MR volumetry of the entorhinal, perirhinal, and temporopolar cortices in drug-refractory temporal lobe epilepsy

BACKGROUND AND PURPOSE: The occurrence of damage in the entorhinal, perirhinal, and temporopolar cortices in unilateral drug-refractory temporal lobe epilepsy (TLE) was investigated with quantitative MR imaging. METHODS: Volumes of the entorhinal, perirhinal, and temporopolar cortices were measured in 27 patients with unilateral drug-refractory TLE, 10 patients with extratemporal partial epilepsy, and 20 healthy control subjects. All patients with TLE were evaluated for epilepsy surgery and underwent operations. RESULTS: In left TLE, the mean volume of the ipsilateral entorhinal cortex was reduced by 17% (P <.001 compared with control subjects) and that of the ipsilateral temporopolar cortex by 17% (P <.05). In right TLE, the mean ipsilateral entorhinal volume was reduced by 13% (P < or =.01), but only in patients with hippocampal atrophy. Asymmetry ratios also indicated ipsilateral cortical atrophy. When each patient was analyzed individually, the volume of the ipsilateral hippocampus was reduced (> or = 2 SD from the mean of controls) in 63% and that of the entorhinal cortex in 52% of patients with TLE. Furthermore, ipsilateral entorhinal (left: r = 0.625, P <.001; right: r = 0.524, P < or =.01), perirhinal (left: r = 0.471, P <.05), and temporopolar (right: r = 0.556, P <.01) volumes correlated with ipsilateral hippocampal volumes. There was no association, however, with clinically or pathologically identified causes of epilepsy, duration of epilepsy, or age at onset of epilepsy. Mean cortical volumes were unaffected in extratemporal partial epilepsy. CONCLUSION: Subpopulations of patients with unilateral TLE have ipsilateral damage in the entorhinal and temporopolar cortices. The damage is associated with hippocampal damage.     

MR volumetric analysis of the piriform cortex and cortical amygdala in drug-refractory temporal lobe epilepsy

BACKGROUND AND PURPOSE: The assessment of patients with temporal lobe epilepsy (TLE) traditionally focuses on the hippocampal formation. These patients, however, may present structural abnormalities in other brain areas. Our purpose was to develop a method to measure the combined volume of the human piriform cortex and cortical amygdala (PCA) by using MR imaging and to investigate PCA atrophy. METHODS: The definition of anatomic landmarks on MR images was based on histologic analysis of 23 autopsy control subjects. Thirty-nine adults with chronic TLE and 23 age-matched control subjects were studied. All underwent high-spatial-resolution MR imaging at 1.5T, including a tilted T1-weighted 3D dataset. The PCA volumes were compared with the control values and further correlated with hippocampal, amygdala, and entorhinal cortex volumes. RESULTS: The normal volume was 530 +/- 59 mm(3) (422-644) [mean +/- 1 SD (range)] on the right and 512 +/- 60 mm(3) (406-610) on the left PCA (no asymmetry, and no age or sex effect). The intraobserver and interobserver variability were 6% and 8%, respectively. In right TLE patients, the mean right PCA volume was 18% smaller than in control subjects (P < .001) and 15% smaller than in left TLE (P < .001). In left TLE, the mean left PCA volume was 16% smaller than in control subjects (P < .001) and 19% smaller than in right TLE (P < .001). Overall, 46% (18/39) of the patients had a greater than 20% volume reduction in the ipsilateral PCA. There was bilateral atrophy in 18% (7/39). Patients with hippocampal volumes of at least 2 SDs below the control mean had an 18% reduction in the mean PCA volume compared with patients without hippocampal atrophy (P < .001). Ipsilaterally, hippocampal (r = 0.756, P < .01), amygdaloid (r = 0.548, P < .01), and entorhinal (r = 0.500, P < .01) volumes correlated with the PCA volumes. CONCLUSION: The quantification of PCA volume with MR imaging showed that the PCA is extensively damaged in chronic TLE patients, particularly in those with hippocampal atrophy.     

