Imaging in Neurovascular Disease A Case-Based Approach

Imaging in Neurovascular Disease A Case-Based Approach

by Waleed Brinjikji (Author), Timo Krings (Author)

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Unique case-based reference presents high-yield images and expertise focused on vascular neuroradiology

Imaging in Neurovascular Disease: A Case-Based Approach by Waleed Brinjikji and Timo Krings is unique in its approach, detailing diagnostic and interventional neuroradiology cases based on radiologic findings. The book explores the key role vascular imaging can play in treatment decision making, prognostication, and improving the understanding of the pathophysiology of neurovascular diseases.

Spread over 11 chapters, this book covers a full spectrum of neurovascular diseases spanning the age continuum, starting with acute ischemic stroke, concluding with spinal vascular disease. All vascular neuroradiology cases follow a consistent format. After a succinct introduction describing the clinical scenario with relevant case images, the authors present key facts about the disease and the integral role of different neurovascular imaging procedures in disease management. Imaging findings are discussed in depth, with insightful clinical pearls on image-guided procedures and tips on managing potential pitfalls.

Key Highlights

About 600 high-quality noninvasive images, such as MR angiography/MR imaging, CT angiography/CT perfusion, with angiography where applicable, elucidate a spectrum of findings Analysis of the imaging appearance of a diverse array of common to rare neurovascular diseases provides diagnostic and treatment insights Each case concludes with the most important points clinicians need to know, high-yield facts about a specific cerebrovascular disease, and suggested readings for further exploration This unique case-based book is essential reading for radiology, neurology and neurosurgery residents. It will greatly benefit neurovascular disease specialists including radiologists, neurosurgeons and neurologists as well as interested in furthering their knowledge on the use of neuroimaging to guide neurointerventional and neurosurgical procedures to treat cerebrovascular disease.

This book includes complimentary access to a digital copy on https://medone.thieme.com.

Neuromelanin magnetic resonance imaging

Neuromelanin magnetic resonance imaging

Neuromelanin-sensitive MRI (NM-MRI) purports to detect the content of neuromelanin (NM), a product of dopamine metabolism that accumulates with age in dopamine neurons of the substantia nigra (SN). Interindividual variability in dopamine function may result in varying levels of NM accumulation in the SN; however, the ability of NM-MRI to measure dopamine function in nonneurodegenerative conditions has not been established.


Neuromelanin sensitive MRI may be the method of choice for the follow-up of meningeal melanocytoma 1).


Cassidy et al. validated that NM-MRI signal intensity in postmortem midbrain specimens correlated with regional NM concentration even in the absence of neurodegeneration, a prerequisite for its use as a proxy for dopamine function. They then validated a voxelwise NM-MRI approach with sufficient anatomical sensitivity to resolve SN subregions. Using this approach and a multimodal dataset of molecular PET and fMRI data, they further showed the NM-MRI signal was related to both dopamine release in the dorsal striatum and resting blood flow within the SN. These results suggest that NM-MRI signal in the SN is a proxy for function of dopamine neurons in the nigrostriatal pathway. As a proof of concept for its clinical utility, we show that the NM-MRI signal correlated to severity of psychosis in schizophrenia and individuals at risk for schizophrenia, consistent with the well-established dysfunction of the nigrostriatal pathway in psychosis. The results indicate that noninvasive NM-MRI is a promising tool that could have diverse research and clinical applications to investigate in vivo the role of dopamine in neuropsychiatric illness 2).


A study aimed to evaluate the accuracy and diagnostic test performance of the U-net-based segmentation method in neuromelanin magnetic resonance imaging (NM-MRI) compared to the established manual segmentation method for Parkinson’s disease diagnosis.

NM-MRI datasets from two different 3T-scanners were used: a “principal dataset” with 122 participants and an “external validation dataset” with 24 participants, including 62 and 12 PD patients, respectively. Two radiologists performed SNpc manual segmentation. Inter-reader precision was determined using Dice coefficients. The U-net was trained with manual segmentation as ground truth and Dice coefficients used to measure accuracy. Training and validation steps were performed on the principal dataset using a 4-fold cross-validation method. We tested the U-net on the external validation dataset. SNpc hyperintense areas were estimated from U-net and manual segmentation masks, replicating a previously validated thresholding method, and their diagnostic test performances for PD determined.

For SNpc segmentation, U-net accuracy was comparable to inter-reader precision in the principal dataset (Dice coefficient: U-net, 0.83 ± 0.04; inter-reader, 0.83 ± 0.04), but lower in external validation dataset (Dice coefficient: U-net, 079 ± 0.04; inter-reader, 0.85 ± 0.03). Diagnostic test performances for PD were comparable between U-net and manual segmentation methods in both principal (area under the receiver operating characteristic curve: U-net, 0.950; manual, 0.948) and external (U-net, 0.944; manual, 0.931) datasets.

