VQ Lung Scan Quiz
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Questions and Answers

What is the primary purpose of a VQ lung scan?

  • To measure blood pressure
  • To assess heart size
  • To examine cholesterol levels
  • To diagnose suspected pulmonary embolism (correct)

    • Particles larger than red blood cells can be injected into a peripheral vein for imaging.

    True (A)

    What components make up the VQ lung scan?

    Ventilation (V) and perfusion (Q)

    The particles used in perfusion imaging are called ___ albumin.

    <p>macroaggregated</p> Signup and view all the answers

    What can the VQ scan be used for besides diagnosing pulmonary embolism?

    <p>Quantitation of pulmonary function (B)</p> Signup and view all the answers

    The VQ scan does not provide information about pulmonary blood flow.

    <p>False (B)</p> Signup and view all the answers

    What does Tc-99m stand for in the context of VQ scans?

    <p>Technetium-99m</p> Signup and view all the answers

    After passing through the heart and central pulmonary arteries, the particles lodge in the ___ lung capillaries.

    <p>peripheral</p> Signup and view all the answers

    What does the V in VQ stand for?

    <p>Ventilation (C)</p> Signup and view all the answers

    What scoring system is used for pretest determination of PE probability?

    <p>Modified Wells Scoring System (C)</p> Signup and view all the answers

    Pregnancy is included in the Modified Wells Score.

    <p>False (B)</p> Signup and view all the answers

    What is the total score range for moderate risk in the Modified Wells Scoring System?

    <p>2-6</p> Signup and view all the answers

    A clinical sign of DVT is worth ___ points in the Modified Wells Score.

    <p>3.0</p> Signup and view all the answers

    Match the criteria with their corresponding points in the Modified Wells Scoring System:

    <p>Clinical signs of DVT = 3.0 Previous vascular thromboemboli = 1.5 Hemoptysis = 1.0 Malignancy = 1.0</p> Signup and view all the answers

    What is the percentage risk of PE for patients with a high score (>6) in the Modified Wells Scoring System?

    <p>41% (A)</p> Signup and view all the answers

    Pulmonary angiography is frequently performed today for diagnosing PE due to its low invasiveness.

    <p>False (B)</p> Signup and view all the answers

    What is the minimum score needed to be considered at low risk for PE according to the Modified Wells Scoring System?

    <p>Less than 2</p> Signup and view all the answers

    A heart rate greater than ___ beats per minute is worth 1.5 points in the Modified Wells Score.

    <p>100</p> Signup and view all the answers

    Which of the following is NOT a criterion in the Modified Wells Scoring System?

    <p>Travel history (D)</p> Signup and view all the answers

    Which factors increase the risk of developing a pulmonary embolus (PE)?

    <p>Inactivity and recent surgery (C)</p> Signup and view all the answers

    Chest radiographs are typically the most reliable diagnostic tool for pulmonary embolism.

    <p>False (B)</p> Signup and view all the answers

    What is the relationship between deep vein thrombosis (DVT) and pulmonary embolism (PE)?

    <p>DVT can lead to PE; approximately 30% to 50% of symptomatic DVTs result in PE.</p> Signup and view all the answers

    Serum D-dimer is considered _______ but _______.

    <p>sensitive, nonspecific</p> Signup and view all the answers

    Match the diagnostic tests for pulmonary embolism with their characteristics:

    <p>Serum D-dimer = Sensitive but nonspecific Doppler ultrasound = Non-invasive diagnosis for venous thrombosis Chest radiograph = Identifies other causes, findings are variable CT pulmonary angiography = Visualizes blood flow in the lungs</p> Signup and view all the answers

    What is the primary reason for the difficulty in diagnosing a pulmonary embolus?

    <p>Wide range of presenting signs and symptoms (D)</p> Signup and view all the answers

    Pregnancy is considered to be a moderate risk factor for developing a pulmonary embolism.

    <p>True (A)</p> Signup and view all the answers

    What is the mortality rate for untreated pulmonary embolism?

