Temperature Dependency of Quantitative Ultrasound

Abstract

Quantitative ultrasound (QUS) parameters are temperature dependent. We examined the effect of temperature on QUS using Lunar Achilles+ and Hologic Sahara units. In vivo studies were performed in a cadaveric foot and in 5 volunteers. QUS scans were performed in the cadaveric foot, using both machines, at temperatures ranging from 15 to 40 degrees C. To assess the effect of change in water bath temperature in the Achilles+, independently of foot temperature, 5 volunteers were studied at water temperatures ranging from 10 to 42 degrees C. In the cadaveric foot there were strong negative correlations between temperature and speed of sound (SOS) but a moderately positive correlation between temperature and broadband ultrasound attenuation (BUA). Stiffness and the Quantitative Ultrasound Index (QUI) in the cadaveric foot showed strong negative correlations with temperature, reflecting their high dependence on SOS. In the 5 volunteers, in whom foot temperature was assumed to be constant, there was a small change in Stiffness in the Achilles+, with variation in water temperature. In conclusion, while there are opposite effects of temperature on SOS and BUA in vivo, there is still a significant effect of temperature variation on Stiffness and the QUI. This may have clinical significance in particular subjects. The precision of QUS may be affected by temperature variation of the environment or of the patient's limb. Instruments utilizing a water bath may be able partly to compensate for changes in environmental temperature, but standardization of water bath temperature is crucial to maximize precision.

Effect of Temperature on Ultrasonic Properties of the Calcaneus In Situ

“…However, these findings are ambiguous since calcaneal temperature was inferred from water bath or skin temperatures rather than measured directly. The only in situ data available are those obtained for a single cadaver foot, which yielded results broadly in line with the reported in vivo trends, but, again, temperatures were not measured directly in the calcaneus [10]. Furthermore, it is notable that, with a single exception [11], there have been no attempts to develop physical explanations for these temperature trends.…”

“…In vivo measurements of the human calcaneus suggest a negative thermal coefficient for velocity and a positive thermal coefficient for attenuation [8][9][10]. However, these findings are ambiguous since calcaneal temperature was inferred from water bath or skin temperatures rather than measured directly.…”

Avaliação ultra-sonométrica da consolidação de osteotomias mediodiafisárias transversas em diferentes períodos: estudo experimental em tíbias de carneiro

“…Temperature is an important variant to consider when sound speed measurements are performed. In a study performed on human cadavers' calcaneus, using the transmission technique, by the moment the piece was sunk in water during the analysis, the authors found a negative correlation between sample temperature and water temperature with the USPV (16) . For this reason, the acoustic tank temperature was strictly controlled during this investigation.…”

“…In a more recent study, the authors used a commercially available equipment, developed for osteoporosis analysis in human tibiae (SoundScan 2000 ® -Myriad Ultrasound Systems Ltd, Israel), for evaluating fractures, detecting an ultrasound conduction velocity increase as healing progresses (16) . The same equipment was used in other board study, where the USPV was measured in bodies of evidence of various materials having known length failures simulating simple transverse diaphyseal fractures in order to evaluate the variations imposed by the failure.…”

“…On the other hand, USPV varies according to the reference medium (water) temperature and to the temperature of the sample to be analyzed, this is because water, Teflon, and all samples' temperatures were also standardized during the analysis performance (16) . USPV itself is calculated by means of an equation, which may vary according to the source referred, with the one that best fitted the kind of analysis employed being selected for this study (17,18,19,20) .…”