Velocity of ultrasound wave transmission at the bones for evaluating incipient rickets in infants
Authors: Chun-hua Jin, Yue Zhang, Xiao-yan Wang, Rui-hua Yang, He-ru Wang, Wen-hong Song, Mei Li, Mu-lan Yang, Guang-chi Wu
Journal: BMJ (2010)

Objective To explore rules of changes in velocity of ultrasound wave transmission at the tibia and radius by a quantitative bone mineral density ultrasound scanner in examination of early incipient rickets in infants and its significance in clinical diagnosis.Methods One hundred and fifty-seven infants who visited child health-care clinic of the Capital Institute of Pediatrics,Beijing during May 2004 to December 2007 and clinically diagnosed as rickets according to the Criteria of Diagnosis for Rickets in Infants and Young Children formulated in 1986 by the Ministry of Health,as well as 124 normal healthy infants as controls,were enrolled in the study and followed-up for three months.Velocity of ultrasound wave transmission at the tibia and radius in all the infants were measured by a bone mineral density ultrasound scanner (Sunlight Omnisense 7000R made in Israel).Results One hundred and fifty-seven infants were clinically diagnosed as rickets,127 of them undergone with carpal plane roentgenography and 90 of the 127 with positive change in bone x-ray imaging and 37 without it.Velocity of ultrasound wave transmission at the tibia and radius measured by z-score was significantly lower in infants with clinically diagnosed rickets than that in healthy controls (Z-values of-10.411 and-10.399 at the tibia and-5.646 and-5.517 at the radius,respectively,P = 0.000 with Mann-Whitney test).Velocity of ultrasound wave transmission at the tibia and radius measured by z-score was lower in those with positive change in x-my imaging than that in those without it,but not reaching a level of statistically significant difference.Velocity of ultrasound wave transmission and z-score correlated positively with change in bone x-ray imaging,respectively with Spearman coefficients of correlation of 0.581 and 0.677 for tibia,0.316 and 0.467 for radius (P = 0.000).Receiver operating characteristic (ROC) curve was drawn from those with rickets and positive left carpal plane roetgenograph.Area under curve of ROC for z-score of velocity of ultrasound wave transmission at the tibia was 0.812 and 0.799 (95% CI 0.758-0.856 and 0.742-0.855,P =0.000),respectively.Area under ROC curve of z-score of velocity of ultrasound wave transmission at the radius was 0.715 and 0.697 (95% CI 0.650-0.780,0.631-0.764,P =0.000),respectively.Cut-off value of z-score was-205--1.95 at the tibia,according to the largest sensitivity and the least false-positivity,with sensibility of 0.8 to 0.9 and specificity of 0.733 to 0.702.As its sensitivity at the radius was more than 0.7,its specificity was lower than 0.524.Conclusions Quantitative ultrasound scanning can be used to detect insufficient bone mineral density in infants and their early skeletal change by rickets but without change in bone x-ray imaging.Velocity of ultrasound wave transmission at the tibia can be used as an indicator to predict early rickets in infants rather than its severity.

Key words: 
Infant;  Rickets;  Skeleton;  Ultrasonography