Pulmonary Radiologyby

The Dark HorseATSU-SOMA

The Basics

• X-rays are attenuated as they pass through the patient’s body.

• Two processes play a role: absorption and scatter.Exposure Geometry:

For the naked eye of an observer, far objects result in asmall projection and close objects in a large projectionon our retina. In projection radiography it is just the

other way around!!!Depth seen on X-ray:

Whatever is closer to the focus, i.e., farther away fromthe detector, projects larger on the detector. (It is like looking at your own shadow on a wall—the closer you get to the wall the smaller the shadow gets.

Density:

• The less dense a material the fewer x-rays it will absorb and therefore the darker it will be (ex. air)

• The more dense a material the more x-rays it will absorb and therefore the whiter it will be (ex. Bone)

• The terms opaque (whiter) and lucent (darker) are used to describe the density of a structure compared to its surrounding tissue

Densities

• Black– Air

• Gray– Water– Fluid

• White– Bone – Calcifications– Foreign objects

Typical X-ray Scanning Approach-

PA• PA: patient’s chest

against X-ray film with radiation exposure from posterior to anterior (most common). AP is less desirable (leads to magnification of structures)

• PA technique for looking at films. Encompassing the entire lung boundaries (left) , scanning with fovea over each part of lung (right).

Typical X-ray Scanning Approach-

Lateral• Lateral: usually a left

lateral film is taken unless specified differently (left side of patient is against X-ray film) Scan lung boundaries (left) , scanning with fovea over each part of lung (right).

General Overviewing of a Patient’s X-ray

• General Body Size, Shape, and Symmetry • Male vs. Female • Is this an infant, child, young adult, elderly person? • Survey for foreign objects –

– Tubes (endotracheal, NG, etc.)– IV lines (peripheral, central)– EKG leads – Surgical drains– Prosthesis– Sutures, clips, staple lines– Non-medical objects

• bullets• shrapnel• glass, etc.

Systematic Approach:Concentrate on one thing at a time and ignore everything else on the film. Your eye gaze should scan all portions of the film! Always compare sides when looking at these structures1) soft tissue/chest wall2) bones3) mediastinum4) diaphragm & abdomen5) lungs & pleura

Areas of importance on X-ray

The Silhouette sign

• The silhouette sign is in essence elimination of the silhouette or loss of lung/soft tissue interface caused by a mass or fluid in the normally air filled lung.

• In other words, if an intrathoracicopacity is in anatomic contact with, for example, the heart border, then the opacity will obscure that border.

• The sign is commonly applied to the heart, aorta, chest wall, and diaphragm. The location of this abnormality can help to determine the location anatomically.

The right heart border is silhouetted out.This is caused by a pneumonia.

Soft Tissues

Breast Tissue:

• Notice how the apparent lung density changes from the lung area covered by the soft tissue of the breast to the lung area inferior to the breast.

CHEST WALL

• Look for overall thickness, subcutaneous emphysema, calcification.

• Look for sharp, distinct muscle fat planes as illustrated on the annotated image (arrows).

distinct muscle fat planes

Fat Chest Wall

Subcutaneous Emphysema

(air in soft tissues)Extrapleural Mass

BONES• Look at each bone for the

following items: – Overall size, shape, and contour

of each bone. – The density or mineralization. – Compare cortical thickness to

medullary cavity, trabecularpattern, look for erosions, fractures, any lytic or blasticregions.

– At joints, are articularrelationships normal, joint spaces narrowed, widened, any calcification in the cartilages, air in the joint space, abnormal fat pads, etc. Multiple Rib Fractures

Lytic Lesions Ribs

Bones on X-ray

Cervical Riib

MEDIASTINUM

• At this time, look at the overall size and shape of the entire mediastinum on the frontal and lateral view.

• Also look for obvious masses and calcifications, double check for tubes, electrical leads, a pacemaker, or artificial valves.

• Check for evidence of mediastinalshift and if present, is the entire mediastinum shifted, or just a section of it.

• Look at the trachea and major bronchi for size, position, and presence of intraluminal masses.

Basic Chest X-Ray Abnormalities-Mediastinum

• Mediastinum– Widened

• Should be approximately < 1/3 transthoracic width

(< 8cm)• Cardiomegaly (enlarged

heart)

• Aortic Aneurysm

• Hilar mass

• Hiatal hernia

Thoracic Aortic Aneurysm

Cardiomegaly (enlarged heart)

Congestive Heart Failure (CHF)

Pulmonary vascular congestion and mild cardiomegaly secondary to CHF

The left image demonstrates a patient with a severe pulmonary edema as a result of CHF. The right image is the same patient after significant resolution.

HILUM

• Review hila:– normal relationships – size – Look for masses or

widening

• Calcifications:– Infections

• TB• Histoplasmosis• Others

Normal Hilum

Diaphragm/Abdomen

• Level of right and left diaphragm• Costophrenic angle• Normal gastric air bubble• Normal bowel gas• Free air• Mass• Hiatal hernia (usually presents

as mediastinal mass)• Rupture or herniation

Normal Gastric Bubble

Bilateral freeair under the diaphragmDiaphragmatic Mass

Traumatic Rupture Diaphragm

Sliding Hiatal Hernia

Can you see the air-filled "mass" posterior to the heart?

