Diagnosis Of Focal Nodular Hyperplasia Research Articles

Focal Nodular Hyperplasia of the Liver without a Central Scar: A Rare Case Report

Focal Nodular Hyperplasia (FNH) is most frequent benign tumour of liver just after the haemangioma, which makes about 3%-5% of all primary hepatic tumours. It occurs frequently in females during their middle age group. This is case report of 48-year-old female patient having complains of upper abdominal pain since last one year. Using abdominal ultrasonography and a CT scan, it was discovered that segment four of the liver contained a tumour measuring 11 cm in maximum diameter without a central scar, which made preoperative imaging scans for FNH difficult to diagnose. Lobectomy of left lobe was done. The gross specimen on cut section revealed a lesion with nodular appearance and absence of any central stellate scar. On the basis of histopathological finding the diagnosis of FNH without central stellet scar was made. To ensure adequate therapy, it is essential to differentiate between FNH and other hyper vascular liver lesions and metastases. Therefore, it is difficult to diagnose FNH before surgery if there are no typical radiological findings. This case report focused on FNH without the usual radiological findings and emphasised its importance to distinguish it from other malignant hyper vascular liver entities.

Fat in mass in primary liver lesions: are usual MRI diagnostic criteria of both malignant and benign liver lesions still applicable?

To evaluate the accuracy of the usual MRI diagnostic patterns of primary liver lesions applied to the diagnosis of pathologically proven fat-containing liver lesions. This monocentric IRB approved retrospective study included all patients with pathologically proven focal liver lesions and documented intra-tumoral fat on pathology and who underwent preoperative liver MRI for characterization. Both liver morphology and usual lesion MRI features were analyzed and their distribution correlated to the final pathological result (Khi-2 or Fisher exact tests, Student t-test or Mann-Whitney U test, as appropriate). The Sensitivity (Se) and Specificity (Sp) of MRI patterns known to be associated to both Hepatocellular Carcinoma (HCC), Focal Nodular Hyperplasia (FNH), and Hepatocellular Adenoma (HCA) subtypes were evaluated. Between March 2014 and November 2021, 66 lesions were included, corresponding to: 26 HCC, 32 HCA, 6 FNH and 2 hepatic angiomyolipoma (HAML). All lesions developed on a dysmorphic liver were HCC. A non-rim arterial phase hyperenhancement with a washout and an enhancing capsule had a 98% specificity for HCC diagnosis; A homogeneous dropout of signal on the opposed phase had a sensitivity of 92% and a specificity of 89% for the diagnosis of HNF1alpha inactivated subtype of HCA (HHCA). The FNH pattern was specific at 100% for the diagnosis of FNH with a 40% Se. Finally, the accuracy of inflammatory hepatocellular adenoma (IHCA) pattern had a low 60% Se but a high 89% Sp for IHCA diagnosis. Known MRI patterns remain reliable for the accurate diagnosis of primary liver tumors on MRI even in fat-containing lesions.

Diagnosis and Follow-up of Incidental Liver Lesions in Children.

Incidental liver lesions are identified in children without underlying liver disease or increased risk of hepatic malignancy in childhood. Clinical and imaging evaluation of incidental liver lesions can be complex and may require a multidisciplinary approach. This review aims to summarize the diagnostic process and follow-up of incidental liver lesions based on review of the literature, use of state-of-the-art imaging, and our institutional experience. Age at presentation, gender, alpha fetoprotein levels, tumor size, and imaging characteristics should all be taken into consideration to optimize diagnosis process. Some lesions, such as simple liver cyst, infantile hemangioma, focal nodular hyperplasia (FNH), and focal fatty lesions, have specific imaging characteristics. Recently, contrast-enhanced ultrasound (CEUS) was Food and Drug Administration (FDA)-approved for the evaluation of pediatric liver lesions. CEUS is most specific in lesions smaller than 3 cm and is most useful in the diagnosis of infantile hemangioma, FNH, and focal fatty lesions. The use of hepatobiliary contrast in MRI increases specificity in the diagnosis of FNH. Recently, lesion characteristics in MRI were found to correlate with subtypes of hepatocellular adenomas and associated risk for hemorrhage and malignant transformation. Biopsy should be considered when there are no specific imaging characteristics of a benign lesion. Surveillance with imaging and alpha fetoprotein (AFP) should be performed to confirm the stability of lesions when the diagnosis cannot be determined, and whenever biopsy is not feasible.

