Comment to the article:

A. Stadlbauer et al. Magnetic Resonance Spectroscopic Imaging for Visualization of the Infiltration Zone of Glioma. Cen Eur Neurosurg. Cen Eur Neurosurg 2011; 72: 63–70

In this issue Stadlbauer et al. present their results on spectroscopic imaging in patients with glioma. From a pure methodical aspect this is a nice paper. The only weakness is that the spatial resolution of both imaging methods is really different and from a methodical point of view this automatically leads to an underestimation of tumour volume on MRI compared to spectroscopic imaging. But beside this, we have to be careful that the new “hammer” (MRSI) does not make everything look like a nail. It's obvious that you can use MRSI in malignant brain tumours (as you can do in Multiple Sclerosis, stroke….), but is there really any new and therapeutic relevant information on these images?

We do know since decades that the real tumour border is far beyond the T2-alteration and even more far beyond the area of contrast-enhancement in malignant tumours. Therefore, I am in doubt, whether the final statement of the authors “…(MRSI) may thus helpful in therapeutic planning” will really improve the prognosis of the patients. Gliomas and specifically the malignant variant – and these are the main therapeutic challenge – are not a local problem. Neither radical surgery nor more focussed or targeted radiation therapy will cure the patients, regardless whether you can see a little bit tumour invasion with MRSI or not. The recurrence free survival rate is clearly improved, if the neurosurgeon can achieve a gross total resection, but he will never achieve a total tumour resection, regardless what kind of imaging we offer.

However, my hope would be to develop an imaging method than can differentiate between responders and non-responders for e. g. different types of chemo- or anti-metabolic therapies. That would be helpful.

In summary: It is necessary to develop new methods like MRSI, no doubt and to figure out in which clinical situations they may be useful. However, I am in doubt, whether MRSI will play a major role in clinical neurosurgery.

Michael Forsting
Radiology and Neuroradiology
University Essen
Germany