Speaker
Dr
Keiko Imamura
(Department of Radiology, St. Marianna University School of Medicine)
Description
Regarding that new molecular imaging technologies mostly emerge from isotopic
imaging, it is important to reevaluate preceding technologies of other modalities and
their current role in clinical medicine in order to understand what we presently know
and what are needed.
Among many modalities, MR spectroscopy (MRS) should be reemphasized because it is a
robust in-vivo technique which can detect intrinsic metabolite molecules in living
tissues and evaluate their concentrations. Proton (1H) and phosphorus (31P) MRS are
applied to patients using clinical high-field (higher than or equal to 1.5T) MR
units. Detectable metabolites by MRS are those related to the energy and membrane
metabolism, organ-specific functions, or fermentation processes, such as ATP,
(phospho)creatine, lactate, (phospho)choline, (phospho)ethanolamine, n-acetyl
aspartate in the brain, citrate in the prostate, amino acids, lipids, etc. Metabolite
signals are obtained from the defined region-of-interest in the tissue using a
sophisticated signal localization MR sequence. Measurement time is usually several
minutes in 1H MRS and 30 minutes in 31P MRS for a patient.
Analysis of signal intensities of metabolites in MR spectra is helpful for diagnosis
of diseases, like tumors, inflammation, infection and degenerative diseases.
Especially, treatment follow-up of patients is the another area of application of
MRS. Viability of cancer cells can be estimated based on signal intensities of ATP
and phosphocholine/phosphoethanolamine in a 31P MR spectrum; the former is a measure
of energy activity and the latter membrane turnover or cell proliferation rate.
Therefore, MRS provides a biochemical evaluation of treatment effect of cancers,
which otherwise can hardly be known. Although reduction in tumor size is accepted as
an indicator of an effective treatment, discrepancy is sometimes observed between
morphological evaluation and biochemical one; MRS suggests still a high viability of
cells in the reduced residual tumor. Further treatment or change of therapeutic
regimen are needed for those cases. Our experience will be presented.
As conclusions, reevaluation of MRS might accurately present needs for the emerging
new molecular imaging because MRS is the only available technique which provides in-vivo
biochemical information in clinical medicine.
Author
Dr
Keiko Imamura
(Department of Radiology, St. Marianna University School of Medicine)
Co-authors
Dr
Hisaya Nakajima
(Department of Orthopedic Surgery, St. Marianna University School of Medicine)
Prof.
Yasuo Nakajima
(Department of Radiology, St. Marianna University School of Medicine)
Dr
Yuko Kobashi
(Department of Radiology, St. Marianna University School of Medicine)
