Differentiation Of Focal Nodular Hyperplasia Research Articles

Differentiation of focal nodular hyperplasia and hepatocellular adenoma using qualitative and quantitative imaging features and classification and regression tree analysis.

To assess qualitative and quantitative analysis of gadoxetate disodium-enhanced hepatobiliary phase MR imaging (MRI) and assess the performance of classification and regression tree analysis for the differentiation of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA). This retrospective study was approved by our local ethics committee. One hundred seventy patients suspected of having FNH or HCA underwent gadoxetate disodium-enhanced MRI. The reference standard was either pathology or follow-up imaging. Two readers reviewed images to identify qualitative imaging features and measure signal intensity on unenhanced, dynamic, and hepatobiliary phase images. For quantitative analysis, contrast enhancement ratio (CER), lesion-to-liver contrast (LLC), signal intensity ratio (SIR), and relative signal enhancement ratio (RSER) were calculated. A classification and regression tree (CART) analysis was developed. Eighty-five patients met the inclusion criteria, with a total of 97 FNHs and 43 HCAs. For qualitative analysis, the T1 signal intensity on the hepatobiliary phase provided the highest overall classification performance (91.9% sensitivity, 90.1% specificity, and 90.9% accuracy). For quantitative analysis, RSER in the hepatobiliary phase with a threshold of 0.723 provided the highest classification performance (92.6% sensitivity and 89.4% specificity) to differentiate FNHs from HCAs. A CART model based on five qualitative imaging features provided an accuracy of 94.4% (95% confidence interval 90.0-98.9%). Gadoxetate disodium-enhanced hepatobiliary phase provides high diagnostic performance as demonstrated in quantitative and qualitative analysis in differentiation of FNH and HCA, supported by a CART decision model.

Value of discrepancy of the central scar-like structure between dynamic CT and gadoxetate disodium-enhanced MRI in differentiation of focal nodular hyperplasia and hepatocellular adenoma

PurposeTo identify the value of discrepancies in the central scar (CS)-like structure between dynamic CT and gadoxetate disodium-enhanced MRI for differentiating FNH from HCA. MethodsThis retrospective study included 113 patients with pathologically-diagnosed FNH (n = 80) or HCA (n = 37). CS-like structures were evaluated on arterial phase (AP) CT and hepatobiliary phase (HBP) MRI. Presence of the CS-like structure, its discrepancy in visibility or size between AP CT and HBP MRI and between AP and HBP MRI, and features of non-scarred tumor portion were evaluated by two radiologists. Inter-observer agreement was evaluated by intraclass correlation coefficients (ICCs) and weighted kappa. Univariable and multivariable logistic regression and ROC analysis were performed to explore features differentiating FNH from HCA. ResultsInter-observer agreement was moderate-to-excellent (ICCs≥0.74, kappa≥0.65). On univariable analysis, presence of CS-like structures (P < 0.001), discrepancy of the CS-like structures between AP CT and HBP MRI (73.8 % in FNH; 16.2 % in HCA, P < 0.001) and between AP and HBP MRI (70.0 % in FNH; 16.2 % in HCA, P < 0.001), and the features of non-scarred tumor portion (P ≤ 0.011) were significantly different between FNH and HCA. On multivariable analysis, the discrepancy of CS-like structures between AP CT and HBP MRI, and the absence of low SI of the non-scarred tumor portion on HBP MRI, were suggestive of FNH (P = 0.036 and P < 0.001, respectively; area under the ROC curve, 0.96 [95 % CI, 0.93–0.99]). ConclusionEvaluation of discrepancy in the visibility or size of CS-like structures between dynamic CT and gadoxetate disodium-enhanced MRI may facilitate the differentiation of FNH from HCA.

