Intratumoral Fat Research Articles

Accuracies of Chemical Shift In/Opposed Phase and Chemical Shift Encoded Magnetic Resonance Imaging to Detect Intratumoral Fat in Hepatocellular Carcinoma

Magnetic Resonance Imaging (MRI) being a noninvasive modality may help in preoperative evaluation of intratumoral fat in hepatocellular carcinoma (HCC) using chemical shift encoded (CSE) MRI and in-/opposed-phase (IOP) imaging sequences. To compare the diagnostic accuracy of chemical shift encoded fat fraction at three different flip angles (FAs) using quantitative chemical shift encoded MRI (CSE-MRI) with in-/opposed phase (IOP) imaging to evaluate intratumoral fat in HCC. Retrospective. Eighty-six patients with 87 pathology proven HCCs. IOP (LAVA-Flex) and CSE-MRI (IDEAL IQ) a three-dimensional spoiled gradient-echo pulse sequences acquired at 3 T. Regions of interest (ROIs) were manually drawn by two observers in the tumors to measure mean fat fractions. Surgical specimens were reassessed for intratumoral fat content. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed for CSE-MRI sequence at FA 3°, 8°, and 9°. Intraclass correlation coefficient (ICC) was expressed in terms of inter- and intra-observer agreements. Receiver operating characteristic curve analysis was performed for the diagnostic performance followed by combined metric of both. SNR/CNR were analyzed by Kruskal-Wallis test. Excellent inter- and intra-observer agreements (ICC >0.95, P < 0.001) were observed for both IOP and CSE-MRI. IOP (86.4%) showed higher sensitivity than CSE-MRI at FA 3° (72.5%), FA 8° (76.4%) and FA 9° (76.3%). In contrast, the specificity for CSE-MRI at FA 3° (86%), FA 8° (87%), and FA 9° (87%) were greater than IOP (72%). A combined metric of IOP and CSE-MRI derived fat fractions at FA 8° gave highest AUC of 87% and accuracy of 86%. SNR and CNR for CSE-MRI were significantly higher at FA 8° and FA 9° than FA 3° (P < 0.05). IOP and quantitative CSE-MRI are both feasible methods to detect intratumoral fat in HCC with higher accuracy and SNR for CSE-MRI at FA 8° and 9°. 3 TECHNICAL EFFICACY: Stage 2.

Role of MRI in distinguishing intrahepatic cholangiocarcinoma from poorly differentiated hepatocellular carcinoma

ObjectivesTo evaluate the role of MRI in the diagnosis of mass-forming intrahepatic cholangiocarcinoma (mICC), its enhancement pattern with contrast agent, and distinction from poorly differentiated hepatocellular carcinoma (pHCC).BackgroundmICC is the second most common primary hepatobiliary tumor that is increasing in incidence. Imaging characteristics in mICC differ significantly, having overlapping imaging features with pHCC. Thus, it is important to differentiate mICC from pHCC.Patients and methodsA retrospective MRI study was conducted on 15 patients with mICC and 15 patients with pHCC referred to MRI unit of the National Liver Institute, Menoufia University from June 2017 to January 2019. MRI were analyzed for tumor shape, intratumoral hemorrhage, fibrous capsule, T2 signal intensity, capsular retraction, intratumoral fat, biliary dilatation, vascular invasion, intraductal lesion, intrahepatic metastasis, restricted diffusion, and enhancement pattern after contrast injection. Associations between MRI features and tumor type were examined using the Fisher's exact and χ2 tests.ResultsLate enhancement was more common in mICC than pHCC (P < 0.001). T2 central hypointense area was more common in mICC versus HCC (P = 0.001). Capsular retraction was more common in mICC than HCC (P = 0.001). Biliary dilatation was more common in mICC than pHCC (P = 0.001). Fat component was more in pHCC than mICC (P = 0.01). Fibrous capsule was more common in pHCC than mICC (P = 0.002). Others parameters were not significant.ConclusionBiliary dilatation, central fibrosis, overlying capsular retraction, and late enhancement at 3 min with absence of fat and fibrous capsule appear to be the most important characteristics for mICC and help its differentiation from pHCC.

