MRI and MR angiography of vertebral artery dissection

Self-Chiropractic Cervical Spinal Manipulation Resulting in Fatal Vertebral Artery Dissection: A Case Report and Review of the Literature

ABSTRACT

Chiropractic cervical spinal manipulations have several complications and can result in vascular injury, including traumatic dissection of the vertebral arteries. A 43-year-old woman was admitted to the emergency department after performing a self-chiropractic spinal manipulation. She experienced headache and vomiting and was unresponsive with severe hypertension at the time of hospital admission. Clinical computerized tomography angiography showed narrowing of the right vertebral artery but was inconclusive for dissection or thrombosis. At autopsy, subacute dissection of the right vertebral artery was identified along with cerebral edema and herniation. A small peripheral pulmonary thromboembolism in the right lung was also seen. Neuropathology consultation confirmed the presence of diffuse cerebral edema and acute hypoxic-ischemic changes, with multifocal acute subarachnoid and intraparenchymal hemorrhage of the brain and spinal cord. This case presents a unique circumstance of a fatal vertebral artery dissection after self-chiropractic manipulation that, to the best of our knowledge, has not been previously described in the medical literature.

Simultaneous intracranial and extracranial vertebral artery dissections: a case report

Vertebral artery dissection can occur in intracranial or extracranial vertebral arteries. However, the simultaneous dissection of both intracranial and extracranial vertebral arteries is extremely rare. We describe a 45-year-old man with simultaneous intracranial and extracranial vertebral artery dissections in separate sites. The patient visited a neurosurgical clinic because of headache; he was diagnosed with right vertebral artery dissection and referred to our hospital. Magnetic resonance imaging showed an intramural hematoma and mild dilation of the external lumen in the right vertebral artery distal to the posterior inferior cerebellar artery. Magnetic resonance angiography revealed poor delineation of the entire right vertebral artery, including the proximal portion from the posterior inferior cerebellar artery. Computed tomography angiography revealed right extracranial vertebral artery dissection. Careful imaging assessment is thus important for identifying simultaneous intracranial and extracranial vertebral artery dissections.

Imaging of Non-atherosclerotic Vasculopathies

Non-atherosclerotic vasculopathies (NAVs) may present with various neurological symptoms ranging from headache, stroke, visual symptoms, and various types of intracranial hemorrhage. NAVs result from different etiologies which include collagenopathies, immunological, hematological, and infection mechanisms, and other rarer unidentifiable or idiopathic causes. NAV etiologies account for about 10–15% and 20–25% of adult and pediatric stroke cases, respectively, and therefore, diagnosing the underlying cause of NAV becomes clinically very important. Clinical diagnosis of NAV is challenging because the clinical presentation is very non-specific and overlapping with various other central nervous system disorders. Before the advent of non-invasive techniques, making a diagnosis of non-atherosclerotic vasculopathy as a cause of the stroke was very challenging. Today with newer techniques such as high-resolution magnetic resonance (MR), MR and computed tomography perfusion, and angiogram, there are number of pointers which can give us a lead about the non-atherosclerotic causes. Imaging may provide the first lead to the clinician regarding the diagnosis or possible differential diagnosis so that the targeted and focused biomarkers (blood, cerebrospinal fluid, or/and in some cases biopsies) may be obtained to clinch the diagnoses. The purpose of the article is to enumerate the causes, clinical features, and illustrate the imaging findings of the various non-atherosclerotic vasculopathic disorders and discuss “pearls” to their diagnosis. In this article, we have also discussed the latest advances in vascular imaging and elaborated on few uncommon non-atherosclerotic vasculopathies. These are very relevant clinically in the day-to-day practice for the radiologist, neurologist, and the neurointerventionalist.

Qualitative Assessment and Reporting Quality of Intracranial Vessel Wall MR Imaging Studies: A Systematic Review

BACKGROUND

Over the last quarter-century, the number of publications using vessel wall MR imaging has increased. Although many narrative reviews offer insight into technique and diagnostic applications, a systematic review of publication trends and reporting quality has not been conducted to identify unmet needs and future directions.

PURPOSE

We aimed to identify which intracranial vasculopathies need more data and to highlight areas of strengths and weaknesses in reporting.

DATA SOURCES

PubMed, EMBASE, and MEDLINE databases were searched up to September 2018 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA ANALYSIS

Two independent reviewers screened and extracted data from 128 articles. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used to assess the reporting quality of analytic observational studies.

DATA SYNTHESIS

There has been an exponentially increasing trend in the number of vessel wall MR imaging publications during the past 24 years (P < .0001). Intracranial atherosclerosis is the most commonly studied intracranial vasculopathy (49%), followed by dissections (13%), aneurysms (8%), and vasculitis (5%). Analytic observational study designs composed 48% of the studies. Transcontinental collaborations showed nonsignificantly higher reporting quality compared with work originating from single continents (P = .20).

LIMITATIONS

A limitation is the heterogeneity in study designs.

CONCLUSIONS

Investigations on the diagnostic utility of vessel wall MR imaging in less commonly studied intracranial vasculopathies such as dissections, aneurysms, and vasculitis are warranted. More consistent adherence to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines should improve transparency and maximize effective synthesis for clinical translation. Diverse collaborative teams are encouraged to advance the understanding of intracranial vasculopathies using vessel wall MR imaging.

