MR findings in eosinophilic infiltration of the liver

OBJECTIVE: This study describes the findings of magnetic resonance imaging (MRI) of focal eosinophilic infiltration of the liver. METHODS: Contrast-enhanced MR images of 8 patients with focal hepatic eosinophilic infiltration were reviewed retrospectively. We evaluated the signal intensity of focal lesions in T1-weighted and T2-weighted images and the pattern of enhancement in a dynamic contrast study. RESULTS: A total 22 focal hepatic lesions were observed; the lesions were isointense (55%) or hypointense (45%) on T1-weighted images and isointense (14%) or hyperintense (86%) on T2-weighted images. The arterial phase of the contrast study revealed 11 hyperintense lesions (50%). During the portal and delayed phases, 18 (82%) and 17 lesions (77%) were hyperintense, respectively. CONCLUSION: The focal eosinophilic infiltrations showed homogeneous enhancement in the portal and delayed phases in the dynamic contrast MR study. These findings should help to distinguish focal eosinophilic infiltration, especially from metastasis in patients with malignancy.     

肝脏局灶结节性增生的CT、MRI诊断

目的:评估CT、MRI对肝脏局灶结节性增生(focal nodular hyperplasia,FNH)的诊断价值.材料和方法:回顾性分析9例FNH(6例经病理证实,3例经磁共振特异性对比剂Resovist证实)的CT、MRI表现和术前或穿刺前诊断.结果:8例为单发病灶、1例为3个病灶.10个病灶呈稍低密度,其中7个T1WI为稍低信号、T2WI稍高信号,3个病灶T1WI和T2WI为稍高信号;1个病灶为等密度和等信号;CT动脉期明显增强、门静脉期轻度增强或无增强;MRI的增强方式与CT相似,但10个病灶存在明显的延迟增强.7个病灶检出瘢痕,T1WI呈低信号、T2WI高信号,动脉期和门静脉期无增强、延迟期轻至中度增强.8例单发病灶均正确诊断为FNH.结论:CT和MRI能显示FNH的特征性改变并提高诊断的准确性.     

肝脏炎性假瘤的CT及MRI征象

目的:探讨肝脏炎性假瘤的CT和MRI表现。方法:8例经手术病理证实的肝脏炎性假瘤。男5例,女3例,年龄35~65岁,平均53岁。8例均作CT平扫及增强扫描,其中3例行MR对比检查。结果:CT表现为1 个病灶6 例,2个病灶2例,共发现病灶10个。平扫9个病灶表现为低密度,1 个病灶表现为稍高密度。动态增强扫描2 个病灶动脉期显著强化,门脉期及延迟期中度强化;8个病灶动脉期无明显强化,门脉期及延迟期有不同方式的强化,主要表现为周边完整或不完整的环形或结节状强化,中心核心样强化及线状或不规则分隔样强化。MRI表现为2 例病灶T1WI呈低信号,T2WI呈稍高信号,1例病灶T1WI及T2WI均为等信号,动态增强扫描与CT相仿。结论:肝脏炎性假瘤的CT及MRI表现因其病理阶段不同而表现各异,诊断需结合临床,确诊尚依靠病理检查。     

肝硬化结节与小肝癌的MRI研究

目的:回顾性分析肝硬化合并小肝癌、再生结节(RN)及肝不典型增生结节(DN)的MR表现,探讨其MR诊断与鉴别诊断。方法:收集50例结节性肝硬化病例MR检查资料,患者行正反相位T1WI、脂肪抑制T2WI、动态增强扫描和弥散加权(DWI)扫描,总结肝内结节的信号特点。结果:RN在T1WI脂肪抑制上多为等信号或稍高信号,T2WI多为低信号,增强后与周围正常肝组织强化相似或信号稍低;DN在T1WI多为较高信号,T2WI多为稍低或等信号,增强后强化不明显;癌结节T1WI多为稍低或等信号,偶有稍高信号,T2WI多为较高信号,DWI为高信号,强化多为动脉中晚期强化,门静脉期以后强化减退。结论:磁共振平扫加动态增强能对大多数RN、DN和小肝癌结节做出明确诊断和鉴别。     

