Imaging Modalities for Lung Diseases (1)

5/28/2018 Imaging Modalities for Lung Diseases (1)

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IMAGING MODALITIES FOR

LUNG DISEASESAimee Esther Vicedo-Reyes, MD

Radiology Resident

January 21, 2014

BaTWO-BaTWO

INTRODUCTION Every year, more than

300 million x-rays, CT

scans, MRIs and other

medical imaging exams

are performed in the

United States

Seven out of 10 peopleundergo some type of

radiologic procedure

CHEST X-RAY

Oldest radiographic technique Most commonly performed procedure (~25%

of radiographic examinations)

Cost effective Important in diagnosis of pulmonary,

mediastinal and bony thorax diseases

Makes images of the heart, lungs, airways,blood vessels, and bones of the spine and the

chest

PROJECTION It indicates the direction in which the x-ray

beam traverses the patient on its way to the

film

There are several projections of chestradiography:

Table 1. Comparison of PA and AP views of chest x-ray

Criteria PA view AP view

Indications Routine For ill patients that

cant stand erect

Tube-filmdistance

~72 in. (6 ft.) ~40 in. (3.33 ft)

Direction of

beam

X-ray beam from

behind, plate in

front of the

patient

X-ray beam from

the front to

posterior, plate

behind the patient

Patient

position

Upright Supine

Figure 1. AP view (left); PA view (right)

Table 2. Comparison of features seen in PA and AP

views of chest x-ray

Criteria PA AP

Mongolian

hat sign

Present Absent; vertebral bodi

are rectangular

Ribs Angulated Straighter

Clavicle V-shaped More horizontal

Scapula Winging No winging

Heart

magnification

Heart not

magnified

Heart and other

structures more

magnified

Figure 2. Mongolian hat sign in PA view (left); AP vi(right)

Figure 3. V-shaped clavicle in PA view (left); More

horizontal clavicle in AP view (right)


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Figure 4. Winging of scapula in PA view (left); No

winging of scapula in AP view (right)

LATERAL POSITIONINDICATIONS

Assess mediastinal structures: heart, sternum,retrocardiac space, retrosternal space and the

lungs

Confirmation of findings in PA or AP views We use this to determine if the lesion is

anteriorly or posteriorly located

Used to evaluate blunting of posterior gutter(posterior costophrenic sulcus) in pleural

effusion

IMAGE CRITERIA

Ribs posterior to the vertebrae should besuperimposed

Costophrenic (CP) angles and lung apicesincluded

Hilar region should be at the center Circular structures on this view may represent

blood vessels

OBLIQUE POSITION

INDICATIONS

Assess tracheal bifurcation Study heart, hilum and ribs Tracheal lumen should be normally about

1.5cm in diameter

If it is wider then one should suspect apathology

Figure 5. Lateral view (left); Oblique view (right)

APICOLORDOTIC (AL) POSITION

Lung apices viewed better Leaning backward in exaggerated lordosis The anterior and posterior segments of the

same ribs are superimposed

Figure 6. AL position (left); AL view (right)

LATERAL DECUBITUS POSTION

Patient lying on his side for 10-15 minutes Can detect the following:

o Pleural effusions: mobile vs. loculateo Small pneumothorax

Figure 7. A patient in position for a right lateral

decubitus position (left); Example of a decubitus fi

in this case showing mobile pleural effusion(right


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When we suspect that the problem is effusion,the patient should lie on the ipsilateral side

For pneumothorax, we ask them to lie on thecontralateral side so that the air will rise to the

non-dependent portion of the lungs

FLUOROSCOPY

Not normally used It is more used when we assess the activity of

the structures involved like the diaphragm and

the heart

Only indicated for patients with acuteobstructive overinflation secondary to

aspiration of foreign body

Uses a higher radiation exposure When used, necessary to use smallest aperture

so that the radiation exposure is limited

Limit total fluoroscopic time to reduceradiation exposure (


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COMPUTED TOMOGRAPHY

Uses series of x-rays to produce detailedimages of the inside of the body

Offers a spatial resolution in the submillimeterrange (15mm)

Best methodin evaluating very small lesionswithin the lungs

Main tool for the diagnosis and staging of lungcancer

HIGH RESOLUTION CHEST TOMOGRAPHY (HRCT)

Based on thin (15 mm) sections Method of choicefor assessing lung tissue Analyzing diffuse lung diseases such as

pulmonary fibrosis, emphysema or diseases

affecting the airways

Help locate the abnormality and suggest themost suitable location for a histological biopsy

