HEENT Flashcards
What ending will be found on traditional x-ray studies to help you know it is an x-ray?
“graphy”/ “gram”
What is a “wet read” of an imaging study, in current terms?
Start initial review of images when time is critical, followed by more in-depth interpretation. Early/preliminary
What are the basic densities of tissues on x-rays and CTs, and what do they look like on imaging?
5 basic densities of tissues on X-rays:Air, Fat, Soft tissue/fluid, Calcium, Metal
What does air look like on imaging?
Least dense, appears mostly black.
What does fat look like imaging?
slightly gray
What does soft tissue and fluid look like on imaging?
slightly gray
What do bones/kidney stones/ gallstones look like on imaging?
white, more dense
What do metals look like on imaging?
most dense, appears brightest on X-ray- white
What are the types of contrast used with x-rays? What are the major possible adverse effects?
Contrast highlights structures that may be hard to distinguish otherwise. Types of contrast:
1. Oral: Barium (GI tract)- crossover with shellfish and iodine allergy so be careful. Air- Contraindicated in bowel perforation. Water soluble (iodinated)
2. IV (water soluble)
3. Inhaled
4. Rectal (enema). Barium. Air. Double Contrast: like the picture below. It shows an apple core sign which is usually a sign of colon cancer.
What are the risks, uses of x-rays?
radiation exposure
What are the benefits of x-rays?
easy, fast, cheap
What are the limitations of x ray?
hard to see soft tissues changes, multiple views needed to see 3D relationships
What are the common uses of x-rays?
CXR, Abd x ray, skeletal x ray, soft tissue foreign body, fluoroscopy, mammograms
Describe fluoroscopy and its primary uses.
Rapid series of x-rays projected on a screen and forms a video
1. Visualization of movement- typically a swallowing study like GI tract (contrast)
2. Visualization of anatomy. Joint injection- gets harder with pts with arthritis. Lumbar puncture- 2 people have to have tried and failed to do this. Angiography (contrast)- heart caths. Genitourinary studies (contrast)- Vesicoureteral reflux (VUR) reflux
Describe what a Hounsfield unit is
Each image=thousands of pixels. Each pixel is assigned a Hounsfield unit based on attenuation. Hounsfield units: -1000 to +1000
give typical Hounsfield units (HU) for air
-1000 HU
give typical Hounsfield units (HU) for water
Water= 0
give typical Hounsfield units (HU) for bone
+400 to +600
give typical Hounsfield units (HU) for organs and fat and metal
Lung: -600 to -400 HU and Fat -100 to -60 HU Soft tissue= +40 and +80 Metal:+1000 HU
Describe what a CT “window” is. What are the typical windows used in clinical practice?
In PACS, can adjust how HU are displayed in order to see different tissues better. Common Windows: Bone (+400), Lung ( -600), abdomen (+150) and brain (+40)
Describe the orientation of the typical CT image
Left side of the picture is the right side of the patient. As if you are standing at the foot of the bed. Initial images are in axial plane. Axial images can be post-processed to give sagittal and coronal views
Describe the types of contrast used with CT scans
Contrast: Water soluble (iodinated). Can be given IV, oral, or rectal. Oral/rectal-enhance GI structures. IV-enhance soft tissue structures and blood vessels use for cancer, abscess, or infection. IV affects the kidneys. Anyone with poor kidney function, we run the risk of sending them into dialysis. If they are already on dialysis it doesn’t matter. Don’t use: active bleeding (toxic to tissue), looking for stones, looking for fractures.
What are the risks for using or not using contrast
acute kidney injury, more likely with underlying kidney disease. To reduce the risk, we can over hydrate our patients and wait 24-48 hours between administration.
What are the contraindications for using contrast?
decreased renal function. Iodine allergy/shellfish allergy. To reduce risk of allergic reaction, can antihistamines and steroids prior to giving contrast. Can order CT scans- w/ or w/o contrast, CT Angiography-specialized view of blood vessels
Describe the risks of CT scans
increased radiation exposure, contrast risks
What are the benefits of CT?
fast, good visualization of soft tissues and bones, easier to see 3D relationships
What are the limitations of CT?
less readily available, more expensive, size issue- 350 pound weight limit.
Describe the common uses of CT scans
brain/spinal cord imaging, chest, abd. Pelvis, blood vessels, bone evals
What are some newer uses for CT?
virtual colonoscopy, virtual bronchoscopy, 3D reconstruction
Describe the process used in MRI to get signals from the body
Magnetic Resonance Imaging. No radiation. Uses strong magnetic field using protons is tissues are forced into alignment with the magnetic field. Pulsed radiofrequency signals push protons (more=more protons, = brighter images) out of alignment. When radio signal stops, protons return to alignment with magnetic field- emit a signal as they realign-detected by the scanner and strength of signal depends on relative amount of protons in the tissue. Computer processing of signals yields images.
