Table 2. Studies reporting reference values for 3D strain parameters from healthy volunteers.

Author	Number population (age range)	Ultrasound system	3DSTE software	3D global longitudinal strain	3D global circumferential strain	3D global radial strain	3D area strain (or 3D principal tangential strain^)
Kleijn et al. [2015] (41)	303 [18–82]	Artida 4D (Toshiba Medical Systems)	Toshiba Medical Systems	−15.9±2.4	−30.6±2.6	35.6±10.3	−42.0±2.4
Muraru et al. [2014] (18)	265 [18–76]	Vivid E9 scanner (GE Vingmed Ultrasound)	4D AutoLVQ (EchoPac BT12 and 13, GE Vingmed Ultrasound)	−19 [−21, −17]*	−18 [−20, −17]*	52 [47−59]*	−33 [−36,−31]*
Muraru et al. [2014] (18)	265 [18–76]	Vivid E9 scanner (GE Vingmed Ultrasound)	4D LV Analysis (TomTec Imaging Systems)	−20 [−23, −18]*	−28 [−31, −25]*	41 [36–44]*	−32 [−35, −29]*
Kaku et al. [2014] (40)	313 [1–88]	Sonos 7500 or iE33 scanner (Philips Medical Systems)	4D LV Analysis (TomTec Imaging Systems)	−20.3±3.2	−28.9±4.6	–	−37.6±4.8
Pérez de Isla et al. [2011] (43)	60 [23–53]	Artida 4D (Toshiba Medical Systems)	Toshiba Medical Systems	–	–	–	−38.8±5.8

^, three-dimensional strain or principal tangential strain (4D LV-Analysis); *, reference values are expressed as median [first quartile, third quartiles].