定量动态增强MRI鉴别乳腺良恶性病变的研究

目的 探讨定量动态增强MRI鉴别乳腺良恶性病变的价值.方法 118例乳腺疾病患者行3.0 T定量动态增强MR检查,测量定量参数:容量转移常数(Ktrans)、速率常数(Kep)和血管外细胞外间隙容积比(Ve),对恶性病变、良性病变及正常腺体组间定量参数行单因素方差分析及LSD法两两比较;对浸润性癌与导管原位癌组间行独立样本t检验;最后绘制ROC曲线.结果 恶性病变组Ktrans、Ken、Ve均值分别为(1.010±0.580)min-1、(1.634±1.481)min-1、(0.735±0.273);良性病变组三者均值分别为(0.331±0.192)min-1、(0.417±0.324)min-1、(0.847±0.291);正常腺体组间三者均值分别为(0.051±0.028)min-1、(0.133±0.125)min-1、(0.597±0.354).正常腺体与良性病变、正常腺体与恶性病变及良性病变与恶性病变间Ktrans差异均有统计学意义(t值分别为9.681、11.189、5.590,P值均＜0.01);正常腺体与恶性病变、良性病变与恶性病变间Kep差异有统计学意义(t值分别为5.287、3.874,P值均＜0.05);正常腺体与良性病变、正常腺体与恶性病变间Ve差异有统计学意义(t值分别为2.932、2.562,P值均＜0.05);正常腺体与良性病变间Kep、良性病变与恶性病变间Ve差异无统计学意义(t值分别为0.760、0.832,P值均＞0.05).浸润性癌与导管原位癌组间Ktrans、Kep、Ve差异均无统计学意义(t值分别为0.834、0.075、0.454,P值均＞0.05).Ktrans、Kep、Ve三者ROC曲线下面积分别为0.934、0.941、0.659,以最大约登指数为最佳诊断切点值,则三者判断乳腺良恶性病变的敏感性分别为77.01%、91.95%、56.32%;特异性分别为95.65%、86.96%、78.26%.结论 定量动态增强参数Ktrans、Kep值可以对乳腺良恶性病变做出鉴别诊断,并表现出相对高的诊断效能,但对浸润性癌与导管原位癌鉴别效能较低.

Abstract：

Objective To evaluate the value of quantitative 3T dynamic contrast enhanced MRI in the diagnosis of breast lesions. Methods One-hundred and eighteen patients suspected of breast lesions underwent MRI examination. A 3.0 T MR scanner was used to obtain the quantitative MR pharmacokinetic parameters: Ktrans( volume transfer constant), Kep (exchange rate constant) and Ve (extravascular extracellular volume fraction). The mean Ktrans, Kep and Ve of malignant, benign and normal glandular tissues were calculated and compared each other using LSD method. Independent sample t test was used between invasive ductal carcinoma and ductal carcinoma in situ (microinvasion included). Finally, the areas under the ROC curve (AUC) of Ktrans, Kep and Ve between malignant and benign lesions were compared. Results The mean Ktrans, Kep and Ve of malignant lesions (n=87) were (1.010±0.580) min-1, (1.634 ± 1.481) min-1 and (0.735 ±0.273); the mean Ktrans, Kep and Ve of benign lesions (n=23) were (0.331±0.192) min - 1, (0.417±0.324) min - 1 and (0.847±0.291); and the mean Ktrans, Kep and Ve of normal glandular tissues (n =83) were (0.051 ±0.028) min-1, (0.133±0.125) min-1 and (0.597±0.354), respectively. There were significant differences between normal glandular tissues and benign lesions, normal glandular tissues and malignant lesions, benign and malignant lesions in Ktrans (t=9.681, 11.189, 5. 590, respectively, P ＜ 0. 01 ), normal glandular tissues and malignant lesions, benign and malignant lesions in Kep(t =5. 287, 3. 874, P＜0. 05). There were a statistic differences between normal glandular tissues and benign lesions, normal glandular tissues and malignant lesions in Ve(t =2. 932, 2. 562 ,P ＜0. 05). There were no significant differences between normal glandular tissues and benign lesions in Kep, benign and malignant lesions in Ve ( t = 0. 760, 0. 832, P ＞ 0.05 ),invasive ductal carcinoma and ductal carcinoma in situ (microinvasion included) in Ktrans, Kep and Ve(t =0.834,0.075,0.454,P＞0.05). The areas under the ROC curve (AUC) of Ktrans, Kep and Ve between malignant and benign lesions were 0. 934, 0. 941 and 0. 659. The sensitivity of Ktrans, Kep and Ve were 77.01% ,91.95% ,56. 32% and the specificity of Ktrans, Kep and Ve were 95. 65%, 86. 96%, 78.26% for the differential diagnosis of breast lesions if taken the maximum Youden's index as cut-off. Conclusion The differential diagnosis of benign and malignant breast lesions by Ktrans, Kep is applicable.     

