Oral Exam - Thoracic

Question 1

Proposed PE categories

Answer 1

• PE likely/present: High probability scan, with inclusion of a single-segmental VQ mismatch in the high probability category
• PE unlikely/absent: Normal and very low probability scans
• Non diagnostic for PE: All others

Question 2

PCP findings

Answer 2

Ga-67
– Early infection: Intense diffuse pulmonary uptake of Ga-67; no nodal uptake; may precede radiographic and physiologic abnormalities

Question 3

TB findings/MAC findings

Answer 3

Patchy/lobar pulmonary plus hilar nodal Ga-67 uptake

Question 4

Kaposi sarcoma

Answer 4

No Ga67 uptake

Question 5

Tl-201 and Ga-67 combined imaging

Answer 5

○ PJP: Thallium negative/gallium positive; diffuse
pulmonary uptake

○ Mycobacterial infection: Thallium negative/gallium
positive; mediastinal uptake

○ Bacterial pneumonia: Thallium negative/gallium positive;
focal pulmonary uptake

• Kaposi sarcoma: Thallium positive/gallium negative;

○ Lymphoma: Thallium positive/gallium positive; pulmonary and mediastinal uptake

Question 6

Ga-67 protocol

Answer 6

□ Physical t1/2: 78 hours
□ Principal photopeaks: 93 keV (40%), 184 keV (24%),
296 keV (22%), and 388 keV (7%)
□ Excretion: 10-25% by kidneys in first 24 hours,
followed by gastrointestinal tract
– Dose: 4-6 mCi IV

– Image acquisition
□ Large field-of-view multipeak gamma camera with medium-energy parallel hole collimator
□ Anterior and posterior projections obtained 24-72 hours after injection
□ 250k-1miltotalcountsforchest

Question 7

Lambda sign

Answer 7

Ga-67 or F-18 FDG PET/CT

symmetric hilar and right paratracheal activity

Question 8

Panda sign

Answer 8

Ga-67 or F-18 FDG PET/CT

symmetric lacrimal and parotid gland activity

Question 9

Defect size on VQ

Answer 9

– Large: > 75% of segment
– Moderate: 26-74% of segment
– Small:<25%ofsegment

2 moderates = large

Question 10

Concentric pleural uptake

Answer 10

Asbestos related pleural disease
Mesothelioma
Metastases
Primary pleural malinancy
Pleurodesis

Question 11

FDG avid effusion

Answer 11

80% chance malignancy

Question 12

HOA cause

Answer 12

Bronchogenic carcinoma
Pulmonary metastases
Other benign thoracic tumours
Mesothelioma
Bronchiectasis
Lung abscess

Question 13

Unilateral large matched defect

Answer 13

Low probability

Ddx: 
Central PE
Hilar mass
Severe unilateral parenchymal disease
Swyer james
Hypoplastic PA

Question 14

Bilateral upper lobe large mismatched perfusion defects

Answer 14

Consider artifact from MAA injection - patient should be supine
High prob PE
Asthma/COPD

Question 15

Kidney activity on MAA perfusion study

Answer 15

R-L shunt
Free pertechnetate
Recent study

Question 16

Causes R-> Shunt

Answer 16

Intracardiac (PDA, ASD)
Pulmonary AVMs
Cirrhosis resulting in intrapulmonary shunts

Question 17

Ddx high prob study

Answer 17

2 large or equivalent mismatched perfusion defects

Ddx:
Pulmonary vasculitis
Mediastinal adenopathy

Question 18

Triple match defect (PIOPED II)

Answer 18

Low prob in upper and mid lung

Intermediate prob in lower lung

Question 19

pneumothorax on ventilation scan

Answer 19

Activity on periphery of pleuaral cavity

Question 20

Ddx pleural fluid/thickened fissures on ventilation scan

Answer 20

Tumour microemboli
Lymphangitic disease
Pleural fluid

Question 21

Small subsegmental mismatched defecgt

Answer 21

Low probabilitiy
Ddx: 
Atelectasis
Bronchitis
Asthma
Pleural fluid
Pneumonia

Question 22

Large matched defects

Answer 22

Obstruction from: 
Neoplasm
Mucous plugging
Foreign body
Pneumonectomy
Pulmonary atresia

Reactive from:
CHF
COPD
Asthma
Pneumonia
Swyer James