肝脏孤立性坏死结节的MRI表现

目的 总结肝脏孤立性坏死结节(SNN)平扫和动态增强MRI特征性表现.方法 回顾性分析经手术病理证实的15例SNN的MRI征象,对病灶数目、形状、大小、部位、边界、平扫和增强后信号及强化方式进行评价.结果 病灶单发14例,另1例有2个病灶.平扫T1WI及T2WI各发现15和14个病灶,增强扫描发现16个病灶.14个病灶最大径≤3 cm.平扫T1WI病灶呈低信号5个,略低信号9个,1个呈等信号伴有周边低信号包膜及内部点状低信号.在T2WI病灶呈高信号5个,略高信号4个,略低信号3个,明显低信号2个,其中2个病灶内见点状或细线样极高信号.16例在增强扫描后各期均呈低信号,尤其在门静脉期及延迟期呈明显低信号,边界及形态显示清楚.12个病灶形状不规则,4个病灶呈圆形或卵圆形.增强后病灶内部均未见强化,3个病灶在门静脉期及延迟期可见细环状轻度强化的包膜.结论 SNN特征性MRI表现有助于与肝脏其他肿瘤鉴别.     

抑脂技术和动态增强MRI在胰岛素瘤诊断中的价值探讨

目的 探讨抑脂技术和动态增强MRI在胰岛素瘤术前定位诊断中的价值。方法 12例手术病理证实的胰岛素瘤患者术前行MR检查，扫描序列包括：横断面SE T1WI，快速自旋回波(FSE)T2WI，加脂肪抑制技术的T1WI和T2WI(即T1WI FS和T2WI FS)，快速多层面扰相梯度回波(FMPSPGR)序列作动态增强扫描。结果 在常规T1WI和T2WI序列仅检出4例肿瘤，表现为T1WI稍低信号和T2WI稍高信号。在T1WI FS上7例呈均匀低信号，显示清晰；在T2WI FS上6例病灶呈不同程度的高信号。快速动态增强扫描(FMPSPGR)检出11例肿瘤，在动脉期7例肿瘤明显强化呈高信号，4例轻度强化呈稍高信号，1例无明显强化呈等信号，胰腺实质期和门脉期6例仍呈高信号，6例呈等信号。与手术后病理结果比较，动态增强MRI对胰岛素瘤术前定位诊断准确率为91．7％(11／12)。结论 动态增强MRI是胰岛素瘤术前定位诊断敏感而准确的方法。     

原发性透明细胞型肝癌的CT和MRI诊断

目的 探讨原发性透明细胞型肝癌的影像表现,评价CT和MRI对该病的诊断价值.方法 回顾性分析19例经手术病理证实的原发性透明细胞型肝癌的CT和MRI表现.13例行CT平扫和动态增强扫描,8例行MR T1WI、T2WI和动态增强扫描.结果 CT平扫13例病灶均为低密度,其中9例病灶内部见不规则的更低密度影.增强后动脉期所有病灶均有强化表现,9例病灶不均匀强化,病灶中心有无强化的低密度区.门静脉期11例病灶呈相对低密度,2例呈等密度.3例可见环形强化的包膜.MR T1WI上5例病灶为低信号,3例为稍高信号.T2WI上5例病灶为混杂高信号,3例为等、低信号.MRI增强动脉期所有病灶均有显著强化.门静脉期和延迟期7例病灶为相对低信号,1例为等信号.2例病灶见环形强化的包膜.结论 CT和MRI可显示原发性透明细胞型肝癌的特征性表现,有助于提高该病的诊断准确性.     

