MR imaging of the brachial plexus: anatomy and pathology

Transcription

1 MR imaging of the brachial plexus: anatomy and pathology Poster No.: C-0265 Congress: ECR 2012 Type: Scientific Exhibit Authors: N. Bermejo; Bilbao/ES Keywords: Trauma, Neoplasia, Inflammation, Imaging sequences, MR, Neuroradiology peripheral nerve DOI: /ecr2012/C-0265 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 43

2 Purpose 1. To identify the structures which make up the brachial plexus (BP) in magnetic resonance imaging (MRI). 2. To choose the appropriate MRI protocol of sequences for each clinical context 3. To show examples of the pathology that may affect the BP Page 2 of 43

3 Methods and Materials PROTOCOL: We use a 1.5 T magnetic resonance (MR) and applied a: 1. Routine protocol in the study of the BP: - Right and left sagittal T1-weighted images - Coronal STIR, T1 and T2-weighted images - Axial T2-weighted images USE OF EACH SEQUENCE: T1: anatomic assessment. - Sagittal of each side separately: to locate the lesion in each compartment. - Coronal: to obtain a simultaneous overview of both plexuses. It also allows finding references to determine which region of the BP (roots, trunks...) is affected. - Axial: to evaluate the medulla in the spinal canal, axillary lymphadenopathies and the plexus on another level. T2, STIR: detection of pathology, especially STIR, which is more sensitive. As the pathology (tumoral, inflammatory...) tends to have more water content (and water shines in these sequences) it is easier to identify the region of the pathology 2. Other sequences, based on clinical suspicion: - Tumoral, inflammatory (also to rule out abscess): post contrast, fat-saturated T1weighted images to better define the pathological region to be enhanced with contrast. - Post-radiotherapy fibrosis: there are different opinions. Some authors believe that the addition of contrast to differentiate tumor recurrence has no value because both can show enhancement, so the morphological signs and signal intensity are better shown in contrast-free sequences. - Thoracic Outlet Syndromen : sagittal T1-weighted images arms up right and left, to compare on the same side with arms down, and upper extremity MR Angiography to confirm stenosis and detect possible post-stenotic dilatations. HALLMARKS: Page 3 of 43

4 Through coronal sequences, some anatomical hallmarks were considered to determine the affected plexus region. Fig.1 1. Anterior and middle scalene muscle: - Medial: roots (interscalene space (IS)) - Lateral: trunks (coracoclavicular space (CC)) upper, middle and lower 2. Lateral edge of the 1st rib - Divisions (CC) 3. Coracoid: - Cords (retropectoral minor space (RP)): lateral, posterior and medial Fig. 1: Hallmarks References: Hospital Basurto - Bilbao/ES Page 4 of 43

5 Fig. 2: Hallmarks STIR References: Hospital Basurto - Bilbao/ES ANALYSIS: Following signs were considered suspicious (which must be always interpreted within the clinical context): - Diffuse or focal enlargement (especially eccentric or nodular mass) - Marked hyperintensity on T2-weighted images or STIR - Loss of fat planes around all or part of a plexus - Enhancement on T1-weighted images with fat supression ATTENTION!! STIR hyperintensity without other suspicious signs requires careful analysis since it can happen under normal conditions due to magic angle artifact. Page 5 of 43

6 INDICATIONS: 1. Non-traumatic pathology where patients may be studied because of different reasons: - After treatment (most frequent; radiotherapy in breast cancer) to rule out recurrence or fibrosis - Known neoplasis to rule out BP metastases or infiltration by vicinity (breast cancer metastases, Pancoast Tumour..) - Clinic to raise arms: Thoracic Outlet Syndrome - Clinic without history of interest Trauma (usually motorcycle accidents or injury in newborns due to birth trauma) Page 6 of 43

