Intermediate Vq Scan Images

Clinical

HIGH probability: 80% chance PE LOW probability: 80% chance of no PE

Ventilation

2. 4-5mCi Tc-99m-DTPA 140 keV

Aerosol T1/2 = 6 h Initial phase 30 s

Equilibrium phase 3 min Washout phase 3 min

Perfusion

4 mCi Tc-99m-MAA (10-40 1 million particles T1/2 = 6 h

-Ventilation

-Lung volumes

-Exclude obstructive disease

Defect Size

High Probability

2 large/mismatched defects or the arithmetic equivalent in moderate or large defects

Intermediate Probability

1 large/2 moderate mismatched perfusion defects or the arithmetic equivalent in large and moderate defects

Low Probability

>3 small defects

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Very Low Probability

Nonsegmental defects (i.e., cardiomegaly, prominent hila, enlarged aorta), >2 matched defects

V/Q MISMATCH DDX

1. Primary vascular disease (vasculitis)

2. Radiation therapy

3. PE/previous embolus

4. Lymph nodes/Hilar carcinoma/ sarcoma/lymphoma

LIVER UPTAKE

Early: Fatty liver Late: Right heart failure

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