The correlation of fractional anisotropy parameters with Ki-67 index, and the clinical implication in grading of non-enhancing gliomas and neuronal-glial tumors.

PURPOSE: To investigate the correlation between the FA parameters and Ki-67 labeling index, and their diagnostic performance in grading supratentorial non-enhancing gliomas and neuronal-glial tumors (GNGT). METHODS: This institutional review board-approved, Health Insurance Portability and Accountability (HIPAA) compliant retrospective study enrolled 35 patients, including 19 with low grade GNGT and 16 with high grade GNGT. The mean FA, maximal FA and mean maximal FA values derived from diffusion tensor imaging were measured. The correlation between the FA parameters and the Ki-67 labeling index was assessed by Spearman rank test. The receiver operating characteristic curve analysis and multivariate logistic regression analysis were performed to detect the optimal imaging parameters in grading GNGT. RESULTS: The three FA parameters of low grade GNGT were significantly lower than the high grade GNGT (p < 0.001). The mean FA, maximal FA and mean maximal FA had significant positive correlation with Ki-67 labeling index (p = 0.001, p < 0.001, p < 0.001 respectively). The maximal FA showed a higher sensitivity and specificity in grading of non-enhancing GNGT with specificity of 78.9%, sensitivity of 100.0%, respectively. CONCLUSIONS: The FA parameters correlated with Ki-67 labeling index, and were useful surrogates in preoperative grading supratentorial non-enhancing GNGT.

The preliminary radiogenomics association between MR perfusion imaging parameters and genomic biomarkers, and their predictive performance of overall survival in patients with glioblastoma.

The radiogenomics association of neovascularization is important for overall survival (OS) in glioblastoma patients and remains unclear. The purpose of this study is to assess the association between MR perfusion imaging derived parameters and genomic biomarkers of glioblastoma, and to evaluate their prognostic value. This retrospective study enrolled 41 patients with newly diagnosed glioblastoma. The mean and maximal relative cerebral blood volume (rCBV) ratio (rCBVmean and rCBVmax), derived from MR perfusion weighted imaging, of the enhancing tumor, as well as maximal rCBV ratio of peri-enhancing tumor area (rCBVperi-tumor) were measured. The ki-67 labeling index, mammalian target of rapamycin (mTOR) activation, epidermal growth factor receptor (EGFR) amplification, isocitrate dehydrogenase (IDH) mutation and TP53 were assessed. There was a significant correlation between rCBVmax and mTOR based on Pearson's correlations with Benjamini-Hochberg adjustment for controlling false discovery rate, p = 0.047. The rCBVperi-tumor showed significant correlation with mTOR (p = 0.0183) after adjustment of gender and EGFR status. The mean rCBVperi-tumor value of the patients with OS shorter than 14 months was significantly higher than patients with OS longer than 14 months, p = 0.002. The rCBVperi-tumor and age were the two strongest predictors of OS (hazard ratio = 1.29 and 1.063 respectively) by Cox regression analysis. This study showed that hemodynamic abnormalities of glioblastoma were associated with genomics activation status of mTOR-EGFR pathway, however, the radiogenomics associations are different in enhancing and peri-enhancing area of glioblastoma. The rCBVperi-tumor has better prognostic value than genomic biomarkers alone.

Improved spatial regression analysis of diffusion tensor imaging for lesion detection during longitudinal progression of multiple sclerosis in individual subjects.

Subject-specific longitudinal DTI study is vital for investigation of pathological changes of lesions and disease evolution. Spatial Regression Analysis of Diffusion tensor imaging (SPREAD) is a non-parametric permutation-based statistical framework that combines spatial regression and resampling techniques to achieve effective detection of localized longitudinal diffusion changes within the whole brain at individual level without a priori hypotheses. However, boundary blurring and dislocation limit its sensitivity, especially towards detecting lesions of irregular shapes. In the present study, we propose an improved SPREAD (dubbed improved SPREAD, or iSPREAD) method by incorporating a three-dimensional (3D) nonlinear anisotropic diffusion filtering method, which provides edge-preserving image smoothing through a nonlinear scale space approach. The statistical inference based on iSPREAD was evaluated and compared with the original SPREAD method using both simulated and in vivo human brain data. Results demonstrated that the sensitivity and accuracy of the SPREAD method has been improved substantially by adapting nonlinear anisotropic filtering. iSPREAD identifies subject-specific longitudinal changes in the brain with improved sensitivity, accuracy, and enhanced statistical power, especially when the spatial correlation is heterogeneous among neighboring image pixels in DTI.

