Detection of liver metastases: Gadoxetic acid-enhanced three-dimensional MR imaging versus ferucarbotran-enhanced MR imaging

Purpose

To compare the diagnostic performance of gadoxetic acid-enhanced MRI with ferucarbotran-enhanced MRI for the detection of liver metastases.

Materials and methods

Thirty-six patients with 80 liver metastases who underwent gadoxetic acid-enhanced MRI using a three-dimensional volumetric interpolated technique and ferucarbotran-enhanced MRI with a mean interval of 7 days (range, 5-10 days) were included in this study. Two observers independently interpreted the two sets of images - the gadoxetic acid set (unenhanced, early dynamic and 20 min delayed phase images) and the ferucarbotran set (unenhanced and ferucarbotran-enhanced T2*-weighted-gradient echo and T2-weighted turbo spin echo images). Diagnostic accuracy was evaluated using the alternative-free response receiver operator characteristic (ROC) method. Sensitivity and positive predictive value were also evaluated.

Results

There was a trend toward increased areas under the ROC curve (Az values) for the gadoxetic acid set (0.950, 0.948) as compared with the ferucarbotran set (0.941 and 0.939) of images, but no significant difference was found for both observers (p < 0.05). Sensitivities of the gadoxetic acid set (93.8% and 92.5%) were also slightly better than those of the ferucarbotran set (88.8% and 87.5%) with no significant difference (p = 0.13). The two image sets showed similar positive predictive values (98.7% and 98.6%, respectively).

Conclusions

Gadoxetic acid-enhanced MRI showed comparable diagnostic performance to ferucarbotran-enhanced MRI for the detection of liver metastases.     

Detection and characterization of liver metastases: 16--slice multidetector computed tomography versus superparamagnetic iron oxide-enhanced magnetic resonance imaging

The aim of our study was to compare the diagnostic performance of 16--slice multidetector computed tomography with that of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging in the detection of small hepatic metastases and in the differentiation of hepatic metastases from cysts. Twenty-three patients with 55 liver metastases and 14 liver cysts underwent SPIO-enhanced MR imaging and multiphasic CT using 16-MDCT. Two observers independently analyzed each image, in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation as metastases or cysts for MDCT and SPIO-enhanced MR imaging were calculated using receiver operating characteristic analysis. For all observers, the Az values of SPIO-enhanced MR imaging for lesion detection and differentiation of liver metastases from cysts (mean 0.955, 0.999) were higher than those of MDCT (mean 0.925, 0.982), but not statistically significantly so (P>0.05). Sensitivity of SPIO-enhanced MR imaging with regard to the detection of liver metastases (mean 94.5%) was significantly higher than that of MDCT (mean 80.0%) (P<0.05). SPIO-enhanced MR imaging and 16-MDCT showed similar diagnostic accuracies for detection and differentiation of liver metastases from cysts, but sensitivity of SPIO-enhanced imaging in the detection of liver metastases was superior to that of 16-MDCT.     

Detection of hepatocellular carcinoma: comparison of Gd-DTPA- and ferumoxides-enhanced MR imaging

The aim was to compare the diagnostic performance of dynamic Gd-DTPA- and ferumoxides-enhanced MRI for hepatocellular carcinoma (HCC). Twenty-five patients with chronic hepatitis or liver cirrhosis underwent both dynamic gadopentetate- and ferumoxides-enhanced MRI studies of the liver for HCC detection on the same day. MR data of both studies were retrospectively and independently analyzed. Two observers determined in consensus the grade of diffuse fibrotic liver changes (mild, moderate or severe) and the number of focal lesions. HCCs were confirmed by histology (n=22) and/or follow-up studies for at least six months (n=64). Differences in results obtained from both MR data sets were tested for significance with the McNemars test (p<0.05). Ferumoxides-enhanced MR images detected 84 of 99 hepatic lesions, including 82 of 86 HCCs and 2 false positive, nonmalignant lesions, while Gd-DTPA-enhanced MR images detected 92 of 99 hepatic lesions, including 81 of 86 HCCs and 11 false positive, nonmalignant lesions. Sensitivity of MRI for detection of HCCs was not significantly different between ferumoxides-enhanced (95.3%; p>0.05) and Gd-DTPA-enhanced scans (94.2%). Gd-DTPA- and ferumoxides-enhanced MRI perform equally well for HCC detection. The majority of small hypervascular hepatic lesions, detected on dynamic Gd-DTPA-enhanced MRI but not on ferumoxides-enhanced MRI, represent no HCCs.     

