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 LULThe LUL is subdivided into four segments: anterior, apicoposterior, and the superior and inferior lingular The middle lobe bronchus arises from the intermediate bronchus and divides into medial and lateral segmental branches The LUL is subdivided into four segments: anterior, apicoposterior, and the superior and inferior lingular LLL has a superior segment and three basal segments: anterior lateral, and posterior RLL It is subdivided into a superior segment and four basal segments: anterior, lateral, p osterior, and medial.

ANATOMY Fig. 1.14 The anatomy of the main bronchi and segmental divisions.Nomenclature approved by the Thoracic Society (reproduced by permission of the Editors of Thorax

ANATOMY Fig. 21◊(a) The segments of the right lung. (b) The segments of the left lung.

pulmonary interstitium ANATOMY pulmonary interstitium The pulmonary interstitium is the scaffolding of the lung providing support for the airways, gas-exchanging units, and vascular structures 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 Interstitial Compartments of the Lung 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.

Interstitial Compartments of the Lung ANATOMY Interstitial Compartments of the Lung 1-Bronchovascular interstitium interstitium from the mediastinum peripherally and enveloping the bronchovascular bundles is termed the axial or bronchovascular interstitium

Interstitial Compartments of the Lung ANATOMY Interstitial Compartments of the Lung 2-Centrilobular interstitium (surrounds the distal bronchiolovascular bundle) 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 ANATOMY Interstitial Compartments of the Lung 3-SubPleural interstitium 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 ANATOMY Interstitial Compartments of the Lung 4-Interlobular septal interstitium Invaginations of the subpleural interstitium into the lung parenchyma form the borders of the secondary pulmonary lobules and represent the interlobular septa The subpleural interstitium and interlobular septa are parts of the peripheral interstitium, which divides secondary pulmonary lobules

ANATOMY Interstitial Compartments of the Lung 5- intralobular, parenchymal, or alveolar interstitium. 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 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 is the smallest discrete unit of lung tissue surrounded by connective tissue septa.

ANATOMY ACINUS the functioning lung unit, is that portion of the lung ARISING FROM TERMINAL BRONCHIOL

ANATOMY

ANATOMY small pulmonary arteries and veins

HRCT 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 Scanning is usually obtained in the supine position at full inspiration, but prone and expiratory images are sometimes obtained 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. IV contrast is not used for high-resolution CT examinations that are limited to evaluating the lung parenchyma

Normal HRCT Findings 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 The centrilobular bronchiole, with a diameter of 1 mm and a wall thickness of 0.15 mm, is not normally visible on HRCT http://radiology.rsnajnls.org/cgi/content/full/239/2/322?maxtoshow=&HITS=20&hits=20&RESULTFORMAT=&searchid=1&FIRSTINDEX=0&displaysectionid=Reviews&resourcetype=HWCIT The peribronchovascular, centrilobular, and intralobular interstitial compartments are not normally visible on HRCT.

Normal HRCT Findings HRCT small pulmonary arteries and veins 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

Normal HRCT Findings HRCT airways Normal airways are visible only to within 3 cm of the pleura. The centrilobular bronchiole, with a diameter of 1 mm and a wall thickness of 0.15 mm, is not normally visible on HRCT.

Normal HRCT Findings HRCT Intralobular Lines: These lines are not normally visible on HRCT and represent thickening of the intralobular or parenchymal interstitium Lymphangitic Carcinomatosis

Normal HRCT Findings HRCT Interlobular septa 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). FIGURE 17.2. HRCT of Normal Lobular Anatomy. Normal interlobular septa (solid black arrows) and centrilobular arteries (open white arrows) are clearly visible

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

HRCT Normal HRCT Findings 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 interlobular septae (black arrows). Centrilobular arteries are visible as dots (white arrows).

HRCT Normal HRCT Findings Fig. 2.10a–f. 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 dependent and 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 pulmonary lobules 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 more areas of air-trapping can be seen on expiratory scans, particularly in the lower lobes. Usually only 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).

