HRCToflung

IN THE NAME OF GOD,ANATOMY,1-tracheal,2-main,3-lobar,4-segmental bronchial,5- bronchioles Bronchi gradually lose their cartilaginous support between generations 1 and 12 to 15.,bronchioles,these 1- to 3-mm airways,6-terminal bronchiole,7-respiratory bronchioles.,8-alveolar ducts,9-alveolar sacs,ANATOMY,The trachea is approximately 12 cm long in adults, with an upper limit of normal coronal tracheal diameter of 23 mm in men and 20 mm in women,The right main bronchus is considerably shorter than the left main bronchus (mean lengths of 2.2 cm and 5 cm, respectively,It commences at the larynx(at the level vertebral level of C6 in humans) and bifurcates into the primary (main) bronchi (at the vertebral level of T4/T5 in humans) in mammals,ANATOMY,In average, a total of 21 to 25 generations are found between the trachea and the alveoli.,ANATOMY,The middle lobe bronchus arises from the intermediate bronchus and divides into medial and lateral segmental branches,RLL It is subdivided into a superior segment and four basal segments: anterior, lateral, p osterior, and medial.,LLL has a superior segment and three basal segments: anterior lateral, and posterior,LULThe LUL is subdivided into four segments: anterior, apicoposterior, and the superior and inferior lingular,The LUL is subdivided into four segments: anterior, apicoposterior, and the superior and inferior lingular,ANATOMY,Fig. 1.14 The anatomy of the main bronchi and segmental divisions.Nomenclature approved by the Thoracic Society (reproduced by permissionof the Editors of Thorax,Fig. 21(a) The segments of the right lung. (b) The segments of the left lung.,ANATOMY,It is a continuous network of connective tissue fibers that begins at the lung hilum and extends peripherally to the visceral pleura (see Fig. 12.10).,pulmonary interstitium,The pulmonary interstitium is the scaffolding of the lung,providing support for the airways, gas-exchanging units, and vascular structures,ANATOMY,pulmonary Interstitial Compartments of the Lung,1-Bronchovascular interstitium surrounds the bronchovascular bundle 2-Centrilobular interstitium (surrounds the distal bronchiolovascular bundle) 3-SubPleural interstitium 4-Interlobular septal interstitium (often seen as lines perpendicular to the pleura) 5- intralobular, parenchymal, or alveolar interstitium.,ANATOMY,interstitium from the mediastinum peripherally and enveloping the bronchovascular bundles is termed the axial or bronchovascular interstitium,Interstitial Compartments of the Lung,1-Bronchovascular interstitium,ANATOMY,The axial interstitium is contiguous with the interstitium surrounding the small centrilobular arteriole and bronchiole within the secondary pulmonary lobule, where it is called the centrilobular interstitium,Interstitial Compartments of the Lung,2-Centrilobular interstitium (surrounds the distal bronchiolovascular bundle),ANATOMY,The most peripheral component of the interstitium is the subpleural or peripheral interstitium, which lies between the visceral pleura and the lung surface,Invaginations of the subpleural interstitium into the lung parenchyma form the borders of the secondary pulmonary lobules and represent the interlobular septa,Interstitial Compartments of the Lung,3-SubPleural interstitium,ANATOMY,4-Interlobular septal interstitium,Interstitial Compartments of the Lung,ANATOMY,The subpleural interstitium and interlobular septa are parts of the peripheral interstitium, which divides secondary pulmonary lobules,Invaginations of the subpleural interstitium into the lung parenchyma form the borders of the secondary pulmonary lobules and represent the interlobular septa,Extending between the centrilobular interstitium within the lobular core and the interlobular septal/subpleural interstitium in the lobular periphery is a fine network of connective tissue fibers that support the alveolar spaces called the intralobular, parenchymal, or alveolar interstitium.,ANATOMY,5- intralobular, parenchymal, or alveolar interstitium.,Interstitial Compartments of the Lung,ANATOMY secondary pulmonary lobule,The secondary pulmonary lobule is defined as that subsegment of lung supplied by three to five terminal bronchioles and separated from adjacent secondary lobules by intervening connective tissue (interlobular septa),The secondary lobule is between 1.0 and 2.5 cm in size and isthe smallest discrete unit of lung tissue surrounded by connectivetissue septa.,the functioning lung unit, is