And it’s not as though we needed more research to prove that V/Q was a better initial strategy than CT, but this paper just came out in The Journal of Nuclear Medicine:
Results: A total of 81 simultaneous studies were available for analysis, of which 38% were from patients with PE. V/Q SPECT had a sensitivity of 97% and a specificity of 88%. When low-dose CT was added, the sensitivity was still 97% and the specificity increased to 100%. Perfusion SPECT with low-dose CT had a sensitivity of 93% and a specificity of 51%. MDCT angiography alone had a sensitivity of 68% and a specificity of 100%. Conclusion: We conclude that V/Q SPECT in combination with low-dose CT without contrast enhancement has an excellent diagnostic performance and should therefore probably be considered first-line imaging in the work-up of PE in most cases.
This is a little complicated. The key points are that V/Q scanning is more sensitive (much more sensitive) than CTA. That had already been established in the POIPED trials. Although V/Q scanning is moderately less specific than CTA, when combined with non-contrast low dose CT the specificity improved to 100%.
I don’t think it has ever been systematically studied but I strongly suspect there has been a spike in contrast-induced renal failure in hospitalized patients due to this non-evidence based trend.
Medscape commentary here.