Pancreatic neuroendocrine tumor: added value of fusion of T2-weighted imaging and high b-value diffusion-weighted imaging for tumor detection

Objectives

To investigate the added value of fusion of high b-value diffusion-weighted images (DWI) and T2-weighted (T2) MR images for the detection of pancreatic neuroendocrine tumors (PNT).

Methods

18 patients with 18 histologically proven PNT were included. Two radiologists independently and retrospectively reviewed four randomized images sets (T2+T1, DWI, T2+DWI, and DWI+T2 fusion). Lesion detection confidence level was assessed using a three grade score (no lesion; uncertain lesion and certain lesion); lesion size and signal intensity were recorded. Apparent diffusion coefficients (ADC) of tumor and adjacent pancreas were measured.

Results

Readers 1 and 2 respectively detected 14/18 and 16/18 lesions on T2+T1, 13/18 and 12/18 on DWI, 16/18 and 15/18 on T2+DWI and 17/18 and 16/18 on DWI+T2 fusion. Lesion median size was 16 mm (range: 7 mm–40 mm), 22% were hyperfunctioning (all insulinomas) and 72% were low-grade (Rindi 1). All tumors except one (with cystic component) showed lower ADC than adjacent pancreatic parenchyma. Fusion imaging had significantly better detection score by both authors (p < 0.005) and provided the higher inter-reader agreement (kappa 0.7). DWI alone had the worst score for both readers.

Conclusions

Fusion images improve the detection of PNT, especially in patients with small isointense lesions on conventional MR sequences.     

Prostate cancer: utility of fusion of T2-weighted and high b-value diffusion-weighted images for peripheral zone tumor detection and localization

Purpose:

To retrospectively assess the utility of fusion of T2‐weighted images (T2WI) and high b‐value diffusion‐weighted images (DWI) for prostate cancer detection and localization.

Materials and Methods:

In this IRB‐approved HIPAA‐compliant study, 42 patients with prostate cancer underwent MRI including multiplanar T2WI and axial DWI before prostatectomy. Two independent radiologists first assessed multiplanar T2WI and axial DWI_b‐1000 images and recorded whether tumor was present in each sextant. Axial T2WI was then fused with axial DWI_b‐1000 images, and the radiologists re‐evaluated each sextant for tumor. Accuracy was compared using generalized estimating equations based on a binary logistic regression model.

Results:

The accuracy, sensitivity, specificity, PPV, and NPV for tumor detection on a sextant‐basis using separate and fused image sets was 65.1%, 50.8%, 78.0%, 67.8%, and 63.6% and 71.0%, 60.8%, 80.3%, 73.7%, and 69.3%, respectively, for reader 1, and 54.0%, 42.5%, 64.4%, 52.0%, and 55.2%, and 61.1%, 56.7%, 65.2%, 59.6%, and 62.3%, respectively, for reader 2. The improvements in accuracy, sensitivity, and NPV using fused images were statistically significant for both readers, as was the improvement in PPV for reader 2 (P ranging from <0.0001 to 0.041). With either separate or fused images, there was greater sensitivity for tumors of higher grade or larger size (P ranging from <0.001 to 0.099).

Conclusion:

Fusion of T2WI and high b‐value DWI resulted in significant improvements in sensitivity and accuracy for tumor detection on a sextant‐basis, with similar specificity. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Prostate cancer screening: the clinical value of diffusion-weighted imaging and dynamic MR imaging in combination with T2-weighted imaging

PURPOSE: To evaluate the clinical value of diffusion-weighted imaging (DWI) and dynamic MRI in combination with T2-weighted imaging (T2W) for the detection of prostate cancer. MATERIALS AND METHODS: A total of 83 patients with elevated serum prostate specific antigen (PSA) levels (>4.0 ng/mL) were evaluated by T2W, DWI, and dynamic MRI at 1.5 T prior to needle biopsy. The data from the results of the T2W alone (protocol A), combination of T2W and DWI (protocol B), and the combination of T2W+DWI and dynamic MRI (protocol C) were entered into a receiver operating characteristic (ROC) curve analysis, under results of systemic biopsy as the standard of reference. RESULTS: Prostate cancer was pathologically detected in 44 of the 83 patients. The sensitivity, specificity, accuracy, and the area under the ROC curve (Az) for the detection of prostate cancer were as follows: 73%, 54%, 64%, and 0.711, respectively, in protocol A; 84%, 85%, 84%, and 0.905, respectively, in protocol B; and 95%, 74%, 86%, and 0.966, respectively, in protocol C. The sensitivity, specificity, and accuracy were significantly different between the three protocols (P < 0.01). CONCLUSION: In patients with elevated serum PSA levels, the combination of T2W, DWI, and dynamic MRI may be a valuable tool for detecting prostate cancer and avoiding an unnecessary biopsy without missing prostate cancer.     