Detection of hepatocellular carcinoma: comparison of ferumoxides-enhanced and gadolinium-enhanced dynamic three-dimensional volume interpolated breath-hold MR imaging

The purpose was to compare the diagnostic accuracy of ferumoxides-enhanced MR imaging and gadolinium-enhanced dynamic MR imaging using three-dimensional (3D) volume interpolated breath-hold examination (VIBE) for the detection of hepatocellular carcinoma (HCC). Forty-nine patients with 61 HCCs, who underwent ferumoxides-enhanced and gadolinium-enhanced dynamic MR imaging, were included prospectively in this study. Ferumoxides-enhanced MR imaging was performed 24 h after completion of the dynamic study using 3D-VIBE. Three radiologists independently interpreted the images. The diagnostic accuracy was evaluated using the receiver-operating characteristic method, and the sensitivity of each imaging technique was compared using McNemars test. The mean diagnostic accuracy of dynamic MR imaging (Az=0.95) was higher than that of ferumoxides-enhanced MR imaging (Az=0.90), but failed to reach a statistical significance (P=0.057). The mean sensitivity of dynamic MR imaging (90.7%) was significantly superior to that of ferumoxides-enhanced MR imaging (80.9%, P=0.03). Furthermore, for lesions smaller than 15 mm, the mean sensitivity of dynamic MR imaging was significantly higher than that of ferumoxides-enhanced MR imaging (85.2% vs. 69.2%, P<0.05). Dynamic MR imaging showed a trend toward better diagnostic accuracy for than ferumoxides-enhanced MR imaging for the detection of HCCs.     

大鼠种植型肝癌的超顺磁性的氧化铁磁共振增强实验研究

目的 研究正常大鼠的超顺磁性氧化铁（ＳＰＩＯ）剂量梯度－肝脏信号曲线、大鼠种植地癌ＳＰＩＯ增强前后的对比噪声比和检出率。方法 第１组：７２只正常ＳＤ大鼠随机分成１８个样本组,平扫后以０、２、５……２８０ｕｍｏｌＦｅ／ｋｇ１８个ＳＰＩＯ剂量分别做增强扫描,做剂量梯度－肝脏信号曲线。第２组：３８只种植型肝癌模型鼠,共计生成４３个肿瘤,行平扫及ＳＰＩＯ增强扫描,分析肿瘤磁共振强化特点;测量增强前后Ｔ１及     

Detection of liver metastases using gadoxetic-enhanced dynamic and 10- and 20-minute delayed phase MR imaging

Purpose:

To assess the incremental value of hepatobiliary phase images in gadoxetate disodium‐enhanced magnetic resonance imaging (MRI), and to compare diagnostic accuracy and lesion conspicuity on 10‐ and 20‐minute delayed images for preoperative detection of hepatic metastases with subgroup analysis according to size and history of chemotherapy.

Materials and Methods:

Forty‐six patients with 107 metastases who underwent surgery after gadoxetate disodium‐enhanced MRI were evaluated. Four observers independently interpreted three sets: dynamic set comprising precontrast T1‐, T2‐weighted, and dynamic images; 10‐minute set comprising dynamic set and 10‐minute delayed; 20‐minute set comprising 10‐minute set and 20‐minute delayed. Diagnostic accuracy was compared with subgroup analysis. Liver‐to‐lesion signal ratio (SR) was calculated using the region of interest method and compared.

Results:

Mean A_z and sensitivities were significantly higher for 10‐ (A_z = 0.894, sensitivity = 95.6%) and 20‐minute (0.910, 97.2%) than dynamic set (0.813, 79.9%) (P < 0.001), with no significant difference between 10‐ and 20‐minute sets (P = 0.140). In patients with small (≤1 cm) metastases and a history of chemotherapy, sensitivities were significantly higher with 10‐ (88.2%) and 20‐minute (91.6%) sets than dynamic set (48.6%) (P < 0.001). SR was significantly higher for 10‐ and 20‐minute delayed than precontrast and dynamic, with significantly higher SR on 20‐ than 10‐minute delayed.

Conclusion:

Regardless of size or prior chemotherapy, detection of hepatic metastases was significantly improved by adding hepatobiliary phase images without significant differences between 10‐ and 20‐minute delayed. J. Magn. Reson. Imaging 2012;35:635‐643. © 2011 Wiley Periodicals, Inc.     

