Neonatal pig brain: lack of heating during Doppler US.
OBJECTIVE
To evaluate potential local brain-heating effects of Doppler ultrasound (US) at high power output settings.


METHODS
After craniotomy, a temperature probe was inserted into deep white matter or basal ganglia in 12 anesthetized newborn piglets. The range gate and focal zone were placed directly over the temperature sensor. Brain and core (rectal) temperatures were measured before and during 5 minutes of continuous transdural duplex or color Doppler US, with transmitter power output settings of less than 500 mW in situ spatial peak temporal average or less than 800 mW in situ spatial peak temporal average. Temperature also was measured during administration of a US contrast agent with duplex US at less than 500 mW in situ spatial peak temporal average and after death at the same output setting.


RESULTS
Maximal differences between the baseline and the post-US temperatures were, on average, less than 0.3 degree C (P > .5) and were highly correlated with changes in core temperature (r = .9, P < .001). Addition of the contrast agent did not result in focal brain heating during pulsed Doppler US (P > .6). There was no association between an increase in estimated power output and brain temperature change (P = .9). In addition, brain ischemia (postmortem exposure) was not associated with focal brain heating during pulsed Doppler US.


CONCLUSIONS
Transfontanellar Doppler US alone or with administration of a contrast agent does not produce statistically significant focal brain heating at high transmitter power levels.
Taylor
G A
GA
Department of Radiology, Children's Hospital, Boston, MA, USA.
Barnewolt
C E
CE
Dunning
P S
PS
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001479:Basal Ganglia / Q000502:physiology; D001831:Body Temperature / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D002545:Brain Ischemia / Q000503:physiopathology; D003287:Contrast Media / Q000008:administration & dosage; D003399:Craniotomy; D004453:Echoencephalography; D005069:Evaluation Studies as Topic; D006358:Hot Temperature; D013552:Swine; D013821:Thermometers; D018608:Ultrasonography, Doppler; D018615:Ultrasonography, Doppler, Color; D018616:Ultrasonography, Doppler, Duplex; D018617:Ultrasonography, Doppler, Pulsed
D003287:Contrast Media