Comparison of Magnetic Resonance Imaging Sequences With Computed Tomography to Detect Low-Grade Subarachnoid Hemorrhage

Spontaneous Non-Aneurysmal Convexity Subarachnoid Hemorrhage: A Scoping Review of Different Etiologies beyond Cerebral Amyloid Angiopathy

Spontaneous convexity subarachnoid hemorrhage (cSAH) is a vascular disease different from aneurysmal SAH in neuroimaging pattern, causes, and prognosis. Several causes might be considered in individual patients, with a limited value of the patient's age for discriminating among these causes. Cerebral amyloid angiopathy (CAA) is the most prevalent cause in people > 60 years, but reversible cerebral vasoconstriction syndrome (RCVS) has to be considered in young people. CAA gained attention in the last years, but the most known manifestation of cSAH in this context is constituted by transient focal neurological episodes (TFNEs). CAA might have an inflammatory side (CAA-related inflammation), whose diagnosis is relevant due to the efficacy of immunosuppression in resolving essudation. Other causes are hemodynamic stenosis or occlusion in extracranial and intracranial arteries, infective endocarditis (with or without intracranial infectious aneurysms), primary central nervous system angiitis, cerebral venous thrombosis, and rarer diseases. The diagnostic work-up is fundamental for an etiological diagnosis and includes neuroimaging techniques, nuclear medicine techniques, and lumbar puncture. The correct diagnosis is the first step for choosing the most effective and appropriate treatment.

ACR Appropriateness Criteria® Headache: 2022 Update

Headache is an ancient problem plaguing a large proportion of the population. At present, headache disorders rank third among the global causes of disability, accounting for over $78 billion per year in direct and indirect costs in the United States. Given the prevalence of headache and the wide range of possible etiologies, the goal of this document is to help clarify the most appropriate initial imaging guidelines for headache for eight clinical scenarios/variants, which range from acute onset, life-threatening etiologies to chronic benign scenarios. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Modern Imaging of Aneurysmal Subarachnoid Hemorrhage

In this review, we discuss the imaging of aneurysmal subarachnoid hemorrhage (SAH). We discuss emergency brain imaging, aneurysm detection techniques, and the management of CTA-negative SAH. We also review the concepts of cerebral vasospasm and delayed cerebral ischemia that occurs after aneurysm rupture and their impact on patient outcomes. These pathologies are distinct, and the use of multimodal imaging modalities is essential for prompt diagnosis and management to minimize morbidity from these conditions. Lastly, new advances in artificial intelligence and advanced imaging modalities such as PET and MR imaging scans have been shown to improve the detection of aneurysms and potentially predict outcomes early in the course of SAH.

Subarachnoid Hemorrhage

PURPOSE OF REVIEW

Subarachnoid hemorrhage (SAH) remains an important cause of mortality and long-term morbidity. This article uses a case-based approach to guide readers through the fundamental epidemiology and pathogenesis of SAH, the approach to diagnosis and management, the results of clinical trials and evidence to date, prognostic considerations, controversies, recent developments, and future directions in SAH.

RECENT FINDINGS

Historically, management of SAH focused on prevention and treatment of subsequent cerebral vasospasm, which was thought to be the primary cause of delayed cerebral ischemia. Clinical and translational studies over the past decade, including several therapeutic phase 3 randomized clinical trials, suggest that the pathophysiology of SAH-associated brain injury is multiphasic and multifactorial beyond large vessel cerebral vasospasm. The quest to reduce SAH-associated brain injury and improve outcomes is shifting away from large vessel cerebral vasospasm to a new paradigm targeting multiple brain injury mechanisms, including early brain injury, delayed cerebral ischemia, microcirculatory dysfunction, spreading cortical depolarization, inflammation, and the brain-body interaction in vascular brain injury with critical illness.Despite multiple negative randomized clinical trials in search of potential therapeutic agents ameliorating the downstream effects after SAH, the overall outcome of SAH has improved over recent decades, likely related to improvements in interventional options for ruptured cerebral aneurysms and in critical care management. Emerging clinical evidence also suggests potential harmful impact of historic empiric treatments for SAH-associated vasospasm, such as prophylactic induction of hypertension, hypervolemia, and hemodilution (triple H therapy).With decreasing mortality, long-term SAH survivorship and efforts to reduce chronic morbidity and to improve quality of life and patient-centered outcome are growing areas of unmet need. Despite existing guidelines, significant variabilities in local and regional practices and in scientific terminologies have historically limited advancement in SAH care and therapeutic development. Large global collaborative efforts developed harmonized SAH common data elements in 2019, and studies are under way to examine how existing variabilities in SAH care impact long-term SAH outcomes.

