Research Article A Simple and Inexpensive Stereotactic ...downloads.hindawi.com/archive/2014/139535.pdfto develop stereotactic cerebral interventions or MRI-compatible guidance frames,

Research ArticleA Simple and Inexpensive Stereotactic Guidance Framefor MRI-Guided Brain Biopsy in Canines

Alexander D Squires1 Yabiao Gao1 Sean F Taylor1

Marc Kent2 and Zion Tsz Ho Tse1

1 College of Engineering The University of Georgia Athens GA 30602 USA2College of Veterinary Medicine The University of Georgia Athens GA 30602 USA

Correspondence should be addressed to Alexander D Squires asquiresugaedu

Received 9 December 2013 Revised 10 April 2014 Accepted 13 April 2014 Published 18 May 2014

Academic Editor Olivier Beuf

Copyright copy 2014 Alexander D Squires et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A magnetic resonance imaging (MRI) guided stereotactic system was developed to provide veterinarians a method to accomplishminimally invasive stereotactic brain biopsies and procedures involving the cerebrum in canines While MR-guided proceduresare prevalent for humans they are less common in animal practices The system was designed to minimize fabrication costs in aneffort tomake such procedures more accessible in the veterinary field A frame constrained the head without the need for puncturesand supported registration and guidance attachments Location data for registration and relevant structures were selected by theclinician and a reverse kinematic analysis program generated the settings of the stereotactic arch to guide a needle to the desiredlocation Phantom experiments and three cadaver trials showed an average targeting error of lt3mm using the system

1 Introduction

Magnetic resonance imaging (MRI) is widely used inmedicalresearch andpractice due to its ability to peer inside biologicalorganisms with superior image quality providing high-quality soft tissue imaging while not exposing patients topotentially ionizing radiation or contrast agents [1] Advancesin MRI technology have led to numerous studies and thedevelopment of MR-guided treatment techniques [2] Ofparticular interest here is the prevalence of MR-guidedbrain biopsy procedures [3ndash14] as well as similar proceduresperformed via computed tomography (CT) [15ndash18]

Utilizing MRI to perform brain biopsies in humans iscommon but in canine subjects tumor diagnosis is mostcommonly performed postmortem Naturally such timingdoes not help the patient and access to tumors in vivois desirable Image-based diagnosis by itself provides lesscertainty and open-skull biopsies require a sizable amountof tissue and bone to be damaged or removed both caseshave their drawbacks [17] Stereotactic procedures can bemuch superior thanks to their precise targeting abilities and

the small size of holes in tissue and bone which are requiredcausing tissue to be minimally damaged

Inside an MR suite use of certain materials will degradeimage quality andor endanger the safety of a patient [19] Forthis reason any device which operates on electromagneticprinciples (such as common electric motors or relays) is notcompatible with the MR environment [20] Thus actuationof devices inside the MR suite must be powered usingother means often via pneumatics or piezoceramics [21]Additionally any ferro-paramagnetic materials are bannedfor safety reasons [19 20 22] Plastics are frequently used forthis reason certain nonmagnetic metals such as aluminumbrassm or titanium can also be used but run the risk ofcausing interference with image acquisition and generatingartifacts [22ndash24] Electrical circuits must be shielded toprevent interference in both directions [1]

Previously researchers have developed various stereotac-tic brain biopsy platforms for animal subjects [25] Whileprevious procedures enabled high-precision stereotaxy thereis plenty of room for optimization One issue is thatsome current techniques are based on external markers

Hindawi Publishing CorporationJournal of Medical EngineeringVolume 2014 Article ID 139535 7 pageshttpdxdoiorg1011552014139535

2 Journal of Medical Engineering

(skull fiducials) These markers are related to an MRI visu-alized intracranial target Depending on MRI slice thicknessand the size and shape of the markers this technique maycause some distortion and inaccuracy during MR imagingand identification of the markers [26] Another problem canbe that coordinates are calculated in 2D space on an MRIviewer screen while failing to consider 3D reconstructiondata or automatic target calculation Another potential issueis that the trajectory can be constrained to a straight verticalapproach with no angled or oblique targeting in the dorsal ortransverse planes available due to their need for more robustand complex calculations requiring greater information thanthat which is provided in 2D space Vertical trajectoriesmay restrict the surgeon to unhelpful and inappropriatetrajectories To solve these problems the currently existingLeskell system an arch-based stereotactic system for isocen-tric stereotaxy and 3D coordinate calculations relative tostereotactic frame integrated with fiducial markers couldbe implemented The Leskell system is already clinicallyavailable [27]While there has been some evidence to suggestthat free-hand techniques performed under MRI guidancemay be the equal or superior to stereotactic techniques[28 29] the surgeons working with the project expressed adesire for the use of a stereotactic frame thus causing thatavenue to be pursued Research has demonstrated that frame-based stereotactic systems are more accurate than framelesssystems thus a frame-based method was explored for theconstruction of the device [30]

