In vivo single-voxel proton MR spectroscopy in brain lesions with ring-like enhancement
1Department of Neurosurgery, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan. tekimura-nsu@umin.ac.jp
Abstract:
It is often difficult to make a correct diagnosis of ring-like enhanced lesions on Gd-enhanced MR brain images. To differentiate these lesions using proton MR spectroscopy (1H-MRS), we retrospectively evaluated the correlation between the 1H-MR spectra and histopathological findings. We evaluated proton MR spectra obtained from the lesions in 45 patients, including metastasis (n = 19), glioblastoma (n = 10), radiation necrosis (n = 7), brain abscess (n = 5), and cerebral infarction (n = 4). The rate of misdiagnosis was found to be lowest at the threshold level of 2.48 for the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) obtained from the whole lesions, which include the enhanced rim and the non-enhanced inner region. That is, the positively predictive values of a Cho/Cr greater than 2.48 for diagnosing metastasis or glioblastoma was 88.9 and 60.0%, respectively, and the positively predictive value of a Cho/Cr less than 2.48 for diagnosing radiation necrosis or cerebral infarction was 71.4 and 100%, respectively. For further differentiating between metastasis and glioblastoma, information about the presence and absence of an N-acetyl-aspartate (NAA) peak and lipid- or lactate-dominant peak was found to be useful. In 73.7% of metastasis cases a lipid-dominant peak was observed in the whole lesion without an NAA peak in the inner region, whereas the same pattern was observed in only 10% of the glioblastoma cases. Correlation with the histopathological findings showed that a high Cho signal is suggestive of neoplasm. Lipid signal in the non-enhanced central region was correlated to necrosis. Lactate signals were often observed in glioblastoma, abscess and sometimes metastasis, presumably reflecting the anaerobic glycolysis by the living cells in the ring-like enhanced rim. Single-voxel proton MR spectroscopy may serve as a potential tool to provide useful information of differentiation of ring-like enhanced lesions that cannot be diagnosed correctly using enhanced MR images alone.
Insights
Proton MR spectroscopy (1H-MRS) aids in diagnosing brain lesions. A specific ratio of choline compounds to creatine (Cho/Cr) helps differentiate tumors like metastasis and glioblastoma from non-neoplastic conditions such as radiation necrosis and infarction.
Area of Science:
- Neurology
- Radiology
- Biochemistry
Background:
- Diagnosing ring-like enhanced lesions in brain MRIs is challenging.
- Proton MR spectroscopy (1H-MRS) offers potential for improved differentiation.
Purpose of the Study:
- To evaluate the correlation between 1H-MR spectra and histopathological findings for diagnosing ring-like enhanced brain lesions.
- To determine the diagnostic utility of the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) in differentiating various lesion types.
Main Methods:
- Retrospective analysis of 1H-MR spectra from 45 patients with diverse brain lesions (metastasis, glioblastoma, radiation necrosis, abscess, infarction).
- Correlation of spectral data with histopathological findings.
- Evaluation of the (choline containing compounds)/(creatine and phosphocreatine) ratio (Cho/Cr) as a diagnostic threshold.
Main Results:
- A Cho/Cr threshold of 2.48 demonstrated the lowest misdiagnosis rate.
- Positive predictive values for Cho/Cr > 2.48 were 88.9% for metastasis and 60.0% for glioblastoma.
- Positive predictive values for Cho/Cr < 2.48 were 71.4% for radiation necrosis and 100% for cerebral infarction.
- N-acetyl-aspartate (NAA) and lipid/lactate peaks aided differentiation between metastasis and glioblastoma.
- High Cho signals correlated with neoplasms, lipid signals with necrosis, and lactate signals with anaerobic glycolysis in viable cells.
Conclusions:
- Single-voxel proton MR spectroscopy provides valuable information for differentiating ring-like enhanced brain lesions.
- The Cho/Cr ratio is a useful marker, with additional spectral features enhancing diagnostic accuracy.
- 1H-MRS can supplement enhanced MR imaging for challenging diagnoses.
