Fat saturation in breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI): comparison between DIXON and SPAIR techniques

Introdução – A ressonância magnética (RM) mamária com injeção de contraste é uma ferramenta indispensável para a caracterização de lesões mamárias. Para tal, é fulcral uma boa capacidade de saturação de gordura de forma a delimitar as lesões observadas. Este trabalho tem como objetivo analisar quantitativa e qualitativamente as técnicas de saturação de gordura em RM mamária, nomeadamente as técnicas SPAIR e Dixon. Metodologia – Utilizou-se um equipamento de RM de 1,5T com bobina específica para a mama. Aplicou-se, durante o exame, uma sequência adicional em que a técnica de saturação de gordura utilizada foi a Dixon. Posteriormente foram analisadas as imagens obtidas com as técnicas SPAIR e Dixon e colocadas regiões de interesse (ROI) na lesão, na glândula mamária, no tecido adiposo e no ar. Estes valores de sinal obtidos foram registados e calcularam-se as relações sinal-ruído (SNR), contraste-ruído (CNR) e uniformidade de saturação de gordura para as mesmas estruturas a analisar e nas distintas sequências. Resultados – Verificou-se que a técnica de supressão de gordura Dixon apresenta resultados quantitativos e qualitativos superiores à técnica SPAIR. Conclusões – Recomenda-se a utilização da técnica Dixon para saturação de gordura nas sequências de estudo dinâmico com agente de contraste, especificamente nos estudos de RM mamária.ABSTRACT: Introduction – Breast MRI with contrast injection is an indispensable tool for the characterization of breast lesions. To achieve this, good fat saturation is important in order to delimit the lesions. This study aims to assess quantitatively and qualitatively the fat saturation techniques in breast MRI, including SPAIR and Dixon techniques. Materials and methods – The study was performed in 1.5T MRI equipment and a specific breast coil was used. The study included an additional sequence with the Dixon fat saturation technique. Subsequently, the images obtained were analyzed and specifics ROI were placed in the lesion, mammary gland, adipose tissue and air, for both SPAIR and Dixon technique images. The obtained signal values were registered and, the SNR, CNR and uniformity of fat saturation were calculated for all mentioned structures. Results – It was found that the fat suppression technique Dixon quantitative and qualitative results are better than the technique SPAIR. Conclusions – From this study, the use of the Dixon technique for fat saturation is recommended in the dynamic study sequences with contrast agent, specifically in breast MRI studies

Análise quantitativa da saturação de gordura em ressonância magnética mamária: comparação das técnicas SPAIR e DIXON

Introdução – A ressonância magnética (RM) mamária com injeção de contraste é uma ferramenta indispensável para a caracterização de lesões mamárias. Para tal, é fulcral uma boa capacidade de saturação de gordura de forma a delimitar as lesões observadas. Este trabalho tem como objetivo analisar quantitativa e qualitativamente as técnicas de saturação de gordura em RM mamária, nomeadamente as técnicas SPAIR e Dixon. Metodologia – Utilizou-se um equipamento de RM de 1,5T com bobina específica para a mama. Aplicou-se, durante o exame, uma sequência adicional em que a técnica de saturação de gordura utilizada foi a Dixon. Posteriormente foram analisadas as imagens obtidas com as técnicas SPAIR e Dixon e colocadas regiões de interesse (ROI) na lesão, na glândula mamária, no tecido adiposo e no ar. Estes valores de sinal obtidos foram registados e calcularam-se as relações sinal-ruído (SNR), contraste-ruído (CNR) e uniformidade de saturação de gordura para as mesmas estruturas a analisar e nas distintas sequências. Resultados – Verificou-se que a técnica de supressão de gordura Dixon apresenta resultados quantitativos e qualitativos superiores à técnica SPAIR. Conclusões – Recomenda-se a utilização da técnica Dixon para saturação de gordura nas sequências de estudo dinâmico com agente de contraste, especificamente nos estudos de RM mamária