Perilesional hyperintense rim of malignant hepatic tumors on ferumoxide-enhanced T1-weighted gradient-echo MR images: correlation between MR imaging and histopathologic findings

PURPOSE: To correlate the perilesional hyperintense rim of malignant hepatic tumors seen on ferumoxide-enhanced T1-weighted gradient-echo (GE) MR images with histopathologic findings. MATERIALS AND METHODS: In 13 tumors in 12 patients, T1-weighted GE images (TE of 1.4 msec, flip angle of 90 degrees) obtained after IV administration of ferumoxide were evaluated. MR imaging was initiated within one hour of the completion of ferumoxide administration. Surgical resection for tumors was performed within an interval of two weeks of the MR imaging. Resected specimens were histopathologically examined for peritumoral sinusoidal congestion, desmoplastic reaction, compressed hepatic parenchyma, lymphocytic infiltration, and vascular proliferation. RESULTS: In twelve tumors (92%), prominently (N = 2), moderately (N = 5), and mildly to minimally (N = 5), a perilesional hyperintense rim was observed. Among histopathologic findings, the degree of peritumoral sinusoidal congestion correlated (R =.75, P <.04) with the degree of perilesional hyperintense rim. The thickness of the perilesional hyperintense rim showed a moderate positive correlation (R =.65, P <.02) with the thickness of peritumoral area with sinusoidal congestion. CONCLUSION: Perilesional hyperintense rim of malignant hepatic tumors on ferumoxide-enhanced T1-weighted GE images may correlate with sinusoidal congestion surrounding malignant hepatic tumors.     

超高b值弥散加权联合T2加权序列诊断外周带前列腺癌的价值

目的 探讨超高b值弥散加权成像（DWI）联合T2加权成像（T2WI）诊断外周带前列腺癌（PCa）的临床应用价值。 方法 选取2018年12月1日至2019年10月1日在佛山市第一人民医院行超声引导下前列腺靶点穿刺、临床病理学确诊并于穿刺前后1个月内行前列腺MRI检查的PCa患者41例,年龄49~89岁,中位年龄69岁。所有患者均行3.0T超高b值（分别为2000、3000 s/mm2）的DWI及T2WI脂肪抑制序列MRI成像。以前列腺靶点穿刺病理学结果为“金标准”,分别计算T2WI、DWI（b=2000 s/mm2）、DWI（b=3000 s/mm2）、T2WI+DWI（b=2000 s/mm2）、T2WI+DWI（b=3000 s/mm2）对PCa的诊断灵敏度、特异度和准确率。采用受试者工作特征（ROC）曲线分析计算各方法诊断PCa的曲线下面积。 结果 41例患者中,PCa患者26例（通过临床结合穿刺点位置确诊为外周带PCa）,良性前列腺增生患者15例。T2WI、DWI（b=2000 s/mm2）、DWI（b=3000 s/mm2）、T2WI+DWI（b=2000 s/mm2）、T2WI+DWI（b=3000 s/mm2）诊断PCa的灵敏度分别为0.962（25/26）、0.962（25/26）、0.962（25/26）、0.923（24/26）、0.923（24/26）,特异度分别为0.400（6/15）、0.667（10/15）、0.876（13/15）、0.800（12/15）、1.000（15/15）,准确率分别为0.756（31/41）、0.854（35/41）、0.926（38/41）、0.878（36/41）、0.951（39/41）,ROC曲线下面积分别为0.681、0.814、0.914、0.872、0.972（P=0.056、0.001、＜0.001、＜0.001、＜0.001）。 结论 T2WI+DWI（b=3000 s/mm2）序列图像诊断PCa具有较高的准确率,有望成为一种可靠的诊断前列腺疾病的无创性检查方法。     

