MR imaging and histologic features of subinsular bright spots on T2-weighted MR images: Virchow-Robin spaces of the extreme capsule and insular cortex

Enlarging and shrinking focal perivascular spaces

BACKGROUND AND PURPOSE

Perivascular spaces (PVS) are interstitial fluid-filled spaces surrounding blood vessels traversing the deep gray nuclei and white matter of the brain. These are commonly encountered on CT and MR imaging and are generally asymptomatic and of no clinical significance. However, occasional changes in the size of focal PVS, for example, when enlarging, may mimic pathologies including neoplasms and infections, hence potentially confounding radiological interpretation. Given these potential diagnostic issues, we sought to better characterize common clinical and imaging features of focal PVS demonstrating size fluctuations.

MATERIALS AND METHODS

Upon institutional approval, we retrospectively identified 4 cases demonstrating PVS with size changes at our institution. To supplement our cases, we also performed a literature review, which identified an additional 14 cases. Their clinical and imaging data were analyzed to identify characteristic features.

RESULTS

Of the 18 total cases (including the 4 institutional cases), 10 cases increased and 8 decreased in size. These focal PVS ranged from 0.4-4.5 cm in size. Whereas a decrease in size did not represent a diagnostic issue, focal increase in size of PVS led to concerning differential diagnoses in at least 30% of the radiology reports. These enlarging PVS were most found in the basal ganglia and temporal lobe, and in patients with previous brain radiation treatment.

CONCLUSION

Focal size change of PVS can occur, especially years after brain radiation treatment. Being cognizant of this benign finding is important to consider in the differential diagnosis to avoid undue patient anxiety or unnecessary medical intervention.

Neuropathology of Vascular Brain Health: Insights From Ex Vivo Magnetic Resonance Imaging-Histopathology Studies in Cerebral Small Vessel Disease

Sporadic cerebral small vessel disease (SVD) is a major contributor to vascular cognitive impairment and dementia in the aging human brain. On neuropathology, sporadic SVD is characterized by abnormalities to the small vessels of the brain predominantly in the form of cerebral amyloid angiopathy and arteriolosclerosis. These pathologies frequently coexist with Alzheimer disease changes, such as plaques and tangles, in a single brain. Conversely, during life, magnetic resonance imaging (MRI) only captures the larger manifestations of SVD in the form of parenchymal brain abnormalities. There appears to be a major knowledge gap regarding the underlying neuropathology of individual MRI-detectable SVD abnormalities. Ex vivo MRI in postmortem human brain tissue is a powerful tool to bridge this gap. This review summarizes current insights into the histopathologic correlations of MRI manifestations of SVD, their underlying cause, presumed pathophysiology, and associated secondary tissue injury. Moreover, we discuss the advantages and limitations of ex vivo MRI-guided histopathologic investigations and make recommendations for future studies.

Giant tumefactive perivascular spaces in a pediatric patient: A rare radiological entity

Background:

Giant tumefactive perivascular spaces (TPVS) are radiological rarities and may mimic other neurological structural lesions. Fewer than 80 cases have been reported in the literature with even fewer in the pediatric population.

Case Description:

The authors present an image report showcasing a 3-year-old boy presenting with uncontrolled seizures despite multiple anti-epileptic medications. His magnetic resonance imaging showed multiple, non-contrast enhancing cyst clusters within the left parieto-occipital region that was hyperintense on T2-weighted imaging, and isointense to cerebrospinal fluid. Due to a characteristic absence of perilesional edema seen on fluid-attenuated inversion recovery imaging or diffusion restriction on diffusion-weighted imaging (DWI) sequences, this was diagnosed as a giant TPVS.

Conclusion:

Accurate diagnosis of these rare radiological entities is based on pathognomonic findings that can help prevent unnecessary surgery and guide management for patients, particularly in the pediatric population as seen in our case.

Contribution of advanced MRI to the diagnosis of giant tumefactive perivascular spaces

BACKGROUND

Giant tumefactive perivascular spaces (PVSs) are uncommon benign cystic lesions. They can imitate cystic neoplasms.

PURPOSE

To evaluate the contribution of advanced neuro magnetic resonance imaging (MRI) techniques in the diagnosis of giant tumefactive PVSs and to further characterize these unusual cerebral lesions.

MATERIAL AND METHODS

The MRI scans of patients with tumefactive PVS diagnosed between 2010 and 2019 were retrospectively reviewed. All imaging studies included three plane conventional cerebral MRI sequences as well as precontrast 3D T1 MPRAGE, post-gadolinium 3D T1 acquisitions, sagittal plane 3D T2 SPACE, diffusion-weighted imaging, and time-of-flight (TOF) angiography. Some patients received perfusion MR, MR spectroscopy, diffusion tensor imaging (DTI), and contrast-enhanced TOF MR angiography.

RESULTS

A perforating vessel was demonstrated in 16 patients (66.7%) by TOF imaging. In four patients, there were intracystic vascular collaterals on contrast-enhanced TOF MR angiography. Septal blooming was observed in four patients in susceptibility-weighted imaging. On perfusion MR, central hyperperfusion was observed in four patients, and peripheral hyperperfusion was observed in one patient. On MR spectroscopy, choline increase was observed in two patients, and there was a lactate peak in three patients, and both a choline increase and lactate peak in one patient. On DTI, there was fiber distortion in five patients and fiber deformation in one patient.

CONCLUSION

Advanced MRI techniques and 3D volumetric high-resolution MRI sequences can provide a valuable contribution to the diagnosis and can be successfully used in the management of these lesions.

Anatomical Variations, Mimics, and Pitfalls in Imaging of Patients with Epilepsy

Epilepsy is among one of the most common neurologic disorders. The role of magnetic resonance imaging (MRI) in the diagnosis and management of patients with epilepsy is well established, and most patients with epilepsy are likely to undergo at least one or more MRI examinations in the course of their disease. Recent advances in high-field MRI have enabled high resolution in vivo visualization of small and intricate anatomic structures that are of great importance in the assessment of seizure disorders. Familiarity with normal anatomic variations is essential in the accurate diagnosis and image interpretation, as these variations may be mistaken for epileptogenic foci, leading to unnecessary follow-up imaging, or worse, unnecessary treatment. After a brief overview of normal imaging anatomy of the mesial temporal lobe, this article will review a few important common and uncommon anatomic variations, mimics, and pitfalls that may be encountered in the imaging evaluation of patients with epilepsy.