Diagnostic challenges of focal nodular hyperplasia: interobserver variability, accuracy, and the utility of glutamine synthetase immunohistochemistry.

The diagnosis of focal nodular hyperplasia (FNH) and the interpretation of glutamine synthetase (GS) staining can be challenging on biopsies. We aimed to evaluate the reproducibility of needle biopsy diagnosis of FNH, the effect of GS immunohistochemistry on FNH diagnosis, and which histological features are most useful for the diagnosis of FNH. The study included virtual needle biopsies generated from 75 resection specimens (30 FNHs, 15 hepatocellular adenomas, 15 hepatocellular carcinomas, and 15 non-lesional liver specimens). Pathologists were reasonably accurate (83.1%) in the diagnosis of FNH with haematoxylin and eosin alone. Ductular reaction and nodularity had the highest sensitivity for a diagnosis of FNH (88.1% and 82.2%, respectively), whereas central scar was the most specific feature (90.6%). The presence of two or more of the classic histological features had 89.6% sensitivity and 86.2% specificity for a diagnosis of FNH. Diagnostic accuracy was significantly higher with the addition of a GS stain. A map-like GS staining pattern was highly specific (99.3%) for FNH. However, GS staining was interpreted as non-map-like in 14.4% of reviews of true FNH cases, and overall interobserver agreement for interpretation of the GS staining pattern was only moderate (kappa=0.42). Pathologists are reasonably accurate in the diagnosis of FNH on virtual biopsies, and GS staining improves accuracy. However, a subset of FNH cases remain challenging. Steatosis and a pseudo-map-like GS staining pattern were associated with increased difficulty. Therefore, although a map-like GS staining pattern is useful for confirmation of a diagnosis, the lack of a map-like GS staining pattern on needle biopsy does not necessarily exclude a diagnosis of FNH.

Focal nodular hyperplasia after systemic chemotherapy: Pathological features of a series of 15 cases

AbstractIntroductionChemotherapy, particularly oxaliplatin, has been associated with the development of focal nodular hyperplasia (FNH). Imaging diagnosis of FNH is well standardized, but it can be misdiagnosed as liver metastasis. The aim of this study was to describe the pathological features of FNH occurring after systemic chemotherapy.Materials and methodsFrom our pathological files for 1990‐2021, we retrieved 15 cases of resected newly developed FNH in adults with liver metastasis treated with systemic chemotherapy. Pathological features of FNH nodules and non‐tumoral liver samples were reviewed.ResultsIn 11/15 (73%) cases, FNH developed after an oxaliplatin‐based regimen. The median interval from the beginning of chemotherapy to the FNH diagnosis was 15 months. FNH was unique in 11 (73%) cases, and the median size of nodules was 1.1 cm [range 0.5‐2.5]. Histologically, 9 (60%), 11 (73%) and 11 (73%) cases exhibited fibrous central scar, dystrophic vessels and ductular proliferation, respectively, with all three criteria present in five (33%) cases. Eight (53%) cases showed intralesional steatosis and nine (60%) cases showed a glutamine synthetase immunostaining map‐like pattern. In non‐tumoral liver, eight (53%) cases exhibited sinusoidal obstruction syndrome and four (27%) nodular regenerative hyperplasia.ConclusionThe occurrence of FNH after systemic chemotherapy is an emerging condition challenging the imaging diagnosis because typical morphological features are frequently missing. The presence of sinusoidal changes, including regenerative hyperplasia, in non‐tumoral liver supports the potential role of chemotherapy in the pathogenesis of FNH.

