How to Design a Molecular Imaging Experiment
Emmanuel L. Barbier1

1Functional Neuroimaging and Brain Perfusion, Grenoble Inst des Neurosciences (GIN), Grenoble, France


This course will address the steps that a beginner should follow to develop a molecular imaging experiment in small animals: after setting the target and choosing the appropriate animal model, we will evaluate the pros and cons of existing imaging modalities, with a focus on MRI data acquisition and integration during post-processing. Examples will be taken from oncology and neuroscience.

1. Setting the target

You will come with one or several questions in mind. Then, after discussing with imaging people, you may reformulate your questions. It is very important to follow this path so that you can actually come with questions that can be effectively addressed by molecular imaging. You will have to consider technical aspects (imaging modality (may be several modalities), imaging technical details, possibly contrast agents (1,2) (type, dose), regulation issues, post-processing issues, data integration and statistics…). Be sure to cover these aspects when designing your experiments. If you do not find an existing study that describes what you want to do, you may need to conduct preliminary tests to evaluate whether molecular imaging can answer your specific question(s). One major issue is to handle this set-up phase within your specific regulations. Do not hesitate to contact the authors of publications similar to the study you have in mind to discuss limits or ask for a data sample. You can also try to obtain sample data during already authorized research. For example, you may want to obtain an extra image during an existing protocol to evaluate if a particular spatial resolution may be reached.

2. Some issues about animal models

Based on examples taken in the field of oncology and neuroscience, we will briefly illustrate the potentials and the limits of animal models, including the impact of anesthetics and physiological monitoring.

3. Overview of animal imaging modalities

Several imaging modalities are available. We will briefly review the pros and cons of the main preclinical imaging modalities, including X-ray imaging, optical imaging (3,4), nuclear imaging (5), ultrasound (6), and MRI (7-9). Multi-modal (such as PET-MRI) systems are also emerging. Main items to consider are spatial and temporal resolutions and sensitivity

4. Overview of MRI options

MRI is a technique well-suited to image several information during a single session. We will briefly review how to organize your MRI experiment and what estimates may be obtained with MRI. Several types of map may be obtained without any contrast agent such as diffusion based estimates (related to edema or tissue microstructure), blood flow, MR spectroscopy. Contrast agents may also be used to map other information such as tissue oxygenation. At a preclinical level, many contrast agents have also been developed to reach specific targets. Imaging protocols should be adapted to the pharmacokinetic of the contrast agent. Depending on the desired quantification level, additional sequences may be required (e.g. measure a reference signal, acquire a T1 map…).

5. Data processing, integration, and interpretation

From the acquired images, one need to estimate values. There is no standard software to post-process this type. One can extract information image per image, either using standard contrasts (signal difference between an area that received contrast agent and an area that did not) or using texture analysis (sometimes call Radiomics) (10). In case several types of MRI images are acquired per animal, one may also consider an integrated analysis (11-13). This ability to derive tissue information across several images – potentially across several imaging modalities – appears very powerful.


No acknowledgement found.


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Proc. Intl. Soc. Mag. Reson. Med. 26 (2018)