Anatomi Pleura

Pleura merupakan lapisan pembungkus paru (pulmo). Dimana antara pleura yg membungkus pulmo dextra et sinistra dipisahkan oleh adanya mediastinum. Pleura dr interna ke eksterna terbagi atas 2 bagian :

• Pleura Visceralis/ Pulmonis

Pleura yg langsung melekat pd permukaan pulmo.

• Pleura Parietalis

Bagian pleura yg berbatasan dg dinding thorax.

Kedua lapisan pleura ini slg berhubungan pd hilus pulmonis sbg lig. Pulmonale (Pleura penghubung) . Diantara kedua lapisan pleura ini terdapat sebuah rongga yg disebut dg cavum pleura. Dimana di dalam cavum pleura ini terdapat sedikit cairan pleura yg berfungsi agar tdk terjadi gesekan antar pleura ketika proses pernapasan.

Pleura parietal berdasarkan letaknya terbagi atas :

• Cupula Pleura (Pleura Cervicalis)

Merupakan pleura parietalis yg terletak di atas costa I namun tdk melebihi dr collum costae nya. Cupula pleura terletak setinggi 1-1,5 inchi di atas 1/3 medial os. clavicula

• Pleura Parietalis pars Costalis

Pleura yg menghadap ke permukaan dalam costae, cartilage costae, SIC/ ICS, pinggir corpus vertebrae, dan permukaan belakang os. sternum

• Pleura Parietalis pars Diaphragmatica

Pleura yg menghadap ke diaphragm permukaan thoracal yg dipisakan oleh fascia endothoracica.

• Pleura Parietalis pars Mediastinalis (Medialis)

Pleura yg menghadap ke mediastinum / terletak di bagian medial dan membentuk bagian lateral dr mediastinum.

Refleksi Pleura

• Refleksi vertebrae

Pleura costalis melanjut sbg pleura mediastinalis di depan columna vertebralis membentuk refleksi vertebrae yg membentang dr SIC I – XII.

• Refleksi costae

Pleura costalis melanjut sbg pleura diaphragmatica membentukk refleksi costae.

• Refleksi sternal

Pleura costalis melanjut sbg pleura mediastinalis di belakang dr os. Sternum membentuk refleksi sterna

• Pleura mediastinalis melanjut sbg pleura diaphragm

Garis Refleksi Pleura

Garis refleksi pleura antara pleura dextra dan sinistra terdapat perbedaan, yakni :

• Garis Refleksi Pleura Dextra

Garis refleksi dimulai pd articulation sternoclavicularis dextra lalu bertemu kontralateral nya di planum medianum pd angulus ludovichi/ angulus Louis setinggi cartilage costae II. Lalu berjalan ke caudal sampai di posterior dr proc. Xiphoideus pd linea mediana anterior/ linea midsternalis menyilang sudut xiphocostalis menuju cartilage costae VIII pd linea midclavicularis, menyilang costae X pd linea axillaris media dan menyilang cartilage costa XII pd collum costaenya.

• Garis Refleksi Pleura Sinistra

Garis refleksi dimulai pd articulation sternoclavicularis sinistra lalu bertemu kontralateral nya di planum medianum pd angulus ludovichi/ angulus Louis setinggi cartilage costae II. Lalu berjalan turun sampai cartilage costa IV dan membelok di tepi sternum lalu mengikuti cartilage costa VIII pd linea midclavicularis dan menyilang costae X pd linea axillaris anterior dan menyilang costa XII pd collum costaenya.

Vaskularisasi Pleura

Pleura parietal divaskularisasi oleh Aa. Intercostalis, a. mammaria interna, a. musculophrenica. Dan vena2 nya bermuara pd system vena dinding thorax.

Sedangkan pleura visceralis nya mendapatkan vaskularisasi dr Aa. Bronchiales.

Innervasi Pleura

• Pleura parietalis pars costalis diinnervasi oleh Nn. Intercostales.

• Pleura parietalis pars mediastinalis diinnervasi oleh n. phrenicus

• Pleura parietalis pars diaphragmatica bagian perifer diinnervasi oleh Nn. intercostales. Sedangkan bagian central oleh n. phrenicus

• Pleura visceralis diinnervasi oleh serabut afferent otonom dr plexus pulmonalis.