Fat saturation in breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI): comparison between DIXON and SPAIR techniques

Introduction – Breast MRI with contrast injection is an indispensable tool for the characterization of breast lesions. To achieve this, good fat saturation is important in order to delimit the lesions. This study aims to assess quantitatively and qualitatively the fat saturation techniques in breast MRI, including SPAIR and Dixon techniques. Materials and methods – The study was performed in 1.5T MRI equipment and a specific breast coil was used. The study included an additional sequence with the Dixon fat saturation technique. Subsequently, the images obtained were analyzed and specifics ROI were placed in the lesion, mammary gland, adipose tissue and air, for both SPAIR and Dixon technique images. The obtained signal values were registered and, the SNR, CNR and uniformity of fat saturation were calculated for all mentioned structures. Results – It was found that the fat suppression technique Dixon quantitative and qualitative results are better than the technique SPAIR. Conclusions – From this study, the use of the Dixon technique for fat saturation is recommended in the dynamic study sequences with contrast agent, specifically in breast MRI studies

Sensitivity of MRI-Guided Near-Infrared Spectroscopy Clinical Breast Exam Data and Its Impact on Diagnostic Performance

In this study, data from breast MRI-guided near infrared spectroscopy (NIRS) exams delivered to 44 patients scheduled for surgical resection (ending in 16 benign and 28 malignant diagnoses) were analyzed using a spatial sensitivity metric to quantify the adequacy of the optical measurements for interrogating the tumor region of interest, as derived from the concurrent MRI scan. Along with positional sensitivity, the incorporation of spectral priors and the selection of an appropriate regularization parameter in the image reconstruction were considered, and found to influence the diagnostic accuracy of the recovered images. Once optimized, the MRI/NIRS data was able to differentiate the malignant from benign lesions through both total hemoglobin (p = 0.0037) and tissue optical index (p = 0.00019), but required the relative spatial sensitivity of the optical measurement data to each lesion to be above 1%. Spectral constraints implemented during the reconstruction were required to obtain statistically significant diagnostic information from images of H2O, lipids, and Tissue Optical Index (TOI). These results confirm the need for optical systems that have homogenous spatial coverage of the breast while still being able to accommodate the normal range of breast sizes

Collagen Complexity Spatially Defines Microregions of Total Tissue Pressure in Pancreatic Cancer.

The poor efficacy of systemic cancer therapeutics in pancreatic ductal adenocarcinoma (PDAC) is partly attributed to deposition of collagen and hyaluronan, leading to interstitial hypertension collapsing blood and lymphatic vessels, limiting drug delivery. The intrinsic micro-regional interactions between hyaluronic acid (HA), collagen and the spatial origins of mechanical stresses that close off blood vessels was investigated here. Multiple localized pressure measurements were analyzed with spatially-matched histochemical images of HA, collagen and vessel perfusion. HA is known to swell, fitting a linear elastic model with total tissue pressure (TTP) increasing above interstitial fluid pressure (IFP) directly with collagen content. However, local TTP appears to originate from collagen area fraction, as well as increased its entropy and fractal dimension, and morphologically appears to be maximized when HA regions are encapsulated by collagen. TTP was inversely correlated with vascular patency and verteporfin uptake, suggesting interstitial hypertension results in vascular compression and decreased molecular delivery in PDAC. Collagenase injection led to acute decreases in total tissue pressure and increased drug perfusion. Large microscopic variations in collagen distributions within PDAC leads to microregional TPP values that vary on the hundred micron distance scale, causing micro-heterogeneous limitations in molecular perfusion, and narrows viable treatment regimes for systemically delivered therapeutics