Degree of hippocampal atrophy is related to side of seizure onset in temporal lobe epilepsy

BACKGROUND AND PURPOSE: Temporal lobe epilepsy (TLE) is associated with pathologic changes in hippocampal physiology and morphology. Our aim was to quantify volume reduction of the right and left hippocampus in patients with TLE and to investigate whether the degree of hippocampal atrophy is related to the side of seizure onset. METHODS: The volume of the right and left hippocampus was estimated for 50 controls and 101 patients with TLE, by applying the unbiased Cavalieri method on MR images. RESULTS: Pairwise comparisons, within a multivariate analysis of variance and adjusted by using the Bonferroni correction, revealed that both right and left hippocampal volumes were, on average, significantly smaller in patients with right-sided seizure onset (R-patients) relative to those of controls (P < .001 and P = .04, respectively). Furthermore, left hippocampal volume was significantly smaller in patients with left-sided seizure onset (L-patients) compared with controls (P < .001), but the right-sided hippocampal volume was not significantly smaller (P = .71). Moreover, a correlation analysis revealed that the strong linear association between the right and left hippocampal volumes existing in the control population (r = 0.73) is partially lost in patients with TLE (r < or = 0.48), and this loss in correlation appears to be more pronounced in L-patients than in R-patients. CONCLUSION: Our MR imaging results suggest that although the major damage in patients with TLE is located in the hippocampus ipsilateral to the side of seizure onset, R-patients are more likely to have bilateral hippocampal volume reduction. These findings support the hypothesis that cerebral hemispheres may not only differ in their functionality organization but also in their vulnerability to a neurologic insult.     

5-HT 1A receptors are reduced in temporal lobe epilepsy after partial-volume correction.

Preclinical studies suggest that serotonin 1A receptors (5-HT 1A) play a role in temporal lobe epilepsy (TLE). Previous PET studies reported decreased 5-HT 1A binding ipsilateral to epileptic foci but did not correct for the partial-volume effect (PVE) due to structural atrophy. METHODS: We used PET with 18F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexanecarboxamide (18F-FCWAY), a 5-HT 1A receptor antagonist, to study 22 patients with TLE and 10 control subjects. In patients, 18F-FDG scans also were performed. An automated MR-based partial-volume correction (PVC) algorithm was applied. Psychiatric symptoms were assessed with the Beck Depression Inventory Scale. RESULTS: Before PVC, significant (uncorrected P < 0.05) reductions of 18F-FCWAY binding potential (BP) were detected in both mesial and lateral temporal structures, mainly ipsilateral to the seizure focus, in the insula, and in the raphe. Group differences were maximal in ipsilateral mesial temporal regions (corrected P < 0.05). After PVC, differences in mesial, but not lateral, temporal structures and in the insula remained highly significant (corrected P < 0.05). Significant (uncorrected P < 0.05) BP reductions were also detected in TLE patients with normal MR images (n = 6), in mesial temporal structures. After PVC, asymmetries in BP remained significantly greater than for glucose metabolism in hippocampus and parahippocampus. There was a significant inverse relation between the Beck Depression score and the ipsilateral hippocampal BP, both before and after PVC. CONCLUSION: Our study shows that in TLE patients, reductions of 5-HT 1A receptor binding in mesial temporal structures and insula are still significant after PVC. In contrast, partial-volume effects may be an important contributor to 5-HT 1A receptor-binding reductions in lateral temporal lobe. Reduction of 5-HT 1A receptors in the ipsilateral hippocampus may contribute to depressive symptoms in TLE patients.     

Evidence of neuronal injury outside the medial temporal lobe in temporal lobe epilepsy: N-acetylaspartate concentration reductions detected with multisection proton MR spectroscopic imaging--initial experience

PURPOSE: To determine whether magnetic resonance (MR) spectroscopic imaging reveals metabolic changes, especially decreased N-acetylaspartate (NAA) concentrations outside the medial temporal lobe in patients with mesial temporal lobe epilepsy (TLE), consistent with neuropathologic findings of extratemporal neuronal impairment. MATERIALS AND METHODS: Eleven patients with mesial TLE and 13 control subjects were examined with multisection MR spectroscopic imaging. Three MR spectroscopic imaging sections were acquired. Thirteen brain regions in each hemisphere and the midbrain were analyzed in each patient, and the NAA to creatine-phosphocreatine (Cr) plus choline-containing compounds (Ch) (NAA/[Cr + Ch]) ratios were determined. In addition, hemispheric and whole-brain values were calculated and statistically analyzed. RESULTS: The NAA/(Cr + Ch) ratio in the ipsilateral hippocampus was significantly reduced, compared with that in the contralateral hippocampus (P <.002) and compared with that in control subjects (P <.03), confirming findings in previous studies. In patients, whole-brain NAA/(Cr + Ch) ratio outside the hippocampus was significantly lower than that in control subjects (P <.002). For the ipsilateral hemisphere in patients, NAA/(Cr + Ch) ratio was significantly lower than that in control subjects (P <.0002). Comparisons between individual brain regions revealed trends toward lower NAA/(Cr + Ch) ratios in many areas of the ipsilateral and, to a lesser extent, the contralateral hemisphere outside the hippocampus and temporal lobe, suggesting diffuse impairment. CONCLUSION: Results suggest that repeated seizure activity damages neurons outside of the seizure focus.     

