RESUMO
Hepatocellular carcinoma (HCC) is the most common primary liver cancer and a major public health problem worldwide. Liver fibrosis is closely correlated with liver functional reserve and the risk of HCC development. Meanwhile, malignant tumors generally have high cellularity compared to benign tumors, which results in increased stiffness. Magnetic resonance elastography (MRE) has emerged as a new non-invasive technique for assessing tissue stiffness with excellent diagnostic accuracy, not only for assessing liver fibrosis but also for measuring tumor stiffness. Recent studies provide new evidence that MRE may play an important role in the management of patients with HCC and show several novel clinical applications, such as predicting the development of HCC, differentiating between benign/malignant liver lesions (FLL) and HCC pathological grades, assessing treatment response, and predicting recurrence after treatment, although some findings are controversial. Therefore, we conducted this review to summarize these novel applications of MRE in HCC patients and also discuss their limitations and future advancement.
Assuntos
Carcinoma Hepatocelular , Técnicas de Imagem por Elasticidade , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Técnicas de Imagem por Elasticidade/métodos , Fígado/patologia , Prognóstico , Cirrose Hepática/diagnóstico por imagem , Cirrose Hepática/patologia , Imageamento por Ressonância Magnética/métodosRESUMO
OBJECTIVES: To evaluate the feasibility and diagnostic value of using a 2D spin-echo MR elastography (SE-MRE) sequence at 3.0 Tesla for solid focal liver lesions (FLL) characterization. METHODS: This prospective study included 55 patients with solid FLL (size > 20 mm), who underwent liver SE-MRE at 3 Tesla between 2016 and 2019. Stiffness measurements were performed by two independent readers blinded to the complete MRI exam or patient information. Histological confirmation or typical behavior on the complete MRI exam evaluated in consensus by expert abdominal radiologists was used as reference standard. FLLs were grouped and compared (malignant vs. benign) using the Mann-Whitney and Kruskal-Wallis tests. MRE diagnostic performance was assessed, and stiffness cutoffs were obtained by analysis of ROC curves from accuracy maximization. A linear regression plot was used to evaluate inter-rater agreement for FLLs stiffness measurements. p values < 0.05 were considered statistically significant. RESULTS: The final study group comprised 57 FLLs (34 malignant, 23 benign). Stiffness measurements were technically successful in 91.23% of lesions. To both readers, the median stiffness of the lesions categorized as benign was 4.5 ± 1.5 kPa and in the malignant group 6.8 ± 1.7 and 7.5 ± 1.5 kPa depending on the reader. A cutoff of 5.8 kPa distinguished malignant and benign lesions with 88% specificity and 75-85% accuracy depending on the reader. The inter-rater agreement was 0.90 ± 0.04 with a correlation coefficient of 0.94. CONCLUSION: 2D-SE-MRE at 3.0 T provides high specificity and PPV to differentiate benign from malignant liver lesions. Trial registration 18FFUA-A02.
Assuntos
Técnicas de Imagem por Elasticidade , Neoplasias Hepáticas , Humanos , Fígado/diagnóstico por imagem , Neoplasias Hepáticas/diagnóstico por imagem , Imageamento por Ressonância Magnética , Estudos Prospectivos , Reprodutibilidade dos TestesRESUMO
PURPOSE: Magnetic resonance elastography (MRE) measures stiffness of soft tissues by analyzing their spatial harmonic response to externally induced shear vibrations. Many MRE methods use inversion-based reconstruction approaches, which invoke first- or second-order derivatives by finite difference operators (first- and second-FDOs) and thus give rise to a biased frequency dispersion of stiffness estimates. METHODS: We here demonstrate analytically, numerically, and experimentally that FDO-based stiffness estimates are affected by (1) noise-related underestimation of values in the range of high spatial wave support, that is, at lower vibration frequencies, and (2) overestimation of values due to wave discretization at low spatial support, that is, at higher vibration frequencies. RESULTS: Our results further demonstrate that second-FDOs are more susceptible to noise than first-FDOs and that FDO dispersion depends both on signal-to-noise ratio (SNR) and on a lumped parameter A, which is defined as wavelength over pixel size and over a number of pixels per stencil of the FDO. Analytical FDO dispersion functions are derived for optimizing A parameters at a given SNR. As a simple rule of thumb, we show that FDO artifacts are minimized when A/2 is in the range of the square root of 2SNR for the first-FDO or cubic root of 5SNR for the second-FDO. CONCLUSIONS: Taken together, the results of our study provide an analytical solution to a long-standing, well-recognized, yet unsolved problem in MRE postprocessing and might thus contribute to the ongoing quest for minimizing inversion artifacts in MRE.
