MRI对经皮肝穿射频消融治疗肝癌的疗效评价

目的 评价MRI对经皮超声引导射频消融治疗肝癌术近期疗效的价值。方法 对80例经皮超声引导射频消融治疗肝癌术中的48例患者进行了MRI随访观察。结果 经皮超声引导射频消融治疗肝癌术后病灶随着时间的改变而其MRI表现各有不同。病灶早期(1个月内)T1WI中央区呈高信号或稍高信号,周围呈环行低信号,PDWI和T2WI病灶中央区呈低信号,周围则呈环行高信号。静脉注射Gd-DTPA后中央区无强化,而边缘则呈环行强化。半年后随访病灶则T1WI、PDWI、T2WI则均呈低信号,且无强化。结论 MRI对局部组织损伤后是否存在出血,含铁血黄素的改变,以及判定局部是否存在水肿有着重要的作用。外周环行异常信号区的大小是判断毁损灶大小的最合适标志。其大小与疗效明显相关。     

MRI对经皮肝穿射频消融治疗肝癌的疗效评价

目的 评价MRI对经皮超声引导射频消融治疗肝癌术近期疗效的价值。方法 对80例经皮起声引导射频消融治疗肝癌术中的48例患进行了MRI随访观察。结果 经皮超声引导射频消融治疗肝癌术后病灶随着时间的改变而其MRI表现各有不同。病灶早期(1个月内)T1WI中央区呈高信号或稍高信号，周围呈环行循信号，PDWI和T2WI病灶中央区呈低信号，周围则呈环行高信号。静脉注射Gd—DTPA后中央区无强化，而边缘则呈环行强化。半年后随访病灶则T1WI、PDWI、T2WI则均呈低信号，且无强化。结论 MRI对局部组织损伤后是否存在出血。含铁血黄素的改变，以及判定局部是否存在水肿有着重要的作用。外周环行异常信号区的大小是判断毁损灶大小的最合适标志。其大小与疗效明显相关。     

3.0 T MR扩散加权成像评价兔肝VX2瘤射频消融治疗的实验研究

目的 探讨3.0 T MR DWI评价兔肝VX2瘤射频消融治疗疗效的价值.方法 新西兰大白兔22只.20只用于建立VX2瘤模型,2只健康正常兔用于行正常肝射频消融术对照.于VX2瘤种植后14～21 d(平均17 d),对符合实验条件瘤兔(病灶位于肝实质内,最大直径≤3 cm,坏死病灶直径≤整个病灶直径的1/2)行3.0 T常规MRI和功能DWI.对瘤兔及对照组正常兔行射频消融治疗,射频消融术后7～10 d(平均8 d)行3.0 T常规MRI及DWI.所有射频消融治疗兔行MR检查后均行病理检查.测量兔肝VX2瘤、正常兔肝射频消融治疗前后ADC值,分析兔肝VX2瘤射频消融治疗前后3.0 T MR常规成像、ADC值特征,并与病理对照.同一b值射频消融治疗后不同组织间ADC值比较采用重复测量资料方差分析.结果 20只实验组兔肝VX2瘤模型均建立成功,1例肿瘤突出于肝表面、1例肿瘤病灶出现明显坏死未纳入实验.所有18个瘤灶及2例正常兔肝射频消融均成功.兔VX2瘤T1WI序列表现为低或等信号,T2WI为高信号.肝VX2瘤兔射频消融治疗后7～10 d,射频消融病灶T1WI序列表现为低或稍高信号,T2WI为混杂信号.T2WI序列周边环形稍高信号为肉芽组织,增强扫描明显强化,T2WI序列低、中等信号为凝固性坏死.坏死组织在DWI图上为低信号,活性肿瘤组织位于病灶周边,呈结节状,在T2WI、DWI图上为等或稍高信号.肿瘤标本为灰白色,部分肿瘤组织间夹杂增生血管、少许肉芽组织.b值为600 s/mm2时,射频消融治疗后活性肿瘤组织(9只)、坏死组织(18只)、肉芽组织(18只)、正常组织(18只)ADC值分别为:(1.227±0.140)×10-3、(0.702±0.050)×10-3、(1.918±0.124)×10-3、(1.739±0.044)×10-3mm2/s,各组间ADC值差异具有统计学意义(P＜0.01).b值分别为200、400、600、800、1000 s/mm2时治疗后坏死组织、活性残留或复发肿瘤组织、肉芽组织、正常肝组织间ADC值差异具有统计学意义(P＜0.01).结论 兔VX2瘤模型适合3.0 T MR评价射频消融治疗疗效的动物实验研究,对射频消融治疗基础及临床应用研究具有重要价值.     

