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IMAGE INTERPRETATION · LUNG V/Q IMAGING

High-Probability V/Q Scan: Mismatched Defects

Ventilation-perfusion (V/Q) lung scan — 58-year-old male
Ventilation-perfusion (V/Q) lung scan — 58-year-old male

CC BY-SA 4.0 · Hellerhoff / Wikimedia Commons · source file

Question

This V/Q scan shows normal ventilation with multiple segmental/lobar perfusion defects (a 'mismatch' pattern). According to the PIOPED II criteria, this pattern is interpreted as:

  1. ALow probability for pulmonary embolism
  2. BIntermediate (indeterminate) probability for pulmonary embolism
  3. CHigh probability for pulmonary embolism
  4. DNormal — no evidence of pulmonary embolism
Show the answer and explanation

C. High probability for pulmonary embolism

A V/Q mismatch — normal ventilation with absent or significantly reduced perfusion in a segmental distribution — is a HIGH probability pattern for pulmonary embolism (PE) by PIOPED II criteria. PE causes vascular obstruction that reduces perfusion to ventilated lung segments. A 'matched' defect (both ventilation and perfusion reduced) is more typical of COPD/airway disease (low or intermediate probability). High probability V/Q combined with high clinical suspicion warrants anticoagulation without further imaging.

More lung v/q imaging images

Ventilation/perfusion (V/Q) lung scan — multiple projectionsMatched V/Q Defects: Low Probability for PE Lung perfusion scintigraphy — normal study (standard projections)Normal Lung Perfusion Scan and Pulmonary Embolism Lung perfusion scintigraphy — multiple viewsHow Tc-99m MAA Lung Perfusion Imaging Works V/Q lung scan showing ventilation-perfusion mismatchReducing MAA Particles in Pulmonary Hypertension Lung perfusion scintigraphy — multiple projectionsStripe Sign on a Lung Perfusion Scan V/Q lung scan — matched ventilation and perfusion defectsV/Q Scan in COPD: Matched Defects
← Lung Perfusion Projections: Why Lateral Views MatterMatched V/Q Defects: Low Probability for PE →

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