Guide for EPVS rating scale - Brain Research Imaging Centre
Contents
1. More inferiorly in the centrum semiovale EPVS are frequently seen as linear rather than rounded structures Fig 8 Some scales separate EPVS in the centrum semiovale into round oval and linear Rouhl 2008 in this scale only 1 rating is given to EPVS in the centrum semiovale Figure 8 EPVS arrows visualised as linear structures in the centrum semiovale at the level of the bodies of the lateral ventricles V J Wardlaw University of Edinburgh 15 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh c Midbrain EPVS At the junction of the midbrain and pons Fig 9 EPVS may be seen in relation to perforating arteries arising from the short paramedian perforating branches of the basilar artery On standard axial T2MR imaging EPVS in the midbrain normally appear as rounded foci of high signal Normally at least 2 slices should be reviewed when assessing midbrain EPVS Figure 9 A Level of pons B Midbrain at pons midbrain junction the third major site at which EPVS are seen C Slice above pons A magnified view of the midbrain is also shown demonstrating lower midbrain EPVS arrowheads Midbrain lower C Midbrain upper J Wardlaw l J Wardlaw University of University of Edinburgh Inferior Edinburgh Middle ORANET IEVA University of Edinburgh Superior 16 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Ed2. Figure 14 Axial T2 weighted images slices demonstrating varying numbers of EPVS at different levels of centrum semiovale with fewer EPVS visible closer to the vertex right image J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh 23 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh D Double counting of linear EPVS Care should be taken to try to avoid counting linear EPVS twice particularly in the centrum semiovale Fig 15 Review of slices closer to the vertex where EPVS are more often punctuate rather than linear may help in form an initial impression of the closest rating category In all areas review of adjacent slices can help reduce this potential problem Figure 15 Illustration of potential pitfall of double counting EPVS in the centrum semiovale ORANET VO AIEI of Edinburgh gt AL i 24 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh E Poor scan quality including movement In some cases EPVS rating may be made more difficult due to limited scan quality particularly in patients with mild moderate EPVS Fig 16A rather than frequent severe EPVS Fig 16B In such cases an estimate of the closing rating category should be made Figure 16 Limited MRI scan quality due to movement making assessment of small structures more difficult particularly where EPVS are
3. parameters may also contribute to observer differences although this is a parameter which may be difficult to alter in the majority of cases 29 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Section 4 The EPVS scale A Rating categories amp descriptions for each anatomical area Rating Description Basal ganglia and centrum semiovale 0 No EPVS 1 1 10 EPVS mild 2 11 20 EPVS moderate 3 21 40 EPVS frequent 4 gt 40 EPVS severe Midbrain 0 No EVPS visible 1 EPVS visible Notes Review both sides of the brain for EPVS but use the highest number from 1 side only Review all relevant slices but use the slice with the highest number of EPVS In cases where rating is difficult e g due to movement extensive WMH or uncertainty due to variations in EPVS visibility select the closest category In cases of marked asymmetry rare record the score for the side of the brain with more EPVS For basal ganglia EPVS do not include EPVS in the anterior perforated substance see above 30 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh B Imaging examples for rating categories a Basal ganglia Basal ganglia 1 10 EPVS category 1 one example 31 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh B
4. Joanna Wardlaw University of Edinburgh Centrum semiovale gt 40 EPVS category 4 Example 2 of 2 OWA ET CEA University of Edinburgh J Wardlaw University of Edinburgh 45 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh c Midbrain EPVS visible category 1 46 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh References 1 Kwee RM Kwee TC Virchow Robin spaces at MR imaging RadioGraphics 2007 1071 1089 2 Patankar TF Mitra D Varma A Snowden J Neary D Jackson A Dilatation of the Virchow Robin space is a sensitive indicator of cerebral microvascular disease study in elderly patients with dementia Am J Neuroradiol 2005 26 1512 1520 3 Rouhl RPW van Oostenbrugge Ru Knotterus ILH Staals JEA Lodder J Virchow Robin spaces relate to cerebral small vessel disease severity J Neurol 2008 255 692 696 4 Heier LA Bauer CJ Schwartz L Zimmerman RD Morgello S Deck MD Large Virchow Robin spaces MRP clinical correlation Am J Neuroradiol 1989 10 929 936 5 Groeschel S Chong WK Surtees R Hanefeld F Virchow Robin spaces on magnetic resonance images normative data their dilatation and a review of the literature Neuroradiology 2006 48 745 754 6 Di Costanza A Di Salle F Santoro L Bonavita V Tedeschi G Dilated Virchow Robin spaces in myotonic dystrophy frequency extent and signi
