组织特异性对比剂--Mn-DPDP的临床应用

目的　探讨肝脏、胰腺病变在Mn -DPDP增强MRI检查中的强化特征。方法　 2 5例Mn -DPDP增强MRI检查 ,其中有15例先行Gd -DTPA增强扫描。常规扫描序列为SET1WI、FSET2 WI、FSET1WI脂肪抑制序列。Mn -DPDP剂量为 0 .5ml/Kg体重 ,肘静脉缓慢滴注 ( 2～ 3ml/min) ,于给药结束后 40min～ 1h扫描 ,序列为SET1WI和FSPGRT1WI ,5例病人 2 4h后复查。结果　原发型肝癌 10例 ,8例为轻度不均匀强化、2例呈半环状强化。肝硬化 2例 ,表现为结节状均匀一致强化且信号高于正常肝组织。肝血管瘤 2例、肝转移瘤 2例、肝囊肿 1例均无强化 ;胰头癌 8例 ,病灶无强化 ,周围胰腺组织明显强化。结论　Mn -DPDP对比剂能使正常肝脏、胰腺显著强化。该药物峰值持续时间长 ,可提供充裕的扫描时间窗     

Evidence for the dissociation of the hepatobiliary MRI contrast agent Mn-DPDP

These experiments assessed and quantitated the release of free manganese Mn⁺⁺ from the hepatobiliary contrast agent Mn-DPDP (manganese dipyridoxal diphosphate), using several magnetic resonance techniques (EPR spectroscopy, ³¹P-NMR spectroscopy, and relaxometry) to differentiate between free Mn⁺⁺ and Mn⁺⁺ in complexes in various preparations. The presence of calcium and magnesium in physiological concentrations in aqueous solutions induced the release of Mn⁺⁺ from the complex, as did incubation of the complex in liver homogenates. After intravenous injection of 15 μmol/kg of Mn-DPDP, both EPR and ³¹P-NMR spectroscopy demonstrated that Mn-DPDP is partly dissociated (approximately 25%) in the liver. By comparing in vitro and ex vivo data from the liver, we concluded that the dissociation of Mn-DPDP occurs primarily in the liver, whereas a minor portion of the dissociated Mn found in the liver comes from dissociation of the complex in the blood. Most of the dissociated Mn in liver becomes bound to macromolecules and is responsible for the enhancement of relaxivity observed with this agent.