Stereo-EEG exploration in the insula/operculum in paediatric patients with refractory epilepsy

PURPOSE

Failure to recognise involvement of the insula / opercula (I/O) region is associated with poor outcome in epilepsy surgery. Recognition is challenging due to high connectivity with adjacent structures resulting in variable and misleading semiology, often subjective and therefore likely to be underreported by children. In this study we explored prevalence and characteristics of I/O involvement in paediatric patients undergoing sEEG exploration.

METHOD

We retrospectively included all consecutive patients undergoing sEEG at our centre between 11/2014 and 01/2018 with at least three contacts within I/O and excluded those with undetermined seizure onset zone (SOZ) by sEEG. We divided patients into three groups: 1) SOZ in I/O, 2) spread to I/O and 3) no I/O involvement. We compared pre-invasive characteristics, sEEG results, surgery and outcome for each group.

RESULTS

29 of all 53 consecutive patients had an identified SOZ by sEEG and at least three contacts within the I/O and were included. 41% had I/O SOZ, 38% had I/O spread and 21% had no I/O involvement. Insula associated symptoms described in adult literature were not statistically different between the three groups. Complications due to sEEG were low (2 of 53 patients). Following I/O surgery, 63% were seizure free while an additional 26% of patients achieved seizure reduction. Postoperative deficits were seen in 75% of the patients but completely resolved in all but one patient.

CONCLUSIONS

Our data suggest an important role of the I/O region with frequent onset or propagation to the I/O region (at least 64% of all 53 sEEG cases). Semiology appears less specific than in adults. Insula depth electrode insertion is safe with subsequent good surgical outcomes albeit common transient deficits.

Tumefactive perivascular space demonstrated with post-contrast time-of-flight MR angiography

The cerebral perivascular spaces are interstitial fluid-filled anatomic structures surrounding the perforating arteries. They appear as small, round or curvilinear structures on magnetic resonance (MR) imaging. Occasionally, these structures may become very large and cause mass effect. In this case, they may imitate malignant processes and are referred to as tumefactive perivascular spaces. In this study, we present a case of tumefactive perivascular space demonstrated with post-contrast time-of-flight (TOF) MR angiography. To our knowledge, there have been no previous clear demonstrations of the perforating artery in tumefactive perivascular space with contrast-enhanced TOF MR angiography. The purpose of this study was to describe advanced imaging findings in this unusual condition.

Differences in Signal Intensity and Enhancement on MR Images of the Perivascular Spaces in the Basal Ganglia versus Those in White Matter

Purpose:

To elucidate differences between the perivascular space (PVS) in the basal ganglia (BG) versus that found in white matter (WM) using heavily T₂-weighted FLAIR (hT₂-FL) in terms of 1) signal intensity on non-contrast enhanced images, and 2) the degree of contrast enhancement by intravenous single dose administration of gadolinium based contrast agent (IV-SD-GBCA).

Materials and Methods:

Eight healthy men and 13 patients with suspected endolymphatic hydrops were included. No subjects had renal insufficiency. All subjects received IV-SD-GBCA. MR cisternography (MRC) and hT₂-FL images were obtained prior to and 4 h after IV-SD-GBCA. The signal intensity of the PVS in the BG, subinsular WM, and the cerebrospinal fluid (CSF) in Ambient cistern (CSF_AC) and CSF in Sylvian fissure (CSF_Syl) was measured as well as that of the thalamus. The signal intensity ratio (SIR) was calculated by dividing the intensity by that of the thalamus. We used 5% as a threshold to determine the significance of the statistical test.

Results:

In the pre-contrast scan, the SIR of the PVS in WM (Mean ± standard deviation, 1.83 ± 0.46) was significantly higher than that of the PVS in the BG (1.05 ± 0.154), CSF_Syl (1.03 ± 0.15) and the CSF_AC (0.97 ± 0.29). There was no significant difference between the SIR of the PVS in the BG compared to the CSF_AC and CSF_Syl. For the evaluation of the contrast enhancement effect, significant enhancement was observed in the PVS in the BG, the CSF_AC and the CSF_Syl compared to the pre-contrast scan. No significant contrast enhancement was observed in the PVS in WM.

Conclusion:

The signal intensity difference between the PVS in the BG versus WM on pre-contrast images suggests that the fluid composition might be different between these PVSs. The difference in the contrast enhancement between the PVSs in the BG versus WM suggests a difference in drainage function.

Perivascular Spaces in Old Age: Assessment, Distribution, and Correlation with White Matter Hyperintensities

BACKGROUND AND PURPOSE

The visual rating scales for perivascular spaces vary considerably. We sought to develop a new scale for visual assessment of perivascular spaces and to further describe their distribution and association with white matter hyperintensities in old age.

MATERIALS AND METHODS

This population-based study included 530 individuals who did not have dementia and were not institutionalized (age, ≥60 years or older; mean age, 70.7 years; 58.9% women) who were living in central Stockholm, Sweden. A semiquantitative visual rating scale was developed to score the number and size of visible perivascular spaces in 7 brain regions in each hemisphere. A modified Scheltens visual rating scale was used to assess white matter hyperintensities.

RESULTS

The global scores for perivascular spaces ranged from 4-32 for number, 3-22 for size, and 7-54 for the combination of number and size. The weighted κ statistics for the intra- and interrater reliability both were 0.77. The global score for the number of perivascular spaces increased with advancing age (P < .001). The scores for the number of perivascular spaces in the basal ganglia and subinsular regions were significantly correlated with the load of white matter hyperintensities, especially in lobar and deep white matter regions (partial correlation coefficients, >0.223; P < .01).

CONCLUSIONS

The new visual rating scale for perivascular spaces shows excellent intra- and interrater reliability. The number of perivascular spaces globally and, especially, in the basal ganglia, is correlated with the load of lobar and deep white matter hyperintensities, supporting the view that perivascular spaces are a marker for cerebral small-vessel disease.

