多模态MRI技术对颅内单发环形强化病变的诊断价值

The value of multimodal MRI in intracranial solitary ring-enhancing lesions

目的分析多模态磁共振成像(MRI)技术对颅内单发环形强化病变的诊断价值。方法40例经临床确诊或病理证实环形强化病变患者,包括18例高级别胶质瘤(HGG)、14例脑脓肿(BA)及8例脑转移瘤(SBM)。分析病变的MRI常规序列、弥散加权成像(DWI)、灌注加权成像(PWI)、磁共振波谱(MRS)及磁敏感加权成像(SWI)特点。观察分析常规MRI表现、多模态MRI表现,比较3种病变不同位置表观扩散系数(ADC)、相对脑血容量(rCBV)、胆碱/肌酸(Cho/Cr)、N-乙酰天门冬氨酸/肌酸(NAA/Cr)。结果HGG:形态不规则,瘤壁厚薄不均,16例内壁伴结节、外壁毛糙,平扫呈T1WI等、T2WI等信号,增强不均匀环形强化,病变周围中至重度水肿。其中12例侵犯周围脑组织;BA:形态规则,11例呈均匀薄壁,3例厚薄不均内壁伴结节,平扫呈T1WI等、T2WI稍低高信号。增强较均匀环形强化,病变周围重度水肿。其中4例内部伴液-液平面;SBM:形态局限,呈类圆形,位于皮髓质交接区。瘤壁稍厚,内壁毛糙,外壁光整,平扫呈T1WI等、T2WI稍高信号,增强不均匀环形强化,病变周围重度水肿。DWI:HGG及SBM瘤壁弥散受限,ADC略升高,BA内部弥散受限明显,信号明显增高,ADC明显减低,HGG水肿区ADC明显低于BA、SBM,差异有统计学意义(P<0.05);PWI:灌注强度HGG>SBM>BA,rCBV不同程度升高。3种病变内部坏死区均呈低灌注,HGG周围水肿rCBV高于BA、SBM,差异有统计学意义(P<0.05);MRS:MRS显示HGG水肿区Cho/Cr高于BA、SBM,NAA/Cr低于BA、SBM,差异有统计学意义(P<0.05);SWI:17例HGG瘤壁旁见弥漫分布极低信号,5例SBM周围见小范围点状极低信号。结论HGG、BA与SBM常规MRI影像学征象存在重叠现象,鉴别诊断有时困难。多模态MRI技术可综合评价颅内环形强化病变,有助于临床定性诊断。

Objective To analyze the value of magnetic resonance imaging(MRI)in the diagnosis of intracranial solitary ring-enhancing lesions.Methods There were 40 patients with ring-enhancing lesions clinically confirmed or pathologically confirmed,including 18 high-grade gliomas(HGG),14 brain abscesses(BA),and 8 solitary brain metastases(SBM).The characteristics of conventional MRI sequence,diffusion weighted imaging(DWI),perfusion weighted imaging(PWI),magnetic resonance spectroscopy(MRS),and susceptibility weighted imaging(SWI)of the lesion was analyzed.The conventional MRI and multimodal MRI findings were observed and analyzed.The apparent diffusion coefficient(ADC),relative cerebral blood volume(rCBV),choline/creatine(CHO/Cr)and N-acetylaspartate/creatine(NAA/Cr)levels at different locations of the three lesions were compared.Results HGG:irregular shape,uneven tumor wall thickness,16 cases of inner wall with nodules,rough outer wall,plain scan showed T1WI and other T2WI signals,enhanced uneven ring enhancement,moderate to severe edema around the lesion,of which 12 cases invaded the surrounding brain organization.BA:regular morphology,11 cases showed uniform thin wall,3 cases with uneven inner wall with nodules,plain scan showed slightly low and high signal on T2WI such as T1WI;enhanced more uniform ring enhancement,severe edema around the lesion,including 4 cases with liquid-liquid level.SBM:limited in shape,round in shape,located at the junction of cortex and medulla;the tumor wall was slightly thick,the inner wall was rough,the outer wall was smooth,plain scan showed slightly high signal on T1WI and T2WI,uneven enhancement,ring enhancement,severe edema around the lesion.DWI:diffusion of HGG and SBM tumor wall was limited,ADC slightly increased,BA internal diffusion was limited,signal significantly increased,ADC significantly decreased,ADC of HGG edema area was significantly lower than BA,SBM,the difference was statistically significant(P<0.05);PWI:perfusion intensity HGG>SBM>BA,rCBV increased in varying degrees.The internal necrosis areas of the three kinds of lesions were all hypoperfused,and the rCBV of edema around HGG was higher than that of BA and SBM,and the difference was statistically significant(P<0.05);MRS:MRS showed that the Cho/Cr of HGG edema area was higher than those of BA and SBM,and the NAA/Cr was lower than BA and SBM,the difference was statistically significant(P<0.05);SWI:17 cases of HGG showed diffusely distributed very low signal next to the tumor wall,and 5 cases of SBM had small spot-like very low signal around.Conclusion The conventional MRI imaging signs of HGG,BA and SBM are overlapped,and the differential diagnosis is sometimes difficult.Multimodal MRI technology can comprehensively evaluate intracranial ring-enhancing lesions,which is helpful for clinical qualitative diagnosis.