Colby R Ayers

Roderick McColl

Ronald M Peshock

Susan A Matulevicius

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BioMed Central
Journal of Cardiovascular Magnetic 
Resonance
ssOpen AccePoster presentation
Systematic method for cleaning circumferential strain from raw 
harmonic phase magnetic resonance imaging (HARP) analyzed 
data
Susan A Matulevicius*, Colby R Ayers, Roderick McColl and 
Ronald M Peshock
Address: University of Texas Southwestern, Dallas, TX, USA
* Corresponding author    
Introduction
Analysis of cardiac tissue tagging strain measurements can
be prone to noise secondary to tag fading, through plane
motion, and other imaging artifacts.
Purpose
We propose a method for systematically removing outlier
data points to improve reproducibility of circumferential
strain measurements as well as better model the physio-
logic behavior of the myocardium.
Methods
Spatial Modulation of Magnetization tissue tags were
placed on the myocardium at 3 T in 400 participants in
the Dallas Heart Study. Short-axis tagged slices were ana-
lyzed by the harmonic phase (HARP) method (Diagno-
soft, Palo Alto, California) to assess circumferential strain.
The raw segmental data at each phase (24 points per wall/
phase) was evaluated by the Shapiro-Wilk test for normal-
ity. If the strain at a given phase was not normally distrib-
uted (Shapiro-Wilk test p < 0.05), outlier points, defined
as any value less than the 25th percentile -1.5× the inter-
quartile range or greater than the 75th percentile +1.5×
the interquartile range, were removed. The mean strain
value at each phase was then calculated for cleaned data
and compared with raw data. 10 participants were ran-
domly selected for intra- and inter-observer variability cal-
culations. Interclass correlation coefficients were
calculated for peak systolic strain in each wall to compare
intra- and inter-observer variability. The mean and stand-
ard of peak systolic strain was calculated for the entire
cohort from both the raw and cleaned data and the per-
centage of participants with > 5 or < -5% strain at the end
of diastole in clean vs. raw data was compared.
Results
Cleaning improved both intra-observer and inter-observer
reproducibility (Table 1). Cleaning also decreased the
proportion of participants in the total sample who had
strain values > 5% or < -5% in late diastole (Table 2). The
standard deviation in peak systolic strain values was
decreased after cleaning (Clean vs raw: septum -18.5 ±
3.9% vs. -18.1 ± 4.4%; inferior -16.0 ± 3.3% vs. -15.5 ±
3.7%; lateral -20.5 ± 2.9% vs. -19.9 ± 3.2%; anterior -21.1
± 3.1% vs. 20.6 ± 3.3%).
Conclusion
Systematic cleaning of raw HARP circumferential strain by
removing outliers in non-normal distributions of strain at
each phase improves inter- and intraobserver variability
and decreases the proportion of participants in the total
sample who had strain values > 5% or < -5% in late dias-
tole.
from 13th Annual SCMR Scientific Sessions
Phoenix, AZ, USA. 21-24 January 2010
Published: 21 January 2010
Journal of Cardiovascular Magnetic Resonance 2010, 12(Suppl 1):P233 doi:10.1186/1532-429X-12-S1-P233
<supplement> <title> <p>Abstracts of the 13<sup>th </sup>Annual SCMR Scientific Sessions - 2010</p> </title> <note>Meeting abstracts - A single PDF containing all abstracts in this Supplement is available <a href="http://www.biomedcentral.com/content/files/pdf/1532-429X-11-S1-full.pdf">here</a>.</note> <url>http://www.biomedcentral.com/content/files/pdf/1532-429X-11-S1-info</url> </supplement>
This abstract is available from: http://jcmr-online.com/content/12/S1/P233
© 2010 Matulevicius et al; licensee BioMed Central Ltd. Page 1 of 2
(page number not for citation purposes)
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Table 1: Intraclass Coefficients of Variability for peak Systolic Strain Intra- and Interobserver Variability
Septal R2 Pr > F Inferior R2 Pr > F Lateral R2 Pr > F Anterior R2 Pr > F
Intraobserver Raw 0.87 0.05 0.88 < 0.01 0.83 0.02 0.72 0.11
Intraobserver Clean 0.93 < 0.01 0.86 < 0.01 0.88 < 0.01 0.82 0.02
Interobserver Raw 0.93 < 0.01 0.64 0.24 0.83 0.02 0.66 0.21
Interobserver Clean 0.96 < 0.01 0.91 < 0.01 0.83 0.02 0.78 0.05
Table 2: Proportion of participants with systolic strain > 5% or < -5% in late diastole
Septum Inferior Lateral Anterior
Clean 54/400 (14%) 46/400 (12%) 116/400 (29%) 110/400 (28%)
Raw 104/400 (26%) 112/400(28%) 167/400 (42%) 170/400 (43%)Page 2 of 2
(page number not for citation purposes)


Systematic method for cleaning circumferential strain from raw harmonic phase magnetic resonance imaging (HARP) analyzed data

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Systematic method for cleaning circumferential strain from raw harmonic phase magnetic resonance imaging (HARP) analyzed data

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