|
|
Longitudinal multivoxel MR spectroscopy study of
pediatric diffuse brainstem gliomas treated with radiotherapy
Laprie A, Pirzkall A, Haas-Kogan DA, Cha S, Banerjee A, Le TP, Lu Y,
Nelson S, McKnight TR
Department of Radiology, University of California, San Francisco, San
Francisco, CA, USA; Department of Radiation Oncology, Claudius Regaud
Institute, Toulouse, France.
Background and Purpose. After radiotherapy (RT), children with diffuse
intrinsic pontine gliomas (DIPG) are followed with sequential magnetic
resonance imaging (MRI).
However, MRI changes do not necessarily reflect
tumor progression, and therefore additional noninvasive tools are needed to
improve the definition of progression vs. treatment-related changes.
In this
study, we determined the feasibility and accuracy of multivoxel proton
magnetic resonance spectroscopic imaging ((1)H-MRSI) for monitoring
pediatric patients with DIPG.
Methods and Patients. Twenty-four serial
examinations of MRI/MRSI (7 2D-MRSI and 17 3D-MRSI) were performed on 8
patients with DIPG who received local RT.
A total of 1635 voxels were
categorized as "normal" or "abnormal" based on
corresponding imaging findings on contrast-enhanced T1- and T2-weighted MRI.
The choline to N-acetyl-aspartate ratio (Cho:NAA) and choline to creatine
ratios (Cho:Cr) within each category of MRI abnormality were compared to
their counterpart in normal surrounding tissues.
The changes in these ratios
corresponding to each type of abnormality were evaluated before RT, at
response, and at recurrence, as determined by the clinical status of the
patients.
The presence or absence of lactate and lipid peaks was noted for
each voxel.
MRI/MRSI was performed on posterior fossa and supratentorial
tissue of 3 volunteer pediatric patients.
Results. The Cho:NAA and Cho:Cr
values within the imaging abnormalities (3.8 +/- 0.93 and 3.55 +/- 1.37,
respectively) were significantly higher than the mean values in
normal-appearing regions (0.93 +/- 0.2 and 1.13 +/- 0.38, respectively) (p
< 0.005).
Cho:NAA values decreased from studies at diagnosis to the time
of response to RT (3.12 +/- 0.5 and 2.08 +/- 0.73, respectively), followed
by an increase at the time of relapse (from 1.83 +/- 0.92 to 4.29 +/- 1.08).
Loss of lactate and lipid peaks correlated with response, and their presence
and stability with relapse.
In 3 patients, increased spectral abnormalities
preceded the radiological and clinical deterioration by 2-5 months.
Conclusion. Multivoxel MRSI is a feasible and reproducible noninvasive tool
for assessing pediatric DIPG.
Longitudinal multivoxel MRSI measurements have
potential value in assessing response to radiation or other therapies,
because they offer more coverage than single-voxel techniques and provide
reliable spectral data.
PMID: 15850898 [PubMed - in process]
|