Diagnostic value of morphological enhancement patterns in the hepatobiliary phase of gadoxetic acid-enhanced MRI to distinguish focal nodular hyperplasia from hepatocellular adenoma.

To describe the different morphological enhancement patterns of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI (Gd-EOB-DTPA MRI) and to determine their added value in their differential diagnosis. A retrospective analysis of imaging findings in 185 benign hepatocellular lesions (154 FNH; 31 HCA) in 108 patients who underwent Gd-EOB-DTPA MRI was performed by two independent reviewers. Six patterns on HBP were recorded: 1) homogeneous enhancement; 2) peripheral ring-like enhancement with hypointense central core; 3) peripheral ring-like enhancement with hyperintense central core; 4) central core enhancement with hypointense periphery; 5) heterogeneous enhancement; and 6) the absence of enhancement. Peripheral ring-like enhancement with hypointense central core and peripheral ring-like enhancement with hyperintense central core showed the highest specificity for the diagnosis of FNH (100% and 96.8%, respectively). The absence of enhancement and central core enhancement with hypointense periphery were only present in 0.6% and 1.9% of FHN, respectively. All other patterns were observed with similar frequencies in FNH (22.1% to 26.6%). Six HCA showed contrast uptake on the HBP: homogeneous (6.5%), peripheral ring-like enhancement with hyperintense central core (3.2%) and heterogeneous (9.7%). Both FNH and HCA may demonstrate enhancement in the HBP of Gd-EOB-DTPA MRI, limiting its specificity. A significant improvement in specificity can be achieved by the evaluation of morphological enhancement patterns: Peripheral ring-like enhancement with hypointense or hyperintense central core was highly specific for FNH diagnosis. On the other hand, the absence of HBP enhancement makes the diagnosis of FNH unlikely.

Application of Immunohistochemistry in the Pathological Diagnosis of Liver Tumors

Although radiological diagnostics have been progressing, pathological diagnosis remains the most reliable method for diagnosing liver tumors. In some cases, definite pathological diagnosis cannot be obtained by histological evaluation alone, especially when the sample is a small biopsy; in such cases, immunohistochemical staining is very useful. Immunohistochemistry is the most frequently used technique for molecular pathological diagnosis due to its broad application, ease of performance and evaluation, and reasonable cost. The results occasionally reflect specific genetic mutations. The immunohistochemical markers of hepatocellular carcinoma include those of hepatocellular differentiation—such as hepatocyte paraffin 1 and arginase-1—and those of malignant hepatocytes—such as glypican-3, heat shock protein 70, and glutamine synthetase (GS). To classify the subtypes of hepatocellular adenoma, examination of several immunohistochemical markers, such as liver fatty acid-binding protein, GS, and serum amyloid A, is indispensable. Immunohistochemical staining for GS is also important for the diagnosis of focal nodular hyperplasia. The representative immunohistochemical markers of intrahepatic cholangiocarcinoma include cytokeratin (CK) 7 and CK19. In this article, we provide an overview of the application of immunohistochemistry in the pathological diagnosis of liver tumors referring to the association with genetic alterations. Furthermore, we aimed to explain the practical points in the differential diagnosis of liver tumors by immunohistochemical staining.

Focal nodular hyperplasia mimicking hepatocellular adenoma and carcinoma in two cases

Focal nodular hyperplasia (FNH) is a solid benign tumor of the liver, predominantly in young women. A correct diagnosis of FNH is essential for making appropriate clinical decisions and avoiding unnecessary liver resection. Herein, we reported that two male cases with FNH, who initially presented with persistent abdominal discomfort, were misdiagnosed with hepatocellular adenoma (HCA) and hepatocellular carcinoma (HCC) on contrast-enhanced magnetic resonance imaging and computed tomography scans, respectively. After surgery, a histological diagnosis of FNH was finally established. In this paper, we also reviewed the knowledge regarding diagnosis and differential diagnosis of FNH on imaging examinations, which are helpful for avoiding misdiagnoses and guiding clinical interventions.

