Sparing of Fatty Infiltration Around Focal Hepatic Lesions in Patients with Hepatic Steatosis: Sonographic Appearance with CT and MRI Correlation

Role of textural analysis parameters derived from FDG PET/CT in differentiating hepatocellular carcinoma and hepatic metastases

INTRODUCTION

Texture and radiomic analysis characterize the tumor's phenotype and evaluate its microenvironment in quantitative terms. The aim of this study was to investigate the role of textural features of 18F-FDG PET/computed tomography (CT) images in differentiating hepatocellular carcinoma (HCC) and hepatic metastasis in patients with suspected liver tumors.

METHODS

This is a retrospective, single-center study of 30 patients who underwent FDG PET/CT for the characterization of liver lesions or for staging a suspected liver tumor. The histological diagnosis of either primary or metastatic tumor was obtained from CT-guided biopsy, ultrasound-guided biopsy, or surgical removal of a liver lesion. The PET/CT images were then processed in commercially available textural analysis software. Region of interest was drawn over the primary tumor with a 40% threshold and was processed further to derive 42 textural and radiomic parameters. These parameters were then compared between HCC group and hepatic metastases group. Receiver-operating characteristic (ROC) curves were used to identify cutoff values for textural features with a P value <0.05 for statistical significance.

RESULTS

A retrospective study of 30 patients with suspected liver tumors was done. After undergoing PET/CT, the histological diagnosis of these lesions was confirmed. Among these 30 patients, 15 patients had HCC, and 15 patients had hepatic metastases from various primary sites. Seven textural analysis parameters were significant in differentiating HCC from liver metastasis. Cutoff values were calculated for these parameters according to the ROC curves, standardized uptake value (SUV) Skewness (0.705), SUV Kurtosis (3.65), SUV Excess Kurtosis (0.653), gray-level zone length matrix_long zone emphasis (349.2), gray-level zone length matrix_long zone low gray-level emphasis (1.6), gray-level run length matrix_long run emphasis (1.38) and gray-level co-occurrence matrix_Homogeneity (0.406).

CONCLUSION

Textural analysis parameters could successfully differentiate HCC and hepatic metastasis non-invasively. Larger multi-center studies are needed for better clinical prognostication of these parameters.

A flexible three‐dimensional heterophase computed tomography hepatocellular carcinoma detection algorithm for generalizable and practical screening

Hepatocellular carcinoma (HCC) can be potentially discovered from abdominal computed tomography (CT) studies under varied clinical scenarios (e.g., fully dynamic contrast‐enhanced [DCE] studies, noncontrast [NC] plus venous phase [VP] abdominal studies, or NC‐only studies). Each scenario presents its own clinical challenges that could benefit from computer‐aided detection (CADe) tools. We investigate whether a single CADe model can be made flexible enough to handle different contrast protocols and whether this flexibility imparts performance gains. We developed a flexible three‐dimensional deep algorithm, called heterophase volumetric detection (HPVD), that can accept any combination of contrast‐phase inputs with adjustable sensitivity depending on the clinical purpose. We trained HPVD on 771 DCE CT scans to detect HCCs and evaluated it on 164 positives and 206 controls. We compared performance against six clinical readers, including two radiologists, two hepatopancreaticobiliary surgeons, and two hepatologists. The area under the curve of the localization receiver operating characteristic for NC‐only, NC plus VP, and full DCE CT yielded 0.71 (95% confidence interval [CI], 0.64–0.77), 0.81 (95% CI, 0.75–0.87), and 0.89 (95% CI, 0.84–0.93), respectively. At a high‐sensitivity operating point of 80% on DCE CT, HPVD achieved 97% specificity, which is comparable to measured physician performance. We also demonstrated performance improvements over more typical and less flexible nonheterophase detectors. Conclusion: A single deep‐learning algorithm can be effectively applied to diverse HCC detection clinical scenarios, indicating that HPVD could serve as a useful clinical aid for at‐risk and opportunistic HCC surveillance.

Imaging of hepatic hemangioma: from A to Z

The hemangioma is the most common solid lesion of the liver. Therefore, radiologists must know the typical and atypical imaging findings of this lesion in order to reach a correct diagnosis and avoid diagnostic errors. However, only few papers have comprehensively described the entire spectrum of atypical and uncommon imaging features. In this updated review, we provide the imaging features of hepatic hemangioma, in both typical and atypical forms, as well as its association with abnormalities in the adjacent hepatic parenchyma and other hepatic lesions, and its complications.