3T MR扩散加权成像对肝脏转移瘤的诊断价值初探

目的:探讨MR扩散加权成像(DWI)对肝脏转移瘤的诊断价值.方法:对临床确诊的25例肝脏转移瘤患者进行DWI、T2WI及Gd-DTPA-T1WI扫描,观察肝脏转移瘤的信号特征,并统计分析3种序列所检出的转移瘤数目.结果:对于直径大于1.0 cm的32个转移瘤灶,3种序列都准确检出;而直径小于1.0 cm的微小转移瘤,在T2WI上共检出76个,病灶信号均为略高信号;在DWI上共栓出85个,呈高信号;在增强门脉期T1WI上共检出68个,大部分瘤灶呈环状强化或不均匀强化.3种序列对转移瘤的检出差别无显著性意义.结论:DWI对肝脏微小转移瘤的敏感性较高,将DW与T2W、GD-DTPA-T1W 3种序列相结合,可以互相弥补各序列不足之处,将大大提高肝脏微小转移瘤灶的检出率.     

为什么部分肝脏局灶病变在超顺磁氧化铁增强T_1WI上呈现高信号

目的:探讨肝脏病变在SPIO增强扫描T1WI上呈现高信号的机制.方法:肝脏局灶病变39例(56个病灶),其中33个恶性病灶(肝细胞癌10个、转移瘤21个、胆管细胞癌2个)和良性病灶23个(海绵状血管瘤9个,肝囊肿14个).平扫序列包括SE T1WI、FSPGR T1WI及FSE T2WI.SPIO(菲立磁)增强扫描序列包括FSE T2WI、SE T1WI(TE值分别为8 ms、20 ms)和 FSPGR T1WI(TE值分别为1.5 ms、4.2 ms).分析不同序列图像上病灶及肝实质的的信号变化.结果:在SPIO增强T1WI上,随着TE的延长,肝实质信号降低,肝内局灶病变信号相对增高.在SPIO增强长TE T1WI上,大部分恶性病灶及全部血管瘤呈相对高信号.结论:在SPIO增强T1WI上,SPIO对肝实质的T2*效应可能是部分局灶病变呈高信号的主要原因.     

肝脏肿瘤微波消融后MRI信号演变解读

目的 对肝脏恶性肿瘤微波消融(MWA)术后MRI信号随时间的演变进行解读.方法 56例患者共56个肝肿瘤病灶,在MWA术后第2天、1个月、6个月行上腹部MRI平扫及增强扫描.观察不同时间点消融区T1WI、T2WI、DWI及增强扫描的信号变化,并判断是否存在肿瘤复发.结果 MWA后2d,消融区在T1WI、T2WI序列表现为靶样结构,T1WI表现为中央高信号的消融坏死区与周围环绕的低信号带,T2WI表现为低信号的消融坏死区及周围环绕的高信号带;术后1个月及6个月消融区体积萎缩,T1WI及T2WI仍可见靶样结构,T1WI显示消融坏死区信号升高.增强扫描显示MWA后2d,消融区周围存在异常高灌注,术后2d、1个月及6个月消融坏死区均无强化.DWI序列显示消融后2d,消融区周围反应性信号增高,术后1个月及6个月信号逐渐降低.结论 肝脏肿瘤MWA术后消融区信号变化是随时间演变的过程,对消融区MRI信号的正确解读有助于疗效判断及方案制定.     