HRCT compare Normal& abnormal HRCT Findings 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)

HRCT compare Normal& abnormal HRCT Findings

HRCT Compare WHAT IS YOURS FINDING ?

Dependent Atelectasis HRCT Dependent Atelectasis

2-Where is distribution within lung? HRCT 1-what is the dominant HR pattern? A- High attenuation (CTscan findings manifesting as increase opacity) B- low attenuation (CTscan findings manifesting as decreased opacity) 2-Where is distribution within lung? (is there an upper versus lower zone or a central versus pripheral prodominance) 3-Are there additional findings? (plura fluid,lymphadenopathy)

HRCT what is the dominant HR pattern? A- High attenuation (CTscan findings manifesting as increase opacity) 1- LINEAR ABNORMALITIES 2-NODULES 3 - GROUND GLASS OPACITY 4 - CONSOLIDATIN B- LOW attenuation (CTscan findings manifesting as decreased opacity) 1-AREAS OF DECREASED ATTENUATION WITH WALLS( CYSTS ; HONEYCOMB ; BRONSHECTASIA ) 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS(EMPHYSEMA ,MOSAIC PERFUSION )

FIGURE 17.3. HRCT Findings in Interstitial Lung Disease 1- Interlobular (Septal) Lines 2-Intralobular Lines 3-Thickened Fissures 4-Thickened bronchovascular structures Dot lik 5-Centrilobular (Lobular Core) Abnormalities tree-in-bud lldefined 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

HRCT B-nodular A-LINEAR C- high attenuation) A- High attenuation (CTscan findings manifesting as increase opacity) B-nodular C- high attenuation) A-LINEAR 1-thickened inter lobular septa 1-Illdefined centrilobular nodules 2-Dot lik 3-tree-in-bud 2-Intralobular Lines 1-ground-glass 3-Thickened Fissures a-centrilobular 2-consolidation 4-bronchovascular interstitial thickening b-perilymphatic c-random, 5-Subpleural lines 4-The larger nodular densities The tiny nodules (1 to 2 mm in size) 6-Parenchymal bands Conglomerate Masses

HRCT A-Linear Abnormalities A- High attenuation (CTscan findings manifesting as increase opacity) A-Linear Abnormalities 1-thickened interlobular septa 2-Intralobular Lines 3-Thickened Fissures 4--bronchovascular interstitial thickening 5-Subpleural lines 6-Parenchymal bands

HRCT WHAT IS DOMINANT PATTERN ?

1- Interlobular (Septal) Lines HRCT A-Linear Abnormalities 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

1- Interlobular (Septal) Lines HRCT A-Linear Abnormalities 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. D.D: 1-Interstitial edema 2-Lymphangitic carcinomatosis 3-Sarcoidosis 4-Idiopathic pulmonary fibrosis (IPF)

HRCT WHAT IS DOMINANT PATTERN ?

1- Interlobular (Septal) Lines A-Linear Abnormalities 1- Interlobular (Septal) Lines Focal septal thickening in lymphangitic carcinomatosis

HRCT WHAT IS DOMINANT PATTERN ?

2-Intralobular Lines A-Linear Abnormalities 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. Intralobular lines: 1-IPF (UIP) 2-  Asbestosis 3-  Alveolar proteinosis 4-Hypersensitivity pneumonitis (chronic)

HRCT WHAT IS DOMINANT PATTERN ?

2- Intralobular Lines A-Linear Abnormalities 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. Intralobular lines: 1-IPF (UIP) 2-  Asbestosis 3-  Alveolar proteinosis 4-Hypersensitivity pneumonitis (chronic)

WHAT IS DOMINANT PATTERN ?

A-Linear Abnormalities 2- Intralobular Lines

WHAT IS DOMINANT PATTERN ?

2- Intralobular Lines A-Linear Abnormalities 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).

WHAT IS DOMINANT PATTERN ?

3- Thickened Fissures A-Linear Abnormalities 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. Thickened Fissures : 1-Pulmonary edema 2-Sarcoidosis 3- Lymphangitic carcinomatosis

WHAT IS DOMINANT PATTERN ?

4-Thickened bronchovascular structures 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). 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.