SUMMARY

Although the overall incidence and mortality of SAH is decreasing with advances in preventive and acute care, SAH remains a major cause of long-term morbidity in survivors. Significant variabilities in care settings and empiric treatment protocols and inconsistent scientific terminologies have limited advancement in patient care and therapeutic clinical studies. Large consensus efforts are under way to introduce clinical guidelines and common data elements to advance therapeutic approaches and improve patient outcome.

ACR Appropriateness Criteria® Headache

Headache is one of the most common human afflictions. In most cases, headaches are benign and idiopathic, and resolve spontaneously or with minor therapeutic measures. Imaging is not required for many types of headaches. However, patients presenting with headaches in the setting of "red flags" such as head trauma, cancer, immunocompromised state, pregnancy, patients 50 years or older, related to activity or position, or with a corresponding neurological deficit, may benefit from CT, MRI, or noninvasive vascular imaging to identify a treatable cause. This publication addresses the initial imaging strategies for headaches associated with the following features: severe and sudden onset, optic disc edema, "red flags," migraine or tension-type, trigeminal autonomic origin, and chronic headaches with and without new or progressive features. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Subarachnoid extension of lobar hemorrhage on acute/subacute MRI is associated with cerebral amyloid angiopathy criteria

Subarachnoid hemorrhage extension (SAHE) in the acute phase of cerebral amyloid angiopathy (CAA)-related lobar hemorrhage (LH) assessed by CT is very frequent. Recently, SAHE, together with finger-like projections on CT and ApoE4, has been used in a prediction model for histopathologically proven CAA showing excellent discrimination. Our aim was to analyze SAHE on MRI in the acute and subacute phase of LH in patients with and without associated hemorrhagic features supportive of CAA (i.e. chronic LH, cortical superficial siderosis [CSS], and strictly lobar cerebral microbleeds [CMB]). We retrospectively studied SAHE on MRI performed in the acute and subacute phase (within 21 days) in a cohort of consecutive patients with acute LH recruited between January 2012 and April 2018. Sixty-eight acute LH patients (35 men and 33 women, mean age 74 [range 50-89]) were analyzed. Mean delay between symptom onset and MRI was 3.8 days, and 32 patients underwent MRI within 24 h. Based on MRI, 51 patients were classified as probable CAA and 17 patients without probable CAA. Both groups were comparable regarding age, sex, time of MRI performance, MRI field strength, and acute LH volume. Overall, SAHE was observed in 46 (68%) patients, including 39 (76%) patients with probable CAA and 7 (41%) patients without probable CAA (p = 0.015). SAHE presence was also associated with larger LH volumes. During the work-up in the acute/subacute phase of patients with acute LH, in addition to T2*-weighted imaging in search for other hemorrhagic features (chronic LH, CSS, or lobar CMB) evoking probable underlying CAA etiology, search for SAHE on adapted MRI sequences (FLAIR and T2*-weighted imaging) seems to be interesting because of the association with the presence of probable CAA criteria.

Magnetic Resonance Imaging in Aneurysmal Subarachnoid Hemorrhage: Current Evidence and Future Directions

BACKGROUND

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with an unacceptably high mortality and chronic disability in survivors, underscoring a need to validate new approaches for treatment and prognosis. The use of advanced imaging, magnetic resonance imaging (MRI) in particular, could help address this gap given its versatile capacity to quantitatively evaluate and map changes in brain anatomy, physiology and functional activation. Yet there is uncertainty about the real value of brain MRI in the clinical setting of aSAH.

METHODS

In this review, we discuss current and emerging MRI research in aSAH. PubMed was searched from inception to June 2017, and additional studies were then chosen on the basis of relevance to the topics covered in this review.

RESULTS

Available studies suggest that brain MRI is a feasible, safe, and valuable testing modality. MRI detects brain abnormalities associated with neurologic examination, outcomes, and aneurysm treatment and thus has the potential to increase knowledge of aSAH pathophysiology as well as to guide management and outcome prediction. Newer pulse sequences have the potential to reveal structural and physiological changes that could also improve management of aSAH.

CONCLUSION

Research is needed to confirm the value of MRI-based biomarkers in clinical practice and as endpoints in clinical trials, with the goal of improving outcome for patients with aSAH.

