course objectives (complete, l1-7)

8/11/2019 Course Objectives (Complete, L1-7)

1/56

Week 1 - History of Radiology:(1) Know when and who invented radiologyWilhelm Conrad Roentgen is recognized as the Father of Radiology/Roentgenology. In 1895,

Roentgen began experiments using electric current flow in a partially-evacuated glass tube,

known as a cathode-ray tube. He noticed that, whenever the tube was in operation, a piece of

barium platinocyanide in line with it gave off light.Roentgen theorized that the interaction of electrons striking the tube's glass wall formed an

unknown radiation that caused the fluorescence. He called the mysterious phenomenon X-

radiation, or X-rays. Today, the cathode-ray tube is composed of tungsten, except inmammography, where it is composed of molybdenum.

(2) Understand the concept of projection and how it affects image quality

The quality of a medical image is determined by the imaging method, the characteristics of theequipment and the imaging variables selected by the operator. Image quality is not a single factor

but is a composite of at least 5 factors: contrast, blur, noise, artifacts and distortion.

(3) Understand the concept of how an image is formed

In projection imaging (radiography and fluoroscopy), images are formed by projecting an x-ray

beam through the patient's body and casting shadows onto an appropriate receptor that convertsthe invisible x-ray image into a visible light image. The gamma camera records a projection

image that represents the distribution of radioactive material in the body. The primary advantageof this type of image is that a large volume of the patient's body can be viewed with one image.

A disadvantage is that structures and objects are often superimposed so that the image of one

might interfere with the visibility of another. Projection imaging produces spatial distortion thatis generally not a major problem in most clinical applications.

Tomographic imaging, i.e., conventional tomography, computed tomography (CT), sonography,

single photon emission tomography (SPECT), positron emission tomography (PET), and MRI,

produces images of selected planes or slices of tissue in the patient's body. The generaladvantage of a tomographic image is the increased visibility of objects within the imaged plane.

One factor that contributes to this is the absence of overlying objects. The major disadvantage isthat only a small slice of a patient's body can be visualized with one image. Therefore, mosttomographic procedures usually require many images to survey an entire organ system or body

cavity.

(4) Understand the amount of radiation exposure with different radiologic modalities

X-ray:most common imaging technique used today; the most common x-ray ordered is a chest

x-ray, and the musculoskeletal x-ray exam comes in second. An x-ray provides a 2-D image of

the 3-D interior of the body. A single x-ray passes through the body and exposes the film on aradiograph (or fluorescent screen) placed on the opposite side.

CT:x-rays move as laser-like beam in an arch around the part of the body being observed. The

beam of x-rays passed through the region of the body imaged are collected by a detector that

converts the x-rays into electronic pulses, which produce readings of the tissue density into a1cm slice of the body. From these readings, a computer can assemble a picture of the body,

called a CT scan, which can be viewed on a fluorescent screen, then photographed for later

examination. It obtains parts of the body that can't be seen on a standard x-ray with the help ofcomputer algorithms in conjunction with the enhanced x-ray technology.

MRI:uses the magnetic properties of the hydrogen nucleus, which is excited by radiofrequency

radiation transmitted by a coil, which surrounds by the body part being imaged. When placed instrong magnetic fields, the nuclei of certain atoms absorb radiofrequencies beamed at them, and


2/56

then emit their own radio frequency waves. This process allows readers to see very clear pictures

of the inside of the body, including tissues, organs and blood vessels. MRI is a noninvasive

technique that does not use ionizing radiation. MRI has become one of the primary tools used toimage the brain, spinal cord, MSK (musculoskeletal) system, major blood vessels and several

key organs and extremities. The images can be produced in 3-D, which significantly enhances

the physician's ability to diagnose problems. MRI is also used to help view the process of surgeryin real time in 3-D, which assists with a whole host of surgical procedures.

Differences between CT scans and X-Ray's: CT scans are an advanced form of x-ray

technology used in detecting diseases in soft body tissues, and can actually provide images of

internal organs that are impossible to detect with standard x-ray techniques. X-rays are good atfinding bone fractures, and for being used as a contrasting agent for several types of exams;

however, CT provides greater detail and clarity. CT scans have additional advantages of being

able to produce imaging in virtually any orientation. It is a more technologically developedversion of an x-ray, which is used on specific parts of the body. It also provides better images for

bone structures, such as the inner ear as it can easily detect tumors in the auditory canal and

cochlea. CT scans help diagnose bone fractures, bone tumors, internal injuries and bleeding and

blood clots, and to monitor heart diseases and cancer.Differences between CT scans & MRI's: MRI uses magnetic waves to produce images while

CT images are produced using x-rays. MRI provides moredetails of bony structures compared to

CT scans. CT scans cannot help much in seeing clearly, very fine, softtissue details as in theshoulder or knee compared to MRI. MRI scans are best for imaging soft tissue. CTscans are

much more costly and takes a longer time (30 minutes) to be completed compared to a MRI that

takes about 5 minutes to complete. People with surgical clips, metallic fragments, cardiacmonitors and pacemakers cannot have CT scans. Also, pregnant women should not have CT

scans, and they should be used with caution in children and young adults. MRI machines can

produce imagesin any plane without moving the patient. They also have the ability to change thecontrast of images,making them clearer than CT scans.

Table: American College of Radiology appropriateness criteria, relative radiation level

information

Relative radiation

level

Effective dose estimate

range

Example examinations

None 0 Ultrasound, MRI

Minimal 10 mSv Abdomen CT without and with contrast, whole

body PET

Week 2 - Musculoskeletal:(1) Understand fracture terminology

Displaced: loss of contact between fracture fragments


3/56

Dislocated: loss of contact between joint surfaces

Comminuted: bone fractures into 2+ fragments

Impacted: bone fragments are driven into each otherAngulation: bone fragments are at angles to one another

Intra-articular: break crosses into joint surface; always result in some degree of cartilage damage.

