Thoracic Radiology Mount Sinai
Michael Chung, MD Assistant Professor Cardiothoracic Radiology Mount Sinai
World Congress of Thoracic Imaging June 2017 Disclosures
There are no disclosures pertinent to this presentation
Mount Sinai Department of Radiology Introduction
• The chest wall muscular anatomy is an aspect of chest CT that can be often overlooked by the cardiothoracic radiologist
• Goals: • Review the normal chest wall anatomy on CT • Highlight the common normal variations in chest wall anatomy and shape • Focus on a few conditions which may distort the normal anatomy • Review common chest wall surgeries, including their indications and imaging appearance on CT
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KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Sternocleidomastoid (16) 2. Pectoralis minor 11. Deltoid • Divides neck into anterior and posterior triangles 3. Subscapularis 12. Serratus Anterior • Will often see a portion of the SCM as it attaches to its 4. Teres Major 13. Rhomboid origin on the manubrium 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Platysma 7. Infraspinatus 16. Sternocleidomastoid • Not visualized here, but can be seen on chest CTs as a 8. Latissimus Dorsi 17. Rectus Abdominis broad sheet of thin muscle covering the anterior neck 9. Trapezius
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NOTES: KEY: 1. Pectoralis major 10. Long Head of Triceps • Deltoid (11) 2. Pectoralis minor 11. Deltoid • Largest shoulder muscle, will commonly see on chest 3. Subscapularis 12. Serratus Anterior CTs with patient’s arms elevated 4. Teres Major 13. Rhomboid • Innervated by the axillary nerve (C5-6) 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Levator Scapulae (15) 7. Infraspinatus 16. Sternocleidomastoid • Connects pectoral girdle to the cervical spine (originates 8. Latissimus Dorsi 17. Rectus Abdominis on C1-4 transverse processes) 9. Trapezius
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KEY: • Teres Major (4) 1. Pectoralis major 10. Long Head of Triceps • Will often be confluent with the latissimus dorsi (8) 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior • Assists in medial shoulder rotation and shoulder 4. Teres Major 13. Rhomboid adduction 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Teres Minor (5) 7. Infraspinatus 16. Sternocleidomastoid • Part of the rotator cuff, assists in external rotation 8. Latissimus Dorsi 17. Rectus Abdominis • Can be difficult to differentiate with infraspinatus in 9. Trapezius younger, thinner patients
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2 8 3 12 4 5 14 7 13 6 10 9 11 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Supraspinatus (6) 2. Pectoralis minor 11. Deltoid • The most commonly ruptured rotator cuff muscle 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Can degenerate in elderly patients leading to instability 5. Teres Minor 14. Erector Spinae in the glenohumeral joint 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid • Infraspinatus (7) 8. Latissimus Dorsi 17. Rectus Abdominis • Assists in laterally rotating the arm 9. Trapezius • Innervated by suprascapular nerve (C5 and C6)
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4 3 5 14 7 6 10 13 9 NOTES: • Pectoralis Major (1) KEY: • Covers much of the anterior chest, inserts on the lateral 1. Pectoralis major 10. Long Head of Triceps lip of the bicipital groove of the humerus 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Pectoralis Minor (2) 5. Teres Minor 14. Erector Spinae • Divides the axillary artery into 3 parts 6. Supraspinatus 15. Levator Scapulae • Divides axillary lymph nodes into levels 7. Infraspinatus 16. Sternocleidomastoid • I: below inferior edge of p. minor 8. Latissimus Dorsi 17. Rectus Abdominis • II: underneath/posterior to p. minor 9. Trapezius • III: above/medial to p. minor
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8 3 7 14 9 10 NOTES: 13 • Rhomboid (13) • Q uadrilateral shaped, helps retract scapula KEY: 1. Pectoralis major 10. Long Head of Triceps • Innervated by dorsal scapular nerve, injury can lead to a 2. Pectoralis minor 11. Deltoid winged scapula 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Long Head of Triceps (10) 5. Teres Minor 14. Erector Spinae • Arises from infraglenoid tubercle of the scapula 6. Supraspinatus 15. Levator Scapulae • Extends distally anterior to the teres minor and posterior 7. Infraspinatus 16. Sternocleidomastoid to the teres major 8. Latissimus Dorsi 17. Rectus Abdominis • Acts in extending forearm; long head stabilizes humeral 9. Trapezius head in abduction
