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Identifikacija in kvantifikacija izvorov variabilnosti pri meritvah krčenja srčne mišice levega prekata z ultrazvočno metodo STE
Strašek, Katja (Author), Jeraj, Robert (Mentor) More about this mentor... This link opens in a new window, Kirn, Borut (Co-mentor)

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Abstract
$\textbf{UVOD:}$ Miokarditis je redka bolezen srca, ki pogosteje prizadene mlajše odrasle. Slikovna preiskava deformacije miokarda s sledenjem ultrazvočnega vzorca (STE) se je zaradi večje dostopnosti uveljavila kot alternativna diagnostična metoda. S to metodo je moč zaznati spremembo globalnega krčenja levega ventrikla, lokacije in obsega poškodbe pa zaradi velike variabilnosti rezultatov ne moremo izmeriti. V raziskavi so nas zanimali vzroki negotovosti, ki vplivajo na kvantitativno vrednotenje ultrazvočnih slik. $\textbf{METODE:}$ V krivuljah longitudinalne deformacije levega prekata 34 preiskovancev ob diagnozi miokarditsa in šest mescev kasneje, izmerjenih z metodo STE, smo določili točko največje deformacije $\varepsilon_P$. Z analiziranjem povprečnih $\varepsilon_P$ po sektorjih, projekcijah in rezinah ter izračunom gradienta $\varepsilon_P$ od baze do apeksa (k) v vseh treh projekcijah smo analizirali vzroke negotovosti, ki vplivajo na kvantitativno vrednotenje ultrazvočnih slik, in sicer: tri merilne projekcije, odstopajoče meritve deformacije, način izračuna vrednosti $\varepsilon_P$ in različne vrednosti $\varepsilon_P$ med preiskovanci. Vplive smo ocenjevali s povprečjem in standardno deviacijo. $\textbf{REZULTATI:}$ Povprečna vrednost $\varepsilon_P$ v naši raziskavi je znašala –20.3 $\% \pm$ 5.2 $\%$. V projekcijah je znašala povprečna vrednost $\sigma_P$ 5.2 $\%$, k pa –2.15 $\% \pm$2.68 $\%$; statističnih razlik v variabilnosti med projekcijami nismo opazili (p>0.62 in p>0.27). Vpliv odstopajočih meritev na variabilnost je bil v območju pričakovanega. Z izračunom vrednosti $\varepsilon_P$ iz več točk smo dobili povprečno vrednost $\sigma_P$ 5.1 $\%$, k pa –2.04 $\% \pm$ 2.66 $\%$, kar se statistično ni razlikovalo od vrednosti, ki smo jih določili iz ene točke (p>0.26). Interindividualna variabilnost bolnih in zdravih je bila za 30 $\%$ večja od intraindividualne variabilnosti pred in po zdravljenju. $\textbf{ZAKLJUČEK:}$ Lokalne lastnosti odražajo znano mehaniko levega ventrikla. Največji del variabilnosti vrednosti $\varepsilon_P$ in k izvira iz naravne variabilnosti deformacije med preiskovanci, saj z optimizacijo kvantitativne analize (izbor merilnih projekcij, odstranitev najbolj odstopajočih meritev in način izračuna vrednosti $\varepsilon_P$) ne prispevamo pomembno k zmanjšanju variabilnosti.

Language:Slovenian
Keywords:STE, miokarditis, variabilnost, levi prekat, največja deformacija, gradient največje deformacije
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:FMF - Faculty of Mathematics and Physics
Year:2021
COBISS.SI-ID:75806211  This link opens in a new window
Views:61
Downloads:12
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Secondary language

Language:English
Title:Identification and quantification of sources of variability in measurments of left ventricle strain with ultrasound method STE
Abstract:
$\textbf{INTRODUCTION:}$ Myocarditis a rare hearth disease, more common with young adults. As an alternative diagnostic method, speckle tracking echocardigraphy (STE) is used, which is more accessible as other established methods. Changes in global strain can be detected with this method, while location and extent of inflammation remain unknown due to big variability of measurements. In this paper, we researched the causes of variability influencing the quantitative evaluation of ultrasound measurements. $\textbf{METHODS:}$ Longitudinal strain curves of the left ventricle were measured with STE in 34 patients upon the diagnosis and 6 months later, in which we detemined the point of maximum deformation $\varepsilon_P$. With the analysis of average $\varepsilon_P$ in sectors, projections and slices, and the calculation of its gradient from base to apex (k) we determined the effects on variability: three different projections, deviating measurements, method of calculation of $\varepsilon_P$ and interpersonal differences. We assessed these effects by calculating mean and standard deviation. $\textbf{RESULTS:}$ Average calculated $\varepsilon_P$ was –20.3 $\% \pm$ 5.2 $\%$. Average $\sigma_P$ in projections was 5.2 $\%$, k –2.15 $\% \pm$ 2.68 $\%$, with no statistical differences (p>0.62 and 0.27). The effect of the deviating measurements was in the expected range. When calculating $\varepsilon_P$ from multiple points, the average $\sigma_P$ was 5.1 $\%$, k –2.04 $\% \pm$ 2.66 $\%$ in projections, with no statistical difference from previous values (p>0.26). Interindividual variability of healty individuals and patients was 30 $\%$ higher than intraindividual variability before and after tratment. $\textbf{CONCLUSION:}$ Local properties reflect the known mechanics of the left ventricle. Most of the variability of $\varepsilon_P$ stems from the natural interindividual variability of the deformation since the optimization of the quantitative analysis (selection of measurement projections, exclusion of deviating measurements, improvement of the calculation of $\varepsilon_P$) does not contribute significantly to its reduction.

Keywords:STE, myocarditis, variability, left ventricle, peak strain, gradient of peak strain

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