Differentiation of well‐differentiated hepatocellular carcinomas from other hepatocellular nodules in cirrhotic liver: Value of SPIO‐enhanced MR imaging at 3.0 Tesla

Purpose

To determine the diagnostic value of superparamagnetic iron oxide (SPIO)‐enhanced MRI for the differentiation of well‐differentiated hepatocellular carcinomas (WD‐HCCs) from other hepatocellular nodules in cirrhotic liver.

Materials and Methods

This study included 114 patients with 216 histologically confirmed hepatocellular nodules, i.e., 23 dysplastic nodules (DNs), 37 WD‐HCCs, and 156 moderately or poorly differentiated HCCs (MD‐/PD HCCs), who underwent SPIO‐enhanced MRI at 3.0T. MRI included T2‐weighted fast‐spin echo and T2*‐weighted gradient recalled echo (GRE) sequences before and after administration of ferucarbotran. The contrast‐to‐noise ratio (CNR) of the lesion was calculated. Reviewers analyzed signal intensity (SI) of the nodules and their enhancement features on SPIO‐enhanced images. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the diagnosis of WD‐HCC were also calculated.

Results

The mean CNR of WD‐HCC was significantly higher than that of DN on T2*‐weighted image. Incomplete high SI on SPIO‐enhanced T2*‐weighted images were seen in 56.8% of WD‐HCC. The most prevalent enhancement features of WD‐HCCs on SPIO‐enhanced T2*‐weighted images, were iso SI with high SI foci [32.5% (12/37)] and homogenous subtle high SI [24.3% (9/37)]. Alternatively, 22 of 23 DNs (95.7%) showed low‐ or iso SI, and 145 of 156 (94.9%) MD‐/PD HCCs showed strong high SI. When iso SI with high SI foci or subtle homogenous high SI nodule was considered as diagnostic criteria for WD‐HCC, we could identify 56.8% of the WD‐HCCs but only 4.4% of the DNs and 3.2% of the MD‐/PD HCCs.

Conclusion

WD‐HCCs have characteristic enhancement features that differentiate them from DNs and MD‐/PD HCCs on SPIO‐enhanced 3.0T MRI. The lesion conspicuity was better on T2*‐weighted images than that on T2‐weighted images. J. Magn. Reson. Imaging 2009;29:328–335. © 2009 Wiley‐Liss, Inc.     

Characterization of hyperintense nodules on precontrast T1-weighted MRI: utility of gadoxetic acid-enhanced hepatocyte-phase imaging

Purpose:

To evaluate the utility of gadoxetic acid‐enhanced hepatocyte‐phase magnetic resonance imaging (MRI) in characterization of T1‐weighted hyperintense nodules within cirrhotic liver.

Materials and Methods:

This retrospective study was approved by our Institutional Review Board. Thirty‐four nodules hyperintense in unenhanced T1‐weighted MRI with histopathological confirmation from a collection of 19 patients were included. Tumor size, signal intensity on T1‐weighted, and T2‐weighted imaging as well as enhancement patterns on contrast‐enhanced dynamic/hepatocyte‐phase imaging were recorded. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of hepatocyte‐phase imaging.

Results:

Evaluation of the nodules with standard of reference revealed 15 dysplastic nodules (DN), seven well‐differentiated hepatocellular carcinomas (wHCC), and 12 moderately differentiated HCCs (mHCC). The mean size of dysplastic nodules was smaller than that of HCCs (P < 0.001). Using the HCC criteria (T2W or arterial enhancement followed with portal venous washout), 11/19 HCC were correctly characterized. Using solely hypointensity (compared to the surrounding liver parenchyma) during the hepatocyte phase as the criterion, 18/19 HCC were correctly characterized. There were seven additional HCCs diagnosed with hepatocyte‐phase imaging (P = 0.02).

Conclusion:

Gadoxetic acid‐enhanced MRI with hepatocyte‐phase imaging is superior to gadoxetic acid‐enhanced MRI with conventional criteria alone in characterization of T1W hyperintense nodules. J. Magn. Reson. Imaging 2011;33:625–632. © 2011 Wiley‐Liss, Inc.     

