Upright, Weight-B e aring, Dynamic-Kinetic MRI of the Spine

Riv istu .l i Neuro rud iologio l 5: 333-356. 2002
Upright,Weight-Bearing,
Dynamic-KineticMRI of the Spine
pMRI/kMRI
J.R.JINKINS,J.S.DWORKIN*,C,A.GREEN*,J.NGREENHALGH'I,M. GIANNI+,M. GELBIEN*,
R.B.WOLF*.J.DAMADIANX.R.V DAMADIAN*
Medical C(llega of PennsrlvaniaHahnennun, Drexel Univercit"-,Philadelphia,Pennsylvania;
* Fdnr ('orDorotion.l\Ialville. Neu,York
Key rrordsrmagneticresonance
imagingspine.kineticspineimaging.uprightspineimaging.dyrramicspineimaging
SUMMARY - The purposeof this study was to demonstratethe generalutility of the first dedicated
magneticresonanceimaging (MRI) unit enabling upright, weight-bearingpositional evaluationof the
spinalcolumn (pMRI) during variousdynamic-kineticmaneuvers(kMRI) in patientswith degenerative
conditionsof the soine.
This study coniistedof a prospectiveanalysisof cervicaland lumbar imagingexaminations.
All studies were performed on a recently introduced whole body MRI system(Stand-Up"'MRI, Fonar Corp,
Melville, NY). The systemoperatesat 0.6T using an electromagnetwith a horizontalfield, transverseto
the longitudinalaxis of the patient'sbody.Dependingupon spinal level,all examinationswere acquired
with either a cervical or lumbar solenoidalradiofrequencyreceivercoil. This unit is configuredwith a
top/front-opendesign.incorporatinga patient-scanning
table with tilt, translationand elevationfunctions.
The unique motorized patient handling systemdevelopedfor the scannerallows for vertical (upright,
weight bearing) and horizontal (recumbent)positioningof all patients.The top/front-openconstruction
also allows dynamic-kineticflexion and extensionmaneuversof the spine.Patternsof bony and soft tissue changeoccurringamong recumbent(/MRI) and upright neutral positions(pMRI), and dynamic-kinetic acquisitions(kMRI) were sought.
Dependingon the specificunderlyingpathologicdegenerativecondition,significantalterationsobservedon pMRI and kMRI that were either more or lesspronouncedthan on rMRI included:fluctuating
anterior and posterior disc herniations,hypermobile spinal instability,central spinal canal and spinal
neural foramen stenosisand generalsagittalspinalcontour changes.No patient sufferedfrom feelingsof
claustrophobiathat resultedin terminationof the examination.
In conclusion,the potential relative beneficialaspectsof upright,weight-bearing(pMRI), dynamickinetic (kMRI) spinalimagingon this systemover that of recumbentMRI (rMRI) include:the revelation
of occult diseasedependenton true axial Ioading,the unmaskingof kinetic-dependent
disease,and the ability to scanthe patient in the position of clinicallyrelevantsignsand symptoms.This imagingunit also
demonstratedlow claustrophobicpotential and yielded relativelyhigh-resolutionimageswith little motion/chemical-shift
artifact.
Ricevutoil30.{)7.2002
333
Upright. WeightBearing, Drnani(Kitvtic
MRI of the Spine
Introduction
Magneticresonanceimaging(MRI) usingcommercial systemshas until the presentbeen limited
to acquiringscanswith patientsin the recumbent
position.It is a logicalobservationthat the human
condition is subjectto the effectsof gravity in positions other than that of recumbencv'.In addit i o n . i t i s c l e a rl h a t p a l i e n t se x p e r i e n i es i g n sa n d
symptomsin dynamicmaneuversof the spinalcolumn other than the recumbentone. For this reason,a new fully open MRI unit was configuredto
allow upright, partially upright, as well as recumbent imaging.This would at the sametime enable
partial or full weight bearingand simultaneouskinetic maneuversof the patient's whole body or
any body part. The obiective was to facilitate
imaging of the body in any position of normal
stress,acrossthe limits of rangeof motion, and importantly in the specificposition of the patient's
clinical syndrome.Under optimized conditions it
was hoped that a specific imaging abnormality
might be linked with the specificposition or kinetic maneuverthat reproducedthe clinical syndrome. In this way imaging findings could potentially be tied meaningfully to patient signs and
symptoms.Furthermore,it was anticipatedthat radiologicallyoccult but possiblyclinically relevant
weight bearing and/or kinetic dependentdisease
not visible on the recumbentexaminationwould
be unmaskedby the positional-dynamicimaging
technique:.
Material and Methods
This study consistedof a prospectiveanalysisof
cervicaland lumbar MRI examinations.
All examinations were performed on a recently introduced
full body MRI system (Stand-UprM MRI, Fonar
Corporation,Melville, NY) (figure 1). The system
operatesat 0.6T usingan electromagnet
with a horizontal field, transverseto the longitudinal axis of
the patient's body.
Table I Patienl Positionins rehted variationsof MRI
. RecumbentMRI: rMRI:
Supine,recumbentimaging
. PositionalMRI:2MRI:
lmaging in varyingangularpositions
of longitudinalaxis of body
. I(inetic MRI: kMRI:
Imagingduring dynamic-kineticsomatic
maneuvers(flexion.extension,rotation.
lateral bending)
334
LR. Jinkins
Depending upon spinal level, all examinations
were acquiredwith either a cervicalor lumbar solenoidalradiofrequencyreceivercoil.This MRI unit is configuredwith a top/front-opendesign,incorporating a patient-scanningtable with tilt,
translation and elevation functions.The unioue
M R I - c o m p a t i b l em. o t o r i z e dp a t i e n th a n d l i n gs y s tem developedfor the scannerallowsvertical (upright, weight bearing)and horizontal(recumbent)
positioningof all patients.The top/front-openconstruction also allows dynamic-kineticflexion and
extensionmaneuversof the spine.
Sagittal lumbar/cervicalT1- (TR: 680, TE: 17,
NEX: 3, ETL: 3) weighted fast spin echo imaging
(Tl FSEWI), sagittal lumbar/cervicalT2- (4000,
140-160,2.13-15)weightedfast spin echo imaging
(T2FSEWI), axial lumbar Tl WI (600, 20, 2) or
Tl FSEWI (800,17,3, 3), axial cervicalgradientrecalled echo T2*-weighted (620-730, 22, 2)
(T2*GREWI) were performed in all cervical/lumbar studies,respectively.In all cases,recumbent
neutral, upright neutral, upright flexion, and upright extensionimaging was performed.The patients were seatedfor the upright cervicalexaminationsand for the neutral upright lumbar acquisitions,and were placedin the standingposition for
the lumbar kinetic studies.
