多回波快速自旋回波T2 mapping定量技术评价心肌T2值的价值

 目的 探讨多回波快速自旋回波序列(MEFSE)的T₂ mapping定量技术评价左室心肌T₂值的价值。方法 30例健康志愿者,均行3.0T心脏磁共振(CMR)Cine电影、T₂WI序列、MEFSE T₂ mapping序列扫描,依据描述性研究方法,探索MEFSE T₂ mapping序列临床应用的可行性和可重复性,测定感兴趣区T₂值,应用方差分析方法统计分析心肌17节段和不同供血区下有无差异。应用Bland~Altman分析和Pearson相关分析方法研究此技术在不同观察者间的一致性。结果 健康志愿者17节段心肌T₂值不全相等(P＜0.01)。不同冠状动脉供血区T₂值无统计学差异(F=1.656,P=0.192)。左室心肌平均T₂值如下:基底部,(71.6±7.1)ms;中间部,(77.3±9.2) ms;心尖部,(83.0±8.5)ms,差异有统计学意义(F=14.245,P＜0.01)。根据Bland-Altman一致性分析和Pearson相关分析得到参数测量在观察者间具有良好的一致性,95%一致性界限(-6.1,24.8)ms,相关系数r=0.809。结论 CMR MEFSE T₂ mapping定量技术在心脏成像中具有较好的可行性和可重复性。中国健康志愿者中心肌T₂值存在节段性差异。     

ADC值在肝脏局灶性病变定量诊断中的价值

目的评价MR扩散加权序列表观扩散系数(ADC)值在肝脏局灶性病变定量诊断中的价值。资料与方法对153例共187个肝脏局灶性病变(focal liver lesion,FLL)行常规MR扫描的同时增加b=0、500(s/mm2)扩散加权序列,图像经后处理拟合出ADC图,分析并比较各类病灶ADC值。结果良性FLL的ADC值分别为:肝囊肿(n=26)(3.21±0.22)×10-3mm2/s、成熟肝脓肿(n=18)(2.12±0.81)×10-3mm2/s、不成熟肝脓肿(n=7)(1.46±0.22)×10-3mm2/s、肝血管瘤(n=23)(1.92±0.36)×10-3mm2/s、肝脏局灶性结节增生(FNH)(n=8)(1.75±0.26)×10-3mm2/s。恶性FLL的ADC值分别为:肝癌(n=57)(1.23±0.43)×10-3mm2/s、胆管癌(n=12)(1.47±0.35)×10-3 mm2/s、转移癌(n=36)(1.36±0.33)×10-3 mm2/s。良恶性组的平均ADC值分别为(2.40±0.79)×10-3mm2/s、(1.29±0.41)×10-3mm2/s,差异有统计学意义。若AD...     

肝脏局灶病变血供对表观扩散系数的影响

目的　研究肝脏局灶病变的血供对病灶表观扩散系数 (apparentdiffusioncoefficient,ADC)的影响。方法　研究对象包括 87例病人 ,共 1 59个肝脏局灶病变 ,采用不同的b值和b值差的扩散加权成像 (diffusion weightedimaging,DWI)技术对各病灶及肝脏、脾脏及胆囊进行ADC值的测量。结果小b值和b值差所检测到的ADC值受组织或病变内血流灌注的影响 ,海绵状血管瘤的平均ADC值最高 (7 64× 1 0 - 3mm2 /s) ,富血供恶性肿瘤的平均ADC值明显高于乏血供恶性肿瘤 (分别为 3 47×1 0 - 3mm2 /s和 2 39× 1 0 - 3mm2 /s,t=2 39,P <0 0 1 ) ,肝囊肿的ADC值几乎不受b值和b值差的影响。结论　当利用小b值和小b值差进行DWI时 ,组织或病变的ADC值受血流灌注的影响较大。DWI及ADC值测量可在一定程度上反映肝脏局灶病变的血供     

