BRONCHOPULMONARY SEGMENTS RADIOLOGY AND IMAGING

RADIOLOGY OF LUNG

1. BRONCHOPULMONARY SEGMENTS DR ANTONY SHAJAN

2. LOBAR ANATOMY The Right Lung – 1.Right upper lobe : • Has large anterior projection • three segments-apical,posterior,anterior. 2.Middle lobe • two segments-medial and lateral • Is wedge-shaped in outline 3.Right lower lobe • Lies inferior and posterior to the oblique major fissure • five segments-superior,medial basal,anterior basal,lateral basal,posterior basal.

3. The Left lung 1. Left upper lobe • Is much bigger than the right upper lobe • Has large anterior projection • Supplies four segments-apicoposterior,anterior,superior and inferior lingular • Has a wide cardiac notch anteriorly • Has lingula, which is a small tongue like projection located antero-inferiorly 2. Left lower lobe • Lies inferior and posterior to the oblique major fissure • Supplies four segments-superior,anterior basal,lateral basal,posterior basal.

4. MAIN BRONCHUS LOBAR BRONCHUS SEGMENTAL BRONCHUS TERMINAL BRONCHIOLES RESPIRATORY BRONCHIOLES ALVEOLAR DUCT ALVEOLAR SAC (2-3) (2-11) ( 2-6) TRACHEA THE BRONCHIAL TREE

5. Airways The airways consists of trachea , bronchi , bronchioles and distal small airways . Trachea :Begins at the lower border of cricoid cartilage at the level of C5 vertebra and extends till carina at the level of sternal angle(T5) where it bifurcates. Carina : Anteroposterior ridge at the junction of main bronchi. Right main bronchus : Shorter(2.5cm), larger diameter, more vertical( 45 degrees ), more susceptible to aspiration. Gives 3 lobar bronchi. Left main bronchus: Longer(5 cm),smaller diameter, more horizontal, makes an angle of 45 degrees with trachea. Gives 2 lobar bronchi . Segmental Bronchus divides into smaller airways becomes bronchioles and divide until the terminal bronchiole and the acinus.

6. Bronchopulmonary segments are the independent respiratory units of the lung divided on the basis of the division of the segmental/tertiary bronchi. Definition: Each of the tertiary bronchi serves a specific bronchopulmonary segment . These segments each have their own artery. Thus, each bronchopulmonary segment is supplied by a bronchus, and an artery. Pulmonary veins do not accompany bronchi or pulmonary artery.They run in the intersegmental planes.Thus each segment has more than one vein and each vein drains more than one segment. Segments vary considerably in size and shape, but in general , segments are wedge shaped and radiate from hilum. Unlike the lobes these segments are not separated by the pleura .

7. In 1960, at the seventh international congress of anatomists meeting in New York,a nomenclature was adopted for BPS-THE BOYDEN NUMBERING SYSTEM.

8. BRONCHOPULMONARY SEGMENTS OF RIGHT LUNG Right upper lobe bronchus B1 apical B2 posterior B3 anterior Right middle lobe bronchus B4 lateral B5 medial Right lower lobe bronchus B6 Apical(superior) B7 medial-basal B8 anterior-basal B9 lateral-basal B10 posterior-basal

9. BRONCHOPULMONARY SEGMENTS OF LEFT LUNG Left upper lobe bronchus B1+B2 apico-posterior (merger of "apical" and "posterior") B3 anterior Lingula of left upper lobe B4 superior lingular B5 inferior lingular Left lower lobe bronchus B6 apical(superior) B7 +B8 anteromedial basal (merger of "anterior basal" and "medial basal") B9 lateral basal B10 posterior basal

10. LOCATION OF BPS ON CXR Right upper lobe Apical segment CXR- PA : medially –mediastinum, Laterally-line drawn from the hilum along ant border of 1st rib. CXR- lat :- D2 vertebral body to hilum hilum to outer border of 1st rib.

11. Posterior Segment • CXR PA:line drawn from apex to hilum abutting the outer border of first rib. Another line drawn from hilum to 3rd ICS. • CXR LAT: D2 to hilum and hilum to D4

12. Anterior Segment CXR PA: hilum to outer border of 2nd rib hilum to chest wall along 4th rib. Silhouette sign on ascending aorta. CXR-Lat :horizontal fissure, hilum to 1st rib.

13. Middle Lobe {Lateral & Medial } Segments CXR-PA :horizontal line from hilum to chest wall, lower part of oblique fissure. • Silhouettes rt heart border . CXR-Lat :horizontal line from hilum to 4th costo Chondral junction lower half of oblique fissure.