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented.     

Preoperative detection of hepatocellular carcinoma: comparison of combined contrast-enhanced MR imaging and combined CT during arterial portography and CT hepatic arteriography

The aim of this study was to compare Gd-DTPA-enhanced dynamic MR images, superparamagnetic iron oxide (SPIO)-enhanced MR images, combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images, vs combined CT arterial portography (CTAP) and CT hepatic arteriography (CTHA), in the detection of hepatocellular carcinoma (HCC) using receiver operating characteristic (ROC) analysis. Twenty-four patients with 38 nodular HCCs (5–60 mm, mean 23.0 mm) were retrospectively analyzed. Image reviews were conducted on a liver segment-by-segment basis. A total of 192 segments, including 36 segments with 38 HCC, were reviewed independently by three radiologists. Each radiologist read four sets of images (set 1, unenhanced and Gd-DTPA-enhanced dynamic MR images; set 2, unenhanced and SPIO-enhanced MR images; set 3, combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images; set 4, combined CTAP and CTHA). To minimize any possible learning bias, the reviewing order was randomized and the reviewing procedure was performed in four sessions at 2-week intervals. The diagnostic accuracy (A_z values) for HCCs of combined CTAP and CTHA, combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images, Gd-DTPA-enhanced dynamic MR images, and SPIO-enhanced MR images for all observers were 0.934, 0.963, 0.878, and 0.869, respectively. The diagnostic accuracy of combined CTAP and CTHA and combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images was significantly higher than Gd-DTPA-enhanced dynamic MR images or SPIO-enhanced MR images (p<0.005). The mean specificity of combined CTAP and CTHA (93%) and combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images (95%) was significantly higher than Gd-DTPA-enhanced dynamic MR images (87%) or SPIO-enhanced MR images (88%; p<0.05). Combined Gd-DTPA-enhanced dynamic and SPIO-enhanced MR images may obviate the need for more invasive combined CTAP and CTHA for the preoperative evaluation of patients with HCC.     

Added diagnostic value of T2-weighted MR imaging to gadolinium-enhanced three-dimensional dynamic MR imaging for the detection of small hepatocellular carcinomas

Purpose

To assess the added value of T2-weighted MRI to gadolinium-enhanced dynamic MRI for detection of HCCs.

Materials and methods

Two readers retrospectively analyzed MRIs of 115 patients with 131 HCCs (size; 0.6–2.0 cm) that had been diagnosed by histology (n = 41) or imaging findings (n = 90). Two separate blind image analyses of the gadolinium set and the combined T2-weighted imaging and gadolinium sets were performed. Diagnostic accuracy was evaluated using the alternative-free response receiver operating characteristic method with four-point scale. Sensitivity and positive predictive value were also calculated.

Results

For both observers, the Az values and sensitivities with the combined T2-weighed imaging and gadolinium set (mean Az 0.806, sensitivity 84.7) were significantly higher than those with the gadolinium set (mean Az 0.660, sensitivity 59.9) (p < 0.05). The addition of T2-weighted imaging led to a change in diagnosis for 27 lesions by both observers, which at gadolinium set were assigned a confidence level of 1 or 2 but at additional reading of T2-weighted imaging were assigned a confidence level of 3 or 4. For the positive predictive values, each image set showed a similar value for each observer.

Conclusion

The addition of T2-weighted imaging to gadolinium-enhanced 3D dynamic imaging could be helpful in the detection of HCC by increasing reader confidence for HCCs with equivocal findings on gadolinium-enhanced MRIs.     

Detection of liver metastases: comparison of gadobenate dimeglumine-enhanced and ferumoxides-enhanced MR imaging examinations

