integrative imaging techniques for tumor analysis in mice

Inoculazione guidata del tumore e imaging multimodale nei topi

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.

Autore in primo piano: Integrazione dell'imaging intravitale ad alta risoluzione e della risonanza magnetica per migliorare la pianificazione della radioterapia stereotassica corporea

Un modello murino tumorale della camera della finestra delle pliche cutanee dorsali per la microscopia intravitale combinata e la risonanza magnetica nella ricerca traslazionale sul cancro

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.

Tecniche di imaging integrative per l'analisi dei tumori nei topi

Dopo almeno tre o quattro giorni dall'intervento chirurgico della camera finestra, fissare il topo anestetizzato in una fase di imaging con un attacco per anestesia gassosa. Utilizzando la microscopia a campo chiaro, è possibile ottenere un'immagine con un ampio campo visivo, garantendo la visibilità dei divot del marcatore fiduciale sul telaio anteriore del DSFC. Lo stesso giorno, utilizzare la modalità di microscopia intravitale per acquisire un'immagine microvascolare.Dopo aver posizionato il topo sul lettino per la risonanza magnetica, inserire un ago a farfalla calibro 27 con microtubo attaccato nella vena caudale. Fissare la camera della finestra in un dispositivo di immobilizzazione stampato in 3D Utilizzando un ago calibro 18, iniettare il lubrificante veterinario per gli occhi nei sette tubi del fiducial marker MRI. Applicare il fiducial marker al DSFC.Inserire il letto in uno scanner MRI preclinico da sette Tesla. Per l'acquisizione, impostare un campo visivo di 32 x 32 millimetri con una matrice di 64 x 64 per 0,5 x 0,5 millimetri in risoluzione semplice con impulsi RF coerenti. Acquisisci set di immagini pesate in T2 coronale e assiale per visualizzare il piano della camera della finestra.Prescrivere e riorientare iterativamente un set sagittale pesato in T2 per allineare le sezioni di imaging con il DSFC e i marcatori fiduciali, assicurandosi che la sezione cinque contenga il segnale tissutale nel DSFC e la sezione quattro no. Eseguire l'imaging microvascolare utilizzando il metodo di risonanza magnetica con mezzo di contrasto dinamico selezionato. Nell'area di lavoro MATLAB, caricare i dati microvascolari, di microscopia a campo chiaro e di risonanza magnetica microvascolare, quindi fare clic sul pulsante Esegui.Passare al file contenente le sezioni di risonanza magnetica pesate in T2 e selezionare fino a quattro sezioni che visualizzano i marcatori fiduciali. Posizionare un punto su ciascuno dei sette marcatori fiduciali nell'immagine MRI e abbinarli al punto corrispondente sull'immagine al microscopio. Selezionare almeno tre punti di riferimento microvascolari sull'immagine microvascolare svOCT e i punti corrispondenti nell'immagine microscopica.Contornare il tumore nell'immagine di microscopia coregistrata, quindi vengono visualizzati il set di dati microvascolari svOCT, l'immagine di microscopia coregistrata e le mappe dei parametri MRI coregistrate. Salvare la mappa per un'analisi successiva. La coregistrazione dell'imaging microvascolare, della microscopia a campo largo e della risonanza magnetica in topi sani e portatori di tumore consente l'analisi della correlazione delle metriche microvascolari e macrovascolari.Le metriche macrovascolari MRI dinamiche con mezzo di contrasto hanno mostrato forti correlazioni tra le metriche microvascolari derivate da svOCT, come indicato dai valori R al quadrato in entrambi i grafici. Le correlazioni sono state misurate sia in topi sani che portatori di tumore per valutare la capacità della risonanza magnetica con mezzo di contrasto dinamico di misurare le caratteristiche vascolari in architetture microvascolari molto diverse.

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 ...

Ricerca

Ricerca sul cancro

Tumor Cells Inoculation in Mice Through Precise Landmarking and Injection Techniques

Inoculazione di cellule tumorali nei topi attraverso tecniche di landmarking e iniezione precise

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

Chirurgia della camera a finestra in topi iniettati con cellule tumorali per la visualizzazione e l'imaging della crescita tumorale