Magnetic Resonance Imaging and Clinical Factors Associated With Ischemic Stroke in Patients Suspected of Cervical Artery Dissection

Background and Purpose- Cervical artery dissection is a major cause of ischemic stroke in the young and presents with various imaging findings, including stenosis and intramural hematoma (IMH). Our goal was to determine the relative contribution of lumen findings and IMH to acute ischemic stroke and whether a heavily T1-weighted sequence could more reliably detect IMH. Methods- Institutional review board approval was obtained for this retrospective study of 254 patients undergoing magnetic resonance imaging/magnetic resonance angiography for suspected dissection. Imaging included standard turbo spin-echo (TSE) T1-fat saturation and heavily T1-weighted flow-suppressed magnetization-prepared rapid acquisition gradient-recalled echo sequences. Subjects with stents (1) or atherosclerotic disease (26) were excluded, leaving 227 subjects. Kappa analysis was used to determine IMH interrater reliability on magnetization-prepared rapid acquisition gradient-recalled echo and T1-fat saturation in 4 vessels per subject. Lumen findings, cardiovascular risk factors, medications, and nondissection stroke sources were recorded. Mixed-effects multivariate Poisson regression was used to determine the prevalence ratio of each factor with acute ischemic stroke, accounting for 4 vessels per patient with backward elimination to a threshold P value of 0.10. Results- Patients were 41.9% men, mean age of 47.3±16.6 years, with 114 dissections and 107 strokes. IMH interrater reliability was significantly higher for magnetization-prepared rapid acquisition gradient-recalled echo (κ=0.83; 95% CI, 0.78-0.86) versus T1-fat saturation (0.58; 95% CI, 0.57-0.68). The final acute stroke prediction model included magnetization-prepared rapid acquisition gradient-recalled echo-detected IMH (prevalence ratio, 2.0; 95% CI, 1.1-3.9; P=0.034), stenosis, pseudoaneurysm, male sex, current smoking, and nondissection stroke sources. The final model had high discrimination for acute stroke (area under the curve, 0.902; 95% CI, 0.872-0.932), compared with models without stenosis (0.861; 95% CI, 0.821-0.902), and without stenosis and IMH (0.831; 95% CI, 0.783-0.879). All 3 models were significantly different at P<0.05. Conclusions- Along with stenosis, IMH detection significantly contributed to acute ischemic stroke pathogenesis in patients with suspected cervical artery dissection. In addition, IMH detection can be made more reliable with heavily T1-weighted sequences.

Traumatic vertebral artery injury: a review of the screening criteria, imaging spectrum, mimics, and pitfalls

PURPOSE

Traumatic vertebral artery injury (TVAI) can have a varied clinical presentation and appearance on imaging. In this review, we present the screening criteria, spectrum of imaging features, grading, and imaging pitfalls of TVAI. Our review focuses on the imaging of TVAI on computed tomography angiography (CTA), magnetic resonance angiography (MRA), and cases of TVAI mimics.

IMAGING

The imaging spectrum on CTA can range from either focal or long segment luminal stenosis (the most common findings), smooth or tapered narrowing of lumen, string of pearls appearance, concentric intramural haematoma, intimal flap (the most definite sign), and double lumen of the artery. On time-of-flight MRA, the most common findings include loss of flow void within the vessel due to slow flow, thrombosis or occlusion, and hyperintense signal within the vessel wall due to intramural haematoma on T1 fat-saturated images.

CONCLUSION

The reader should be aware of the screening criteria, common and uncommon findings, variant anatomy, artifacts, and mimics of TVAI when evaluating cases of craniocervical trauma, to be competent in calling in or ruling out injury.

The Prevalence of and Factors Related to Vascular Hyperintensity on T1-Weighted Imaging in Acute Ischemic Stroke

BACKGROUND

Thrombus visualization in patients with acute ischemic stroke has been detected and reported using various imaging modalities. T1-weighted imaging (T1-WI) can depict thrombi as hyperintense signals within vessels. Moreover, in addition to thrombi, T1-WI hyperintensities in arteries may suggest arterial dissection. However, the frequency of and factors related to the T1-hyperintense vessel sign (T1-HVS) are not fully known. The aim of this study was to clarify the prevalence of and related factors for the T1-HVS in patients with acute ischemic stroke.

METHODS

From September 2014 through December 2015, consecutive acute ischemic stroke patients who were admitted to our stroke unit within 7 days from symptom onset were retrospectively recruited from the prospective registry. A T1-HVS was defined as the presence of a hyperintense signal, with intensity higher than surrounding brain, within the vessel lumen. Moreover, T1-HVSs were separated into filled T1-HVSs (hyperintensity fills whole vessel lumen) and non-filled T1-HVSs. The frequency of the T1-HVS and the timing of emersion and the relationship between the presence of the T1-HVS and arterial occlusion were assessed.

RESULTS

A total of 399 patients (139 women; median age 73 years; National Institutes of Health Stroke Scale score 3) were enrolled in the present study. Of these, 327 (82%) patients had T1-WI on admission. Two hundred and sixty-seven (67%) subjects had at least one follow-up T1-WI (median 6 days after admission), and 134 (34%) cases had ≥2 follow-up T1-WI examinations. The T1-HVS was observed in 18 patients during admission; therefore, the frequency of the T1-HVS in acute ischemic stroke patients was 4.5% (95% CI 2.5-6.5%). All but one (94%) of the T1-HVSs were first observed on follow-up imaging, and the median number of days from onset to T1-HVS appearance was 9. For patients having initial major artery occlusion and follow-up MRI (n = 95), sensitivity and specificity of the T1-HVS for persistent arterial occlusion on follow-up MR angiography were 22 and 100%, respectively. T1-HVS persisted for a few months and then normalized. Although there were no significant differences between filled and non-filled T1-HVS, more patients with non-filled T1-HVS had arterial dissection (43%) than those with filled T1-HVS (9%, p = 0.245).

CONCLUSION

The T1-HVS was observed in 4.5% of acute ischemic stroke patients. T1-HVSs appeared in the subacute phase in arteries with persistent occlusion and remained for a few months.

