ventilation-perfusion (VQ) scan
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Introduction
Assessment of ventilation-perfusion (VQ) mismatch.
Indications
- chronic thromboembolic pulmonary hypertension (CTEPH)
- method of choice
- assessment of pulmonary embolism
- pulmonary angiography is generally method of choice
Clinical significance
- initial diagnostic modality in the evaluation of chronic thromboembolic pulmonary hypertension (CTEPH)[4]
- alternate diagnostic modality in the evaluation of pulmonary emboli
- initial diagnostic test in pregnant women
- preferred method in patients with risk of acute kidney injury
- preexisting kidney disease (chronic renal failure)
- diabetes mellitus
- hypovolemia
- free urinary light chains of multiple myeloma[1]
- pulmonary CT angiography is the preferred method in patients with intermediate to high-probability PE[1]
- ventilation in the absence of perfusion suggests pulmonary emboli
- two or more segmental defects on perfusion scan suggest large vessel chronic thromboembolic disease or pulmonary hypertension
- however, defects on perfusion scan are non-specific & may be seen in COPD
- pulmonary angiography is indicated to resolve equivocal findings on VQ scan.
Sensitivity: 77%, specificity 98%[3]
VQ scans underestimate severity of central pulmonary arterial obstruction.[2]
More general terms
References
- ↑ Jump up to: 1.0 1.1 1.2 Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 18. American College of Physicians, Philadelphia 1998, 2012, 2018
- ↑ Jump up to: 2.0 2.1 Smith R., Jewish Home for the Aging, Reseda CA, 2001, unpublished
- ↑ Jump up to: 3.0 3.1 Sostman HD et al, Acute pulmonary embolism: Sensitivity and specificity of ventilation-perfusion scintigraphy in PIOPED II study. Radiology 2008, 246:941 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18195380
- ↑ Jump up to: 4.0 4.1 Salaun P-Y et al. Noninvasive diagnosis of pulmonary embolism. Chest 2011 Jun; 139:1294 PMID: https://www.ncbi.nlm.nih.gov/pubmed/20724733