    <p>Approximately 30%</p> Signup and view all the answers

    The likelihood of a positive test result for PE is influenced by ________ probabilities.

    <p>pretest</p> Signup and view all the answers

    Which of the following statements about PE treatment regimens is true?

    <p>They can potentially expose patients to harm. (B)</p> Signup and view all the answers

    Flashcards

    Pulmonary Embolism (PE)

    A condition where a blood clot travels to the lungs, blocking blood flow.

    Sensitivity (Test)

    The ability of a test to correctly identify a condition when it is present.

    Specificity (Test)

    The ability of a test to correctly identify the absence of a condition.

    Pretest Probability

    The likelihood of a condition before any tests are performed.

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    Bayes' Theorem

    A statistical principle that updates the probability of a condition based on test results.

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    D-dimer Test

    A blood test that measures a protein fragment released when blood clots break down.

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    Doppler Ultrasound

    A type of ultrasound that examines the blood vessels in the legs to identify blood clots.

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    Deep Vein Thrombosis (DVT)

    A condition where a blood clot forms in a vein, often in the legs.

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    Ventilation/Perfusion (V/Q) Scan

    An imaging technique that uses radioactive gas to assess lung function.

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    Thrombolysis

    A procedure that uses a thin tube inserted into a vein to remove blood clots.

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    VQ Lung Scan

    A medical imaging technique that uses radioactive tracers to assess both ventilation (airflow) and perfusion (blood flow) in the lungs.

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    Radiolabeled Particles for Perfusion Imaging

    Radioactive particles slightly larger than red blood cells that are injected into a vein and travel to the lungs, where they lodge in the capillaries, creating a map of blood flow.

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    Radiolabeled Gas or Aerosol for Ventilation Imaging

    Radioactive gases or aerosols inhaled by the patient, used in VQ scans to assess airflow patterns in the lungs.

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    Ventilation

    The process of moving air in and out of the lungs.

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    Perfusion

    The flow of blood through the lungs.

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    Pulmonary Embolism

    A medical condition where blood clots form in the pulmonary arteries, blocking blood flow to the lungs.

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    Gamma Camera Imaging in VQ Scans

    The distribution of ventilation and perfusion in the lungs can be visualized using a gamma camera, which detects the radiation emitted by the radioactive tracers.

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    Quantifying Lung Function with VQ Scans

    VQ scans can help measure lung function before or after lung surgery, such as resection or transplantation.

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    Assessing Corrective Surgery with VQ Scans

    VQ scans can determine if corrective surgery on pulmonary vasculature has been successful.

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    VQ Scans for Pulmonary Embolism Diagnosis

    VQ scans are most commonly used to diagnose suspected pulmonary embolism.

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    Modified Wells Scoring System

    A clinical tool used to assess the likelihood of a pulmonary embolism (PE) based on specific clinical features like history of DVT, recent surgery, heart rate, and other risk factors.

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    Imaging Workup

    This refers to the use of diagnostic imaging tests to determine the severity or extent of a disease or condition. In the context of PE, this could include scans to assess the size and location of any blood clots in the lungs.

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    Pulmonary Angiography

    A traditional imaging technique used to diagnose PE that involves injecting a contrast agent into the blood vessels of the lungs to produce an image of the blood flow.

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    Clinical Risk Assessment

    A general term that refers to the initial evaluation of a patient based on their medical history, current symptoms, and physical examination findings.

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    Previous Vascular Thromboemboli

    A condition where a person has had a previous blood clot or clotting event, which increases their risk of developing another blood clot in the future, including a PE.

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    Malignancy

    A condition where a person has a history of having had a malignancy (cancer), which can also increase the risk of developing blood clots including PEs.

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    Pregnancy

    A condition where a person is pregnant or has recently finished their pregnancy. This can increase the risk of developing blood clots, including PEs.

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    Patient Risk Stratification

    This refers to the process of assessing the overall likelihood of a PE based on a person's medical history, clinical symptoms, and any diagnostic test results. Usually done before ordering further expensive or invasive tests.

