Nuclear Medicine

Question 1

Species, abnormalities, labels

Answer 1

Lateral scan of a normal brain

A: vasculature of the scalp, underlying sheel, dorsal longitudinal sinus - progressively wider band coursing caudally

B: Nasopharynx - circular region of decreased activity

C: Parotid salivary gland

D: Transverse sinus courses in a rostroventral direction

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Question 2

Species, abnormalities? What are the two ovoid regions of high activity? Assuming you can see the faint x region of activity labeled, name it.

Answer 2

Dorsal scan of a normal canine brain

Parotid salivary glands

Cavernous and petrosal sinuses

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Question 3

Species, abnormalites - be specific

Answer 3

Dorsal brain scan, region of increased activity in left cerebellar region

meningioma

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Question 4

Species, abnromalities

Answer 4

Canine, dorsal scan, area of increased uptake in cerebellar and medulla oblongata area

meningioma

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Question 5

Name three reasons you might not visualize a brain tumor on a nuc med scan?

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Answer 5

• outside place of focus/obscured by other structures that absorb/scatter radiation
• tumors on midline have low detection rates such as astrocytomas
• corticosteroid administration decreases peritumoral edema

Question 6

Why might you have a false positive on a brain scan for a tumor?

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Answer 6

• see normal structures not always visualized - cavernous sinus if not perfectly dorsal (aka obliquity)
• auricle can cause artifact

Question 7

What two structures have activity that might hinder interpretation of a brain scan? and what can you do to help?

vru 1977 Dijkshoorn - Detection of Brain Tumors in dogs by scintigraphy

Answer 7

Parotid glands and choroid plexus

-administer sodium or potassium perchlorate prior to scan

Question 8

What does accumulation of radiopharmaceutical in abnormal brain depend on? (6 reasons)

1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats

Answer 8

1. increased vascularity
2. abnormal capillary permeability
3. uninhibited pinocytosis
4. adjacent reactive edema
5. increase in extracellular space of tumor
6. ability of tumor to transfer or bind molecules intracellularly

Question 9

Why might you have a technically poor brain scintigram? 6 reasons

1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats

Answer 9

1. insufficient activity administered
2. poor binding 99mTc to ligand
3. patient motion
4. insufficient time for clearance
5. decreased clearance due to severe renal disease

Question 10

Define sensitivity, specificity, PPV, NPV

1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats

Answer 10

1. Sensitivity is defined as the ability of a test to identify correctly those who have the disease
2. Specificity is defined as the ability of the test to identify correctly those who do not have the diseas
3. Predictive value of a positive test is the proportion of true positives (i.e., diseased individuals) among all those who have positive test results​
4. Predictive value of a negative test is the proportion of non-diseased individuals among all those who have negative test result

Question 11

What size tumor in man is consistently seen with brain scintigraphy? What is a factor that aids in visualization?

1994 Dykes - Retrospective Analysis Of Brain Scintigraphy In 116 Dogs And Cats

Answer 11

1 cm

peritumoral edema

Question 12

Is brain scintigraphy reliable for detecting diffuse disease and normal patients?

Answer 12

No