Review of optical breast imaging and spectroscopy

Diffuse optical imaging and spectroscopy of the female breast is an area of active research. We review the present status of this field and discuss the broad range of methodologies and applications. Starting with a brief overview on breast physiology, the remodeling of vasculature and extracellular matrix caused by solid tumors is highlighted that is relevant for contrast in optical imaging. Then, the various instrumental techniques and the related methods of data analysis and image generation are described and compared including multimodality instrumentation, fluorescence mammography, broadband spectroscopy, and diffuse correlation spectroscopy. We review the clinical results on functional properties of malignant and benign breast lesions compared to host tissue and discuss the various methods to improve contrast between healthy and diseased tissue, such as enhanced spectroscopic information, dynamic variations of functional properties, pharmacokinetics of extrinsic contrast agents, including the enhanced permeability and retention effect. We discuss research on monitoring neoadjuvant chemotherapy and on breast cancer risk assessment as potential clinical applications of optical breast imaging and spectroscopy. Moreover, we consider new experimental approaches, such as photoacoustic imaging and long-wavelength tissue spectroscopy

Análise quantitativa da saturação de gordura em ressonância magnética mamária: comparação das técnicas SPAIR e DIXON

Mestrado em Radiações Aplicadas às Tecnologias da Saúde - Ramo de especialização: Ressonância MagnéticaA Ressonância Magnética (RM) Mamária com injecção de contraste é uma ferramenta indispensável para a caracterização de lesões mamárias. Para tal, é fulcral uma boa capacidade de saturação de gordura de forma a delimitar as lesões observadas. Este trabalho tem como objectivo analisar quantitativamente e qualitativamente as técnicas de saturação de gordura em RM mamária, nomeadamente as técnicas SPAIR e Dixon. Este estudo foi realizado no Hospital da Luz e foram estudadas 16 utentes do sexo feminino, com idade média±desvio padrão de 54,8±12,8 anos (dos 37 aos 76 anos) às quais foram identificadas 9 lesões benignas e 7 lesões malignas. Utilizou-se um equipamento de RM de 1,5T com bobina específica para a mama. Além do protocolo normal aplicou-se durante o exame uma sequência adicional em que a técnica de saturação de gordura utilizada foi a Dixon. Posteriormente foram analisadas as imagens obtidas com as técnicas SPAIR e Dixon e colocadas regiões de interesse (ROIs) na lesão, na glândula mamária, no tecido adiposo e no ar. Estes valores de sinal obtidos foram registados e calculou-se o valor médio de intensidade de sinal, as relações sinal-ruído (SNR), contraste-ruído (CNR) e uniformidade de saturação de gordura para as mesmas estruturas a analisar e nas distintas sequências. Verificou-se que a técnica de supressão de gordura Dixon apresenta resultados quantitativos e qualitativos superiores à técnica SPAIR. A partir deste estudo recomenda-se a utilização da técnica Dixon para saturação de gordura nas sequências de estudo dinâmico com agente de contraste, especificamente nos estudos de RM mamária.ABSTRACT - Breast MRI with contrast injection is an indispensable tool for the characterization of breast lesions. To achieve this, good fat saturation is important in order to delimit the lesions. This study aims to assess quantitatively and qualitatively the fat saturation techniques in breast MRI, including SPAIR and Dixon techniques. This study was performed at Hospital da Luz and 16 female subjects were studied, with mean age ± SD of 54.8 ± 12.8 years (from 37 to 76 years). Nine benign lesions and seven malignant lesions were identified. The study was performed in 1.5T MRI equipment and a specific breast coil was used. Besides the normal protocol, the study included an additional sequence with the Dixon fat saturation technique. Subsequently, the images obtained were analyzed and specifics ROI's were placed in the lesion, mammary gland, adipose tissue and air, for both SPAIR and Dixon technique images. The obtained signal values were registered and the average value of signal intensity, the SNR, CNR and uniformity of fat saturation were calculated for all mentioned structures. It was found that the fat suppression technique Dixon quantitative and qualitative results are better than the technique SPAIR. From this study, the use of the Dixon technique for fat saturation is recommended in the dynamic study sequences with contrast agent, specifically in breast MRI studies