E³ 1626 - Molecular imaging in oncology
1. To understand the basics of molecular imaging.
2. To appreciate the unmet needs of oncological imaging.
3. To learn the role of molecular imaging in oncology.
Today, radiology is playing a central role in the set-up of multidisciplinary cancer centres and in the comprehensive work-up of oncologic patients, integrating an ever increasing amount of qualitative and quantitative diagnostic information. Still, radiology is facing significant challenges, as “precision medicine” develops and matures. Integrating functional and molecular information in a quantitative fashion and adding complementary multimodality information is crucial. In detail, molecular imaging is regarded as the direct or indirect non-invasive monitoring and recording of the spatial and temporal distribution of in vivo molecular, genetic, and/or cellular processes for biochemical, biological, diagnostic, or therapeutic applications. Molecular images that indicate the presence of malignancy can be acquired using an abundance of modalities, including optical, ultrasonic, radiologic, radionuclide, and magnetic resonance techniques. In this session, molecular and functional imaging of oncologic processes are reviewed with respect to their physical basics and imaging characteristics, including attributes of hypoxia, proliferation, and metabolism. Also, the role, development and standardisation of prognostic, predictive and therapy response oncologic imaging biomarkers will be discussed, and current and future clinical applications in oncologic diagnosis will be reviewed.
1. To review the fundamentals of hypoxia imaging.
2. To review the advantages and disadvantages of hypoxia imaging and its relation to perfusion.
3. To learn about hypoxia imaging in radiation treatment.
Tumour hypoxia is present in up to 60% of locally advanced solid tumours. Tumour hypoxia is a significant challenge to successful therapy, contributing to treatment resistance and a poor prognosis. Intra-tumoural hypoxia may be assessed by molecular markers including hypoxia inducible factor 1 (HIF-1) and carbonic anhydrase isoenzyme IX (CA-IX). However, hypoxia is a dynamic process and alters depending on perfusion and oxygenation status. Non-invasive imaging of intra-tumoral hypoxia provides an opportunity to better stratify patients to improve local control. Tumour hypoxia may be assessed in vivo by direct and indirect imaging techniques. Positron emission tomography (PET) imaging targets hypoxic cells with tracers including18F-fluoromisonidazole (18F-MISO), 18F-fluoroazomycin arabinofuranoside (18F-FAZA) and 64Cu-diacetyl-bis(N4-methylthiosemicarbazone (64Cu-ATSM). Hypoxia imaging may also be undertaken by magnetic resonance imaging (MRI) with techniques such as blood oxygenation level-dependent (BOLD) MRI and oxygen enhanced MRI measuring R2* and R1 changes, respectively. This lecture will review the biological basis and fundamentals of hypoxia imaging and potential clinical applications including radiotherapy.
1. To understand basic principles of proliferation imaging.
2. To become familiar with imaging of proliferation.
3. To learn about difficulties in liver proliferation imaging.
"No abstract submitted."
1. To learn the clinical indications for FDG imaging.
2. To become familiar with imaging protocol.
3. To learn about difficulties in FDG imaging.
18F-FDG PET/CT is an imaging technique that is aimed to evaluate glucose metabolism of tissues and organs. PET/CT scanners consist of a combination of a PET scanner and a CT scanner providing both morphological and functional images. The procedure is standard and includes several steps. Patients are not allowed to consume any food or sugar for at least 6 h prior to the start of the PET study. Injection should be fully intravenous. Optimal uptake time is 60 minutes. In general, for a 3D system and 3 MBq/Kg of FDG, 2 min/bed position is enough, leading to an average overall acquisition time of 14 minutes. Low-dose CT (120 kV, 80 mA) is necessary both for attenuation correction and for image interpretation. Once reconstructed, images must be interpreted on a dedicated workstation. SUV max based on body weight is the standard semi-quantitative index. FDG PET/CT was proved to be accurate for several malignancies for the definition of TNM at staging and in the suspect of relapse. Furthermore, changing in SUV max are related to the response to systemic therapies, both during and after treatment. This parameter is considered a non-invasive surrogate for therapy assessment. Some particular kinds of malignant tumours are not detectable by FDG PET. In particular, mucinous cancers, transitional cell cancers, clear cell cancers, indolent HCC and some adenocarcinomas fail to significantly concentrate FDG. Low accuracy can also be found in some particular areas of the body where FDG is physiologically concentrated such the brain and the urinary tract.
1. To learn the clinical indications for biomarker imaging.
2. To become familiar with quantification.
3. To learn about difficulties in quantification.
Originally regarded as a morphological imaging technique with excellent soft-tissue contrast, MRI today is recognised as a technique that can also provide functional biomarkers through different approaches. For treatment response assessment, diffusion-weighted imaging (DWI), which indirectly provides information on cell density in tumours, is quite well-established. In lymphoma, for instance, it is even considered as an alternative to [18F]FDG-PET after treatment with chemo- or immunochemotherapy. Nevertheless, limitations for DWI include artefacts and standardisation of apparent diffusion coefficients between different DWI pulse sequences, and between MR scanners of different vendors. Perfusion-weighted imaging (PWI) is another technique that is increasingly being used in the response evaluation of hypervascular tumours, such as hepatocellular carcinoma. In the body, PWI is most commonly performed on the basis of dynamic contrast-enhanced sequences (relying on T1 shortening), with k-trans, a measure of capillary permeability, as one of several quantitative parameters. Alternatively, PWI may be performed using arterial spin labelling, without contrast media. MR spectroscopy (MRS), which today is most frequently based on protons, is another technique that can be used to assess biomarkers in the form of metabolites, such as lactate and choline. While several studies reported encouraging data, for instance in breast cancer and prostate cancer, limitations such as long acquisition times and difficulties in terms of standardisation and quantification have prevented MRS from being introduced into routine clinical imaging. Cutting-edge techniques, such as chemical exchange saturation transfer (CEST) imaging, may overcome the limitations of MRS.