Research article

Metabolic profiling of human brain metastases using in vivo proton MR spectroscopy at 3T

Torill E Sjøbakk¹ , Roar Johansen² , Tone F Bathen³ , Ursula Sonnewald¹ , Kjell A Kvistad⁴ , Steinar Lundgren^2,5 and Ingrid S Gribbestad³

¹Department of Neuroscience, Norwegian University of Science and Technology (NTNU), Norway

²Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway

³Department of Circulation and Medical Imaging, NTNU, Trondheim, Norway

⁴Department of Radiology, St. Olavs University Hospital, Trondheim, Norway

⁵Department of Oncology, St. Olavs University Hospital, Trondheim, Norway

author email corresponding author email

BMC Cancer 2007, 7:141doi:10.1186/1471-2407-7-141

Published:	27 July 2007

Abstract

Background

Metastases to the central nervous system from different primary cancers are an oncologic challenge as the overall prognosis for these patients is generally poor. The incidence of brain metastases varies with type of primary cancer and is probably increasing due to improved therapies of extracranial metastases prolonging patient's overall survival and thereby time for brain metastases to develop. In addition, the greater access to improved neuroimaging techniques can provide earlier diagnosis. The aim of this study was to investigate the feasibility of using proton magnetic resonance spectroscopy (MRS) and multivariate analyses to characterize brain metastases originating from different primary cancers, to assess changes in spectra during radiation treatment and to correlate the spectra to clinical outcome after treatment.

Methods

Patients (n = 26) with brain metastases were examined using single voxel MRS at a 3T clinical MR system. Five patients were excluded due to poor spectral quality. The spectra were obtained before start (n = 21 patients), immediately after (n = 6 patients) and two months after end of treatment (n = 4 patients). Principal component analysis (PCA) and partial least square regression analysis (PLS) were applied in order to identify clustering of spectra due to origin of metastases and to relate clinical outcome (survival) of the patients to spectral data from the first MR examination.

Results

The PCA results indicated that brain metastases from primary lung and breast cancer were separated into two clusters, while the metastases from malignant melanomas showed no uniformity. The PLS analysis showed a significant correlation between MR spectral data and survival five months after MRS before start of treatment.

Conclusion

MRS determined metabolic profiles analysed by PCA and PLS might give valuable clinical information when planning and evaluating the treatment of brain metastases, and also when deciding to terminate further therapies.