Quantitative analysis of multiphase magnetic resonance images may assist prediction of histopathological grade of small hepatocellular carcinoma.

BackgroundThe aim of the study was to investigate whether preoperative quantitative analysis of multiphase magnetic resonance images may assist in predicting the pathological grade of small hepatocellular carcinoma (HCC).MethodsA total of 49 patients with small HCCs (≤3 cm) underwent multiphase magnetic resonance imaging (MRI) and were retrospectively reviewed. Routine unenhanced and post gadobenate dimeglumine (Gd-BOPTA)-enhanced MRI were preoperatively performed. Signal intensity (SI) was measured within the designated region of interest (ROI) including those of the lesion and paraspinous muscles. The lesion-to-paraspinous muscle relative contrast ratio (RCR) on T2-weighted (T2W) imaging, diffusion-weighted (DW) imaging, and dynamic phase Gd-BOPTA-enhanced T1W (T1-weighted) imaging were calculated, and statistical analysis was performed to determine the predictive power for the histological grade.ResultsIn all, 49 cases were included comprising 3 well-differentiated (WD) HCCs, 36 moderately differentiated (MD) HCCs, and 10 poorly differentiated (PD) HCCs. There was a negative correlation between the RCR and pathological grade of small HCC in the arterial phase [correlation coefficient (ρ)=−0.305, P<0.05]. However, there was no correlation between RCR in other phases and pathological grade (P>0.05 for all). There was also no correlation between tumor margin, tumor location, cystic/necrotic change, intratumoral fat, enhancement pattern, tumor capsule, tumor boundary or tumor size, and any of the differentiation categories (P>0.05 for all).ConclusionsThe lesion-to-paraspinous muscle RCR on arterial phase Gd-BOPTA-enhanced T1W imaging may be useful for the prediction of the histological characteristics of small HCC.

Combined hepatocellular-cholangiocarcinoma: which preoperative clinical data and conventional MRI characteristics have value for the prediction of microvascular invasion and clinical significance?

ObjectivesTo explore which preoperative clinical data and conventional MRI findings may indicate microvascular invasion (MVI) of combined hepatocellular-cholangiocarcinoma (cHCC-CCA) and have clinical significance.MethodsThe study enrolled 113 patients with histopathologically confirmed cHCC-CCA (MVI-positive group [n = 56], MVI-negative group [n = 57]). Two radiologists retrospectively assessed the preoperative MRI features (qualitative analysis of morphology and dynamic enhancement features), and each lesion was assigned according to the LI-RADS. Preoperative clinical data were also evaluated. Logistic regression analyses were used to assess the relative value of these parameters as potential predictors of MVI. Recurrence-free survival (RFS) rates after hepatectomy in the two groups were estimated using Kaplan–Meier survival curves and compared using the log-rank test.ResultsThe majority of cHCC-CCAs were categorized as LR-M. On multivariate analysis, a higher serum AFP level (OR, 0.523; 95% CI, 0.282–0.971; p = 0.040), intratumoral fat deposition (OR, 14.368; 95% CI, 2.749–75.098; p = 0.002), and irregular arterial peritumoral enhancement (OR, 0.322; 95% CI, 0.164–0.631; p = 0.001) were independent variables associated with the MVI of cHCC-CCA. After hepatectomy, patients with MVI of cHCC-CCA showed earlier recurrence than those without MVI (hazard ratio [HR], 0.402; 95% CI, 0.189–0.854, p = 0.013).ConclusionA higher serum AFP level and irregular arterial peritumoral enhancement are potential predictive biomarkers for the MVI of cHCC-CCA, while intratumoral fat detected on MRI suggests a low risk of MVI. Furthermore, cHCC-CCAs with MVI may have worse surgical outcomes with regard to early recurrence than those without MVI.Key Points• Higher serum levels of AFP combined with irregular arterial peritumoral enhancement are independent risk factors for the MVI of cHCC-CCA, while fat deposition might be a protective factor.• cHCC-CCA with MVI may have a higher risk of early recurrence after surgery.• Most cHCC-CCAs were categorized as LR-M in this study, and no significant difference was found in MVI based on LI-RADS category.