Spatial regression analysis of serial DTI for subject-specific longitudinal changes of neurodegenerative disease.

Quantitative measurement of localized longitudinal changes in brain abnormalities at an individual level may offer critical information for disease diagnosis and treatment. The voxel-wise permutation-based method SPREAD/iSPREAD, which combines resampling and spatial regression of neighboring voxels, provides an effective and robust method for detecting subject-specific longitudinal changes within the whole brain, especially for longitudinal studies with a limited number of scans. As an extension of SPREAD/iSPREAD, we present a general method that facilitates analysis of serial Diffusion Tensor Imaging (DTI) measurements (with more than two time points) for testing localized changes in longitudinal studies. Two types of voxel-level test statistics (model-free test statistics, which measure intra-subject variability across time, and test statistics based on general linear model that incorporate specific lesion evolution models) were estimated and tested against the null hypothesis among groups of DTI data across time. The implementation and utility of the proposed statistical method were demonstrated by both Monte Carlo simulations and applications on clinical DTI data from human brain in vivo. By a design of test statistics based on the disease progression model, it was possible to apportion the true significant voxels attributed to the disease progression and those caused by underlying anatomical differences that cannot be explained by the model, which led to improvement in false positive (FP) control in the results. Extension of the proposed method to include other diseases or drug effect models, as well as the feasibility of global statistics, was discussed. The proposed statistical method can be extended to a broad spectrum of longitudinal studies with carefully designed test statistics, which helps to detect localized changes at the individual level.

Dysregulation of the IL-23/IL-17 axis and myeloid factors in secondary progressive MS.

OBJECTIVE: In the current exploratory study, we longitudinally measured immune parameters in the blood of individuals with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS), and investigated their relationship to disease duration and clinical and radiologic measures of CNS injury. METHODS: Peripheral blood mononuclear cells (PBMCs) and plasma were obtained from subjects with RRMS, SPMS, and from healthy controls on a monthly basis over the course of 1 year. MRI and Expanded Disability Status Scale evaluations were performed serially. PBMCs were analyzed by enzyme-linked immunosorbent spot assay to enumerate myelin basic protein-specific interleukin (IL)-17- and interferon (IFN)-γ-producing cells. Plasma concentrations of proinflammatory factors were measured using customized Luminex panels. RESULTS: Frequencies of myelin basic protein-specific IL-17- and IFN-γ-producing PBMCs were higher in individuals with RRMS and SPMS compared to healthy controls. Patients with SPMS expressed elevated levels of IL-17-inducible chemokines that activate and recruit myeloid cells. In the cohort of patients with SPMS without inflammatory activity, upregulation of myeloid-related factors correlated directly with MRI T2 lesion burden and inversely with brain parenchymal tissue volume. CONCLUSIONS: The results of this exploratory study raise the possibility that Th17 responses and IL-17-inducible myeloid factors are elevated during SPMS compared with RRMS, and correlate with lesion burden. Our data endorse further investigation of Th17- and myeloid-related factors as candidate therapeutic targets in SPMS.

Imaging and diseases of the ascending and descending pathways.

The corticospinal tract and other ascending and descending fibers are important in executing cerebral function. Conventional magnetic resonance and advanced neuroimaging findings of diseases involved in ascending and descending pathways are reviewed, including amyotrophic lateral sclerosis, secondary degeneration diseases, and intracranial tumors.

Diffusion-weighted imaging of skull lesions.