that portion of the lung ARISING FROM TERMINAL BRONCHIOL,ANATOMY ACINUS,ANATOMY,small pulmonary arteries and veins,ANATOMY,HRCT technique involves incremental thinly collimated scans (1.0 to 1.5 mm) obtained at evenly spaced intervals through the thorax for the evaluation of diffuse bronchial or parenchymal lung disease,Expiratory HRCT scans are useful for the detection of air trapping in patients with small airways disease,Routine settings for CT display of mediastinal structures are window width WW = 400 and window level WL = 40 and for the lungs are WW = 1,500 and WL = 700.,Scanning is usually obtained in the supine position at full inspiration, but prone and expiratory images are sometimes obtained,IV contrast is not used for high-resolution CT examinations that are limited to evaluating the lung parenchyma,HRCT,Figure 2: Radiograph of 1-mm lung slice taken from peripheral lower lobe. Two well-defined secondary pulmonary lobules are visible. Lobules are marginated by thin interlobular septa (S) containing pulmonary vein (V) branches. Bronchioles (B) and pulmonary arteries (A) are centrilobular. (Reprinted, with permission, from reference 10.),Normal HRCT Findings,HRCT,Normal HRCT Findings,/cgi/content/full/239/2/322?maxtoshow=&HITS=20&hits=20&RESULTFORMAT=&searchid=1&FIRSTINDEX=0&displaysectionid=Reviews&resourcetype=HWCIT,The centrilobular bronchiole, with a diameter of 1 mm and a wall thickness of 0.15 mm, is not normally visible on HRCT,The peribronchovascular, centrilobular, and intralobular interstitial compartments are not normally visible on HRCT.,HRCT,Normal HRCT Findings,More peripherally, numerous small dots and a few branching lines represent small pulmonary arteries and veins. Throughout, arteries branch at acute angles, and veins branch at 90 angles,Centrilobular arteries (1 mm in diameter) are V- or Y-shaped structures on HRCT seen within 5 to 10 mm of the pleural surface.,Pulmonary veins (0.5 cm) are occasionally seen as linear or dotlike structures within 1 to 2 cm of the pleura and, when visible, indicate the locations of interlobular septa,small pulmonary arteries and veins,HRCT,The centrilobular bronchiole, with a diameter of 1 mm and a wall thickness of 0.15 mm, is not normally visible on HRCT.,Normal airways are visible only to within 3 cm of the pleura.,Normal HRCT Findings,airways,HRCT,Normal HRCT Findings,These lines are not normally visible on HRCT and represent thickening of the intralobular or parenchymal interstitium,Lymphangitic Carcinomatosis,Intralobular Lines:,HRCT,Normal HRCT Findings,FIGURE 17.2. HRCT of Normal Lobular Anatomy. Normal interlobular septa (solid black arrows) and centrilobular arteries (open white arrows) are clearly visible,Interlobular septa are normally 0.1 mm thick and can be seen in the lung periphery, particularly along the anterior and mediastinal pleural surfaces (Fig. 17.2).,Interlobular septa,HRCT,Normal HRCT Findings Fissural Anatomy,FIGURE 12.7. Fissural Anatomy on HRCT. The oblique fissures appear as thin curvilinear lines (solid arrows) concave anteriorly in the upper thorax (A), flat lines in the midthorax (B), and convex anterior lines in the lower chest (C). The apex of the domed minor fissure is seen as an avascular zone in the midthorax (open arrow in B).,Normal HRCT Findings Fissural Anatomy,FIG. 10-14. Normal HRCT.A. The lung appears homogeneous in attenuation, with posterior lung appearing slightly denser than anterior lung. Fissures are smooth and uniform in thickness. Vessels are smooth in contour and sharply marginated. The most peripheral vessels visible are 5 to 10 mm from the pleural surface and represent centrilobular arteries or, sometimes, veins in interlobular septa. Centrilobular bronchioles and interlobular septa are not visible.B.Coned-down HRCT of the left lower lobe. Two pulmonary lobules are outlined by pulmonary veins within interlobularseptae (black arrows). Centrilobular arteries are visible as dots (white arrows).,Normal HRCT Findings,HRCT,Fig. 2.10af. HRCT of the normal lung at upper and middle levels in supine and at lower level in prone body position (a,c,e,suspended deep inspiration; b,d,f, same levels, suspended deep expiration). Note the density gradient between the dependentand the nondependent lung, which is larger on expiratory scans than on inspiratory scans,Normal HRCT Findings,HRCT,In many normal subjects, one or more areas of air-trapping are seen on expiratory scans (Fig. 2.11).In these