Pathologic: abnormal bone; fracture through bone made weak by disease, such as a tumor.Insufficiency: weak bone; fracture through weak bone, such as due to osteoporosis.

Occult: does not appear in x-rays, but bone shows new formation within 3-4 weeks of fracture.

Open vs. closed:

Closed/simple fracture: skin is still intact.Open/compound fracture: involves wounds that communicate with the fracture.

Stress fracture: fracture through bone due to abnormal force; NOT an insufficiency fracture.

Greenstick / torus / buckle: typically occurs in a young, soft bone in which the bone bendsand partially breaks. It is due to mechanical failure on the tension side; that is, since the bone is

not as brittle as it would be in an adult, it does not completely fracture, but rather exhibits

bowing without complete disruption of the bone's cortex in the surface opposite the applied

force.What do fractures look like?

- Loss of cortical integrtity

- Deformity- Periosteal reaction (subactue): formation of new bone in response to injury or other stimuli of

the periosteum surrounding the bone

- Effusion- Soft tissue swelling

- Bony lucency

- Invisible

(2) Be familiar with the cervical spine bone anatomy

Lateral view


4/56

P-A view


5/56

Contour lines/margins:

(3) Be able to identify the following plain films:- Salter-Harris fracture: involves epiphyseal/growth plate of a bone; common injury in children.

Salter-Harris fracture

Normal epiphysis/growth plate

- Distal radius fracture


6/56

Colle's fracture: fracture of the distal radius with dorsal/posterior displacement of the

wrist and hand; it is aka "dinner fork" deformity. It is a dorsally-angulated fracture

because the fracture faces the dosrsal/posterior surface.

Smith's fracture (opposite of Colle's): fx of distal radius w/ volar/anterior/palmar

displacement of the wrist and hand.

Smiths fracture vs. Colles fracture:


7/56

Barton's fracture: comminuted (2+ fragments), intra-articular fracture of the distal radiuswith dislocation of the radiocarpal joint; palmar/volar is more common than

dorsal/posterior.


8/56

Boxers: transverse fracture through the neck of a metacarpal bone; more likely to occur from a

straight punch, hence the name. In this image, distal 5th

metacarpal fracture.

- Simple vs. comminuted fracture: see above (Colles vs. Bartons)

- Dislocation vs. displacement

- Dislocation fracture (aka luxation): occurs when bones in a joint become displaced ormisaligned. It is often caused by a sudden impact to the joint. The ligaments always

become damaged as a result of a dislocation. A subluxation is a partial dislocation.

- Displaced fracture: fracture in which the 2 ends of the bone are separated from oneanother, no longer in anatomical alignment.


9/56


10/56

- Cervical spine fracturesCT: better for bone detail

MRI: better for soft tissue and joint detail

1. AA (atlanto-axial) dislocation

Hyperextension injuryChildren>adults

Head slips forward on C1

Usually fatal

2. Jefferson fracture of C1:


11/56

Fracture of the anterior and posterior arches of C1 (atlas vertebra), often appearing as

a 2-part or 3-part fracture.

Burst fracture; caused by compressive forceBilateral breaks in anterior and posterior arches

Open mouth view shows bilateral offset of C1 on C2

Not associated with neurologic deficit

3. Hangmans fracture (traumatic spondylolisthesis) of C2:

Fracture of either both pedicles or pars interarticularis of C2 (axis vertebra).Most common fracture of C2

Most common cervical spine fracture

Hyperextension/compression fractureFractures through pedicles of C2, with anterior slip of C2 on C3

Teardrop fracture of inferior aspect of C2 or C3 is clue to dx of Hangmans fracture

Not associated with neurologic deficit


12/56

4. Odontoid (Dens) fracture:Fracture through the odontoid process (dens).

Hyperextension injury; generally associated with anterior of C1 subluxation on C2.

3 types:

Type I (tip of dens): extends through the tip of the dens; usually stable.Type II (base of dens): extends through the base of the dens; most commonly

encountered fracture for this region of the axis, never stable.

Type III (sub-dentate / below dens): extends through vertebral body of the axis; can

be stable or unstable.

5. Flexion-teardrop fracture


13/56

Fracture of the antero-inferior aspect of a cervical vertebral body due to flexion of the

spine, along with vertical axial compression. It is usually associated with spinal cord

injury, often a result of displacement of the posterior portion of the vertebral bodyinto the central spinal canal.

Combination of flexion and compression, e.g. MVA (motor vehicle accident)

Teardrop fragment comes from antero-inferior aspect of vertebral bodyRemainder of body displaced backward into spinal canal

Facet joint and interspinous distances usually widened

Disk space may be narrowed

70% have associated neurologic deficit

- Pathologic fracture: fracture through bone, made weak by disease, such as by a tumor


14/56

- Radial head (proximal radius) fracture: sails sign present = anterior and posterior fat pad

displacement/elevation/swelling surrounding the elbow joint

Week 3 - Abdomen Plain Films and Ultrasound(1) Understand the diagnostic role of plain abdominal film

a. Abdominal X-ray has as much radiation as 30 chest xrays.

b. Good Reasons to order

i. Cheap, Fast, available, can be highly specificc. Bad reasons to order

i. Cheap (get what you pay for), available (order because they can), can be

limited.

d. What it showsi. Free fluid

ii.

Air outside the bowel lumen1. Intraperitoneal, retroperitoneal, abscess, pneumatosis2. Cant see pneumoperitoneum in supine position (erect or lateral

decubitus is used)

iii. Air inside the bowel lumen1. Ileus, Bowel obstruction, Volvulus

2. Small bowel vs colon air

a. Small bowel: Centrally located, valvulae conniventes

b. Colon: Peripherally located, haustral markings.3. Too Much Gass Intestinal Dilation (3 cm in small bowel, 6-8 in

colon)

a.

Think Obstruction or Ileusi. Ileus think absent bowel sounds and think post-op

or possible meds that suppress bowel activity)

b. Next test for obstructionCT4. Air fluid levels Look for associated signs of obstruction.

iv. Bowel wall thickening

v. Densities

1. Bones, appendicolith, stones, pancreatic calcification, AAA


15/56

vi. Organs.

