infarction MI care.
The development of this type of unit began in the s, the first in Toronto being established in By the s, when the evidence for thrombolysis for acute MI became accepted, infrastructure was already in place for treatment of acute MI, which made the goal of short door-to-needle times highly feasible. Furthermore, admission to a coronary care unit is beneficial because this setting offers rapid identification and treatment of malignant arrhythmias, diagnostic expertise and early introduction of medical treatments.
In cases of suspected ischemic stroke, bypassing the emergency department is difficult because of the need for imaging. The particular stroke type ischemic v. Rapid in-hospital processes and a team approach are required to reduce door-to-needle times. A median time of 20 minutes was shown to be possible in a cohort study from Helsinki, 39 but in North America median times of 60 minutes or more are typical.
Research studies are underway in Berlin and Houston to examine the effects of placing CT scanners in ambulances to allow rapid imaging, remote transmission of imaging data for expert review and a thrombolysis decision, so that paramedics can deliver thrombolytic therapy in the ambulance.
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Distinguishing clinically between transient ischemic attack and minor stroke is not particularly helpful for prognosis because both are associated with substantial early and day risks of major ischemic stroke, and urgent investigation and management are therefore warranted for both. Non-ST-segment elevation acute coronary syndromes include unstable angina and non-ST-segment elevation myocardial infarction.
Unstable angina is considered an acute coronary syndrome in which there is no detectable release of enzymes biomarkers of myocardial necrosis. These events occur as a consequence of platelet aggregation and complex interactions among the vascular wall, leukocytes, platelets and atherogenic lipoproteins.
Non-ST-segment elevation myocardial infarction has the same pathophysiology as unstable angina but is distinguished by the release of cardiac markers of myocardial necrosis e. Thrombolytic therapy is not indicated for these patients. Early coronary angiography and revascularization are beneficial in high-risk patients with acute coronary syndrome.
Specialized coronary care units are prevalent worldwide, but the same is not true for stroke units. Randomized controlled trials have shown conclusively that patients treated in dedicated stroke units fare better than those treated in general wards without the same ready access to personnel trained and experienced in managing stroke. Patients with stroke who receive organized inpatient care in a stroke unit are more likely to be alive, independent and living at home one year after the stroke.
Conceptually, there are broad similarities in the presentation, pathophysiology and treatment of acute ischemic stroke syndromes from the mildest transient ischemic attack or minor stroke through major ischemic stroke and acute coronary syndromes. Two unifying concepts are that treatments must be fast and decisive and that organization of care is critical to good outcomes.
Acute stroke care is rapidly catching up with acute coronary care. Ischemic stroke and acute coronary syndromes are similar because they are both caused by sudden arterial occlusion. Different causes and pathological processes can result in occlusion; therefore, approaches to treatment differ as well.
Time to treatment is a critical factor affecting outcome for both ischemic stroke and acute coronary syndromes. As is the case for acute coronary syndromes, coordinated systems of care are required to achieve good outcomes in patients with acute ischemic stroke. CMAJ Podcasts: author interview at soundcloud.
Competing interests: For work outside the scope of this review, Michael Hill reports consulting fees from Merck, nonfinancial support from Hoffmann-La Roche Canada Ltd.
Dating Acute, Subacute, and Chronic Infarct on MRI
He has a US patent pending no. No other competing interests were declared.
Jul 17, An educational blog on the most important radiology numbers created for radiology residents (by their chief resident) starting their ER shift. This website can be loaded at the beginning of each ER shift and kept in the background. Residents can access high yield information rapidly from this link. Sep 08, Globally, stroke is the second leading cause of death. 1 The estimated 62 strokes that occur each year in Canada affect all age groups, from neonates to elderly people, with occurrence rates rising by age. The lifetime risk of overt stroke is estimated at one in four by age 80 years, and the lifetime risk of silent or covert stroke is likely closer to %.Cited by: Past topics have included stroke, breast cancer screening, and coronary artery disease. We also offer the Radiology Legacy Collection, an electronic database featuring the most influential articles from archives of Radiology issues dating all .
Contributors: Tapuwa Musuka wrote the first draft of the manuscript and coordinated editing and revision. Stephen Wilton, Mouhieddin Traboulsi and Michael Hill edited, revised and approved the final version of the manuscript. All authors agree to act as guarantors for the work. National Center for Biotechnology InformationU.
Tapuwa D. HillMD. Author information Copyright and License information Disclaimer. Correspondence to: Michael D. Hill, ac. This article has been cited by other articles in PMC. Box 1: Evidence used in this review.
Diffusion weighted imaging (DWI) is a commonly performed MRI sequence for evaluation of acute ischemic stroke, and is sensitive in the detection of small and early infarcts. Conventional MRI sequences (T1WI, T2WI) may not demonstrate an infarct for 6 hours, and small infarcts may be hard to appreciate on CT for days, especially without the benefit of prior imaging. utes of stroke onset and are more sensitive than diffusion-weighted sequences that are performed after a stroke, which demonstrate hyperintensity. Table 1 Guide to Dating an Acute Ischemic Stroke on the Basis of MR Imaging Findings Imaging Sequence Early Hyperacute ( hours) Late Hyperacute ( hours) Acute (24 hours-1 week). Radiology Reference A not for profit site intended for radiologists to improve patient care. Search. Dating Acute, Subacute, and Chronic Infarct on MRI * Cortical necrosis usually resolves by 3 months after stroke and rarely persists for more than a year.
How do the causes of ischemic stroke and coronary syndromes compare? Table 1: Comparison of ischemic syndromes of the brain and heart. Open in a separate window. What are the signs and symptoms of acute ischemic stroke? Box 2: Diagnosis and assessment of acute stroke syndrome. How is the diagnosis confirmed?
Box 3. How diagnostics defined treatment in stroke and coronary syndromes. How should the patient with acute ischemic stroke be treated?
Sequence-specific MR imaging findings that are useful in dating ischemic stroke. Allen LM(1), Hasso AN, Handwerker J, Farid H. Author information: (1)Department of Radiological Sciences, University of California-Irvine Medical Center, Orange, CA , USA. [email protected] by: May 02, Initial non-contrast head CT scans of 2 pts with stroke presenting with L-sided weakness. The pt in (A.) has an ischemic stroke in the R hemisphere which is not yet visible on CT imaging early after onset while the pt in (B.) has evidence of a R hemisphere IC bleed. From the Department of Radiological Sciences, University of California-Irvine Medical Center, The City Drive S, Rte , Orange, CA Address correspondence to L.M.A. (e-mail: [email protected]). Patients may present to the hospital at various times after an ischemic stroke. Many present weeks after a neurologic deficit has Cited by:
Time is brain! Hours count Distinguishing clinically between transient ischemic attack and minor stroke is not particularly helpful for prognosis because both are associated with substantial early and day risks of major ischemic stroke, and urgent investigation and management are therefore warranted for both.
What care should be provided in hospital? Conclusion Conceptually, there are broad similarities in the presentation, pathophysiology and treatment of acute ischemic stroke syndromes from the mildest transient ischemic attack or minor stroke through major ischemic stroke and acute coronary syndromes. Key points Ischemic stroke and acute coronary syndromes are similar because they are both caused by sudden arterial occlusion.
References 1. Heart disease and stroke statistics - ate: a report from the American Heart Association. Circulation ; :ee Tracking heart disease and stroke in Canada. Ottawa: Public Health Agency of Canada; Available: www. An evidence-based causative classification system for acute ischemic stroke.
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