This study aimed to integrate fiducial marker Z-framesinside the scanner with a modified Leskell stereotactic archused outside the magnetic field to enable arch-based isocen-tric stereotaxyThe request for the construction of this devicecame from the neurosurgical unit of theUniversity ofGeorgiaVeterinary School Following an MRI scan to locate braintumors and determine operability an open skull biopsy isperformed to obtain a sampleDesiring a less invasivemethodof surgery the developed system took inspiration fromprevious research and developed a low-cost system (in termsof additional costs to the existing procedure) to integratewith current operational procedures Given an average tumordiameter of 10mm to biopsy the surgeons requested less than3mm of error when targeting the center of the tumor

2 Materials and Methods

21 Overview Previous studies have been conductedto develop stereotactic cerebral interventions or MRI-compatible guidance frames including several whichimplement Z-frame approaches and 3-point head fixations[11ndash14 25ndash27 31ndash37] We combined both fields developingan MRI-guided device to assist veterinarians in executingminimally invasive brain biopsies and other cerebralprocedures

The design consists of a primary frame with two setsof attachments one for imaging and the other for needleplacement The framersquos cross-section is U-shaped in order tomaintain sufficient strength and stiffness contain a caninersquoshead and fit inside a standard MRI head coil

Table 1 Materials costs

Delrin $175Aluminum $20Stereotactic arch $600Contrast agent $10Assorted hardware $85Fabrication shop labor $500Total $1410

The Z-frame attachments contain tubes of Vitamin E oilacting as a localizing agent (to replace fiducials) to facilitateimage registration The geometry of the markers ensuresthat either a dorsal or transverse plane will contain 6 pointswhere the plane intersects the tubes A LabView program(National Instruments Austin Texas) was written to uselocation data (X Y and Z coordinates) from these points andcreate a mapping of the scannerrsquos coordinate system onto thecoordinate system of the frame

Following image acquisition the veterinarian determinedthe location of structure(s) to be targeted The relevantcoordinates from the scanner were mapped onto the framersquoscoordinate system using the developed transform Aftertransformation the relevant coordinates were fed into a sec-ond LabView program which performed reverse kinematicscalculations to generate the adjustments on the stereotacticarch which enable the point of a biopsy needle to arrive at thetarget point

After completing the necessary imaging the Z-frameattachments could be removed outside the MRI suite andreplaced with the stereotactic arch and its supports Onceattached the archwould be adjusted following the parametersestablished by the program providing a precise guide for theclinician to perform their procedures

By utilizing a simple frame a commonplace material fora contrast agent and a surplus stereotactic arch the cost ofmaterials for the project wasminimized An outline of pricingfor the materials used in the final system is shown in Table 1

22 Mechanical Design The body of the device (Figure 1(a))consists of four sets of components the primary frame theZ-frames the arch support attachments the stereotactic archand a 14-gauge biopsy needle The primary frame consistsof Delrin U-shaped end pieces with Delrin lateral supports(Figures 1(b) and 1(c))The supports constrain the attachmentpieces Zygomatic arch supports are located in the center ofthe lateral supports and consist of a rubber sheet over an ABSconcave support which is attached to a brass threaded rodA post to support the bite plate (both Delrin) is attached toone of the end piecesThe support structures are independentfrom the attachment pieces ensuring patients do not shiftduring transition between attachments These supports arenoninvasive eliminating the need for bone screws to supportfiducial markers or a stereotactic device The frame wasconstructed to conform to the space within the head coilused by the veterinary neurosurgeonThe frame secures headwidths between 7 and 20 cm The framersquos design could be