Contralateral lesions detected by preoperative MRI in patients with recently diagnosed breast cancer: application of MR CAD in differentiation of benign and malignant lesions

Objectives

To retrospectively investigate the added value of kinetic features measured by computer-aided diagnosis (CAD) for differentiating benign and malignant contralateral breast lesions detected by preoperative MRI in breast cancer patients.

Methods

This study was approved by our institutional review board, and the requirement for informed consent was waived. Fifty-two breast MR images and their CAD kinetic features were obtained for 52 consecutive breast cancer patients with contralateral breast lesions detected by preoperative MRI and confirmed by excision (23 cancers and 29 benign lesions). Three experienced radiologists independently reviewed the MR images without CAD information and assessed probabilities of malignancy. Four weeks later, these probabilities were reanalyzed using stored CAD data. Diagnostic performances and detection rates of delayed washout components were compared between interpretations without and with CAD for each reader.

Results

Use of MR CAD increased detection of washout component by 2.4- to 3.7-fold than visual assessment for enhancing contralateral lesions, which increased sensitivity (91% vs. 87% in reader 1; 96% vs. 74% in reader 2; 91% vs. 70% in reader 3) and decreased specificity, but statistical significance was only found for decreased specificity in one reader (52% vs. 28%, P = 0.039), and overall performance (areas under ROC curves 0.672 vs. 0.616 in reader 1; 0.624 vs. 0.603 in reader 2; 0.706 vs. 0.590 in reader 3) remained unimproved.

Conclusion

Addition of MR CAD increased sensitivity and decreased specificity than radiologist's assessment alone for differentiating benign and malignant contralateral lesions in breast cancer patients and overall performance remained unimproved.     

动态增强MRI检查分级评估良恶性乳腺团块型病灶的价值

目的 探讨鉴别乳腺良恶性病灶的客观评分方法,为乳腺团块型病灶的良恶性判断提供客观评价依据.方法 将第4版乳腺影像和报告系统(BI-RADS)的MR部分对团块型病灶的描述作为病灶评价指标对188个高血供团块型病灶评分,根据评分结果与病理结果进行ROC曲线分析,计算曲线下面积并计算最佳良恶性诊断阈值;根据最佳诊断阈值及病灶良恶性倾向将病灶归入Ⅰ～Ⅴ级(Ⅰ级阴性、Ⅱ级良性、Ⅲ级可能良性、Ⅳ级可疑恶性、Ⅴ级高度提示恶性),最后检测评分方法诊断恶性团块型病灶的敏感度和特异度.结果 病理证实188个高血供病灶中有91个恶性,97个良性.ROC曲线下面积为0.938±0.016,评分法鉴别病灶良恶性的最佳阈值为5分.病灶分级结果为Ⅱ级24例、Ⅲ级72例、Ⅳ级54例、Ⅴ级38例.评分法诊断恶性乳腺团块型病灶的敏感度为87.91％,特异度为87.62％.除去Ⅲ级中3例假阴性的导管原位癌,特异度提高到90.90％.结论 建立在多参数标准化分析基础上的评分方法有助于客观判读乳腺动态增强MR影像.     