4-Thickened bronchovascular structures A-Linear Abnormalities 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 Thickened bronchovascular structures: 1-Pulmonary edema (smooth 2-Sarcoidosis (nodular) 3-Lymphangitic carcinomatosis (smooth or nodular) Lymphangitic carcinomatosis can result in either smooth or irregular peribronchovascular thickening, although the former is more common (Fig. 17.6).

WHAT IS DOMINANT PATTERN ?

5-Subpleural lines A-Linear Abnormalities FIG[ 3[*Prone HRCT of a 31 yr/ old male demonstrates non specific subpleural band opacities bilaterally "arrows#[ Lung parenchyma is otherwise normal 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 Subpleural lines: 1-Asbestosis  2-IPF (UIP) http://rheumatology.oxfordjournals.org/cgi/reprint/36/6/677.pdf

WHAT IS DOMINANT PATTERN ?

6-Parenchymal bands A-Linear Abnormalities (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 Parenchymal bands are nontapering linear opacities, 2 to 5 cm in length, that extend from the lung to contact the pleural surface These fibrotic bands can be distinguished from vessels and thickened septa by their length, thickness, course, absence of branching, and their association with regional parenchymal distortion Parenchymal bands: 1-Asbestosis 2-IPF (UIP) 3-sarcoidosis http://radiology.rsnajnls.org/cgi/content/full/230/3/836

WHAT IS DOMINANT PATTERN ?

6- Parenchymal bands A- Linear Abnormalities Figure 2   Non-specific interstitial pneumonia in a 48 year old woman (patient 2). (A) Initial CT scan showing irregular areas of consolidation with bronchovascular bundle thickening and patchy areas of ground glass attenuation. (B) CT scan obtained at one year follow up showing improvement of lesions. Slight areas of ground glass attenuation and parenchymal bands are seen.    

HRCT B-nodular A-LINEAR C- others A- High attenuation (CTscan findings manifesting as increase opacity) B-nodular C- others A-LINEAR 1-thickened inter lobular septa 1-Dot lik 2-iIldefined 3-tree-in-bud 1-ground-glass 2-Intralobular Lines 2-consolidation 3-Thickened Fissures 4-bronchovascular interstitial thickening a-centrilobular 3- Irregularity of Lung Interfaces b-perilymphatic c-random, 5-Subpleural lines 4-The larger nodular densities The tiny nodules (1 to 2 mm in size) 6-Parenchymal bands Conglomerate Masses

WHAT IS DOMINANT PATTERN ?

B-Nodules Appearance patterns: Nodular: Small, well-defi ned nodules Soft-tissue density (interstitial nodules)

HRCT WHAT IS DOMINANT PATTERN ?

B-Nodules 1-Dotlike Fig. 6.21a,b. (Peri)lymphatic (a) vs centrilobular (b) distribution of disease. (a) Patient with sarcoidosis showing numerous subpleural and fissural nodules. Since nodules are also found in other areas where lymphatics are located (peribronchovascular interstitium, interlobular septa and centrilobular) diagnosis of disease with a (peri)lymphatic distribution can be made. (b) Patient with infectious bronchiolitis (tuberculosis) showing centrilobular changes (nodules, branching lines and tree-in-bud), suggesting disease that predominantly involves the airways DOTLIKE : 1-pulmonary edema, 2-lymphangitic carcinomatosis, and 3-UIP

HRCT WHAT IS DOMINANT PATTERN ?

HRCT B-Nodules 2- Ill-defined (Ground-Glass) centrilobular nodules FIGURE 17.7. Centrilobular Ground-Glass Nodules in Subacute Hypersensitivity Pneumonitis. HRCT shows the typical poorly defined centrilobular nodules (arrows) of subacute hypersensitivity pneumonitis (bird-fancier's lung). Caption: Picture 5. High-resolution chest CT scan of a patient with hypersensitivity pneumonitis demonstrates centrilobular nodules. These nodules are unlike those of sarcoidosis, in which the nodules are subpleural and along peribronchovascular interstitium Ill-defined (Ground-Glass) centrilobular nodules represent disease of the bronchiole and adjacent parenchyma : 1- subacute hypersensitivity pneumonitis 2-cryptogenic organizing pneumonia (COP),

HRCT WHAT IS DOMINANT PATTERN ?

