Pulmonary Radiology

Rui Domingues, MDLincoln Mental and Medical Center

September 2008

Pulmonary Imaging Imaging techniques used to

investigate pulmonary pathology include:

Plain film Computed Tomography Magnetic Resonance Imaging Ultrasound Angiography

Keys to reading X-rays well

1. A good understanding of normal anatomy

2. A good search pattern

But before we can do this we need to understand how x-rays are produced.

Things to cover… Radiographic basics How to approach a chest x-ray Normal radiographic anatomy

Radiographic Basics

What causes the blacks, whites and grays of an x-ray image?

X-ray beams contains x-ray photons of differing energies

As these photons pass through a patient…

Some are absorbed completely Some penetrated directly to the plain film Some are absorbed partially, and While others are deflected (Scatter)

Tissue Density A product of the type of tissue and

the thickness of that tissue

Results in differential absorption

Differential Absorption Penetration of the x-ray beam is

dependent on tissue density

Denser object = less penetration

Less beam striking the film (more absorption) = WHITER

More beam striking the film = BLACKER

Glass Test Tube

Air

Fat

Water

Bone + Water

Metal

Differential AbsorptionBlack Air (Lungs / Trachea / Outside the body)

Fat (Perirenal fat / Fascial plane)

Water (Muscle / Organs)

Bone (Bone / Atherosclerotic plaquing)

White Metal (Fillings / Markers / Ortho devices)

Radiographic Image Adjacent structures of similar

densities are not visualized

Kidney (water density) against liver (water density)

Radiographic Image Adjacent structures of different

densities are visualized

Liver (water density) next to Bowel (air density)

Chest Films Minimum Diagnostic Series

PA Left Lateral

Additional Views Apical Lordotic Inspiration / Expiration

PA CXR Left Lateral CXR

Apical Lordotic CXR

Allows for better visualization of the Apices of the lungs

Expiration Inspiration

Visualizes respiratory excursion

Inspiration study

Normal positioning for PA Chest

Expiration study

Helps visualize: - Small Pneumothorax

- Air Trapping Dz (Emphysema)

- Bronchial obstruction

How to approach an X-ray?

Reading a Chest X-ray First thing:

Correctly put of the film

Then perform your search pattern which you always follow when looking at

any film this way you will miss fewer findings

Reading a radiograph Start reading every radiograph by

scanning the areas of least interest first, working your way to the more important areas.

You will be less likely to miss important secondary findings.

Chest Film Search Patterns ABCs

Abdomen Bone Chest Soft tissues

ATMLL Abdomen Thorax Mediastium Lung Lung

These are the two main search patterns that people use when evaluating a chest film.

“ATMLL” Search Pattern Remember

A = Abdomen T = Thorax M = Mediastinum L = Lungs (unilaterally) L = Lungs (bilaterally)

Searching the “Abdomen” Scan across the upper abdomen several

times

Evaluate normal gas containing structures: Stomach Hepatic flexure of the colon Splenic flexure of the colon

Evaluate the liver and on occasion one can visualize the spleen

Structures Visualized:

Stomach gas bubble

Splenic flexure

Liver

Hemidiaphragms

Abdomen dz that can mimic Lung disease include:

Subphrenic abscess

Diaphragmatic hernia

Hiatal Hernia

Searching the Bony “Thorax”

Start at the right base, look at the soft tissues of the chest wall, ribs, spine and shoulder girdle

Go up one side and come down on opposite side

Remember: Posterior ribs descend medial to lateral Anterior ribs descend lateral to medial

Structures Visualized:

Breast Tissue

Posterior Ribs

Anterior Ribs

Scapula

Clavicle

Spine

Thorax cage dz that may stimulate chest dz:

Bony metastasis

Rib / Clavicle fractures

Searching the “Mediastinum”

An organized search of the mediastinum is complicated because of all the overlapping structures.

Start with a global look for contour abnormalities, then follow with a more detailed search

Three searches of the mediastinum:

1. Trachea and carina

2. Aorta and the heart

3. Hilum

Three searches of the mediastinum:

1. Trachea and carina

2. Aorta and the heart

3. Hilum

Three searches of the mediastinum:

1. Trachea and carina

2. Aorta and the heart

3. Hilum

Three searches of the mediastinum:

1. Trachea and carina

2. Aorta and the heart

3. Hilum

Searching the “Lungs” Since most chest x-rays are ordered to

evaluated for lung disease, so the lungs are examined last.

They are important, so their evaluation should be more through, therefore we evaluate them twice. Once individually Second time comparing right and left

Structures Visualized:

Costophrenic angles

Lung fields

Pulmonary vasculature

Right minor fissure

Left Lateral Chest Film Valuable radiographic study Helps to better localize lesions Allows to visualize overlapping

tissues Allows the visualization of hidden

pathology

Searching the Lateral Chest Film

The pattern is the same:1) Abdomen2) Thoracic cage strutures3) Mediastinum4) Lungs

Search Pattern:

Abdomen

Thoracic cage and bones

Mediastinum

Lungs

Search Pattern:

Abdomen

Thoracic cage and bones

Mediastinum

Lungs

Search Pattern:

Abdomen

Thoracic cage and bones

Mediastinum

Lungs

Search Pattern:

Abdomen

Thoracic cage and bones

Mediastinum

Lungs

Search Pattern:

Abdomen

Thoracic cage and bones

Mediastinum

Lungs

What to look for… Abnormal density

Usually air versus water Abnormal shape

Lung field Mediastinum

Abnormal size Lung field Mediastinum

Abnormal location Hemidiaphragm, hila, mediastinum, trachea,

fissure, vasculature

But before that we need to have a good understanding of Normal Radiographic Anatomy

Let’s look at some of the visual abdominal

structures

Stomach gas bubble

Splenic flexure of the large intestines

Liver

Left Hemidiaphragm

Right Hemidiaphragm

Let’s look at the Bony thorax

Ribs

Spine

Clavicle

Scapula

Chest wall

Let’s look at the Bony thorax

Ribs

Spine

Clavicle

Scapula

Chest wall

Trachea on CXR

Let’s look at the normal Mediastinal Structures

Hilum

Vessels

Aortic Arch

Pulmonary Artery

Left Atrium

Left Ventricle

Inferior Vena Cava

Right Atrium

Ascending Aorta

Superior Vena Cava

Descending Aorta

Aortic Knob/Arch

Ascending Aorta

Right Ventricle

Inferior Vena Cava

Left Ventricle

Left Atrium

Upper

Middle

Lower

Lung Fields

Let’s look at the normal Lung Structures

Retrosternal Clear Space

Retrocardiac Clear Space

Lateral Costophrenic Sulci

(Recesses, Angles)

Cardiophrenic Sulci

(Recesses, Angles

Posterior Costophrenic Sulci

(Recesses, Angles)

What are the Pulmonary Fissures?

They are the coming together of the visceral pulmonary pleura.

Right lung Oblique (major) fissure Horizontal (minor) fissure

Left Lung Oblique (major) fissure

Horizontal Fissure

Right Oblique Fissure

Left Oblique Fissure

LUL

LLL

RUL

RML

RLL

A closer look at

the fissures

References Felson’s Principles of Chest Roentgenology: A

Programmed Test, 2nd Edition. Goodman, Lawrence R.; W.B. Saunders Co., 1999.

Pocket Atlas of Radiographic Anatomy. Moller, TB et al.; Thieme Medical Publishers, 1993

Clinical Imaging with Skeletal, Chest and Abdomen Pattern Differentials, Dennis Marchiori, ed. (WN 180 M317c)