SHA24/015004

How to use Tissue Doppler and Strain Imaging in Clinical daily practice Abdulhalim J Kinsara Ass professor Head of cardiology King Saud Bin Abdulaziz university, COM King Abdulaziz medical city, king faisal cardiac center 1

why New imaging technologies provide a unique window into myocardial mechanics helping to better understand the pathophysiologic mechanisms of cardiovascular disease

2

Myocardial Strain • Strain – deformation of myocardial fibers produced by applying a mechanical or electrical force , measured in % change • Deformation a change in lengthening or shortening in relation to original length – Negative strain myocardial fibers shorten or compress in relation to original length – Positive Strain myocardial fibers lengthen or stretch in relation to original length 3

Strain is a dimensionless index of change in length Strain ( % ) = (L - L0)/ L0 L L0

4

• For 2-D or 3-D deformations, the concept of strain becomes more complex since shear strains add changes that might not occur in any of the coordinate directions.

Therefore, new approaches have been developed in order to assess the 2D motion and deformation based on speckle tracking.

5

• this speckle pattern characterises the underlying myocardial tissue acoustically and is assumed to be unique for each myocardial segment-serve as a fingerprint of the myocardial segment. •

Tracking of the acoustic pattern during the cardiac cycle allows to follow the motion and the deformation of this myocardial segment.

6

Complex Motion of Myocardial Fibers

7

Three Main Types of Strain • Longitudinal strain – systolic myocardial shortening from base to apex (negative strain) • Track subendocardial fibers • More longitudinal strain at base than apex

8

Longitudinal Strain

The Prince Charles Hospital

GMS2012

Three Main Types of Strain • Circumferential strain – reflecting intramural circumferential shortening (negative strain) • Most stable – mid wall • Short axis Septum and posterior highest

10

Circumferential Strain

The Prince Charles Hospital

GMS2012

Three Main Types of Strain • Radial strain – %thickening of the heart muscle toward the center from the endocardium to epicardium (transmural) positive strain • Can identify dyssynchrony • Least stable curve • Compare to average thickening values by MRI • Short axis view 12

Transverse / Radial Strain

The Prince Charles Hospital

GMS2012

Transverse

The Prince Charles Hospital

GMS2012

Transverse / Radial Strain

The Prince Charles Hospital

GMS2012

Strain Calculation • End – diastole (LV short axis)

10mm

• End – systole (LV short axis)

14mm

Strain calculates % thickening or shortening Strain = 14 – 10/10 = 40% Ending thickness - starting thickness / starting thickness = % strain 16

Strain Rate • Strain rate measures the time course of deformation, and is the primary parameter of deformation derived from tissue Doppler • Strain is an analog of regional function • Increased preload = increased strain • Increased afterload = reduced strain – Strain rate • Less related to pre load and after load than strain

17

•The strain rate is the temporal derivative of the strain and indicates therefore the rate of the deformation. •This measurement is closely related to parameters of myocardial contractility.

18

Strain and Strain Rate Imaging • Strain Imaging measures the physical change (deformation) of the myocardium • Strain Rate Imaging measures how fast the deformation of the myocardium is occurring • To assess regional myocardial function • Distinguish local velocity from translational motion • Unaffected by tethering effect from other regions • Relatively uniform throughout the normal left ventricular myocardium 19

filling

HOW TO MEASURE THE STRAIN

21

Strain • • • • • • •

M Mode Tissue Doppler Imaging (pulsed wave) Color Tissue Doppler Imaging (TDI) 2D Strain Imaging – Doppler Velocity Speckle Tracking Torsion Twist 22

Why not one • Vigilance to ensure that values obtained by various techniques and technologies don’t get “lost in translation” and truth identified.

•

Standardization

23

Tissue Velocity Imaging from Dopplerto Grey Scale PW-DMI 1989

2D-Color DMI

2001

Color M-Mode

2003

Strain/S-Rate

2005

Speckle tracking 2007

Speckle tracking

M mode: Real Time Acquisition of Thickening Parameters

25

Tissue Doppler Imaging Techniques PW TDI

Color TDI S’

S’ A’ A’

E’

Peak Velocities

Mean Velocities

E’

26

Tissue Doppler Imaging Techniques PW TDI

Color TDI S’

S’ A’

E’

systole

E’

A’

diastole

27

1.

TDI characterizes the low velocity, high intensity signals that come from the wall.

2.