Recessus Pleura

Recessus merupakan sebuah ruangan kosong yg akan terisi oleh paru saat inspirasi dalam dan akan mjd tempat yg berisi cairan pd pasien dg kasus efusi pleura. terdapat 3 ps recessus, yaitu :

- recessus costodiaphragmatica dextra et sinistra

recesssus yg terletak diantara pleura parietalis pars costalis dan pleura parietalis pars diaphragmatica

- recessus costomediastinalis anterior dextra et sinistra

recessus yg terletak di antara pleura parietalis pars costalis dan pleura parietalis pars mediastinalis di bagian ventral

- recessus costomediastinalis posterior dextra et sinistra

recessus yg terletak di antara pleura parietalis pars costalis dan pleura parietalis pars mediastinalis di bagian dorsal.

Fisiologi pleura

Fungsi mekanis pleura adalah meneruskan tekanan negatif thoraks kedalam paru-paru, sehingga paru-paru yang elastis dapat mengembang. Tekanan pleura pada waktu istirahat (resting pressure) dalam posisi tiduran pada adalah -2 sampai -5 cm H2O; sedikit bertambah negatif di apex sewaktu posisi berdiri. Sewaktu inspirasi tekanan negatif meningkat menjadi -25 sampai -35 cm H2O.

Selain fungsi mekanis, seperti telah disinggung diatas, rongga pleura steril karena mesothelial bekerja melakukan fagositosis benda asing; dan cairan yang diproduksinya bertindak sebagai lubrikans.

Cairan rongga pleura sangat sedikit, sekitar 0.3 ml/kg, bersifat hipoonkotik dengan konsentrasi protein 1 g/dl. Gerakan pernapasan dan gravitasi kemungkinan besar ikut mengatur jumlah produksi dan resorbsi cairan rongga pleura. Resorbsi terjadi terutama pada pembuluh limfe pleura parietalis, dengan kecepatan 0.1 sampai 0.15 ml/kg/jam. Bila terjadi gangguan produksi dan reabsorbsi akan mengakibatkan terjadinya pleural effusion.

Fungsi pleura yang lain mungkin masih ada karena belum sepenuhnya dimengerti.

Jumlah cairan

• 250 -300ml - foto torak tegak

• 100 – 200 ml - foto lateral tegak

• < 100 ml - posisi dekubitus dan arah sinar horisontal

• Kadang cairan terkumpul setempat di pleura atau fissura interlobar ( loculated / encapsulated ) o/k perlekatan pleura.

USG Pleura Normal

Gambaran dinding dada normal terdiri

dari lapisan jaringan lunak, otot dan fascia adalah

echogenic. Tulang rusuk digambarkan seperti garis

echogenic diatas lapisan jaringan lunak, otot dan

fascia. Gambaran ini dapat dilihat pada gambar

9. Pleura parietal digambarkan seperti dua garis

echogenic dibawah tulang rusuk. Transducer yang

digunakan sebaiknya berbentuk linier array dengan

panjang gelombang 7,5-10 MHz. Bentuk transducer

lain dapat digunakan untuk pemeriksaan ini tapi

hasil yang didapat tidak sebaik jika menggunakan

transducer linier array. Gambaran normal toraks

dapat berbeda tergantung dari posisi pemeriksa dan

letak transducer.

2

Chest Ultrasound

Sonography is complementary to chest radiography and CT in the evaluation of

processes in the thorax. US commonly reveals abnormalities not shown by other imaging methods (Fig. 12.1) [1,2 and 3]. Although limited by air and bone, US visualization is made possible by the pathologic processes creating a sonographic window. Pleural effusion, pulmonary consolidation, atelectasis, and mediastinal tumors are sonographic portals to the thorax. US can be performed at the bedside of critically ill patients, avoiding the necessity of moving them and all their life support equipment to the radiology department [4]. US is excellent for guidance of diagnostic and therapeutic invasive procedures in the chest [5].Imaging TechniqueThe first step in US examination of the thorax is to review the chest radiograph. The chest radiograph or chest CT provides a guide for sonography. The examination is then directed to answer the specific questions raised. Two basic approaches are used to examine the chest with US. The direct approach utilizes the intercostal spaces. Linear or curved array transducers with frequencies of 5.0-7.5 MHz are used to examine the pleura and structures in the near field-of-view. For large pleural effusions and for structures deeper in the chest a 3.5-MHz sector transducer may be used. However, the near field is obscured by reverberation artifact with sector transducers, and important findings related to the pleura and chest wall may be missed if only sector transducers are used (Fig. 12.2). The second approach to examination of the thorax is the transabdominal technique. A 3.5-MHz sector transducer is angled superiorly through the liver or spleen to examine the diaphragm and lower thorax (Figs. 12.3, 12.4)The sector transducer can also be used to examine the mediastinum by angling downward from the sternal notch or by angling centrally from parasternal