5. Morris and Prof Joanna Wardlaw University of Edinburgh Figure 6 A EPVS at the level of the anterior perforated substance thin arrows on the slice immediately above the upper midbrain left image and below the basal ganglia circled right image A J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh Inferior Superior B Magnified view showing EPVS at the level of the anterior perforated substance where the anterior commissure is also seen block arrow pointing to anterior commissure left side b Centrum semiovale EPVS 13 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh EPVS are seen in the centrum semiovale 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 On standard axial T2MR imaging EPVS in the centrum semiovale may have 3 different appearances depending on location scan orientation and perforator vessel orientation Fig 7 Figure 7 Varied configuration of EPVS in the centrum semiovale close to the vertex with a combination of rounded arrowheads short linear block arrow and long linear arrows configurations J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh 14 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh
6. also remain visible despite the presence of extensive WMH Where WMH are non confluent rating may be more straightforward Fig 13 in such cases non affected parenchyma should be used and review of gray matter may also help 20 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Figure 12 Extensive deep WMHs in the centrum semiovale extending to the vertex Appearances closer to the vertex magnified image bottom right image suggest only mild EPVS oD AS A re FE J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Figure 13 Non confluent WMHs J Wardlaw University of Edinburgh ORANET EVAL J Wardlaw University mn of Edinburgh of Edinburgh 22 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh C Varying number of EPVS on different slices The number of EPVS may vary depending on the slice selected For example in some patients fewer EPVS will be visualised in the centrum semiovale at the level of the vertex compared to slices below this Fig 14 After reviewing all relevant slices for the anatomical area being assessed the highest number of EPVS should be recorded
7. mild A rather than frequent B J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh 25 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh F Asymmetry in background brain appearances When background brain parenchyma is asymmetric due to the presence of another lesion e g infarction Fig 17A EPVS should be rated on the other side where possible or an estimate made of the closest category Lacunes fully partially or non cavitated in the basal ganglia may also lead to difficulties in rating Fig 17B again an estimate must be made of the closest category Figure 17 A Asymmetry of background brain parenchyma due to an infarct in the right parieto occipital lobe on T2 weighted MRI arrow B Fully cavitated short arrow partially cavitated thick arrow and probably non cavitated arrowhead lacunar lesions in the basal ganglia on T2 and FLAIR MRI The exact nature of the lesion indicated by the long arrow is less certain this could represent a cavitated lacune or EPVS with surrounding WMH J Wardlaw z J Wardlaw ORAN ETCIEVA University of _ University of University of Edinburgh Edinburgh Edinburgh 26 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh G Asymmetry in EPVS In some patients EPVS may show significant asymmetry Fig 18 In such cases the side with the higher number sho
8. Enlarged perivascular spaces EPVS a visual rating scale and user guide Gillian Potter Zoe Morris amp Joanna Wardlaw Section 1 Introduction Page 3 Section 2 EPVS on brain MRI A Definition Page 4 B Visualisation of EPVS on MRI Page 5 C Location of EPVS Page 8 D Description of EPVS in each anatomical area a Basal ganglia BG Page 9 b Centrum semiovale CS Page 12 c Midbrain Page 14 Section 3 Potential difficulties in EPVS rating Page 15 A Difficulties due to differences in EPVS visibility B Difficulties rating due to white matter hyperintensities C Varying number of EPVS on different slices D Double counting of linear EPVS E Poor scan quality including movement F Asymmetry in background brain appearances G Asymmetry in EPVS H Focally dilated EPVS Differentiating between the most severe categories CS EPVS 1 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh J Variations in lesion load between cohorts Section 4 The EPVS rating scale A Rating categories amp descriptions Page 26 B Imaging examples of rating categories a Basal ganglia Page 27 b Centrum semiovale Page 34 c Midbrain Page 40 References Page 41 Conclusion Page 42 2 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Section 1 Introduction Enlarged perivascular spaces EPVS sometimes called Virchow Robin spaces surro
9. ardlaw University of Edinburgh N 2 EN A 4 gt J Wardlaw University of Edinburgh a A j 7 8 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh C Location of EPVS EPVS are found throughout the brain and are subpial spaces surrounding the perforating arteries arterioles veins and venules of the brain For EPVS rating there are three primary areas to be considered basal ganglia centrum semiovale and midbrain EPVS in these areas have been kept separate in the rating scale as it is possible that they may have different underlying pathophysiology For the basal ganglia this will normally involve reviewing at least 3 slices for the midbrain 1 2 and for the centrum semiovale at least 3 slices Each anatomical area will now be described in more detail 9 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh D Description of EPVS in each anatomical area a Basal ganglia EPVS EPVS are seen in the basal ganglia along the paths of the perforating lenticulostriate arteries arising from the middle cerebral artery which enter the brain parenchyma inferiorly at the anterior perforated substance at the level of the anterior commissure before coursing superiorly through the basal ganglia However EVPS in relation to perforating arteries in the insular cortex should be included in the basal ganglia EPVS r