Patternsof bony and soft tissuechangeoccurring among recumbent neutral (rMRI) and upright neutral positions (pMRI), and dynamic-kinetic acquisitions(kMRI: upright flexion-extension) were sought(table 1). Specifically,
degenerative spinal diseaseincluding focal intervertebral
disc herniations,spinal stenosisinvolving the central spinal canal and spinal neural foramina,and
hypermobile spinal instability were compared to
other visibly normal segmental spinal levels among the rMRI, the pMRI and kMRI acquisitions
(tables2-7).
Focal disc herniationswere defined as localized
protrusionsof intervertebraldiscmaterial that encompassedlessthat 25% of the total disc periphery in the axial plane; central spinal stenosiswas
defined as generalizednarrowing of the central
spinal canal in the axial and/or sagittalplane relative to that of other spinal levels;spinal neural
foramen narrowing was defined as general narrowing of the neural foramina as determined from
sagittal acquisitionsrelative to that of other segmental spinallevels;and hypermobilespinalinstability was defined as relativemobility betweenadjacent spinalsegmentsas comparedto other spinal
levelsthat in turn demonstratedvirtually no inter-
Rivisurdi Neuroratliologin
15: 333-356.
2tfr2
segmentalmotion. Generally speaking,degenerative disc diseasewas defined as both intrinsic discal MRI signallossas well as morphologicalalteration to include a reduction in suoeroinferiordimensionaldisc spaceheight.
Alterations in sagittal spinal curvature were
also noted between the neutral rMRI and oMRI
a c q u i s i t i o n(st a b l e 8 ) . F i n a l l y n
. o t a t i o nw a s m a d e
as to whether or not the patient was referred in
part becauseof an inability to undergo a prior
MRI due to subjectivefeelingsof claustrophobia
attemptedin a "closed" MRI unit.
The neutral upright imaging studies (neutralpMRI) demonstratedthe assumptionby the patient of the true postural sagittal lumbar cervical
or lumbar lordotic spinal curvatureexistingin the
patient at the time of the MRI examination,a feature that was partially or completely lost on the
neutral recumbent examination (rMRI) (figures
2,3). In other words,this relative postural sagittal
spinal curvature correction phenomenon was manifested by a change from a straight or even reversed lordotic curvature on rMRI to a more lordotic one on pMRI. Increasingseverity of focal
posterior disc herniation on the neutral-pMRl
comparedto the rMRI was noted (figure 3), and
was yet worse in degreeon extension-kMRl (figure 2); these posterior disc herniationswere less
severe on flexion-kMRI maneuvers as comoared
to all other acquisitions(figure 4). Absoluie de
novo appearance of disc herniation on neutralpMRI was identified on extension-kMRI acquisitions in some casesas comparedto rMRI (figure
2). A reduction of intervertebral disc height was
typically noted at levelsof disc degeneration(fig-
Table 2 Dynamic spinal olterations
Table 4 Types of intersegmentalspinal motion
Results
. Bony Structures:
. Eumobility:normal motion
Intersegmental Relationships
Rangeof Motion
Spinal Contour
. lnteryertebral Discs:
- Disc Height
- Disc Margin
. Hypermobility: increasedmotion in the
X, Y, Z planes
. HvDomobilitv:decreasedmotion
Table 5 Positional lluclualion in spinal ligaments and discs
(p/kMRI)
. Ligaments:
Ligamentotactic Ef fects
Ligamentopathic Effects
. PerispinalMuscles
. NeuralTissue:
Li gamentotactic effects
Intact spinal ligamentous structures
Spinal Cord
Spinal Nerye Roots
(ventral and dorsal)
Cauda Equina
Table 3 "Telescoping"of spinal column in degenerativedisease
. Intersegmenlal settling:
- Disc collapse
- Posterior spinal facet (zygapophyseal)
joint subluxation
- Contained bulging peripheral disc material
- Inclusion of disc material within disc
spacewhen ligaments are tensed
- Further protrusion of disc material into
perispinal spacewhen ligaments are relaxed
Table 6 Dysfunclional intersegment.l molion (DlM)
. DIM is a form of intersegmentalhypermobility
. Annulusfibrosusredundancy
. Ligamentous redundancy
. Meningeal redundancy
. Neural redundancy
. DIM engendersgeneralized accelerated
intersegmentaldegeneration
. Mechanism of acceleratedspinal degeneration:
chronic. reDetitive autotrauma
335
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Rivista di Neulo rudiolosia 15: 333-356. 2002
Figure 2 Sagittalcervicalspinal curvaturecorrection:unmaskingof central spinal stenosis;occult herniatedintervertebral disc (all imagesin samepatient):A) recumbentmidline sagittalT2-weightedfast spin echo MRI (iMRI) showsstraighteningand partial reversal
of the sagittalspinal curvature of the cervicalspine (double headedarrow). Minor posterior disc bulges/protrusionsare presentat multiple levels,but the spinal cord (asterisk) is not compressed.B) Upright-neutral midline sagittal T2-weighted fast spin echo MRI
(pMRI) showspartial resioration of the true sagittalpostural cervical curvature upon neutral-upright positioning (curved line). Note
the relative increasein the posterior disc protrusion at the C5-6level (arrowhead) and encroachmeoton the spinalcord (aste sk) as
comparedto the recumbentimage (A). C) Recumbentaxial T2*-weighted gradient recalledecho MRI (rMRI) through the C4-5 level
showspatent neural foramina bilaterally (single headedarrows),and mild stenosisof the central spinal canal (double headedarrow).
C) Upright-neutral axial T2*-weighted gradient recalled echo MRI (pMRI) through the C4-5 level showsbilateral narrowing of the
neural foramina (singleheadedarrows).Note also the narowing of the central spinal canal (double-headedarrows) relative to the recumbent study (D), and the compressionof the underlying spinal cord [i.e.,relative anteroposteriorflattening of the spinal cord as
comparedto the recumbent image (D)].
337
Up rillht, Weight-B?arint!, D|D(Dtit-Kineti( lr,lRI of thc Spi r
Figure: E)Uprighl cxtensionnlidlincsa-qiltal
T2-wciShtcdf|sl \pin echo l\,1Rl(exrcnsionkMRI) sh()lrsfurthcr posleriorpfolrusion
ol the inlervcrtcbraldiscsat multiplelevels(arrows)and anleriorinlbldinqol lhc poslcrior\pinal lilLamenls
(ar;()whcldsj.r.esulting
in overallworseningof lhc stcnosisol the ccntralspinalcanal.Nole thc imtingemcnl(i.e..compressidn)
of the untlerlvingspinalcorl
(asleJr.5kJ_bv
lhcsccncroaching
spinalsoll lissueelcmcnls.F') Recumbcnla\iillT2:' rciehred gr.adient
r.ecallcd
ccho MRI ifMRI) al
lhc C5 C6 disc level showsposleriorparadiscal
osleophveli)rmnlion(arrowhcad)exte-nding
into thc xnlerior aspeclof the ccntral
spinll_canal.
