This study was performed to compare the ability in discerning targets of different elasticity in an elasticity phantom between strain-ratios, strain-histograms and shear-wave-velocity measurements.
Materials and Methods: A commercially available elasticity phantom was used to assess the ability of strain-ratios, strain-histograms and shear-wave-velocity measurements in discerning targets of different elasticities. Twenty targets of varying diameters (2.5 to 16.7 mm) and stiffness (8, 14, 45 and 80 kPa) were evaluated and each target was evaluated ten times. This yielded 200 observations pr. elastographic method used. Receiver-Operator Characteristic curves were analyzed for each method with data divided between the four different target elasticities.
Results: All three methods performed well when data was divided between the soft and hard targets (8 and 14 kPa vs. 45 and 80 kPa): Area under curve (AUC) were 0.991 for both strain-ratios and strain-histograms and shear-wave-velocities. When data was divided between the soft targets (8 kPa vs. 14, 45 and 80 kPa) AUC of strain-ratios and strain-histograms were slightly better than AUC of shear-wave-velocities (0.946 and 0.940 vs. 0.902). In data divided between the hard targets (8, 14 and 45 kPa vs. 80 kPa), all strain-ratios and strain-histograms also had slightly better AUCs than shear-wave-velocities (0.978 and 0.989 vs. 0.861).
Conclusion: Strain-ratios, strain-histograms and shear-wave-velocity-measurements all have high diagnostic accuracies in an elasticity phantom. The AUC of the different methods vary according to which level of target stiffness is being assessed.