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KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Erector Spinae (14) 2. Pectoralis minor 11. Deltoid • From lateral to medial: 3. Subscapularis 12. Serratus Anterior • Iliocostalis 4. Teres Major 13. Rhomboid • Longissimus 5. Teres Minor 14. Erector Spinae • Spinalis 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius
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KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Subscapularis (3) 2. Pectoralis minor 11. Deltoid • Part of the rotator cuff 3. Subscapularis 12. Serratus Anterior • Inserts on the lesser tuberosity of the humerus and 4. Teres Major 13. Rhomboid assists in internal rotation 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius
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KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Trapezius (9) 2. Pectoralis minor 11. Deltoid • Diamond shaped, superficial muscle of the posterior 3. Subscapularis 12. Serratus Anterior neck/back 4. Teres Major 13. Rhomboid • I nnervated by CN XI (accessory nerve) 5. Teres Minor 14. Erector Spinae • Acts to elevate, rotate and retract the scapula 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius
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KEY: 1. Pectoralis major 10. Long Head of Triceps 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius
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KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Latissimus Dorsi (8) 3. Subscapularis 12. Serratus Anterior • Assists in adduction, internal rotation, and extension of 4. Teres Major 13. Rhomboid the glenohumeral joint 5. Teres Minor 14. Erector Spinae • Innervated by thoracodorsal nerve 6. Supraspinatus 15. Levator Scapulae • Important to preserve this nerve in surgical flaps 7. Infraspinatus 16. Sternocleidomastoid involving the lattisimus 8. Latissimus Dorsi 17. Rectus Abdominis • Arises from posterior cord of brachial plexus 9. Trapezius
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KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Serratus Anterior (12) 3. Subscapularis 12. Serratus Anterior • Draws scapula anteriorly against chest wall 4. Teres Major 13. Rhomboid • Consists of 8 interdigitations of muscles 5. Teres Minor 14. Erector Spinae • Originates from ribs 1-8 and inserts on medial border of 6. Supraspinatus 15. Levator Scapulae scapula 7. Infraspinatus 16. Sternocleidomastoid • Innervated by the long thoracic nerve 8. Latissimus Dorsi 17. Rectus Abdominis • Injury to this nerve results in winged scapula 9. Trapezius
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KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Rectus Abdominis (17) 3. Subscapularis 12. Serratus Anterior • Paired muscles separated by the linea alba 4. Teres Major 13. Rhomboid • Attaches to the costal cartilages of ribs 5-7 and the 5. Teres Minor 14. Erector Spinae xiphoid process of the sternum 6. Supraspinatus 15. Levator Scapulae • Dual blood supply from the superior and inferior 7. Infraspinatus 16. Sternocleidomastoid epigastric vessels 8. Latissimus Dorsi 17. Rectus Abdominis • Can be used for muscle flaps in the chest 9. Trapezius
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KEY: 1. Pectoralis Major 1. Long Head of Triceps 2. Pectoralis minor 2. Deltoid 3. Subscapularis 3. Serratus Anterior 4. Teres Major 4. Rhomboid 5. Teres Minor 5. Erector Spinae 6. Supraspinatus 6. Levator Scapulae 7. Infraspinatus 7. Sternocleidomastoid 8. Latissimus Dorsi 8. Rectus Abdominis 9. Trapezius
Mount Sinai Department of Radiology Variant Anatomy: Sternalis
• Muscle band extending from the jugular notch to the inferior aspect of the sternum
• Lies adjacent to the medial edge of the pectoralis major
• Can be mistaken for a pathologic lesion
• Found in ~5% of the population
Mount Sinai Department of Radiology Variant Anatomy: Sternalis
• Muscle band extending from the jugular notch to the inferior aspect of the sternum
• Lies adjacent to the medial edge of the pectoralis major
• Can be mistaken for a pathologic lesion
• Found in ~5% of the population
• Often seen on mammography • Typically visible in the medial aspect of the breast on cranio-caudal (CC) view
Mount Sinai Department of Radiology Variant Anatomy: Pectus Excavatum
• Congenital chest wall deformity with a concave depression of the sternum • Most common chest wall deformity (90%)