Quantification of degree of steatosis in extended criteria donor grafts with standardized histologic techniques: implications for graft survival

The gap between the availability of livers from organ donors and the increased demand has led many centers to apply strategies to reduce this deficit. Splitting of cadaveric organs for use in 2 recipients; domino transplantation; and organs from living donors, non-heart-beating donors, and extended-criteria donors (ECDs) are all currently used in orthotopic liver transplantation (OLT). Fatty changes in the donor liver are a risk factor for poor function after OLT; however, the presence of steatosis, frequently present in livers from ECDs, does not exclude the use of these organs. Since January 2000 at our institution, we observed 39 steatotic grafts that were stratified istologically as follows: low steatosis, 5% to 15%; mild steatosis, 16% to 30%; moderate steatosis, 31% to 60%; and severe steatosis (>60%). Histologic techniques can enable identification of the type of fatty change as macrovesicular and microvesicular. These alterations have different effects on primary nonfunction and primary dysfunction. Fifteen grafts, all with severe or moderate, macrovesicular changes were discarded. Twenty-four fatty grafts with low to moderate steatosis were utilized for transplant. Sections from 2 liver biopsies (1 wedge in the left lobe and 1 needle in the right lobe) were stained with hematoxylin-eosin, Masson trichrome, Gomori reticulin, and oil red O. The OLT was performed only in patients with a MELD (Model for End-Stage Liver Disease) score lower than 27. The rate of primary dysfunction was 12.5%, and of primary nonfunction 8.4%. The 6-month graft survival for all fatty livers was 80%. We encourage the careful use of grafts with low to moderate steatosis in recipients without additional risks.

Characteristics suggestive of focal Fatty sparing from liver malignancy on ultrasound in liver screening

OBJECTIVE

The objective of this study was to determine whether there are ultrasound characteristics that can be used to differentiate focal fatty sparing (FFS) from hepatocellular carcinoma and other liver malignancies in liver screening.

METHODS

Data of patients with FFS found at ultrasound were reviewed, 136 patients with FFS were included, and 112 patients with hepatocellular carcinoma and 65 patients with liver metastatic tumor (173 tumors) were selected as control group. Ultrasound and color Doppler characteristics of FFS and liver malignancies were studied. Some characteristics drawn from this study were used as reference to validate the liver malignancies and FFS, and sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

Hyperechogenicity, isoechogenicity, heterogeneous echotexture, posterior acoustic shadowing, halo, hypervasculature presented exclusively in liver malignancies, posterior acoustic enhancement presented predominantly in liver malignancies, irregularly shaped morphology presented exclusively in FFS, arterial velocity, and maximal size of liver malignancies were significantly higher than those of FFS (P < 0.001). Halo presented in 109 of 285 liver malignancies (38.2%), but was absent in FFS (P < 0.001). The overall sensitivity, specificity, and positive and negative predictive values were 94.38%, 90.44%, and 95.39% and 88.49%, respectively.

CONCLUSIONS

Combination of hyperechogenicity, isoechogenicity, heterogeneous echotexture, posterior acoustic shadowing, posterior acoustic enhancement, halo appearance, and hypervascularity with high-speed artery has high sensitivity, specificity, and positive and negative predictive values for distinguishing liver malignancy and FFS.

Evaluation of hemodynamics in focal steatosis and focal spared lesion of the liver using contrast-enhanced ultrasonography with sonazoid

We aim to investigate the hemodynamics in focal steatosis and focal spared lesion of the liver using contrast-enhanced ultrasonography (CEUS) with Sonazoid. The subjects were 47 patients with focal steatosis and focal spared lesion. We evaluated enhancement patterns (hyperenhancement, isoenhancement, and hypoenhancement) in the vascular phase and the presence or absence of a hypoechoic area in the postvascular phase for these lesions using CEUS. Of the 24 patients with focal steatosis, the enhancement pattern was isoenhancement in 19 and hypoenhancement in 5. Hypoechoic areas were noted in the postvascular phase in 3 patients. Of the 23 patients with focal spared lesions, the enhancement pattern was isoenhancement in 18 and hyperenhancement in 5. No hypoechoic areas were noted in the postvascular phase in any patient. The hemodynamics in focal steatosis and focal spared lesions in nondiffuse fatty liver can be observed using low-invasive procedures in real-time by CEUS. It was suggested that differences in the dynamics of enhancement in the vascular phase of CEUS were influenced by the fat deposits in the target lesion, the surrounding liver parenchyma, and the third inflow.

Focal fatty sparing usually does not arise in preexisting nonalcoholic diffuse homogeneous fatty liver

OBJECTIVES

The purpose of this study was to investigate whether focal fatty sparing can arise in preexisting nonalcoholic diffuse homogeneous fatty liver and its clinical implications.

