正常乳腺的MR扩散加权成像:表观扩散系数的可重复性及月经周期及绝经期的变化的研究

摘要目的研究正常乳腺腺体组织的表观扩散系数(ADC)测量的可重复性以及月经周期及绝经期乳腺组织ADC值的变化。方法31名志愿者(13个绝经前,18个绝经后)进行两次磁共振扩散加权序列扫描(间隔11～22d),计算ADC总和灌注不敏感的ADC高(忽略b=0),对观察者多次重复测量及不同观察者间的平均ADC值的一致性进行评估,并且评价月经周期和绝经后两个阶段乳腺组织的平均ADC值的变化。     

Diffusion weighted imaging and estimation of prognosis using apparent diffusion coefficient measurements in ischemic stroke

Objective

Estimation of the prognosis of infarction by using diffusion weighted imaging (DWI) and quantitative apparent diffusion coefficient (ADC) measurements.

Methods

23 patients having acute stroke symptoms with verified infarction in magnetic resonance imaging (MRI) were included in this study. Their MRI studies were performed between 6 and 12 h after the onset of their symptoms and were repeated on the fifth day. The infarction volumes were calculated by using DWI and the patients were divided into two groups as the ones having an expansion in the infarction area (group 1, n = 16) and the others having no expansion in the infarction area (group 2, n = 7). Quantitative ADC values were estimated. The groups were compared in terms of the ADC values on ADC maps obtained from DWI, performed during the between 6 and 12 h from the onset of the symptoms, referring to the core of the infarction (ADC_IC), ischemic penumbra (ADC_P) and the nonischemic parenchymal tissue (ADC_N). P values < 0.05 were accepted to be statistically significant.

Results

During the between 6 and 12 h mean infarction volume calculated by DWI was 23.3 cm³ for group 1 patients (ranging from 1.1 to 68.6) and this was found to be 40.3 cm³ (ranging from 1.8 to 91.5) on the fifth day. For the group 2 patients these values were found to be 42.1 cm³ (ranging from 1 to 94.7) and 41.9 (ranging from 1 to 94.7) for the same intervals respectively. A significant statistical result was failed to be demonstrated between the mean ADC_IC and ADC_N values (p = 0.350 and p = 0.229 respectively). However the comparison of the ADC_P values between the groups was found to be highly significant (p < 0.001). When the differences between the ADC_P and ADC_IC and ADC_N and ADC_P were compared the results proved to be statistically significant (p = 0.038 and p < 0.001 respectively).

Conclusions

We believe that ADC results that would be obtained from the core and the penumbra of the infarction area will be beneficial in the estimation of the infarction prognosis and in the planning of a treatment protocol.     

Diffusion tensor magnetic resonance imaging of the normal breast: reproducibility of DTI-derived fractional anisotropy and apparent diffusion coefficient at 3.0 T

PURPOSE: Diffusion-weighted imaging (DWI) may improve the diagnostic performance of conventional breast magnetic resonance imaging (MRI). Diffusion tensor imaging (DTI) is an extension of DWI. If DTI-derived measurements are to be clinically useful, particularly for predicting and/or monitoring therapeutic effects, they must be robust and reliable. The purpose of this study was to assess intra- and interobserver reproducibility of DTIderived fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at 3.0 T. MATERIALS AND METHODS: This prospective study was approved by the Institutional Review Board, and participants provided written informed consent. Sixty normal contralateral breasts of 60 patients (28-85 years, median 57) were analysed with a DWI sequence following a standard MRI protocol. Four authors performed all postprocessing and analyses independently and in different sessions. The same authors, blinded to the initial results, repeated the image postprocessing and analysis 4 weeks after the initial session. RESULTS: Mean ADC and FA for DTI sequences were, respectively, 1.92±0.30 and 0.32±0.09. Intra- and seinterobserver agreement of the four radiologists for ADC and FA were good (acceptable). Kappa values for ADC were intra-R1=0.82; intra-R2=0.84; intra-R3=0.89; intra-R4=0.88; inter-R1-R2=0.73; inter-R1-R3=0.74; inter-R1-R4=0.81; inter-R2-R3=0.76; inter-R2-R4=0.77; inter-R3-R4=0.83. Kappa values for FA were intra-R1=0.60; intra-R2=0.72; intra-R3=0.84; intra-R4 = 0.66; inter-R1-R2=0.64; inter-R1-R3=0.69; inter-R1-R4=0.72; inter-R2-R3=0.80; inter-R2-R4=0.71; inter-R3-R4=0.73. Within-subject coefficient of variation was 15% for ADC and 30% for FA. Repeatability with α=0.05 was 0.37×10-3 mm(2)/s for ADC and 0.112 for FA. CONCLUSIONS: ADC and FA measurements obtained with DTI are reproducible and may be valid, reliable and sensitive to change. ADC values obtained with DTI are more reproducible than FA.     