Monitoring of acute generalized status epilepticus using multilocal diffusion MR imaging: early prediction of regional neuronal damage

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging (DWI) has emerged as tool for noninvasive and early detection of neuronal alterations. The aim of this study was to investigate the evolution of acute phase changes in different brain regions during experimental status epilepticus (SE) using DWI correlated with SE-induced neuronal cell loss. METHODS: DWI was performed in 20 rats before (baseline) and 3, 5, 10, 15, 20, 30, 45, 60, 90, and 120 minutes after onset of pilocarpine-induced SE. Apparent diffusion coefficients (ADCs) were calculated for the parietal cortex, temporal cortex, pyriform cortex, hippocampus, amygdala, and thalamus and compared with baseline. Neuronal cell loss was quantified at different time points after SE using cresyl-violet-staining. RESULTS: ADC-mapping demonstrated a significant transient increase in ADC (to 116 +/- 4% of baseline) in the very acute phase, starting 3 minutes after SE onset, lasting for 10 minutes, followed by a significant gradual decline in ADC in all animals. Compared with surviving animals (76 +/- 7%), decline in ADC was significantly lower for the animals who died within 2 hours for all regions of interest (63 +/- 6.5%, 0.45 +/- 0.03 x 10(-3) mm(2)/s) except the thalamus (P < .01, analysis of variance). There was good correlation between neuronal cell loss in specific brain regions 2 weeks after SE and maximal decrease in ADC (r > 0.76). CONCLUSION: Serial ultrafast DWI is a sensitive noninvasive technique for early detection and monitoring of seizure-induced neuronal alterations. Using ADC-mapping differentiation of regional severity of neuronal damage may be possible because there is good correlation between the maximal decrease in ADC in the acute phase of SE and late neuronal cell loss.     

磁共振多种成像方法在颞叶癫痫的综合诊断

目的 应用MR不同成像方法探讨MRI对颞叶癫痫的诊断价值。资料与方法 设对照组40例，颞叶癫痫组(TLE)20例，颞叶外癫痫组(ELE)21例。应用MRI测量并比较对照组及TLE、ELE组间海马结构(HF)体积差异，行TLE组致痫侧评判。应用扩散加权成像(DWI)测量并比较对照组与TLE患侧、对侧、ELE组间表观弥散系数(ADC)值差异。应用1H MRS对各组分别进行单体素波谱(SVS)和化学位移成像(CSI)，SVS时比较TLE患侧、对侧及对照组各代谢物比值差异，对TLE组行致痫灶定侧诊断。CSI时分析HF从前到后NAA／(Cho Cr)的变化规律。结果TLE组患侧HF体积、NAA／(Cho Cr)值下降，ADC值升高，与对照组差异有显著性。定量MRI、SVS对TLE组定侧敏感性分别为70％、85％，特异性分别为87．5％、95％。CSI示HF的NAA／(Cho Cr)与HF部位间呈直线相关关系，TLE时前部改变较后部大。结论 定量MRI、SVS可帮助TLE致痫灶定侧，SVS更敏感、特异，两者结合后价值更大。CSI显示HF从前到后代谢物浓度渐变现象，TLE组头部改变较尾部大。DWI可作为MRI诊断颞叶癫痫的补充。     

