Kinetic analysis of 3'-deoxy-3'-18F-fluorothymidine in patients with gliomas.

3'-Deoxy-3'-fluorothymidine (FLT), a thymidine analog, is under investigation for monitoring cellular proliferation in gliomas, a potential measure of disease progression and response to therapy. Uptake may result from retention in the biosynthetic pathway or leakage via the disrupted blood-tumor barrier. Visual analysis or static measures of 18F-FLT uptake are problematic as transport and retention cannot be distinguished. METHODS: Twelve patients with primary brain tumors were imaged for 90 min of dynamic 18F-FLT PET with arterial blood sampling. Total blood activity was corrected for labeled metabolites to provide an FLT input function. A 2-tissue compartment, 4-rate-constant model was used to determine blood-to-tissue transport (K1) and metabolic flux (K(FLT)). Modeling results were compared with MR images of blood-brain barrier (BBB) breakdown revealed by gadolinium (Gd) contrast enhancement. Parametric image maps of K1 and K(FLT) were produced by a mixture analysis approach. RESULTS: Similar to prior work with 11C-thymidine, identifiability analysis showed that K1 (transport) and K(FLT) (flux) could be estimated independently for sufficiently high K1 values. However, estimation of K(FLT) was less robust at low K1 values, particularly those close to normal brain. K1 was higher for MRI contrast-enhancing (CE) tumors (0.053 +/- 0.029 mL/g/min) than noncontrast-enhancing (NCE) tumors (0.005 +/- 0.002 mL/g/min; P < 0.02), and K(FLT) was higher for high-grade tumors (0.018 +/- 0.008 mL/g/min, n = 9) than low-grade tumors (0.003 +/- 0.003 mL/g/min, n = 3; P < 0.01). The flux in NCE tumors was indistinguishable from contralateral normal brain (0.002 +/- 0.001 mL/g/min). For CE tumors, K1 was higher than K(FLT). Parametric images matched region-of-interest estimates of transport and flux. However, no patient has 18F-FLT uptake outside of the volume of increased permeability defined by MRI T1+Gd enhancement. CONCLUSION: Modeling analysis of 18F-FLT PET data yielded robust estimates of K1 and K(FLT) for enhancing tumors with sufficiently high K1 and provides a clearer understanding of the relationship between transport and retention of 18F-FLT in gliomas. In tumors that show breakdown of the BBB, transport dominates 18F-FLT uptake. Transport across the BBB and modest rates of 18F-FLT phosphorylation appear to limit the assessment of cellular proliferation using 18F-FLT to highly proliferative tumors with significant BBB breakdown.     

MR of vasculitis-induced optic neuropathy.

PURPOSETo describe the MR characteristics of optic neuropathy caused by vasculitis.METHODSNine cases of optic neuropathy with diagnosis of vasculitis (six with systemic lupus erythematosis and one each with rheumatoid arthritis, Sjögren disease, and radiation vasculitis) were reviewed retrospectively. Patients were 31 to 62 years old, and all but one were women. All patients had MR imaging through the orbits and anterior visual pathways, five with fat suppression, with and without gadopentetate dimeglumine. Five patients also had MR imaging of the entire brain. The size and enhancement of various segments of the optic nerve and anterior visual pathways were studied.RESULTSMR imaging with contrast material showed enhancement and enlargement of segments of the optic nerves and/or chiasm in six of the nine patients (all but three with systemic lupus erythematosis). Enlargement of a segment of the anterior visual pathway never occurred without enhancement, but enhancement alone did occur in three cases. Of the five patients who had MR imaging of the whole brain, abnormalities were seen in three: periventricular hyperintensity in two and a lacunar infarct in one; none had vessel abnormalities.CONCLUSIONBecause the MR enhancement seen represents disruption of the blood-brain barrier within the optic nerve, MR imaging with gadopentetate dimeglumine and fat suppression should be performed to detect increased permeability of the blood-brain barrier in acute optic neuropathy.     