14. Right lower Lobe Superior basal Segment CXR PA :super imposes on right hilum CXR LAT: Upwards –hilum to posterior border of D4 vertebra Downwards-hilum to D7 vertebra.

15. Medial basal Small triangle shape -posterior ends of 8th to 10th rib . Silhouetting cardio phrenic angle

16. Anterior Basal - Diamond shaped CXRPA: Inf- lat 2/3 of diaph Sup-hilum to lower border of 8 th rib post, Med-hilum to medial 1/3 of diaph Lat :lower part of oblique fissure , ant to mid axillary line

17. Lateral Basal Segment CXR-PA: occupies the costo phrenic angle & Lat 2/3 of Diaphragm CXR LAT: Extends from mid axillary line from D10 to hilum

18. Posterior Basal CXR PA: occupies a Para cardiac rectangle Space, CXR Lat: D7 to hilum Hilum to diaphragm D7 to D10

19. LEFT LUNG Upper Lobe Apico posterior Segment(BI,B2) PA :hilum to 2nd rib. Obliterates the aortic knob. Lat :upper part of oblique fissure , hilum to 2 nd costal cartilage

20. Anterior Segment PA : hilum to 2 nd rib hilum to 4 th rib Lat : hilum to 2 nd costal cartilage hilum to 4 th coastal cartilage.

21. Lingular Segments PA :hilum to 4 th rib, lower part of oblique fissure. Lat :lower part of oblique fissure , hilum to 4th costal cartilage. silhouettes the left cardiac border

22. Left Lower Lobe Superior Segment CXR PA : Oval shape 6 th rib and 8 th rib, CXR Lat :upper part of oblique fissure , D4 to D7, hilum to D7.

23. Anterio-medial Segment Lat; lower part of oblique fissure Anterior to Mid axillary line PA : upper margin , extending from hilum to lower border of 8 the rib. Lower border obliterates lateral 1/3 of diagram and extending up to mid axilla

24. Lateral Basal Segment Lat wedge shape ant and post to mid axillary line.

25. LOCATION OF BPS ON CT SCAN • Most commonly used levels 1.At the level of aortic arch 2.At the level of Lt pulmonary artery level. 3.At the level of Rt pulmonary artery level. 4.At the level of cardiac ventricles

26. AT THE LEVEL OF AORTIC ARCH LEVEL PURELY UPPER LOBE BPS

27. LT PULMONARY ARTERY LEVEL

28. RT PULMONARY ARTERY LEVEL

29. AT THE LEVEL OF CARDIAC VENTRICLES

30. CLINICAL IMPORTANCE Collapse of multiple lobes or segments in certain combinations almost rules out malignancy (RUL+RML ,LLL+LUL, RML+ one segment of RLL ) Exceptions : multi centric neoplasm primary & metastasis

31. Silhoutte sign : is applied to localize parenchymal lesions which can be stated as “an intrathoracic lesion with similar radiologic density is in contiguity with either heart, aorta, or diaphragm and will obliterate the border, as the radiographic contrast is lost.” Right cardiac border – Right middle lobe . Left cardiac border - Lingula Aortic knuckle –Apico posterior segment LUL Right aortic border –Anterior segment of RUL , middle lobe

32. 1. Tuberculosis —apical & posterior segments of upper lobes because of high ventilation perfusion ratios with elevated alveolar PO2 relative to other zones 2. Sequestration of lung-posterior basal segment of lower lobe (left>>right) 3. Cancerous lesion-anterior segments of RUL. 4. Lung abscess —posterior segment of the upper lobe or in the superior or posterior basal segment of the lower lobe, especially on the right lung because of more vertical bronchus and also the aspirated secretions tend to gravitate in these segments in supine position

33. 5.Aspiration pneumonia: apical segments of both lower lobes or posterior segment of the RUL. Bronchiectasis is more common in left lower lobe because of longer and narrower bronchus leading to retained secretions.

34. SUGICAL RESECTION PRINCIPLE: A diseased segment, as it is a structural unit can be removed surgically. During surgical resection, the surgeon works along the segmental veins to isolate a particular segment. Indications: Aspergilloma TB Bronchiectasis Metastatic disease Primary lung cancer

35. Contra indications: Extrinsic segmental compression Presence of endoluminal tumor Prerequisites: complete bronchoscopy Advantages : 1)thorough resection 2)better staging 3)decreasing local recurrence

36. THANK YOU…