DWIBS 对直肠癌淋巴结转移的初步研究

目的：探讨背景信号抑制扩散加权成像(DWIBS)在直肠癌淋巴结转移诊断中的应用价值。方法30例经肠镜确诊的直肠癌患者行常规 MRI 及 DWIBS 检查。对照术后病理结果,确定转移性和非转移性淋巴结。测量淋巴结实质部分的表观扩散系数(ADC)值,比较差异有无统计学意义,采用受试者工作特征曲线(ROC)分析确定 ADC 值的诊断阈值。结果73枚淋巴结中,转移性淋巴结52枚,非转移性淋巴结21枚。转移性与非转移性淋巴结实质部分的 ADC 值分别为(0.881±0.094)×10-3 mm2/s和(1.072±0.108)×10-3 mm2/s,差异有统计学意义(P <0.05)。当以 ADC=0.957×10-3 mm2/s 作为鉴别转移性与非转移性淋巴结的诊断指标,其诊断价值为优(Az 值=0.919,P <0.05),灵敏度为90.5%,特异度为80.8%。结论ADC 值可用于直肠癌淋巴结转移的鉴别,DWIBS 在直肠癌淋巴结转移的评估中具有较高的应用价值。     

Usefulness of 3T diffusion-weighted MRI for discrimination of reactive and metastatic cervical lymph nodes in patients with oral squamous cell carcinoma: a pilot study

Objectives:

To study the diagnostic accuracy of 3T diffusion-weighted MRI (DW-MRI) for the discrimination of reactive and metastatic cervical lymph nodes in patients with oral squamous cell carcinoma.

Methods:

DW T₁ and T₂ weighted MRI was performed in 25 patients with biopsy-proved primary oral squamous cell carcinoma. The mean apparent diffusion coefficient (ADC) values of 30 histopathologically proved reactive lymph nodes and 21 histopathologically proved metastatic lymph nodes were compared using an unpaired t-test. A cut-off ADC value with optimal diagnostic sensitivity, specificity and area under the curve in discrimination of the two groups was determined using a receiver operating characteristic curve analysis.

Results:

The mean ADC values of reactive lymph node and metastatic lymph node groups were (1.037 ± 0.149) × 10⁻³ and (0.702 ± 0.197) × 10⁻³ mm² s⁻¹, respectively. A statistically significant difference in ADC values of the two groups was certified (p < 0.0001). An optimal ADC threshold value of 0.887 × 10⁻³ mm² s⁻¹ was suggested as the cut-off point, which resulted in 93.33% sensitivity, 80.95% specificity, 88.20% accuracy and area under curve of 0.887.

Conclusions:

Our preliminary study indicates that the addition of 3T DW-MRI may be useful for discriminating between reactive lymph nodes and metastatic lymph nodes in patients with oral squamous cell carcinoma. However, larger studies are still required to validate our results and to standardize this imaging technique for daily clinical practice.     

ADC值鉴别胃癌淋巴结性质的研究

目的 探讨ADC值鉴别胃癌转移与非转移淋巴结的价值.方法 回顾性分析经手术病理证实的43例胃癌患者的临床资料及术前MRI图像,测量胃癌转移与非转移淋巴结的长径、短径、最小ADC值以及右肾门层面右侧竖脊肌ADC值,计算相对ADC值(rADC),利用ROC曲线下面积评价上述各项指标鉴别胃癌转移与非转移淋巴结的诊断效能.结果 转移淋巴结短径和长径均大于非转移淋巴结,且两者差异具有统计学意义(P＜0.001;P＜0.001);转移淋巴结的最小ADC值和rADC值均低于非转移淋巴结,且差异均具有统计学意义(P＜0.001;P＜0.001);短径、长径、最小ADC值和rADC值对鉴别胃癌胃周转移与非转移淋巴结均有诊断意义(Az＞0.5),其中最小ADC值的诊断效能最高,选取最小ADC值阈值为0.913×10-3mm2/s时,其灵敏度和特异度分别为87.7％和77.4％.转移和非转移淋巴结各ADC值指标与形态学参数均无显著相关性(均为P＞0.05).结论 ADC值能很好地鉴别胃癌转移与非转移淋巴结,以最小ADC值最为敏感,其诊断效能优于形态学指标.     