Recurrent medulloblastoma: frequency of tumor enhancement on Gd-DTPA MR imaging

Thirty-two children with medulloblastoma were evaluated postoperatively with conventional and gadolinium-enhanced MR imaging. Eleven patients had abnormal cranial MR studies; nine of these had recurrent tumor. In six patients recurrent tumor enhanced with Gd, while in the other three patients recurrent tumor did not enhance. The remaining two patients had areas of abnormal Gd enhancement that were caused by radiation-induced breakdown of the blood-brain barrier rather than by recurrent tumor. This study shows that not all recurrent medulloblastoma enhances and that the absence of Gd enhancement does not necessarily indicate the absence of recurrent tumor.     

Recurrent medulloblastoma: frequency of tumor enhancement on Gd-DTPA MR imaging

Thirty-two children with medulloblastoma were evaluated postoperatively with conventional and gadolinium-enhanced MR imaging. Eleven patients had abnormal cranial MR studies; nine of these had recurrent tumor. In six patients recurrent tumor enhanced with Gd, while in the other three patients recurrent tumor did not enhance. The remaining two patients had areas of abnormal Gd enhancement that were caused by radiation-induced breakdown of the blood-brain barrier rather than by recurrent tumor. This study shows that not all recurrent medulloblastoma enhances and that the absence of Gd enhancement does not necessarily indicate the absence of recurrent tumor.     

Cerebral metabolism and permeability of the hemato-encephalic barrier in an experimental model for brain radiotherapy

Whole brain irradiation (WBR) can produce acute and chronic neurological adverse effects, which are usually divided into acute, early delayed and late delayed reactions according to the time of onset. To assess the impact of WBR on brain functional parameters during the early-delayed phase, we employed the [14C]-2-deoxyglucose (2-DG) and the [14C]-alfa-aminoisobutyric (AIB) acid quantitative autoradiographic techniques to study local cerebral glucose utilization and blood-brain barrier permeability, respectively. Sprague-Dowley albino rats were exposed to conventional fractionation (200 Gy/day 5 days a week) for a total dose of 4000 Gy. Experiments were made 3 weeks after completion of the radiation exposure. In comparison with control and sham-irradiated animals, cerebral metabolic activity was diffusely decreased following irradiation. As a rule, brain areas with the highest basal metabolic rates showed the highest percentage drop in glucose utilization. Changes in blood-brain barrier function, as assessed by an increased transcapillary transport of AIB, were also demonstrated in specific brain regions. This study illustrates how moderate doses of WBR induce well-defined changes in brain metabolism and BBB function, which are possibly involved in the pathogenesis of the early-delayed radiation-induced cerebral dysfunction in humans.     

Preoperative grading of glioma malignancy with thallium-201 single-photon emission CT: comparison with conventional CT.

PURPOSETo compare thallium-201 single-photon emission CT with conventional CT in grading the malignancy of gliomas and to determine the reliability of each in tumor assessment.METHODSWe studied 37 patients who had gliomas (31 high grade and 6 low grade) and compared the CT findings with the thallium-201 index, which we defined as tumor uptake relative to the uptake in the contralateral hemisphere.RESULTSAmong the high-grade gliomas, we observed a significant correlation between breakdown volume of the blood-brain barrier and thallium-201 uptake. However, 8 of the high-grade gliomas had low thallium-201 uptake, in the same range as the low-grade gliomas. Of these, 2 were nonenhancing and the other 6 showed ring enhancement on CT scans. Analysis of variance showed no significant difference in thallium-201 indexes between low-grade gliomas and highly malignant (grade II-III) gliomas. Accuracy of thallium-201 imaging was lower (78%) than that of CT (84%) in identifying high-grade gliomas.CONCLUSIONSDamage to the blood-brain barrier is a prerequisite for uptake of thallium-201 in gliomas. Tumors with central necrotic areas and moderate ring enhancement tend to be underestimated when evaluated by means of thallium-201 scintigraphy. The results indicate a need for caution when interpreting findings on images obtained with thallium-201 single-photon emission CT in preoperative evaluation of brain tumors.     

MR and cognitive testing of patients undergoing osmotic blood-brain barrier disruption with intraarterial chemotherapy.