Journal of Medical Engineering 3

(a) Arch front view

NeedleStereotactic

archZ

Y

Arch parallel shift range along Y

45∘

minus100sim100 mm

Headphantom

(b) Z-frame front view

Z

X

Arch parallel shift range along X

20∘

60∘

minus80sim150mm

(c) Z-frame lateral view

Figure 1 (a) Stereotactic arch and frame assembled for needle guidance Design (left) and workspace (right) of the stereotactic guidanceframe in front (b) and lateral (c) views

widened to support the heads of larger breeds as well inconjunction with a body coil

The Z-frames and arch attachments were also manufac-tured from Delrin Internal channels in the Z-frames containremovable tubes filled with Vitamin E oil The arch supportshave aluminum rails to mount the stereotactic arch Bothsets of attachments attach to the frame via nylon screws andnuts and are capable of being changed out without disturbingpatient fixation

The stereotactic arch has 5 degrees of freedom Thearch slides along the rails of the arch support frame (X)rotates about an axis drawn between the rails (rotates aroundY) slides along that same axis (Y) and rotates about anaxis parallel and central to the two rails (rotates aroundX) Additionally the support frames can be set to one oftwo vertical positions and the needle depth adjusted with astopper (both affect Z position)

23 Z-Frame Design The Z-frames each contain five tubesfilled with an image contrast agent (Figure 2(a)) Four tubesform a rectangle while the fifth lies along a diagonal Whenattached to the primary frame the diagonals form an Xwhen viewed laterally (Figure 2(b))This configuration allowseither a dorsal or transverse image slice to be used to developa coordinate system for the frame and dog The opposingdiagonals generate a unique solution for any possible plane

which intersects the Z-frames allowing the true position ofthe frame to be known

24 Image Registration Amapping between theMRI coordi-nate system (119875) and the stereotactic frame coordinate system(1198751) is required to perform kinematic calculations We usedknown physical relationships of the Z-frames (Figure 2(a))in the stereotactic frame coordinate system to calculate atransformation matrix between the two coordinate systems(Figure 2(c)) Markers 1 3 4 and 6 in Figure 3(a) were usedto calculate a 4times4 transformationmatrix119879 using the formula119875 = 119879 sdot 119875

1 [38] in a Matlab program (MathWorks NatickMassachusetts) embedded into the LabView interface Sincean arbitrary frontal plane is imaged to obtain registrationpoints the relationship between the scanner Z-coordinateand frame Z-coordinate is initially unknown it is calculatedusing distances between registration points in the frontalplane image Figure 3(b) shows the relationships used whencalculating the Z-coordinate of the base frame The Z-coordinate in the frame coordinate system is calculated as

119911 =(119897 minus 2119889) ℎ

2119897

(1)

where the lengths are taken from the registration image 119889 isthe distance between marker 2 and 3 ℎ is the length of theZ-frame in Z-axis of stereotactic coordinate system and 119897 is


(a) Z-frame interior view

MRIscanning

plane

Z frame

1

l

2

3d

a

h

X998400

(b) Z-frame geometry

(X 998400 Y 998400

Z998400

Y998400

)

Z998400

00

X

Y

ZP (P1)

MRIscanner

Stereotacticframe

X998400

(X Y Z)

(c) MRI amp framersquos coordinates

Figure 2 (a) Z-frame design (b) Calculation of 6 points to X Y and Z coordinate in guidance frame and (c) MRI-frame registration

Phantom results

(a) Registration markers in Z-frame

Phantom results

(b) Tumor embedded phantom

Phantom results

(c) Needle targeting

Cadaver trial results

(d) Cadaver trial registration image


(e) Cadaver trial

AGAR


(f) Agar phantom in cadaver

Figure 3 MRI images of (a) the Z-frame markers for registration and (b) of the target tumor target in the agar phantom (c) Photo of agarphantom (d) Registration image from cadaver trial and (e) performing the cadaver biopsy (f) Agar embedded in the skull


the length of the Z-frame in X-axis of stereotactic coordinatesystemAfter themapping processwas finished the stereotac-tic coordinates can be converted from their MR coordinatesvia inverse transformation Assuming the coordinate matrixof a target point is119862 in theMR scanner coordinate system andits corresponding coordinate in stereotactic system is1198621 then1198621= 119879minus1sdot119862The inverse kinematics necessary to position the

stereotactic arch are processed in a second LabView interfacean operator can adjust the trajectory and observe the requiredsettings of the stereotactic frame to hit the target ldquotumorrdquo

