Dynamic and delayed contrast enhancement in upper abdominal MRI studies: comparison of gadoxetic acid and gadobutrol

OBJECTIVE: To prospectively compare contrast properties of extracelullar (gadobutrol) and hepatospecific (gadoxetic acid) contrast agents in upper abdominal MRI studies. MATERIALS AND METHODS: Standardized (0.1 ml/kg) dose of gadobutrol (56 subjects) and gadoxetic acid (51 subjects) was administered intravenously by MRI-compatible injector at 2 ml/s, followed by 20 ml saline flush. MR signal intensity changes (SIC) between precontrast scans and arterial phase, portal venous phase, equilibrium, and delayed scans at 10 and 20 min were measured in abdominal aorta, portal vein, common bile duct, liver, and spleen. Mean SIC values for gadobutrol and gadoxetic acid were compared by a two-sample t-test with p-value <0.05 considered significant. RESULTS: In abdominal aorta, the mean SIC in the arterial phase did not significantly differ between gadobutrol (330%) and gadoxetic acid (295%). In portal vein, the mean SIC in the portal venous phase significantly differed between gadobutrol (267%) and gadoxetic acid (176%). Liver parenchyma enhancement was significantly higher for gadobutrol than for gadoxetic acid in both arterial phase (28 versus 13%) and portal venous phase (81 versus 46%). On the contrary, gadobutrol reached significantly lower mean SIC in the liver on delayed scans at 10 min (47 versus 59%) and 20 min (40 versus 67%), as well as in common bile duct at 10 min (54 versus 133%) and 20 min (57 versus 457%), respectively. In the spleen, mean SIC for gadobutrol was significantly higher at all phases. CONCLUSION: Gadobutrol showed superior enhancement of upper abdominal structures in the dynamic phases whereas gadoxetic acid showed better enhancement of the hepatobiliary structures on delayed scans.     

MR imaging of the liver with Gd-BOPTA: quantitative analysis of T1-weighted images at two different doses.

This study evaluates the efficacy of gadobentate-dimeglumine (Gd-BOPTA) for enhancement of liver signal-to-noise ratio (SNR) and lesion-liver contrast-to-noise ratio (CNR) on T1-weighted spin-echo (SE) and gradient-recalled-echo (GRE) images at two different doses. Fifty patients with known or suspected liver lesions were examined at 1.5 T. T1-weighted SE (TR/TE 300/12 msec) and GRE images (TR/TE80/4.2 msec/flip angle 80 degrees) were obtained before and at 40-80 minutes and 90-120 minutes after administration of 0.05 or 0.1 mmol/kg Gd-BOPTA. Quantitative measurements of tissue signal intensity were performed at each dose. Liver showed significant enhancement after Gd-BOPTA on T1-weighted SE and GRE images (0.05 mmol: P < 0.05; 0.1 mmol: P < 0.001). The dose of 0.1 mmol/kg provided higher liver SNR than 0.05 mmol/kg. Mean liver SNR was higher on GRE than SE images (P < 0.0001). Lesion-liver CNR significantly increased on GRE images after 0.1 mmol (P < 0.05). There was a trend toward superiority of 0.1 mmol over 0.05 mmol/kg. GRE images were superior to SE images for pre- and post Gd-BOPTA lesion-liver CNR (P < 0.05). Our study suggests that Gd-BOPTA provides prolonged enhancement of liver SNR and CNR, that a dose of 0.1 mmol/Kg appears to be superior than 0.05 mmol/Kg, and that GRE techniques should be used in preference over SE techniques.     

Dynamic contrast‐enhanced magnetic resonance imaging of abdominal solid organ and major vessel: Comparison of enhancement effect between Gd‐EOB‐DTPA and Gd‐DTPA

Purpose

To evaluate the differences in enhancement of the abdominal solid organ and the major vessel on dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) obtained with gadolinium ethoxybenzyldiethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA: EOB) and gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) in the same patients.

Materials and Methods

A total of 13 healthy volunteers underwent repeat assessments of abdominal MR examinations with DCE‐MRI using either Gd‐DTPA at a dose of 0.1 mmol/kg body weight or EOB at a dose of 0.025 mmol/kg body weight. DCE images were obtained at precontrast injection and in the arterial phase (AP: 25 seconds), portal phase (PP: 70 seconds), and equilibrium phase (EP: 3 minutes). The signal intensities (SIs) of liver at AP, PP, and EP; the SIs of spleen, renal cortex, renal medulla, pancreas, adrenal gland, aorta at AP; and the SIs of portal vein and inferior vena cava (IVC) at PP were defined using region‐of‐interest measurements, and were used for calculation of signal intensity ratio (SIR).