Nolc thal the ceNicalspinalcord is alrophic.hut lherc is a rinl ol CSF hvpcrintcnsit!enlirelvsurroundinglhe cord.C)
Uprighl cxtcnsionaxialT2:'rcighted gradienlrecalledechoMRI (exlensionkMRI) rerealinqlexicnsion,iellted)tbcalDosteri)rclisc
hernialion(arrow).Nole thc o\erall increased
rtenosisol lhe ccnlralspintl canal.rn.tthe c,,rrrfrrr'\\r,,n-tndcnrrri,'n
0l lhe underlying
cervicalsoinalcord (aslerisk
).
ures 3.4). Increasing severitv of central spinal
canalstenosiswas identifiedon neutral-oMRI and
o n c x t c n s i o n - k M R Ia c q u i s i l i o n sa.s c o m p a r c dt o
rMRI, and was overall ntost severeon extension
and leastsevereon flexion-kMRI acquisitions(figures 2.5). Similarly.increasingscveritv of spinal
neural foramcn stenosiswas identifiedon neutralpMRl (figures3). as comparedto rMRI. and was
overall most scvereon extcnsionand lcast severe
on flexion-kMRl acquisitions(figure 6). Increasing centralspinalcanalnarrowingwith spinalcord
compressionon extcnsion-kMRIwas identificd in
somecervicalexaminations(figure 2) ascompared
to recumbent IMRI. neutral-pMRI and f'lexionk M R I m a n e u v e r sT.i a n s l a t i o n asl a s i t t a lo l a n e i n l c r s e g m c n t ahly p e r m o b i l i t w
y a , i d c n t i f i c da r s o m c
levels associatedwith degenerativcdisk discase
and minor anterolisthesis
of a dcqenerativcnature
33u
(figurcs 5.7). Postoperativespinal stability was identitied acrosslevelsof prior surgicalfusion (figure 8). No examinationwas uninterpretablebased
on paticnt motion during anv portion of the MRI
acquisitions.No patient was unable to completc
t h e c n t i r e e x a m i n a t i o nd u e t o s u b j e c t i v el e e l i n g s
of claustrophobia.
Discussion
C o n v e n t i o n arle c u m b e nM
t RI. or rMRI. isobviously inadequatetheoreticallvtbr a completc and
thorough evaluationof the spinal column and its
contents.The biomechanicsol human condition
includesboth wcight bearing body positioning.or
/ ) M R l . a s u c l l a s c o m p l e xk i n c t i cm a n e u r e r so.r
k M R I i n t h r e c d i m e n s i o n s ' "T.h e p r e s e n tM R I u nit was intended to addrcssthese considerations.
T
T
r r ( \ l l i k r l \ t \ . t l l r \ r \ S L ' | r r rf l r r r r c ( ' l r . r d rI t r r ] | t ' l r r r l J \ r h r L l ! f r r - , r r . , \L l n , r L , r l r i l r u l .1 { i1 h r \l r h r r r ( ) r ) r . l l , ' r l
.i.19
Upright, Weight-Bearing. Dvnunic-Kinetic MRI oJ the Spint
J.R. Jinkins
i
T1-weishted spinechoMRt (rMRI)ontheparient
s lerrsideshows
narowinsor rhe
lL)/r
P,:f"l.-1]
l,ltg'lcfr,"1
I splnall:::l?:ll]:l!lii"neuralIoramen(dashed
arrow).asa.resultof^fast
posterior
protrusion,
disc
interveriebral
discspacenarrowingand iaradiscal o'leoFhvtclurmation-F) Uprighl-neulralmidlin( parn;acitralI I.weighredfasrsplp ..1lo vnripMftii""
'ri" "uii.n, . t"'r ,,.t.
narro$rngol,allol rhs \pjnal ncuratforJminatsotidarro\as).
inctudrnpthtrL5rSI tevettda.fiedarrolr) (com_
:"^::r.i...T,Il-.].ry1:ll'r/ed
parewllh.recumDent
examlniltlon.
t) Al-somepoint in this stenolicprocess.
the exilingneurovascular
bundle(asterisk)will undcrgo
compressionand may becomesvmptomatic.
Both occult weight bearing disease(e.g.,focal intervertebraldisc herniations,spinalstenosis,
thecal
sacvolumetricchange),and kinetic dependentdisease(e.g..disc herniations.spinal stenosis.hypermobile instability) of a degenerativenature 7rr
were unmaskedby the p/kMRI technique.In additlon, a true assessment
of the patient'ssagittalpostural spinal lordotic curvature was possible on
n e u t r a lu p r i g h tp M R I . r h e r e b ye n a b l i n gb e r r e re valuationof whetherthe lossof curvaturewas due
to patient positioning(i.e.,rMRI) or as a probable
r e s u l to f s o m a t i cp e r i s p i n am
l usculag
r u r r d i n go r
spasm (figures 2,3). Axial loading and dvnamic
flexion-exlen5ionstudies by othir reseirchers
have borne thesevaried observationsout:{rt.
Simple upright or upright pMRI, showeda phen o m e n o nh e r e l e r m e d" t e l e s c o p i n gw" h e r e b yt h e
levelsof generalizedintersegmentalspinaldegeneration showeda collapseof the spine into iiself
(figure 4) ".
Consequentredundancyof the discal,ligamentous and meningealtissuesof the spineresultedin
340
increaseddegreesof central canal and lateral recessspinal stenosis,while craniocaudalshortenins
o f t h e s p i n ea s s o c i a t erd. irt h t e l e s c o p i ncga u s e di n creaseddegreesof neural foramen stenosis(figure
3 ) . O n o c c a s i o nt .h e d e g r e eo f f r a n k p o s t e r i o r t i s c
h e r n i a t i o nw a ss e e nt o e n l a r g ew i t h u p r i g h tp M R I
( l i g u r e3 ) .T h i s l a r t e rf i n d i n ew o u l d s e e mL o b e a n
important observation,obviously improving the
qualitativenature of the analysisin relevantcases
of disc herniation.Finally.upright-neutralimaging
frequently showed increasingdegreesof sagittal
plane anterolisthesis,
both in degenerativespondylolisthesis and in some cases of soondvlolvtic
spondylolih
s te si s
Upright extension kMRI tended to show
greater degreesof central canal and neural forarnen stenosis,while flexion kMRI revealeda lessening or complete resolutionof the same central
canal and neural foramen narrowing (figures5.6).
