Pleura and Mediastinum

Radiology (Dra. Bandong)

Pleura, mediastinum…

05 July 2008

Anatomyo a space within the thoracic cavityo bounded by:

- anterior sternum- posterior vertebral bodies- superior thoracic inlet- inferior diaphragm- lateral parietal pleura

o divided into compartments by drawing a line from the sternal angle to the 4th thoracic intervertebral disk space

- area above superior compartment- area below inferior compartment

o anterioro middleo posterior

CT SCANo is the imaging modality of choice for diagnosis, staging, and

follow up of patientso offers the advantage of better localization and

characterization of the disease processo it can demonstrate compression and involvement of the

adjacent structures in the mediastinum better than plain films.

Normal Thymuso Lies in a retrosternal location behind the manubriumo Commonly seen anterior to the proximal ascending aorta

and distal superior vena cavao Size of a normal thyroid is largets between 12-19 years

of age.

o Anteriorly by the sternumo Posteriorly by the pericardium, aorta, and brachiocephalic

vessels

Masses situated predominantly in the anterior mediastinal compartment (AMC)

A mass is considered to lie in the AMC when it is situated in the region anterior to the line drawn along the anterior border of the trachea and posterior border of the heart

Anterior Mediastinal Masso Thymus

- Thymoma – Most common- Thymic cyst- Thymolipoma- Thymic carcinoid- Thymic hyperplasia

o Lymphomao Germ cell tumor

- Teratoma- Seminoma- Shoriocarcinoma

o Thyroid- Goiter - Tumor

o Mesenchymal tumors- Leiomyoma- Liposarcoma

o Hemorrhage

NOTES:Mediastinal mass: Pulmonary mass:

o Margins are smooth o Spiculated margins o Bilateral o Unilateralo Loss of cardiac silhouette

1C ng 3B (jassie, viki, candz..ung iba support group..hehe) 1 of 14

Pleura

Anterior mediastinal compartment

o Widened mediatinum o Loss of cardiac

silhouette o Intact silhouette of

descending aorta

o Retrosternal area is filled with mass density

Anterior mediastinal mass

RADIOLOGY – Pleura and mediastinum by Dra. Bandong Page 2 of 14

ThymomaTeratomaThyroid nodule / goiterLymphoma

THYMOMAo Most common neoplasm of the anterior mediastinumo 30-35% are malignanto Commonly occur in patients >40y/oo Asymptomatico CXR:

- Found in anterior mediastinum to the ascending aorta above the right ventricular outflow tract and main pulmonary artery

- Maybe situated as low in the mediastinum as the cardiophrenic angles

o CT(Benign)- Well demarcated masses with homogenous

density- Uniform contrast enhancement- Have areas of decrease attenuation- Punctuate or ring like calcifications

o CT (Malignant)- Heterogenous attenuation- May obliterate adjacent mediastinal fat- May detect pleural spread

LYMPHOMA

2 types of lymphoma: Hodgkin’s (HL)

o Bimodal age distribution—25-30 y/o and >70 y/oo 67% intrathoracic involvement (anterior/ superior

mediastinal and hilar adenopathy) o 15-40% pulmonary involvement by:

- Direct extension form involved nodesPulmonary nodulesParenchymal consolidationPleural effusionSternal erosions

Non Hodgkin’s (NHL)o 4x more common than HLo 3rd most common childhood malignancyo More frequently fatal than HLo Middle medisatinum – most frequently involvedo Posterior mediastinum and cariophrenic angles can be

alteredo Appears as a single large conglomerateo Other common nodal signs involvement include

Lung parenchymaPleuraPericardium

o most are found in the anterior mediastinumo 20-40 yearso Divided into

seminomatous neoplasms (seminoma) non seminomas

Seminomatous neoplasm (Seminoma)o Most common germ cell tumoro most common primary malignant cell tumoro less aggressiveo secrete low levels of HCGo On CT:

large masses with sharply demarcated borderso Homogenous attenuation but may have hemorrhage and

necrosis

Germ Cell Tumors


Non Seminomatous neoplasmo More aggressiveo Secrete high levels of fetoprotein and / or HCGo Teratoma

- Most common non seminomatous tumors- Most common mediastinal germ cell tumor- Benign: mature teratoma

MATURE TERATOMACXR: large, well demarcated, rounded masses

Located anterior to the root of the aorta and main pulmonary arteryCalcification, ossification or even teeth may be visible

CT: large cystic massThick, encapsulated wallMay enhanceMay contain curvilinear calcifications

MALIGNANT TERATOMACXR: more lobulated in outline

Rarely has calcifications and never has fat densityMetastasize to the lungs, bones or pleura

CT: typical mass has irregular border with thick capsuleEnhances with IV contrastAdjacent fat planes are obliterated

Extreme local invasion is common*In CT scan, this can be distinguished from thymoma and seminoma.