肝脏局灶性病变的病理解剖

认识肿瘤样病变及上皮性和间质性肿瘤的病理解剖对肝脏局灶性病变的影象诊断具有重要意义。本文根据病理学知识,对肝脏局灶性病变的病理解剖作系统概述。     

定量研究表观扩散系数与T2值在肝局灶性小病变中的应用价值

目的通过对表观扩散系数（ADC）与T2值的定量对比研究,探讨ADC值与T2值在肝脏局灶性小病变定性诊断中的价值. 资料与方法对临床发现有肝脏局灶性小病变患者73例（其中包括原发性肝细胞癌22例22个病灶,肝转移瘤16例26个病灶,肝海绵状血管瘤27例38个病灶,肝囊肿8例11个病灶）分别行磁共振扩散加权成像（DWI）和常规快速自旋回波（FSE）T2WI,然后测量计算各病变的ADC值及T2值,进行统计学分析,对比两种量化方法（ADC值和T2值）对肝脏良恶性病变的诊断准确性. 结果肝脏恶性病变的ADC值明显低于良性病变（P＜0.01）,其诊断准确性为93.8%;肝脏恶性病变的T2值也低于良性病变（P＜0.05）,但两者数值重叠较多,其诊断准确性为77.3%,有明显统计学差异（P＜0.05）. 结论利用ADC值在定性方面优于T2值,对肝脏局灶性小病变的诊断更具临床价值.     

正常人胫股关节软骨T2及T2*弛豫值的比较研究

目的:探讨正常志愿者膝关节软骨的T2及T2*弛豫值范围、影响因素及其内在相关程度。方法:将63名健康人胫股关节按照年龄分为青少年组(<35岁)18人、中年组(36~55岁)28人和老年组(56~78岁)17人,计算体重指数(BMI)并行T2图、T2*图成像,按照全器官磁共振成像评分(WORMS)规定的软骨分区法测量胫股关节软骨10个感兴趣区的T2、T2*弛豫率并取平均值,然后进行统计学分析。结果:健康人胫股关节软骨T2、T2*值分别为(42.98±4.19)ms、(19.75±2.43)ms。左右膝胫股关节T2、T2*值分别为(43.60±4.08 ms,42.37±4.26 ms)、(19.29±2.48 ms,20.21±2.37 ms),经检验两者均无明显统计学差异(P>0.05)。女性及男性胫股关节软骨T2、T2*值分别为(44.28±5.14 ms,41.86±4.09 ms)、(19.36±2.48 ms、20.09±2.42 ms),亦无明显统计学差异(P>0.05)。青少年组、中年组及老年组胫股关节软骨的T2、T2*值分别为(37.45±1.76 ms,41.29±2.13 ms,44.98±4.73 ms)、(17.95±1.58 ms,20.76±1.52 ms,22.30±2.08 ms),三组间有明显统计学差异(P<0.01)。青少年组、中年组及老年组三组内T2、T2*值均呈显著相关(P<0.05,Pearson相关系数分别为0.61、0.63、0.55)。结论:正常人胫股关节软骨T2及T2*弛豫值研究可以为关节软骨早期病变的诊断提供相似的参考价值,定量测定T2*值有望替代传统的T2值用于研究软骨形态学改变之前软骨内生化成分的变化。     

通过T1和T2值评估发育性语言障碍儿童的脑微结构改变

目的 分析发育性语言障碍儿童和典型发育儿童之间语言相关脑结构的纵向弛豫时间（T₁）值和横向弛豫时间（T₂）值,研究发育性语言障碍儿童的脑脱水和髓鞘丢失情况,并探索弛豫时间改变与语言发育商的关系。方法 搜集25例发育性语言障碍儿童为病例组和20例典型发育儿童作为对照组,行常规MRI和合成磁共振序列Magic扫描后得到T₁和T₂地图。共测量7个白质和灰质感兴趣区的T₁和T₂值进行组间比较,并分析发育性语言障碍组感兴趣区弛豫值与语言发育商的相关性。结果 与对照组相比,病例组尾状核头T₁值降低,T₂值升高,差异具有统计学意义（P<0.05）。ROC曲线分析显示,尾状核头的T₁和T₂值诊断效能均大于0.7,两者诊断效能比较无统计学意义（P>0.05）。病例组尾状核头T₁值降低与语言能力下降呈正相关（r=0.658,P<0.05）。结论 发育...     

