A- Review the anatomy and MR appearance of the brachial plexus. (Should Provide full description of BP and MRI appearance with appropriate justification).
B- Suggest an MRI protocol for a patient presenting with thoracic outlet syndrome. (Should Provide full discussion /justification of sequence inclusion. MRI sequence types and parameters are explained and supported )
C- (1000 words)
Anatomy of the Brachial Plexus
The brachial plexus is the nervous network present in the neck, of which its branches innervate the upper limbs and chest. The plexus forms from the ventral roots on either side of the C5 to T1 vertebra, and essentially forms three distinct branches: the superior trunk, middle trunk and inferior trunk (Figure 8). The subsequent cords—the posterior, medial and lateral cords—branch off to form five terminal branches innervating various regions of the arms (Luijkx & Knipe, 2015). All of the brachial plexus branches are responsible for the motor and sensory control of the arms (Lawande, Patkar, & Pungavkar, 2012). Injuries to this neural network are common and can be severely debilitating. In such cases, MRI is the modality of choice to visualise the brachial plexus in a patient with suspected injury (van Es, 2001; Magill, Brus-Ramer, Weinstein, Chin, & Jacques, 2015). Equally important is the visualisation of potential tumours in this brachial plexus region (van Es, 2001). Localisation of lesions can have a drastic impact on clinical approach (Lawande, Patkar, & Pungavkar, 2012)
As demonstrated in Figure 8, the superior, middle and inferior trunks originate from the dorsal roots of C5-T1, off which the he dorsal scapular nerve and the long thoracic nerve originate. These roots divide further into anterior and posterior divisions of each trunk, and intersecting to form the lateral, posterior and medial cords. The subclavian nerve arises from the superior trunk to innervate the subclavius musle (Tortora & Derrickson, 2009). The lateral pectoral and medial pectoral nerves that supply the pectoral muscles branch off the lateral and medial cords. Similarly, the upper subscapular and lower subscapular nerves that supply to subscapularis and terres major muscle, and the thoracodorsal nerve that supplies the latissimus dorsi muscle branches off the posterior cord (Tortora & Derrickson, 2009). The lateral cord becomes the musculocutaneous nerve and combines with a branch of the medial cord to form the median nerve. The posterior cord becomes the axillary and radial nerves. Apart from the aforementioned connection with the lateral cord to form the median nerve, the medial cord becomes the ulnar nerve and medial cutaneous nerves of the arm and forearm (Tortora & Derrickson, 2009).
Figure: Thoracic Outlet Syndrome. (The space between your collarbone (clavicle) and your first rib. This narrow passageway is crowded with blood vessels, nerves and muscles.
Figure 8 The brachial plexus is a network of nerves that arise from the base of the cervical vertebra to innervate the upper limbs (Luijkx & Knipe, 2015).
MR appearance of the Brachial Plexus
Successful imaging of the brachial plexus is possible with MRI due to its superior contrast and multiplanar capabilities (van Es, 2001; Lawande, Patkar, & Pungavkar, 2012). Ultrasound, the alternate approach to imaging the brachial plexus, is limited by is operator and is not capable of imaging the entire plexus, particularly to proximal and distal regions due to the bones that overlie the structures (van Es, 2001). Moreover, spinal CT is capable of visualising the brachial plexus using multiplanar constructions, although its lacking detail and contrast render it largely ineffective compared to MRI (van Es, 2001). This is because MRI is able to contrast the surrounding fat and nerves, in addition to depicting a greater amount of anatomical detail (van Es, 2001). Van Es (2001) states that different MRI sequences used to image the brachial plexus add to the diagnostic armamentarium of neurologists in identifying brachial plexus conditions. This is particularly significant, as brachial plexopathies bit it traumatic or otherwise, manifest with ambiguous symptoms (Lawande, Patkar, & Pungavkar, 2012).
The basic appearance of T1 weighted images of the brachial plexus demonstrates hypointense signals compared to fat and is intensity compared to blood vessels (Figure 12) (van Es, 2001). Moreover on T2 weighted images, the nerves of the brachial plexus appear brighter (Figure 13 and Figure 14)—even more so in STIR images due to the absence of fat signal (Figure 9).
Figure 9. Coronal STIR and sagittal T2 images displays ruptured nerve and a collection of fluid surrounding the area (Lawande, Patkar, & Pungavkar, 2012).