Thesephenomenawere only observedat levelsof
disc degeneration(i.e., both disc desiccationand
disc spacenarrowing)'''.. In exceptionalcases,de
L'pi i(ht. l4'd!:ht- B( ri !1,D\'tluttliL Ki t,ti( lllRI t)l th( Spint:
Figurc5 Worscnine-reducing
ccnlral\pinal canalslcnosison d!nrmic-kineticMRI (kMRI): minor lranslationalinlcrscgmcntalhv,
pcrnrobilcinstabilitvon dvnamic-kinctic
M R | ( k M R I ) A ) RrcurirhcrrLmr.llinc'agiltalT2-weighlcdlaslsli11echoM R I ( ri,l RI ) shows
'12mild. generaliredspondvlosis
and minor gcncralircdnarr()$inqol lhe centrillspinalcanal.B) t-rprighlncutral midlinesxgitlal
\\'eightcdfastspin ccho MRI (pMRI) sh()wsvcrv nlinor \vorsenine
of lhc ccntralspinalcanalstcnosisinleriorlv(+) relaltveto the rc
crmbenl i age (A). Nolc lhc assumplionby lhe pLllicntol lhc lruc posluralsagiltallordoliccurvillurcof the lumbosacral
spiners
comparcdlo the rccumbcnlcxrminalion.
/l(/v(,posteriordisc herniationswcrc revealedonlv
on upright-extensionkMRI (figure 2). When prescnt in the cervical spine. such casesinvariablv
showedcompressionof the undcrlyingspinalcord.
Overall.this was fclt to be one ol the most important observationsnoted in this study.lnterestinglv.
some of the posteriordisc herniationsbecameless
severewhen upright flexion kMRI was performcd
(figurc 4).
This would seem to bc worthy of preoperative
note to thoscsurgeonsthat operateon the spinc in
positionsof llexion. Presumablythis phcnomenon
is caused lx a liganrcntotucticeffact: the intact
flbers ol the anterior and posterior longitudinal
ligamentsand the intact peripheralannular fibcrs
have effectsupon the underlyingdisc material.alternatelvallowing morc disc protrusionwhen lax.
and lcssprotrusionwhen taught.It was notcd that
all casesof fluctuatingintervcrlcbral disc herniation had MRI signallosscompatiblewith desiccation as well as intervertebraldisc spaceheight rcduction"".
342
Thesc disc findings wcrc also invariably true in
cascsof sagittal("x") plane hypermobilespinalins t a b i l i t y r " ' .I t w a s p o s s i b l et o j u d g e e v e n m i n o r
degreesof translationalhypermobilespinal instability (e.g..mobile antero-or retrolisthesis)grossly
as well as by using direct region of intcrcst mcasurements(figures5.7).The kMRI techniqueobviouslv does not suffer from the effectsof magnification and patient positioning crrors potentially
inhcrcnt in conventional radiographic dynamic
flexion-extensionstudies traditionally uscd in
these circumstances.
Thcsc instancesof intersegm e n t a lh y p c r m o b i l i t vs c c m i n p a r t t o b e a m a n i festationof spinal liguntentoputhv'".As the princ i p a l r o l e so f s p i n a ll i g a m e n t sa r e t o s t a b i l i z ct h c
segmentsof the spineand also to limit the rangeof
motion that the spinal segmentscan traverse.degenerativestretchingor frank rupture of theseligamcnts will predictablyallow some degreeof intersegmentalh)'permobilitv'""r.
Other alterationsin the intervcrtcbraldiscsand
posterior spinal facetjoints will have either posi-
RivistuIi Net!ft)ruIit
lognr 15:3.3.3-356.2002
-f2
Figure5 C) U priSht-exlension
midlincsagittal wcighledIas(spincchoMR | (kMRI)rcvcalssevereworseningofthecenlrtlspinal
c a n a l s t e n o si ni st h e l o w e rl u m b a ra r e a( a r r o w sL: ' l - L 5 . L 5 S l ) . T h i s r e s u l l s f r o m a c o m b i n { l i o n o f f a c l o r s . i n c l u d i ; e r e d u n d a n c v o f t h e
I h e c asl a ca n d s p i n alli g a m c n las n d i n c r e a s i rpuo s t e r i opr r o l f u s i o nosf t h c i n t e r \ c r t . b r i ldl i \ c \ . r tL l - i i | n L i L 5 S l . D ) U p r i g h t - f l e x i o n
midlinesag.illalf2-weightedfitstspinccho MRI (kMRI) demonstrates
completereduclionof lhc posrcriordiscprotrusiiniar the L.l5 and L5_Sllcvels.lnd resolutionof the ccnlralspinalcanalslcnosisa1thcselurnbarscqnrcnts
(c;parc with Cj. Also note that there
is nlinor anierolislhesis
at Ihe L2-3and L:l 5 levelsascomparedto the neutralcxaminali()ns
(A.B). indicatingrssociatcdmild translational interscqmcnlal
hypertnobileinstabilityal thcscIcvels.
tive (i.e..hypermobility)or negative(i.e..hypomobility) effectsupon intersegmentalmotion^.o..
Also noted at levelsof disc degenerationwas a
sagittalplane hypermobile"rocking" of the vertebrae in relationshipto each other (figurcs 4.6),'".
Observation of the opposed adjacent vertebral
endplatesin such casesshowed them to move in
relationshipto each other to a much greatcr de'l'able
7 Translationalhvpelmobile instabilit.l of the spinal cot-
L i ganten top ath i c alter ations'.
ligamentousstretching/rupture
Mobile translationalantero-and retrolisthesis
(X-plane)
- Mobilc latero- and roblisthesis(Z and Y-planes)
Dynamic overextensionof spinalrange(s)ofmotion
(X. Y. Z planes)
Tablc tl Tvpesof upright postural spinal curvature
. Normal curvature
Cervical:lordotic
- l horacic:kyphotic
- Lumbar: lordotic
Exaggeratedcurvature
- Hvperlordosis
- Hyperkyphosis
. Lossof sagittalspinalcurvature
(straightspine)
- Hl,polordosis
- Hvpokvphosis
. Coronal plane scoliosis
(directionof convexcurve)
- Leftward:levoscoliosis
- Rightward:dextroscoliosis
- Serpentine:serpentinescoliosis
343
Upright.W(ightBcurittg,Drnontic Kitk|.ti(MRI ol tll.,spittr
F i g u r e6 E f t e c l s o f d t n a n l i c k i n c l i c n a n c u \ c r s ( k M R l ) o n s p i nn cnul r a li ) ( r n r i n i a
r t l c v c l so f d c q c n e [ r t c tdl i s ct l i s c . r si lcn dt h c o r c t i cal]iga.menlous.laxiIv(i'e'.Iigamcntopl1ht'):'dvsfunc1i01alin1crstgmcnll|]molir'nA)Rccunrben1plr1tsllgiltalT llN
cho MRI (rMRI) \hows intcNerrcbraldiscdeqcncralionlll lbc LS-Sl levcl (rsrcrisk).N(ne thc ill nariorvinqof thi-neural
foramcn
( n r r o \ \ ' ) a t 1 h i s l e v c ] ( i - e ' ' m i o o r t ) r a m i n a l \ l e n ( x i ' . - a n d t h c n c | r p a r i l |.calcscu\ o l l b c v c r 1 c b r a I e n d
j:l..i l".P"il':Cl!ll I l: $ cighttd frst rp114.1,uMRI (k MRI ) re\ealsfurlhcr nrrrowin{ of rhc neuratrul^ni.n lii iili r i"ttuo r r"r"l t \ c r , , r h <r ( c u m h r l | rt m J s r/ \ ) . \ . , t , . t h ( u p c n i n r , , t h LI.r t c r r r , r , , \ l ( ( r . , rr h , . . l r . i . l : r r er J , , u h l uh c : r J r . L i . r r rr,.,($1 , , \ r n p ,l,hr ( p u .