采用MRT1和（T2）*图评价肝脏的铁负荷

目的对可疑肝脏铁负荷过量(HIO)的病人采用MRI的T1和T2*图进行评价。材料与方法对25例临床怀疑HIO的病人进行回顾性研究。所有病人进行了MRI检查和肝脏活检。采用脂肪抑制的多回波梯度回波序列,12个回波链(TR=200ms,TE=0.99+n×1.41ms,翻转角20°),定量评价肝脏的T2*值。T1值采用快速反转恢复FLASH序列的快速T1序列。在各参数图上分析相应的兴趣区。结果 ROC曲线分析显示,当T2*诊断HIO的临界点为10.07ms和15.47ms时,准确度为88%和88%,敏感度为84%和89.5%,特异度为100%和83%。MRI能正确诊断20例(80%)病人。所有HIO病人均表现为T1和T2*弛豫时间缩短。单纯HIO与伴脂肪性肝炎的HIO病人之间的T1值差异存在统计学意义(P=0.018)。结论采用MRI的T2*弛豫诊断HIO非常准确,即使在铁浓度较低时。综合T1与T2图能获得更多的诊断信息,可作为一种快速、无创、准确和可重复性高的诊断技术,即使是程度较轻的HIO。     

肝脏局灶性病变的血管造影检查

目前,肝脏局灶性病变的首次检出和定性诊断几乎只有通过超声、CT以及超声和CT导向活检才能达到。血管造影的适应范围主要限于外科手术前确定肝动脉、门静脉和肝静脉的血管解剖以及用于门静脉肿瘤种植的局部化疗或肝肿瘤的栓塞治疗。当非损伤性影象检查方法被拒用以及活检不安全时,唯有血管造影对局灶性病变的定性诊断能提供更多的信息。术前必须了解肝的动脉和静脉的血供类型,占位性病变侵犯哪个(些)段以及门静脉在肝内的分支情况。腹腔——肠系膜动脉造影、间接门静脉造影、选择性肝灌注造影、经皮经肝穿刺门静脉造影以及选择性肝静脉造影可以解决这些问题。     

Characterization of head and neck lesions with diffusion-weighted MR imaging and the apparent diffusion coefficient values

Purpose

The aim of this study was to determine the role of diffusion-weighted MR imaging (DWI) and the apparent diffusion coefficient (ADC) in characterization of head and neck lesions.

Patients and methods

MR imaging including diffusion-weighted sequences was performed on 43 patients presented with head and neck lesions. Images were obtained with a diffusion-weighted factor (b factor) of 100, 500, and 1000 s/mm². ADC maps were reconstructed, and the ADC value of the lesions was calculated.

Results

The mean ADC value of malignant tumors was (1.02 ± 0.22) × 10⁻³ mm²/s (n = 31). The mean ADC value of benign tumors was (1.62 ± 0.27) × 10⁻³ mm²/s (n = 12). The mean ADC of lymphomas was significantly lower than that of carcinomas. The difference in the ADC value between the malignant tumors and benign lesions was statistically significant (p < 0.001). Selection of (1.2) × 10⁻³ mm²/s as a threshold value of ADC for differentiating benign from malignant tumors yielded the best result, with an accuracy of 94%, sensitivity of 95%, specificity of 92%, positive predictive value of 92% and negative predictive value of 94%.

Conclusion

DWI and the ADC measurement are promising, non-invasive imaging approach that can be used for characterization of head and neck lesions. It can help differentiate malignant tumors from benign lesions.     

