Imaging in rhabdomyosarcoma: a patient journey.

Rhabdomyosarcoma, although rare, is the most frequent soft tissue sarcoma in children and adolescents. It can present as a mass at nearly any site in the body, with most common presentations in the head and neck, genitourinary tract and extremities. The optimal diagnostic approach and management of rhabdomyosarcoma require a multidisciplinary team with multimodal treatment, including chemotherapy and local therapy. Survival has improved over the last decades; however, further improvement in management is essential with current 5-year overall survival ranging from 35% to 100%, depending on disease and patient characteristics. In the full patient journey, from diagnosis, staging, management to follow-up after therapy, the paediatric radiologist and nuclear physician are essential members of the multidisciplinary team. Recently, guidelines of the European paediatric Soft tissue sarcoma Study Group, the Cooperative Weichteilsarkom Studiengruppe and the Oncology Task Force of the European Society of Paediatric Radiology (ESPR), in an ongoing collaboration with the International Soft-Tissue Sarcoma Database Consortium, provided guidance for high-quality imaging. In this educational paper, given as a lecture during the 2022 postgraduate ESPR course, the multi-disciplinary team of our national paediatric oncology centre presents the journey of two patients with rhabdomyosarcoma and discusses the impact on and considerations for the clinical (paediatric) radiologist and nuclear physician. The key learning points of the guidelines and their implementation in clinical practice are highlighted and up-to-date insights provided for all aspects from clinical suspicion of rhabdomyosarcoma and its differential diagnosis, to biopsy, staging, risk stratification, treatment response assessment and follow-up.

Imaging features of hepatic sinusoidal obstruction syndrome or veno-occlusive disease in children.

Hepatic sinusoidal obstruction syndrome, also known as veno-occlusive disease, can occur as a complication of myeloablative chemotherapy, as a result of low-intensity chemotherapy-related liver toxicity or radiotherapy of the liver. Symptoms of sinusoidal obstruction syndrome can range from asymptomatic to liver dysfunction or severe disease with life-threatening acute multi-organ failure. Imaging features can suggest or support this clinical diagnosis. Familiarity with the imaging spectrum of sinusoidal obstruction syndrome is therefore important for both radiologists and clinical oncologists. Here, multi-modality radiologic appearances of sinusoidal obstruction syndrome in pediatric patients are illustrated, including outcome after follow-up.

Lipidomics in Nonalcoholic Fatty Liver Disease: Exploring Serum Lipids as Biomarkers for Pediatric Nonalcoholic Fatty Liver Disease.

OBJECTIVES: Disturbances in lipid metabolism play an important role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Using lipidomics, an analytical technique that is used to broadly survey lipid metabolism, we searched for biomarkers in plasma that are correlated with the presence of hepatic steatosis in children with obesity. METHODS: Lipidomics was performed in plasma samples of 21 children with obesity in whom steatosis was detected using proton magnetic resonance spectroscopy (H-MRS) and were compared with the lipidome of 21 samples of nonsteatotic subjects with obesity. RESULTS: Forty-two samples were analyzed (57% boys; median age 15 years). A total of 18 lipid classes constituting 839 different lipid species were identified. A statistically significant increase in alkyldiacylglycerol (TG[O]) and phosphatidylethanolamine (PE) species and a significant decrease in alkyl/alkenyl-phosphatidylethanolamine (PE[O]), alkyl/alkenyl-lysophosphatidylethanolamine (LPE[O]) and alkyl/alkenyl-phosphatidylcholine (PC[O]) was observed in children with hepatic steatosis compared with controls. Twelve individual lipid species of 3 lipid classes were significantly increased in steatotic subjects compared with controls. CONCLUSIONS: In this pilot study, we found statistically significant alterations in 5 major lipid classes and 12 individual lipid species in children with steatosis. These might be potential biomarkers for pediatric NAFLD. Lipidomic studies in larger cohorts of children are needed to determine the diagnostic value of these lipids and determine whether results can be generalized for different age groups and ethnic backgrounds.

