乳腺肿瘤的MRI扩散特征及参数选定

目的探讨MR扩散加权成像（DWI）不同扩散敏感因子（b）值对鉴别乳腺良恶性病变的价值。方法测定83例患者95个乳腺病变在b值分别取500、1000、2000s／mm^2时的表观扩散系数（ADC）值和信号强度，以手术后病理结果为金标准，比较同一b值时不同乳腺病变、以及不同b值时同一种病变平均ADC值和信号强度的差异。结果（1）乳腺病变分为乳腺癌、良性病变和囊肿。各种病变的平均ADC值、平均信号强度在不同b值时不同，其中乳腺癌在b=500s／mm^2时分别为1．375±0．378和839．713±360．493（与其他病变比较，F值分别为16．019、30．409，P均〈0．01）；b=1000s／mm^2时分别为1．176±0．311和459．314±229．609（与其他病变比较，，值分别为16．578和23．092，P均〈0．01）．b=2000s／mm^2时分别为0．824±0．198和243．825±110．616（与其他病变比较，F值分别为3．122、23．888，P值分别〈0．05和〈0．01）。各种乳腺病变两两比较显示在b=500和1000s／mm^2时，大部分病变之间平均ADC值差异有统计学意义，而在b=2000s／mm^2时仅在乳腺癌和良性病变间差异有统计学意义。（2）以各b值时乳腺癌平均ADC95％可信区间的上限作为确定乳腺癌的上限阈值点，取这些阈值点在b值=500、1000、2000s／mm^2时确定乳腺癌的诊断指标，敏感性分别为70．92％、70．73％、69．77％，特异性分别为77．19％、75．70％、54．76％，准确性分别为77．12％、74．32％、62．35％。ROC曲线分析曲线下面积（Az）500=0．775±0．046，Az1000=0．780±0．044，P均〈0．01，提示b取500和1000s／mm^2时对诊断乳腺癌有统计学意义。而Az2000=0．620±0．062，P〉0．05，提示b=2000s／mm^2对鉴别乳腺良恶性病变差异无统计学意义。结论b值取500和1000s／mm^2的MRDWI可以用于鉴别乳腺良恶性病变。     

Diagnostic performance of conventional diffusion weighted imaging and diffusion tensor imaging for the liver fibrosis and inflammation

Objective

To evaluate the diagnostic accuracy of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation.

Materials and methods

Thirty-seven patients with histologic diagnosis of chronic viral hepatitis and 34 healthy volunteers were included in this prospective study. All patients and healthy volunteers were examined by 3 T MRI. CDI and DTI were performed using a breath-hold single-shot echo-planar spin echo sequence with b factors of 0 and 1000 s/mm². ADCs were obtained with CDI and DTI. Histopathologically, fibrosis of the liver parenchyma was classified with the use of a 5-point scale (0–4) and inflammation was classified with use of a 4-point scale (0–3) in accordance with the METAVIR score. Quantitatively, signal intensity and the ADCs of the liver parenchyma were compared between patients stratified by fibrosis stage and inflammation grade.

Results

With a b factor of 1000 s/mm², the signal intensity of the cirrhotic livers was significantly higher than those of the normal volunteers. In addition, ADCs reconstructed from CDI and DTI of the patients were significantly lower than those of the normal volunteers. Liver ADC values inversely correlated with fibrosis and inflammation but there was only statistically significant for inflammatory grading. CDI performed better than DTI for the diagnosis of fibrosis and inflammation.

Conclusion

ADC values measured with CDI and DTI may help in the detection of liver fibrosis. They may also give contributory to the inflammatory grading, particularly in distinguishing high from low grade.     

