ROBERTO CARTOLARI U.O.D. DI Neuroradiologia Ospedale “Belcolle” Viterbo – Italy Servizio di Radiologia Ospedale “S. Giovanni” – EOC Bellinzona - Switzerland The Axial Loaded Imaging of the Lumbar Spine 18 Years After. Is It Still a Valuable Examination?

AL-CT In 1992 the idea of Axial Loading

AL-CT Newton’s third law of Conservation of the Momentum

AL-CT Newton’s third law of Conservation of the Momentum

NON-PATHOLOGIC MOTION PATTERN REFERENCE MODEL OF THE SPINE UNDER A PURE AXIAL LOAD

The Axial Loader is a non-ferromagnetic/x-Ray transparent device

AL-CT TECHNIQUE  Basal/AL Volumetric acquisition (L2-L3/S1)  MPR (Sagittal plane)  3D SSD  Basal/AL images cine-loop

AL-MRI TECHNIQUE  Basal acquisition (Sag T1w, Sag T2w, Ax T2w)  AL Volumetric acquisition (Sag T1w, Sag T2w, Ax T2w)  Basal/AL images cine-loop

Axial ImagesSagittal Images3D Images

REMEMBER !!!  only axial loading (the simplest work)  no motion is superimposed  the Patient is SUPINE (it’ s not true orthostatism) AL-CT/MRI

REMEMBER !!!  all the findings are REAL (no distortion artifacts) AL-CT/MRI

AL-CT/MRI FINDINGS CLINICAL SIGN !!! > 90% Patients referred partial to total recurrence of their symptoms during axial loading

AL-CT/MRI: WHEN? THE CLINICAL PICTURE DOESN’ T MATCH THE BASIC IMAGING (X-RAY, CT, MRI)

AL-CT/MRI FINDINGS Elementary Dynamic Modifications Intervertebral Disc Modifications Intervertebral Disc Modifications Alterations of Intersomatic Relationships Alterations of Intersomatic Relationships Alteration in Relationships of Articular Processes Alteration in Relationships of Articular Processes Narrowing of Spinal Neural Foramina Narrowing of Spinal Neural Foramina Thickening of Ligamenta Flava Thickening of Ligamenta Flava Narrowing of Interspinous Spaces and Hypermobility of the Spinous Processes Narrowing of Interspinous Spaces and Hypermobility of the Spinous Processes

THE “PARADOXICAL MOTION”

THE “DISC VACUUM SIGN” (“telescoping spine” – J.R.Jinkins, 2002 )

THE “ARTICULAR VACUUM SIGN” (CT)/DISPLACEMENT OF INTRARTICULAR FLUID (MRI)

THE “FUNCTIONAL STENOSIS” (disc protrusion & yellow ligaments thickening & degenerative listhesis)

THE DISC HERNIATION

THE COMPLEX DYNAMIC MODIFICATIONS (CDMs) Stereotyped sequences of EDMs in response to axial loading

CDMsBasal studies Plain FilmsAL studiesInstability grade CDM1- L4 facet underslipping - Narrowing L4-L5 (disc) interspinous space - Conserved L5-S1 disc space - Further L4 facet underslipping - Further narrowing L4-L5 space - Anterior L4 translation - L5 paradoxical motion Grade 1 CDM2- L4, L5 facet underslipping - Narrowing of L4-L5 and L5-S1 and spinous spaces - Further facet underslipping - Further disc and spinous spaces narrowing - Anterior translation of L4 (<) Grade 2 CDM3- As CDM2, plus: - Degenerative listhesis (>) - often disc and articular vacuum phenomenon - Further disc space narrowing - Increment of listhesis - vacuum disappearing (Vacuum Sign) Grade 3 CDM4- Lysis and listhesis of L5 (L4) - Underslipping of L4 inferior facets - Narrowing of interspinous spaces - Widening of lysis and increment of listhesis - Wedging of L4 inferior facets into the lysis Grade 4A Grade 4B

CDM-1

CDM-2

CDM-3

CDM-OCDM-1CDM-2CDM-3 As one of the components of the spine fails for any reason (infection, trauma, degenerative changes, …), a stereotyped series of actions occur which lead to a cascade series of alterations in a sort of “domino effect”

The “DOMINO EFFECT”

modello CARTOLARI

AL-MRI CDM4

FONAR rMRI/pMRI/kMRI J.R.Jinkins – 1999/2000

G- SCAN G- SCAN

pMRI kMRI

At present no comparative studies between AL and rMRI/pMRI/kMRI

AL-CT OF THE OPERATED SPINE

AL-CT/AL-MRI are relatively invasive examinations (X-Rays) moderately time-consuming procedures

AL-CT/AL-MRI are powerful diagnostic tools to visualize the possible alterations in the distribution of the vectorial lumbar pathways after axial loading allow a good visualization of the response of any part of the FSU to axial loading

AL-MRI vs AL-CT

 Less invasive (no X-Rays)

AL-MRI vs AL-CT  Less invasive (no X-Rays)  Better tissue contrast

AL-MRI vs AL-CT  Less invasive (no X-Rays)  Better tissue contrast  Wider FOV

AL-MRI vs AL-CT  Less invasive (no X-Rays)  Better tissue contrast

AL-CT vs AL-MRI  Better bone structures definition

AL-CT vs AL-MRI  Better bone structures definition  Better evaluation of complex spatial instabilities (3D)

AL-CT vs AL-MRI  Better bone structures definition  Better evaluation of complex spatial instabilities (3D)  Easier evaluation of articular “micro-movements”

AL-CT vs AL-MRI  Better bone structures definition  Better evaluation of complex spatial instabilities (3D)  Easier evaluation of articular “micro- movements”  Shorter acquisition time (better Patient’s compliance)

AL-MRI: indications

 Younger Patients

AL-MRI: indications  Younger Patients  Early stages instability

AL-CT: indications  Older Patients

AL-CT: indications  Older Patients  Previously operated Patients (more complex instability patterns)

AL-CT: indications  Older Patients  Previously operated Patients (more complex instability patterns)  Late stages instability

AL-CT: indications  Older Patients  Previously operated Patients (more complex instability patterns)  Late stages instability  AL-MRI gives no or little informations

CONCLUSIONS AL-CT AL-CT:  Clearly image the operated spine  Allows the observation of any intersegmental motion  Allows the analysis of the ways the operated spine dissipates vectorial forces  Directly evaluate the way the spine devices work  First choice examination in FBSS

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