Results

The mean SIRs of liver (0.195 ± 0.140), spleen (1.35 ± 0.353), renal cortex (1.58 ± 0.517), renal medulla (0.548 ± 0.259), pancreas (0.540 ± 0.183), adrenal gland (1.04 ± 0.405), and aorta (2.44 ± 0.648) at AP as well as the mean SIRs of portal vein (1.85 ± 0.477) and IVC (1.16 ± 0.187) at PP in the EOB images were significantly lower than those (0.337 ± 0.200, 1.99 ± 0.443, 2.01 ± 0.474, 0.742 ± 0.336, 0.771 ± 0.227, 1.26 ± 0.442, 3.22 ± 1.20, 2.73 ± 0.429, and 1.68 ± 0.366, respectively) in the Gd‐DTPA images (P < 0.05 each). There was no significant difference in mean SIR of liver at PP between EOB (0.529 ± 0.124) and Gd‐DTPA (0.564 ± 0.139). Conversely, the mean SIR of liver at EP was significantly higher with EOB (0.576 ± 0.167) than with Gd‐DTPA (0.396 ± 0.093) (P < 0.001).

Conclusion

Lower arterial vascular and parenchymal enhancement with Gd‐EOB, as compared with Gd‐DTPA, may require reassessment of its dose, despite the higher late venous phase liver parenchymal enhancement. J. Magn. Reson. Imaging 2009;29:636–640. © 2009 Wiley‐Liss, Inc.     

超顺磁性氧化铁（SPIO）对比剂肝脾MR成像的比较研究

目的 比较两种超顺磁性氧化铁（superparamagnetic iron oxide,SPIO)对比剂,Ferumoxides及SHU－555A在肝脾MR成像中的效应。材料与方法 36例已知为肝转移癌患者于SPIO造影前后进行T2WI快速自旋回波成像（T2WI TSE）及T1WI梯度回波快去速相位成像（T1WI FLASH）。扫描伪为1．0T MR机。18例患者行Ferumoxides增强后90分钟进行MR成像;另18例行SHU－55A快速团柱增强,注药后即刻、30秒及480秒行T1WI FLASH成像,10分钟行T2WI TSE成像。测量肝脾、肝转移癌SPIO增强前后的信号强度（signal intensity,SI),计算两种SPIO对比剂在肝脾、肝转移癌增强前后SI变化的百分比（percentage signal intensity change,PSIC)及病灶肝脏对比噪声比（lesion-to-liver contrast-to-noise ratio,CNR)及其变化（ΔCNR）。结果 在T2WI TSE图像上,两种SPIO对比剂造成的肝实质SI下降无显著性差异（P＞0．05）。Ferumoxides引的脾信号下降显著大于SHU－555A（P＜0．05）。两种SPIO对比剂均导致肝实转移癌SNR显著增高。T1WI FLASH图像上,两种对比剂均可导致延迟像上肝脏SI的轻度下降及肝转移癌CNR下降,两者肝脏SIC之间无显著性差异。T1WI上两种对比剂均可导致脾脏SI显著升高,两者脾脏PSIC之间无显著性差异（P＞0．05）。结论 两种SPIO在肝脏的TI及T2增强效应相似,而脾脏的T2增强效应,Ferumoxides强于SHU－555A。     

Evaluation of the changes in signals from the spleen using ferucarbotran

Purpose Because superparamagnetic iron oxide is actively taken into the reticuloendothelial system, the signal intensity observed on T2-weighted images is reduced not only in the liver but also in the spleen. There is no difference in the reduction in signal intensity in the liver after contrast between the ferumoxides and ferucarbotran, but the reduction in signal intensity in the spleen is considerable. In the present study, we examined the efficacy of T2*-weighted imaging to compensate for the reduction in signal intensity in the spleen by administering ferucarbotran. Materials and methods We examined the images obtained from 35 patients who underwent MRI with ferucarbotran. T2-weighted images and T2*-weighted images were obtained before and after administration of ferucarbotran, and the changes in signal intensity in the liver and spleen were then analyzed. Results A reduction in signal intensity was observed in the liver by both T2- and T2*-weighted imaging. In the spleen, the signal intensity was reduced on T2-weighted images but was not reduced on T2*-weighted images. Conclusion The reduction in signal intensity due to administration of ferucarbotran is low in the spleen. Thus, it was considered necessary to approach the problem of diagnosing ectopic splenic tissue using ferucarbotran with caution.     