A CT-based radiomics nomogram for differentiation of focal nodular hyperplasia from hepatocellular carcinoma in the non-cirrhotic liver

BackgroundThe purpose of this study was to develop and validate a radiomics nomogram for preoperative differentiating focal nodular hyperplasia (FNH) from hepatocellular carcinoma (HCC) in the non-cirrhotic liver.MethodsA total of 156 patients with FNH (n = 55) and HCC (n = 101) were divided into a training set (n = 119) and a validation set (n = 37). Radiomics features were extracted from triphasic contrast CT images. A radiomics signature was constructed with the least absolute shrinkage and selection operator algorithm, and a radiomics score (Rad-score) was calculated. Clinical data and CT findings were assessed to build a clinical factors model. Combined with the Rad-score and independent clinical factors, a radiomics nomogram was constructed by multivariate logistic regression analysis. Nomogram performance was assessed with respect to discrimination and clinical usefulness.ResultsFour thousand two hundred twenty-seven features were extracted and reduced to 10 features as the most important discriminators to build the radiomics signature. The radiomics signature showed good discrimination in the training set (AUC [area under the curve], 0.964; 95% confidence interval [CI], 0.934–0.995) and the validation set (AUC, 0.865; 95% CI, 0.725–1.000). Age, Hepatitis B virus infection, and enhancement pattern were the independent clinical factors. The radiomics nomogram, which incorporated the Rad-score and clinical factors, showed good discrimination in the training set (AUC, 0.979; 95% CI, 0.959–0.998) and the validation set (AUC, 0.917; 95% CI, 0.800–1.000), and showed better discrimination capability (P < 0.001) compared with the clinical factors model (AUC, 0.799; 95% CI, 0.719–0.879) in the training set. Decision curve analysis showed the nomogram outperformed the clinical factors model in terms of clinical usefulness.ConclusionsThe CT-based radiomics nomogram, a noninvasive preoperative prediction tool that incorporates the Rad-score and clinical factors, shows favorable predictive efficacy for differentiating FNH from HCC in the non-cirrhotic liver, which might facilitate clinical decision-making process.

Evaluation of texture analysis for the differential diagnosis of focal nodular hyperplasia from hepatocellular adenoma on contrast-enhanced CT images.

To explore the value of CT texture analysis (CTTA) for differentiation of focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA) on contrast-enhanced CT (CECT). This is a retrospective, IRB-approved study conducted in a single institution. A search of the medical records between 2008 and 2017 revealed 48 patients with 70 HCA and 50 patients with 62 FNH. All lesions were histologically proven and with available pre-operative CECT imaging. Hepatic arterial phase (HAP) and portal venous phase (PVP) were used for CTTA. Textural features were extracted using a commercially available research software (TexRAD). The differences between textural parameters of FNH and HCA were assessed using the Mann-Whitney U test and the AUROC were calculated. CTTA parameters showing significant difference in rank sum test were used for binary logistic regression analysis. A p value < 0.05 was considered statistically significant. On HAP images, mean, mpp, and skewness were significantly higher in FNH than in HCA on unfiltered images (p ≤ 0.007); SD, entropy, and mpp on filtered analysis (p ≤ 0.006). On PVP, mean, mpp, and skewness in FNH were significantly different from HCA (p ≤ 0.001) on unfiltered images, while entropy and kurtosis were significantly higher in FNH on filtered images (p ≤ 0.018). The multivariate logistic regression analysis indicated that the mean, mpp, and entropy of medium-level and coarse-level filtered images on HAP were independent predictors for the diagnosis of HCA and a model based on all these parameters showed the largest AUROC (0.824). Multiple explored CTTA parameters are significantly different between FNH and HCA on CECT.

Differentiation of focal nodular hyperplasia from hepatocellular adenoma: Role of the quantitative analysis of gadobenate dimeglumine-enhanced hepatobiliary phase MRI.