Diagnostic accuracy of flair in detection of acute subarachnoid hemorrhage in patients presenting with severe headache

BACKGROUND

Fluid attenuation inversion recovery (FLAIR) magnetic resonance imaging (MRI) sequences are previously described for the evaluation of acute subarachnoid hemorrhage (SAH) and demonstrated good sensitivity. This study was designed to find the diagnostic accuracy of FLAIR in detection of acute SAH in patients presenting with severe headache considering the fact that controversy has been observed in previous studies.

OBJECTIVE

To determine diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache using lumber puncture as gold standard.

METHODOLOGY

A total of 245 patients fulfilling selection criteria were enrolled in the study through the emergency department of Combined Military Hospital, Lahore. MRI was performed by Philips Intera Achieva 1.5T super conducting MR unit (Philips Medical Systems, the Netherlands), with the use of a head coil. FLAIR examination was performed at 6700/150 (TR/TE) with an inversion time (TI) of 2200ms, a field of view 230mm, matrix 189×256, scan time of 3min 50s and section thickness 5mm in axial plane. Following MRI, patients underwent lumbar puncture for cerebrospinal fluid (CSF) examination after 8-12h from the onset of event. MRI and CSF analysis results were then compared.

RESULTS

Out of 245 cases, 49.39% (n=121) were between 20-55 years of age while 50.61% (n=124) were between 56-70 years of age, mean±sd was calculated as 52.13±10.45 years, 53.88% (n=132) were male while 46.12% (n=113) were females, frequency of acute subarachnoid hemorrhage in patients presenting with severe headache was recorded as 5.71%(n=14), diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard as 78.57% sensitivity, 96.53% specificity, 57.89% positive predictive value, 98.67% negative predictive value and accuracy rate was calculated as 95.29%.

CONCLUSION

Diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard is higher and reliable.

One-year prognosis of non-traumatic cortical subarachnoid haemorrhage: A prospective series of 34 patients

INTRODUCTION

Cortical subarachnoid haemorrhage (cSAH) has multiple aetiologies. No prospective study has reported the long-term progression of the condition. The objective of this study is to describe the clinical and aetiological characteristics of patients with cSAH and to gain insight into prognosis.

METHODS

We performed a prospective, observational, multi-centre study. Data on clinical and radiological variables were collected; during a one-year follow-up period, we recorded data on mortality, dependence, rebleeding, and the appearance of dementia.

RESULTS

The study included 34 patients (mean age, 68.3 years; range, 27-89). The most frequent symptoms were headache and focal neurological deficits, which were frequently transient and recurrent. CT scans returned pathological findings in 28 patients (85%). Brain MRI scans were performed in 30 patients (88%), revealing acute ischaemia in 10 (29%), old haemorrhage in 7 (21%), and superficial siderosis in 2 (6%). Aetiology was identified in 26 patients (76.5%): causes were cerebral amyloid angiopathy in 8, ischaemic stroke in 5, vasculitis in 4, reversible posterior encephalopathy in 2, venous thrombosis in 2, reversible cerebral vasoconstriction syndrome in 2, carotid occlusion in 1, Marfan syndrome in 1, and meningeal carcinomatosis in 1. Three patients died during follow-up (2 due to causes related to the cause of cSAH). Three patients developed dementia, 3 had lobar haemorrhages, and one had a second cSAH.

CONCLUSIONS

The most frequent causes of cSAH in our series were cerebral amyloid angiopathy, ischaemic stroke, and vasculitis. This type of haemorrhage has a worse prognosis than other non-aneurysmal cSAH. There are numerous possible causes, and prognosis depends on the aetiology. In elderly patients, intracranial haemorrhage is frequently associated with cognitive impairment.

Reversible cerebral vasoconstriction syndrome: an important and common cause of thunderclap and recurrent headaches

Reversible cerebral vasoconstriction syndrome is an intracranial vascular manifestation of a wide variety of diseases. It is the second most common cause of thunderclap headache, the most common cause of recurrent severe secondary headaches, and, in patients <60 years of age, has been reported as the commonest cause of isolated convexity subarachnoid haemorrhage. Radiologically, its key feature is vasoconstriction of the intracranial vessels, a dynamic process that is typically maximal at 2 weeks, varies in its distribution over the course of the disease, and typically resolves after 3 months. It can have haemorrhagic and ischaemic complications and sometimes occurs in concert with posterior reversible encephalopathy syndrome. It also has important associations with dissection and migraine. Rarer atypical cases can present with mild headache, no headache at all, or even a comatose state. This paper provides a detailed review of this syndrome, its pathophysiology, differential diagnosis, imaging findings, and work-up. It also describes the role that high-resolution magnetic resonance imaging (MRI) techniques can have in diagnosing the disease and emphasises the central role that all radiologists have in detecting this important and underdiagnosed condition.