Masses predominantly in the MMC and PMC

A lesion can be considered to properly lie in the MMC or PMC when it is located between a line drawn through the anterior aspect of the trachea and posterior aspect of the heart and the line drawn through the anterior margins of the vertebral bodies

Middle and Posterior Mediastinum (MMC / PMC)


NOTES:Posterior lesion – 20 to osseous; sarcoma involving

the vertebral columnMiddle lesion – esophagus, bronchogenic cyst

Middle MediastinumBoundaries by posterior margin of anterior division and

anterior margin of posterior division (malamang!)

Normal structuresHeart and pericardiumAscending and transverse aortaBrachiocephalic vesselsSVC and IVCMain pulmonary vesselsTrachea and main bronchiLymph nodes

Differential diagnosis of middle mediastinal massesLymphadenopathyBronchogenic cystVascular abnormalitiesPericardial cystTracheal tumor

Most common: aneurysm

Posterior mediastinumBoundaries bounded anteriorly by the posterior margin of

the pericardium and great vessels and posteriorly by the thoracic vertebral bodies

Normal structuresDescending thoracic aortaEsophagusThoracic dustAzygous and hemiazygousAutonomic nervesLymph nodesFat

Differential diagnosisNeurogenic tumorsParavertebral abnormalitiesVascular abnormalitiesEsophageal abnormalitiesLymphadenopathyNeurenteric cystBochdalek’s herniaExtramedullary hematopoeisis

*It is difficult to delineate middle to posterior mediastium.

CASE: An 87 year old woman presents with dysphagia

Radiographs show a homogenous mass in the middle / posterior mediastinum extending from the level of the aortic arch to the

diaphragm and displacing the esophagus to the right (residual contrast is evident in the esophagus from a barium swallow)

A CT scan just below the level of the carina reveals a hematogenous soft tissue mass with a central area of low attenuation (A). Note the markedly compressed esophagus (B). It is not possible to discern whether the mass is arising from the wall of the esophagus or the adjacent mediastinum. There is an incidental finding of calcified brachial plates (C)

Non contrasted chest CT demonstrating heterogenous appearing post. Mediastinal mass with punctuate calcifications which appears to extend into the neural foramina (see picture below)

*With contrast, there is enhancement of blood vessels and vice versa in non-contrast.


Contrasted Chest CT demonstrating heterogenous appearing post mediastinal mass with punctuate calcifications which appears to extend into the neural foramina.

o Age: occur in young patients in the first 4 decades of life (young???)

o Gender: males and females equally affectedo Round, homogenous with widening of the neural forameno MRI: slightly brighter than muscle on T1

Very bright on T2 homogenous enhancement following gadolinium demonstration

Neuroblastoma

o Tricuspid valve regulates blood flow between RA and RVo Pulmonary valve controls blood flow from right ventricle

into the pulmonary artery which carry blood to the lungs to puck up O2

o Mitral valve lets O2 rich blood from lungs to pass from LA to LV

o Aortic valve opens the way for O2 rich blood to pass from LV to the aorta, the largest artery, where it is delivered to the rest of the body

During Diastole, atria and ventricles are relaxed and the AV valves are open. DeO2ated blood from the SVC / IVC flows to the RA. The open ______ atrioventricular valves allow blood to pass through the ventricles. During systole, the ventricles contracts triggering the atria to contract. The RA empties its contents into RV. The tricuspid valve prevents blood from flowing back into the RA.

NOTES:Common Imaging modalities:

a. Ionizing radiation – Radiography, CT, Nuclear Scintigraphy

b. Non-ionizing radiation – MRI and 2D Echo

NEUROGENIC TUMORS

CARDIAC IMAGING LECTURE


This coronal MRI shows a somewhat anterior plane of the heart. The RV and proximal pulmonary artery is well defined. Portions of the SVC and RA are also visible.

This axial MRI shows the main and right pulmonary artery crossing under the aortic arch (medyo malabo, pxenxa)

This sagital MRI shows the mid-section of the LV, defining the interventricular septum of the myocardium and the lateral wall.

