Image quality of low-dose CCTA in obese patients: impact of high-definition computed tomography and adaptive statistical iterative reconstruction

Gebhard, Cathérine ; Fuchs, Tobias ; Fiechter, Michael ; Stehli, Julia ; Stähli, Barbara ; Gaemperli, Oliver ; Kaufmann, Philipp

In: The International Journal of Cardiovascular Imaging, 2013, vol. 29, no. 7, p. 1565-1574

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    Summary
    The accuracy of coronary computed tomography angiography (CCTA) in obese persons is compromised by increased image noise. We investigated CCTA image quality acquired on a high-definition 64-slice CT scanner using modern adaptive statistical iterative reconstruction (ASIR). Seventy overweight and obese patients (24 males; mean age 57years, mean body mass index 33kg/m2) were studied with clinically-indicated contrast enhanced CCTA. Thirty-five patients underwent a standard definition protocol with filtered backprojection reconstruction (SD-FBP) while 35 patients matched for gender, age, body mass index and coronary artery calcifications underwent a novel high definition protocol with ASIR (HD-ASIR). Segment by segment image quality was assessed using a four-point scale (1=excellent, 2=good, 3=moderate, 4=non-diagnostic) and revealed better scores for HD-ASIR compared to SD-FBP (1.5±0.43 vs. 1.8±0.48; p<0.05). The smallest detectable vessel diameter was also improved, 1.0±0.5mm for HD-ASIR as compared to 1.4±0.4mm for SD-FBP (p<0.001). Average vessel attenuation was higher for HD-ASIR (388.3±109.6 versus 350.6±90.3 Hounsfield Units, HU; p<0.05), while image noise, signal-to-noise ratio and contrast-to noise ratio did not differ significantly between reconstruction protocols (p=NS). The estimated effective radiation doses were similar, 2.3±0.1 and 2.5±0.1mSv (HD-ASIR vs. SD-ASIR respectively). Compared to a standard definition backprojection protocol (SD-FBP), a newer high definition scan protocol in combination with ASIR (HD-ASIR) incrementally improved image quality and visualization of distal coronary artery segments in overweight and obese individuals, without increasing image noise and radiation dose