Faculty of Medicine and Health Sciences
Department of Circulation and medical imaging


Strain rate imaging

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Microblog archive.


#Cardiotoots #EchoFirst






November 4th: Thread on new reference values for global longitudinal strain from the HUNT4 study, comparison with HUNT3:


Nyberg J et al. Echocardiographic Reference Ranges of Global Longitudinal Strain for All Cardiac Chambers Using Guideline-Directed Dedicated Views.




October 30th: Derivation of the Doppler equation


The Doppler effect for a moving source and a stationary observer. In the time the original wave has moved a wavelength (which is 1 / f0), the source has moved the distance closer to the observer, determined by the velocity V of the source. The next wave will then meet the observer after the distance - , corresponding to the perceived wavelength .

 The Doppler effect for a stationary wave source and a moving observer. In the time the wave has moved the distance , the observer has moved the distance closer to the source, determined by the velocity v of the observer, and will meet the wavefront earlier , corresponding to the perceived wavelength , which is  - .

https://folk.ntnu.no/stoylen/strainrate/Basic_ultrasound.html#Derivation









October 23rd Angle deviation in Doppler velocity measurement:


#Cardiotoots #EchoFirst. If angle deviation causes If M-mode measurement to increase by the cosine of the angle, why does the Doppler velocity DECREASE by the cosine? Because the Doppler  wavelength actually increases, but as the frequency is inversely related to the wavelength, Doppler frequency, and thus wavelength, decreases by the cosine of the angle deviation.

https://folk.ntnu.no/stoylen/strainrate/Basic_ultrasound.html#AngleDop




October 16th 2023: Angle deviation in motion and dimension measurement


I've often met the misunderstanding that as angle deviation reduces the Doppler velocity measurement by the cosine to the angle, M-mode motion is reduced similarly. However, angle distortion INCREASES distance measurement by the cosine to the angle, both for dimension and motion measures.
https://folk.ntnu.no/stoylen/strainrate/Basic_ultrasound.html#Angle_dependency_1






October 13th 2023: Eulerien and Lagrangian strain


Eulerian versus Lagrangian strain https://folk.ntnu.no/stoylen/strainrate/Motion%20and%20deformation.html#Lagrangian_and_Eulerian_strain








September 30th 2023: IVR


IVR is more than just pressure/tension decline, there's simultaneous basal shortening and apical stretch. Basal shortening is not "wasted work":
1 causing apical flow in front of filling: is not wasted
2 shortening during relaxation is not really work.
https://folk.ntnu.no/stoylen/strainrate/Basic_physiology.html#IVR



September 22nd 2023: Strain rate vs strain



What's the difference between strain and strain rate?
1: Timing display https://folk.ntnu.no/stoylen/strainrate/Motion%20and%20deformation.html#Strain_vs_strain_rate
2: Peak strain rate is related to peak ejection volume decrease = peak flow i.e. contractility https://folk.ntnu.no/stoylen/strainrate/Basic_physiology.html#Peak_ejection , peak strain is related to total volume decrease (EF), i.e. total ejection performance.https://folk.ntnu.no/stoylen/strainrate/Basic_physiology.html#Ejection_performance



September 19th.: Atrial "conduit strain"



"Conduit strain" = AV-plane motion during early filling (ventr. diast. funct.) / atrial size. Conduit flow = atrial filling to replenish the part of AV flow due to transverse ventricular expansion, unrelated to atrial "conduit strain" which is compression. https://folk.ntnu.no/stoylen/strainrate/Basic_physiology.html#Atrial_filling_during_early_diastole._



September 8th: Atrial contractile strain:




Atrial contractile strain, reflects ventricular expansion during atrial systole, and is a complex function of atrial contractility, ventricular compliance (Numerator), and atrial size (denominator). Plenty of confounders. https://folk.ntnu.no/stoylen/strainrate/Basic_physiology.html#Late_filling