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

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

Gd-EOB-DTPA enhancement pattern of hepatocellular carcinomas in rats: Comparison with Tc-99m-IDA uptake

The enhancement pattern of chemically induced hepatocellular carcinomas (HCCs) after intravenous administration of the hepatobiliary magnetic resonance (MR) contrast agent gadolinium-EOB-DTPA (ethoxybenzyl-diethylenetriaminepentaacetic acid) was compared with the uptake pattern of technetium-99m-labeled iminodiacetic acid (IDA), a hepatobiliary radioactive tracer. The hepatocyte uptake of both the contrast agent and the scintigraphic agent has been shown to be driven by the organic anion transporter. The tumors enhanced less than the liver after Gd-EOB-DTPA administration, whereas the Tc-99m-IDA uptake of differentiated HCCs exceeded that of the liver at 30 minutes and 3 hours after administration. The enhancement pattern of a differentiated HCC with Gd-EOB-DTPA does not mirror that seen with Tc-99m-IDA.     

Experimental hepatic dysfunction: Evaluation by MRI with Gd-EOB-DTPA

To investigate the potential of gadolinium (Gd)-ethoxybenzyl (EOB)-diethylenetriamine-pentaacetic acid (DTPA) for evaluating liver function, chemically induced hepatitis animal models were studied. The rats in group 1 underwent intraperitoneal administration of 2.0 ml/kg and those in group 2 underwent intraperitoneal administration of .5 ml/kg of 50% (V/V) carbon tetrachloride (CCl₄) solution. The rats in group 3 served as controls. For rats of each group, the signal intensity of the liver was measured on T1-weighted spin-echo MR images acquired before and until 60 minutes after an intravenous injection of Gd-EOB-DTPA. The remaining rats in each group underwent indocyanine green test, serologic examination, or measurement of prothrombin time. Liver enhancement was compared with results of the other examinations. The degree of liver enhancement with Gd-EOB-DTPA was decreased and the washout of contrast was prolonged in the CCl₄-administered groups. In this animal model, both hepatic dysfunction and liver enhancement were dose-dependent. MRI with Gd-EOB-DTPA has the potential to evaluate hepatic function.     

Spin-echo and dynamic gadoliniumenhanced flash MR imaging of hepatocellular carcinoma: Correlation with histopathologic findings

Evaluation of histologic subtype and degree of differentiation in hepatocellular carcinoma (HCC) is essential because it affects patient prognosis and treatment planning. To evaluate the histologic subtype of HCC with magnetic resonance (MR) imaging, conventional spin-echo and dynamic studies were correlated with histopathologic and angiographic findings in 72 HCCs. Dynamic MR imaging was performed with the fast low-angle shot (FLASH) technique after administration of gadopentetate dimeglumine. There was considerable overlap in signal intensity between various tumor grades on both T1- and T2-weighted images. On dynamic MR images, the peak contrast enhancement ratio correlated with tumor grade (well-differentiated, 29.5 ± 24.7; moderately differentiated, 63.5 ± 24.1; poorly differentiated, 86.9 ± 26.4) or degree of dilatation of the sinusoidlike vascular space between tumor cells. The maximum contrast-to-noise ratio in tumor (relative to surrounding liver) was achieved within 60 seconds in 45 HCCs (mostly of the trabecular or pseudoglandular type). Enhancement was slight or minimal in 17 tumors (mostly small, well-differentiated tumors). In 10 tumors, the degree of enhancement increased with time, with maximum enhancement in the delayed phase (most frequently in scirrhous HCC). These dynamic patterns correlated with angiographic findings. These data indicate that the degree and pattern of enhancement on dynamic MR images reflect tumor differentiation and architecture of HCC.     

Mangafodipir trisodium‐enhanced MRI for the detection and characterization of focal hepatic lesions: Is delayed imaging useful?