HRCT B-Nodules 3-tree-in-bud appearance Figure 2.  Postprimary active tuberculosis in a 66-year-old woman with a chronic cough. High-resolution CT scans of the right lung show peripheral, poorly defined, small (2–4-mm-diameter) centrilobular nodules and branching linear opacities of similar caliber originating from a single stalk (the tree-in-bud pattern) in the lower lobe (arrow)

HRCT Nodules 3- tree-in-bud appearance Small airways disease can produce centrilobular bronchiolar abnormalities, which are seen on HRCT as fluid-filled dilated branching Y-shaped structures Figure 1.  High-resolution CT scan (far left) and drawings of the lung (middle left), a budding tree (middle right), and tree buds (far right) show the tree-in-bud pattern http://radiographics.rsnajnls.org/cgi/content/full/25/3/789/F5A

Centrilobular (Lobular Core) Abnormalities HRCT B-Nodules Centrilobular (Lobular Core) Abnormalities Tree-in-bud almost always indicates the presence of: Endobronchial spread of infection (TB, MAC, any bacterial bronchopneumonia) Airway disease associated with infection (cystic fibrosis, bronchiectasis) less often, an airway disease associated primarily with mucus retention (allergic bronchopulmonary aspergillosis, asthma). (Mycobacterium Avium Complex Disease) Typical Tree-in-bud appearance in a patient with active TB.

HRCT Nodules Ill-defined centrilobular nodules tree-in-bud appearance Dotlike Tree-in-bud almost always indicates the presence of: Endobronchial spread of infection (TB, MAC, any bacterial bronchopneumonia) Airway disease associated with infection (cystic fibrosis, bronchiectasis) less often, an airway disease associated primarily with mucus retention (allergic bronchopulmonary aspergillosis, asthma). represent disease of the bronchiole and adjacent parenchyma pulmonary edema, lymphangitic carcinomatosis, and UIP in subacute hypersensitivity pneumonitis (Fig. 17.7), cryptogenic organizing pneumonia (COP), and other disorders. Centrilobular nodules: 1- Hypersensitivity pneumonitis 2-Bronchiolitis obliterans with organizing pneumonia (BOOP)/cryptogenic organizing pneumonia (COP) 3-Respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)

HRCT B-nodular A-LINEAR C- others A- High attenuation (CTscan findings manifesting as increase opacity) B-nodular C- others A-LINEAR 1-thickened inter lobular septa 1-Dot lik 2-iIldefined 3-tree-in-bud 1-ground-glass 2-Intralobular Lines 2-consolidation 3-Thickened Fissures 4-bronchovascular interstitial thickening a-centrilobular b-perilymphatic c-random, 5-Subpleural lines 4-The larger nodular densities The tiny nodules (1 to 2 mm in size) 6-Parenchymal bands Conglomerate Masses

B-Nodules Nodular distribution

HRCT B-Nodules

HRCT B-Nodules Algorithm for nodular pattern

HRCT 1-WHAT IS DOMINANT PATTERN ? 2- Where is it distribution within lung

HRCT Nodules perilymphatic distribution Figure 5a. (a) Thin-section CT image shows perilymphatic nodules in the lungs of a patient with sarcoidosis. There are many nodules,, along the right major fissure and lateral pleural surface; the patchy distribution distinguishes perilymphatic from random nodules. Note the beading of visible peripheral arterial structures (arrows) that is typical of axial interstitial disease perilymphatic distribution

HRCT B-Nodules sarcoidosis Nodules predominating in the peribronchovascular, interlobular, and subpleural regions those portions of the interstitium where the lymphatics lie are said to have a perilymphatic distribution Sarcoidosis: typical presentation with nodules along the bronchovascular bundle and fissures Notice the partially calcified node in the left hilum.

