Weissleder R, Hahn P F, Stark D D, Rummeny E, Saini S, Wittenberg J, Ferrucci J T
AJR Am J Roentgenol. 1987 Oct;149(4):723-6. doi: 10.2214/ajr.149.4.723.
Detection of intrasplenic neoplasms using sonography, CT, and scintigraphy is limited by poor inherent tumor-spleen contrast relative to image noise. Despite the wide range of contrast parameters available for MR imaging, similar limitations have been found with this technique. Magnetopharmaceuticals have the ability to enhance tumor-spleen contrast and improve lesion detectability. In this study, a rodent model of cancer metastasized to the spleen was used to evaluate the potential of superparamagnetic ferrite particles as a tissue-specific reticuloendothelial contrast agent. Other studies have shown ferrite to have little or no toxicity. Without contrast material, metastatic adenocarcinoma of the spleen could not be distinguished from normal splenic parenchyma on in vivo MR images. At a dose of 50 mumol Fe/kg, the T2 relaxation time of spleen decreased by 77%, while tumor T2 was essentially unchanged (p less than .005). Intrasplenic tumors 4-6 mm in size became readily detectable on in vivo MR images after the administration of ferrite particles. Lesion conspicuity, quantitated by the tumor-spleen contrast-to-noise ratio, showed a 43-fold increase. Ferrite particles show great promise as a contrast agent to enhance the detection of focal splenic lesions.
相对于图像噪声，脾脏内肿瘤与脾脏之间固有的对比度较差，这限制了超声、CT和闪烁扫描对脾脏内肿瘤的检测。尽管磁共振成像（MR成像）有多种可用的对比度参数，但该技术也存在类似的局限性。磁性药物有能力增强肿瘤与脾脏之间的对比度，并提高病变的可检测性。在本研究中，使用癌症转移至脾脏的啮齿动物模型来评估超顺磁性铁氧体颗粒作为组织特异性网状内皮细胞造影剂的潜力。其他研究表明，铁氧体的毒性很小或没有毒性。在体内MR图像上，若无造影剂，脾脏转移性腺癌无法与正常脾实质区分开来。以50 μmol Fe/kg的剂量给药时，脾脏的T2弛豫时间缩短了77%，而肿瘤的T2基本未变（p<0.005）。给予铁氧体颗粒后，4 - 6毫米大小的脾脏内肿瘤在体内MR图像上变得易于检测。通过肿瘤与脾脏的对比噪声比进行定量的病变清晰度提高了43倍。铁氧体颗粒作为增强局灶性脾脏病变检测的造影剂显示出巨大的前景。