Plain abdominal film:

- Normal plain abdominal film does not exclude ileus or other pathology, and may falselyreassure the clinician

- Plain abdominal film has a limited value in the evaluation of abdominal pain

-

Plain abdominal films are useful for detection of:o Kidney stones

o Pneumoperitoneum

- All other indications: use CT or sonography/US (ultrasound)

(2) Understand the best test to order for gallbladder disease, appendicitis, kidney stones,

testicular pain, and ovarian/gyn issues

a. Gallbladder diseasevii. Ultrasound (Single best for cholecystitis)

1. Ultrasound is only 85% sensitive in detection of bile duct stones

(Still test of choice)

b.

Pancreasviii.

CT

c. Appendicitis

ix. Ultrasound: for Peds, poor in adults.x. MRI for Pregnant

xi. CT: Single Best test.

d. Kidney Stones

xii. Non-Con CT is more Sensitive

xiii. Ultrasound for Kidney masses (Cystic vs solid)

e. Testicular painxiv. Ultrasound (small parts imaging: testes, breast, thyroid)

f. OBGYN Issues

xv.

Ultrasound

Gallbladder disease: ultrasound. Cholecystitis occurs when a calculus obstructs the cystic duct.

The trapped bile causes inflammation of the gallbladder wall. As gallstones are often occult on

CT, US is the preferred imaging method for the evaluation of cholecystitis, also allowingassessment of the compressibility of the gallbladder.

Appendicitis: CT. According to a systematic review from UCSF comparing US vs. CT scans, CT

is more accurate than US for the diagnosis of appendicitis in adults and adolescents. CT has asensitivity of 94% and specificity of 95. US had an overall sensitivity of 86% and a specificity of

81%.

Kidney stones: CT without contrast. Ca2+

-containing stones are relatively radiodense, and theycan often be detected by a traditional x-ray of the abdomen that includes the kidneys, ureters, and

bladder (KUB film). Where available, a non-contrast, helical CT scan is the diagnostic modality

of choice in the radiographic evaluation of suspected nephrolithiasis. All stones are detectable on

CT scans, except very rare stones composed of certain drug residues in the urine.Testicular pain: ultrasound. Doppler ultrasonography in patients with testicular pain helps

distinguish torsion from other causes by assessing testicular blood flow. Radionuclide scanning

can also be used to image blood flow to the testes.


16/56

Ovary / gynecological issues: US can be used to determine the right treatment for an ovarian or

gynecologic issue by examining blood flow to the ovaries. Potential complications of

hysterectomy and other gynecologic and obstetric procedures are numerous. These complicationsinclude ureteral obstruction or transection, bladder perforation, bowel perforation or obstruction,

fistula, bleeding, abscess, retention of surgical instruments or sponges, incisional hernia, and

tumor or endometriosis implants in surgical scars. The available imaging techniques are almostas varied as the problems they investigate. CT, intravenous urography (IVU), ultrasonography,

MRI, gastrointestinal fluoroscopic studies, angiography and even scintigraphy can be used to

diagnose complications. Furthermore, each technique can be optimized to answer a particular

question. If the surgeon is looking for a specific complication, the technique should be adjustedto answer that question. Typically, if cancer is being diagnostically investigated, then X-ray and

CT are not used due to radiation exposure.

SBO (small bowel obstruction) and/or perforated bowel: CT. CT is superior to conventionalradiography and barium studies in diagnosing SBO.

Pneumothorax: chest x-ray, P-A and lateral views. Traditionally a plain P-A chest x-rayhas been

the most appropriate first investigation. These are usually performed during maximal inspiration

(holding one's breath); no added information is gathered by obtaining a chest X-ray in expiration(after exhaling). If the PA X-ray does not show a pneumothorax but there is a strong suspicion,

lateral X-rays may be performed, but this is not routine practice. CT can be useful in particular

situations, such as lung diseases like emphysema, and/or the identification of underlying lunglesions. Ultrasound may be more sensitive than chest X-rays in the identification of

pneumothorax after blunt trauma to the chest.

CT: generally not used or used with caution for pregnant women, children and young adultsbecause of radiation exposure

(3) Be able to identify the following on a plain x-ray of the abdomen:

OBGYN Issues

Ultrasound

e.

Small bowel obstructioni. Dilation over 3cm. Look for valvulae conniventes

(thin circular folds of mucosa that span the entire

width)

ii. Causes: Adhesions, Ileus

f. Large bowel obstructioni.

Over 6-8 cm in diameter. Look for haustra.

ii. Peripherally located.

iii. Common cause: Colorectal carcinoma and

diverticular strictures, Hernias, Volvulus.


17/56

g. Constipation

i. Stool is Opaque white surrounded by black bowel gas

h. Free intraperitoneal air

i. Emergency (Bowel Perforation)ii. Erect Position: Look for a crescent beneath the

diaphragm.

iii. (Below is same pt with free air highlighted in red)

i. Large kidney stones


18/56

- Small Bowel Obstruction

Key features of mechanical SBO:

- Dilated small bowel- Fighting loops

-

Little gas in colon, especially rectum- Disproportionate dilatation of SB

- Large Bowel Obstruction


19/56

Key features of mechanical LBO:Dilated colon until point of obstruction

Little or no air in sigmoid/rectumLittle or no gas in small bowel, if ileocecal valve remains competent

- Constipation


20/56

- Pneumoperitoneum (free intraperitoneal air)

Signs: air beneath diaphragm, both sides of bowel wall, falciform ligament sign


21/56

White arrow: evidence of free air betweenthe abdominal wall and the liver. Black

arrow: evidence of free fluid in the

peritoneum.- Large Kidney Stones

Summary info from lecture (last 3 pages of text):

Hounsfield units (HU) relate the attenuation coefficients of tissue to that of water (HU = 0)

Tissues with lower attenuation (fats) are negative (fats), those with higher attenuation

(bone/calcium) are positive Windows adjust the gray scale to make visible different portions of the image

Metals can cause artifacts

Use water soluble oral contrast (if at all) when perforation is suspected. Other commonly usedcontrast is barium.

