ABSTRACT
Background and Purpose: Grading of brain tumors carries great importance in its evaluation and management. The aim of this work was to evaluate the role of apparent diffusion coefficient [ADC] and multivoxel chemical shift proton spectroscopy in grading of various brain lesions
Subjects and Methods: This study was conducted on 35 patients with brain tumors [11 high grade and 7 low-grade glioma, 7 metastases, 6 meningiomas, and 4 tuberculomas]. They presented with various combinations of neurologic manifestations [headache [24 patients], convulsions [11], focal neurologic deficits [27] and altered sensorium [6]]. They were prospectively evaluated with contrast material-enhanced MR imaging, multi-voxel proton MR spectroscopy [TE = 270 ms], and diffusion-weighted imaging [b = 0, 500, and 1000 s/mm2] before surgery
Results: MR spectroscopy could differentiate benign from malignant tumors but was not useful in grading malignant tumors. In the differentiation of malignant from benign tumors, N-acetylaspartate [NAA]/choline [Cho] and Cho/ creatine [Cr], ratios [P < 0.001] were statistically more significant than NAA/Cr. Lipid and lactate peacks were detected in 8 cases of high grade glioma and 6 cases of matastases but was not detected in any case of low grade glioma. ADCs were effective for grading malignant tumors [P < 0.001] but not for distinguishing different tumor types with the same grade. High-grade malignant tumors [0.85+8 x 10-3 mm2/s] had significantly lower ADC values than did low-grade malignant [1.15 + 9 x 10-3 mm2/s] and benign [1.08 + 12 x 10-3 mm2/s] tumors. Peritumoral ADCs were insignificant in differentiation between high and lowgrade glioma as well as between edema and non enhanced peritumoral infiltration
Conclusion: Combination of calculated ADC values from tumoral core and specific relative metabolite ratios acquired by MR spectroscopy added more information to MR imaging in the differentiation and grading of brain tumors
Subject(s)
Humans , Male , Female , Aged , Magnetic Resonance Spectroscopy , Diagnostic Techniques and Procedures , Neoplasm StagingABSTRACT
The aim of this study was to evaluate the role of cho/cr ratio in MR spectroscopy [MRS] in differentiation between recurrent tumor and radiation necrosis in equivocal brain lesions following radiotherapy for brain tumors. Hydrogen [1H] MR spectroscopy was performed for 17 patients presented with recent neurological manifestations and / or their CT or MRI examination revealed an equivocal brain lesion during follow up after completion of radiotherapy for brain tumor [gliomas [12], medulloblastoma [3] and ependymoma [2]]. Volume of interest [VOI] was placed inside the lesion in T2 WIs [high SI] using single voxel spectroscopy in 7 patients and chemical shift for 10 patients according to the size and homogenecity of the lesion.Ratios of peak areas under the choline [Cho] and creatine [Cr] resonance were estimated in all cases and compared with those from samples of normal brain tissue. The Cho/Cr ratios in cases of tumor recurrence [1.5 +/- 0.6] were elevated compared to those in normal brain tissue while there was a reduction of Cho/Cr ratio [0.4 +/- 0.3] in radiation necrosis compared to normal brain. We also reported an obvious increase of Cho/Cr ratio in tumor recurrence than radiation necrosis. Cho/Cr ratio in MR Spectroscopy represents a recent helpful modality to differentiate between tumor recurrence and radiation necrosis in follow up of brain tumor patients after completion of radiotherapy