小脑延髓池孤立性纤维瘤一例

患者 女,50岁.头痛2年,加重4个月.体检未发现明显阳性体征.MR检查:小脑扁桃体下缘与延髓之间可见大小约3.8 cm×3.5 cm×3.2 cm的异常信号影.T1WI呈等、低信号(图1),T2WI呈等、稍高信号(图2),病灶信号不均匀,边缘清晰,周围未见水肿灶.     

肝脏局灶性结节增生的典型与非典型MR表现及其病理基础

目的:研究肝脏局灶性结节增生(FNH)的典型与非典型MR表现及其病理基础,探讨MRI对各型的诊断价值。方法:分析经手术病理证实的FNH 28例(36个病灶)的典型与非典型MR表现,并与病理结果相对照。结果:①典型表现20例(28个病灶),大小在2.0~10.5cm,T1WI上呈等/稍低信号,T2WI上呈等/稍高信号,增强扫描动、门脉期病变呈显著增强,延迟扫描呈等/略高信号,中心瘢痕出现率占42.9%(12/28例),于T1WI上呈低信号,T2WI上呈高信号,增强扫描呈延迟强化。组织学上有特征性的中央纤维瘢痕,由纤维结缔组织和扭曲的血管组成,并向外放射状形成许多纤维间隔,纤维间隔旁围绕以无明显异形性的肝细胞形成硬化样结节;②非典型表现8例(8个病灶),大小在1.5~8.5cm,T1WI呈略高或低信号,T2WI呈不均匀高信号,增强扫描病灶强化不显著、不均匀,病灶内未见中心瘢痕或瘢痕不强化,出现假包膜等。镜下病变内毛细胆管扩张,其内纤维分隔较短、不连续,部分较大病灶内有出血、脂肪变及坏死,但无异型性肝细胞。结论:MRI能很好反映肝脏局灶性结节增生的典型与非典型表现的病理基础,具有高度的诊断特异性。     

肝脏炎性肌纤维母细胞瘤的影像表现

目的 探讨肝脏炎性肌纤维母细胞瘤(IMT)的影像表现特征,以提高影像诊断水平.方法 回顾性分析经手术病理证实的12例肝脏IMT的影像表现,其中12例均行CT扫描,2例行MR检查.结果12例单发病灶均位于肝右叶.6例肿块为实性,4例肿块为囊实混合性,2例表现为门静脉周围浸润性病灶.CT图像上呈实性或囊实性低密度影,MR T1WI为低信号,T2WI为略高信号;增强扫描肿块实性部分呈均匀或不均匀中重度强化,囊实混合性病灶周边及灶内实性间隔呈蜂窝样强化.结论CT及MR检查能为临床诊断及鉴别诊断肝脏IMT提供有价值的信息.     

磁敏感加权成像对脑部恶性肿瘤的诊断价值

目的:探讨磁敏感加权成像(SWI)技术对脑部恶性肿瘤诊断的应用价值.材料和方法:搜集30例经手术及病理证实的脑恶性肿瘤患者资料,其中胶母细胞瘤13例、间变性脑膜瘤6例、恶性室管膜瘤4例、恶性生殖细胞瘤4例、转移瘤3例.全部病例行T1WI、T2WI、增强T1WI及SWI序列检查,对结果进行对比分析.结果:19例病灶内见散在T1WI低信号、T2WI等或高信号灶,无法鉴别坏死或出血,11例病灶内等信号,全部病灶增强T1WI强化不均.SWI序列病灶内可见较T1WI、T2WI异常信号范围更大的低信号出血灶,无异常信号的病灶内出现低信号出血灶,有14例显示低信号肿瘤引流静脉.结论:SWI序列可以显示肿瘤内常规MRI序列无法判断性质或不能显示的出血及肿瘤静脉血管,对恶性肿瘤的诊断具有较大价值.     

