ANATOMY OF BRACHIAL AND LUMBOSACRAL MR NEUROGRAPHY PLEXUS BRACHIAL PLEXUS Roots trunks -cords
Roberto Gasparotti Clinical examples (traumatic injuries) Neuroradiology Unit Department of Diagnostic Imaging LUMBOSACRAL PLEXUS University of Brescia Italy Roots sciatic femoral - obturator pudendal nerves Clinical examples ECNR COURSE Dubrovnik October 21-25 2018
MR IMAGING of PERIPHERAL NERVES
Imaging of peripheral nerves Surface Phased-array coils Technical limitations : T2 FSE with fat suppression Small size of the nerves T2 STIR sequences Poor contrast resolution Uniform suppression of fat between nerves, muscles signal and vessels T1 Low SNR Signal intensity variability Flow artefacts Intact nerves Anatomical complexity mild hyperintensity compared to muscles Lower intensity compared to veins T1 T2 FSE_fs T2 STIR Maravilla KR et al. Imaging of the peripheral nervous system: evaluation of peripheral neuropathy and plexopathy. AJNR Am J Neuroradiol 1998;19:1011-1023
3D MR NEUROGRAPHY NEW SEQUENCES HIGH RESOLUTION MR NEUROGRAPHY fascicular pattern 3D T2 sequences Inversion recovery excitation (3D SPACE, VISTA, XETA) Further refinement of MR Neurography Enhanced contrast between nerves and muscles High resolution 3D volumes Oblique and curved-planar reformations of plexuses (MPR and MIP)
MIP Sciatic nerve MR NEUROGRAPHY upper limb MR NEUROGRAPHY brachial plexus and upper limbs Median n. Forearm supination Neck, Thoracic (and Abdominal) surface coils in a phased array 1.5 3T Small Field of View T2FSE or STIR Ulnar n. sequences High resolution Fat suppression Peripheral Pulse triggering T2 3D MRN T1 2D MRN
Radial n.
2D MRN
MR NEUROGRAPHY DTI peripheral nerves
lumbosacral plexus and lower extremities Peripheral 1.5T- 3 T MR units Nerve Sensitivity to the water molecules Surface phased array coils diffusion along the nerves Spine Thoracic - Abdominal MR lumbar spine axons QUANTITATIVE ANALYSIS MR Neurography Fractional Anisotropy Pelvis > Thigh > Leg (FA) Mean Diffusivity (MD) Coronal 3D MRN and T1 Axial Diffusivity Pelvic region Radial Diffusivity Axial T1-T2 STIR T2 T1 Radial Anisotropy Sacral promontory >knee > ankle Fiber count Fiber length
Tractography > Graphical display of DTI 2D MRN T1 data (streamlines) Jambawalikar et al. Skeletal Radiol 2010
DTI TRACTOGRAPHY DTI TRACTOGRAPHY
Median Nerve (3T) Median Nerve (3T) Guggenberger et al. Eur J Radiol 2012 Guggenberger et al. Eur J Radiol 2012
Sciatic nerve (3T) Sciatic nerve (3T) Mathys et al. Muscle Nerve 2013 Mathys et al. Muscle Nerve 2013
Brachial plexus (1.5T) Brachial plexus (1.5T) Gasparotti et al. Invest Radiol 2013 Gasparotti et al. Invest Radiol 2013 IMAGING OF NERVE ROOTS C5 3D T2 SPACE sequences C6 Long echo trains> rapid image formation with diminished artifacts C5 C6 C7 C7 SNR spatial resolution C8 C4-C5 T1 acquisition time C8 High resolution 3D volumes Multiplanar and curved
planar reconstructions 3D SPACE T2 T1 Gasparotti et al. Radiographic Assessment of adult brachial plexus C5-C6 injuries. In "Practical Management of Pediatric and Adult Brachial MIP Plexus Injuries " . Chung K, Yang L, McGillicuddy J eds. Elsevier, New Baumert B et al. Magnetic Resonance Imaging 2009 York, 2012