Cardiac Borders: (see picture above)Right side – SVC and RALeft side – aorta, aortic arch, pulmonary artery, LA, LV


The right ventricle and its outflow tract are seen as one continuous structure.

Calcium Scoreo Identifies calcification of coronary arterieso Screeningo Increased calcification = MI

The widest diameter of the heart compared to the widest internal diameter of the rib cage

Get the diameter of the heart then divide it to the diameter of the entire thoracic area within the confines of the thorax (ribs not included)

Normal Cardio-thoracic ratio:o Adults - < 0.5o Children – 0.55

o

Sometimes, CTR is more than 50% BUT heart is normalExtracardiac causes of heart enlargement

Portable AP films

ObesityPregnancyAscitesStraight back syndromePectus excavatum

CTR is less than 50% BUT heart is abnormalObstruction to outflow of the ventriclesVentricular hypertrophyMust look at cardiac contours

Here is an example of a heart which is < 50% of the CTR, in which the heart is still abnormal. This is recognized because there is an abnormal contour to the heart.

Cardiac contours: Ascending aorta

o Enlargement 20 to atherosclerosiso Enlargement is called: Double density sign

Left atrium Aortic knob

o Normal: not > 0.35 mmo If enlarged, there is atherosclerotic aortao >0.5 cm: aneurysm

Pulmonary arteryo Congenital diseaseo Dilatation of artery

CARDIO THORACIC RATIO

CARDIAC CONTOURS


DOUBLE DENSITY OF LA ENLARGEMENT

Two shadows: the yellow arrow pointing to the LA and the red arrow to the RA, overlap each other where the indentation between the ascending aorta and the right heart border meet.

Aortic knob o The first bump on the left sideo Can be measured from the lateral border of air by the

trachea to the edge of the aortic knob.o Enlarged by

Increased pressureIncreased flowChanges in the aortic wall

Main Pulmonary ArteryThe next bump down is the main pulmonary artery and is the keystone of this system


Two major classificationso Main pulmonary artery projects beyond the tangent line

Increase pressureIncrease flow

NOTES:Small pulmonary artery: TOF, Truncus arteriosusApex of ventricle goes down: Enlargement of left ventricleApex of ventricle goes up: Enlargement of right ventricle

o Main pulmonary artery more than 155mm away from the tangent line.

Because MPA is small or absentBecause tangent line is being pushed away from the

MPAExamples: small pulmonary artery

Truncus arteriosusTetralogy of fallot

Left atrial enlargement Concavity where LA will appear on the L side when enlarged

Which ventricle is enlarged?If heart is enlarged and main pulmonary artery is bigRV is enlarged

Five states of the Pulmonary Vasculature:


Normal (more vessels should be seen in inferior part of the lungs); with enlargement of upper lobe, there is cephalization.

Pulmonary venous hypertension Pulmonary arterial hypertension Increased flow Decreased flow

What we’re going to evaluateRight descending pulmonary arteryDistribution of flow in the lungs

Upper vs. lower lobesCentral vs. peripheral

Right Descending Pulmonary Arteryo Serves right, middle and lower lobes

Normally should not be more than 17mm in diameter. (Diameter is measured before the bifurcation)

1. Normal Distribution of flow (U / M/ L lobes)o In erect position, blood flow to the bases is > than flow

to the apices

o Size of vessels at the bases is normally > than the size of vessels at apex

o You cant measure the vessels at the left because the heart blocks them

*Central Vs. Peripheral distribution of flow: divide lungs vertically into 3. Outer 2/8: here, you seldom see vascular markings. If present, there is congestion.

2. Pulmonary Venous Hypertensiono Has cephalization (more vessels in upper lobes than

lower lobes)o Increased vascular markings

3. Pulmonary Arterial hypertensiono RDPA > 17 mmo More central vessels are dilatedo Dilatation of right descending pulmonary arteryo Main pulmonary artery projects beyond the tangent line


o Rapid cutoff on size of peripheral vessels relative to the size of central vessels

o Central vessels appear to large for size of peripheral vessels which come from them = Pruning

4. Increased flowo Distribution of flow is maintained as normalo Gradual tapering from central to peripheralo L lobe bigger than U lobe

