Advances in neuro-oncology imaging

Key Points

  • Improvement of brain tumour diagnostics is necessary because therapies are extremely expensive and their efficient use is mandatory

  • Both amino acid PET and advanced MRI methods (perfusion-weighted imaging, diffusion-weighted imaging and magnetic resonance spectroscopic imaging) provide substantial additional information for brain tumour diagnostics

  • Advanced MRI methods are readily available but interpretation is challenging and images are frequently impaired by susceptibility artefacts

  • Amino acid PET requires additional scanning but is a robust and attractive approach for clinicians because of easy scan reading

  • Information from amino acid PET and advanced MRI methods seems to be complementary but multimodal studies are scarce and urgently needed


Despite the fact that MRI has evolved to become the standard method for diagnosis and monitoring of patients with brain tumours, conventional MRI sequences have two key limitations: the inability to show the full extent of the tumour and the inability to differentiate neoplastic tissue from nonspecific, treatment-related changes after surgery, radiotherapy, chemotherapy or immunotherapy. In the past decade, PET involving the use of radiolabelled amino acids has developed into an important diagnostic tool to overcome some of the shortcomings of conventional MRI. The Response Assessment in Neuro-Oncology working group — an international effort to develop new standardized response criteria for clinical trials in brain tumours — has recommended the additional use of amino acid PET imaging for brain tumour management. Concurrently, a number of advanced MRI techniques such as magnetic resonance spectroscopic imaging and perfusion weighted imaging are under clinical evaluation to target the same diagnostic problems. This Review summarizes the clinical role of amino acid PET in relation to advanced MRI techniques for differential diagnosis of brain tumours; delineation of tumour extent for treatment planning and biopsy guidance; post-treatment differentiation between tumour progression or recurrence versus treatment-related changes; and monitoring response to therapy. An outlook for future developments in PET and MRI techniques is also presented.

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Figure 1: Patient with an anaplastic astrocytoma WHO grade III.
Figure 2: Hybrid PET–MRI study of a patient with newly diagnosed glioblastoma WHO grade IV.
Figure 3: Hybrid PET–MRI study of a patient with low-grade glioma.


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Author information

All authors researched data for the article, provided substantial contributions to discussion of content, wrote the article and reviewed and edited the manuscript before submission. K.-J.L. and N.G. contributed equally to the article.

Correspondence to Karl-Josef Langen.

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PowerPoint slides


Adjuvant chemotherapy

Administration of chemotherapy after surgery or radiation treatment for cancer to target remaining malignant cells.

T1-weighted and T2-weighted sequences

Standard morphological images weighted by the longitudinal (T1) and transverse (T2) relaxation times of the protons.

Perfusion-weighted imaging

Image acquisition techniques that highlight fluids moving through arteries, veins and capillaries.

Diffusion-weighted imaging

Imaging technique designed to weight the MRI signal by the amount of diffusion (random thermal motion) of water molecules.

Fluid-attenuated inversion recovery

MRI technique that uses inversion recovery, in which the signal from water is reduced by timing the delay of the inversion pulse.

Cerebral blood flow

Flow of capillary blood per unit mass through the brain tissue (units: ml/min/100 g).

Relative cerebral blood volume

The volume of blood in a brain lesion in relation to the normal brain tissue.

Mean transit time

The average time, in seconds, that red blood cells spend within a given volume of capillary circulation.

Single voxel spectroscopy

A magnetic resonance spectroscopy technique used to assess the concentration of metabolites in a defined region of interest.

Brownian motion

Continuous random movement of particles suspended in a fluid, which arises from collisions with the fluid molecules.

Fractional anisotropy

Fractional anisotropy (FA) is a scalar parameter (0 ≤ FA ≤1) used to quantify the degree of anisotropy of the diffusion process.

Local maxima

Area with maximum signal of different parameters in the tumour area


Area with locally increased signal of different parameters in the corresponding image.


A phenomenon whereby tumours initially 'grow' on MRI due to immune infiltrate, but then decrease in size.

Convection-enhanced delivery

A therapeutic strategy to facilitate delivery of pharmaceuticals. Placement of small-diameter catheters directly into the brain tumour is followed by infusion of therapeutics.

Chemical exchange saturation transfer

An MRI technique in which exogenous or endogenous compounds containing exchangeable molecules are selectively saturated and, after transfer of this saturation, detected indirectly through the water signal with enhanced sensitivity.

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Langen, K., Galldiks, N., Hattingen, E. et al. Advances in neuro-oncology imaging. Nat Rev Neurol 13, 279–289 (2017).

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