Background:
The aim of this study is to perform a systematic review of the feasibility
and clinical application of double low-dose CT pulmonary angiography (CTPA) in the diagnosis of
patients with suspected pulmonary embolism.
Discussion:
A total of 13 studies were found to meet selection criteria reporting both low radiation
dose (70 or 80 kVp versus 100 or 120 kVp) and low contrast medium dose CTPA protocols. Lowdose
CTPA resulted in radiation dose reduction from 29.6% to 87.5% in 12 studies (range: 0.4 to
23.5 mSv), while in one study, radiation dose was increased in the dual-energy CT group when
compared to the standard 120 kVp group. CTPA with use of low contrast medium volume (range:
20 to 75 ml) was compared to standard CTPA (range: 50 to 101 ml) in 12 studies with reduction
between 25 and 67%, while in the remaining study, low iodine concentration was used with 23%
dose reduction achieved. Quantitative assessment of image quality (in terms of signal-to-noise ratio
and contrast-to-noise ratio) showed that low-dose CTPA was associated with higher, lower and no
change in image quality in 3, 3 and 6 studies, respectively when compared to the standard CTPA
protocol. The subjective assessment indicated similar image quality in 11 studies between low-dose
and standard CTPA groups, and improved image quality in 1 study with low-dose CTPA.
Conclusion:
This review shows that double low-dose CTPA is feasible in the diagnosis of pulmonary
embolism with significant reductions in both radiation and contrast medium doses, without
compromising diagnostic image quality.