IV contrast is I-(iodine) based; helps distinguish cystic from solid, as it helps to visualize

vasculature and viscera.


22/56

Contraindications of IV contrast include allergy (pre-treat with steroids) and renal insufficiency

(creatinine > 2.0)

Sometimes IV contrast is not needed, e.g. renal stones or head trauma CT should be used judiciously, especially in the young/children and pregnant women

CT plays a large role in the imaging of cancer, trauma, vascular pathology and abdominal

symptoms Intra-abdominal fluid is a marker of pathology

Other important stuff:

Abdominal CT images, 2 axial:

Anterior

Posterior

Anterior


23/56

Posterior

What to look for:


24/56

Obstruction series Normal gas pattern Abnormal gas pattern Aunt Minnies (image

appearance so classic that, once you see it, you easily ID it) Extraluminalair Soft tissue

masses CalcificationsNormal gas patterns:

- Stomach: gas ALWAYS present

- Small bowel: gas in 23 loops of non-distended bowel- Large bowel: gas almost always present in sigmoid or rectum

Normal fluid levels:

- - Stomach: fluid ALWAYS present, except in supine films

- Small bowel: few (23) levels of fluid possible- Large bowel: no fluid should be present

Small bowel vs. Large bowel

- Small bowel:-- Central

-- Valvulae extend across lumen

-- Maximal diameter of 2

- Large bowel:-- Peripheral

-- Haustral markings do not extend from wall-to-wall


25/56


26/56


27/56

(2) How does an x-ray create a visible image on a radiograph?

Beam from cathode tube fans out and increases in size the further away it is from the source

(cathode tube). Want the area being imaged closest to film (not x-ray source/tube) in order toproperly capture the area. The further away the film is to the area being imaged, the larger and

more fuzzy (i.e., less clear and focused) the organ/image will be.

X-ray radiation for medical imaging is typically produced by x-ray tubes, which operate throughbombarding the anode with high energy electrons emitted from a hot cathode. Image sharpness,

contrast, and patient dosage are important considerations in medical radiography and these

requirements determined the desired energies of the tube, the type of material used on the anode,

and the method in which the power is generated to drive the tube. The photons emitted come indiscrete bands of energy corresponding to the material of the anode, and the undesired bands are

removed. Choice of the anode and its emitted radiation energies depends on the application and

the tissues being imaged, for instance molybdenum is often used in mammography. Too highradiation energies will result in poor pictures since the radiation cannot be readily attenuated,

however too low energies will increase the radiation dosage of the patient without improvements

in image quality.

Sharpness of a radiographic image is strongly determined by the size of the x-ray source. This isdetermined by the area of the electron beam hitting the anode. A large photon source results in

more blurring in the final image and is worsened by an increase in image formation distance.

This blurring can be measured as a contribution to the modulation transfer function of theimaging system.

(3) Describe the term that indicates when different densities may appear the same on a

radiograph, as well as being familiar with the major sources of artifact on chest x-rays.

Silhouette sign:produced when two fluid densities are contiguous and the individual outlineof each is lost. Commonly used in the evaluation of chest problems.

Loss of different densities when a film is too dark is due to OVER exposure, while a film that is

too white would be considered UNDER exposed could also explain different densities appearingthe same.

The silhouette sign refers to loss of normal border between structures, or an intra-thoracic radio-

opacity obscuring the border of the heart or aorta due to a contiguous structure.In other words it

is difficult to make out the borders of a particular structure - normal or otherwise - because it is

next to another dense structure, both of which will come up as white on a standard X-ray. It may

occur, for example, in middle lobe disease, where the right heart margin is lost, and in rightlower lobe pneumonia, where the border of the diaphragm on the right side is obscured, while the

right heart margin remains distinct.

Most imaging methods can create image features that do not represent a body structure or object.These are image artifacts. In many situations an artifact does not significantly affect object

visibility and diagnostic accuracy. But artifacts can obscure a part of an image or may be

interpreted as an anatomical feature. A variety of factors associated with each imaging method

can cause image artifacts.

Example of artifact caused by patients hair:


28/56

(4) Understand the technical approach to reading a chest x-ray

Check the image for - Inclusion, Projection, Rotation, Inspiration, Penetration and Artifact

Inclusion: A chest X-ray should include the entire thoracic cage. Look for First ribs,

costophrenic angles and the lateral edges of ribs.

Projection: PA projection is typical. X-rays pass from the posterior to the anterior of thepatient - hence Posterior-Anterior (PA) projection. The image is viewed as if looking at

the patient face-to-face.

Rotation: The spinous processes of the thoracic vertebrae are in the midline at the backof the chest. They should form a vertical line that lies equidistant from the medial ends of

the clavicles, which are at the front of the chest. Rotation of the patient will lead to off-

setting of the spinous processes so they lie nearer one clavicle than the other. Find the

medial ends of the clavicles, Find the vertebral spinous processes, The spinous processesshould lie half way between the medial ends of the clavicles Assessing inspiration

Inspiration: To assess the degree of inspiration it is conventional to count ribs down to

the diaphragm. The diaphragm should be intersected by the 5th to 7th anterior ribs in themid-clavicular line. Less is a sign of incomplete inspiration.

Penetration: A well penetrated chest X-ray is one where the vertebrae are just visible

behind the heart. Although X-rays are still occasionally over or under exposed, adiscussion of penetration now best serves as a reminder to check behind the heart. The

left hemidiaphragm should be visible to the edge of the spine. Loss of the hemidiaphragm

contour or of the paravertebral tissue lines may be due to lung or mediastinal pathology.

