integrative imaging techniques for tumor analysis in mice

Inoculação tumoral guiada e imagem multimodal em camundongos

Tumor microvasculature is an important component of the tumor microenvironment that can be a target for therapy and a determinant of treatment response. In the preclinical setting, the microvasculature is typically studied using intravital microscopy in orthotopic or heterotopic window chamber animal models1,2. This has several advantages over histological studies since the imaging is done in live tissues and the tumor can be monitored longitudinally over several weeks or even months2,3. These studies can leverage the high-resolution imaging capabilities of intravital microscopy to study the delivery of therapeutics to the tumor4,5, the causes of treatment resistance6, and the response of the micro vessels to therapies such as antiangiogenic treatment7,8 and radiotherapy2,9.
Intravital microscopy clearly plays an important role in preclinical cancer research; however, how can tumor microenvironmental features be measured in the clinic? Microvascular information would be useful in the clinic for measuring blood supply and tumor cell hypoxia, which is important for determining treatment resistance in radiotherapy10, as well as the ability of the microvasculature to deliver chemotherapeutic agents to the surrounding tumor cells11. For example, in radiotherapy, spatial information on the structure and function of the tumor microvasculature may help personalize a patient&#39;s treatment plan by adjusting the fractionation schedule or by preferentially boosting the dose to avascular and likely hypoxic regions12.
Intravital microscopy can measure these important microvascular features since it has a very high resolution (&#956;m scale); however, its depth penetration into tissue is limited to several hundred microns or a few millimeters, at most making clinical implementation challenging. Indeed, there are some novel applications of intravital microscopy in the clinic13; however, these are still limited to examinations of near-surface level tissue such as the skin14 or mucosal/endothelial linings of various body cavities via flexible catheters/endoscopes15,16.
More commonly, the microvasculature is studied using imaging modalities such as CT17 or MRI18. These clinical imaging modalities can image to any depth within the body, but they have a much lower spatial resolution (mm scale). Thus, there is a need to bridge this resolution gap between preclinical intravital microscopy and clinical imaging modalities to bring high-resolution and detailed microvascular information into the clinic19. Several functional imaging methods have been developed to improve the microvascular imaging capabilities of clinical imaging modalities such as dynamic contrast-enhanced (DCE) MRI and CT20, and Intravoxel incoherent motion (IVIM) MRI21. However, these are model-based methods that provide indirect measurements of the microvasculature and thus, must be validated with appropriate &#34;ground truth&#34; measurements of the microvasculature19,22.
We have developed a dorsal skinfold window chamber (DSFC) tumor mouse model to bridge this gap between preclinical intravital microscopy and clinically applicable imaging modalities such as CT and MRI. The DSFC provides direct access to the tumor for high-resolution, intravital microscopy imaging through a glass window but also clinically applicable imaging such as MRI as it is made of MR-compatible materials (plastic and glass). Furthermore, an included MATLAB code performs multimodality 3D co-registration for direct spatial correlations between preclinical intravital microscopy and clinically applicable imaging modalities. Here we will describe the design and surgery to install the DSFC as well as the procedure to co-register intravital microscopy and clinically applicable imaging modalities.

Autor em destaque: Integrando imagens intravitais de alta resolução e ressonância magnética para melhorar o planejamento da radioterapia corporal estereotáxica

Um modelo de camundongo tumoral de câmara de janela de dobra cutânea dorsal para microscopia intravital combinada e ressonância magnética na pesquisa translacional do câncer

Preclinical intravital imaging has very high resolution, but limited depth penetration in the tissue, which makes it very good for preclinical imaging studies. On the other hand, MRI is much more clinically applicable and has a higher depth penetration, but very low spatial resolution. The goal of this study is to correlate these two modalities with each other in order to better translate our findings from preclinical intravital microscopy into the clinic via magnetic resonance imaging.Perfusion-sensitive imaging methods in MRI and biophotonics, including our optical coherence tomography and geography system, are revealing how the microvasculature impacts tumor response to hypofractionated radiotherapy. 3D printing is also aiding through cost-effective custom tool manufacturing, facilitating longitudinal studies. Finally, AI image analysis is facilitating the identification of novel radiotherapy predictive biomarkers.We've made several findings concerning the tumor response to hypofractionated radiotherapy, including more recently, the temporal kinetics of both radiobiologically significant and abstracted AI-derived tissue response metrics. Additionally, we have demonstrated the promise for multimodal imaging being performed more accurately, correlating both MRI, macroscopic and optical coherence tomography, microscopic, angiography-derived metrics. By extending the effective length of longitudinal studies, we may better identify predictive biomarkers for long-term tumor treatment response.Additionally, by improving robustness of co-registration between macroscopic clinically available imaging modalities and microscopic preclinical imaging modalities, we may enhance the translatability of our findings from benchtop to bedside. During a stereotactic body radiation therapy, high doses of radiation are delivering a reduced number of fractions. One potential radiobiological target associated with increased cell death in SVRT is the tumor microvasculature.By combining high-resolution optical angiography and MRI, we want to enable functional MRI microvascular imaging for patient-specific SVRT treatment planning and improved outcomes.