Usefulness of R2* maps generated by iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence for cerebral artery dissection

INTRODUCTION

Acute intramural hematoma resulting from cerebral artery dissection is usually visualized as a region of intermediate signal intensity on T1-weighted images (WI). This often causes problems with distinguishing acute atheromatous lesions from surrounding parenchyma and dissection. The present study aimed to determine whether or not R2* maps generated by the iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantitation sequence (IDEAL IQ) can distinguish cerebral artery dissection more effectively than three-dimensional variable refocusing flip angle TSE T1WI (T1-CUBE) and T2*WI.

METHODS

We reviewed data from nine patients with arterial dissection who were assessed by MR images including R2* maps, T2*WI, T1-CUBE, and 3D time-of-flight (TOF)-MRA. We visually assessed intramural hematomas in each patient as positive (clearly visible susceptibility effect reflecting intramural hematoma as hyperintensity on R2* map and hypointensity on T2*WI), negative (absent intramural hematoma), equivocal (difficult to distinguish between intramural hematoma and other paramagnetic substances such as veins, vessel wall calcification, or hemorrhage) and not evaluable (difficult to determine intramural hematoma due to susceptibility artifacts arising from skull base).

RESULTS

Eight of nine patients were assessed during the acute phase. Lesions in all eight patients were positive for intramural hematoma corresponding to dissection sites on R2* maps, while two lesions were positive on T2*WI and three lesions showed high-intensity on T1-CUBE reflected intramural hematoma during the acute phase.

CONCLUSION

R2* maps generated using IDEAL IQ can detect acute intramural hematoma associated with cerebral artery dissection more effectively than T2*WI and earlier than T1-CUBE.

A dilated surface appearance on basiparallel anatomic scanning-magnetic resonance imaging is a useful tool for the diagnosis of spontaneous vertebral artery dissection in lateral medullary infarction

Spontaneous dissection of the vertebral artery (VA) is a major vascular lesion causing lateral medullary infarction (LMI). A dilated surface appearance of the VA is a feature of VA dissection and can be observed on basiparallel anatomic scanning (BPAS)-magnetic resonance imaging (MRI). The aim of this study was to validate BPAS-MRI in the diagnosis of VA dissection in patients with LMI. The subjects of the present study were 41 consecutive patients with LMI within 7 days of onset. The diagnosis of VA dissection was made with the clinical criteria-based diagnosis. Percent (%) dilatation of the VA on BPAS-MRI was calculated by comparing the maximum surface diameter of the intracranial VA to the diameter of the distal normal surface of the VA. Fourteen patients (34%) were diagnosed with VA dissection. The optimal cutoff % dilatation of the VA for dissection was more than 169%. The sensitivity and specificity of % dilatation of VA more than 169% and aneurysmal dilatation, stenosis, or occlusion on magnetic resonance angiography (MRA) for VA dissection were 92.9% and 81.5%, respectively. BPAS-MRI combined with time-of-flight-MRA is a useful tool for the diagnosis of VA dissection in patients with acute LMI.

Intracranial vertebral artery dissections: evolving perspectives

Intracranial vertebral artery dissection (VAD) represents the underlying etiology in a significant percentage of posterior circulation ischemic strokes and subarachnoid hemorrhages. These lesions are particularly challenging in their diagnosis, management, and in the prediction of long-term outcome. Advances in the understanding of underlying processes leading to dissection, as well as the evolution of modern imaging techniques are discussed. The data pertaining to medical management of intracranial VADs, with emphasis on anticoagulants and antiplatelet agents, is reviewed. Surgical intervention is discussed, including, the selection of operative candidates, open and endovascular procedures, and potential complications. The evolution of endovascular technology and techniques is highlighted.

MR diagnosis of vertebral artery dissection: value of 3D time-of-flight and true fast imaging with steady-state precession fusion imaging

OBJECTIVES

We hypothesized that 3D time-of-flight (TOF) and true fast imaging with steady-state precession (true-FISP) fusion imaging could provide more information regarding the arterial vessel wall. The purpose of this study was to compare the accuracy of lesion detection and the diagnostic confidence of VAD between TOF images alone and fused TOF and true-FISP images.

METHODS

Fifty patients were studied: 17 had VAD and 33 had vertebral artery hypoplasia. Fusion images of the vertebral artery were reconstructed using a workstation. A receiver-operating characteristic (ROC) analysis was conducted with a continuous rating scale from 1 to 100 to compare observer performance in VAD detection. Five radiologists participated in the observer performance test, and their performances with TOF images were compared with those using fused images.

RESULT

The observers found that the mean areas under the best-fit ROC curve for TOF images alone and fused TOF images were 0.66 ± 0.05 and 0.93 ± 0.04, which were significantly different (P < 0.01).

CONCLUSION

The fusion images provided more information regarding the arterial vessel wall. Fused images aided distinction between vertebral artery dissection versus vertebral artery hypoplasia.

KEY POINTS

• New MR techniques can help to differentiate flowing blood from static blood products. • Fused TOF and true-FISP images differentiate the lumen and the arterial wall, improving diagnostic performance. • Fused images may be superior to time-of-flight MR angiography alone.

Vertebral artery injury in destabilized midcervical spine trauma; predisposing factors and proposed mechanism

BACKGROUND

By now it has been well established that vertebral artery injury (VAI) is associated with unstable cervical spine injuries resulting from blunt trauma. A more complete understanding of predisposing factors and the mechanism of injury in VAI should result in improved outcomes and reduced risk for patients with VAI associated with unstable cervical spine injury following blunt trauma. The authors report statistical outcome and hypothesis to more thoroughly examine the predisposing factors for VAI, of which management is controversial, in destabilized midcervical spine trauma.