Laparoscopic anatomical segment III resection for a giant focal nodular hyperplasia (FNH): advantages of the extraglissonean approach—a case report

: In recent years the laparoscopic approach in liver surgery has gained wide acceptance compared to open surgery, especially in cases of benign liver lesions. Many of these, i.e., focal nodular hyperplasia (FNH), have an important vascular inflow depending from nutrient vessels, which hamper sometimes a proper resection. We report in this video a 24-year-old male with a fortuitous diagnosis of a 10×8×7 cm FNH in the left hepatic lobe, with its characteristic central nutrient vessel. Given the size of the lesion, surgical excision was indicated and performed a laparoscopic resection of segment III following an extraglissonean approach. This approach enables an intrahepatic identification of the targeted glissonean pedicle for segment III without dissecting the hepatoduodenal ligament. It also permits the localization and clamp of the vascular inflow of the tumor leading to tumor shrinkage, which facilitates the resection without invading the tumor capsule and thus respecting the portal pedicles for the other segments. The patient did not present postoperative complications and was discharged on the third postoperative day. The definitive pathology confirmed the diagnosis of FNH. A detailed preoperative anatomical study of the liver segments allows a better planning of liver surgeries. More specifically, this selective transfisural glissonean approach avoids a dissection of the hepatoduodenal ligament and therefore the risk of a postoperative bile leak.

Machine Learning-Based Ultrasomics Improves the Diagnostic Performance in Differentiating Focal Nodular Hyperplasia and Atypical Hepatocellular Carcinoma.

BackgroundThe typical enhancement patterns of hepatocellular carcinoma (HCC) on contrast-enhanced ultrasound (CEUS) are hyper-enhanced in the arterial phase and washed out during the portal venous and late phases. However, atypical variations make a differential diagnosis both challenging and crucial. We aimed to investigate whether machine learning-based ultrasonic signatures derived from CEUS images could improve the diagnostic performance in differentiating focal nodular hyperplasia (FNH) and atypical hepatocellular carcinoma (aHCC).Patients and MethodsA total of 226 focal liver lesions, including 107 aHCC and 119 FNH lesions, examined by CEUS were reviewed retrospectively. For machine learning-based ultrasomics, 3,132 features were extracted from the images of the baseline, arterial, and portal phases. An ultrasomics signature was generated by a machine learning model. The predictive model was constructed using the support vector machine method trained with the following groups: ultrasomics features, radiologist’s score, and combination of ultrasomics features and radiologist’s score. The diagnostic performance was explored using the area under the receiver operating characteristic curve (AUC).ResultsA total of 14 ultrasomics features were chosen to build an ultrasomics model, and they presented good performance in differentiating FNH and aHCC with an AUC of 0.86 (95% confidence interval [CI]: 0.80, 0.89), a sensitivity of 76.6% (95% CI: 67.5%, 84.3%), and a specificity of 80.5% (95% CI: 70.6%, 85.9%). The model trained with a combination of ultrasomics features and the radiologist’s score achieved a significantly higher AUC (0.93, 95% CI: 0.89, 0.96) than that trained with the radiologist’s score (AUC: 0.84, 95% CI: 0.79, 0.89, P < 0.001). For the sub-group of HCC with normal AFP value, the model trained with a combination of ultrasomics features, and the radiologist’s score remain achieved the highest AUC of 0.92 (95% CI: 0.87, 0.96) compared to that with the ultrasomics features (AUC: 0.86, 95% CI: 0.74, 0.89, P < 0.001) and radiologist’s score (AUC: 0.86, 95% CI: 0.79, 0.91, P < 0.001).ConclusionsMachine learning-based ultrasomics performs as well as the staff radiologist in predicting the differential diagnosis of FNH and aHCC. Incorporating an ultrasomics signature into the radiologist’s score improves the diagnostic performance in differentiating FNH and aHCC.

