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RADIOLOGY QUIZ 1 REVIEW
Radiology Quiz 1
Review
Chapter 1: Cynthia Russell, Paula Arneson
Chapter 2: Abed Makkawi
Chapter 4: Irina Inoyatova
Chapter 5: Irina Inoyatova
Chapter 6: Renee Aboushi
Chapter 7: Christine Hannah
Chapter 8: Irina Aminova
Chapter 9: Leo Yagudayev
Chapter 10: Lauren Montemayor, Chris Yagliyan
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RADIOLOGY QUIZ 1 REVIEW
CHAPTER 1: BASIC CONCEPTS
 X-rays produced by bombarding tungsten target with an electron beam
 They are a form of radiant energy similar visible light
 X-ray wavelength shorter than that of visible light
Science of radiology based on this difference since many substances that
are opaque to light are penetrated by x-rays
 In 1895 Wilhelm Conrad Roentgen recognized that he had unintentionally produced
a hitherto unknown form of radiant energy that was invisible, could cause
fluorescence, and passed through objects opaque to light.
 Roentgen had been working with apparatus that caused emission of x-rays as
byproduct; he observed that whenever apparatus was working a chemical-coated
piece of cardboard lying on table glowed with pale green light. When he placed his
hand b/w source and cardboard, he could see the bones inside his fingers w/in the
shadow of his hand.
 There is a difference between what Roentgen saw fluoroscopically and what we see
on x-ray: it was the reverse of all the light-dark values you see on x-ray.
 Fluoroscopic light very faint unless amplified electronically so you will probably not
see much fluoroscopy in your lifetime
 When light hits photographic film, a photochemical process takes place in which
metallic silver is precipitated in fine particles within the gelatin emulsion , rendering
the film black when developed chemically: places that are not exposed remain clear;
when positive paper print is made of “negative” film values are reversed: the black
areas prevent light from reaching the photosensitive paper while clear areas in the
film permit paper to be blackened
 X-ray films equivalent to the negative photo films
 X-rays slower than light waves; since patient cannot be expected to hold still for too
long and too much radiation is dangerous reinforcing technique was invented
 Special film container called Cassette.
o Cassette contains two fluorescent intensifying screens which are
activated by x-rays and in turn emit light rays that reinforce the
photochemical effects of the x-rays on the film
o Theses special cassettes permit imaging with less radiation and faster
exposure
o Object placed between the x-ray beam source and cassette prevents
light activation of fluorescent screen and no silver will be precipitated
 Recently change from traditional way (analog imaging) to digital way of imaging
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o Digital images are stored and distributed through the radiology dept.
and medical center over a large computer network called PACS
(picture archiving and communications system)
o Images can also be viewed on the internet by referring physicians
o Advantage: no x-ray film costs, no lost films, no large film storage
spaces, no personnel needed to retrieve images, viewers can
manipulate images (alter contrast, brightness, magnify image)
o Images can also be sent over normal or high-speed telephone lines for
remote review or interpretation (teleradiology)
 Traditional X-ray: ex. hand
o Parts of film not covered by hand: blackened
o Soft tissues of hand: film appears gray
o Bones: due to calcium (absorb more x-rays than soft tissues)lighter
gray
o Gold ring: (each metal absorbs according to its thickness and atomic
number): no x-rays passedcompletely white
 Dense objects white (radiopaque), less dense more gray or black
(radiolucent)
 Metals and metallic salts are relatively radiopaque, so therefore also mixtures of oil
and brilliantly metallic salts responsible for whole field of oil painting
 Radiography of painting and other works of art fascinating and
technically useful branch of the science. Frauds, inept reconstructions and
masterpieces painted over by amateurs may sometimes be detected by xrays (if you want to read more about this p.6 I didn’t think it was that
important, but I might be wrong, so be safe and read it)
 Industrial uses of x-rays: Flaws, cracks, and fissures in heavy steel can be shown by
x-raying big equipment or building materials (this requires more penetrating x-ray of
very short wavelength)
 Wavelength
o X-rays with very short wavelength called hard x-rays: to study destroy
malignant tumors (radiation therapy)
o X-rays with longer wavelength called soft x-rays: to study thin,
delicate objects (bone or tissue section of 1 or 2 microns in thickness
(microradiography)
o Wavelengths that lie in between used for medical x-ray diagnosis
 X-ray technologists trained to choose appropriate wavelength suited to the density
and thickness of part they are filming by
o varying kilovoltage of machine
 The higher the voltage the harder or penetrating the x-ray
o vary amount of radiation by altering milliamperage used
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o they can control time of exposure (thin object short time, dense object
long exposure
Radiodensity as function of composition, with thickness kept constant
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As you look at an x-ray you should consider the “relative radiodensity of all
structures”
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Radiolucent structures- are less dense and appear dark in the x-ray (for example:
air),because the sparse air molecules offers almost no obstacles to the rays.
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Subcutaneous fat is also radiolucent!
Blood, muscle and liver will have the same shade of light grey in the x-ray
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Radiopaque structures like bone appear as in lighter or white color in the x-ray.
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Remember: all moist solids or fluid- filled organs and tissue masses will have
about the same radiodensity. For example the muscular heart with its blood-filled
chamber: in the x-ray you see a homogeneous mass much denser than the aircontaining lung on both sides of it, but showing no differentiation between
muscular ventricle wall and blood within the ventricle.
Radiographs as Summation Shadowgrams
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The x-rays are radiant energy of very short wavelength, beyond light in the
electromagnetic spectrum, and that they penetrate, differently according to their
wavelength, substances opaque to light.
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The beams of X-ray penetrate a complex object like the hand in accordance with
the relative radiodensities of the materials which compose the object.
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Also remember that radiodensity is a function of anatomic number. The higher the
anatomic number, more dense is the structure.
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A sheet of uniform composition, if it lies flat and parallel to the film, will have a
uniform x-ray density and cast a homogeneous shadow. However if this same
sheet is curved, those parts that lies perpendicular to the film, or in the plane of
the x-ray, is equivalent to many thickness. Example: imagine the density of the xray of a rose petal ( when the petal is flat and parallel to the film) and the same
rose petal, when the petals are not parallel to film( bent). The bent petals are
going to be appear more dense than the single flat petal).
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CHAPTER 2: THE IMAGING TECHNIQUES
YOU MUST THINK IN LAYERS WHEN LOOKING AT ANY RADIOGRAPH
PA Film
 Air-filled lungs  radiolucent, muscular fluid-filled radiolucen
 Structures through which the x-ray beam has passed from back to front.
 Always place CX film as if you are facing the pt. (only possible with PA and AP
views)
 AP is less satisfactory: usually done when pt. is too sick to leave the bed.
 The normal AP chest film looks different for the following reasons: enlarged heart
shadow, position of Pt is leaning back, post ribs look more horizontal, diaphragm
higher, less lung volumes (b/c can’t take as deep a breath)
 After standard PA film, the next most common view is the lateral usually the left
lateral b/c the heart s closer to the film and is less magnified.
 Lordotic view- apices; first you do AP film and nothing shows but you have a
suspicion to TB and then you do lordotic: projects clavicles upward
 PA oblique to study ♥ or hila region
 Conventional Tomographic- studies effectively slice the living pt. so that you
can study the shadows cast by certain structure free of superimposed shadows.
(only the structures in one plane will be in focus in the tomogram)
 Made by moving x-ray tube and the film around the pt. during exposure.
 Conventional tomograms are less likely to be requested today than in the past
been replaced by Computed tomography.
 Fluoroscopy – real time visualization of Pt’s, art/veins. Used during contrast
exam of GI trat to follow course of barium thru esoph, stomach + bowel. Also for
catheter placement for angio procedures. During procedure, continuous beam of
Xray passes thru  image on screen. (**Black + white r rev.; bone + contrast,
dark; radiolucent lungs are white**)
 Angiography – IV of iodinated contrast agents into vascular.
 Images Arterial structures- arteriogram
 Images of venous structure- venograms
*Allergy to iodine; arteriogram / venograms; arterial system usually opacified by
contrast, done under fluoroscopic guide
 CT – cross-sectional slices, ID masses or bleeding, focused w/o superimposition.
Range of densities (id conditions). Denser tissues – white (bone); less dense –
dark; air is black. 5mm slices. Contrast media may be used to enhance diff
densities (ie: GI, colonic)
 CT Angiography- form of 3D CT. vascular system w/ short time with a bolus of
contrast; to evaluate aortic aneurysms, dissection, stenosis, atherosclerotic
plaques, Fx’s
 HI speed CT allow for uninterrupted scanning, Pt moves thru scanner, tube
moves ~ Pt, 90sec.
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 Ultrasound – echogenic (solid) vs. anechoic (liquid); air + bone can’t be
visualized well,
5 adv > CT;
1.no ionizing radiation, no bio injury,
2. any plane/direction,
3. OB/GYN, pediatric, testicular,
4. less $,
5. portable & moving images.
Disadv: more time than CT up to 20-30 mins; technician-dependent
 MRI – no ionizing radiation, powerful magnet; 2D picture, imaging H+ atoms, fat
& H2O molecules; bone is dark; White – strong signals, black – little signal or
none (or gray). Compact bone, black; fat = brite white. Adv > CT; direct
multiplanar scanning is possible.
 Radioisotope scanning – nuclear imaging; visualization of living organ via
radionuclide injection. Chemical stays long enough for organ to be visualized;
short ½ life to minimize radiation. Technetium – 99M is the MC; thyroid + lung.
 **Bone scan is commonly requested, good for locating bone metastasis, detects
Fx not seen on X-ray; sees bone healing itself; Ca will show where technetium
