Intro to Radiology and Chest Xrays Flashcards
Xray advantages and disadvantages
advantage- fast, low radiation
disadvantage- poor soft tissue eval.
Chest radiography seems warranted in ARI when one or more of the following are present
- older than age 40
- dementia
- a positive physical examination
- hemoptysis
- associated abnormalities (leukocytosis, hypoxemia)
- or other risk factors, including CAD, CHF, or drug-induced acute respiratory failure.
types of nuclear medicine scans
VQ scan
bone scan
thyroid uptake
cardiac stress test
Pros of CT
- allows simultaneous visualization of many structures
- no superimposition of structures
- can be viewed in several planes (axial, coronal, sagittal)
- Quicker than MRI (LESS movement artifact)
- HIGHER spatial resolution than MRI
CONS of MRI
- VERY sensitive to movement (have to hold breath)
- SLOW
- VERY loud and claustrophobic
- does not image bone well
- gadolinium reaction
- multiple contradictions (cannot have metal in body)
how does a computed tomography (CT) work?
- a rotating beam of xrays is passed through patient and picked up by MULTIPLE detectors (motorized table)
- evaluated by a computer and converted to 2D slices
- data can be manipulated to generate various types of slices or to highlight various structures
when assessing lucencies and densities on X-ray and you see an abnormal finding, check for:
- normal anatomy
- structure formed by superimposition of 2 structures
- artifact due to inaccurate positioning
- true pathologic lesion
fluid from the circulatory system (out of capillaries)
exudates
what should you see w/ a lateral chest xray
- AP window
- Retrosternal airspace
- Lower 1/3 of sternum should be in contact w/ R ventricle
- CVA is most dependent position in upright film
what is the first line therapy for a bilateral aspiration pneumona
clindamycin 450-900 mg IV q8 hours
what type of imaging is ionizing?
Electromagnetic Radiation: Xrays, CTs
Particle Radiation: Nuclear medicine- bone scan, VQ scan, thyroid uptake, thallium cardiac stress, PET scan, fluoroscopy
common DDX for hip effusion in a 0-3 y/o
septic hip
hip dysplasia
occult fracture
length discrepancy
why would one want a lordotic chest xray?
better visualize structures in the thoracic apex obscured by overlying bone strutures
(ex. see apex of lungs better)
what workup would you do for a limping child
- 1st plain film- fx or foreign body
- possibly then:
- US: hip effusion- infection or transient synoviti- post viral
- MR: myositis, osteomyelitis, absess
- bone scan: osteomyelitis, bone mets
terms used for “black” on Xray, CT, MRI, US, nuclear medicine imaging
Xray- lucent CT- decreased attenuation MRI- decreased signal intensity US- decreased echogenicity Nuclear Medicine-increased tracer uptake
Silhouette/structure:
left heart border
lingula (anterior of left lobe)
how to assess level of inspiration on chest xray
- counting ribs
- 9 posterior ribs (angle downward)
- 7 anterior ribs
- heart shadow should not be hidden by diaphragm
- on an upright PA radiograph projecting above the diaphragm would be satisfactory
what are signs of a pneumothorax?
- visualization of visceral pleural line (MUST FOR DX)
- convex curve of the visceral pleural line paralleling the contour of the chest wall
- absence of lung markings distal to the visceral pleural line (most times)
- Cardiac or hemidiaphragm shift
- deep sulcus sign on supine radiograph
what % of CTs are done with contrast?
75%
what is penetration in chest xray interpretation?
- refers to adequate photons traversing the patient to expose the radiograph
- limited in pts of large size such that there is poor visualization of structures in the lower lung fields and in retro-cardiac location
what type of images are affected by excess fat
Fat and CT = great!
