MRI
Certain structures are more difficult to evaluate on standard radiographs, but imaging is superior on MRI machines, which areas of the body are these?
Brain, Spinal Cord, Ligaments, Cartilage, softer tissue structures.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p211).
Compare and contrast the terms, "hyperechoic", "hypoechoic", "anechoic", and "isoechoic."
Hyperechoic: Will appear brighter in color in comparison to surrounding structures. Is reflecting an increased intensity of soundwaves.
Hypoechoic: Will appear darker in color in comparison to surrounding structures. Is reflecting a decreased intensity of soundwaves.
Isoechoic: Will appear as the same echogenicity as another structure.
Anechoic: Will appear black, no sound waves are reflecting.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p171).
What is the ideal positioning and collimation for a Lateral Abdominal for small animal?
Positioned in right or left lateral accordingly. Forelimbs pulled cranially, hind limbs pulled caudally, head in natural position. Collimation should begin 1 inch cranial to xiphoid process, and end caudally at the greater trochanter, should be centered over L2 and L3
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p251).
Compare and contrast kvp and mAs
kVp = Increasing kVp increases contrast of the image by "hardening the beam." (Quality of Radiation)
mAs= Increasing mAs increases amount of photons released, and changes density of image. (Quantity of Radiation)
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p71).
Mesial: opposite of distal, toward the rostral end of the mouth.
Occlusal: on the chewing surface of the tooth
Buccal: Towards the cheek
Lingual: Towards the tongue
Palatal: Towards the hard palate.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p417).
MRI scans require a contrast agent, what is this agent called and what is special about it?
Gadolinium, it is partially magnetic (paramagnetic), which allows it to alter the way certain tissues glow or appear under the MRI
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p216).
Compare and contrast the relationships probe frequency has with scan penetration and lateral spatial resolution.
Inverse Relationship between probe frequency and scan penetration. Ex. Frequency increases, then penetration depth will decrease or vice versa.
Direct Relationship between probe frequency and lateral spatial resolution. As Probe frequency increases, so does lateral spatial resolution, or vice versa.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p178).
What is the ideal position of a craniocaudal view of the radius and ulna in small animal?
Placed in sternal. Guide head, neck and unaffected limb away from the affected limb, hindlimbs can be kept in a natural position, while affected limb is extended fully. Collimation should proximally include the cubital joint, and distally include the carpal joint, should be centered over the middle of radius and ulna.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p308).
What is thermionic emission and where does it take place?
Thermionic emission is the process of creating a cloud of electrons when the cathode (tungsten wire filament) is heated with electricity
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p20).
What are the proper dental formulas for adult canines and adult felines? What about puppies and kittens with deciduous teeth?
Canine Adult: 3142/3143
Canine Deciduous: 313/313
Feline Adult: 3131/3121
Feline Deciduous: 313/312
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p418-419).
Why is it critical to have a patient's kidney function assessed before getting an MRI?
Gadolinium is eliminated from the body through the kidneys. We have seen necrotizing systemic fasciitis in humans with renal failure post MRI.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p216-217).
Compare and Contrast a linear, microconvex transducer.
Linear transducer: Produces a rectangular field of view, can be prone to artifacts, great for fine detail imagining.
Microconvex transducer: Produces a curvilinear field of view, while image quality is not as good, it is extremely helpful in smaller/exotic patients, and for scanning harder to reach areas such as the intercostal spaces.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p180-181).
What is the ideal positioning and collimation of a mediolateral view of the wing in a bird?
Should be in dorsal recumbency with the wing extended at a 90 degree angle. Collimation should include the whole wing and the scapulohumeral joint, and the center should be over the middle of the wing or area of interest. May use avian safe tape for security of wing/tail/pelvic limbs/head if sedated and necessary.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p588).
What is the focal spot and where is it located?
The focal spot is the target on the anode where the photons from the cathode are directed. From the focal spot, the photons bounce off of it produces x rays
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p21).
Compare and contrast when you would see foreshortening and elongation of a tooth?
Both occur when attempting bisecting angle technique. Elongation occurs when the machine is angled too strongly at the long axis of the tooth instead of the bisecting angle. Foreshortening occurs when the machine is aimed too strongly at the plate instead of the bisecting angle.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p424).
What is the main disadvantage of MRI in comparison to CT?
You cannot store raw data in MRI imagining, once the scan has been taken no adjustments to contrast or resolution may be made like one can do with CT.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p214).
What does adjusting the "focal zone" in ultrasonography do and why is it helpful?
Allows manual adjustment of what depth the beams converge during a scan. Can be beneficial to increase resolution of a particular body part on the scan.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p178).
What is the appropriate technique and positioning of a fish for a lateral radiograph and what might be an indication for this procedure?
Quickly yet gently place the fish into a plastic bag with its OWN WATER, and then position into lateral in the bag, and use a vertical beam to shoot. Following the radiograph, immediately release the fish back into its environment.
Indications: Swim bladder issues, neoplasia, trauma.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p622-623).
Which types of x-ray machines have a stationary anode and what special considerations should be made.
Stationary anodes are typically found in dental or portable machines. They are unable to dissipate heat as efficiently as the rotating anode and will need cool off time occasionally to avoid overheating.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p21).
Describe the parallel technique and where it is used in the mouth
Used with 307 and 407 and all teeth distal in canine and feline mouths. Placing the film directly behind the teeth, and shooting perpendicular to it.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p423).
How does MRI image processing work?
Patient's molecular structure aligns with the magnetism of the MRI machine. A radio frequency is then emitted to match the frequency of hydrogen atoms, as a response, the atoms enter a higher energy state and change their direction of magnetism.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p211).
Compare and contrast the difference between acoustic shadowing, acoustic enhancement, and edge shadowing artifacts.
Acoustic Shadowing: When scanning a denser object such as a urolith, the sound waves split to either side, creating a shadow distal to the object.
Acoustic Enhancement: When scanning a softer structure the sound waves travels through slower and reflects brighter just distal to the object.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p183).
What is the ideal positioning and collimation of a rostrocaudal frontal sinus view of a small animal?
Dorsal recumbency. Leave hindlimbs in natural position, and pull forelimbs caudally toward the chest. position the head comfortably, and secure the snout perpendicular to the table, mouth must remain closed. Should be collimated to the tip of the nose from the occipital crest, and should be centered between the eyes.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p393-394).
What is the anode heel effect? How does it influence patient positioning?
The cathode side of the machine produces a greater amount of radiation than the anode side. In order to maximize this amount of radiation, the thicker part of the patient should be positioned toward the cathode.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p21-22).
Describe the bisecting angle technique and where it is used in the mouth
Used on all maxillary teeth, all incisors, all canines, and mandibular PM 1 and 2 in canine and feline mouths. The bisecting angle should be shot between the film and the long axis of the tooth, may cause elongation and foreshortening if done incorrectly.
Source: Lavin's Radiology for Veterinary Technicians 7th edition (p423-424).