Focal nodular hyperplasia with steroid-resistant nephrotic syndrome: A paraneoplastic condition or coincidental findings?

Background: Paraneoplastic glomerulonephritis (GN) are defined as glomerular lesions not directly related to tumor burden, invasion, or metastasis but induced by products of tumor cells. They are usually associated with solid tumors of gastrointestinal tract and hematological malignancies. Nephrotic syndrome is a rare manifestation of paraneoplastic syndromes, especially in children and biopsy findings are usually those of minimal change disease (MCD) or membranous nephropathy. We describe a case of steroid-resistant nephrotic syndrome with focal nodular hyperplasia (FNH) of liver. To the best of our knowledge, this has not been reported previously. Clinical Description: A 9-year-old boy presented with features of nephrotic syndrome and had a significant hepatomegaly. Based on radiological features and histopathological confirmation, the child was diagnosed to have a hepatic tumor consistent with a diagnosis of FNH, and the renal biopsy was suggestive of MCD. Management: As FNH did not require a surgical intervention, the nephrotic syndrome was managed with prednisolone initially, but the patient failed to achieve remission and was subsequently started on oral tacrolimus with enalapril and low-dose alternate day prednisolone. Remission of proteinuria was achieved within 2 months, and the child has been in follow-up for the past 18 months and the liver mass has been stable. Conclusion: This report suggests a possible paraneoplastic GN (steroid-resistant nephrotic syndrome) with FNH of liver that responded to immunosuppression.

Mesenchymal Hamartoma of the Liver and Spleen-A Rare Pseudotumour in Adults

Hepatic mesenchymal hamartoma is the third most common liver neoplasm of the pediatric age group, rarely diagnosed in adults, with under 50 cases having been reported so far. Mesenchymal hamartoma of the spleen is a very rare vascular lesion, documented in less than 200 cases since 1861 when it was first described by Karl von Rokitansky. 1.1. Aim: The aim of this paper is to discuss the differential diagnosis of these tumour-like lesions and the association between them, especially considering their rarity. 1.2. Methods: We present a case of multifocal mesenchymal hamartoma of the liver and spleen in a 51-year-old female patient. The hepatic tumour appears as a macro nodular lesion involving the interface between segments V and VIII [30x28mm], showing central scarring upon MRI imaging and suggesting the diagnosis of focal nodular hyperplasia. Moreover, a sub capsular splenic cystic mass was also revealed, involving the sub diaphragmatic surface of the organ [15x10mm]. 1.3. Results: The histological examination of the hepatic tumour revealed a myxoid stromal proliferation, composed of stellate and fibroblastoid cells, bile ducts with inconspicuous lumina, small vascular structures and chronic non-specific inflammatory infiltrate. On microscopic examination, the splenic lesion exhibited nodular collagenous fibrosis, radial septa and large hyalinized areas. 1.4. Conclusion: A key aspect in the effective treatment of patients diagnosed with mesenchymal hamartomas is surgery with negative margins. The peculiarity of this case consisted of the incidental finding of multiple liver tumours, the incidental finding of the splenic mass, and the rarity of this particular association in adults.

Focal nodular hyperplasia diagnosis with contrast-enhanced ultrasound

Focal nodular hyperplasia diagnosis with contrast-enhanced ultrasound

Focal nodular hyperplasia: new findings at Doppler ultrasonography.