PURPOSETo determine whether osmotic blood-brain barrier disruption is associated with MR abnormalities or cognitive deterioration and, if so, whether the MR findings correlate with cognitive test results.METHODSFifteen brain tumor patients who had a complete tumor response (nine central nervous system lymphoma, three germ cell and two astrocytoma, and one primitive neuroectodermal tumor) treated with blood-brain barrier disruption procedures (318 total procedures) with intraarterial chemotherapy were included. MR images were evaluated for the development of white matter hyperintensity, vascular lesions, or atrophy. Cognitive testing was performed to assess deterioration caused by this therapy.RESULTSIn two patients white matter hyperintensity developed, in two small vascular lesions developed, and in one mild atrophy developed. One infarct was asymptomatic and the second one resulted in mild dysesthesia in one upper extremity. No patient showed diminished cognitive function on the posttherapy evaluation.CONCLUSIONIn patients undergoing blood-brain barrier disruption with intraarterial chemotherapy, new abnormalities on MR imaging may develop. These patients maintain the same level of cognitive and neurologic function and MR findings do not correlate with the results of cognitive testing.     

Pharmacokinetic modeling of Gd-DTPA extravasation in brain tumors

RATIONALE AND OBJECTIVES: The endothelial permeability of brain tumors affecting the blood-brain barrier can be quantified using dynamic contrast enhanced MR imaging. MATERIALS AND METHODS: The dynamics of contrast medium (CM) exchange was investigated in 31 brain tumors (intra- and extra-axial) by fast repeated T1-weighted imaging in order to determine the exchange rates and saturation concentrations. RESULTS: The analysis of CM exchange reveals two different transport processes from the blood into two separate interstitial subcompartments for intra- and extra-axial tumors, a rapid one with a transfer constant of 1/ =7.0 seconds and a slow one with 1/ =133.7 seconds. Highly significant differences exhibit gliomas and meningiomas with respect to the saturation concentrations of fast and slowly enhancing compartments. CONCLUSIONS: The fast component is probably caused by extravasation into viable tissue (enhanced in meningiomas) while the slow one probably reflects increased diffusion distances into poorly perfused tissue such as necrotic areas in glioblastomas.     

Dosimetric evaluation of iodine-125 brachytherapy for brain tumors using MR guidance combined with a three-dimensional non co-planar template

PURPOSETo investigate the consistency between preoperative and postoperative dosimetry when ¹²⁵I brachytherapy for brain tumors is performed with magnetic resonance (MR) guidance and a three-dimensional non co-planar template (3DNPT).METHODS AND MATERIALSThirty patients with brain tumors (metastatic or gliomas) underwent radioactive ¹²⁵I seed implantation. A preoperative treatment plan was determined with MR imaging, and the operation was done under 3DNPT assistance and MR guidance. The dosimetry was verified postoperatively based on postoperative CT–MR fusion images. Postoperative dosimetric parameters and implant quality indices were defined and compared with those in the preoperative treatment plan. Furthermore, a comparison of preoperative and postoperative doses to normal brain tissues and organs at risk was also performed.RESULTSAll mean postoperative dosimetries were calculated. Target coverage parameters D90, D100, %CTV100, %CTV150, and %CTV200 were 143.6 cGy, 76.6 cGy, 88.2%, 63.1%, and 41.4%, respectively. The values of implant quality indices CI, EI, and HI were 0.75, 0.14, and 0.28, respectively. No significant differences between most preoperative and postoperative dosimetric parameters were found (p > 0.05). The differences were also insignificant for organs at risk. Postoperative %CTV150 and %CTV200 were higher than the preoperative, whereas postoperative HI was significantly lower than in the treatment plan.CONCLUSIONSMagnetic resonance guidance combined with 3DNPT allows accurate positioning and direction in ¹²⁵I brachytherapy for brain tumors. However, seed distribution and dose homogeneity require further improvement.     

In vivo three-dimensional MR microscopy of mice with chronic relapsing experimental autoimmune encephalomyelitis after treatment with insulin-like growth factor-I.