3 Results and Discussion

31 Experimental Setup in MRI Phantom tests (Figure 2(c))and preliminary cadaver studies (Figure 3(e)) to confirm thesafety and precision of the system were performed in a 3TGE MRI scanner The phantoms used in the experimentswere made from agar gel containing tumor representationsmade of 5mm to 10mm diameter balls of putty (Figure 3(c))which displayed as a dark spot on a lighter background in theMRI images (Figures 3(a) and 3(d)) For the cadaver studiesthe cerebrum was removed and replaced with the phantommaterial (Figure 3(f))

For the MRI tests a vial of image contrast agent wasplaced in the phantom in the +X +Y quadrant of the primaryframe to provide an easily distinguishable reference pointThe phantom was placed in the frame and fixed via thezygomatic arch supports and a modified bite plate The Z-frame attachments were placed on the frame and the systemwas scanned with a gradient echo sequence (TR = 200 flipangle = 30 slice thickness = 3mm pixel size = 1mm times 1mmnumber of slices = 15 FOV = 300mm times 300mm BW =130Hzpixel) Signal-to-noise ratio reductionswere under 2while the system was in the scanner After acquiring imagescontaining the points necessary for registration (Figure 3(a))and the locations of the ldquotumorsrdquo (Figure 3(b)) the systemwas removed from the MRI

Following the removal from the scanner room the Z-frames were replaced by the arch and its support attachmentsThe settings on the arch to target a particular ldquotumorrdquo wereprocessed by the LabView programs the arch was thenadjusted to match those settings by an operator Finally astopper that was placed on a biopsy needle to halt it progressat the indicated depth was addedThe biopsy needle was theninserted into the arch and then into the phantom

32 System Precision The sum of squared errors in theregistration process ranged from 240mm to 350mm in ourexperiment Errors were likely caused by Z-frame placementerror in the MRI scanner slight inaccuracies in base framemeasurements for the stereotactic frame coordinate sys-tem and measurement errors when determining registrationmarker coordinates in the MRI We visually determined thecenter of the tumor on screen to serve as the target whichmaynot be themost accurate valueThe result would improvewithan algorithm calculating the center of target utilizingmultipleimages

Table 2 Procedure time summary

Task Time requiredDevice Setup in MRI scanner 2 minutesLocalizer scan 3 minutesManual detection of image markers 5 minutesRegistration 5 minutesInverse kinematics 3 minutesManual joint movement 1 minuteTotal 19 minutes

Distances between needle tip placement and the centersof target tumors were quantified by segmenting the phantomThe errorwhile targeting the phantomwaslt3mm in all trialswhichmet theminimum requirements of the neurosurgeonsSlight errors in the registration process influence the errorin targeting the tumor because the registration matrix con-verts the tumorrsquos MRI coordinates to the framersquos coordinatesystem Notably the most recent cadaver trial had a meantargeting error of 25mm with a sum of squared errors in theregistration process of 243mm indicating that registrationerrors are the major contributing factor to targeting errorThe time required for each task in the process is shown inTable 2 Errors stem from tissue deformation and needleflexing during insertion These errors present themselvesin comparable MRI-guided targeting devices with meantargeting errors ranging from 179mm to 44mm [14 39 40]Similar CT procedures resulted in mean targeting errorsbetween 28mm and 36mm [15ndash17]

4 Conclusion

A stereotactic device for MRI-guided biopsy was designedand fabricated The device was designed to be small enoughto fit into a head coil with a setup time in the MRI scannerof less than 5 minutes The device was tested in a GE3T MRI scanner using a custom made agar phantom withembedded simulated tumors The time for manual detectionand registration of the 6 marker points in the Z-frames wasless than 10 minutes

A biopsy targeting error of lt3mm was measured whichoutperforms the goal of set by our veterinary neurosurgeonfor targeting 10mm diameter tumors Programs with agraphical user interface were developed for the computationof the coordinate system after registration stereotactic archmovement and needle trajectory planning Computationtime was less than 3 minutes per tumor target and themanipulation of the stereotactic arch to target a tumor tookless than 1 minute for a total targeting time of less than 4minutes per target Our experiment demonstrated that alltumors (6 out of 6) were targeted and hit by the needle withan average accuracy of 2mm

