Abstract:We performed magnetic resonance angiography (MRA) and susceptibility-weighted imaging (SWI) to observe cerebral changes during a migraine attack in a 28-year-old man. MRA revealed regional arterial spasm, andˆndings of SWI were consistent with decreased blood ‰ow and/or venous dilatation. Because these noninvasive techniques can be performed repeatedly at short intervals, they can be useful for evaluating hemodynamic changes during and after migraine attacks.
“…PWI is not really helpful because both mildly increased [ 46 ] and decreased [ 47 ] perfusions have been reported. Magnetic resonance spectroscopy may instead help diagnose acute demyelinating lesions as it shows a reduction of the N-acetylaspartate peak while choline is typically increased [ 58 ], and a negative doublet corresponding to lactate is abnormally visible on long TE [ 49 ]. Fig.…”
Section: Stroke Mimics With Abnormal Dwimentioning
confidence: 99%
“…These abnormalities are observed in brain regions corresponding to the patient’s symptoms, with a predilection for the posterior regions. Bilateral hypoperfusion can be seen, and TOF-MRA may reveal regional and distal loss of visibility of the arteries in relation with the hypoperfused areas [ 58 ]. On the other hand, because of the increased oxygen extraction and relative increase of deoxyhaemoglobin in the hypoperfused brain parenchyma, T2-GRE or SWI shows dilated cortical veins draining these regions [ 59 ].…”
Acute ischaemic stroke represents the most common cause of new sudden neurological deficit, but other diseases mimicking stroke happen in about one-third of the cases. Magnetic resonance imaging (MRI) is the best technique to identify those ‘stroke mimics’. In this article, we propose a diagnostic approach of those stroke mimics on MRI according to an algorithm based on diffusion-weighted imaging (DWI), which can be abnormal or normal, followed by the results of other common additional MRI sequences, such as T2 with gradient recalled echo weighted imaging (T2-GRE) and fluid-attenuated inversion recovery (FLAIR). Analysis of the signal intensity of the parenchyma, the intracranial arteries and, overall, of the veins, is crucial on T2-GRE, while anatomic distribution of the parenchymal lesions is essential on FLAIR. Among stroke mimics with abnormal DWI, T2-GRE demonstrates obvious abnormalities in case of intracerebral haemorrhage or cerebral amyloid angiopathy, but this sequence also allows to propose alternative diagnoses when DWI is negative, such as in migraine aura or headaches with associated neurological deficits and lymphocytosis (HaNDL), in which cortical venous prominence is observed at the acute phase on T2-GRE. FLAIR is also of major interest when DWI is positive by better showing evocative distribution of cerebral lesions in case of seizure (involving the hippocampus, pulvinar and cortex), hypoglycaemia (bilateral lesions in the posterior limb of the internal capsules, corona radiata, striata or splenium of the corpus callosum) or in posterior reversible encephalopathy syndrome (PRES). Other real stroke mimics such as mitochondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS), Susac’s syndrome, brain tumour, demyelinating diseases and herpes simplex encephalitis are also included in our detailed and practical algorithm.Key points
• About 30% of sudden neurological deficits are due to non-ischaemic causes.
• MRI is the best technique to identify stroke mimics.
• Our practical illustrated algorithm based on DWI helps to recognise stroke mimics.
“…PWI is not really helpful because both mildly increased [ 46 ] and decreased [ 47 ] perfusions have been reported. Magnetic resonance spectroscopy may instead help diagnose acute demyelinating lesions as it shows a reduction of the N-acetylaspartate peak while choline is typically increased [ 58 ], and a negative doublet corresponding to lactate is abnormally visible on long TE [ 49 ]. Fig.…”
Section: Stroke Mimics With Abnormal Dwimentioning
confidence: 99%
“…These abnormalities are observed in brain regions corresponding to the patient’s symptoms, with a predilection for the posterior regions. Bilateral hypoperfusion can be seen, and TOF-MRA may reveal regional and distal loss of visibility of the arteries in relation with the hypoperfused areas [ 58 ]. On the other hand, because of the increased oxygen extraction and relative increase of deoxyhaemoglobin in the hypoperfused brain parenchyma, T2-GRE or SWI shows dilated cortical veins draining these regions [ 59 ].…”
Acute ischaemic stroke represents the most common cause of new sudden neurological deficit, but other diseases mimicking stroke happen in about one-third of the cases. Magnetic resonance imaging (MRI) is the best technique to identify those ‘stroke mimics’. In this article, we propose a diagnostic approach of those stroke mimics on MRI according to an algorithm based on diffusion-weighted imaging (DWI), which can be abnormal or normal, followed by the results of other common additional MRI sequences, such as T2 with gradient recalled echo weighted imaging (T2-GRE) and fluid-attenuated inversion recovery (FLAIR). Analysis of the signal intensity of the parenchyma, the intracranial arteries and, overall, of the veins, is crucial on T2-GRE, while anatomic distribution of the parenchymal lesions is essential on FLAIR. Among stroke mimics with abnormal DWI, T2-GRE demonstrates obvious abnormalities in case of intracerebral haemorrhage or cerebral amyloid angiopathy, but this sequence also allows to propose alternative diagnoses when DWI is negative, such as in migraine aura or headaches with associated neurological deficits and lymphocytosis (HaNDL), in which cortical venous prominence is observed at the acute phase on T2-GRE. FLAIR is also of major interest when DWI is positive by better showing evocative distribution of cerebral lesions in case of seizure (involving the hippocampus, pulvinar and cortex), hypoglycaemia (bilateral lesions in the posterior limb of the internal capsules, corona radiata, striata or splenium of the corpus callosum) or in posterior reversible encephalopathy syndrome (PRES). Other real stroke mimics such as mitochondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes (MELAS), Susac’s syndrome, brain tumour, demyelinating diseases and herpes simplex encephalitis are also included in our detailed and practical algorithm.Key points
• About 30% of sudden neurological deficits are due to non-ischaemic causes.