METHODS

Ninety-one of 131 consecutive patients who underwent surgery for a traumatically destabilized subaxial cervical spine were included, and results were analyzed statistically by logistic regression.

RESULTS

Eighteen patients (19.8 % of 91 patients) had a VAI associated with midcervical spine trauma (C2-C6). In univariate statistical analysis, transverse foramen fracture (P = 0.002), facet dislocation (P = 0.014), and facet fracture (P = 0.001) were significant risk factors. However, only facet fracture was determined to be significant risk factor after multivariate analysis (P = 0.006, odds ratio 20.98). It is hypothesized that a VAI occurs in a midcervical spine injury when a facet fracture allows the bony compartment to impinge on the relatively narrow free space of the intervertebral foramen, which is also occupied by the cervical root.

CONCLUSION

A facet fracture is the most important risk factor for VAI in patients with a destabilized midcervical spine injury. Patients with a C2-C6 facet fracture may require a definitive evaluation with vertebral artery imaging.

Craniocervical arterial dissection in children: diagnosis and treatment

OPINION STATEMENT

Diagnosis of craniocervical arterial dissection (CCAD) in children begins with a careful history and physical in a child with a transient ischemic attack (TIA) or arterial ischemic stroke (AIS). The extent of radiologic evaluation for suspected CCAD is based upon careful consideration of the risks associated with the best imaging techniques, weighed against the benefits of enhanced vascular imaging with better diagnostic sensitivity. Although conventional angiography (CA) and CT angiography (CTA) have a higher sensitivity than magnetic resonance angiography (MRA), they are accompanied by risks: for CA, femoral hematoma, femoral arterial pseudoaneurysm, recurrent AIS, and radiation exposure; for CTA, radiation. For children (non-neonates) with suspected CCAD, MRI with MRA is recommended as the first-line imaging study. MRI usually includes diffusion-weighted, FLAIR, and T1 images of the brain, and T1 or T2 fat-saturation axial imaging through the neck. MRA should include 3D time-of-flight MRA of the head and neck (from the aortic arch through the circle of Willis). Contrast-enhanced MRA should be highly considered in neck imaging. If MRI/MRA is equivocal, CCAD is strongly suspected but not detected on MRI/MRA (especially in the posterior circulation), or the child has recurrent events, additional imaging of the craniocervical vasculature is likely warranted. Individual clinical circumstances warrant careful, case-by-case consideration. Treatment of CCAD in children is challenging and differs for intracranial and extracranial dissections. In extracranial CCAD, we most commonly use anticoagulation for 6 weeks to 6 months in patients with TIA or AIS. Typically, unfractionated heparin is used in the acutely ill patient at heightened risk for bleeding (because of its short half-life), whereas low-molecular-weight heparin (LMWH) or warfarin are reserved for the stable patient. If the history is suspicious for dissection (head and neck trauma, recent cervical chiropractic manipulation, recent car accident, or neck pain), we consider treatment for dissection even with normal MRI/MRA. For patients with CCAD with a stroke size greater than one third to one half of the middle cerebral artery territory (or other bleeding risk factors) and extracranial CCAD, in whom there is concern about heightened risk for hemorrhagic conversion, we commonly use aspirin therapy during the acute phase. Regardless of their treatment in the initial weeks to months, we subsequently treat all patients with aspirin for 1 year after their event, and sometimes longer if they have other risk factors. Interventional techniques, such as extracranial cerebral arterial stent placement or selective occlusion, are understudied in children. Interventional techniques are typically reserved for patients who fail aggressive medical management and have recurrent TIA or AIS. The diagnosis and treatment of intracranial dissection is extraordinarily challenging in children, in whom inflammatory intracranial arteriopathies are common. When intracranial arteriopathy is clearly associated with dissection, the clinician should look for the presence of subarachnoid hemorrhage and/or dissecting aneurysm. Treatment decisions should be made by a multidisciplinary pediatric stroke team, given the lack of data in this area. Intracranial cerebral artery stent placement carries high risk and is not recommended for intracranial CCAD in children. Most importantly, we educate all children with CCAD and their parents about the paucity of evidence in the treatment of this disease, the risks of enhanced imaging techniques such as CTA or CA, and the challenges involved in weighing the risks of aggressive therapies and interventions against the costs of unclear diagnosis and potentially ineffective treatments. We also educate our patients with CCAD about the signs and symptoms of recurrence and the importance of emergent evaluation.

Multidetector computed tomography angiography: Application in vertebral artery dissection

BACKGROUND AND PURPOSE

Multidetector computed tomography angiography (MDCTA) is a minimally invasive radiological technique providing high-resolution images of the arterial wall and angiographic images of the lumen. We studied the radiological features of vertebral artery dissection (VAD) in a consecutive series of patients investigated for acute stroke and subarachnoid hemorrhage (SAH) in order to confirm and define the diagnostic features of VAD on MDCTA.

PATIENTS AND METHODS

Review of patients identified prospectively over a 4-year period with VAD assessed by MDCTA was conducted. Radiological features of VAD on MDCTA were reanalyzed utilising previously reported criteria for VAD.

RESULTS

Thirty-five patients (25 males, mean age 49.6 years) with a total of 45 dissected vertebral arteries were reviewed. MDCTA features of VAD included increased wall thickness in 44/45 (97.7%) arteries and increased total vessel diameter in 42/45 arteries (93.3%). All dissected arteries had either lumen stenosis (21/45) or associated segmental occlusion (24/45). An intimal flap was detected in 6/45 (13.3 %) vessels. Twenty-five patients had follow-up imaging, 14/32 vessels returned to normal, 4 showed improvement in stenosis but did not return to normal and 14 demonstrated no change. The majority of non-occluded vessels became normal or displayed improved patency. Only 4/17 occluded arteries demonstrated re-establishment of flow. No adverse effects were recorded.