原发性肝细胞癌射频消融治疗后MR动态随访研究

目的 探讨原发性肝细胞癌射频消融(RFA)治疗后的MR随访表现特征及规律.方法 回顾性分析2008年8月至12月住院的110例原发性肝细胞癌患者RFA治疗后的MR资料,根据MR检查时间分为3组:消融后48 h内、1～6个月、6个月以上.采用卡方检验分析比较肝细胞癌RFA治疗后肿瘤MR表现的动态变化.结果 110例短期(48 h内)RFA区域在GRE-TtWI表现为高信号,快速自旋回波(TSE)-T2WI则呈低信号,增强扫描无强化.1～6个月,GRE-T1WI示RFA区域信号呈不均匀下降,72例呈高信号,4例呈等低信号;＞6个月时,60例呈高信号,17例呈等低信号,此改变在6个月后与48 h内和1～6个月比较差异均有统计学意义(P值均＜0.015).TSE-T2WI示RFA区域信号呈不均匀轻度增高,1～6个月,65例呈低信号,11例呈等信号;＞6个月时,47例呈等信号,30例呈低信号,而此信号改变在6个月后与48 h内和1～6个月比较差异均有统计学意义(P值均＜0.015).增强后早期RFA区域主要表现为环状强化伴或不伴异常灌注,而随着时间延长趋向无强化,1～6个月,37例无强化;＞6个月,63例无强化,此改变在3组间差异均有统计学意义(P值均＜0.015).6例肿瘤残留或局部进展,表现RFA区边缘结节,TSE-T2WI抑脂像呈中等高信号,GRE-T1WI呈低信号并伴有不同程度的强化.结论 原发性肝细胞癌RFA治疗后,动态MR随访能显示肿瘤完全坏死、肿瘤残留或局部进展及并发症的相关特征.     

Use of Semiflexible Applicators for Radiofrequency Ablation of Liver Tumors

Purpose To evaluate the feasibility and potential advantages of the radiofrequency ablation of liver tumors using new MRI-compatible semiflexible applicators in a closed-bore high-field MRI scanner. Methods We treated 8 patients with 12 malignant liver tumors of different origin (5 colorectal carcinoma, 2 cholangiocellular carcinoma, 1 breast cancer) under MRI guidance. Radiofrequency ablation (RFA) was performed using 5 cm Rita Starburst Semi-Flex applicators (Rita Medical Systems, Milwaukee, WI, USA) which are suitable for MR- and CT-guided interventions and a 150 W RF generator. All interventions were performed in a closed-bore 1.5 T high-field MRI scanner for MRI-guided RFA using fast T1-weighted gradient echo sequences and T2-weighted ultra-turbo spin echo sequences. Control and follow-up MRI examinations were performed on the next day, at 6 weeks, and every 3 months after RFA. Control MRI were performed as double-contrast MRI examinations (enhancement with iron oxide and gadopentetate dimeglumine). All interventions were performed with the patient under local anesthesia and analgo-sedation. Results The mean diameter of the treated hepatic tumors was 2.4 cm (±0.6 cm, range 1.0–3.2 cm). The mean diameter of induced necrosis was 3.1 cm (±0.4 cm). We achieved complete ablation in all patients. Follow-up examinations over a duration of 7 months (±1.3 months, range 4–9 month) showed a local control rate of 100% in this group of patients. All interventions were performed without major complications; only 2 subcapsular hematomas were documented. Conclusion RFA of liver tumors using semiflexible applicators in closed-bore 1.5 T scanner systems is feasible. These applicators might simplify the RFA of liver tumors under MRI control. The stiff distal part of the applicator facilitates its repositioning.     

