Analysis of ischemic cerebral lesions using 3.0-T diffusion-weighted imaging and magnetic resonance angiography after revascularization surgery for ischemic disease

Background

Cerebral revascularization surgery (CRS) is increasingly recognized as an important component in the treatment of complex cerebral vascular disease and tumors. CRS requires that the incidence of perioperative neurological complications should be minimized, because CRS for ischemic disease is often not the goal of treatment, but rather a prophylactic surgery. CRS carries the risk of focal postoperative neurological deficits. Little has been established concerning mechanisms of post-CRS ischemia. We used 3.0-T diffusion-weighted magnetic resonance imaging (DWI) and magnetic resonance angiography (MRA) to analyze the incidence and mechanism of ischemic lesions.

Methods

We studied the anterior circulation territory after 20 CRS procedures involving 33 vascular anastomosis procedures (13 double anastomoses and 7 single anastomoses) in 12 men and 8 women between June 2007 and October 2011. The operations included single or double superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis to treat internal carotid artery/MCA occlusions or severe MCA stenosis. A combined STA–MCA anastomosis and indirect bypass were performed for moyamoya disease. Postoperative DWI and MRA were obtained in all patients between 24 and 96 h after surgery to detect thromboembolism, hypoperfusion, or procedural ischemic complications and vasospasms of the donor STA.

Results

Follow-up DWI and MRA were carried out 1.8 ± 0.6 days after CRS (range, 1–4 days). Temporary occlusion time for anastomoses averaged 18.9 min (range, 16–32 min). Asymptomatic new hyperintensities occurred in the ipsilateral hemisphere of 2 patients on postoperative DWI (10% patients/6.0% anastomoses), and 1 moyamoya patient (5.0% patients/3.0% anastomoses) developed a symptomatic hyperintensity in the ipsilateral occipital lobe in response to the operation. Two abnormal small (<5 mm) cortical DWI lesions were caused by sacrifices of a small branch of the recipient MCA.

Conclusion

This study is the first postoperative 3.0-T DWI study of CRS and related clinical events. The incidence of symptomatic postoperative DWI abnormalities was restricted to 1 moyamoya patient representing 5.0% of total patients and 3.0% anastomoses. Although some postoperative DWI abnormalities occurred, CRS was found to be safe with a low risk of symptomatic ischemia.     

静脉注射Gd－DTPA在三维TOF法磁共振脑血管成像中的应用价值

为了降低饱和作用, 提高单体积三维TOF法静脉血管及动脉小分支的显示能力, 我们采用了静脉注射造影剂(Gd-DTPA)的方法缩短血液的T1值, 减少饱和作用影响。结果表明, 增强MRA不但动脉小分支显示能力提高, 而且扫描层面内的重要脑内静脉血管结构显示很清楚, 血管的CNR提高。增强MRA短时间内同时显示高分辨率的动静脉血管结构将明显提高MRA的临床应用价值, 减少对静脉血管疾病的遗漏。     

PWI联合MRA评价侧支循环在后循环远端缺血中的代偿作用

目的 探讨磁共振灌注加权成像(PWI)联合磁共振血管造影(MRA)评价侧支循环在后循环远端缺血中的代偿作用.方法 搜集32例伴有椎基底动脉重度狭窄的后循环缺血患者(病例组),分析PWI和MRA检查资料,并与30名健康志愿者(对照组)比较,观察后循环血管狭窄程度,侧支血管的显示,局部脑血流量(rCBF)、局部脑血容量(rCBV)、平均通过时间(rMTT)指标.结果 病例组中后交通动脉开放22例;软脑膜动脉显示11例;微小动脉团显示12例.病例组ROL/额叶白质比值相对于对照组rCBF、rCBV值均下降,MTT值延长,两组参数比较P值均＜0.05,有统计学差异.病例组中有后交通开放的患者与未开放的患者比较,rCBF升高,MTT缩短,P值均＜0.05;而rCBV两组间比较,P值=0.36(＞0.05),无统计学差异.结论 PWI联合MRA可以客观地评价后交通动脉在后循环远端缺血中的代偿作用,为临床治疗及判断预后提供帮助.     

两种上肢磁共振血管成像检查方法的对比分析

目的：对比磁共振血管成像（ MRA）检查上肢血管疾病的2种方法,探讨移床技术的优势。方法对20例临床诊断有上肢血管疾病的患者分2组进行非移床血管示踪三维动态MRA和移床血管示踪三维动态MRA检查。结果20例均显示出清晰的上肢病变血管（动静脉畸形、血管瘤等）。其中8例显示全程上肢血管影像,供血走向清晰。结论上肢移床血管示踪MRA与非移床MRA比较,具有更好的连续性,能更全面地判定上肢血管病变性质,是更值得推广的检查方法。     

颈动脉体瘤的MR诊断

目的:探讨MR诊断颈动脉体瘤(CBT)的价值。材料与方法:4例经手术病理证实的CBT进行MRI和MRA检查。结果:4例CBT MR检查均显示颈总动脉分叉(common cartid artery bifurcation,CCAB)处类圆形或椭圆形肿瘤,包绕颈内、外动脉,T_1WI呈等或略高信号,T_2WI呈高信号;包膜完整。T_1WI、T_2WI均呈低信号。肿瘤中见多发蜿蜓纡曲的肿瘤小血管。MRA均示CCAB角杯状扩大及肿瘤血管丛。结论:MR不仅能直接显示肿瘤部位、形态、大小及颈动脉关系,也能显示肿瘤血管及CCAB角扩大,是CBT诊断与鉴别的理想方法。     

乳腺癌的动态增强MRA的特点研究

目的探讨乳腺癌的动态增强MRA特点。方法选取2009年7月到2014年3月期间行乳腺常规MRI及动态增强MRA检查的51例乳腺病变患者,扫描序列有T1WI、T2WI-STIR及dyn-THRIVE动态增强,动态扫描时间间隔46 s。连续扫描12个时相,获取动脉早期、动脉晚期及静脉期3期图像。手术病理证实乳腺癌14例共16个病灶。观察乳腺的动态增强MRA特点及动态增强MRA动脉早期、动脉晚期、静脉期乳腺癌与邻近正常乳腺实质或健侧乳腺实质的信号比值差异。结果乳腺癌动态增强MRA特点:瘤体动态显现,自动脉早期信号明显增强,周围有多支或粗大供血血管,动脉晚期可见增粗回流静脉。动脉早期、动脉晚期、静脉期乳腺癌与邻近正常乳腺实质或健侧乳腺实质的信号比值分别约1.56±0.32、1.48±0.35、1.45±0.30。结论结合动态增强MRA的恶性新生肿瘤血管、瘤体染色特点,有助于诊断乳腺癌。