MR‐diffusion weighted imaging of healthy liver parenchyma: Repeatability and reproducibility of apparent diffusion coefficient measurement

Purpose:

To compare repeatability and reproducibility of four different methods of apparent diffusion coefficient (ADC) evaluation of liver parenchyma. In fact, repeatability and reproducibility assessment is mandatory in quantitative evaluations, however, these have not been accurately investigated in liver MR‐diffusion‐weighted studies.

Materials and Methods:

Diffusion‐weighted sequences, b‐value = 0–1000 s/mm², were acquired on 30 healthy volunteers by a 1.5T scanner whose reliability has been validated by a phantom study. Four sampling methods, evaluating various parenchyma percentages by different‐sized region‐of‐interests (ROIs), were compared by two observers: 70% and 30% of the volume, 4%‐one‐ROI‐per‐segment, and 4%‐one‐ROI‐per‐slice in the right‐lobe. Ninety‐five percent limits of agreement and intraclass correlation coefficient (ICC) were calculated.

Results:

Complete measurements on the left lobe could be obtained in less than half of patients. The 4%‐one‐ROI‐per‐slice and 4%‐one‐ROI‐per‐segment yielded lower mean values compared with 30–70% volume methods (1343–1373 versus 1463–1560·10^?6 mm²/s, respectively). Repeatability was acceptable (ICCs ～ 0.80) whereas reproducibility was low (ICCs ≤ 0.45) for all methods. Averaging at least 3 measurements in middle‐lower sections of the right lobe improved both repeatability (ICCs to ≥0.87) and reproducibility (ICCs to 0.82) for 30–70% V methods.

Conclusion:

ADC measurements were repeatable but not reproducible in our study. Reproducibility could be improved by taking averages on the right lobe with large ROI methods. Studies on procedures that standardize ADC measurements using more than two observers are needed. J. Magn. Reson. Imaging 2010;31:912–920. ©2010 Wiley‐Liss, Inc.

     