Artifact: examples include rotation, incomplete inspiration and incorrect penetration.Other radiographic artifact includes clothing or jewelry not removed. Other common

artifact to find is medical or surgical equiptment like NG tubes.

Mnemonic for reading a [normal] chest x-ray: ABCDEFGHI

A = Airway

B = BoneC = Cardiac silhouette


29/56

D = Diaphragm

E = Edge of the heart

F = Field of lungG = Gastric bubble

H = Hilum of lung

I = Impression (diagnosis)14 steps (total):

1. Check the patient's name. Above all else, make sure you are looking at the correct chest

x-ray first.

2. Read the date of the chest radiograph. Make special note of the date when comparingolder radiographs (always look at older radiographs if available). The date the radiograph

is taken provides important context for interpreting any findings. For example, a mass

that has become bigger over 3 months is more significant than one that has becomebigger over 3 years.

3. Note the type of film (while this article assumes you are looking at a chest x-ray, practice

noting if it is a plain film, CT, angiogram, MRI, etc.) For chest x-ray, there are several

views as follows:o The standard view of the chest is the posteroanterior radiograph, or "PA chest."

Posteroanterior refers to the direction of the x-ray traversing the patient from

posterior to anterior. This film is taken with the patient upright, in full inspiration(breathed in all the way), and the x-ray beam radiating horizontally 6 feet away

from the film.

o The anteroposterior (AP) chest radiograph is obtained with the x-ray traversingthe patient from anterior to posterior, usually obtained with a portable x-ray

machine from very sick patients, those unable to stand, and infants. Because

portable x-ray units tend to be less powerful than regular units, AP radiographsare generally taken at shorter distance from the film compared to PA radiographs.

The farther away the x-ray source is from the film, the sharper and less magnified

the image. (You can confirm this by placing your hand about 3 inches from adesk, shining a lamp above it from various distances, and observing the shadow

cast. The shadow will appear sharper and less magnified if the lamp is farther

away.) Since AP radigraphs are taken from shorter distances, they appear more

magnified and less sharp compared to standard PA films.

o
http://www.wikihow.com/Image:Normal_L.JPG


30/56

Lateral chest x-ray.

The lateral chest radiograph is taken with the patient's left side of chest held

against the x-ray cassette (left instead of right to make the heart appear sharperand less magnified, since the heart is closer to the left side). It is taken with the

beam at 6 feet away, as in the PA view.

o

An oblique view is a rotated view in between the standard front view and thelateral view. It is useful in localizing lesions and eliminating superimposed

structures.

o

Right lateral decubitus chest x-ray showing pleural effusion. The A arrow

indicates "fluid layering" in the right chest. The B arrow indicates the width of the

right lung. The volume of useful lung is reduced because of the collection of fluidaround the lung.

A lateral decubitus view is one taken with the patient lying down on the side. It

helps to determine whether suspected fluid (pleural effusion) will layer out to the

bottom, or suspected air (pneumothorax) will rise to the top. For example, ifpleural fluid is suspected in the left lung, check a leftlateral decubitus view (to

allow the fluid to layer to the left side). If air is suspected in left lung, check arightlateral decubitus view (to allow the air to rise to the left side).

4. Look for markers: 'L' for Left, 'R' for Right, 'PA' for posteroanterior, 'AP' for

anteroposterior, etc. Note the position of the patient: supine (lying flat), upright, lateral,

decubitus.5. Note the technical quality of film.

o Exposure: Overexposed films look darker than normal, making fine details harder

to see; underexposed films look whiter than normal, and cause appearance of

areas of opacification. Look for intervertebral bodies in a properly penetratedchest x-ray. An under-penetrated chest x-ray cannot differentiate the vertebral

bodies from the intervertebral spaces, while an over-penetrated film shows the

intervertebral spaces very distinctly.

To assess exposure, look at the vertebral column behind the heart on the

frontal view. If detailed spine and pulmonary vessels are seen behind the

heart, the exposure is correct. If only the spine is visible, but not thepulmonary vessels, the film is too dark (overexposed). If the spine is not

visible, the film is too white (underexposed).

o Motion: Motion appears as blurred areas. It is hard to find a subtle pneumothoraxif there is significant motion.

o Rotation: Rotation means that the patient was not positioned flat on the x-ray film,

with one plane of the chest rotated compared to the plane of the film. It causes

distortion because it can make the lungs look asymmetrical and the cardiacsilhouette disoriented. Look for the right and left lung fields having nearly the
http://www.wikihow.com/Image:Pleural_effusion_920.jpg


31/56

same diameter, and the heads of the ribs (end of the calcified section of each rib)

at the same location to the chest wall, which indicate absence of significant

rotation. If there is significant rotation, the side that has been lifted appearsnarrower and denser (whiter) and the cardiac silhouette appears more in the

opposite lung field.

6.

Left tension pneumothorax. Note the large, well-demarcated area devoid of lungmarkings, and deviation of the trachea (airway) and the heart away from the affected side.

The bright metallic spots are snaps for EKG readings.Airway: Check to see if the airway is patent and midline. For example, in a tensionpneumothorax, the airway is deviated away from the affected side. Look for the carina,

where the trachea bifurcates (divides) into the right and left main stem bronchi.

7.

Fracture of the left clavicle.

Bones: Check the bones for any fractures, lesions, or defects. Note the overall size, shape,

and contour of each bone, density or mineralization (osteopenic bones look thin and lessopaque), cortical thickness in comparison to medullary cavity, trabecular pattern,

presence of any erosions, fractures, lytic or blastic areas. Look for lucent and sclerotic

lesions. A lucent bone lesion is an area of bone with a decreased density (appearing

darker); it may appear punched out compared to surrounding bone. A sclerotic bonelesion is an area of bone with an increased density (appearing whiter). At joints, look for

joint spaces narrowing, widening, calcification in the cartilages, air in the joint space,

abnormal fat pads, etc.8.
http://www.wikihow.com/Image:Clavicle_fracture_left.jpghttp://www.wikihow.com/Image:Pneumothorax_CXR.jpg


32/56

Enlarged cardiac silhouette in a case of aortic dissection (blood fills the mediastinum).Note that the cardiac silhouette takes up more than half of the chest width. Characteristic

of aortic dissection here is the enlarged mediastinum (labeled 1) and aortic arched

(labeled 2).Cardiac silhouette: Look at the size of the cardiac silhouette (white space representing the

heart, situated between the lungs). A normal cardiac silhouette occupies less than half the

chest width.

o Look for water-bottle-shaped heart on PA plain film, suggestive of pericardialeffusion. Get an ultrasound or chest Computed Tomagraphy (CT) to confirm.