• Males > Females
• Associations: A • Marfan syndrome • Ehlers Danlos syndrome • Noonan syndrome B
• Haller index used to quantify severity • Maximal transverse diameter (A) / narrowest AP length of chest (B) • normal = 2.5, significant if >3.25
• On chest radiograph can result in: • Silhouetting/blurring of right heart border • Increased density in right inferomedial lung
Mount Sinai Department of Radiology Variant Anatomy: Pectus Carinatum
• Also known as “pigeon chest”
• Less common than pectus excavatum
• Two patterns: • Chondrogladiolar • More common • Involves mid and lower portions of sternum • Chondromanubrial • Involves upper portion of sternum (manubrium) • More inferior body of sternum is deviated posteriorly
• Treatment • Ravitch procedure • Open surgery, more invasive • Reverse Nuss procedure
Mount Sinai Department of Radiology Conditions to Note: Poland Syndrome
• Congenital unilateral absence of pectoralis major and minor muscles
• Causes a unilateral hyperlucent hemithorax on radiographs
• Rare and usually sporadic, not familial
• Spectrum of disease can result in aplasia or hypolasia of the muscles • Can also see effects in overlying breast or nipple
• Consider the condition “amastia” instead if • Absent left pectoralis major and minor muscles there is just absence of breast tissue • More inferiorly, breast tissue was also aplastic • Can be seen after chest wall irradiation during childhood or after excision of pre- pubertal breast bud
Mount Sinai Department of Radiology Conditions to Note: Poliomyelitis
• Once common but now rare disease secondary to infection by poliovirus
• Most infected patients have no serious symptoms, but ~1% develop paralysis from destruction of motor neurons
• Two forms: • Paralytic • Lower limbs more affected than upper limbs • Non -paralytic
• Note the extensive fatty muscle atrophy in the left hemithorax involving the pectoralis muscles, subscapularis, trapezius, and latissimus • NOT to be confused with Poland Syndrome!
Mount Sinai Department of Radiology Conditions to Note: Facioscapulohumeral Muscular Dystrophy (FSHD)
• Autosomal dominant form of muscular dystrophy • In >95% cases, associated with an abnormality in chromosome 4
• Initially affects facial muscles, scapula, and upper arms • Weakness often asymmetric
• Symptoms may develop in early childhood
• Studies have shown it most commonly affects: • Trapezius and serratus anterior • Followed by less commonly the • Note the prominent atrophy of the right serratus latissimus and pectoralis major anterior as well as the surrounding shoulder girdle muscles • MRI can potentially be used to differentiate FSHD from other forms of muscular dystrophy
Mount Sinai Department of Radiology Conditions to Note: Elastofibroma Dorsi
• Benign soft tissue tumor located in the infrascapular region, deep to the serratus anterior and latissimus dorsi
• When unilateral, may be more commonly right sided • Bilateral involvement is overall more common (~55-60%)
• Frequently shows mild-moderate FDG uptake on PET-CT
• Seen commonly in older females • Mean age of diagnosis 65-70 years
• Bilateral soft-tissue masses with attenuation similar to the serratus anterior overlying it
Mount Sinai Department of Radiology Common Surgeries: Nuss Procedure
• a.k.a. minimally invasive repair of pectus excavatum (MIRPE)
• First reported in 1987 by D. Nuss
• Concave stainless steel bar inserted underneath sternum through two small incisions
• Postoperative testing may show improvement in pulmonary function tests and increased exercise tolerance
• Bar displacement is a possible complication • Seen post-trauma (i.e. car accident)
• Imaging pre- (top) and post-repair
Mount Sinai Department of Radiology Common Surgeries: Eloesser Flap
• Single stage procedure
• For treatment of severe pleural empyema
• Described in 1935 by Leo Eloesser • Initially used to treat tuberculous empyema
• U- shaped incision with resection of multiple posterolateral ribs • U- shaped flap is folded into pleural space, creating a constant communication
• Open communication necessitates prolonged wound care and dressing changes
Illustration: Denlinger, “Eloesser Flap Thoracostomy Window”
Mount Sinai Department of Radiology Common Surgeries: Eloesser Flap
• Single stage procedure
• For treatment of severe pleural empyema
• Described in 1935 by Leo Eloesser • Initially used to treat tuberculous empyema
• U- shaped incision with resection of multiple posterolateral ribs • U- shaped flap is folded into pleural space, creating a constant communication