5 Future Work

Ongoing work aims to improve registration point selec-tion through the use of feature-based image registration


techniquesThe systemwill be tested in a cohort of swine andcanine cadavers to verify the functionality and accuracy ofthe system After verification the system will be used for thetesting and treatment of live patients

Disclosures

This research received funding from the Georgia CaRES forPets Fund

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] H Elhawary Z T H Tse A Hamed M Rea B L Daviesand M U Lamperth ldquoThe case for MR-compatible roboticsa review of the state of the artrdquo The International Journal ofMedical Robotics and Computer Assisted Surgery vol 4 no 2pp 105ndash113 2008

[2] H Elhawary A Zivanovic B Davies and M Lamperth ldquoAreview of magnetic resonance imaging compatible manipula-tors in surgeryrdquo Proceedings of the Institution of MechanicalEngineers H Journal of Engineering in Medicine vol 220 no3 pp 413ndash424 2006

[3] W A Hall A J Martin H Liu E S Nussbaum R E Maxwelland C L Truwit ldquoBrain biopsy using high-field strengthinterventional magnetic resonance imagingrdquoNeurosurgery vol44 no 4 pp 807ndash813 1999

[4] Y Koseki T Washio K Chinzei and H Iseki ldquoEndoscopemanipulator for trans-nasal neurosurgery optimized for andcompatible to vertical field open MRIrdquo in Proceedings of the5th International Conference on Medical Image Computingand Computer-Assisted Intervention (MICCAI rsquo02) pp 114ndash121Tokyo Japan 2002

[5] J S Lewin ldquoInterventionalMR imaging concepts systems andapplications in neuroradiologyrdquoAmerican Journal of Neuroradi-ology vol 20 no 5 pp 735ndash748 1999

[6] N Miyata E Kobayashi D Kim et al ldquoMicro-grasping forcepsmanipulator for MR-guided neurosurgeryrdquo in Proceedings ofthe 5th International Conference on Medical Image Computingand Computer-Assisted Intervention (MICCAI rsquo02) pp 107ndash113Tokyo Japan 2002

[7] A Rossi A Trevisani and V Zanotto ldquoA telerobotic hapticsystem for minimally invasive stereotactic neurosurgeryrdquo TheInternational Journal of Medical Robotics and Computer AssistedSurgery vol 1 no 2 pp 64ndash75 2005

[8] G R Sutherland P B McBeth and D F Louw ldquoNeuroArm anMR compatible robot for microsurgeryrdquo International CongressSeries vol 1256 pp 504ndash508 2003

[9] C S Tseng ldquoImage-guided robotic navigation system for neu-rosurgeryrdquo Journal of Robotic Systems vol 17 no 8 pp 439ndash4472000

[10] T W Vitaz S G Hushek C B Shields and T M MoriartyldquoInterventional MRI-guided frameless stereotaxy in pediatricpatientsrdquo Stereotactic and Functional Neurosurgery vol 79 no3-4 pp 182ndash190 2002

[11] R Bradford D G Thomas and G M Bydder ldquoMRI-directedstereotactic biopsy of cerebral lesionsrdquo Acta NeurochirurgicaSupplementum vol 39 pp 25ndash27 1987

[12] R J Maciunas and R L Galloway ldquoMagnetic resonance andcomputed tomographic image-directed stereotaxy for animalresearchrdquo Stereotactic and Functional Neurosurgery vol 53 no3 pp 197ndash201 1989

[13] A V Chen F A Wininger S Frey et al ldquoDescription andvalidation of a magnetic resonance imaging-guided stereotacticbrain biopsy device in the dogrdquo Veterinary Radiology amp Ultra-sound vol 53 no 2 pp 150ndash156 2012

[14] K Masamune E Kobayashi Y Masutani et al ldquoDevelopmentof an MRI-compatible needle insertion manipulator for stereo-tactic neurosurgeryrdquo Journal of Image Guided Surgery vol 1 no4 pp 242ndash248 1995

[15] P Moissonnier ldquoAccuracy testing of a new stereotactic CT-guided brain biopsy device in the dogrdquo Research in VeterinaryScience vol 68 no 3 pp 243ndash247 2000

[16] P D Koblik R A Lecouteur R J Higgins et al ldquoModificationand application of a Pelorus Mark III stereotactic system forCT-guided brain biopsy in 50 dogsrdquo Veterinary Radiology ampUltrasound vol 40 no 5 pp 424ndash433 1999