l " , " j l ' , ; l T ; l ] i .ucmun\lrrte\
1 l . . 1 , ] . i : j ] : ] ,'p!nrns
) . : l " : . . ] ','. 'l] .thc
" ' : .neural
'lothcrecumbcn1ina8c(A).(.)t:prig|rl-llcxi()nllrasaeil1al'I.2.wcigh F
forrnrenal L5-sl (rrro$). lhc openin1]
ot'rhe posrorioraspeit of the disc space
)lI:"!l':'11,)
jl:l,":.j:]]y:y':',I:,:l').c-|oS|n!'.,l,thci|nteriorlspectollhddi\cs
(llne\l tlgure\ tl. L lllu\llirl,rLl\'\i n(ttr,nalinlcrsegmenlal
moti()nin rddition to thc dvnamicchan{esin thc sizcol lhc neuralroranrcnr1'le!e]SoldiscdcgcncIiIlionandlbeorcticil|lig:|n]entous|l\il\'(i'c'.ligilmen1oP
somcwhalenlafqedt\ c(nlparedt() lhc recumbcntirnd the c\lensi(r;inlue\lA.B).
relr(Jl lrPrn1(nlrru\
lr\rl\ ( I ir" lrP,irn!ntoPitlht
) A) Reclmbcntmidlinesa!irtalT l-ncightcdilsl spinccho NIRI (rMRI) snowsnrnor.
lc\\,lnirn qrruc l
\p'trltl\lt' ll\lhests
ll the L1-5 level (lrrowhcad). lhe pars interarticuliiris
was inlact on hoih siclcslt rhis
..rnlcrr"r
\ , ' l c t h ( rrel.llionship
level
l < \ c l . Nole-the
c l i l L l o n s h l Oh
helwcen
e l r \ c u I lhe
l h e anleriorsurluces
ol the L-l und L-svertcbfalb(rdiesiclashcdlincsl.Bl Upriqhi,neutratmid,
line sagittalr I'wciShrcdi.st spinechoM R,l( FM Rl ) rrr eirtsnrin,'r r\,)r\unrn{.t rl,e anr.ti,,. riif .iiil ,;; i:i
l. ,,. ",,,n
p a r c dl o l h e r c c u m b e ndt x a n t i D a l i oCn). L p r i q h t - l l c r r , ,mni J l t r \ . r u I l T l - \ \ E i q b t c c l i a s l s p i n c c h o U n t lill^;li;j';;;.,,"
tVntiaentonstrurcstu.1herantcrior5ub]ux:r1ionolL-lrlnI,5in||c\I('n(LllshcdJrr.lu)..rst.rnr0lrredto.ligu|esA.E|.'Ihisdcnltlnslialcil1
Ine|<|JI|nn\hlfhCl\\i'\'nlll(i||)l('|l,n.url'|(.'.,,llllfI|.lllLlIi!(lt(hr:||h,rJrc.lLl'rshtJ
recumbenlilnacc(A).
344
Ri I i stu I i N eutu)tul iolr,qi( I 5r -.133-356.
2(X)2
Figure lJ Postoperaliveinlerseqmentalfusi()nstability (four )ears status-postclinicallv successlulinterbody bone grall lusion).A) Upriqht ncutralmidlincsagittalTl wcightcdfastspin echo MRI (pMRI) showsthe surgicaliusionat C5-C6(asterisk):
autologousbony
dowels\vereusedibr thc oriSinalfusionperlbrmed,lvcarsprior to the currentexaminalion.
Notc thc normalbony iniersegmental
vertebralalisnmcntand normaluprightposturalsagiltalIordoticcurvalure.B) Lipright-neutral
midlinesagitlalT2-weighted
taslspinecho
MRI (pMRI) aSainshowsthc interscgmcntal
fusion(asterisk).
Note the goodspatialdimensions
ofthe CSFsurrounding
the spinalcord.
C) Uprighl-nexion(arro* ) midlinesaSi[a]T2-weightedfastspinccho MRI (kMRI) showsno intcrsegmenral
slippasear.suprrjacenr
to. or subjaccntto thc surgicallvfuscdlcvel (solidline).Note the maintenance
oi the anleroposterjor
dimensionof the centralspinal
(arrow)midlinesagiltalT2weightedfasrspin ccho MRI (kMRI) againrevcalsno inlerseqmenlal
canal.D) Uprighl-extension
hyper,
mobilc instability(i.c..no intcrscgmental
mobilit),:solidline) or cenlralspinalcanalcompromisea1any level.
gree than is observedat levelswith normal intervertebraldiscsasjudged by MRI (figures4.6).This
is herc termed as tlvs.funttionul
inter:iegmental
no/ldr (DIM).
The significanceof DIM is the theoreticalpossibility that such pathologicvertebral motion mav
engendergencralizedacceleratedintersegmental
degenerationdue to the effects of micro-autotrauma over long periodsof time.The self-protecting spinal mechanismsinherent in the normal intervertebraldiscsand intact spinal ligamentsare
l a c k i n gi n s u c hc a s e sp. e r h a p si n i t i a t i n ga p r o g r e s sive degenerativecascadeof degeneraldjve
outotrantatizing hypermobilit1t.