The dynamic magnetic resonance study of focal liver lesions by FLASH sequences with bolus intravenous gadolinium-DTPA]

Thirty-five patients with hepatic hemangioma (n = 12), metastasis (n = 10), hepatocellular carcinoma (HCC) (n = 10) and focal nodular hyperplasia (n = 3) were examined with the fast low-angle shot (FLASH) technique and an intravenous bolus injection of Gd-DTPA. In order to differentiate the lesions, the following criteria were used: a) pre Gd-DTPA intensity of lesions; b) post Gd-DTPA patterns of contrast enhancement. On the basis of these criteria, an unquestionable differential diagnosis could be made. Hemangiomas were characterized by an hypointense mass before Gd-DTPA, by peripheral contrast enhancement and by subsequent continuous hyperintense fill-in; thus, hemangiomas were visualized as hyperintense lesion during the late phase. Before contrast administration hypovascular metastases appeared as hypointense; they were characterized by delayed uptake of contrast agent. HCCs were hyperintense lesions before contrast administrations; then, quick contrast enhancement and rapid decrease in signal intensity were observed with visualization of a hyperintense ring due to the capsule. Finally, focal nodular hyperplasia appeared isointense or hypointense relative to normal liver on precontrast scans; the lesions were enhanced transiently with subsequent quick dismission of contrast agent. This initial experience suggests dynamic contrast-enhanced MR imaging as an effective method to improve the differential diagnosis among hepatic tumors when precontrast T2-weighted images are equivocal.     

Eosinophilic hepatic necrosis: magnetic resonance imaging and computed tomography comparison

OBJECTIVE: To compare the findings of magnetic resonance (MR) imaging with those of computed tomography (CT) of focal liver lesions related to peripheral eosinophilia. METHODS: For 12 patients with peripheral eosinophilia (>7%) examined with hepatic MR imaging and CT, 52 focal hepatic lesions larger than 0.5 cm, including 31 lesions simultaneously found on the 2 imaging modalities, were subjected to a comparative analysis of their imaging features. RESULTS: The total number of lesions distinguished from background liver was 39 (75%) on MR imaging and 44 (85%) on CT scans. On arterial phase images of 10 patients with comparable data, homogeneously hyperintense lesions were demonstrated more frequently (P = 0.006) on MR imaging (16 [50%] of 32 lesions) than on CT scans (4 [13%] of 32 lesions). Only 7 (22%) of the 32 hypoattenuating lesions on portal phase CT were depicted as hypointense lesions on portal phase MR images in 12 patients. On delayed phase images in 8 patients, the number of hyperintense lesions on MR images (9 [56%] of 16) was greater (P = 0.077) than that seen on the CT scans (4 [25%] of 16). CONCLUSIONS: For many focal hepatic lesions related to peripheral eosinophilia, dynamic MR imaging more easily demonstrates lesional enhancement on arterial and delayed phases than CT scans. Because of the higher degree of lesional enhancement of MR imaging compared with CT, the lesion-to-liver contrast may not be sufficient to distinguish the lesion from the background liver, resulting in decreased sensitivity of portal phase dynamic MR imaging.     

Focal nodular hyperplasia of the liver: MR findings in 35 proved cases

MR images of 28 patients with 35 lesions of hepatic focal nodular hyperplasia were reviewed to determine the frequency of findings considered typical of this condition (isointensity on T1- and T2-weighted pulse sequences, a central hyperintense scar on T2-weighted images, and homogeneous signal intensity). Fifteen lesions were imaged at 0.6 T with T1- and T2-weighted spin-echo (SE) pulse sequences; 20 lesions were imaged at 1.5 T with T1-weighted SE and gradient-echo pulse sequences and T2-weighted SE pulse sequences. Diagnosis of focal nodular hyperplasia was made pathologically in 25 patients, with nuclear scintigraphy in four, and with follow-up imaging in six. Only seven lesions (20%) were isointense relative to normal liver on both T1- and T2-weighted images. On T1-weighted SE images, 21 lesions (60%) were isointense relative to normal liver, 12 (34%) were hypointense, and two (6%) were hyperintense. On T2-weighted SE images, 12 lesions (34%) were isointense and 23 (66%) were hyperintense relative to normal liver. A central scar was present in 17 lesions (49%) and was hypointense relative to the lesion on T1-weighted images and hyperintense on T2-weighted images. Twenty lesions (57%) were of homogeneous signal intensity throughout the lesion, except for the presence of a central scar. All three MR imaging characteristics were present in three cases (9%). We conclude that hepatic focal nodular hyperplasia has a wide range of signal intensity on MR imaging.     

