Stauffer Paul R, Maccarini Paolo F, Arunachalam Kavitha, De Luca Valeria, Salahi Sara, Boico Alina, Klemetsen Oystein, Birkelund Yngve, Jacobsen Svein K, Bardati Fernando, Tognolatti Piero, Snow Brent
Radiation Oncology Department, Duke University, Durham NC, 27710.
Proc SPIE Int Soc Opt Eng. 2011;7901:79010V. doi: 10.1117/12.875636. Epub 2011 Feb 22.
Vesicoureteral reflux (VUR) is a serious health problem leading to renal scarring in children. Current VUR detection involves traumatic x-ray imaging of kidneys following injection of contrast agent into bladder via invasive Foley catheter. We present an alternative non-invasive approach for detecting VUR by radiometric monitoring of kidney temperature while gently warming the bladder. METHODS: We report the design and testing of: i) 915MHz square slot antenna array for heating bladder, ii) EMI-shielded log spiral microstrip receive antenna, iii) high-sensitivity 1.375GHz total power radiometer, iv) power modulation approach to increase urine temperature relative to overlying perfused tissues, and v) invivo porcine experiments characterizing bladder heating and radiometric temperature of aaline filled 30mL balloon "kidney" implanted 3-4cm deep in thorax and varied 2-6°C from core temperature. RESULTS: SAR distributions are presented for two novel antennas designed to heat bladder and monitor deep kidney temperatures radiometrically. We demonstrate the ability to heat 180mL saline in in vivo porcine bladder to 40-44°C while maintaining overlying tissues <38°C using time-modulated square slot antennas coupled to the abdomen with room temperature water pad. Pathologic evaluations confirmed lack of acute thermal damage in pelvic tissues for up to three 20min bladder heat exposures. The radiometer clearly recorded 2-6°C changes of 30mL "kidney" targets at depth in 34°C invivo pig thorax. CONCLUSION: A 915MHz antenna array can gently warm in vivo pig bladder without toxicity while a 1.375GHz radiometer with log spiral receive antenna detects ≥2°C rise in 30mL "urine" located 3-4cm deep in thorax, demonstrating more than sufficient sensitivity to detect Grade 4-5 reflux of warmed urine for non-invasive detection of VUR.
膀胱输尿管反流（VUR）是导致儿童肾瘢痕形成的严重健康问题。目前VUR检测涉及通过侵入性Foley导管将造影剂注入膀胱后对肾脏进行创伤性x光成像。我们提出了一种通过在轻柔加热膀胱的同时对肾脏温度进行辐射测量来检测VUR的非侵入性替代方法。方法：我们报告了以下设计和测试：i）用于加热膀胱的915MHz方槽天线阵列，ii）电磁干扰屏蔽对数螺旋微带接收天线，iii）高灵敏度1.375GHz全功率辐射计，iv）相对于覆盖的灌注组织提高尿液温度的功率调制方法，以及v）体内猪实验，表征植入胸部3 - 4厘米深处、与核心温度相差2 - 6°C的30mL气囊“肾脏”的膀胱加热和辐射温度。结果：展示了两种新型天线的比吸收率（SAR）分布，这两种天线旨在加热膀胱并以辐射方式监测深部肾脏温度。我们证明，使用与腹部耦合的室温水垫的时间调制方槽天线，能够将体内猪膀胱中的180mL盐水加热至40 - 44°C，同时保持覆盖组织温度低于38°C。病理评估证实，在长达三次每次20分钟的膀胱热暴露中，盆腔组织未出现急性热损伤。辐射计清晰记录了在34°C的体内猪胸部深处30mL“肾脏”目标的2 - 6°C变化。结论：915MHz天线阵列可以在不产生毒性的情况下轻柔地加热体内猪膀胱，而带有对数螺旋接收天线的1.375GHz辐射计能够检测到位于胸部3 - 4厘米深处的30mL“尿液”中≥2°C的升温，这表明其灵敏度足以检测温热尿液的4 - 5级反流，用于VUR的非侵入性检测。