HRCT 1-WHAT IS DOMINANT PATTERN ? 2- Where is it distribution within lung

HRCT sarcoidosis

1-WHAT IS DOMINANT PATTERN ? 2- Where is it distribution within lung

LEFT: miliary TB RIGHT: metastases Differential diagnosis of TB Miliary TB: metastases of medullary thyroid ca, chorion ca and melanoma. In both miliary TB and metastases the nodules have a random distribution. In miliary TB the nodules are more uniform in size.

HRCT WHAT IS DOMINANT PATTERN ?

HRCT B-Nodules 4-Conglomerate Masses FIGURE 17.10. Nodules and a Conglomerate Mass in Silicosis. A. Posteroanterior radiograph of a 79-year-old patient with silicosis shows diffuse nodules as well as a conglomerate mass in the right upper lobe (arrow). B. HRCT scan through the upper lobes shows peribronchovascular and subpleural micronodules (small arrows), larger nodules (curved arrow), and a conglomerate mass representing progressive massive fibrosis in the right upper lobe (large arrow). The pleural effusions are caused by concomitant congestive heart failure. Conglomerate Masses: 1- Sarcoidosis 2-Silicosis  3-CWP  4-Radiation fibrosis These conglomerate masses are most often seen in patients with end-stage sarcoidosis but can occur in complicated silicosis with progressive massive fibrosis (PMF) (Fig. 17.10) or radiation fibrosis

HRCT 4-Conglomerate Masses B-Nodules A similar finding is seen rarely in intravenous drug users when a granulomatous fibrosis results as a response to intravenous talc or starch mixed with narcotics.

HRCT B-nodular A-LINEAR C- high attenuation) A- High attenuation (CTscan findings manifesting as increase opacity) B-nodular C- high attenuation) A-LINEAR 1-thickened inter lobular septa 1-Dot lik 2-Illdefined centrilobular nodules 3-tree-in-bud 2-Intralobular Lines 1-ground-glass 3-Thickened Fissures 2-consolidation a-centrilobular 4-bronchovascular interstitial thickening b-perilymphatic c-random, 5-Subpleural lines 4-The larger nodular densities The tiny nodules (1 to 2 mm in size) 6-Parenchymal bands Conglomerate Masses

HRCT WHAT IS DOMINANT PATTERN ?

C-Ground-Glass or Hazy Increased Density A- High attenuation (CTscan findings manifesting as increase opacity) C-Ground-Glass or Hazy Increased Density FIGURE 17.11. Ground-Glass Opacity in Acute Hypersensitivity Pneumonitis. An HRCT through the upper lobes shows confluent ground-glass opacity in a patient with hypersensitivity pneumonitis. Note that the pulmonary vessels are still visible within the areas of abnormality. The presence of ground-glass opacities is important because it often implies an active inflammatory process or edema that is reversible and warrants aggressive treatment Ground-glass opacities: 1-UIP  2-Desquamative interstitial pneumonia  3-Acute interstitial pneumonia (AIP)  4-Hypersensitivity pneumonitis 5- BOOP/COP 6-RB-ILD 7-Hemorrhage 8-Pneumocystis jiroveci pneumonia 9-Cytomegalovirus pneumonia10- Alveolar proteinosis

C-Ground-Glass or Hazy Increased Density A- High attenuation (CTscan findings manifesting as increase opacity) C-Ground-Glass or Hazy Increased Density How to Recognize Ground-glass Opacity Note that in the regions of ground-glass, one can see the vessels. Ground-glass opacity (GGO) represents: Filling of the alveolar spaces with pus, edema, hemorrhage, inflammation or tumor cells. Thickening of the interstitium or alveolar walls below the spatial resolution of the HRCT as seen in fibrosis This image shows patchy ground-glass opacities throughout both lungs This patient had influenzal pneumonia

HRCT C-Ground-Glass or Hazy Increased Density The ground-glass densities are occasionally confined to the immediate centrilobular regions of the pulmonary lobules, where they appear as fuzzy nodular densities that outline the normally invisible centrilobular bronchiole (Fig. 17.7) d d The location of the abnormalities in ground glass pattern can be helpfull: Upper zonepredominance: Respiratory bronchiolitis, PCP. Lower zone predominance: UIP, NSIP, DIP. Centrilobular distribution: Hypersensitivity pneumonitis, Respiratory bronchiolitis

HRCT WHAT IS DOMINANT PATTERN ?