Comparison of diagnostic accuracy of screening tests ALT and ultrasound for pediatric non-alcoholic fatty liver disease.

Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD). No direct comparison of these two modalities in children exists. We aimed to compare head-to-head the diagnostic accuracy of ALT and US and their combination for detecting NAFLD in children with obesity. Ninety-nine children with severe obesity underwent simultaneous serum-ALT and abdominal ultrasound (US steatosis score 0-3). Proton magnetic resonance spectroscopy was used as reference standard for detecting steatosis/NAFLD. ROC curve analyses were performed to determine diagnostic performance and to determine optimum screening cut-points aiming for a specificity ≥ 80%. The area under the ROC (AUROC) of ALT and US were not significantly different (0.74 and 0.70, respectively). At the optimal ALT threshold (≥40 IU/L), sensitivity was 44% and specificity was 89%. At the optimal US steatosis score (≥ 2), sensitivity was 51% and specificity was 80%. Combining ALT and US did not result in better accuracy than ALT or US alone.Conclusion: ALT and US have comparable and only moderate diagnostic accuracy for detecting hepatic steatosis in children with obesity. A stepwise screening strategy combining both methods does not improve diagnostic accuracy. What is Known: • Alanine aminotransferase (ALT) and ultrasound (US) are the most commonly used tools for detecting non-alcoholic fatty liver disease (NAFLD). • ALT and ultrasound have mediocre accuracy in detecting steatosis in children with obesity. What is New: • In a head-to-head comparison, the difference in diagnostic accuracy of ALT and ultrasound in detecting steatosis is not significant. • A stepwise screening strategy combining both methods does not improve diagnostic accuracy.

Iron storage in liver, bone marrow and splenic Gaucheroma reflects residual disease in type 1 Gaucher disease patients on treatment.

Gaucher disease (GD) is a lysosomal storage disorder characterized by the storage of glycosphingolipids in macrophages. Despite effective therapy, residual disease is present in varying degrees and may be associated with late complications, such as persistent bone or liver disease and increased cancer risk. Gaucher macrophages are capable of storing iron and locations of residual disease may thus be detectable with iron imaging. Forty type 1 GD (GD1) patients and 40 matched healthy controls were examined using a whole-body magnetic resonance imaging protocol consisting of standard sequences, allowing analysis of iron content per organ, expressed as R2* (Hz). Median R2* values were significantly elevated in GD1 patients as compared to healthy controls in liver [41 Hz (range 29-165) vs. 38 Hz (range 28-53), P < 0·01], femoral bone marrow [54 Hz (range 37-129) vs. 49 Hz (range 39-69), P = 0·036] and vertebral bone marrow (118 Hz (range 82-210) vs. 105 Hz (range 76-149), P < 0·01). In the spleen, primarily focal Gaucher lesions known as Gaucheroma were found to have increased R2* values. R2* values of liver, spleen and vertebral bone marrow strongly correlated with serum ferritin levels. GD1 patients with persistent hyperferritinaemia demonstrate increased iron levels in liver and bone marrow, which may carry a risk for liver fibrosis and cancer.

Imaging characteristics of focal splenic and hepatic lesions in type 1 Gaucher disease.

In Gaucher disease (GD) imaging of liver and spleen is part of routine follow-up of GD patients. Focal lesions in both liver and spleen are frequently reported at radiological examinations. These lesions often represent benign accumulations of Gaucher cells, so-called "gaucheroma", but malignancies, especially hepatocellular carcinoma, are more frequently found in GD as well. We report the imaging characteristics of all focal lesions in liver and spleen in the Dutch GD cohort. Of the 95 GD1 patients, 40% had focal splenic and/or hepatic lesions, associated with more severe GD. Lesions identified as gaucheroma have variable imaging characteristics: hyper- to hypointense on MRI, hyper- or hypoechoic on US and hypodense on computed tomography (CT). Hepatic lesions were classified as simple cysts or haemangioma based upon imaging characteristics. Focal nodular hyperplasia (FNH), gaucheroma and hepatocellular carcinoma (HCC) could not be distinguished by conventional US, CT or MRI. Growth of these lesions and/or characteristics of HCC on dynamic CT or MRI and pathology was used to identify or rule out HCC. We propose a decision-making algorithm including the use of growth and dynamic CT- or MRI-scanning to characterize lesions.

