Vesicoureteral reflux in young children: a study of radiometric thermometry as detection modality using an ex vivo porcine model.
Microwave radiometry is evaluated for renal thermometry tailored to detect the pediatric condition of vesicoureteral urine reflux (VUR) from the bladder through the ureter into the kidney. Prior to a potential reflux event, the urine is heated within the bladder by an external body contacting a hyperthermia applicator to generate a fluidic contrast temperature relative to normal body temperature. A single band, miniaturized radiometer (operating at 3.5 GHz) is connected to an electromagnetic-interference-shielded and suction-coupled elliptical antenna to receive thermal radiation from an ex vivo porcine phantom model. Brightness (radiometric) and fiberoptic temperature data are recorded for varying urine phantom reflux volumes (20-40 mL) and contrast temperatures ranging from 2 to 10 °C within the kidney phantom. The kidney phantom itself is located at 40 mm depth (skin-to-kidney center distance) and surrounded by the porcine phantom. Radiometric step responses to injection of urine simulant by a syringe are shown to be highly correlated with in situ kidney temperatures measured by fiberoptic probes. Statistically, the performance of the VUR detecting scheme is evaluated by error probabilities of making a wrong decision. Laboratory testing of the radiometric system supports the feasibility of passive non-invasive kidney thermometry for the detection of VUR classified within the two highest grades.
Department of Physics and Technology, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway. svein.jacobsen@uit.no
Svein
S
Jacobsen
Øystein
Ø
Klemetsen
Yngve
Y
Birkelund
D000818:Animals; D002648:Child; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D013552:Swine; D062125:Thermometry / Q000295:instrumentation / Q000379:methods*; D014718:Vesico-Ureteral Reflux / Q000175:diagnosis*