The aim of our study was to explore the features of focal nodular hyperplasia (FNH) at Doppler ultrasonography, analyzing specifically the presence of intratumoral venous flow in patients with an established diagnosis of FNH. Previous studies showed that using a venous Doppler spectrum, intratumoral vessels are often depicted in hepatocellular adenoma (HCA) but less frequently in FNH. Forty-five FNHs from thirty-three consecutive patients (26 female, 7 male; mean±SD age: 40±13) underwent color Doppler ultrasonography and spectral analysis according to a standardized protocol. FNH diagnosis was established by the presence of typical behavior at contrast-enhanced ultrasound (CEUS) associated with another imaging technique (contrast-enhanced computed tomography [ceCT] or contrast-enhanced magnetic resonance [ceMR]). A biopsy was performed when imaging was inconclusive. All data concerning Doppler analysis were reviewed by two more operators, blinded to the final diagnosis, and the interobserver agreement for the presence of venous Doppler signal was determined by Cohen's Kappa. Of the 33 patients, 24 had a single solitary focus, and 9 had multiple foci. Lesion diameter ranged between 1.2 and 8.9 cm (mean ± SD 3.2±1.6 cm). The central feeding artery with the typical arterial spectrum was detected in all 45 lesions, whereas the spoke-wheel sign was observed in 18 cases (40%). A venous Doppler signal was detected in 35 FNHs (77.8%), and in 60% of them, it was identified in the center of the lesion. Venous Doppler signal located in the center of the lesion suspected to be a hypervascular benign lesion cannot be considered a typical HCA feature since it has been detected in a high percentage of FNH cases.

S2464 A Case of De novo Focal Nodular Hyperplasia Appearing as a New Liver Lesion After Liver Transplantation for Hepatocellular Carcinoma

INTRODUCTION: Focal nodular hyperplasia (FNH) is a benign hepatocellular lesion caused by vascular abnormalities within the liver, with radiologic features similar to Hepatocellular Carcinoma (HCC). Due to alterations in hepatic circulation associated with liver transplant (LT), FNH should be considered in the differential of liver lesions in patients with liver allografts. CASE DESCRIPTION/METHODS: We present the case of a 67-year-old male who underwent LT for HCC in the background of compensated hepatitis C related cirrhosis. LT was uncomplicated, with explant histology showing a single liver lesion with significant treatment effect and 5-10% of viable moderately differentiated HCC. On his initial post-LT surveillance Magnetic Resonance Imaging (MRI) done at 3 months, a 1.3 cm arterial phase enhancing liver lesion without venous washout or delayed capsular enhancement (LiRads3) was noted. Repeat MRI done at 6 and 9-months post-LT showed interval growth of the lesion, 1.7 then to 2.5 cm, respectively. At this time, with the suspicion for recurrence of HCC, a mass directed biopsy was performed, which resulted non-diagnostic for the mass lesion. MRI at 12 and 15 months post-LT showed continued growth to 2.8 cm (LiRADs5) with mildly hyperintense intralesional signal. As concern for HCC recurrence remained, repeat mass directed biopsy with several cores of tissue was completed. Histologic exam in two of the cores showed slightly expanded fibrous septa containing vessel branches and focal bile ductular reaction with mixed inflammatory infiltrate. A Glypican 3 immunostain was negative and reticulin stain showed intact lobular architecture with no thickened plates, sheets, or pseudoacinar formations, leading to a diagnosis of FNH. DISCUSSION: While not rare as a primary hepatic lesion, few cases describing FNH following LT have been documented. Our patient had an uneventful LT without hemodynamic instability or transfusion requirements. There was no known liver lesion in the donor prior to procurement and no liver graft biopsy was performed. Hepatic lesion discovery was made incidentally on surveillance MRI 3 months post LT, while liver enzymes remained normal. As there were no high-risk features on imaging, surveillance was continued. Diagnosis was confirmed 15 months post-LT, when significant growth led to biopsy and histological confirmation. Two years post-LT, the lesion remains stable and unchanged. Based on this evidence, we postulate that our case had de novo FNH following LT.

THU492 - Application of acoustic radiation force impulse elastography in non-invasive diagnosis of focal nodular hyperplasia

THU492 - Application of acoustic radiation force impulse elastography in non-invasive diagnosis of focal nodular hyperplasia

Long-term study analysis of contrast-enhanced ultrasound in the diagnosis of focal nodular hyperplasia.