Non-invasive evaluation of liver fibrosis: a comparison of ultrasound-based transient elastography and MR elastography in patients with viral hepatitis B and C.

OBJECTIVE: To compare the diagnostic accuracy of TE and MRE and establish cutoff levels and diagnostic strategies for both techniques, enabling selection of patients for liver biopsy. METHODS: One hundred three patients with chronic hepatitis B or C and liver biopsy were prospectively included. Areas under curves (AUROC) were compared for TE and MRE for METAVIR fibrosis grade ≥ F2 and ≥F3. We defined cutoff values for selection of patients with F0-F1 (sensitivity >95%) and for significant fibrosis F2-F4 (specificity >95%). RESULTS: Following exclusions, 85 patients were analysed (65 CHB, 19 CHC, 1 co-infected). Fibrosis stages were F0 (n = 3), F1 (n = 53), F2 (n = 15), F3 (n = 8) and F4 (n = 6). TE and MRE accuracy were comparable [AUROCTE ≥ F2: 0.914 (95% CI: 0.857-0.972) vs. AUROCMRE ≥ F2: 0.909 (0.840-0.977), P = 0.89; AUROCTE ≥ F3: 0.895 (0.816-0.974) vs. AUROCMRE ≥ F3: 0.928 (0.874-0.982), P = 0.42]. Cutoff values of <5.2 and ≥8.9 kPa (TE) and <1.66 and ≥2.18 kPa (MRE) diagnosed 64% and 66% of patients correctly as F0-F1 or F2-F4. A conditional strategy in inconclusive test results increased diagnostic yield to 80%. CONCLUSION: TE and MRE have comparable accuracy for detecting significant fibrosis, which was reliably detected or excluded in two-thirds of patients. A conditional strategy further increased diagnostic yield to 80%. KEY POINTS: • Both ultrasound-based transient elastography and magnetic resonance elastography can assess hepatic fibrosis. • Both have comparable accuracy for detecting liver fibrosis in viral hepatitis. • The individual techniques reliably detect or exclude significant liver fibrosis in 66 %. • A conditional strategy for inconclusive findings increases the number of correct diagnoses.

Comparison of interobserver agreement of magnetic resonance elastography with histopathological staging of liver fibrosis.

PURPOSE: MR elastography (MRE) can serve as an accurate surrogate marker of liver fibrosis. For any diagnostic test that is to replace the current reference standard, interobserver agreement should be at least as good and preferably better. The objective of this study was to perform a head-to-head comparison of the interobserver agreements of MRE and liver fibrosis staging on biopsy in a single cohort of hepatitis patients. METHODS: One hundred and three patients with viral hepatitis B or C who had a liver biopsy underwent MRE. Two readers independently selected a region-of-interest (ROI) in the liver to derive elasticity values. Two pathologists first independently staged fibrosis on biopsies using the METAVIR classification and subsequently held a consensus meeting. Interobserver agreements of elasticity values and fibrosis stages were assessed with intraclass correlation coefficients (ICC). RESULTS: MRE and biopsy data were available for 85/103 patients. ICC of pathologists staging fibrosis was almost perfect at 0.91 (95% CI 0.86-0.94). ICC for MRE readers was significantly (P < 0.0001) higher at 0.99 (95% CI 0.98-1.00). CONCLUSIONS: Interobserver agreement for liver fibrosis staging was almost perfect for both histopathology and MRE, with a significant higher agreement for MRE. Its high interobserver agreement and reliable accuracy support the use of MRE as a non-invasive screening tool for liver fibrosis.

