Keywords:
Image verification, Diagnostic procedure, Ultrasound, Elastography, CT, Lung
Authors:
R. Kubale1, H. Wilkens2, J. Stroeder2, R. Seidel2, A. Bücker3; 1Pirmasens/DE, 2Homburg/DE, 3Homburg a.d. Saar/DE
DOI:
10.1594/ecr2013/C-1684
Methods and Materials
Method:
Normally the speed of sound is characterized by compressibility of the medium (Longitudinal waves).
In the case of transversal waves (Shear waves) elasticity is the main component and helps to quantify the stiffness of tissues (Fig.
1).
Shear wave imaging uses a push pulse and several tracking pulses to achieve an image (Fig.
2).
The results are displayed as maps (Fig.
3):
– Shear wave velocity map: Time to peak,
velocity estimates (m/sec)
– Shear wave quality map: Signal to noise level,
displacement magnitude
– Shear wave travel time: Inverse of velocity (fast to slow)
– Displacement map: High in soft tissue and low in stiff tissue (dark blue)
Material and Patients:
25 patients with normal lung parenchyma and 20 patients with subpleural fibrotic changes proved by x-ray and/or CT were correlated with the results of shear wave imaging (S3000 Siemens).
The displacement maps are compared with chest X-ray and CT.
Modifications and analysis of factors
–Frequency and angle of insonation
–Compression of scan head
–Size of ROI and frequency