Effect of Voxel Position on Single-Voxel MR Spectroscopy Findings
Peter E. Riccia,
Alan Pitta,
Paul J. Kellera,
Stephen W. Coonsa and
Joseph E. Heiserman
,a
a From the Departments of Neuroradiology (P.E.R., A.P., J.E.H.), MR Physics (P.J.K.), and Pathology (S.W.C.), Barrow Neurological Institute, Phoenix, AZ.
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FIG 1. Patient 20: 60-year-old woman with no significant medical history.
A, Axial enhanced T1-weighted MR image reveals focal enhancement in the left cerebral peduncle and thalamus. Spectroscopy voxel is placed at the anterior margin of enhancement.
B, MR spectrum reveals elevation of the Cho/Cr ratio, elevation of the lipid/lactate peak, and marked reduction of NAA. The pattern was interpreted as consistent with tumor and was proved to be a glioblastoma multiforme at biopsy.
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FIG 2. Patient 2: 48-year-old woman with a history of a glioblastoma multiforme treated with surgery, external beam radiation (59 Gy), and interstitial brachytherapy (58 Gy).
A, Axial T1-weighted MR image reveals enhancement of a right frontal lobe/insular lesion that has both solid and cavitary components. The spectroscopy voxel includes the medial margin of enhancement.
B, MR spectrum shows a prominent lipid/lactate peak with minimal residual Cho and Cr; NAA is absent. The pattern was thought to be consistent with radiation necrosis, and this diagnosis was confirmed at resection. This patient had subsequent follow-up spectroscopy studies at 1, 3, and 4 months that were unchanged (not shown).
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FIG 3. Patient 25: 58-year-old man with a new right frontal lobe mass.
A, Axial T1-weighted MR image reveals a multilobular cystic and solid mass in the right frontal lobe that contains peripheral and central enhancing regions. The spectroscopy voxel is positioned centrally in an enhancing portion of the tumor and does not include the enhancing edge.
B, MR spectrum reveals absence of discernible Cho, Cr, and NAA. The pattern was thought to be consistent with no tumor. The lesion was histologically shown to be a glioblastoma multiforme after resection.
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FIG 4. Patient 11: 68-year-old man with a history of a malignant glioma treated with surgical resection, external beam radiation (60 Gy), and interstitial brachytherapy (56 Gy) locally to the tumor bed.
A, Axial T1-weighted MR image obtained 8 weeks after radiation shows an enhancing mass in the right temporal lobe. There is no obvious cavitation/necrosis. The MR spectroscopy voxel is centrally positioned within the enhancing lesion.
B, The MR spectral pattern of a large lipid-lactate peak centered at 1.3 ppm and the absence of discernible Cho, Cr, or NAA were interpreted as consistent with no evidence of tumor. The lesion was completely resected and shown to be an equal mixture of glioblastoma and necrotic tissue. Because of the presence of a significant tumor component, the MR spectroscopy study was considered incorrect.
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FIG 5. Patient 22: 61-year-old man with no significant medical history.
A, Axial enhanced T1-weighted MR image reveals a cystic and solid mass at the right paramedian parieto-occipital junction. The spectroscopy voxel includes the medial and posterior enhancing margins of the lesion.
B, The spectral pattern of a large lipid-lactate peak, markedly reduced Cho, and absent Cr and NAA was interpreted as consistent with no evidence of tumor. The lesion was completely resected and shown to be a solitary metastasis.
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AJNR - American Journal of Neuroradiology