[17] A R Taylor N D Cohen S Fletcher J F Griffin and J MLevine ldquoApplication and machine accuracy of a new framelesscomputed tomography-guided stereotactic brain biopsy systemin dogsrdquo Veterinary Radiology amp Ultrasound vol 54 no 4 pp332ndash342 2013

[18] P Moissonnier S Blot P Devauchelle et al ldquoStereotactic CT-guided brain biopsy in the dogrdquo Journal of Small AnimalPractice vol 43 no 3 pp 115ndash123 2002

[19] GE Medical Systems ldquoMR Safety and Compatibility TestGuidelines for Signa SP Version 1rdquo httpwwwgemedicalsys-temscomradmripdfsaftey1pdf

[20] F G Shellock ldquoMagnetic resonance safety update 2002implants and devicesrdquo Journal of Magnetic Resonance Imagingvol 16 no 5 pp 485ndash496 2002

[21] R Gassert A Yamamoto D Chapuis L Dovat H Bleulerand E Burdet ldquoActuation methods for applications in MRenvironmentsrdquo Concepts in Magnetic Resonance B MagneticResonance Engineering vol 29 no 4 pp 191ndash209 2006

[22] F G Shellock ldquoMetallic surgical instruments for interventionalMRI procedures evaluation of MR safetyrdquo Journal of MagneticResonance Imaging vol 13 no 1 pp 152ndash157 2001

[23] ASTM Standard Test Method for Evaluation of MR ImageArtifacts from Passive Implants Designation F2110-01 AmericanSociety for Testing and Materials 2001

[24] J F Schenck ldquoThe role of magnetic susceptibility in magneticresonance imaging MRImagnetic compatibility of the first andsecond kindsrdquoMedical Physics vol 23 no 6 pp 815ndash850 1996

[25] C R Bjarkam G Cancian M Larsen et al ldquoAMRI-compatiblestereotaxic localizer box enables high-precision stereotaxicprocedures in pigsrdquo Journal of Neuroscience Methods vol 139no 2 pp 293ndash298 2004

[26] R J Maciunas R L Galloway Jr and J W Latimer ldquoTheapplication accuracy of stereotactic framesrdquo Neurosurgery vol35 no 4 pp 682ndash695 1994

[27] L Leksell D Leksell and J Schwebel ldquoStereotaxis and nuclearmagnetic resonancerdquo Journal of Neurology Neurosurgery andPsychiatry vol 48 no 1 pp 14ndash18 1985


[28] W A Hall H Liu A J Martin and C L Truwit ldquoCompar-ison of stereotactic brain biopsy to interventional magnetic-resonance-imaging-guided brain biopsyrdquo Stereotactic and Func-tional Neurosurgery vol 73 no 1ndash4 pp 148ndash153 1999

[29] D Y Wen W A Hall D A Miller E L Seljeskog and RE Maxwell ldquoTargeted brain biopsy a comparison of freehandcomputed tomography-guided and stereotactic techniquesrdquoNeurosurgery vol 32 no 3 pp 407ndash413 1993

[30] H Bjartmarz and S Rehncrona ldquoComparison of accuracyand precision between frame-based and frameless stereotacticnavigation for deep brain stimulation electrode implantationrdquoStereotactic and Functional Neurosurgery vol 85 no 5 pp 235ndash242 2007

[31] C R Bjarkam G Cancian A N Glud K S Ettrup R LJoslashrgensen and J-C Soslashrensen ldquoMRI-guided stereotaxic target-ing in pigs based on a stereotaxic localizer box fitted withan isocentric frame and use of SurgiPlan computer-planningsoftwarerdquo Journal of Neuroscience Methods vol 183 no 2 pp119ndash126 2009

[32] C R Bjarkam ldquoAporcinemodel of subthalamic high-frequencydeep brain stimulation in Parkinsonrsquos diseaserdquo Danish MedicalBulletin vol 51 no 3 p 311 2004

[33] C R Bjarkam R L Jorgensen K N Jensen N A Sunde andJ-C H Soslashrensen ldquoDeep brain stimulation electrode anchoringusing BioGlue a protective electrode covering and a titaniummicroplaterdquo Journal of Neuroscience Methods vol 168 no 1 pp151ndash155 2008