PURPOSEThe purpose of this study was to determine the ability of three-dimensional in vivo MR microscopy to depict the treatment effects of insulin-like growth factor-I (IGF-I) in SJL mice with chronic relapsing experimental autoimmune encephalomyelitis (crEAE).METHODSThe experiments were performed at 4.7-T on 10 crEAE mice and on one set of control animals. Five crEAE mice were treated with IGF-I and five were treated with a placebo.RESULTSIn the crEAE mice treated with the placebo, in vivo MR microscopy showed areas of abnormal signal throughout the cerebrum, brain stem, and cerebellum. These findings were not present in either the IGF-I-treated mice or the normal control animals. The diffuse alterations in signal intensity in the placebo-treated crEAE mice were not identified on histologic sections of the same areas.CONCLUSIONDifferences between the IGF-I- and placebo-treated groups may reflect changes in stabilization or permeability of cell membranes and/or of the blood-brain barrier, although other alternative contrast mechanisms could be playing a role. In vivo MR microscopy depicted changes resulting from treatment of crEAE with IGF-I.     

Gadolinium enhancement in acute and chronic-progressive experimental allergic encephalomyelitis in the guinea pig

Magnetic resonance imaging detects blood-brain barrier disruption after gadolinium-DTPA enhancement of central nervous system lesions of multiple sclerosis. Experimental allergic encephalomyelitis has many clinical and pathological features in common with multiple sclerosis including alterations in the integrity of the blood-brain barrier. We have compared T₂-weighted cranial MR images with Gd-DTPA dimeglumine-enhanced T₁-weighted images of myelin bask protein-induced acute (Days 8–42 postimmunlzation) and central nervous system-induced chronic-progressive (Days 70–95 post immunization) forms of experimental allergic encephalomyelitis in the guinea pig. Although animals from both groups had abnormal T₂-weighted images, only the myelin bask protein-acute-EAE animals (Days 14–24 postimmunlzation) showed enhancement on postcontrast MR studies. The different responses of the acute and chronic diseases may result from different immunogens, severity of disease, or different permeability of the blood-brain barrier. Therefore, gadolinium-DTPA-enhanced, T₁-weighted MR images distinguish acutely active and chronic inflammatory lesions in experimental allergic encephalomyelitis.     

MgSO4对大鼠急性放射性脑损伤后NSE和S-100蛋白表达的影响

目的探讨MgSO4对电离辐射诱发的脑组织损伤的保护作用。方法将成熟的SD大鼠36只随机分为空白对照组、实验对照组和MgSO4实验用药组，用6MeV电子线对实验大鼠行20Gv全脑单次垂直照射，吸收剂量率为200cGy／min；实验用药组大鼠于照射前1d、照射后即刻、照后连续3d分别给予10％的MgSO4腹腔注射，分别于照射后1、7、14和30d处死大鼠，取其脑组织，用免疫组织化学法测定神经元特异性稀醇化酶（NSE）、S-100蛋白的相对含量，并与对照组进行比较。结果在上述时间点，脑内海马区S-100和NSE表达有时间规律，照射后1周S-100蛋白的表达和照射后24hNSE的表达组间存在一定差别。与空白对照组相比，实验对照组大鼠脑组织中NSE表达显著下降（P〈0．05），S-100表达显著升高（P〈0．05）；与实验对照组相比，在照射后7d，MgSO4可明显抑制S-100的表达（P〈0．05），诱导NSE的表达（P〈0．05）。结论 脑组织中S-100和NSE表达水平的变化是辐射诱导的急性脑损伤的敏感指标，MgSO4可降低S-100的表达水平并升高NSE在神经元中的含量，早期使用对急性放射性脑损伤有保护作用。     

Brain tumour imaging with carbon-11 choline: comparison with FDG PET and gadolinium-enhanced MR imaging