collects
 PET – positron-positron radioisotope is injected intravenously or inhaled as a gas.
Earlier detection of some cancer; reveals increased metabolic activity; heartblood flow, Sx of CAD and Brain- suspected epilepsy; Alzheimer’s.
Chapter 4: How to Study the Chest
The system generally employed:
o Look at various structures in a deliberate order concentrating on anatomy
of each while excluding the superimposed shadows of other structures
o Adopt a definite order
 Begin with scapulae
 Then look at portions of humerus and shoulder joint
 Inspect clavicles
 Then study ribs in pairs (ALWAYS COMPARE SIDES)
 Spine and sternum (Super imposable)
Technique used for chest films designed to study lung
Projection
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Can alter the appearance of structures far away from the film
Broad-chested → little of shoulder girdle and humerus is seen
Small- chested→ most of shoulder and most of upper arm seen
Overlap shadow → added densities of tissues overlapping each other
Thickness and composition determines radiodensity
Fat, Skin, Muscle less radiodense than bone, the shadow cast by a thick mass of
those tissues will approach that of a bone.
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Rib Cage
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Technique:
o Bilateral system of each pair of rib
o Begin at origin of 1st rib at its junction with 1st thoracic vertebra
o Trace each rib as far anteriorly to the beginning of radiolucent costal
cartilage
Ribs locate an abnormal shadow by its proximity to a particular rib or interspace
Go over Figure 4.9
When observing concentrate on posterior halves on ribs then on anterior
Confusing Shadows Produced by rotation
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Bc of curved shape, clavicles appear symmetrical w/ no rotation of chest
True PA film:
o Beam passes thru midsagittal plane
o Arms and shoulders symmetrical
o If turned clavicles exhibit remarkable degree of asymmetry
 Helps distinguish b/w a true PA or AP film without rotation
Slight rotation is undesirable bc heart and mediastinum are radiographed
obliquely and their shadows appear enlarged and distorted
Importance of Exposure
Thoracic spine not well seen bc its density is added to mediastinal structures and
sternum together absorb all rays
To ↑ penetration- ↑ exposure factors (kilovoltage, milliamperage, exposure time)
o This produces a beam of x-rays of shorter wavelength so harder rays
o This is called an overexposed film intentionally to ↑ penetration of dense
structures
Scattered x-rays can happen
o ↑ exposure factors to produce a harder and more penetrated beam- ↑ amt
of scattered x-rays
o hence a simple overexposed film can lack contrast and sharpness
Bucky grid device- eliminates scattered rays
o Flat grid composed of alternating thin strips of radiolucent and radioopaque material
o Only most perpendicular rays pass thru the lucent plastic strips
o If interposed grid is motionless, lead strips will appear white lines so need
to move grid across film throughout exposure
Always observe soft tissue
Chapter 5: The Lung
Normal Lung
 Lung usually radiolucent bc of increased air
 Spherical structure + uniform composition → round shadow
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Knobby and irregular → knobs present
Cylindrical like blood filled vessels → tapering linear gray shadow
Branched vessels→ the shadow will branch
Vessels that pass thru lung parallel to film and perpendicular to ray → tapering
and branching will be accurately rendered on the PA film
 If passes thru a sagittal direction→ lines w/ beam absorbing more x-rays so
shadow appears dense round spot
 Tracheobranchiol tree is rendered visible
o Bronchography
 Large vessels in hilum cast heaviest and widest shadows (medusa like tangle of
arteries)
 Right hilar extends out further than left hilar bc left obscured by heart
 Left Hilar is higher than right
Variations in Pulmonary Vascularity
 With left heart failure and pulmonary stenosis, the lung root may be enlarged bc
of engorgement of veins.
 Dilation of the arteries → in congenital heart disease
 In judging the appearance of hila can decide if vascular trunks are enlarged of not
 Lung is thicker medially where it borders the mediastinum than its lateral
extremity, s more vessels superimposed on medial half of lung on radiograph.
 In the upright pt, there is increased flow to the lower lobe vessels, which increase
their caliber.
 Many vascular trunks overlap so it can get hard to understand abnormalities.
 The truly comparable part of left lung lies closer to the midline obscured by
shadow of heart.
 Hilar enlargements are usually visible and can have overlapping
o Can have primary tumor masses round and smooth, unilateral
o May cast shadows and superimposes on the hilum
 Conventional tomography used to distinguish masses
 Computed tomograpghy- Preferred method
o Bilateral Hilar Adenopathy can be seen with nonmalignant conditions
 Masses are clusters of enlarged hilar nodes
 Vascular hilar enlargements
 With contrast CT, hilar enlargements due to tumors or nodes can
be routinely distinguished from vascular hilar enlargements.
Pulmonary Microcirculation
 Look at All Figures Pg. 100
Solitary lesions in lung
 Look at example
Air space and intestinal disease
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 2 different patterns
A. Air- Space disease
a. Involves alveoli filled with fluid that displaces the air in them
b. Alveoli appear white and radio opaque
B. Interstial disease