C-Ground-Glass or Hazy Increased Density HRCT C-Ground-Glass or Hazy Increased Density . The history was typical for hypersensitivity pneumonitis.Hypersensitivity pneumonitis usually presents with centrilobular nodules of ground glass density (acinar nodules).When they are confluent, HRCT shows diffuse ground glass. The differential diagnosis is 1- hypersensitivity pneumonitis, 2-bronchiolitis or 3- thromboembolic disease

HRCT WHAT IS DOMINANT PATTERN ?

A- High attenuation (CTscan findings manifesting as increase opacity) D-Consolidation FIGURE 17.13. Consolidation in Cryptogenic Organizing Pneumonia (COP). A. Posteroanterior radiograph in a 53-year-old patient with fever, dyspnea, and a dry cough shows patchy consolidation and diminished lung volumes. B. HRCT scan shows multifocal areas of consolidation in a peribronchial distribution. Note air bronchograms with mild bronchial dilatation within the consolidated areas. An open lung biopsy showed COP Consolidation refers to increased lung density that obscures underlying blood vessels; air bronchograms are commonly present Consolidation refers to increased lung density that obscures underlying blood vessels; air bronchograms are commonly present Consolidation: 1-BOOP/COP 2-Sarcoidosis 3- AIP  4-UIP

HRCT WHAT IS DOMINANT PATTERN ?

HRCT D-Consolidation How to Recognize Consolidation This image shows complete opacification of most of the left upper lobe. Vessels are not visible in this area. When the bronchi remain aerated, they are seen as branching lucencies called air-bronchograms, which are present in this image. "Soft Tissue Windows" Defined The same computer information from the image above can be displayed, as shown here, using "soft tissue windows," in which bone appears white; muscle, lymph nodes, and consolidated lung appear grey; and air and aerated lung appear black.   This image represents infectious pneumonia, which is limited by the major fissure, resulting in a sharp border. The advancing anteromedial margin shows ground-glass opacity (see later).

Irregularity of Lung Interfaces 1 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 irregularity of the normally smooth interface between the bronchovascular bundles and the surrounding lung reflects edema or fibrosis of the axial interstitium or infiltration by granulomas (Fig. 17.6) or tumor Irregular lung interfaces:1-Pulmonary edema 2-IPF (UIP)3-Sarcoidosis

Irregularity of Lung Interfaces High-resolution CT scan shows diffuse, patchy, subpleural, reticular opacities with irregularly thickened interlobular septa and intralobular lines and subpleural honeycombing. 2 irregularity of the interface between fissures or pleural surfaces and adjacent lung indicates peripheral interstitial disease

HRCT 2-Where is distribution within lung? 1-what is the dominant HR pattern? A- High attenuation CTscan findings manifesting as increase opacity B- low attenuation CTscan findings manifesting as decreased opacity 2-Where is distribution within lung? (is there an upper versus lower zone or a central versus pripheral prodominance) 3-Are there additional findings? (plura fluid,lymphadenopathy)

HRCT what is the dominant HR pattern? A- High attenuation CTscan findings manifesting as increase opacity 1- LINEAR ABNORMALITIES 2-NODULES 3 - GROUND GLASS OPACITY 4 - CONSOLIDATIN B- LOW attenuation CTscan findings manifesting as decreased opacity 1-AREAS OF DECREASED ATTENUATION WITH WALLS ( CYSTS ; HONEYCOMB ; BRONSHECTASIA ) 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION )

HRCT B- LOW attenuation CTscan findings manifesting as decreased opacity

B- LOW attenuation CTscan findings manifesting as decreased opacity The wall of a cavity is usually irregular or lobulated and, by definition, is greater than 1 mm thick. Lung abscess and necrotic neoplasm are the most common cavitary pulmonary lesions. An air cyst is any well-circumscribed intrapulmonary gas collection with a smooth thin wall >1 mm thick A bleb is a collection of gas <1 cm in size within the layers of the visceral pleura. It is usually found in the apical portion of the lung. These small gas collections are not seen on plain radiographs but may be visualized on chest CT, where they are indistinguishable from paraseptal emphysema A bulla is a gas collection within the pulmonary parenchyma that is >1 cm in diameter and has a thin wall <1 mm thick Pneumatoceles are thin-walled, gas-containing structures that represent distended airspaces distal to a check-valve obstruction of a bronchus or bronchiole, most commonly secondary to staphylococcal pneumonia.

