[Magnetic resonance imaging with spectroscopy, perfusion and cerebral diffusion in the diagnosis of brain tumours]

We review three of the most important functional techniques in magnetic resonance imaging, it means spectroscopy, perfusion and diffusion; we do emphasize in its applications, particularly in the diagnostic and treatment of brain tumors. First, we discuss the physical principles and results interpretation of each technique. After that, we discuss its major applications.

Choline containing compounds using contralateral creatine and choline for normalization or ipsilateral N-acetyl-aspartate appeared to correlate best with the degree of tumor infiltration, regardless o tumor histological grade. Magnetic resonance spectroscopy imaging (MRSI) seems more accurate than conventional magnetic resonance imaging (MRI) in defining indistinct tumor boundaries and quantifying the degree of tumor infiltration. MRSI is the choice of site within a lesion for biopsy and use in image-guided therapy, including definition of radiation ports. Angiogenesis, and increased vascular permeability, are characteristic of cerebral neoplasms; these processes can be imaged using perfusion MRI. Most commonly, tumor perfusion is measured using rapid gradient T2-weighted imaging during bolus injection of gadolinium dimeglumine gadopentetate. Care has to be taken to avoid blood-brain barrier leakage affecting perfusion results. Pharmacokinetic models are available for estimation of blood-brain permeability. Cerebral blood volume increases with tumor grade, and maybe helpful in identifying tumor recurrence, and peri-tumoral edema, and distinguishing malignant from benign lesions.