DWI和Vibrant动态增强MR成像在乳腺癌中的诊断价值

目的：探讨MR扩散加权成像（DwI）和Vibrant技术在乳腺癌中的诊断价值。方法：搜集经病理证实的55例乳腺癌患者,55例均行MRI平扫、DWI及Vibrant成像,扩散系数b值为1000s／mm2,测量正常腺体组织、病灶的ADC值及病灶早期强化率,确定动态增强时间-信号强度曲线类型;将Vibrant图像进行3D最大强度投影（MIP）重组,观察病灶不同角度的特征。结果：乳腺癌平均ADC值[（0．92±0．25）×10-3mm2／s]较正常腺体[（1．73±0．13）×10-3mm2／s2明显减低,差异有统计学意义（P〈0．05）;恶性肿瘤灌注曲线表现为廓清型（49例）或平台型（16例）,病灶早期强化率为1．85±0．58。3DMIP图像可整体观察病灶形态,有利于供血动脉的显示。结论：MRI平扫、DwI、Vibrant成像结合3DMIP图像特征可为乳腺恶性肿瘤的诊断提供更多信息。     

MRI扩散加权成像对乳腺良恶性病变的诊断

目的:探讨磁共振扩散加权成像(DWI)对乳腺良恶性疾病的诊断价值。方法:回顾性分析40例经病理确诊的乳腺疾病,其中良性病变22个,恶性病变18个;均行DWI检查,测定病灶区表观扩散系数(ADC值),与正常组织进行比较,计算相对表观扩散系数(rADC值),应用SPSS 16.0软件比较其平均值,并以病理结果为金标准,作ROC曲线,求其最佳诊断阈值。结果:良性病变及恶性病变的ADC值分别为(1.55±0.35)×10-3和1.00±0.18)×10-3 mm2/s,其rADC值分别为(0.82±0.19)和(0.52±0.08)。良恶性病变组间均有统计学差异,以ADC值及rADC值为诊断标准作受试者工作特征曲线(ROC曲线),其中ADC值的曲线下面积(AUC)为(0.927±0.04),rADC值的AUC为(0.965±0.03),诊断阈值分别为1.17×10-3 mm2/s、0.66,相应敏感度及特异度分别为(90.9%、88.9%)和(95.5%、94.4%),rADC值的AUC、敏感度及特异度均高于ADC值。结论:DWI对乳腺良恶性病变的的诊断具有重要作用,其中rADC值有更好诊断效能。     

Accuracy and reproducibility of manual and semiautomated quantification of MS lesions by MRI

PURPOSE: To evaluate the accuracy, reproducibility, and speed of two semiautomated methods for quantifying total white matter lesion burden in multiple sclerosis (MS) patients with respect to manual tracing and to other methods presented in recent literature. MATERIALS AND METHODS: Two methods involving the use of MRI for semiautomated quantification of total lesion burden in MS patients were examined. The first method, geometrically constrained region growth (GEORG), requires user specification of lesion location. The second technique, directed multispectral segmentation (DMSS), requires only the location of a single exemplar lesion. Test data sets included both clinical MS data and MS brain phantoms. RESULTS: The mean processing times were 60 minutes for manual tracing, 10 minutes for region growth, and 3 minutes for directed segmentation. Intra- and interoperator coefficients of variation (CVs) were 5.1% and 16.5% for manual tracing, 1.4% and 2.3% for region growth, and 1.5% and 5.2% for directed segmentation. The average deviations from manual tracing were 9% for region growth and 5.7% for directed segmentation. CONCLUSION: Both semiautomated methods were shown to have a significant advantage over manual tracing in terms of speed and precision. The accuracy of both methods was acceptable, given the high variability of the manual results.     

Preoperative MR-guided wire localization for suspicious breast lesions: Comparison of manual and automated software calculated targeting

Objectives

Preoperative magnetic resonance (MR) guided wire localization is a frequently used tool to target MR-only visible breast lesions. Different techniques are available. Targeting can be performed using automated software or a manual approach. Aim of this study therefore was to compare manually and automated software assisted wire localization of suspicious breast lesions regarding to image time and accurate positioning.

Methods

60 females with suspicious breast lesions underwent MR-guided wire localization. In 30 patients a manual target calculation and in another 30 patients a software calculated approach was used. Time measurements for MR imaging as well as calculation of the target coordinates were performed. Furthermore size measurements of (i) lesions, (ii) distance to wire anchor as well as, (iii) distance to skin were performed. A Mann-Whitney-test was used for statistical evaluation.

Results

Total imaging time was shorter for the automated software calculated approach but failed to show a statistical significant difference (p = 0.13). Time for localization of the lesions was significantly shorter for the software based method (p < 0.001). Lesion sizes, distances to wire anchor and skin showed no statistically significant differences.