MR扩散加权成像表观扩散系数在乳腺结节病变诊断中的应用价值

目的 评价ADC值及相对ADC值(rADC)在乳腺结节病灶检查中的应用价值.方法 对52例66个乳腺结节病灶行MR DWI扫描,b值分别为0、800、1000 s/mm2,测量乳腺结节及同侧、对侧乳头层面未受累乳腺实质组织ADC值,计算rADC1(病灶ADC值/同侧未受累乳腺实质ADC值)及rADC2(病灶ADC值/对侧未受累乳腺实质ADC值),对所获资料采用两独立样本t检验、x2检验进行统计学分析.所有病灶均经穿刺活检或手术病理证实.结果 52例患者中,浸润性导管癌18例,纤维腺瘤34例,DWI显示50例,共64个病灶.b=800s/mm2时,良、恶性结节平均ADC值、同侧rADC800-1及对侧rADC800-2分别为(1.54±0.28)×10-3、(1.01±0.09)×10-3 mm2/s和0.77±0.15、0.52±0.07,0.76±0.14、0.51±0.06;其差异均有统计学意义(t值分别为8.217、9.339、10.394,P值均＜0.01);以乳腺浸润性导管癌平均值95％参考值范围上限界值作为恶性病变上限阈值点,ADC值、rADC8o0-1及rADC800-2分别为1.05×10-3 mm2/s、0.55、0.53,诊断的敏感度分别为75.0％、65.0％、60.0％,特异度分别为100.0％、95.7％、97.8％,阳性预测值分别为100.0％、86.7％、92.3％,阴性预测值分别为90.2％、86.3％、84.9％,诊断符合率分别为92.4％、86.4％、86.4％.b=1000 s/mm2时,良、恶性结节平均ADC值、rADC1000-1及rADC1000-2分别为(1.45±0.28)×10-3、(0.93±0.08)×10-3mm2/s和0.75±0.16、0.53±0.09,0.74±0.15、0.52±0.07;其差异有统计学意义(t值分为11.844、5.820、8.082;P值均＜0.01);ADC值、rADC1ooo-1及rADC1000-2阈值点分别为0.97×10-3 mm2/s、0.58、0.55,诊断的敏感度均为70.0％,特异度分别为100.0％、95.7％、93.5％,阳性预测值分别为100.0％、87.5％、82.4％,阴性预测值分别为88.5％、88.0％、87.8％,诊断符合率分别为90.9％、87.9％、86.5％.以上6种诊断方法的敏感度及诊断符合率差异无统计学意义(x2值分别为1.232、2.263,P值分别为0.942、0.812).结论 ADC值与rADC值均为鉴别良恶性乳腺病变的重要参数,尤其是b= 800 s/mm2时的ADC值临床应用价值最高.     

Diffusion‐weighted imaging of breast cancer: Correlation of the apparent diffusion coefficient value with prognostic factors

Purpose

To evaluate the role of diffusion‐weighted imaging (DWI) in the detection of breast cancers, and to correlate the apparent diffusion coefficient (ADC) value with prognostic factors.

Materials and Methods

Sixty‐seven women with invasive cancer underwent breast MRI. Histological specimens were analyzed for tumor size and grade, and expression of estrogen receptors (ER), progesterone receptors, c‐erbB‐2, p53, Ki‐67, and epidermal growth factor receptors. The computed mean ADC values of breast cancer and normal breast parenchyma were compared. Relationships between the ADC values and prognostic factors were determined using Wilcoxon signed rank test and Kruskal‐Wallis test.

Results

DWI detected breast cancer as a hyperintense area in 62 patients (92.5 %). A statistically significant difference in the mean ADC values of breast cancer (1.09 ± 0.27 × 10^?5 mm²/s) and normal parenchyma (1.59 ± 0.27 × 10^?5 mm²/s) was detected (P < 0.0001). There were no correlations between the ADC value and prognostic factors. However, the median ADC value was lower in the ER‐positive group than the ER negative group, and this difference was marginally significant (1.09 × 10^?5 mm²/s versus 1.15 × 10^?5 mm²/s, P = 0.053).

Conclusion

The ADC value was a helpful parameter in detecting malignant breast tumors, but ADC value could not predict patient prognosis. J. Magn. Reson. Imaging 2009;30:615–620. © 2009 Wiley‐Liss, Inc.

     

The effect of the surroundings to the apparent diffusion coefficient on diffusion weighted imaging

Diffusion weighted imaging (DWI) is now widely used in magnetic resonance (MR) imaging of the head and body. Moreover, the Apparent diffusion coefficient (ADC) value is often used for the differential diagnosis of the tumor. However, the effect of the surroundings on the ADC value has not been reported. In this study, we used the phantom completely sealed up to measure the change in the ADC value depending on the surroundings material. The results showed that the ADC value decreased according to the density of superparamagnetic iron oxide (SPIO) in the surroundings. Clinically, hemorrhage or iron deposit around the tumor may affect the ADC value of the tumor and result in under-estimation.     

