Bilateral Thalamic Gliomas-MRI & MRS

Primary thalamic tumors are rare and bilateral thalamic tumors are even rarer. The incidence, clinical manifestations, natural history and prognosis of primary bilateral thalamic gliomas (PBTT) remain relatively obscure.  Spectroscopy reveals raised choline-creatinine ratio.

Reported by Teleradiology Providers

Glioma MRS

This is classical MR spectroscopy findings of thalamic glioma.

Hippocampus-MR Spectroscopy

"According to King et al in Radiology 2008;249:242-250 there is significant metabolic heterogeneity along anteroposterior axis of healthy hippocampus. Mean NAA, creatine, and choline concentrations are higher in posterior hippocampus than anterior hippocampus. Thereby implying that consistent voxel placement are important for correct comparisons of both absolute metabolic levels and metabolite ratios."

Prostate MRS

The prostate lends itself to MRS due to its unique production, storage, and secretion of citrate. While healthy prostate tissue demonstrates high levels of citrate and low levels of choline that marks cell wall turnover, prostate cancer (PCA) utilizes citrate for energy metabolism and shows high levels of choline. The ratio of (choline + creatine)/citrate differentiates healthy prostate tissue and PCA. The combination of magnetic resonance imaging (MRI) and 3-dimensional MRS (3D-MRSI or 3D-CSI) of the prostate localizes PCA to a sextant of the peripheral zone of the prostate with sensitivity/specificity of up to 80/80%.

Further reading-

Radiologe 2003 Jun;43(6):481-8.

Eur J Radiol 2007 Sep;63(3):351-60. Epub 2007 Aug 20

Radiology Grand Rounds XXIII

Here is a case of Cannavan's Disease for the Radiology Grand Rounds submitted by Dr Sumer Sethi of Teleradiology Providers. Concept and Archive of the Radiology Grand Rounds is available at- Radiology Grand Rounds.

Canavan’s disease
Deficiency of N- acetylaspartate cyclase enzyme – Increase in NAA.

"Canavan disease demonstrates bilateral symmetric T2 white matter hyperintensity, including involvement of the subcortical arcuate fibers. This disease appears diffusely throughout the cerebral white matter, does not enhance at computed tomography (CT) or MR imaging, and demonstrates variable involvement of the basal ganglia and cerebellar white matter. For example, both Canavan disease and Alexander disease demonstrate macrocephaly with bilaterally symmetric increased T2 signal intensity of cerebral white matter and involvement of subcortical arcuate fibers. MR spectroscopy, however, has been shown to be a useful diagnostic tool in making this distinction. There is an accumulation of NAA in patients with Canavan disease because of a deficiency in the myelin synthesis pathway; thus, MR spectroscopy reveals a markedly elevated NAA peak. "

In other white matter diseases there is Axonolysis hence NAA decreases, Defective myelination leads to increased Choline and lactate is seen in the activer disease.

Further reading (Radiology 2006;241:310-324.)

Hope you enjoyed this edition of Radiology Grand Rounds submissions are requested for the next Radiology Grand Rounds posted every month last sunday. If you interested in hosting any of the future issues contact me at sumerdoc-AT-yahoo-DOT-com.

Case by-Dr.Sumer K Sethi, MD
Consultant Radiologist ,VIMHANS and CEO-Teleradiology Providers
Editor-in-chief, The Internet Journal of Radiology
Director, DAMS (Delhi Academy of Medical Sciences)

MR Spectroscopy in Meningioma

MR spectroscopy may provide additional information in cases in which the differential diagnosis
of tumors by neuroimaging is difficult. Cho reflects membrane turnover, correlates with malignancy in astrocytic tumors, and forms high peaks in meningioma. The most common proton spectrum found in meningiomas is a high Cho peak with low or absent NAA and Cr and variable amounts of lactate. Most important, an unusually high ratio of Ala to Cr has been found in meningiomas because of the high Ala and low Cr content, and this is a relatively specific finding for meningioma. Alanine is seen as doublet centered at 1.47 ppm and inverts on the long-TE sequence.

Reference- AJNR Am J Neuroradiol 20:882–885, May 1999