PURPOSE: To compare gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance (MR) imaging with ferumoxides-enhanced MR imaging for detection of liver metastases. MATERIALS AND METHODS: Twenty consecutive patients known to have malignancy and suspected of having focal liver lesions at ultrasonography (US) underwent 1.0-T MR imaging with gradient-recalled-echo T1-weighted breath-hold sequences before, immediately after, and 60 minutes after Gd-BOPTA injection. Subsequently, MR imaging was performed with turbo spin-echo short inversion time inversion-recovery T2-weighted sequences before and 60 minutes after ferumoxides administration. All patients subsequently underwent intraoperative US within 15 days, and histopathologic analysis of their resected lesion-containing specimens was performed. Separate qualitative analyses were performed to assess lesion detection with each contrast agent. Quantitative analyses were performed by measuring signal-to-noise and contrast-to-noise ratios (CNRs) on pre- and postcontrast Gd-BOPTA and ferumoxides MR images. Statistical analyses were performed with Wilcoxon signed rank and Monte Carlo tests. RESULTS: Sensitivity of ferumoxides-enhanced MR imaging was superior to that of Gd-BOPTA-enhanced MR imaging for liver metastasis detection (P <.05). Ferumoxides MR images depicted 36 (97%) of 37 metastases detected at intraoperative US, whereas Gd-BOPTA MR images depicted 30 (81%) metastases during delayed phase and 20 (54%) during dynamic phase. All six metastases identified only at ferumoxides-enhanced MR imaging were 5-10 mm in diameter. There was a significant increase in CNR between the lesion and liver before and after ferumoxides administration (from 3.8 to 6.8, P <.001) but not before or after Gd-BOPTA injection (from -4.8 to -5.5, P >.05). CONCLUSION: Ferumoxides-enhanced MR imaging seems to be superior to Gd-BOPTA-enhanced MR imaging for liver metastasis detection. Copyright RSNA, 2002     

Detection of hypervascular malignant foci in borderline lesions of hepatocellular carcinoma: comparison of dynamic multi-detector row CT, dynamic MR imaging and superparamagnetic iron oxide-enhanced MR imaging

The study object was to retrospectively compare the detection rate of hypervascular foci visualized by CT during hepatic arteriography (CTHA) in borderline nodules, which was observed upon cirrhotic livers, on dynamic MDCT, dynamic gadolinium-enhanced MR (dynamic MR), and SPIO-enhanced MR imaging. Eighty-five nodules in 49 patients with cirrhosis were evaluated. When a part of the nodule showed hyperdensity relative to the surrounding areas of the nodule on CTHA, it was defined as "hypervascular focus." The relationships between the dynamic MDCT and dynamic MR and SPIO-enhanced MR imaging findings of these foci were analyzed using X(2) test. Hypervascular foci were detected in 17 (53%) of 32 on the arterial dominant phase of dynamic MDCT, in 19 (37%) of 51 on the arterial dominant phase of dynamic MR and in 6 (26%) of 23 on SPIO-enhanced MR imaging. Arterial dominant phase of dynamic MDCT demonstrated a significantly higher detection rate of hypervascular foci less than 5 mm in diameter than did dynamic and SPIO MR imaging (p<0.05). Hypervascular foci in borderline nodules could be better visualized by dynamic MDCT than by gadolinium- and SPIO-enhanced MR imaging. Dynamic MDCT is recommended for the follow-up examination of hypovascular borderline lesions.     

Comparison of superparamagnetic iron oxide-enhanced and gadobenate dimeglumine-enhanced dynamic MRI for detection of small hepatocellular carcinomas

OBJECTIVE: The purpose of this study was to compare superparamagnetic iron oxide (SPIO)-enhanced MRI with gadobenate dimeglumine-enhanced MRI for the detection of hepatocellular carcinoma using receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: Twenty-nine consecutive patients with 35 hepatocellular carcinomas underwent gadobenate dimeglumine-enhanced MRI (unenhanced, arterial, portal, and equilibrium phases) using 3D fat-saturated volumetric interpolated imaging and SPIO-enhanced MRI on a 1.5-T unit. SPIO-enhanced T2-weighted turbo spin-echo and T2*-weighted gradient-echo sequences were performed 48 hr after completion of the dynamic study. Three observers independently interpreted the images in random order, separately, and without patient identifiers. Diagnostic accuracy was evaluated using the alternative free response receiver operating characteristic method. Sensitivity and positive predictive value were also evaluated. RESULTS: The mean sensitivity and positive predictive value of SPIO-enhanced imaging were 81.0% and 85.0%, respectively, and those of gadobenate dimeglumine-enhanced MRI were 91.4% and 88.1%, respectively. A significant difference was seen in the sensitivity of the two MRI examinations (p < 0.05). The mean value of the area under the ROC curve (A(z)) for gadobenate dimeglumine-enhanced imaging (A(z) = 0.97 +/- 0.01) was significantly higher than that for SPIO-enhanced imaging (A(z) = 0.90 +/- 0.02) (p = 0.004). CONCLUSION: Gadobenate dimeglumine-enhanced 3D dynamic imaging showed better diagnostic performance than SPIO-enhanced imaging for the detection of hepatocellular carcinomas.     