9.

Left pleural effusion associated with left lower lobe pneumonia: note that the

costophrenic angle is blunted, and the left diaphragm is raised compared to the right.

Diaphragms: Look for a flat or raised diaphragm. A flattened diaphragm may indicateemphysema. A raised diaphragm may indicate area of airspace consolidation (as in

pneumonia) making the lower lung field indistinguishable in tissue density compared tothe abdomen. The right diaphragm is normally higher than the left, due to the presence of

the liver below the right diaphragm. Also look at the costophrenic angle (which should be

sharp) for any blunting, which may indicate effusion (as fluid settles down). It takesabout 300-500 ml of fluid to blunt the costophrenic angle.

10.
http://www.wikihow.com/Image:LLL_pneumonia_with_effusionM.jpghttp://www.wikihow.com/Image:AoDiss_ChestXRay.jpg


33/56

A) Normal chest radiograph; B) Q fever pneumonia affecting the lower and middle lobesof the right lung. Note the loss of the normal radiographic silhouette (contour) betweenthe affected lung and its right heart border as well as between the affected lung and its

right diaphragm border. This phenomenon is called the silhouette sign.

Edges of heart; External soft tissues: Check the edges of the heart for the silhouette sign:a radioopacity obscuring the heart's border, in right middle lobe and left lingula

pneumonia, for example. Also, look at the external soft tissues for any abnormalities.

Note the lymph nodes, look for subcutaneous emphysema (air density below the skin),and other lesions.

11.

Right lower lobe pneumonia. Note the prominent air-bronchogram sign: air visualized in

the peripheral intrapulmonary bronchi, due to an infiltrate or consolidation surroundingthe bronchi.

Fields of the lungs: Look for symmetry, vascularity, presence of any mass, nodules,

infiltration, fluid, bronchial cuffing, etc. If fluid, blood, mucous, or tumor, etc. fills the air

sacs, the lungs will appear radiodense (bright), with less visible interstitial markings.12.

Gastric bubble: Look for the presence of a gastric bubble, just below the heart; note

whether it is obscured or absent. Assess the amount of gas and location of the gastricbubble. Normal gas bubbles may also be seen in the hepatic and splenic flexures of the

colon.

13.
http://www.wikihow.com/Image:RLL_pneumoniaM.jpghttp://www.wikihow.com/Image:Pneumonia_x-ray.jpg


34/56


35/56

Air Bronchogram

If an area of lung is consolidated it

becomes dense and white. If the

larger airways are spared, they are of

relatively low density (blacker). This

phenomenon is known as airbronchogram and it is a

characteristic sign of consolidation.

Right Atrium, Right Ventricle,

Left Ventricle, Diaphragms, Ribs,Trachea,

Aortic Arch, Pulmonary Fissures,

Costophrenic Angle

Pneumothorax

- Free Intraperitoneal Air

- Pneumonia: The x-ray findings of pneumonia are airspace opacity, lobar consolidation, orinterstitial opacities. There is usually considerable overlap. Again, pneumonias is a space

occupying lesion without volume loss. What differentiates it from a mass? Masses are generally

more well-defined. Pneumonia may have an associated parapneumonic effusion.


36/56

- Congestive Heart Failure: The earliest CXR finding of CHF is cardiomegaly, detected as an

increased cardiothoracic ratio (>50%). In the pulmonary vasculature of the normal chest, thelower zone pulmonary veins are larger than the upper zone veins due to gravity. In a patient with

CHF, the pulmonary capillary wedge pressure rises to the 12-18 mmHg range and the upper zone

veins dilate and are equal in size or larger, termed cephalization. With increasing PCWP(pulmonary capillary wedge pressure, 18-24 mmHg.), interstitial edema occurs with the

appearance of Kerley lines. Increased PCWP above this level is alveolar edema, often in a classic

peri-hilar bat wing pattern of density. Pleural effusions also often occur.


37/56

- Cardiomegaly: refers to excessive heart size in proportion to the diameter of the rib cage. Heart

size is usually estimated based on the cardiothoracic ratio, which compares the maximum width

of the cardiac silhouette on a frontal CXR, with the maximum internal diameter of the rib cage.Cardiomegaly is usually present if the maximum width of the cardiac silhouette is >50% of the

maximum internal diameter of the rib cage.

- Air Bronchogram: sign in which branching radiolucent columns of air corresponding to bronchiis seen, usually indicates air-space (alveolar) disease, as from blood, pus, mucus, cells, protein

surrounding the air bronchograms; this is often seen in RDS (respiratory distress syndrome),specifically occurring due to infiltrates outlining larger air passageways. Air bronchograms occurwhen there is pulmonary infiltration or edema in the tissues immediately adjacent to the bronchi.

Darker tubular densities can be seen when the inflammatory process involves the alveoli but has

not filled the bronchi with fluid, and therefore distinguishes this disease from cases of atelectasisor pulmonary edema.


38/56

- Pneumothorax: The symptoms of pneumothorax can be vague and inconclusive, especially in

those with a small PSP, and confirmation with medical imaging is usually required. In contrast,tension pneumothorax is a medical emergency and may be treated before imaging - especially if

there is severe hypoxia, very low blood pressure, or an impaired level of consciousness. In

tension pneumothorax, X-rays are sometimes required if there is doubt about the anatomical

location of the pneumothorax.The lung is held close to chest wall because

of the negative pressure in the pleural space.