The value of gadobenate dimeglumine-enhanced delayed phase MR imaging for characterization of hepatocellular nodules in the cirrhotic liver

OBJECTIVES: To evaluate the value of 1-hour delayed phase imaging (DPI) of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging for the characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in patients with cirrhosis. MATERIALS AND METHODS: A total of 37 patients with 42 HCCs and 13 DNs were included in this study and all lesions were histopathologically confirmed except for 15 HCCs. T1-weighted 3-dimensional gradient-echo images were acquired before, immediately after (30, 60, 180 s), and 1 hour after bolus injection of gadobenate dimeglumine at a dose of 0.1 mmol/kg. The lesions were classified as isointense, hypointense, or hyperintense compared with the surrounding liver parenchyma on DPI for qualitative assessment. We performed quantitative analyses of the contrast-to-noise ratio (CNR) and of the relative contrast enhancement of the lesion on the DPI. RESULTS: In the qualitative analysis, among 42 HCCs, 30 (71.4%) were hypointense on DPI, and 10 (23.8%) and 2 (4.8%) were isointense and hyperintense, respectively; only 1 of 13 DNs (7.7%) was hypointense and 10 (76.9%) and 2 (15.4%) were isointense and hyperintense, respectively. In contrast, 25 HCCs (71.4%) of 35 hypervascular HCCs were hypointense on DPI, and no hypervascular DN (0/7) was hypointense with statistical significance (P = 0.0007). When we considered the hypointensity of the hepatic lesions on delayed phase as a sign of HCC in cirrhotic liver, our results gave a sensitivity of 71.4% and a specificity of 91.7%. In the quantitative analysis, the mean CNR of the HCCs and the DNs on the 1-hour DPI was -6.32 +/- 6.27 and -0.07 +/- 3.28, respectively; the difference between the HCCs and the DNs was significant (P < 0.05). CONCLUSIONS: Delayed gadobenate dimeglumine-enhanced MR imaging allows improved characterization of HCC in cirrhotic liver. The relative hypointensity to adjacent normal liver parenchyma is a reliable predictor that this lesion favors HCC rather than DN in cirrhotic liver.     

Signal characteristic and enhancement patterns of pancreatic adenocarcinoma: evaluation with dynamic gadolinium enhanced MRI

AIM: To determine the signal characteristics and enhancement patterns of proven pancreatic adenocarcinomas at 1.5 T and to compare these results with contrast enhanced computed tomography (CECT). MATERIALS AND METHODS: Twenty-five patients, mean age 73 years, with proven pancreatic adenocarcinoma were imaged at 1.5 T using in- and opposed-phase, gradient-echo (GRE), T1-weighted sequences, T2 weighting using either a short tau inversion recovery (STIR) or frequency selective, fat-suppressed turbo spin echo (TSE) sequence, and with a three-dimensional (3D), fat-suppressed, GRE T1 sequence before, during the arterial, venous, and equilibrium phases after Gadolinium administration. Fourteen of the 25 patients underwent CECT. Magnetic resonance imaging (MRI) examinations were evaluated by two observers in consensus for size, signal characteristics, and enhancement patterns, and the results were compared with CECT. RESULTS: The mean size of pancreatic adenocarcinomas was 32 mm. On unenhanced T1-weighted images, 12 of 25 lesions (48%) were hypointense, 13 (52%) were isointense. On STIR/T2, 11 of 25 (44%) pancreatic adenocarcinomas were hyperintense, 14 (56%) were isointense. All 25 (100%) adenocarcinomas were hypointense during the arterial phase. Twenty (80%) and 17 (68%) remained hypointense in the venous phase and equilibrium phases, respectively. In seven of 14 (50%) cases, the pancreatic mass was iso-attenuating to the pancreatic parenchyma during both the pancreatic and venous phases of CECT. CONCLUSION: The results of the present study showed that all 25 pancreatic adenocarcinomas were hypointense to pancreatic parenchyma during the arterial phase. Moreover, MRI may be useful in patients with a high suspicion of pancreatic carcinoma that is not visualized during CECT.     

