ABSTRACT
Magnetic resonance elastography (MRE) of the liver has emerged as the non-invasive standard for the evaluation of liver fibrosis in chronic liver diseases (CLDs). The utility of MRE in the evaluation of different CLD in both adults and children has been demonstrated in several studies, and MRE has been recommended by several clinical societies. Consequently, the clinical indications for evaluation of CLD with MRE have increased, and MRE is currently used as an add-on test during routine liver MRI studies or as a standalone test. To meet the increasing clinical demand, MRE is being installed in many academic and private practice imaging centers. There is a need for a comprehensive practical guide to help these practices to deliver high-quality liver MRE studies as well as troubleshoot the common issues with MRE to ensure smooth running of the service. This comprehensive clinical practice review summarizes the indications and provides an overview on why to use MRE, technical requirements, system set-up, patient preparation, acquiring the data, and interpretation.
Subject(s)
Elasticity Imaging Techniques , Liver Diseases , Adult , Child , Elasticity Imaging Techniques/methods , Humans , Liver/diagnostic imaging , Liver/pathology , Liver Cirrhosis/pathology , Liver Diseases/diagnostic imaging , Liver Diseases/pathology , Liver Function Tests , Magnetic Resonance Imaging/methodsABSTRACT
PURPOSE: Magnetic resonance (MR) elastography (E) is a noninvasive technique for quantifying liver stiffness (LS) for fibrosis. This study evaluates whether LS is associated with risk of developing radiation-induced liver disease (RILD) in patients receiving liver-directed radiation therapy (RT). METHODS AND MATERIALS: Based on prior studies, LS ≤3 kPa was considered normal and LS >3.0 kPa as representing fibrosis. RILD was defined as an increase in Child-Pugh (CP) score of ≥2 from baseline within 1 year of RT. Univariate and multivariate Cox models were used to assess correlation. RESULTS: One hundred two patients, 51 with primary liver tumors and 51 with liver metastases, were identified with sufficient follow-up. In univariate models, pre-RT LS >3.0 kPa (hazard ratio [HR] 4.9; 95% confidence interval [CI], 1.6-14; P = .004), body mass index (BMI), clinical cirrhosis, CP score, albumin-bilirubin (ALBI) grade 2, primary liver tumor, and mean liver dose were significantly associated with risk of post-RT RILD. In a multivariate analysis, LS >3.0 and mean liver dose both were significantly associated with RILD risk. CONCLUSIONS: Elevated pre-RT LS is associated with an increased risk of RILD in patients receiving liver-directed RT.
ABSTRACT
The role of quantitative magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) techniques continues to grow and evolve in the evaluation of musculoskeletal tumors. In this review we discuss the MRI quantitative techniques of volumetric measurement, chemical shift imaging, diffusion-weighted imaging, elastography, spectroscopy, and dynamic contrast enhancement. We also review quantitative PET techniques in the evaluation of musculoskeletal tumors, as well as virtual surgical planning and three-dimensional printing.
Subject(s)
Bone Neoplasms/diagnostic imaging , Magnetic Resonance Imaging/methods , Muscle Neoplasms/diagnostic imaging , Positron-Emission Tomography/methods , Bone Neoplasms/therapy , Contrast Media , Humans , Image Enhancement/methods , Image Interpretation, Computer-Assisted/methods , Muscle Neoplasms/therapyABSTRACT
The viscoelastic properties of tissue are significantly altered with the development of tumors and these alterations can be assessed with magnetic resonance elastography (MRE). Accurate detection and characterization of malignant and benign lesions can be obtained by quantifying tumor stiffness, improving the specificity and diagnostic accuracy of conventional magnetic resonance imaging. Furthermore, MRE can be used to stratify patients for treatment based on risk of normal tissue toxicity and surgical considerations including consistency and adherence of the tumor to surrounding structures. MRE is a reliable reproducible technique demonstrated in studies that include both patients with cancer and normal volunteers, and an average technical failure rate of <1%. The addition of MRE into a multiparametric magnetic resonance imaging assessment may improve the diagnosis and treatment of cancer.
Subject(s)
Elasticity Imaging Techniques/methods , Magnetic Resonance Imaging/methods , Neoplasms/diagnostic imaging , Neoplasms/pathology , Elasticity , Female , Humans , Reproducibility of Results , Sensitivity and Specificity , ViscosityABSTRACT
Tissue mechanical properties are significantly altered with the development of cancer. Magnetic resonance elastography (MRE) is a noninvasive technique capable of quantifying tissue mechanical properties in vivo. This review describes the basic principles of MRE and introduces some of the many promising MRE methods that have been developed for the detection and characterization of cancer, evaluation of response to therapy, and investigation of the underlying mechanical mechanisms associated with malignancy.
Subject(s)
Elasticity Imaging Techniques/methods , Magnetic Resonance Imaging/methods , Neoplasms/diagnostic imaging , Neoplasms/pathology , Animals , Humans , Image Interpretation, Computer-Assisted , Neoplasms/diagnosis , Neoplasms/physiopathologyABSTRACT
PURPOSE: The overall goal is to develop magnetic resonance elastography derived shear stiffness as a biomarker for the early identification of chemotherapy response, allowing dose, agent type and treatment regimen to be tailored on a per patient basis, improving therapeutic outcome and minimizing normal tissue toxicity. The specific purpose of this study is to test the feasibility of this novel biomarker to measure the treatment response in a well-known chemotherapy model. METHODS: Tumors were grown in the right flank of genetically modified mice by subcutaneous injection of DoHH2 (non-Hodgkin's lymphoma) cells. Magnetic resonance elastography was used to quantify tumor stiffness before and after injection of a chemotherapeutic agent or saline. Histological tests were also performed on the tumors. RESULTS: A significant decrease (P < 0.0001) in magnetic resonance elastography-derived tumor shear stiffness was observed within 4 days of chemotherapy treatment, while no appreciable change was observed in saline-treated tumors. No significant change in volume occurred at this early stage, but there were decreased levels of cellular proliferation in chemotherapy-treated tumors. CONCLUSION: These results demonstrate that magnetic resonance elastography-derived estimates of shear stiffness reflect an initial response to cytotoxic therapy and suggest that this metric could be an early and sensitive biomarker of tumor response to chemotherapy.