Once the negative pressure is lost the lungtends to recoil due to elastic properties and

becomes atelectatic. This occurs in patientswith pneumothorax and pleural effusion.

- Pneumoperitoneum (free intraperitoneal air)

Signs: air beneath diaphragm, both sides of bowel wall, falciform ligament sign


39/56

White arrow: evidence of free air between the abdominal wall and the liver. Black arrow:

evidence of free fluid in the peritoneum.

Chest x-ray anatomic structures to check

1. Trachea/bronchi

2. Hilar structures

3. Lung zones

4. Pleura

5. Lung lobes/fissures

6. Costophrenic angles

7. Diaphragm

8. Heart 9. Mediastinum

10.Soft tissues

11. Bones


40/56

Week 5 - Chest: Part Two:(1) Understand X-ray transmission and how that is related to CT scans

X-ray source and detectors rotate around patient


41/56

Amount of radiation transmitted though body at various angles is recorded

Creates density map of human tissue

Table carries patient past continuously rotating x ray tube = volumetric dataacquisition

CT scans are an advanced form of x-ray technology used in detecting diseases in soft bodytissues, and can actually provide images of internal organs that are impossible to detect with

standard x-ray techniques. X-rays are good at finding bone fractures, and for being used as a

contrasting agent for several types of exams; however, CT provides greater detail and clarity. CTscans have additional advantages of being able to produce imaging in virtually any orientation. It

is a more technologically developed version of an x-ray, which is used on specific parts of the

body. It also provides better images for bone structures, such as the inner ear as it can easily

detect tumors in the auditory canal and cochlea. CT scans help diagnose bone fractures, bonetumors, internal injuries and bleeding and blood clots, and to monitor heart diseases and cancer.

(2) Understand the resolution differences between chest x-ray and CT scans

An Xray produces a single image in which structures are overlaid on each other. In contract a CTproduces many slices of an image, essentially using many xrays at different angles to create

images of layers throughout the body.

There are several advantages that CT has over traditional 2D medical radiography (i.e. plain x-ray films). First, CT completely eliminates the superimposition of images of structures outside

the area of interest. Second, because of the inherent high-contrast resolution of CT, differences

between tissues that differ in physical density by less than 1% can be distinguished. Finally, data

from a single CT imaging procedure consisting of either multiple contiguous or one helical scancan be viewed as images in the axial, coronal, or sagittal planes, depending on the diagnostic

task. This is referred to as multi-planar reformatted imaging.CT scans use a high level of

ionizing radiation. Ionizing radiation has the capacity to break molecular bonds, and thus alterthe molecular structure of the irradiated molecules.

(3) Understand how IV contrast administration effects contrast

Intravenous contrast is used to highlight blood vessels and to enhance the structure of organs likethe brain, spine, liver, and kidney. Typically the contrast is contained in a special injector, which

injects the contrast through a small needle taped in place (usually on the back of the hand) during

a specific period in the CT exam. Once the contrast is injected into the bloodstream, it circulatesthroughout the body. The CT's x-ray beam is weakened as it passes through the blood vessels

and organs that have "taken up" the contrast. These structures are enhanced by this process and

show up as white areas on the CT images. When the test is finished, the kidneys and liver

quickly eliminate the contrast from the body.IV contrast is a substance that is opaque to x-rays. When administered, it brightens and allows

greater visualization of internal organs, arteries, veins and tissues as it courses through them. For


42/56

some exams it is essential and cannot be done properly without it, while with other exams it is

contraindicated, as it may cause anaphylaxis, nephropathy or negative / drug-drug interactions.

(4) When looking at CT scans, be able to identify normal landmarks:

- Heart (Here are 4 images: superior to inferior)

- Pulmonary Arteries


43/56


44/56

The coronal CT image on the left shows the right minor (horizontal) fissure (white arrow), right

major fissure (yellow arrow), and left major (oblique) fissure. These structures are also seen onthe right lateral sagittal CT image on the right. The minor fissure separates the right superior lobe

from the right middle lobe. The right major fissure separates the right upper and middle lobes

from the inferior lobe. The left major fissure (middle CT image) separates the left upper andlower lobes. These fissures are easy to see because this patient suffers significant pleural

effusions that fill the pleural space and partially separates the lobes.


45/56

Week 6 - Abdomen: CT & Sectional AnatomyItalics are not part of objectives, but can help with understanding

Hounsfield Units: Relates attenuation coefficients of tissue to that of water. Low

attenuation (negative) blocks only a few exrayso

Air = -1000o Fat = -50

o Water = 0

o Tissue = 40o Calcium = 100

o Bone = 1000

Metals can cause artifacts

Use CT Judiciously especially in the youth

1. Know when to order a CT scan of the abdomen

a.

CT is very usefull in the imaging of Cancer, Trauma, Vascular pathology, andAbdominal Symptoms

b. Intraabdominal fluid is a marker of pathology.

2. Be able to determine when to use contrast and when to order a non-Con Abdominal

CT

a. Oral and IV Contrast (IV is Iodine based)

i. Water soluble Oral contrast if you suspect Perforation.


46/56

ii. IV Contrast helps with vasculature, Viscera and distinguishes cystic from

solid.

b. Risk for IV Contrasti. Allergy (Pretreat with steroids)

ii. Renal insufficiency (Creatinine >2.0

c.

No Contrast for Head Trauma and Renal Stones3. Know how to diagnose the following conditions with an Abdominal CT

a. Kidney stones

i. History of Flank Painii. (Left Ureteral Stone on image on the right)

b. Appendicitis

i.

Worm like structure inferior to the cecumii. To find it, Find the ascending colon @ iliac crests and scroll down until

you reach the inferior cecum and find the worm.


47/56


48/56

d. Abdominal aortic Aneurysm

i. Pt typically has hypotension and distended abdomen.

