NEW ORLEANS — The combination of magnetic resonance spectroscopy with magnetic resonance imaging significantly improved the pretherapeutic diagnostic accuracy for pediatric brain tumors, according to findings from a retrospective study.
In a review of 122 children with newly detected brain tumors, Dr. Mark S. Shiroishi compared imaging reports with histopathologic findings. He found that the correct diagnosis was made 63% of the time (38/60) with contrast-enhanced magnetic resonance imaging (MRI). When magnetic resonance spectroscopy (MRS) was combined with contrast-enhanced MRI, the accuracy rate increased to 87% (54/62). MRI led to a partially correct diagnosis in 10% of cases (6/60), a rate that fell to 5% (3/62) when MRS was added.
Importantly, 27% of tumors (16/60) were incorrectly diagnosed with MRI alone, compared with 8% of those (5/62) who also underwent MRS. The difference in diagnostic accuracy between the two groups was statistically significant (P less than .01), said Dr. Shiroishi, a neuroradiologist at Childrens Hospital Los Angeles.
MR spectroscopy is a noninvasive way of monitoring the biochemical components of normal and abnormal brain tissue in vivo. MRS uses the same principles as MRI, but in MRS, a plot representing the chemical make-up of a region (rather than an image) is generated. MRS has proved useful in imaging tumors, infarcts, and epileptic foci.
“Spectroscopy allows us to readily distinguish … medulloblastomas, pilocytic astrocytomas, choroid plexus papillomas, and choroid plexus carcinomas,” said Dr. Shiroishi when he presented his findings at the annual meeting of the American Society of Neuroradiology.
“There is still a gray zone overlapping between anaplastic and regular astrocytomas and ependymomas,” he noted.