Invited. Ultrafast T2-weighted imaging of the abdomen and pelvis: Use of single shot fast spin-echo imaging

Single shot (SS) rapid acquisition with relaxation enhancement (RARE) and half Fourier SS-RARE (HFSS-RARE, HASTE, or SS-FSE) sequences allow ultrafast imaging acquisition and generate high imaging quality. Images can be acquired within a very short time, without artifacts from physiologic motion. They are widely applied in the abdominal MRI. Clinical application of the ultrafast SS-RARE imaging techniques provide not only improved temporal resolution but better spatial resolution, higher SNR, and higher tissue contrast. Imaging parameters must be optimized for different MR scanners to obtain diagnostic images.     

Computed diffusion-weighted MR imaging for visualization of pancreatic adenocarcinoma: Comparison with acquired diffusion-weighted imaging

ObjectiveTo assess the feasibility of computed diffusion-weighted imaging (cDWI) in comparison with directly acquired DWI for visualizing pancreatic adenocarcinomas.Materials and methodsPatients with pancreatic adenocarcinoma underwent DWI at b-values of 0, 1000 (DWI₁₀₀₀), 1500 (DWI₁₅₀₀) and 2000 (DWI₂₀₀₀) s/mm². From DWIs at b-values of 0 and 1000 s/mm², we generated cDWIs at b-values of 1500 (cDWI₁₅₀₀) and 2000 (cDWI₂₀₀₀) s/mm². DWI findings of pancreatic adenocarcinomas (clear hyperintensity; hyperintensity with an unclear distal border; and isointensity), the image quality and the tumor to pancreas contrast ratio (CR) were compared between directly acquired DWI and cDWI.ResultsAmong the 63 included patients, clear hyperintense tumors were seen in 35 on DWI₁₀₀₀, 50 on DWI₁₅₀₀, 50 on cDWI₁₅₀₀, 53 on DWI₂₀₀₀ and 44 on cDWI₂₀₀₀. Incidence of clear hyperintense tumors was significantly higher on cDWI₁₅₀₀ than on DWI₁₀₀₀ (P = 0.013). There was no significant difference in the incidence of clear hyperintense tumors between DWI₁₅₀₀ and cDWI₁₅₀₀ (P > 0.999), but a lower incidence was seen on cDWI₂₀₀₀ than on DWI₂₀₀₀ (P = 0.028). Image quality was lower on cDWI than on DWI at b-values of 1500 (P = 0.002) and 2000 s/mm² (P < 0.001). The tumor to distal pancreas CR was significantly higher on cDWI₂₀₀₀ than on cDWI₁₅₀₀ (P < 0.001), and on cDWI₁₅₀₀ than on DWI₁₀₀₀ (P < 0.001). The cDWI showed a significantly higher tumor to distal pancreas CR than DWI at b-values of 1500 (P = 0.004) and 2000 s/mm² (P < 0.001).ConclusionscDWI₁₅₀₀ generated from b-values of 0 and 1000 s/mm² should be considered more effective than DWI₁₀₀₀ and at least as effective as DWI₁₅₀₀.     

Differentiation between cavernous hemangiomas and untreated malignant neoplasms of the liver with free-breathing diffusion-weighted MR imaging: Comparison with T2-weighted fast spin-echo MR imaging

Objective

To test interobserver variability of ADC measurements and compare the diagnostic performances of free-breathing diffusion-weighted (FBDW) with that of T2-weighted FSE (T2WFSE) MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.

Materials and methods

Thirty-five patients with cavernous hemangiomas and 35 with untreated hepatic malignant neoplasms had FBDW and T2WFSE MR imaging. Hepatic lesions were characterized with ADC measurement and visual evaluation. Interobserver agreement for ADC measurement was calculated. Association between ADC value and lesion type was assessed using univariate analysis. Sensitivity, specificity and accuracy of ADC values and visual evaluation of MR images for the diagnosis of untreated malignant hepatic neoplasm were compared.