Multinodular focal fatty infiltration of the liver: atypical imaging findings on delayed T1-weighted Gd-BOPTA-enhanced liver-specific MR images

We report a case of pathologically confirmed multinodular focal fatty infiltration. MRI was performed after bolus injection of gadobenate dimeglumine (Gd-BOPTA, MultiHance; Bracco, Milan, Italy), a liver-specific paramagnetic, gadolinium (Gd)-based MR contrast agent that concomitantly enables the acquisition of a standard dynamic phase with timing strategies similar to those used for other extracellular fluid contrast agents, followed by a delayed T1-weighted liver-specific phase (the so-called hepatobiliary phase). In the present case, multiple rounded areas of fatty infiltration, although confidently diagnosed using chemical shift sequences due to a significant signal intensity reduction on out-of-phase images, were unexpectedly hypointense during the delayed liver-specific phase of Gd-BOPTA. Reduced Gd-BOPTA concentration during the liver-specific phase is generally correlated with liver malignancy. Since such lesions can be prospectively mistaken for metastatic disease, we performed a hepatic biopsy to establish a definitive diagnosis. Our empirical observations suggest that Gd-BOPTA uptake may be impaired in fatty infiltrated liver tissue. Because at present there is no report evaluating the kinetics of Gd-BOPTA in fatty liver, further studies are needed to specifically investigate this issue.     

Focal liver lesions: SPIO-, gadolinium-, and ferucarbotran-enhanced dynamic T1-weighted and delayed T2-weighted MR imaging in rabbits

PURPOSE: To compare a superparamagnetic iron oxide (SPIO), VSOP-C184, with a gadopentetate dimeglumine with regard to signal-enhancing effects on T1-weighted dynamic magnetic resonance (MR) images and with another SPIO contrast medium with regard to signal-reducing effects on delayed T2-weighted MR images. MATERIALS AND METHODS: All experiments were approved by the responsible Animal Care Committee. Twenty rabbits (five for each contrast agent and dose) implanted with VX-2 carcinoma were imaged at 1.5 T. VSOP-C184 at 0.015 and 0.025 mmol Fe/kg was compared with gadopentetate dimeglumine at 0.15 mmol Gd/kg and ferucarbotran at 0.015 mmol Fe/kg. The imaging protocol comprised a T1-weighted dynamic gradient-echo (GRE) MR before injection and at 6-second intervals for up to 42 seconds after injection and a T2-weighted turbo spin-echo MR before and 5 minutes after injection. Images were evaluated quantitatively, and contrast media were compared by using nonparametric analysis of variance. RESULTS: At dynamic T1-weighted GRE MR imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median peak contrast-to-noise ratio (CNR) was 20.7 (25th percentile, 16.3; 75th percentile, 22.6), 24.2 (25th percentile, 19.3; 75th percentile, 28.5), 16.4 (25th percentile, 13.7; 75th percentile, 20.3), and 14.0 (25th percentile, 11.4; 75th percentile, 16.8), respectively. Both doses of VSOP-C184 yielded significantly higher CNR (P < .05) than the other two agents. At T2-weighted turbo spin-echo imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median CNR was 15.0 (25th percentile, 13.4; 75th percentile, 21.3), 15.7 (25th percentile, 14.5; 75th percentile, 19.8), 11.3 (25th percentile, 8.2; 75th percentile, 12.2), and 15.7 (25th percentile, 12.5; 75th percentile, 22.4), respectively. There was no significant difference between VSOP-C184 and ferucarbotran; both had a significantly higher CNR than did gadopentetate dimeglumine. CONCLUSION: VSOP-C184 produces higher liver-to-tumor contrast at dynamic T1-weighted imaging than does gadopentetate dimeglumine; at delayed T2-weighted imaging, the contrast is comparable to that achieved with ferucarbotran.     