In CT scan, we usually do CT-guided biopsy if thelesion is adherent to the pleura. We do not dobiopsy if the lesions are centrally-located due to the

risk for pneumothorax

MULTIDETECTOR CHEST TOMOGRAPHY (MDCT)

Most high-end CT machines Uses multiple detectors Allows for production of cross sections through

the chest in any direction (axial, sagittal or

coronal)

Produces three-dimensional (3D) imagescompared to HRCT

USES IN LUNG IMAGING

Evaluation and staging of primary pulmonaryneoplasm

Detection of pulmonary metastases fromnonpulmonary primary tumors

Characterization of solitary pulmonary nodules Characterization of focal and diffuse lung

diseases

Useful in guidance for needle biopsy Helpful in the study of cavitary masses,peripheral lung tumors and pulmonary collapse

USES IN MEDIASTINAL IMAGING

Study the causes of mediastinal wideningwhether tumor/neoplasms or aortic

dissections/aneurysms

Staging of tumors that spread to themediastinum

Characterization of mediastinal masses fordiagnosis

Localization of mediastinal masses whether in the anterior mediastinum, midmediastinu

or posterior mediastinum

USES IN PLEURAL IMAGING

Localization and evaluation of extent ofplaques, masses, loculated fluid and occultcalcification

USES IN CHEST WALL IMAGING

Study of masses involving soft tissue, bone,spinal canal and adjacent lung

ADDITIONAL USES

Evaluation of chest involvement in trauma

Figure 11. Example of chest CT results

MAGNETIC RESONANCE IMAGING (MRI)

Latest technique for lung examination Uses subtle resonant signal that can be

obtained from hydrogen nuclei (protons) of

H2O or organic substances when they are

exposed to a strong magnetic field and excit

by precise radio frequency pulses

Provides more functional information andexcellent morphological imaging capacities

ADVANTAGES

No radiation hazard or other known biologicrisk

Images may be acquired without use ofmechanical motion devices and views in

multiple planes can be acquired directly

IV contrast agents are not necessary to idenintrathoracic vascular structures or to show

presence of vascular flow


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Greater ability than CT or plain films todifferentiate types of tissue based on signal

characteristics

Magnetic resonance angiography is capable ofdemonstrating some vascular anatomy in a

display format comparable to that of

conventional angiography, but non-invasively

DISADVANTAGES Motion artifacts cause degradation of the

images

Imaging of lung parenchyma is poor due to lowproton density of the lung tissue and the many

air-tissue interfaces that cause loss of signal

Patients witho cardiac pacemakerso ferromagnetic intracranial aneurysm

clips

o metal fragments in the eye or near thespinal cord

o cochlear implants, ando neurostimulators

cannot be examined

Claustrophobia Longer time required for most MRI

examinations

Higher costAPPLICATIONS

Assessment ofo aortic vascular disease,o subacute and chronic dissection,o vascular anomalies, ando venous obstruction of mediastinal and

subclavian vessels

o chest-wall lesions and infections Cardiac evaluation of selected congenital and

acquired heart conditions and pericardial

diseases

Evaluation ofo brachial plexopathy including

determination of the extent of

pancoast tumors,

o the diaphragm and peridiaphragmaticprocesses

o intracardiac and paracardiac massesincluding staging of tumors that may

potentially involve the heart,

pericardium, or pulmonary arteries and

veins,

o breast implants for rupture and breastmasses, and

o congenital and developmentalanomalies of the pediatric chest suc

as

vascular rings, coarctation of the aorta, lympangiomas, and sequestrations

Determination of the extent of posteriormediastinal masses, especially those withintraspinal extension

Detection of ectopic parathyroid adenomas the mediastinum

Figure 12. Examples of chest MRI results

POSITRON EMISSION TOMOGRAPHY

Uses radioactive tracers and photon detecto Based on injection of radioactive-labelled

biomolecules (tracers), which are then follow

and detected (enhancement)

18F-fluorodeoxyglucose (FDG)o Most widely used tracer

ADVANTAGES

Improved diagnostic accuracy for staging Allows detection of lesions not initially seen

CT or PET

More precise lesion localization Better delineation of surrounding structures Better characterization of lesions as benign o

malignant

DISADVANTAGES Small lesions (


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Figure 13. Examples of PET Scan Results. Areas

pointed out by the arrows are sites of metabolic

activity

PULMONARY ANGIOGRAPHY

Outline the pulmonary arterial system Used to study patients with suspected

pulmonary arterial or venous anomalies or

diseases

Study of thromboembolic disease of the lungsby means of pulmonary arteriography

Needed when the diagnosis remains in doubtafter roentgen and scintiscan studies

When patient is not responding to treatmentfor presumed pulmonary embolism

TECHNIQUE Injection of contrast material into the superior

vena cava with the use of digital subtraction

angiography (DSA)