areas, lung does not increase as much in attenuation as expected and as seen in the surrounding normal areas and appears relatively lucent. This relative lucency is most typically seen in the superior segments of the lower lobes, posterior to the major fissures, and in the anterior part of the middle lobe and lingua. Often, however, only individual pulmonarylobules are involved, particularly in the lowerlobes (Lee et al. 2000; Webb et al. 1993). Focal areas of air-trapping are seen in up to 75% of asymptomatic subjects, especially in older patients (Chen et al. 1998; Lee et al. 2000) and in smokers or ex-smokers (Verschakelen et al. 1998).,Fig. 2.11. In many healthy subjects, one or moreareas of air-trapping can be seen on expiratoryscans, particularly in the lower lobes. Usuallyonly one or a few lobules are involved (arrows),Normal HRCT Findings,HRCT,Interlobular lines on HRCT are the equivalent of Kerley B lines seen in the inferolateral portions of the lungs on frontal radiographs. Within the central regions of the lung, long (2 to 6 cm) linear opacities representing obliquely oriented connective tissue septa can be seen, which are the equivalent of radiographic Kerley A lines,Figure 2. High resolution CT at the level of the lower lobes demonstrates smooth thickening of interlobular septa (arrow) and subtle ground-glass opacities (arrowhead).,Normal HRCT Findings,HRCT,In the image compare the irregularly thickened interstitial compartments in the right lung to the normal, mostly invisible counterparts in the left lung (R = right lung; L = left lung),compare Normal& abnormal HRCT Findings,HRCT,compare Normal& abnormal HRCT Findings,HRCT,Compare,WHAT IS YOURS FINDING ?,HRCT,Dependent Atelectasis,HRCT,1-what is the dominant HR pattern?,B- low attenuation (CTscan findings manifesting as decreased opacity),A- High attenuation (CTscan findings manifesting as increase opacity),(is there an upper versus lower zone or a central versus pripheral prodominance),(plura fluid,lymphadenopathy),2-Where is distribution within lung?,3-Are there additional findings?,HRCT,B- LOW attenuation (CTscan findings manifesting as decreased opacity),what is the dominant HR pattern?,A- High attenuation (CTscan findings manifesting as increase opacity),3 - GROUND GLASS OPACITY,2-NODULES,1- LINEAR ABNORMALITIES,4 - CONSOLIDATIN,1-AREAS OF DECREASED ATTENUATION WITH WALLS( CYSTS ; HONEYCOMB ; BRONSHECTASIA ),2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS(EMPHYSEMA ,MOSAIC PERFUSION ),HRCT,FIGURE 17.3. HRCT Findings in Interstitial Lung Disease,1- Interlobular (Septal) Lines,2-Intralobular Lines,3-Thickened Fissures,4-Thickened bronchovascular structures,5-Centrilobular (Lobular Core) Abnormalities,6- Subpleural lines,7-Parenchymal bands,8-Honeycombing,9-Thin-walled cysts,10-Irregularity of Lung Interfaces,11-Ground-Glass or Hazy Increased Density,12-Architectural Distortion and Traction Bronchiectasis,13-Conglomerate Masses,14-Consolidation,Dot lik,tree-in-bud,lldefined,A-LINEAR,B-nodular,C- high attenuation),1-thickened inter lobular septa,4-bronchovascular interstitial thickening,6-Parenchymal bands,5-Subpleural lines,3-Thickened Fissures,2-Intralobular Lines,4-The larger nodular densities,The tiny nodules (1 to 2 mm in size),b-perilymphatic,c-random,2-consolidation,1-ground-glass,Conglomerate Masses,2-Dot lik,3-tree-in-bud,1-Illdefined centrilobular nodules,HRCT,a-centrilobular,A- High attenuation (CTscan findings manifesting as increase opacity),A-Linear Abnormalities,1-thickened interlobular septa,4-bronchovascular interstitial thickening,6-Parenchymal bands,5-Subpleural lines,3-Thickened Fissures,HRCT,2-Intralobular Lines,A- High attenuation (CTscan findings manifesting as increase opacity),WHAT IS DOMINANT PATTERN ?,HRCT,1- Interlobular (Septal) Lines,Figure 6: Interlobular septal thickening in pulmonary edema. Transverse thin-section CT scan shows thickened septa (small arrows) in upper lobes. Smooth thickening of interlobular septa outline a number of secondary pulmonary lobules. Visible lobules vary in size, at least partly because of the position of lobules relative to the scan plane. Pulmonary veins (large arrows) in septa are visible as small rounded dots or linear or branching opacities. Septa are well developed in the apices, and septal thickening is often well depicted in this region,A-Linear Abnormalities,HRCT,1- Interlobular (Septal) Lines,FIGURE 17.4. Interlobular Septal Lines in Lymphangitic