Value of diffusion tensor imaging in differentiating malignant from benign parotid gland tumors

PurposeTo evaluate whether diffusion tensor imaging (DTI) can be used to differentiate malignant parotid gland tumors from the benign ones.Materials and methodsThe study population comprised 59 parotid gland tumors (24 Warthin’s tumors, 19 pleomorphic adenomas, seven other benign tumors, and nine malignant tumors). Single-shot echo-planar DTI was performed with motion-probing gradients along 30 noncollinear directions (b = 1000 s/mm²) at 3.0 T. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values for benign and malignant tumors were compared using the Mann–Whitney U test. Receiver-operating characteristic (ROC) curve analysis was performed to assess the ability of the ADC and FA values to differentiate malignant tumors from the benign ones.ResultsADC values showed no significant difference between malignant (0.93 ± 0.21 × 10⁻³ mm²/s) and benign tumors (1.19 ± 0.50 × 10⁻³ mm²/s) (p = 0.225). FA values of malignant tumors were significantly higher than those of benign tumors (0.26 ± 0.06 vs. 0.17 ± 0.05, p < 0.001). The area under the ROC curve of FA was significantly greater than that under the curve of ADC (0.884 vs. 0.628, p = 0.010).ConclusionsDTI, particularly FA, can help differentiate malignant parotid gland tumors from the benign ones.     

Diffusion-weighted MRI in a liver protocol: its role in focal lesion detection

AIM: To evaluate the role of diffusion-weighted imaging (DWI) in the detection of focal liver lesions (FLLs), using a conventional magnetic resonance imaging (MRI) protocol. METHODS: Fifty-two patients (22 males, average age 55.6 years, range: 25-82 years), studied using a 1.5 Tesla magnetic resonance scanner, were retrospectively analyzed; detection of FLLs was evaluated by considering the number of lesions observed with the following sequences: (1) respiratory-triggered diffusion-weighted single-shot echo-planar (DW SS-EP) sequences; (2) fat-suppressed fast spin-echo (fs-FSE) T2 weighted sequences; (3) steady-state free precession (SSFP) images; and (4) dynamic triphasic gadolinium-enhanced images, acquired with three-dimensional fast spoiled gradient-echo (3D FSPGR). Two radiologists independently reviewed the images: they were blinded to their respective reports. DW SS-EP sequences were compared to fs-FSE, SSFP and dynamic gadolinium-enhanced acquisitions using a t -test. Pairs were compared for the detection of: (1) all FLLs; (2) benign FLLs; (3) malignant FLLs; (4) metastases; and (5) hepatocellular carcinoma (HCC). RESULTS: Interobserver agreement was very good (weighted = 0.926, CI = 0.880-0.971); on the consensus reading, 277 FLLs were detected. In the comparison with fs-FSE, DW SS-EP sequences had a significantly higher score in the detection of all FLLs, benign FLLs, malignant FLLs and metastases; no statistical difference was observed in the detection of hepatocellular carcinoma (HCCs). In the comparison with SSFP sequences, DW SS-EP had significantly higher scores (P < 0.05) in the detection of all lesions, benign lesions, malignant lesions, metastases and HCC. All FLLs were better detected by dynamic 3D FSGR enhanced acquisition, with P = 0.0023 for reader 1 and P = 0.0086 for reader 2 in the comparison with DW SS-EP sequences; with reference to benign FLLs, DW SS-EP showed lower values than 3D FSPGR enhanced acquisition (P < 0.05). No statistical differences were observed in the detection of malignant lesions and metastases; considering HCCs, a very slight difference was reported by reader 1 (P = 0.049), whereas no difference was found by reader 2 (P = 0.06). CONCLUSION: In lesion detection, DWI had higher scores than T2 sequences; considering malignant FLLs, no statistical difference was observed between DWI and dynamic gadolinium images.     

磁共振扩散加权成像及动态增强MRI在乳腺病变中的应用价值

目的 探讨月经周期对正常乳腺实质磁共振扩散加权成像(DWI)表观扩散系数(ADC)值的影响,并评价动态增强MRI(DCE-MRI)及DWI在乳腺病变鉴别诊断中的价值。方法 选取健康女性志愿者34例、乳腺病变患者96例,所有病例均经外科手术或针吸病理证实,其中良性病变者36例,共44个病灶;恶性病变者60例,共70个病灶...     

