Current and Potential Applications of Clinical ¹³C MR Spectroscopy

Abstract

In this article, the current and potential clinical roles of 13 C magnetic resonance spectroscopy (MRS) and 13 C magnetic resonance spectroscopic imaging are presented, with a focus on applications to prostate cancer and hyperpolarized 13 C spectroscopic imaging. The advantages of 13 C MRS have been its chemical specificity and lack of background signal, with the major disadvantage being its inherently low sensitivity and the subsequent inability to acquire data at a high-enough spatial and temporal resolution to be routinely applicable in the clinic. The approaches to improving the sensitivity of 13 C spectroscopy have been to perform proton decoupling and to use endogenous 13 C-labeled or enhanced metabolic substrates. With these nominal increases in signal-to-noise ratio, 13 C MRS using labeled metabolic substrates has shown diagnostic promise in patients and has been approved by the Food and Drug Administration. The development of technology that applies dynamic nuclear polarization to generate hyperpolarized 13 C-labeled metabolic substrates, and the development of a process for delivering them into living subjects, have totally changed the clinical potential of MRS of 13 C-labeled metabolic substrates. Preliminary preclinical studies in a model of prostate cancer have demonstrated the potential clinical utility of hyperpolarized 13 C MRS.

Targeting cancer metabolism: a therapeutic window opens

“…Furthermore, increased application of techniques such as MR spectroscopy, including dynamic nuclear polarization to generate hyperpolarized 13 C--labeled metabolites whose metabolism can be tracked in tumors, can allow direct visualization of how metabolism is altered as a result of new therapies in patients 73,74 . These approaches to track metabolism in vivo will be especially critical to understand how cell metabolism is influenced by the tumor microenvironment 5 , and will help select the right patients for specific drugs targeting metabolism.…”

Espectroscopia cerebral em candidatos a transplante hepático

“…Recentemente, refinamentos técnicos na espectroscopia por ressonância magnética (RM) tornaram possível o estudo bioquímico do cérebro humano in vivo, com a identificação e quantificação dos metabólitos cerebrais em regiões específicas 4,8,22,29 . A encefalopatia hepática é caracterizada por depleção do mio-inositol (MI) e da colina (Cho) associada a um aumento do complexo glutamino-glutamato (Glx).…”

“…A espectroscopia foi realizada com um aparelho de ressonância com 1,5T (Magnetom Vision; Siemens, Erlanger, Germany) utilizandose uma bobina polarizada circular posicionada junto à cabeça dos examinados. Para os exames de controle pós-operatório, a exata reprodução da localização espectral foi conseguida mediante a aquisição prévia de três cortes (sagital, transversal e coronal) na RM em T2 (tempo de relaxamento transversal dos núcleos) utilizando-se a técnica de fast spin echo para posicionamento tridimensional do volume de interesse (voxel) na parte medial do lobo occipital (substância branca e cinzenta) com 2 X 3 X 2 cm 8,12 .…”

13C MR Imaging of Methionine-rich Gliomas at 4.7T: A Pilot Study

“…1 The major safety limitation in human 1 H decoupled 13 C-MRI is the speciˆc absorption rate (SAR) of tissue exposed to 1 H frequency irradiation. 2 Replacing the 12 C (98.9z natural abundance) with the 13 C isotope at a speciˆc carbon in a metabolic substrate does not aŠect its biochemistry.…”

“…However, the clinical use of 13 C-MRI has been limited by the low natural abundance of 13 C (1.1z) and its low magnetogyric ratio (the g of 13 C is 25z that of protons [ 1 …”