Results

ADC measurements showed excellent interobserver correlation (intraclass correlation coefficient = 0.980). Malignant neoplasms had lower ADC values than hemangiomas for the two observers (1.11 × 10⁻³ mm²/s ± .21 × 10⁻³vs. 1.77 × 10⁻³ mm²/s ± .29 × 10⁻³ for observer 1 and 1.11 × 10⁻³ mm²/s ± .19 × 10⁻³vs. 1.79 × 10⁻³ mm²/s ± .32 × 10⁻³ for observer 2) and univariate analysis found significant correlations between lesion type and ADC values. Depending on ADC threshold value, accuracy for the diagnosis of malignant neoplasm varied from 82.9% to 94.3%. Using visual evaluation, FBDW showed better specificity and accuracy than T2WFSE MR images for the diagnosis of malignant neoplasm (97.1% vs. 77.1% and 94.3% vs. 62.9%, respectively).

Conclusion

FBDW imaging provides reproducible quantitative information and surpasses the value of T2WFSE MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.     

DWI、T2加权像及综合应用对前列腺癌诊断价值的研究

目的:通过对分别应用T2WI及DWI两种成像方法及其综合应用对前列腺癌进行定性诊断的比较,探讨两种方法各自及综合应用对前列腺癌的诊断价值。方法:应用1.5T MR成像仪对42例前列腺疾病患者进行前列腺磁共振高分辨成像,其中前列腺癌15例,良性病变包括良性前列腺增生及慢性前列腺炎症等27例。在MRI常规成像基础上行DWI扫描,扩散敏感系数(b)值分别为0、1000s/mm2。采用盲法阅片,按照前列腺6分区法将两种MR技术分别所得图像数据分区评估测量并采用5分制评分,根据两种技术的5分制评分进行T2加权像综合DWI方法评分,将所得结果与病理结果对照。利用SPSS 11.5分别做ROC曲线分析比较,计算各组方法诊断的敏感度、特异度及准确度等。结果:各组诊断方法的敏感度、特异度及ROC曲线下面积(Az)如下:T2WI:88.2%,67.2%和0.848±0.030,最佳诊断界值为3;ADC诊断:82.4%,81.6%和0.860±0.033,最佳界值为4;ADC结合T2WI诊断:78.4%,92.5%和0.922±0.021,最佳界值为4.结论:通过独立评估T2WI及DWI两种方法均可以有效诊断前列腺癌;两种成像方法综合应用诊断前列腺癌的准确度显著高于两种成像技术独立诊断,其诊断结果与病理分析一致性较好。     

Isotropic diffusion-weighted and spiral-navigated interleaved EPI for routine imaging of acute stroke

An interleaved echo-planar imaging (EPI) technique is presented for the rapid acquisition of isotropic diffusion-weighted images of stroke patients. Sixteen isotropic diffusion-weighted images at three b values are acquired in less than 3 min. A spiral navigator echo is used to measure the constant and linear phase shifts across the head in both the x and y directions which result from motion during the isotropic diffusion- sensitizing gradients. The measured k-space errors are corrected during a gridding reconstruction. The gridding kernel has a constant width in k_x and a variable width in k_y which eliminates variable data-density ghosts. The resulting isotropic diffusion-weighted images have excellent lesion-to-normal brain contrast, very good spatial resolution, and little sensitivity to susceptibility effects in the base of the brain. Examples of diffusion-weighted images and ADC maps from several stroke patients are shown.     

