1. Anatomy of the Chest in Computed Tomography
Michael C. Ficorelli, RT

2. Lesson Description
To explain the various exams pertaining to the chest and thorax using computed tomography, incorporating cross sectional anatomy from images

3. Lesson Description
To be able to identify anatomy of the thoracic cavity. Understand the clinical indications for exams of the chest. To understand the methods of patient scanning, positioning, and protocols. To understand indications for contrast.
Chapter 16

4. CT of the Chest

5. Bony Thorax / Visceral Thorax

6. Bony Thorax Protects and aids in the organs of respiration
Thoracic vertebrae – ( 12 ) - Posterior boundary
Sternum – Anterior boundary with 3 components
Manubrium – superior articulates with clavicles and first pair of ribs, contains jugular notch (level T2 – T3)
Sternal Angle – where manubrium and body come together ( T4 – T5 )
Body – articulates with the cartilage of the 3rd through 7th ribs
Xiphoid – muscle attachments
Ribs – ( 12 pair ) – head, neck, tubercle and body
First 7 pair = True ribs
Lower 5 pair = False ribs
Costal Cartilage

7. Thoracic Apertures 2 openings Superior – Thoracic Inlet
Formed by first thoracic vertebrae, First pair of ribs w/ costal cartilage, and Manubrium
Allows passage of nerves, vessels and viscera from the neck
Inferior – Thoracic Outlet
Much Larger than the Inlet, made up of 12th thoracic vertebrae, 12th pair of ribs and xiphoid sternal junction

8. Pleural Cavities
Pleura – serous membrane in which each lung lies which secrete fluid to provide lubrication for the lungs while breathing
Parietal Pleura – outer layer; continuous with thoracic wall and diaphragm; moves with inspiration
Visceral pleura – inner layer; closely covers outer surface of lung and falls into the fissures

9. Lungs

10. Lungs
Conical shaped organs of respiration composed of spongy like material called parenchyma
Apex – above level of first rib
Bases – aka diaphragmatic surfaces – dome of the diaphragm
3 borders
Inferior
Anterior
Posterior
2 Angles
Cardiophrenic sulcus – medial
Costophrenic sulcus - lateral

11. Lungs Divided into lobes by fissures lined by pleura Right – 3 lobes
Inferior lobe separated from middle by oblique fissure
Middle lobe separated from superior by horizontal fissure
Left – 2 lobes
Lobes separated by oblique fissure
Cardiac Notch – located on medial surface
Lingula – tongue-like projection on infero-anterior surface
Hilum – opening on the medial surface of each lung which acts as a passage for main bronchi, blood vessels, lymph and nerves entering and exiting

12. Bronchi
Trachea bifurcates into right and left mainstem bronchus at carina ( T-5 )
Right mainstem is wider, shorter and more vertical than the left
Enter the lungs and divide into secondary bronchi
Secondary divides into tertiary or segmental bronchi which extend into each of the approximately 10 segments within the lung
Continues to divide into smaller bronchi then into bronchioles which continue to divide into alevoli ( functional units of the respiratory system )

13. Secondary Pulmonary Lobule
Basic unit of pulmonary structure and function
Surrounded by connective tissue and consists of 3 – 5 acini ( which contain alveoli ) for gas exchange
Visualized with High-Resolution Chest CT – ILD (Interstitial Lung Disease)

15. Mediastinum
Midline region of the thoracic cavity between the two pleural cavities of the lungs which is further divided into 2 compartments – Contains the thymus gland, trachea, esophagus, lymph nodes, thoracic duct, heart, great vessels and various nerves
Bounded by the sternum anteriorly and posteriorly by the thoracic vertebrae
Superior compartment – contains thymus gland and acts as a conduit for entrance and exits of structures
Inferior compartment – subdivides
Anterior - anterior to pericardial sac and posterior to sternum
Middle – contains pericardial sac, heart and root of great vessels
Posterior – posterior to pericardium and anterior to the inferior 8 thoracic vertebrae