Focal nodular hyperplasia: morphologic and functional information from MR imaging with gadobenate dimeglumine.

PURPOSE: To determine whether gadobenate dimeglumine (Gd-BOPTA) is able to provide morphologic and functional information for characterization of focal nodular hyperplasia (FNH). MATERIALS AND METHODS: Sixty-three consecutive patients with proved FNH were retrospectively examined. Magnetic resonance (MR) imaging with T2-weighted turbo spin-echo and T1-weighted gradient-echo sequences was performed. Images were acquired prior to and during the dynamic phase of contrast-material enhancement and 1-3 hours after administration of 0.1 mmol/kg Gd-BOPTA. Qualitative analysis of signal intensity and homogeneity on images in the various phases of the MR study and examination for the presence of central scar or atypical features were performed. On the basis of features observed in the precontrast and dynamic phases, lesions were defined as typical or atypical. Intensity and enhancement patterns of the lesions and scars were also evaluated in the delayed phase. RESULTS: One hundred FNHs were depicted on MR images. Seventy-nine of 100 lesions demonstrated typical morphologic and enhancement characteristics. On delayed phase images, 72% of 100 FNHs appeared hyperintense; 21%, isointense; and 7%, slightly hypointense. The delayed pattern of enhancement was homogeneous, heterogeneous, and peripheral in 58%, 22%, and 20% of 100 FNHs, respectively. Atypical morphologic features and lesion and/or scar enhancement were observed in 21 of 100 FNHs. On delayed phase images, 76% of 100 atypical FNHs appeared hyperintense, 14% isointense, and 10% slightly hypointense. Hyperintensity and isointensity allowed the correct characterization in 90% of atypical FNHs. CONCLUSION: Gd-BOPTA during both dynamic and delayed phases provides morphologic and functional information for the characterization of FNH.     

Nondysplastic nodules that are hyperintense on T1-weighted gradient-echo MR imaging: frequency in cirrhotic patients undergoing transplantation

OBJECTIVE: Our objective was to determine the frequency and MR imaging findings of nondysplastic nodules that are hyperintense on T1-weighted gradient-echo imaging in patients with cirrhosis who undergo liver transplantation. MATERIALS AND METHODS: Two observers retrospectively evaluated in-phase (4-5 msec), opposed-phase gradient-echo (2.0-2.4 msec), and turbo short tau inversion recovery (STIR) MR images in 68 patients with cirrhosis--but without dysplastic nodules or hepatocellular carcinoma--who underwent MR imaging at 1.5 T within 150 days before liver transplantation. The size, number, signal characteristics, and arterial enhancement pattern of nodules that appear hyperintense on T1-weighted gradient-echo images were evaluated as well as the presence or absence of signal loss on opposed-phase imaging. These imaging findings were correlated with pathologic findings of whole explanted livers. RESULTS: Eleven (16%) of 68 patients had at least one nondysplastic nodule that was hyperintense on T1-weighted MR imaging. Three patients had diffuse nondysplastic hyperintense nodules (>10 nodules) measuring less than 0.5 cm, and the remaining eight patients had 22 nondysplastic hyperintense nodules ranging in size from 0.5 to 2.5 cm (mean, 1.2 cm), of which 13 were isointense and nine were hypointense on turbo STIR images. No lesion lost signal on opposed-phase imaging or enhanced during the hepatic arterial phase. CONCLUSION: In cirrhotic patients undergoing liver transplantation, nondysplastic nodules that are hyperintense are common findings on T1-weighted gradient-echo MR imaging and do not lose signal intensity on opposed-phase imaging or enhance during the hepatic arterial phase. These nodules may be indistinguishable from dysplastic nodules.     