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    Study Notes

    Lung Scan

    • Lung scans use radiolabeled particles or gases to visualize pulmonary blood flow and ventilation.
    • Radiolabeled particles are injected intravenously, traveling through the heart and lodging in peripheral lung capillaries.
    • This creates a map of pulmonary blood flow, imaged by a gamma camera.
    • Radiolabeled gases or aerosols allow ventilation imaging.
    • Ventilation (V) and perfusion (Q) scans are used to diagnose suspected pulmonary embolism.
    • VQ lung scans are also used for quantifying pulmonary function, pre or post-lung surgery, and assessing corrective vascular surgeries.

    Pulmonary Embolism Diagnosis

    • Diagnosing pulmonary embolus (PE) is challenging due to diverse symptoms and available diagnostic tests.
    • Prompt diagnosis and treatment are vital to reduce mortality risk.
    • Pretest probabilities are important for test accuracy according to Bayes' theorem.
    • Patient risk stratification (e.g., Modified Wells Scoring System) is crucial before extensive testing.
    • Risk factors for PE include immobilization, recent surgeries, hypercoagulable states, prior PE, and deep vein thrombosis (DVT).
    • 30% to 50% of symptomatic DVT cases result in PE.
    • Pregnancy and hormonal use are moderate risk factors.
    • Chest X-rays can identify other causes but display highly variable PE findings.
    • Serum D-dimer tests are sensitive but non-specific.
    • Doppler ultrasound is useful for non-invasive DVT diagnosis.
    • Pulmonary angiography, a previous gold standard, is rarely used today. It's invasive and requires significant resources, potentially failing to visualize smaller clots.

    Imaging Techniques

    • Multislice computed tomography pulmonary angiography (CTPA) is the dominant imaging modality for PE diagnosis.
    • Magnetic resonance angiography (MRA) visualizes pulmonary vasculature without ionizing radiation.
    • Nuclear medicine VQ lung scans are valuable in patients unable to tolerate IV contrast, with renal dysfunction, or lacking adequate CT/MRA results.
    • VQ scans efficiently provide definitive results while minimizing patient radiation exposure.
    • Ventilation and perfusion components are important for interpretation, requiring understanding of lung anatomy and physiology.
    • Advanced techniques like SPECT or SPECT/CT are reported to improve VQ accuracy.
    • Modern ventilation agents include Tc-99m DTPA and Tc-99m Technegas.
    • Tc-99m MAA is the most commonly used perfusion agent.
    • Ventilation studies usually precede perfusion studies due to limitations in their visualization overlap.

    Ventilation and Perfusion Defects

    • Ventilation defects involve airway problems, while perfusion defects concern blood flow.
    • Causes of abnormal ventilation include lung disease (emphysema, interstitial lung disease, asthma) and various other conditions.
    • Mismatched defects suggest PE, while matched defects point to other conditions, frequently being seen in airway diseases.
    • Radiopharmaceutical differences impact VQ scan findings and interpretations.
    • Xe-133 is a gas agent, whereas Tc-99m DTPA is an aerosol agent and Tc-99m Technegas are different types of solid carbon particles.
    • Consideration for patient factors like age, weight, pregnancy, pulmonary hypertension, and right-to-left cardiac shunts are important for VQ scan analysis.
    • Specific image findings may indicate more significant conditions than a PE, like right-to-left cardiac shunts or severe unilateral lung involvement.

    Normal and Abnormal Findings

    • Normal VQ scans have a homogeneous distribution of radioactivity.
    • Abnormal VQ scans can display mismatched or matched defects varying in shape, size, and intensity. Mismatched defects may suggest PE.
    • Nonsegmental defects may be caused by extrapulmonary structures like enlarged heart, pleural effusion, or metal artifacts.

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    Lung Scan PDF

    Description

    Test your knowledge about the VQ lung scan, its purpose, components, and applications in diagnosing pulmonary issues. This quiz covers key concepts such as the Modified Wells Scoring System and the technical elements involved in VQ imaging. Perfect for healthcare professionals and students in medical courses!

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