CONCLUSIONS

MDCTA is a safe and reliable technique for the diagnosis of VAD. Increased wall thickness (97.7%) and increased vessel wall diameter (93.3%) were the most frequently observed features.

Comparison of test performance characteristics of MRI, MR angiography, and CT angiography in the diagnosis of carotid and vertebral artery dissection: a review of the medical literature

OBJECTIVE

Initial assessment of patients with suspected dissection of the carotid or vertebral arteries typically is made by MRI, alone or in combination with MR angiography (MRA) or CT angiography (CTA). We reviewed the medical literature to determine, based on test performance characteristics such as sensitivity, specificity, positive predictive value, and negative predictive value, whether evidence could be found to support routine use of one imaging technique over the other for assessment of suspected dissection.

CONCLUSION

Test characteristics for MR techniques such as MRI and MRA were relatively similar to those for CTA in diagnosis of carotid and vertebral artery dissection.

Low detection rate of craniocervical arterial dissection in children using time-of-flight magnetic resonance angiography: causes and strategies to improve diagnosis

Craniocervical arterial dissection is a frequent cause of childhood arterial ischemic stroke requiring prompt diagnosis and treatment. However, there is no universal guideline for diagnostic cerebrovascular imaging in children. We assessed the role of time-of-flight magnetic resonance angiography in diagnosing craniocervical arterial dissection. We included children (1 month to 18 years) with craniocervical arterial dissection and ischemic stroke from January 1998 to June 2007. Institutional protocol required magnetic resonance imaging (MRI)/ magnetic resonance angiography for all ischemic stroke cases and conventional cerebral angiography if magnetic resonance angiography showed any arteriopathy. Among 233 ischemic stroke cases, craniocervical arterial dissection was diagnosed in 13 patients (5.6%; 10 males), with a mean age of 7.5 years. Initial time-of-flight magnetic resonance angiography missed dissection in 8 patients (61.5%) because the neck vessels were not scanned (n = 2), of suboptimal technique (n = 3), and of diagnostic error (n = 3). T1 fat-saturated MRI and contrast-enhanced magnetic resonance angiography were not performed in 12 patients. If suspicion for arterial dissection is high, T1 fat-saturated neck imaging and contrast-enhanced magnetic resonance angiography should be considered to maximize detection.

Spin-echo T1-weighted imaging of the brain with interleaved acquisition and presaturation pulse at 3 T: a feasibility study before clinical use

RATIONALE AND OBJECTIVES

Although spin-echo (SE) sequence has some advantages over gradient-echo sequence in brain imaging, gradient-echo sequence is commonly used for T1-weighted imaging (T1WI) at 3 T because contrast on SE T1WI is widely believed to be poor at 3 T. Recently, gray-white matter contrast on single-slice and multi-slice SE imaging with interslice gap was reported as better at 3 T than at 1.5 T. This study examined the feasibility of interleaved SE T1WI of the brain at 3 T. This study also examined whether presaturation pulse (PP) sufficiently suppresses intra-arterial signals because these signals tend to be hyperintense due to longer T1 at 3 T.

MATERIALS AND METHODS

Subjects consisted of 18 healthy volunteers. Two sets of T1WI were performed using SE sequence. One set consisted of imaging without PP, and the other consisted of imaging with PP. Each set contained three types of gapless imaging as follows; sequential, 100% interleaved, and 200% interleaved imaging. In each subject, contrast-to-noise ratio between gray-matter and white-matter (CNR(GM-WM)) and intra-arterial signals were evaluated.

RESULTS

CNR(GM-WM) was significantly higher on interleaved images than on sequential images, regardless of PP (P < .0001). PP sufficiently suppressed intra-arterial signals (P < .0001).

CONCLUSION

CNR(GM-WM) on SE T1WI at 3 T can be improved by interleaved acquisition, and PP sufficiently suppressed intra-arterial signals. Interleaved SE T1WI with PP appears clinically feasible at 3 T.

Late complications of vertebral artery dissection in children: pseudoaneurysm, thrombosis, and recurrent stroke

Craniocervical arterial dissection is an important cause of childhood arterial ischemic stroke, accounting for 7.5% to 20% of cases. Significant neurologic morbidity and mortality may result and recurrence risk may be higher than in adults. However, the natural history and long-term outcome of pediatric dissection are poorly studied. We report 3 cases of extracranial vertebral artery dissection with complications including pseudoaneurysm formation, recurrent stroke, and late spontaneous thrombosis of the dissected artery. These cases illustrate the dynamic processes involved in vascular injury and healing of vertebral artery dissection in children over years, with potential implications for long-term management and prevention of recurrence.

Vertebral artery dissection with a normal-appearing lumen at multisection CT angiography: the importance of identifying wall hematoma

BACKGROUND AND PURPOSE

CT angiography (CTA) is widely used and may be the only vascular imaging technique ordered for emergent evaluation of neurovascular disease. With thin-section multisection CTA, the resolution of vessel wall imaging has improved. We describe cases of acute vertebral artery dissection (VAD) in which the only abnormality on CTA was a characteristic thickening of the wall of the V3 portion of the vertebral artery (VA). The arterial lumen at the dissection site was normal in caliber. This type of dissection is easily overlooked if only lumen-opacifying studies such as contrast MR angiography (MRA) or conventional angiography are performed. We highlight the importance of recognizing this finding, the "suboccipital rind" sign, in the V3 portion, a segment commonly affected in VAD. The purpose of our study was to review the CTA imaging characteristics of patients with VAD in the V3 portion compared with normal controls.