Detection of lymph node metastasis in cervical and uterine cancers by diffusion-weighted magnetic resonance imaging at 3T

PURPOSE: To evaluate diffusion-weighted imaging (DWI) for detection of pelvic lymph node metastasis in patients with cervical and uterine cancers. MATERIALS AND METHODS: Fifty patients scheduled for pelvic lymph node dissection were enrolled for 3T magnetic resonance imaging (MRI) using a single-shot echo-planar DWI technique, body-phased array coil, b = 0, 1000 s/mm(2). We measured short/long-axis diameters, mean apparent diffusion coefficient (ADC) values of all identifiable nodes, relative ADC values between tumors and nodes, and utilized their cutoff values to validate the diagnostic accuracy internally. Histopathologic results served as the reference standard. RESULTS: The relative ADC values between tumor and nodes were significantly lower in metastatic than in benign nodes (0.06 vs. 0.21 x 10(-3) mm(2)/s, P < 0.001; cutoff value 0.10 x 10(-3) mm(2)/s). Compared to conventional MRI, the method combining size and relative ADC values resulted in better sensitivity (25% vs. 83%) and similar specificity (98% vs. 99%). The smallest metastatic lymph node detected by this method measured 5 mm on its short axis. CONCLUSION: The combination of size and relative ADC values was useful in detecting pelvic lymph node metastasis in patients with cervical and uterine cancers.     

定量MRI诊断直肠癌淋巴结转移的研究进展

评估直肠癌淋巴结转移对治疗和预后至关重要。常规MRI诊断直肠癌淋巴结转移主要依据淋巴结的短径和形态学特征,诊断效能较低。定量MRI包括动态增强MRI（DCE-MRI）、动态磁敏感增强MRI（DSC-MRI）、单指数模型扩散加权成像（DWI）、扩散峰度成像（DKI）、体素内不相干运动扩散加权成像（IVIM-DWI）等,可以对直肠癌淋巴结及原发灶进行定量分析,从而有助于诊断淋巴结转移。就常规MRI及定量MRI诊断直肠癌淋巴结转移的研究进展予以综述。     

Diffusion-weighted magnetic resonance imaging in the characterization of axillary lymph nodes in patients with breast cancer

Purpose:

To assess prospectively the accuracy of diffusion‐weighted magnetic resonance imaging (DWI) in differentiating between metastatic and benign axillary lymph nodes in patients with breast cancer.

Materials and Methods:

In all, 215 patients with histologically proven breast cancer, prior to axillary dissection, underwent breast and axillary 1.5 T MRI. In 102 patients in whom at least one axillary lymph node with a short axis of 6 mm or more was found the apparent diffusion coefficient (ADC) was measured in one lymph node per patient by means of an echo planar, parallel imaging DWI sequence. Forty‐three lymph nodes were finally included which, on histological examination, either contained a metastasis larger than 5 mm or were metastasis‐free; nodes with metastases smaller than 5 mm were excluded.

Results:

From histological examination, 19/43 lymph nodes had a metastasis at least 5 mm, while in 24/43 no malignant cells were found. The ADC values of the lymph nodes with metastases (mean: 0.878 × 10^?3 mm²/s; range: 0.30 –1.20) were significantly lower (P < 0.001) than those of the benign lymph nodes (mean: 1.494; range: 0.60 –2.50). Adopting a threshold value of 1.09 × 10^?3 mm²/s DWI resulted in 94.7% sensitivity, 91.7% specificity, and 93.0% accuracy in the identification of metastasis in this series of lymph nodes.

Conclusion:

From these preliminary data DWI seems a promising method in the differential diagnosis between metastatic and benign axillary lymph nodes in patients with breast cancer. J. Magn. Reson. Imaging 2012;36:858–864. © 2012 Wiley Periodicals, Inc.

     

磁共振扩散加权成像对直肠癌术前分期的价值

目的:探讨MR扩散加权成像在直肠癌诊断中的临床应用价值。方法:回顾性分析43例直肠癌患者的MRI资料,所有患者均行常规序列T1WI、T2WI及DWI检查,将MRI诊断结果与手术病理结果进行对照分析。结果:常规序列T1分期的诊断符合率为60.0%(3/5),T2、T3、T4分期分别为80.0%(12/15)、66.7%(12/18)和80.0%(4/5);常规序列联合DWI的T1分期诊断符合率为100%(5/5),T2、T3、T4分期分别为100.0%(15/15)、83.3%(15/18)和100.0%(5/5)。常规序列及常规序列联合DWI的直肠癌T分期总诊断符合率分别为72.1%和93.0%。结论:MR扩散加权成像结合常规序列能够对直肠癌T分期做出较准确的诊断。     

