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library:spine_deep_dive [2025/06/18 02:55] – scottlibrary:spine_deep_dive [2026/06/11 05:53] (current) – scott
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 ====What is this page?==== ====What is this page?====
  
-This page is dedicated to more technical information regarding spine imaging, to include anatomy, MRI technique, pathology, and more of the 'why' of spine MRI. This page will follow the format of a question and answer dialogue for each topic. +This page is dedicated to more technical information regarding spine imaging, to include anatomy, MRI technique, and more of the 'why' of spine MRI. This page will follow the format of a question and answer dialogue for each topic. See [[:pathology|MR Pathology]] for various diseases of the spine. 
 + 
 +====What is Important Spine Anatomy to Know For Scanning?==== 
 + 
 +  * **Cervical**: 7 Vertebrae 
 +  * **Thoracic**: 13 Vertebrae 
 +  * **Lumbar**: 7 Vertebrae 
 + 
 +Comfort with the anatomy of the spine, Vertebrae, and spinal cord are imperative for good scans. Click on each slide to expand. 
 + 
 +{{:library:discanatomyslide.png?400|}}  {{:library:spinalcordanatomyslide.png?400|}}  {{:library:lumbarplexusanatomyslide.png?400|}}  {{:library:vertebralanatomyslide.png?400|}} 
 + 
 +====Brachial Plexus==== 
 + 
 +The brachial plexus is a network of nerves exiting the spinal cord bilaterally between roughly C3/4 and T1/2 that travel through the axilla and innervate the forelimbs. Because the nerves travel up through the limb, positioning is important when examining the brachial plexus. Typically, extend and secure the limbs rostrally and symmetrically for best visualization. The use of an anterior coil can greatly improve SNR as well, as the ventral thorax can be far from the spine coil, especially in deep chested dogs. Quality imaging of the brachial plexus should include: 
 + 
 +  * All 3 planes: Sagittal, Axial, and Dorsal 
 +  * Motion reduction: High bandwidth, extra averages/NEX, BLADE/PROPELLER 
 +  * Large FOV: Demonstrate any changes to muscles 
 +  * Post contrast imaging with fat saturation 
 + 
 +For more details on scanning technique see [[:brachial_plexus|Brachial Plexus MRI]] 
 +See the images below to get a sense of the brachial plexus anatomy 
 + 
 +{{:library:nerve_stir_sag_mip.gif?|}}  
 + 
 +{{:library:nerve_stir_ax_mip.gif?|}} 
 + 
 +{{:library:nerve_stir_dor_mip.gif?|}} 
 + 
 +{{:library:nerve_stir_mip_rotate.gif?|}} 
 + 
 +====Lumbar Plexus==== 
 + 
 +The lumbar plexus is a network of nerves that exit the lumbar spine bilaterally from L4 and innervate the hindlimbs. When imaging the lumbar plexus, it may be necessary to image down through the femurs, so positioning the hindlimbs extended and internally rotated is preferable. The typical frog-leg positioning would preclude imaging most of the femur and hindlimb muscles on many scanners, and increase imaging time due to the amount of oversampling that would be required. 
 + 
 +{{:library:dor_mensa_plexus_mip.gif?|}}
  
 ====Why is it important to use an odd number of slices for sagittal spine imaging?==== ====Why is it important to use an odd number of slices for sagittal spine imaging?====
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 Below are some commonly available sequences, with their vendor specific names, where to find them, caveats, and advantages: Below are some commonly available sequences, with their vendor specific names, where to find them, caveats, and advantages:
  
-==Balanced Steady State Free Precession with Phase Cycling (FIESTA-C, CISS)==+===Balanced Steady State Free Precession with Phase Cycling (FIESTA-C, CISS)===
  
 Where to find: Most vendors have this saved in an IAC protocol, occasionally spine. Where to find: Most vendors have this saved in an IAC protocol, occasionally spine.
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 Advantages: Very high inherent SNR; it's possible to get really high resolution or very thin slices. It can be run isotropically for reformats. Bright fluid contrast can help with anatomic information Advantages: Very high inherent SNR; it's possible to get really high resolution or very thin slices. It can be run isotropically for reformats. Bright fluid contrast can help with anatomic information
  
-==RF Spoiled Fast Gradient Echo (FLASH, FSPGR)==+===RF Spoiled Fast Gradient Echo (FLASH, FSPGR)===
  
 Where to find: Most vendors have this saved in a brain protocol Where to find: Most vendors have this saved in a brain protocol
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 Advantages: Pretty robust sequences with relatively high inherent SNR. There are usually different fat saturation options available such as SPECIAL/SPAIR which can be more homogenous and less time intensive that regular FatSat options. The grey/white matter contrast is superior to FSE Advantages: Pretty robust sequences with relatively high inherent SNR. There are usually different fat saturation options available such as SPECIAL/SPAIR which can be more homogenous and less time intensive that regular FatSat options. The grey/white matter contrast is superior to FSE
  
-==RF Spoiled Fast Gradient Echo with k space modifications (LAVA, VIBE)==+===RF Spoiled Fast Gradient Echo with k space modifications (LAVA, VIBE)===
  
 Where to find: Most vendors have this saved in a routine liver protocol Where to find: Most vendors have this saved in a routine liver protocol
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 Advantages: These are really designed to run for speed more than anything else, so they'll be faster the FSPGR/FLASH. Reserve this for some thing incidental in the soft tissues outside the spine. Advantages: These are really designed to run for speed more than anything else, so they'll be faster the FSPGR/FLASH. Reserve this for some thing incidental in the soft tissues outside the spine.
  
-==3D Fast Spin Echo (CUBE, SPACE)==+===3D Fast Spin Echo (CUBE, SPACE)===
  
 Where to find: Most vendors have this saved in a spine or brain protocol Where to find: Most vendors have this saved in a spine or brain protocol
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 Advantages: Very high SNR, these can be run isotropically or with very thin slices. Due to the long ETL and varying flip angle intravascular signal will be dark, which is excellent for vessel wall imaging  ruling out vessel vs. lesion. True T2 weighting can be achieved with a higher TE ~120, though keep the ETL a bit shorter than the out of the box parameters. If using a STIR, consider running it post contrast! This will suppress intravascular signal and help visualize nerves. Advantages: Very high SNR, these can be run isotropically or with very thin slices. Due to the long ETL and varying flip angle intravascular signal will be dark, which is excellent for vessel wall imaging  ruling out vessel vs. lesion. True T2 weighting can be achieved with a higher TE ~120, though keep the ETL a bit shorter than the out of the box parameters. If using a STIR, consider running it post contrast! This will suppress intravascular signal and help visualize nerves.
  
-==Multi Echo GRE (MERGE, MEDIC)==+===Multi Echo GRE (MERGE, MEDIC)===
  
 Where to find: Most vendors have this saved in a cervical spine protocol Where to find: Most vendors have this saved in a cervical spine protocol