• Open communication necessitates prolonged wound care and dressing changes
• Note the contiguous skin flap extending into the pleural space
Mount Sinai Department of Radiology Common Surgeries: Clagett Flap
• Three -stage procedure for treatment of severe empyemas • v ersus single stage for Eloesser
• Resection of posterolateral lower ribs with formation of open window • No skin flap; allows for granulation tissue to form and line the cavity
• Second step is antibiotic irrigation
• Third step is closure
• Note the lack of an obvious contiguous skin flap extending into the cavity
Mount Sinai Department of Radiology Common Surgeries: Mastectomy
• Simple Mastectomy • Removal of breast tissue alone, including areola/nipple • Residual chest wall thickness will vary depending on the thickness of the patient’s subcutaneous fat
• Modified Radical Mastectomy • Various forms exist • Defined as removal of breast tissue with axillary node dissection, in addition to partial removal of pectoralis major/minor • Can also just remove the pectoralis major fascia, in which case it can be indistinguishable from simple mastectomy on imaging • Simple mastectomy (top) showing preserved pectoralis muscles • Modified radical mastectomy (bottom) with arrow pointing to partially resected pectoralis major
Mount Sinai Department of Radiology Common Surgeries: Mastectomy
• Radical Mastectomy • Removal of the breast/nipple/areola, axillary nodes, and chest muscles • Pectoralis major and minor
• Once the standard, but now less commonly performed due to existence of less invasive procedures
• Small amount of residual pectoralis major may be seen at its costal attachment (yellow arrow) • Should not be misinterpreted as recurrent tumor
Seah W. “Chest Wall after Mastectomy,” Radiology, 1987.
Mount Sinai Department of Radiology Common Surgeries: Implant Reconstruction
• Two main surgical planes for implant placement: • Subglandular • Retropectoral
• Examples of retropectoral to the right: • Implant lies under the pectoralis major (arrow)
• Retropectoral first introduced in 1968 by Dempsey and Latham
• Benefits of retropectoral: • Decreased incidence of capsular contracture • Improved breast contour • Plane of dissection is less invasive • Improved visibility of the breast tissue on mammography
Mount Sinai Department of Radiology Conclusion
• While focusing on the lungs, cardiovascular organs or osseous structures of the thorax, the overlying chest musculature may be easily overlooked
• Cardiothoracic radiologists should be experts on the normal chest wall anatomy as well as the potential variants and anatomic/structural abnormalities which are commonly encountered in everyday practice
• One of the biggest impacts we have as cardiothoracic radiologists is the precision and accuracy by which we describe a pathologic process, especially when it involves the chest wall
Mount Sinai Department of Radiology References
• Anjamrooz, S. H. (2013). Biceps sternalis: A y-shaped muscle on the anterior chest wall. Journal of Cardiothoracic Surgery, 8(1). • Donnelly, Lane F., et al. “Anterior Chest Wall: Frequency of Anatomic Variations in Children.” Radiology 212.3 (1999): 837–840. • Fishman, EK., et al. “CT of the axilla: normal anatomy and pathology.” Radiology. 1986 May; 6(3):475-502. • Mullan CP, Madan R, Trotman-Dickenson B, Qian X, Jacobson FL, Hunsaker A. Radiology of chest wall masses. AJR Am J Roentgenol. 2011 Sep;197(3):W460-70. • Nam SJ, Kim S, Lim BJ, Yoon CS, Kim TH, Suh JS, Ha DH, Kwon JW, Yoon YC, Chung HW, Sung MS, Choi YS, Cha JG. Imaging of primary chest wall tumors with radiologic-pathologic correlation. Radiographics. 2011 May-Jun;31(3):749-70. • Ochsner JE, Sewall SA, Brooks GN, Agni R. Best cases from the AFIP: Elastofibroma dorsi. Radiographics. 2006;26(6):1873-6. • Raikos A, Paraskevas GK, Tzika M, Faustmann P, Triaridis S, Kordali P, et al. Sternalis muscle: an underestimated anterior chest wall anatomical variant. Journal of Cardiothoracic Surgery. 2011;6(1). • Tasca G, Monforte M, Iannaccone E, et al. Upper girdle imaging in facioscapulohumeral muscular dystrophy. PLoS ONE. 2014;9(6):e100292. • Thourani VH, Lancaster RT, Mansour KA et-al. Twenty-six years of experience with the modified eloesser flap. Ann. Thorac. Surg. 2003;76 (2): 401-5
Mount Sinai Department of Radiology Author Information
Michael Chung, MD Assistant Professor Cardiothoracic Radiology Mount Sinai Hospital New York, NY Email: [email protected]
Mount Sinai Department of Radiology