肝硬化结节与小肝癌的CT、MRI诊断

在肝硬化结节及小肝癌的早期诊断方面,CT、MRI仍是目前临床工作中最重要的方法,本文阐述肝硬化结节演变为肝癌过程中的几个重要环节的CT、MRI表现及国内、外对此的研究现状,这几个环节包括肝硬化再生结节、发育不良性结节(低、中、高级)、小肝癌及肝癌,它们在CT、MRI表现上各有特征,但相互间也有影像学表现上的重叠,故多数较典型者可以通过CT密度值、MRI信号值及增强表现判断其性质,少部分诊断有困难的病灶可以通过双动脉期扫描、MR菲立磁增强及灌注成像等方法提供更多的诊断信息。     

Support vector machine multiparametric MRI identification of pseudoprogression from tumor recurrence in patients with resected glioblastoma

Purpose

To automatically differentiate radiation necrosis from recurrent tumor at high spatial resolution using multiparametric MRI features.

Materials and Methods

MRI data retrieved from 31 patients (15 recurrent tumor and 16 radiation necrosis) who underwent chemoradiation therapy after surgical resection included post‐gadolinium T1, T2, fluid‐attenuated inversion recovery, proton density, apparent diffusion coefficient (ADC), and perfusion‐weighted imaging (PWI) ‐derived relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time maps. After alignment to post contrast T1WI, an eight‐dimensional feature vector was constructed. An one‐class‐support vector machine classifier was trained using a radiation necrosis training set. Classifier parameters were optimized based on the area under receiver operating characteristic (ROC) curve. The classifier was then tested on the full dataset.

Results

The sensitivity and specificity of optimized classifier for pseudoprogression was 89.91% and 93.72%, respectively. The area under ROC curve was 0.9439. The distribution of voxels classified as radiation necrosis was supported by the clinical interpretation of follow‐up scans for both nonprogressing and progressing test cases. The ADC map derived from diffusion‐weighted imaging and rCBV, rCBF derived from PWI were found to make a greater contribution to the discrimination than the conventional images.

Conclusion

Machine learning using multiparametric MRI features may be a promising approach to identify the distribution of radiation necrosis tissue in resected glioblastoma multiforme patients undergoing chemoradiation. J. Magn. Reson. Imaging 2011;33:296–305. © 2011 Wiley‐Liss, Inc.     

Intraprocedural diffusion‐weighted PROPELLER MRI to guide percutaneous biopsy needle placement within rabbit VX2 liver tumors

Purpose

To test the hypothesis that diffusion‐weighted (DW)‐PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) magnetic resonance imaging (MRI) can be used to guide biopsy needle placement during percutaneous interventional procedures to selectively target viable and necrotic tissues within VX2 rabbit liver tumors.

Materials and Methods

Our institutional Animal Care and Use Committee approved all experiments. In six rabbits implanted with 15 VX2 liver tumors, baseline DW‐PROPELLER images acquired prior to the interventional procedure were used for apparent diffusion coefficient (ADC) measurements. Next, intraprocedural DW‐PROPELLER scans were performed with needle position iteratively adjusted to target viable, necrotic, or intermediate border tissue regions. DW‐PROPELLER ADC measurements at the selected needle tip locations were compared with the percentage of tumor necrosis qualitatively assessed at histopathology.

Results

DW‐PROPELLER images demonstrated intratumoral tissue heterogeneity and clearly depicted the needle tip position within viable and necrotic tumor tissues. Mean ADC measurements within the region‐of‐interest encompassing the needle tip were highly correlated with histopathologic tumor necrotic tissue assessments.

Conclusion

DW‐PROPELLER is an effective method to selectively position the biopsy needle tip within viable and necrotic tumor tissues. The DW‐PROPELLER method may offer an important complementary tool for functional guidance during MR‐guided percutaneous procedures. J. Magn. Reson. Imaging 2009;30:366–373. © 2009 Wiley‐Liss, Inc.     

Gadoxetic acid-enhanced MRI findings of early hepatocellular carcinoma as defined by new histologic criteria

Purpose:

To describe the imaging features of early hepatocellular carcinoma (HCC) on gadoxetic acid‐enhanced MRI (Gd‐EOB‐MRI) in comparison with multidetector computed tomography (MDCT) examinations.