To determine the value of quantitative analysis of the hepatobiliary phase (HBP) in gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA). Thirty-eight patients bearing 67 lesions (40 FNH; 27 HCA) were retrospectively included in this Institutional Review Board-approved study. The same volumetric interpolated breath-hold examination (VIBE) T1 -weighted sequences were performed before and after contrast injection on a 1.5T MRI, with HBP images acquired with a mean delay of 80 minutes (range 60-120 min). After a visual assessment of lesions enhancement (qualitative HBP analysis), the HBP signal intensity ratio (SIR) and the lesion-to-liver contrast enhancement ratio (LLCER) were calculated for each lesion by two observers (Mann-Whitney test). The sensitivities, specificities (receiver operating characteristic [ROC] curve analysis) and interobserver correlation (intraclass coefficient, ICC) of quantitative HBP analysis were determined. All FNH and 44.4% of HCA appeared hyper- or isointense relative to the adjacent liver on qualitative HBP analysis. The mean SIR (P < 0.01) and LLCER (P < 0.0001) of FNH were significantly higher than that of HCA. The area under the ROC curve for the differentiation of FNH from HCA with LLCER was 0.98 for both observers. With a cutoff value of -0.3%-observer 1 with highest experience- LLCER assessment provided respective sensitivity and specificity values of 100% and 96.2% for the differentiation of FNH from HCA. The ICC was 0.7 for SIR measurements and 0.8 for LLCER measurements. Quantitative LLCER assessment allows an accurate differentiation of FNH from HCA, even in hyper- or isointense HCA on HBP images.

Focal nodular hyperplasia and hepatocellular adenoma

Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are liver lesions of hepatocellular origin. The FNH is a commonly occurring hepatic lesion whereas HCA is very rare. Non-invasive differentiation between HCA subtypes and atypical FNH may pose a diagnostic challenge as both entities predominantly occur in middle-aged female patients. The conventional imaging modalities include ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI). Distinguishing FNH from HCA is of great importance clinically as FNH is considered to be a benign lesion and needs no further management. In contrast HCA is considered to be a borderline tumor due to the risk of hemorrhage, growth and even malignant transformation and requires individualized management. The above mentioned radiological procedures usually enable an accurate and certain diagnosis of a typical FNH to be achieved. In cases of atypical FNH, particularly in patients with a clinical history of malignancy, these imaging modalities are insufficient to establish a clear diagnosis. In this scenario, the use of modern hepatobiliary contrast-enhanced MRI will enable a differentiation between FNH and metastasis with a high sensitivity and specificity. Furthermore, it allows a differentiation of FNH from 90 % of adenoma subtypes. This article describes the histopathological and radiological features of these lesions and explains the advantages and limitations of various imaging modalities used for the diagnosis and differentiation of these entities. The new classification of HCAs according to phenotype and genotype and their imaging features, as well as different enhancement patterns, are described. The correlation between HCA subtypes and their individual management are also discussed.

MRI with hepatobiliary contrast

Hepatobiliary contrast agents currently are essentially gadolinium based agents (Gd-EOB-DTPA and Gd-BOPTA) with dual ability to perform dynamic contrast enhanced imaging similar to extracellular gadolinium contrast as well as providing hepatobiliary uptake and excretion in later phases. Hepatobiliary uptake and excretion with gadoxetic acid (Gd-EOB-DTPA) is related to OATP and cMOAT and MRP2 receptors presence on hepatocytes. Since gadoxetic acid has a recommended dose which is 25 %( 0.025mmol/kg) of Gd-DTPA attention to technical parameters is crucial. Improved arterial phase enhancement is obtained by MR fluoroscopic or bolus-tracking type triggering technique and either a lower injection flow rate of 1 mL/s or less as opposed to 2 mL/s, or contrast dilution. To improve liver-lesion contrast-to-noise ratio, 3D T1-weighted gradient-echo acquisition for the hepatobiliary phase should be performed with higher flip angles (20-35°). In order to optimize workflow, Diffusion-weighted and T2-weighted imaging can be performed after gadoxetic acid administration without compromising diagnostic capability; however, MRCP pulse sequences should be acquired before the contrast injection. The clinical utilization of Hepatobiliary contrast agents is predominantly for staging of liver metastases, characterization of hepatocellular lesions such as adenoma and FNH as well as diagnosis of HCC and cirrhosis related nodules. In the preoperative setting for accurate evaluation of colorectal liver metastases and appropriate surgical planning, gadoxetic acid-enhanced liver MRI is recommended because it has superior sensitivity and specificity compared to ultrasound, PET, and CT. In the assessment of patients with colorectal liver metastases who have been treated with chemotherapy, preoperative imaging with gadoxetic acid may be of particular benefit. For the differentiation of focal nodular hyperplasia from hepatic adenoma, gadoxetic acid-enhanced MRI should be considered due to its discriminative ability between the two based on hepatobiliary phase features. The combination of hypointensity on hepatobiliary phase images and mild-to-moderate arterial enhancement for adenoma versus strong enhancement on arterial phase images and iso- or hyperintensity on hepatobiliary phase images for FNH showed sensitivity and specificity of 83.7% and 100% and 83.8% and 98.5%, respectively. However a small percentage of adenomas can exhibit hepatobiliary uptake and surveillance and or biopsy should be considered when imaging appearances are not typical. Although gadoxetic acid-enhanced MRI yields significantly higher diagnostic accuracy and sensitivity compared with multiphasic CT for the diagnosis of HCC in cirrhosis, its role in the clinical management of HCC has yet to be defined in North America while it has seen widespread implementation in Asia/Japan. There is insufficient evidence supporting cost-effectiveness or outcomes for recommending the utilization of gadoxetic acid-enhanced MRI for HCC screening at this time. A significant percentage of nodules with hepatobiliary phase hypoenhancement but atypical enhancement on the dynamic phases have been associated with a diagnosis of HCC or future development of HCC. Biopsy or close surveillance of these lesions is recommended. Off label applications include evaluation of biliary disorders, bile leaks and hepatic function. Gadoxetic acid-enhanced liver MRI is an evolving technique with potential for non-invasive quantification of liver function and staging of hepatic fibrosis.