MATERIALS AND METHODS

Our imaging data base was reviewed for cases of acute VAD and the presence of a "suboccipital rind" sign. A control group of 50 patients was randomly recruited from a group of patients undergoing CTA. The VA luminal diameter, the wall thickness (total diameter-luminal diameter), and the ratio of luminal diameter/total diameter were measured along 5 adjacent V3 segments and were compared between the 2 groups.

RESULTS

There was no evidence of luminal tapering or narrowing in the dissected VAs compared with controls (P = .1). The average wall thickness of the dissection group was 2.96 mm greater than that for the control group (P < .001; 95% confidence interval, 2.6-3.3). There was a significant difference in the ratio of lumen diameter/lumen+wall diameter in dissected segments compared with controls (P < .001).

CONCLUSIONS

Cross-sectional vascular imaging is often performed with multisection helical CTA for a variety of concerns, some without neurologic symptoms. Our study confirms that in cases of the "suboccipital rind" sign, the lumen appears normal in caliber, with wall thickening as the only imaging sign of VAD. In our center, this clinically occult VAD would influence management, with patients usually treated with antiplatelet agents. We caution against using only luminal-opacifying techniques such as contrast-enhanced MRA or conventional angiography to exclude VAD because they are limited in the evaluation of mural hematoma.

Craniocervical arterial dissection: spectrum of imaging findings and differential diagnosis

Craniocervical artery dissection is a potentially disabling yet probably underrecognized condition that often occurs in young and middle-aged adults. Accurate and prompt diagnosis of this condition is crucial because timely and appropriate therapy can significantly reduce the risk of stroke and long-term sequelae. Because of the great diversity in the clinical features of craniocervical artery dissection, imaging plays a primary role in its diagnosis. The increased diagnosis of this disorder in the past two decades can be attributed to an increased awareness of the clinical manifestations of internal carotid artery and vertebral artery dissection and to use of noninvasive diagnostic imaging techniques. To achieve an accurate diagnosis of craniocervical artery dissection, it is important to be familiar with its pathologic features (intimal tear, intramural hematoma, and dissecting aneurysm); the spectrum of imaging findings at color duplex ultrasonography, computed tomographic angiography, magnetic resonance (MR) imaging with MR angiography, and conventional angiography; and potential pitfalls in image interpretation.

Overreliance on symptom quality in diagnosing dizziness: results of a multicenter survey of emergency physicians

OBJECTIVE

To assess emergency physicians' diagnostic approach to the patient with dizziness, using a multicenter quantitative survey.

PARTICIPANTS AND METHODS

We anonymously surveyed attending and resident emergency physicians at 17 academic-affiliated emergency departments with an Internet-based survey (September 1, 2006, to November 3, 2006). The survey respondents ranked the relative importance of symptom quality, timing, triggers, and associated symptoms and indicated their agreement with 20 statements about diagnostic assessment of dizziness (Likert scale). We used logistic regression to assess the impact of "symptom quality ranked first" on odds of agreement with diagnostic statements; we then stratified responses by academic rank.

RESULTS

Of the 505 individuals surveyed, 415 responded for an overall response rate of 82%. A total of 93% (95% confidence interval [CI], 90%-95%) agreed that determining type of dizziness is very important, and 64% (95% CI, 60%-69%) ranked symptom quality as the most important diagnostic feature. In a multivariate model, those ranking quality first (particularly resident physicians) more often reported high-risk reasoning that might predispose patients to misdiagnosis (eg, in a patient with persistent, continuous dizziness, who could have a cerebellar stroke, resident physicians reported feeling reassured that a normal head computed tomogram indicates that the patient can safely go home) (odds ratio, 6.74; 95% CI, 2.05-22.19).

CONCLUSION

Physicians report taking a quality-of-symptoms approach to the diagnosis of dizziness in patients in the emergency department. Those relying heavily on this approach may be predisposed to high-risk downstream diagnostic reasoning. Other clinical features (eg, timing, triggers, associated symptoms) appear relatively undervalued. Educational initiatives merit consideration.

Therapeutic Endovascular Treatments for Traumatic Vertebral Artery Injuries

OBJECTIVE

Traumatic vertebral artery injuries pose difficulty in early diagnosis and management because of concomitant neurologic dysfunction and limitations in direct surgical access. The purpose of this report is to review endovascular therapy in patients with traumatic vertebral artery injuries for preservation of the parent artery, and to determine the safety and efficacy of such endovascular therapy.

METHODS

Six patients with traumatic vertebral artery lesions were treated using therapeutic endovascular methods. Endovascular therapy was accomplished by stent insertion or coil embolization or both.

RESULTS

Except one patient who underwent coil embolization of a transected vertebral artery, all dissections and pseudoaneurysms were successfully treated by stent placement or stent-assisted coiling with preservation of parent arteries. No additional surgical procedures for vascular lesions were required. There were no delayed neurologic or vascular complications and no lesions recurred during the follow-up period (mean, 36.7 months).

CONCLUSION

The author's experience demonstrates that endovascular therapy using stents and coils is both feasible and safe in the treatment of traumatic vertebral artery injuries. Endovascular therapy selectively eliminated the vascular abnormality while maintaining the normal patency of the cerebral arteries. Long-term follow-up review of these repairs will be necessary to provide a full evaluation of the safety and efficacy of these devices.

State of the art: noninvasive imaging and management of neurovascular trauma

Neurotrauma represents a significant public health problem, accounting for a significant proportion of the morbidity and mortality associated with all traumatic injuries. Both blunt and penetrating injuries to cervicocerebral vessels are significant and are likely more common than previously recognized. Imaging of such injuries is an important component in the evaluation of individuals presenting with such potential injuries, made all the more important since many of the vascular injuries are clinically silent. Management of injuries, particularly those caused by blunt trauma, is constantly evolving. This article addresses the current state of imaging and treatment of such injuries.