PURPOSE: To investigate the usefulness of early and delayed hepatic MRI after mangafodipir trisodium (Mn-DPDP) administration for the detection and characterization of focal hepatic lesions. MATERIALS AND METHODS: Forty-five patients (31 males and 14 females, mean age = 61 years) with a total of 113 hepatic lesions (mean size = 3.5 cm) were included in this study (15 with hepatocellular carcinoma (HCC, N = 35), 20 with hepatic metastasis (N = 63), five with hemangioma (N = 10), three with cholangiocarcinoma (CC, N = 3), and two with liver abscess (N = 2)). T1-weighted gradient-echo MR images were obtained before and after Mn-DPDP administration, with a mean 18-hour delayed imaging. A qualitative analysis (including the size and signal intensity (SI)) and quantitative analysis (including enhancement and lesion-liver contrast-to-noise ratio (CNR)) were performed on pre- and postcontrast early and delayed MR images. RESULTS: Compared to postcontrast early imaging, 17 (48.6%) of 35 HCCs showed higher SI, 16 (45.7%) showed no SI change, and two (5.7%) showed lower SI on delayed imaging. All 63 metastases, 10 hemangiomas, three CCs, and two abscesses showed no SI change. On delayed imaging, ring enhancement was noted in 53 metastases (84.1%), three hemangiomas (30.0%), and one abscess (50.0%), but was not seen in HCCs or CCs. Eight metastases (12.7%) also showed ring enhancement on postcontrast early imaging. No newly detected hepatic lesions were revealed on postcontrast delayed MR images compared to postcontrast early images. Regarding CNR, the HCCs showed a significant increase in CNR from postcontrast early to delayed images after administration of Mn-DPDP (P < 0.01). However, none of the metastases, hemangiomas, CCs, and abscesses showed a significant increase of CNR from postcontrast early to delayed images. CONCLUSION: Postcontrast delayed MR images after Mn-DPDP administration were helpful in distinguishing hepatocellular from nonhepatocellular lesions, but were not useful for lesion detection and had limited utility for lesion characterization, since benign and malignant hepatic lesions looked the same.     

Potential for differential diagnosis with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging in experimental hepatic tumors

RATIONALE AND OBJECTIVES: To investigate whether dynamic and delayed magnetic resonance imaging (MRI) with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), a hepatobiliary MRI contrast agent, has potential for the differential diagnosis of experimental hepatic tumors. METHODS: Twelve male rats received N-nitrosomorpholine solution as drinking water to induce hepatic tumors. After injection of Gd-EOB-DTPA, rats were subjected to dynamic and delayed MRI. The relative enhancement (RE) was calculated, and the time of the maximum RE (Tmax) was evaluated. After MRI, liver was histologically analyzed. RESULTS: One hundred sixty-three hepatic tumors 3-12 mm in diameter were induced after 18 weeks of treatment with 0.01 wt/vol% of N-nitrosomorpholine, and 81 of them were evaluated. The RE in hyperplastic nodules (HPNs) was significantly higher than that in moderately or poorly differentiated hepatocellular carcinomas (HCCs) in the late phase, whereas there was no significant difference in RE between well-differentiated HCCs and HPNs. The average Tmax in HPNs was about 13 minutes, whereas that of each differentiated HCCs was about 1 minute. CONCLUSIONS: It was possible to differentiate benign HPNs and malignant HCCs (especially well-differentiated HCCs) by evaluating the change of RE or comparison of Tmax with Gd-EOB-DTPA-enhanced MRI.     

肝脏MR动态增强扫描：Gd-EOB-DTPA与Gd-DTPA的个体内对照研究

目的：比较钆塞酸二钠（Gd-EOB-DTPA）及钆喷酸葡胺（Gd-DTPA）肝脏 MR动态增强扫描腹腔脏器及血管的强化特点,重点比较Gd-EOB-DTPA移行期与Gd-DTPA平衡期的图像特点。方法：本研究为前瞻性、个体内随机对照研究。25例病理证实为原发直肠癌或结肠癌、怀疑肝转移的患者,3天内行2次肝脏 MR 动态增强检查,分别使用 Gd-EOB-DTPA及Gd-DTPA两种对比剂。动态增强扫描的序列相同,包括平扫、动脉期、门静脉期、平衡期（Gd-DTPA）／移行期（Gd-EOB-DTPA）。图像客观评估中,测量各期相图像上血管及肝脾实质的信号强度。以椎旁肌肉的信号为参考,计算相对信号强度（RS）并比较两组间的差异,以及不同期相时肝实质RS的差异。主观评估：读片者主观评价增强扫描各期相图像上,主动脉、门静脉及肝静脉与肝实质的相对信号强度。结果：肝实质的RS：在动脉期Gd-DTPA 组明显高于Gd-EOB-DTPA组（t＝3．006,P＝0．005）;在门静脉期及平衡期／移行期,两组检查的差异无统计学意义（t＝1．788,P＝0．086;t＝0．781,P＝0．442）。Gd-EOB-DTPA检查时,门静脉期肝实质RS明显高于动脉期（t＝－3．014,P＝0．006）,移行期RS与门静脉期的差异无统计学意义。Gd-DTPA检查时,平衡期肝实质RS明显低于门静脉期（t＝5．827,P＝0．000）。主观评估：Gd-DTPA增强扫描平衡期图像上所有患者的主动脉、门静脉、肝静脉均为高信号（100％）;Gd-EOB-DTPA 增强扫描移行期图像上主动脉、门静脉、肝静脉均以低或等信号为主（84％,92％,92％）。结论：Gd-EOB-DTPA动态增强 MR 检查,肝脏实质在门静脉期及移行期呈持续强化,其移行期的图像特征与Gd-DTPA平衡期的图像特征有明显不同,在影像诊断时应予以关注。     