7 Images for this section: Fig. 1: Hallmarks Hospital Basurto - Bilbao/ES Page 7 of 43

8 Fig. 2: Hallmarks STIR Hospital Basurto - Bilbao/ES Page 8 of 43

9 Results We will show 13 cases of BP pathology: A. NON-TRAUMATIC INJURY Method of study 1. Identification of BP lesions with mass efect to rule out: - Primary neurogenic tumors (neurifibromas, schwannomas,) - Secondary tumors (metastases or infiltration by vicinity) 2. Analysis of the contour and signal of the BP fibers which, according to the clinical context, focus on: - Post-radiotherapy injury, post-surgery - Post-infectious neuritis 3. Rule out cervical disc disease (especially C5-6 and C6-7): hernias which compress the spine or roots Rule out Thoracic Outlet Syndrome: although the clinical is suggestive and the protocol is somewhat different 5. After having ruled out masses, cervical hernias, history of radiation, surgery or recent vaccination and if there's no infection: Diagnosis by exclusion of idiopathic neuritis, which is a benign and self-limiting process with spontaneous resolution over time (usually postinfectious or inflammatory) CASES 1. TORATHIC OUTLET SYNDROME Definition: Compression of the neurovascular structures passing through the cervicalthoracic-brachial junction with raised arms. It is more common in women (*4) aged 20 to 40. Clinic: is somewhat different depending on the compressed structure, which orientates the radiologist: - Arterial: coldness, pallor, and pain - Nervous: paresthesias and pain from ear to shoulder (affectation of C5, 6.7) or on arm (C8, T1) Page 9 of 43

10 - Venous: heaviness, edema, cyanosis Etiology: osseous or soft tissue causes 1. Osseous: - Partial or complete cervical rib (soft, fibrous), elongated C7 transversal apophysis - First rib and collarbone: exostosis, fracture callus, tumors 2. Soft tissue: - Congenital: anterior scalenus muscle (hypertrophy, more anterior insertion), supernumerary muscle (minor scalenus) - Acquired fibrosis after surgery, radiotherapy or trauma. 3. Predisposing morphotypes: thin women with little fat in the thoracic operculum area or postural. Imaging diagnosis: - Simple radiography (thorax and cervical spine): should be performed routinely to exclude bone abnormalities. - MR: Excellent soft tissue contrast (Non-ionizing, non-iodinated contrast). Image analysis: 1. Comparative analysis of the three spaces (IS, CC, RP) in the sagittal T1-weighted with raised arms and arms down. - ARTERIAL pathology: any caliber reduction is pathological. Arterial compression is most often noticed in the CC compartment, followed by IS. - VENOUS pathology: caliber reduction is not significant because it may also appear in asymptomatic individuals. Search for indirect signs such as collateral circulation and venous thrombosis. - NERVOUS pathology: analyze perineural fat (because its disappearance indicates nerve compression) and possible contact with bony structures, which also indicates compression. 2. Search for causes of compression in the 3 compartments (see etiology) Page 10 of 43

11 Fig. 3: IS References: Hospital Basurto - Bilbao/ES Page 11 of 43

12 Fig. 4: CC References: Hospital Basurto - Bilbao/ES Page 12 of 43

13 Fig. 5: RP References: Hospital Basurto - Bilbao/ES CASE 1 Page 13 of 43

14 Fig. 6: Cervical Rib References: Hospital Basurto - Bilbao/ES CASE 2 Page 14 of 43

15 Fig. 7: Parcial cervical rib References: Hospital Basurto - Bilbao/ES CASE 3 Fig. 8: Morphotype References: Hospital Basurto - Bilbao/ES 2. MASSES MR: image analysis 1. Determine if the mass is intrinsic or extrinsic - Intrinsic: benign and malignant neurigenic tumors: may be indistinguishable in imaging. - Extrinsic: metastases or direct extension from non-neurogenic tumor (Pancoast, sarcoma, fibromatosis, desmoid tumor, lipoma) 2. Locate the area of the injury in the BP: support prior to surgery Page 15 of 43

16 Fig. 9: Intrinsic References: Hospital Basurto - Bilbao/ES CASE 4 Page 16 of 43

17 Fig. 10: Neurogenic tumor References: Hospital Basurto - Bilbao/ES CASE 5 Page 17 of 43

18 Fig. 11: Neurogenic tumor2 References: Hospital Basurto - Bilbao/ES Page 18 of 43

19 Fig. 12: Extrinsic References: Hospital Basurto - Bilbao/ES CASE 6 Page 19 of 43

20 Fig. 13: Pancoast tumor References: Hospital Basurto - Bilbao/ES 3. POST-TREATMENT The clinical context is often a patient with a history of cancer, especially breast cancer, with clinical evidence of plexopathy after radiotherapy treatment. Signs that suggest: A. Fibrosis: low signal intensity on T2 and T1-weighted images with diffuse thickening B. Recurrence: eccentric mass with low signal intensity on T1 and increased T2 signal intensity CASE 7 Page 20 of 43