Conclusions

Preoperative MR-guided wire localization of suspicious lesions that are accessible horizontally, a manually or automated software generated target calculation can be used. As MR guided wire localization of breast lesions needs its time in total, a minimal time consuming approach and therefore an automated software calculated targeting (if available) should be preferred.     

Time to enhancement derived from ultrafast breast MRI as a novel parameter to discriminate benign from malignant breast lesions

ObjectivesTo investigate time to enhancement (TTE) as novel dynamic parameter for lesion classification in breast magnetic resonance imaging (MRI).MethodsIn this retrospective study, 157 women with 195 enhancing abnormalities (99 malignant and 96 benign) were included. All patients underwent a bi-temporal MRI protocol that included ultrafast time-resolved angiography with stochastic trajectory (TWIST) acquisitions (1.0 × 0.9 × 2.5 mm, temporal resolution 4.32 s), during the inflow of contrast agent. TTE derived from TWIST series and relative enhancement versus time curve type derived from volumetric interpolated breath-hold examination (VIBE) series were assessed and combined with basic morphological information to differentiate benign from malignant lesions. Receiver operating characteristic analysis and kappa statistics were applied.ResultsTTE had a significantly better discriminative ability than curve type (p < 0.001 and p = 0.026 for reader 1 and 2, respectively). Including morphology, sensitivity of TWIST and VIBE assessment was equivalent (p = 0.549 and p = 0.344, respectively). Specificity and diagnostic accuracy were significantly higher for TWIST than for VIBE assessment (p < 0.001). Inter-reader agreement in differentiating malignant from benign lesions was almost perfect for TWIST evaluation (κ = 0.86) and substantial for conventional assessment (κ = 0.75).ConclusionsTTE derived from ultrafast TWIST acquisitions is a valuable parameter that allows robust differentiation between malignant and benign breast lesions with high accuracy.     

US correlation for MRI-detected breast lesions in women with familial risk of breast cancer

AIM: To examine the value of US correlation for MRI-detected breast lesions in women with familial risk of breast cancer. METHODS: From an initial dataset of 245 women with positive family history who had breast cancer surveillance involving mammography or MRI between November 1994 and February 2001, 179 subjects with follow-up data were selected. A total of 43 women with 48 MRI-detected lesions underwent further assessment with US. Histopathological correlation was available from 38 breast biopsies performed for 33 women. RESULTS: Sonographic correlates were identified in 32 (66.7%) of the 48 MRI-detected lesions, with cancer present in 11 (34.4%) of these. This compares with 1 (6.3%) cancer found in the 16 lesions without sonographic correlates. Of the 12 malignant lesions, 11 (91.7%) had sonographic correlates whereas 21 (58.3%) of the 36 benign lesions had sonographic correlates. In all 74% of breast biopsies were performed under US guidance compared with 8% under MRI guidance. The proportion of MRI- and US-correlated benign and malignant lesions undergoing US-guided biopsy were 85.7% and 90.9%, respectively. CONCLUSION: The probability of cancer was significantly higher in MRI-detected breast lesions with sonographic correlates compared with those without such correlation. The advantage of convenient biopsy under US guidance as opposed to MRI guidance highlights the value of sonographic assessment of MRI-detected breast lesions.     

Targeted ultrasound for MR-detected lesions in breast cancer patients.

OBJECTIVE: To investigate the usefulness of targeted ultrasound (US) in the identification of additional suspicious lesions found by magnetic resonance (MR) imaging in breast cancer patients and the changes in treatment based on the identification of the lesions by the use of targeted US. MATERIALS AND METHODS: One-hundred forty nine patients who underwent breast MR imaging for a preoperative evaluation of breast cancer between January 2002 and July 2004 were included in the study. We searched all cases for any additional lesions that were found initially by MR imaging and investigated the performance of targeted US in identifying the lesions. We also investigated their pathological outcomes and changes in treatment as a result of lesion identification. RESULTS: Of the 149 patients with breast cancer, additional suspicious lesions were detected with MR imaging in 62 patients (42%). Of the 69 additional lesions found in those 62 patients, 26 (38%) were confirmed as cancers by histology. Thirty-eight lesions in 31 patients were examined with targeted US and were histologically revealed as cancers in 18 (47%), high risk lesions in two (5%), benign lesions in 15 (39%), and unidentified lesions in three (8%). The cancer rate was statistically higher in lesions with a US correlate than in lesions without a US correlate (p = 0.028). Of 31 patients, the surgical plan was altered in 27 (87%). The use of targeted US justified a change in treatment for 22 patients (81%) and misled five patients (19%) into having an unnecessary surgical excision. CONCLUSION: Targeted US can play a useful role in the evaluation of additional suspicious lesions detected by MR imaging in breast cancer patients, but is limited in lesions without a US correlate.     