MR-guided radiofrequency ablation of hepatic malignancies at 1.5 T: initial results

Purpose

To assess the feasibility of magnetic resonance (MR)‐guided radiofrequency ablation (RFA) of hepatic malignancies using a high‐field MR scanner.

Materials and Methods

A total of 10 patients with 14 primary (N = 1) or secondary (N = 13) hepatic malignancies underwent MR‐guided RFA using a closed‐bore 1.5 T MR scanner. Lesion diameters ranged from 2.0 cm to 4.7 cm. RFA was performed using a 200‐W generator in combination with a 3.5‐cm LeVeen electrode applying a standardized energy protocol.

Results

RFA was technically feasible in all patients. Necrosis diameter ranged from 2.5 cm to 6.8 cm. The mean follow‐up period is 12.2 ( 1 - 18 ) months. In nine out of 10 patients, local tumor control was achieved. For this purpose, a second CT‐guided RFA was required in two patients. In four patients, multifocal hepatic tumor progression occurred, with the treated lesion remaining tumor‐free in three of these patients. Two patients showed extrahepatic tumor progression. Four patients remained tumor‐free. No major complications occurred.

Conclusion

MR‐guided RFA of hepatic malignancies in a closed‐bore high‐field MR scanner is technically feasible and safe. It can be advantageous in locations considered unfavorable for CT‐guided puncture or in patients in which iodinated contrast material is contraindicated. J. Magn. Reson. Imaging 2004;19:342–348. © 2004 Wiley‐Liss, Inc.

     

磁共振成像在诊断颅内海绵状血管瘤中的应用价值

目的分析颅内海绵状血管瘤(cerebral cavernous malformations,CCMs)常规MRI序列表现及MRI磁敏感加权成像(susceptibility weighted imaging,SWI)的诊断价值。资料与方法回顾性分析50例经病理证实的CCMs患者的MRI资料,比较常规MRI序列(T1WI和T2WI)和SWI表现、检出率和病灶大小,判断其对CCMs的诊断价值。结果 50例共捡出97个病灶,22个病灶可见短T1信号伴出血,常规MRI对出血病灶具有多种表现形式;75个病灶未见短T1信号不伴出血。49个病灶T2WI灶周具有"铁环征";97个病灶中有48个病灶在T1WI或T2WI上呈"网格"状或"桑椹"状高、低混合信号;8个病灶T1WI、T2WI均呈高信号;6个病灶T1WI、T2WI均呈低信号;3个病灶T1WI呈等信号、T2WI呈稍低信号。SWI显示的病灶范围包括瘤体及灶周含铁血黄素区域,病灶信号不均匀性降低;SWI上90个病灶显示均匀或不均匀黑色信号,7个病灶显示混杂信号影。T1WI、T2WI、SWI对出血性病灶的检出率均为100%,SWI对非出血性病灶检出率为100%,显著高于T1WI和T2WI(18.6%和40.0%,P<0.05)。SWI显示出血性瘤体大小为(3.3±1.2)cm,显著大于T1WI和T2WI[(2.0±0.6)cm和(2.6±0.9)cm,P<0.05];SWI显示非出血性瘤体大小为(3.1±1.1)cm,显著大于T1WI和T2WI[(1.7±0.6)cm和(2.3±0.8)cm,P<0.05]。结论 MRI是诊断CCMs的首选方法,常规序列结合SWI序列能提供更准确和更全面的诊断信息。     

MR-guided radiofrequency ablation in a 0.2-T open MR system: technical success and technique effectiveness in 100 liver tumors