MRI诊断肝脏炎性假瘤

目的 :探讨MRI对肝脏炎性假瘤 (IPL)的诊断价值。材料和方法 :回顾性分析经病理证实的 16例IPL的MRI表现 ,并与病理所见对照。结果 :病理诊断前 13例诊断为良性病变 ,3例误诊为恶性肿瘤。T1WI低信号、T2WI高信号组 12例 :血管炎型 5例、浆细胞肉芽肿型 3例、坏死型 4例 ;T1WI和T2WI低信号组 2例 :坏死型和硬化型各 1例 ;T1WI和T2WI等信号、高信号各 1例均为血管炎型。 2例血管炎型于动脉期显著强化、门脉期和延迟期中度强化 ;3例血管炎型和 2例浆细胞肉芽肿型于动脉期轻度强化、门脉期和延迟期中度强化 ;3例坏死型于门脉期和延迟期周边轻度强化。结论 :IPL的MRI表现缺乏特异性。MRI能将多数IPL诊断为良性病变。     

Fat-suppressed dynamic and delayed gadolinium-enhanced volumetric interpolated breath-hold magnetic resonance imaging of cholangiocarcinoma

OBJECTIVE: To determine the enhancement phase providing the highest contrast-to-noise ratio (CNR) between cholangiocarcinoma and liver or portal vein on dynamic and delayed gadolinium-enhanced magnetic resonance imaging (MRI). SUBJECTS AND METHODS: Precontrast, 3-phase dynamic postcontrast, and delayed postcontrast MRI of the liver was performed in 25 patients with cholangiocarcinoma and correlated with surgical findings, pathology, and other imaging studies. Contrast-to-noise ratios for tumor relative to adjacent liver and portal vein were calculated from signal intensities determined from regions of interest obtained for each phase of enhancement. A subjective assessment of the signal intensity of the periportal tissues relative to the portal vein was made for each set of delayed images. RESULTS: A mass was visible in 24 of 25 patients. Tumor masses were hypointense in 92%, 67%, 75%, and 21%; isointense in 8%, 8%, 17%, and 12%; and hyperintense in 0%, 25%, 8%, and 67% of patients relative to liver on precontrast, arterial, portal venous, and delayed images, respectively. No single phase of gadolinium enhancement demonstrated consistently superior tumor-versus-liver CNR. Delayed imaging demonstrated the highest tumor-versus-liver CNR in 25% of patients and the lowest in 33%. The portal venous phase demonstrated the highest tumor-versus-portal vein CNR in 75% of patients. Delayed postcontrast images demonstrated the lowest tumor-versus-portal vein CNR in 38% of patients. Periportal tissues were isointense to portal vein in all but 1 patient on delayed images. CONCLUSION: No single phase of dynamic and delayed gadolinium-enhanced MRI demonstrates superior CNR between cholangiocarcinoma and normally enhancing liver, although the portal phase provides the best CNR between tumor and portal vein in most cases. Although delayed enhancement is typical of cholangiocarcinoma, delayed imaging does not necessarily offer superior contrast between tumor and liver parenchyma compared with other phases of enhancement. Differentiation between tumor and portal vein and periportal tissues may be difficult on delayed images.     

