clinical application MRS

CLINICAL APPLICATION OF PROTON MAGNETIC RESONACE SPECTROSCOPY (1H-MRS) IN THE DIAGNOSIS OF INTRA-AXIAL BRAIN TUMOR IN ADULTS Cao Thiên Tượng Phạm Ngọc Hoa Introduction     Diagnosis of brain tumors based on CT and conventional MRI is still challenging problem Magnetic resonance spectroscopy (MRS) is advanced technique being used to diagnosis brain tumors and other neurologic diseases in many countries This technique provides information related to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumor tissues MRS can help to differentiate between neoplastic and non-neoplastic lesions, evaluate tumor tissue and edema, predict grading of glioma, localize biopsy site, evaluate after treatment (surgery, radiotherapy…) Metabolites in the brain in proton spectroscopy at 135ms TE, 1.5T (*) Abbreviation Metabolite Frequency Significance Cho Phosphocholine, Glycerophosphorylcholine 3.22 ppm Membrane turnover, cell proliferation Cr Creatine and phosphocreatine 3.03 and 4ppm Temporal store for energy-rich phosphates NAA N-acetyl-L-aspartate 2.01ppm Indicates the presence of intact glioneural structures Exact function unknown Lac Lactacte 1.33ppm (inverte d) doublet Anaerobic glycolysis Lipids Free fatty acide 1.2-1.4 ppm Necrosis (*) Delorme, S and M.A Weber, Applications of MRS in the evaluation of focal malignant brain lesions Cancer Imaging, 2006 6: p 95-9 1H-MRS in the brain of normal indiviual Signal intensity Resonance frequency Summary of MRS findings for brain lesions (*) Pathology MRS Cho/Cr Cho/Cho (n) NAA/Cr High-grade glioma Very high Very high Very low Low-grade glioma High High Low Gliomatosis cerebri Normal/High Normal/High Low Embryonal tumors Very high Very high Low Meningioma High High Low Metastases High High Low Radiation necrosis Low Low Low Abscess Mod Mod Low Demyelination High High Slight low Infarct High Low Low Contusion/Hematoma Mod Mod Low Cho/Cho(n): Cho lesion/cho contralateral (*) Law, M., MR spectroscopy of brain tumors Topics in Magnetic Resonance Imaging, 2004 15(5): p 291-313 Objectives  Evaluate the clinical application of proton magnetic resonance spectroscopy (1H-MRS) for differentiation of intra-axial neoplastic and non-neoplastic lesions in adults  Predicting grade of glioma by 1HMRS Material and methods (1)    Adult patients admitted to the department of neurosurgery of Cho Ray hospital with supratetorial intra-axial brain lesion suspiciuos for a neoplasm on clinical examination and conventional MR imaging Those patients had confirmed on pathologic examination (n=26) Patients with cerebral infarct based on clinical examination and follow-up after treatment in the department of neurology of Cho Ray hospital (n=3) Normal individuals (n=11) Material and methods (2)     Prospective study Study duration from Jun 2008 to Oct 2008 Patients are examined by conventional MR imaging on 1T MRI unit (Harmony, Siemens, Erlangen, Germany) or 1.5 Tesla unit (Avanto, Siemens, Erlangen, Germany) Multivoxel 1H-MRS examination is performed on 1.5 Tesla MRI unit (Avanto, Siemens, Erlangen, Germany) with a ̣2D-Chemical shift imaging technique [TR/TE: 1500/135ms] Material and methods (3)     Automated postprocessing was performed with NUMARIS software package, version Syngo MR B 15 (Siemens) Cho (3.22ppm), Cr (3.02ppm), NAA (2.02ppm) were identified Lactate peak (1.3ppm) was noted by qualitative analysis Calculate ratios: Lesion Cho / contralateral side Cho (Abv nCho), lesion NAA / contralateral side NAA (abv nNAA), Lesion Cho /lesion Cr (abv lChocr), lesion Cho /lesion NAA (Abv lChoNAA), Lesion NAA /lesion Cr (abv lNAACr), Lesion Cho/ contralateral side Cr and lesion NAA /contralateral side Cr Statistical analysis by SPSS software 10.0.5 (SPSS Inc, Chicago, IL, USA) and Medcalc Results 26 cases have histopathologic result +20 gliomas were graded according to WHO classification from Grade I to Grade IV (grade I, n=1; grade II, n=8, grade III, n=8, grade IV, n=3), including 19 astrocytomas and oligodendroglioma +2 brain metastase +1 CNS lymphoma +3 brain abscesses  Normal, contralateral A 18-yearold man with giant cell astrocyto ma grade IV Lac A 64-yearold man with brain metastasis Normal, contralateral Normal, contralateral A 46-year-old man with brain abscess Lac Normal, contralateral A 24-year-old man with brain infarct Discussion (1) Our result indicates elevated Cho (nCho) in tumor cases (mean 2.39) compared to nonneoplastic lesions (mean 0.88) In the ROC curve, a nCho > 1.32, predicted tumor with sensitivity 91.3%, Specificity 100%, PPV 100%, NPV 75%  Study of Nagar VA et al (*) showed nCho> in tumor lesions and nCho< in non-tumor lesions Several other studies have shown similar results  This result indicates Cho could be used as an MRS biomarker in predicting of brain tumor  (*) Nagar, V.A., et al., Multivoxel MR spectroscopic imaging distinguishing intracranial tumours from non-neoplastic disease Ann Acad Med Singapore, Discussion (2)    nNAA significantly decreases in tumor case (mean: 0.24) compared to non-tumor cases (mean: 0.52) Decrease NAA in gliomas may indicate a decrease or displacement of neurons by tumor (*) Although decrease in NAA can be found in non-neoplastic diseases as infarction, hypoxic-ischemic encephalopathy…, The decrease in NAA is also indicator to suggest brain tumor Tien, R.D., et al., Single-voxel proton brain spectroscopy exam (PROBE/SV) in patients with primary brain tumors AJR Am J Roentgenol, 1996 167(1): p 201-9 Result of Hourani & al.(*) and our study Metabolite Tumor Non-tumor p Hourani R& al N=36 Our study N=23 Hourani R& al N=33 Our study N=6 nCho 2.00±0.98 2.39 ±1.17 1.19±0.49 0.88 (0.35) P