IS Case 124: High Probability of Pulmonary Embolism

Nate Johnson, MD

Imaging Sciences URMC 2008
Publication Date: 2009-05-20


Patient is a 54-year-old female with acute, chronic shortness of breath.


Multiple segmental, peripheral, non-matched perfusion defects without matching ventilation defects.


High Probability of Pulmonary Embolism


Multiple systems exist to evaluate for probability of pulmonary embolism. The most widely used is the PIOPED criteria. Based on PIOPED criteria our patient falls into the high probability of pulmonary embolism category. There are greater than two large perfusion segment defects without corresponding abnormality on the ventilation images.

Amended PIOPED Criteria: High: Greater than or equal to two mismatched perfusion segments without ventilation or CXR abnormalities. Can be fulfilled by:

  1. Four moderate segmental defects;
  2. One large and two moderate defects;
  3. Two large defects.


  1. Findings not consistent with high or low probability;
  2. Triple match defect in lower lung zones;
  3. One moderate, but less than two large mismatched segments without ventilation or CXR abnormality;
  4. Corresponding V/Q defect and small pleural effusion;
  5. One moderate matched V/Q defect with a normal CXR.


  1. Nonsegmental perfusion defect;
  2. Greater than three small perfusion defects but normal CXR;
  3. Stripe sign;
  4. Perfusion defect with larger corresponding CXR abnormality;
  5. V/Q defect with corresponding pleural effusion;
  6. Triple match defect of middle or upper lung zones;
  7. Matched V/Q defects with normal CXR.

Very Low: Less than three small perfusion defects with normal CXR.

Normal: No defects on perfusion scan.


  1. PIOPED Investigators. Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). JAMA. 1990 May 23-30;263(20):2753-9. [PMID: 2332918]
  2. Gottschalk A, Stein PD, Goodman LR, Sostman HD. Overview of Prospective Investigation of Pulmonary Embolism Diagnosis II. Semin Nucl Med. 2002 Jul;32(3):173-82. [PMID: 12105798]

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