Introduction of a Dedicated Emergency Department MR Imaging Scanner at the Barrow Neurological Institute

Use of advanced imaging in the emergency department has been increasing in the United States during the past 2 decades. This trend has been most notable in CT, which has increased concern over the effects of increasing levels of medical ionizing radiation. MR imaging offers a safe, nonionizing alternative to CT and is diagnostically superior in many neurologic conditions encountered in the emergency department. Herein, we describe the process of developing and installing a dedicated MR imaging scanner in the Neuroscience Emergency Department at the Barrow Neurological Institute and its effects on neuroradiology and the emergency department in general.

Imaging of Intracranial Hemorrhage

Intracranial hemorrhage is common and is caused by diverse pathology, including trauma, hypertension, cerebral amyloid angiopathy, hemorrhagic conversion of ischemic infarction, cerebral aneurysms, cerebral arteriovenous malformations, dural arteriovenous fistula, vasculitis, and venous sinus thrombosis, among other causes. Neuroimaging is essential for the treating physician to identify the cause of hemorrhage and to understand the location and severity of hemorrhage, the risk of impending cerebral injury, and to guide often emergent patient treatment. We review CT and MRI evaluation of intracranial hemorrhage with the goal of providing a broad overview of the diverse causes and varied appearances of intracranial hemorrhage.

A completely thrombosed, nongiant middle cerebral artery aneurysm mimicking an intra-axial neoplasm

Background:

Few reports exist regarding thrombosed aneurysms where the initial work up was concerning for a neoplasm. To date, no published reports exist regarding a nongiant thrombosed middle cerebral artery aneurysm, where the primary workup and treatment plan was directed toward a preliminary diagnosis of intra-axial neoplasm.

Case Description:

We report a 43-year-old female who presented with a generalized tonic-clonic seizure attributed to a lesion along the right superior temporal gyrus. The lesion enhanced on initial magnetic resonance imaging (MRI) of the brain, as well as on follow-up MRI. Subsequent vascular studies and metastatic work up were negative. A craniotomy with image guidance was performed and an intraoperative diagnosis was made of a thrombosed aneurysm along a branch of the middle cerebral artery. The aneurysm was trapped and resected as there was no significant flow from the branch as seen on the prior cerebral angiogram. The patient had an uneventful postoperative course.

Conclusion:

Completely thrombosed, nongiant aneurysms can mimic an intra-axial neoplasm. Typical imaging features for thrombosed aneurysms may be missed, especially if the aneurysms are small, where imaging characteristics of the intraluminal contents is more difficult to appreciate. Although imaging may be consistent with a neoplastic lesion, there should be suspicion for a potential underlying aneurysm.

Subarachnoid hemorrhage in ten questions

Traumatic subarachnoid hemorrhage (SAH) has an annual incidence of 9 per 100 000 people. It is a rare but serious event, with an estimated mortality rate of 40% within the first 48hours. In 85% of cases, it is due to rupture of an intracranial aneurysm. In the early phase, during the first 24hours, cerebral CT, combined with intracranial CT angiography is recommended to make a positive diagnosis of SAH, to identify the cause and to investigate for an intracranial aneurysm. Cerebral MRI may be proposed if the patient's clinical condition allows it. FLAIR imaging is more sensitive than CT to demonstrate a subarachnoid hemorrhage and offers greater degrees of sensitivity for the diagnosis of restricted subarachnoid hemorrhage in cortical sulcus. A lumbar puncture should be performed if these investigations are normal while clinical suspicion is high.

Recognizing the signs and symptoms of aneurysmal subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating neurologic condition with a high mortality and long term neurological morbidity in 50% of survivors. In addition, SAH commonly affects young patients causing substantial loss of productive life years and resulting in significant long term healthcare costs. Early recognition of the signs and symptoms of SAH is absolutely critical to earlier intervention, and delays in diagnosis can have devastating consequences. To avoid such delays in SAH diagnosis, the medical provider should recognize its signs and symptoms. Neuroimgaging, cerebrospinal fluid examination and angiography (invasive or non-invasive) facilitate early diagnosis of SAH. The purpose of this review is not to provide an exhaustive critique of the available literature, rather, it is to provide an overview that will better enable a provider to recognize and initiate the workup of patients with SAH.