TDI is limited to movement relative to the sample volume fixed in space 3.Velocity pitfalls of tethering and translational motion

28

Strain Derived from Tissue Velocities • TV is maximum at the base (V1), lower in the mid heart (V2) and least at the apex (V3).

• This gradient in velocities is used to calculate strain rates.

• Strain rate is calculated as the difference between 2 tissue velocities along the ultrasound beam (V2 –V1) normalized to the distance between these 2 velocities 29 (d).

Higher Frame Rate with PW-DMI and M-Mode DMI Temporal Resolution 3-5 msec Q-S: Q-PEAK: ET: IRT: ICT: DIAST: C-O:

7 msec

Sutherland Doppler Myocardial Imaging Book Hasselt Belgium 2006

14 msec

85

msec

140 msec 287 msec 53 msec 67 msec 590 msec 447 msec

28 msec

50 msec

Sutherland Doppler Myocardial Imaging Book

Color Tissue Doppler Imaging (TDI)

direction and velocity

• Doppler based • Angle dependent • Difficulty lining up to scan plane • Tethering • Signal noise • Not as reproducible as anticipated

31

• • • • •

High frame rate > 140 Reduce depth and sector width.

Focus on temporal resolution.

The angle of icidence < 15 one-dimensional

32

ANGLE DEPENDENCY OF TDI •

Doppler signal is analyzed only along the scanline

•

Measured velocities are understimated if us beam is not adequately aligned with the movement direction of the examined structure

•

Narrow sector single wall acquisition may help minimizing this problem

•

3 components of myocardial motion can be interrogated by Doppler techniques   

Longitudinal Radial Cinrcumferential

Velocity: traslocation ,rotation ,thetering

Galiuto et al. EAE Textbook on Echocardiography. (in press) ed. Oxford: Oxford University Press; 2010

Tissue Based Strain Doppler TIPS • • • • •

To assess motion in a base to apex direction Sensitive to sub endocardial damage Velocity regression technique Signal noise ensure clean velocity signal Angle dependence align axis of movement with scan line + narrow sector.

• Respiratory drift acquire end expiration • Underestimation use high frame rates • Plane motion Caution in interpretation of events late after QRS 34

Onset to Peak Systole Septum Lateral

Systolic Ejection Time

Onset ECG Q-wave 35

Optimal Image Capture

Similar heart rate

LVOT for marking ET 36

Figure 3. Example of longitudinal velocity and strain curves before and after induction of a myocardial infarction. The basal portion of the interventricular septal wall (yellow curve) is necrotic whereas the mid (blue curve) and apical (red curv...

37

In Review • Tissue Doppler based strain – The velocity movement of the myocardium – Displayed as a parametric color image – Each pixel represents velocity relative to the transducer – Graphically recorded – Regression gradient between two points of velocity data, this measure provides the shortening or lengthening that represents strain 38

2D Based Strain Speckle Tracking

39

Doppler Strain – Primary Data is Strain Rate Frame 1

Frame 2

Frame 3

•Acquire a cineloop of Colour DTI /TVI • Unpack each frame •Offline analysis •Pixel encoded velocity data •High spatial resolution velocity map

The Prince Charles Hospital

GMS2012

Doppler Strain â&#x20AC;&#x201C; Primary Data is Strain Rate Frame 1

Frame 2

Frame 3

1cm

V1

V2

4cm/s - 5cm/s 1cm The Prince Charles Hospital

SR = v 2 - v1 Distance x

= -1/s GMS2012

Doppler Strain â&#x20AC;&#x201C; Primary Data is Strain Rate -1/s

Frame 1

Frame 2

Frame 3

1cm

V1 5cm/s

The Prince Charles Hospital

V2 - 7cm/s 1cm

= -2/s GMS2012

Doppler Strain â&#x20AC;&#x201C; Primary Data is Strain Rate -1/s

Frame 1

-2/s

Frame 2

Frame 3

1cm

V1 5cm/s

The Prince Charles Hospital

V2 - 5cm/s 1cm = 0/s

GMS2012

Doppler Strain â&#x20AC;&#x201C; Primary Data is Strain Rate -1/s

Frame 1

-2/s

0/s

Frame 2

SR = v 2 - v1 Distance x

V1 Frames

V2 E IVC

The Prince Charles Hospital

Frame 3

A

IVR

[1/s]

Time Strain Rate

GMS2012

Pros & Cons 2D Strain Advantages   

High spatial resolution Not Doppler angle dependant Analyses strain in 3 axis directions