positions. Placing the patient in right or left lateral decubitus positions helps to enlarge the parasternal window [6]. Doppler is essential when examining the mediastinum to evaluate major vessels and to diagnose vascular lesions [7].AnatomyThe pleural space is bounded by a continuous serosal membrane that forms the visceral pleuraP.434

covering the lungs and forming the interlobar fissures, and the parietal pleura that covers the mediastinum, diaphragm, and inner surface of the chest wall. The total thickness of both pleural membranes is only 0.2-0.4 mm. US does not directly demonstrate the normal pleura but rather shows the interface of the pleura with pleural fluid and the interface of the surface of the air-filled lung (Fig. 12.5). These interfaces serve as the sonographicP.435

landmarks for evaluation of the pleura. The chest wall is identified by the characteristic appearance of the ribs. Ribs cause a bright surface echo and a dense acoustic shadow. Intercostal muscles extend between the ribs, providing an effective intercostal window. Subcutaneous fat is of variable thickness, so the ribs provide the best landmark for identification of the parietal pleura, which is approximately 1 cm deep to the surface echo of the rib. Between the parietal pleura and the chest wall is fatty connective tissue of variable thickness but rarely exceeding a few millimeters. The normal pleural space contains 1-5 mL of pleural fluid seen as a thin echolucent line between the two pleural interfaces (Fig. 12.6) [8]. Normal pleural fluid lubricates the pleural space easing motion of the lung with breathing. It also aids in providing an adhesive force that holds the lung open and against the chest wall. Pleural fluid, mass, or air breaks this adhesive seal and allows the lung to retract, resulting in atelectasis. The pleural space is easy to identify by observing the respiratory motion of the visceral pleura/lung interface, the “gliding sign” [9]. The bright, linear surface echo slides back and forth with inspiration and expiration. With breathing, streaks of bright reverberation artifacts emanate from the boundary of the visceral pleura and air-filled lung [10].

Figure 12.1 Utility of Chest US. A. Chest radiograph shows opacification of most of the right hemithorax but yields little information as to its nature. B. Transverse US image of the lower right thorax shows a large cystic mass (C) that displaces and compresses the heart (h). The cystic mass is thick-walled and contains layering echogenic debris (arrow). This proved to be a large pulmonary hydatid cyst. The layering echogenic debris is hydatid sand.

Figure 12.2 Limitation of Sector Transducers in the Thorax. A. 3.5-MHz sector transducer. Near-field artifact characteristic of sector transducers obscures the pleural space. B. 5.0-MHz linear array transducer. Use of a linear array transducer in the same intercostal space clearly reveals a pleural effusion (F). The interface of the parietal pleura (black arrow) and the visceral pleura/lung interface (white arrow) are well demonstrated.

Figure 12.3 Normal Mirror Image Artifact. Longitudinal image obtained through the liver (L) shows the bright interface of the diaphragm (arrows) with air-filled lung above it. The soft tissue-air interface at the level of the diaphragm causes near-complete sound reflection back into the liver. Further reflection of the sound beam within the liver delays the return of the echoes to the transducer. As a result, an artifactual mirror image (MI) of the liver is displayed further from the transducer and above the diaphragm. The mirror image of the liver above the diaphragm should be recognized as an artifact, but also provides evidence that normal air-filled lung is present at the lung base. Compare to Figure 12.412.4.

Figure 12.4 Pleural Effusion Seen from the Abdomen. Longitudinal image through the liver and right kidney shows a wedge of anechoic pleural fluid (black arrow) above the diaphragm. The sound wave penetrates the fluid and reveals the chest wall, recognized by rib shadows (white arrow). These findings are pathognomonic of pleural effusion.

Figure 12.5 Normal Pleural Space. A. Longitudinal image obtained with a linear array transducer applied directly to the thorax demonstrates the bright surface echo produced by the

ribs (R) and the dense acoustic shadow (AS) resulting from marked sound absorption by bone. The bright linear echo (arrow) produced by the interface of visceral pleura and air-filled lung indicates the location of the pleural space in this normal patient. This interface is observed on real-time scanning to move with respiration, the “gliding sign.” Note that the pleural space is within 1 cm of the rib surface echo. Intercostal muscles (m) are seen between the ribs. B. Turning the transducer to align with the intercostal space produces this transverse image. The gliding sign identifies the location of the parietal pleura (black arrow) and the visceral pleura (white arrow). Air-filled lung is obscured by reverberation artifact (RA).P.436