Clinicopathologic analysis of renal cell carcinoma containing Intratumoral fat with and without osseous metaplasia

BackgroundThere is minimal information regarding the prevalence of intratumoral adipose in renal cell carcinoma (RCC), and no study has assessed the impact of intratumoral adipose on the preoperative imaging diagnosis. The aim of this study was to investigate the prevalence and histopathologic characteristics of entrapped adipose with or without osseous metaplasia in RCC nephrectomy specimens and to determine if this finding impacted the preoperative imaging interpretation.Methods704 RCC specimens were prospectively evaluated for entrapped adipose and osseous metaplasia (423 partial nephrectomies, 281 total nephrectomies; 327 pT1a, 377 ≥ pT1b; 510 clear cell, 119 papillary, 30 chromophobe, 22 clear cell papillary, 23 other). Imaging reports were obtained, and the presence of intratumoral fat or calcification and the radiologic diagnostic impression were recorded.Results3% (n = 21) contained microscopically identified intratumoral adipose, with a similar frequency in the main histologic subtypes (p = 0.76). Mean metaplastic deposit size was 0.4 cm, mean deposit to capsule distance 0.2 cm, and 29% involved the tumor capsule. Histologically identified adipose was infrequently noted via imaging (13%), and only 1 case with histologically identified metaplasia had a radiologic diagnostic differential of angiomyolipoma (1/704, 0.1%).ConclusionWhile intratumoral adipose and/or osseous metaplasia can be observed within RCC, it is extremely rare for the radiologic diagnostic impression to have been confounded by histologically identified entrapped adipose. Awareness that metaplastic deposits are usually near the tumor capsule and may be minute could help prevent errors in diagnosis or staging.

Characterization of clear cell renal cell carcinoma and other renal tumors: evaluation of dual-energy CT using material-specific iodine and fat imaging.

This study aimed to assess material-specific iodine and fat images for diagnosis of clear cell renal cell carcinoma (cc-RCC) compared to papillary RCC (p-RCC) and other renal masses. With IRB approval, we identified histologically confirmed solid renal masses that underwent rapid-kVp-switch DECT between 2016 and 2018: 25 cc-RCC (7 low grade versus 18 high grade), 11 p-RCC, and 6 other tumors (2 clear cell papillary RCC, 2 chromophobe RCC, 1 oncocytoma, 1 renal angiomyomatous tumor). A blinded radiologist measured iodine and fat concentration on material-specific iodine-water and fat-water basis pair images. Comparisons were performed between groups using univariate analysis and diagnostic accuracy calculated by ROC. Iodine concentration was higher in cc-RCC (6.14 ± 1.79mg/mL) compared to p-RCC (1.40 ± 0.54mg/mL, p < 0.001), but not compared to other tumors (5.0 ± 2.2mg/mL, p = 0.370). Intratumoral fat was seen in 36.0% (9/25) cc-RCC (309.6 ± 234.3mg/mL [71.1-762.3ng/mL]), 9.1% (1/11) papillary RCC (97.11mg/mL), and no other tumors (p = 0.036). Iodine concentration ≥ 3.99mg/mL achieved AUC and sensitivity/specificity of 0.88 (CI 0.76-1.00) and 92.31%/82.40% to diagnose cc-RCC. To diagnose p-RCC, iodine concentration ≤ 2.5mg/mL achieved AUC and sensitivity/specificity of 0.99 (0.98-1.00) and 100%/100%. The presence of intratumoral fat had AUC 0.64 (CI 0.53-0.75) and sensitivity/specificity of 34.6%/93.8% to diagnose cc-RCC. A logistic regression model combining iodine concentration and presence of fat increased AUC to 0.91 (CI 0.81-1.0) with sensitivity/specificity of 80.8%/93.8% to diagnose cc-RCC. Iodine concentration values are highly accurate to differentiate clear cell RCC from papillary RCC; however, they overlap with other tumors. Fat-specific images may improve differentiation of clear cell RCC from other avidly enhancing tumors. • Clear cell renal cell carcinoma (RCC) has significantly higher iodine concentration than papillary RCC, but there is an overlap in values comparing clear cell RCC to other renal tumors. • Iodine concentration ≤ 2.5mg/mL is highly accurate to differentiate papillary RCC from clear cell RCC and other renal tumors. • The presence of microscopic fat on material-specific fat images was specific for clear cell RCC, helping to differentiate clear cell RCC from other avidly enhancing renal tumors.

