CONSISTENCY OF SIGNAL INTENSITY AND R2* IN FROZEN PORCINE KIDNEY AND LIVER

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。前言：MR引导下冷冻消融是治疗前列腺、肝、肾肿瘤的一种很有前途的微创治疗方法。MRI很好地描绘了冰球边缘，因为冰冻组织的信号强度降低了。虽然已知冷冻组织中的松弛速率R2*增加，但不知道这些MR参数在组织类型之间有多一致。这项工作的目的是量化和比较新鲜切除的两种不同类型的体外冷冻组织的MR参数，肾脏和肝脏。方法和讨论：在Signa SP0.5T介入性扫描仪上对3个肝和4个肾组织标本进行成像。在两个相距25 mm的12x12x65 mm铜块之间的有机玻璃平板上放置10x10x25 mm的组织标本，放置一个仅接受的直肠内线圈。在每个铜块中插入35 mm的低温探头。将四个光纤温度放置在相隔5 mm的组织样本中。成像采用非层选择性脉冲序列(TR=200ms，FOV=200 mm，翻转角=60°，带宽31.25 kHz)。图像采集时间分别为210us、310us和610us。当组织从室温冷却到-40℃时，以5℃为增量重复成像。根据每个温度传感器周围的感兴趣区域计算信号强度(SI)和R2*。来自四个肾脏实验的SI数据以及三个肝脏实验的数据被组合在一起。SI适用于0℃和-4℃之间(线性拟合)和-6℃以下(指数拟合)之间的曲线。对于R2*数据，使用了线性拟合。两个斜率之间的差异在一个标准差内。然而，两条曲线的交点具有较大的变异性。SI和R2*值的一致性也在组织类型中进行了研究。三个肝脏实验和四个肾脏实验的R2*(T)线性拟合的斜率变化很小，但受试者之间的交叉值有相当大的不确定性。资助金编号：RO1 CA09061

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: MR-guided cryoablation is a promising method for the minimally invasive therapy of prostate, liver, and kidney tumors. MRI beautifully depicts the iceball edge as the frozen tissue has decreased signal intensity. Although it is known that the relaxation rate R2* increases in frozen tissue, it is not known how consistent these MR parameters are between tissue types. The purpose of this work was to quantify and compare the MR parameters of freshly excised ex vivo frozen tissue of two different types, kidney and liver. Methods and Discussion: Three liver and four kidney tissue samples were imaged in a Signa SP 0.5T interventional scanner. A receive only endorectal coil was placed adjacent to the tissue samples of dimensions 10x10x25mm which were placed on a plexi-glass plate between two 12x12x65mm copper blocks 25mm apart. A cryo probe was inserted 35mm into each copper block. Four fiber-optic temperature were placed into the tissue sample 5 mm apart. A non slice-selective pulse sequence was used for imaging (TR = 200ms, FOV = 200mm, flip angle = 60¿ and BW of 31.25 kHz). Images were acquired at echo times of 210us, 310us, and 610us. Imaging was repeated as the tissue was cooled from room temperature to -40¿C in 5¿C increments. Signal Intensity (SI) and R2* were calculated from a region of interest surrounding each temperature sensor. SI data from the four kidney experiments were grouped together as well as data for the three liver experiments. SI was fit to separate curves between 0¿C and -4¿C (linear fit) and below -6¿C (exponential fit). For R2* data, a linear fit was used. The difference between the slopes is within one standard deviation. However the intersects for two curves had a greater variability. Consistency of SI and R2* values was also studied within tissue types. The R2*(T) linear fits for three liver experiments and for four kidney experiments had little variability in slope, but considerable uncertainty in intersect values between the subjects. Grant #: RO1 CA09061