Lumbar Spine MRI

==Anatomical Structures==
===Sagittal Scans===
Sagittal MRI scans are typically taken across five standard planes. There may be further scans between these planes, or it may be slightly displaced to the left or right.
 Sagittal MRI five standard planes and the intersecting structures
Plane 	Vertebral structures 	Vertebral canal structures 	Extra-vertebral structures
Median 	Vertebral bodies and intervertebral discs (AP and AF) anteriorly, and the spinous processes posteriorly 	Conus medullaris at upper segmental levels, and the cauda equina at lower levels. 	Aorta terminates opposite L4
Paramedian 	Vertebral bodies and intervertebral discs anteriorly (AP and AF), and the laminae posteriorly 	May miss the spinal cord, and only show the cauda equina. 	Right of midline: right side edge of the aorta, right common iliac artery in front of L5, and left common iliac vein.Left of midline passes through the aorta.Posteriorly there is multifidus.
Transpedicular	Lateral sectors of the vertebral bodies, the lateral sectors of the intervertebral discs (AF +/- NP), the pedicles, and some portions of the facet joints. Slightly more medial intersects the inferiorly articular processes. Slightly more lateral intersects the superior articular processes	Spinal nerves and their dural sleeves as they pass under the pedicles in the intervertebral foraminae	Right of midline: IVC, right common iliac artery in front of L5Left of midline: might intersect lateral aortaPosteriorly multifidus.
Tangential 	Most lateral margins of the vertebral bodies and the AF at each segmental level, or the concavity of the vertebral body and their lumbar arteries and veins 	No intersection 	Left of midline: lateral to aorta or lateral segmentsRight of midline: IVC, right common iliac artery in front of L5Posteriorly the erector spinae at most levels and multifidus at lumbosacral levels.
Peripheral 	Transverse processes 	No intersection 	Psoas major, quadratus lumborum anteriorly. Erector spinae posteriorly.
*Anteriorly different planes have various intersections with the crura of the diaphragm, the great vessels, psoas major, and quadratus lumborum. 
*Posteriorly there is intersection through multifidus, longissimus thoracic, or iliocostalis lumborum.
*Across the vertebral body concavities there are the lumbar arteries and lumbar veins that are covered by psoas
*Anterior to the vertebral bodies on the right there is the right crus and the IVC
*Anterior to the vertebral bodies towards the centre and left there is the left crus and the aorta
*Posterior to the laminae there is multifidus
*Anterior to the transverse processes there is the psoas major and quadratus lumborum
*Posterior the the transverse processes there is various components of the erector spinae.
===Axial scans===
There are three main planes for axial MRI scans. With interpretation, the first step is determining whether the scan is transpedicular, subpedicular, or transarticular. The second step is estimating the segmental level by examining the external relations.
 Axial MRI three standard planes and the internal relations
Plane 	Vertebral structures 	Vertebral canal structures
Transpedicular	Pedicles project form the posterior surface of the vertebral body. Posteriorly various parts of the laminae and spinous process.	Dural sac and nerve roots of the cauda equina. Nerve roots typically towards posterior surface of the sac due to the patient lying supine.
Subpedicular 	Vertebral body anteriorly, laminae posteriorly 	Dural sac with nerve roots of the cauda equina, and spinal nerves of the segment as they run through the intervertebral foramen. Spinal nerve lateral to the dural sac +/- dural sleeve with CSF.
Transarticular	Intervertebral disc, facet joints 	Dural sac and cauda equina centrally. Spinal nerve or ventral ramus leaving the vertebral column at the posterolateral corner of the disc and entering the psoas major. The spinal nerve passes obliquely and caudally through the foramen and so it is located further laterally than in subpedicular scans and is dissociated from the dural sac.
The external relations can be used to identify the segment being used.
 External Relations
Segment	Anterior 	Lateral 	Posterior
L1 	Left and right crus, IVC, Aorta, left renal vessels	Broad flat quadratus lumborum, and a narrow psoas major 	Narrow multifidus plus longissimus thoracic, and iliocostalis lumborum.
L2 	Crura are smaller, IVC, Aorta, right renal vessels 	Quadratus lumborum, larger psoas major 	Multifidus, longissimus thoracic, and iliocostalis lumborum
L3 	No crura. IVC and Aorta 	Quadratus lumborum, large psoas major 	Multifidus expands laterally to the limits of the laminae. Plus longissimus thoracic and iliocostalis lumborum
L4 	3 great vessels: IVC and common iliac arteries 	large psoas major, small quadratus lumborum 	Multifidus is wide, and erector spinae are small.
L5 	4 great vessels: common iliac veins and arteries 	Huge psoas major, absent quadratus lumborum, iliolumbar ligament	Multifidus is wide. No iliocostalis, and a small portion of longissimus.
==Check List for Interpretation==
Before doing anything, first verify patient identification and the date of scan
===Survey View===
Count vertebra, and assess for transitional anatomy
===Fat Suppressed Coronal===
Assess facet joints for effusions, size, cartilage thickness, oedema. Look for extra spinal pathology. Scroll through the sacroiliac joints looking for osteoarthritis, oedema, effusions.
===T1 Sagittals===
In T1, spinal fluid is dark and fat is bright. Determine the left-right orientation. On the left, the gives off branches at ~L1. On the right, the renal artery runs posterior to IVC. The Aorta is wider than IVC.
Working from caudal to rostral observe:
*Neural foramina and nerve roots: nerve contact and compression.
*Intervertebral discs: width, protrusions/ herniations.
*Spinal column: alignment (spondylolisthesis), vertebral body shape (compression fractures, Schmorls’ nodes), posterior bony elements (spondylolysis), degenerative end plate changes (changes in fat content), hemangiomas.
*Retroperitoneal space: adenopathy, masses, great vessel aneurysm, etc
===T2 Sagittals===
In T2, spinal fluid is bright.
Working from caudal to rostral observe:
*Dural sac—cord and rootlets: width, compression, irregularities 
*Intervertebral discs: width, protrusions/ herniations, hydration, high intensity zones
*Spinal column: alignment (spondylolisthesis), vertebral body shape (compression fractures, Schmorls’ nodes), posterior bony elements (spondylolysis), degenerative end plate changes (changes in fat content), hemangiomas.
*Posterior bony elements: breakage, listhesis, pseudo-articulations, etc.
===T1 Axials===
The CSF appears gray and fat appears bright. Proceed caudal to cranial.
Orientation – neural foramina lie at level of discs. 
*Content of the spinal canal and neural foramina: Trace course of nerve roots through neural foramina
*Intervertebral discs— continuity, bulges, etc.
*Bone – Vertebral bodies; spondylolisthesis, posterior bony elements (spondylolysis, breakage)
*Ligamentam flavum: thickened appearance, impingement
*Retroperitoneal space: adenopathy, masses, muscle, fat infiltration of multifidus (see image)
===T2 Axials===
Spinal fluid appears bright. Proceed caudal to cranial.
*Content of the spinal canal and neural foramina: Trace course of nerve roots through neural foramina
*Intervertebral discs— continuity, bulges, etc.
*Bone – Vertebral bodies; spondylolisthesis, posterior bony elements (spondylolysis, breakage)
*Ligamentam flavum: thickened appearance, impingement
*Retroperitoneal space: adenopathy, masses, muscle, etc.
==Assessment==
Ensure you have covered all structures. Assess need for other studies
==Bibliography==
*Bogduk, Nikolai. Clinical and radiological anatomy of the lumbar spine. Chapter 19. Edinburgh: Elsevier/Churchill Livingstone, 2012.
==References==
Category:Lumbar Spine
Category:Radiology