10. asal ganglia 11 20 EPVS category 2 Example 1 of 2 32 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh OWA ET CEA University of Edinburgh J Wardlaw University of Edinburgh Basal ganglia 11 20 EPVS category 2 33 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Example 2 of 2 ORAM ET CEA University of Edinburgh J Wardlaw University of Edinburgh Basal ganglia 34 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh 20 40 EPVS category 3 Example 1 of 2 ORAM ET CIEE University of Edinburgh 35 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Basal ganglia 20 40 EPVS category 3 ORAVE CEA University of Edinburgh J Wardlaw University of Edinburgh 36 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Basal ganglia gt 40 EPVS category 4 Example 1 of 2 37 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh OWA ET CIE A University of Edinburgh OWA ET CIEE University of Edinburgh Basal ganglia gt 40 EPVS category 4 38 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Example 2 of 2 OWA ET CEA University of E
11. ating Structures to be reviewed in basal ganglia rating are shown in the following diagram 10 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh J Wardlaw University of Edinburgh eo Ven C Caudate nucleus IC Internal capsule T Thalamus L Lentiform nucleus E Externallextreme capsules Ins Insular cortex On standard axial T2MR imaging EPVS in the basal ganglia most commonly appear as rounded foci of high signal Fig 4 In the insular cortex EPVS often appear as short linear structures due to different orientation of vessels Fig 5 Figure 4 Basal ganglia EPVS appearing as multiple rounded sharply delineated foci of T2 high signal arrowheads 11 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh ORRE EVA University of Edinburgh Fa 2 A e t ji A J f J Wardlaw University of Edinburgh A Figure 5 Linear EPVS following the course of perforating arteries in the insular cortex arrows J Wardlaw University of Edinburgh Inferior to the basal ganglia at the level of the anterior perforated substance or substantia innominata most normal people will demonstrate EPVS Fig 6 Rating of EPVS in the basal ganglia should therefore be done above this level EPVS at the level of the anterior commissure should be excluded from the overall rating 12 Guide prepared by Gillian Potter Zoe
12. dinburgh ORAYE CEA University of Edinburgh 39 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh b Centrum semiovale Centrum semiovale 1 10 EPVS category 1 J Wardlaw University of Edinburgh OWA ET CIE a University of Edinburgh 40 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Centrum semiovale 11 20 EPVS category 2 Example 1 of 2 OWA ET CIEE University of Edinburgh X OE to ORANET EWA University of Edinburgh A A Pa y A 41 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Centrum semiovale 11 20 EPVS category 2 Example 2 of 2 J Wardlaw University of Edinburgh OWA ET CIEE f University of Edinburgh i a _ a N A 42 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Centrum semiovale 20 40 EPVS category 3 J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh g J 43 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Centrum semiovale gt 40 EPVS category 4 Example 1 of 2 OWA Ele Ea University of Edinburgh ORAYE IEVA University of Edinburgh J NOR k A 44 Guide prepared by Gillian Potter Zoe Morris and Prof
13. es WMH particularly when confluent and lacunes in the CS and BG regions respectively The user guide was subsequently modified to help avoid residual sources of observer variation This revised EPVS rating scale includes the 3 major anatomical regions where EPVS are found basal ganglia BG centrum semiovale CS and midbrain The development of a validated 3 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh rating scale including a user guide with illustrations will hopefully minimise inter observer variation in studies of EPVS enable cross comparison between research groups and facilitate meta analysis of EPVS studies 4 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Section 2 EPVS on brain MRI A Definition EPVS may be defined on MRI as small sharply delineated structures of cerebrospinal fluid CSF intensity or close to CSF intensity measuring lt 3mm following the course of perforating vessels B Visualisation of EPVS on MRI EPVS are most easily seen on T2 weighted imaging T2W1 and may be distinguished from cavitated lacunes which contain CSF by the latter s large size gt 3mm and shape spheroid Fig 1 these features are often easier to see by reviewing adjacent slices Figure 1 Differentiating true EPVS arrowhead from lacunes containing CSF thin and block arrows in the basal ganglia u
14. ficance Eur Neurol 2001 46 131 139 7 Adachi T Kobayashi S Yamaguchi S Okada K MRI findings of small subcortical lacunar like infarction resulting from large vessel disease J Neurol 2000 247 280 285 8 MacLullich AM Wardlaw JM Ferguson KJ Starr JM Seckl JR Deary IJ Enlarged perivascular spaces are associated with cognitive function in healthy elderly men J Neurol Neurosurg Psychiatry 2004 75 1519 1523 9 Wardlaw JM Ferguson KJ Graham C White matter hyperintensities and rating scales observer reliability varies with lesion load J Neurol 2004 251 584 590 47 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Conclusion Because the clinical implications of EPVS remain to be established there is still an opportunity to improve the reliability of EPVS assessment by the use of the EPVS rating scale so that adequately powered well designed studies will be able to answer the outstanding clinical concerns about their diagnostic and prognostic value within the spectrum of cerebral small vessel disease and whether EPVS should influence patient management Although we have developed and tested a visual rating scale automated EPVS measurement methods may be possible with improved image processing algorithms in future 48 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh
15. inburgh 17 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Section 3 Potential difficulties in EPVS rating A Variations in EPVS visibility With current MRI scanners some EPVS may be seen as faint indistinct high signal structures in the basal ganglia centrum semiovale and midbrain rather than clear very high near CSF signal structures Fig 10 11 A general impression of the region being rated should be used to choose a category using the whole picture and matching as closely as possible with the categories provided Figure 10 Multiple tiny EPVS visualised in the centrum semiovale in a patient with additional movement artefact 18 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Figure 11 Multiple tiny EPVS visualised in the basal ganglia where other EPVS are also seen far more clearly 19 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh B Background WMH Where there are extensive WMHs EPVS may be difficult to rate In such cases an estimate must be made of the closest rating category using the appearance of non involved white matter where visible and cortical gray matter Review of all slices including those at the vertex may be useful where uninvolved white matter and cortical gray matter may be more easily visible Fig 12 Some EPVS may
16. sing size and shape criteria PA ORBE EVASE H OJ Wardlaw Universit S i of Edinburgh of Edinburgh Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh Although often described as hypointense structures on T1 and FLAIR many EPVS will not be visible unless severe Fig 2 Figure 2 A Sagittal T1 imaging showing severe EPVS in the basal ganglia arrows B Axial T2 and equivalent FLAIR imaging showing a spongiform appearance of the basal ganglia on both sides due to numerous EPVS A J Wardlaw University of Edinburgh J Wardlaw University of Edinburgh i N N 1 f T2 weighted imaging FLAIR 6 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh If EPVS are not identified on T2 images it is very unlikely that they will be identified on other routine sequences Thus T2 images should always be reviewed first Although others have excluded EPVS with surrounding FLAIR hyperintensity when rating EPVS Fig 3 these have been included in the current scale Figure 3 Axial FLAIR MRI showing EPVS surrounded by white matter hyperintensities WMH in the centrum semiovale A arrows and basal ganglia B arrows different patient to A EPVS without surrounding WMH are also visible in both regions arrowheads 7 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh J W
17. uld be counted Figure 18 Marked asymmetry in EPVS with a higher number of EPVS in the posterior cerebral artery territory on the right side arrows OW MIET CEVA University of Edinburgh J Wardlaw J Wardlaw University of University of Edinburgh Edinburgh 27 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh H Focally dilated EPVS In some patients focally dilated EPVS will be seen amongst uniformly dilated EPVS Fig 19 The rating scale does not specifically take account of these Figure 19 Focally dilated EPVS arrows amongst uniformly dilated EPVS ORM ET EWY University of Edinburgh l Differentiating between the most severe categories of centrum semiovale EPVS In many patient cohorts the number of patients exhibiting the highest numbers most severe degrees of EPVS in the centrum semiovale will be limited Experience in rating the highest degrees of EPVS will thus be limited for the majority of people performing EPVS rating J Variations in lesion load between cohorts Rating of EPVS may vary with lesion load as found in observer reliability testing for WMH intermittent review of the full range of EPVS which may be encountered in patients as demonstrated in this guide is advised in order to help raters recalibrate Differences in MRI 28 Guide prepared by Gillian Potter Zoe Morris and Prof Joanna Wardlaw University of Edinburgh
18. und the walls of vessels as they course from the subarachnoid space through the brain parenchyma EPVS appear in all age groups but are only visualised clearly on T2 weighted brain magnetic resonance imaging MRI when enlarged Several EPVS rating scales have been described but these are either limited in their anatomical location in the range of EPVS that they describe or in their method of assessing severity Additionally some scales were tested using specific MRI sequences rather than standard structural brain MRI We reviewed existing EPVS visual rating scales identified omissions or ambiguities in each and used this combined knowledge to design improvements to one existing scale that already most closely met requirements for a comprehensive easy to use scale We then tested this revised scale on 60 MRI scans chosen to demonstrate a full range of EPVS frequencies and designed a comprehensive user guide Using the revised scale and the user guide two observers showed similar intra rater agreement for BG CS and midbrain EPVS ranging from good to very good kappa values Inter rater agreement was moderate for CS and MB EPVS on both ratings although very good for BG EPVS on the initial rating Disagreements were mainly due to the counting of very small but just visible EPVS which were a recognised source of difficulty prior to rating Other main causes for disagreement were the presence of background white matter hyperintensiti
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