PURPOSE: To evaluate the feasibility and technique effectiveness of magnetic resonance (MR)-guided radiofrequency (RF) ablation of hepatic malignancies. MATERIALS AND METHODS: In 64 patients, 100 primary (N = 19) or secondary (N = 81) liver tumors (mean diameter = 24.7 mm; range = 4-60 mm) were treated with 87 sessions of MR-guided RF ablation. The entire ablation procedure was carried out at an 0.2-T open MR system by using MR-compatible internally cooled electrodes. T2-weighted turbo spin echo sequences (TR/TE = 3500 msec/110 msec) were used to monitor thermally induced coagulation. Technique effectiveness was assessed four months after the last RF ablation by dynamic MR imaging at 1.5-T. RESULTS: MR-guided RF ablation procedures were technical successful in 85 of 87 (97.7%) assessed at the end of each session. Complete coagulation was intended in 99 of 100 tumors. Technique effectiveness was observed in 92 of 99 (92.9%) of these tumors. To achieve complete coagulation 82 of 92 (89.1%) tumors required a single session. T2-weighted sequences were accurate to monitor the extent of coagulation and were supportive to guide overlapping ablation. There were two of 87 (2.3%) major and seven of 87 (8.0%) minor complications. CONCLUSION: MR-guided RF ablation is a safe and effective therapy in the treatment of hepatic malignancies. MR imaging offers an accurate monitoring of thermally-induced coagulation, thus enabling complete tumor coagulation in a single session.     

肝肿瘤经皮射频切除术后CT表现

目的 研究肝肿瘤经皮射频切除术后病灶及周围肝实质的CT表现。材料与方法 回顾性分析32例肝肿瘤患者（原发性肝癌28例,转移性肝癌4例）共40个病灶经皮射频切除术前后CT表现。CT检查采用普通或螺旋CT扫描,后者增强扫描为双期螺旋扫描。结果 术后平扫治疗区为低密度,范围增大,大多数边界不清。增强扫描低密度区边界清晰。29个病灶（肿瘤大小1．5－4．3cm,平均3．1cm）治疗区无强化,11个病灶（肿瘤大小4．9－11．0cm,平均6．4cm)仍见残留癌灶强化。其他征象有：治疗区周围强化,病灶内出血、含气,胸水和腹水。结论 肝肿瘤经皮射频切术后CT检查,特别是增强扫描对评估治疗效果和发现并发症有很大价值。     

Magnetic resonance-guided percutaneous radiofrequency ablation of renal cell carcinomas: a pilot clinical study

OBJECTIVE: The objective of this study was to assess the feasibility and efficacy of magnetic resonance imaging-(MRI) guided percutaneous radiofrequency (RF) ablation of renal cell carcinomas (RCC). SUBJECTS AND METHODS: Twelve patients with RCC (63 to 82 years old) were treated with RF ablation in an interventional 0.2-Tesla open MR unit. Tumor sizes varied from 1.6 cm to 3.9 cm in maximum diameter (tumor volumes 1.9 cm3 to 28.7 cm3). RF procedures were entirely performed in the MR suite. For positioning of the MR-compatible RF-electrode, near real-time MR fluoroscopy by means of rapid gradient echo sequences (acquisition time approximately 2 seconds) was used. Monitoring of ablation was obtained by intermittent imaging with T1- and T2-weighted spin echo sequences. RESULTS: Accurate placement of the RF electrodes was possible in all cases using near real-time MR fluoroscopy. Eleven of 12 patients were successfully treated within 1 single session; 1 patient had to be retreated for tumor relapse at 13 months follow up. Mean number of electrode repositionings under MR guidance during 1 session was 1.7; ablation time ranged between 12 and 28 minutes. Mean duration of 1 treatment session was 5 hours. Coagulation volumes ranged from 7.3 cm3 up to 30.2 cm3. All patients now appear to be disease-free with a mean follow up of 10.3 months (range, 3-23 months). CONCLUSION: MRI-guided RF ablation of RCC in an interventional MR unit is safe and feasible. Fast MR imaging is a convenient method for rapid positioning of MR-compatible RF electrodes. MR monitoring of ablation procedure with T2-weighted imaging allows for immediate assessment of coagulation extent.