Lactate quantification by proton magnetic resonance spectroscopy using a clinical MRI machine: A basic study

Abstract

The purpose of this study was to establish quantification method of lactate concentration by proton magnetic resonance spectroscopy (MRS) carried out using a conventional 1.5-T MRI machine. We used a lactate phantom with known concentrations (1, 1.5, 3, 6, 12 and 14 mmol/L). As a clinical example, a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) was evaluated. Proton MRS was carried out using a clinical 1.5-T super-conducting magnetic resonance whole-body system. Data were acquired by point resolved spectroscopy. A coupling constant of J = 7.35 Hz (2/J = 272 ms) and two long in-phase echo time of 272 ms and 544 ms were used to calculate the T2 relaxation time. The tissue water signal was used as an internal standard to quantify lactate. The correlation coefficient R between the calculated lactate concentrations and the known concentration of lactate was 0.99 with a constant factor of 0.32 (1/3.14). In patients with MELAS, the lactate concentration measured by MRS was 6.2 mmol/kg wet weight, which is similar to the value obtained in previous studies. In the present study, we have established a reliable method for lactate quantification in a phantom study and have shown a sample of clinical case of MELAS.

Neuroimaging of mitochondrial disease

“…myo-inositol, choline, creatine, and NAA). In mitochondrial diseases, lactate elevations are suggested to range from 3−11 mM (Wilchowski et al, 1999) with other studies reporting average levels of approximately 6 mM (Saitoh et al, 1998;Isobe et al, 2007). The most consistent MRS change accompanying increased lactate in mitochondrial disease is decreased NAA, suggestive of cellular compromise.…”

Does MRS Lactate Peak Correlate with Lactate in the CSF and Blood?

“…Previous reports have shown that MRS is a useful tool for the noninvasive detection of an LP in the brain parenchyma and in the ventricles. 6,8,12 Isobe et al 17 performed an in vitro study that showed a correlation between lactate concentration in a phantom and its quantification by MRS, and they demonstrated the reliability of MRS in LP detection. In our study of patients suspected of having mitochondrial disorders, we were able to quantify an LP by MRS in the lateral ventricles of all studied patients.…”

The use of neuroimaging in the diagnosis of mitochondrial disease

“…Given the correct clinical presentation, lactate elevations above normal levels of 1 mM can aid in determining whether ETC function is normal or compromised. Marked elevations can be observed in many patients with mitochondrial disease and ranging from 3 to 11 mM [Wilichowski et al, 1999], with some studies reporting average levels of 6 mM [Saitoh et al, 1998;Isobe et al, 2007]. Three examples illustrating markedly elevated brain lactate are shown in Figure 7.…”