Diffusion-weighted imaging can increase the conspicuity of skull lesions and be applied toward noninvasive differentiation of malignant from benign lesions. Malignant skull lesions generally display lower diffusivity than benign lesions, although there are exceptions, and clinical parameters and conventional imaging modalities should also be considered in the evaluation of skull lesions. Nevertheless, in some instances diffusion-weighted imaging (DWI) can be used for problem solving when conventional imaging features are indeterminate, such as with skull base involvement by nasopharyngeal carcinoma versus osteomyelitis. In addition, DWI may be useful for monitoring treatment effects. The use of readout segmented technique, parallel imaging, multishot acquisition, turbo spin-echo DWI, diffusion tensor imaging, and higher field strengths can improve image quality. The feasibility of implementing DWI for characterizing skull lesions, the DWI findings of benign and malignant skull lesions, and technical considerations are discussed in this article.

Different stages of white matter changes in the original HDLS family revealed by advanced MRI techniques.

BACKGROUND: The temporal evolution of white matter (WM) changes on MR examinations in hereditary diffuse leukoencephalopathy with spheroids (HDLS) is largely unknown. Our purpose was to investigate the evolution of these WM changes with diffusion weighted/tensor imaging (DWI/DTI) and MR Spectroscopy (MRS). METHODS: A newly diagnosed patient with HDLS from the original Swedish family was followed prospectively with 5 MRI as well as DWI/DTI and MRS examinations during 16 months. RESULTS: The DTI eigenvalues demonstrated changes that suggested early myelin and axonal disturbances in the normal appearing WM (NAWM). DWI/DTI showed a rim of decreased diffusion progressively expanding through the WM from the initial frontal periventricular zones, and indicated complete destruction of axons and myelin in the area behind the front. MRS findings were suggestive of axonal destruction in the NAWM. CONCLUSION: We describe HDLS changes in three temporal stages of development corresponding to lesions outside, in the vicinity of, and behind a characteristic rim centrifugally progressing from the ventricular horns. The axonal disturbances indicated by MRS changes in the NAWM support a primary axonal degeneration, as proposed in the original HDLS report, rather than axonal degeneration secondary to demyelination. These findings could help in differential diagnosis of HDLS.

Correlation between progression free survival and dynamic susceptibility contrast MRI perfusion in WHO grade III glioma subtypes.

The purpose of this study was to determine whether dynamic susceptibility contrast MR perfusion relative cerebral blood volume (rCBV) correlates with prognosis of World Health Organization (WHO) grade III glial tumors and their different subtypes. Retrospective evaluation of pre-treatment tumor rCBV derived from dynamic susceptibility contrast MR perfusion was performed in 34 patients with histopathologically diagnosed WHO grade III glial tumors (anaplastic astrocytomas (n = 20), oligodendrogliomas (n = 4), and oligoastrocytomas (n = 10)). Progression free survival was correlated with rCBV using Spearman rank analysis. ROC curve analysis was performed to determine the operating point for rCBV in patients with anaplastic astrocytomas dichotomized at the median progression free survival time. For all grade III tumors (n = 34) the mean rCBV was 2.51 with a progression free survival of 705.5 days. The mean rCBV of anaplastic astrocytomas was 2.47 with progression free survival 495.2 days. In contrast, the mean rCBV for oligodendroglial tumors was 2.56 with a progression free survival of 1005.6 days. Although there was no significant correlation between rCBV and progression free survival among all types of grade III gliomas (P = 0.12), among anaplastic astrocytomas there was a significant correlation between pretreatment rCBV and progression free survival with correlation coefficient of -0.51 (P = 0.02). The operating point for rCBV in patients with anaplastic astrocytomas dichotomized at the median progression free survival time (446.5 days) was 2.86 with 78 % accuracy and there was a significant difference between the survival of patients with anaplastic astrocytomas in the dichotomized groups (P = 0.0009). Pre-treatment rCBV may serve as a prognostic imaging biomarker for anaplastic astrocytomas, but not grade III oligodendroglioma tumors.

Advanced MR diffusion tensor imaging and perfusion weighted imaging of intramedullary tumors and tumor like lesions in the cervicomedullary junction region and the cervical spinal cord.

