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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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is not lack of knowledge but rather lack of will.
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