不同类型正常乳腺表观扩散系数值差异的研究

目的 研究不同类型正常乳腺表观扩散系数（ADC）值的差异，探讨ADC值与组织学分型之间的关系。方法 采用单次激发平面回波（EPI）技术，扩散敏感因子（b）值分别为0、500、1000s／mm^2，对62个正常乳腺（包括42例乳腺病变患者的对侧正常乳腺及10名健康志愿者20个乳腺）进行MR扫描及MR扩散加权成像（DWI）检查，计算62个正常乳腺分别在不同b值时的ADC值。将62个正常乳腺分为3型，比较3型之间ADC值的差异及不同b值时ADC值的差异。结果 42例乳腺病变患者对侧正常乳腺的DWI及ADC图与组织切片对比，不同类型乳腺组织学结构不同，其DWI及ADC图表现亦有差异。62个正常乳腺分为致密型10个，分叶斑点型42个及退化型10个。致密型和分叶斑点型乳腺随b值降低ADC值升高，而退化型乳腺随b值降低ADC值变化不明显。b=1000—0s／mm^2时，致密型、分叶斑点型、退化型乳腺ADC值分别为（1．70±0．37）、（1．93±0．46）、（1．18±0．65）×10^-3mm^2／s，3组间比较差异有统计学意义（F=12．998，P=0．000）。不同b值时每2种类型间进行单因素方差分析，致密型和分叶斑点型之间差异无统计学意义（F=2．167，P=0．147）；致密型和退化型之间、分叶斑点型和退化型之间差异均有统计学意义（F值分别为5．593、19．128，P值分别为0．029、0．000）。结论 3型正常乳腺ADC值受乳腺组织学结构的影响，致密型和分叶斑点型乳腺ADC值受b值高低的影响。     

Menstrual cycle variation of apparent diffusion coefficients measured in the normal breast using MRI

Recent investigations have shown that tumors may be distinguished from benign lesions in the breast based on differences in apparent diffusion coefficient (ADC) values. The goal of this study was to assess the magnitude of normal variations in the measured ADC of breast parenchyma during the menstrual cycle. Eight healthy female subjects were scanned once a week for 4 weeks, using a diffusion-weighted single-shot fast spin-echo (DW-SSFSE) sequence. The ADC of breast fibroglandular tissue was calculated for each woman at each time point. Results showed a trend of decreased ADC during the second week of the cycle, and increased ADC during the final week. However, no significant influence of menstrual cycle on breast ADC values was identified. The results of this study show that the normal fluctuation of breast ADC is relatively small, and the coefficient of variation was determined to be 5.5% for our group of volunteers during a menstrual cycle. Nonetheless, breast diffusion measurements for tumor differentiation and evaluation of treatment response should be interpreted with consideration of normal variability.     

弥散加权成像及表观弥散系数在前列腺病变诊断中的价值

目的：探讨弥散加权成像（DWI）及表观弥散系数（ADC）在前列腺病变诊断中的应用价值。方法对64例前列腺病病变患者采用磁共振常规扫描和磁共振弥散加权成像检查,选取感兴趣区记录DWI的信号强度和表观弥散系数（apparent diffusion coefficient ,ADC）值,并对得到的数据进行方差分析。结果64例经经手术或穿刺活检诊断结果显示前列腺癌35例,前列腺增生29例。当b取800s／mm2时,以前列腺癌组外周带癌灶的平均ADC值单值上界95％可信区间的上限为0．87×10‐3 mm2／s ,而前列腺增生结节的ADC值单值上界95％可信区间的上限为1．30×10‐3 mm2／s ,两组ADC之间无交叉,所以以ADC值≤0．87×10‐3 mm2／s作为诊断前列腺癌的阈值,其诊断敏感度为88．57％,特异性为89.66％,准确性为89．06％,Kappa＝0．67,P ＜0．01,说明其与病理结果具有较好的一致性。结论 DWI对于前列腺增生、前列腺癌可提供定量诊断信息,ADC值是鉴别前列腺增生与前列腺癌的一个很有价值的参数。     

Apparent diffusion coefficient values of the normal uterus: Interindividual variations during menstrual cycle

Objectives

To assess the apparent diffusion coefficient (ADC) changes of the normal uterine zones among reproductive women during the menstrual cycle.