[34] P Cumming E Danielsen M Vafaee et al ldquoNormalizationof markers for dopamine innervation in striatum of MPTP-lesionedminiature pigs with intrastriatal graftsrdquoActa Neurolog-ica Scandinavica vol 103 no 5 pp 309ndash315 2001

[35] J Antonsson O Eriksson P Lundberg and K Wardell ldquoOpti-cal measurements during experimental stereotactic radiofre-quency lesioningrdquo Stereotactic and Functional Neurosurgeryvol 84 no 2-3 pp 118ndash124 2006

[36] N Dorward T Paleologos O Alberti and D Thomas ldquoTheadvantages of frameless stereotactic biopsy over frame-basedbiopsyrdquo British Journal of Neurosurgery vol 16 no 2 pp 110ndash118 2002

[37] S L Simon P Douglas G H Baltuch and J L Jaggi ldquoErroranalysis of MRI and Leksell stereotactic frame target local-ization in deep brain stimulation surgeryrdquo Stereotactic andFunctional Neurosurgery vol 83 no 1 pp 1ndash5 2005

[38] B K Horn ldquoClosed-form solution of absolute orientation usingunit quaternionsrdquo Journal of the Optical Society of America Avol 4 no 4 pp 629ndash642 1987

[39] H Xu A Lasso P Guion et al ldquoAccuracy analysis in MRI-guided robotic prostate biopsyrdquo International Journal of Com-puter Assisted Radiology and Surgery vol 8 no 6 pp 937ndash9442013

[40] R C Susil K Camphausen P Choyke et al ldquoSystem for pro-state brachytherapy and biopsy in a standard 15 TMRI scannerrdquoMagnetic Resonance in Medicine vol 52 no 3 pp 683ndash6872004

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Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


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Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



(skull fiducials) These markers are related to an MRI visu-alized intracranial target Depending on MRI slice thicknessand the size and shape of the markers this technique maycause some distortion and inaccuracy during MR imagingand identification of the markers [26] Another problem canbe that coordinates are calculated in 2D space on an MRIviewer screen while failing to consider 3D reconstructiondata or automatic target calculation Another potential issueis that the trajectory can be constrained to a straight verticalapproach with no angled or oblique targeting in the dorsal ortransverse planes available due to their need for more robustand complex calculations requiring greater information thanthat which is provided in 2D space Vertical trajectoriesmay restrict the surgeon to unhelpful and inappropriatetrajectories To solve these problems the currently existingLeskell system an arch-based stereotactic system for isocen-tric stereotaxy and 3D coordinate calculations relative tostereotactic frame integrated with fiducial markers couldbe implemented The Leskell system is already clinicallyavailable [27]While there has been some evidence to suggestthat free-hand techniques performed under MRI guidancemay be the equal or superior to stereotactic techniques[28 29] the surgeons working with the project expressed adesire for the use of a stereotactic frame thus causing thatavenue to be pursued Research has demonstrated that frame-based stereotactic systems are more accurate than framelesssystems thus a frame-based method was explored for theconstruction of the device [30]

This study aimed to integrate fiducial marker Z-framesinside the scanner with a modified Leskell stereotactic archused outside the magnetic field to enable arch-based isocen-tric stereotaxyThe request for the construction of this devicecame from the neurosurgical unit of theUniversity ofGeorgiaVeterinary School Following an MRI scan to locate braintumors and determine operability an open skull biopsy isperformed to obtain a sampleDesiring a less invasivemethodof surgery the developed system took inspiration fromprevious research and developed a low-cost system (in termsof additional costs to the existing procedure) to integratewith current operational procedures Given an average tumordiameter of 10mm to biopsy the surgeons requested less than3mm of error when targeting the center of the tumor

2 Materials and Methods

21 Overview Previous studies have been conductedto develop stereotactic cerebral interventions or MRI-compatible guidance frames including several whichimplement Z-frame approaches and 3-point head fixations[11ndash14 25ndash27 31ndash37] We combined both fields developingan MRI-guided device to assist veterinarians in executingminimally invasive brain biopsies and other cerebralprocedures

The design consists of a primary frame with two setsof attachments one for imaging and the other for needleplacement The framersquos cross-section is U-shaped in order tomaintain sufficient strength and stiffness contain a caninersquoshead and fit inside a standard MRI head coil