a. Distribute through the lung
b. Produces linear stands of density or spherical densities which are
superimposed
 Taking pts history will determine which disease it is
C. Bilateral disseminated interstial disease
a. Nonspecific pattern on CXR
Importance of Clinical Findings
 Pt history is important
 Inform radiologist of any clues of past history so they can make a Diagnosis.
 Include all clinical information and write out a requisition, so that radiologist can
best advise you.
High resolution CT of lung
 Ct most useful bc of its resolution for fine detail and ability to sort out
superimposed parenchyma structures
 Can show evidence of definite lung abnormality when plain films on chest are
normal , visa versa
 It can also assist in making a more specific diagnosis
 CT technique that examines the lung is called high resolution or HRCT
 Thin slices obtained after pt takes deep breathe
 It yields images that are superior in visualization to images provided by plain fils
of the bronchi and blood vessels, interstitial connective tissue and air spaces.
 4 different lung patterns seen
o reticular opacities
 thickens the interstitial fiber network with fluid, fibrous tissue,
inflammatory cells, or tumor cells
 appearance at a CT would be thick tissues around airways and
blood vessels
 bronchovascular thickening
o Nodular opacities
 Represents inflammatory diseases
 Sarcoidosis
 TB
 Metastatic disease
o Pulmonary consolidations
 Can be detected earlier
 Common Ct appearance “Ground Glass”
 Represent ongoing acute conditions such as pneumonia and
pulmonary edema
o Focal areas of decreased lung capacity
 In pts with air trapping and lung destructions
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Ex emphysema- enlargement of distal air spaces
Chapter 6: Lung Consolidation & Pulmonary Nodules
Consolidation of a Whole Lung
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Massive lung consolidation- attained density of soft tissues and airless due to a
pathological process
The part of the lung that has attained soft tissue density (opacified) will cast a
uniform shadow of approximately the same density as the heart shadow, and its
projected opacity will relate to the shape of the part involved
A normal heart shadow is thrown into relief by the normally aerated lung (black)
The two domed diaphragmatic shadows are seen in relief because there is air in
the lung above them
The stomach bubble under the medial half of the left hemi diaphragm may be seen
in the upright patient
If the entire left lung becomes consolidated; the heart, mediastinal structures, and
dense lung will be of all the same densities. The left side of the heart border
disappears because the shadows merge into one
If the right lung solidifies; the liver, right lung, and heart will be identical in
density. Their shadows will merge
Disappearance of borders implies solid change in the lung next to them because
the usual solid-air roentgen interface no longer exists
Any consolidation against the mediastinum will result in loss of a part of the
mediastinal border. Any consolidation of the base of the lung will erase the border
of the diaphragm or segment of it
Consolidation that erases the border of the heart must be located in the anterior
part of the lung
Consolidation of One Lobe
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Consolidation of the upper and middle lobes on the right would lead to the right
heart border disappearing but the profile of the diaphragm would be preserved by
the well aerated lower lobe
The oblique planes of the two major fissures are important because their location
will be visible in the lateral view
The fissures appear as a thin line of density outlined on both sides of the lung
The minor fissure on the right should be thought of as roughly horizontal,
extending forward and laterally from the middle of the major fissure – forming
the floor of the right upper lobe and the roof of the right middle lobe
Exercise
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A solid sphere within the lung will project as a circular shadow on either the PA
or the lateral view
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RADIOLOGY QUIZ 1 REVIEW
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Assymetrical wedges will project differently according to the direction of the ray
passing through them
The middle lobe is a good example because it is a long wedged x-rayed end-on in
the PA view and appears as a much smaller shadow than it does when its full
length is seen in the lateral view of the chest
Consolidation of Only a Part of One Lobe
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Consolidation of all the lung tissue against the diaphragm will cause the outline of
the diaphragm to disappear, but a patch of dense lung against the lateral half of
the diaphragm will cause the disappearance of only the lateral half of its outline,
leaving the medial half visible
If you see an xray where the lower left lung looks opacified but you can
nevertheless see the entire diaphragmatic margin, then there must be air within the
lower lobe
If you cannot see any part of the diaphragm but you see the left heart border
through the dense lung, then there must be air in the upper lobe against the dense
heart
If the heart border is preserved then most likely the posterior part of the chest is
the section that is involved
Pneumonia and tumor can both produce solid areas in the lung: pleural fluid and
atelectasis are common with these pathologies
Consolidation of lobar pneumonia should be thought of a pure air-space disease