Differentiation of focal nodular hyperplasia from hepatocellular adenomas with low-mechanical-index contrast-enhanced sonography (CEUS): effect of size on diagnostic confidence.

The purpose of this study was to assess the diagnostic performance of contrast-enhanced sonography (CEUS) for the differentiation of focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA) according to lesion size. Forty patients with a definite diagnosis of FNH or HCA who underwent CEUS were included in this institutional review board (IRB)-approved study. A total of 43 FNHs and 20 HCAs, including 15 inflammatory HCAs and five unclassified HCAs, were analysed. Two radiologists reviewed the diagnostic CEUS parameters separately and in consensus, including the presence or absence of centrifugal filling and central vessels. The sensitivity (Se), specificity (Sp), and inter-observer confidence (Kappa) of CEUS diagnostic parameters were assessed. Inter-observer agreement of CEUS for FNH diagnosis was high (kappa = 0.81) with an overall Se of 67.4% [29/43 (CI 95%: 51.4-80.1 %)] and an Sp of 100% [20/20 (CI 95%: 81-100%)]. Significantly higher Se figures were found for lesions ≤ 35 mm than for lesions > 35 mm [respectively, 93 % (28/30) (CI 95%: 77.6-99.2) vs. 7.7% (1/13) (CI 95%: 0.2-36%), p = 0.002] with unchanged specificity. CEUS is highly specific for the diagnosis of FNH, with very good inter-observer agreement, whatever the size, but its sensitivity is significantly reduced in diagnosing lesions larger than 35 mm. • CEUS is highly specific for the diagnosis of FNH, regardless of lesion size • CEUS shows reduced sensitivity in diagnosing FNH lesions larger than 35 mm • The filling patterns of hepatocellular adenomas are not affected by lesion size.

Adenoma or Atypical Hepatic Focal Nodular Hyperplasia: Role of Preoperative Imaging and Laparoscopic Treatment

Differentiation of focal nodular hyperplasia (FNH) and other hypervascular liver lesions, such as hepatocellular adenoma (HCA), is important because of the drastically different therapeutic approach. However, FNH can be well distinguished only if it shows a typical aspect; alternatively, in the case of atypical FNH, imaging findings are not specific enough to provide a secure diagnosis and histologic verification of the lesion is required. In addition, HCA cannot be identified conclusively by any current available imaging technique and it can be at best suspected strongly, and this suspicion may lead to liver resection. Herein we report a case of a patient with an unusual FNH nodule presenting at ultrasonographic scanning as an isoechoic mass arising from hepatic segment 4b; the diagnostic indecision between FNH and HCA was not definitively solved even after computed tomography scan and magnetic resonance imaging and the patient was scheduled for a laparoscopic resection. The pathologic examination diagnosed an atypical FNH nodule. The clinical doubt between FNH and HCA remains a problem affecting the clinicians, and more effort should be made in the direction of a better preoperative differentiation of such different conditions. Surgical resection should not be considered as the failure of the preoperative diagnostic attempt, but as the mainstay for a definitive and sure diagnosis.