Thoracic outlet syndrome (TOS)
Neurogenic thoracic outlet syndrome (TOS) manifests due to trauma of the brachial plexus as it passes from the thoracic outlet to the axilla (Magill, Brus-Ramer, Weinstein, Chin, & Jacques, 2015). Vascular impingement may also occur, termed vascular TOS. All protocols should first and foremost ensure imaging of the entire plexus. In a patient with TOS, several MRI protocols may be utilised. Lawande, Patkar, & Pungavkar (2012) suggest the following approach: coronal short-tau inversion recovery (STIR) imaging, T1 weighted images and sagittal T1 weighted images should be obtained (Lawande, Patkar, & Pungavkar, 2012). The sagittal T1 images are taken with a hyperabducted arm through the symptomatic side, extending from the midline to axilla (Lawande, Patkar, & Pungavkar, 2012). Further sagittal T1 images with the arm in neutral position should also be acquired (Lawande, Patkar, & Pungavkar, 2012). Contrast can be used, especially if a tumour is suspected (Ersoy et al., 2012).
Figure 10. Corononal STIR and T1 weighted images of asymptomatic and non-remarkable brachial plexus (Lawande, Patkar, & Pungavkar, 2012).
Figure 11. A, B, C and D demonstrate normal anatomy from the sagittal aspect using T1 3D volume acquisition with a 1.5mm slice thickness. Image (A) demonstrates several anatomical landmarks, including the anterior (a) and middle (m) scalene muscles, ventral rami of C7-T1 (names accordingly), the subclavian vein (V) and the clavicle (c). Seen more laterally than Image (A), Image (B) displays the trunks of the brachial plexus (superior [low black arrow], middle [short black arrow] and lower [white arrow]). Image (C) shows the various divisions of the plexus. Image (D) displays the three cords: medial cord (white arrow), posterior cord (long black arrow), and the anterior cord (short black arrow). Image adapted from van Es (2001).
Figure 12. Arrow indicates a tumour in the left brachial plexus and scalene muscles on coronal T1-weighted images leading to motor and sensory symptoms (Castillo, 2005). The tumour on the left side has destroyed the interscalene fat pad visible on the right.
Figure 13. A Schwannoma seen on Coronal fat-suppressed T2-weighted MRI. The lowest arrow demonstrates hyperintense signal in the root/trunk region of the brachial plexus. Tumour growth into the spine around C7 to C11 is typical of tumours of the nervous sheath (Castillo, 2005).
Figure 14. Coronal fat suppressed T2-weighted MRI of a patient with Charcot-Marie-Tooth disease demonstrates hyperintensity and thickening of the brachial plexus.
Ersoy, H., Steigner, M. L., Coyner, K. B., Gerhard-Herman, M. D., Rybicki, F. J., Bueno, R., & Nguyen, L. L. (2012). Vascular thoracic outlet syndrome: protocol design and diagnostic value of contrast-enhanced 3D MR angiography and equilibrium phase imaging on 1.5-and 3-T MRI scanners. American Journal of Roentgenology, 198(5), 1180-1187.
Lawande, M., Patkar, D. P., & Pungavkar, S. (2012). Pictorial essay: Role of magnetic resonance imaging in evaluation of brachial plexus pathologies. The Indian journal of radiology & imaging, 22(4), 344.
Luijkx, T., & Knipe, H. (2015). Brachial plexus. Retrieved from http://radiopaedia.org/articles/brachial-plexus
Magill, S. T., Brus-Ramer, M., Weinstein, P. R., Chin, C. T., & Jacques, L. (2015). Neurogenic thoracic outlet syndrome: current diagnostic criteria and advances in MRI diagnostics. Neurosurgical focus, 39(3), E7.
Tortora, G. J. & Derrickson, B. (2009). Principles of Anatomy and Physiology. John Wiley & Sons, Inc.
Van Es, H. W. (2001). MRI of the brachial plexus. European radiology, 11(2), 325-336.
Use the Harvard referencing style.
(maximum 1000 words).:
For this section (attached) answers for last year student you can use the articles and paraphrase all information and use different MRI images
1. Review the anatomy and MR appearance of the brachial plexus.
Should Provide full description of BP and MRI appearance with appropriate justification.
2. Suggest an MRI protocol for a patient presenting with thoracic outlet syndrome.
Should Provide full discussion /justification of sequence inclusion. MRI sequence types and parameters are explained and supported.
A request arrives from General Practitioner (GP) which reads “Lumbar spine MRI”. Clinical indications: 50 year old male complaining of back pain and fever. You performed a T2 Sagittal on L1-S1. Discuss the following. (maximum 1000 words)
A-Identify the abnormality (in above image) and discuss possible pathologies.
Should Provide full discussion /justification of sequence with appropriate justification. Also include images normal and abnormal to compare (MRI Images)
-Sequestration of disc. L3-L4 ( This is the main pathology ) should explain it.
– Infection like TB or Brucellosis (this is other pathologies) should explain.
B-How would you tailor this exam in light of this finding?
Should Provide full discussion /justification of sequence inclusion. MRI sequence types and parameters are explained and supported. Also include images (MRI Images)