-t4)
Upright, WeighbBeatin+, Dynanic-Kinetic
MRI ofthe Spine
J.R.linkins
intersegmental-hypermobileinstability al segmenrabove fusion.5 years fo owing bitaleral fusion (pedicte
l]9:::
:- j,.:l:p:1"-'11:
screws.and
rods extenchng
belweenL4-Sl) and bilalerallamineclomyat the Lzt-SllevetsA) Recumbentmiblinesagittal T I -w;ighted
fast sPin echo.MRI (rMRl) showsbilateral lamineclomy extending-from L,l--SI (arrowheais). The patient aiio haf 6il"teral pjdicl.
screwsand rods extendlS-from and to lhe sameIevels{ not shown): No melallic arlifact is presentUe'cau=.rtre suieiirl ;atenals were
composedof litanium.-B)sagirtal-uprighl-siuing
(i.e..parrialflexionrmidrineT2-weighred
tist spinecho MRI (p,,t'MEijoemonstrates
marxeo antenor sllp ot lhe LJ vertebralbody upon the L4 verlebra (dashedarrows).Also note the resullant mari<edstenosisof the central sPinalcanalat the-L3-4 level (solid arrow), and resultantencroachmentof the-bonystructuresof the spine upon itre cauoaequlna
(courtesyof M. Rose.M.D).
Table g Combincd effectsofspinal degenerrtion with telescoD.
ing. diskopaahy.ligrmentopalht hypermobiteiltstobitity.& Dli4
. Spinal Stenosis[central spinal canal, lateral
recesses(subarticular zone), neural foramina]
Table 10 Clinicoradiologicrelevrnce ofpl&MRI
. Patientcareconsiderations
- Improvementof imagingsensitivity
over that of recumbentexaminations
. SpinalCord/NerveCompression
. Medicolegal aspects
- Revelation of diagnosesmissed
. SomaticNerveEndins Irritation
on recumbent examinations
. Worker'scompensation
. Neuromuscular/Ligamentous
Autotrauma
- Revelationof occultpathologynot found
on recumbentexaminations
. Related Patient Signs/Symptoms
346
. Economic factors
l l t \ ! \ t t tt l i \ t I t , ) n k l i , r r , ! / , / l 5 l r l
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f r r \ \ ( l l r r l , , 1l l r r r I i ! l u r r l r l i . . h r f l r L r r r o rrr( L ' ! r l ! \ \ t i l \ l
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l.+8
Rivistadi Neuroraliulogial5: 333.350.2002
\ Svndroms
y,ll; :!lll*l^*:" of - Lhermine
. or ctecrrical
!ensarions
exrcndrng
do\rn horhupperexlremrI9",::]l "T::.li]:-p-f
rne
cervrcal.sprne
A) Recumb(nr
midlinesagittal
j]:: :ry:,'1.1.'_:l
T2-weighred
spinechoMRI { rMRa showsrhenoimatappear:l
ance.ortne ccrvlcal \plnal cord (black dstcrlsk) dnd lhe l\ro lerel poqreriordisc prutrusionq al the C5
Co and C6-C7 lcrels (wl.iii( as\agrrral
T2-wcrshred..!prn
echoMRt rkMirr demonsrrares
anreriordispraccmenr
of rhc spin.rl
l.^:':\'.]:^B"lYt:ql'.::"llrl T9].:
::;:'''ii'i'ifJfiil*fft
"ililF:fii:':Jil"lL'"1:Ti:;l"lTJ::l,"Ji,jii,:li!"y5l5l#:!::"Ti:i
ii(5redsymptums
conri:'renr
wirhLhcrmirre
. slndromc
duringthisftexion
"iuoy.Tri""i"d'y;;;. r;; ;;i;;i,;i ;;;i;;i,'..
dynamic-kinetic
MRI (kMRI) in its abilityto correlatea speciific
imagingacquiiitionwih i sp*iiic crii,lc"L.i;;j;;*'
nn,ur.o,
Figurel4-F,atsuppression
(STIR:shorttau inversionrecovery)lechnique.A)Recumbenr
midlinesagrrral
Tl-weighlediastsprnecho
MRI (rMRI) showsnormalvertebralmarow.epiduralandperivertebialfat'(aslerisks).B) n.."-u!"i .iolir" ,""giilirz-i,.igl,,"a
'gl:ilfp*qsionrsrtR) showq
excelenrrarsupp,e.*ion
eq,"riya"r.-;'ri;;;"i;;l;;;;
rtargeisrcr_
l:;:,.oJ,i:.1:Yl,,,lylll_lil
lsKs,L\olelnegooo\lsuallTalton
(smallaslerisk)
ol lheconusmedulari<
andthen(rverootsofthe caudaequina1arr5ws1.
349
Uprillht, Weight-Beuring,DvnanticKinetic M RI rr.fthe Spi ?
(arrow)midlincsagit
Figure15 Ultra-fastimagingtechniques
for applicaiionwith spinalstressmaneuvers:kMRL
A) Uprighr-flexion
(arrow)midline
talT2-weighteddriven-equilibrium
MRI (kMRI) demonstrates
normalspinalcolumnmobility.B) Upright-cxtension
sagittalT2-weighted
driven-equilibrium
MRI (kMRI) againshowsnormalspinalcolumnmobilitlr.Nole thal thereis someIncrease
rn
the posteriordiscprotrusionsat multiplelevels.increasedintbldingof the posteriorspinalligamcntousstruclurcs.
and consonantmi
nor. noncompressive
nanowing of the anteroposterior
dimcnsionof the spinalcanal.Thesesingle-slice.
driven-equilibrium
images
wcre eachacquiredin thirty-fourseconds(time:l7 secx 2 NEX = 34 sec).Thistechniqucwill likcly provc to be importantin casesof
criticalstenosis
of the centralspinalcanalundcrconditionsof hvpermobileinslabilitv.
wherethe spinalcord may be in dangerof compressionduringstressmaneuvers-The
d ven equilibriumsequences
shouldallowverv brief imaginSacquisitions
and cnablcdynamic
kineticpatientpositionsto be sa[elyassumedfbr ver! shortpcriodsof timc requiredby this technique.
Figure 16 Telescoping
ol the spinalcolumnassociatcd
with dcgcnerative
A) Diagramof recumbentspineshowingdediscdisease.
generativcdiscdiseascat thc L4 L5 lcvel.and degeneralion
ol the interspinous
ligamcntat this samelcvcl (scrraledlines).Notc thc
bulgingol the degenerated
intervertebral
discal L,l L5 rcsultingin mild narrowingof the centralspinalcanal(doubleheadedarrow).
B) Diagramof Ihe uprighl-neulrallumbosacral
gravityrelated(largesolidarrow) narrowingof the l-4-t-5interspinedemonstrating
vertebraldiscspace(dashedarrow) and intcrspinous
space(smallsolidarrow)as comparedto the recumbentimagcA. togcthcrwith
redundancy
of th€ soft tissuesborderingupon the centralspinalcanal.This telescoping
of thc spinalcolumnmav resultin varyingde,
greesoI worseningslenosisof the centra]spinalcanal(doublchcadedarrow).
