Fundamentals Of Imaging Flashcards
What does CT image best?
- subtle fractures or complex fractures
- evaluating degenerative changes
- multiple injuries to both osseous and soft tissue structures can be determined from one imaging series
- evaluation of spinal stenosis
- condition of intervertebral disk
- evaluation of loose bodies in a joint
- less time consuming
- accurate measurements of osseous alignment in any plane
- less expensive
- not claustrophobic
What are the general advantages of ultrasound?
Low cost portability no contraindications not limited by orthogonal planes continuous modification
What are the abnormal characteristics of tendons and ligaments on an ultrasound?
Strains: thickening of mixed echogenicity
Ruptures: disruption of structure
What are the abnormal characteristics of surface cortical bone on an ultrasound?
break in continuity, uneven surfaces
What are the abnormal characteristics of muscle on an ultrasound?
muscle strain: disruption of fibrous bands
Rupture: retraction of muscle
What is considered the gold standard that all new imaging technologies are measured against?
Film/ screen radiography
Radiolucent is defined as?
Easily penetrated by x-rays.
Fracture line can be?
Transverse
Longitudinal
Oblique
Spiral
What is a complete fracture?
A fracture in which all vortices of the bone have been disrupted
What are some different forms of CT?
3D CT
CT myelogram
Cone beam computed tomography
The order of radiodensity of body matter:
Air (black)
Fat (gray-black)
Water (gray)
Bone (white)
MR imaging characteristics for inflammation:
T1 low signal intensity
T2 high signal intensity
Why can an MRI detect an injury that is not visible on a CT or radiograph?
The injury can leave a bone bruise as a “footprint”
What is three- dimensional CT?
Presents 3D images of body parts that can be rotated in space
What is one factor known to reduce error?
Communication between the clinical and radiologist
General components of a radiologic report:
Heading Clinical information Findings Conclusions/ Impressions Recommendations Signature of radiologist
What is fluoroscopy?
Fluoroscopy is a dynamic or continuous radiographic examination.
Evaluation of Alignment:
General Skeletal architecture
General contour of bone
Alignment of bones to adjacent bones
What are the advantages of MRI over CT?
Greater resolution for soft tissue imaging
No radiation
Less risk of missing disease processes
what is doppler ultrasound used for?
To measure blood flow in an artery or a vein.
Often used to rule out DVT
What is a radiograph?
A radiograph has been defined for over a century as an x-ray film containing an image of part of a patient’s anatomy
Why are stress fractures difficult to diagnose?
Because the fracture line or periosteal reaction may not be evident for up to 6 weeks
Evaluation of Cartilage spaces:
Joint space width
Subchondral bone
Epiphyseal plates
What does MRI image best:
Display of soft tissue detail
Tissue origins used to classify tumors:
Bone Marrow Cartilage Nerves Fat Fibrous Unknown
What is malunion?
Fracture has successfully united but a degree of angular or rotary deformity exists
What is slow union?
The rate of union, although slow, may be average or normal given he significant factors involved.
What are the ABCS of radiologic analysis?
A: Alignment
B: Bone density
C: Cartilage spaces
S: Soft tissues
Two types if trauma that can cause fractures:
Direct and indirect
What are the pitfalls of image interpretation?
Errors ! Errors of observation or errors of interpretation.
What are the different projections?
Anteroposterior (AP)
Posteroanterior (PA)
Lateral
Oblique
The MRI are actually what type of images?
They are slices
Direct forces that can cause a fracture:
Tapping
Crushing
Penetrating
Radiopaque is defined as?
Not easily penetrated by x-rays
What is nonunion?
Fracture fragments fail to unite and the processes of bone repair have ceased completely
Salter- Harris classification of epiphyseal fractures:
Type I-V
Rang’s Type VI
Ogden’s Types VII, VIII, IX
What are errors in interpretation?
Errors in interpretation can be linked to the practitioner’s failure to link abnormal radiologic signs to relevant clinical data
What are disadvantages of ultrasound over MRI?
limited ability to show joint surfaces and interarticular structures
only shows cortical outline
What is osteomyelitis?
Result of contiguous dissemination of a pathogen from an open fracture or surgical fixation
MR imaging characteristics of muscle:
T1 intermediate signal intensity
T2 intermediate signal intensity
Indirect forces that can cause fractures:
Bending Torsion Compression + bending Compression + bending+ torsion Traction
What makes a structure hypo echoic?
the structure reflects little energy
Categories of skeletal pathology:
Congenital Inflammatory Metabolic Neoplastic Traumatic Vascular
Interventional radiology:
Radiologists diagnose and treat disease nonoperatively
Why do clinicians need to view diagnostic images?
- A more comprehensive evaluation is obtained
- The information the clinician seeks is often of a different nature from the information the physician seeks and of a different nature from what may be described in the radiologist’s report
What is avascular necrosis?
Exists when the blood supply to a bone or segment of a bone is compromised, leading to localized bone death
What are stress fractures also known as?
Microfractures, fatigue fractures, and insufficiency fractures
What is radiodensity?
Radiodensity is the combination of physical qualities of an object that determine how much radiation it absorbs from the x-ray beam.
What is the most common disorder of the musculoskeletal system evaluated by radiology?
Trauma: fractures and dislocations makeup the majority of traumatic conditions
What are the limitations of MRI?
Length of time needed to produce an image
What does T1 imaging provide?
