How we read: the combined use of MRI and novel PET tracers for the characterisation and treatment planning of masses in neuro-oncology

Abstract

Technical advances in imaging are well demonstrated by MRI (Magnetic Resonance Imaging) and PET (Positron Emission Tomography). Excellent anatomical detail and a lack of ionising radiation make MRI the standard of care for most neuroimaging indications, and advanced sequences are providing an ever-growing ability for lesion characterisation. PET utilising the tracer fluorine-18 fluorodeoxyglucose is widely used in oncology, while newer PET tracers are able to target a growing number of metabolic pathways and cell membrane receptors. The sequential use of these modalities harnesses the strengths of both, providing complementary diagnostic and therapeutic information. Here we outline the ways in which we use MRI and PET in a complementary manner to improve lesion characterisation in neuro-oncology. Most commonly, an abnormality is detected on either PET or MRI, and the addition of the other modality allows a more confident diagnosis and/or demonstrates additional lesions, guiding treatment decisions and, in some cases, obviating the need for biopsy. These modalities may also be combined to guide the treatment of intracranial masses for which the diagnosis is known, such as neuro-endocrine tumour metastases or meningiomas refractory to conventional therapies.

Deuterium Metabolic Imaging—Rediscovery of a Spectroscopic Tool

“…In addition, the high abundance (99.98%) and sensitivity (highest gyromagnetic ratio) of the hydrogen nucleus has led to rapid evolution of tools for 1 H NMR including many spectroscopic methods that are now integrated into routine clinical practice, especially for the characterization of prostate tumors [ 33 , 34 ], brain tumors [ 35 , 36 , 37 ], and various other metabolic derangements [ 38 , 39 , 40 ]. As far as other metabolic imaging tools, PET has also been extraordinarily successful especially with the rapid proliferation of metabolite-derived tracers and the expansion of dual modality scanners (i.e., PET-CT and PET-MR) [ 41 , 42 , 43 , 44 ]. Finally, imaging of other stable isotopes (i.e., 13 C) has benefitted from dynamic nuclear polarization (DNP) [ 45 , 46 ], where the nuclear polarization (and therefore the MR signal) is transiently increased by several orders of magnitude prior to injection.…”

The utility of pharmacological and radiological interventions to optimize diagnostic information from PET/CT

“…Incidental detection of features indicating neurodegenerative or cerebrovascular disease may also impact treatment choices. With tracers that have low or no significant uptake in the brain, inclusion of the head can detect incidental abnormalities that might also provide complementary information to formal neuroimaging [ 37 ].…”

[6,6′‐2H2] fructose as a deuterium metabolic imaging probe in liver cancer

“…Current methods for metabolic imaging aim to differentiate healthy and cancerous tissues by characterizing changes in glycolysis, as enhanced aerobic glycolysis, termed the Warburg effect, is a metabolic phenotype of cancer 3 . Fluorodeoxyglucose–positron emission tomography (FDG‐PET) is one of the most widely used clinical modalities, by detecting enhanced glucose uptake 4–8 . However, information regarding downstream metabolic processes, which is of fundamental importance for tumor detection and evaluation of therapeutic treatment, cannot be obtained by FDG‐PET.…”