Multisection proton MR spectroscopy for mesial temporal lobe epilepsy

BACKGROUND AND PURPOSE: Extensive metabolic impairments have been reported in association with mesial temporal lobe epilepsy (mTLE). We investigated whether proton MR spectroscopy ((1)H-MRS) depicts metabolic changes beyond the hippocampus in cases of mTLE and whether these changes help lateralize the seizure focus. METHODS: MR imaging and (1)H-MRS were performed in 15 patients with mTLE with a postoperative diagnosis of mesial temporal sclerosis and in 12 control volunteers. Point-resolved spectroscopy and multisection (1)H-MRS measured N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampus, temporal opercular and lateral cortices, insula and cerebellum, and frontal, parietal, and occipital lobes. Metabolites were assessed as ratios to Cr and in absolute units. RESULTS: Twelve patients had ipsilateral hippocampal atrophy; three had negative imaging results. In the ipsilateral hippocampus, absolute NAA (/NAA/) was 27.3% lower in patients compared with that in control volunteers (P <.001) and 18.5% lower compared with that in the contralateral side (P <.01). /NAA/ averaged over selected regions in the ipsilateral temporal lobes of patients with mTLE was 19.3% lower compared with the mean in the control group (P <.0001) and by 17.7% lower compared with the contralateral values (P <.00001). Using only hippocampal data, 60% of the cases of mTLE were correctly lateralized. Lateralization, determined using whole temporal lobe data, had 87% sensitivity and 92% specificity. /NAA/ was bilaterally reduced in the frontal, parietal, and occipital lobes of patients with mTLE compared with that in control volunteers (P <.01). CONCLUSION: Multisection (1)H-MRS depicts interictal reductions of NAA in the ipsilateral temporal lobe beyond the hippocampus and accurately lateralizes seizure foci.     

Cerebral blood flow in temporal lobe epilepsy: a partial volume correction study

Purpose Previous studies in temporal lobe epilepsy (TLE) have shown that, owing to brain atrophy, positron emission tomography (PET) can overestimate deficits in measures of cerebral function such as glucose metabolism (CMR_glu) and neuroreceptor binding. The magnitude of this effect on cerebral blood flow (CBF) is unexplored. The aim of this study was to assess CBF deficits in TLE before and after magnetic resonance imaging-based partial volume correction (PVC). Methods Absolute values of CBF for 21 TLE patients and nine controls were computed before and after PVC. In TLE patients, quantitative CMR_glu measurements also were obtained. Results Before PVC, regional values of CBF were significantly (p<0.05) lower in TLE patients than in controls in all regions, except the fusiform gyrus contralateral to the epileptic focus. After PVC, statistical significance was maintained in only four regions: ipsilateral inferior temporal cortex, bilateral insula and contralateral amygdala. There was no significant difference between patients and controls in CBF asymmetry indices (AIs) in any region before or after PVC. In TLE patients, AIs for CBF were significantly smaller than for CMR_glu in middle and inferior temporal cortex, fusiform gyrus and hippocampus both before and after PVC. A significant positive relationship between disease duration and AIs for CMR_glu, but not CBF, was detected in hippocampus and amygdala, before but not after PVC. Conclusion PVC should be used for PET CBF measurements in patients with TLE. Reduced blood flow, in contrast to glucose metabolism, is mainly due to structural changes.     

Evolution of water diffusion and anisotropy in hyperacute stroke: significant correlation between fractional anisotropy and T2

BACKGROUND AND PURPOSE: We hypothesized that, in acute cerebral ischemic stroke, anisotropic diffusion increases if T2 signal intensity is not substantially elevated and decreases once T2 hyperintensity becomes apparent. Our purpose was to correlate fractional anisotropy (FA) measurements with the clinical time of stroke onset, apparent diffusion coefficients (ADC), and T2 signal intensity. METHODS: Tensor diffusion-weighted images (DWIs) of 25 patients were obtained within 12 hours of symptom onset. Trace DWIs, ADCs, FAs, and echo-planar T2-weighted images (T2WI) were generated. Stroke and contralateral normal volumes of interest (VOIs) were outlined on DWIs and projected onto the inherently coregistered ADC map, FA map, and echo-planar T2WI. Mean signal intensity of the ischemic and contralateral normal VOIs were compared for relatives change in ADC, FA, and signal intensity on T2WIs. RESULTS: A significant negative correlation was observed between FA and T2 signal-intensity change (r = -0.61, P =.00009). A trend of correlation between FA signal intensity and time of onset were found (r = -0.438, P =.025). No significant correlation was found between ADC and FA values (r = -0.302, P =.134). The mean ADC reduction in the ipsilateral ischemic volume was 31% +/- 11 compared with the contralateral normal side. CONCLUSION: Change in FA is inversely correlated with T2 signal intensity and, to a lesser extent, the time of onset, but it is not well correlated with ADC values in the acute stage.     

