No ventilation on inspiration to lung becaused pluged. Causes of perfusion defects on a vq scan dr matt a. A single moderate perfusion defect is appropriately categonzed as intermediate, rather than as low probability. For intermediateprobability scans, 2 separate datasets were produced and analyzed. Vq lung scan what to expect during a ventilation and quantitative lung scan. Low probability scan when there is matching perfusion and ventilation defects. Vq scanning is very important for several reasons, one being that it can help identify chronic thromboembolic pulmonary hypertension or cteph, a disease caused by blood clots. Vq scan lung ventilation and perfusion what you need to know.
These conditions do give rise to unmatched perfu sion defects. Single matched defect may be better categonzed as intermediate probability. Vq scanning is the initial screening test of choice to detect cteph. The ventilation scan may also provide additional information about cardiopulmonary disorders other than. Matched or reversed mismatch vq defects of any size, shape, or number in. Nuc116 vq interpretation at gateway community college studyblue.
Part 1 ventilationperfusion lung scan linkedin slideshare. The main criticism of the vq scan is the high percentage 6070% of indeterminate results low probability or intermediate probability. Pulmonary hypertension is a contraindication and vq imaging cannot be performed. A vq scan, more properly known as a ventilation perfusion scan, is used to examine two different elements within the lungs. Aerosol lung scan, radioactive ventilation scan, ventilation scan, vq lung scan, xenon lung scan. Think of all the things they can test you on for a vq scan. Low probability criteria multiple matched vq defects, regardless of size, with normal cxr triple matched i. Most patients with cteph have very abnormal vq scan findings and often have multiple moderate and large perfusion defects, without matching ventilation defects, in their lungs 23,25.
Ventilation perfusion mismatch or vq defects are defects in total lung ventilation perfusion ratio. However, mismatched ventilationperfusion pattern was shown on the upper right lobe, which was consistent with pulmonary embolism figure 3. A vq scan is a test used to show the air flow and blood flow in your lungs. Reverse ventilationperfusion mismatch is most often caused by obstruction of the airway, most commonly secondary to a. Causes of perfusion defects on a vq scan radiology. Mar 06, 2017 a vq scan, more properly known as a ventilation perfusion scan, is used to examine two different elements within the lungs. In copd, distribution of ventilation is uneven, and in aerosol studies, focal. You will then have pictures taken lying on your back with your arms raised over your head. Value of lung perfusion scintigraphy in patients with idiopathic. Typically the defect is segmental, while the ventilation scan remains normal, the socalled mismatched perfusion defect. A large defect generally involves more than 75% of the expected volume of a bronchopulmonary segment. Vq images showed severe unilaterally matched vq defects on the right middle and inferior lobes. Lung scintiscanning an overview sciencedirect topics. In pna is the vent or perfusion defect usually larger.
Vq ventilationperfusion scan is a scintigraphic examination of the lung that. Ct is an ideal initial test in those patients with high clinical suspicion in whom you may choose to perform ct first or in those. Interpretive criteria developed from the pioped, pioped ii, or pisaped trials can be used to determine the probability of a pulmonary embolism on a vq scan. This report offers a more detailed description of the prone maneuver in a case where repositioning revealed underlying normal perfusion in an area with a previous matched. A highprobability scan was suggestive of chronic thromboembolic pulmonary disease, whereas a lowprobability scan was suggestive of nonchronic thromboembolic pulmonary disease etiology. A single matched segmental perfusion defect of any size, with clear chest xray. The left lung has multiple wedge shaped blood flow defects. Patchy distribution nonsegmental defect matched vq defects abnormal cxr finding. Patchy, inhomogeneous uptake is seen primarily in the middle and. Normally, capillary perfusion and alveolar ventilation are matched in order. It is usually done if your healthcare provider thinks you have a pulmonary embolism blood clot. Ventilationperfusion scan an overview sciencedirect. A properly performed perfusion scan, which includes at least six projections, is highly sensitive for the detection of small defects.
