FET PET points to additional glioma activity compared with MRI

PET provides more detail than perfusion-weighted MRI about the boundaries and metabolic function of glioma tumors, according to a study published online Feb. 27 in the Journal of Nuclear Medicine.

MR neuroimaging is considered a strong modality for the detection of brain tumors due to the technology’s fine sensitivity and contrast for soft tissues, but PET provides distinct information that MR imaging cannot.

Christian P. Filss, from the Institute of Neuroscience and Medicine Research Center in Julich, Germany, and colleagues compared MR perfusion-weighted imaging (PWI) with PET using O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET) for their ability to reflect cerebral gliomas. Results showed very different pictures between modalities.

“PET using (F-18 FET) provides important diagnostic information in addition to that from conventional MR imaging on tumor extent and activity of cerebral gliomas,” wrote Filss et al.

The researchers compared the modalities after analyzing both scans in a total of 56 glioma patients and a control group of eight subjects with meningiomas. Results showed that F-18 FET PET found substantially higher tumor-to-brain ratios and larger tumor volumes than MR maps of cerebral blood volume.

“The spatial congruence of both parameters is poor,” wrote the authors. “The locations of the local hot spots differ considerably. Taken together, our data show that metabolically active tumor tissue of gliomas as depicted by amino acid PET is not reflected by [regional cerebral blood flow] as measured with PWI.”

Overall sensitivity of F-18 FET uptake for glioma detection was 84 percent versus the PWI’s maps, which showed 38 percent sensitivity for regional cerebral blood flow. Sensitivity of both modalities for the control group of meningioma patients was 100 percent.