Published in:
01-03-2014 | Cardiac
Dose reduction in dynamic CT stress myocardial perfusion imaging: comparison of 80-kV/370-mAs and 100-kV/300-mAs protocols
Published in: European Radiology | Issue 3/2014
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Objectives
To determine the effect of reduced 80-kV tube voltage with increased 370-mAs tube current on radiation dose, image quality and estimated myocardial blood flow (MBF) of dynamic CT stress myocardial perfusion imaging (CTP) in patients with a normal body mass index (BMI) compared with a 100-kV and 300-mAs protocol.
Methods
Thirty patients with a normal BMI (<25 kg/m2) with known or suspected coronary artery disease underwent adenosine-stress dual-source dynamic CTP. Patients were randomised to 80-kV/370-mAs (n = 15) or 100-kV/300-mAs (n = 15) imaging. Maximal enhancement and noise of the left ventricular (LV) cavity, contrast-to-noise ratio (CNR) and MBF of the two groups were compared.
Results
Imaging with 80-kV/370-mAs instead of 100-kV/300-mAs was associated with 40 % lower radiation dose (mean dose–length product, 359 ± 66 vs 628 ± 112 mGy⋅cm; P < 0.001 ) with no significant difference in CNR (34.5 ± 13.4 vs 33.5 ± 10.4; P = 0.81) or MBF in non-ischaemic myocardium (0.95 ± 0.20 vs 0.99 ± 0.25 ml/min/g; P = 0.66). Studies obtained using 80-kV/370-mAs were associated with 30.9 % higher maximal enhancement (804 ± 204 vs 614 ± 115 HU; P < 0.005), and 31.2 % greater noise (22.7 ± 3.5 vs 17.4 ± 2.6; P < 0.001).
Conclusions
Dynamic CTP using 80-kV/370-mA instead of 100-kV/300-mAs allowed 40 % dose reduction without compromising image quality or MBF. Tube voltage of 80-kV should be considered for individuals with a normal BMI.
Key Points
• CT stress perfusion imaging (CTP) is increasingly used to assess myocardial function.
• Dynamic CTP is feasible at 80-kV in patients with normal BMI.
• An 80-kV/370-mAs protocol allows 40 % dose reduction compared with 100-kV/300-mAs.
• Contrast-to-noise ratio and myocardial blood flow of the two protocols were comparable.