HRCT WHAT IS DOMINANT PATTERN ?

B- LOW attenuation CTscan findings manifesting as decreased opacity 1-AREAS OF DECREASED ATTENUATION WITH WALLS (HONEYCOMB ; CYSTS ; BRONSHECTASIA ) 1-Honeycombing FIGURE 17.8. Honeycomb Lung in Idiopathic Pulmonary Fibrosis. HRCT in a patient with IPF shows peripheral honeycombing (arrows) indicative of end-stage pulmonary fibrosis. Honeycombing, seen as small (6 to 10 mm) cystic spaces with thick (1 to 3 mm) walls, most often in the posterior subpleural regions of the lower lobes, represents end-stage pulmonary fibrosis of various etiologies. Honeycombing : 1-IPF (UIP) 2-Asbestosis 3-Hypersensitivity pneumonitis(chronic) 4-Sarcoidosis

HRCT WHAT IS DOMINANT PATTERN ?

B- LOW attenuation CTscan findings manifesting as decreased opacity 2-Thin-walled cysts FIGURE 17.9. Thin-Walled Cysts in Lymphangioleiomyomatosis (LAM). An HRCT of a patient with LAM shows multiple, variably sized, round, thin-walled cysts Thin-walled cysts are a common manifestation of late stages of Langerhans cell histiocytosis of lung (LCH) and lymphangioleiomyomatosis (LAM). An air cyst is any well-circumscribed intrapulmonary gas collection with a smooth thin wall >1 mm thick Thin-walled cysts :1-Eosinophilicgranuloma 2-Lymphangioleiomyomatosis 3-Tuberous sclerosis 4-Neurofibromatosis (pneumatocele)

HRCT WHAT IS DOMINANT PATTERN ?

3-Architectural Distortion and Traction Bronchiectasis B- LOW attenuation CTscan findings manifesting as decreased opacity 3-Architectural Distortion and Traction Bronchiectasis FIGURE 17.12. Architectural Distortion and Traction Bronchiectasis in Idiopathic Pulmonary Fibrosis. HRCT through the lower lobes shows peripheral honeycombing, traction bronchiectasis (arrow), and resultant architectural distortion A finding commonly associated with architectural distortion is traction bronchiectasis Sarcoidosis and UIP (Fig. 17.12) are the diseases most commonly associated with architectural distortion. Architectural distortion: 1- IPF/UIP 2-Sarcoidosis

HRCT WHAT IS DOMINANT PATTERN ?

B- LOW attenuation CTscan findings manifesting as decreased opacity 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION ) 1-Emphysema Emphysema typically presents as areas of low attenuation without visible walls as a result of parenchymal destruction. A-Centrilobular emphysema due to smoking. The periphery of the lung is spared (blue arrows). Centrilobular artery (yellow arrows) is seen in the center of the hypodense area Fig. 5.16a,b. Confl uent centrilobular emphysema. Multiple,confl uent lucencies,

HRCT WHAT IS DOMINANT PATTERN ?

B- LOW attenuation CTscan findings manifesting as decreased opacity 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION ) 1-Emphysema B-Paraseptal emphysema Paraseptal emphysema is localized near fissures and pleura and is frequently associated with bullae formation (area of emphysema larger than 1 cm in diameter).Apical bullae may lead to spontaneous pneumothorax. Giant bullae occasionally cause severe compression of adjacent lung tissue. Paraseptal emphysema with small bullae

HRCT WHAT IS DOMINANT PATTERN ?