梗阻性脑积水的弥散加权成像及弥散张量成像研究

目的探讨磁共振弥散加权成像(DWI)与弥散张量成像(DTI)对梗阻性脑积水的诊断价值。方法 25例梗阻性脑积水患者和30例志愿者均行3.0T磁共振常规序列以及DWI和DTI扫描,重建出ADC图、MD图、FA图、RA图、VR图及AI图,并对各参数图进行测量和记录,所得数据进行统计学分析。结果 30例志愿者及25例梗阻性脑积水患者分别测量双侧侧脑室周围脑白质、胼胝体膝部及压部区域的ADC、MD、FA、RA、VR及AI进行测量,ADC图中胼胝体膝部两组ADC值差异具有统计学意义(P<0.05),双侧侧脑室外侧脑白质两组所测得MD、FA、VR、AI值均有统计学意义(P<0.05),两组胼胝体压部RA值有统计学差异(P<0.05),两组间胼胝体膝部所有测得DTI各参数值均无统计学差异(P>0.05)。结论 DWI和DTI在脑积水的诊断中具有重要的诊断价值。     

子宫粘膜下肌瘤的MRI、超声及宫腔镜对照研究

目的:评价磁共振、经阴道超声诊断子宫粘膜下肌瘤的价值,并以宫腔镜及手术病理结果为标准对两种检查方法进行比较。方法:回顾性分析31例子宫粘膜下肌瘤患者的MRI、经阴道超声检查结果,并与宫腔镜及手术病理结果对照。结果:MRI诊断符合率为96%,阴道超声诊断准确率83%。MRI、阴道超声对子宫粘膜下肌瘤的分型符合率分别为90%、80%。MRI分型结果与病理结果密切相关,对Ⅰ型粘膜下肌瘤的评价MRI与超声有明显统计学差异。结论:MRI对子宫粘膜下肌瘤的诊断及确定分型有较高的临床价值。     

子宫内膜息肉与早期子宫内膜癌的MRI信号特征分析

目的 分析子宫内膜息肉与早期子宫内膜癌的特征性MRI平扫表现,以期在无需静脉注射对比剂的情况下,提高两者术前鉴别诊断的准确性。方法 回顾性分析经手术病理证实的39例子宫内膜息肉和32例早期子宫内膜癌病人的MRI资料。采用独立样本t检验比较2组病人病变大小及DWI相对信号强度值。采用Pearson卡方检验分析2组病人MRI平扫信号特征,包括T2WI上病变内部信号特征(低信号纤维核心和高信号小囊),DWI上病变与正常肌层的信号强度差值,T2WI和DWI上病变周围线样高信号。结果与子宫内膜癌相比,子宫内膜息肉T2WI上有高信号小囊和低信号纤维核心表现者更多(P<0.05)。DWI上病变与子宫肌层信号强度差值比较,子宫内膜息肉(36.4±61.7)低于子宫内膜癌(229.8±94.8)(P<0.05)。子宫内膜息肉在T2WI、DWI上的病灶周边线样高信号表现均多于子宫内膜癌(P<0.05)。结论 子宫内膜息肉的MRI表现具有特征性,T2WI及DWI上病变周围线样高信号有助于鉴别子宫内膜息肉与子宫内膜癌。     

扩散敏感因子800时乳腺良恶性病变ADC界值的确定

目的：确定扩散敏感因子为800s/mm^2时乳腺良恶性病变的ADC界值,评价MR扩散加权成像（DWI）对乳腺良恶性病变鉴别诊断的价值。方法：回顾性分析经手术病理证实的70例（78个病灶）乳腺病变的DWI图像,其中良性病变26例（31个病灶）,恶性病变44例（47个病灶）。测量DWI图像上显示的病变表观扩散系数（ADC）值。通过ROC曲线确定ADC值的诊断阈值,并以此值进行鉴别诊断,同时计算ROC曲线下面积。结果：良恶性病变的ADC值均符合正态性分布,良恶性病变的ADC平均值分别为（1.46±0.26）×10^-3mm^2/s和（1.02±0.19）×10^-3mm^2/s,恶性病变的ADC值明显低于良性病变（P〈0.05）。约登指数最大法确定的ADC诊断阈值为1.28×10^-3mm^2/s,以此值进行鉴别诊断时的敏感度、特异度和诊断符合率分别为93.6%,75.9%,86.8%;阳性似然比最大法确定的ADC诊断阈值为1.035×103mm^2/s,以此值进行鉴别诊断时的敏感度、特异度和诊断符合率分别为46.8%,96.6%,65.8%;ROC曲线下面积为0.905（95%可信区间为0.836-0.975）。结论：扩散敏感因子为800s/mm^2时乳腺良恶性病变的ADC界值确定为1.28×10^-3mm^2/s,DWI的ADC值测定有助于乳腺良恶性病变的鉴别诊断。     