The purpose of this study was to assess the clinical potential of methyl-¹¹C-choline (¹¹C-choline) in the diagnosis of brain tumours. To this end, the results of ¹¹C-choline positron emission tomography (PET) in 22 patients suspected of having brain tumours were compared with the findings of contrast-enhanced magnetic resonance (MR) imaging and fluorine-18 fluorodeoxyglucose PET. A histopathological diagnosis was made for each patient during open surgery. The standardised uptake values of brain tumours and the tumour-to-white matter count (T/W) ratios were determined. The degree of ¹¹C-choline accumulation noted in PET images was compared with the gadolinium-enhanced areas of MR images. The mean T/W ratio of ¹¹C-choline in high-grade gliomas was found to be higher than that in low-grade gliomas. This difference was statistically significant (mean-SD: 8.7Lj.2, n=9 versus 1.5ǂ.7, n=5, P<0.03) when data pertaining to the prominent uptake of ¹¹C-choline in a patient with a pilocytic astrocytoma were excluded. ¹¹C-choline PET failed to detect non-neoplastic lesions in two patients. Areas of ¹¹C-choline accumulation in PET scans were larger than areas enhanced on MR images in five cases involving high-grade gliomas. ¹¹C-choline PET differentiated between low-grade gliomas and high-grade gliomas, but did not differentiate between low-grade gliomas and non-neoplastic lesions. The combination of ¹¹C-choline PET and MR imaging may provide investigators with an accurate means by which to identify high-grade gliomas.     

大鼠全脑照射后早期血清S-100B变化特征

目的 观察大鼠全脑不同剂量照射后1月内不同时间点血清中S-100B的变化,以探讨S-100B在早期放射性脑损伤中的变化特征。方法 对大鼠予4 MeV电子线分别单次全脑照射2、10和30 Gy制备大鼠早期放射性脑损伤模型。采用酶联免疫吸附试验(ELISA)检测照射后1 h、6 h、12 h、24 h、3 d、1周、1个月血清中S-100B的浓度。结果 大鼠血清S-100B浓度在照射后6h升高最明显,照射后12h浓度下降,照后24h再升高(除外2 Gy组为在照射后3d再升高), 随后下降直到最后观察时间点。结论 大鼠全脑照射后血清S-100B水平发生了变化,不同剂量组血清S-100B浓度有显著性差异,剂量越高,浓度越高。结果提示S-100B可能会成为检测早期放射性脑损伤的重要血清指标。     

大鼠早期放射性脑损伤后少突胶质细胞内Tau蛋白表达的变化特征

目的 观察大鼠全脑照射条件下皮质下白质区少突胶质细胞内Tau蛋白在不同剂量和不同时间点的表达情况。方法 分别以单次2、10和30 Gy照射大鼠全脑后24 h、1周和1个月时用免疫组织化学法观察少突胶质细胞内Tau-1和Tau-5的表达,并分析剂量、照射后时间的影响。结果 照射后24 h Tau-1的表达迅速升高达到峰值,1周后开始下降,其表达与照射剂量呈正相关,1个月后恢复照射前水平。Tau-5的表达各组在不同时间点表达差异无统计学意义(P>0.05)。结论 在大脑受电离辐射后早期,少突胶质细胞内Tau蛋白出现迅速的一过性去磷酸化,并且呈剂量依赖性。这提示Tau蛋白在早期放射性脑损伤的发生、发展过程中可能起到了一定的作用。     

Estimating Local Cellular Density in Glioma Using MR Imaging Data

BACKGROUND AND PURPOSE:Increased cellular density is a hallmark of gliomas, both in the bulk of the tumor and in areas of tumor infiltration into surrounding brain. Altered cellular density causes altered imaging findings, but the degree to which cellular density can be quantitatively estimated from imaging is unknown. The purpose of this study was to discover the best MR imaging and processing techniques to make quantitative and spatially specific estimates of cellular density.MATERIALS AND METHODS:We collected stereotactic biopsies in a prospective imaging clinical trial targeting untreated patients with gliomas at our institution undergoing their first resection. The data included preoperative MR imaging with conventional anatomic, diffusion, perfusion, and permeability sequences and quantitative histopathology on biopsy samples. We then used multiple machine learning methodologies to estimate cellular density using local intensity information from the MR images and quantitative cellular density measurements at the biopsy coordinates as the criterion standard.RESULTS:The random forest methodology estimated cellular density with R² = 0.59 between predicted and observed values using 4 input imaging sequences chosen from our full set of imaging data (T2, fractional anisotropy, CBF, and area under the curve from permeability imaging). Limiting input to conventional MR images (T1 pre- and postcontrast, T2, and FLAIR) yielded slightly degraded performance (R² = 0.52). Outputs were also reported as graphic maps.CONCLUSIONS:Cellular density can be estimated with moderate-to-strong correlations using MR imaging inputs. The random forest machine learning model provided the best estimates. These spatially specific estimates of cellular density will likely be useful in guiding both diagnosis and treatment.