Dissection of the V4 segment of the vertebral artery: clinicoradiologic manifestations and endovascular treatment

Intracranial vertebral artery (VA) dissection has three clinical presentations: ischemia, hemorrhage, and mass effect. Imaging findings of intracranial VA dissections vary according to clinical presentation. Irregular stenosis or occlusion of the VA is the most common finding in patients with posterior fossa infarction, whereas a dissecting aneurysm is the main feature in those with acute subarachnoid hemorrhage. A chronic, giant, dissecting aneurysm can cause mass effect on the brain stem or cranial nerves, as well as distal embolism. Magnetic resonance imaging is useful for detection of intramural hematomas and intimal flaps, both of which are diagnostic of VA dissection. Multidetector computed tomography angiography is increasingly used for diagnosis of VA dissection. Catheter angiography is still beneficial for evaluation of precise endoluminal morphology of the dissection before surgical or endovascular intervention. Endovascular treatment is now considered a major therapeutic option for patients with a ruptured dissecting aneurysm or a chronic dissecting aneurysm. Anticoagulation therapy is currently considered the initial treatment of choice in patients with posterior circulation ischemic symptoms. Endovascular treatment, such as stent-assisted angioplasty or coil occlusion at the dissection site, can be performed in selected patients with posterior fossa ischemic symptoms.

Imaging of Traumatic Neurovascular Injury

Traumatic injury to the major vessels of the head and neck can result in potentially devastating neurologic sequelae. Until recently, conventional angiography was the primary imaging modality used to evaluate these often challenging patients. Advances in cross-sectional imaging have improved the ability to screen for these lesions, which have been found to be more common than previously thought; however, accepted protocols of imaging evaluation have not yet been fully established. This article presents a general approach to the patient with suspected neurovascular injury. This includes a discussion of the histopathologic spectrum, clinical presentation, mechanisms, radiologic work-up, pertinent issues of the most common lesions, and some of the endovascular techniques used in their management.

An Analysis of the Etiology of Cervical Artery Dissections: 1994 to 2003

OBJECTIVE

To provide a literature review of the etiologic breakdown of cervical artery dissections.

METHODS

A literature search of the MEDLINE database was conducted for English-language articles published from 1994 to 2003 using the search terms cervical artery dissection (CAD), vertebral artery dissection, and internal carotid artery dissection. Articles were selected for inclusion only if they incorporated a minimum of 5 case reports of CAD and contained sufficient information to ascertain a plausible etiology.

RESULTS

One thousand fourteen citations were identified; 20 met the selection criteria. There were 606 CAD cases reported in these studies; 321 (54%) were internal carotid artery dissection and 253 (46%) were vertebral artery dissection, not including cases with both. Three hundred seventy-one (61%) were classified as spontaneous, 178 (30%) were associated with trauma/trivial trauma, and 53 (9%) were associated with cervical spinal manipulation. If one apparently biased study is dropped from the data pool, the percentage of CADs related to cervical spinal manipulation drops to approximately 6%.

CONCLUSIONS

The case series that were reviewed in this article indicated that most CADs reported in the previous decade were spontaneous but that some were associated with trauma/trivial trauma, and a minority with cervical spine manipulation. This etiologic breakdown of CAD does not differ significantly from what has been portrayed by most other authors.

Non-Atherosclerotic Vascular Disease in the Young

There are a large variety of non-atherosclerotic causes of ischemic stroke in the young. Arterial dissection, most commonly associated with non-traumatic causes, is among the most common. Both the carotid and vertebrobasilar circulations can be affected. The vasculitidies represent a rare, but potentially treatable series of conditions that can lead to stroke through diverse mechanisms. Moyamoya is a nonatherosclerotic, noninflammatory, nonamyloid vasculopathy characterized by chronic progressive stenosis or occlusion of the distal internal carotid arteries and/or proximal portions of the middle and/or anterior cerebral arteries. Moyamoya can be idiopathic (moyamoya disease) or the result of other conditions. An appreciation of the unusual causes of stroke in the young is important when considering secondary prevention measures.

Traumatic vertebral artery dissection in a child with brachial plexus injury

Traumatic vertebral artery dissection is an unusual event in children, but early recognition and treatment are important to prevent neurological deficits. The authors present a case of a 4-year-old boy with a traumatic extracranial vertebral artery dissection, who suffers from left arm monoplegia due to brachial plexus injury.

Penetrating Injuries of the Neck: Use of Helical Computed Tomographic Angiography

The diagnostic evaluation of stable patients with penetrating trauma to the neck remains controversial. Conventional angiography has traditionally been considered the gold standard for evaluation of vascular injuries. The use of angiography for stable patients with penetrating neck trauma has been questioned because of its invasive nature and reported low yield. In recent years, there has been a renewed interest in the use of noninvasive techniques such as helical computed tomographic (CT) angiography for the evaluation of these patients. Helical CT angiography, a low-risk, rapid, accurate, noninvasive, reproducible technique, is less expensive than conventional angiography. Helical CT angiography also can provide information about potential lesions of associated vital structures such as the cervical spine and the aerodigestive tract. This review evaluates the authors' current protocol for penetrating neck wounds and identifies indications for helical CT angiography.