Quantification of perivascular spaces at 7T: A potential MRI biomarker for epilepsy

PURPOSE

7T (7T) magnetic resonance imaging (MRI) facilitates the visualization of the brain with resolution and contrast beyond what is available at conventional clinical field strengths, enabling improved detection and quantification of small structural features such as perivascular spaces (PVSs). The distribution of PVSs, detected in vivo at 7T, may act as a biomarker for the effects of epilepsy. In this work, we systematically quantify the PVSs in the brains of epilepsy patients and compare them to healthy controls.

METHODS

T₂-weighted turbo spin echo images were obtained at 7T on 21 epilepsy patients and 17 healthy controls. For all subjects, PVSs were manually marked on Osirix image analysis software. Marked PVSs with diameter≥0.5mm were then mapped by hemisphere and lobe. The asymmetry index (AI) was calculated for each region and the maximum asymmetry index (|AI_max|) was reported for each subject. The asymmetry in epilepsy subjects was compared to that of controls, and the region with highest asymmetry was compared to the suspected seizure onset zone.

RESULTS

There was a significant difference between the |AI_max| in epilepsy subjects and in controls (p=0.016). In 72% of patients, the region or lobe of the brain showing maximum PVS asymmetry was the same as the region containing the suspected seizure onset zone.

CONCLUSION

These findings suggest that epilepsy may be associated with significantly asymmetric distribution of PVSs in the brain. Furthermore, the region of maximal asymmetry of the PVSs may help provide localization or confirmation of the seizure onset zone.

Enlarged Virchow-Robin Spaces in A Young Man: A Constrained Spherical Deconvolution Tractography Study

BACKGROUND AND AIM

Virchow-Robin spaces are mainly located along the path of the lenticulo-striate arteries in the basal ganglia through the anterior perforate substance, and can be found both in normal subjects, as a rare phenomenon, and in patients with different diseases. We report a case of a healthy young man with unilateral enlarged Virchow-Robin spaces in the left capsule-lenticulostriate area. Aim of this case report is to show the potential of probabilistic Constrained Spherical Deconvolution (CSD) tractography in showing abnormal diffusion tensor imaging and tractography of the anterior thalamic tracts caused by mass effect from adjacent enlarged Virchow-Robin spaces.

METHODS

The study was performed with a 3T magnetic resonance imaging (MRI) scanner (Achieva, Philips Healthcare, Best, Netherlands); equipped with a 32-channel SENSE head coil. Diffusion Weighted Images were analyzed by using CSD, a fast computation method that overcomes major limitations of Diffusion Tensor Imaging allowing reliable estimation of one or more fiber orientations in the presence of intravoxel orientational heterogeneity.

RESULTS

Tractography showed increased Fractional Anisotropy and reduced Apparent Diffusion Coefficient values, a displacement and compression of the anterior thalamic projections by part of the enlarged VRS, and a decrease of white matter fibers in the left side in comparison to the right one.

CONCLUSIONS

We report on a case of a healthy individual with unilateral dilated VRS in the capsulo-lenticulostriatal area, proving the utility of diffusion MRI and tractography in understanding the abnormal neuroanatomy of this particular condition.

Linear sign in cystic brain lesions ≥5 mm: A suggestive feature of perivascular space

OBJECTIVE

To determine the prevalence of a linear sign within enlarged perivascular space (EPVS) and chronic lacunar infarction (CLI) ≥ 5 mm on T2-weighted imaging (T2WI) and time-of-flight (TOF) magnetic resonance angiography (MRA), and to evaluate the diagnostic value of the linear signs for EPVS over CLI.

METHODS

This study included 101 patients with cystic lesions ≥ 5 mm on brain MRI including TOF MRA. After classification of cystic lesions into EPVS or CLI, two readers assessed linear signs on T2WI and TOF MRA. We compared the prevalence and the diagnostic performance of linear signs.

RESULTS

Among 46 EPVS and 51 CLI, 84 lesions (86.6%) were in basal ganglia. The prevalence of T2 and TOF linear signs was significantly higher in the EPVS than in the CLI (P < .001). For the diagnosis of EPVS, T2 and TOF linear signs showed high sensitivity (> 80%). TOF linear sign showed significantly higher specificity (100%) and accuracy (92.8% and 90.7%) than T2 linear sign (P < .001).

CONCLUSIONS

T2 and TOF linear signs were more frequently observed in EPVS than CLI. They showed high sensitivity in differentiation of them, especially for basal ganglia. TOF sign showed higher specificity and accuracy than T2 sign.

KEY POINTS

• Linear sign is a suggestive feature of EPVS. • Time-of-flight magnetic resonance angiography can reveal the lenticulostriate artery within perivascular spaces. • Linear sign helps differentiation of EPVS and CLI, especially in basal ganglia.

Mild Developmental Foreign Accent Syndrome and Psychiatric Comorbidity: Altered White Matter Integrity in Speech and Emotion Regulation Networks

Foreign accent syndrome (FAS) is a speech disorder that is defined by the emergence of a peculiar manner of articulation and intonation which is perceived as foreign. In most cases of acquired FAS (AFAS) the new accent is secondary to small focal lesions involving components of the bilaterally distributed neural network for speech production. In the past few years FAS has also been described in different psychiatric conditions (conversion disorder, bipolar disorder, and schizophrenia) as well as in developmental disorders (specific language impairment, apraxia of speech). In the present study, two adult males, one with atypical phonetic production and the other one with cluttering, reported having developmental FAS (DFAS) since their adolescence. Perceptual analysis by naïve judges could not confirm the presence of foreign accent, possibly due to the mildness of the speech disorder. However, detailed linguistic analysis provided evidence of prosodic and segmental errors previously reported in AFAS cases. Cognitive testing showed reduced communication in activities of daily living and mild deficits related to psychiatric disorders. Psychiatric evaluation revealed long-lasting internalizing disorders (neuroticism, anxiety, obsessive-compulsive disorder, social phobia, depression, alexithymia, hopelessness, and apathy) in both subjects. Diffusion tensor imaging (DTI) data from each subject with DFAS were compared with data from a group of 21 age- and gender-matched healthy control subjects. Diffusion parameters (MD, AD, and RD) in predefined regions of interest showed changes of white matter microstructure in regions previously related with AFAS and psychiatric disorders. In conclusion, the present findings militate against the possibility that these two subjects have FAS of psychogenic origin. Rather, our findings provide evidence that mild DFAS occurring in the context of subtle, yet persistent, developmental speech disorders may be associated with structural brain anomalies. We suggest that the simultaneous involvement of speech and emotion regulation networks might result from disrupted neural organization during development, or compensatory or maladaptive plasticity. Future studies are required to examine whether the interplay between biological trait-like diathesis (shyness, neuroticism) and the stressful experience of living with mild DFAS lead to the development of internalizing psychiatric disorders.