Hepatocellular MR contrast agents: enhancement characteristics of liver parenchyma and portal vein after administration of gadoxetic acid in comparison to gadobenate dimeglumine

Purpose

To investigate the enhancement characteristics of liver parenchyma and portal vein as well as the portal vein-to liver contrast in Gd-EOB-DTPA- and Gd-BOPTA-enhanced abdominal MRI.

Materials and methods

The local institutional review board approved this retrospective study. A total of 70 patients (30 female, 40 male) without relevant liver disease underwent either Gd-EOB-DTPA-enhanced (35 patients, dose 0.025 mmol/kg) or Gd-BOPTA-enhanced (35 patients, dose 0.1 mmol/kg) abdominal MRI. Signal-to-noise ratios (SNR) for the portal vein and the liver as well as portal vein-to-liver contrast-to-noise ratios (CNR) were calculated for three consecutive arterial phases, one portal venous phase and one delayed imaging phase.

Results

The liver SNR showed higher values for the Gd-BOPTA group in the arterial and portal venous phases (statistically significant for the second and third arterial phase), while the liver SNR in the delayed phase was higher for the Gd-EOB-DTPA group. The portal venous SNR as well as the portal vein-to-liver CNR was higher in the Gd-BOPTA group in all imaging phases (statistically significant in all phases except for the first arterial phase).

Conclusion

The enhancement of liver parenchyma and portal vein as well as the portal vein-to-liver contrast in the arterial and portal venous imaging phases were higher for patients receiving Gd-BOPTA compared with Gd-EOB-DTPA at the respective recommended doses. Gd-BOPTA might therefore enable better evaluation of the portal vein.     

Contrast-enhanced MR imaging of the liver: Comparison between Gd-BOPTA and mangafodipir

The purpose of the study was to evaluate the MR contrast agents gadolinium benzyloxypropionictetro-acetate (Gd-BOPTA) and Mangafodipir for liver enhancement and the lesion-liver contrast on T1W spin-echo (SE) and gradient-recalled-echo (GRE) images. Fifty-one patients (three groups of 17 patients each) with known or suspected liver lesions were evaluated with T1W SE (300/12) and GRE (77-80/2.3-2.5/80°) images before and after intravenous (IV) Gd-BOPTA (0.1 or 0.05 mmol/kg) or Mangafodipir (5 μmol/kg) in phase II to III clinical trials. Quantitative analysis by calculating liver signal-to-noise ratio (SNR), lesion-liver contrast-to-noise ratio (CNR), and spleen-liver CNR was performed. Liver SNR and spleen-liver CNR were always significantly increased postcontrast. SNR was highest after application of 0.1 mmol/kg Gd-BOPTA (51.3 ± 3.6, P < .05). CNR was highest after Mangafodipir (?22.6 ± 2.7), but this was not significantly different from others (P = .07). Overall, GRE images were superior to SE images for SNR and CNR. Mangafodipir and Gd-BOPTA (0.1 mmol/kg) provide equal liver enhancement and lesion conspicuity postcontrast. By all criteria, contrast-enhanced T1-weighted GRE were comparable to SE images.     

Superparamagnetic iron oxide (SPIO)-enhanced liver MRI with ferucarbotran: efficacy for characterization of focal liver lesions

PURPOSE: To evaluate the efficacy of ferucarbotran in T2-weighted (T2W) fast spin-echo (FSE) and T2*W gradient-echo (GRE) sequences for characterizing focal liver lesions. MATERIALS AND METHODS: In 68 patients, 46 malignant and 22 benign focal liver lesions were evaluated. Precontrast (NCE) T2W FSE images and contrast-enhanced (CE) T2W FSE and T2*W GRE images were obtained on a 1.5T MR system. Based on signal intensity (SI) measurements in focal lesions and liver parenchyma, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all sequences. The percentage of SI loss (PSIL) in focal lesions after contrast agent (CA) application was calculated for the T2W FSE sequence. Qualitative analyses were performed to assess image quality and lesion conspicuity obtained with the CE-T2W FSE and CE-T2*W GRE sequences. RESULTS: The mean PSIL was higher in solid benign lesions than in malignant lesions (39.6% vs. 3.2%, P<0.05). With a threshold PSIL of 25%, the sensitivity and specificity for characterizing malignant lesions were 97.8% and 92.9%, respectively. The mean CNR of the malignant lesions was higher in the CE-T2*W sequence than in the CE- and NCE-T2W FSE sequences (29.9 vs. 22.7 (P<0.01) vs. 12.8 (P<0.01)). CE-T2*W images showed a superior image quality and lesion conspicuity (P<0.05) compared to the CE-T2W FSE sequence. CONCLUSION: The PSIL can be an accurate tool for characterizing benign and malignant lesions. The addition of a CE-T2*W GRE sequence is helpful for the detection and characterization of malignant lesions.     

