Health

Preparation required before thyroid scintigraphy What patient preparation is required before thyroid scintigraphy? Patients should fast after midnight or, at a minimum, for 4 hours before receiving the radioactive iodine-123 ( 123 I) pill to maximize absorption through the gut. Patients should also avoid ingesting foods containing high amounts of iodine because they would saturate the iodine …

Preparation required before thyroid scintigraphy Read More »

What are possible causes of unilateral decreases in lung perfusion with relatively preserved lung ventilation on a ventilation perfusion scan? The most common cause of unilaterally decreased lung perfusion is a central mass lesion such as lung cancer, which has a predilection for affecting lung perfusion given the more readily compressible pulmonary vasculature compared to …

Possible causes of unilateral decreases in lung perfusion with relatively preserved lung ventilation on a ventilation perfusion scan Read More »

What are the causes of matched ventilation and perfusion defects on a ventilation perfusion scan? Most conditions associated with matched ventilation and perfusion defects arise from diseases affecting the airways with subsequent physiologic shunting of blood away from the underventilated regions. The most common causes of matched defects include COPD, bronchiectasis, and asthma. Other causes …

Causes of matched ventilation and perfusion defects on a ventilation perfusion scan Read More »

What does stripe sign signify on a ventilation perfusion scan? A “stripe” sign refers to a rim of radiotracer activity that surrounds the edge of a perfusion defect. The implication of this sign is that the subjacent perfusion defect is not the result of PE. This is because perfusion defects related to PE should extend …

What does stripe sign signify on a ventilation perfusion scan Read More »

How are ventilation perfusion scans utilized in patients who have had lung transplantation? In the immediate postoperative period, the V/Q scan can be useful to assess the transplanted lung for overall function. V/Q scans can also be useful to assess for pulmonary emboli in the transplanted lung and to assess for worsening function that may …

How are ventilation perfusion scans utilized in patients who have had lung transplantation Read More »

What does activity in the brain or kidneys imply on a perfusion scan? Some nuclear medicine departments will image the brain or kidneys to evaluate for a mechanical right-to-left shunt. Because the 99m Tc-MAA is too large to pass through the capillary beds of the lungs, all of the injected material should remain in the lungs unless …

What does activity in the brain or kidneys imply on a perfusion scan Read More »

How quickly do perfusion defects associated with pulmonary emboli resolve? Studies have reported varying rates of resolution of perfusion defects associated with pulmonary emboli. Some perfusion defects can resolve within 24 hours while others can persist indefinitely. For this reason, some clinicians recommend obtaining a V/Q scan approximately 3 months after treatment of PE to …

How quickly do perfusion defects associated with pulmonary emboli resolve Read More »