Computed Tomography and Magnetic Resonance Angiography in Cervicocranial Vascular Disease

Although catheter angiography, or digital subtraction angiography (DSA), is still regarded as the gold standard for imaging of cervicocranial vascular disease, its morbidity, cost, and time-consuming features have prompted the development of noninvasive techniques based on computed tomography (CT) and magnetic resonance imaging. With the advent of powerful software, CT and magnetic resonance angiography are complementing and, in some cases, even replacing DSA in the diagnostic evaluation of carotid atherostenosis, unruptured aneurysms, dissections, stroke, penetrating trauma to the neck, and dural venous sinus occlusive disease. They offer advantages over DSA not only in reduced morbidity and time-saving but also in assessment of brain parenchyma, quantitative perfusion, and abnormalities of vessel walls. In the evaluation of blunt neck injuries and intracranial vascular malformations, fistulas, and vasculitis, CT and magnetic resonance angiography still do not provide as much information as DSA.

Penetrating injuries of the neck and the increasing role of CTA

Vascular injuries of the neck are most frequently the result of penetrating trauma. Diagnostic evaluation of hemodynamically stable patients who have suffered penetrating neck wounds is challenging and remains controversial. In order to reduce morbidity and mortality, prompt diagnosis and subsequent treatment of these injuries is critical. Traditionally, these patients undergo direct contrast angiography. However, this technique has limitations including its invasive nature and potential complications. The use of routine screening angiography has also been questioned because of the low rate of positive examinations. More recently, helical and multislice CT angiography (CTA) has emerged as a fast, minimally invasive accurate study to evaluate penetrating neck injuries. CTA is not operator-dependent and the results can be reproduced easily by using established technical parameters. It is readily available in most centers and allows the simultaneous evaluation of the extravascular soft tissues and bones.

CT, MR Imaging, and MR Angiography in the Evaluation of Patients with Acute Stroke

The patient with acute stroke presents a full challenge to the diagnostic and therapeutic aspects of medicine in all forms, from community through tertiary care. Patients with brain damage in the ischemic, but not yet infarcted, phase have the greatest potential for recovery. Herein, the author reviews the most commonly employed diagnostic tools that are currently used before stroke therapy. The logistical demands of emergency evaluation of a patient at a given institution often dictate which modality can and should be practically applied. Any of the available modalities, when used well, can offer pertinent diagnostic and even predictive information to assist in the quick, accurate classification of patients to the most appropriate treatment group.

Neurovascular injuries of the spinal cord

Neurovascular spinal cord injuries are very prevalent and in a busy trauma center radiology practice these injuries are commonly seen. Imaging neurovascular injuries has been greatly facilitated by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). The histopathological changes that occur with spinal cord trauma have been found to correlate well with what is seen on MRI examinations. The MRI findings in spinal cord trauma have also been found to be useful in determining patient prognosis. Spinal cord infarcts due to arterial injury from trauma are relatively rare, but it has been shown by imaging that vertebral artery injuries are not an unusual occurrence. The specific findings associated with neurovascular injuries will be described with an emphasis on the findings on MRI and MRA examinations. MRI and MRA techniques have become the procedure of choice for evaluating neurovascular injuries because of their proven accuracy and because they are non-invasive. Conventional angiography, although, does remain quite useful for evaluating arterial injuries.

Normal variation of vertebral artery on CT angiography and its implications for diagnosis of acquired pathology

PURPOSE

CT angiography (CTA) is rapidly becoming a popular tool for the evaluation of cerebrovascular diseases. Noninvasive diagnosis of vertebral artery pathology using CTA relies in part on diminished vertebral artery size or eccentric position relative to the transverse foramen. However, normal variation of the vertebral artery on CT has not been systematically described.

METHOD

Patients younger than 40 years who underwent CTA for reasons other than evaluation of vertebral artery disease were studied. Area measurements of the vertebral artery and the transverse foramen were performed by three radiologists. Variance component analysis was performed.

RESULTS

There is marked variation in the size of the vertebral artery relative to the transverse foramen, with the vertebral artery occupying 8-85% of the foramen. In many patients, marked asymmetry in relative vertebral artery size and position was observed. This asymmetry would often vary markedly from level to level within the same patient.

CONCLUSION

Vertebral artery size and position in the transverse foramina vary markedly in normal young subjects. These normal variations must be considered when evaluating vertebral artery pathology on CT angiograms.

Vertebrobasilar dissection: a possible role of whiplash injury in its pathogenesis

We reviewed 29 patients with vertebrobasilar dissections (VBD) to investigate the correlation between minor trauma and VBD and the clinical features of this trauma-related condition. Mean age was 43 years, with a male predominance (male/female ratio was 25/4). Seventeen patients presented with subarachnoid hemorrhage (SAH), and 12 with ischemic symptoms. Two patients presenting with ischemia had extracranial VBD (V3 segment). Angiographically, aneurysmal dilatation was observed in most SAH patients (13 patients) in contrast to narrowing or occlusion in most ischemic patients (10 patients). Among the 12 SAH patients treated with coil embolization or conservatively, five died, whereas all ischemic patients recovered well with anticoagulation and/or antiplatelet therapy. Seven patients had received minor or trivial head/cervical trauma, due to whiplash injury, minor fall, or during exercise, which were identified to precede with the lapse of some time (a few minutes or days) the onset of symptoms. All of these patients presented with ischemic symptoms, and they were younger than the other ischemic or SAH patients. The site of vertebral artery dissection was intracranial in four cases, extracranial in one case, and combined in two cases at the level of the V3 segment and the origin of the posterior inferior cerebellar artery. However, no SAH occurred. These clinicopathological findings, i.e. ischemia and angiographic narrowing/occlusion, suggest that dissections were subintimal. Therefore, it is believed that this minor or trivial trauma may primarily cause subintimal dissection with luminal compromise, leading to ischemic symptoms, rather than subadventitial or transmural dissection with aneurysmal dilatation, leading to SAH. This lesion may also occur in younger patients with a favorable outcome. Careful note should be made of patient for the early recognition of this disorder.