Hippocampal alterations in children with temporal lobe epilepsy with or without a history of febrile convulsions: evaluations with MR volumetry and proton MR spectroscopy

BACKGROUND AND PURPOSE: The causal effect of early febrile convulsions (FC) on later-onset temporal lobe epilepsy (TLE) remains unclear. In this study, we sought to examine the hippocampal alterations in epileptic children with or without FC history by using MR spectroscopy and volumetry. METHODS: Fifty-five children ranging in age from 18 months to 15 years were enrolled in this study. Subjects were divided into three groups: the control group without either TLE or history of FC (n = 16), the TLE group with early history of FC (TLE + FC; n = 22), and the TLE group without FC history (n = 17). Measurement of hippocampal volume (HV) was performed on thin section T1-weighted images acquired with a 3D gradient echo MR image and normalized by the intracranial volume. Each individual subject had two measures of lateralization; one gives the smaller side of HV and the other the contralateral larger side of HV, assuming that the side with smaller HV is the possible primary site of seizure focus and the contralateral larger HV the secondary or normal site. Single-voxel proton MR spectroscopy of the hippocampi was performed, with metabolic ratio n-acetylaspartate (NAA)/choline (Cho) + creatine plus phosphocreatine (Cr) calculated and grouped separately as were with volumetry. RESULTS: The overall mean HV for the control group was 2.61 +/- 0.21 cm(3) at an average intracranial volume of 965 +/- 241 cm(3), and the asymmetry index for hippocampal volume was (2.32 +/- 1.58)%. The overall mean HV was 2.30 +/- 0.33 cm(3) for TLE + FC group and 2.34 +/- 0.33 cm(3) for TLE group. Mean HV differed significantly for the three groups (P < .01). When the small and large sides were analyzed separately, significant differences were found between control and TLE as well as between control and TLE + FC for the smaller side (P < .05), whereas for the larger side significant differences were found only between control and TLE + FC. In MR spectroscopic measurements, the mean NAA/(Cr + Cho) of bilateral hippocampi was 0.77 +/- 0.06 for control group, 0.62 +/- 0.12 for TLE + FC group, and 0.66 +/- 0.11 for TLE group. In terms of statistically significant difference between groups, spectroscopic results were similar to volumetric measurements, except that there was no significant interaction effect between groups and measures of asymmetrical indices (P = .272). CONCLUSION: Children with TLE and early history of FC tend to have lower hippocampal volumes and NAA/(Cr + Cho) ratios than do TLE children without FC history. The TLE + FC group seems to have increased vulnerability of the contralateral hippocampus as compared with TLE group. MR volumetry and spectroscopy are equally capable of showing the trends of hippocampal alternations in children with TLE with or without FC history.     

A fast FLAIR dual-echo technique for hippocampal T2 relaxometry: first experiences in patients with temporal lobe epilepsy

To evaluate the use of cerebrospinal fluid (CSF) signal nulling in MR T2 measurements of the hippocampus in normal control subjects and patients with temporal lobe epilepsy (TLE), dual-echo acquisitions covering the whole brain were used. T2 relaxation times were estimated in 12 standard Eurospin II MR test objects and in the hippocampi of 10 control subjects, using T2 maps constructed from conventional spin-echo (CSE), fast spin-echo (FSE), and fast FLAIR (FF) dual-echo sequences on a 1.5-T MR scanner. Hippocampal T2 values (HCT2) were measured on contiguous coronal 5-mm slices throughout the antero-posterior extent of each hippocampus in the 10 controls and 12 TLE patients, using both CSE and FF. Scan-rescan reproducibility in Eurospin II standard MR test objects was high for all sequences. There was a good correlation between T2 values from CSE, FF, and FSE sequences in test objects and in control hippocampi. In controls, the coefficient of variation of mean HCT2 values differed between slice positions, but was lowest for FF, followed by CSE data. The intrarater coefficient of reliability between repeated measurements in control subjects was lowest for FF HCT2, at 2.3%. The interrater coefficient of reliability for CSE HCT2 measurements in controls (4.8%) was slightly lower than the interrater coefficient for FF HCT2 (5.4%). HCT2 measurement with both CSE and FF identified abnormal values in the same 10 hippocampi of 12 patients. Hippocampal dual-echo T2 relaxometry using CSF nulling is reliable in control subjects, and identifies the abnormal hippocampi in patients with TLE. The increases in hippocampal T2 signal demonstrated using FF HCT2 measurements are unlikely to be partial volume effects from CSF.     