Disadvantages   

The Prince Charles Hospital

Extremely image dependant Offline only Low temporal resolution

GMS2012

Speckle Tracking Techniques • • • •

Ultrasound reflectors within the tissue Highly reproducible Behave like magnetic resonance tags Shortening can be calculated by comparison of speckles from frame to frame • Attention to technical detail important, high frame rates can create high noise level

46

Competing technologies for Strain Doppler Strain

The Prince Charles Hospital

2D Strain

GMS2012

Optimal Image Capture

High frame rates Heart rates similar 48

Derivation of 2D Strain by Echo ZOOM

ZOOM

BLOCK

Y

New location Old location

dY 0

dX

X

Leitman M et al. JASE 2004; 17:1021-1029 49

Longitudinal Strain Normal

50

Longitudinal Strain Rate Normal

51

Radial Strain Short Axis

52

Radial Displacement

53

Clinical Applications Apex

Regional Function

Left Ventricular Function

Intramural Function

CRT

LAA Function

Right Ventricular function

LeftAtrial Function

Global Strain

Trambaiolo P Salustri A, JASE

Longitudinal Strain Dilated Cardiomyopathy

55

Follow-Up: Myocarditis Before recovery

European Society of Cardiology copyright -All right reserved

After recovery

56

Courtesy of Dr. M. Feinberg

Global LV Function • Global LV Function traditionally measured by LVEF and Volumes • Regional Wall Function – Highly subjective – Desires high level of training

57

Abnormal Global Longitudinal Strain â&#x20AC;&#x201C; 14%

58

Inferior yellow

59

Acute MI Typical Patterns Normal

LAD

RCA

LCX

European Society of Cardiology copyright -All right reserved

60

2D Speckle Tracking to Calculate Strain in Infarction

Bullâ&#x20AC;&#x2122;s eye plots generated by semiautomated strain analysis using 2dimensional speckle tracking technique to calculate strain

A : Normal Volunteer B: Antero-lateral infarction C: Infero-lateral Infarction D: non ischemic cardiomyopathy

Abraham TP et al Circulation 2007; 116: 2597-2609

61

Normals (n=40)

165±61

*p<0.001

STRAIN % Atrial Fibrillation (n=68)

79±16 98±31

44±26*

26±21* 26±18*

Strain

Normal subject

Patient with amiloidosys

3D Displacement

Limitations of 2D Speckle Tracking Hypertrophic Cardiomyopathy

•

The optimal frame rate for speckle tracking seems to be 50-70 frame per seconds which is lower compared to TDI(>180 frame).this could result in undersampling especially in patients with tachicardia

•

Rapid events during the cardiac cycle (ICT,IVRT) may disappear all together and peak SR and vel values may be reduced due to under sampling especially in isovolumic phases and in early diastole

•

Calculated parametres are averaged over the myocardial segment when using the result page of the software.

•

Small regions of myocardial dysfunction such as early stages of hypertrophic cardiomyopathy or arrhythmogenic right ventricular dysplasia the averaging could result in normal deformation

•

Software programs designed for speckle tracking are new and are subjected to periodical improvment

•

Different tracking algorithms produce different results

Right Ventricular Dysplasia

65

So Why Is Strain Rarely Used?

• In 2012 very few echoes report any advanced mechanics

• No interoperability – Each company has proprietary format – No DICOM scan line format – Different results with different equipment

• Need for standardization phantom • Changing workflow requirements – On-line or off-line? Need for separate review software?

• Too many parameters!

– Need for comparative studies 66

TDI versus STE strain STE STRAIN

TDI STRAIN • 1-dimensional

• 2-dimensional

• Angle-dependent (limited segments)

• Angle-independent (comprehensive)

• Limited spatial resolution

• Better spatial resolution

• High temporal resolution

• Lower temporal resolution

• Less dependent on image quality

• Dependent on image quality

• Requires expert readers to ensure

• Semi-automated analysis for less

reliability of results

experienced observers

• Time consuming

• Rapid

• Higher interobserver reproducibility

• Better reproducibility 67

Difference between Myocardial Velocity

by Doppler and by Speckle tracking • Higher frame rate • Great experience in many studies • Angle Dependence • Higher temporal resolution

Doppler

• No angle dependence • Possibility to analyze the apex • Better lateral resolution 2D Speckle • More automated and applied • More reproducible • Usable on previous exams stored(Grey scale) 68

Thank You!

69