Contrast-enhanced MR imaging of diffuse and focal splenic disease with use of magnetic starch microspheres

The diagnostic value of magnetic starch microspheres (MSM), a new superparamagnetic contrast agent, was studied in experimental models of diffuse and focal splenic disease in rats by means of ex vivo relaxometry and in vivo magnetic resonance (MR) imaging. Owing to small differences in unenhanced T1 and T2 values between diffuse lymphoma and normal spleen, MR imaging failed to distinguish tumor-bearing animals from control animals by signal-to-noise ratios (SNRs) obtained with T1- and T2-weighted spin-echo sequences. One hour after injection of 20 μmol/kg MSM, lymphomatous spleen showed significantly (P <.001) reduced enhancement relative to normal splenic tissue. As a result, animals with diffuse lymphoma (SNR: 10.3 ± 1.7) could be easily differentiated from control animals (SNR: 5.5 ± 0.6) on T2-weighted (TR msec/TE msec = 2,000/45) images. In focal splenic disease, MSM produced normal enhancement of nontumorous splenic tissue, whereas relaxation times of tumors were not different before and after contrast agent injection. On T2-weighted images (2,000/45), the tumor-spleen contrast-to-noise ratio increased from (4.8 ± 1.6 to 21.8 ± 1.9 +354%), improving conspicuity of splenic tumors. The results show that MSM-enhanced MR imaging improves the detection of diffuse and focal splenic disease.     

Dynamic MR imaging of liver metastases with Gd-EOB-DTPA

Purpose: To assess liver and lesion enhancements by dynamic MR imaging after bolus injection of the hepatobiliary contrast agent gadolinium ethoxybenzyldiethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) in patients with liver metastases and to compare the effect of different doses.Material and Methods: A randomized double-blinded trial with doses of 12.5, 25 and 50 μmol/kg Gd-EOB-DTPA was performed in 35 patients with liver metastases. Liver enhancement, tumor enhancement and liver lesion contrast-to-noise (C/N) ratios were calculated from breath-hold gradient echo images (100/5/80°) recorded precontrast and at different times up to 10 min postcontrast.Results: Normal liver showed a characteristic enhancement pattern, with a rapid enhancement in the first 45 s postcontrast and a slight but significant further increase up to 600 s. The initial enhancement in the lesions was also pronounced, but the enhancement was slightly decreased after 240 s postcontrast. At dose levels of 12.5 and 25 μmol/kg Gd-EOB-DTPA, C/N ratios significantly increased compared to baseline from 90 to 600 s. Postcontrast C/N-values obtained using 50 μmol/kg Gd-EOB-DTPA were not significantly increased, except for the examinations 480 s postcontrast.Conclusion: In liver metastases, C/N ratios obtained with doses of 12.5 and 25 μmol/kg Gd-EOB-DTPA were slightly superior to 50 μmol/kg Gd-EOB-DTPA. This finding is probably due to a more pronounced extracellular effect of the contrast medium at higher doses.     

Gd-EOB-DTPA enhanced MRI for hepatocellular carcinoma: quantitative evaluation of tumor enhancement in hepatobiliary phase.