The normal lung is air-filled and is seen only as the bright linear surface echo and an intense reverberation artifact (Fig. 12.5, Fig. 12.6). Disease in the lung replaces air with fluid, inflammatory cells, or tumor, or collapses the air spaces of the lung to produce a solid structure that can be penetrated with US. Disease that is completely surrounded by air-filled lung will not be visible to US.When scanning the thorax from an abdominal approach, the air-filled lung causes complete sound reflection and the curving surface of the diaphragm causes multipath reflectionP.437

of the US beam. This results in the striking mirror-image artifact described in Chapter 1. The image of the liver or spleen is duplicated above the diaphragm (Fig. 12.3). The presence of a mirror image artifact indicates that normal air-filled lung is above the diaphragm. Absence of the mirror image artifact is evidence of pathology in the lung base or pleural space.

Figure 12.6 Normal Pleural Fluid. Intercostal image shows a sliver of normal pleural fluid (arrow) separating the parietal and visceral pleural surfaces. A tiny volume of pleural fluid is normally present.Pleural SpaceThe pleura is involved by pathologic processes that occur as isolated disease or as a complication of diseases of the lung, chest wall, or abdomen. Chest radiographs accurately detect pleural disease but are limited in providing characterization of the disease. Disease in the pleura provides an excellent window for US evaluation [10]. US is exceptionally valuable in guiding aspiration, biopsy, and catheter drainage procedures in the pleural space [11].Pleural EffusionPleural effusion is an abnormal increase in the volume of pleural fluid. Fluid escapes from the blood vessels and lymphatics of the pleural surface as a result of a pathologic process. US is excellent in diagnosing the presence and volume of pleural fluid, and in assessing whether the fluid is amenable to aspiration [12]. Pleural effusions may be characterized as to whether they are transudates or exudates [13].

A layer of anechoic or hypoechoic pleural fluid separates the visceral and parietal pleura (Fig. 12.7).

On transabdominal scanning the mirror image artifact is absent. Fluid is seen above the diaphragm and the inside of the chest wall is visualized

through the fluid layer. The chest wall is recognized by the acoustic shadows that emanate from ribs (Figs. (Fig. 12.4, Fig. 12.8).

Atelectasis is always present with pleural effusion (Fig. 12.8). An abnormal volume of pleural fluid releases the adhesive tension that holds the surface of the lung against the chest wall and the lung reflexly collapses. The atelectatic lung is seen as a wedge-shaped echogenic mass moving with respiration within the pleural fluid.

P.438

Signs that indicate that a pleural lesion is fluid that can be aspirated are: (a) change in shape of the lesion with respiration, (b) floating echodensities, and (c) moving fibrous strands [12].

The volume of pleural fluid can be estimated by US measurement of the distance between parietal and visceral pleura. The measurement is made with the patient supine and holding breath in maximal inspiration. Transverse scans are obtained in the intercostal space at the posterior axillary line just above the diaphragm. The maximum width of the fluid space is measured and related to the data shown in Table 12.1 [14].

P.439

Anechoic fluid may be either transudate or exudate. Aspiration and chemical analysis of the fluid is needed to differentiate the type of effusion [13].

Fluid that contains floating debris or has septations or fibrous strands is always an exudate [13].

US is exceptionally valuable in localizing pleural fluid and in guiding diagnostic or therapeutic thoracentesis.

Figure 12.7 Pleural Effusions. Intercostal images with a linear array transducer from two patients (A, B) show small pleural effusions (e). Cursor (+) measures the distance to the lung surface.

Figure 12.8 Pleural Effusions. A. Transabdominal image in transverse plane shows a large pleural effusion (e) with a wedge of echogenic collapsed lung (l). Atelectasis always accompanies pleural effusion. A small volume of ascites (a) is also evident. Note the bare area of the liver (arrow). B. Transabdominal image in longitudinal plane in a different patient shows a large pleural effusion (e) and right lower lobe atelectasis (l).

Table 12.1: Quantification of Pleural Effusion VolumeThickness of EffusionMeasured by US (mm) Mean Effusion Volume

0 55 80

10 17015 26020 38030 55040 100050 1420

Adapted from Eibenberger KL, Dock WI, Amman ME, et al. Quantification of pleural effusions: sonography versus radiography. Radiology 1994;191:681-684.