Materials and Methods:

We analyzed imaging findings of 19 pathologically proven early HCC lesions in 15 patients who underwent both MDCT and Gd‐EOB‐MRI at 3.0 Tesla (T) units before surgery. MRI included in‐phase and out‐of‐phase T1‐weighted dual‐echo gradient‐recalled‐echo sequences, dynamic T1‐weighted images before and after bolus injection of gadoxetic acid disodium, fat‐saturated T2‐weighted fast spin‐echo sequences, and T1‐weighted hepatobiliary phase images 20 min after contrast injection. Two radiologists retrospectively evaluated the signal intensities and enhancement features on MRI and MDCT.

Results:

None of the lesions displayed arterial enhancement and washout on MDCT. On Gd‐EOB‐MRI, six (32%) lesions showed T2‐hyperintensity, five (26%) lesions showed signal drop on opposed‐phase. Three lesions (16%) showed arterial enhancement and washout. Twelve (63%), 13 (68%), and 15 (79%) lesions were hypointense on hepatic venous, equilibrium, and hepatobiliary phase, respectively.

Conclusion:

Most early HCCs did not show arterial enhancement and washout pattern on both MDCT and Gd‐EOB‐MRI. Gd‐EOB‐MRI may provide several ancillary findings for diagnosis of early HCC such as decreased hepatobiliary uptake, T2 hyperintensity and signal drop in opposed phase. J. Magn. Reson. Imaging 2012;393‐398. © 2011 Wiley Periodicals, Inc.     

Detection of hepatocellular carcinoma (HCC) using super paramagnetic iron oxide (SPIO)‐enhanced MRI: Added value of diffusion‐weighted imaging (DWI)

Purpose:

To evaluate whether diffusion‐weighted imaging (DWI) improves the detection of hepatocellular carcinoma (HCC) on super paramagnetic iron oxide (SPIO)‐enhanced MRI.

Materials and Methods:

This retrospective study group consisted of 30 patients with 50 HCC nodules who underwent MRI at 1.5 Tesla. Two combined MR sequence sets were compared for detecting HCC: SPIO‐enhanced MRI (axial T2‐weighted fast spin‐echo (FSE) and T1‐/T2*‐weighted fast field echo (FFE) scanned before and after administration of ferucarbotran) and SPIO‐enhanced MRI + DWI (SPIO‐enhanced MRI with axial DWI scanned before and after administration of ferucarbotran). Three blinded readers independently reviewed for the presence of HCC on a segment‐by‐segment basis using a four‐point confidence scale. The performance of the two combined MR sequence sets was evaluated using receiver operating characteristic (ROC) analysis.

Results:

The average area under the ROC curve (Az) of the three readers for the SPIO‐enhanced MRI + DWI set (0.870 ± 0.046) was significantly higher that that for the SPIO‐enhanced MRI set (0.820 ± 0.055) (P = .025). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of HCC were 66.0%, 98.0%, 90.0%, and 91.4%, respectively, for the SPIO‐enhanced MRI set, and 70.0%, 98.6%, 92.9%, and 92.4%, respectively, for the SPIO‐enhanced MRI + DWI set.

Conclusion:

The SPIO‐enhanced MRI + DWI set outperformed the SPIO‐enhanced MRI set for depicting HCC. J. Magn. Reson. Imaging 2010; 31: 373–382. © 2010 Wiley‐Liss, Inc.     

Effect of disease progression on liver apparent diffusion coefficient and T2 values in a murine model of hepatic fibrosis at 11.7 Tesla MRI

Purpose:

To evaluate the effects of hepatic fibrosis on ADC and T₂ values of ex vivo murine liver specimens imaged using 11.7 Tesla (T) MRI.

Materials and Methods:

This animal study was IACUC approved. Seventeen male, C57BL/6 mice were divided into control (n = 2) and experimental groups (n = 15), the latter fed a 3, 5‐dicarbethoxy‐1, 4‐dihydrocollidine (DDC) supplemented diet, inducing hepatic fibrosis. Ex vivo liver specimens were imaged using an 11.7T MRI scanner. Spin‐echo pulsed field gradient and multi‐echo spin‐echo acquisitions were used to generate parametric ADC and T₂ maps, respectively. Degrees of fibrosis were determined by the evaluation of a pathologist as well as digital image analysis. Scatterplot graphs comparing ADC and T₂ to degrees of fibrosis were generated and correlation coefficients were calculated.

