Li Weiguo, Zhang Zhuoli, Gordon Andrew C, Chen Jeane, Nicolai Jodi, Lewandowski Robert J, Omary Reed A, Larson Andrew C
From the Department of Radiology, Northwestern University, 737 N Michigan Ave, 16th Floor, Chicago, IL 60611 (W.L., Z.Z., A.C.G., J.C., J.N., R.J.L., A.C.L.); and Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tenn (R.A.O.).
Radiology. 2016 Feb;278(2):405-12. doi: 10.1148/radiol.2015150315. Epub 2015 Aug 27.
To investigate the qualitative and quantitative impacts of labeling yttrium microspheres with increasing amounts of superparamagnetic iron oxide (SPIO) material for magnetic resonance (MR) imaging in phantom and rodent models.
Animal model studies were approved by the institutional Animal Care and Use Committee. The r2* relaxivity for each of four microsphere SPIO compositions was determined from 32 phantoms constructed with agarose gel and in eight concentrations from each of the four compositions. Intrahepatic transcatheter infusion procedures were performed in rats by using each of the four compositions before MR imaging to visualize distributions within the liver. For quantitative studies, doses of 5, 10, 15, or 20 mg 2% SPIO-labeled yttrium microspheres were infused into 24 rats (six rats per group). MR imaging R2* measurements were used to quantify the dose delivered to each liver. Pearson correlation, analysis of variance, and intraclass correlation analyses were performed to compare MR imaging measurements in phantoms and animal models.
Increased r2* relaxivity was observed with incremental increases of SPIO microsphere content. R2* measurements of the 2% SPIO-labeled yttrium microsphere concentration were well correlated with known phantom concentrations (R(2) = 1.00, P < .001) over a broader linear range than observed for the other three compositions. Microspheres were heterogeneously distributed within each liver; increasing microsphere SPIO content produced marked signal voids. R2*-based measurements of 2% SPIO-labeled yttrium microsphere delivery were well correlated with infused dose (intraclass correlation coefficient, 0.98; P < .001).
MR imaging R2* measurements of yttrium microspheres labeled with 2% SPIO can quantitatively depict in vivo intrahepatic biodistribution in a rat model.
研究在体模和啮齿动物模型中，用不同含量的超顺磁性氧化铁（SPIO）材料标记钇微球对磁共振（MR）成像的定性和定量影响。
动物模型研究经机构动物护理与使用委员会批准。由四种微球SPIO组合物构建32个琼脂糖凝胶体模，每种组合物有八个浓度，测定每种组合物的r2弛豫率。在MR成像前，用这四种组合物对大鼠进行肝内导管输注操作，以观察其在肝脏内的分布。对于定量研究，将5、10、15或20mg 2% SPIO标记的钇微球剂量注入24只大鼠（每组6只大鼠）。用MR成像R2测量值来量化输送到每个肝脏的剂量。进行Pearson相关性分析、方差分析和组内相关性分析，以比较体模和动物模型中的MR成像测量结果。
随着SPIO微球含量的增加，观察到r2弛豫率升高。在比其他三种组合物更宽的线性范围内，2% SPIO标记的钇微球浓度的R2测量值与已知体模浓度具有良好的相关性（R(2) = 1.00，P <.001）。微球在每个肝脏内分布不均；微球SPIO含量增加会产生明显的信号缺失。基于R2*的2% SPIO标记的钇微球输送测量值与注入剂量具有良好的相关性（组内相关系数，0.98；P <.001）。
用2% SPIO标记的钇微球的MR成像R2*测量值可定量描绘大鼠模型中体内肝内生物分布情况。