Fat and US= bad (obstructs image)
Fat and MRI= doesn’t affect image
- If spinous process appears closer to the right clavicle, the patient is rotated toward their _____
- If spinous process appears closer to the left clavicle, the patient is rotated toward their _____
- own left side
- own right side
*inverse relationship (if RIGHT clavicle is CLOSER, than it is rotated to the LEFT)
what is the best view to confirm the presence of pleural effusion?
decubitis, then lateral, then AP/PA
-bc its gravity dependent and shifts w/ position
normal anatomic landmarks of Chest PA and lateral view
- trachea
- carina
- aortic arch
- heart
- costophrenic angles
- hilum*
- diaphragm
indications for a bone scan
- screening for metastasis to bone
- stress fracture and other occult skeletal trauma
- early osteomyelitis
- early avascular necrosis
Rank these imaging modalities from least to most effective radiation dose:
CT abdomen and pelvis w/ and w/o contrast, CT abdomen and pelvis, CT chest, chest xray, Coronary CTA, PET scan
Chest xray (~10days) Chest CT (~2 yrs) CT abdomen and pelvis (~3yrs) Coronary CTA (~4 yrs) CT abdomen and pelvis w/ and w/o contrast (~7yrs) PET Scan (~8 yrs)
4 basic densities for CT
- Air (darkest)
- Fat
- Soft tissue
- Bone (white)
*Contrast appears WHITE on images
disadvantage of MRA
- resolution generally inferior to CT catheter angiogram
- does not image calcium or small vessels well
what is the difference between ionizing and non-ionizing radiation
Ionizing radiation breaks chemic bonds (DNA)
*but with any radiologic study we are adding energy into the person
Silhouette/structure:
upper right heart border/ascending aorta
anterior segment of RUL
what planes can CTs be viewed in?
coronal- front and back
sagittal- R and L
axial- top and bottom
main components of a radiology report
- patients demographics. (name, DOB, SSN, etc.)
- relevant clinical info and ICD-9 code
- Findings (description of study results)
- impression (conclusion or diagnosis)
*recommends = want you to do!
form when there is increased capillary Hydrostatic pressure or decreased osmotic pressure
transexudate
work up for Chest pain
- start w/ CXR
- if normal determine if need CT (cysts) or cardiac cath, etc, based on clinical presentation/hx
describe the fissures of the lungs
- Major oblique fissure- separates the LUL and LLL
- Right Major fissure- separates the RUL/RML from RLL
- Right minor fissure- separates the RUL from RML
what imaging things would you never do in a trauma?
- MRI bc it takes too long and pt may be unstable
- PO IV
Silhouette/structure:
upper left heart border
anterior segment of left upper lobe (LUL)
how to assess the mediastinum on chest xray
assess width and contour
- lower margin of the left hilum is at upper margin of right hilum (typically higher on L bc heart takes up space and pushes it up)
- higher density is symmetrical
why is contrast material used in MRI
to enhance blood vessels, most often in conjuction w/ brain imagine
The cardiac border or silhouette will appear larger on ____ radiograph due to the magnification effect of the more anteriorly located heart relative to the film.
an AP
what are the pre-read steps for chest xray interpretation?
- name/ date
- obtain old films to compare
- what type of view(s)
what is the difference between cold and hot nodules in a thyroid uptake scan
cold nodules (decreased uptake) are more concerning and require biopsy
MR contrast is associated w/ contrast reaction in who?
pts w/ severe renal failure (stage 4 or 5; GFR less than 30mL/min/1/73m2)–> causing development of the rare inflammatory disease nephrogenic systemic fibrosis
how does an ultrasound work?
- High-frequency sound waves are transmitted into the patient and the “echoes” of this emitted sound are picked up by a detector
- 2D image is generated based onthe strength and timing of the sound echoes
- Doppler US uses the Dopplerprinciple to detect and measure blood flow
- *NIVA-noninvasive vascular assessment
PROs of MRI
- non-ionizing radiation
- good for soft tissues ex. cartilage assessment (compared to CT)
- allows simultaneous visualization of many structures
- no superimposition of structures
- can be viewed in several planes
Things to look w/ joints on xrays
- articular cortex
- articular cartilage
- synovial fluid
- symmetrical joint space
- bone spurs
what is the difference between the parietal pleura and the visceral pleura?
- parietal: lines inside of thoracic cage- constantly reabsorbing and set through lymphatic system
- Visceral: adheres the surface of the lung- constantly producing fluid
what is “background” radiation?
- the radiation an avg person gets per year (~3 mSv per yr)
- depends on altitude (~1.5mSv more per yr in Colorado)
how do you order a CXR looking for line placement
- tell them where you placed the line!!
- EG tube should be on left side in stomach NOT through bronchus
what could cause a promient right atrium on an AP radiograph?
pt is rotated to their right side (left shoulder forward)
A routine x-ray assessment of extremities includes looking at…..