If the pathological change is interstitial then expect to see linear strands of density
on the radiograph
Collapsed lung produces the same appearance as consolidation except there will
be evidence for the change in the size and shape of the lung involved
Collections of fluid in the pleural space can also produce opacities in the thoracic
cavity, obscuring the lung it envelopes AND causing the disappearance of the
diaphragmatic outline
Solitary and Multiple Pulmonary Nodules
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A solitary pulmonary nodule could be something as unimportant as an old
granuloma from prior histoplasmosis or TB, or lung cancer
If a nodule is neoplastic, it could be either a benign or malignant tumor; and if
malignant it could be either a primary lung cancer or a single metastsis from
any number of distant primaries
If you fine a SPN on a chest film, refer back to the patients prior chest films
for comparison
If the nodule is unchanged you can assume that the nodule represents a
benign, old granuloma
If the mass contains calcium that is central and densely particulate, it is most
likely a benign granuloma
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Diagnostic evaluation is mandatory if there are no old films or if the nodule
didn’t appear on the earlier films
If multiple nodules are present, then the clinical workup must focus on a
search for metastatic disease or inflammatory conditions associated with
multiple nodules, such as sarcoidosis or histoplasmosis
If nodules are absent from the chest film, request a CT scan. CT scan can
show nodules too small to be shown by plain films or nodules in locations
difficult or impossible to identify on plain films
If the nodule is a primary lung cancer, CT may demonstrate metastases to the
mediastinum that are not seen on chest films.
No nodules on a CT scan requires a tissue diagnosis
For a nodule that is located in the lung periphery, a tissue sample may be
obtained by percutaneous needle aspiration biopsy under CT guidance
Chapter 7: The Diaphragm, the Pleural Space, and Pulmonary Embolism
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The sum of the densities just below the level of the dome of the diaphragm on the
radiograph includes a part of the lung posteriorly and the dense liver or spleen,
solidly applied against its inferior concave surface.
The diaphragm:
 Is anatomically composed of a thin sheet of muscle attached to the
xiphoid, lower 6 costal cartilage, ribs, and upper lumbar vertebrae
 itself contributes little to the white density on the chest film
 is a dome shell dividing the chest from the abdomen
 contracts downward and flattens on inspiration
 relaxes upward on expiration
 may be elevated due to large collections of fluid in peritoneal space,
obstruction in the GI system, abdominal surgery, or in the 3rd trimester of
pregnancy
 may be depressed or flattened due to any condition that increases the
volume within the thoracic cage such as emphysema, pleural fluid, or
tumor masses in the lungs
Gastric bubble shows a straight line marking the fluid level, above which air provides
a radiolucent pocket for air to pass
 No bubble will be seen on a patient laying down
 Air acts as a contrast substance, forming a radiolucent cast of the hollow
structure containing it, just as barium sulfate and other safely inert
substances from the radiopaque fluid casts of the hollow structure into
which they are introduced
 Gastric bubble should be included in the systemic survey of a chest film
because anything in between the diaphragm and the fundus of the stomach
may distort or displace the bubble (tumor)
If a chest film made at expiration is not recognized as an expiration film, an
erroneous diagnosis of cardiomegaly could be made in a patient with a normal-sized
heart
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The 2 hemi-diaphragms seen in a PA adult chest film are normally smooth curves
taking off from the midline at the origin of the tenth or eleventh rib
Pleural Effusion
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Pleura is a closed empty space, one side is visceral (covers the surface of the lung,
dipping into its fissures) and the other side is parietal (covers the inner surface of the
thoracic cavity).
 Can only be seen on an x-ray if it is thickened by inflammation
 Thicknesses of the pleura in the minor fissure can be seen as a thin white
line extending straight laterally from the right hilum (the minor fissure is
normally horizontal)
 Major fissures are too oblique to see on the PA, seen better on CT
Pleural Space
- Normally empty and collapsed
- May come to contain either fluid or air or both – will alter the appearance of the
chest film
- Massive collection of fluid on one side can displace the mediastinum toward the
opposite side, depress the diaphragm, collapse the lung, and render the hemithorax
dense and white
- The costophrenic sulcus (or sinus) is a continuous ditch formed between the chest
wall and the diaphragm.
- Lowest part of the sulcus is posterior on either side of the spine
 Therefore, the first 100 mL of fluid will accumulate in the posterior
portion of the diaphragm and will not be visible in the lateral costophrenic
sulcus, but will be visible in a lateral chest film obscuring the posterior
portion of the diaphragm.
Fluid in lateral costophrenic sulcus = blunting or obliteration of costophrenic sulcus
Obscured diaphragm:
 Fluid – upward curve of density against lateral chest wall or fluid level
 Process obscuring diaphragmatic border – lower lobe pneuomonia or
atelectasis
Pneuomothorax