Contrast-enhanced ultrasound in the detection and characterization of liver tumors.

Contrast-enhanced ultrasound (CEUS) has unique advantages over contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) in the characterization of hepatic tumors. These include the capability of real-time dynamic imaging depicting the enhancement pattern of tumors regardless of its rapidity, purely intravascular properties of the microbubble contrast agents more consistently demonstrating washout of malignancy, and capability of repetitive observation of tumor vascularity with multiple injections of microbubbles with an excellent safety profile and no nephrotoxicity. For an indeterminate mass detected on an ultrasound scan, an immediate benign diagnosis reduces the necessity of costly further imaging as well as patients’ anxiety and an immediate malignant diagnosis prompts the proper work-up and management. CEUS is often served as a problem-solving tool for indeterminate lesions on prior CT or MRI scans, obviating further invasive steps. CEUS offers excellent visualization of peripheral nodular enhancement in even flash-filling or very slow-filling hemangiomas. Careful observation of early arterial filling pattern is helpful in the differentiation of focal nodular hyperplasia versus adenoma. Hepatocellular carcinoma is typically characterized by arterial hypervascularity and often late, partial washout. Metastasis shows brief arterial hypervascularity and complete rapid washout, which can improve its detection during a portal phase survey. The washout phenomenon of malignant tumors in general is useful to differentiate them from benign lesions.

Research on focal nodular hyperplasia with MSCT and postprocessing

To investigate and evaluate the pathological features and diagnostic value of focal nodular hyperplasia (FNH) with multi-section spiral computed tomography (MSCT) and postprocessing. A total of 25 patients with FNH who had undergone MSCT and postprocessing were included in the investigation. All patients had been pathologically or clinically confirmed with FNH. A number of 75 cases of hepatic carcinomas, hemangiomas and adenomas were randomly selected at a same period for a comparative study. There was a single focus in 22 cases and multiple foci in 3 cases. On the plain scan, 17 lesions showed hypodensity, 7 isodensity and 4 hyperdensity (the case with fatty liver). With contrast, 28 lesions were enhanced evenly or in the nodules in the arterial phase; 13 lesions still showed hyperdensity, 11 lesions isodensity and 4 lesions hypodensity in the parenchymatous phase; in the delayed phase only 5 lesions showed hyperdensity but 9 lesions showed isodensity or slight hypodensity and 14 lesions showed hypodensity. Twelve lesions of 28 had central asteroid scars. Thickened feeding arteries in postprocessing were seen in 24 lesions, and were integrated into the parenchymatous lesions with a gradual and smooth course. On the contrary, there were no artery penetrated into the lesion found in any of comparative hepatic tumors. Doctors could make a correct diagnosis and differentiation of FNH on evaluation of the characteristic appearance on MSCT with postprocessing.

2287: Differentiation of focal nodular hyperplasia and hepatic adenoma with microbubble-enhanced low-MI contrast-enhanced ultrasound—work in progress

2287: Differentiation of focal nodular hyperplasia and hepatic adenoma with microbubble-enhanced low-MI contrast-enhanced ultrasound—work in progress

Differential Diagnosis of Focal Nodular Hyperplasia With Quantitative Parametric Analysis in Contrast-Enhanced Sonography