Results:

Strong correlation was found between degrees of hepatic fibrosis and ADC with higher degrees of fibrosis associated with lower hepatic ADC values. Moderate correlation between hepatic fibrosis and T₂ values was seen with higher degrees of fibrosis associated with lower T₂ values.

Conclusion:

Inverse relationships between degrees of fibrosis and both ADC and T₂ are seen, highlighting the utility of these parameters in the ongoing development of an MRI methodology to quantify hepatic fibrosis. J. Magn. Reson. Imaging 2012;35:140‐146. © 2011 Wiley Periodicals, Inc.     

Small nodules (1-2 cm) in liver cirrhosis: characterization with contrast-enhanced ultrasound

Objective

To determine the diagnostic efficacy of arterial phase contrast-enhanced ultrasound (CEUS) for characterizing small hepatic nodules (1-2 cm) in patients with high-risk for hepatocellular carcinoma (HCC).

Materials and methods

Over 12 months, CEUS was performed in 59 patients at high-risk for HCC with small hepatic nodules (1-2 cm; mean, 1.5 cm). Based only on arterial phase (<45 s) vascular intensity and pattern, lesions were prospectively diagnosed as HCC if there was hypervascularity without known features of hemangioma. The diagnosis of HCC was made regardless of the presence or absence of washout. Verification of diagnosis was made by liver transplantation (n = 13), biopsy (n = 12), resection (n = 3) or clinical and imaging follow-up for at least 12 months (n = 31).

Results

At of the time of CEUS, the 59 nodules were diagnosed as HCC in 26 and benign lesions in 33, including 20 regenerative/dysplastic nodules (RN/DN), 11 hemangiomas, and 2 focal fat sparing. All 26 nodules with arterial phase hypervascularity without hemangioma-like features were HCC. However, CEUS misdiagnosed HCC as RN/DN in 4 cases with arterial iso- (n = 3) or hypovascularity (n = 1). CEUS correctly diagnosed all 11 hemangiomas. The sensitivity, specificity, and accuracy of CEUS for diagnosing HCC were 86.7, 100, and 93.2%.

Conclusions

Arterial phase vascular intensity and pattern of CEUS are highly accurate for the diagnosis of small (1-2 cm) HCC and hemangioma in liver cirrhosis. On CEUS, arterial phase hypervascularity without a hemangioma-pattern alone may be sufficient for diagnosis of small HCC. Infrequent iso/hypovascular HCC may erroneously suggest RN/DN necessitating biopsy or close follow-up.     

Prediction of locally recurrent prostate cancer after radiation therapy: Incremental value of 3T diffusion‐weighted MRI

Purpose

To prospectively evaluate the incremental value of diffusion‐weighted imaging (DWI) with apparent diffusion coefficient (ADC) maps in addition to T2‐weighted imaging (T2WI) for predicting locally recurrent prostate cancer in patients with biochemical failure after radiation therapy.

Materials and Methods

Thirty‐six consecutive patients with an increased prostate‐specific antigen level after radiation therapy underwent 3T MRI followed by transrectal biopsy. The MRI findings and biopsy results were correlated in sextant prostate sectors of peripheral zones (PZs). Two radiologists in consensus reviewed T2WI and combined T2WI and DWI with ADC maps, and rated the likelihood of recurrent cancer on a five‐point scale. ADC values were calculated for recurrent cancer and benign tissue.

Results

Of 216 sectors, 65 prostate sectors (30%) were positive for cancer in 18 patients. For predicting recurrent cancer, combined T2WI and DWI showed a greater sensitivity compared to T2WI (P < 0.001). A significantly greater area under the receiver operating characteristics curve (Az) was determined for combined T2WI and DWI (Az = 0.879, P < 0.01) as compared to T2WI (Az = 0.612). Mean ADC values between recurrent cancer and benign tissue showed a statistically significant difference (P < 0.01).

