First Head-to-Head Comparison of Effective Radiation Dose from Low-Dose 64-Slice CT with Prospective ECG-Triggering versus Invasive Coronary Angiography

OBJECTIVES: To compare effective radiation dose of low-dose 64-slice CTCA using prospective ECG-triggering versus diagnostic invasive coronary angiography (CA). Background: Reduction of radiation burden of multidetector computed tomography coronary angiography (CTCA) has remained an important task.

METHODS: 42 patients referred for elective invasive CA owing to suspected coronary artery disease (CAD) were prospectively enrolled to undergo a low-dose CTCA without calcium scoring within the same day before CA. Dose-area product of diagnostic invasive CA and dose-length product of CTCA were measured, converted into effective radiation dose and compared using Mann-Whitney U tests. In addition, accuracy of CTCA to detect CAD (coronary artery narrowing >50%) was assessed using invasive CA as standard of reference. On an intention-to-diagnose basis all non-evaluative vessels were included in the analysis and censored as positive.

RESTULTS: The estimated mean effective radiation dose was 8.5 (4.4) mSv (range 1.4–20.5 mSv) for diagnostic invasive CA, and 2.1 (0.7) mSv (range 1.0–3.3 mSv) for CTCA (p<0.001). 19 patients (42.9%) had no CAD by invasive CA. 40 (95.2%) patients have been correctly classified as having CAD (23/23) or no CAD (17/19). Over 97% (551/567) of segments were evaluable. Vessel-based analysis revealed sensitivity, specificity, positive and negative predictive value of 94.2% (CI 0.8% to 1.0%), 94.8% (CI 09% to 1.0%), 89.0% (CI 0.8% to 1.0%), 97.4% (CI 09% to 1.0%) and an accuracy of 94.6%.

CONCLUSIONS: Low dose CTCA allows evaluation of CAD with high accuracy, but delivers a significantly less effective radiation dose to patients compared to diagnostic invasive CA.  

PMID: 19581273

Posted in Computed Tomography and tagged , , .


  1. Interesting paper comparing effective radiation dose between invasive coronary angiography and coronary CTA performed using prospective ECG-triggered technique. Radiation doses were actually higher and more variable using conventional catheterization than with CT.

  2. Study included 42 prospectively enrolled patients. The mean effective dose was significantly higher in invasive angiography than in CTCA in all analyzed patients. Additionally, the authors showed that even after stratifying patients for BMI, the variability of the effective dose from CTCA was negligible while it remained high for invasive angiography.

    Image quality was diagnostic in up to 97.18% of the analyzed segments on CTCA.

  3. See also:
    Radiation dose and image quality of prospective triggering with dual-source cardiac computed tomography.
    Blankstein R, Shah A, Pale R, Abbara S, Bezerra H, Bolen M, Mamuya WS, Hoffmann U, Brady TJ, Cury RC.
    Am J Cardiol. 2009 Apr 15;103(8):1168-73. Epub 2009 Mar 4.

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