OBJECTIVE: The purpose of this study was to evaluate the utility of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the quantitative evaluation of hepatocellular carcinoma (HCC) and dysplastic nodules in the hepatobiliary phase. MATERIAL AND METHODS: The subjects comprised 12 patients with 27 lesions (22 HCCs and 5 dysplastic nodules). Chemical-shift-selective fat-suppressed T1-weighted sequences were obtained before and 10, 20, and 40 min after the injection of Gd-EOB-DTPA. Quantitative analyses were performed with the enhancement ratio of the lesion and the contrast-to-noise (C/N) ratio. RESULTS: The enhancement ratios of the HCCs were 44.0+/-36.5, 44.7+/-46.8, and 47.7+/-52.8 (%) at 10, 20, and 40 min, respectively, after the injection of Gd-EOB-DTPA. The enhancement ratios of the dysplastic nodules were 36.2+/-34.3, 44.3+/-37.3, and 40.1+/-46.8 (%). The C/N ratios of the HCCs were 0.2+/-6.6 for the precontrast image, and -9.2+/-12.6, -9.9+/-14.8, and -12.7+/-15.7 at 10, 20, and 40 min, respectively, after the injection of Gd-EOB-DTPA. The C/N ratios of the dysplastic nodules were 1.4+/-8.0, -13.7+/-11.1, -13.3+/-7.6, and -13.1+/-10.4. No significant differences were found between the HCCs and the dysplastic nodules in the enhancement ratio and the C/N ratio. Only two HCCs showed a positive C/N ratio value, and these HCCs were pathologically confirmed to be a well differentiated and a moderately differentiated carcinoma, respectively. CONCLUSION: HCCs and some of the dysplastic nodules showed hypointensity in the hepatobiliary phase in Gd-EOB-DTPA-enhanced MRI. No specific enhancement was observed, regardless of tumor differentiation.     

Comparison of three different injection methods for arterial phase of Gd-EOB-DTPA enhanced MR imaging of the liver

Objective

To compare three different injection methods for optimizing hepatic arterial phase of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) enhanced MR imaging.

Methods

Arterial phase images were obtained after the injection of contrast agent at a rate of 3 mL/s with diluted Gd-EOB-DTPA (dilution method) in 27 patients, 3 mL/s with undiluted Gd-EOB-DTPA (3 mL method) in 26 patients and 1 mL/s with undiluted Gd-EOB-DTPA (1 mL method) in 28 patients. In the quantitative evaluation, signal-to-phantom ratios (SPR) of the liver parenchyma, pancreas, renal cortex, portal vein and aorta were evaluated. In the qualitative evaluation, the seven items for image quality of hepatic arterial phase were assessed, and the total score of all items in each subject was calculated.

Results

The score of enhancement of abdominal aorta and total score of seven items in 1 mL method were significantly higher than those in 3 mL method. The SPR of the liver parenchyma in 3 mL method was significantly higher than that in 1 mL method, suggesting substantial hepatic inflow from portal venous return.

Conclusion

For the optimal arterial phase imaging, injection rate of 1 mL/s with undiluted Gd-EOB-DTPA is convenient and preferable, compared with other two methods, based on our qualitative analysis.     

Enhanced tumor detection in the presence of fatty liver disease: Cell-specific contrast agents

It is assumed that hepatobiliary, cell-specific contrast agents will be adversely affected by the presence of diffuse liver disease. The diagnostic efficacy for tumor detection in the presence of fatty liver disease was experimentally studied at contrast-enhanced magnetic resonance (MR) imaging with manganese-DPDP (N,N′-dipyridoxylethylenediamine-N,N′-diacetate 5,5′-bis[phosphate]) and gadobenate dimeglumine (Gd-BOPTA/dimeg) and compared with conventional and chemical shift imaging. Carcinosarcoma was implanted into the liver of rats, and fatty liver was induced with L-ethionine. Without contrast agents, the tumor-fatty liver contrast-to-noise ratio (C/N) was increased on T1-weighted and decreased on T2-weighted MR images relative to tumor-bearing control rats without fatty liver. Chemical shift imaging (phase-contrast method) increased the tumor—fatty liver C/N from 2.3 ± 1.0 to 6.1 ± 1.7 (P <.001). Mn-DPDP and Gd-BOPTA/dimeg increased the tumor—fatty liver C/N from -5.4 ± 1.6 to -11.0 ± 1.9 and ?9.8 ± 3.4, respectively (P <.001). The hepatobiliary, cell-specific contrast agents were equally effective in both fatty and nonfatty liver and outperformed both chemical shift and conventional MR imaging in detecting liver tumors.     

