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Objective To explore the value of improved CT perfusion in delineation of brain arteriovenous malformation(AVM) target for stereotactic radiosurgery.Methods 22 patients diagnosed with AVM by DSA were included in this study.14 cases of AVM were detected from initial symptoms of intracereb.ral hemorrhage,of which 4 cases were given immediate intracranial hematoma evacuation,then in 3 cases postoperative embolization was performed,and other 10 cases received conservative treatment including 3 cases treated by embolization.8 cases of AVM were detected from initial symptoms of epilepsy or headache,without surgery or embolization treatment.In all patients,the improved CT perfusion and MRA examinations were performed before treatment to evaluate the diagnostic efficacy of different methods in AVM.Results The interference rates of hemorrhage and granulation tissue on MRA images were 27.3 ％ and 54.5 ％,respectively,while those on enhanced CT and improved CT perfusion images were 0 ％.The interference rate of embolization material on enhanced CT and improved CT perfusion images was 27.3％,while that on MRA images were 0％.The contrast-enhancement rates of MRA,CT and improved CT perfusion images were 4 5.5 ％,5 4.5 ％ and 7 2.7 ％,respectively.Conclusion Improved CT perfusion technique is helpful in delineation of brain AVM target for stereotactic radiosurgery in patients with AVM combined with intracerebral hemorrhage or postoperative patients.
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OBJECTIVE: To assess the effects of varying the number of diffusion gradient directions (NDGDs) on diffusion tensor fiber tracking (FT) in human brain white matter using tract characteristics. MATERIALS AND METHODS: Twelve normal volunteers underwent diffusion tensor imaging (DTI) scanning with NDGDs of 6, 11, 15, 21, and 31 orientations. Three fiber tract groups, including the splenium of the corpus callosum (CC), the entire CC, and the full brain tract, were reconstructed by deterministic DTI-FT. Tract architecture was first qualitatively evaluated by visual observation. Six quantitative tract characteristics, including the number of fibers (NF), average length (AL), fractional anisotropy (FA), relative anisotropy (RA), mean diffusivity (MD), and volume ratio (VR) were measured for the splenium of the CC at the tract branch level, for the entire CC at tract level, and for the full brain tract at the whole brain level. Visual results and those of NF, AL, FA, RA, MD, and VR were compared among the five different NDGDs. RESULTS: The DTI-FT with NDGD of 11, 15, 21, and 31 orientations gave better tracking results compared with NDGD of 6 after the visual evaluation. NF, FA, RA, MD, and VR values with NDGD of six were significantly greater (smallest p = 0.001 to largest p = 0.042) than those with four other NDGDs (11, 15, 21, or 31 orientations), whereas AL measured with NDGD of six was significantly smaller (smallest p = 0.001 to largest p = 0.041) than with four other NDGDs (11, 15, 21, or 31 orientations). No significant differences were observed in the results among the four NDGD groups of 11, 15, 21, and 31 directions (smallest p = 0.059 to largest p = 1.000). CONCLUSION: The main fiber tracts were detected with NDGD of six orientations; however, the use of larger NDGD (> or = 11 orientations) could provide improved tract characteristics at the expense of longer scanning time.
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Adult , Female , Humans , Male , Young Adult , Anisotropy , Diffusion Tensor Imaging/methods , White Matter/diagnostic imagingABSTRACT
Objective To explore the value of MR spectroscopy in preoperative grading of astrocytic tumors.Methods 52 cases with astrocytomas proved by pathology,including 20 diffuse astrocytomas,14 anaplastic astrocytomas and 18 glioblastomas,underwent MR spectroscopy with multi-voxel PRESS sequence.Results ①Astrocytic tumors were characterized by increased Cho and decreased NAA,while Lipids were present in high-grade astrocytic tumors;②Cho/Cr(r＝0.656,P=0.000),Lip1.3/Cr(r＝0.559,P=0.001) and Glx/Cr(r＝0.482,P=0.005) in the solitary tumor's regions had a significant positive correlation with the grading of astrocytic tumors, while Cho/NAA(r＝0.395,P=0.025),Lip0.9/Cr(r＝0.386,P=0.029) had a positive correlation with the tmor grading;③When Cho/Cr＝2, the sensitivity, specificity,positive predictive value and negative predictive value for diagnosis of WHO4 astrocytic tumors were 94.4%,64.3%,77.3% and 90% respectively;④When Lip1.3/Cr＝0.526, the sensitivity, specificity,positive predictive value and negative predictive value for diagnosis of WHO4 astrocytic tumors were 88.9%,92.9%,94.1% and 86.7% respectively. Conclusion MR spectroscopy is helpful in preoperative grading of astrocytic tumors.
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Objective To study the average ADC and eADC values in the C6 glioma regions and the contralateralnormal caudate nucleus of rat C6 glioma models on 3.0Tesla MR.Methods 32 healthy male Sprague-Dawley rats, weighted 250~300 g, were injected with C6 cells in right candate nucleus. All subjects were examined with MR imaging, including conventional and diffusion-weighted imaging with two b values ( 0 and 1000 s/mm~2 ) at 3.0T . ADC and eADC values were determined on ADC and eADC maps . Results The average ADC values in the C6 glioma regions and the contralateral normal caudate nucleus were(0.805?0.12)?10~ -3 mm~2/s and( 0.666?0.13 )?10~ -3 mm~2/s respectively ; the average eADC values in the C6 glioma regions and the contralateral normal caudate nucleus were (0.451?0.06) and (0.519?0.08) respectively. The difference of average ADC and eADC value between C6 glioma region and the contralateral normal caudate nucleus is significant. Conclusion It is feasible to do DWI in rat C6 glioma model with 3.0T MR and the ADC and eADC values measured in C6 glioma model can be used for reference in future studies.
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Objective To study the correlations between MR imaging and histological classification of intracranial meningiomas.Methods MR imaging findings of 128 cases of intracranial meningiomas proved by operation and pathology were analyzed retrospectively.Results On T 1-weighted images,29(49%) meningothelial meningiomas were hypointense, 11(19%) were slightly hypointense and 17(29%) were isointense, while fibrours meningiomas were respectively in 23(59%),5(13%) and 9(23%). On T 2-weighted images, 34(58%) meningothelial meningiomas were hyperintense, 15(25%) were slightly hyperintense and 10(17%) were isointense, while fibrours meningiomas were in 2(5%),8(20.5%) and 11(28%) respectively. Most of the intracranial meningiomas such as meningothelial, fibrours and transitional were iso- and hypo-intense to the cortex on T 1-weighted imaging. On T 2-weighted imaging, meningothelial, angiomatous and transitional were hyperintense or slightly hyperintense, while fibrous tended to be hypointense or slightly hypointense. Conclusion The signals of meningiomas of different histologic type on T 1-weighted images are no significant different.On T 2-weighted images,there are significant correlation between signal intensity and tumor histology.