Carcinomatosis. An HRCT scan through the upper lobes in a patient with lymphangitic carcinomatosis shows thickened interlobular septa (small arrow). Note the presence of nodular fissural thickening (large arrows), another common finding in this entity.,A-Linear Abnormalities,D.D: 1-Interstitial edema2-Lymphangitic carcinomatosis3-Sarcoidosis4-Idiopathic pulmonary fibrosis (IPF),HRCT,WHAT IS DOMINANT PATTERN ?,HRCT,1- Interlobular (Septal) Lines,Focal septal thickening in lymphangitic carcinomatosis,A-Linear Abnormalities,HRCT,WHAT IS DOMINANT PATTERN ?,2-Intralobular Lines,Figure 7a.Methotrexate-induced NSIP in a 41-year-old woman with rheumatoid arthritis who presented with dyspnea and decreased diffusing capacity of the lungs for carbon monoxide (DLCO). (a) High-resolution CT scan shows scattered ground-glass attenuation and thickened inter- and intralobular lines (arrow).,a lattice of fine lines is seen within the central portion of the pulmonary lobule radiating out toward the thickened lobular borders to produce a spoke-and-wheel or spiderweb appearance.,A-Linear Abnormalities,Intralobular lines: 1-IPF (UIP) 2- Asbestosis 3- Alveolar proteinosis4-Hypersensitivity pneumonitis (chronic),WHAT IS DOMINANT PATTERN ?,HRCT,FIGURE 17.5. Intralobular Lines in Idiopathic Pulmonary Fibrosis (IPF). A targeted HRCT through the right lower lobe in a patient with IPF shows thickening of intralobular (long arrows) and interlobular (arrowheads) lines associated with ground-glass opacity.,2- Intralobular Lines,A-Linear Abnormalities,Intralobular lines: 1-IPF (UIP) 2- Asbestosis 3- Alveolar proteinosis4-Hypersensitivity pneumonitis (chronic),WHAT IS DOMINANT PATTERN ?,2- Intralobular Lines,A-Linear Abnormalities,WHAT IS DOMINANT PATTERN ?,2- Intralobular Lines,Alveolar proteinosis,Intralobular lines usually represent fibrosis and are most commonly seen in idiopathic pulmonary fibrosis (IPF) and other forms of usual interstitial pneumonia (UIP).,A-Linear Abnormalities,WHAT IS DOMINANT PATTERN ?,3- Thickened Fissures,FIGURE 17.4. Interlobular Septal Lines in Lymphangitic Carcinomatosis. An HRCT scan through the upper lobes in a patient with lymphangitic carcinomatosis shows thickened interlobular septa (small arrow). Note the presence of nodular fissural thickening (large arrows), another common finding in this entity.,A-Linear Abnormalities,Thickened Fissures : 1-Pulmonary edema2-Sarcoidosis 3-Lymphangitic carcinomatosis,WHAT IS DOMINANT PATTERN ?,4-Thickened bronchovascular structures,Lymphangitic carcinomatosis can result in either smooth or irregular peribronchovascular thickening, although the former is more common (Fig. 17.6).,FIGURE 17.6. Thickened Bronchovascular Structures in Lymphangitic Carcinomatosis. In a patient with lymphangitic carcinomatosis, an HRCT shows both smooth and nodular thickening of the bronchovascular structures (arrows) that represents lymphatic tumor surrounding the axial interstitium.,A-Linear Abnormalities,4-Thickened bronchovascular structures,Lymphangitic carcinomatosis can result in either smooth or irregular peribronchovascular thickening, although the former is more common (Fig. 17.6).,This produces apparent enlargement of perihilar vascular structures and thickening of bronchial walls, which is the HRCT equivalent of peribronchial cuffing and tram tracking seen radiographically,A-Linear Abnormalities,Thickened bronchovascular structures: 1-Pulmonary edema (smooth 2-Sarcoidosis (nodular)3-Lymphangitic carcinomatosis (smooth or nodular),WHAT IS DOMINANT PATTERN ?,5-Subpleural lines,These 5- to 10-cm-long curvilinear opacities are found within 1 cm of the pleura and parallel the chest wall.,This finding, which probably represents an early phase of lung fibrosis, should be distinguished from a similar line that is seen as a result of atelectasis in the dependent portion of the lungs in normal individuals,/cgi/reprint/36/6/677.pdf,FIG 3*Prone HRCT of a 31 yr/ old male demonstrates non specific subpleural band opacities bilaterally arrows# Lung parenchyma is otherwise normal,A-Linear Abnormalities,Subpleural lines: 1-Asbestosis 2-IPF (UIP),WHAT IS DOMINANT PATTERN ?,6-Parenchymal bands,(b) Scan obtained on day 18 of illness shows mixed pattern that developed, with bandlike and angled consolidation (arrowheads) in right lung base and parenchymal bands (arrows) in the left lung base,/cgi/content/full/230/3/836,Parenchymal bands are nontapering linear opacities, 2 to 5 cm in len