Conclusion

For predicting locally recurrent prostate cancer after radiation therapy, the use of combined T2WI and DWI showed a better diagnostic performance compared to T2WI. J. Magn. Reson. Imaging 2009;29:391–397. © 2009 Wiley‐Liss, Inc.     

Initial experience of 3 tesla apparent diffusion coefficient values in differentiating benign and malignant thyroid nodules

Purpose:

To evaluate the role of diffusion‐weighted magnetic resonance imaging (DWMRI) in differentiating benign and malignant thyroid nodules using a 3 Tesla (T) MRI scanner.

Materials and Methods:

Twenty‐eight nodules in 25 patients and 14 healthy control cases were included in the study. DWMRI was acquired with 6 b values with a 3T MRI scanner. The apparent diffusion coefficient (ADC) values of the nodules were calculated from reconstructed ADC map images and were compared with the final histopathological diagnoses.

Results:

The mean ADC value of the benign nodules was 1548 ± 353.4 (×10^?6 mm²/s), and the mean ADC of the malignant nodules was 814 ± 177.12 (×10^?6 mm²/s). The normal thyroid tissue had a mean ADC value of 1323.43 ± 210.35 × 10^?6 mm²/s (958–1689 × 10^?6 mm²/s) in the healthy control group. The ADC values were significantly different among the three groups (P = 0.001). An ADC value of 905 × 10^?6 mm²/s was determined to be the cutoff value for differentiating benign and malignant nodules, with 90% (55.5–98.3) sensitivity and 100% (81.3–100.0) specificity.

Conclusion:

This study suggests that the ADC values of nodules measured with a 3T MRI scanner could help in differentiating benign thyroid nodules from malignant nodules. J. Magn. Reson. Imaging 2013;37:1077–1082. © 2012 Wiley Periodicals, Inc.

     

Siderotic nodules at MR imaging: regenerative or dysplastic?

OBJECTIVE: To determine if iron containing "siderotic" nodules detected at magnetic resonance (MR) imaging are regenerative (RN) or dysplastic (DN) and to attempt to identify features that may distinguish them. MATERIAL AND METHODS: MR imaging (1.5 T) was performed on 77 cirrhotic patients who underwent orthotopic liver transplantation within 0-117 days (mean 30 days) of MR imaging. Two readers retrospectively evaluated breath-hold gradient-echo pulse sequences (echo time > or =9.0 ms, flip angle < or =45 degrees) for the presence of hypointense nodules, which were classified as micronodular (< or =3 mm), macronodular (>3 mm), or mixed. Nodule distribution was classified as focal (<5), scattered (5-20), or diffuse (>20) per slice. Thin section pathologic correlation was available in all cases, and Prussian blue iron stains were performed. RESULTS: Of 35 patients with pathologically proven siderotic nodules, 10 (29%) had at least 2 siderotic DN. MR detected siderotic nodules in 10 of 10 (100%) patients with siderotic DN and RN, and in 18 of 25 patients (72%) with siderotic RN only. CONCLUSION: Siderotic RN cannot be reliably distinguished from siderotic DN with MR imaging, and therefore the widely used term "siderotic regenerative nodule" should be avoided and replaced by "siderotic nodule."     

High-resolution MRI of excised human prostate specimens acquired with 9.4T in detection and identification of cancers: validation of a technique

Purpose:

To evaluate feasibility of high‐resolution, high‐field ex vivo prostate magnetic resonance imaging (MRI) as an aid to guide pathologists' examination and develop in vivo MRI methods.

Materials and Methods:

Unfixed excised prostatectomy specimens (n = 9) were obtained and imaged immediately after radical prostatectomy under an Institutional Review Board‐approved protocol. High‐resolution T2‐weighted (T2W) MRI of specimens were acquired with a Bruker 9.4 T scanner to correlate with whole‐mount histology. Additionally, T2 and apparent diffusion coefficient (ADC) maps were generated.