Dilatation of Virchow-Robin spaces in children hospitalized at pediatric neurology department

BACKGROUND AND PURPOSE

Dilated Virchow-Robin spaces (dVRs) have been revealed by magnetic resonance imaging (MRI) in patients with various neurological disorders. However, their etiology and clinical importance have not been discovered yet. The aim of the study was to estimate dVRs occurrence in hospitalized children and determine dVRs localization and their association with different nervous system diseases.

MATERIAL AND METHODS

Contrast-enhanced brain MRI examinations with the use of 1.5T GE device were performed in children with different diseases of nervous system, who were hospitalized at Pediatric Neurology Department, Chair of Children and Adolescent Neurology, Jagiellonian University in the years 2010-2011. The mean age of examined children was 11.58 years, and the studied group included 27 boys and 26 girls.

RESULTS

Within two years, MRI examinations of the brain were performed in 1348 children and dVRs were found in 53 of them (3.93%). Among children with dVRs, 15 were diagnosed with headache (28.3%) and 18 with epilepsy (33.96%). Other diagnoses were less frequent and occurred in 37.7%. Generalized dVRs and those localized in the subcortical nuclei were most frequently found.

CONCLUSIONS

Higher incidence of dVRs was found in children with headache and epilepsy. No association was found between localization of dVRs and symptomatology of different nervous system diseases except for large dVRs probably due to the pressure on the surrounding tissues.

Towards the automatic computational assessment of enlarged perivascular spaces on brain magnetic resonance images: a systematic review

Enlarged perivascular spaces (EPVS), visible in brain MRI, are an important marker of small vessel disease and neuroinflammation. We systematically evaluated the literature up to June 2012 on possible methods for their computational assessment and analyzed confounds with lacunes and small white matter hyperintensities. We found six studies that assessed/identified EPVS computationally by seven different methods, and four studies that described techniques to automatically segment similar structures and are potentially suitable for EPVS segmentation. T2-weighted MRI was the only sequence that identified all EPVS, but FLAIR and T1-weighted images were useful in their differentiation. Inconsistency within the literature regarding their diameter and terminology, and overlap in shape, intensity, location, and size with lacunes, conspires against their differentiation and the accuracy and reproducibility of any computational segmentation technique. The most promising approach will need to combine various MR sequences and consider all these features for accurate EPVS determination.

Delineation of the safe zone in surgery of sylvian insular triangle: morphometric analysis and magnetic resonance imaging study

BACKGROUND

Surgery within the insula carries significant risk of morbidity, particularly hemiparesis, because of the difficulty in detecting the internal capsule boundaries.

OBJECTIVE

We analyzed the anatomy of the insula and identified landmarks anticipated to facilitate surgery for intrinsic insular lesions.

METHODS

Insular region anatomy was studied in 11 cadaveric brains harvested within 72 hours postmortem. MRI of the specimens was acquired using 3.0 T with T2-weighting and 25 directions of diffusion tensor imaging. Landmarks easily recognizable during surgery were identified on the surface of the insula. The interrelationships between surface landmarks and critical structures were analyzed.

RESULTS

The posterior inferior insular point (PIIP) and the upper central insular point (UCIP) were newly established as landmarks on the insula. The PIIP corresponded to the obvious bend in the posterior long insular gyrus. The UCIP is the meeting point between the central insular sulcus and superior peri-insular sulcus. The corticospinal tract was identified as a high-intensity area in the posterior limb of the internal capsule on T2-weighted imaging and its course confirmed with diffusion tensor imaging tractography. The corticospinal tract took a course deep to the posterosuperior insula on T2-weighted imaging, 4.8 mm from the UCIP and 6.2 mm from the PIIP.

CONCLUSION

The posterosuperior part of the insula forms the region at greatest risk to corticospinal tract injury. The PIIP and UCIP are crucial to understanding the relationship of the insula with the posterior limb of the internal capsule including the corticospinal tract.

Giant tumefactive perivascular spaces that expanded and became symptomatic 14 years after initial surgery

BACKGROUND

Perivascular spaces (PVSs) or Virchow-Robin spaces in the brain are pial-lined interstitial fluid (ISF)-filled structures surrounding the penetrating arteries and arterioles. These spaces appear as 1- to 2-mm in diameter, round, oval, or curvilinear smooth-walled structures on magnetic resonance imaging (MRI). Typical PVSs are asymptomatic. Occasionally, they become enlarged and cause specific clinical manifestations that depend on location and the degree of tissue compression. In this case, they are referred to as giant tumefactive PVSs. To our knowledge, there have been no reported cases in which giant PVSs increased remarkably in number and size during both the natural course and postoperative course. We describe a rare progression of giant tumefactive PVSs 14 years after initial surgery.

CASE DESCRIPTION

On first admission at age 17, endoscopic ventriculocystostomy and third ventriculostomy were performed to relieve hydrocephalus caused by cysts compressing the cerebral aqueduct. Fourteen years later, the multicystic lesion reappeared with an increase in both cyst number and size. The patient showed no hydrocephalus but presented with oculomotor and trochlear nerve palsies, which were caused by a mass effect on the midbrain. Endoscopic ventriculocystostomy was performed and symptoms improved.

CONCLUSION

This is the first case report in which giant PVSs increased significantly in number and size.

