Introduction to Imaging—Part 3: Scintigraphy, Ultrasonography, DEXA, and Clinical Decision Making

Practice flashcards covering Scintigraphy, Ultrasonography, DEXA, imaging interpretation models (ABCs), AI in imaging, and referral communication models (SBAR, AGOLDMED).

What does Scintigraphy primarily indicate regarding bone health?

It serves as an indicator of increased bone metabolic activity.

How are radiopharmaceuticals administered during a Scintigraphy procedure?

They are injected intravenously ($IV$).

Where do radiopharmaceuticals concentrate in the body during Scintigraphy?

In areas of hyperfunction within the skeletal system.

What is a major disadvantage of Scintigraphy regarding the diagnosis of specific conditions?

It has poor specificity, as many conditions demonstrate similar increased uptake.

In what clinical scenario is Scintigraphy considered most valuable?

Detecting the presence and distribution of lesions.

List the three primary factors related to increased uptake of radiopharmaceuticals.

Increased blood flow, interrupted sympathetic nerve supply, and increased mineralization or osteoid formation.

Why do Scintigraphy results differ between adults and children?

Children have active epiphyseal plates that show naturally increased uptake.

What types of changes can Scintigraphy effectively demonstrate?

Osteoclastic and osteoblastic changes.

If metabolic activity has subsided, how might a Scintigraphy test appear?

It may be negative.

What specific application does Scintigraphy have for prosthetic joints?

Assessment for signs of infection or loosening.

According to Khanna & Gelfand (2024), Scintigraphy is used for the differential diagnosis of which two conditions?

Osteomyelitis vs. cellulitis.

Why does interpretation of Scintigraphy require caution with older patients?

Uptake becomes less uniform due to increased age and osteoporosis.

What process causes increased uptake at osseotendinous junctions?

Areas of constant stress and tissue remodeling.

What is the primary mechanism of Ultrasonography?

Sound waves are introduced through a transducer and are absorbed or reflected at tissue interfaces.

In Ultrasonography, what does the term 'hypoechoic' signify?

A decrease in echoes within the tissue.

In Ultrasonography, what does the term 'hyperechoic' signify?

An increase in echoes within the tissue.

Which anatomical structures show a tendency for greater echogenicity in ultrasound?

Fascial planes.

What does a hypoechoic area within a tissue generally suggest?

A change of structural integrity.

What pattern is typically seen in a longitudinal axis ultrasound of musculotendinous structures?

A fibrilinear pattern.

What is the sensitivity of Ultrasonography for diagnosing rotator cuff tears according to Ardic et al. (2006)?

$98.1\%$ sensitive.

How does Ultrasonography compare to MRI for detecting partial-thickness rotator cuff tears?

It is superior to MRI.

Why is Ultrasonography the 'go-to' screening method for Developmental Dysplasia of the Hip ($DDH$) in infants?

There is no risk of ionizing radiation.

What is the primary disadvantage of Ultrasonography according to Whittaker et al. (2019)?

It is very operator dependent.

What does the acronym DEXA (or DXA) stand for?

Dual Energy X-Ray Absorptiometry.

How is bone density calculated in a DEXA scan?

It is based on the attenuation of x-rays and the amount of radiation absorbed.

What is the radiation dose of a DEXA scan compared to a normal chest x-ray?

Approximately $\frac{1}{10}$ of a normal chest x-ray.

What is the weight limit for many DEXA models due to high BMIs?

$400$ pounds.

What is the 'Z score' in a DEXA report?

A comparison of the subject's bone density to age-matched individuals.

What is the 'T score' in a DEXA report?

A comparison of the subject's bone density to young healthy individuals.

According to the WHO, what T-score defines osteoporosis?

A T-score of less than $-2.5$.

According to the WHO, what T-score range defines osteopenia or low bone mass?

A T-score of $-1.0$ to $-2.5$.

Which imaging utility has high cost and high radiation according to Brunader & Shelton (2002)?

Quantitative Computed Tomography ($QCT$).

What are the 'ABCs' used for reading Radiography and CT images?

A = Alignment/Appearance, B = Bone Density, C = Cortex/Consistency or Cartilage Space, S = Soft Tissues.

Under the 'A' in ABCs, what specific characteristics of bones are evaluated?

Number, size, shape, contour, and position.

What consistency and space factors are reviewed under the 'C' in ABCs?

Joint space width and symmetry, subchondral bone contour, and epiphyseal plates.

When using ABCs for MRI, what extra factors are examined for soft tissues?

Signal intensity and tissue continuity.

How does Artificial Intelligence (AI) recognize pathology in digital images?

Algorithms recognize patterns of pixels that represent pathological vs. normal arrangements.

In which area is AI currently less accurate according to Ruitenbeek et al. (2024)?

Musculoskeletal disease detection, especially with MRI.

What should remain with the clinician regardless of AI accuracy?

Patient-centered decision-making.

What determines if imaging is indicated in terms of 'yield'?

High diagnostic yield and potential for change in management.

What factors suggest imaging is NOT indicated?

Low risk of pathology, low diagnostic yield, and potential radiation exposure.

What information should an imaging referral include according to ACR Practice Parameters?

Relevant clinical information, a working diagnosis, and/or pertinent clinical signs and symptoms.

What does each letter stand for in the SBAR model of communication?

S = Situation, B = Background, A = Assessment, R = Recommendation/Request.

In the SBAR model, what is included in the 'Assessment'?

Your hypothesis of the patient's problem.

What does the 'A' and 'G' stand for in the AGOLDMED model of imaging referral?

Age and Gender.

What does the 'O', 'L', and 'D' stand for in the AGOLDMED model?

Onset, Location, and Duration of symptoms.

What does the 'M', 'E', and 'D' stand for in the AGOLDMED model?

Mechanism of injury, Exam findings, and Diagnosis (hypothetical).

Which skill involves using evidence-based imaging guidelines according to Mabry et al. (2022)?

Skill $2$.

Which skill involves educating patients on imaging findings in the professional scope of practice?

Skill $7$.

What is Skill 9 in the physical therapist's scope regarding imaging?

Refer the patient if imaging findings are outside the physical therapist's scope.