Proton magnetic resonance spectroscopy ((1)H MRS) of human brain tumours: assessment of differences between tumour types and its applicability in brain tumour categorization

Our objective was to evaluate the usefulness of proton magnetic resonance spectroscopy (¹H MRS) in categorizing brain tumours. In vivo single-voxel ¹H MRS at an echo time of 136 ms was performed in 108 patients with brain neoplasms that included 29 meningiomas (MEN), 15 low-grade astrocytomas (LGA), 12 anaplastic astrocytomas (AA), 25 glioblastomas (GBM) and 27 metastases (MET). Time-domain fitted areas of nine resonances were evaluated in all spectra. Twenty-five additional tumours were prospectively included as independent test set. Differences in at least two resonances were found in all pairwise comparisons of tumour groups except in GBM vs MET. Large lipid resonance at 1.30 ppm was found to be characteristic of GBM and MET, and alanine was characteristic of MEN. Significant differences were found between LGA and AA in choline-containing compounds and total creatine resonances. When implemented in a stepwise algorithm, these findings correctly classified 84% (21 of 25) tumours in the independent test set. Some additional utility was found in glycine/myo-inositol at 3.55 ppm for bilateral differentiation between GBM and MET (9 of 11, 82% correct classification in the test set). ¹H MRS provides useful information to categorize the most common brain tumours that can be implemented in clinical practice with satisfactory results. Electronic Publication     

动态增强MRI鉴别乳腺良恶性病变的前瞻性研究

目的　前瞻性评估乳腺良恶性病灶的增强形态、时间-信号强度曲线形态、早期增强率以及鉴别病变的价值。方法　40例乳腺病变行三维动态增强MRI检查,在工作站上绘制时间-信号强度曲线并计算早期增强率,分别根据病灶增强形态、时间-信号强度曲线分型和早期增强率大小诊断病变的良恶性。结果　40例41个病灶经病理证实,恶性病灶23个,良性病灶18个。良性病变边缘77.8%（14/18）为光滑或分叶,16.7%(3/18)为不规则或毛刺,早期增强率为(55.5±28.3)%,时间-信号强度曲线72%(13/18)为单相型;恶性病变边缘82.6%(19/23)为不规则或毛刺,13%（3/23）为光滑或分叶,早期增强率为(90.5±38.6)%,时间-信号强度曲线78.3%(18/23)为流出型。良恶性病变的形态分布、时间-信号强度曲线类型和早期增强率差异有显著性意义(χ2值分别为18.42、20.68、10.38,P值均<0.01)。病灶增强形态诊断的敏感性82.6%（19/23）,特异性77.8%（14/18）。时间-信号强度曲线诊断的敏感性95.7%（22/23）,特异性72.2%（13/18）。早期增强率诊断的敏感性87%（20/23）,特异性61.1%（11/18）。结论　典型毛刺状形态和流出型时间-信号强度曲线均强烈提示恶性;单相型时间-信号强度曲线强烈提示良性;早期增强率诊断的特异性差。     

MRI of the Breast for the Detection and Assessment of the Size of Ductal Carcinoma in Situ

Objective

The aim of the study was to compare the accuracy of magnetic resonance imaging (MRI) and mammography for the detection and assessment of the size of ductal carcinoma in situ (DCIS).

Materials and Methods

The preoperative contrast-enhanced MRI and mammography were analyzed in respect of the detection and assessment of the size of DCIS in 72 patients (age range: 30-67 years, mean age: 47 years). The MRI and mammographic measurements were compared with the histopathologic size with using the Pearson''s correlation coefficients and the Mann-Whitney u test. We evaluated whether the breast density, the tumor nuclear grade, the presence of comedo necrosis and microinvasion influenced the MRI and mammographic size estimates by using the chi-square test.