MR 动态增强联合扩散加权成像对壶腹区良恶性病变的鉴别

目的：研究M R动态增强联合扩散加权成像（DWI）在鉴别壶腹区良恶性病变的价值。方法回顾性分析43例胆总管下段狭窄患者的M R动态增强及DWI的数据。其中包括32例恶性病变和11例慢性炎症。1位影像医生对壶腹周围良恶性病变的M R动态增强信号强度及DWI信号进行分析,另外2位影像医生对壶腹周围病变的M R动态增强影像以及M R动态增强联合DWI影像进行评估。应用 Logistic回归分析比较灵敏度及特异性。结果壶腹周围良恶性病变MR动态增强表现差异无统计学意义;DWI影像中,壶腹周围癌比炎症更多地表现为高信号,表观扩散系数（ADC）图表现为低信号（P＜0．001）。2位读片者在结合DWI影像后对恶性壶腹周围病变的诊断灵敏度均有提高,分别从84．4％提高到96．9％和从87．7％提高到96．6％。结论 M R动态增强联合DWI可提高鉴别壶腹周围区良恶性狭窄的诊断准确率。     

Diagnostic use of isotropic diffusion-weighted MRI in patients with ischaemic stroke: detection of the lesion responsible for the clinical deficit

We examined the diagnostic use of isotropic diffusion-weighted (DW) MRI in 140 consecutive patients suspected of or diagnosed as having an ischaemic stroke. Isotropic DW imaging could demonstrate the lesion responsible for the clinical deficit in patients with multiple cerebral infarts at an early stage, even small lesions without a perifocal oedema or mass effect. Accurate diagnosis by DW images may, however, be difficult about 2 weeks after the onset of stroke. Received: 15 November 1998 Accepted: 12 February 1999     

宫腔声学造影、宫腔镜与组织病理学对子宫内膜息肉诊断的一致性研究

目的：分析宫腔声学造影（SHG）、宫腔镜（HS）与组织病理学对子宫内膜息肉（EMP）诊断的一致性,进而探讨SHG在EMP诊断中的应用价值。方法：选取经腹部或阴道超声检查疑有宫腔占位性病变的已婚女性患者54例,于月经干净后3~7天分别进行SHG与HS检查,以组织病理学为金标准进行Kappa一致性检验。结果：SHG与组织病理学的kappa系数=0.762,HS与组织病理学的kappa系数=0.841,SHG与HS的kappa系数=0.803,P〈0.05。结论：SHG在EMP的诊断上与HS、组织病理学具有良好的一致性,可以成为诊断EMP的常规首选检查。     

三维肝脏容积超快速采集MR动态增强扫描及其定量数据对子宫内膜癌的诊断价值

目的 探讨子宫内膜癌MRI动态增强数据及曲线类型对诊断、分期的价值.方法 回顾性分析经分段诊断性刮宫证实为子宫内膜癌的55例患者MRI动态增强表现,绘制病灶区及邻近正常组织的动态增强时间-信号曲线(TIC),测量及计算动态早期相对信号增强率(ARSI％)、最大相对信号增强率(MRSI％)和总体相对信号增强率(SER％),并对曲线分型,对不同征象分组间MRSI％的差异行独立样本t检验,ARSI％和SER％的差异行Mann-Whitney U检验.结果 病灶动态增强扫描早期信号强度为716 ±215,正常组织为894±355,差异有统计学意义(t=-2.911,P＜0.01);病灶动态增强扫描晚期强化率为803±289,正常组织为1111±289,差异有统计学意义(t=-4.926,P＜ 0.01).低分化组16例患者ARSI％(中位数为1.07％)高于中高分化组的39例(中位数为0.36％),深肌层浸润组19例的ARSI％(中位数为0.76％)高于无或浅肌层浸润组36例患者(中位数为0.32％),宫颈受累组27例患者的ARSI％(中位数为0.84％)高于未受累组的28例患者(中位数为0.25％),宫颈受累组SER％(中位数为2.90％)高于未受累组(中位数为1.40％),宫旁及其他组织受侵、转移组7例患者的SER％(中位数为2.03％)高于局限在子宫内组48例患者(中位数为1.60％),差异有统计学意义(Z值分别为-2.038、-2.260、-2.172、-2.695及-2.621,P值均＜0.05).病灶区动态增强曲线:I型13例(13/55),Ⅱ型22例(22/55),Ⅲ型9例(9/55),Ⅳ型11例(11/55).结论 MR动态增强扫描能定量分析子宫内膜癌在各阶段的强化特点,根据其TIC及定量数据可以进一步判断预后、指导分期.     