MRI扩散加权成像表观弥散系数对肝脏转移瘤的诊断价值

目的 评价表观弥散系数(apparent diffusion coefficient,ADC)在不同组织来源的肝脏转移瘤的诊断价值.方法 回顾性分析45例经1.5T MRI检查的肝脏转移瘤患者的扩散加权图像,采用单因素方差分析276处肝脏转移瘤的ADC值,比较不同肿瘤组间的差异性.结果 来源于胃直肠癌、肝癌、乳腺癌的肝脏转移瘤的平均ADC值间的差异无统计学意义.来源于肺癌的肝脏转移瘤的平均ADC值低于其他来源的肝脏转移瘤,差异有统计学意义(P＜0.05).来源于胰腺癌的肝脏转移瘤的平均ADC值高于其他来源的肝脏转移瘤,差异有统计学意义(P＜0.05).结论 ADC值在肺癌和胰腺癌来源的肝脏转移瘤的诊断中有一定的价值.     

腰椎间盘异常:3.0 T MR定量T2图与传统检查方式的比较

目的评估腰椎间盘形态学异常与定量T2图(T2 mapping)间的关系。方法腰痛病人53例,中位年龄39岁,行3.0TMRI检查[矢状位T1快速自旋回波序列(FSE)及3方位     

Diffusion-weighted imaging of breast lesions: Region-of-interest placement and different ADC parameters influence apparent diffusion coefficient values

Objectives

To investigate the influence of region-of-interest (ROI) placement and different apparent diffusion coefficient (ADC) parameters on ADC values, diagnostic performance, reproducibility and measurement time in breast tumours.

Methods

In this IRB-approved, retrospective study, 149 histopathologically proven breast tumours (109 malignant, 40 benign) in 147 women (mean age 53.2) were investigated. Three radiologists independently measured minimum, mean and maximum ADC, each using three ROI placement approaches:1 – small 2D-ROI, 2 – large 2D-ROI and 3 – 3D-ROI covering the whole lesion. One reader performed all measurements twice. Median ADC values, diagnostic performance, reproducibility, and measurement time were calculated and compared between all combinations of ROI placement approaches and ADC parameters.

Results

Median ADC values differed significantly between the ROI placement approaches (p?<?.001). Minimum ADC showed the best diagnostic performance (AUC .928–.956), followed by mean ADC obtained from 2D ROIs (.926–.94). Minimum and mean ADC showed high intra- (ICC .85–.94) and inter-reader reproducibility (ICC .74–.94). Median measurement time was significantly shorter for the 2D ROIs (p?<?.001).

Conclusions

ROI placement significantly influences ADC values measured in breast tumours. Minimum and mean ADC acquired from 2D-ROIs are useful for the differentiation of benign and malignant breast lesions, and are highly reproducible, with rapid measurement.

Key Points

? Region of interest placement significantly influences apparent diffusion coefficient of breast tumours. ? Minimum and mean apparent diffusion coefficient perform best and are reproducible. ? 2D regions of interest perform best and provide rapid measurement times.

     