Focal nodular hyperplasia (FNH) is a hyperplastic mass of vascular abnormality and the second most common benign liver lesion. It can be discovered incidentally or during a surveillance examination in patients at risk for hepatic malignancy, mostly by conventional ultrasound. CEUS has been used as an additional alternative method for the rapid diagnosis of FNH. However, none of the previous studies compared the diagnostic performance of CEUS to MRI retrospectively in a 10-year observation. The aim of this long-term retrospective study is to assess the diagnostic performance of CEUS in the imaging of FNH and compare the results to MRI. A single experienced physician performed CEUS examinations in 244 patients between 2009 and 2019 with suspected focal nodular hyperplasia after conventional ultrasound. A second-generation blood pool agent (SonoVue®, Bracco, Milan, Italy) was administered. Additional dynamic MRI with contrast agent was performed in a subgroup of 95 patients. Out of 244 patients, FNH could be displayed in 221 patients on CEUS. A subgroup of 95 patients had CEUS examinations and CEMRI for diagnosis comparison. In comparison with CEMRI, CEUS presented a sensitivity of 97%, a specificity of 76%, a positive predictive value of 93% and a negative predictive value of 89%. CEUS is a safe and feasible approach that assess the diagnosis of focal nodular hyperplasia equally to MRI. The focal lesion enhancement can be depicted in real-time in the arterial, venous and late phase facilitating the prompt diagnosis.

Quantification of liver fat content in liver and primary liver lesions using triple-echo-gradient-echo MRI.

To quantify and compare the fat fraction of background liver and primary liver lesions using a triple-echo-gradient-echo sequence. M&M: This IRB-approved study included 128 consecutive patients who underwent a liver MRI for lesion characterization. Fat fraction from the whole lesion volume and the normal liver parenchyma were computed from triple-echo (consecutive in-phase, opposed-phase, in-phase echo times) sequence. Forty-seven hepatocellular carcinoma (HCCs), 25 hepatocellular adenomas (HCAs), and 56 focal nodular hyperplasia (FNH) were included. The mean intralesional fat fraction for various lesions was 7.1% (range, 0.5-23.6; SD, 5.6) for HCAs, 5.7% (range, 0.8-14; SD, 2.9) for HCCs, and 2.3% (range, 0.8-10.3; SD, 1.9) for FNHs (p = 0.6 for HCCs vs HCA, p < 0.001 for FNH vs HCCs or HCA). A fat fraction threshold of 2.7% enabled distinction between HCA and FNH with a sensitivity of 80% and a specificity of 77%. The mean normal liver parenchyma fat fraction was lower than the intralesional fat fraction in the HCC group (p = 0.04) and higher in the FNH group (p = 0.001), but not significantly different in the HCA group (p = 0.51). Triple-echo-gradient-echo is a feasible technique to quantify fat fraction of background liver and primary liver lesions. Intralesional fat fraction obtained from lesion whole volume is greater for HCCs and HCA compared to FNH. When trying to distinguish FNH and HCA, an intralesional fat fraction < 2.7% may orient toward the diagnosis of FNH. • Triple-echo technique is feasible to quantify intralesional fat fraction of primary liver lesions. • Whole volume intralesional fat fraction is greater for HCCs and HCA compared to FNH. • An intralesional fat fraction < 2.7% may orient toward the diagnosis of FNH.

