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Unformatted text preview: Lung Ventilation-Perfusion
)Scan (V/Q Scan
الدكتور قصي المقبل
أستاذ مشارك- قسم الشعة والطب
كلية الطب-جامعة العلوم والتكنولوجيا
الردنية Pulmonary Embolism
Pulmonary The main application of this procedure is
in pulmonary embolism investigation.
in Pulmonary embolism usually causes
perfusion defects, which usually occur in
more than one segment.
Technique Perfusion scan is usually correlated with
ventilation If perfusion scan is normal, ventilation
scan can be skipped.
scan If there are segmental perfusion defects,
then ventilation scan is needed.
Ventilation/Perfusion Types of Perfusion Defects
Types Mismatched Perfusion defects:
-Ventilation is normal in that segment
-Indicative of PE.
-Indicative Matched Perfusion defects:
-Ventilation defect in that segment.
-It is usually seen in parenchymal lung
RESULTS Normal perfusion scan:
means that the patient is very unlikely to
have acute PE.
have Low probability V/Q scan:
means that the patient has less than 20%
probability of having acute PE.
RESULTS-Cont.. High probability V/Q scan:
means that the patient has greater than
80% probability of having acute PE.
80% Intermediate probability V/Q scan:
means that the patient has between 20 –
80% probabilities of having acute PE.
80% High Probability for PE
Problem Intermediate probability is a frequent
finding in V/Q scans and creates a
problem for the clinician due to its wide
range of probability.
range CT-scan has replaced this test due to its
high sensitivity and specificity for acute PE
which reaches about 90%.
However.. However, V/Q scan is still indicated in
patients with underlying renal impairment.
patients Iodinated contrast given during CTIodinated
scanning can deteriorate renal function in
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- Fall '08