脾脏硬化性血管瘤样结节性转化的MRI表现

MRI Findings of Sclerosing Angiomatoid Nodular Transformation of the Spleen

目的探讨脾脏硬化性血管瘤样结节性转化(SANT)的MRI特征。方法回顾性分析10例经手术病理证实的脾脏SANT患者的MRI资料,总结其影像特征。10例均行MR平扫及多期增强扫描,其中7例行扩散加权成像(DWI)及双回波同反相位磁共振成像(IP/OP)。结果 (1)单发9例,均为类圆形肿块,4例(44.4%)见假包膜;T1WI呈等或低信号;T2WI呈不均匀低信号8例(88.9%),不均匀稍高信号1例(11.1%);动态增强扫描均为向心性、渐进性强化,其中辐条轮状强化7例(77.8%),明显结节样强化2例(22.2%),延迟期呈等或高信号,内均见裂隙;7例DWI检查中,低信号6例(85.7%),等信号1例(14.3%);病灶内出血2例(22.2%),均未见坏死囊变。(2)多发1例,表现为脾内弥漫分布的类圆形小结节(>10个),T1WI均为等信号,T2WI为高信号,增强扫描渐进性强化。结论单发脾SANT的MRI表现有一定的特征性,特别是病灶周围假包膜有助于本病的诊断;多发SANT与脾脏其他脉管性肿瘤鉴别困难。

Objective To investigate the MRi features of sclerosing angiomatoid nodular transformation （SANT） of the spleen in order to improve its diagnostic accuracy. Methods The imaging materials of 10 patients with pathologically- proved SANT were retrospectively analyzed and the imaging features were summarized. Both plain and dynamic enhanced MRI were performed in all 10 patients, and additional diffusion weighted imaging （DWI） and dual echo reverse phase （in/ out-of-phase imaging, IP/OP） MRI was employed in 7 palients. Results （ 1 ） Solitary lesion was seen in 9 patients, and pseudocapsule was observed in 4 patients （44.4%） ; the lesion was iso-intense or hypo-intense on TI WI; on T2WI the lesion was inhomogeneous hypo-intense （ n = 8, 88.9% ）, or inhomogeneous slightly hyper-intense （ n = 1, 11.1% ）. On dynamic enhanced scan, the lesion showed concentric and progressive enhancement; spoke-wheel shaped enhancement pattern was seen in 7 patients （77.8%） , obvious nodular enhancement with iso- or hyper-intensity signal on delayed scan in 2 patients （22.2%）. DWI was performed in 7 patients, among them the lesion presented as lower signal in 6 （85.7%） and iso-signal in one （ 14.3% ）, and hemorrhage within the lesion was detected in 2 （22.2%）, and no necrosis or cystic degeneration was observed. （2） Multiple nodules were seen in one patient, which was characterized by diffusely distributed round small nodules （more than 10 nodules）, presenting iso-signal on T1WI, hyper-signal on T2WI and progressive enhancement. Conclusion Solitary SANT has certain MRI characteristics, which, especially the presence of pseudocapsule around the lesion, are helpful for the diagnosis. The differentiation of multiple SANT from other splenic vascular tumors is usually difficult.