Results

Of the 72 DCIS lesions, 68 (94%) were detected by MRI and 62 (86%) were detected by mammography. Overall, the Pearson''s correlation of the size between MRI and histopathology was 0.786 versus 0.633 between mammography and histopathology (p < 0.001). MRI underestimated the size by more than 1 cm (including false negative examination) in 12 patients (17%), was accurate in 52 patients (72%) and overestimated the size by more than 1 cm in eight patients (11%) whereas mammography underestimated the size in 25 patients (35%), was accurate in 31 patients (43%) and overestimated the size in 16 patients (22%). The MRI, but not the mammography, showed significant correlation for the assessment of the size of tumor in noncomedo DCIS (p < 0.001 vs p = 0.060). The assessment of tumor size by MRI was affected by the nuclear grade (p = 0.008) and the presence of comedo necrosis (p = 0.029), but not by the breast density (p = 0.747) or microinvasion (p = 0.093).

Conclusion

MRI was more accurate for the detection and assessment of the size of DCIS than mammography.     

动态增强MRI定量参数及最大线性斜率比值对鉴别乳腺良恶性疾病的价值

目的 通过对动态增强MRI时间.信号强度曲线(TIC)的后处理,寻找有效的鉴别诊断良、恶乳腺疾病的定量参数.方法 回顾性分析行MR检查的30例乳腺疾病初诊患者,对动态增强MRI的TIC进行后处理,得出最高信号强度(SImax)、强化峰值(PH)、最大线性斜率(Slope)、最大线性斜率比值(SlopeR)4个定量参数,用独立样本t检验和秩和检验评价4个定量参数在良、恶性病灶间的分布是否具有统计学意义.结果 共17个良性病灶和18个恶性病灶,良性病灶和恶性病灶的SImax值(M值)分别为375.2和158.1,95%可信区间分别为278.2～506.0和160.5～374.8;PH值(M值)分别为114.4和87.8.95%可信区间分别为73.7-196.5和71.3~162.9;Slope值(M值)分别为22.3×10-3和44.0×10-3,95%可信区间分别为13.7×10-3~41.1×10-3和46.1×10-3~81.8×10-3;SlopeR值(M值)分别为2.6和11.4,95%可信区间分别为1.9～3.4和9.8~14.5.SImax、PH值在良、恶性病灶间的分布差异无统计学意义(P值均>0.05);Slope值在良、恶性病灶间的分布差异具有统计学意义(P<0.01),但曲线下面积重叠较大;SlopeR值在良、恶性病灶间的分布差异具有统计学意义(P<0.01),曲线下面积重叠少.结论 SlopeR值对乳腺良、恶性病灶间的鉴别有重要意义.     

The pseudocapsule in hepatocellular carcinoma: correlation between dynamic MR imaging and pathology

Nodular hepatocellular carcinoma (HCC) is characterized by the presence of a pseudocapsule (constructed usually from connective fibrous tissue) that appears hypointense on T1- and T2-weighted spin-echo (SE) and gradient-echo (GE) MR imaging sequences without a contrast medium. The presence of vascular structures inside the tumor, which are verified by histological exam, affects enhancement of the PC after administrating the contrast medium: The impregnation is more evident in the dynamic study but also persists on the delayed T1-weighted SE images. The accuracy of MR in detecting the pseudocapsule of HCC and contrast enhancement of the pseudocapsule during dynamic studies were evaluated and related to pathological findings. Thirty-seven HCC were examined in 33 patients and afterwards resected. In capsulated nodules, besides usual hematoxylin, eosin, and trichrome stainings, histochemical and immunohistochemical methods were performed. On a 1.5-T MR unit, T1- and T2-weighted SE and GE FLASH 2D sequences after intravenous injection of Gd-DTPA (dynamic study) were used. In a later phase, T1-weighted SE sequences were repeated. Histologically, the pseudocapsule (thickness 0.2–6 mm) was present in 26 of 37 nodules (70 %). The dynamic study was the most suitable technique to show the pseudocapsule, which was recognized in 80.7 % (21 of 26 nodules). In 5 of 26 cases, the pseudocapsule, not demonstrated by MR, was thinner than 0.4 mm. In 16 of 21 cases, in the early portal phase (30–60 s), the pseudocapsule had an early enhancement, which was more evident later; in 5 of 21 cases the enhancement was observed only in the late portal phase (1–2 min). At histological examination, 14 of 16 pseudocapsules with early enhancement showed a more prominent vasculature than those with enhancement in the equilibrium phase. Magnetic resonance was a reliable tool in demonstrating the pseudocapsule of HCC. The histological examination demonstrated a good correlation between the enhancement behavior and the vessel number of the pseudocapsule. Received: 28 July 1997; Revision received: 9 February 1998; Accepted: 20 March 1998     