Reprinted from Brant WE. Chest. In McGahan JP, Goldberg BB. Diagnostic Ultrasound–A Logical Approach. Lippincott-Raven. Philadelphia, 1998.Transudative Pleural EffusionA transudative pleural effusion is a simple serous pleural effusion. Transudates are ultrafiltrates of plasma from normal pleural membranes [13]. Transudates result from an underlying disease, such as congestive heart failure, that increases capillary hydrostatic pressure or causes a decrease in colloid osmotic pressure [8, 15]. Additional causes of transudative pleural effusion include cirrhosis, nephrotic syndrome, hypoalbuminemia, constrictive pericarditis, and superior vena cava obstruction.

Transudative pleural effusions are anechoic without floating debris (Figs. 12.4), (Fig. 12.7B) [13].

The fluid changes shape with respiration and positioning.

Exudative Pleural EffusionExudative pleural effusions are complicated effusions with high protein content (>3.0 gm/100 mL) and may contain blood, pus, chyle, or malignant cells. The pleura is abnormal and is directly involved with an inflammatory or neoplastic process. Causes include empyema and parapneumonic effusion, neoplasms involving the pleura, hemothorax, tuberculous pleurisy, and intraabdominal inflammatory processes such as abscess or pancreatitis.

Floating echogenic debris is seen within the pleural fluid (Fig. 12.9). Homogeneous floating echodensities are indicative of hemorrhagic effusion

parapneumonic effusion, or empyema [13]. Moving debris within the fluid scatters the US beam and produces color

signals within the fluid—the fluid color sign [16]. This finding aids in the differentiation of echogenic pleural fluid from pleural thickening.

P.440

Linear fibrous bands form with organization of the exudative fluid (Fig. 12.10). These thin echogenic septa move to-and-fro with respiration and may cause loculation of the fluid. A honeycomb appearance is indicative of high likelihood of inability to drain the effusion with a small-bore catheter. These septa, seen easily with US, are not seen on chest radiographs and are often not apparent on CT.

The presence of thickened pleura or associated lung consolidation or masses are associated with exudative effusion (Fig. 12.11) [13].

Figure 12.9 Exudative Parapneumonic Pleural Effusion. Transverse image shows a large echogenic pleural effusion (e). Real-time imaging revealed swirling motion of the particulate matter within the effusion. Echogenic particulate matter in a pleural effusion is indicative of an exudative effusion. This patient’s chest radiograph revealed a right lower lobe pneumonia in association with the large effusion. Thoracentesis confirmed the absence of bacteria within the exudative effusion. l, partially collapsed right lower lobe; rt, right; s, coarse septation within the effusion.

Figure 12.10 Complex Exudative Pleural Effusions. Images of pleural effusions in three different patients (A, B, C) show the complex network of fibrinous strands and loculations that may develop in chronic exudative pleural effusions.Empyema and Parapneumonic EffusionEmpyema is the presence of pus in the pleural cavity. Parapneumonic effusions are exudative effusions that complicate pneumonia and lung abscess. No US findings are specific for these conditions. Diagnosis is based upon analysis of the pleural fluid aspirated. Empyema is diagnosed when (a) the fluid is grossly purulent, (b) bacteria are identified on Gram’s stain or culture, or (c) the white blood cell count in the fluid exceeds 15,000/mL [17].

Figure 12.11 Chronic Empyema. Intercostal image shows a loculated, echogenic pleural fluid bounded by thickened pleura (arrow). US-guided aspiration confirmed chronic empyema.P.441

PneumothoraxContrary to popular belief, pneumothorax can be reliably detected by US.

Absence of visualization of the gliding visceral pleura (Fig. 12.12) and absence of the streak-like reverberation artifacts that emanate from the lung surface during breathing are evidence of pneumothorax [18].

During US-guided invasive procedures sudden loss of visualization of the target lesion is evidence of pneumothorax [19].

Because air in the pleural space will move to the non-dependent thorax, US is not reliable in excluding pneumothorax [20].

Hydropneumothorax may be recognized by the presence of an air-fluid level with air shadow above a layer of fluid (Fig. 12.13). Microbubbles may be seen within the pleural fluid [21].

Pleural PlaquesPleural plaques are localized thickenings of the pleura caused by inflammation or infarction. Asbestos exposure is a common cause of pleural plaques that frequently calcify.

Figure 12.12 Pneumothorax. Intercostal image shows the bright reflection (large arrow) and the reverberation artifact caused by air in the pleural space. Real-time US is required to see the absence of the “gliding pleura sign” that confirms pneumothorax. On static images, pneumothorax cannot be differentiated from normal lung reflection (compare to Figure (Fig. 12.4). Repeated sound reflection between the air interface and the surface of the transducer reproduces the image of the air interface deeper in the image (small arrow).

