Stephan Achenbach, MD,

Department of Cardiology, University of Erlangen-Nuremberg, Germany

Andreas Blaha,

Business Unit CT, Siemens Healthcare, Forchheim, Germany

A 70-year-old female patient was referred to the cardiology department because of recurrent episodes of atrial fibrillation accompanied by typical chest pain. Prior to catheter ablation, coronary CT angiography was scheduled to assess pulmonary vein anatomy and to rule out coronary artery stenoses.

During coronary CT angiography, which was performed using a SOMATOM Definition Flash Dual Source CT system, the patient was in sinus rhythm (52/min).

In order to achieve accurate contrast timing, contrast agent transit time was determined using a test bolus approach after injection of 10 ml contrast agent (Ultravist 370), followed by 60 ml of saline solution. Coronary CT angiography was performed in Flash Spiral mode (prospectively ECG-triggered spiral acquisition, 0.28 ms rotation time, pitch 3.2), with a 270 msec scan in cranio-caudal direction, triggered at 55% of the RR interval. 60 ml of contrast agent was followed by 60 ml saline chaser, both injected with 6 ml/sec flow to keep the bolus as compact as possible. CT angiography was able to clearly demonstrate the absence of coronary artery stenoses as well as the absence of calcified and non-calcified plaques. A minor calcified lesion was located at the aortic valve. Anatomy of the left atrium and pulmonary veins was normal. For coronary CT angiography, using the prospectively ECG-triggered spiral Flash spiral mode, the dose length product was 68 mGy/cm, corresponding to an estimated effective dose of 0.95 mSv.

With a fast rotation time of 0.28 seconds and two X-ray tubes, the SOMATOM Definition Flash system allows a new, prospectively ECG–triggered spiral scan mode that uses a very high pitch value. This fast scan mode requires only 270 msec of data acquisition time within one single cardiac cycle and provides a temporal resolution of 75 msec. It therefore allows ultra-low dose, artifact free visualization of the heart and coronary arteries.

Fig 1a+Fig1b: Volume rendered image of the heart, highlighting the coronary arteries as well as the left atrium (LA in red).

Fig 2a: Curved planar reformation in MIP technique shows the entire course of the RCA 

Fig 2b: The “angio like view” in MIP from anterior oblique direction shows the entire coronary tree.

Fig 3a+Fig3b: Curved planar Reformation in MIP technique shows the entire course of the LCX (3a) and the LAD (3b).

The information presented in this case study is for illustration only and is not intended to be relied upon by the reader for instruction as to the practice of medicine. Any health care practitioner reading this information is reminded that they must use their own learning, training and expertise in dealing with their individual patients. This material does not substitute for that duty and is not intended by Siemens Medical Systems to be used for any purpose in that regard.

The drugs and doses mentioned herein are consistent with the approval labeling for uses and/or indications of the drug. The treating physician bears the sole responsibility for the diagnosis and treatment of patients, including drugs and doses prescribed in connection with such use. The Operating Instructions must always be strictly followed when operating the CT System. The source for the technical data is the corresponding data sheets. Results may vary.