16. Mediastinum

17. Thymus Gland and Lymph Nodes of Chest
Thymus = Triangular shaped bilobed gland located in superior mediastinum
Responsible for immunity, produces thymosin (maturation of lymphocites)
Lymph nodes in mediastinum are clustered around the great vessels
Difficult to see in scan unless abnormal
Thoracic Duct – main vessel of lymph system
Begins inferior to diaphragm

18. Lymph Chain of Chest

19. Heart
Four chambered muscular organ lying obliquely in the chest with 2/3 of its mass situated on the left
Base – Posterior aspect
Apex – formed by left ventricle
Sternocostal – Anterior surface formed by right atrium and ventricle with small portion of left ventricle
Diaphragmatic – rests on diaphragm and formed by both ventricles and right atrium
Pulmonary – left surface; left ventricle and rests in the cardiac notch of the lung

20. Pericardium

21. Pericardium
Sac which encloses the heart and proximal portions of the great vessels
Fibrous pericardium – attached to central tendon of diaphragm through which the IVC emerges
Serous pericardium – double layered inner surface of the fibrous pericardium
Parietal layer – Inner surface of fibrous pericardium
Visceral layer – covers outer surface of the heart and roots of the great vessels
Pericardial cavity – between the two layers and contains serous fluid for lubrication

22. Heart Wall 3 layers Epicardium – thin outer layer
Myocardium – thick middle layer made of cardiac muscle
Endocardium – thin inner lining which also lines the heart valves and inner lining of the vessels

23. Heart Chambers
4 chambers – Right / Left Atrium and Right / Left Ventricles
Atrium – Superior chambers
Right Atrium – receives de-oxygenated blood from the Vena Cava (Inf. and Sup.), coronary sinus and cardiac veins
Left Atrium – Posterior to right, receives oxygenated blood from lungs from the pulmonary veins (4 total)
Ventricles – Inferior chambers
Right Ventricle – Lies on diaphragm, receives de-oxygenated blood from the atrium and displaces it to the pulmonary architecture in the lungs
Left Ventricle – Receives oxygenated blood from the left atrium and pumps it into the Aorta

24. Cardiac Valves 4 valves of the heart Atrioventricular (2)
Entrances to ventricles
Tricuspid – right
Bicuspid (Mitral) – left
Semilunar (2)
Ventricles to Great Vessels
Pulmonary semilunar – right
Aortic semilunar - left

25. Blood Path in Heart SVC Rt. Atria Tricuspid Valve Rt. Ventricle
Pulmonary Valve
Pulmonary Artery
Lungs
Pulmonary Veins
Lt. Atrium
Mitral Valve
Left Ventricle
Aortic Valve
Ascending Aorta

26. Great Vessels
Aorta – Largest artery of the body divided into ascending, aortic arch and descending
Ascending - begins at base of left ventricle
Aortic root divides into 3 sinuses for coronary flow
Aortic Arch – ( T-3 ) superior, posterior curve of the ascending aorta located over the right pulmonary artery and the left mainstem bronchus
Descending – passes slightly anterior and to the left of the vertebrae and continues through both the thoracic and abdominal cavities

27. Aorta

28. Great Vessels Branches of Aortic Arch – 3 main branches
Brachiocephalic (Innominate) Artery – First major vessel arising from arch which divides into the right common carotid and right subclavian arteries
Right Common Carotid – extends superiorly until C-4 where it divides into right external and internal carotids
Right subclavian – becomes right axillary artery
Left Common Carotid – Second vessel on arch extends superiorly until C-4 where it divides into left external and internal carotids
Left Subclavian Artery - becomes left axillary artery

29. Aorta / Arterial Network of Neck

30. Great Vessels
Pulmonary Trunk (Artery) – main pulmonary artery lying within the pericardial sac
Arises from the right ventricle and ascends in front of the aorta until T-4 where it bifurcates into the right and left pulmonary arteries
Right pulmonary artery – enters hilum of right lung and divides into 2 branches; upper feeds superior lobe, lower feeds middle and inferior lobes
Left pulmonary artery – shorter and most superior pulmonary vessel; enters hilum of left lung
Both arteries descend and divide into lobar and segmental arteries and continue to branch out into smaller divisions of the pulmonary tree