Results:

By visual inspection of the nine prostate specimens imaged, high‐resolution T2W MRI showed improved anatomical detail compared to published low‐resolution images acquired at 4 T as published by other investigators. Benign prostatic hyperplasia, adenocarcinomas, curvilinear duct architecture distortion due to adenocarcinomas, and normal radial duct distribution were readily identified. T2 was ≈10 msec longer (P < 0.03) and the ADC was ≈1.4 times larger (P < 0.002) in the normal peripheral zone compared to the peripheral zone with prostate cancer.

Conclusion:

Differences in T2 and ADC between benign and malignant tissue are consistent with in vivo data. High‐resolution, high‐field MRI has the potential to improve the detection and identification of prostate structures. The protocols and techniques developed in this study could augment routine pathological analysis of surgical specimens and guide treatment of prostate cancer patients. J. Magn. Reson. Imaging 2011. © 2011 Wiley‐Liss, Inc.     

Improving detection of siderotic nodules in cirrhotic liver with a multi-breath-hold susceptibility-weighted imaging technique

Purpose:

To evaluate the role of abdominal susceptibility‐weighted imaging (SWI) in the detection of siderotic nodules in cirrhotic liver.

Materials and Methods:

Forty patients with pathologically identified liver cirrhosis and 40 age/sex‐matched normal controls underwent T1‐, T2‐, T2*‐weighted imaging and SWI at 3T. Two radiologists prospectively analyzed all magnetic resonance imaging (MRI) studies. Siderotic nodules detected by each imaging technique were counted for comparison. The conspicuity of siderotic nodules was assessed using a scale from 1 to 3 (1, weak; 2, moderate; 3, prominent).

Results:

The number of siderotic nodules detected by SWI (3863) was significantly greater than that of T1‐weighted imaging (262, P < 0.001), T2‐weighted imaging (842, P < 0.001), and T2*‐weighted imaging (2475, P < 0.001). No suspected siderotic nodules were detected in normal controls by any imaging technique.

Conclusion:

SWI appears to provide the most sensitive method to detect siderotic nodules in cirrhotic liver. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Endometrial cancer: Utility of diffusion‐weighted magnetic resonance imaging with background body signal suppression at 3T

Purpose:

To prospectively assess the usefulness of diffusion‐weighted magnetic resonance imaging (MRI) with background body signal suppression (DWIBS) at 3T for the preoperative evaluation of endometrial cancer.

Materials and Methods:

Fifty‐two consecutive patients with biopsy‐proven endometrial cancer were examined with a 3T MR scanner, followed by a hysterectomy. MR examinations included T2‐weighted (T2WI), DWIBS, and dynamic contrast‐enhanced T1‐weighted imaging (DCEI). The apparent diffusion coefficient (ADC) was calculated in the tumor and normal myometrium. According to tumor grade, the mean ADC of the tumor was analyzed. The depth of myometrial invasion was independently assessed by two radiologists for three MRI datasets on a five‐point scale.

Results:

The mean ADC of the tumors was significantly lower than that of normal myometrium (P < 0.001). The mean ADC of grades 2 or 3 was significantly lower than grade 1 (P < 0.01). For predicting myometrial invasion, the specificity, accuracy, and area under the curve of combined T2WI and DWIBS in both readers were similar to DCEI (P > 0.05). Interreader agreement in all MRI datasets was excellent.

Conclusion:

DWIBS at 3T has potential for being an effective method for the preoperative evaluation of endometrial cancer. J. Magn. Reson. Imaging 2013;37:1151–1159. © 2012 Wiley Periodicals, Inc.     

Effect of Gd‐EOB‐DTPA on T2‐weighted and diffusion‐weighted images for the diagnosis of hepatocellular carcinoma

Purpose:

To evaluate the effect of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA) on T2‐weighted imaging (T2WI) and diffusion‐weighted imaging (DWI) for the diagnosis of hepatocellular carcinoma (HCC).

Materials and Methods:

The phantom signal intensity was measured. We also evaluated 72 patients including 30 patients with HCC. T2WI and DWI were obtained before and then 4 and 20 min after injecting the contrast medium. The signal to noise ratio (SNR), contrast to noise ratio (CNR), and apparent diffusion coefficient (ADC) were calculated in the tumor and liver parenchyma.