We investigated the potential of quantitative parametric analysis in the differential diagnosis of focal nodular hyperplasia (FNH) from other hypervascularized liver focal lesions. Eighty-five focal liver lesions (in 83 patients) were explored using contrast-enhanced ultrasound (SonoVue and Cadence Contrast Pulse Sequencing) consisting of typical FNH (n=52), hepatocellular carcinoma (n=11), hemangioma with high flow (n=8), hypervascular metastases (n=10), and hepatocellular adenoma (n=4). QontraXt software (AMID, Italy) was used here to estimate the following parameters: maximum peak value, Tr (time corresponding to time for obtaining 63% of the plateau), beta parameter corresponding to the exponential factor, and slope corresponding to the tangent value of the first phase of enhancement. These parameters were obtained from the time-intensity curves derived from the enhancement observed in 2 regions of interest corresponding, respectively, to the whole lesion and the central region only. A significant statistical difference (P<0.05) was found in the values of Tr, beta, and slope between FNH and other hypervascularized lesions on both the whole lesion and central region. Among these parameters, slope appeared as the most valuable whatever the region of interest, ie, central or whole lesion (P<0.01). Central region was more accurate in the differentiation of FNH and concordant with visual characterization. Quantitative parametric curve analysis of the different hypervascularized lesions confirms the depiction of the central artery in FNH and thus could help in differentiating this specific focal liver lesion from the others.

Differentiation of focal nodular hyperplasia and hepatocellular adenoma by contrast-enhanced ultrasound

Non-invasive differentiation of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) is difficult. The aim of this study was to assess the accuracy of contrast-enhanced phase inversion ultrasound to differentiate between histologically proven FNH and HCA, analysing the arterial and (early) portal venous phase. 32 patients with histological proven FNH (n=24) or HCA (n=8) have been included in this prospective study. Examination technique: Siemens Elegra, phase inversion harmonic imaging (PIHI) with low mechanical index (MI)<0.2-0.3 using SonoVue (BR 1). The contrast enhancing tumour characteristics were evaluated during the hepatic arterial (starting 8-22 s) and early portal venous phase (starting 12-30 s). The image analysis was performed by three examiners. In 23 of 24 patients with FNH the contrast pattern revealed pronounced arterial and (early) portal venous enhancement. Homogeneous enhancement was detected during the hepatic arterial phase in all eight patients with HCA. In contrast to patients with FNH, no enhancement was seen during the portal venous phase. In conclusion, contrast-enhanced phase inversion ultrasound demonstrated pronounced arterial and portal venous enhancement in patients with focal nodular hyperplasia. In contrast, after homogeneous enhancement during hepatic arterial phase, no enhancement during hepatic portal venous phase was detected in patients with hepatocellular adenoma. Therefore, this technique might improve the functional characterization of benign hypervascular focal liver lesions.

Accurate Differentiation of Focal Nodular Hyperplasia from Hepatic Adenoma at Gadobenate Dimeglumine–enhanced MR Imaging: Prospective Study

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. 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. 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. Accurate differentiation of FNH from HA and LA is achievable on delayed T1-weighted GRE images after administration of gadobenate dimeglumine.

Characterization of focal hepatic lesions with ferumoxides-enhanced T2-weighted MR imaging.

The purpose of this study was to evaluate whether ferumoxides-enhanced MR imaging of focal hepatic lesions provides distinctive signal intensity and lesion-to-liver contrast changes for benign and malignant lesions, helping to further characterize and differentiate these lesions. Data analysis was performed on 70 patients, with previously identified focal hepatic lesions, who underwent MR imaging of the liver before and after IV administration of ferumoxides (10 micromol Fe/kg). Lesions analyzed with pathologically proven diagnoses included metastases (n = 40), hepatocellular carcinoma (n = 11), cholangiocarcinoma (n = 6), hemangioma (n = 4), focal nodular hyperplasia (n = 6), and hepatocellular adenoma (n = 3). Response variables measured and statistically compared included the percentage of signal-intensity change and lesion-to-liver contrast. Focal nodular hyperplasia showed significant signal intensity loss on ferumoxides-enhanced T2-weighted images (mean, -43%+/-6.7%, p < 0.01). All other lesion groups showed no statistically significant change in signal intensity on ferumoxides-enhanced T2-weighted images, although signal intensity loss was seen in some individual hepatocellular adenomas (mean, -6.6%+/-24.0%) and hepatocellular carcinomas (mean, -3.3%+/-10.3%). All lesions, with the exception of hepatocellular carcinoma, had a marked increase in lesion-to-liver contrast on ferumoxides-enhanced T2-weighted images, which was statistically significant for metastases and hemangioma (p < 0.02). Focal nodular hyperplasia shows significant decrease in signal intensity on ferumoxides-enhanced T2-weighted images, which may aid in the differentiation of focal nodular hyperplasia from other focal hepatic lesions. Other lesions, namely, hepatocellular adenoma and carcinoma, can have reticuloendothelial uptake, but usually to a lesser degree than that of focal nodular hyperplasia.