METHODS

This prospective study consisted of 2 parts. In the first part, 8598 people (5202 men and 3396 women; mean age ± SD, 43.4 ± 28.3 years; range, 18-82 years) were consecutively evaluated with sonography for abnormal liver findings; in the second part, participants with diffuse homogeneous fatty liver were followed over approximately 3 years. Sonographic findings of the participants in the first year and findings of the participants with diffuse homogeneous fatty liver in the first and third years were analyzed.

RESULTS

In the first part, 778 of 8598 participants (9.05%) were found to have fatty liver, including 752 cases of nonalcoholic diffuse fatty liver (8.75%) and 26 cases of alcoholic fatty liver (0.30%). Of the 752 cases of nonalcoholic diffuse fatty liver, 301 participants had nonalcoholic diffuse homogeneous fatty liver, and 68 (9.04%) had focal fatty sparing. In the second part, the 301 participants with nonalcoholic diffuse homogeneous fatty liver (205 men and 96 women; mean age, 39.6 ± 10.4 years; range, 18-60 years) were followed. In the third year, 2 cases of fatty liver (0.67%) had resolved, 2 cases (0.67%) had inflammatory pseudotumors, and no focal fatty sparing was found (P < .001).

CONCLUSIONS

The findings of this study suggest that focal fatty sparing usually does not arise in preexisting nonalcoholic diffuse homogeneous fatty liver, and a newly emerging abnormality is more likely a true lesion.

Comparison of contrast-enhanced ultrasonography with grey-scale ultrasonography and contrast-enhanced computed tomography in diagnosing focal fatty liver infiltrations and focal fatty sparing

PURPOSE

Fatty liver infiltrations and fatty sparing impair diagnostic performance of grey-scale ultrasonography in differentiating malignant and benign focal liver lesions. In the study, we present our experience in diagnosing focal fatty liver infiltrations and focal fatty sparing with contrastenhanced ultrasonography (CEUS) in comparison to grey-scale ultrasonography and contrast-enhanced computed tomography (CECT).

MATERIAL AND METHOD

The retrospective study group (n=82 patients), included 44 (53.7%) men, 38 (46.3%) women (aged 29- 81 years, mean 55.8 years) with 48 focal fatty liver infiltrations and 34 focal fatty sparing. All patients underwent grey-scale ultrasonography (US), CEUS using SonoVue® and CECT executed within the 7 days.

RESULTS

With US, CEUS and CECT focal fatty liver infiltrations were diagnosed in 22, 46 and 44 cases, respectively. The following values were obtained: sensitivity - 45.8%, 95.8% and 91.7%, specificity - 100% for all, accuracy - 95.2%, 99.6% and 99.3%, respectively. Focal fatty sparing was diagnosed in 16, 31 and 30 cases, respectively. The following values were obtained: sensitivity - 47.1%, 91.2% and 88.2%, specificity - 99.8%, 100% and 100%, accuracy - 95.6%, 99.4% and 99.3%, respectively. No statistically significant differences were found in sensitivity of diagnosing focal fatty liver infiltrations and focal fatty liver sparing between CEUS and CECT. Sensitivity of grey-scale ultrasonography was significantly lower when compared to those of CEUS and CECT (p<0.001).

CONCLUSION

CEUS is as sensitive as CECT in focal fatty infiltrations and focal fatty sparing diagnosing. However, CEUS provides more information than CECT about the vasculature and enhancement pattern of focal fatty liver infiltrations.

Dynamic changes in ultrasound characteristics of nodules in cirrhotic liver and their implications in surveillance for malignancy

OBJECTIVE

To investigate whether there are ultrasound characteristics that can suggest HCC in ultrasound surveillance of nodules in cirrhotic liver.

METHODS

Data from 277 patients with hepatitis B virus-related nodules in cirrhotic liver undergoing ultrasound surveillance of the nodules for malignancy were reviewed. Size of the nodules ranged 6-23 mm. The nodules were followed by color Doppler ultrasound at 3- to 6-month intervals, with focus on size, shape, echogenicity, margin, halo sign, and vasculature. Suspicious malignant nodules underwent contrast-enhanced CT/MRI, and some indeterminate nodules underwent biopsy.

RESULTS

Nodules in 189 patients were hypo/isoechoic/faint high echoic, 23 were hyperechoic, and 65 were both hypo/isoechoic/faint high echoic and hyperechoic. Forty-two patients developed hepatocellular carcinoma: 35 from nodules and 7 from background parenchyma. Fourteen nodules recessed (size >10 mm), 11 new nodules emerged (size >10 mm), and the total number of nodules increased over 5 years. All hepatocellular carcinomas developed from hypo/isoechoic/faint high echoic nodules, and no typical hyperechoic nodules developed into hepatocellular carcinomas. The size increased significantly when the nodules developed into hepatocellular carcinomas. No nodule presented an overt halo, seven hepatocellular carcinomas developed from nodules with a halo, and ill-defined margins of 16 nodules became well defined when they developed into hepatocellular carcinomas. No vasculature was detectable in the nodules, while it was detectable in eight hepatocellular carcinomas. No significant change occurred in nodules without malignancy.