Methods

The study included 101 women of reproductive age, each with regular cycle and normal endometrium/myometrium, as proved on histopathology or MR imaging examination. Diffusion-weighted (DW) imaging was performed along the axial plane, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 800 s/mm². The mean and standard deviation of the ADC values of normal endometrium/myometrium were calculated for menstrual, proliferative and secretory phase. Analysis of variance followed by the least significant difference test was used for statistical analysis.

Results

The ADC values of the endometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.25 ± 0.27; proliferative phase: 1.39 ± 0.20; secretory phase: 1.50 ± 0.18) (F: 9.64, p: 0.00). Statistical significant difference was observed among all groups (p < 0.05). The ADC values of the normal myometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.91 ± 0.35; proliferative phase: 1.72 ± 0.27; secretory phase: 1.87 ± 0.28) (F: 3.60, p: 0.03). Statistical significant difference was observed between menstrual and proliferative phase and between proliferative and secretory phase (p < 0.05). No significant difference was noted between menstrual and secretory phase (p > 0.05).

Conclusions

A wide variation of ADC values of normal endometrium and myometrium is observed during different phases of the menstrual cycle.     

磁共振扩散加权成像在眼眶良恶性肿瘤鉴别中的应用

目的 探讨磁共振扩散加权成像(DWI)及表观扩散系数(ADC)在眼眶良恶性肿瘤鉴别诊断中的价值.方法 回顾性分析40例(良性组∶恶性组=25∶15)眼眶肿瘤病例的DWI及ADC图像,分析其DWI及ADC图像信号特点.逐层勾画肿瘤边界以获得整体感兴趣区(ROD,得到肿瘤平均ADC值(ADCM).眼眶良恶性肿瘤的信号特点比较采用Fisher精确检验,2组间ADCM值比较采用独立样本t检验.炎性假瘤及淋巴瘤的ADCM值比较采用Mann-Whitney U检验.采用受试者工作特征曲线(ROC)法分析AIDCM值对眼眶良恶性肿瘤的鉴别诊断价值.结果 眼眶良恶性肿瘤组间DWI图像信号特点无明显统计学差异(P＞0.05),2组ADC图像信号特点有明显统计学差异(P＜0.05).良性肿瘤的ADCM明显高于恶性肿瘤(P＜0.05),其中炎性假瘤的ADCM明显高于淋巴瘤(P＜0.05).以ADC值≥1.289×10-3 mm2/s判断眼眶肿瘤良恶性,可获得最优的诊断价值[曲线下面积(AUC)0.968;敏感度0.960;特异度0.933].结论 磁共振DWI及ADC值在眼眶肿瘤良恶性鉴别中具有重要价值.     

Role of PROPELLER diffusion weighted imaging and apparent diffusion coefficient in the diagnosis of sellar and parasellar lesions

Objective

To evaluate the role of the apparent diffusion coefficient (ADC) using periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion weighted imaging (DWI) in the differentiation between sellar and parasellar mass lesions.

Materials and methods

The study protocol was approved by our institutional review board. We retrospectively studied 60 patients with sellar and parasellar lesions who had undergone PROPELLER DWI on a 3-T MR imager. Conventional MRI findings were expressed as the ratio of signal intensity (SI) in the lesions to the normal white matter and the degree of contrast enhancement. ADC values were calculated as the minimum (ADC-MIN), mean (ADC-MEAN), and maximum (ADC-MAX). All patients underwent surgery and all specimens were examined histologically. Logistic discriminant analysis was performed by using the SI ratios on T1- and T2-weighted images (T1-WI, T2-WI), the degree of enhancement, and absolute ADC values as independent variables.