350
Rir istadi Neurctudiolo gia 15l.333-356.2OO2
B
c
Ftgorc 17
.Li8(nenkrtadic a d liSanenbparri. cffects.A) Diagram of the recumbenl spine sho\ring degenerationof the L4-L-5inter!ertchralJi\c.andinter\prnous
ligament(serratedlines).Noteihe mild peripheralbulgingof the iniervirtebraldiscat L4-L5.and the
mrnornarro\rIng()l the ccntral\pinal cirnal(doubleheadedarrow).Also notethe near-pa;lletpositionof the intervertebral
end plates
on eithcr5iJ( of the L4-5JIsc.B) Diagramof the upright-flexed
(solidcurvedarrow)iumbosicralspineshowsan increasein the anlerlor dlscprotrullon-(ofen curvedrrrow) relatedto laxityof the anteriorlongitudinalligamentand anteriorfibersof the annulusfibro\u\. l(\enlnP ol
poslcriordr\c prolrusir,nbulgecau.e.ihy rcnsionrrf thi posterioilongitudinalligamenland rrmaintngintacl
,lhc
fro\l(rror lrher\ ol the annulusfihrosu\ sllayingol Ihe \pinou5procc\\cst5olidstraitshtarrowst.hypcrcipansionol the inter\pinou\
tpacc {\lippllng,.openingup uf lhe po\t(rior aspectol the discspace(aqteri.l.,lashe'd
curv(d arro;s). and narrowinqol tnr anrenor
aqp(ctol thcd,\c space(straightdashedarrows).Nole.thatthe centralspinalcanalbecomes
wider (doubleheadedarr<iw)ascompared
lo the neutralpositionor extensionmaneuver(A.C).AIso note thal the opposedvertebralendplates
on eithersidcof the degenJrated
L4-5 inlcrvertebral disc assumean anleriorly directed wedgc-configuration(dysfunctionalintirsegmental motion: C). C) Diagram of
ihe uprighl-extended.lumbosacral
spinc shows.anincreasein thc posterior disc protrusion (open sriaight arrow) relat;d t; laxit:yof the
poslcrior longitudinal ligament and anterior fibers of th€ annului fibrosus.lesseningof the ;nterior ;isc protrusion causedbv tension
ol thr anleriorlon8iludinalligamentand remcrningintacl anleriorliber\ of the a-nnulus
lihrosus.tollrsionof thc spinousprocesses
(.olid stratghlarrows,r.
opcntngup ot th( anrcriordiscspacela!tcnsk.dcshed\lralghl arrow.). and narrowingof the'poster
ior a.pecl
ot thc dllc.sprce.(da\hed
cur\,edarrows).Note thal the centralspinalcanalbecomc.s
narrower(doubleheadeAarrow)'ascourparcuro
the neutral position or flexion maneuver(A.B). Also note thal the opposedvertebral endplateson either side of the degeneratedL45 interyertebraldisc assume_
a posteriorly directed wcdge cr:nfiguralion.This lattcr observition indicatesdysfunctionali;tersegmental
motion at this level of disc degeneration.a resuh in pa of inle;segmentalligamentopathy(i.e..ligamentois laxity/rupture). -
The postoperativespine may perhaps be best
analyzedby p/kMRI in those patientswho have
undergone surgical intersegmentalfusion procedureso'.In the absenceof ferromaeneticfusion imp l a n t st.h e M R I u n i t w a sc a p a b l eo f i d e n t i c ael v a l uation as compared to the preoperative spine.
Casesof stabile intersegmentalfusion, for example,showedno evidenceof intersegmentalmotion,
thereby confirming postoperativeintersegmental
stability (figure 8). Overall mobility of the spine
may also be negativelyimpacted by discectomy
alone.unaccompanied
by surgicalbony fusion7,,.
Spinal cord motion is another dynamic factor
that may be amenableto analysisin caseswhere
there is clinicallysuspectedcongenitalor postoperative spinal cord,tethering.In test cases,for example, the conus medullaris was seen to freely
move anteriorlyand posteriorlyon flexion and extensionkMRI, respectively(figure 10).
Provocativep/kMRI is an experimental technique that may be of major practicalrelevancein
the future.By comparingimageswhere the patient
is pain or symptomfree,with a specificposition in
which the patient experiencespain or symptom(s),
the imaging specialistmay be able to clearly link
the medical imageswith the clinical syndrome.In
this manner,provocativep/kMRI may become a
truly specific diagnostic imaging method in cases
of spinaldisease(figure 11).
The imagesof the cervicaland lumbar spinesuftered very little from motion artifactsfrom either
CSF or body origin; no study was degradedto the
point of being uninterpretable.Patientmotion was
not a problem, this being overcome by simply
placing the scan table at 5 degreesposterior tilt
enabling the patient to passivelyrest againstthe
table during the MRI acquisitions.In addition, it
351
Upright, Weight-Beuring, Dvnumic-Kinetic MRI ol the Spine
J.R. Jinkins
A
Figure l13 Effects of weight bearing-neutralposture (uprighFneutral gravity and muscularbalanceeffects).and dynamic-kineticma
neuvetson the neuralforamina;dvsfunctionalintersegmental
motion (DIM) at levelsof discdegeneration.
A) Diagramof the recumbentspineshowingdegeneration
of the L4-L5 intervertebral
disc(serratedlines)-Note the minor narrowingof the neuralfora,
men at thislevel(openarrowhead).The
inleriorrecessof the ncuralforamenremarnsopen(rolid arrowhead).
Also nole the nearparallel position of the intervertebral end plates on either side of the L4-L5 disc.B) Diagram of the upright-neutral spine (large solid s,
lraight arrow: standingpostural axial loading) showingdegenerationof the L4-L5 intervertebraldisc (serratedlines)-Note the minor
increasein narrowing of the neural fbramen at this level (open arrowhead:compare with A). The inferior recessof the neural foramen is fu her nafiowed (solid arrowhead) by the increasingprotrusion of ihe posterolateralaspectof the intervertebraldisc (dashed
arrow: compar€with A). Also note the minor reduction in superoinferiorheight of the bony marginsof the neural foramen,in part as
a result of the disc spacenarrowing (dashedarow) associatedwith subluxationof the spinal facet joint arlicular processes(small straishtsolidarrows).
was found to be unnecessaryto stand the patient
for upright p/kMRI of the cervical and thoracic
spines;at present,only one sagittalsequenceis felt
to be necessaryfor evaluationof the lumbar spine,
in order to analyze the lumbosacral spine for true
postural curvature and for consideringissuesof
spinal balanceltT!.
The remainder of the lumbosacralspine p/k
MRI examinationmay be performedin the sitting
position.
The chemicalshift artifact was minor on all images,this being directly related to field strengtht
this effect would be expectedto be lessthan onehalf that experiencedat 1.5T. In addition,the degree of motion artifact from such sources as the
heart or CSF motion was typically minor, even
without'flow compensation'overlaytechniques
352
that were not used:this sourceof artifactsis also
related to field strength,commonly being worse
on high-fieldMRI units.