31. Great Vessels Pulmonary Veins – (4) 2 superior and 2 inferior
Start as capillary network along alveoli and continue to merge until they form a single trunk for each lobe eventually combining until both pairs extend into the left atrium from the lungs

32. Great Vessels Vena Cava – Largest Vein in the body
Superior Vena Cava – formed by junction of brachiocephalic veins and carries blood from thorax, upper limbs, head and neck
Found posterior and lateral to ascending aorta before entering the right atrium
Inferior Vena Cava – formed by junction of common iliac veins in pelvis, ascends through the abdomen to the right of the abdominal aorta

33. Vena Cava

34. Chest Imaging
May be performed to assess the chest and its organs for tumors and other lesions, injuries, intra-thoracic bleeding, infections, unexplained chest pain, obstructions, or other conditions, particularly when another type of examination, such as X-rays or physical examination, is not conclusive
Lung Infiltrates
Surveys for metastatic disease
Parenchyma disease
Pleural disease

35. Preparation Pumonary emboli Mediastinal and hilar masses
Patient is in the supine position and either feet or head first
Arms over the head
Scout from the thoracic inlet to adrenal glands on inspiration
Assess patient to see if they and hold breath for need time
Contrast indications
Pumonary emboli
Mediastinal and hilar masses
Lung infiltrates ( differentiating infiltrate from lung cancer )
Lung nodules
High resolution scans can be done supine and prone

36. Chest Protocol Lung nodules Cancer Vascular disease
Parameters
Single Slice
4 SLICE
16 SLICE
PATIENT
HEAD or FEET FIRST. SUPINE
SAME
SCANNING AREA
APEX TO ADRENAL GLANDS
CONTRAST
100ML AT 45 SECOND DELAY
DETECTOR COLLI NA
4X1MM OR 1.25MM
16X0.75 OR 16X1.25
DFOV
DEPENDS ON PATIENT
SLICE THICKNESS
5 MM
ANGLE
NONE
TABLE FEED/ROT
6MM
VARIES
PITCH
1 OR 1.5
ROT TIME
1 SEC
0.5 SEC
RECON
STANDARD/LUNG
WINDOW
450W/30L—1600W/600L
Lung nodules
Cancer
Vascular disease
Effusion and infiltration
Trauma
Pulmonary Parenchymal diseases
Hilar Masses
Aneurysms,disection,pe Parenchymal- asbestosis,sarcoid,tuberculosis,interstitial lung disease,

37. Chest CT (Lower Neck) 1 – Trachea 1 2 – Jugular Vein 2
3 – Common Carotid
4 – Esophagus 1 2 3 4

38. Apex of Chest 3 2 1 4 1 – Right Subclavian 2 – Right Common Carotid
3 – Left Common Carotid
4 – Clavicle
5 - Scapula 5

39. Main Takeoffs of Heart 2 3 1 1 – SVC 4 2 – Rt. Innominate
3 – Lt. Common Carotid
4 – Lt. Subclavian
5 – Lt. Brachiocephalic Vein 4 5

40. Mag View of Takeoffs and Cava7
1- SVC
2- Brachiolcephalic Artery
3- Lt. Common Carotid Artery
4- Lt. Subclavian Artery
5- Esophagus
6- Trachea
7- Lt.Brachiolcephaic Vein 2 3 1 4 5 6

41. Aortic Arch 2 1
1 – SVC
2 – Aortic Arch
3 – Trachea
4 - Espohagus 3 4

42. Chest Pulmonary Trunk 1 – SVC 2 – Ascending Aorta
3 – Main Pulmonary Trunk
4 – Right Pulmonary Artery
5 – Carina
6 – Descending Aorta
7 – Left Pulmonary Artery 1 3 2 6 4 7 5

