Three Dimensional Ultrasound Imaging

Transcription

1 Three Dimensional Ultrasound Imaging Hans Torp/ Sevald Berg/Kjell Kristoffersen m/flere Department of circulation and medical imaging NTNU Hans Torp NTNU, Norway Acquisition Reconstruction Filtering Collecting ultrasound data Motor devices (paper B, C, E) Postition locator systems (paper( F) 2D-arrays Important factors Accuracy Callibration Temporal and spatial resolution Cardiac gating Visualization Analysis Page 1

2 Acquisition Reconstruction Build 3D data volumes: Cardiac gating Reorganizing data Temporal and spatial resolution Scan conversion Interpolation Filtering Visualization Analysis Acquisition Reconstruction Reduce image noise Spatial and temporal filtering Strong filtering common for 3D ultrasound visualization Filtering Visualization Analysis Page 2

3 Acquisition Reconstruction Filtering Visualization 3D object model Slicing Surface rendering Analysis Volume rendering Acquisition Reconstruction Quantification of physiological parameters Volume estimation Estimation of regurgitation jet volume Blood volume flow estimation Filtering Visualization Analysis Page 3

4 J Appl Physiol, vol 9, 1956 D. H. Howry et al, 1956 G. Baum et al, 1961 Page 4

5 J. F. Brinkley et al, 1982 AM J Obstet Gynecol, vol 144, 1982 J. Roelandt et al, 1994 Thoraxcentre Journal, vol 6, 1994 Page 5

6 Transvaginal 3D probe Specially designed 3D probe 7.5 MHz annular array transducer Raw digital ultrasound data No externally moving parts Tilted scanning angle Tilted scanning angle Page 6

7 Rotating Probe 3D Transvaginal ultralyd - Nasjonalt senter for Fostermedisin - IFBT, IDI, NTNU - GE Vingmed Ultrasound Technology EagleEye TM Symmetrically Focusing Array High density of central elements for high resolution near imaging Larger outer elements for high resolution far imaging The eagle has similar high density of retina neurons for sharp focusing on central objects simultaneous with large field of view Page 7

8 Technology OwlVision TM 3D visualization software Crown-rump length 7.5 mm 6 weeks 6 days Technology OwlVision TM 3D visualization software 8 0 weeks CRL 14.5 mm Page 8

9 Kretz Ultrasound Curved array tilted by stepper motor Free-hand probe for 3D Magnetic position sensor mounted on probe Position data loaded directly into scanner Digital ultrasound and position data transferred to external PC for post processing Page 9

10 Dynamic 3D data acquisition Page 10

11 Freehand tilting Probe slowly tilted during cardiac cycles Held end-expiration Choosing best acoustic window possible Sevald Berg NTNU, Norway Mitral valve surface Page 11

12 2D matrix array electronic steering of beam elements in a 1D array 32* *96 elements in a 2D array elements Cable Electronics Beamformer Azimuth Elevation The Cardiac 3D Challenge From 1D Array to 2D Array array elements array elements Main Challenges Large element count Tiny element size high electrical impedance Page 12

13 Transducer Thinning Sparse 50 x 50 element transducer Every second element used for transmitter, totally 253: 256 elements for receiver, x, found by genetic optimization: no overlap with transmitter elements to simplify system electronics optimizes beamwidth and sidelobes of ultrasound beam different layouts to search, (only electrons in the universe!) Joint work with IBMT/Fraunhofer Institut Periodic array (Lockwood et al) 221 Tx, 489 Rx, 57 overlap Simulations: A. Austeng Page 13

14 The cardiac 3D challenge 2D Matrix Array ~ 2000 elements Beamformer Electronics ~ 15 cm 256 System Channels Probe Technology Challenges Matrix Transducer Advanced Interconnect Low-power Micro Electronics Thermal Management Probe Assembly Architecture System Technology Challenges 2x Data Acquisition 10x Data Processing in Display ECG Stitching of Sub-Volumes... for Large-Volume Acquisition Application Software Solved Using Data-reducing Electronics in the Probe Handle 3D Ultralydprobe high tech 2000 Transducer Elements 7 Boards, 35 ASICs 256 System Channels Page 14

15 4D Scanning and Processing Slicing Volume rendering Navigator 3D Beamforming 3D vector processing 3D scan conversion 3D Rendering 2D display All steps in Real Time Real time 3D Volume Imaging Standard setup Increased elevation width No ECG gating Volume rendering / orthogonal slicing Volume size: ~20 x 80º / ~35 x 45º Volume rate: Page 15

16 ECG-gated Data Acquisition Full Volume (ECG gated acquisition) Typically acquired in 4 beats Page 16

17 4D LV Volumes Chamber quantification based on deformable model (TomTec( TomTec) Ejection Fraction Regional Wall Motion Navigation & Viewing 9 Slice Nine equidistant slices Wall motion assessment Page 17

18 4D Color Imaging (ECG Gated) Gated from 7 heart beats High frame rates (17-35 frames / second) High Color sensitivity High Color resolution Color 6 Slice View Parallel slices easily identify vena contracta Planimetry provided Page 18

19 Bi-plane Imaging Parasternal imaging Tilt of elevation plane Tri-plane Imaging Apical Imaging: Three simultaneously recorded images All color modes supported Page 19

20 Sanntid 3D ultralyd - foster Page 20