Table 1 Materials costs

Delrin $175Aluminum $20Stereotactic arch $600Contrast agent $10Assorted hardware $85Fabrication shop labor $500Total $1410

The Z-frame attachments contain tubes of Vitamin E oilacting as a localizing agent (to replace fiducials) to facilitateimage registration The geometry of the markers ensuresthat either a dorsal or transverse plane will contain 6 pointswhere the plane intersects the tubes A LabView program(National Instruments Austin Texas) was written to uselocation data (X Y and Z coordinates) from these points andcreate a mapping of the scannerrsquos coordinate system onto thecoordinate system of the frame

Following image acquisition the veterinarian determinedthe location of structure(s) to be targeted The relevantcoordinates from the scanner were mapped onto the framersquoscoordinate system using the developed transform Aftertransformation the relevant coordinates were fed into a sec-ond LabView program which performed reverse kinematicscalculations to generate the adjustments on the stereotacticarch which enable the point of a biopsy needle to arrive at thetarget point

After completing the necessary imaging the Z-frameattachments could be removed outside the MRI suite andreplaced with the stereotactic arch and its supports Onceattached the archwould be adjusted following the parametersestablished by the program providing a precise guide for theclinician to perform their procedures

By utilizing a simple frame a commonplace material fora contrast agent and a surplus stereotactic arch the cost ofmaterials for the project wasminimized An outline of pricingfor the materials used in the final system is shown in Table 1

22 Mechanical Design The body of the device (Figure 1(a))consists of four sets of components the primary frame theZ-frames the arch support attachments the stereotactic archand a 14-gauge biopsy needle The primary frame consistsof Delrin U-shaped end pieces with Delrin lateral supports(Figures 1(b) and 1(c))The supports constrain the attachmentpieces Zygomatic arch supports are located in the center ofthe lateral supports and consist of a rubber sheet over an ABSconcave support which is attached to a brass threaded rodA post to support the bite plate (both Delrin) is attached toone of the end piecesThe support structures are independentfrom the attachment pieces ensuring patients do not shiftduring transition between attachments These supports arenoninvasive eliminating the need for bone screws to supportfiducial markers or a stereotactic device The frame wasconstructed to conform to the space within the head coilused by the veterinary neurosurgeonThe frame secures headwidths between 7 and 20 cm The framersquos design could be


(a) Arch front view

NeedleStereotactic

archZ

Y


45∘

minus100sim100 mm

Headphantom


Z

X


20∘

60∘

minus80sim150mm










119911 =(119897 minus 2119889) ℎ

2119897

(1)




MRIscanning

plane

Z frame

1

l

2

3d

a

h

X998400


(X 998400 Y 998400

Z998400

Y998400

)

Z998400

00

X

Y

ZP (P1)

MRIscanner

Stereotacticframe

X998400

(X Y Z)



Phantom results


Phantom results


Phantom results





(e) Cadaver trial

AGAR















4 Conclusion



5 Future Work




Disclosures




References












































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a) Arch front view

NeedleStereotactic

archZ

Y


45∘

minus100sim100 mm

Headphantom


Z

X


20∘

60∘

minus80sim150mm










119911 =(119897 minus 2119889) ℎ

2119897

(1)




MRIscanning

plane

Z frame

1

l

2

3d

a

h

X998400


(X 998400 Y 998400

Z998400

Y998400

)

Z998400

00

X

Y

ZP (P1)

MRIscanner

Stereotacticframe

X998400

(X Y Z)



Phantom results


Phantom results


Phantom results





(e) Cadaver trial

AGAR















4 Conclusion



5 Future Work




Disclosures




References












































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











MRIscanning

plane

Z frame

1

l

2

3d

a

h

X998400


(X 998400 Y 998400

Z998400

Y998400

)

Z998400

00

X

Y

ZP (P1)

MRIscanner

Stereotacticframe

X998400

(X Y Z)



Phantom results


Phantom results


Phantom results





(e) Cadaver trial

AGAR















4 Conclusion



5 Future Work




Disclosures




References












































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation




















4 Conclusion



5 Future Work




Disclosures




References












































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Disclosures




References












































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









Documents

Research Article A Simple and Inexpensive Stereotactic ...downloads.hindawi.com/archive/2014/139535.pdfto develop stereotactic cerebral interventions or MRI-compatible guidance frames,