Lung Scan

Ventilation and Perfusion Scan

Results

A lung scan is a nuclear scanning test that is most commonly used to detect a blood clot that is preventing normal blood flow to part of a lung (pulmonary embolism). The results of a lung scan are usually available in 1 day.

Lung scan

Normal:	The radioactive tracer is evenly distributed throughout the lungs during ventilation and perfusion.
Abnormal:	The ventilation scan is abnormal but the perfusion scan is normal. This may mean abnormal airways in all or parts of the lung. Chronic obstructive pulmonary disease (COPD) may be present.
	The perfusion scan is abnormal but the ventilation scan is normal. Depending on the difference between the two scans, a pulmonary embolism may be present.
	Both the ventilation and perfusion scans are abnormal. This can be caused by certain types of lung disease, such as pneumonia or COPD.

Lung scan results can help your doctor determine the likelihood that a pulmonary embolism is present. The results are generally reported in one the following ways:

• Low probability. The results indicate that the likelihood of pulmonary embolism is low. Your doctor may feel that further testing is needed.
• Indeterminate or intermediate probability. The lung scan results show there is a possibility of a pulmonary embolism. More tests, such as angiogram or CT pulmonary angiogram, may be needed.
• High probability. The results indicate that the likelihood of a pulmonary embolism is high. No further diagnostic testing is generally necessary.

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Author:	Jan Nissl, RN, BS	Last Updated: November 1, 2006
Medical Review:	Patrice Burgess, MD - Family Medicine Kenneth B. Sutherland, CD, BSc, MD, FRCPC - Diagnostic Radiology
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