Hyperpolarized 3He magnetic resonance imaging of chronic obstructive pulmonary disease: reproducibility at 3.0 tesla

RATIONALE AND OBJECTIVES: We assessed subjects with stage II and stage III chronic obstructive pulmonary disease (COPD) and age-matched healthy volunteers at a single center using (3)He magnetic resonance imaging (MRI) at 3.0 T. Measurements of the (3)He apparent diffusion coefficient (ADC) and center coronal slice (3)He ventilation defect volume (VDV) were examined for same-day and 7-day reproducibility as well as subgroup comparisons. MATERIALS AND METHODS: Twenty-four subjects who provided written informed consent (15 males; mean age 67 +/-7 years) with stage II (n = 9), stage III COPD (n = 7), and age-matched healthy volunteers (n = 8) were enrolled based on their age and pulmonary function test results. All subjects underwent plethysmography, spirometry, and MRI at 3.0 T. The time frame between scans was 7 +/- 2 minutes (same-day rescan) and again 7 +/- 2 days later (7-day rescan). (3)He ADC and VDV reproducibility was evaluated using linear regression, intraclass correlation coefficients (ICC) and Lin's concordance correlation coefficients (CCC). RESULTS: ADC reproducibility was high for same-day rescan (r(2) = 0.934) and 7-day rescan (r(2) = 0.960, ICC and CCC of 0.96 and 0.98, respectively). Same-day rescan VDV reproducibility evaluated using the ICC and CCC (0.97 and 0.98, respectively) as well as linear regression (r(2) = 0.941) was also high, but VDV 7-day rescan reproducibility was lower and significantly different (r(2) = 0.576, P < .001, ICC 0.74, CCC 0.75, P < .01). CONCLUSIONS: Hyperpolarized (3)He MRI was well-tolerated in subjects with stage II and stage III COPD. Seven-day repeated scanning was highly reproducible for ADC and moderately reproducible for VDV.     

The added value of the apparent diffusion coefficient calculation to magnetic resonance imaging in the differentiation and grading of malignant brain tumors

OBJECTIVE: ADC calculation can improve the diagnostic efficacy of MR imaging in brain tumor grading and differentiation. METHODS: Apparent diffusion coefficient (ADC) values and ratios of 33 low-grade (23 astrocytomas, 10 oligodendrogliomas) and 40 high-grade (25 metastases and 15 high-grade astrocytomas) malignant tumors were prospectively evaluated. RESULTS: Tumoral ADC values (r=-0.738, P <0.000) and ratios (r=-0.746, P < 0.000) were well correlated with higher degree of malignancy and quite effective in grading of malignant brain tumors (P < 0.000). By using cutoff values of 0.99 for tumoral ADC value and 1.22 for normalized ADC ratio, the sensitivity of MR imaging could be increased from 72.22% to 93.75% and 90.63%, the specificity from 81.08% to 92.68% and 90.24%, PPV from 78.79% to 90.91% and 87.88%, and NPV from 75.00% to 95.00% and 92.50%, respectively. CONCLUSION: ADC calculation was quite effective in grading of malignant brain tumors but not in differentiation of them and added more information to conventional contrast-enhanced MR imaging.     

Apparent diffusion coefficient of human brain tumors at MR imaging

PURPOSE: To determine if apparent diffusion coefficient (ADC) can be used to differentiate brain tumors at magnetic resonance (MR) imaging. MATERIALS AND METHODS: Institutional review board approval or informed patient consent was not required. MR images were reviewed retrospectively in 275 patients with brain tumors: 147 males and 128 females 1-81 years old, treated between September 1997 and July 2003. Regions of interest were placed manually in tumor regions on MR images, and ADC was calculated with a five-point regression method at b values of 0, 250, 500, 750, and 1000 sec/mm2. ADC values were average values in tumor. All brain tumor subgroups were analyzed. Logistic discriminant analysis was performed by using ADC, age, and patient sex as independent variables to discriminate among tumor groups. RESULTS: A significant negative correlation existed between ADC and astrocytic tumors of World Health Organization grades 2-4 (grade 2 vs grades 3 and 4, accuracy of 91.3% [P < .01]; grade 3 vs 4, accuracy of 82.4% [P < .01]). ADC of dysembryoplastic neuroepithelial tumors (DNTs) was higher than that of astrocytic grade 2 tumors (accuracy, 100%) and other glioneuronal tumors. ADC of malignant lymphomas was lower than that of glioblastomas and metastatic tumors (accuracy, 83.6%; P < .01). ADC of primitive neuroectodermal tumors (PNETs) was lower than that of ependymomas (accuracy, 100%). ADC of meningiomas was lower than that of schwannomas (accuracy, 92.4%; P < .01). ADC of craniopharyngiomas was higher than that of pituitary adenomas (accuracy, 85.2%; P < .05). ADC of epidermoid tumors was lower than that of chordomas (accuracy, 100%). In meningiomas, ADC was not indicative of malignancy grade or histologic subtype. CONCLUSION: ADC is useful for differentiation of some human brain tumors, particularly DNT, malignant lymphomas versus glioblastomas and metastatic tumors, and ependymomas versus PNETs.     