Liver contrast-enhanced sonography: computer-assisted differentiation between focal nodular hyperplasia and inflammatory hepatocellular adenoma by reference to microbubble transport patterns

A new computer tool is proposed to distinguish between focal nodular hyperplasia (FNH) and an inflammatory hepatocellular adenoma (I-HCA) using contrast-enhanced ultrasound (CEUS). The new method was compared with the usual qualitative analysis. The proposed tool embeds an "optical flow" algorithm, designed to mimic the human visual perception of object transport in image series, to quantitatively analyse apparent microbubble transport parameters visible on CEUS. Qualitative (visual) and quantitative (computer-assisted) CEUS data were compared in a cohort of adult patients with either FNH or I-HCA based on pathological and radiological results. For quantitative analysis, several computer-assisted classification models were tested and subjected to cross-validation. The accuracies, area under the receiver-operating characteristic curve (AUROC), sensitivity and specificity, positive predictive values (PPVs), negative predictive values (NPVs), false predictive rate (FPRs) and false negative rate (FNRs) were recorded. Forty-six patients with FNH (n = 29) or I-HCA (n = 17) with 47 tumours (one patient with 2 I-HCA) were analysed. The qualitative diagnostic parameters were accuracy = 93.6%, AUROC = 0.94, sensitivity = 94.4%, specificity = 93.1%, PPV = 89.5%, NPV = 96.4%, FPR = 6.9% and FNR = 5.6%. The quantitative diagnostic parameters were accuracy = 95.9%, AUROC = 0.97, sensitivity = 93.4%, specificity = 97.6%, PPV = 95.3%, NPV = 96.7%, FPR = 2.4% and FNR = 6.6%. Microbubble transport patterns evident on CEUS are valuable diagnostic indicators. Machine-learning algorithms analysing such data facilitate the diagnosis of FNH and I-HCA tumours. • Distinguishing between focal nodular hyperplasia and an inflammatory hepatocellular adenoma using dynamic contrast-enhanced ultrasound is sometimes difficult. • Microbubble transport patterns evident on contrast-enhanced sonography are valuable diagnostic indicators. • Machine-learning algorithms analysing microbubble transport patterns facilitate the diagnosis of FNH and I-HCA.

2226 Hot Spot Sign on Tc-99m DISIDA Nuclear Hepatobiliary Scan

INTRODUCTION: Hepatic Focal Nodular Hyperplasia (FNH) can be an unusual cause of abdominal pain. Prior to the advent of readily accessible diagnostic imaging techniques, patients with FNH primarily presented with vague symptoms of abdominal pain, then proceeded to imaging, which led to diagnosis. Today, most cases are found incidentally on imaging, in often asymptomatic patients. Here, we present a patient with significant symptoms in whom an identified FNH was considered inconsequential, but is eventually proven otherwise. CASE DESCRIPTION/METHODS: A previously healthy 31-year-old male presented with a one-month history of persistent postprandial right upper quadrant abdominal pain. Ultrasound showed cholelithiasis. MRI revealed FNH of the anteroinferior subsegment of the liver. Tc-99m DISIDA Cholescintigraphy showed a normal functioning gallbladder, but an abnormal delayed clearance of tracer from a focal area in inferior tip of the liver, corresponding to the FNH seen on MRI, consistent with a “hot spot sign”. Due to suspicion for symptomatic cholelithiasis, he underwent elective cholecystectomy. Symptoms persisted post-op, thus, his pain was thought to be from symptomatic FNH. After subsequent elective FNH resection, symptoms subsided. DISCUSSION: While cholescintigraphy typically evaluates for biliary tree dysfunction, it can also reveal abnormality in hepatic parenchymal tissue. Previously, Tc-99m Sulfur Colloid Liver-Spleen scans were used for diagnosis of FNH. However, the “hot spot sign” on cholescintigraphy has also been described as diagnostic for FNH. This case illustrates that a focal area of delayed tracer washout, or “hot spot”, can also be seen with Tc-99m DISIDA. Although the significance of delayed tracer washout is unclear, this finding suggests liver parenchyma’s inability to effectively clear bile from an FNH. This inability to adequately clear bile, may result in pain. The severity of impaired clearance may even correlate with the severity of symptoms. Although further investigation is necessary, cholescintigraphy may prove a useful tool in functional imaging for differentiating between symptomatic and asymptomatic FNH.