DWI在鉴别脊椎良恶性病变中的应用价值

目的:探讨DWI在鉴别脊椎良恶性病变中的应用价值。方法:分析经病理和/(或)临床随访证实的脊柱压缩性骨折患者共50例82个病变椎体,其中良性组20例,34个椎体;恶性组30例,48个椎体。选取50例中的正常椎体35例共35节椎体作为对照组。均行MRI常规序列及DWI扫描;分析良恶性病变的DWI信号特点,并定量测定3组椎体的ADC值,进行统计学分析。结果:良性及恶性组病灶DWI序列均可表现为高、等、低或混杂信号,且2组信号表现差异无统计学意义;良性组、恶性组、对照组ADC值分别为(2.23±0.25)×10-3 mm2/s,(1.62±0.27)×10-3 mm2/s及(0.43±0.34)×10-3 mm2/s,经t检验,各组间ADC值差异均有统计学意义(P<0.05)。结论:DWI信号改变不能用于鉴别椎体良恶性病变,而ADC值具有重要的鉴别诊断价值。     

乳腺疾病的MRI研究进展

MRI具有极佳的软组织分辨率,近年来,该技术越来越广泛的应用于乳腺疾病的诊断.乳腺动态增强成像和灌注加权成像可从不同角度反映乳腺组织及病灶的血供灌注情况,弥散加权成像和磁共振波谱分析则从分子水平提供乳腺病变组织信息,磁共振乳腺导管成像为导管内病变提供了新的影像诊断方法.随着MRI技术的成熟、软硬件的迅速发展,MRI在乳腺疾病的检出和诊断方面显示出其独到的优势.     

后循环缺血的磁共振弥散成像观察

 目的 探讨磁共振弥散成像(diffusion - weighted - imaging,DWI)对超早期后循环缺血(posterior circulation ischemia,PCI)患者的临床诊断价值.方法 回顾性分析140例PCI患者入院2h内常规头颅MRI及DWI影像学特点,并与24h和3周后复查的MRI平扫及DWI进行对比研究.结果 140例PCI患者入院2 h MRI平扫发现9例异常,同时进行的DWI54例在脑干、小脑、枕叶及丘脑出现高信号改变;24h后复查,54例DWI异常者仍存在,但MRI平扫阳性者增加至22例,临床明确诊断为后循环脑梗死( posterior ischemic stroke,PIS).正规治疗3周后复查,后循环脑梗死患者磁共振平扫T2SE及FLRIR仍存在异常影像学改变,但DWI异常影像学改变消失,诊断亚急性脑梗死;剩余的32例DWI异常者(诊断后循环TIA明确),6例在磁共振平扫和DWI上显示异常,结合临床诊断为进展性脑梗死,26例磁共振平扫及DWI均正常.结论 DWI对后循环缺血敏感性、特异性高,阳性率比常规MRI高,对缺血后组织损伤的可逆性和预后判断、确定治疗方案有帮助,同时后循环TIA发作的异常影像学改变是动态变化和可逆的,治疗有效、发作频率减少的病例可逆性改变的可能性更大,而短期内频繁发作且发作时间超过1h者更容易进展为PIS.     