Aneurysmal subarachnoid haemorrhage from a neuroimaging perspective

Neuroimaging is a key element in the management of patients suffering from subarachnoid haemorrhage (SAH). In this article, we review the current literature to provide a summary of the existing neuroimaging methods available in clinical practice. Noncontrast computed tomography is highly sensitive in detecting subarachnoid blood, especially within 6 hours of haemorrhage. However, lumbar puncture should follow a negative noncontrast computed tomography scan in patients with symptoms suspicious of SAH. Computed tomography angiography is slowly replacing digital subtraction angiography as the first-line technique for the diagnosis and treatment planning of cerebral aneurysms, but digital subtraction angiography is still required in patients with diffuse SAH and negative initial computed tomography angiography. Delayed cerebral ischaemia is a common and serious complication after SAH. The modern concept of delayed cerebral ischaemia monitoring is shifting from modalities that measure vessel diameter to techniques focusing on brain perfusion. Lastly, evolving modalities applied to assess cerebral physiological, functional and cognitive sequelae after SAH, such as functional magnetic resonance imaging or positron emission tomography, are discussed. These new techniques may have the advantage over structural modalities due to their ability to assess brain physiology and function in real time. However, their use remains mainly experimental and the literature supporting their practice is still scarce.

Cerebral convexity subarachnoid hemorrhage: various causes and role of diagnostic imaging

Computed tomography (CT) and magnetic resonance imaging (MRI) have made it relatively easy to diagnose cortical convexity subarachnoid hemorrhages (cSAH); however, the evaluation of these hemorrhages should not be limited to size and location. It is imperative that possible underlying etiologies be identified so that clinicians may properly treat and prevent this potentially catastrophic event. The goal of this article is to review etiologies of cortical convexity subarachnoid hemorrhages, from common causes such as cerebral amyloid angiopathy to less common causes such as reversible cerebral vasoconstriction syndrome and moyamoya. The specific imaging findings of each etiology that may be responsible for these hemorrhages are described in this article so that the radiologist may properly aid in the diagnosis of the underlying cause.

Cerebral venous thrombosis as a rare cause of subarachnoid hemorrhage: case report and literature review

We report a 48-year-old woman presenting with subarachnoid hemorrhage (SAH) as the first manifestation of superior sagittal sinus thrombosis. In a literature review of 73 cases, SAH associated with cerebral venous thrombosis (CVT) was usually seen at the cerebral convexities. SAH was adjacent to thrombosed venous structures; therefore, the most possible explanation seems to be the rupture of cortical veins due to extension of thrombosis. Computed tomography (CT) was effective for diagnosis of CVT in only 32% of the cases. CVT should be considered when SAH is limited to cerebral convexities and magnetic resonance (MR) imaging with MR venography should be performed.

Commonly asked questions: imaging stroke and other types of neurovascular disorders

The medical management of patients requiring imaging of the head is often complex. This is confounded by growth and development of neuroimaging technology. Summarizing established guidelines and provided answers to commonly asked questions about neurovascular imaging may aid in providing efficient medical care. Noncontrast head computed tomography (CT) is usually the first line in imaging because of its speed and wide-spread availability. More advanced techniques are reserved for more specific questions or when the CT head is non-diagnostic. MRI is the modality of choice for indications that include chronic headache, pulsatile tinnitus, and cerebrovascular diseases including stroke in the subacute or chronic setting. The imaging of stroke is evolving and many advanced techniques including CT and magnetic resonance perfusion are playing an increasing role in diagnosis. Digital subtraction angiography is widely accepted as the gold standard for evaluation of vascular pathology including aneurysm, vascular malformations, Moyamoya syndrome, carotid stenosis and dissection; and offers treatment options. Alternatives such as MR angiography, MR venography, and CT angiography offer similar sensitivity and specificity to conventional digital subtraction angiography. Safety considerations are an important concern. When using iodinated and gadolinium contrast agents, there are potential complications including allergic reactions, lactic acidosis, and nephrogenic systemic fibrosis. Impaired renal function requires modification in the use of contrast during neuroimaging. Neuroimaging during pregnancy is also discussed.