Results

ADC-MIN of hemorrhagic pituitary adenomas was lower than of the other lesions with similar appearance on conventional MRI (non-hemorrhagic pituitary adenomas, craniopharyngiomas, Rathke's cleft cysts; accuracy 100%); the useful cut-off value was 0.700 × 10⁻³ mm²/s. ADC-MAX of meningiomas was lower than of non-hemorrhagic pituitary adenomas (accuracy 90.3%; p < 0.01). ADC-MIN of craniopharyngiomas was lower than of Rathke's cleft cysts (accuracy 100%; p < 0.05).

Conclusion

As PROPELLER DWI is less sensitive to susceptibility artifacts than single-shot echoplanar DWI, it is more useful in the examination of sellar and parasellar lesions. Calculation of the ADC values helps to differentiate between various sellar and parasellar lesions.     

Diffusion-weighted imaging of the abdomen at 3.0 Tesla: image quality and apparent diffusion coefficient reproducibility compared with 1.5 Tesla

Purpose

To compare single‐shot echo‐planar imaging (SS EPI) diffusion‐weighted MRI (DWI) of abdominal organs between 1.5 Tesla (T) and 3.0T in healthy volunteers in terms of image quality, apparent diffusion coefficient (ADC) values, and ADC reproducibility.

Materials and Methods

Eight healthy volunteers were prospectively imaged in this HIPAA‐compliant IRB‐approved study. Each subject underwent two consecutive scans at both 1.5 and 3.0T, which included breathhold and free‐breathing DWI using a wide range of b‐values (0 to 800 s/mm²). A blinded observer rated subjective image quality (maximum score= 8), and a separate observer placed regions of interest within the liver, renal cortices, pancreas, and spleen to measure ADC at each field strength. Paired Wilcoxon tests were used to compare abdominal DWI between 1.5T and 3.0T for specific combinations of organs, b‐values, and acquisition techniques.

Results

Subjective image quality was significantly lower at 3.0T for all comparisons (P = 0.0078– 0.0156). ADC values were similar at 1.5T and 3.0T for all assessed organs, except for lower liver ADC at 3.0T using b0‐500‐600 and breathhold technique. ADC reproducibility was moderate at both 1.5T and 3.0T, with no significant difference in coefficient of variation of ADC between field strengths.

Conclusion

Compared with 1.5T, SS EPI at 3.0T provided generally similar ADC values, however, with worse image quality. Further optimization of abdominal DWI at 3.0T is needed. J. Magn. Reson. Imaging 2011;33:128–135. © 2010 Wiley‐Liss, Inc.     

DWI及ADC图对脑梗死病情进展的评估作用研究

目的:研究核磁共振弥散加权成像及表观弥散系数图像对脑梗死的病情进展和恢复状态的评估作用。方法:对一组超急性期(8例)和急性期(10例)脑梗死患者连续追踪行T_1-FLAIR、FSE-T_2WI、T_2-FLAIR、DWI序列扫描检查,及ADC图像重建,观察不同期相脑梗死灶的图像特征,计算其固定层面病灶区域残余弥散积(MSAFSS):面积×(3.0-1 000×ADC),并使其与相应的脑功能损害评分相对应,进行相关性分析。结果:①超急性期病灶,T_1-FLAIR、T_2WI均无明显信号改变,T_2-FLAIR偶可见等或稍高信号,DWI则可见明显的高信号,ADC图为低信号;急性期梗死灶,T_1-FLAIR基本都呈低信号改变,T_2WI表现为高信号,T_2-FLAIR为高信号,DWI仍为高信号,ADC图为低信号;亚急性期病灶,T_1-FLAIR信号较前都明显降低,T_2WI、T_2-FLAIR、DWI均为高信号表现,ADC图为稍低或等信号表现;慢性期病灶,T_1-FLAIR为低信号,T_2WI为高信号,T_2-FLAIR、DWI呈低或等信号,而ADC图为高信号。②对12例全程追踪的观察结果显示,病灶全过程的MSAFSS与评分分值之间无相关(P0.05);而亚急性早期前10例的MSAFSS与分值间具有正相关性(P0.05)。结论:各期脑梗死在DWI及ADC图上都有其不同的图像特征,并可据此大体判断脑梗死所处期相;通过计算MSAFSS可以对亚急性早期以前的脑梗死病情进展与功能恢复状态给予一定程度的评估。     