Increased cellular density (CD) is a hallmark of cancer and a key feature in histologic glioma analysis.¹ Mapping cellular density throughout a tumor would be a valuable tool to probe how tumors infiltrate and analyze the transition between diseased and healthy brain. However, measuring CD requires tissue, which entails additional risks and is expensive to obtain. There is no currently accepted clinical algorithm to translate imaging data into quantitative assessments of CD.There is great need for a method to estimate CD noninvasively in human patients with gliomas. In this article, we describe the development of such a method using MR imaging data inputs by correlating with multiple biopsy specimens acquired during a prospective human clinical trial. We obtained comprehensive MR imaging, including conventional, diffusion, perfusion, and permeability imaging sequences. We used machine learning approaches to correlate imaging findings with CD measurements from pathology, devised an algorithm to estimate CD from MR imaging inputs, and generated CD maps for the visual display of the predictions. We identified the most informative imaging data subset. This work has multiple applications in the diagnosis and treatment of patients with gliomas: For example, the method can be used to guide biopsy, resection, and surgery and delineate tumor borderzones both pre- and postoperatively.²     

Noninvasive profiling of exercise-induced hypoxemia in competitive cyclists

The purpose of this case study was to profile maximal exercise and the incidence of exercise-induced arterial hypoxemia (EIAH) at three different altitudes within a group of competitive cyclists residing and training at 1,500 m. Ten male cyclists (category I or II professional road cyclists: ages, 27.7 +/- 6.1; weight, 69.9 +/- 6.9 kg) participated in three randomly assigned VO2max tests at sea level (SL), 1,500 m and 3000 m. Arterial saturation (pulse oximetry), ventilation, and power output (PO) were recorded continuously throughout the test. The SaO2 percentages at VO2max were significantly higher at SL when compared with 1500 m (p < 0.001); however, no difference was observed between VO2max values at either altitude (SL: 72.3 +/- 2.5 mL.kg-1.min-1, 1,500 m: 70.6 +/- 2.3 mL.kg-1.min-1), only when compared with 3,000 m: 63.9 +/- 2.1 mL.kg-1.min-1, p < 0.021. Percent SaO2 did correspond with maximal PO, and there was an overall main effect observed between POs as they continually declined from SL to 3,000 m (SL: 403.3 +/- 10.6 W; 1,500 m: 376.1 +/- 9.8 W; 3,000 m: 353.9 +/- 7.8 W; p < 0.0001). The results of this case study revealed that training and residing at 1,500 m did not reduce the incidence of EIAH during maximal exercise at 1,500 m for this selected group of cyclists.     

MR of toxic effects of accelerated fractionation radiation therapy and carboplatin chemotherapy for malignant gliomas.