Signal changes on T2*-weighted magnetic resonance imaging from the acute to chronic phases in patients with subarachnoid hemorrhage

BACKGROUND

Timing of the onset of subarachnoid hemorrhage (SAH) is important for treatment decision-making, especially as some patients visit hospital several weeks after the onset of SAH. T2*-weighted (T2*W) magnetic resonance (MR) imaging is regarded as a sensitive method for the detection of deoxyhemoglobin or hemosiderin deposits. This study investigated the characteristics of the abnormal low intensity changes on T2*W imaging in patients with SAH, how long the abnormal low intensity persisted, and whether the day of onset could be predicted based on the T2*W imaging changes.

METHODS

The study included patients treated for SAH associated with ruptured cerebral aneurysms, or who had previously suffered such SAH and were followed up at our hospital, between 2006 and 2007. MR imaging was performed using a whole-body 3.0-tesla MR scanner. All patients underwent gradient recalled echo (GRE) and echo planar (EP) T2*W imaging. The strength of the low intensity areas was evaluated as the following 5 grades: grade 0, no abnormal low intensity on both GRE and EP T2*W images; grade 1, no abnormal intensity on GRE T2*W images and low intensity on EP T2*W images; grade 2, spotty abnormal low intensity on both GRE and EP T2*W images; grade 3, medium abnormal low intensity (<5 mm) on both GRE and EP T2*W images, and grade 4, large abnormal low intensity (≥5 mm) on both GRE and EP T2*W images.

RESULTS

A total of 50 patients with 74 MR images were included during the study period. Abnormal low intensity on T2*W imaging was observed in all patients. The T2* score gradually decreased from the onset of SAH until day 90, showing a significant negative linear correlation (R(2) = 0.25, p = 0.0002). On the other hand, the T2* score did not change after 1 year. The square correlation coefficient between the recorded and calculated days from the onset of SAH was 0.29 (p = 0.0107). The pure error was ±10 days.

CONCLUSION

The T2* score gradually decreased until 90 days from the onset of SAH, but persisted for 16 years after the onset. We could predict the day of onset with pure error ±10 days in patients with SAH within 90 days of onset using our grading system for T2*W images.

An updated definition of stroke for the 21st century: a statement for healthcare professionals from the American Heart Association/American Stroke Association

Despite the global impact and advances in understanding the pathophysiology of cerebrovascular diseases, the term "stroke" is not consistently defined in clinical practice, in clinical research, or in assessments of the public health. The classic definition is mainly clinical and does not account for advances in science and technology. The Stroke Council of the American Heart Association/American Stroke Association convened a writing group to develop an expert consensus document for an updated definition of stroke for the 21st century. Central nervous system infarction is defined as brain, spinal cord, or retinal cell death attributable to ischemia, based on neuropathological, neuroimaging, and/or clinical evidence of permanent injury. Central nervous system infarction occurs over a clinical spectrum: Ischemic stroke specifically refers to central nervous system infarction accompanied by overt symptoms, while silent infarction by definition causes no known symptoms. Stroke also broadly includes intracerebral hemorrhage and subarachnoid hemorrhage. The updated definition of stroke incorporates clinical and tissue criteria and can be incorporated into practice, research, and assessments of the public health.

Detecting subarachnoid hemorrhage: comparison of combined FLAIR/SWI versus CT

OBJECTIVES

Aim of this study was to compare the utility of susceptibility weighted imaging (SWI) with the established diagnostic techniques CT and fluid attenuated inversion recovery (FLAIR) in their detecting capacity of subarachnoid hemorrhage (SAH), and further to compare the combined SWI/FLAIR MRI data with CT to evaluate whether MRI is more accurate than CT.

METHODS

Twenty-five patients with acute SAH underwent CT and MRI within 6 days after symptom onset. Underlying pathology for SAH was head trauma (n=9), ruptured aneurysm (n=6), ruptured arteriovenous malformation (n=2), and spontaneous bleeding (n=8). SWI, FLAIR, and CT data were analyzed. The anatomical distribution of SAH was subdivided into 8 subarachnoid regions with three peripheral cisterns (frontal-parietal, temporal-occipital, sylvian), two central cisterns and spaces (interhemispheric, intraventricular), and the perimesencephalic, posterior fossa, superior cerebellar cisterns.