Cardiac MRI in diagnosis, prognosis, and follow-up of hypertrophic cardiomyopathy in children: current perspectives.

Hypertrophic Cardiomyopathy (HCM) is an inherited myocardial disease characterised by left ventricular hypertrophy, which carries an increased risk of life-threatening arrhythmias and sudden cardiac death. The age of presentation and the underlying aetiology have a significant impact on the prognosis and quality of life of children with HCM, as childhood-onset HCM is associated with high mortality risk and poor long-term outcomes. Accurate cardiac assessment and identification of the HCM phenotype are therefore crucial to determine the diagnosis, prognostic stratification, and follow-up. Cardiac magnetic resonance (CMR) is a comprehensive evaluation tool capable of providing information on cardiac morphology and function, flow, perfusion, and tissue characterisation. CMR allows to detect subtle abnormalities in the myocardial composition and characterise the heterogeneous phenotypic expression of HCM. In particular, the detection of the degree and extent of myocardial fibrosis, using late-gadolinium enhanced sequences or parametric mapping, is unique for CMR and is of additional value in the clinical assessment and prognostic stratification of paediatric HCM patients. Additionally, childhood HCM can be progressive over time. The rate, timing, and degree of disease progression vary from one patient to the other, so close cardiac monitoring and serial follow-up throughout the life of the diagnosed patients is of paramount importance. In this review, an update of the use of CMR in childhood HCM is provided, focussing on its clinical role in diagnosis, prognosis, and serial follow-up.

MR elastography of the liver: defining thresholds for detecting viscoelastic changes.

PURPOSE: To define thresholds for detecting significant change in liver viscoelasticity with magnetic resonance (MR) elastography, both for whole-liver measurements and for voxel-wise measurements in relation to spatial resolution. MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and all participants provided written informed consent. Thirty participants (16 volunteers and 14 patients with hepatitis B or C; 18 men; median age, 30.4 years; age range, 18.9-58.6 years) underwent imaging twice while in the same position (intraimage reproducibility), after repositioning (within-day reproducibility), and 1-4 weeks later (between-weeks reproducibility). MR elastography parameters comprised elasticity, viscosity, attenuation parameter α, and propagation parameter ß. Bland-Altman analysis was used to calculate repeatability indexes for each parameter. Analyses were performed in a region-of-interest and a voxel-by-voxel level. Voxel-wise results were calculated in relation to spatial resolution by applying Gaussian filtering to establish the optimal trade-off point between resolution and reproducibility. RESULTS: For elasticity, α, and ß, within-day and between-weeks results were significantly lower than intraimage results (P ≤ .018 for all). Within-day and between-weeks results did not differ significantly. Over-time changes of more than 22.2% for elasticity, 26.3% for viscosity, 26.8% for α, and 10.1% for ß represented thresholds for significant change. The optimal trade-off between spatial resolution and reproducibility was found at a filter size of 8-mm full width at half maximum (FWHM) for elasticity and propagation parameter ß and at 16-mm FWHM for viscosity and attenuation parameter α. CONCLUSION: Repositioning causes a significant decrease in the reproducibility of MR elastography. The propagation parameter ß is the most reliable parameter, with an over-time threshold for significant change of 10.1% and the ability to reproduce viscoelasticity up to a resolution of 8-mm FWHM. Online supplemental material is available for this article.

US cannot be used to predict the presence or severity of hepatic steatosis in severely obese adolescents.