Describe the differences between T1 and T2 images
Signals are detected at different time intervals after the radio signal ends. T1: shorter interval T2- longer interval. Protons in fat realign faster than protons in water. T1 images-fat is bright and T2 images- fat and water are bright. T2 images usually processed to remove signal from fat-highlights water. Compare T1 and T2 images to detect areas with increased water. Increased water= edema, likely from cell damage. Other types of images: FLAIR: fluid attenuated inversion recovery. Diffusion weighted. In T1- gray matter shows up gray because it is surrounded by myelin which contains fat. In T2, they have a mass and swelling. This is where pathology is gonna show up best. SX with the mass: headache, issues with movement, balance issues, nausea, worse at night and in the morning, especially for several days in a row. If it is on their left, it will affect the right side of the body.
Describe the risks of MRI scans
strong magnet + metal in the body, contrast risks. No one with a pacemaker can have an MRI.
What are the benefits of MRI?
no radiation, good visualization of nervous ligaments and tendons (ACLs), good visualization of masses.
What are the limitations of MRI?
less readily available, much more expensive, longer time to obtain images, size issues, anxiety/claustrophobia- small tube and loud- may use ativan oral or IV. some people need to be full on sedated. For 30 mins
Describe the common uses of MRI scans
brain and spinal cord imaging, abdomen/pelvis imaging. Ligament/tendon/cartilage/bone imaging. Will show osteomyelitis.
Describe the process used in nuclear imaging scans
Uses radioactive isotope. Isotope injected and after time lapse, gamma detector detects concentration of isotope and creates image. Looking for areas of increased concentration or decreased concentration. Example-thyroid. Isotope breaks down to inert substance cleared by the body (urine/stool).
When doing these scans. Consider if the female is pregnant or if they have babies or kids, make sure they are kept away from their kids for awhile so the radioactive isotope can leave their system.
What areas are the most concerning for thyroid cancer?
cold spots
Describe the risks and benefits of nuclear medicine scans
Risks: radiation
Benefits: analysis of function
What are the limitations of nuclear medicine scans?
less readily available, much much more expensive, poor spatial resolution, takes a long time
What are the uses for nuclear scans?
Thyroid scan, parathyroid scan, bone scan, cardiac stress test (do we need to go in and do a heart cath), Positron emission tomography (PET) scan
Describe the process used in ultrasound to obtain images
Sound waves transmitted into tissue. Reflected signal detected and turned into image on screen. Transducer- generates sound waves and detects reflected signals, many different shapes and orientations, producing different frequencies of sound.
Higher frequencies- better resolution don’t penetrate deeply, abscesses vs. cellulitis
Lower frequencies-less resolution but penetrate further , appendix
Small transducers on the ribs
Medium on the belly
Transvaginal or transrectal
Describe the level of echogenicity seen with different types of tissues, and describe the appearance on the ultrasound image.
Different tissues given different amount of reflection
Fluids-minimal reflection-dark area on screen
Bone-maximum reflection- bright area on screen with shadow beyond
Soft tissue- moderate reflection-gray area
Anechoic: no echo because it is air or fluid
Hyperechoic: really dense connective tissue
Isoechoic: liver, kidneys, solid organs
Hypoechoic: blood, not in a vessel
Describe how an ultrasound image is oriented on the screen versus the orientation of the transducer
Describe the risks and benefits of ultrasound scans.
Risks: no major risks identified
Benefits: fast, no radiation, can be done at the bedside
Describe the limitations of US
bone, bowel gas blocks visibility, lower resolution, dependent on operator experience/technique, body habitus
Describe the common uses ultrasound scans.
Uses: cardiac function, vascular evaluation, soft tissue evaluation, fluid evaluation, fetal evaluation, needle guidance
Describe Water view
PA view with head titled up. Maxillary sinuses with a better view
Describe Caldwell view
PA view with head titled down to see the frontal sinuses. Bow to Mr. Caldwell
Describe orbital view
Similar to Water’s view but shows orbits better- Metal fragments, Orbital floor fracture (muscles can get caught in the fracture limiting movement)
Describe a nasal bone view
Magnifying the nasal bone
Describe a mandible view
focus on the mandible
Mandible-Panorex
@ the dentist or with trauma, widened view and goes all around
Cervical Spine AP view
Lateral view
Cervical Spine Oblique
Cervical Spine Odontoid
C1 and C2: critical for head support and spinal cord because the skull rests on the top of the atlas
Describe what a fracture looks like on an x-ray
Fractures are disruptions of the brighter cortex of the bone
Describe what sinusitis looks like on an x-ray
Sinusitis: look for symmetry of sinuses and fluid It will look cloudy/grey.