Results:

The phantom signal intensity increased on T2WI at a concentration of contrast medium less than 0.2 mmol/L but decreased when the concentration exceeded 0.4 mmol/L. SNR of the liver parenchyma on T2WI was significantly different between before and 4 min after injecting the contrast medium, while there were no significant differences between before and 4 and 20 min after injection. On T2WI, SNR, and CNR of HCC showed no significant differences at any time. SNR, CNR, and ADC of the liver parenchyma and tumor on DWI also showed no significant differences at any time.

Conclusion:

It is acceptable to perform T2WI and DWI after injection of Gd‐EOB‐DTPA for the diagnosis of HCC. J. Magn. Reson. Imaging 2010;32:229–234. © 2010 Wiley‐Liss, Inc.     

HBV相关肝硬化结节演变的多模态MRI研究

目的:通过与病理结果进行对照分析,总结肝硬化再生结节多步演变的多模态MRI影像特征,探讨肝硬化再生结节的早期诊断及鉴别诊断价值.方法:搜集乙肝肝硬化患者50例(85个结节),回顾性分析其MRI平扫及增强扫描资料,对病理证实的多步演变结果与对应的MRI影像表现进行对照研究.结果:MRI检出82个结节,检出率为96.5％,T2 WI和动态增强扫描是检测再生结节较敏感的序列,检出率分别为93.9％和96.3％,磁敏感成像(SWI)的检出率稍低(69.5％);再生结节(RN)与低级不典型增生结节(LGDN)(x2=8.348,P=0.004)、高级不典型增生结节(HGDN)与肝细胞癌(HCC)(x2=4.612,P=0.032)的MRI诊断符合率差异均有统计学意义.T1WI图像上LGDN的信噪比(SNR)值与RN、HGDN、HCC比较差异均有统计学意义(P值均＜0.05);T2 WI图像上HCC的SNR值与RN、LGDN、HGDN比较差异均有统计学意义(P值均＜0.05).结论:MRI是目前检测肝硬化结节最敏感的无创性检查方法,通过MRI与病理的对照分析,多模态序列从不同角度反映了肝硬化再生结节的影像学特征及演变规律,对肝硬化再生结节的诊断及鉴别诊断具有一定价值.     

Multiparametric MRI for prostate cancer localization in correlation to whole‐mount histopathology

Purpose:

To prospectively evaluate multiparametric magnetic resonance imaging (MRI) for accurate localization of intraprostatic tumor nodules, with whole‐mount histopathology as the gold standard.

Materials and Methods:

Seventy‐five patients with biopsy‐proven, intermediate, and high‐risk prostate cancer underwent preoperative T2‐weighted (T2w), dynamic contrast‐enhanced (DCE) and diffusion‐weighted (DW) MRI at 1.5T. Localization of suspicious lesions was recorded for each of 24 standardized regions of interest on the different MR images and correlated with the pathologic findings. Generalized estimating equations (GEE) were used to estimate the sensitivity, specificity, accuracy, positive, and negative predictive value for every MRI modality, as well as to evaluate the influence of Gleason score and pT‐stage. Tumor volume measurements on histopathological specimens were correlated with those on the different MR modalities (Pearson correlation).

Results:

DW MRI had the highest sensitivity for tumor localization (31.1% vs. 27.4% vs. 44.5% for T2w, DCE, and DW MRI, respectively; P < 0.005), with more aggressive or more advanced tumors being more easily detected with this imaging modality. Significantly higher sensitivity values were obtained for the combination of T2w, DCE, and DW MRI (58.8%) as compared to each modality alone or any combination of two modalities (P < 0.0001). Tumor volume can most accurately be assessed by means of DW MRI (r = 0.75; P < 0.0001).

Conclusion:

Combining T2w, DCE, and DW imaging significantly improves prostate cancer localization. J. Magn. Reson. Imaging 2013;37:1392–1401. © 2012 Wiley Periodicals, Inc.     

Apparent diffusion coefficient and dynamic contrast-enhanced MRI as reliable biomarkers for evaluating response to locoregional therapy in hepatocellular carcinoma patients

Aim of this study

To evaluate the diagnostic utility of DW-MRI with ADC and colored maps, as well as DCE-MRI with subtraction and perfusion color-coded maps for evaluation of the tumor response after LRT in patients with HCC.

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.