Clinical Characteristics and Surgical Management of Adult Adrenal Teratoma: A 15-year Experience and Systematic Review of the Literature

ObjectiveTo summarize the clinical characteristics and surgical management of adrenal teratoma in adults. Patients and MethodsWe retrospectively reviewed 14 patients with adrenal teratoma from January 2002 to June 2017, at 2 large centers in China and performed a systematic review of 39 patients from our series and published literatures. The clinicopathological characteristics, imaging features, surgical management and outcomes of this rare disease were analyzed. ResultsOur series includes 12 females and 2 males with the median age of 35. Seven patients were treated by open adrenalectomy (OA) and 7 by laparoscopic adrenalectomy (LA) without perioperative complications. All patients were alive without recurrence or canceration over a mean follow-up of 77.1 months. In the systemic review, the male-female ratio was nearly 1:3, with a median age of 29 years. Mean tumor size was 9.4 cm and the distribution was almost the same between left and right side (53.8% vs 46.2%). The most common symptoms were flank or abdominal pain (46.2%), whereas 53.8% patients were asymptomatic. Tumors were often cystic (63.9%) with intratumoral fat (91.7%) and calcifications (80.6%). All patients underwent surgery including 17 (43.6%) OA and 22 (56.4%) minimally invasive surgery. All tumors were pathologically confirmed mature teratoma except for one. ConclusionAdrenal teratoma is an extremely rare entity, frequently found to be large, benign and cystic. The patient's prognosis is generally good. As for its large volume, OA is the first choice for teratoma in most cases, while the LA can be an option in the small one.

Gadoxetic acid-enhanced magnetic resonance imaging can predict the pathologic stage of solitary hepatocellular carcinoma.

BACKGROUNDAlthough important for determining long-term outcome, pathologic stage of hepatocellular carcinoma (HCC) is difficult to predict before surgery. Current state-of-the-art magnetic resonance imaging (MRI) using gadoxetic acid provides many imaging features that could potentially be used to classify single HCC as pT1 or pT2.AIMTo determine which gadoxetic acid-enhanced MRI (EOB-MRI) findings predict pathologic stage T2 in patients with solitary HCC (cT1).METHODSPre-operative EOB-MRI findings were reviewed in a retrospective cohort of patients with solitary HCC. The following imaging features were examined: Hyperintensity in unenhanced T2-weighted images, hypointensity in unenhanced T1-weighted images, arterial enhancement, corona enhancement, washout appearance, capsular appearance, hypointensity in the tumor tissue during the hepatobiliary (HB) phase, peritumoral hypointensity in the HB phase, hypointense rim in the HB phase, intratumoral fat, hyperintensity on diffusion-weighted imaging, hypointensity on apparent diffusion coefficient map, mosaic appearance, nodule-in-nodule appearance, and the margin (smooth or irregular). Surgical pathology was used as the reference method for tumor staging. Univariate and multivariate analyses were performed to identify predictors of microvascular invasion or satellite nodules.RESULTSThere were 39 (34.2%; 39 of 114) and 75 (65.8%; 75 of 114) pathological stage T2 and T1 HCCs, respectively. Large tumor size (≥ 2.3 cm) and two MRI findings, i.e., corona enhancement [odds ratio = 2.67; 95% confidence interval: 1.101-6.480] and peritumoral hypointensity in HB phase images (odds ratio = 2.203; 95% confidence interval: 0.961-5.049) were associated with high risk of pT2 HCC. The positive likelihood ratio was 6.25 (95% confidence interval: 1.788-21.845), and sensitivity of EOB-MRI for detecting pT2 HCC was 86.2% when two or three of these MRI features were present. Small tumor size and hypointense rim in the HB phase were regarded as benign features. Small HCCs with hypointense rim but not associated with aggressive features were mostly pT1 lesions (specificity, 100%).CONCLUSIONImaging features on EOB-MRI could potentially be used to predict the pathologic stage of solitary HCC (cT1) as pT1 or pT2.