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More obvious when lung is less aerated – full expiration shows small
pneumothorax
Lateral decubitus chest film visualizes a small pneumothorax – patient lies on the
good side and the air in the pleural space will collect between the lung and the
chest wall.
 Also good to visualize a subpulmonic fluid collection – patient lays on
the affected side and fluid collects in the lateral chest wall of affected
side
Tension Pneumothorax
- Pneumothorax associated with a ball-valve mechanism that permits increasing
volumes of air to become trapped within the pleural space
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There is mediastinal shift and depression of diaphragm on ipsilateral
hemidiaphragm.
Pulmonic Embolic Disease
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MC finding – linear or patchy segment of atelectasis or elevated hemidiaphragm on
affected side
Westermark’s sign – localized areas of peripheral oligemia with or without distended
proximal pulmonary arteries
May result in pulmonary infarction – presents as air-spaced opacity or pleural
effusion on CXR
 Appears in lateral periphery and as rounded opacities (Hampton’s Hump)
near the costophrenic sulcus
DX: Radioisotope Ventilation/Perfusion Lung Scan or CT and sometimes
Arteriography
Radioisotope Ventilation/Perfusion Lung Scan
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IV injection of human albumin tagged with technetium 99m
Used in diagnosis of pulmonary embolism because emboli block pulmonary artery
branches. The lung tissue peripheral to that block is therefore not perfused with the
isotope, and a “defect” (nonblackened) is produced on the scan (perfusion scan)
Ventilation scan is carried out by in the inhalation of radioactive gas (xenon-133)
and ventilation of all parts of the lung can be imaged.
Matching scans – underperfusion and underventilation (not embolism)
Pulmonary arteriography
- More accurate for diagnosing pulmonary embolism – more invasive and expensive
Pulmonary Embolism CT
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Most accurate in detecting emboli in the larger central and mid-level pulmonary
arteries – tiny emboli are overlooked in CT
Procedure of choice in patients with suspected pulmonary embolism whose chest film
is abnormal because of emphysema, CHF, or other pulmonary conditions
Chapter 8: Lung Overexpansion, Lung Collapse, and Mediastinal Shift
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When lung tissue is inflated with more than its normal content of airmore
radiolucent.
An x-ray of overexpanded lung will show increased radiolucencyaffected lung
would appear too dark. Blood vessels will be spread apart as separated farther by
ballooned alveoli.
-Obstructive emphysemalocalized to one segment of lung, however may
be so exaggerated could be confused with pneumothorax.
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Atelectasiscauses lung to appear less radiolucent, will 1st be seen as difference
in density b/w 2 sides of film.
 Poor inspiratory effort increase haziness, deep breath expands lungs.
Emphysema
 Chronic emphysema lungs are both overexpanded, diaphragm low, flattened,
and serrated. With fluoroscopy, would see diaphragm that moves down only
slightly on inspiration and returns slowly on forced expiration.
-Those with emphysema can develop pulmonary fibrosis web of
filamentous strands of increased opacity seen.
 Emphysematous bullae huge air cysts bordered by dense thin walls that enclose
them. Rupture spontaneous pneumonthorax.
Normal Mediastinum Position
 On routine PA chest film, only lateral margins of mediastinum outlined by air in
lungs on either side can be identified.
 With changes in air content of either lung, or w/ unilateral accumulations of
pleural air or fluid, mediastinum will bow to one side like an elastic diaphragm.
 3 significant points in determining the position of mediastinum:
1. Air in trachea (visible a dark vertical shadow)
2. White knob you see to left of the spine at about 5th rib posteriorly,
knob is shadow of margin created by arch of aorta.
3. Shadow of the right heart border
(These tag points will appear displaced in patient with minor degree of scoliosis).
 If whole lung collapses on one side, all three tag points will show shift in position,
since whole mediastinum swings to one side.
Mediastinal Shift
 Mediastinum may be displaced permanently (surgical removal of whole lung),
temporarily (pleural effusion), or transiently (foreign body in major bronchus
interfering with inflation.
 Mediastinum may be pushed to one side by pressure from an overexpanded lung.
Ex-Obstructive emphysema, when air is drawn into that part of the lung with
every breath but incompletely expelled.
o Remember-mediastinum is like a flexible disc held in the midline only
when the volumes of the two hemithoraces are equal therefore the
mediastinum must shift when there is a significant change in volume on
one side.
 Massive pleural effusion shifts mediastinum to the opposite side.
 Tension pneumothorax-mediastinum shifts away from affected side.
Collapsed lobes
 A collapsing lobe tends to fold up fanwise against the mediastinum.
 Elevation of the diaphragm compressing the heart will exaggerate the lateral
projection of both heart borders. Accuracy-count ribs to ensure diaphragm has
been drawn down well.
 Right upper lobe collapse hilum, trachea, aortic arch pulled up to the right;
lower and middle lobes expand to compensate for collapsed right upper lobe.
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