Contrast enhancement with GD-EOB-DTPA in MR imaging of hepatocellular carcinoma in mice: A comparison with superparamagnetic iron oxide

The purpose of this study was to evaluate the ability of the new liver-specific magnetic resonance contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) to detect hepatocellular carcinoma (HCC). Seventeen mice with 66 chemically induced HCCs underwent magnetic resonance imaging with both Gd-EOB-DTPA (30 μmol/kg) and superparamagnetic iron oxide (SPIO; 10 μmol/kg). After enhancement, lesion-to-liver contrast-to-noise ratios (CNRs) of 47 detected HCCs increased negatively from 3.7 ± 10.7 (mean ± SD) to –55.1 ± 25.8 with Gd-EOB-DTPA (P < .001) and increased positively from 10.4 ± 10.4 to 26.1 ± 16.3 with SPIO (P < .001). The improvement of CNR after administration of SPIO was less in smaller lesions (< 4 mm), whereas that after administration of Gd-EOB-DTPA was independent of lesion size. However, Gd-EOB-DTPA positively enhanced four HCCs (8.5%), both highly differentiated (grade 1) and moderately differentiated (grade 2). Gd-EOB-DTPA allows the conspicuous detection of small HCCs; however, moderately differentiated HCCs occasionally may be positively enhanced.     

International investigation of breast MRI: results of a multicentre study (11 sites) concerning diagnostic parameters for contrast-enhanced MRI based on 519 histopathologically correlated lesions

A multicentre study was undertaken to provide fundamentals for improved standardization and optimized interpretation guidelines of dynamic contrast-enhanced MRI. Only patients scheduled for biopsy of a clinical or imaging abnormality were included. They underwent standardized dynamic MRI on Siemens 1.0 (163 valid lesions ≥ 5 mm) or 1.5 T (395 valid lesions ≥ 5 mm) using 3D fast low-angle shot (FLASH; 87 s) before and five times after standardized bolus of 0.2 mmol Gd-DTPA/kg. One-Tesla and 1.5 T data were analysed separately using a discriminant analysis. Only histologically correlated lesions entered the statistical evaluation. Histopathology and imaging were correlated in retrospect and in open. The best results were achieved by combining up to five wash-in or wash-out parameters. Different weighting of false-negative vs false-positive calls allowed formulation of a statistically based interpretation scheme yielding optimized rules for the highest possible sensitivity (specificity 30 %), for moderate (50 %) or high (64–71 %) specificity. The sensitivities obtained at the above specificity levels were better at 1.0 T (98, 97, or 96 %) than at 1.5 T (96, 93, 86 %). Using a widely available standardized MR technique definition of statistically founded interpretation rules is possible. Choice of an optimum interpretation rule may vary with the clinical question. Prospective testing remains necessary. Differences of 1.0 and 1.5 T are not statistically significant but may be due to pulse sequences Received: 25 January 2000 Accepted: 29 September 2000     

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。     

Minimizing contrast agent dose during intraarterial gadolinium-enhanced MR angiography: in vitro assessment.

PURPOSE: To minimize contrast agent dosage for intra-arterial (IA) contrast-enhanced magnetic resonance angiography (CE-MRA) by examining the effects of encoding order (elliptical vs. sequential) and injection duration (100% to 30% of the acquisition time). MATERIALS AND METHODS: Catheter-based IA gadolinium (Gd) injections were performed in an arterial flow phantom. Blood flow rates, injection rates, and injection durations were systematically varied. Signal-to-noise (SNR) measurements were obtained in the aorta, renal artery, and common iliac artery. RESULTS: No significant SNR losses were observed for any of the vessels with 75% injection duration, or for the aorta and iliac artery with 50% injection duration. Excellent images of all vessels were obtained at 50% injection duration. There was no significant SNR difference between encoding schemes. CONCLUSION: Contrast agent dosage can be substantially reduced without loss of SNR by limiting injection to part of the imaging acquisition time.