2016 Winter Project Week/Projects/EVD

Measuring Anatomic Factors for Extraventricular Drain Placement

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  Projects List

Key Investigators

• Kirby Vosburgh (BWH)
• P. Jason White (BWH)

Project Description

Objective	Approach and Plan	Progress and Next Steps
In current clinical practice, extraventricular drains (EVD) are inserted though the brain into a ventricle to release excess pressure in cerebral spinal fluid. They are placed manually, generally perpendicular to the skull at Kocher's Point. Inaccurate initial placement is common, and iatrogenic morbidity is evident in a few percent of cases. Published data from our team, prior collaborations, and a few other investigators, is limited and not entirely consistent, but there is general agreement that the procedure should be improved, but only if the new method is inexpensive and rapidly and easily used. Dr. Vosburgh, with collaborators at MGH and BWH, has pursued a variety of approaches to EVD placement, such as the Smart Stylet, with the goal of replacing today’s freehand technique. Recently, working with Jason White, PhD and consulting with William Gormley, MD at BWH, various ultrasound-based Extra-Ventricular Drain guidance concepts have been explored. To reduce these inventions to practice, we need a more accurate understanding of the geometrical factors governing accurate EVD placement in a significant sample of likely patients.	Under IRB approval for a retrospective study, we propose to extract from the BWH archive pre-procedure CT data sets for patients who then received an EVD placement. Among the data we will derive from the image set are: How often will orthogonal insertion at Kocher’s Point penetrate the target in the lateral ventricle? What is the range of final placements, assuming strict orthogonality is achieved? How accurately must the location of Kocher’s point be determined? In what fraction of the patients are the ventricles distorted or displaced? What is the likely B-scan ultrasound signal profile through the Kocher’s Point burr hole, and through other commonly used probe insertion sites on the skull? If transcranial imaging is used, what are skull thicknesses and other anatomic factors relevant to ultrasound beam transmission? What is the range of depths from the dura to the nearest appropriate ventricular access point? To answer these and related questions, we propose to use 3D Slicer and PLUS to measure and record these data for each CT image set. Our Project this week consists of getting this analysis software up and running on MacBooks. Kirby will supply some CT Data (such as used clinically) to work with. These initial tests will supply preliminary information to support the IRB application. Once data reduction is completed for the full data set, the data and results will be published and posted on line.	Raul San Jose got us started on simple thresholding and seed placement, and then handed us off to Beatriz Paniagua who showed us how their CMF Extension could be used for our geometric processing Steve Pieper was very helpful in two ways: Introducing us to Randy Gollub, and then giving a detailed demo of ventricle segmentation using GrowCut, which was enabled by a trick for reformatting our DICOM data so that they could be read. These tricks are really handy. Randy got us launched with RPDR (for downloading DICOM data from the electronic medical record system), and then grabbed Kirby’s Mac and bookmarked the key pages we should understand and use.

References

• Patil V, Lacson R, Vosburgh KG, Wong JM, Prevedello L, Andriole K, Mukundan S, Popp AJ, Khorasani R. Factors associated with external ventricular drain placement accuracy: data from an electronic health record repository. Acta Neurochir (Wien). 2013 Sep;155(9):1773-9. PMID: 23700258; PMC3744605.
• Patil V, Gupta R, San José Estépar R, Lacson R, Cheung A, Wong JM, Popp AJ, Golby A, Ogilvy C, Vosburgh KG. Smart stylet: the development and use of a bedside external ventricular drain image-guidance system. Stereotact Funct Neurosurg. 2015;93(1):50-8. PMID: 25662506; PMC4423620.
• Meral FC, Persaud MA, Silva AE, Mundra A, Clement GT, Vosburgh KG, White PJ. A novel device for guiding ventriculostomy with transcranial ultrasound. J Acoust Soc Am. 2014 Apr; 135(4):2211.
• Ghajar JBG. A guide for ventricular catheter placement--Technical note. J Neurosurg.1985; 63(6):985-6.