B- LOW attenuation CTscan findings manifesting as decreased opacity 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION ) C-Panlobularl emphysema There is uniform destruction of the underlying architecture of the secondary pulmonary lobules, leading to widespread areas of abnormally low attenuation. Pulmonary vessels in the affected lung appear fewer and smaller than normal. Panlobular emphysema is diffuse and is most severe in the lower lobes. In severe panlobular emphysema, the characteristic appearance of extensive lung destruction and the associated paucity of vascular markings are easily distinguishable from normal lung parenchyma.On the other hand, mild and even moderately severe panlobular emphysema can be very subtle and difficult to detect on HRCT(1). Panlobular emphysema

B- LOW attenuation CTscan findings manifesting as decreased opacity Emphysema

HRCT WHAT IS DOMINANT PATTERN ?

HRCT 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION ) another patient with ground glass pattern in a mosaic distribution.Again the ground glass appearance is the result of hyperperfused lung with large vessels adjacent to oligemic lung with small vessels due to chronic thromboembolic disease.Emboli adherent to the wall and intravascular septa are typical for chronic thromboemboli in which partial recanalization place.

HRCT 2-AREAS OF DECREASED ATTENUATION WITHOUT WALLS (EMPHYSEMA ,MOSAIC PERFUSION ) 2-MOSAIC PERFUSION If the vessels are difficult to see in the 'black' lung as compared to the 'white' lung, than it is likely that the 'black' lung is abnormal chronic pulmonary embolism. 1-obstructive bronchiolitis If the vessels are the same in the 'black' lung and 'white' lung, then you are looking at a patient with infiltrative lung disease, like the one on the right with the pulmonary hemmorrhage

Normal lung appearing relatively dense adjacent to lung with air-trapping (respiratory bronchiolitis, bronchiolitis obliterans). Bronchiolitis obliterans is seen in: Infectious (viral, mycoplasma) Chronic bronchitis Inhalation of toxin, fume (cigarette smoke) RA, Sjögren Post transplant Drug reaction (penicillamine)

What is the major abnormality in this case? a) Linear opacities b) Nodules c) Consolidation d) Ground-glass opacity F = mediastinal end of the right major interlobar fissure

Answer . The major abnormality is the presence of nodules. Also present are linear abnormalities (answer a): thickened fissures, bronchovascular interstitium, and interlobular septa.

1-Find 3 pleural nodules in the right lung. 2-Find an example of thickened bronchovascular interstitium in the right lung. 3-Find thickened fissural pleura with nodules along the outer portion in the left lung. 4-Find interlobular septal nodules. F = mediastinal end of the right major interlobar fissure

1-Find 3 pleural nodules in the right lung. 2-Find an example of thickened bronchovascular interstitium in the right lung. 3-Find thickened fissural pleura with nodules along the outer portion in the left lung. 4-Find interlobular septal nodules. F = mediastinal end of the right major interlobar fissure

What is the distribution of the major abnormality? a) Bronchovascular interstitium b) Interlobular septa c) Centrilobular region d) Pleura

HRCT Answer The distribution of the nodules includes all of the regions listed although the centrilobular nodules are subtle

1-Find nodules along 2 interlobular septa originating from the right fissure. 2-Find a group of centrilobular nodules in the right lung. Outline this group of centrilobular nodules. 3-Find a nodule at the proximal end of thickened bronchovascular interstitium in the right lung.

1-Find nodules along 2 interlobular septa originating from the right fissure. 2-Find a group of centrilobular nodules in the right lung. Outline this group of centrilobular nodules. 3-Find a nodule at the proximal end of thickened bronchovascular interstitium in the right lung. Note the unmarked nodules along the fissural pleura bilaterally. Architectural distortion is seen here as angulation along the major fissure on the right.

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases Linear pattern

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases Nodular pattern

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases Nodular pattern

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases High Attenuation pattern

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases High Attenuation pattern (2)

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases Low Attenuation pattern

Differential diagnosis of interstitial lung diseases

Differential diagnosis of interstitial lung diseases Low Attenuation pattern (2)

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