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。     

MRI特异性对比剂铁羧葡胺对肝脏局灶性病变检出的比较研究

目的 通过比较MR平扫、应用对比剂钆喷替酸葡甲胺（Gd—DTPA）增强MRI及MRI特异性对比剂铁羧葡胺增强MRI对肝脏局灶性病变的检出，验证铁羧葡胺在病灶检出方面的优势。方法 2003年12月至2004年7月，选择怀疑为肝脏局灶性病变的病例59例，根据相对金标准判定共133个病灶。所有病例均先行梯度回波（GRE）T1WI、去脂快速自旋回波（FSE）序列T2WI、动态梯度回波Gd—DTPA增强MRI，48h后行铁羧葡胺动态GRE增强扫描及去脂FSE T2WI与GRE TW^＊W延迟扫描。统计各序列对局灶性病变检出的敏感性。结果 铁羧葡胺延迟增强去脂FSE T2W序列、动态GRE增强扫描、GRE T2^＊W延迟增强扫描检出病灶数分别为130、115、127个；平扫GRE T1WI序列、去脂FSE T2WI检出病灶分别为84和106个；Gd—DTPA动态GRE增强检出123个病灶。对于其中44个的微小病灶（〈1cm），铁羧葡胺延迟增强去脂FSE T2WI检出率达到932％（41/44），铁羧葡胺动态增强检出率为727％（32/44），铁羧葡胺延迟增强GRE T2^＊WI检出率为886％（39/44），Gd—DTPA动态增强检出率为795％（35/44），平扫去脂FSE T2WI检出率为545％（24/44），平扫GRE T1WI检出率为34.1％（15/44）。铁羧葡胺延迟增强去脂FSE T2WI及GRE T2WI显著提高了对于微小病灶（〈1cm）的检出率，与平扫MR（包括去脂FSE T2WI和GRE T1WI）及Gd—DTPA动态增强MR相比差异有统计学意义（P〈005）。结论 铁羧葡胺延迟增强去脂FSE T2WI及GRE T2^＊WI序列优势主要为提高肝微小病灶（〈10cm）的检出率。     

Evaluation of gadobenate dimeglumine in hepatocellular carcinoma: results from phase II and phase III clinical trials in Japan.

To evaluate the clinical efficacy of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging for hepatocellular carcinoma (HCC), we reviewed the results of clinical phase II and III trials in Japan. Gd-BOPTA was administered at a dose of 0.1 mmol/kg to 139 patients who were suspected to have HCC. Dynamic phase images [breath-hold T1-weighted gradient echo (GRE)], spin-echo (SE) images obtained within 10 minutes of injection, and delayed breath-hold GRE images obtained 40-120 minutes after injection were evaluated. All post-contrast images were compared with T1- and T2-weighted pre-contrast images. The contrast efficacy for the dynamic study was classified as ( ) or (++) in 92.1% (128/139), in 43.1% (59/137) with SE within 10 minutes of injection, and in 43.2% (60/139) with breath-hold GRE at delayed phase. The increase in lesion-liver contrast-to-noise ratio was best at the arterial phase of dynamic breath-hold GRE. Liver signal-to-noise ratio showed a mean 52.3% increase in delayed phase. Additional information at delayed phase compared with images acquired within 10 minutes of injection (including the dynamic study) was classified as ( ) or (++) in 28.1% (39/139). With regard to safety, the overall incidence of adverse reactions was 5.0% (7/141) of the patients who were suspected to have HCC, all of whom recovered within 12 hours without any sequelae. No clinically important changes were observed in the blood and urine laboratory tests. It was concluded that Gd-BOPTA was well tolerated and effective in both dynamic study and delayed static imaging for the diagnosis of HCC.     