Gadobenate dimeglumine-enhanced liver MR imaging: value of dynamic and delayed imaging for the characterization and detection of focal liver lesions

The aim of this study was to determine the value of delayed-phase imaging (DPI) of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging for the evaluation of focal hepatic tumors compared with precontrast imaging and early dynamic phase imaging. The MR images were obtained in 48 patients with 98 focal hepatic tumors. Three-dimensional gradient-echo (GRE) imaging obtained before and 30, 60, and 1 h after administration of 0.1 mmol/kg of gadobenate dimeglumine. Each image set was analyzed qualitatively (lesion detection, conspicuity, delineation, and enhancement pattern on DPI) and quantitatively [signal-to-noise ratio (SNR), tumor–liver contrast-to-noise ratio (CNR)]. Improved lesion-to-liver contrast during the dynamic phase imaging was observed compared with precontrast images. The DPI showed a homogeneous enhancement of liver parenchyma and distinctive enhancement features of focal liver lesions: metastases (85%) showed a target shaped enhancement, and hepatocellular carcinomas (HCCs) showed an inhomogeneous (58%) or homogeneous enhancement (21%). The DPI showed better performance for the detection of metastases than other images by increasing lesion delineation (p<0.05). The absolute CNR of metastasis measured from periphery of the tumors on DPI was greater than precontrast and arterial phase imaging (p<0.05). The Gd-BOPTA during both dynamic and delayed phases provides valuable information for the characterization of focal liver lesions, and furthermore, Gd-BOPTA-enhanced DPI contributed to the improved detection of liver metastasis compared to precontrast and early dynamic imaging.     

对比剂铁羧葡胺在正常兔MR脑灌注的初步实验研究

目的 探讨铁羧葡胺(Resovist)应用于脑MR灌注加权成像(PWI)的可行性、给药方法以及最佳剂量.方法 健康新西兰大白兔30只,随机数字法平均分为A、B、C、D、E组.其中A、B、C、D 4组分别给予4、8、16、32 μmol Fe/kg;E组设为对照,给予0.2 mmol/kg的钆喷替酸葡甲胺(Gd-DTPA).所有动物均行MR PWI,获得相应信号强度一时间曲线图,并分别计算脑灰质、白质的最大信号下降百分比(SRRmax)、局部脑血容量(rCBV)和灰质与白质rCBV之比(QRCBV)、SRRmax之比(QRR max).所得数据,根据资料性质,行配对t检验和单因素方差分析.结果 Resovist能快速团注,4组均获得满意的信号强度一时间曲线图;4种剂量的Resovist对实验兔脑灰质和白质均有良好的分辨率.A、B、C、D、E 5组脑灰质和白质的rCBV分别为(50.48±3.84)、(25.57±2.10),(94.69±2.60)、(45.33±3.14),(141.13±6.26)、(67.67±4.65),(243.75±5.90)、(162.06±5.14),(84.60±3.60)、(41.36±2.18)ml/100 g;灰质和白质的SRRmax分别为:(13.70±1.50)%、(7.38±0.41)%,(31.01±4.06)%、(16.49±2.35)%,(43.81±3.42)%、(21.64±4.14)%,(64.49±5.35)%、(43.61±5.78)%,(27.78±2.98)%、(14.42±2.25)%;各组脑灰质与白质检测数据比较差异均有统计学意义(P值均<0.01).A、B、C、D、E 5组QrCBV分别为1.98±0.07、2.09±0.11、2.09±0.07、1.50±0.01、2.05±0.03;QSRRmax分别为:1.85±0.11、1.88±0.06、2.06±0.25、1.49±0.09、1.94±0.12;5组间差异均有统计学意义(QrCBV的F值为85.076,QSRR max的F值为13.915,P均<0.01).A、B、C 3组QrCBV值和QSRR max值差异无统计学意义(P>0.05);而D组QrCBV值和QSRR max值显著低于A组(P<0.01).结论 Resovist应用于MR脑灌注是可行的,适宜剂量4～16 μmol Fe/kg.     