1.5T DWI在肺内良、恶性病变鉴别诊断中最适b值的探讨

目的:探讨1.5TDWI对肺内良、恶性病变的鉴别诊断价值及b值的优化。方法:搜集40例经病理/临床证实的肺内良、恶性病变患者(恶性病变23例,良性病变17例)的影像及临床资料,40例均经MSCT检查发现肺部病变,并行常规T1WI、T2WI以及多b值DWI(b=0,300,600,1000s/mm2)检查,测量3组b值测得的ADC值,分析不同b值对图像质量、信噪比(SNR)、对比噪声比(CNR)的影响,根据受试者工作特征(ROC)曲线评价不同b值下ADC值鉴别肺部良、恶性病变的诊断效能;并比较同一b值下良、恶性病变ADC值的差异。结果:随着b值的增加,DWI图像信号逐渐增高,ADC、SNR及CNR值逐渐下降;b值为300和600s/mm2两组图像SNR值差异无统计学意义(P>0.05),b值为300与1000s/mm2以及600与1000s/mm2两组SNR值差异均具有统计学意义(P均<0.05);CNR值在两两组间的差异均具有统计学意义(P均<0.05)。b值为300、600和1000s/mm2时,ROC的曲线下面积(AUC)分别为0.78、0.83和0.81,且均具有诊断意义(AUC均>0.5),当b=600s/mm2时,诊断效能最高。在同一b值下,恶性病变图像信号高于良性病变,且ADC值低于良性病变(P均<0.05)。结论:1.5T DWI多b值胸部扫描有助于鉴别肺内良、恶性病变,当b=600s/mm2时,对肺良、恶性病变的鉴别诊断效能最高。     

DWI在鉴别诊断膀胱良恶性病变中的应用价值

目的：探讨磁共振（magnetic resonance ,MR）弥散加权成像（diffusion-weighted imaging ,DWI）中的表观扩散系数（apparent diffusion coefficient ,ADC）及相对表观扩散系数（r-ADC）值在膀胱良恶性病变鉴别诊断中的应用价值。方法共收集2012年10月～2013年5月75例超声诊断为膀胱占位患者,并最终经膀胱镜病理确诊。所有患者均行常规横断位T1 WI、T2 WI、DWI（b值为0和1500s/mm2）,横断位和冠状位增强LAVA序列。测量病灶及病灶对侧膀胱壁的ADC值及r-ADC值进行统计学分析。结果所有恶性膀胱肿瘤病灶及4例良性病灶在DWI图像上病灶显示为明显高信号。恶性膀胱肿瘤病灶平均ADC值（0．85±0．30）×10-3 mm2/s明显低于良性病灶的 ADC值（1．62±0．86）×10-3 mm2/s）（ P ＜0．05）。恶性肿瘤性病灶的r-ADC值（0．74±0．27）也明显低于良性肿瘤性病灶（1．20±0．73）（ P ＜0．01）。结论结论DWI在鉴别膀胱良恶性肿瘤中有较高的应用价值,是一种较可靠的检查方法。     

高b值MR扩散加权成像在乳腺良恶性病变诊断中的应用价值

目的 评价高b值MR DWI及ADC值在乳腺良恶性病变诊断中的应用价值.方法 165例患者在行乳腺MR动态增强扫描前行不同b值(分别为500、1500 s/mm2)的DWI扫描,对171个怀疑或高度怀疑恶性病变者行回顾性分析.以正常乳腺组织为参考基准,选择增强图像中异常强化的高信号病变,同时在高b值(b= 1500 s/mm2)DWI中视觉判定是高信号的病变定义为恶性病变阳性结果,否则为良性病变阴性结果.对其中111个DWI视觉判定阳性结果的病变计算ADC值.依据全部病变穿刺活检病理诊断结果,应用Fisher精确检验和Wilcoxon秩和检验对比分析高b值DWI视觉评估中恶性和良性病变的阳性和阴性病灶数,以ADC值=1.13×10-3 mm2/s作为临界值,计算诊断的特异度和敏感度.结果 乳腺病变穿刺活检病理证实的171个乳腺病变中,91个恶性病变,80个良性病变.高b值DWI视觉评估,139个阳性结果中,恶性病变83个,良性病变56个;32个阴性结果中,良性病变24个,恶性病变8个(非肿块性导管原位癌),差异有统计学意义(P＜0.01).所有浸润性癌和肿块样导管原位癌(DCIS)在DWI视觉判定中为阳性,8例非肿块性DCIS判定为假阴性,总体的敏感度为91.2％ (83/91),特异性为30.0％ (24/80).110个肿块样病变和1个局灶性病变DWI视觉评估阳性结果的病变中,63个恶性病变平均ADC值为(0.73±0.24)×10-3 mm2/s,48个良性病变平均ADC值为(1.19±0.42)×10-3mm2/s,差异有统计学意义(Z=5.818,P＜0.01).以ADC值=1.13×10-3mm2/s作为临界值时,61个恶性病变为阳性结果,2个黏液癌为假阴性结果;27个良性病变为阴性结果,21个良性病变为假阳性,诊断敏感度是96.8％(61/63),特异度为56.2％ (27/48).结论 高b值DWI及ADC值对乳腺良恶性病变的鉴别诊断有一定的作用,但在诊断非肿块性乳腺病变时仍需慎重.     

Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning

Purpose

To compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI.

Material and methods

27 consecutive patients (15 male, range 27.1–88.8 years, mean 66.9 years) underwent 1.5 T MRI prior to chemoradiation (45 Gy in 25 fractions; oral capecitabine 850 mg/m²), including axial T2W MRI (TR = 6600 ms, TE = 90 ms) and DWI (TR = 3000 ms, TE = 77 ms, b = 0, 100, 800 s/mm²). 3D tumour volume (cm³) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann–Whitney test. Observer agreement was assessed using Bland–Altman statistics. Significance was at 5%.

Results

Artefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b = 800 s/mm²) 3D GTVin cm³ were 33.97 (4.44–199.8) and 31.38 (2.43–228), respectively, for Reader One and 43.78 (7.57–267.7) and 42.45 (3.68–251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p = 0.52 Reader One; p = 0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were −9.84 (−54.96 to +35.28) cm³ and −14.79 (−54.01 to +24.43) cm³ respectively.

Conclusion

Smaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.     

Evaluation of optimized inversion-recovery fat-suppression techniques for T2-weighted abdominal MR imaging

PURPOSE: To test the theoretical benefits of a spectral attenuated inversion-recovery (SPAIR) fat-suppression (FS) technique in clinical abdominal MRI by comparison to conventional inversion-recovery (IR) FS combined with T2-weighted (T2W) partial Fourier single shot fast spin echo (SSFSE). MATERIALS AND METHODS: 1.5T MRI studies of the abdomen were performed in 28 patients with liver lesions (hemangiomas n = 14; metastases n = 14). T2W sequences were acquired using IR and SPAIR SSFSE. Measurements included retroperitoneal and mesenteric fat signal-to-noise (SNR) to evaluate FS; liver lesion contrast-to-noise (CNR) to evaluate bulk water signal recovery effects; and bowel wall delineation to evaluate susceptibility and physiological motion effects. RESULTS: SPAIR-SSFSE images produce significantly improved FS and liver lesion CNR. The mean SNR of the retroperitoneal and mesenteric fat for SPAIR SSFSE was 20.5 +/- 10.2 (+/-1 SD) and 12.7 +/- 6.2, compared to 43.2 +/- 24.1 (P = 0.000006) and 29.3 +/- 16.8 (P = 0.0000005) for IR-SSFSE. SPAIR-SSFSE images produced higher CNR for both hemangiomas CNR = 164 +/- 88 vs. 126 +/- 83 (P = 0.00005) and metastases CNR = 75 +/- 27 vs. 53 +/- 19 (P = 0.007). Bowel wall visualization was significantly improved using SPAIR-SSFSE (P = 0.002). CONCLUSION: The theoretical benefits of SPAIR over conventional IR FS translate into significant multiple improvements that can be measured on clinical abdominal MRI scans.     

The value of diffusion-weighted imaging in combination with T2-weighted imaging for rectal cancer detection

OBJECTIVE: To evaluate the clinical value of diffusion-weighted imaging (DWI) in combination with T(2)-weighted imaging (T(2)WI) for the detection of rectal cancer as compared with T(2)WI alone. MATERIALS AND METHODS: Forty-five patients with rectal cancer and 20 without rectal cancer underwent DWI with parallel imaging and T(2)WI on a 1.5 T scanner. Images were independently reviewed by two readers blinded to the results to determine the detectability of rectal cancer. The detectability of T(2)W imaging without and with DW imaging was assessed by means of receiver operating characteristic analysis. The interobserver agreement between the two readers was calculated with kappa statistics. RESULTS: The ROC analysis showed that each of two readers achieved more accurate results with T(2)W imaging combined with DW imaging than with T(2)W imaging alone significantly. The A(z) values for the two readers for each T(2)WI and T(2)WI combined with DWI were 0.918 versus 0.991 (p=0.0494), 0.934 versus 0.997 (p=0.0475), respectively. The values of kappa were 0.934 for T(2)WI and 0.948 for T(2)WI combined with DWI between the two readers. CONCLUSION: The addition of DW imaging to conventional T(2)W imaging provides better detection of rectal cancer.     

