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Utilizing ultra-low-dose of 0.05 mSv for premature baby with congenital heart disease

Author: Authors: Jean-Francois Paul, MD* and Andreas Blaha**
*Centre Chirurgical Marie Lannelongue / Le Plessis-Robinson, France
**Business Unit CT, Siemens Healthcare, Forchheim, Germany

History

A premature baby was referred to the radiology department with diagnosis of congenital heart disease. An atrial and left ventricular septum defect could be detected with echocardiography but with a doubt about the exact origin and course of right pulmonary artery.
Therefore a low-dose CT examination was requested, utilizing low kilovoltage (kV) and low milliampere seconds (mAs) to achieve ultra-low-dose radiation values.
The CTA was acquired with a fast pitch spiral technique (Flash Spiral Cardio) while a mean heart rate of 56 bpm was present.


Diagnosis
A mild stenosis present at the ostium of the right pulmonary artery (RPA) could be observed. Although the RPA showed an irregularity it had a normal anatomical course. The ventricular septum defect as well as the still open atrial septum could be clearly revealed by using oblique planar reformations. The right coronary artery was well depicted despite a heart rate of 157 bpm.


Comments
The data acquisition was performed with a SOMATOM Definition Flash using the ECG triggered sequential mode (Flash Cardio Sequence) which resulted in an ultra-low-dose value of 0.05 mSv. Calculated with the dose length product (DLP) of 1, an estimated dose of 0.05 mSv (50 micro Sv) could be achieved.
Using the Definition Flash low-dose acquisition technique it was possible to detect this congenital heart disease (CHD) in a very early stage of the patients life.

Ventricular septal defect in VRT technique (arrowheads), Foramen ovale (PFO, arrows)
Ventricular septal defect in MIP technique (caudo-cranial view, arrow); PFO (arrowhead)
caudo cranial view MIP, mild stenosis and irregularity of the RPA (arrow)
cranio caudal view VRT
Fused VRT and MIP highlighting RPA (arrow)

Examination Protocol

Scanner SOMATOM Definition Flash
Scan mode Flash Cardio Sequence
Scan area Thorax
Scan length 33 mm
Scan direction Cranio - Caudal
Scan time 1 sec
Tube voltage 80 kV / 80 kV
Tube current 22 mAs/rot
Rotation time 0.28 s
Slice collimation 128 x 0.6 mm
Slice width 0.75 mm
Reconstruction increment 0.4 mm
Spatial Resolution 0.33 mm
Reconstruction Kernel B26f
Pitch 3.4
CTDIvol 0.078 mGy
DLP 1 mGy/cm
Effectiv Dose 0.05 mSv
Postprocessing CT Cardiac Engine

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.

Date: Feb 16, 2010


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