Describe what epiglottitis looks like on an x-ray
thumb print sign
Describe what a retropharyngeal abscess looks like on an x-ray
When would you use CT maxillofacial without contrast
Trauma to the facial bones
When would you use CT maxillofacial with contrast
evaluation of masses
When would you use CT head without contrast
trauma of skull bones
When would you use CT head w/o contrast
orbital fracture
When would you use CT orbits without contrast
orbital fracture
When would you use CT neck with contrast
Eval of masses/swelling. Eval of hoarseness. Eval of dysphagia. Eval of stridor
When would you use CT sinuses without contrast
evaluation of sinuses
When would you use CTA neck
Blood vessels
Describe the indications for an MRI of the brain
Hearing loss (unilateral) weber-rinne-CN8. Vertigo (inner ear/stroke). Eval of masses (stroke, maybe), eval of brain/spinal cord (Neurology)
Describe the differences on ultrasound between cellulitis and abscess
Identify the pathologies
Epiglotitis with a thumb print sign
Identify the pathologies
CT of the sinuses, the left is impacted
identify the pathology
Retinal detachment
Identify the pathology
Left tonsil is infected
Identify the pathology
Hearing loss/vertigo Can happen bilaterally, MIDDLE AGED PERSON (40s). Acoustic neuroma tumor on CN8 unilateral hearing loss
Describe the indications and contraindications for nasal and sinus endoscopy
Contraindications-relative: trauma (make sure there are no fractures), intracranial infection, bleeding disorder or on blood thinners
Describe possible causes and the diagnostic workup for sialadenitis (enlarged salivary gland)
enlarged salivary gland (sialadenitis), infection, blocked salivary duct (stone= sialadenolithiasis), Cancer
DX: imaging: CT, MRI, US, biopsy if needed
Describe how and when eye pH should be measured
Indication: chemical burns. Worry more about alkali stuff Measure between the lower lid and eye. pH paper.
Acidic vs alkali- measure pH in both eyes- measure between lower lid and eye pH 7.0-7.3
Irrigate thoroughly and measure pH at intervals until pH is back to normal
Describe how to distinguish conjunctivitis from scleritis
Both conditions have hyperemia (engorged vessels) “conjunctiva is injected”
Scleritis- needs ophthalmology eval, much more concerning
Location in eye: conjunctiva, episclera, or sclera phenylephrine solution- shrinks vessels in conjunctiva/episclera see a lot of white a few mins after, but not in sclera
Describe the indication and process for fluorescein staining of the cornea
Indication: evaluate for cornea abrasions/foreign bodies SX?
Fluorescein=dye that fluoresces with blue light. Normal cornea-evenly distributed. An abrasion/foreign body-fluorescein concentrated at that site. Application: drops or strips
Describe the process of tonometry and normal/abnormal finding
Screening for increased IOP (yearly eye exam), evaluate eye pain, redness, decreased visual acuity.
General principle: force is used to flatten the cornea, amount of force needed is related to IOP. Normal IOP- 10-20 mmHg. 20 mmHg<glaucoma.
What are some contraindications and examples for tonometry?
Contraindications: trauma, recurrent abrasions, active infection
Ex: goldman tonometer. Contact made with cornea-anesthetic needed. Force is applied to applanate a specific size/area. Visual lines on apparatus are aligned. Risks: infection and overapplication of force. Even amounts of pressure, line ares even
Air puff tonometer that use air to flatten cornea and the amount of deformation is measured and correlated with IOP. Eyelid: pressure measured thru upper eyelid
Orbital cellulitis requires what kind of imgaing modality?
CT with contrast
Opacification with air-fluid levels on CT is indicative of what?
Sinusitis
What is the best way to view a retinal detachment?
US
When evaluating a zygomatic fracture, what imaging modality is best?
CT maxillofacial without contrast using a bone window.
pulsatile masses need what kind of imaging modality?
CT with contrast and angiography
Thyroid nodules and malignancies are best viewed with which modality?
US of the neck
Patietns with a neck mass and history of cancer treatment need what imaging?
CT with contrast or CT w/ PET