Virchow-Robin Spaces in Health and Disease

Virchow-Robin spaces are pial-lined, interstitial fluid-filled structures that do not directly communicate with the subarachnoid space, and accompany penetrating arteries and veins. They are common, incidental, “leave me alone” lesions that should not be mistaken for more ominous disease. They are frequently seen in the supratentorial white matter, basal ganglia region, around the anterior commissure, and surrounding penetrating lenticulostriate arteries, thalamus, midbrain, cerebellum, insular cortex, corpus callosum, cingulate gyrus, extreme capsule, along the optical tracts, and in the hippocampus. Most are small, well-defined fluid-filled cysts less than five mm in diameter, and are isointense to CSF on all pulse sequences. They are often mistaken for lacunar infarcts, cystic neoplasms or infectious cysts. We retrospectively analyzed various appearances of VRS as seen on magnetic resonance imaging of brain in 100 cases, in an attempt to provide a better understanding of these lesions and their significance in various physiological and pathological conditions.

Spread of infection to Virchow-Robin spaces in a patient with Streptococcus pneumoniae meningitis

We present a case of a child with acute bacterial leptomeningeal infection caused by Streptococcus pneumoniae. There was an extension of infection along multiple Virchow-Robin spaces into the brain parenchyma, resulting in multiple microabscesses. These abscesses showed restricted diffusion on the diffusion-weighted images on the initial magnetic resonance imaging. A follow-up magnetic resonance imaging showed evolution of these microabscesses with contrast enhancement that ultimately resolved with antibiotics.

Perivascular space and neurological disorders

Perivascular space (PVS) is a crevice between two slices of cerebral pia maters, filled with tissue fluid, which be formed by pia mater emboling in the surrounding of cerebral perforating branch (excluding micrangium). Normal PVS (diameter < 2 mm) can be found in almost all healthy adults; however enlarged PVS (diameter > 2 mm) has correlation with neurological disorders probably. The article reviews the formation mechanism, imageology characteristics and the relation with neurological disorders of PVS, which is beneficial to the research of some neurological disorders etiopathogenesis and treatment.

Enhancement of Virchow-Robin Spaces

Virchow-Robin spaces are enclosed spaces filled with interstitial fluid and covered with pia that accompany arteries, arterioles, veins and venules as they perforate the brain. They are round, linear or punctuate areas depending on the image that parallel cerebrospinal fluid attenuation or signal intensity. They are classically described as isointense to cerebrospinal fluid on images obtained with all pulse sequences. They appear hypointense relative to brain on T1-weighted MR scans and present a high signal intensity on T2-weighted MR scans. They also show complete signal suppression on fluid-attenuated inversion recovery (FLAIR) scans and no enhancement after intravenous contrast administration. However, many pathologic states result in abnormal dilation with an increased number of Virchow-Robin spaces visible on MRI imaging and many pathological conditions cause the spaces to enhance. The purpose of this study is to present the major causes of Virchow-Robin enhancement.

Potential surrogate markers of cerebral microvascular angiopathy in asymptomatic subjects at risk of stroke

Cerebral microvascular angiopathy (MVA) is associated with clinical vascular risk factors and is characterised by histological changes, including thickening of the walls of arterial vessels and dilatation of the Virchow-Robin spaces (VRS). We have previously described two novel biomarkers of MVA based on magnetic resonance imaging (MRI), VRS dilatation and abnormalities in the transfer of systolic arterial pulsation to the ventricular CSF, which occur as a result of decreased cerebral arterial compliance. These are associated with vascular dementia and treatment-resistant late onset depression. We studied a group of normal subjects at risk of cerebrovascular disease to determine if these biomarkers are present in patients who have no evidence of symptomatic vascular disease. We studied 31 subjects, 16 with three or more vascular risk factors and 15 with one or less significant risk factors. We measured arterial blood flow and CSF flow in the cerebral aqueduct, white matter lesion load, and the distribution and number of VRS. There were significant differences in CSF pulsatility and in VRS in the basal ganglia between the two groups, but no differences in white matter lesion load. We conclude that asymptomatic subjects at risk of stroke have MRI evidence of MVA before white matter lesions become apparent.

Enhancement of robin-virchow spaces MRI evaluation

The perivascular spaces are normally microscopic. Even in normal brain some Robin-Virchow spaces are usually seen in the area of substantia innominata at the level of anterior commissure. Many pathologic states result in abnormal dilatation with an increased number of spaces visible on MRI imaging. Dilatation is most commonly associated with anterior abnormalities that arise due to aging, diabetes, hypercholesterolemia, smoking, hypertension and other vascular risk factors. The precise etiology of dilatation is currently unknown.

Biomarkers of cerebrovascular disease in dementia

There is increasing recognition that cerebrovascular disease contributes significantly to the development and progression of patients with dementia. The concepts of pure vascular and pure degenerative dementia have been replaced with a recognition that, in many patients, there is a spectrum of neurodegenerative and vascular processes. This is supported by preliminary studies showing response to vascular therapeutics and ventriculo-peritoneal shunting in patients with Alzheimer's disease. This article examines the imaging biomarkers that are available for the characterization of microvascular abnormality in the ageing brain, with particular reference to microvascular angiopathy, cerebral embolic disease, orthostatic hypotension and abnormalities of Monro-Kellie homeostasis.

Giant tumefactive perivascular spaces

We describe the imaging characteristics of giant tumefactive perivascular spaces in a 37-year-old man who initially presented at the age of twenty years with vision change and headache and was found to have probable low grade neoplasm. The patient was followed subsequently at 8 years and 17 years later at our institution with stable imaging and neurologic exam. Magnetic resonance imaging demonstrated multiple cystic mass in the right frontal lobe which was stable in size and appearance. The mass followed signal intensity identical to cerebrospinal fluid on all sequences and was consistent with a giant tumefactive perivascular space. This report illustrates the need to keep this entity in mind when imaging evaluation demonstrates a lesion isointense to cerebrospinal fluid on all sequences. These lesions can actually be quite large and ominous appearing and many proceed to biopsy unnecessarily.