A normal ventilation scan even distribution of radionuclide throughout the lung fields with multiple, bilateral perfusion defects are the classical. Perfusion defects that match ventilation and cxr abnormalities in size and location are called. Most patients with cteph have very abnormal vq scan findings and often. In one dataset, intermediateprobability scans were considered as. According to the modified pioped criteria, a q scan must show at least 2 large or segmental wedgeshaped defects that are mismatched meaning without correlating wedgeshaped defects on v scan or chest xray to be interpreted as high probability for acute pe. The ventilationperfusion lung scan is recommended to exclude chronic. Vq lung scan definition of vq lung scan by medical. Unless the vq scan is low probability and the clinical suspicion is low, the diagnosis of pe cannot be excluded or made based on a nondiagnostic study. If there is a clot present, the scan will show that areas of the lung are being ventilated but not perfused. The aim of the scan is to look for evidence of any blood clot in the lungs, called pulmonary embolism pe. Mimickers of chronic thromboembolic pulmonary hypertension on. Regional ventilationperfusion mismatch pattern in patient. This ia a 76yearold male with malignant neoplasm of the lung.
For patients with pulmonary hypertension vq imaging requires a. The patient will be asked to breath in a radioactive gas through a tube to demonstrate the air supply to the lungs. Vq scan the vq, or lung ventilation and perfusion scan uses a gamma camera and small amounts of radioactive tracer to take images of the air and blood supply to the lungs. Various conditions can cause mismatched defects on. Potential role of the ventilation and perfusion vq lung. One to three small segmental perfusion defects vq scan. The first part of the test involves having the patient inhale radioactive material and then taking pictures of the lungs as it is inhaled. There are several causes leading to a perfusion defect on a vq scan with. Perfusion scan from a patient with severe chronic thromboembolic pulmonary hypertension. Nuclear medicine vq scan loyola university chicago. I set the files to be ignored again, and the outstanding defects view is empty again. Ventilationperfusion scintigraphy is more sensitive than. Can have air trapping on washout due to collateral air drift nodec perfusion because of reflex arterial constriction.
The vq scan, however, is the preferred and recommended screening test for chronic thromboembolic pulmonary hypertension cteph, a severe, longterm complication of acute pulmonary embolism that can potentially be cured only with pulmonary thromboendarterectomy pte surgery. Extensive matched vq abnormalitiesare appropriate for low probability, provided that the cxr is dear. A case offalsepositive high probability ventilation. Various conditions can cause mismatched defects on ventilationperfusion scanning including emphysema. There are several causes leading to a perfusion defect on a vq scan with an acute pulmonary embolus being only one of them. The test is performed in two parts to test air flow and blood flow.
Perfusion defects match those seen on initial breath image of the ventilation scan. It is a condition in which one or more areas of the lung receive oxygen but no blood flow, or they receive blood flow but no oxygen due to some diseases and disorders. A ventilationperfusion vq scan is a nuclear medicine scan that uses radioactive material radiopharmaceutical to examine airflow ventilation and blood flow perfusion in the lungs. Ventilationperfusion vq mismatch occurs when either the ventilation airflow or perfusion blood flow in the lungs is impaired, preventing the lungs from optimally delivering oxygen to the blood. Its most common use is to diagnose a suspected clot on the lung pulmonary embolus. A pulmonary embolism pe may be caused by a blood clot that travels from your leg to your lungs. The threedimensional location of ventilation or perfusion defects must be. Common use to assess pulmonary ventilation to assist in diagnosis of pulmonary embolism. Eanm guidelines for ventilationperfusion scintigraphy. Nuc116 vq interpretation at gateway community college. Some of the key advantages include, ease of availability and simplicity of interpretation. Ventilation perfusion scan vq scan test for blood clots.