Other currently relevantoverlaytechniquesare
possible on this p/kMRI unit. Included among
theseare fat suppressionimaging(STIR: short tau
inversionrecovery)coupledwith fast spin echoacquisitions(figure 12).This is felt to be very useful
in the evaluation of spinal inflammation and
spinalneoplasia.
Finally, in the patient with a possible critical
stenosisof the spine in associationwith hypermobile instabilityor positionalworseningof the narrowing of the centralspinalcanal,long time period
acquisitionsequences
are of concernin the patient
who may have greater degreesof spinal cord or
cauda equina compressionin upright flexion-ex-
Rivistadi NeurcrudioloSid 15:333-356.2002
\J
(
Figure llt .C) Diagramof the upright-extended
(curvedsolid arrow) lumbosacral
spinesho\rs.an increasein the posteriordiscpro,
trusion/bulge.
and nalrowingof the posterioraspcctof the discspace(straightdashedarrows).Noie the increasing
posteriordiscproIrusion associatedwith obliteralion of the inferior recess(solid arrowhead) and superior recess(open arrowheadj of the neural foramen (solidarrowhead).
the openingup of the anlcriordiscspace(asterisk.
dashedcurvcdarrows).the narrowingof the postsriorirspecl oflhc discspace(straightdashedarrows).thc partialshearingcontractingsubluxationof the posteriorspinil facetlzygapopnv(solidslraightarrows).and the diminulionin sizeof the antcriorlvbulgingdiic (opcn curvedarrow)."Ati"iroi"
scal).iointprocesses
that thc opposedv-ertebral
endplateson eithersideof the degenerated
L4-5 intervertebral
discassurnea posteriorlydirecledwed€le
configuration(dYsfunctional
intersegmenlal
motion:C). D) Diagramof the upright-llexed(solid curvcd arrow) lumbosacralspine
demonstraling
anlerior discprotrusion(open curvedarrow) relatcdto Iaxit),ol the anlcrior longiludinalligament.lessening
of the
poslerior disc protrusion/bulgeas a r€sult of Iension of the remaining intacl posterior annular fib;rs. opening up of the pt,stJrior as
pect_ofthc discsPace(asterisk.
straighldashedarrows).narrowingof the anterioraspectof thc discspace(cuiveddashedarrows).the
partialshearingdislractingsubluxationof Ihe posteriorspinalfacet (z),gapophvseal)
joint processei(solidstraightarrowsl.and rhc
openinSup of the superiorreccss(solidarrowhead)and inleriorrecess(openarrowhead)oithc spinalneurallbr;men.Also note that
thc opposedverlebralcndplateson eithersideof the degencrated
L,1-5intervertebmldiscassumean anteflorl],directeuweugccon
fiSuration.
This latier observationindicalesdvsfunctional
intersegnrental
motion al lhN Iqvelot diqcdegcn(ration.a resultin parr of
intersegmental
(i.e..ligamenrous
ligamentopathy
laxitv/rupture).
tensionp/kMRl. For this purpose.very fast acquisition sequenceshave been implementedin order
lo screenfor suchcriticalabnormalitiesbefore going forward with longer time period imagingstudies (e.g., -4-5 minutes). Driven-equilibrium fast
spin echo acquisitionsoffer excellentquality imaging in a fraction of the time (e.g.,1 NEX - l7 seconds) required of traditionalsequences,
and allow
safe imaging of almost any patient with p/kMRI
(figure l3). These fast high-resolutiontechniques
may in the future be a major if not only method of
i m a g i n gt h e s p i n eu s i n gp / k M R l .
Conclusions
To conclude,the potentialrelativebeneficialaspectsof upright,weight-bearing(pMRI), dynamic-
kinetic (kMRl) spinalimagingon this systemover
that of recumbentMRI (rMRl) include:clarification of true sagittal upright neutral spinal curvature unaffectedby patient positioning.revelation
of occult degenerativespinal diseasedependent
on true axial loading (i.e.,weighfbearing) (figure
14),unmaskingof kinetic-dependentdegenerative
spinal disease(i.e..flexion-extension)(figures 1517),and the potential ability to scanthe patient in
the position of clinically relevantpain (figure 11)
(table 9). Scanningthe patient in Ihe operativeposillon, enablingthe surgeonto have a true preoperative picture of the intraoperative pathologic
morphology,is a topic currently under investigation ". This MRI unit also demonstratedlow claustrophobic potential and yielded high-resolution
imaseswith little motion/chemicalartifact.
J)J
Upright, WeightBearing, Dynamic-Kinetic MRI ofthe Spine
J.R. Jinkins
Figure 19 Translationalhypermobile instability associatedwith
dynamic flexion-extensionimaging (kMRI). A) Diagram of the
recumbent spine showingdegenerationof the L4-L5 interverte'
bral disc and interspinousligament (serrated lines). and degenerative anterior spondylolisthesisof L,l (asterisk) on L5. Note
the minor narrowing of the central spinal canal (double headed
arrow). B) Diagram of the upright-extended(solid curved arrow) lumbosacralspine showsa partial reduction of the spondylolisthesis(dashedand solid straight arrows). Note that the central spinal canal becomeswider (double headedarrow) as compared to the neutral or fl€xion diagrams(A.C). C) Diagram of
the uprighfflexed lumbosacral spine (solid curved arrow) reveals a minor increasein the anterior translationalsoondvlolisrhecis{dashedand solid slraighlarro$s).Nore rharihe cenrral
spinal canal becomesnarrower (double headed arrow) as compared to the neutral or extensiondiagrams(A,B).
Basedon initial experience
with this unit, it is
felt that mid-field MRI may prove to be the optimal field strengthfor routine,anatomicMR imaging of the spinalcolumnin degenerative
aswell as
"
other spinaldiseasecategories
In addition,the evidencethus far indicatesthat
p/kMRI may prove to be efficaciousto incorporate as a part of the diagnosis-treatment
paradigm
354
in patientswith spinal,radicularand referredpain
syndromes originating from spinal pathology
(table10).
This article is the proprietary property of Fonar Corporation,
Melville, New York. Some or all of the contentsmay be used again in other review publicationson this subject.Fonar Corporation reseNesthe rights of republicationafter proper reference
of the present Rivista di Neuroradiologiaarticle.
Rivista di Neuroradiolosia 75l.333-356.2C|J-2
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J. Randy Jinkins MD, FACR. FEC
Director of CraniospinalAnalomic Imaging Research
Department of Radiological Sciences
Medical Collegeof Philadelphia-Hahnemann
Drexel University
245 North 15'hStreet - Mailstop 206
Phifadefphia. PA 19102-| 192
E-mail:[email protected]