Pre-operative exclusion of coronary artery stenosis with less than 1mSv dose

Authors: Sebastian Leschka, MD *; Andreas Blaha **
*Institute of Diagnostic Radiology, University Hospital Zurich, Zurich, Switzerland
**Business Unit CT, Siemens Healthcare, Forchheim, Germany
 |  16-12-2009


A 71-year-old male patient with a history of cerebral infarction caused by a high-grade stenosis of the left internal carotid artery and lysis therapy was now referred to the radiology department to rule out coronary artery disease.
In addition to the coronary CT-angiography examination (CTA) a non-enhanced calcium-scoring scan (CaSC) was performed.
The CTA was acquired with a fast pitch spiral technique (Flash Spiral Cardio) while a mean heart rate of 56 bpm was present.


In total, ten calcified lesions could be detected in the CaSc. Diffuse distribution of calcified deposits was observed in the right coronary artery (RCA), the left coronary artery (LAD) and the left circumflex coronary artery (CX). The total Agatston score was 130.
CTA unveiled a normal coronary artery anatomy, right dominant coronary supply type with regular sized lumen of the coronary arteries. RCA and LAD showed no hemodynamic relevant lesions. CX coronary artery unveiled a < 50% stenosis in its proximal segment. A deep myocardial bridging of the LAD could also be depicted.


In combination with the CaSc (0.35 mSv) and the CTA (0.8 mSv), an effective dose of 1.1 mSv was applied to the patient to detect coronary artery disease. The entire acquisition time of the CTA was 280 ms; calcium scoring was acquired in 120 ms.
The Flash spiral cardio method quickly and reliably combines low radiation dose values with the accurate display of the coronary arteries in all segments.

Examination Protocol

Scanner SOMATOM Definition Flash
Scan area Flash Spiral CorCTA
Scan length 130 mm
Scan direction Cranio - Caudal
Scan time 0.28 sec
Tube voltage 100/100
Tube current 320 mAs/rot
Dose modulation CARE Dose
CTDIvol 3.10 mGy
DLP 59
Dosis mSv 0.8 mSv
Rotation time 0.28 s
Pitch 3.4
Slice collimation 128 x 0.6 mm
Slice width 0.75 mm
Spatial Resolution 0.33 mm
Reconstruction increment 0.7
Reconstruction Kernel B26f
Volume 60 ml
Flow Rate 6 ml / sec
Start delay Test Bolus

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 labelling 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.