磁共振扩散加权成像在颈部淋巴结病变中的应用

目的:探讨颈部淋巴结病变DWI检查的可行性,并重点研究影响DWI图像质量的技术参数。方法:使用GE1.5T磁共振扫描仪及颈部相控阵线圈对30例单侧或双侧颈部淋巴结肿大患者行常规SE序列扫描,其中16例为恶性肿瘤,14例为良性病变,均经手术及病理证实。全部病例使用体线圈行SE-EPI DWI序列扫描,采用全方位扩散梯度及6个b值扫描。DWI扫描时间40~52s。结果:在DWI序列扫描中,恶性淋巴结和反应性增生性淋巴结均呈高信号,计算ADC值可以鉴别良性和恶性淋巴结,通过各种扫描参数的合理匹配,可使图像的信噪比达到最佳,并减少图像的几何变形。结论:DWI对于鉴别颈部良恶性淋巴结病变是一种快速可行并行之有效的技术,具有一定的临床价值。     

Magnetic resonance enhancement pattern and diagnostic accuracy of gadofluorine M in a rabbit VX2 tumor model: Comparison with gadopentetate dimeglumine

Objective

The purpose of this study was to evaluate the enhancement pattern and the diagnostic accuracy of gadofluorine M in comparison with gadopentetate dimeglumine in a rabbit VX2 tumor model.

Materials and methods

Thirteen rabbits with experimentally induced VX2 carcinomas in the thighs underwent sequential T1-weighted enhancement MR imaging using a 3.0 T MR imager, first with gadopentetate dimeglumine, and then 24 (n = 4) or 4 h (n = 9) later with gadofluorine M. In 4 rabbits with 13 tumors, the time-percentage enhancement (PE; i.e., percentage of signal intensity increase) curve was obtained for up to 24 h for each contrast agent. In 9 rabbits with 49 tumors (random numbers of VX2 tumors were inoculated at random sites in the thigh), 3 readers unaware of the histopathologic results interpreted the MR images and determined the number and conspicuity level of the detected tumors. The reference standard was the histopathology of the specimen.

Results

The time-to-peak PE for gadopentetate dimeglumine was 1 min and gadopentetate dimeglumine showed a rapid washout pattern. The time-to-peak PE for gadofluorine M was 30 min and gadofluorine M showed a plateau enhancement pattern for up to 24 h. The peak PE of gadofluorine M was approximately twice that of the same dose of gadopentetate dimeglumine (108.2 ± 14.8 vs. 51.5 ± 24.0). The sensitivities for detecting VX2 tumors by 3 readers were 89.8% (44/49), 85.7% (42/49), and 95.9% (47/49) for gadopentetate dimeglumine-enhanced MR imaging, and 87.8% (43/49), 89.8% (44/49), and 89.8% (44/49) for gadofluorine M-enhanced MR imaging. No significant differences in the sensitivities existed between the two contrast agents for any reader. However, the conspicuity level of tumors was superior with gadofluorine M-enhanced MR imaging for two readers and similar for the other reader.

Conclusion

Gadofluorine M showed strong and plateau enhancement of tumors for up to 24 h. In the reader study, gadofluorine M showed better conspicuity for VX2 tumors than gadopentetate dimeglumine, but had a similar sensitivity.     

Endorectal diffusion-weighted imaging in prostate cancer to differentiate malignant and benign peripheral zone tissue

PURPOSE: To determine if the apparent diffusion coefficient (ADC) can discriminate benign from malignant peripheral zone (PZ) tissue in patients with biopsy-proven prostate cancer that have undergone endorectal diffusion-weighted imaging (DWI) of the prostate. MATERIALS AND METHODS: Ten patients with prostate cancer underwent endorectal magnetic resonance imaging (MRI) in addition to DWI. A two-dimensional grid was placed over the axial images, and each voxel was graded by a 4-point rating scale to discriminate nonmalignant from malignant PZ tissue based on MR images alone. ADC was then determined for each voxel and plotted for nonmalignant and malignant voxels for the entire patient set. Second, with the radiologist aware of biopsy locations, any previously assigned voxel grade that was inconsistent with biopsy data was regrouped and ADCs were replotted. RESULTS: For the entire patient set, without and with knowledge of the biopsy data, the mean ADCs for nonmalignant and malignant tissue were 1.61 +/- 0.27 and 1.34 +/- 0.38 x 10(-3) mm2/second (P = 0.002) and 1.61 +/- 0.26 and 1.27 +/- 0.37 x 10(-3) mm2/second (P = 0.0005), respectively. CONCLUSION: DWI of the prostate is possible with an endorectal coil. The mean ADC for malignant PZ tissue is less than nonmalignant tissue, although there is overlap in individual values.     

Discrimination of axillary metastatic from nonmetastatic lymph nodes with PROPELLER diffusion-weighted MR imaging in a metastatic breast cancer model and its correlation with cellularity

Purpose:

To assess the accuracy of apparent diffusion coefficient (ADC) in the differentiation of axillary metastatic from nonmetastatic lymph nodes in rabbits with metastatic breast cancer and to determine the relationship between the ADC and the cellularity of axillary lymph nodes of two different types.

