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Simple Measurement of Aneurysm Residual after Treatment: the SMART scale for evaluation of intracranial aneurysms treated with flow diverters

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Abstract

Background

Primary endovascular reconstruction with flow diversion represents a fundamental paradigm shift in the technique of endovascular aneurysm treatment. Unlike coil embolization, often there remains residual post-procedural filling within the aneurysm with flow diverters, the curative reconstruction presumably occurring over a period of weeks. Thus, conventional grading scales for post-procedural aneurysm occlusion and recanalization are inadequate. The aim of this paper is to propose a new angiographic grading scale that addresses this fundamentally new treatment option.

Method

A five-point grading scale describes the location of residual flow within the aneurysm in the venous phase [grade 1: patent aneurysm with diffuse inflow; grade 2: residual filling of the aneurysm dome (saccular) or wall (fusiform); grade 3: only residual neck (saccular) or only intra-aneurysmal filling with former boundaries covered (fusiform); grade 4: complete occlusion].

Findings

Grade 0 represents any aneurysm, regardless of occlusion rate with early phase, coherent inflow jet. Intra-aneurysmal flow stagnation is categorized into: (a) none, (b) capillary phase, and (c) venous phase. Prevailing parent vessel hemodynamics with in-stent stenosis (ISS) are divided into none (ISS0), mild (ISS1), moderate (ISS2), severe (ISS3), and total (ISS4) occlusion. The proposed grading scales allow assessment of the hemodynamic consequences of stent placement on endosaccular in-flow, stasis, and location of stasis as well as parent vessel hemodynamics.

Conclusions

Further studies need to show the applicability and possible predictive value of this new grading scale on the efficacy of the stent in promoting intra-aneurysmal flow stagnation, thus creating the potential to harmonize the results of future papers. This may help to optimize treatment and future device design.

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Conflicts of interest

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Author information

Authors and Affiliations

  1. Acute Vascular Imaging Centre (AVIC), NIHR Oxford Biomedical Research Centre, University of Oxford and Oxford Radcliffe Hospital NHS Trust, John Radcliffe Hospital, Oxford, OX3 9DU, UK

    Iris Quasar Grunwald

  2. Oxford Neurovascular and Neuroradiology Research Unit, Level 6 West Wing, John Radcliffe Hospital, Oxford, UK

    M. Kamran

  3. Department for Neuroradiology, West Wing, John Radcliffe Hospital, Oxford, UK

    R. A. Corkill

  4. New England Center for Stroke Research, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA

    A. L. Kühn & M. J. Gounis

  5. Lahey Clinic Medical Center, School of Medicine, Tufts University, Burlington, MA, USA

    I. S. Choi

  6. Nuffield Department of Surgery, University of Oxford, Oxford, UK

    R. A. Corkill, S. Turnbull & D. Dobson

  7. Department of Neurology, Saarland University, Homburg, Germany

    K. Fassbender

  8. Consultant Biomedical Engineer, San José, CA, USA

    D. Watson

Authors
  1. Iris Quasar Grunwald
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  2. M. Kamran
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  3. R. A. Corkill
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  4. A. L. Kühn
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  5. I. S. Choi
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  6. S. Turnbull
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  7. D. Dobson
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  8. K. Fassbender
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  9. D. Watson
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  10. M. J. Gounis
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Corresponding author

Correspondence to Iris Quasar Grunwald.

Additional information

Comment

Grunwald et al. propose a new scale for the evaluation of aneurysm residual after flow-diversion stenting. They suggest a five-point scale that represents five radiologic phenomena within the aneurysm sac that are seen after flow-diversion stenting throughout the arterial, capillary, and venous phases. Grade 0 (a–c) represents any flow seen within the aneurysm in the early arterial phase. The rest of the scale describes the flow in the aneurysm seen during the venous phase: grade 1—diffuse flow with a patent aneurysm, grade 2—reduction of flow with filling of the dome/outer wall of the aneurysm, grade 3—residual neck filling with occlusion of the dome/outer wall, and grade 4—complete occlusion. Another proposal is a scale for the effect of this technology on the parent artery, i.e., in-stent stenosis (grade 0—no stenosis and grade 4—occlusion of the stent).

The authors have incorporated the radiologic phenomena seen after flow diversion into a scale that may help us to understand this evolving technology and to better understand these changes and, thus, to reduce the risk of post-stenting rupture. The authors’ novel radiologic scale for the assessment of the flow in aneurysms after flow-diversion stenting is an easy scale to use, without the need for further technology. The scale takes into account the principles of flow-diversion technology and the radiologic presentation of the flow changes in the aneurysm, with extrapolation of these phenomena on the risk for rupture. Further studies with more cases will be needed to show the predictive value of this scale.

Shady Jahshan

L. Nelson Hopkins

Buffalo, New York, USA

All authors contributed equally

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Grunwald, I.Q., Kamran, M., Corkill, R.A. et al. Simple Measurement of Aneurysm Residual after Treatment: the SMART scale for evaluation of intracranial aneurysms treated with flow diverters. Acta Neurochir 154, 21–26 (2012). https://doi.org/10.1007/s00701-011-1177-0

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  • DOI: https://doi.org/10.1007/s00701-011-1177-0

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