CONCLUSION

The characteristics for dynamic surveillance of nodules in cirrhotic liver for malignancy should include nodule growth, margin, halo, and vasculature. Apart from evident growth, an ill-defined margin becoming a well-defined margin, a newly emerged halo, and newly detectable vasculature are strongly suggestive of nodule malignancy.

Hepatic haemangioma: common and uncommon imaging features

The haemangioma, the most common non-cystic hepatic lesion, most often discovered by chance, may in certain situations raise diagnostic problems in imaging. In this article, the authors first demonstrate that the radiological appearance of the hepatic haemangioma, in its typical form, is closely related to three known histological sub-types. They then show that certain atypical features should be known in order to establish a diagnosis. They also observe the potential interactions between the haemangioma, an active vascular lesion, and the adjacent hepatic parenchyma. Finally, they discuss the specific paediatric features of hepatic haemangiomas and illustrate the case of a hepatic angiosarcoma.

Sonographic characterization of 271 hepatic hemangiomas with typical appearance on CT imaging

PURPOSE

Hepatic hemangioma is the most frequent benign solid tumor that requires differentiation from hepatic malignancy on ultrasonography. Useful ultrasound findings are therefore required for diagnosis.

SUBJECTS AND METHODS

The following factors were investigated for 271 masses diagnosed as hepatic hemangioma by contrast-enhanced computed tomography (CT) in 188 patients: hepatic subsegment location, shape, maximum diameter, internal echo level, hyperechoic rim, posterior echoes, marginal hypoechoic band (halo), lateral shadow, blood flow signal in the central portion of the mass, and underlying liver disease.

RESULTS

Hepatic masses were classified by internal echo pattern as homogeneous hyperechoic (35.0%), homogeneous hypoechoic (22.9%), isoechoic (5.2%), mixed hyperechoic (22.1%), or mixed hypoechoic (14.8%) masses. Twelve masses were isoechoic, and could be recognized by the hyperechoic rim. Posterior echo enhancement was present in 66 masses. There were no cases of posterior echo attenuation. A halo was present in six masses, with the underlying condition being fatty infiltrated liver in two masses; a hypoechoic region with a small amount of fat deposit was present around the mass, and this resembled a halo. This finding was termed a "pseudohalo." There were no masses in which a lateral shadow was observed. In terms of blood flow signals in the central portion of the mass, pulsatile flow was present in only one mass.

CONCLUSIONS

Important ultrasonographic findings of hepatic hemangioma are characterized as the absence of lateral shadow (100%) and no attenuation of posterior echoes (100%), while the presence of a hyperechoic rim is useful for detecting isoechoic hemangioma.

Successful use of extended criteria donor grafts with low to moderate steatosis in patients with model for end-stage liver disease scores below 27

Liver transplantation may be performed using extended criteria donor grafts (ECDg). The characteristics of ECDg include age >60 years, long intensive care unit (ICU) stay, history of malignancy or steatosis. Grafts are often discarded due to steatosis, which can be macrovesicular (MaS) or microvesicular (MiS). MaS is the variety most frequently involved with unfavorable outcomes due to primary nonfunction (PNF) or primary dysfunction (PDF). As of January 2000, all livers referred to our institution were considered potentially transplantable. Steatosis was defined as the presence of fat droplets in more than 5% of hepatocytes. We observed 35 steatotic grafts. Grafts were stratified according to MaS and MiS as follows: low steatosis (5%-15%), mild steatosis (16%-30%), moderate steatosis (31%-60%), or severe steatosis (>60%). Fifteen grafts with moderate (n = 2) or severe (n = 13) MaS were discarded. Twenty grafts were harvested: 18 of them were transplanted at our institution, the remaining 2, discarded by our donor team, were transplanted by other Italian centers. Low MaS was detected in 10 grafts (50%), mild MaS in 4 (20%), and moderate MaS in 2 (10%). Low MiS was detected in 8 grafts (40%), mild MiS in 5 (25%), and moderate MiS in 1 (5%). Steatotic grafts were transplanted only into recipients with model for end-stage liver disease (MELD) scores <27. The 6-month graft survival was 80%; the PNF rate was 10%; and the PDF rate was 15%. The careful use of ECDg with low to moderate steatosis is possible if particular care is taken to avoid additional risk factors related to the recipient.