Gd-EOB-DTPA对多b值肝脏DWI中表观弥散系数值的影响

目的 通过行肝脏多b值弥散加权成像（DWI）,观察注射钆塞酸二钠（Gd-EOB-DTPA）前、后不同时相表观弥散系数（ADC）值的变化,探讨增强后行DWI的可行性。方法 收集行Gd-EOB-DTPA肝脏增强的受检者126例,其中,例行体检的健康志愿者30名,肝脏病变患者96例（原发性肝癌25例、转移性肝癌20例、肝血管瘤28例、肝囊肿23例）,均经临床或病理证实。在Philips Achieva 1.5T双梯度超导MR成像系统上,行同相与正反相T1加权像闭气轴位平扫及轴位呼吸门控DWI。通过肘静脉向受检者注射0.025 mmol/kg Gd-EOB-DTPA,行动脉期、静脉期、3 min期、10 min期、20 min期、30 min期闭气轴位T1加权高分辨率各向同性容积激发序列（THRIVE）扫描,在5 min期,行轴位T2加权像脂肪抑制呼吸门控扫描,在15 min期,行轴位呼吸门控DWI后,接着行冠状位T2加权闭气扫描,在25 min期,行轴位呼吸门控DWI。平扫期、15 min期、25 min期的DWI参数完全一致,为单次激发自旋回波-平面回波成像（SE-EPI）序列,b值依次取0、50、300、600 s/mm2,扫描时间196 s。在EWS工作站上,通过ADC分析函数生成平扫期、15 min期、25 min期在b=50、300、600 s/mm2时的ADC图,测出正常肝脏、原发性肝癌、转移性肝癌、肝血管瘤、肝囊肿的ADC值,对同一b值下同一疾病在平扫期、15 min期及25 min期的ADC值进行t检验,分析是否存在统计学差异。结果 同一b值下同一疾病的ADC值在平扫期时最大,随着Gd-EOB-DTPA的注入,ADC值开始下降,然后上升,到了25 min期,ADC值与平扫期时基本一致,15 min期的ADC值最低,平扫期、15 min期、25 min期的ADC值差异无统计学意义（t=0.25~1.29,P均>0.05）。同一疾病同一时相的DWI中,随着b值的增加,ADC值不断下降,b值越小,ADC值越大。结论 静脉注射Gd-EOB-DTPA后,肝脏ADC值下降十分有限,增强后行DWI是可行的。     

Accuracy of visual analysis vs. apparent diffusion coefficient quantification in differentiating solid benign and malignant focal liver lesions with diffusion-weighted imaging

Purpose

The authors compared the accuracy of diffusion-weighted imaging (DWI) visual analysis (VA) vs. apparent diffusion coefficient quantification (ADC-Q) in assessing malignancy of solid focal liver lesions (FLLs).

Materials and methods

Using a 1.5-T system, two radiologists retrospectively assessed as benign or malignant 50 solid FLLs: (a) by VA of signal intensity on DWI images at b=800 s/mm² and ADC map; (b) by quantifying lesion ADC. Reference standard included histology or follow-up confirmation of diagnosis by a consensus panel. Receiver operating characteristic (ROC) curve analysis was performed.

Results Because of 20 false-negative hepatocellular carcinomas, VA showed lower accuracy than ADC-Q (52.0% vs. 68.0%). However, stratified accuracy for metastases was higher with VA (75.0 vs. 66%). ADC and signal features of malignant and benign FLLs were found to largely overlap

Conclusions

VA performed worse than ADC-Q for hepatocellular carcinoma and better for metastases. Overall, the accuracy of both methods was limited because of the overlap in visual appearance and ADC values between solid benign and malignant FLLs.     

Breath-hold MR imaging of focal liver lesions: comparison of fast and ultrafast techniques

The performance of breath-hold MR imaging using two T2-weighted hybrid sequences (TSE, TGSE), two T2-weighted single-shot sequences (HASTE, EPI-SE), and one T1-weighted gradientecho sequence (FLASH) was compared with a standard conventional T2-weighted SE sequence in 20 patients with focal liver lesions. Liver signal-to-noise ratio was highest spleen-liver contrast-to-noise ratio (54.3 ± 8.3) and thee HASTE (41.1 ± 12.5) sequence, whereas the highest spleen-liver contrast-noise-ratio was obtained by the TSE sequence (38.9 ± 20.7). Lesion-liver CNR was highest with the TSE sequence (63.9 ± 21.4). With both TSE and HASTE significantly (p < 0.01) more lesions were detected as compared with SE and EPE-SE sequences. Our results indicate that breath-hold TSE and HASTE sequences will eventually replace conventional T2-weighted SE techniques due to their insensitivity to motion artifacts, superior lesion detectability and inherently short acquisitions times.Correspondence to: J. Gaa     

Diffusion-weighted imaging in the head and neck region: usefulness of apparent diffusion coefficient values for characterization of lesions

PURPOSE

We aimed to evaluate the role of apparent diffusion coefficient (ADC) values calculated from diffusion-weighted imaging for head and neck lesion characterization in daily routine, in comparison with histopathological results.

