基底节区小血肿与小钙化灶的磁敏感加权成像相位图表现

摘要

Objective To investigate the imaging characteristics of small hematoma and calcification in basal ganglia on phase images derived from magnetic resonance susceptibility weighted imaging(SWI) and its differentiating value between these two entities. Methods 22 cases with ovoid high density lesions smaller than 1 cm in size in the basal ganglia detected by initial head CT underwent SWI were retrospectively analyzed,of which, 14 cases with calcic foci and 8 cases with small hematomas. SWI characteristics of both calcification and hematoma were compared. Results Small calcifications and hematomas in basal ganglia all appeared as ovoid high density on CT and the CT attenuation ranged from 50 HU to 120 HU,iso- or slightly hyper-low signal intensity on T2WI, low or iso- or slightly hyper-signal intensity on T1 WI without brain edema or obvious space occupying effect,and showed low signal intensity on magnitude images derived from SWI. On phase images, the central slice of small calcifications showed heterogeneous signal intensity surrounded by high signal ring and low signal in two poles along Z axis (perpendicular to the axial plane, parallel to the magnet) , while central slice of small hematomas showed heterogeneous signal intensity surrounded by low signal ring and high signal in two poles along Z axis, which was opposite to the characteristics of small calcification. Conclusion The susceptibility weighted phase imaging features of small ovoid calcifications and hematomas in the basal ganglia are characteristic, which can be used for differential diagnosis reliably.%目的 探讨基底节区小血肿和小钙化灶磁敏感加权成像(SWI)相位图表现及其鉴别诊断价值.方法 回顾性分析CT初检基底节区直径＜1 cm的类圆形高密度病灶共28例,其中钙化灶18例,小血肿10例,进行磁共振磁敏感加权成像检查,比较2种病理改变的磁敏感加权成像特点.结果 基底节区小钙化灶及小血肿CT均表现为类圆形高密度影,CT值50～120 HU,T2WI表现为等、稍低或低信号影,T1WI表现为低、等或稍高信号影,无周围水肿,占位效应轻微,磁敏感加权成像幅度图像均显示为低信号影,小钙化灶相位图中间层面表现为高低混杂信号及周围环形高信号影,Z轴方向(与横断面垂直的方向)上下两极层面呈低信号,小血肿中间层面表现为高低混杂信号及周围环形低信号,Z轴上下两极层面呈高信号.结论 基底节区类圆形小钙化灶和小血肿SWI相位图像表现具有特征性,能够可靠地进行鉴别诊断.