Mergo P J, Helmberger T, Nicolas A I, Ros P R
Department of Radiology, University of Florida College of Medicine, Gainesville 32610, USA.
AJR Am J Roentgenol. 1996 Feb;166(2):379-84. doi: 10.2214/ajr.166.2.8553952.
We performed this study to evaluate the incidence and significance of ring enhancement after i.v. administration of an ultrasmall superparamagnetic iron oxide (USPIO) particle (Code 7227), a reticuloendothelial contrast agent with potential use as a blood-pool agent, for characterizing focal hepatic lesions.
Conventional T1-weighed imaging, fat-suppressed T1-weighted imaging, conventional T2-weighted imaging, and fast T2-weighted imaging of the liver were obtained in 27 patients with 43 liver lesions before and after i.v. administration of a USPIO preparation. All lesions were larger than 1 cm; 29 were malignant and 14 were benign. Diagnosis was confirmed in all cases, either pathologically (19 patients) or by follow-up examination (eight patients). Two readers independently evaluated each pulse sequence for the presence of ring enhancement of hepatic lesions.
Ring enhancement was noted only on T1-weighted images, with no ring enhancement evident on T2-weighted images. Twenty of 43 (47%) lesions showed ring enhancement, including 18 of 29 (62%) malignant lesions and two of 14 (14%) benign lesions (p < .011); Wilcoxon signed rank test). Fat-suppressed T1-weighted imaging showed ring enhancement better than or equal to conventional T1-weighted imaging in all cases, with ring enhancement of 15 of 18 (83%) malignant lesions and two of two benign lesions better demonstrated on fat-suppressed T1-weighted imaging sequences (p < or = .025).
Ring enhancement after i.v. administration of Code 7227 is a frequent finding seen more often with malignant than benign lesions, potentially identifying a new MR imaging feature for the characterization of liver lesions. The identification of ring enhancement on T1-weighted images attests to the significant blood-pool effects of USPIO particles.
我们开展这项研究以评估静脉注射超小型超顺磁性氧化铁（USPIO）颗粒（代码7227）后环形强化的发生率及意义。USPIO是一种网状内皮细胞造影剂，具有作为血池造影剂的潜在用途，用于肝脏局灶性病变的特征性诊断。
对27例患有43个肝脏病变的患者在静脉注射USPIO制剂前后进行肝脏常规T1加权成像、脂肪抑制T1加权成像、常规T2加权成像及快速T2加权成像检查。所有病变均大于1cm；其中29个为恶性病变，14个为良性病变。所有病例均经病理（19例患者）或随访检查（8例患者）确诊。两名阅片者独立评估每个脉冲序列中肝脏病变的环形强化情况。
仅在T1加权图像上观察到环形强化，T2加权图像上未见明显环形强化。43个病变中有20个（47%）显示环形强化，包括29个恶性病变中的18个（62%）和14个良性病变中的2个（14%）（p<0.011；Wilcoxon符号秩检验）。脂肪抑制T1加权成像在所有病例中显示环形强化的效果优于或等同于常规T1加权成像，18个恶性病变中的15个（83%）及2个良性病变中的2个在脂肪抑制T1加权成像序列上环形强化显示更佳（p≤0.025）。
静脉注射代码7227后出现的环形强化是常见表现，在恶性病变中比良性病变更常见，这可能为肝脏病变的特征性诊断确定一种新的磁共振成像特征。在T1加权图像上发现环形强化证明了USPIO颗粒具有显著的血池效应。