Detection and characterization of primary liver cancer in rats by MS-264-enhanced MRI

A new MR contrast agent, MS-264 (Gd(1 RS)-1-(p-butylbenzyl)-DTPA), was developed to achieve hepatobiliary specificity and its potential evaluated for detecting and characterizing liver tumors in rats with chemically induced hepatocellular carcinoma (HCC). In seven rats with 66 HCC lesions, enhancements of different abdominal organs and tumors were compared on T₁-weighted images after intravenous administration of Gd-DTPA (0.3 mmol/kg) and MS-264 (0.05 mmol/kg). MR images were correlated with postmortem microangiographic and histological findings. An overall enhancement of different organs, which normalized within 24 h, was observed after Gd-DTPA and MS-264 injection. MS-264 caused a higher relative enhancement (RE) in liver (60%), compared with that of Gd-DTPA (40%), which resulted in a prompt negative contrast enhancement in 59 of 66 HCCs. All were moderately to poorly differentiated (Grades II–IV) tumors. Six of these 59 negative contrast-enhancing lesions showed a positively enhanced peritumoral rim, which corresponded histologically to malignant infiltration (n = 2) or compression (n = 4). On the other hand, six well differentiated HCCs showed prolonged positive enhancement. However, one well differentiated HCC was not positively enhanced by MS-264, probably due to poor access of the agent to the lesion. In comparison to that of the pre-contrast images, enhancement with Gd-DTPA and MS-264 increased the number of detected lesions by 22 and 42%, respectively. In this animal study, MS-264 proved to be useful in detection and characterization of primary liver cancers.     

Gd-DTPA-cascade-polymer: Potential blood pool contrast agent for MR imaging

Gadolinium-DTPA (diethylenetriaminepentaacetic acid)-cascade-polymer, a potential new blood pool contrast agent for magnetic resonance (MR) imaging, was compared with a known blood pool agent, Gd-DTPA-polylysine, in an animal model. The relative signal intensities of liver, renal cortex, pancreas, and trunk muscle were assessed in 12 pigs between 4 seconds and 120 minutes after injection of a 20 μmol/kg dose of each contrast agent, by using a FLASH (fast low-angle shot) sequence. Except for muscle, all tissues showed visible enhancement after injection of either contrast agent. After injection of Gd-DTPA-polymer, enhancement patterns in the liver, renal cortex, and pancreas were similar to those seen after injection of Gd-DTPA-polylysine. No statistically significant differences in enhancement between the two contrast agents were found at any time point. The authors conclude that the contrast kinetics of Gd-DTPA-cascade-polymer are similar to those of Gd-DTPA-polylysine and that this agent may also be used as a blood pool contrast agent for MR imaging.     

Quantitative Evaluation of Liver Function with MRI Using Gd-EOB-DTPA

Objective

Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a newly developed MR contrast agent. After intravenous injection, Gd-EOB-DTPA is gradually taken up by the hepatocytes and eventually excreted via the biliary pathway without any change to its chemical structure. Because of these characteristics, it can be used as a tracer for quantitative liver function testing. The purpose of this study is to develop a noninvasive method of quantitation of the hepatic function using Gd-EOB-DTPA through the deconvolution analysis.

Materials and Methods

Adult New Zealand white rabbits (n = 10, average body weight = 3.5 kg) were used in the present study. Hepatic injury was induced to by the intragastric administration of carbon tetrachloride (CCl4) three times a week for three weeks. Liver enzyme (aspartate aminotransferase, AST; alanine aminotransferase, ALT) levels and the plasma indocyanine green (ICG) retention rate 15 minutes after an intravenous injection of ICG (ICG R15), was checked before and after the three-week administration of CCl4. At the end of experimental period, an observer "blinded" to the treatment given the rabbits performed the histological examination. MRI studies were performed before and after the three-week administration of CCl4 on a 1.5 T scanner using a human extremity coil. After intravenous bolus injection of Gd-EOB-DTPA (0.3 mL of Gd-EOB-DTPA freshly prepared in 2.7 mL of normal saline) through the ear vein, the 250 axial single level dynamic MR images were obtained using a fast low angle shot (FLASH, TR/TE = 11/4.2 msec, flip angle = 15, acquisition time 1 second, slice thickness = 5 mm, matrix = 128×128, field of view = 120 mm) sequence with 1.5 sec time intervals. The time-intensity curves were obtained at the abdominal aorta and the liver parenchyma that was devoid of blood vessels. Deconvolution analysis of the aortic (input function) and hepatic parenchymal (output function) time-intensity curves was performed with a modified Fourier transform technique to calculate the hepatic extraction fraction (HEF). The presence and type of hepatic injury were determined by the histopathologic examination and statistical analysis of the changes of the hepatic enzyme levels, the ICG R15 and Gd-EOB-DTPA HEF values between the time before and after CCl4 administration with Wicoxon signed rank test. Correlation between the Gd-EOB-DTPA HEF and the change of the ICG R15 were analyzed with Pearson''s correlation coefficient.