低场磁共振DWI技术与常规MRI扫描对超急性脑梗死的诊断灵敏度的比较

目的 探讨低场磁共振弥散加权成像(DWI)技术与常规MRI扫描对超急性脑梗死的诊断价值差异。 方法 选择2014年4月至2015年3月期间收治的临床疑诊为脑缺血病例78例, 分别采用低场磁共振DWI技术与常规MRI扫描技术进行检查, 评价两种检查技术对超急性脑梗死的诊断灵敏度。 结果 低场磁共振DWI诊断超急性脑梗死的灵敏度为100.00%(72/72), 而常规MRI扫描的诊断灵敏度仅为5.56%(4/72), 可见采用低场磁共振DWI技术的诊断灵敏度显著高于常规MRI扫描技术。 结论 低场磁共振DWI技术应用于超急性脑梗死的诊断中, 可有效提高其诊断灵敏度, 其效果显著优于常规MRI扫描, 值得在临床上推广使用。     

Dynamic contrast enhanced MRI in correlation with diffusion weighted (DWI) MR for characterization of ovarian masses

Introduction

Ovarian tumors; are the second most common gynecological tumor and are the fifth commonest tumor in women. It is desirable to preoperatively differentiate benign from malignant tumor to decide whether surgery is required, and which type of surgery is appropriate avoiding unnecessary surgery, adding dynamic contrast and diffusion weighted to conventional images can help in differentiation of benign ovarian tumor from malignant. DWI depends on the fact that water molecules can diffuse freely in low cellular environment, while tissue hyper cellularity causes its restriction. As a result, malignant ovarian tumors due to its hypercellular nature show restriction of diffusion, unlike most benign tumors. This study aims at reviewing and emphasizing the role of dynamic contrast enhanced MRI and diffusion-weighted MR in characterization of ovarian lesions.

Patients and methods

This study was performed on 30 patients referred to the radiology department from surgical department by ovarian masses. Pelvic MR with DWI was done for all patients, DCE-MR was done for 29 out of 30 patients. Twenty-five patients underwent surgery with pathologic correlation. Five patients were put under regular follow up US for 3 months.

Results

The sensitivity of MRI was 99.9% while that of DWI was 100%. The specificity was higher for DWI (75%) compared to conventional MRI (58.3%), as well as the accuracy which was 73.9% for MRI while that of DWI was 86.9%. The mean ADC values for malignant lesions were (0.84 × 10⁻³ ± 0.1 SD mm²/s), while that for benign lesions were (1.8 × 10⁻³ ± 0.5 SD mm²/s), with cut off 1.2 × 10⁻³ and p value = 0.005. Mature teratomas showed restricted diffusion with ADC values 0.8 × 10⁻³ mm²/s (false positive), due to mixed cellularity of the teratoma. Hemorrhagic cysts and endometriomas showed high signal not only on diffusion images but also on corresponding ADC map and ADC values 1.3–1.4 × 10⁻³ (T2 Shine-through). Sensitivity of MRI was 99.9% while that of DCE-MRI was 60%. The specificity was higher for DCE 91% compared to conventional MRI sequences 58.3%, as well as the accuracy which was 73.9% for MRI while that of DCE was 77% and so addition of DCE to the MRI is expected to increase the specificity and the accuracy of examination.

Conclusion

Combination of DWI and DCE to conventional MRI improves the specificity of MRI and thus increasing radiologist’s confidence in image interpretation which will finally reflect on patients’ outcome and prognosis.     

蛛网膜下腔出血MRI诊断价值与进展

蛛网膜下腔出血(SAH)是临床最常见的危急病之一,准确及时地诊断十分必要.随着现代医学影像技术的飞速发展,尤其是MRI新技术的临床应用,其对SAH诊断的敏感性不断增加,但对蛛网膜下腔少量出血的早期确诊仍是影像学检查的一个挑战.简述CT与MRI各序列的成像原理,对比了CT和MRI对急性、亚急性、慢性SAH诊断的敏感性,并总结SAH在CT和MRI影像表现上的各种假阳性情况.旨在提高本病的诊断率,为临床确定治疗方案提供依据,探讨最合适的影像学检查方法.