3D MR Myelography - Neurography postprocessing 3D MR Myelography postprocessing curvilinear reconstructions along the course of the nerve roots multiplanar reconstructions along the course of the nerve roots
Ventral and dorsal rootlets C5
C6 C7 T1
T2 C5T1C8C7
3D MRM 3D MRN
COMPLETE NERVE ROOT AVULSION PARTIAL AVULSION R C5 L C7 Reduced number of the identifiable rootlets on MIP projections Missing ventral or dorsal root with absent or minimal abnormalities of the nerve root sleeves MR Myelography 3T dorsal root ganglion
T2 STIR T1
Brachial Plexus: coronal plane Brachial plexus: coronal plane
T1 T1 3D MRN DTI 3D MRN supraclavear
Scalenus medius
sternocleidomastoid
Scalenus anterior clavicle
clavicle MIP infraclavear Coronal oblique Infraclavear BP Infraclavear BP Subclavian a. Multiplanar reformats MIP thin
Brachial plexus supraclavear MR neurography 1.5 vs 3T
Average size 1.5 T of the roots C5 3.8 mm C5 C6 C6 4.8 mm UT C7 4.9 mm C7 C8 4.3 mm C8 LT Brachial plexus: sagittal BRACHIAL PLEXUS Interscalenic space interscalene triangle > roots > trunks anterior scalene muscle middle and posterior scalene T2 STIR muscles first rib subclavian vessels, roots, and Middle-posterior C5 scalene SPT trunks of theBP C6 roots and trunks MPT The 3 trunks are formed within C7 the interscalene triangle. anterior C6 scalene anterior SPT C8 The suprascapular nerve (C5- scalene C7 T1 C6) arise from the superior MPT trunk Subcl. Subcl. C8 Subcl. Artery The phrenic nerve (C3-C5) T1 Artery Artery passes between the anterior Jugular Jugular Jugular Subcl. Subcl. and middle scalene and Subcl. Vein Vein Vein continues over the surface of the anterior scalene muscle.
MRN: axial reformats
Anterior scalene BP T1 BP Middle BP BP scalene BP
Posterior scalene
Anterior scalene T2 STIR
Middle scalene
BRACHIAL PLEXUS BRACHIAL PLEXUS: infraclavear traction injuries
PC LC
C3
C4 C5 C5 C6
C7 Lateral Cord anterior divisions of UT and MT T1 Musculocutaneous and Median nerves MC Posterior Cord posterior divisions of the three trunks Axillary and Radial nerves MIP oblique views BRACHIAL PLEXUS BRACHIAL PLEXUS infraclavear costo-clavicular space infraclavear-retropectoralis minor space
PC PC PC LC LC LC Clavicle LC MC MC The costoclavicular space is bounded anteriorly by the Axillary Axillary MC Artery subclavius muscle, MC Artery anterosuperiorly by the clavicle, Subcl. and posteriorly by the first rib and Artery 1st rib Axillary Axillary the middle scalene muscle Subcl. m Vein Vein Sublc.m Subcl. Pectoralis Pectoralis Subcl. minor. m minor. m subclavian vessels, and the Vein Vein divisions and cords of BP
Demondion er al. Radiology 2003 Demondion er al. Radiology 2003
3D MRN: curviplanar reformats BRACHIAL PLEXUS traction injuries C6 > SPT > PC
C6 C6 SPT PC C5 PC C6 SPT LC PC
MR NEUROGRAPHY
TERMINAL BRANCHES: 3D MRN coronal oblique reformats TRAUMATIC INJURIES OF THE SHOULDER 67 yo M, Humeral Head and neck Fracture with head luxation 2 months before Complete motor deficit R ulnar, median, radial nerves, anesthesia right forearm
PC Axillary. N. LC
Muscoluc. N.
MC
Median N. Ulnar. N.