Week 7 - Neuroradiology: CT scan

(1) How are skull fractures characterized on a head CT (linear vs. depressed)Linear: transverse full thickness of bone w/o being displaced downwardDepressed: comminuted fracture where bone is depressed inward, inc. pressure on brain

A skull fracture is most clinically significant if the paranasal sinus or skull base is involved.

- Distinguished from sutures

- Sutures have undulating margins both sutures


49/56

Linear skull fractures

This is the most common type of skull fracture. In a linear fracture, there is a break in the bone,but it does not move the bone. These patients may be observed in the hospital for a brief amount

of time, and can usually resume normal activities in a few days. Usually, no interventions are

necessary. Depressed skull fractures

This type of fracture may be seen with or without a cut in the scalp. In this fracture, part of the

skull is actually sunken in from the trauma. This type of skull fracture may require surgical

intervention, depending on the severity, to help correct the deformity. Diastatic skull fractures

These are fractures that occur along the suture lines in the skull. The sutures are the areas

between the bones in the head that fuse when we are children. In this type of fracture, the normalsuture lines are widened. These fractures are more often seen in newborns and older infants.

Basilar skull fracture

This is the most serious type of skull fracture, and involves a break in the bone at the base of theskull. Patients with this type of fracture frequently have bruises around their eyes and a bruise

behind their ear. They may also have clear fluid draining from their nose or ears due to a tear in

part of the covering of the brain. These patients usually require close observation in the hospital.

Intracranial hematoma (ICH)

There are several types of ICH, or blood clots, in or around the brain. The different types are

classified by their location in the brain. These can range from mild head injuries to quite serious

and potentially life-threatening injuries.


50/56


51/56

(2) Understand the most common clinical scenarios:

- Subdural, Subarachnoid, Intracerebral and Epidural Bleeds

- Subdural: rupture of bridging vein, usu. Due to deceleration and acceleration, or rotationalforces (atrophy predisposes, so common in elderly who fall)

- blood collects between arachnoid and dura matter, cant cross falx, tentorium

CT- Crescent shaped that crosses suture lines.May contain hypodense foci due to serum, CSF or active bleeding (pic on right)

Subarachnoid:


52/56

- injury of small arteries or veins on the surface of the brain

- bleeds into space between pia and arachnoid matta

- Trauma is most common cause- also due to rupture aneurysm

- worst H/A of life

- CT: Focal high density in sulci and fissures or linear hyperdensity in the cerebral sulci

Epidural Bleeds

-Usually associated with a skull fracture

-Lacerates a dural artery or a venous sinus (middle meningeal artery)-The blood collects between the skull and dura

-On CT, a hyperdense biconvex mass

-Can cross the dural reflections unlike a subdural hematoma-Usually does not cross suture lines where the dura tightly adheres to the adjacent skull


53/56

IntracerebralThe most common cause of non-traumatic intracerebral hematoma: hypertensive hemorrhage

Other causes include: Amyloid angiopathy

Ruptured vascular malformation

CoagulopathyHemorrhage into a tumor

Venous infarction

Drug abuse

Epidural hematoma

Epidural hematomas occur when a blood clot forms underneath the skull, but on top of


54/56

the dura, the tough covering that surrounds the brain. They usually come from a tear in an

artery that runs just under the skull called the middle meningeal artery. Epidural

hematomas are usually associated with a skull fracture.

Subdural hematoma

Subdural hematomas occur when a blood clot forms underneath the skull and underneath

the dura, but outside of the brain. These can form from a tear in the veins that go from thebrain to the dura, or from a cut on the brain itself. They are sometimes, but not always,

associated with a skull fracture.

Contusion or intracerebral hematoma

A contusion is a bruise to the brain itself. A contusion causes bleeding and swellinginside of the brain around the area where the head was struck. Contusions may occur with

skull fractures or other blood clots such as a subdural or epidural hematoma. When

bleeding occurs inside the brain itself (also called "intraparenchymal hemmorage"), thiscan sometimes occur spontaneously. When trauma is not the cause, the most common

causes are long-standing high blood pressure in older adults, bleeding disorders in either

children or adults, or the use of medications that cause blood thinning or certain drugs of

abuse. Diffuse axonal injury (DAI)

These injuries are fairly common and are usually caused by shaking of the brain back and

forth, which can happen in car accidents, from falls or shaken baby syndrome. Diffuseinjuries can be mild, such as with a concussion, or may be very severe, as in diffuse

axonal injury (DAI). In DAI, the patient is usually in a coma for a prolonged period of

time, with injury to many different parts of the brain.

(3) Understand the most common cause of non-traumatic intracerebral bleeds

Hemorrhagic stroke, due to hypertensive hemorrhage- 70-90% of non-traumatic primary intracerebral hemorrhages.

- Vasculopathy involving deep penetrating arteries of the brain.

-

Thalamus, pons, cerebellum, and basal gangliaBlood may extend into the ventricular system Associated with a poor prognosis

(4) Be familiar with the appearance of the following on a CT scan of the Head:

- Epidural Bleed- Subdural Bleed

- Subarachnoid Bleed

- Intracerebral Bleed- Hydrocephalus

- Skull Fracture

Hydrocephalus-

A problem with the ratio of production of CSF to its reabsorption

- Communicating hydrocephalus is the most common and is due to arachnoid villi and

subarachnoid space obstruction.

- Obstructive hydrocephalus is less common but may occur as a result of the following:aqueductal stenosis or occlusion; trapped 4

thventricle; ependymitis


55/56


56/56

Hydrocephalus Normal

Normal (top) Hydrocephaus (bottom)

Week 8 - Interventional Radiology (FYI only)1. Identify indications for common interventional radiology procedures

2. Introduce the student to the concepts of Interventional RadiologyDiscuss various clinical conditions and integrate interventional radiographic procedures as it

applies to the clinical concepts
http://www.seattlechildrens.org/uploadedimages/Seattle_Childrens/cmsassets/Images/hydrocephalus-normal-non-normal-ct-scans_large.gif

course objectives (complete, l1-7)

Documents