DWI结合高分辨T_2WI磁共振在子宫内膜癌分期中的价值

目的:探讨DWI结合高分辨T2WI在子宫内膜癌分期中的价值。方法:回顾性分析70例经手术病理证实的子宫内膜癌DWI及高分辨T2WI表现,测量其ADC值,判断其浸润范围,并与术后病理结果相比较。结果:DWI结合高分辨T2WI对子宫内膜癌2009FIGO分期准确性为94.3%,评价浅肌层、深肌层浸润的敏感度、特异度和准确度分别为94.5%、82.4%、94.3%和83.3%、95.3%、94.3%;评价子宫内膜癌宫颈基质浸润的敏感度、特异度和准确度分别为100%、100%和100%。结论:DWI结合高分辨T2WI磁共振能够提高子宫内膜癌浸润深度评价的准确度,有助于子宫内膜癌的诊断、分期及帮助制定治疗计划。     

Added value of diffusion-weighted MR imaging to T2-weighted and dynamic contrast-enhanced MR imaging in T staging of gastric cancer

ObjectiveTo assess the utilization of diffusion-weighted (DW) magnetic resonance (MR) imaging in T staging of gastric cancer prospectively.MethodsFifty-one patients underwent T2-weighted (T2W), contrast-enhanced (CE) and DW MR imaging. Two radiologists independently interpreted the images for T staging of the tumors.ResultsThe overall accuracy of T staging in pT1-4 gastric cancers by T2W+CE+DW (88.2%) was significantly higher than that by T2W+CE and T2W+DW (both 76.5%, P= .031).ConclusionDW adds useful information to T2W and CE MR imaging in T staging of gastric cancer.     

Feasibility study of computed vs measured high b-value (1400 s/mm2) diffusion-weighted MR images of the prostate

AIM: To evaluate the impact of computed b = 1400 s/mm² (C-b1400) vs measured b = 1400 s/mm² (M-b1400) diffusion-weighted images (DWI) on lesion detection rate, image quality and quality of lesion demarcation using a modern 3T-MR system based on a small-field-of-view sequence (sFOV).METHODS: Thirty patients (PSA: 9.5 ± 8.7 ng/mL; 68 ± 12 years) referred for magnetic resonance imaging (MRI) of the prostate were enrolled in this study. All measurements were performed on a 3T MR system. For DWI, a single-shot EPI diffusion sequence (b = 0, 100, 400, 800 s/mm²) was utilized. C-b1400 was calculated voxelwise from the ADC and diffusion images. Additionally, M-b1400 was acquired for evaluation and comparison. Lesion detection rate and maximum lesion diameters were obtained and compared. Image quality and quality of lesion demarcation were rated according to a 5-point Likert-type scale. Ratios of lesion-to-bladder as well as prostate-to-bladder signal intensity (SI) were calculated to estimate the signal-to-noise-ratio (SNR).RESULTS: Twenty-four lesions were detected on M-b1400 images and compared to C-b1400 images. C-b1400 detected three additional cancer suspicious lesions. Overall image quality was rated significantly better and SI ratios were significantly higher on C-b1400 (2.3 ± 0.8 vs 3.1 ± 1.0, P < 0.001; 5.6 ± 1.8 vs 2.8 ± 0.9, P < 0.001). Comparison of lesion size showed no significant differences between C- and M-b1400 (P = 0.22).CONCLUSION: Combination of a high b-value extrapolation and sFOV may contribute to increase diagnostic accuracy of DWI without an increase of acquisition time, which may be useful to guide targeted prostate biopsies and to improve quality of multiparametric MRI (mMRI) especially under economical aspects in a private practice setting.     

T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Objective

To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods

Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results

SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001).

Conclusion

SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.