PURPOSE: To evaluate the diagnostic accuracy of ultrasonography (US) for the assessment of hepatic steatosis in severely obese adolescents, with proton magnetic resonance (MR) spectroscopy as the reference standard, and to provide insight on the influence of prevalence on predictive values by calculating positive and negative posttest probabilities. MATERIALS AND METHODS: This prospective study was institutional review board approved. All participants, and/or their legal representatives, gave written informed consent. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the overall presence of steatosis and for the presence of substantial (moderate to severe) steatosis. Positive and negative posttest probabilities were calculated and plotted against prevalence. RESULTS: A total of 104 children (47 male, 57 female) were prospectively included. Mean age was 14.5 years (range, 8.3-18.9 years) and mean age-adjusted standard deviation body mass index (BMI) score (BMI z score) was 3.3 (range, 2.6-4.1). The overall prevalence of hepatic steatosis was 46.2% (48 of 104). Sensitivity of US was 85.4% (41 of 48), specificity was 55.4% (31 of 56), PPV was 62.1% (41 of 66), and NPV was 81.6% (31 of 38). The prevalence of substantial steatosis was 15.4% (16 of 104), with US sensitivity of 75.0% (12 of 16) and specificity of 87.5% (77 of 88). PPV was 52.2% (12 of 23) and NPV was 95.1% (77 of 81). Plotting of posttest probabilities against prevalence for both disease degrees demonstrated how disease prevalence influences US accuracy. CONCLUSION: Positive US results in severely obese adolescents cannot be used to accurately predict the presence and severity of hepatic steatosis, and additional imaging is required. Negative US results exclude the presence of substantial steatosis with acceptable accuracy. Steatosis prevalence differs among specific populations, strongly influencing posttest probabilities.

The diagnostic accuracy of US, CT, MRI and 1H-MRS for the evaluation of hepatic steatosis compared with liver biopsy: a meta-analysis.

OBJECTIVE: To meta-analyse the diagnostic accuracy of US, CT, MRI and 1H-MRS for the evaluation of hepatic steatosis. METHODS: From a comprehensive literature search in MEDLINE, EMBASE, CINAHL and Cochrane (up to November 2009), articles were selected that investigated the diagnostic performance imaging techniques for evaluating hepatic steatosis with histopathology as the reference standard. Cut-off values for the presence of steatosis on liver biopsy were subdivided into four groups: (1) >0, >2 and >5% steatosis; (2) >10, >15 and >20%; (3) >25, >30 and >33%; (4) >50, >60 and >66%. Per group, summary estimates for sensitivity and specificity were calculated. The natural-logarithm of the diagnostic odds ratio (lnDOR) was used as a single indicator of test performance. RESULTS: 46 articles were included. Mean sensitivity estimates for subgroups were 73.3-90.5% (US), 46.1-72.0% (CT), 82.0-97.4% (MRI) and 72.7-88.5% (1H-MRS). Mean specificity ranges were 69.6-85.2% (US), 88.1-94.6% (CT), 76.1-95.3% (MRI) and 92.0-95.7% (1H-MRS). Overall performance (lnDOR) of MRI and 1H-MRS was better than that for US and CT for all subgroups, with significant differences in groups 1 and 2. CONCLUSION: MRI and 1H-MRS can be considered techniques of choice for accurate evaluation of hepatic steatosis.

Nonalcoholic fatty liver disease and cardiovascular risk in children with obesity.

OBJECTIVE: Nonalcoholic fatty liver disease (NAFLD) has been recognized as an independent risk factor for cardiovascular disease in adults. It has not been established whether NAFLD is related to early atherosclerotic changes in children. METHODS: In a cross-sectional study, 78 non diabetic, non smoking children with severe obesity were evaluated for NAFLD. Proton magnetic resonance spectroscopy was used to detect liver steatosis and serum ALT was used as a surrogate marker for steatohepatitis. Carotid intima-media thickness (CIMT) and arterial wall stiffness were measured using ultrasound. RESULTS: Steatosis was present in 41 (53%) of subjects. Of these children, 26 out of 41 (63%) had elevated ALT levels. No differences in CIMT and arterial wall stiffness were observed between those without and with steatosis and those with steatosis plus elevated ALT levels [CIMT = 0.47 (±0.06), 0.48 (±0.06) and 0.48 (±0.07) mm, respectively; stiffness = 2.78 (±0.50), 3.00 (±0.81), and 2.90 (±0.78), respectively]. Steatosis and ALT were not correlated to CIMT (r = -0.02 and -0.14, respectively) or arterial wall stiffness (r = 0.13 and -0.11, respectively). CONCLUSIONS: In this study, no relationship between NAFLD and early atherosclerotic changes in children was observed. An atherogenic effect of steatohepatitis (NASH) on pediatric age and long-term atherogenic consequences of simple steatosis cannot be excluded based on this study.