5. Decreased flowo Unrecognizable most of the timeo Small hilao Fewer than normal blood vesselso No vessels in lower lobes (which is normally present)

o Causes: coronary artery diseaseHypertensionCardiomyopathyValvular lesion

AS, MSL to R shunts

o Clinical: left sided heart failure:Shortness of breathParoxysmal nocturnal dyspneaOrthopneaCough

right sided heat failure:Edema

Left Atrial PressureCorrelated with pathologic Findings

Normal 5-10 mm HgCephalization 10-15 mm HgKerley B lines 15-20 mm HgPulmonary Interstitial edema 20-25

Pulmonary Alveolar edema >25

*Normal pulmonary capillary hydrostatic pressure: about 7 mmHg Normal colloid oncotic pressure: 11 mmHg

CONGESTIVE HEART FAILURE


Kerley A lines – near hilum, longer B linesKerley B lines – sign of interstitial edema, located in the basesKerley C lines – does not exist

Keeping lungs dry

Pulmonary Interstitial Edema Fluid present in minor fissure Linear opacities in bases: Kerley B lines X-ray Findings

o Thickening of the interlobular septa- Kerley B lines

o Peribronchial cuffing- Wall is normally hairline thin

o Thickening of the fissures- Fluid in the subpleural space in continuity

with interlobular septa Pleural effusions

Kerley B lineso B = distended interlobular septao Location and appearance

Bases1-2 cm long

Horizontal in directionPerpendicular to pleural surface

Kerley B lines are short, white lines perpendicular to the pleural surface at the lung base

Kerley A and C lineso A = connective tissue near bronchoaretrial bundle distendso Location and appearance

Near hilumRun obliquelyLonger than B lines

o C = reticular network of lines**C lines probably don’t exist (huh??)

Kerley A and C lines form a pattern of interlocking lines in the lung

o Interstitial fluid accumulates around the bronchi

PERIBRONCHIAL CUFFING


o Causes thickening of the bronchial wallo When seen on end, it looks like little “doughnuts”

Peribronchial cuffing results when fluid thickened bronchial walls become visible producing doughnut- like densities in the lung parenchyma

Fluid in the fissureso Fluid collects in the subpleural space

- Between visceral pleura and lung parenchymao Normal fissure is thickness of a sharpened pencil lineo Fluid may collect in any fissure

- Major, minor, accessory fissure, azygous fissures- Minor fissure: thickened fluid- Pleural effusion: there is obliteration of costophrenic

sulcus

o Laminar effusions collect beneath visceral pleuraIn loose connective tissue between lung and the pleuraSame location for “pseudotumors”

Laminar pleural effusion can be difficult to see. Aerated lung should normally extend to the inner margin of the ribs. The white band of fluid seen here (white arrow) is a laminar effusion separating aerated lung from the inner rib margin

o If hydrostatic pressure >10mm Hg fluid leaks into the interstitium of the lung

o Compresses lower lobe vessels first- Perhaps because of gravity

o Resting upper lobe vessels ‘recruited” to carry more bloodo Upper lobe vessels increase in size relative to the lower lobe

Cephalization means pulmonary venous hypertension. As long as the person is erect when the chest X-ray is obtained

TypesPLEURAL EFFUSION

CEPHALIZATION

PULMONARY EDEMA


o Cardiogenico Neurogenico Increased capillary permeability

Congestive heart failureXray patterns1. Interstitial

o Thickening of the interlobular septa- Kerley b lines

o Peribronchial cuffing- Wall in normally hairline thin

o Thickening of the fissures- Fluid in the subpleural space in continuity with

interlobular septao Pleural effusionso Cephalization

2. Alveolaro Acinar shadowo Outer third of the lung frequently spared

- Bat-wing or butterfly configurationo Lower lung zones more affected than uppero Massive pleural effusion

In pulmonary alveolar edema, fluid presumably spills over from the interstitium to the air spaces of the lung producing a fluffy configuration “bat wing” like pattern of disease

Pulmonary Alveolar edema Clearingo Generally clears in 3 days or lesso Resolution usually begins peripherally and moves centrally

Differential diagnosis

Cardiac Renal ARDSKerley B lines and peribronchial cuffing

30% 30% None

Distribution of Pulmonary Edema

Even 90%

Central 70%

Peripheral in 45%Even in 35%

Air bronchograms 20% 20% 70%

Pleural Effusions 40% 30% 10%

CHF in Chronologic Sequence(e2 po ung last topic, pero hindi n nmin nkuha..kung meron sa inyong may notes pshare nlng.

EXCLUSIVE WONCEE TRANS …effort as in…

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Pleura and Mediastinum