Técnicas de imagem integrativa para análise de tumores em camundongos

Após pelo menos três a quatro dias da cirurgia da câmara da janela, prenda o camundongo anestesiado em um estágio de imagem com um acessório de anestesia gasosa. Usando microscopia de campo claro, obtenha uma imagem de amplo campo de visão, garantindo a visibilidade dos divots do marcador fiducial na estrutura frontal do DSFC. No mesmo dia, use a modalidade de microscopia intravital para capturar uma imagem microvascular.Depois de colocar o mouse no leito de ressonância magnética, insira uma agulha borboleta calibre 27 com microtubos presos na veia da cauda. Prenda a câmara da janela em um dispositivo de imobilização impresso em 3D Usando uma agulha de calibre 18, injete lubrificante ocular veterinário nos sete tubos do marcador fiducial de ressonância magnética. Afixe o marcador fiducial no DSFC.Insira a cama em um scanner de ressonância magnética pré-clínica de sete Tesla. Para aquisição, defina um campo de visão de 32 por 32 milímetros com uma matriz de 64 por 64 para 0,5 por 0,5 milímetro em resolução simples com pulsos de RF consistentes. Adquira conjuntos de imagens ponderadas T2 coronais e axiais para visualizar o plano da câmara da janela.Prescreva e reoriente iterativamente um conjunto ponderado em T2 sagital para alinhar os cortes de imagem com o DSFC e os marcadores fiduciais, garantindo que o corte cinco contenha sinal de tecido no DSFC e o corte quatro não. Realize imagens microvasculares usando o método de ressonância magnética com contraste dinâmico selecionado. No espaço de trabalho do MATLAB, carregue os dados microvasculares, de microscopia de campo claro e de ressonância magnética microvascular e clique no botão Executar.Navegue até o arquivo que contém os cortes de ressonância magnética ponderados em T2 e selecione até quatro cortes que exibem os marcadores fiduciais. Coloque um ponto em cada um dos sete marcadores fiduciais na imagem de ressonância magnética e combine-os com o ponto correspondente na imagem de microscopia. Selecione pelo menos três pontos de referência microvasculares na imagem microvascular svOCT e os pontos correspondentes na imagem microscópica.Contorne o tumor na imagem de microscopia co-registrada e, em seguida, o conjunto de dados microvascular svOCT, a imagem de microscopia co-registrada e os mapas de parâmetros de ressonância magnética co-registrados aparecem. Salve o mapa para análise posterior. O corregistro de imagens microvasculares, microscopia de campo amplo e ressonância magnética em camundongos saudáveis e portadores de tumor permite a análise de correlação de métricas microvasculares e macrovasculares.As métricas macrovasculares de ressonância magnética com contraste dinâmico mostraram fortes correlações entre as métricas microvasculares derivadas do svOCT, conforme indicado pelos valores de R ao quadrado em ambos os gráficos. As correlações foram medidas em camundongos saudáveis e portadores de tumor para avaliar a capacidade da ressonância magnética com contraste dinâmico de medir características vasculares em arquiteturas microvasculares amplamente diferentes.

integrative-imaging-techniques-for-tumor-analysis-in-mice

Research

JoVE Journal

Cancer Research

Integrative Imaging Techniques for Tumor Analysis in Mice

A Dorsal Skinfold Window Chamber Tumor Mouse Model for Combined Intravital Microscopy and Magnetic Resonance Imaging in Translational Cancer Research

Preclinical intravital imaging such as microscopy and optical coherence tomography have proven to be valuable tools in cancer research for visualizing the ...

Pesquisa do câncer

Tumor Cells Inoculation in Mice Through Precise Landmarking and Injection Techniques

Inoculação de células tumorais em camundongos por meio de técnicas precisas de marcação e injeção

Window Chamber Surgery in Tumor Cell Injected Mice for Tumor Growth Visualization and Imaging

Cirurgia de câmara de janela em camundongos injetados com células tumorais para visualização e imagem do crescimento tumoral