LUNGS and PLEURA

• Review lungs and pleura:– compare lung sizes– evaluate pulmonary

vascular pattern:• compare upper to lower lobe, • right to left, • normal tapering to periphery

– pulmonary parenchyma– pleural surfaces

• fissures - transverse and oblique - if seen

• compare hemidiaphragms• follow pleura around rib cage

Basic Chest X-Ray Abnormalities

• Lungs/Pleura– Too white

• Pneumonia– Increased opacity (whiteness) usually confined to particular lobe or

segment• Atelectasis

– Partial collapse of lobe or segment• Pleural effusion

– Blunting of the costophrenic angles and possible air-fluid levels• Congestive Heart Failure

– Congestion of pulmonary vasculature– May have “Bat-wing” appearance

• Nodule/Mass– Round, white, fluid density lesions– May be calcified

Pneumonia• Consolidation

– Increased opacity (whiteness) usually confined to particular lobe or segment

– In this case the Right Upper Lobe is involved

PA film of RML pneumonia (arrows).Note the indistinct borders, air bronchograms, and silhouetting of the right heart border.

Silouhette Sign Lobe-Segment

• Right diaphragm

• Right heart margin

• Ascending aorta

• Aortic knob

• Left heart margin

• Descending aorta

• Left diaphragm

• RLL/basal segment

• RML/medial segment

• RUL/anterior segment

• LUL/posterior segment

• Lingula/inferior segment

• LLL/sup. & med. segment

• LLL/basal segments

RUL Pneumonia

RML Pneumonia

RLL Pneumonia

LUL Pneumonia

LLL Pneumonia

Round Pneumonia

AtelectasisAtelectasis is collapse or incomplete expansion of the lung or part of the lung. This is one of the most common findings on a chest x-ray. It is most often caused by an endobronchial lesion, such as mucus plug or tumor. It can also be caused by extrinsic compression centrally by a mass such as lymph nodes or peripheral compression by pleural effusion. An unusual type of atelectasis is cicatricial and is secondary to scarring, TB, or status post radiation.

Atelectasis

This is a PA and lateral film showing round atelectasis, where the lung becomes attached to the chest wall by an area of previous inflammation. The lung then rolls up, causing this opacity.

Left Lung Upper Lobe Atelectasis

• The left lung lacks a middle lobe and therefore a minor fissure, so left upper lobe atelectasis presents a different picture from that of the right upper lobe collapse.

• The result is predominantly anterior shift of the upper lobe in left upper lobe collapse, with loss of the left upper cardiac border. The expanded lower lobe will migrate to a location both superior and posterior to the upper lobe in order to occupy the vacated space.

Left Lung Upper Lobe Atelectasis

• PA and Lateral of a patient with Left Upper Lobe Collapse (arrows). This characteristic finding on CXR is known as the LuftsichelSign and may represent collapse due to obstruction from a bronchogeniccarcinoma.

• The lucency between the mediastinum and the collapsed LUL is caused by hyperexpansion of the superior segment of the LLL.

Left Lower Lobe Atelectasis

• Atelectasis of either the right or left lower lobe presents a similar appearance.

• Silhouetting of the corresponding hemidiaphragm, crowding of vessels, and air bronchogramsare sometimes seen, and silhouetting of descending aorta is seen on the left.

• A substantially collapsed lower lobe will usually show as a triangular opacity situated posteromedially against the mediastinum.

Right Upper Lobe Atelectasis

• Right upper lobe atelectasis is easily detected as the lobe migrates superomediallytoward the apex and mediastinum.

• The minor fissure elevates and the inferior border of the collapsed lobe is a well demarcated curvilinear border arcing from the hilum towards the apex with inferior concavity.

Right Middle Lobe Atelectasis

• Right middle lobe atelectasis may cause minimal changes on the frontal chest film.

• A loss of definition of the right heart border is the key finding.

• Right middle lobe collapse is usually more easily seen in the lateral view.

• The horizontal and lower portion of the major fissures start to approximate with increasing opacity leading to a wedge of opacity pointing to the hilum.

• Like other cases of atelectasis, this collapse may by confused with right middle lobe pneumonia.

Right Lowert Lobe Atelectasis

• Silhouetting of the right hemidiaphragm and a triangular density posteromedially are common signs of right lower lobe atelectasis.

• Right lower lobe atelectasis can be distinguished from right middle lobe atelectasis by the persistance of the right heart border.

Pleural Effusion• Blunting of

Costophrenic angle• In this case, right side.• Also of note there is an

RML infiltrate (consolidation)

Basic Chest X-Ray Abnormalities

• Lungs/Pleura– Too Black

• Pneumothorax

• Tension Pneumothorax

• Emphysema

• Mastectomy

Pneumothorax

• Air between the visceral and parietal pleura

• Usually arising from lung injury

Tension Pneumothorax

• Large pneumothorax• Absence of vascular

markings to air filled peural space

• Causes mediastinal shift away from affected side

• Increased haziness due to atelectasis to contralateral side

Emphysema

• Darkened lung fields due to Increased air secondary to chronic obstruction

• Heart size may be decreased due to lung hyperinflation– Tube heart

• Diaphragm may be flattened due to hyperinflation

• Note overly inflated lungs in this female patient

Emphysema

Mastectomy

• Absence of breast shadow causes relatively increased darkness to right lung field

• Although right side is darker, lung markings extend across entire side

Tumor