RESULTS

SAH was detected in a total of 146 subarachnoid regions. CT identified 110 (75.3%), FLAIR 127 (87%), and SWI 129 (88.4%) involved regions. Combined FLAIR and SWI identified all 146 detectable regions (100%). FLAIR was sensitive for frontal-parietal, temporal-occipital and Sylvian cistern SAH, while SWI was particularly sensitive for interhemispheric and intraventricular hemorrhage.

CONCLUSIONS

By combining SWI and FLAIR, MRI yields a distinctly higher detection rate for SAH than CT alone, particularly due to their complementary detection characteristics in different anatomical regions. Detection strength of SWI is high in central areas, whereas FLAIR shows a better detection rate in peripheral areas.

Emergency diagnosis of subarachnoid hemorrhage: an evidence-based debate

BACKGROUND

The diagnosis of subarachnoid hemorrhage is of paramount concern in patients presenting to the Emergency Department (ED) with acute headache. Computed tomography followed by lumbar puncture is a time-honored practice, but recent technologic advances in magnetic resonance imaging with magnetic resonance angiography and computed tomography with computed tomography angiography can present alternatives for clinicians and patients.

OBJECTIVE

The aim of this article was to compare diagnostic strategies for ED patients in whom subarachnoid hemorrhage is suspected.

METHODS

We analyze and discuss current protocols, in addition to summarizing the advantages and disadvantages of each method.

RESULTS

Through our residency's journal club, we organized an evidence-based debate that pitted proponents of the three subarachnoid hemorrhage diagnostic strategies against one another. Proponents of each strategy described its advantages and disadvantages. Briefly, computed tomography/lumbar puncture is time honored and effective, but is limited by complications and indeterminate lumbar puncture results. Magnetic resonance imaging with magnetic resonance angiography might be more effective in late presentations and can visualize aneurysms, yet has limited availability. Computed tomography with computed tomography angiography offers rapid diagnosis and is considered the most sensitive for diagnosing aneurysms, but has the highest radiation exposure.

CONCLUSIONS

Each of the three strategies used to diagnose subarachnoid hemorrhage has advantages and disadvantages with which clinicians should be familiar. Patient factors (e.g., age, body habitus, and risk factors), presentation factors (e.g., time from headache onset and severity of presentation), and institutional factors (availability of magnetic resonance imaging with magnetic resonance angiography) can influence the choice of protocol.

Cost-effectiveness of diagnostic strategies for evaluation of suspected subarachnoid hemorrhage in the emergency department

OBJECTIVES

Diagnosing subarachnoid hemorrhage (SAH) in emergency department (ED) patients is challenging. Potential diagnostic strategies include computed tomography (CT) only, CT followed by lumbar puncture (CT/LP), CT followed by magnetic resonance imaging and angiography (CT/MRA), and CT followed by CT angiography (CT/CTA). The objective was to determine the relative cost-effectiveness of diagnostic strategies for SAH.

METHODS

 The authors created a decision model to evaluate the cost-effectiveness of SAH diagnostic strategies in ED patients with suspected SAH. Clinical probabilities were obtained from published data; sensitivity analyses were conducted across plausible ranges.

RESULTS

  In the base-case scenario, CT-only had a cost of $10,339 and effectiveness of 20.25 quality-adjusted life-years (QALYs), and CT/LP had a cost of $15,120 and effectiveness of 20.366 QALYs. Among the alternative strategies, CT/CTA had a cost of $12,840 and effectiveness of 20.24 QALYs, and CT/MRA had a cost of $16,207 and effectiveness of 20.27 QALYs. In sensitivity analyses, probability of severe disability from SAH, sensitivity of noncontrast CT, and specificity of LP and MRA were key drivers of the model, and CT-only and CT/LP were preferable.

CONCLUSIONS

In the base-case scenario, CT-only was preferable to the CT/CTA and CT/MRA strategies. When considering sensitivity analyses and the current medicolegal environment, there are no overwhelming differences between the cost-effectiveness of CT/LP and the alternative strategies to suggest that clinicians should abandon the standard CT/LP approach.

The unique features of traumatic brain injury in children. Review of the characteristics of the pediatric skull and brain, mechanisms of trauma, patterns of injury, complications and their imaging findings--part 1

Traumatic head/brain injury (TBI) is a leading cause of death and life-long disability in children. The biomechanical properties of the child's brain and skull, the size of the child, the age-specific activity pattern, and higher degree of brain plasticity result in a unique distribution, degree, and quality of TBI compared to adult TBI. A detailed knowledge about the various types of primary and secondary pediatric head injuries is essential to better identify and understand pediatric TBI. The goals of this review article are (1) to discuss the unique epidemiology, mechanisms, and characteristics of TBI in children, and (2) to review the anatomical and functional imaging techniques that can be used to study common and rare pediatric traumatic brain injuries and their complications.