43. Chest Mid-Heart 1-Rt.Ventricle 2- Rt.Atrium 3- Aortic Root
4-Lt. Atrium
5- Pulmonary Vein
6-Lt.Ventricle 3 1 2 6 4 5

44. Chest Heart 1 3 2 1 – Rt. Atrium / SVC 2 – Aortic Root
3 – Lt. Ventricle
4 – Rt. Pulmonary Vein
5 – Lt. Atrium 4 5

45. Chest Heart 2 3 1 1 – Right Atrium 4 2 – Aortic Root
3 –Right Ventricle
4 – Left Ventricle
5 – Right Pulmonary Vein
6 – Left Atrium 4 6 5

46. Chest Heart 2 1 3 1 – Right Ventricle 2 – Septum 3 – Left Ventricle
4 – Left Atrium

47. Chest Inferior 2 1 – Liver 2 – Stomach 3 – Descending Aorta 4 – Spleen
5 – Splenic Flexure 1 5 44 3

48. Lung Windows 1 – Posterior segmental bronchus of right upper lobe
2 – Anterior segmental bronchus of right upper lobe
3 – Rt. Mainstem bronchus
4 – Lt. Main Bronchus
5 – Superior lobe Lt. Lung
6 – Inferior Lobe Lt. Lung
From Google…

49. Lung Windows
Nodule

50. Pulmonary Embolism Protocols
Pulmonary Embolism (PE) – sudden blockage in a lung artery, normally from a blood clot traveling to the lungs from the legs (DVT)
Can be fatal as low oxygen levels in the blood could be a by-product of a large clot

51. Pulmonary Embolism Protocols
Considered CTA of Chest (Pulmonary Arteries)
Results are best when MDCT is utilized for exam
Approximately 50 – 150 cc of contrast injected through a large bore IV cannula (generally 18 gauge however 20 gauge can be used) at a rate up to 8 cc per second…(practically 3.5 – 5)
When utilizing bolus tracking, scan is started when intensity of contrast is optimized in a region of interest taken in the main pulmonary artery**
**Localized at level of carina
Generally slices between 0.5 mm to 3 mm are utilized with thinner slices being preferred
Reformats especially in coronal plane

52. Pulmonary Embolism Protocols

53. High Resolution Chest CT
HRCT is utilized for the diagnosis and assessment of Interstitial Lung Disease (ILD)
Ex. Asbestosis, Sarcoidosis, Lupus, Pulmonary Fibrosis
Utilizes narrow slice widths (1 – 2 mm) in sections approximately 10 – 40 mm apart in a axial (conventional) acquisition in a high pass algorithm (Bone/Detail)
Soft tissues generally present a great amount of noise due to the algorithm so it is not utilized for routine diagnosis

54. Effusion and infiltration Trauma Pulmonary Parenchymal diseases
Parameters
Single Slice
4SLICE
16 SLICE
PATIENT
HEAD or FEET FIRST. SUPINE
PRONE FOR ASBESTOSIS
SAME
SCANNING AREA
APEX TO ADRENAL GLANDS
CONTRAST
NONE
DETECTOR COLLI NA
2X0.5MM OR .625MM
1MM
DFOV
SKIN TO SKIN
SLICE THICKNESS
1 MM
ANGLE
TABLE FEED/ROT
10 MM
PITCH
1NA
VARIES
ROT TIME
1 SEC
0.5 SEC
RECON
HIGH RESOLUTION/LUNG
WINDOW
1600W/600L
Lung nodules
Cancer
Vascular disease
Effusion and infiltration
Trauma
Pulmonary Parenchymal diseases
Hilar Masses
PRONE FOR MAXIMUM INFLATION AT BASES

55. High Resolution Chest CT

56. Chest

57. Chest (cont’d)

58. Chest (cont’d)

59. Chest (cont’d)

60. Chest (cont’d)

61. Chest (cont’d)

62. Chest (cont’d)

63. Chest (cont’d)

64. Chest (cont’d)

65. Chest (cont’d)

66. Case Presentation 1. Pulmonary Embolus Protocol 2
Case Presentation 1. Pulmonary Embolus Protocol 2. Hi-Resolution Chest 3. “Low Dose” Chest