integrative imaging techniques for tumor analysis in mice

マウスにおける腫瘍のガイド下接種とマルチモーダルイメージング

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.

著者スポットライト:高解像度生体内イメージングとMRIを統合して、定位放射線治療計画を強化する

トランスレーショナルがん研究における生体内顕微鏡検査と磁気共鳴画像法の併用のための背側Skinfold Window Chamber腫瘍マウスモデル

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.

マウスの腫瘍解析のための統合イメージング技術

窓室手術から少なくとも3〜4日後、麻酔をかけたマウスをガス麻酔アタッチメントでイメージングステージに固定します。明視野顕微鏡を使用して、DSFCのフロントフレーム上の基準マーカーのディボットの視認性を確保し、広視野画像を取得します。同日、生体内顕微鏡モダリティを使用して微小血管画像を撮影します。マウスをMRIベッドに置いた後、マイクロチューブを取り付けた27ゲージのバタフライ針を尾静脈に挿入します。3Dプリントされた固定装置で窓室を固定する 18ゲージの針を使用して、MRI基準マーカーの7本のチューブに獣医用眼潤滑剤を注入します。フィデューシャルマーカーをDSFCに貼り付けます。ベッドを7テスラの前臨床MRIスキャナーに挿入します。集録するには、32 x 32 mm の視野と 64 x 64 のマトリクスを 0.5 x 0.5 mm のプレーン解像度に設定し、一貫した RF パルスを設定します。コロナルと軸方向の T2 重み付け画像セットを取得して、窓室平面を可視化します。イメージングスライスを DSFC および基準マーカーに整列させるために、矢状 T2 重み付けセットを処方し、繰り返し向きを変えて、スライス 5 に DSFC に組織シグナルが含まれ、スライス 4 に組織シグナルが含まれないようにします。選択した動的造影MRI法を使用して微小血管イメージングを実行します。MATLAB ワークスペースで、微小血管、明視野顕微鏡、微小血管 MRI のデータを読み込み、[実行] ボタンをクリックします。T2 重み付け MRI スライスを含むファイルに移動し、指標マーカーを表示する最大 4 つのスライスを選択します。MRI画像内の7つの基準マーカーのそれぞれに点を配置し、顕微鏡画像上の対応する点と一致させます。svOCT微小血管画像上の少なくとも3つの微小血管ランドマークポイントと顕微鏡画像内の対応するポイントを選択します。共登録顕微鏡画像で腫瘍を輪郭を描くと、svOCT 微小血管データセット、共登録顕微鏡画像、および共登録 MRI パラメーター マップが表示されます。後で解析するためにマップを保存します。健康なマウスと担がんマウスの両方で微小血管イメージング、広視野顕微鏡、およびMRIを同時レジストレーションすることで、微小血管と大血管の指標の相関分析が可能になります。動的造影MRI大血管メトリクスは、svOCT由来の微小血管メトリクス間に強い相関関係を示し、両方のプロットのR二乗値で示されました。相関関係は、主に異なる微小血管構造にわたって血管特性を測定する動的造影MRIの能力を評価するために、健康なマウスと担腫瘍マウスの両方で測定されました。

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 ...

がん研究

Tumor Cells Inoculation in Mice Through Precise Landmarking and Injection Techniques

精密なランドマークおよび注射技術によるマウスへの腫瘍細胞接種

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

腫瘍増殖の視覚化とイメージングのための腫瘍細胞注入マウスのウィンドウチャンバー手術