Differential diagnosis between intramedullary tumors and tumor-like lesions (TLL) in the cervicomedullary junction region and cervical spinal cord is important, sometimes clinical dilemma on conventional MR imaging and empirical treatment. We evaluated advanced MR diffusion tensor imaging (DTI) and perfusion weighted imaging (PWI) in 25 patients, including 12 with intramedullary tumors and 13 with TLL in the cervicomedullary junction region and cervical spinal cord. We found that mean fractional anisotropy value of tumors was significantly lower than the value found in TLL, and the mean trace apparent diffusion coefficient and peak height values of tumors were significantly higher (P < 0.05). The receiver operating characteristic curve analysis showed that peak height was better than any of the other imaging parameters, with a sensitivity of 90.9% and specificity of 80% using a cutoff value of 4.523 to differentiate between tumors and TLL. In conclusion, the MR DTI and PWI could be useful in differentiating between intramedullary tumors and TLL in the cervicomedullary junction region and cervical spinal cord.

SPatial REgression Analysis of Diffusion tensor imaging (SPREAD) for longitudinal progression of neurodegenerative disease in individual subjects.

OBJECTIVES: To develop a novel statistical method for analysis of longitudinal DTI data in individual subjects. MATERIALS AND METHODS: The proposed SPatial REgression Analysis of Diffusion tensor imaging (SPREAD) method incorporates a spatial regression fitting of DTI data among neighboring voxels and a resampling method among data at different times. Both numerical simulations and real DTI data from healthy volunteers and multiple sclerosis (MS) patients were used in the study to evaluate this method. RESULTS: Statistical inference based on SPREAD was shown to perform well through both group comparisons among simulated DTI data of individuals (especially when the group size is smaller than 5) and longitudinal comparisons of human DTI data within the same individual. CONCLUSIONS: When pathological changes of neurodegenerative diseases are heterogeneous in a population, SPREAD provides a unique way to assess abnormality during disease progression at the individual level. Consequently, it has the potential to shed light on how the brain has changed as a result of disease or injury.

Patterns of white matter injury in HIV infection after partial immune reconstitution: a DTI tract-based spatial statistics study.

HIV-infected individuals with severe immune suppression are more likely to develop HIV-associated neurocognitive disorders than those with preserved immune function. While partial immune reconstitution occurs in those with severe immune suppression after starting combined antiretroviral therapy, it is not established whether improvement in immune function reverses or prevents injury to the central nervous system (CNS). To address this question, 50 participants (nadir CD4 counts ≤ 200 cells/mm(3), on a stable antiretroviral regimen for at least 12 consecutive weeks prior to study) and 13 HIV negative participants underwent a comprehensive neurological evaluation followed by diffusion tensor imaging (DTI). Eighty-four percent of the 50 HIV participants were neurologically asymptomatic (HIVNA) and 16 % had mild cognitive impairment (HIVCI). Tract-based spatial statistics (TBSS) on DTI data revealed that mean diffusivity (MD) increased significantly in the posterior aspect of both hemispheres in HIVNA compared to controls. In HIVCI, compared to controls and HIVNA, increased MD extended to prefrontal areas. Fractional anisotropy decreased only in HIVCI, compared to either controls or HIVNA. Furthermore, DTI showed significant correlations to duration of HIV infection and significant associations with multiple cognitive domains. This study highlights that in partial immune reconstitution, injury to the CNS is present even in those that are neurologically asymptomatic and there are discrete spatial patterns of white matter injury in HIVNA subjects compared to HIVCI subjects. Our results also show that quantitative analysis of DTI using TBSS is a sensitive approach to evaluate HIV-associated white matter disease and thus valuable in monitoring central nervous system injury.

Lesions masquerading as acute stroke.

Rapid and accurate recognition of lesions masquerading as acute stroke is important. Any incorrect or delayed diagnosis of stroke mimics will not only increase the risk of being exposed to unnecessary and possibly dangerous interventional therapies, but will also delay proper treatment. In this article, written from a neuroradiologist's perspective, we classified these lesions masquerading as acute stroke into three groups: lesions that may have "normal imaging," lesions that are "symptom mimics" but on imaging clearly not a stroke, and lesions that are "symptom and imaging mimics" with imaging findings similar to stroke. We focused the review on neuroimaging findings of the latter two groups ending with a suggestion for a diagnostic approach in the form of an algorithm.

Hippocampal volumes in patients exposed to low-dose radiation to the basal brain. A case-control study in long-term survivors from cancer in the head and neck region.