癫痫病人MRI海马结构体积测定

目的测量正常成人及癫痫病人海马结构（ＨＦ）体积，探讨其在颞叶癫痫（ＴＬＥ）致痫灶定侧中的价值。材料与方法本组包括５２例正常成人及８９例癫痫病人，把病人分为三组：继发性癫痫４８例、特发颞叶外癫痫１５例、ＴＬＥ２６例，后者有２２例为顽固性癫痫。均作垂直于海马长轴的冠状位自旋回波（ＳＥ）序列Ｔ１加权像、ＴｕｒｂｏＳＥＴ２加权像，测量颞叶、ＨＦ体积和颞角、环池宽度，肉眼观察Ｔ２加权像海马信号强度改变。采用ＨＦ体积绝对值对ＴＬＥ定侧。结果获取了正常成人ＨＦ体积。２２例ＴＬＥＨＦ体积缩小，其中３例为双侧性；６例ＨＦ硬化经手术、病理证实，１例体积正常且致痫灶位于ＨＦ周围者ＨＦ硬化轻，８例其他类型癫痫病人ＨＦ体积略小，ＴＬＥ致痫灶定侧的敏感性为８５％，特异性为８７％。３例ＴＬＥ病人同侧前颞叶萎缩；部分ＴＬＥ病侧颞角、环池宽度增加；萎缩明显的ＨＦＴ２加权像信号弥漫性增高。结论ＨＦ体积缩小、Ｔ２加权像信号弥漫性增高是ＨＦ硬化萎缩的直接征象，与病变严重程度、致痫灶在颞叶的部位有关，前颞叶萎缩和颞角、环池增宽是ＨＦ硬化的辅助征象。ＨＦ萎缩不仅是颞叶癫痫的主要原因，也可能是其他类型癫痫发作的结果     

脑老化进程中大脑灰质的水分子弥散变化

目的:采用液体衰减反转恢复预脉冲DWI技术(FLAIR- DWI)测定不同年龄段脑灰质ADC值来探讨脑老化变化规律.方法:120名来自社区的健康志愿者分为青年组(20～39岁)、中年组(40～59岁)和老年组(60岁及以上),均采用3.0T MRI仪完成FLAIR - DWI扫描,采用感兴趣区法分别测定两侧额叶皮层、扣带回和丘脑的平均ADC值,并分别比较三个年龄组间不同灰质区的ADC值差异及其与年龄变化之间的相关性.结果:额叶皮层的平均ADC值高于丘脑和扣带回(P＜0.001);老年组的丘脑和左侧额叶皮层的ADC值显著高于中年组和青年组,中年组和青年组间没有显著差异,右侧额叶皮层和扣带回ADC值在不同年龄组间没有显著差异;丘脑(左、右两侧的相关系数分别0.577、0.508,P＜0.01)和左侧额叶皮层(r=0.307,P＜0.01)ADC值与年龄增长呈显著正相关,而右侧额叶(r =0.150,P=0.102)和扣带回(r=0.011、0.024,P＞0.05)ADC值与年龄增长之间没有显著相关性.结论:丘脑和左侧额叶皮层ADC值在正常脑老化过程中可能存在年龄相关的ADC值变化.     