The terminal branches are usually difficult to separate lateral cord Concomitant imaging of the arm Neuropathies TRAUMATIC INJURIES OF THE SHOULDER TRAUMATIC INJURIES OF THE SHOULDER
Signal Intensity of the Nerve > neurogenic edema in dependent muscles
Radial Ulnar
Ulnar BA Radial Median
Median Ulnar
TRAUMATIC INJURIES OF THE SHOULDER Chronic Inflammatory Demyelinating Poliradiculoneuropathy (CIDP) The distribution of hypertrophy in typical CIDP is symmetric and predominant in the nerve roots, with gradual normalization toward the proximal limb segments distally
MusculoCutaneous
Musculocutaneous
Gasparotti R et a. New technologies for the assessment of neuropathies. Nat Rev Neurol. 2017 Apr;13(4):203-216
LUMBOSACRAL PLEXUS MR MIELOGRAPHY Two separate plexuses Lumbar plexus L1 L3 lumbar rami, and L3 T12 and L4 L4 Sacral plexus ventral rami of L4 L5 (lumbosacral trunk) and S1 S4 S1 The lumbosacral trunk (L5+L4) connects the lumbar and sacral plexuses LumbarSacral Plexus Plexus LUMBAR PLEXUS ANATOMY Chronic Inflammatory Demyelinating Poliradiculoneuropathy (CIDP) The distribution of hypertrophy in typical CIDP is symmetric and predominant in the nerve roots, with gradual normalization 3D MR NEUROGRAPHY toward the proximal limb segments distally
MIP L2 L3 L3 L4 L4 L5 L5
3D MR Neurography
Gasparotti R et al. New technologies for the assessment of neuropathies. Nat Rev Neurol. 2017 Apr;13(4):203-216
Femoral Nerve: axial (1.5T) Femoral Nerve : axial (3T) T2 STIR T1 PSm L2-L3-L4 roots lies between the psoas major and iliacus muscles descends inferolaterally through the psoas muscle, traveling in the iliacus compartment Im emerging posterior to the inguinal ligament exits the pelvis under the A A inguinal ligament V V
Femoral Nerve : coronal (3T) Femoral nerve injury
MPR L Fn T2 SPAIR T1 L4 L4 L3 L Fn Fn Fn Fn Fn Fn
L4 Fn
Denervation quadriceps muscle Lateral Femoral Cutaneous Nerve Obturator nerve L2 L4 roots The LFCN is formed from the Obt. n L2 and L3 roots, exits in the exits the pelvis under the superior region of the anterior superior pubic ramus in the upper outer iliac spine (ASIS) under, over, corner of the obturator foramen or through the inguinal Obt. n ligament
Obt. n
Obt. n Obt. n Obt. foramen
Meralgia parestethica Painful mononeuropathy due to entrapment of the LFCN
SACRAL PLEXUS SACRAL PLEXUS
S1 S1 S2 SN
S4 S3
Pudendal Nerve High resolution 3D volumes MPR and MIP reconstructions S2-S3-S4 S2-S3-S4 It passes through the greater sciatic It passes through the greater sciatic foramen between the piriformis and foramen between the piriformis and the coccygeus muscles the coccygeus muscles It crosses over the ischial spine It crosses over the ischial spine after passing between sacrotuberous after passing between sacrotuberous and sacrospinous ligament and sacrospinous ligament Distally enters the pudendal Distally enters the pudendal (Alcock's) canal along the lateral (Alcock's) canal along the lateral wall of the ischiorectal fossa wall of the ischiorectal fossa underneath the obturator internus underneath the obturator internus fascia fascia Hardly identifiable on High Hardly identifiable on High resultion MRN resultion MRN Pudendal neurovascular Pudendal neurovascular bundle bundle Sciatic Nerve L4 S3 roots T2 FSE It courses through the 19 patients with clinical symptoms of greater sciatic foramen sciatica and disc herniation demonstrated most commonly inferior on MRI to the piriformis muscle DTI and tractography of the lumbosacral nerve roots Mean FA value of the compressed lumbar T1 T1 nerve roots was significantly lower than the FA of the contralateral nerve roots (p=0.0001) and healthy volunteers Histological changes Disrupted nerve root barrier > intraneural edema Demyelination and wallerian degeneration
Greater sciatic Iliac vessels Sciatic Nerve foramen 3D MRN
Bounded by the outer L4 edge of the sacrum, greater sciatic notch L5 (superior) and Iliac vessels sacrospinous ligament (inferior)
Sciatic PM MIP
Sciatic Nerve Sciatic nerve Gluteal region
CPN Gemellus Superior
TN GM GM Sciatic Nerve: thigh
AM The nerve then descends into the SM ST BF thigh along the lateral aspect of the ischial tuberosity deep to the gluteus maximus muscle before dividing into the tibial and common peroneal nerves AM SM The sciatic nerves should be BF symmetric in size and gradually decrease in caliber distally
BF peroneal SM tibial tibial peroneal
MR NEUROGRAPHY (3T) lower limb
Tibial Peroneal Tibial Peroneal FA Sciatic n. 0.55 Sciatic nerve
Sciatic nerve injury PIRIFORMIS SYNDROME 48-yo woman, 6 months hystory of left sciatic pain 34-yo male, pelvic trauma, left foot drop
*
Denervation into the muscles innervated by the peroneal nerve