PURPOSETo present MR findings of parenchymal brain injury after accelerated fractionation radiation therapy combined with carboplatin chemotherapy in the treatment of malignant brain gliomas.METHODSEighty-one evaluable subjects in an ongoing treatment protocol for malignant gliomas form the patient base for this report. After surgical resection of tumors, patients underwent a course of accelerated fractionation radiation therapy to a total dose of 60 Gy. Carboplatin was infused intravenously before each radiation treatment. Precontrast and postcontrast MR scans were obtained before treatment and at 4-week intervals afterward and were analyzed retrospectively.RESULTSPosttreatment MR imaging in 20 of the 81 patients showed development of unusual parenchymal lesions or enlarging masses needing debulking, and these patients underwent second operations. Two groups emerged: those with tumor and necrotic brain (n = 11) and those with necrosis and reactive gliosis but no definitive tumor (n = 9). Enhancing lesions in the tumor-negative group appeared later than those in the tumor-positive group, were often multiple, and were usually located several centimeters away from the tumor resection site or even contralaterally. Common locations were the corpus callosum and corticomedullary junctions. Lesions in the tumor-positive group were more often solitary and located immediately adjacent to the surgical site. Positive and negative results of positron emission tomography with fludeoxyglucose F 18 were obtained in both groups. The incidence of brain necrosis without associated tumor was 11%.CONCLUSIONSA pattern of unusual enhancing parenchymal brain lesions was seen on MR imaging after accelerated fractionation radiation therapy and concomitant carboplatin chemotherapy. The abnormalities seem more extensive than focal necrotic lesions on enhanced CT or MR imaging after conventional radiation therapy, and they may mimic recurrent tumor.     

Late radiation injury to the temporal lobes: morphologic evaluation at MR imaging

PURPOSE: To study the morphologic characteristics of late radiation injury to the temporal lobes of the brain on magnetic resonance (MR) images. MATERIALS AND METHODS: This was a prospective study involving 34 patients (age range, 37-72 years) with known radiation injury to the temporal lobes from radiation therapy administered 2-10 years previously for nasopharyngeal carcinoma MR imaging was performed with T2-weighted gradient- and spin-echo, gradient-recalled echo, T1-weighted spin-echo, fluid-attenuated inversion-recovery, and T1-weighted postcontrast spin-echo sequences. RESULTS: Radiation injury was present in 57 of the 68 temporal lobes. The white matter lesions in radiation-induced injury were predominantly hyperintense on T2-weighted images, but in 37 (65%) of the 57 lobes, foci with heterogeneous signal intensity consistent with necrosis were detected. In the 57 involved lobes, gray matter lesions were detected in 50 (88%); blood-brain barrier disruption based on parenchymal contrast enhancement, in 51 (89%); and hemosiderin deposits, in 30 (53%). There was a significant correlation between white matter necrosis, gray matter lesions, and blood-brain barrier disruption, all of which were located mainly in the inferior temporal lobes that received the highest radiation dose. CONCLUSION: The lesion components of radiation-induced injury to the temporal lobes at MR imaging were more varied than have been previously described. In addition to the classic white matter lesions, gray matter lesions, blood-brain barrier disruption, and hemosiderin deposition also were frequently seen.     

老年人血脑屏障通透性、缺血性脑白质高信号严重程度与认知功能的关系

 目的 探讨老年血脑屏障通透性、缺血性脑白质高信号(white matter hyperintensity,WMH)严重程度与认知功能的关系。方法 选择120例老年缺血性WMH患者为观察组,120例老年健康体检者为对照组。行MRI检查,比较两组血脑屏障通透性指标。根据Fazekas评分法将老年缺血性WMH患者分为三组:轻度(Fazekas评分为0~2分)、中度(Fazekas评分为3~4分)、重度(Fazekas评分为5~6分),比较不同WMH严重程度患者的血脑屏障通透性指标和认知功能水平,分析老年缺血性WMH患者血脑屏障通透性与WMH严重程度、认知功能的相关性。结果 观察组脑白质正常区的渗透转运速率、渗透曲线下面积均显著高于对照组(P<0.05)。轻、中、重度WMH组的渗透转运速率、渗透曲线下面积比较,差异均有统计学意义(P<0.05),从高至低依次为重度WMH组、中度WMH组、轻度WMH组。轻、中、重度WMH组的MMSE评分、MoCA评分比较,差异均有统计学意义(P<0.05),从高至低依次为轻度WMH组、中度WMH组、重度WMH组。老年缺血性WMH患者渗透转运速率、渗透曲线下面积与其WMH严重程度均呈正相关(P<0.05),与其MMSE评分、MoCA评分均呈负相关(P<0.05)。结论 老年缺血性WMH患者血脑屏障通透性随着WMH严重程度加重而增强,而血脑屏障通透性越强,认知功能损伤越严重。