- soft tissues
- contour of each bone
- joints: articular space, joint space
- is anatomy normal?
- Lucencies/densities
- Location of lesion (requires orthogonal views)
ddx for widen mediastinum on CXR
- aortic dissection
- connective tissue disease
- lymphoma
- infection, TB
Almost all pleural effusions first collect in ____
a subpulmonic location beneath the lung
what are radiograph plain film images formed by?
penetration of xrays through tissue or other substances
- degree of penetration depends on density and thickness
What does a pneumoperitoneum look like on CXR?
CRESCENTIC lucency that parallels the undersurface of the RIGHT hemidiaphragm
*size proportional to volume of air
5 basic densities for X-ray
least to most
- Air
- Fat
- Water (soft tissue and blood–highly vascular tissue)
- bone (calcium)
- Metallic objects (contrast material)
*Darkest to lightest
types of radiation
- Electromagnetic
- Particle
- Acoustic
- Gravitational
what is inspiration in chest xray interpretation?
the volume of air in the hemithorax will affect the configuration of the heart w/ question of cardiac enlargement w/ a shallow level of inspiration
things to consider when ordering an imaging study
- cost
- risks (radiation)
- burden
- why are you doing the study
- indication driven imaging
what is a bone scan?
-Technetium-99m attached to a phosphate compound, is administered IV and is rapidly incorporated into newly forming bone
-areas of increased bone metabolism appear BLACK
(nuclear med)
common DDX for hip effusion in a 11-16 y/o
SCFE AVN overuse Tarsal coalition CG arthritis
why are children more sensitive to ionizing radiation then adults?
bc their cells are rapidly dividing, they are at increased risk for damage from the radiation
what is a VQ scan (ventilation/perfusion scan)
- Technetium-99m attached to albumin microaggregates, administered IV and is trapped in pulmonary capillaries
- ventilation is evaluated by a lung scan following inhalation of a radioactive gas (xenon, others)
- 2 scans are compared for VQ mismatch
Describe how an X-ray works
X-rays (ionizing radiation) is transmitted through the patient onto:
-a fluorescent screen that emits light, exposing a film
-a detector that converts the energry into a digital image
(xray source, object, detector/film)
abdomen structures to assess on chest xray
- liver
- stomach bubble
- splenic flexure of colon
- diaphragm
when is chest radiography indicated for someone w/ exacerbation of COPD (including asthma)
not typically indicated unless:
-suspected complication such as pneumonia or pneumothorax
OR
-unless one or more of the following are present: leukocytosis, chest pain, edema, or a hx of CAD or CHF
how does nuclear medicine work?
- a radioactive material w/ short halflife is given, usually IV (Technetium-99m)
- concentration in tissues or organs is measured w/ a gamma camera
- uptake of specific organ can be assessed
what is the orientation of CT (and MR) axial images
imagine you are standing at the foot of the supine patient
indications for US
- Fluid-filled structures (cysts)
- Breast abnormalities
- Hernias
- Gallbladder disease
- DVT
- Prostate (transrectal)
- Uterine fibroids
- Poor circulation, claudication
- Obstetrics (abdominal or transvaginal)
- ovarian torsion or testicular torsion
- ascites
- hydronephrosis
- masses
what is magnification in chest xray interpretation?
making reference to the position of the patient and the xray beam
what is an air bronchogram?
a tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammatory exudates
*indicates air space disease with fluid density outlining the air-filled bronchi
what is exudate most commonly seen with?
malignancy
DDX for severe RLQ in a female with possible imaging/work up
- appendicitis- US in kids, CT w/ contrast or MRI in adult (if preg.)
- constipation- PE and possible plain film
- Ovarian torsion- US is key!!
Silhouette/structure:
anterior hemidiaphragm
lower lobes (anterior)
thorax (soft tissues, and bone) structures to assess on chest xray
- ribs
- coracoid process and acromium process
- carina
- trachea
indications for a thyroid uptake scan
thyroid nodules
Silhouette/structure:
Right heart border
Right middle lobe (medial)
what is CT contrast made of?
Iodine-based and carries that risk of contrast ractions
How much air is required to see a pneumothorax on a chest radiograph?
about 500ml
how do you assess rotation of the chest radiograph
- judging the position of the clavicle heads and the thoracic spinous process
- Ideally the clavicle heads should be equidistant from the spinous process.