Results

Histopathologic examination showed findings that were compatible with hepatic fibrosis caused by chronic liver injury. The initial blood biochemical studies before the administration of carbon tetrachloride showed that the mean AST and ALT levels were 39.8±5.2 IU/L and 59.1±11.7 IU/L, respectively. The AST and ALT levels increased to 138.4±50.5 IU and 172.0±71.6 IU/L, respectively, after the three week administration of CCl4. The ALT and AST levels were significantly increased after the three weeks of CCl4 administration (p = 0.018). The ICG R15 values were 4.47±2.08% and 19.43±3.98% before and after three-week administration of CCl4, respectively. The ICG R15 values were significantly increased after hepatic injury (p = 0.018). After normalizing the HEF as 100% in each rabbit before CCl4 administration, the deconvoluted curve after CCl4 administration revealed less hepatocyte extraction efficiency with a mean value of 77.7±3.6. There was a significant correlation between the HEF and changes of the ICG R15 by the Pearson correlation coefficient assessment (correlation coefficient = -0.965, p = 0.000).

Conclusion

The Gd-EOB-DTPA HEF could be calculated from deconvolution analysis of aortic and hepatic parenchymal time-intensity curves obtained by dynamic MRI. The Gd-EOB-DTPA HEF was well correlated with changes of the ICG R15, which is the most common parameter used in the quantitative estimation of the hepatic function. The Gd-EOB-DTPA HEF is a direct, noninvasive technique for the quantitative evaluation of liver function. It could be a promising alternative for the determination of noninvasive hepatic function in those patients with liver disease.     

Dynamics of tumor imaging with Gd-DTPA—polyethylene glycol polymers: Dependence on molecular weight

Macromolecular contrast media offer potential advantages over freely diffusible agents in magnetic resonance (MR) imaging outside the central nervous system. To identify an optimum molecular weight for macromolecular contrast media, the authors studied a novel macromolecular contrast agent, gadolinium diethylenetriaminepentaacetic acid polyethylene glycol (DTPA-PEG), synthesized in seven polymer (average) molecular weights ranging from 10 to 83 kd. Twenty-eight rabbits bearing V2 carcinoma in thighs underwent T1-weighted spin-echo imaging before injection and 5–60 minutes and 24 hours after injection of the Gd-DTPA-PEG polymers or Gd-DTPA at a gadolinium dose of 0.1 mmol/kg. Tumor region-of-interest measurements were obtained at each time point to determine contrast enhancement dynamics. Blood-pool enhancement dynamics were observed for the Gd-DTPA-PEG polymers larger than 20 kd. Polymers smaller than 20 kd displayed dynamics similar to those of the freely diffusible agent Gd-DTPA. Above the 20 kd threshold, tumor enhancement was more rapid for smaller polymers. The authors conclude that the 21.9-kd Gd-DTPA-PEG polymer is best suited for clinical MR imaging.     

Biliary imaging with Gd-EOB-DTPA: is a 20-minute delay sufficient?

RATIONALE AND OBJECTIVES: The authors performed this study to quantitate the change in intrabiliary signal intensity 20 minutes after gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) injection and to correlate the degree of biliary visualization with changes in biliary signal intensity. MATERIALS AND METHODS: Sixteen patients with known hepatic masses (without known biliary disease) who were candidates for resection were enrolled in an open-label protocol of Gd-EOB-DTPA. Three-dimensional spoiled gradient-echo magnetic resonance (MR) images obtained in the coronal plane with breath holding before and 20 minutes after Gd-EOB-DTPA made up the biliary MR cholangiogram study. Manually defined regions of interest were used to measure signal intensity in the bile ducts before and after contrast material administration. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated. Biliary visualization was qualitatively assessed by using a five-point scale. RESULTS: The SNR and CNR significantly increased (P < .0002) after the administration of contrast material. Average biliary visualization ratings were excellent, with moderate to excellent interobserver agreement. There was no correlation between measured SNR or CNR and visualization ratings. CONCLUSION: A 20-minute delay after Gd-EOB-DTPA administration appears to be sufficient for adequate biliary enhancement. Residual hepatic enhancement does not appear to interfere with biliary visualization.     