Virchow-Robin spaces relate to cerebral small vessel disease severity

BACKGROUND AND PURPOSE

Virchow-Robin spaces (VRs) are perivascular spaces surrounding the deep perforating brain arteries. VRs dilatation is pathologic, and it could be a manifestation of cerebral small vessel disease. In the present study we assessed the relation between VRs and silent ischemic lesions in a cohort of patients with cerebral small vessel disease.

METHODS

We divided dilated VRs on MRI (1.5 Tesla) into three semi-quantitative categories in 165 first ever lacunar stroke patients. We counted asymptomatic lacunar infarcts and graded white matter lesions, and compared the prevalence of vascular risk factors in different categories of VRs. We also determined independent predictors of silent ischemic lesions.

RESULTS

VRs at basal ganglia level related to age, hypertension, asymptomatic lacunar infarcts, and white matter lesions. VRs at basal ganglia level predicted silent ischemic lesions (odds ratio 10.58 per higher VRs category; 95 %- confidence interval 3.40 - 32.92).

CONCLUSION

Dilated VRs in the basal ganglia relate to the severity of cerebral small vessel disease and might be a manifestation of the same small vessel abnormality that causes silent ischemic lesions. This adds a role for VRs as a potential marker for small vessel disease.

Correlation among subcortical white matter lesions, intelligence and CTG repeat expansion in classic myotonic dystrophy type 1

OBJECTIVES

To analyze the correlation among intelligence, brain magnetic resonance images (MRI) and genotype in classic myotonic dystrophy type 1 (DM1) patients.

MATERIALS AND METHODS

Seventeen patients with classic DM1 were administered intelligence and neuropsychological tests and brain MRI focusing on a semi-quantitative rating scale of subcortical white matter lesions (WMLs). Statistical analysis was measured to evaluate the correlation among clinical manifestations, intelligence, brain MRI abnormalities, and CTG repeat expansion.

RESULTS

There were statistically significant correlations between intelligence test and insular WMLs for all DM1 patients and between intelligence quotient and temporal WMLs for those patients with less than 400 of the CTG repeat size. We also documented that temporal WMLs were related to the disease course, and frontal WMLs were correlated with aging in all DM1 patients. However, a poor correlation was found among CTG repeat size and clinical pictures, neuropsychological impairments, and brain MRI abnormalities in all DM1 patients.

CONCLUSION

These results suggest that subcortical WMLs are correlated with focal dementia in classic DM1 patients. Temporal and insular WMLs may be responsible for the global intellectual dysfunction of adult DM1 patients.

Giant cystic widening of Virchow-Robin spaces: an anatomofunctional study

We describe 2 patients with unusual white matter cystic dilations, which could correspond to widening of the perivascular spaces. They underwent morphologic MR imaging with tractography, functional MR imaging (fMRI), and neuropsychological evaluation. fMRI examination showed no functional reorganization of cortical areas. Tractography showed an apparent decrease of white matter tract vectors into the regions of concern. Findings of the neuropsychological examination were normal. It seems that even an extensive cystic dilation of white matter does not deteriorate brain function.

[Dilatation of Virchow-Robin perivascular spaces (types III cerebral lacunae): radio-clinical correlations]

BACKGROUND AND PURPOSE

Virchow-Robin spaces are pia-lined extensions of the subarachnoid space surrounding the path of brain vessels. When enlarged, such dilated perivascular spaces are often seen as foci of cerebrospinal fluid signal on MRI or CT scan. These foci are found in patients with miscellaneous clinical status. It is necessary to determine the radiological significance and clinical associations, if any, in such patients in order to give them the appropriate treatment.

METHODS

We describe the clinical and radiological findings of five patients and review the literature on perivascular Virchow-Robin spaces.

RESULTS

The mechanisms of dilated Virchow-Robin spaces are still not well understood. Such dilated perivascular spaces are found in two locations: typically in the high-convexity white matter of healthy elderly subjects, or surrounding the lenticulostriate vessels as they enter the basal ganglia. On MR images, they may be confused with lacunar infarcts. Most of the patients present with no symptoms: small dilatations located in the high convexity actually represent an anatomic variant, also called "état criblé". Sometimes, giant dilatations, or Poirier's type IIIb "expanding lacunae", found in the basal ganglia and midbrain may result in symptomatic hydrocephalus needing appropriate treatment. For other miscellaneous symptoms as headache, generalized epilepsy, dysmorphy, macrocephaly, there is no reliable correlation with enlarged perivascular spaces seen on MR images.

CONCLUSIONS

The real symptomatic dilated perivascular spaces need appropriate and quick treatment. Most of the other patients present with no symptoms and will remain asymptomatic.

Virchow-Robin spaces at MR imaging

Virchow-Robin (VR) spaces surround the walls of vessels as they course from the subarachnoid space through the brain parenchyma. Small VR spaces appear in all age groups. With advancing age, VR spaces are found with increasing frequency and larger apparent sizes. At visual analysis, the signal intensity of VR spaces is identical to that of cerebrospinal fluid with all magnetic resonance imaging sequences. Dilated VR spaces typically occur in three characteristic locations: Type I VR spaces appear along the lenticulostriate arteries entering the basal ganglia through the anterior perforated substance. Type II VR spaces are found along the paths of the perforating medullary arteries as they enter the cortical gray matter over the high convexities and extend into the white matter. Type III VR spaces appear in the midbrain. Occasionally, VR spaces have an atypical appearance. They may become very large, predominantly involve one hemisphere, assume bizarre configurations, and even cause mass effect. Knowledge of the signal intensity characteristics and locations of VR spaces helps differentiate them from various pathologic conditions, including lacunar infarctions, cystic periventricular leukomalacia, multiple sclerosis, cryptococcosis, mucopolysaccharidoses, cystic neoplasms, neurocysticercosis, arachnoid cysts, and neuroepithelial cysts.

