Low-dose, prospective triggered high-pitch spiral coronary computed tomography angiography: comparison with retrospective spiral technique.

RATIONALE AND OBJECTIVES: Cardiac computed tomographic angiography algorithms emphasize radiation reduction while maintaining diagnostic image quality (IQ). The aim of this study was to evaluate IQ and interreader variability using prospective electrocardiographically triggered high-pitch spiral cardiac computed tomographic angiography (FLASH-CT) compared to retrospective electrocardiographic gating (RETRO-CT) for coronary artery disease evaluation in a patient population including overweight and obese individuals.

MATERIALS AND METHODS: Seventy patients (24 women; mean age, 60 years) matched for gender, age, body mass index (27.4 ± 5.5 kg/m(2)), and calcium score (184 ± 328) underwent cardiac computed tomographic angiography, 35 with FLASH-CT (Definition Flash) and 35 with RETRO-CT (Somatom Definition). Images were reconstructed using standard protocols and least motion phase for RETRO-CT acquisitions. Two independent, blinded readers evaluated the coronary arteries using an 18-segment model, grading IQ on a 5-point, Likert-type scale and coronary stenosis on a 5-point semiquantitative and binary scale.

RESULTS: Effective radiation dose (1.50 vs 17.3 mSv, P < .0001) and mean heart rate (58 vs 62 beats/min, P < .05) were significantly lower for FLASH-CT compared to RETRO-CT. Seven hundred forty segments (> 1.5 mm) were evaluated. There was no significant difference between FLASH-CT and RETRO-CT scans in overall per-segment IQ (3.11 ± 0.75 vs 3.10 ± 0.82, P = .94). FLASH-CT had noninferior IQ relative to RETRO-CT (95% confidence interval, -0.25 to 0.26). There was no significant difference in interreader variability in diagnosis between FLASH-CT and RETRO-CT for all coronary segments (77.5% vs 78.2%, P = .83).

CONCLUSIONS: FLASH-CT is an acceptable coronary computed tomographic angiographic method for reducing radiation dose without compromising IQ for a patient population including overweight and obese individuals.