• MRI is the best technique to identify stroke mimics.
• Our practical illustrated algorithm based on DWI helps to recognise stroke mimics.
“…31,32 A study using MR angiography (MRA) and susceptibilityweighted imaging (SWI) during a migraine attack in a young man revealed regional arterial spasm, and findings of SWI were consistent with decreased blood flow or venous dilation. 33 Landmark MRA investigations assessed intracranial vasodilation and blood flow in 20 nitroglycerin (NTG)-induced attacks of migraine. 34 During migraine, blood vessel diameters were no different from baseline, and there was no difference between headache and non-headache sides.…”
Section: This Review Was Initiated With a Pubmed Search Of The Us Natmentioning
Modern imaging methods provide unprecedented insights into brain structure, perfusion, metabolism, and neurochemistry, both during and between migraine attacks. Neuroimaging investigations conducted in recent decades bring us closer to uncovering migraine as a multifaceted, primarily central nervous system disorder. Three main categories of structural and functional brain changes are described in this review, corresponding to the migrainous aura, ictal headache, and interictal states. (Headache 2013;53:46-66)
“…7 Although CVS measurements offer precise information on the thrombotic region, a simpler detection method involves the presence of dilated and hypointense cortical vessels on SW images. 97 The dilated region on SWI correlates with MR angiography (MRA) findings 93 and could be used to monitor occlusion, 57 along with the possibility for hemorrhagic transformation, 57,64 over time.…”
T he initial development of MR venography by Reichenbach et al. 90 laid the foundation for Haacke et al. 42 to apply the principles of MR venography in conventional MRI for broader usage in clinical and research settings. By utilizing magnitude and phase information, both of which are normally acquired from conventional MRI data, susceptibility weighted imaging (SWI) has an enhanced ability to detect microhemorrhages 4,12,26 and microvasculature. 26,27,41,92 It is a highly sensitive imaging modality able to depict magnetic substances, such as deoxygenated hemoglobin, with high contrast 42 and to help investigate neurological diseases, 82 grade tumors, 25,63 and assist in determining treatment or prognosis. 18,26,37,70,71,115 Over the past years, the SWI technique has found applications in the different fields of neurosurgery, namely neurooncology, vascular neurosurgery, neurotraumatolabbreviatioNs AVM = arteriovenous malformation; CCM = cerebral cavernous malformation; CMB = cerebral microbleed; CVS = cortical vessel sign; DAI = diffuse axonal injury; DBS = deep brain stimulation; DWI = diffusion-weighted imaging; GBM = glioblastoma multiforme; GCS = Glasgow Coma Scale; GPe = external globus pallidus; GPi = internal GP; GRE = gradient-recalled echo; ITSS = intratumoral susceptibility signal; mIP = minimum intensity projection; MRA = MR angiography; MS = multiple sclerosis; PD = proton density; PQ = percentagewise quantification; PWI = perfusion-weighted imaging; SN = substantia nigra; STN = subthalamic nucleus; SWI = susceptibility weighted imaging; TBI = traumatic brain injury; VM = vascular malformation. Susceptibility weighted imaging (SWI) is a relatively new imaging technique. Its high sensitivity to hemorrhagic components and ability to depict microvasculature by means of susceptibility effects within the veins allow for the accurate detection, grading, and monitoring of brain tumors. This imaging modality can also detect changes in blood flow to monitor stroke recovery and reveal specific subtypes of vascular malformations. In addition, small punctate lesions can be demonstrated with SWI, suggesting diffuse axonal injury, and the location of these lesions can help predict neurological outcome in patients. This imaging technique is also beneficial for applications in functional neurosurgery given its ability to clearly depict and differentiate deep midbrain nuclei and close submillimeter veins, both of which are necessary for presurgical planning of deep brain stimulation. By exploiting the magnetic susceptibilities of substances within the body, such as deoxyhemoglobin, calcium, and iron, SWI can clearly visualize the vasculature and hemorrhagic components even without the use of contrast agents. The high sensitivity of SWI relative to other imaging techniques in showing tumor vasculature and microhemorrhages suggests that it is an effective imaging modality that provides additional information not shown using conventional MRI. Despite SWI's clinical advantages, its implementation in MRI protocols is st...
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