Prospective Randomized Trial On RadiaTion Dose Estimates Of CT AngIOgraphy In PatieNts Scanned With A Sequential Scan Protocol (PROTECTION-III)

Prospective Randomized Trial On RadiaTion Dose Estimates Of CT AngIOgraphy In PatieNts Scanned With A Sequential Scan Protocol

Prospective Randomized Trial On RadiaTion Dose Estimates Of CT AngIOgraphy In PatieNts Scanned With A Sequential Scan Protocol

The objective of this study is to compare radiation dose of a standard spiral scan with the a new sequential scan protocol. We hypothesize that the sequential scan protocol is associated with a reduction in dose estimates of at least 20%, while the diagnostic image quality is not inferior. Secondary endpoints of the study include quantitative image quality parameters, diagnostic accuracy for spiral versus sequential studies compared to invasive angiography in patients who underwent subsequent invasive coronary angiography.

All patients scheduled for a coronary CT scan are screened for inclusion and exclusion criteria. Patients are included if they have stable sinus rhythm (heart rate <75 bpm for dual source CT and <65 bpm for 64-slice CT). Informed signed consent is obtained from these patients and the CT scan is prepared. After topogram scan and the native scan for Ca-Scoring, patients are randomized in two groups with the use of sealed envelopes. After that contrast-enhanced coronary CT angiography is performed with the standard spiral protocol or with the sequential protocol. The CT examination is evaluated by two experienced investigators on a per-vessel basis and all results and study-related data are collected in a dedicated database. For assessment of image quality, a previously established 4-point score system is used and quantitative image quality parameters are measured. A 30 day follow-up after the CT examination aims to evaluate if patients underwent invasive coronary angiography or were scheduled for a myocardial stress / perfusion test (such as stress-echocardiography, myocardial scintigraphy or stress perfusion imaging by MRI).

Compared with a helical scan protocol the use of a sequential scan protocol is associated with a comparable diagnostic image quality, while the radiation dose estimates are significantly reduced.

impact of the sequential scan protocol on quantitative image quality parameters, e.g. image noise, signal and contrast intensity, signal- and contrast-to-noise-ratios

diagnostic accuracy (sensitivity, specificity as well as positive and negative predictive values) for studies scanned with helical vs. sequential scan protocol when compared with invasive coronary angiography on a per-vessel based analysis

frequency of non-diagnostic CTA studies when comparing studies scanned with the helical vs. the sequential scan protocol

Inclusion Criteria: patients with an indication for a coronary CT angiography (planned evaluation of the coronary arteries) stable sinus rhythm heart rate < 75 bpm with dual-source CT or < 65 bpm with single-source CT signed informed consent Exclusion Criteria: non-ECG triggered studies non-coronary CTA studies, e.g. bypass graft CTAs, pre- or post EP studies, CABG planning studies

Hausleiter J, Meyer TS, Martuscelli E, Spagnolo P, Yamamoto H, Carrascosa P, Anger T, Lehmkuhl L, Alkadhi H, Martinoff S, Hadamitzky M, Hein F, Bischoff B, Kuse M, Schomig A, Achenbach S. Image quality and radiation exposure with prospectively ECG-triggered axial scanning for coronary CT angiography: the multicenter, multivendor, randomized PROTECTION-III study. JACC Cardiovasc Imaging. 2012 May;5(5):484-93. doi: 10.1016/j.jcmg.2011.12.017.