Liver fibrosis in type I Gaucher disease: magnetic resonance imaging, transient elastography and parameters of iron storage.

Long term liver-related complications of type-1 Gaucher disease (GD), a lysosomal storage disorder, include fibrosis and an increased incidence of hepatocellular carcinoma. Splenectomy has been implicated as a risk factor for the development of liver pathology in GD. High ferritin concentrations are a feature of GD and iron storage in Gaucher cells has been described, but iron storage in the liver in relation to liver fibrosis has not been studied. Alternatively, iron storage in GD may be the result of iron supplementation therapy or regular blood transfusions in patients with severe cytopenia. In this pilot study, comprising 14 type-1 GD patients (7 splenectomized, 7 non-splenectomized) and 7 healthy controls, we demonstrate that liver stiffness values, measured by Transient Elastography and MR-Elastography, are significantly higher in splenectomized GD patients when compared with non-splenectomized GD patients (p = 0.03 and p = 0.01, respectively). Liver iron concentration was elevated (>60±30 µmol/g) in 4 GD patients of whom 3 were splenectomized. No relationship was found between liver stiffness and liver iron concentration. HFE gene mutations were more frequent in splenectomized (6/7) than in non-splenectomized (2/7) participants (p = 0.10). Liver disease appeared more advanced in splenectomized than in non-splenectomized patients. We hypothesize a relationship with excessive hepatic iron accumulation in splenectomized patients. We recommend that all splenectomized patients, especially those with evidence of substantial liver fibrosis undergo regular screening for HCC, according to current guidelines.

Accuracy of prediction scores and novel biomarkers for predicting nonalcoholic fatty liver disease in obese children.

BACKGROUND: Accurate prediction scores for liver steatosis are demanded to enable clinicians to noninvasively screen for nonalcoholic fatty liver disease (NAFLD). Several prediction scores have been developed, however external validation is lacking. OBJECTIVE: The aim was to determine the diagnostic accuracy of four existing prediction scores in severely obese children, to develop a new prediction score using novel biomarkers and to compare these results to the performance of ultrasonography. DESIGN AND RESULTS: Liver steatosis was measured using proton magnetic resonance spectroscopy in 119 severely obese children (mean age 14.3 ± 2.1 years, BMI z-score 3.35 ± 0.35). Prevalence of steatosis was 47%. The four existing predictions scores ("NAFLD liver fat score," "fatty liver index," "hepatic steatosis index," and the pediatric prediction score) had only moderate diagnostic accuracy in this cohort (positive predictive value (PPV): 70, 61, 61, 69% and negative predictive value (NPV) 77, 69, 68, 75%, respectively). A new prediction score was built using anthropometry, routine biochemistry and novel biomarkers (leptin, adiponectin, TNF-alpha, IL-6, CK-18, FGF-21, and adiponutrin polymorphisms). The final model included ALT, HOMA, sex, and leptin. This equation (PPV 79% and NPV 80%) did not perform substantially better than the four other equations and did not outperform ultrasonography for excluding NAFLD (NPV 82%). CONCLUSION: The conclusion is in severely obese children and adolescents existing prediction scores and the tested novel biomarkers have insufficient diagnostic accuracy for diagnosing or excluding NAFLD.