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

    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</p> Signup and view all the answers

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

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

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

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

    Pregnancy is included in the Modified Wells Score.

    <p>False</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%</p> Signup and view all the answers

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

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

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

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

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

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

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

    <p>True</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.</p> Signup and view all the answers

    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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    Related Documents

    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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