What is a HIDA (hepatobiliary iminodiacetic acid) scan?
Technetium-99m labeled HIDA, administered IV and is taken up selectively by hepatocytes and excreted into bile
-the test is positive if the gallbladder does not visualize, which is due to cystic duct obstruction, usually from edema associated w/ acute cholecystitis or an obstructing stone
types of acoustic radiation
ultrasound, sound, seismic
what is the standard way to order a chest xray and why?
- PA w/ corresponding lateral bc it will give appropriate magnification of the heart
- portable radiographs are typically bc pt cannot stand (heart appears larger)
why would contrast material be used in CT?
used to enhance blood vessels, GI tract, or renal/urinary collecting system
what is a MRA
- MRI used to image blood vessels
- typically no contrast is needed but gadolinium may be used for image enhancement
- often used in place of more invasive and more expensive CT catheter angiogram (carotid arteries, intracranial arteries, large vessels for aneurysm)
degree penetration depends on what?
density and thickness
CT- to contrast or NOT to contrast for Chest, Abdomen/pelvis, head
- Chest: NON-constrast- except pulmonary nodules, interstitial disease, PE
- Abdomen/Pelvis: Contrast- except kidney stones
- Head: NONcontrast is routine
how to assess ideal penetration
- thoracic spine should be barely perceptual viewing the cardiac silhouette
- see ribs through heart
- see pulmonary vessels nearly to the edges of the lungs
what are the findings/search pattern steps for chest xray interpretation?
Are There Many Lung Lesions
- abdomen
- thorax (soft tissues bones)
- mediastinum
- lung- unilateral
- lung- bilateral
common DDX for hip effusion in a all ages
septic arthritis Osteomyelitis cellulitis stress fx neoplasm neuromuscular
what type of imaging is non-ionizing?
Electromagnetic Radiation: Magnetic Resonance (MR)
Acoustic Radiation: ultrasound
what is the difference between density and lucency with X-rays?
density- “bright” opaque, object which inhibits transmission of xray beam (ex. bone)
Lucency- “dark”, allows transmission of xray beam (ex. air)
what type of movement can be seen w/ fluoroscopy?
- reflux
- peristalsis
- aspiration
what is fluoroscopy?
- “real-time” x-ray
- higher radiation exposure than plain film x-ray (ionizing)
what can poor rotation on a chest xray cause?
- distorts mediastinal anatomy and makes assessment of cardiac chambers and the hilar structures especially difficult.
- Chest wall tissue also contributes to increased density over the lower lobe fields simulating disease
what is a thyroid uptake scan?
technetium-99m pertechnetate, administered IV and is taken up by follicular cells of thyroid
- many benign and almost all malignant nodules do NOT concentrate radioiosotpes as well as normal tissue
- looking for cold vs hot nodules
uses of PET scans
- detection of CA and evaluation of responses to treatment
- assessment of CAD
- management of epilepsy
- evaluation of dementia
terms used for “white” on Xray, CT, MRI, US, nuclear medicine imaging
Xray- density CT- increased attenuation MRI- increased signal intensity US- increased echogenicity Nuclear medicine- decreased tracer uptake
when is fluoroscopy used?
- GI: barium swallow, barium enema
- Ortho: hardware placment, fracture reduction
- CV: angiography
- Other: PICC line placement, pacemaker, ICDs, hiatal hernia, GERD, aspiration, TE fistula, bilious vomiting
- Enema: lower obstruction
CONs of CT
- Higher dose of x-rays (CT of abdomen/Pelvis= 500 chest xrays)
- risk of contrast reaction
- Cost
- artifact w/ certain anatomical regions (posterior fossa)
indications for a VQ scan
suspect pulmonary embolus
- Posterior costophrenic sulcus blunting usually occurs with approximately ____ of fluid
- Decubitus views of the chest can demonstrate effusions as ___- __ mL
75 mL
15 to 20 mL
essential components of a radiology request
- patient ID
- study to be conducted
- Clinical history – ordering w/ symptoms NOT dx and pertinent clinical context)– give how trauma happen so that one can think about mechanism of injury
- reason for study (give DDX but dont say “rule out” “routine” or “pre-op”
- requesting provider w/ phone/pager number
what do the following mean in radiologist reports? "recommend" "consider" "Query" "paucity bowel gas" "no radio opaque FB"
“recommend”- DO IT
“consider”- F/U for further eval if needed
“Query”-i think there is
“paucity bowel gas”- no air. (could be fluid)
“no radio opaque FB”- No metal, coin, leaded gases.. DOES NOT include plastic, wood, food, paper, etc.
types of particle radiation
alpha, beta, neutron (particles of non-zero rest energy)
The vascular pattern in the lung fields will be accentuated with a _____ since the same amount of blood flow is now distributed to a smaller volume of lung.
shallow inspiration
13 step program to chest xray reading consists of what?