Current status of imaging biomarkers predicting the biological nature of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is heterogeneous in terms of its biological nature. Various factors related to its biological nature, including size, multifocality, macroscopic morphology, grade of differentiation, macro/microvascular invasion, bile duct invasion, intra-tumoral fat and molecular factors, and their value as prognostic imaging biomarkers have been reported. And recently, genome-based molecular HCC classification correlated with clinical outcome has been elucidated. The imaging biomarkers suggesting a less aggressive nature of HCC are smaller size, solitary tumor, smooth margin suggesting small nodular type with indistinct margin and simple nodular type with distinct margin, capsule, imaging biomarkers predicting early or well-differentiated grade, intra-tumoral fat detection, and low fluorodeoxyglucose (FDG) accumulation. The imaging biomarkers suggesting an aggressive HCC nature are larger size, multifocality, non-smooth margin suggesting simple nodular type with extranodular growth, confluent multinodular, and infiltrative type, imaging biomarkers predicting poor differentiation, macrovascular tumor thrombus, predicting microvascular invasion imaging biomarkers, bile duct dilatation or tumor thrombus, and high FDG accumulation. In the genome-based molecular classification, CTNNB-1 mutated HCC shows a less aggressive nature, while CK19/EpCAM positive HCC and macrotrabecular massive HCC show an aggressive one. Better understanding of these imaging biomarkers can contribute to devising more appropriate treatment plans for HCC.

Imaging features related with prognosis of hepatocellular carcinoma.

We discuss various imaging features that have been reported to be associated with the prognosis of hepatocellular carcinoma (HCC) but not included in the current staging systems: findings related with microvascular invasion, tumor encapsulation, intratumoral fat, presence of satellite nodules, peritumoral hypointensity on hepatobiliary phase images of gadoxetic-acid enhanced MRI, restricted diffusion, and irregular rim-like hyperenhancement. Current evidence suggests that larger (> 2cm) tumor size, presence of satellite nodules, presence of irregular rim-like hyperenhancement of a tumor, peritumoral parenchymal enhancement in the arterial phase, and peritumoral hypointensity observed on hepatobiliary phase images are independent imaging features to portend a worse prognosis in patients with hepatocellular carcinoma.

MRI Detection of Intratumoral Fat in Colorectal Liver Metastases After Preoperative Chemotherapy.

The objective of this study was to investigate the incidence and clinical significance of intratumoral fat deposition in colorectal liver metastases (CLMs) after preoperative chemotherapy using dual-echo gradient-recalled echo MRI. Our institutional review board approved this retrospective radiographic study and waived the requirement for informed patient consent. Fifty-nine patients (33 men, 26 women; median age, 62 years old) who underwent preoperative MRI and curative hepatic resection for colorectal liver metastases after chemotherapy were selected. Twenty patients also underwent MRI before chemotherapy. On dual-echo gradient-recalled echo MR images, intratumoral fat deposition and fat signal fraction at the densest areas of fat deposition in colorectal liver metastases were evaluated. Predictors of overall survival and intratumoral fat deposition after chemotherapy were identified by multivariate analyses. Before and after chemotherapy, 0 (0%) and 32 (54%) of the patients exhibited intratumoral fat deposition, respectively. Independent predictors of poor overall survival were presence of five or more CLMs (p < 0.001), fat signal fraction of 12% or more (p = 0.01), age of 65 years or older (p = 0.02), and tumor response classified as progressive or stable disease by the Response Evaluation Criteria in Solid Tumors 1.1 (p = 0.049). Predictors of tumor fat signal fraction being 12% or greater after chemotherapy were largest tumor size of 5 cm or more (p = 0.005), tumor calcification (p = 0.008), and history of cetuximab or panitumumab administration (p = 0.04). CLMs after preoperative chemotherapy frequently exhibit intratumoral fat deposition.