Subinsular vascular lesions: an analysis of 119 consecutive autopsied brains

The insula of Reil constitutes a functionally intriguing complex of the brain related to multifunctional activities. We examined the subinsular region in 119 consecutively autopsied patients, as T2 hyperintense lesions are frequently observed in magnetic resonance diagnosis of this region. The patients were admitted in neurology wards and were diagnosed as having cerebrovascular disease in 55 patients (46%), other neurological diseases in 57 patients (48%) and non-neurological diseases in seven patients (6%). Demyelination of the white matter was semi-quantified as a fiber density score (percent stained area/total area) with computer-assisted image analysis on Klüver-Barrera-stained sections. Astrogliosis was assessed by immunohistochemistry for glial fibrillary acidic protein. The lesion analysis showed a dilated perivascular space in 29 patients (24%), demyelination (fiber density score less than the mean - 1 SD) in 27 patients (23%), slit-shaped lesion in six patients (5%), lacunar infarction in one patient (1%) and cerebral hemorrhage in one patient (1%). A histologic-radiologic comparison in two patients with subcortical ischemic vascular dementia showed correspondence between subinsular hyperintensities, and demyelination, gliosis and a dilated perivascular space. These results indicate that subinsular lesions rarely signifies focal vascular lesions, and are consisted of demyelination, gliosis and a dilated perivascular space.

Neuroradiological findings in vascular dementia

INTRODUCTION

There are multiple diagnostic criteria for vascular dementia (VaD) that may define different populations. Utilizing the criteria of the National Institute of Neurological Disorders and Stroke and Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) has provided improved consistency in the diagnosis of VaD. The criteria include a table listing brain imaging lesions associated with VaD.

METHODS

The different neuroradiological aspects of the criteria are reviewed based on the imaging data from an ongoing large-scale clinical trial testing a new treatment for VaD. The NINDS-AIREN criteria were applied by a centralized imaging rater to determine eligibility for enrollment in 1,202 patients using brain CT or MRI.

RESULTS

Based on the above data set, the neuroradiological features that are associated with VaD and that can result from cerebral small-vessel disease with extensive leukoencephalopathy or lacunae (basal ganglia or frontal white matter), or may be the consequence of single strategically located infarcts or multiple infarcts in large-vessel territories, are illustrated. These features may also be the consequence of global cerebral hypoperfusion, intracerebral hemorrhage, or other mechanisms such as genetically determined arteriopathies.

CONCLUSION

Neuroimaging confirmation of cerebrovascular disease in VaD provides information about the topography and severity of vascular lesions. Neuroimaging may also assist with the differential diagnosis of dementia associated with normal pressure hydrocephalus, chronic subdural hematoma, arteriovenous malformation or tumoral diseases.

Virchow-Robin spaces on magnetic resonance images: normative data, their dilatation, and a review of the literature

INTRODUCTION

Virchow-Robin spaces (VRS) are perivascular spaces in the brain and can be visualized on magnetic resonance images (MRI). We attempt to provide a better understanding of the significance of VRS for pathological and physiological processes by reviewing the literature, presenting normative data for the first time, and proposing a definition for the dilatation of the VRS on MRI that is based on shape rather than size.

METHODS

We evaluated the VRS in 125 healthy subjects (age range 1-30 years) using high-resolution 3D images, and in 36 patients (age range 2-16 years) with normal MRI, using routine clinical sequences.

RESULTS

VRS were visible in all high-resolution images of the 125 healthy subjects. Two of them revealed dilated VRS, giving a prevalence of 1.6%. VRS could be visualized in 29 (80%) of the 36 paediatric clinical scans; none was dilated. It was demonstrated that the visibility of VRS on MRI is sequence-dependent.

CONCLUSION

From the results of this study and the literature on the nature and pathology of VRS, we conclude that VRS on MR images of healthy individuals are normal findings, even if they are dilated. A judgement on whether dilated VRS in an individual patient is a normal variant or part of a disease process can be made by taking into account the appearance of the adjacent tissue on MRI and the clinical context.

MR Imaging of Epilepsy: Strategies for Successful Interpretation

MR imaging plays a pivotal role in the evaluation of patients with epilepsy. With its high spatial resolution, excellent inherent soft tissue contrast, multiplanar imaging capability, and lack of ionizing radiation, MR imaging has emerged as a versatile diagnostic tool in the evaluation of patients with epilepsy. MR imaging not only identifies specific epileptogenic substrates but also determines specific treatment and predicts prognosis. Employing appropriate imaging protocols and reviewing the images in a systematic manner helps in the identification of subtle epileptogenic structural abnormalities. With future improvements in software, hardware, and post-processing methods, MR imaging should be able to throw more light on epileptogenesis and help physicians to better understand its structural basis.

Dilation of Virchow-Robin spaces in CADASIL

To precise the severity of dilated Virchow-Robin spaces (VRS) in CADASIL patients and to determine their correlation with clinical presentation and other abnormalities on cerebral Magnetic Resonance Imaging (MRI). Dilated VRS were previously associated with aging, hypertension, dementia, epilepsy or migraine. We already reported increased frequency of enlarged VRS in CADASIL patients when compared with family members without the affected haplotype. We analysed clinical and MRI data from 50 CADASIL patients collected prospectively in our center. The presence of dilated VRS was assessed in the subcortical white matter of temporal lobes, the centrum semi-ovale and the basal ganglia. Their severity in each region was evaluated according to the scale proposed by Heier. We compared the clinical data, the severity of white matter abnormalities and the presence of microbleeds in patients with and without dilated VRS. Seventy-eight percent of patients in our series had dilated VRS, mostly located in the lentiform nuclei (94%) and subcortical white matter of the temporal lobes (66%). The severity of these lesions was variable but not correlated neither to the extent of white matter abnormalities nor to the clinical presentation in our patients. Only the age was found to be related to the extent of dilated VRS. Dilated VRS are frequent in CADASIL and mostly located in the temporal white matter and basal ganglia. The dilation of perivascular spaces does not seem to be directly related to the occurrence of ischemic or hemorrhagic lesions in CADASIL. In contrast, the relation with age suggests that either aging, progression of vascular wall alterations during the course of the disease, or both of these processes can favour the extension of VRS in CADASIL.