The first part, the ventilation scan, shows how well you get the air in and out of your lungs when you breathe. This is the classic finding for a pe in a vq scan but not all scans are that clearcut so additional. Detailed analysis of patients with matched ventilationperfusion defects and chest radiographic opacities. Lung perfusion only vq this study examines the air and blood flow into the patients lungs and is primarily used to diagnose blood clots in the lungs. The perfusion scan involves an intravenous injection. However, this high sensitivity is not matched by a high specificity for the diagnosis of pulmonary embolism.
Pulmonary imaging with ventilationperfusion single photon emission. Patchy areas of high and low ventilationperfusion matching are usually seen. The perfusion is usually not affected much but bottom line is the vq scan will be more difficult to read and the results may be inconclusive. When stopped ignoring them, the defects appeared in the outstanding defects view. Reverse ventilationperfusion mismatch is most often caused by obstruction of the airway, most commonly secondary to a mucus plug. Vq scan a type of medical imaging using scintigraphy to evaluate the circulation of air and blood within a patients lungs. Perfusion scintigraphy in diagnosis and management of. The ventilation part of the vq scan will show air trapping which may be patchy. The ventilation perfusion scan or vq scan is used to evaluate for the presence of blood clots in the lungs. Patients with patchy perfusion defects had a worse outcome. In patients with pah, the ventilationperfusion scan typically is normal or displays only minor, patchy perfusion defects, whereas in patients with cteph, at least one but often several major segmental or subsegmental mismatches in ventilation and perfusion will be evident figure 585, a and b. This vq scan primer has been prepared by dr richard channick, associate. The ventilation scan if done involves breathing in a radioactive substance called technegas.
A pulmonary ventilationperfusion or vq scan is a series of two lung scans. This useful maneuver has been reported previously to convert indeterminate probability to low probability scan. Detailed analysis of patients with matched ventilation. A ventilationperfusion lung scan, also called a vq lung scan, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patients lungs, in order to determine the ventilationperfusion ratio. What is the result of abnormal vq scan if pulmonary embolus. The vq ratio of a healthy lung is approximately equal to 0. Most commonly, vq scans are used to evaluate patients suspected of having pe. Vq scan is still the recommended initial imaging test for the workup of pe pulmonary embolism although many institutions have replaced vq with ct because of uncertainty with how to manage nondiagnostic vq scans. The second part, the quantitative scan, shows how well blood flows to your lungs. The cardinal sign of pulmonary embolism is an underperfused part of the lungs on perfusion scanning. Vp match it has long been recognized that the pulmonary. Informed, consent, medical imaging, nuclear, medicine, vq, vq, scan, pregnancy, xray, xray, radiology created date.
Diagnostic evaluation of chronic thromboembolic pulmonary. Contrast done with inhaled radioactive material xenon gas or technetiumdtpa. A chest radiograph taken within 2 hours of the vq scan shows complete opacification and some volume loss of the entire left lung which correlates, well with the vq scan figure 4. Nov 12, 2014 low probability criteria multiple matched vq defects, regardless of size, with normal cxr triple matched i. Matched ventilationperfusion defect from a pleural. At least one, and more commonly multiple mismatched perfusion defects are seen in patients with cteph. The scans are either performed together or one after the other, but are often referred to as one procedure. Triple matched defects that involved 2550% of a zone showed pe in 12 of 38 32% which was a higher positive predictive value than with smaller or larger triple matched defects, 2 of 46 4% p. Jan 08, 2019 most patients with cteph have very abnormal vq scan findings and often have multiple moderate and large perfusion defects, without matching ventilation defects, in their lungs 23,25. Study 48 nuc116 vq interpretation flashcards from jacquelyn s. For the diagnosis of pe, a vq scan has a reported sensitivity of 77.
In respiratory physiology, the ventilationperfusion ratio v. What is the result of abnormal vq scan if pulmonary. A vq ventilation and quantitative lung scan is a twopart test. The segmental or lobar perfusion defects of acute pulmonary embolic pe disease are classically wedgeshaped. In other words, the clot is preventing blood flow in an area that is being ventilated. The ventilation part of the test looks at the ability of air to reach all parts of the. Ventilationperfusion scan an overview sciencedirect topics.