Left lower lobe collapse less heart shadow to right of spine, decrease in lucency
of the lower left lung with preservation of the left hemidiaphragm, which
becomes slightly elevated medially.
Massive left lower lob collapselittle or no heart shadow is seen to the right of
the spine, medial half of the border of the left diaphragm is missing. Left lower
lobe is now a wedge of opacity seen through the heart and against the spine, the
hilum is depressed.
Chapter 9: The Mediastinum
The mediastinum is considered as a disc of structures compressed between two inflated
lungs in the PA chest film.
 Mediastinum best seen on lateral film
 The heart is the largest of the mediastinal structures, and all of the profiles that
bulge beyond the shadow of the spine on both sides in the PA chest film represent
parts of the heart or of its great vessels.
 The more anteriorly the heart is positioned, the more the vessels are magnified in
comparison to the mediastinal outlines of the PA chest film.
 Where a chamber is thickest, its shadow will be more dense in the angiogram, and
where it tapers off and becomes very thin, a much less dense shadow is produced.

The plain film of the chest xray made PA, shows you a number of mediastinal
bulges seen in profile against the radiolucent lung on either side of the spine, all
of them vascular shadows.
o In addition you can usually see air in the trachea, but all the other
mediastinal structures merge with one another and their shadows are
superimposed upon those of the spine, the heart, and the sternum
o Even the great vessels are merged with other shadows
In Figures 9.5 & 9.6 you have conventional tomograms to study.
 These eliminate the superimposed images of the structures in fornt of or in back
of the coronal plane of study, and afford you a more precise view of the
thracheobronchial anatomy.
The trachea is normally located slightly to the right of the midline because it is closely
applied against the mass of the arch of the aorta; in older patients in whom the mass of
the aortic arch becomes larger (ectatic) as result of aging, the trachea may often be seen a
little farther to the right without indicating a mediastinal shift.
- In questions of tracheal compression or invasion, conventional tomography is
useful.
The esophagus, which lies just behind the trachea, is often deflected with the trachea by
masses like the aortic aneurysm in figure 9.7
The thymus is normally large in infancy and gradually regresses as it is replaced with fat
in adults.
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CT SCANS
“CT scans are conventionally displayed so that you are looking up from the
patient’s feet with the vertebrate down.”
Mediastinal Compartments and masses arising within them
Mediastinal masses generally arise from structures posterior to the heart: the esophagus
(carcinoma as well as dilation of the esophagus itself in the achalasia and scleroderma),
the thracheobronchial tree (bronchogenic carcinoma and cysts) & lymph nodes located
there.
 Posterior mediastinal masses - neural in origin, ganglioneuromas,
neurofibromas, aortic aneurysms
 Near the diaphragm – is where you will also see masses related to the herniation
of the abdominal structures through the diaphragm.
 Ant. mediastin - masses seen in lat Cx film : goiter, thymoma, teratoma,
lymphoma
 Middle mediastinal - posterior to the heart structures: esoph, tracheo-bronchial
tree, LNs
 Superior- goiters, in which thyroid mass extends down into the mediastinum
 Paratracheal space - paratracheal stripe; slightly to right of midline location of
trachea. If widened – something’s there; could mean inflamm, mediastinal
hemorrhage (iatrogenic), lymphoma, abscess in retropharyngeal space (infxtn
travel down neck  medistinitis)
 Pericardial cysts occur most often in the right Paracardiac angle
By no means, all obvious thickenings or widenings of the upper mediastinum is caused
by tumor mass of one kind or another.
Anterior Mediastinal Masses
- Masses in the mediastinum anterior to the heart are generally one of four kinds:
a. ectopic thyroids (goiters extending substernally)
b. teratomas (benign or malignant),
c. thymomas – often asymptomatic occur in conjunction with S&S of
myasthenia gravis.
d. lymphomas
-
You know when it is not an anterior mediastinal mass when it does not obliterate
the heart border.
Benign posterior mediastinal masses are more common than malignant ones.
Chapter 10: The Heart
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
Generally, the plain film diagnosis of heart dz is limited to the determination of
cardiac enlargement, pulmonary vascular abnormalities, cardiac calcifications,
and CHF.
Measurement of Heart Size
 For a heart normal in size, the cardiac width should measure less than half the
thoracic width. See Figure 10-1. This is called the cardiothoracic ratio, and is
calculated from the PA chest film ONLY.
 Cardiac enlargement may be (1) simulated (poor film), or (2) masked (as in a
large left pleural effusion).
 In a normal left lateral film, the convex posterior heart border does NOT extend
beyond the posterior margin of the IVC. Compare Figures 10-3 and 10-4.
 Rib notching: Saucered erosions of the undersurface of ribs, where dilated
intercostal arteries had developed as collateral pathways.
Factors Limiting Measurement of Heart Size
 Hearts may be apparently enlarged for many reasons.
 Chest films at EXPIRATION may show an apparently enlarged heart b/c of the
raised diaphragm.
 Rotation of a patient may produce an appearance of a widened heart. Check
symmetry of clavicles to ensure there is no rotation present.
 Deformity of the thoracic cage will often render impossible the measurement of
heart size, such as in severe scoliosis. A depressed sternum usually displaces the
heart to the left.
 An infant’s heart looks enlarged because we can’t ask him to take a deep breath
in, they have not developed proper lung:heart size proportions yet, and they are
hard to immobilize.
 Overdistention of lungs for any reason compresses the heart and mediastinal
structures from both sides and narrows their PA shadow.
 Noncardiac dz may mask true cardiac enlargement. Size or shapr of heart can’t be
studied in pts with pleural effusion, consolidation, or a mediastinal mass. A
mediastinal shift may alter the position of the heart.
 *** Look at slides on pages 184-185.***
Interpretation of the Medically Enlarged Heart Shadow
 Enlarged left ventricle: extension to Lf. on PA view & posteriorly in lateral view.
 Enlarged right ventricle: no posterior extension but will show anterior fullness.
 Effusions are documented by echocardiography. Sudden shapeless or glomerular
increase in size should suggest pericardial effusion.
The Heart in Failure
 Look for pulmonary venous engorgement (in failing heart). Normally, they
would be indistinguishable.
 Kerley’s B lines: short horizontal, white linear densities very close to chest wall.
Variations in Pulmonary Blood Flow (Figure 10-24)
1. Normal Pulmonary Vasculature – blood flow in an upright pt is much greater at
the bases than at the apex
2. Pulmonary Venous HTN – increased prominence & thickening of the upper lobe
blood vessels & decreased prominence over lower lobe vessels.
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3. Increased Pulmonary Vasculature – increase in the prominence of both upper and
lower lobe blood vessels.
4. Pulmonary Arterial HTN – decreased vasculature & enormously dilated hilar
trunks.
Cardiac Calcification
 Various parts of the heart may calcify. A “shell” around the heart can be seen in
pericarditis.
Coronary Arteriography