3.0 T MR标准化表观扩散系数值评价肝纤维化程度的研究

目的 探讨标准化ADC值对肝纤维化程度定量分析的能力.方法 采用3.0 TMRDWI检查回顾性分析10名健康志愿者(对照组)和43例经肝脏穿刺活检病理证实为肝功能代偿期的肝病患者(慢性肝病组)资料,慢性肝病组患者进行肝纤维化分期(S分期).测量不同肝纤维化分期下肝脏ADC值、脾脏ADC值、肾皮质ADC值、脾脏标准化ADC值(S-ADC)及肾脏标准化ADC值(R-ADC).采用非参数Spearman检验分析S分期与ADC值之间的相关性;采用单因素方差分析比较各期ADC值间的差异,采用Logistic回归分析评价ADC值预测纤维化程度的能力,选择约登指数最大作为截断点,计算曲线下面积(AUC)、敏感度及特异度.结果 10名对照组志愿者均为SO期.慢性肝病组SO、S1、S2、S3、S4期分别有2、5、9、12和15例.S0～S4期肝脏ADC值分别为(1.37±0.13) ×10-3、(1.33±0.16)×10-3、(1.17±0.16) ×10 -3、(1.23 ±0.14)×10-3和(1.12 ±0.11)×10-3 mm2/s,S-ADC分别为1.86 ±0.18、1.68 ±0.12、1.34 ±0.14、1.48 ±0.15和1.34 ±0.10,R-ADC分别为0.71 ±0.08、0.68 0.12、0.61 ±0.09、0.64±0.11和0.60±0.08,差异均有统计学意义(F值分别为6.48、18.70和3.04,P＜0.05).S-ADC、肝脏ADC值和R-ADC均与肝纤维化分期呈负相关性(r值分别为-0.71、-0.51和-0.41,P值均＜0.01),但S-ADC与肝纤维化分期的相关性高于肝脏ADC值和R-ADC.对于预测≥S2期、≥S3期及s4期纤维化,S-ADC的效果均优于肝脏ADC值、R-ADC,约登指数分别为0.91、0.58和0.59.结论 S-ADC在评价肝纤维化方面优于肝脏ADC值及R-ADC,具有良好的诊断准确性.     

DWI及ADC图在脑梗死不同期相中的诊断价值

目的：研究磁共振弥散加权成像（diffusion weighted imaging,DWI）及表观弥散系数（apparent diffusion coefficient,ADC）图像对不同期相脑梗死的图像特征及诊断价值。方法：对54例脑梗死患者按发病就诊时间分为超急性期（8例）、急性期（10例）、亚急性期（22例）和慢性期（14例）4组,对每例进行MRI的T1-FLAIR、FSE-T2WI、T2-FLAIR、DWI序列扫描检查及ADC图像重建,分别测量病灶中心和病灶对称点正常脑组织的信号强度,计算出两者的信号差作为本序列对病灶显示的对比度,并对在各序列图像上的信号差进行对比,对急性期患者在各序列图像上同一层面所显示面积进行比较。结果：对超急性期、急性期脑梗死病灶,DWI序列的信号差（对比度）明显高于其它序列（P＆lt;0.05）;亚急性期的病灶,T2-FLAIR的信号差低于DWI的病灶（P＆lt;0.05）,T2WI、DWI中病灶信号差类同（P＆gt;0.05）,不存在序列间的相互差别;对于慢性期的病灶,T2WI序列的病灶信号差明显高于其它序列（P＆lt;0.05）;对于急性期的相同层面,T2WI、T2-FLAIR、DWI显示的病灶面积类同,不存在序列间的相互差别（P〉O．05）。结论：DWI能对超急性期、急性期、亚急性期的脑梗死病灶做出明确诊断,并对超急性期、急性期病灶的诊断敏感性明显高于其它序列。