The different faces of renal angiomyolipomas on radiologic imaging: a pictorial review.

Renal angiomyolipoma (AML) is an uncommon renal tumour, generally composed of mature adipose tissue, dysmorphic blood vessels and smooth muscle. Identification of intratumoral fat on unenhanced CT images is the most reliable finding for establishing the diagnosis of renal AML. However, AMLs sometimes exhibit atypical findings, including cystic as well as solid forms; some of these variants overlap with the appearance of other renal tumours. A rare type of AML, the epithelioid type, possesses malignant potential. The aim of this pictorial review is to gather the different imaging features of AMLs including the classic and fat-poor types, AMLs with epithelial cysts, epithelioid AML, AML associated with tuberous sclerosis, haemorrhagic AML and large AMLs mimicking retroperitoneal liposarcomas. The diagnostic clues that help to distinguish AMLs from other renal tumours are also described in the review.

Superselective Transcatheter Arterial Embolization for Large Unruptured Renal Angiomyolipoma in Lymphangioleiomyomatosis

PurposeTo retrospectively evaluate therapeutic performance and complications of superselective transcatheter arterial embolization (TAE) for unruptured renal angiomyolipoma (AML) in patients with lymphangioleiomyomatosis (LAM) and to investigate the correlation between percentage reduction in tumor volume and intratumoral fat content. Materials and MethodsSuperselective TAE was performed in 14 consecutive patients with 15 large unruptured renal AMLs associated with LAM (mean age, 38 y; range, 21–57 y). Patients had renal AML with aneurysms ≥ 5 mm in diameter, tumor-related abdominal symptoms, or both. In all cases, embolization of 1 tumor was achieved in a single session by using multiporous gelatin sponge particles (GSPs) with additional metallic coils in all but 1 case. Tumor volume and fat content percentage were measured on CT or MR imaging before and after superselective TAE (median, 11 months; range, 6–14 months). ResultsResidual tumor staining declined by > 90% after all TAE sessions except 2, with embolization of all treated aneurysms. No nontarget embolization or severe complications were encountered. Mean percentage reduction in tumor volume after superselective TAE was 69% (range, 21%–95%). Percentage tumor volume reduction was negatively correlated with fat content before embolization (P < .01). ConclusionsSuperselective TAE with multiporous GSPs and metallic coils for large unruptured renal AML in patients with LAM is useful for reducing tumor volume and treating intratumoral aneurysms without major pulmonary or renal complications. Extent of tumor reduction may be influenced by fat content before embolization.

Liponeurofibroma: Clinicopathological features and histogenesis.

A neurofibroma is a common cutaneous benign tumor of neural origin. Various histological variants have been reported. Recently, sporadic reports of fatty variants have been reported but their clinicopathological features have not been well studied. The purpose of this study was to examine liponeurofibroma, and to report the distinctive clinicopathological features and histogenesis in comparison with the classic form. A retrospective study was performed on 130 cases. Immunohistochemical staining was performed for S100, factor VIIIa, perilipin and vascular endothelial growth factor. Masson's trichrome stain was also used. Intratumoral adipocytes were examined with transmission electron microscopy. Thirty-two (24.6%) cases were classified as liponeurofibroma on microscopic examination. This variant was more common in patients with neurofibromatosis type 1, older age and female sex. The most prevalent location was the head and neck. Intratumoral fat deposits showed differences in morphology and size compared with subcutaneous fat on light microscopy. Neurofibromatosis type 1 had the highest odds of fatty change in liponeurofibroma. In sporadic cases, fatty change can be caused by senescence, chronic injury, or tissue hypoxia secondary to internal or external stimuli. Further investigation is needed to identify the pathomechanism of fatty change in various cutaneous neoplasms, including neurofibroma.

Soft tissue masses with myxoid stroma: Can conventional magnetic resonance imaging differentiate benign from malignant tumors?

