Prospective comparison of different ultrasound modalities to measure thicknesses less than 1 mm

PURPOSE: New ultrasound techniques with improved visualization and better transducers constantly expand the methods of measurement. In the border area in the case of thickness measurements of less than 1 millimeter, e. g. the measurement of the "Intima-Media Thickness" (IMT), it is not clear if better visualization comes at the price of incorrect measurement values. We checked different modalities for accuracy and visualization quality. MATERIALS AND METHODS: We prospectively examined the IMT of obese children using different ultrasound modalities. The image quality was evaluated by two independent pediatric radiologists. A phantom with an exact thickness of 0.3 mm (value of the thinnest measured IMT thickness) was subsequently created by precision engineers. Measurements were carried out and analyzed using fundamental ultrasound, tissue harmonic imaging, speckle reduction imaging and cross beam (real-time compound) imaging. RESULTS: The best image quality was reached using speckle reduction imaging. This technique and fundamental ultrasound produced the most exact data. However, the recognizability was worse in fundamental ultrasound than in speckle reduction imaging. CONCLUSION: Speckle reduction imaging appears to be the best technique for measuring thicknesses less than 1 mm.