Improved quantification of left ventricular volumes and mass based on endocardial and epicardial surface detection from cardiac MR images using level set models.
OBJECTIVE
The reproducibility of left ventricular (LV) volume and mass measurements based on subjective slice-by-slice tracing of LV borders is affected by image quality, and volume estimates are biased by geometric modeling. The authors developed a technique for volumetric surface detection (VoSD) and quantification of LV volumes and mass without tracing and geometric approximations. The authors hypothesized that this technique is accurate and more reproducible than the conventional methodology.


METHODS
Images were obtained in 24 patients in 6 to 10 slices from LV base to apex (GE 1.5 T, FIESTA). Volumetric data were reconstructed, and endocardial and epicardial surfaces were detected using the level set approach. LV volumes were obtained from voxel counts and used to compute ejection fraction (EF) and mass. Conventional measurements (MASS Analysis) were used as a reference to test the accuracy of VoSD technique (linear regression, Bland-Altman). For both techniques, measurements were repeated to compute inter- and intra-observer variability.


RESULTS
VoSD values resulted in high correlation with the reference values (EDV: r = 0.98; ESV: r = 0.99; EF: r = 0.91; mass: r = 0.98), with no significant biases (8 ml, 5 ml, 0.2% and -9 g) and narrow limits of agreement (SD: 13 ml, 10 ml, 6% and 9 g). Inter-observer variability of the VoSD technique was lower (range 3 to 5%) than that of the reference technique (5 to 11%; p < 0.05). Intra-observer variability was also lower (1 to 3% vs. 7 to 10%; p < 0.05).


CONCLUSIONS
VoSD technique allows accurate measurements of LV volumes, EF, and mass, which are more reproducible than the conventional methodology.
Corsi
Cristiana
C
Department of Electronics, Computer Science and Systems, University of Bologna, Bologna, Italy.
Lamberti
Claudio
C
Catalano
Oronzo
O
MacEneaney
Peter
P
Bardo
Dianna
D
Lang
Roberto M
RM
Caiani
Enrico G
EG
Mor-Avi
Victor
V
D002306:Cardiac Volume; D005260:Female; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results; D013318:Stroke Volume