ObjectivesTo retrospectively evaluate the diagnostic performance of morphological signs observed on conventional magnetic resonance (MR) imaging to differentiate benign from malignant peripheral solid tumors of soft tissue with myxoid stroma. MethodsMR images from 95 consecutive histopathologically proven tumors (26 benign and 69 malignant) of soft tissues with myxoid components were evaluated in our tertiary referral center. Two radiologists, blind to pathology results, independently reviewed conventional MR sequences including at least a) one T2-weighted sequence with or without fat suppression; b) one T1-weighted sequence without fat suppression; and c) one T1-weighted sequence with gadolinium-complex contrast enhancement and fat suppression. Multiple criteria were defined to analyze morphology, margins, architecture and tumor periphery and evaluated for each lesion. Intra- and inter-observer reproducibility and Odds ratios were calculated for each criterion. ResultsThe most relevant and reproducible criteria to significantly predict malignancy were: (1) ill-defined tumor margins, (2) a hemorrhagic component, (3) intra-tumoral fat, (4) fibrosis and (5) the “tail sign”. A lesion is classified as malignant if any of these 5 criteria is present, and benign if none of them are observed. Therefore, this combination provides a sensitivity of 92.9% and a specificity of 93.3%. ConclusionConventional MR imaging provides reproducible criteria that can be combined to differentiate between benign and malignant solid tumors of soft tissue with myxoid stroma.

Sporadic versus Tuberous Sclerosis Complex–Associated Angiomyolipomas: Predictors for Long-Term Outcomes following Transcatheter Embolization

PurposeTo evaluate risk factors for long-term outcomes following embolization of sporadic versus tuberous sclerosis complex (TSC)–associated angiomyolipomas (AMLs). Materials and MethodsA retrospective review of consecutive transcatheter embolizations of renal AMLs between 2002 and 2014 was performed. Tumor volumetrics including density analysis were obtained. Treatment outcomes were assessed at 1 year after embolization using Response Evaluation Criteria In Solid Tumors (RECIST) 1.1 and volumetric RECIST criteria. A total of 56 patients, 70% (39/56) of whom had TSC, underwent embolization of 72 renal AMLs. Embolization was most commonly performed (70/72, 97%) using microspheres (300–500 μm or 500–700 μm Embosphere). ResultsBetween the sporadic and TSC-associated populations, there was no difference in follow-up time (648 d vs 583 d, P = .78), initial tumor diameter (6.68 cm vs 5.71 cm, P = .09), or percent tumoral fat content (39.5% vs 8.6%, P = .35). Progressive disease was noted in 9 TSC-associated AMLs by volume and 3 TSC-associated AMLs by diameter but in no sporadic AMLs. Growth suppression curves were remarkable for rebound growth in TSC patients, particularly in TSC patients younger than 18 years. Patient age (P = .007) and tumor volume (P = .03) were found to correlate with tumor regrowth within the TSC population. No difference was found in median change in total volume after embolization based on fat content (−57.9% vs −54.2%, P = .68). ConclusionsTSC, patient age, and tumoral volume before embolization are risk factors for AML growth following embolization. Intratumoral fat content was not found to predict response to embolization.

Should fat in the radiofrequency ablation zone of hepatocellular adenomas raise suspicion for residual tumour?

To assess the significance of fat in the radiofrequency ablation (RFA) zone of hepatocellular adenomas (HCA), and its association with tumoral fat and hepatic steatosis. The radiological archive was searched for patients with ablated HCAs and follow-up magnetic resonance imaging between January 2008 and June 2014. Age, sex, risk factors and duration of clinical and imaging follow-up were recorded. Pre-RFA imaging was assessed for tumour size, intra-tumoral fat and steatosis. Post-RFA imaging was reviewed for size, enhancement and intra-ablational fat. Intra-ablational fat was classified as peripheral, central or mixed; the association of these distributions with steatosis and tumoral fat was assessed using Fisher's exact test. Sixteen patients with 26 ablated HCAs were included. Fat was present in 23/26 (88%) ablation zones. Only 1/26 (4%) showed serial enlargement and enhancement suggestive of residual disease; the enhancing area did not contain fat. All remaining ablations showed involution and/or diminishing fat content without suspicious enhancement (mean follow-up, 27months; range, 2-84months). The peripheral and mixed/central patterns of intra-ablational fat were associated with steatosis (P = 0.0005) and tumoral fat (P = 0.0003), respectively. Fat in the ablation zone of HCAs is a common finding which, in isolation, does not indicate residual tumour. • Fat in the RFA zone of HCAs is a common finding on MRI. • The distribution of fat is associated with hepatic steatosis and intra-tumoral fat. • In isolation, intra-ablational fat of treated HCAs does not indicate residual tumour.

