RESUMEN
OBJECTIVE: The purpose of the study was to assess the additional value of magnetic resonance (MR) elastography (MRE) to contrast-enhanced (ce) MR imaging (MRI) for breast lesion characterisation. METHODS: Fifty-seven suspected breast lesions in 57 patients (mean age 52.4 years) were examined by ce MRI and MRE. All lesions were classified into BI-RADS categories. Viscoelastic parameters, e.g. alpha0 as an indicator of tissue stiffness, were calculated. Histology of the lesions was correlated with BI-RADS and viscoelastic properties. The positive predictive value (PPV) for malignancy, and the sensitivity and specificity of ce MRI were calculated. Receiver-operating characteristics (ROC) curves were separately calculated for both ce MRI and viscoelastic properties and conjoined to analyse the accuracy of diagnostic performance. RESULTS: The lesions (mean size 27.6 mm) were malignant in 64.9% (n = 37) of cases. The PPV for malignancy was significantly (p < 0.0001) dependent on BI-RADS classification. The sensitivity of ce MRI for breast cancer detection was 97.3% (36/37), whereas specificity was 55% (11/20). If ce MRI was combined with alpha0, the diagnostic accuracy could be significantly increased (p < 0.05; AUC(ce MRI) = 0.93, AUC(combined) = 0.96). CONCLUSIONS: In this study, the combination of MRE and ce MRI could increase the diagnostic performance of breast MRI. Further investigations of larger cohorts and smaller lesions (in particular those only visible on MRI) are necessary to validate these results.
Asunto(s)
Neoplasias de la Mama/diagnóstico , Diagnóstico por Imagen de Elasticidad/métodos , Gadolinio DTPA , Aumento de la Imagen/métodos , Imagen por Resonancia Magnética/métodos , Medios de Contraste , Femenino , Humanos , Persona de Mediana Edad , Proyectos Piloto , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The purpose of this analysis is to explore the potential diagnostic gain provided by the viscoelastic shear properties of breast lesions for the improvement of the specificity of contrast enhanced dynamic MR mammography (MRM). The assessment of viscoelastic properties is done via dynamic MR elastography (MRE) and it is demonstrated that the complex shear modulus of in vivo breast tissue follows within the frequency range of clinical MRE a power law behavior. Taking benefit of this frequency behavior, data are interpreted in the framework of the exact model for wave propagation satisfying the causality principle. This allows to obtain the exponent of the frequency power law from the complex shear modulus at one single frequency which is validated experimentally. Thereby, scan time is drastically reduced. It is observed that malignant tumors obtain larger exponents of the power law than benign tumors indicating a more liquid-like behavior. The combination of the Breast Imaging Reporting and Data System (BIRADS) categorization obtained via MRM with viscoelastic information leads to a substantial rise in specificity. Analysis of 39 malignant and 29 benign lesions shows a significant diagnostic gain with an increase of about 20% in specificity at 100% sensitivity.
Asunto(s)
Neoplasias de la Mama/diagnóstico , Diagnóstico por Imagen de Elasticidad/métodos , Gadolinio DTPA , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Medios de Contraste , Femenino , Humanos , Mamografía/métodos , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
OBJECTIVES: We sought to investigate the potential value of magnetic resonance (MR) elastography to improve the differentiation between benign and malignant tumors. MATERIAL AND METHODS: Measurements of 5 patients with 6 malignant lesions, 11 patients with benign lesions, and 4 patients with no lesions at all were performed at 1.5 Tesla. After breast MR imaging, MR elastography was performed as a targeted measurement. Low-frequency mechanical waves (65 Hz) were transmitted into the breast tissue using an oscillator and were displayed by means of a MR sequence within the phase of the MR image. After reconstruction, the viscoelastic information was correlated with the signal intensity and morphology data. RESULTS: All examinations were technically successful realized in approximately 25 minutes. Malignant tumors documented higher values of elasticity than benign corresponding with signal intensity and morphologic data. CONCLUSION: A good separation exists between benign and malignant lesions in elasticity, corresponding with specific signal intensity and morphologic data. Further clinical studies with a larger number of patients are needed for extended validation.
Asunto(s)
Neoplasias de la Mama/diagnóstico , Elasticidad , Aumento de la Imagen/instrumentación , Procesamiento de Imagen Asistido por Computador/instrumentación , Imagen por Resonancia Magnética/instrumentación , Ultrasonografía Mamaria , Adolescente , Adulto , Neoplasias de la Mama/diagnóstico por imagen , Neoplasias de la Mama/patología , Diagnóstico Diferencial , Femenino , Humanos , Persona de Mediana EdadRESUMEN
OBJECTIVES: The objectives of this study were to assess practicability, outcome, and possible advantages of magnetic resonance imaging (MRI)-guided localizations with modified embolization coils for exclusively MRI-detected suspicious breast lesions. MATERIALS AND METHODS: We performed 131 MRI-guided preoperative localizations in 105 patients with exclusively MRI-detected breast lesions. Contrast-enhanced, T1-weighted, 3-dimensional gradient echo sequences were used for imaging. Breast fixation and needle guidance were achieved by a perforated plate. Lesion localization was performed with a modified embolization coil. The distance between coil and lesion was measured. Results of specimen radiography and histopathology were analyzed. RESULTS: Thirty-four of 131 lesions (26%) were malignant. Lesion localization and excision was successful in all patients. The mean distance between the coil and the lesion was 0.5 mm (+/-1.7 mm standard deviation). CONCLUSIONS: Exact MRI-guided preoperative localization of exclusively MRI-detected breast lesions by using a modified embolization coil is feasible with excellent precision. Advantages over wire localization procedures are the possibility of specimen x-ray and the independence from time and place of operation.
Asunto(s)
Neoplasias de la Mama/diagnóstico , Imagen por Resonancia Magnética/instrumentación , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/cirugía , Medios de Contraste , Embolización Terapéutica/instrumentación , Femenino , Humanos , Aumento de la Imagen , Persona de Mediana EdadRESUMEN
Elastography is a technique to assess the viscoelastic properties of tissue by measuring an acoustic wave propagating though the object. Here, the technique is applied in the course of standard MR mammography to 15 patients with different pathologies (six breast cancer cases, six fibroadenoma cases and three mastopathy cases). Low-frequency mechanical waves are coupled longitudinally into the tissue in order to obtain sufficient wave amplitude throughout the entire breast. This leads to the presence of a substantial fraction of compressional waves, which contribute to the total displacement field. It is shown theoretically that the correct evaluation of these contributions from the compressional wave is rather difficult due to the almost incompressible nature of tissue. To overcome this problem, it is proposed to apply the curl-operator to the measured displacement field in order to completely remove contributions from the compressional wave. Results from simulations and a breast phantom demonstrate the feasibility of the technique. The in vivo results show a good separation between breast cancer and benign fibroadenoma utilizing the shear modulus. Breast cancer appears on average 2.2 (P<.001) times stiffer. All breast cancer cases showed a good delineation to the surrounding breast tissue with an average elevation of a factor of 3.3 (P< 1.4 x 10(-6)). The results as obtained for the shear viscosity do not indicate to be useful for separating benign from malignant lesions.