肝硬化相关小肝癌的血供特点和MRI表现

目的:通过分析肝硬化相关小肝癌的MRI平扫及增强扫描的信号特点,结合其血供情况,总结小肝癌的MRI特点,提高小肝癌的诊断水平。方法:对经临床和病理证实的48个肝硬化相关小肝癌行MRI平扫及增强扫描,对其影像学资料进行回顾性分析。结果:48个肝硬化相关小肝癌中,T1WI以稍低、低信号(68.8%)为主,T2WI以稍高、高信号(70.8%)为主,其中10例在T1WI同相位呈等或高信号,在T1WI反相位呈等或低信号影;19例可见假包膜。动态增强扫描后,强化方式有5种:无强化、边缘轻度强化、速升速降、缓升速降及速升缓降;以速升速降(35个,72.9%)为主。结论:肝硬化相关小肝癌的血供方式有5种:动脉、门脉血供均减少;动脉、门脉血供正常或略增加;动脉血供增加,门脉血供减少;门脉血供增加;动脉、门脉血供均增加。其中以动脉血供增多、门脉血供减少为主要血供方式,结合MRI信号特点,可提高早期诊断与鉴别诊断水平。     

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.     

Focal nodular hyperplasia: intraindividual comparison of dynamic gadobenate dimeglumine- and ferucarbotran-enhanced magnetic resonance imaging

PURPOSE: To intraindividually compare the enhancement pattern of focal nodular hyperplasia (FNH) after dynamic administration of two bolus-injectable liver-specific MR contrast agents, ferucarbotran and gadobenate dimeglumine. MATERIALS AND METHODS: A total of 19 patients with 24 FNHs underwent gadobenate dimeglumine- and ferucarbotran-enhanced MRI during the hepatic arterial-dominant phase (HAP; 25 seconds), the portal-venous phase (PVP; 60 seconds), and the equilibrium phase (EP; 180 seconds). Hepatospecific phases were acquired on T1-weighted images 120 minutes after gadobenate dimeglumine administration, and on T2-weighted images 10 minutes after ferucarbotran administration. Lesion enhancement was independently analyzed by two observers. The kappa statistic was determined to evaluate the agreement between the enhancement patterns of the lesions. RESULTS: On gadobenate dimeglumine-enhanced MR images during HAP, PVP, and EP, FNHs were: hyperintense (24/20/13); isointense (0/4/11); and hypointense (0/0/0). On ferucarbotran-enhanced MR images during HAP, PVP, and EP, FNHs were: hyperintense (2/0/0); isointense (16/9/14); and hypointense (6/15/10). Overall, poor agreement between both contrast agents was observed. During the hepatospecific phases, most (20/24; 83%) FNHs showed a typical enhancement pattern during the delayed hepatospecific phase. CONCLUSION: The dynamic enhancement pattern of FNHs is significantly different between gadobenate dimeglumine- and ferucarbotran-enhanced MRI. With respect to hepatospecific phase, the majority of FNHs showed a typical behavior on both contrast agents.     

Contrast-enhanced hepatic MRI: comparison of half-dose and standard-dose gadolinium DTPA administration in lesion characterization with T1-weighted gradient echo sequences

The objective of this article was to compare half-dose (0.05 mm/kg) gadolinium-enhanced dynamic hepatic MR imaging to standard doses (0.10 mm/kg). Eighteen patients for follow-up hepatic MR received 0.05 mm/kg of gadolinium DTPA dynamically with gradient-echo imaging. Imaging parameters were identical to a 0.10-mm/kg study; patients were imaged during multiple phases of contrast enhancement. Two readers assessed for enhancement patterns and characterization. Quantitative signal-to-noise ratios (S/N) were obtained for abdominal viscera and contrast-to-noise ratios (C/N) were obtained on up to three lesions. No significant difference for the arterial dominant phase (P > 0.05) was found. Significant differences were found in all categories during the portal venous phase (except pancreas) and equilibrium phase (except liver). Lesion C/N ratios were not significant at any point (P > 0.05). Sixty-two out of 64 lesions (97%) were identically characterized. Therefore, half-dose dynamic gadolinium-enhanced MR may have diagnostic value.