How to compare the efficiency of albumin-bound and nonalbumin-bound contrast agents in vivo: the concept of dynamic relaxivity

RATIONALE AND OBJECTIVES: The objective of this study was to compare, in a rabbit experimental model that mimics a magnetic resonance (MR) angiographic protocol, the efficiency of the following types of compound on the MR signal: (1) a nonalbumin-bound blood pool contrast agent: P792; (2) a weak albumin-bound extracellular contrast agent: Gd-BOPTA; and (3) a strong albumin-bound blood pool contrast agent: MS325. METHODS: The 2 main phases of early distribution after contrast agent injection, ie, the bolus phase (0-15 seconds postinjection) and the postbolus phase (1-5 minutes postinjection) were investigated by measuring Gd blood concentrations in the first 5 minutes postinjection. In the case of MS325 and Gd-BOPTA, the percentage of the free and bound forms were calculated throughout the pharmacokinetic profile. The dynamic relaxivity at 60 MHz in plasma of each contrast agent was determined in the 2 phases after contrast agent injection, ie, the bolus phase and the postbolus phase. RESULTS: Injected under similar conditions, the 3 contrast agents had a comparable profile during the bolus phase (0-15 seconds postinjection). At 1 minute postinjection, only 38% of Gd-BOPTA remained in the blood, whereas 85% of P792 was still present in the blood. MS-325 had an intermediate position with 61% remaining in the blood. During the postbolus phase, the various compounds demonstrated similar behavior: the plasma concentration of P792 was higher than that of MS325 and Gd-BOPTA, ie, Ci/C0 (P792)>Ci/C0 (MS325)>Ci/C0 (Gd-BOPTA). At the peak of the bolus, 75% of MS325 and 93% of Gd-BOPTA was present in free form. This proportion decreased progressively during the postbolus phase, because 5 minutes postinjection, 23% of the free form remained for MS325 and 82% for Gd BOPTA. A significant decrease in dynamic r1 relaxivity was observed at 60 MHz for the products that bind to albumin (Gd-BOPTA and MS325) during the bolus phase. The dynamic relaxivity for MS325 at the bolus phase was 8.6 mMs and 5.2 mMs for Gd-BOPTA. At the postbolus phase, the dynamic relaxivity increased (17.3 mMs for MS325 and 6.7 mMs for Gd-BOPTA). The dynamic relaxivity of P792, which does not bind to albumin, was constantly equal to 26 mMs at each time point of the pharmacokinetic profile (bolus and postbolus phase). CONCLUSIONS: The physicochemical measurements of relaxivity in plasma are made in vitro at a fixed concentration of gadolinium and the value of relaxivity is not necessarily an accurate reflection of the efficiency of the contrast agent in vivo, especially for contrast agents that bind to albumin. Indeed, in vivo, the proportion of free and bound forms of albumin-binding contrast agents varies according to the pharmacokinetic profile, and the relaxivities of albumin-bound and free contrast agents are different. Consequently, the concept of dynamic relaxivity was introduced to compare the efficiency of MS325, Gd-BOPTA, and P792 in vivo. The variation of the dynamic relaxivity of MS325 and Gd-BOPTA between the bolus and postbolus phase is significant (101% for MS325 and 29% for Gd-BOPTA) as a result of the variation in the quantity of bound and free forms during the pharmacokinetic profile. The blood pool agent P792 has different properties, which result from its intravascular retention and its lack of albumin binding. Indeed, contrary to Gd-BOPTA and MS325, the dynamic relaxivity of P792 is higher at the bolus phase (26 mMs) and does not vary during the pharmacokinetic profile. The impact of these different dynamic relaxivities should be integrated in the analysis of the performance of the different classes of contrast agents in clinical MRA protocols.     

Accurate differentiation of focal nodular hyperplasia from hepatic adenoma at gadobenate dimeglumine-enhanced MR imaging: prospective study