单侧颞叶癫痫病人双侧基底节区多体素MRS研究

目的 采用多体素MRS探讨单侧颞叶癫痫（TLE）病人双侧基底节区代谢物改变。方法 选取根据临床发作症状和脑电图综合诊断的左侧TLE病人10例,右侧TLE病人10例,正常志愿者10例纳入研究。所有TLE病人均进行利物浦痫性发作严重程度量表2.0（LSSS 2.0）评估,采用Simens 3.0 T超导MR设备进行多体素1H-MRS数据采集,对称性测量双侧尾状核头、豆状核和丘脑的N-乙酰天门冬氨酸（NAA）、乙酰胆碱（Cho）、肌酸（Cr）含量,计算各兴趣区NAA/Cr和Cho/Cr比值并进行统计学分析,将代谢物比值与LSSS 2.0评分进行Pearson相关分析。结果 左侧TLE组双侧丘脑NAA/Cr比值分别为1.92±0.15（左）和2.02±0.26（右）,右侧TLE组双侧丘脑NAA/Cr比值分别为2.19±0.16（左）和1.79±0.16（右）,均明显低于对照组[2.37±0.14（左）和2.36±0.10（右）,P＜0.05]。右侧TLE组,其致痫灶同侧丘脑的NAA/Cr比值较对侧丘脑要低（P＜0.05）。TLE组致痫灶同侧丘脑NAA/Cr比值与LSSS 2.0评分呈负相关（左侧 r=-0.667;右侧r=-0.643,均P＜0.05）。结论 单侧TLE病人存在双侧丘脑神经元丢失和/或功能障碍,且致痫灶同侧丘脑NAA/Cr比值与LSSS 2.0评分可以一致性反映近期痫性发作严重程度。     

慢性期MCAO患者脑梗死灶扩散变化及海马继发改变与认知功能关系的DTI研究

目的应用扩散张量成像(diffusion tensor imaging,DTI)检测脑梗死慢性期患者脑梗死灶的改变和海马的继发性改变,并分析其与认知功能的关系。资料与方法选取40例病程半年以上的单侧仅大脑中动脉供血区脑梗死(middle cerebral artery occlusion,MCAO)患者及40名与其性别、年龄、文化程度相匹配的正常志愿者于1.5T磁共振扫描仪行全颅15个方向的DTI检查。采用手工法在脑梗死灶及对侧脑组织和双侧海马选取不同兴趣区(region of interest,ROI)进行测量得到各向异性分数(fractional anisotropy,FA)及表观扩散系数(apparent diffusion co-efficient,ADC)值。结果慢性期单侧MCAO患者脑梗死灶及脑梗死同侧海马较对侧相应部位FA值均降低,脑梗死灶FA值降低49.8%,脑梗死同侧海马FA值降低9.29%,ADC值均升高,脑梗死灶ADC值升高132.75%,脑梗死同侧海马ADC值升高4.9%。脑梗死灶ADC值改变率(rADC)较FA值改变率(rFA)明显,而海马rFA较rADC明显,并且脑梗死灶的rFA与认知功能存在相关性,相关系数为-0.41。结论 DTI技术可以用来定量评价慢性期脑梗死患者脑梗死灶及海马的改变,并且慢性期脑梗死患者脑梗死灶rFA与认知功能存在相关性。     

Changes in brain water diffusion during the 1st year of life

PURPOSE: To evaluate the normal water diffusion changes that occur during the 1st year of life. MATERIALS AND METHODS: Diffusion-weighted imaging was performed in 40 subjects (age range, birth to 1 year) in whom both magnetic resonance imaging and neurologic assessment results were normal at the time of imaging and, where available, at follow-up. Apparent diffusion coefficient (ADC) was calculated in four areas of white matter (anterior and posterior subcortical and internal capsule) and four of gray matter (cortex, thalamus, head of the caudate nucleus, and lentiform nucleus). Linear regression was used to examine the effect of age on ADC, and analysis of variance was used to compare ADC within different brain regions. RESULTS: ADC decreased with age in all regions (P <.01). Data best fit with a logarithmic decline (r(2) = 0.20-0.63). ADC was significantly higher in white (113 x 10(-5) mm(2)/sec) than in gray matter (102 x 10(-5) mm(2)/sec; P <.001). Significant differences were seen among three white matter regions (subcortical, 188 x 10(-5) mm(2)/sec at birth; anterior limb of internal capsule, 130 x 10(-5) mm(2)/sec; posterior limb of internal capsule, 109 x 10(-5) mm(2)/sec) and three gray matter regions (cortex, 134 x 10(-5) mm(2)/sec at birth; head of caudate nucleus, 134 x 10(-5) mm(2)/sec at birth; and thalamus and lentiform nucleus, 120 x 10(-5) mm(2)/sec; P <.01). CONCLUSION: Results suggest that in neonates and infants, water diffusion is highly dependent on both subject age and brain location.