Calcified Renal Angiomyolipoma: A Case Report

We report the case of a calcified angiomyolipoma of the kidney, fortuitously discovered on a computed tomography scan of the abdomen. Because of the presence of intratumoral calcification and macroscopic fat, renal cell carcinoma could not be ruled out by imaging. Biopsy of the mass was performed, and pathological study confirmed the diagnosis of angiomyolipoma. Biopsy of renal masses containing macroscopic fat and calcification may be considered before nephrectomy.

Hepatic Angiomyolipoma Versus Hepatocellular Carcinoma in the Noncirrhotic Liver on Gadoxetic Acid-Enhanced MRI: A Diagnostic Challenge.

The purpose of this study is to describe the imaging characteristics of hepatic angiomyolipoma (AML) on gadoxetic acid-enhanced MRI and to identify imaging features that are helpful for differentiating it from hepatocellular carcinoma (HCC) in a noncirrhotic liver. We retrospectively identified 18 patients with pathologically proven hepatic AMLs who had undergone gadoxetic acid-enhanced MRI between 2008 and 2012. We randomly chose 36 patients with noncirrhotic liver who had a single HCC diagnosed radiologically during the same period. None of the HCCs was of the fibrolamellar variant. Two readers reviewed images in consensus to assess the lesion size, the presence of fat, signal intensity characteristics, enhancement profile, early draining veins, intratumoral vessels, and tumor capsules. The tumor-to-liver contrast ratios were measured. These features and the measurements were compared between the two groups. AMLs are more commonly found in women (83.3%), whereas HCCs are more common in men (75%) (p < 0.01). The size of AMLs (3.4 cm) and HCCs (4.3 cm) did not differ significantly. Intratumoral fat was identified in both AMLs (50.0%) and HCCs (30.6%). The dynamic enhancement profile (arterial hypervascularity and hypointensity during the delayed phase) was similar qualitatively and quantitatively except for the portal phase. AMLs and HCCs differed significantly with regard to isointensity on DWI (16.7% vs 0.0%; p = 0.03), washout in the portal phase (61.1% vs 88.9%; p = 0.03), early draining veins (27.8% vs 2.8%; p = 0.01), intratumoral vessels (55.6% vs 22.2%; p = 0.03), and presence of capsule (11.1% vs 50.0%; p = 0.01). On gadoxetic acid-enhanced MRI of noncirrhotic liver, AML is often indistinguishable from HCC on the basis of the enhancement profiles. Female sex and some imaging features including DWI could facilitate the differentiation.

Lipomatous ependymoma: report of a rare differentiation pattern with a comprehensive review of literature

We report the case of a 13-year-old girl presenting with left-sided hemiparesis, altered sensorium and episodic headache with bouts of projectile vomiting. Imaging revealed a large heterodense intraventricular mass lesion displaying focal calcification and hyperintensity on T1- and T2- weighted fluid attenuated inversion recovery (FLAIR) magnetic resonance images suggesting the presence of intratumoral fat. Histologically, the tumour showed sheets of glial cells, focal perithelial rosettes and individual cells showing fat vacuoles. The morphological impression was of an ependymoma with lipomatous differentiation. Glial fibrillary acid protein (GFAP) immunohistochemistry revealed positivity in the cytoplasmic processes of the tumour cells as well as in the cytoplasmic rim of the cells having an adipocytic appearance. S100 and vimentin were also immunoreactive. Ultrastructural studies confirmed the ependymal differentiation of the tumour and the presence of an osmiophilic fat component confirming the diagnosis. After 1 year of follow-up, the patient presented with similar complaints and MRI evidence of recurrence of the tumour. A comprehensive literature review revealed that half of the reported cases of this pattern recurred suggesting a possibly tenacious clinical course.