Age-related cerebral white matter changes and pulse-wave encephalopathy: observations with three-dimensional MRI

Our purpose was to investigate leukoaraïosis (LA) using three-dimensional MR imaging combined with advanced image-processing technology to attempt to group signal abnormalities according to their etiology. Coronal T2-weighted fast fluid-attenuated inversion-recovery (FLAIR) sequences and three-dimensional T1-weighted fast spoiled gradient recalled echo sequences were used to examine cerebral white matter changes in 75 elderly people with memory complaint but no dementia. They were otherwise healthy, community-dwelling subjects. Three subtypes of LA were defined on the basis of their shape, geography and extent: the so-called subependymal/subpial LA, perivascular LA and "bands" along long white matter tracts. Subependymal changes were directly contiguous with ventricular spaces. They showed features of "water hammer" lesions with ventricular systematisation and a more frequent location around the frontal horns than around the bodies (P=.0008). The use of cerebrospinal fluid (CSF) contiguity criterion allowed a classification of splenial changes in the subpial group. Conversely, posterior periventricular lesions in the centrum ovale as well as irregular and extensive periventricular lesions were not directly contiguous with CSF spaces. The so-called perivascular changes showed features of small-vessel-associated disease; they surrounded linear CSF-like signals that followed the direction of perforating vessels. Distribution of these perivascular changes appeared heterogeneous (P ranging from .04 to 5.10(-16)). These findings suggest that subependymal/subpial LA and subcortical LA may be separate manifestations of a single underlying pulse-wave encephalopathy.

Infarcts in the posterior circulation territory in migraine. The population-based MRI CAMERA study

In a previous study, migraine cases from the general population were found to be at significantly increased risk of silent infarct-like lesions in the posterior circulation (PC) territory of the brain, notably in the cerebellum. In this study we describe the clinical and neuroimaging characteristics of migraine cases with and without aura and controls with PC lesions. In total, 39 PC infarct-like lesions represented the majority (65%) of all 60 identified brain infarct-like lesions in the study sample (n = 435 subjects with and without migraine). Most lesions (n = 33) were located in the cerebellum, often multiple, and were round or oval-shaped, with a mean size of 7 mm. The majority (88%) of infratentorial infarct-like lesions had a vascular border zone location in the cerebellum. Prevalence of these border zone lesions differed between controls (0.7%), cases with migraine without aura (2.2%) and cases with migraine with aura (7.5%). Besides higher age, cardiovascular risk factors were not more prevalent in cases with migraine with PC lesions. Presence of these lesions was not associated with supratentorial brain changes, such as white matter lesions. The combination of vascular distribution, deep border zone location, shape, size and imaging characteristics on MRI makes it likely that the lesions have an infarct origin. Previous investigators attributed cases of similar 'very small' cerebellar infarcts in non-migraine patients to a number of different infarct mechanisms. The relevance and likelihood of the aetiological options are placed in the context of known migraine pathophysiology. In addition, the specific involvement of the cerebellum in migraine is discussed. The results suggest that a combination of (possibly migraine attack-related) hypoperfusion and embolism is the likeliest mechanism for PC infarction in migraine, and not atherosclerosis or small-vessel disease.

MR imaging of epilepsy: strategies for successful interpretation

MR imaging plays a pivotal role in the evaluation of patients with epilepsy. With its high spatial resolution, excellent inherent soft tissue contrast,multiplanar imaging capability, and lack of ionizing radiation, MR imaging has emerged as a versatile diagnostic tool in the evaluation of patients with epilepsy. MR imaging not only identifies specific epileptogenic substrates but also determines specific treatment and predicts prognosis. Employing appropriate imaging protocols and reviewing the images ina systematic manner helps in the identification of subtle epileptogenic structural abnormalities. With future improvements in software, hardware, and post-processing methods, MR imaging should be able to throw more light on epileptogenesis and help physicians to better understand its structural basis.

Surgical considerations regarding giant dilations of the perivascular spaces

Object. Dilations of brain perivascular spaces (PVSs), also known as Virchow—Robin spaces, are routinely identified on magnetic resonance imaging studies of the brain and recognized as benign normal variants. Giant dilations occur only rarely and can be easily misdiagnosed as central nervous system tumors. The relevant surgical literature was reviewed to help establish indications for surgical intervention in these typically benign lesions.

Methods. Giant dilations of the PVSs in 12 patients who had undergone surgery for several different indications were identified. Both clinical and radiographic presentations of these patients were reviewed along with the surgical procedures.

Conclusions. Dilations of the PVSs can become giant lesions that may necessitate surgical intervention to relieve mass effect or hydrocephalus. The relationship of these lesions to neurological symptoms such as tremor and seizures remains unclear.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: MR imaging findings at different ages--3rd-6th decades

PURPOSE

To depict various brain lesions that have been described in patients who have cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with prospective standardized magnetic resonance (MR) imaging in patients of different age groups.

MATERIALS AND METHODS

Forty patients with CADASIL in different age groups (20-30 years, n = 5; 31-40 years, n = 4; 41-50 years, n = 16; 51-60 years, n = 15) underwent transverse MR imaging with T1-weighted dual fast spin-echo, fluid-attenuated inversion-recovery, and T2*-weighted gradient-echo sequences. Images were analyzed by one neuroradiologist for the presence of areas of hyperintensity, lacunar infarcts, microbleeds, and subcortical lacunar lesions (SLLs) in different anatomic locations. Descriptive statistics were obtained for the presence of MR imaging abnormalities in various brain areas and for distribution according to age.

RESULTS

The mean age of the 40 mutation carriers (21 women, 19 men) was 45 years +/- 10 (SD). In patients with CADASIL who were 20-30 years old, characteristic hyperintense lesions in the anterior temporal lobe (100% [five of five]) and SLLs (20% [one of five]) were the only abnormalities seen on MR images. In patients who were 30-40 years old, lacunar infarcts were found in 75% (three of four) of cases. More areas of hyperintensity were noted, and they frequently involved the external capsule, basal ganglia, and brainstem. In patients 41-50 years old, microbleeds were observed in 19% (three of 16). In patients older than 50 years, areas of hyperintensity (100% [15 of 15]), SLLs (73% [11 of 15]), lacunar infarcts (93% [14 of 15]), and microbleeds (47% [seven of 15]) were frequently observed.

CONCLUSION

The four types of brain lesions that are observed in patients with CADASIL were seen in patients of different age groups.