Image quality and diagnostic accuracy of 16-slice multidetector computed tomography for the detection of coronary artery disease in obese patients

Background: Cardiac multislice spiral computed tomography ( MSCT) scanners permit visualization of the coronary arteries with an overall good sensitivity ( sens) and specificity ( spec). However, in obese patients ( pts), who are at higher risk to develop coronary artery disease ( CAD), image quality of MSCT is supposed to be limited. At present, there are no data whether the accuracy of MSCT depends on the body mass index ( BMI). Thus, we compared the catheter-controlled MSCT results from normal weight and obese pts in a cohort of 117 pts with regard to sens, spec, positive predictive value ( PPV), negative predictive value ( NPV) and image quality. Methods and material: In all, 21 normal weight pts ( group I: BMI < 25, 64.6 +/- 11.1 years, number of risk factors 2.1 +/- 1.1), 60 pts with mild overweight ( group II: BMI 25-30, 64.6 +/- 8.9 years, number of risk factors 3.4 +/- 1.0) and 36 obese pts ( group III: BMI > 30, 63.0 +/- 8.5 years, number of risk factors 3.4 +/- 0.9) were examined by MSCT ( Sensation 16 Speed 4 D (R), Siemens, Germany, gantry rotation time 375 ms) and invasive coronary angiography. MSCT results were compared blinded to the results of the coronary angiography with regard to the presence or absence of a significant stenosis ( > 50%) in a modified AHA 13 segment ( sgt) model. Image quality was assessed on a qualitative scale between 1 ( very good) and 5 ( insufficient image quality) for each sgt. Results: Sens, spec, PPV and NPV were statistically not different in all three groups ( I: 0.88/0.97/0.91/0.96, II: 0.83/0.97/0.88/0.95, III: 0.87/0.99/0.96/0.96). 3 pts ( group I 1, group II 2) had to be excluded from analysis due to technical problems. Group I had significantly less risk factors ( P < 0.001) and image quality was significantly better than in group II and III ( P < 0.05). Group II and III did not differ with regard to risk factors or image quality. Conclusions: Overweight and obesity have an impact on MSCT image quality but did not hamper the diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out CAD also in pts with higher BMI. These retrospective data have to be confirmed in larger prospective trials.