PURPOSE: To prospectively determine the accuracy of differentiating benign focal nodular hyperplasia (FNH) from hepatic adenoma (HA) and liver adenomatosis (LA) by using gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging. MATERIALS AND METHODS: The ethics committee at each center approved the study, and all patients provided informed consent. Seventy-three patients with confirmed FNH and 35 patients with confirmed HA (n = 27) or LA (n = 8) underwent MR imaging before (T2-weighted half-Fourier rapid acquisition with relaxation enhancement or T2-weighted fast spin-echo and T1-weighted gradient-echo [GRE] sequences) and at 25-30 seconds (arterial phase), 70-90 seconds (portal venous phase), 3-5 minutes (equilibrium phase), and 1-3 hours (delayed phase) after (T1-weighted GRE sequences only, with or without fat suppression) bolus administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. The enhancement of 235 lesions (128 FNH, 32 HA, and 75 LA lesions) relative to the normal liver parenchyma was assessed. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy for the differentiation of FNH from HA and LA were determined. RESULTS: Hyper- and isointensity on T2-weighted and iso- and hypointensity on T1-weighted GRE images were noted for 177 (88.9%) of 199 lesions visible on unenhanced images. On dynamic phase images after contrast material administration, 231 (98.3%) of 235 lesions showed rapid strong enhancement during the arterial phase and appeared hyper- to isointense during portal venous and equilibrium phases. Accurate differentiation of FNH from HA and LA was not possible on the basis of precontrast or dynamic phase images alone. At 1-3 hours after contrast material enhancement, 124 (96.9%) of 128 FNHs appeared hyper- or isointense, while 107 (100%) HA and LA lesions appeared hypointense. The sensitivity, specificity, PPV, NPV, and overall accuracy for the differentiation of FNH from HA and LA were 96.9%, 100%, 100%, 96.4%, and 98.3%, respectively. CONCLUSION: Accurate differentiation of FNH from HA and LA is achievable on delayed T1-weighted GRE images after administration of gadobenate dimeglumine.     

Detection of portal perfusion abnormalities: comparison of 3 ferucarbotran-enhanced magnetic resonance imaging sequences

OBJECTIVE: To estimate the accuracy, sensitivity, and specificity of 3 ferucarbotran-enhanced magnetic resonance (MR) imaging sequences prospectively for the detection of nontumoral portal perfusion abnormalities. METHODS: Thirty-nine noncirrhotic patients with liver metastases underwent computed tomography during arterial portography (CTAP) and MR imaging comprising T1-weighted gradient recalled echo (GRE), T2-weighted fast spin echo (FSE), and T2*-weighted GRE sequences with and without ferucarbotran. Magnetic resonance images were reviewed by 4 blinded observers for rating based on the confidence scale. The accuracy, sensitivity, and specificity for each sequence were measured by receiver operating characteristic analysis. Contrast-to-noise ratio (CNR) and relative signal-to-noise ratio changes were statistically compared. RESULTS: Thirty-nine nontumoral perfusion defects were observed in 22 patients by CTAP. Receiver operating characteristic analysis showed the accuracy was higher for T2*-weighted GRE (0.884) than for T1-weighted GRE (0.572) and T2-weighted FSE (0.597). T2*-weighted imaging achieved the highest sensitivity (81.4%) and the lowest specificity (86.6%). Postenhanced T2*-weighted imaging achieved the highest CNR (19.3 +/- 9.2). CONCLUSIONS: T2*-weighted imaging was the most accurate and sensitive method for detecting portal perfusion abnormalities compared with T1- or T2-weighted imaging, whereas T1- or T2-weighted imaging is superior in specificity to T2*-weighted imaging during ferucarbotran-enhanced MR imaging.     

Gadoxetic acid disodium-enhanced magnetic resonance imaging for biliary and vascular evaluations in preoperative living liver donors: comparison with gadobenate dimeglumine-enhanced MRI

Purpose

To compare gadoxetic acid disodium (Gd‐EOB‐DTPA)‐enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine (Gd‐BOPTA)‐enhanced MRI in preoperative living liver donors for the evaluation of vascular and biliary variations.

Materials and Methods

Sixty‐two living liver donors who underwent preoperative MRI were included in this study. Thirty‐one patients underwent MRI with Gd‐EOB‐DTPA enhancement, and the other 31 underwent MRI with Gd‐BOPTA enhancement. Two abdominal radiologists retrospectively reviewed dynamic T1‐weighted and T1‐weighted MR cholangiography images and ranked overall image qualities for the depiction of the hepatic artery, portal vein, hepatic vein, and bile duct on a 5‐point scale and determined the presence and types of normal variations in each dynamic phase. Semiquantitative analysis for bile duct visualization was also conducted by calculating bile duct‐to‐liver contrast ratios.