Figure 12.13 Hydropneumothorax. Compare the CT image (A) of a loculated hydropneumothorax to the US image (B) oriented to match the CT scan. With the patient supine, fluid (smaller arrow) gravitates to the dependent portion of the cavity while air (larger arrow) occupies the non-dependent portion of the cavity. Air in the pleural space produces a brightly reflective echo, while sound penetrates and shows the detail within the dependent fluid. The air-fluid level (curved arrow) is seen on US as the sharp area of transition between the bright air echo and the fluid echo.P.442

Plaques appear as focal hypoechoic thickening of the pleura. Thickness is usually in the 5-12-mm range [22].

Calcified plaques are highly echogenic and cause acoustic shadowing [22].

FibrothoraxFibrothorax is a rind of thickened pleura that restricts lung motion.

Fibrothorax appears as echogenic solid pleural thickening (Fig. 12.14). The surface of the pleura may undulate because of variation in the amount of thickening.

No fluid color sign is present in the thickened pleura. Loculation of pleural fluid is commonly also present.

Localized Fibrous Tumor of the PleuraBenign mesothelioma is now called localized fibrous tumor of the pleura. The tumors are fibrous and of mesenchymal origin with areas of dense collagen tissue [23].

US shows a well-defined hyperechoic mass with lobulated contours (Fig. 12.15) [10, 23]. The mass forms obtuse angles where it meets the chest wall. Most are found in the lower thorax.

Malignant Pleural MesotheliomaMalignant pleural mesothelioma is a rare tumor related to occupational asbestos exposure. The tumor has a dismal prognosis [24].

Figure 12.14 Fibrothorax–Thickened Pleura. A. Intercostal image shows marked thickening of the parietal pleura (P) and a small echogenic pleural effusion (e). Reverberation artifact obscures the lung (l). The visceral pleura-lung interface is duplicated as a reverberation artifact (arrow). The cursor (+) marks the interface between parietal pleura and pleural effusion. B.Intercostal image through a pleural effusion in another patient shows thickening of the visceral pleura (arrow) overlying air-filled lung.P.443

Multiple tumor masses on the visceral and parietal pleura are the most common pattern [24].

The masses may grow to become confluent, encasing the lung with lobulated thickened pleura.

Large pleural effusions are present in 60% of patients.

P.444

Calcified pleural plaques are found in 20% of patients. US-guided core biopsy is a highly effective method of confirming the

diagnosis (Fig. 12.15) [25].

Figure 12.15 Localized Fibrous Tumor of the Pleura. A. A large solid tumor of the pleural space is evident. B. US was used to guide core needle (arrow) biopsy of the lesion to confirm a benign localized fibrous tumor of the pleura.

Figure 12.16 Metastases to the Pleura. A. This patient with advanced metastatic colon carcinoma was referred for therapeutic thoracentesis because of severe dyspnea. US examination reveals diffuse thickening of the visceral (vp) and parietal pleura (pp) with a complex loculated pleural effusion (e). A solid nodule (arrow) on the parietal pleural surface represents a metastatic deposit. A metastasis (m) in the lung is seen as a solid intraparenchymal mass. Thoracentesis was deferred because of lack of fluid amenable to aspiration. B. Metastases to the pleural space from lung carcinoma produce echogenic nodules (arrows) that project into pleural fluid. C. In another patient with lung carcinoma, pleural metastases (arrows) have implanted on the pleural surface covering the heart (h).Metastases to the PleuraMetastatic disease to the pleura arises most commonly from lung carcinoma (40%), breast carcinoma (20%), and lymphoma (10%) [26].

Diffuse pleural thickening >1 cm is highly indicative of pleural metastases (Fig. 12.16).

Multiple hypoechoic tumor nodules typically involve the parietal pleura (Fig. 12.16). Appearance is indistinguishable from malignant mesothelioma.

P.445

Exudative pleural effusion is commonly present and provides a sonographic window for visualization of the tumor nodules and diffuse nodular pleural thickening [27]. Malignant pleural effusion is second only to congestive heart failure as the most common cause of pleural effusion in patients older than age 50 [28].

US is commonly used to guide diagnostic and therapeutic thoracentesis. Cytology of pleural fluid obtained by thoracentesis yields a specific diagnosis in approximately two-thirds of cases [28].

Asbestos