U-net segmentation provided relatively high accuracy in the evaluation of the SNpc in NM-MRI and yielded diagnostic performance comparable to that of the established manual method 3)

References

1)

Matsuno H, Takasu S, Seki Y. Usefulness of Neuromelanin Sensitive MRI for En Plaque Meningeal Melanocytoma Involving the Cavernous Sinus: A Case Report. NMC Case Rep J. 2019 Mar 21;6(2):43-46. doi: 10.2176/nmccrj.cr.2018-0211. eCollection 2019 Apr. PubMed PMID: 31016099; PubMed Central PMCID: PMC6476814.
2)

Cassidy CM, Zucca FA, Girgis RR, Baker SC, Weinstein JJ, Sharp ME, Bellei C, Valmadre A, Vanegas N, Kegeles LS, Brucato G, Jung Kang U, Sulzer D, Zecca L, Abi-Dargham A, Horga G. Neuromelanin-sensitive MRI as a noninvasive proxy measure of dopamine function in the human brain. Proc Natl Acad Sci U S A. 2019 Mar 12;116(11):5108-5117. doi: 10.1073/pnas.1807983116. Epub 2019 Feb 22. PubMed PMID: 30796187; PubMed Central PMCID: PMC6421437.
3)

Le Berre A, Kamagata K, Otsuka Y, Andica C, Hatano T, Saccenti L, Ogawa T, Takeshige-Amano H, Wada A, Suzuki M, Hagiwara A, Irie R, Hori M, Oyama G, Shimo Y, Umemura A, Hattori N, Aoki S. Convolutional neural network-based segmentation can help in assessing the substantia nigra in neuromelanin MRI. Neuroradiology. 2019 Aug 10. doi: 10.1007/s00234-019-02279-w. [Epub ahead of print] PubMed PMID: 31401723.

Ferumoxytol magnetic resonance imaging for intracranial arteriovenous malformation

Ferumoxytol magnetic resonance imaging for intracranial arteriovenous malformation

Central nervous system vascular malformations (VMs) result from abnormal vascular- and/or angiogenesis. Cavernomas and arteriovenous malformations are also sites of active inflammation 1).

Inflammation is increasingly being recognized as contributing to the underlying pathophysiology of cerebral aneurysms and brain arteriovenous malformationFerumoxytol is being increasingly used for both its prolonged intravascular imaging characteristics and its utility as an inflammatory marker when imaged in a delayed fashion 2) 3) 4) 5).

Children with intracranial arteriovenous malformations (AVMs) undergo digital DSA for lesion surveillance following their initial diagnosis. However, DSA carries risks of radiation exposure, particularly for the growing pediatric brain and over lifetime. Huang et al. evaluated whether MRI enhanced with a blood pool ferumoxytol (Fe) contrast agent (Fe-MRI) can be used for surveillance of residual or recurrent AVMs.

A retrospective cohort was assembled of children with an established AVM diagnosis who underwent surveillance by both DSA and 3-T Fe-MRI from 2014 to 2016. Two neuroradiologists blinded to the DSA results independently assessed Fe-enhanced T1-weighted spoiled gradient recalled acquisition in steady state (Fe-SPGR) scans and, if available, arterial spin labeling (ASL) perfusion scans for residual or recurrent AVMs. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and intermodality reliability were determined using DSA studies as the gold standard. Radiation exposure related to DSA was calculated as total dose area product (TDAP) and effective dose.

Fifteen patients were included in this study (mean age 10 years, range 3-15 years). The mean time between the first surveillance DSA and Fe-MRI studies was 17 days (SD 47). Intermodality agreement was excellent between Fe-SPGR and DSA (κ = 1.00) but poor between ASL and DSA (κ = 0.53; 95% CI 0.18-0.89). The sensitivity and specificity for detecting residual AVMs using Fe-SPGR were 100% and 100%, and using ASL they were 72% and 100%, respectively. Radiologists reported overall high diagnostic confidence using Fe-SPGR. On average, patients received two surveillance DSA studies over the study period, which on average equated to a TDAP of 117.2 Gy×cm2 (95% CI 77.2-157.4 Gy×cm2) and an effective dose of 7.8 mSv (95% CI 4.4-8.8 mSv).

Fe-MRI performed similarly to DSA for the surveillance of residual AVMs. Future multicenter studies could further investigate the efficacy of Fe-MRI as a noninvasive alternative to DSA for monitoring AVMs in children 6).