T1 imaging provides images of good anatomical detail, displaying the tissues in a fairly balanced manner
What is an ultrasound?
it is a cross sectional imaging method based on sound waves reflected off tissue interfaces
Magnetic resonance image:
A cross- sectional imaging technology that uses a magnetic field and radiofrequency signals to cause hydrogen nuclei to emit their own signals, which then are converted to images by a computer
How are tumors classified?
By their tissue of origin
Views of MR images:
Coronal images are viewed from the front
Axial images are viewed from below
Sagittal images are viewed from left to right for either side of the body
What is a big imaging difference between CT/ radiographs and MRI?
Structures that appear bright on radiographs and CT typically appear dark on MRI
What is it called when a structure reflects no energy?
anechoic
Radiodensities on a CT image:
Dense structures appear white or a light shade of gray whereas less dense structures appear dark
Evaluation of bone density:
General bone density
Textural abnormalities
Local bone density changes
MRI imaging characteristics of ligament and tendon:
T1 Low signal intensity
T2 Low signal intensity
Life threatening complications of fractures:
Hemorrhage (most common) Fat embolism Pulmonary Embolism Gas Gangrene Tetanus
What is a fracture?
A fracture is a break in the structural continuity of bone or cartilage
What is the contrast used for an MRI?
Gadolinium
For patients involved in high velocity injuries the trauma survey will include?
“Cross- table lateral” of the cervical spine
Anteroposterior chest
AP pelvis
Possible additions: CT of the head, cervical spine, thorax, abdomen, and pelvis, with or without contrast
How can an MRI potentially detect a stress fracture?
In a T2 weighted image a stress reaction can be seen
How is ultrasound used in rehabilitation?
physical therapists employ ultrasound imaging for diagnosing musculoskeletal disorders
Other common studies in musculoskeletal imaging:
Contrast- enhanced radiographs
Conventional tomography
Computed tomography
Nuclear imaging
What is pseudoarthrosis?
Abnormal condition associated with nonunion. “False joint” may form between the ends and be surrounded by a burial sac containing synovial fluid.
What is the purpose of a routine or standard radiographic examination?
To provide the most visualization of anatomy with the least number of radiographs and thus to expose the patient to minimal radiation
Why does a comminuted fracture not always have a clear fracture line?
Because it is a fracture with more than two fragments
What are the two other shade of gray on an x-ray?
Contrast media (bright white outline) Heavy metals (solid white)
MR imaging characteristics for stress fractures:
T1 low signal intensity with a dark band
T2 high signal intensity with a dark band
What is delayed union?
Fracture fails to unite in the time frame usually required for union
What is T2 imaging valuable for?
Detecting inflammation
Healing time frame for no operative extremity fracture:
4-8 weeks
What is reduction?
Restoring fragments to their normal an atomic positions
What is the difference between and open fracture and a closed fracture?
With an open fracture the skin is perforated regardless of the size of the wound. A closed fracture the skin remains intact
What is an incomplete fracture?
Only one portion of the cortex is disrupted
What is bone length discrepancy?
Some fracture healing can result in unacceptable shortening of bone length
How can interventional procedures be grouped?
Vascular and nonvascular procedures
Define decubitus:
It is both a body positioned on a horizontal surface and the use of a horizontal x-ray beam
What is the first imaging procedure to be done following the clinical examination?
Conventional radiography
What are the advantages of CT over MRI?
Less expensive More common Faster times Not as affected by motion Greater resolution for Cortical bone
What does “one view is no view” mean?
A single radiograph provides only two dimensions: length and width. The third dimension, depth, is compensated for by viewing a second radiograph projected at a 90 degree angle to the first image.
What is an example of interventional radiology?
Catheters, guide wires, needles, cannula, balloons, stents, and other devices are placed under the guidance of imaging to perform procedures that are often alternatives to surgery
When will bone fracture?
When the imposed load exceeds the bone’s tolerance
What are errors of observation?
Errors of observation can be linked to incomplete or faulty search patterns.
What is gandolinium?
A paramagnetic metal ion that can be used for regular MRI applications.
Different distributions of lesions:
Monostotic- affecting only one bone
Polyostotic- affecting multiple bones or multiple joints
Diffuse- affecting all or nearly all bones or joints
What is the fundamental tool of the musculoskeletal radiologist?
Conventional radiography
What is primary trauma survey?
When imaging was performed initially in the emergency department
What is neuroimaging?
Imaging of the brain, can be described in terms of structural imaging and functional imaging
Fracture complications in other tissues:
Arterial injury: small %
Nerve injury: most temporary; serious associated with open fractures
Compartment syndrome: circulation and function of tissues within a closed space are compromised by increased pressure
What is radiology?
Radiology is the branch of medicine concerned with radiant energy and radioactive substances including x-rays, radioactive isotopes, and ionizing radiation and the application of this information to prevention, diagnosis, and treatment of disease.
Evaluation of soft tissues:
Muscles Fat pads and fat lines Joint capsules Periosteum Miscellaneous soft tissue findings
What makes a structure hyper echoic?
the structure reflects a lot of energy
Upright can denote?
Seated or standing
What are the possible results of a routine radiographic examination?
Positive Negative Negative for one but positive for another Inconclusive Wrong
What is musculoskeletal imaging?
Musculoskeletal imaging is the sub specialty of radiology concerned with the diagnostic evaluation of the musculoskeletal system.
