V/Q Scan: The Preferred and Recommended Screening Test for CTEPH
“V/Q scan is the preferred and recommended screening test for chronic thromboembolic disease in patients with PH. CTPA [computed tomography pulmonary angiogram] for screening may lead to potential misdiagnosis of PAH and underdiagnosis of CTEPH, including patients with distal disease.”3
- The ventilation/perfusion method (V/Q) uses scintigraphy and medical isotopes to evaluate the circulation of air and blood in the lungs.22
- The ventilation scan detects radioactive gas inhaled by the patient and shows the distribution of ventilation.22
- The perfusion scan detects radioactive albumin (intravenously injected prior to the scan) and shows the distribution of pulmonary perfusion.22
- Both scans are usually performed together during a single visit.22
Left image courtesy of G Heresi-Davila, Cleveland Clinic PTE Program; right image courtesy of the PTE Program at University of California, San Diego
- As the Fifth World Symposium on PH reported in 2013, V/Q scanning is the preferred screening test for CTEPH because it is far more sensitive than CTPA.3
- Tunariu et al reported CTPA sensitivity for detecting CTEPH of 51%.23
- The same authors reported V/Q sensitivity >96%.23
- A normal V/Q scan can rule out CTEPH.23
- An abnormal V/Q scan is suggestive of CTEPH—even when a CT scan is negative.23
- Despite widespread and consistent recommendations that V/Q scanning be used to screen for CTEPH: “Underutilization of V/Q scans in screening PH invites potential misdiagnosis of PAH.”3
- A positive V/Q scan should be followed by further diagnostic studies consistent with the diagnostic algorithm.18
- The V/Q scan is also an important diagnostic test for patients with suspected PH or PE patients who are still symptomatic after 3 months of anticoagulation.6
If a V/Q scan suggests CTEPH3, the patient should be referred to a specialized center with expertise in the treatment of this condition.
View a video that dispels the myth that computerized tomographic pulmonary angiography has become so sophisticated that it can be used as a screen instead of a V/Q scan to rule out CTEPH.
An abnormal V/Q scan is suggestive of CTEPH—even when a CT is negative.
V/Q Scanning and RHC in CTEPH
William R. Auger, MD, of UCSD School of Medicine, discusses the use of V/Q scanning and right heart catheterization in diagnosing chronic thromboembolic pulmonary hypertension, or CTEPH.