Results

No statistical differences were found between the two contrast media in terms of hepatic artery or bile duct image quality by the two reviewers, or in terms of portal vein image quality by one reviewer (P > 0.05). Gd‐BOPTA provided better image qualities than Gd‐EOB‐DTPA for the depiction of hepatic veins by both reviewers, and for the depiction of portal veins by one reviewer (P < 0.01). The two contrast media‐enhanced images had similar bile duct‐to‐liver contrast ratios (P > 0.05). Regarding diagnostic accuracies with hepatic vascular/biliary branching types, no significant differences were observed between the two contrast media (P > 0.05).

Conclusion

Gd‐EOB‐DTPA could be as useful as Gd‐BOPTA for the preoperative evaluation of living liver donors, and has the advantage of early hepatobiliary phase image acquisition. J. Magn. Reson. Imaging 2011;33:149–159. © 2010 Wiley‐Liss, Inc.     

Application of pharmacokinetics to electron-beam tomography of the abdomen

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the pharmacokinetics of abdominal time-attenuation curves obtained at electron-beam tomography. MATERIALS AND METHODS: Computed tomographic enhancement data of the aorta, portal vein, vena cava, liver, spleen, and pancreas were obtained in 25 patients after injection of 50 mL of contrast medium. These data were used to calculate pharmacokinetic parameters such as half-lives, mean residence times, and areas under the curve with a computer program. RESULTS: Maximal enhancement was observed in the aorta 24 seconds +/- 5 (mean +/- standard deviation) after starting the injection of contrast medium (178 HU +/- 56), in the portal vein after 42 seconds +/- 14 (60 HU +/- 17), in the vena cava after 35 seconds +/- 7 (66 HU +/- 23), in the liver after 58 seconds +/- 15 (24 HU +/- 6), in the spleen after 35 seconds +/- 12 (42 HU +/- 16), and in the pancreas after 39 seconds +/- 15 (42 HU +/- 10). Half-lives of the last phase observed were 108 seconds +/- 123 in the aorta, 33 seconds +/- 30 in the portal vein, 49 seconds +/- 40 in the vena cava, 50 seconds +/- 54 in the liver, 62 seconds +/- 33 in the spleen, and 22 seconds +/- 27 in the pancreas. The computer program allowed for excellent fitting curves to the measured attenuation values and for subsequent calculation of pharmacokinetic parameters. New dosage regimens also could be simulated successfully. CONCLUSION: The pharmacokinetic parameters evaluated might be useful in the optimization of dosing and scanning parameters of the abdomen for ultrafast and helical CT.     

Contrast-enhanced 3D-MRA of the upper abdomen with a bolus-injectable SPIO (SH U 555 A).

The purpose of this study was to study temporal changes in signal intensity of liver, spleen, abdominal vessels, and focal liver lesions following iv bolus injection of a superparamagnetic iron oxide (SPIO) using a breath-held three-dimensional magnetic resonance angiography (3D-MRA) sequence. Dynamic SH U 555 A-enhanced 3D-MRA studies were performed in 20 patients with focal liver lesions. Sequential coronal 3D-MRA-FISP scans were acquired (TR 5.0 msec, TE 2.0 msec, flip angle 25 degrees, 140 x 256 matrix, and 80 mm slab) within 15 seconds. Scanning was started immediately after bolus injection of 10 micromol Fe/kg bodyweight and was repeated at multiple time points (baseline and 30, 60, 90, 120, 180, 240, 300, 360, and 420 seconds). Signal intensity values of liver, focal liver lesions, spleen, the portal venous system, the abdominal aorta, and the inferior vena cava were obtained to calculate relative enhancement (ENH = [SI post - SI pre]/SI pre x 100). Visibility of vessels was assessed by consensus of two readers. Signal enhancement within abdominal vessels peaked during the first pass; however, significant signal enhancement was still present 420 seconds following injection. The liver and the spleen also demonstrated a biphasic enhancement pattern with prolonged parenchymal enhancement. Dynamic MRA with bolus injectable SH U 555 A is clinically feasible, and significant vessel enhancement can be achieved even at the dose of 10 micromol Fe/kg bodyweight. However, further refinements are required to improve contrast effects.     

Evaluation of small (<or=2 cm) dysplastic nodules and well-differentiated hepatocellular carcinomas with ferucarbotran-enhanced MRI in a 1.0-T MRI unit: utility of T2*-weighted gradient echo sequences with an intermediate-echo time

PURPOSE: To evaluate the detectability and signal intensities of small (相似文献