METHODS

Ninety consecutive patients who underwent magnetic resonance imaging (MRI) at a university hospital for diagnosis of neck lesions were included in this prospective study. Diffusion-weighted echo-planar MRI was performed on a 1.5 T unit with b factor of 0 and 1000 s/mm² and ADC maps were generated. ADC values were measured for benign and malignant whole lesions seen in daily practice.

RESULTS

The median ADC value of the malignant tumors and benign lesions were 0.72×10⁻³ mm²/s, (range, 0.39–1.51×10⁻³ mm²/s) and 1.17×10⁻³ mm²/s, (range, 0.52–2.38×10⁻³ mm²/s), respectively, with a significant difference between them (P < 0.001). A cutoff ADC value of 0.98×10⁻³ mm²/s was used to distinguish between benign and malignant lesions, yielding 85.3% sensitivity and 78.6% specificity. The median ADC value of lymphomas (0.44×10⁻³ mm²/s; range, 0.39–0.58×10⁻³ mm²/s) was significantly smaller (P < 0.001) than that of squamous cell carcinomas (median ADC value 0.72×10⁻³ mm²/s; range, 0.65–1.06×10⁻³ mm²/s). There was no significant difference between median ADC values of inflammatory (1.13×10⁻³ mm²/s; range, 0.85–2.38×10⁻³ mm²/s) and noninflammatory benign lesions (1.26×10⁻³ mm²/s; range, 0.52–2.33×10⁻³ mm²/s).

CONCLUSION

Diffusion-weighted imaging and the ADC values can be used to differentiate and characterize benign and malignant head and neck lesions.Diagnosis of head and neck lesions is difficult due to the complicated anatomic structure and different histological components of the many tissues that the neck contains. Imaging of head and neck lesions is not only important for diagnosis of lesions, but also for differentiation of benign lesions from malignant lesions and staging of tumors. While conventional imaging methods mainly evaluate morphological properties, their value is limited in recognizing prognostic characteristics such as benign-malignant differentiation of lesions (1). Routine magnetic resonance imaging (MRI) is a time-consuming method, which is sensitive to differences between examiners and may require the use of contrast material. With development of rapid MRI sequences (such as echo-planar [EPI], fast advanced spin echo [FASE], split echo acquisition of fast spin echo [SPLICE]), the sensitivity to susceptibility artifacts limiting the use of MRI for the head and neck region and limitations linked to duration have been significantly reduced (2, 3).Diffusion-weighted magnetic resonance imaging (DW-MRI) is a short sequence produced from EPI, FASE, SPLICE sequences. DW-MRI is sensitive to the randomized (Brownian) motion of water molecules at a microscopic level, which provides functional information about tissues. DW-MRI was initially used to diagnose early stroke in the brain and to evaluate brain masses (4–6). Previous studies have shown that rapid growth of high-grade tumors like astrocytoma and lymphoma causes hypercellularity, which leads to limitation of the diffusion of water molecules. Nowadays, apparent diffusion coefficient (ADC) maps calculated from DW-MRI sequences are being increasingly used to provide quantitative data for head and neck lesion diagnosis. In malignant lesions, the DW-MRI signal increases and signal loss is observed on ADC maps (5, 7, 8). Many researchers benefited from this feature of DW-MRI and evaluated the effectiveness of DW-MRI for head and neck lesion identification, benign-malignant differentiation, and characterization of malignant lesions (9–11).In this prospective study, head and neck lesions that are seen in daily routine were evaluated using DW-MRI, and the role of ADC values in lesion characterization was investigated with the guidance of histopathological results.