- pre-read (1-3)
- Quality control (PIRMA) (4-8)
- findings/ search pattern (9-13)
causes of pneumothorax
- pleural blebs
- Bullae
- emphysema and interstitial lung disease
- Traumatic and iatrogenic causes include penetrating wounds, line placements, lung biopsies and mechanical ventilators.
how does lack of penetration appear on xray
“whiter”
-can simulate pneumonia or effusion
*over penetration= dark
how does an MRI work?
-A magnetic field is used to align atoms in the body.
When the magnetic field is released, atoms emit radio
frequency radiation
-Radiofrequency radiation (nonionzing) emitted from the tissues is picked up by multiple detectors and processed by a
computer to generate 2D “slices”.
common DDX for hip effusion in a 4-10 y/o
JRA
toxic synovitis
legg-calve-perthes
what does COPD look like on a CXR?
f-latten diaphragm
- increased rib count
- a LONG NARROW heart
what are the quality control steps for chest xray interpretation?
PIRMA
- penetration
- inspiration
- rotation
- magnification
- angulation
Silhouette/structure:
aortic knob
apical portion of LUL (posterior)
types of electromagnetic radiation
radio waves, visible light, microwaves, x-rays, gamma radiation
what are causes of pneumoperitoneum
- rupture of bowel
- Peptic ulcer
- diverticula
- appy
- carcinoma
- trauma
- 5-7 days AFTER abdominal surgery
when would you get a HCT in a trauma case in:
- a kid less than 2
- a kid older than 2
less than 2: altered mental status, severe mechanism (MVA + ejection, death of another passenger, rollover, fall more than 0.9m, etc.)
older than 2: severe mechanism (MVA + ejection, death of another passenger, rollover, fall more than 1.5m, etc.)
CONS of PET scans
- VERY expensive
- HIGH ionizing radiation dose
what is MR contrast made of?
typically gadolinium
6 causes of an air bronchogram
- lung consolidation
- pulmonary edema
- nonobstructive pulmonary atelectasis
- severe interstitial disease
- neoplasm
- normal expiration
what is a salter fx
goes through both sides of growth plate
what is a PET (positron emission tomography) scan
- uses various radiolabeled compounds to evaluate chemical and physiologic function
- evaluates function , not structure
- HIGH ionizing radiation!
Indications for HIDA scan
- cholestasis (burning hands and feet)
- suspected acute cholecystitis (RUQ pain, N/V)
- post surgical evaluation of the biliary tract
- demonstrating patency of the common bile duct and ampulla
what is transexudate most commonly seen with?
CHF or cirrhosis
what is the difference between T1-weighted and T2-weighted MRI images?
T1-weighted: contrast is white, bone is black
T2- weighted: contrast is black, bone is white
how does a lordotic xray appear different than a PA or AP angle?
beam is angled up toward head so:
- unusually shaped heart
- clavicles will project superiorly relative to upper thorax (distortion of normal mediastinal anatomy)
- more horizontal rib orientation
what imaging is best for organ laceration
CT w/ contrast
*can tell if there is active bleeding too
compare the radiation of a nuclear medicine procedure to that of a diagnostic x-ray
about the same
-both ionizing radiation
what does pneumocystis carinii pneumonia (PCC) look like on CXR?
diffuse bilateral interstitial infiltrates (80-95%)
a fungal pneumonia commonly seen in pts w/ aids/HIV
how to assess for good angulation in a chest xray?
clavicles should lay over 3rd-4th rib and have an S shaped appearance
pneumothorax are most commonly seen in what type of people?
tall, skinny, smokers, (young)
what does a trauma series include?
plain film of chest, pelvis, and lateral spine