BACKGROUND: An earlier study from our group of long time survivors of head and neck cancer who had received a low radiation dose to the hypothalamic-pituitary region, with no signs of recurrence or pituitary dysfunction, had their quality of life (QoL) compromised as compared with matched healthy controls. Hippocampal changes have been shown to accompany several psychiatric conditions and the aim of the present study was to test whether the patients' lowered QoL was coupled to a reduction in hippocampal volume. METHODS: Patients (11 men and 4 women, age 31-65) treated for head and neck cancer 4-10 years earlier and with no sign of recurrence or pituitary dysfunction, and 15 matched controls were included. The estimated radiation doses to the basal brain including the hippocampus (1.5 - 9.3 Gy) had been calculated in the earlier study. The hippocampal volumetry was done on coronal sections from a 1.5 T MRI scanner. Measurements were done by two independent raters, blinded to patients and controls, using a custom method for computer assisted manual segmentation. The volumes were normalized for intracranial volume which was also measured manually. The paired t test and Wilcoxon's signed rank test were used for the main statistical analysis. RESULTS: There was no significant difference with respect to left, right or total hippocampal volume between patients and controls. All mean differences were close to zero, and the two-tailed 95% confidence interval for the difference in total, normalized volume does not include a larger than 8% deficit in the patients. CONCLUSION: The study gives solid evidence against the hypothesis that the patients' lowered quality of life was due to a major reduction of hippocampal volume.

31P MR spectroscopy to evaluate the efficacy of hepatic artery embolization in the treatment of neuroendocrine liver metastases.

BACKGROUND: It is common to treat patients with metastatic disease from gastrointestinal neuroendocrine (NE) tumors with surgical reduction to prolong survival. This can be combined with hepatic arterial embolization (HAE) and medical treatment to reduce hormonal symptoms. Today there are no rapid and reliable methods to evaluate the efficacy of HAE in the treatment of neuroendocrine liver metastasis. PURPOSE: To investigate metabolic changes in hepatic metastases of NE tumors following HAE, and to establish if there are any early spectral patterns that might indicate therapeutic efficacy based on in vivo (31)P MRS data. MATERIAL AND METHODS: Volume selective (31)P MRS was used to study 11 patients with disseminated NE tumors with regional lymph nodes and bilobar liver metastases. Measurements were performed before and 1 and 3 days after HAE. RESULTS: Non-responders had significantly higher PME/Pi and αNTP/ΣNTP ratios than the responders before HAE (P < 0.05). Three days after HAE, non-responders still had significantly higher αNTP/ΣNTP than the responders did (P < 0.05). We also observed trends for increased PME ratios 3 days after HAE, decreased ATP-levels, and liberated Pi in responders. CONCLUSION: This (31)P-MRS study showed significant differences in PME/Pi and αNTP/ΣP ratios between responders and non-responders on the day before HAE, which is an interesting finding that may reflect intrinsic properties of the tumor tissue. We also observed trends for cell membrane renewal and increased energy consumption in responders after HAE. These results demonstrate potentials for (31)P-MRS to predict individual responsiveness prior to HAE.

Diffusion-weighted imaging for differentiating benign from malignant skull lesions and correlation with cell density.

OBJECTIVE: The objective of our study was to determine the utility of diffusion-weighted imaging (DWI) and cell density for differentiating benign from malignant skull lesions. MATERIALS AND METHODS: A retrospective review was performed. Minimum apparent diffusion coefficient (ADC) values were measured and normalized to white matter, which we refer to as "normalized ADC," in 24 skull lesions (12 malignant and 12 benign) in 18 patients. In addition, cell densities were measured in 15 cases and correlated with ADC values. RESULTS: The average minimum ADC in malignant tumors was 0.70 × 10(-3) mm(2)/s versus 1.11 × 10(-3) mm(2)/s in benign tumors (p = 0.0037). Similarly, the average normalized ADC for malignant tumors was 1.03, whereas the average normalized ADC for benign tumors was 1.65 (p = 0.0012). Receiver operating characteristic curve analysis yielded optimal normalized ADC and ADC thresholds of 1.23 (accuracy, 84.6%; sensitivity, 75.0%; specificity, 92.3%) and 1.01 × 10(-3) mm(2)/s (accuracy, 83.7%; sensitivity, 83.3%; specificity, 84.6%), respectively. There was a significant inverse correlation between cell density and normalized ADC (r = -0.58; p = 0.023). The low cellularity in chordoma and low-grade chondrosarcoma and high cellularity in eosinophilic granuloma may explain the DWI features of these lesions. CONCLUSION: ADC values in skull lesions correlate with cell density and can potentially narrow the differential diagnoses for indeterminate skull lesions. Understanding the histopathologic features of skull lesions can refine interpretation of DWI.