Commonly performed in pts. w/ symptoms of ischemic heart disease and may be
used:
o To confirm an anatomic cause for angina, to assess asymptomatic pts. w/
abnormal exercise tolerance tests,
o to evaluate pts before cardiac surgery, and after coronary bypass graft
surgery,
o To determine if a patient is w/ MI is a candidate for interventional
therapy: such as balloon angioplasty and intravascular stent placement for
Tx of coronary artery stenosis.

Arteriography involves selective catheterization of both coronary arteries under
fluoroscopic control w/ flexible angiographic catheter.

A 75 percent reduction in cross sectional area is req. to cause a significant
reduction of blood flow.

Collateral blood flow usually develops when stenosis is greater than 85 percent.
Classic Changes in Shape w/ chamber enlargement

During left ventricular enlargement, you will have a shadow of the left ventricle
that will project farther to the left on the PA view and extend farther posteriorly in
the lateral view. (Figure 10.38B) pg200

You will also appreciate that the posterior surface of the heart is often seen to
overlap the spine to some extent.

Left ventricular enlargement is often assoc. w/ aortic stenosis, and chronic
hypertension, both which may cause enlargement of the tortuosity of the aorta.

Left atrium enlargement, in a patient with mitral valve stenosis, will produce
fullness across the heart at about the level of the waistline producing the shape in
Figure 10.38C(pg200)

In the left oblique view the normally open aortic window b/wn the ascending and
descending aorta will be filled in by enlarging atrium.
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
In the right anterior oblique view, the displacement of the esophagus posteriorly
will be evident too. (Figure 10.40) pg201

In PA view, it first fills in the cardiac waistline so that the left heart border
becomes convex instead of concave, and then the atrium extends to the right so
that its margin is visible along the right heart border, called the “double shadow”
which is a classic sing of left atrial enlargement.

In addition to the enlargement of the left atrium there is also an extension of the
left ventricle to the left, showing left ventricular enlargement in mitral disease of
long standing. (Figure 10.41)

This may result from work overload on the left ventricle, which has to overcome
the inefficient backward flow of some blood into the left atrium through the
poorly closing mitral valve.

Also can be seen in pts. w/ both aortic and mitral valvular disease.
Problems

The right atrium is immensely dilated in Ebstein’s malformation

The right ventricle enlarges w/ increased pulmonary vascular resistance, which
occurs in cor pulmonale, and in pulmonic valve stenosis.

When it does enlarge, the PA film may show the heart to be deceptively normal or
show the normal left ventricle displaced to the left (Figure 10.18 pg 188)

In the lateral view, you will see the filling in of the lower part of the anterior clear
space and by the flat posterior surface of the heart, unlike the rounded posterior
projection of left ventricular enlargement

Pt. in figure 10.43 pg 202 is marked by an increase in the subcarinal angle w/
elevation of the left main bronchus; the pt. has a markedly dilated left atrium.
Classic example of mitral heart.
Nuclear Cardiac Imaging

Myocardial perfusion imagingo uses radioisotopes to identify regions of myocardium that develop
ischemia during exercise.
o Most common and very valuable for the early detection of ischemic heart
disease.
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o Radioactive thallium is used to evaluate coronary artery perfusion. Normal
heart will show uniform distribution whereas ischemic will show
decreased thallium uptake, “cold spots”.

Electrocardiogram-gated myocardial blood pool scanning (aka MUGA or gated
radionuclide ventriculography)o used to evaluate ventricular function, volume, and wall motion.
o Radioactive agents such as technetium-labeled red blood cells or human
serum albumin, are injected into the patient, and the heart is imaged under
a gamma camera that is coupled w/ a computer.
o The image can be manipulated and analyzed to determine features of
ventricular function such as stroke volume and ejection fraction.

Thallium stress imaging has proven to be a highly sensitive and specific test for
detection of coronary artery disease, in fact more sensitive than exercise
electrocardiography.

Should be reserved for those pts whom the EKG is nondiagnostic

The technique currently used to image cardiac perfusion is SPECT(single photon
emission computed tomography)
MR Images of the Heart

MR images are acquired as tomographic slices through ay selected imaging plane;
consequently MR images unlike CT can, yield primary coronal, sagittal, or
oblique slices of the heart, as well as conventional axial slices

Electrocardiographic gating may be used during MR scanning to obtain slice
specific images that match various phases of the cardiac cycle.

You may not only observe chamber wall thickness but wall motion as well.

Ejection fractions may also be determined
Cardiac CT

Noncontrast CT can be used to screen pts with unexplained chest pain for the
presence of coronary artery disease. (The absence of coronary artery calcification
at CT essentially R/O coronary artery disease).

When it is present however, software programs using CT data can precisely
indicate the amount of coronary artery calcification as a calcification “score”.
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