脑转移瘤动态增强磁化率MR灌注成像特点的研究

目的研究治疗前不同来源脑转移瘤的动态增强磁化率(DSC)MR 灌注成像特点。方法对28例经病理或随访证实为脑转移瘤的患者行手术前 DSC MR 灌注成像扫描。分析 MR 灌注曲线及伪彩图像,测量肿瘤实质部分及瘤周水肿区最大相对脑血容积(rCBV)值及相应部位相对平均通过时间(rMTT)数值,并将所测量数值进行 t 检验分析,P<0.05为差异具有统计意义。结果不同来源脑转移瘤的 MR 灌注曲线、伪彩图像特点无明显差异。脑转移瘤肿瘤实质部分灌注程度与正常脑灰质相仿,瘤周水肿区表现为低灌注,两者的灌注时间均延长。12例来源于肺癌与5例来源于乳腺癌的脑转移瘤肿瘤实质部分的最大 rCBV 值(分别为272.5±34.3和210.8±59.4)及相应部位的 rMTT 数值(分别为117.7±4.3和105.2±21.3)之间以及两者瘤周水肿区 rCBV 值(分别为122.0±16.3和68.4±6.1)和 rMTT 值(分别为112.7±8.3和139.8±37.9)之间差异均无统计学意义(P>0.05)。结论不同来源脑转移瘤的 MR 灌注成像特点趋于一致。     

Diagnosis of colorectal hepatic metastases: Contrast-enhanced ultrasonography versus contrast-enhanced computed tomography versus superparamagnetic iron oxide-enhanced magnetic resonance imaging with diffusion-weighted imaging

Purpose:

To create a reliable rat model with small renal cortical scars and evaluate the accuracy and sensitivity of dynamic contrast‐enhanced MRI in detecting the kinds of lesions that are associated with reflux nephropathy.

Materials and Methods:

In 16 rats, three unilateral renal cortical lesions were created using either electrocautery or pure alcohol with the contralateral kidney serving as control. MRI on a 1.5 Tesla GE Signa was performed 10–14 days after surgery. After bolus injection of 0.2 mM/Kg Gd‐DTPA, sequential MRI acquisitions were performed using a 4‐inch quadrature birdcage coil. Renal and scar volumes and pathology were compared after scanning and killing.

Results:

Of the 48 points of injury, 40 (83%) in the 16 rats were detected grossly. Under microscopy, 36 injuries (75%) were detected on mid‐kidney cross‐sections. The average lesion was 4.2 mm³ corresponding to 0.5% of the kidney volume. Using pathological findings as the gold standard, the sensitivity and specificity of scar detection using MRI was 69% and 93%, respectively.

Conclusion:

A rat model was created to demonstrate the sensitivity of dynamic contrast‐enhanced MRI for detecting renal scars. Alcohol and electrocautery created reliable renal scars that were confirmed pathologically. MRI detected these lesions that averaged 4.2 mm³ (0.5% total renal volume) with sensitivity and specificity of 69% and 93%, respectively. J. Magn. Reson. Imaging 2010;31:1132–1136. © 2010 Wiley‐Liss, Inc.     

Contrast agents for MR imaging of the liver: a clinical overview

Different contrast agents have been clinically used in MR imaging of the liver including extracellular gadolinium chelates, contrast agents targeted to the macrophage-monocytic phagocytic system (MMPS), hepatobiliary contrast agents, and blood-pool contrast agents. Extracellular gadolinium chelates are optimally used for characterization of focal hepatic lesions, whereas hepatobiliary and MMPS-targeted contrast agents are optimally used for detection and preoperative evaluation. The present review portrays these contrast agents and discusses their advantages and shortcomings. Received 14 June 1996; Revision received 14 August 1996; Accepted 16 August 1996     

常规SE序列和动态增强MRI诊断肝局灶性病变的比较

目的比较常规SE序列与动态Gd-U．----x增强扫描对肝局灶病变的诊断价值。方法对34例肝局灶病变做了常规SE平扫和动态Gd-U．---A增强及延迟万WI增强扫描；就各序列对肝局灶病变的检出率、病变的信噪比（C／N）值和图像质展进行定员和定性分析。结果36例共142个病灶，动态Gd-lyl？l？A检出率（138／142，958％）明st高于IFZWI和延迟TW［增强（128／14，叨％；119／142，838％）（P＜005）：动态Gd-IJ：1713A增强的C／N值高于TZWI和TIWI延迟增强（P＜0．05）；动态增强的伪影较L们少（P＜0．01），而病灶清晰度各序列之间无明显差别（P＞0．历）。结论动态u-ly：1717A增强扫描在病灶检出率、图像质显反C／N值方面均优于IWI，对肝局灶病变的诊断是一种有价值的方法，