21 Fig. 14: Fibrosis References: Hospital Basurto - Bilbao/ES 4. IDIOPATHIC NEURITIS CASE 8 Page 21 of 43

22 Fig. 15: Neuritis References: Hospital Basurto - Bilbao/ES B. TRAUMATIC INJURY The analysis is usually performed after 4-6 weeks It should follow a study scheme: 1. PREGANGLIONIC INJURY (central spinal axis, foramen roots) - Cervical spinal cord - Nerve roots - Posterior paraspinal musculature CASES 9, 10, 11, 12 Page 22 of 43

23 Fig. 16: Preganglionic References: Hospital Basurto - Bilbao/ES 2. POSTGANGLIONIC INJURY (distal to the neural foramen) - Brachial Plexus - Adjacent tissues Page 23 of 43

24 Fig. 17: Postganglionic References: Hospital Basurto - Bilbao/ES CASE 13 Page 24 of 43

25 Fig. 18: Plexitis References: Hospital Basurto - Bilbao/ES The differenctiation between pre and post-ganglionic areas is useful for treatment, because: - Pre-ganglionic injury: not repairable (transplant donor) - Post-ganglionic injury: repairable (BP discontinuity: auto-grafts, no discontinuity of BP: conservative treatment) Page 25 of 43

26 Images for this section: Fig. 3: IS Hospital Basurto - Bilbao/ES Page 26 of 43

27 Fig. 4: CC Hospital Basurto - Bilbao/ES Page 27 of 43

28 Fig. 5: RP Hospital Basurto - Bilbao/ES Page 28 of 43

29 Fig. 6: Cervical Rib Hospital Basurto - Bilbao/ES Page 29 of 43

30 Fig. 7: Parcial cervical rib Hospital Basurto - Bilbao/ES Fig. 10: Neurogenic tumor Hospital Basurto - Bilbao/ES Page 30 of 43

31 Fig. 12: Extrinsic Hospital Basurto - Bilbao/ES Page 31 of 43

32 Fig. 9: Intrinsic Hospital Basurto - Bilbao/ES Page 32 of 43

33 Fig. 8: Morphotype Hospital Basurto - Bilbao/ES Page 33 of 43

34 Fig. 11: Neurogenic tumor2 Hospital Basurto - Bilbao/ES Page 34 of 43

35 Fig. 17: Postganglionic Hospital Basurto - Bilbao/ES Page 35 of 43

36 Fig. 16: Preganglionic Hospital Basurto - Bilbao/ES Page 36 of 43

37 Fig. 15: Neuritis Hospital Basurto - Bilbao/ES Page 37 of 43

38 Fig. 14: Fibrosis Hospital Basurto - Bilbao/ES Page 38 of 43

39 Fig. 13: Pancoast tumor Hospital Basurto - Bilbao/ES Page 39 of 43

40 Fig. 18: Plexitis Hospital Basurto - Bilbao/ES Page 40 of 43

41 Conclusion MRI is the technique of choice for the study of the brachial plexus. Taking into account certain anatomical landmarks the different parts of PB can be located. Knowledge of the sequences in MRI is important to select an appropriate protocol for each clinical context. Page 41 of 43

42 References 1.Brachial plexus injury: clinical manifestations, conventional imaging findings, and the latest imaging techniques. Yoshikawa T, Hayashi N, Yamamoto S, Tajiri Y, Yoshioka N, Masumoto T, Mori H, Abe O, Aoki S, Ohtomo K. Radiographics Oct. 2.Imaging assessment of thoracic outlet syndrome. Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A. Radiographics Nov-Dec. 3.Acute brachial neuritis (Parsonage-Turner syndrome): MR imaging appearance--report of three cases. Helms CA, Martinez S, Speer KP. Radiology Apr. 4.MR imaging of nontraumatic brachial plexopathies: frequency and spectrum of findings. Wittenberg KH, Adkins MC. Radiographics Jul-Aug. 5.The brachial plexus: normal anatomy, pathology, and MR imaging Brian C. Bowen, MD, PhDa,b,c,*, Pradip M. Pattany, PhDa,c,Efrat Saraf-Lavi, MDb, Kenneth R. Maravilla, MDd Neuroimag Clin N Am 14 (2004). Page 42 of 43

43 Personal Information AUTHORS: Nuria Bermejo Espinosa Marta Bermejo Espinosa Xabier Azores Galeano Miren Gorriño Angulo Page 43 of 43