Assuntos
Técnicas de Imagem por Elasticidade , Artefatos , Imageamento por Ressonância Magnética , Razão Sinal-Ruído , VibraçãoRESUMO
La fibrosis es un destino donde convergen variados trastornos hepáticos. Al tratarse de un proceso dinámico y reversible, su detección temprana y una intervención terapéutica oportuna, pueden frenar su progresión. La elastografía por resonancia magnética (ERM), es un método no invasivo con notable eficacia para la valoración del grado de fibrosis hepática. La tendencia actual es combinar esa técnica con secuencias de cuantificación de lípidos y hierro, lo cual permite un abordaje multiparamétrico de los trastornos difusos del hígado.
Fibrosis is a common destination where multiple liver disorders converge. Due to its dynamic and reversible process, an early detection and timely therapeutic intervention can interrupt its progression. Magnetic Resonance Elastography (MRE) is a non-invasive method with remarkable efficacy for assessing the degree of liver fibrosis. The current trend is to combine this technique with lipid and iron quantification sequences, which allows a multiparametric approach to diffuse liver disorders.
Assuntos
Humanos , Técnicas de Imagem por Elasticidade/métodos , Cirrose Hepática/diagnóstico por imagem , Espectroscopia de Ressonância Magnética , Técnicas de Imagem por Elasticidade/tendências , Fígado Gorduroso/diagnóstico por imagem , Fígado/diagnóstico por imagemRESUMO
AIM: Multiparametric magnetic resonance imaging (mpMRI) may help determine the metabolic profile of patients with obesity and metabolic syndrome in addition to their clinical and laboratory biomarkers for diagnosis and monitoring. An abbreviated mpMRI protocol may be a faster, less-costly, and easier to perform alternative for the diagnosis, treatment, and follow-up of patients with NAFLD and for use in clinical trials. OBJECTIVE: To evaluate an abbreviated mpMRI protocol tailored to analyze quantitative imaging features of patients with obesity and NAFLD and assess its use during treatment. METHODS: This prospective study included patients with obesity and NAFLD to perform a quantitative analysis of liver fat and iron content, stiffness, as well as the visceral adipose tissue (VAT) during the course of a physical exercise-based treatment regimen. RESULTS: Longitudinal improvements in imaging features were observed in patients with good response to treatment, in accordance with improvements in biochemical and anthropometric biomarkers. CONCLUSION: An abbreviated mpMRI protocol consisting of liver fat and iron quantification, MR elastography, and VAT measurements is a feasible, less-costly, and accessible option for screening and monitoring of patients with obesity, NAFLD, and metabolic syndrome.
Assuntos
Terapia por Exercício , Imageamento por Ressonância Magnética/métodos , Hepatopatia Gordurosa não Alcoólica/diagnóstico por imagem , Hepatopatia Gordurosa não Alcoólica/terapia , Adulto , Idoso , Biomarcadores/análise , Feminino , Humanos , Gordura Intra-Abdominal/diagnóstico por imagem , Masculino , Síndrome Metabólica/diagnóstico por imagem , Síndrome Metabólica/terapia , Pessoa de Meia-Idade , Obesidade/complicações , Obesidade/terapia , Estudos ProspectivosRESUMO
BACKGROUND: The presence of liver fibrosis is the common denominator in numerous chronic liver diseases that can progress to fibrosis and hepatocellular carcinoma. Most important, with respect to frequency, are viral hepatitis and non-alcoholic fatty liver disease, the prevalence of which is increasing in epidemic proportions. Liver biopsy, albeit imperfect, continues to be the criterion standard, but in many clinical situations tends to be replaced with noninvasive imaging methods. OBJECTIVES: The aim of the present article was to describe our imaging department experience with magnetic resonance elastography and to analyze and discuss recently published results in gastroenterology, hepatology, and radiology from other authors in the literature, complemented with a PubMed search covering the last 10 years. RESULTS AND CONCLUSIONS: Magnetic resonance elastography is an efficacious, noninvasive method with results that are concordant with liver biopsy. It is superior to ultrasound elastography because it evaluates a much greater volume of hepatic tissue and shows the often heterogeneous lesion distribution. The greatest advantage of the magnetic resonance protocol described is the fact that it quantifies fibrosis, fat content, and iron content in the same 25min examination specifically directed for that purpose, resulting in a favorable cost-benefit ratio for the patient and/or institution.
Assuntos
Técnicas de Imagem por Elasticidade/métodos , Cirrose Hepática/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Hepatopatia Gordurosa não Alcoólica/diagnóstico por imagem , Siderose/diagnóstico por imagem , HumanosRESUMO
Management of pediatric chronic liver disease is limited by lack of validated noninvasive biomarkers of histologic severity. We demonstrate that magnetic resonance elastography is feasible and accurate in detecting significant hepatic fibrosis in a case series of 35 children with chronic liver disease, including severely obese children.