Materials and Methods:

The axillary lymph node models were created by inoculating VX2 cell suspensions in the mammary glands of 30 female rabbits. Conventional MR imaging and multi‐shot fast‐spin‐echo PROPELLER DW imaging were performed approximately 4 weeks after successful inoculation. Images of axillary lymph nodes were analyzed with regard to size and ADC. Differences in the forementioned criteria between the two types of lymph nodes were assessed with reference to histopathologic findings. Cellularity was correlated with the ADC in all selected axillary lymph nodes.

Results:

A total of 41 axillary metastatic and 29 inflammatory lymph nodes were successfully isolated. The size‐based criteria showed no significant difference between the malignant and inflammatory lymph nodes (Ps > 0.05); however, the ADC of metastatic nodes was significantly lower than that of inflammatory nodes (P < 0.001). There was a significant inverse correlation between the ADC and cellularity (r = ?0.674; P < 0.001) regardless of their different tissue types.

Conclusion:

DW imaging is a new promising functional technique for differentiating metastatic from inflammatory lymph nodes. Furthermore, cellularity has a significant influence on the ADC in both malignant and benign lymph nodes. J. Magn. Reson. Imaging 2012;36:624–631. © 2012 Wiley Periodicals, Inc.

     

Diffusion-weighted MRI in rectal cancer: apparent diffusion coefficient as a potential noninvasive marker of tumor aggressiveness

Purpose:

To assess the value of diffusion‐weighted MR imaging (DWI) as a potential noninvasive marker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values and MRI and histological prognostic parameters.

Materials and Methods:

Fifty rectal cancer patients underwent primary staging MRI including DWI before surgery and neo‐adjuvant therapy. In 47, surgery was preceded by short‐course radiation therapy (n = 28) or long‐course chemoradiation therapy (n = 19). Mean tumor ADC was measured and compared between subgroups based on pretreatment CEA levels, MRI parameters (mesorectal fascia ‐ MRF ‐ status; T‐stage; N‐stage) and histological parameters (differentiation grade: poorly differentiated, poorly moderately differentiated, moderately differentiated, moderately well differentiated, well‐differentiated; lymphangiovascular invasion).

Results:

Mean tumor ADCs differ between MRF‐free versus MRF‐invaded tumors (P = 0.013), the groups of cN0 versus cN+ cancers (P = 0.011), and between the several groups of histological differentiation grades (P = 0.025). There was no significant difference in mean ADCs between the various groups of CEA levels, the T stage, and the presence of lymphangiovascular invasion.

Conclusion:

Lower ADC values were associated with a more aggressive tumor profile. Significant correlations were found between mean ADC values and radiological MRF status, N stage and differentiation grade. ADC has the potential to become an imaging biomarker of tumor aggressiveness profile. J. Magn. Reson. Imaging 2012;35:1365–1371. © 2012 Wiley Periodicals, Inc.     

Predicting response to neoadjuvant chemoradiation therapy in locally advanced rectal cancer: diffusion-weighted 3 Tesla MR imaging

Purpose:

To evaluate the efficacy of diffusion‐weighted imaging (DWI) on 3 Tesla (T) MR imaging to predict the tumor response to neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.

Materials and Methods:

Thirty‐five patients who underwent neoadjuvant CRT and subsequent surgical resection were included. Tumor volume was measured on T2‐weighted MR images before and after neoadjuvant CRT and the percentage of tumor volume reduction was calculated. The apparent diffusion coefficient (ADC) value was measured on the DWI before and after neoadjuvant CRT, and the change of ADC (Δ ADC) was calculated. The histopathologic response was categorized either as a responder to CRT or as a nonresponder. The relationship between the ADC parameters and the percentage of tumor volume reduction or histopathologic response was then evaluated.

Results:

There was a significant correlation between tumor volume reduction and pre‐CRT ADC and Δ ADC, respectively (r = ?0.352, r = 0.615). Pre‐CRT ADC of the histopathologic responders was significantly lower than that of the histopathologic nonresponders (P = 0.034). Δ ADC of the histopathologic responders was significantly higher than that of the histopathologic nonresponders (P < 0.005).

Conclusion:

DWI on 3T MR imaging may be a promising technique for helping to predict and monitor the treatment response to neoadjuvant CRT in patients with locally advanced rectal cancer. J. Magn. Reson. Imaging 2012;35:110‐116. © 2011 Wiley Periodicals, Inc.