Longitudinal strain from velocity encoded cardiovascular magnetic resonance: a validation study

Abstract

BackgroundRegional myocardial function is typically evaluated by visual assessment by experienced users, or by methods requiring substantial post processing time. Visual assessment is subjective and not quantitative. Therefore, the purpose of this study is to develop and validate a simple method to derive quantitative measures of regional wall function from velocity encoded Cardiovascular Magnetic Resonance (CMR), and provide associated normal values for longitudinal strain.MethodBoth fast field echo (FFE) and turbo field echo (TFE) velocity encoded CMR images were acquired in three long axis planes in 36 healthy volunteers (13 women, 23 men), age 35±12 years. Strain was also quantified in 10 patients within one week after myocardial infarction. The user manually delineated myocardium in one time frame and strain was calculated as the myocardium was tracked throughout the cardiac cycle using an optimization formulation and mechanical a priori assumptions. A phantom experiment was performed to validate the method with optical tracking of deformation as an independent gold standard.ResultsThere was an excellent agreement between longitudinal strain measured by optical tracking and longitudinal strain measured with TFE velocity encoding. Difference between the two methods was 0.0025 ± 0.085 (ns). Mean global longitudinal strain in the 36 healthy volunteers was −0.18 ± 0.10 (TFE imaging). Intra-observer variability for all segments was 0.00 ± 0.06. Inter-observer variability was −0.02 ± 0.07 (TFE imaging). The intra-observer variability for radial strain was high limiting the applicability of radial strain. Mean longitudinal strain in patients was significantly lower (−0.15± 0.12) compared to healthy volunteers (p<0.05). Strain (expressed as percentage of normal strain) in infarcted regions was lower compared to remote areas (p<0.01).ConclusionIn conclusion, we have developed and validated a robust and clinically applicable technique that can quantify longitudinal strain and regional myocardial wall function and present the associated normal values for longitudinal strain.

INCA (Peru) Study: Impact of Non‐Invasive Cardiac Magnetic Resonance Assessment in the Developing World

“…The clinical utility found in Peru of 56% having changed care after CMR is somewhat less than demonstrated in international registries, as European/US registries have reported that CMR changed care in 61.8% of patients 30, 31. However, we would have reached these levels in our study by including the 5% of patients in which a change in management was appropriate but not possible due to access barriers.…”

“…Quality: The rapid CMR protocol was tested in advance using freely available video conferencing software. We used low‐dose gadolinium (0.1 mmol/L per kg) for cost and so the blood‐pool was not bright at the time of LGE imaging 33. The CMR studies were conducted within a safe environment, with only one minor complication which was a panic attack.…”

“…Cardiac magnetic resonance (CMR) imaging is an emerging imaging technique with the capacity to transform cardiology in an analogous way to the impact of brain MRI in neurology 7, 8. Multiple different techniques are available using CMR (function, scar, perfusion, flow, mapping, angiography), delivering valuable clinical insights with the potential of a high impact 9, 10, 11. However, these varied techniques may make it slow (typically 45 minutes), expensive and complex, potentially out of reach for most inhabitants in the developing world.…”

Mechanistic Insights and Characterization of Sickle Cell Disease–Associated Cardiomyopathy

“…The presence of LGE has been rarely reported in previous studies evaluating smaller cohorts and case reports of patients with sickle cell disease 12-16 . Notably, the significant proportion of patients with LGE is a novel finding in patients with SCD.…”

Myocardial deformation parameters predict outcome in patients with repaired tetralogy of Fallot

“…Despite its recognised advantages, CMR has significant limitations in quantifying myocardial deformation (eg, myocardial strain). While specific techniques such as tissue-tagging CMR or harmonic phase analysis have been available to this end, their acceptance has been limited due to the requirement for sophisticated and time-consuming sequence acquisition, need for specific expertise and financial reasons 16. The introduction of CMR feature tracking (FT)—a technique allowing the quantification of myocardial strain using standard cine steady-state free-precession sequences—offers the opportunity to quantify myocardial deformation directly without resorting to echocardiography 17.…”