The purpose of a study was to evaluate the performance of ferumoxytol-enhanced MRA using a high-resolution 3D volumetric sequence (fe-SPGR) for visualizing and grading pediatric brain AVMs in comparison with CTA and DSA, which is the current imaging gold standard. METHODS In this retrospective cohort study, 21 patients with AVMs evaluated by fe-SPGR, CTA, and DSA between April 2014 and August 2017 were included. Two experienced raters graded AVMs using Spetzler-Martin criteria on all imaging studies. Lesion conspicuity (LC) and diagnostic confidence (DC) were assessed using a 5-point Likert scale, and interrater agreement was determined. The Kruskal-Wallis test was performed to assess the raters’ grades and scores of LC and DC, with subsequent post hoc pairwise comparisons to assess for statistically significant differences between pairs of groups at p < 0.05. RESULTS Assigned Spetzler-Martin grades for AVMs on DSA, fe-SPGR, and CTA were not significantly different (p = 0.991). LC and DC scores were higher with fe-SPGR than with CTA (p < 0.05). A significant difference in LC scores was found between CTA and fe-SPGR (p < 0.001) and CTA and DSA (p < 0.001) but not between fe-SPGR and DSA (p = 0.146). A significant difference in DC scores was found among DSA, fe-SPGR, and CTA (p < 0.001) and between all pairs of the groups (p < 0.05). Interrater agreement was good to very good for all image groups (κ = 0.77-1.0, p < 0.001). CONCLUSIONS Fe-SPGR performed robustly in the diagnostic evaluation of brain AVMs, with improved visual depiction of AVMs compared with CTA and comparable Spetzler-Martin grading relative to CTA and DSA 7).

References

1)

Dósa E, Tuladhar S, Muldoon LL, Hamilton BE, Rooney WD, Neuwelt EA. MRI using ferumoxytol improves the visualization of central nervous system vascular malformations. Stroke. 2011 Jun;42(6):1581-8. doi: 10.1161/STROKEAHA.110.607994. Epub 2011 Apr 14. PubMed PMID: 21493906; PubMed Central PMCID: PMC3412426.
2)

Zanaty M, Chalouhi N, Starke RM, Jabbour P, Hasan D. Molecular Imaging in Neurovascular Diseases: The Use of Ferumoxytol to Assess Cerebral Aneurysms and Arteriovenous Malformations. Top Magn Reson Imaging. 2016 Apr;25(2):57-61. doi: 10.1097/RMR.0000000000000086. Review. PubMed PMID: 27049242.
3)

Chalouhi N, Jabbour P, Magnotta V, Hasan D. Molecular imaging of cerebrovascular lesions. Transl Stroke Res. 2014 Apr;5(2):260-8. doi: 10.1007/s12975-013-0291-0. Epub 2013 Oct 23. Review. PubMed PMID: 24323714.
4)

Chalouhi N, Jabbour P, Magnotta V, Hasan D. The emerging role of ferumoxytol-enhanced MRI in the management of cerebrovascular lesions. Molecules. 2013 Aug 13;18(8):9670-83. doi: 10.3390/molecules18089670. Review. PubMed PMID: 23945642; PubMed Central PMCID: PMC6270297.
5)

Hasan DM, Amans M, Tihan T, Hess C, Guo Y, Cha S, Su H, Martin AJ, Lawton MT, Neuwelt EA, Saloner DA, Young WL. Ferumoxytol-enhanced MRI to Image Inflammation within Human Brain Arteriovenous Malformations: A Pilot Investigation. Transl Stroke Res. 2012 Jul;3(Suppl 1):166-73. doi: 10.1007/s12975-012-0172-y. PubMed PMID: 23002401; PubMed Central PMCID: PMC3445332.
6)

Huang Y, Singer TG, Iv M, Lanzman B, Nair S, Stadler JA, Wang J, Edwards MSB, Grant GA, Cheshier SH, Yeom KW. Ferumoxytol-enhanced MRI for surveillance of pediatric cerebral arteriovenous malformations. J Neurosurg Pediatr. 2019 Jul 19:1-8. doi: 10.3171/2019.5.PEDS1957. [Epub ahead of print] PubMed PMID: 31323627.
7)

Iv M, Choudhri O, Dodd RL, Vasanawala SS, Alley MT, Moseley M, Holdsworth SJ, Grant G, Cheshier S, Yeom KW. High-resolution 3D volumetric contrast-enhanced MR angiography with a blood pool agent (ferumoxytol) for diagnostic evaluation of pediatric brain arteriovenous malformations. J Neurosurg Pediatr. 2018 Sep;22(3):251-260. doi: 10.3171/2018.3.PEDS17723. Epub 2018 Jun 8. PubMed PMID: 29882734.
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