Performance of Gd-EOB-DTPA and superparamagnetic iron oxide particles in the detection of primary liver cancer: A comparative study by alternative free-response receiver operating characteristic analysis

The performance of gadolinium-ethoxybenzyl-dieth-ylenetriaminepentaacetic acid (Gd-EOB-DTPA) and superparamagnetic iron oxide (SPIO) particles in detecting liver cancer was compared using alternative free-response receiver operating characteristic (AFROC) analysis, which allowed observers to indicate both the confidence level and the locations of all perceived abnormalities. Axial T1-weighted MR images (1.5 T) pre/post Gd-EOB-DTPA (25 μmol/kg) injection were obtained for 12 rats with chemically induced liver tumors (64 tumors). T2-weighted images (T2WI) were obtained pre/post SPIO (10 μmol/kg) injection for the same animal. Liver signal-to-noise ratio (SNR), tumor-liver contrast-to-noise ratio (CNR), and histopathologic sections corresponding to MR images were obtained. In AFROC, the location and the confidence level for each tumor were indicated independently on MR images by four radiologists. By plotting true-positive fraction and probability of false-positive per image, the area under the AFROC curve (A1) was estimated and statistically analyzed between each sequence. Either drug significantly improved tumor-liver CNR (P < .001) and tumor detection (diameter ≤ 6 mm; P < .05). Gd-EOB-DTPA significantly (P < .05) improved the A1 in T1WI. There was no A1 difference between T2WI + SPIO and T1WI + Gd-EOB-DTPA. Gd-EOB-DTPA-enhanced T1WI showed the same performance as SPIO-enhanced T2WI in detecting liver tumors.     

Gd-DTPA在诊断卵巢肿块中的应用及评价

目的：正确评价Ｇｄ－ＤＴＰＡ在诊断卵巢病变中的作用。材料和方法：采用ＭＲ的Ｔ２加权成像（Ｔ２ＷＩ）和增强前后Ｔ１加权成像（Ｔ１ＷＩ）３种序列，对具有手术病理结果的７５例１１０个卵巢肿块进行回顾性分析。结果：静注Ｇｄ－ＤＴＰＡ后有以下变化特征：（１）恶性肿瘤特征显示正确率由８３．３％升至１００．０％。（２）良、恶性肿块的实质均有明显强化，其强化率之间无显著性差异（Ｐ＞０．０５）；不同强化时程，绝大多数病变的强化率也无明显差异（Ｐ＞０．０５）。（３）２２例手术病理明确分期的恶性肿瘤患者中，常规平扫Ｔ１ＷＩ及Ｔ２ＷＩ，分期正确率为５９．１％，运用造影剂后升至７７．３％，结合ＭＲＩ的３个序列可达８１．８％。结论：Ｇｄ－ＤＴＰＡ可改善对肿瘤的描述和对其内部结构的显示，提高对恶性肿瘤诊断及分期的正确率，但Ｇｄ－ＤＴＰＡ增强无特异性，尚不能依据信号的强化程度来判断病灶的性质，恰当的选择使用对临床具有重要的指导意义。     

Gadoteridol dose dependence in MR imaging of a liver abscess model

A necrotic liver abscess model was studied with magnetic resonance (MR) imaging at 1.5 T before and after intravenous administration of gadoteridol at doses of 0.1, 0.25, and 0.5 mmol/kg in 24 rabbits. Enhancement characteristics and lesion delineation were assessed with both breath-hold and non-breath-hold imaging techniques. Lesion delineation, as assessed both by signal intensity measurements and evaluations by two image readers blinded to imaging technique, was greatest on high-dose (0.5 mmol/kg) breath-hold images. Lesion rim enhancement was seen consistently only on postcontrast images obtained at a dose of 0.5 mmol/kg and progressed with time after injection of contrast material.