Hypervascular liver lesions: differentiation of focal nodular hyperplasia from malignant tumors with dynamic gadolinium-enhanced MR imaging.

The differentiating points between focal nodular hyperplasia (FNH) and malignant hypervascular liver lesions were studied at dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Thirty-six patients with 50 hypervascular lesions (28 FNH, 12 hepatocellular carcinoma, nine metastases, and one cholangiocarcinoma) underwent unenhanced spin-echo (SE) T1- and T2-weighted imaging and T1-weighted gradient-recalled-echo imaging before and repeatedly for 10 minutes after intravenous bolus injection of gadopentetate dimeglumine. On unenhanced SE images, the signal intensity of 25 FNH lesions (89%) and 10 malignant tumors (45%) was homogeneous. A central scar was detected in 12 FNH lesions (43%) and in none of the malignant tumors. On dynamic gadolinium-enhanced images, all lesions had early vigorous enhancement that was homogeneous in 27 FNH lesions (96%) and in seven malignant tumors (32%) (P < .001). After administration of gadopentetate dimeglumine, central scars were seen in 22 FNH lesions (79%) and in one malignant tumor (4%) (P < .001). All FNH lesions (100%) and six malignant tumors (27%) had well-defined enhancement (P < .001). There was overlap in the enhancement pattern between hypervascular malignant lesions and FNH, but by using the combination of unenhanced and enhanced images, they could be distinguished.

Hepatic focal nodular hyperplasia: specific findings at dynamic contrast-enhanced US with carbon dioxide microbubbles.

Dynamic contrast material-enhanced ultrasonography (US) with intraarterial infusion of carbon dioxide microbubbles was performed for four cases of histologically proved focal nodular hyperplasia (FNH) in four patients and for 167 cases of various hepatic nodules in 144 patients. No complications due to dynamic US were observed in any of the 148 patients. All FNH nodules were less than 3 cm in diameter. Consistent specific findings of FNH were not obtained with US, computed tomography, magnetic resonance imaging, radiocolloid scanning, or angiography in the four cases of FNH. In contrast, the characteristic vascular pattern (ie, early central hypervascular supply with centrifugal filling to the periphery at the arterial phase and a uniform or lobulated dense stain at the capillary phase) was observed in all four cases of FNH with dynamic US. This vascular pattern demonstrated in FNH with dynamic US was not seen in any of the 167 hepatic nodules, including 44 small hepatocellular carcinomas less than 3 cm in diameter. Therefore, the newly developed, dynamic contrast-enhanced US technique seems to be extremely sensitive and specific for diagnosing FNH and is useful in the differentiation of FNH from other hepatic tumors, especially hepatocellular carcinoma.

Hepatic Cell Adenomas

To the Editor .—The article by Ameriks et al, Hepatic Cell Adenomas, Spontaneous Liver Rupture, and Oral Contraceptives ( Arch Surg 110:548, 1975), summarizes the recent reports of tumors and their possible association with oral contraceptives. However, we believe it necessary to point out several inconsistencies requiring clarification. First, the title is misleading as it implies that all of their patients had hepatic cell complicated by spontaneous liver rupture; in fact, only half of their cases (cases 4, 6, 7, and 8) had this complication. Second, we disagree that histopathologic differentiation of focal nodular hyperplasia (FNH) from liver cell adenoma is often impossible. By definition, liver cell adenomas lack a substructure and FNH characteristically shows a central stellate scar with proliferating intranodular and internodular bile ductules. 1,2 That the authors do not appreciate these histopathologic criteria is evidenced by several of their remarks: (1) both adenomas and FNH may