Injection of contrast material into the rightatrium using DSA

Direct injection of contrast medium through acatheter placed in a main pulmonary artery

Selective injection of contrast material into apulmonary artery branch using DSA or balloon-

occlusion cineangiography or serial filming

ADVANTAGES

A very small amount of iodinated contrastmaterial is necessary

DISADVANTAGES

Artifacts produced by motion Limited field of view

Figure 14. An example of pulmonary angiography

showing several PAVMs (Pulmonary ArterioVenous

Malformations) in a patient

BRONCHIAL ARTERIOGRAPHY

Requires selective catheterization of broncharteries

LIMITED use in pulmonary disease Still plays a therapeutic role in the treatmen

selected cases of life-threatening hemoptysi

that may be mitigated with bronchial arteria

embolization

Not available in our localityPERCUTANEOUS TRANSTHORACIC NEEDLE BIOP

Used extensively to obtain material forhistologic and bacteriologic study

INDICATIONS

Peripheral lung masses beyond the reach offiberoptic bronchoscopy

Focal or general pulmonary infections inimmunocompromised hosts

ADVANTAGES High diagnostic yield Low incidence of complications

MAJOR COMPLICATIONS

Pneumothorax Hemorrhage


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CONTRAINDICATIONS

Patients with bleeding diathesis orthrombocytopenia

A suspected vascular lesion Recent severe hemoptysis Severe dyspnea at rest Those who cannot cooperate

CHEST ANATOMY REVIEW

Figure 15. Normal Radiographic Anatomy of the Chest

LUNGS

Right hilum is lower than the left Right HHR is approximately 1/2 : 1/2 Left HHR is approximately 1/3 : 2/3

* Hilar Height Ratio (HHR) value that expresses the

normal position of a hilus in its hemithorax. Pulmona

volume changes, infrapulmonary and subphrenic

processes may produce an abnormal hilar height rat

Detection of pathologic states that do not alter therelative hilar heights is made possible by the

recognition of this abnormal ratio. It is calculated by

dividing the distance from the hilus to the lung apex

the distance from the hilus to the diaphragm.

Figure 16. Shows the comparison of the Right HHR a

Left HHR

BRONCHOVASCULAR RATIO

Diameter of bronchus and artery thataccompanies it should be 1:1

If artery is larger than the bronchus:congestionor edema

If bronchus is larger than the artery:Bronchiectasis

RIGHT LUNG

3 lobes and 2 fissureso Minor fissure Horizontal, at 4thrib

Separates the RUL from theRML, and thus represents th

visceral pleural surfaces of b

of these lobes

o Major fissure From T3 spinous process to

costal cartilage anteriorly

Oriented obliquely


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Separates the right lower lobefrom the upper and middle

lobes

Figure 17. Shows the different locations of the fissures

on CXR results

RIGHT UPPER LOBE

Occupies the upper 1/3 of the right lung Anteriorly: extends inferiorly as far as the 4th

right anterior rib

Posteriorly: adjacent to the first three to fiveribs

Figure 18. Shows the location of the RUL on CXR films

RIGHT MIDDLE LOBE

Smallest lobe Triangular in shape, being narrowest near the

hilum

Figure 19. Highlights the locations of the RML

RIGHT LOWER LOBE

Largest of all three lobes Separated from the others by the major fissu Posteriorly: extend as far superiorly as the 6

thoracic vertebral body, and extends inferio

to the diaphragm

Figure 20. Shows the RLL on CXR film

LEFT LUNG

2 lobes and 1 fissureo

Major fissure Divides left upper and lower

lobe

No defined left minor fissure There are only two lobes on the left

o Left upper lobeo Left lower lobe


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Figure 21. Shows the areas occupied by the LUL and

LLL on CXR film

Two lobes are separated by a major fissure,identical to that seen on the right side,

although often slightly more inferior in location

The portion of the left lung that correspondsanatomically to the right middle lobe isincorporated into the left upper lobe

BRONCHOPULMONARY SEGMENTS

Each pyramid shaped segment is:o Enveloped by a connective tissue

sheath

o Supplied by a single segmentalbronchus and a single pulmonary

arterial branch

o Orient so that its apex projects towardsthe hilum of the lung

The importance has increased now thatsegmental resection and sub-segmental

pulmonary resection are common procedures

SEGMENTS OF THE RIGHT LUNG:

Upper lobe1. Apical2. Anterior3. Posterior

Middle lobe4. Lateral5. Medial

Lower lobe6. Superior7. Medial basal8. Anterior basal9. Lateral basal10.Posterior basal

SEGMENTS OF THE LEFT LUNG

Upper lobe1. Apical posterior2. Anterior3. Apical posterior4. Superior lingular5. Inferior lingular

Lower lobe6. Apical7. Anteromedial Basal8. Anteromedial Basal9. Lateral Basal10.Posterior Basal

Figure 22. Shows the areas of the different segment

of the lungs on CXR

TRACHEA

Midline, within the boundaries of the vertebbody

Location: C6-T5 Bifurcates at the level of T5


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Subcarinal angle must be


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Figure 26. Show how to calculate for the CTR. Obtain

line A by measuring from the middle up to the mostlateral border on the right side. Line B is by measuring

from the middle up to most lateral border on the left

side. Add A and B, then divide it by C which can be

obtain by measuring the length of the chest wall as

shown above.

MEDIASTINUM

The space between the two pleural sacs whichcontains all the structures in the thorax except

the lungs and the pleura

Note for obliteration of spaces Note for opacities

MEDIASTINAL WIDTH

Upright: 8 cm

Supine: 10 cm

FELSONS DIVISION

Anterior: Everything from the sternum tothe posterior aspect of the heart and great

vessels

Middle: The compartment posterior to theheart and great vessels, to a line drawn 1

cm posterior to the anterior edge of the

thoracic vertebrae

Posterior: The space behind the posteriorlimit of middle mediastinum

Figure 27. Felsons division

ANTERIOR/ PREVASCULAR

Loose areolar tissue Lymph nodes Lymphatic vessels

MIDDLE/ VASCULAR

Heart and pericardium Ascending and transverse aorta SVC Other main vessels (ie. pulmonary artery Main veins Trachea

POSTERIOR/POST-VASCULAR/NEURAL

Thoracic portion of descending aorta Esophagus Thoracic duct Azygos and hemizygos veins Sympathetic nerve

COSTOPHRENIC SULCI

Check if it is sharp/blunted Bluntedmay denote presence of pleural

effusion

HEMI-DIAPHRAGMS

Right hemi-diaphragm is higher than the left Lies at 5th ICS on moderately deep inspiratio The curvatureof both hemi-diaphragms

should be assessed to identify diaphragmati

flattening


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Figure 28. Outlines the hemi-diaphragms

*HEMIDIAPHRAGMS

Convex cephalad Right hemi-diaphragm is higher than the left

because of the liver

The cardiac apex on the left pushes the diaphragmdownwards

During moderately deep inspiration, the dome ofthe diaphragm on the right lies in the region of the

5th anterior intercostal space while the left is

slightly lower (usually by intercostal space)

Figure 29. Hemi-diaphragm

OTHER STRUCTURES Portions of liver, spleen, gastric fundus are

routinely visualized on most x-rays

Enlargement of liver cause right diaphragmaticelevation & lateral compression of stomach

SOFT TISSUES

-look for swelling

BONE

-look for osteolytic/osteoblastic and other lesions

-look for fractures

OTHER MASSES: BREAST MASS

-look for opacities and lucencies in other areas

Figure 30. Interpret the findings

REPORTING OF RESULT:Normal

There are no lung infiltrates.

Trachea is at midline.

The heart is not enlarged.

The costophrenic sulci are intact.

The hemi-diaphragms are smooth.

The rest of the findings are unremarkable.

IMPRESSION:

Essentially negative cardiopulmonary findings

COMMON PATHOLOGIES ENCOUNTERED

Figure 31. Pneumonia


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Figure 32. Pleural effusion

Figure 33. Chest x-ray of patient with pulmonary

tuberculosis showing cavitation (arrowheads)

Figure 34. Pulmonary tuberculosis

Figure 35. Pneumothorax

Figure 36. Pulmonary Mass

Pleural effusion


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POST QUIZ

1. What chest x-ray projection shows a moremagnified heart?

ANSWER: AP view

2. What position is used to evaluate lesions in thelung apices?

ANSWER: Apicolordotic view

3. What position checks for mobility of fluid andpresence of small pneumothorax?

ANSWER: Lateral decubitus view

4. What position is used to evaluate retrosternaland retrocardiac spaces?

ANSWER: Lateral view

5. What projection shows a more horizontalposition of the clavicle?

ANSWER: AP view

References: Lecturers slides, audio

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The difference between a successful person and others

is not lack of knowledge but rather lack of will.

-Vince Lombardi

Imaging Modalities for Lung Diseases (1)

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