Prospective application of virtual touch tissue imaging quantification in the diagnosis of initial polymyositis

Objective To explore the application value of virtual touch tissue imaging quantification(VTIQ) technology in initial polymyositis(PM). Methods Sixteen PM patients collected from February 2016 to March 2019 in Wenzhou People′s Hospital were selected as PM group, and 33 healthy subjects as healthy control group. After gray and color Doppler ultrasound, the shear wave velocity(SWV) values of target muscle and control muscle in the same side of affected limb were measured by VTIQ technique. Maximum velocity(Vmax) and minimum velocity(Vmin) were measured, average velocity(Vmean) and standard deviation(SD) were calculated, and compared between the two groups. SWV difference and ratio between target muscle and control muscle were calculated, and creatine kinase(CK) was detected in the same day. Results Part of PM patients had abnormal ultrasonographic manifestations of full muscle shape (31.25%), increased or decreased echo of muscle bundles (56.25%), blurred muscle texture (25.00%) and increased blood flow signals (37.50%). There were significant differences in Vmin, SD, and Vmax difference, Vmin difference, Vmean difference, and Vmax ratio, Vmin ratio, and Vmean ratio between PM group and healthy control group (all P<0.01). The ROC curve analysis showed that the diagnostic efficiency of Vmin was lower than those of Vmin difference and Vmean difference, Vmin ratio and Vmean ratio with very close diagnostic efficiencies of the latter four parameters. The correlation analysis showed that Vmin difference and Vmean difference were moderately correlated with CK value(r=0.512, 0.601; all P<0.05). Conclusions Reduced VTIQ values or relative reduction of VTIQ values compared with other non-involved muscles are the manifestations of initial PM, VTIQ have certain diagnostic efficacy for initial PM. Key words: Virtual touch tissue imaging quantification; Polymyositis; Applied research