Isolated acute nontraumatic cortical subarachnoid hemorrhage

Our aim was to review the etiologic background of isolated acute nontraumatic cSAH. While SAH located in the basal cisterns originates from a ruptured aneurysm in approximately 85% of cases, a broad spectrum of vascular and even nonvascular pathologies can cause acute nontraumatic SAH along the convexity. Arteriovenous malformations or fistulas, cortical venous and/or dural sinus thrombosis, and distal and proximal arteriopathies (RCVS, vasculitides, mycotic aneurysms, Moyamoya, or severe atherosclerotic carotid disease) should be sought by noninvasive imaging methods or/and conventional angiography. Additionally, PRES may also be a source of acute cSAH. In elderly patients, cSAH might be attributed to CAA if numerous hemorrhages are demonstrated by GRE T2 images. Finally, cSAH is rarely observed in nonvascular disorders, such as abscess and primitive or secondary brain tumors.

Imaging of accidental paediatric head trauma

Head trauma is the most common form of injury sustained in serious childhood trauma and remains one of the top three causes of death despite improved road planning and safety laws. CT remains the first-line investigation for paediatric head trauma, although MRI may be more sensitive at picking up the full extent of injuries and may be useful for prognosis. Follow-up imaging should be tailored to answer the specific clinical question and to look for possible complications.

Subintimal hemorrhage in an unruptured superior cerebellar artery aneurysm: prelude to rupture: case report

OBJECTIVE AND IMPORTANCE

An intracranial aneurysm that hemorrhages into the subintimal layer of the blood vessel is a rare clinical entity. Such a hemorrhage is distinct from dissecting aneurysms or pseudoaneurysms of the cerebral circulation and may represent an aneurysm in the process of rupturing. The authors report their experience in the management of a patient who presented with a subintimal hemorrhage of a superior cerebellar aneurysm.

CLINICAL PRESENTATION

A 54-year-old man presented with a progressively worsening headache over the course of 3 days. A noncontrast computed tomographic scan did not demonstrate subarachnoid hemorrhage but was suggestive of a posterior circulation aneurysm.

INTERVENTION

In the absence of subarachnoid hemorrhage on the computed tomographic scan, negative findings for xanthochromia in the cerebrospinal fluid, and no evidence of subarachnoid blood on magnetic resonance imaging, a conventional four-vessel cerebral angiogram was performed, which revealed a right superior cerebellar artery aneurysm. Further evaluation on magnetic resonance imaging demonstrated abnormal signal conforming to the aneurysm wall, suggesting the presence of a contained subintimal hemorrhage. The patient underwent a right frontotemporal craniotomy (half-and-half approach) for clip ligation of the superior cerebellar artery aneurysm.

CONCLUSION

Subintimal hemorrhage of an aneurysm in the absence of subarachnoid hemorrhage may be conceptually considered an aneurysm in the process of rupturing. Thus, aneurysms found in the acute setting may benefit from further workup, such as magnetic resonance imaging or highly selective angiographic evaluation of the aneurysm itself. Timely surgical intervention may prevent otherwise imminent rupture into the subarachnoid space.

Clinical application of magnetic resonance in acute traumatic brain injury

PURPOSE: To evaluate the clinical applications of magnetic resonance imaging (MRI) in patients with acute traumatic brain injury (TBI): to identify the type, quantity, severity; and improvement clinical-radiological correlation. METHOD: Assessment of 55 patients who were imaged using CT and MRI, 34 (61.8%) males and 21 (38.2%) females, with acute (0 to 5 days) and closed TBI. RESULTS: Statistical significant differences (McNemar test): ocurred fractures were detected by CT in 29.1% and by MRI in 3.6% of the patients; subdural hematoma by CT in 10.9% and MRI in 36.4 %; diffuse axonal injury (DAI) by CT in 1.8% and MRI in 50.9%; cortical contusions by CT in 9.1% and MRI in 41.8%; subarachnoid hemorrhage by CT in 18.2% and MRI in 41.8%. CONCLUSION: MRI was superior to the CT in the identification of DAI, subarachnoid hemorrhage, cortical contusions, and acute subdural hematoma; however it was inferior in diagnosing fractures. The detection of DAI was associated with the severity of acute TBI.