A representative cohort of patients with non-progressive multiple sclerosis at the age of normal life expectancy.

Multiple sclerosis may have a non-progressive symptomatology for decades; however, it is not clear whether the disease activity may abate completely. We identified a cohort of patients, resident in Gothenburg at the time of disease onset, between the years 1950-64 (n = 307). These geographical and temporal restrictions, along with favourable conditions for a 'spider' epidemiological study, were optimal for an unbiased selection; this 15-year incidence cohort was essentially followed prospectively for 37-59 years after onset. The shortest follow-up time for patients without primary or secondary progression was 45 years. For patients with an initial relapsing-remitting course and multiple sclerosis diagnosis according to the Poser criteria (n = 202), the probability of non-progressive disease after 40 years was 22% (standard error 3.0%), and after 50 years it was 14% (standard error 3.2%). For attack onset including patients with possible multiple sclerosis, the corresponding probabilities after 40 and 50 years were 35% (standard error 3.3%) and 28% (standard error 3.5%), respectively. At the last follow-up in 2009-10, when patients reached the average age of the Swedish population life expectancy, only 13 patients from the multiple sclerosis diagnosis cohort, according to the Poser criteria, remained alive and non-progressive. Their annualized attack frequency diminished with time from 0.29 to 0.015. These patients had been functioning well socially. Nine patients had an Expanded Disability Status Scale score of 0-2.5, and four patients had a score of 3 or 3.5, with deficits dating back to attacks decades ago. Eight patients participated in a complete neuropsychological examination, which showed a slight difference (P < 0.01) concerning verbal memory and executive function compared to an age and socially matched reference group, whereas results for five other cognitive domains were within the normal range. Magnetic resonance images fulfilled the Barkhof-Tintoré criteria for multiple sclerosis in 10 of 11 patients, with conspicuously few subcortical lesions relative to extensive periventricular lesions and lesions extending from the inferior midline aspect of the corpus callosum. Prediction of the non-progressive stage was possible with moderate hazard ratios and low sensitivity. Early features that predicted a non-progressive course were complete remission of the onset attack, low or moderate initial relapse frequency and-when the patients with possible multiple sclerosis were included-dominating afferent symptoms. The clinical disease activity had abated in these 13 patients, with the caveat that transition to secondary progression continued to occur after four decades, albeit with decreasing risk.

Spurious progression in pediatric brain tumors.

In this study, we sought to characterize post-therapy MRI changes mimicking progression, which we refer to as "spurious progression" (SP) in children with brain tumors. We analyzed whether SP is associated with particular tumor types or therapeutic modalities. Between 2000 and 2009, we identified 181 consecutive children <21 years of age at our center who were treated for brain tumors and had at least three MRI scans within a year after completing therapy. SP was defined as MRI abnormalities characterized by increase in size, enhancement, edema, or cystic changes within 12 months following therapy, and stabilization or improvement on subsequent imaging. One-hundred forty-one patients with brain tumors were evaluable. Fifty-six (40%) had imaging abnormalities initially suggestive of disease progression; of these, 34 (24%) had true disease progression (TP). The remaining 22 (16%) had SP based on either stability, decrease in enhancement, edema, size, or disappearance of these cystic or non-cystic abnormalities. SP occurred in patients with low grade (n = 20) and high grade lesions (n = 2). Median time to SP was 2.4 months (range, 0.7-8.3 months), with time to stability, decrease, or disappearance at a median of 4 months (range 1.4-7.7 months). Five patients were clinically symptomatic from SP and were treated with steroids, cyst drainage, and/or surgery. Therefore, SP occurs more commonly in children with low grade tumors, but can also occur with high grade brain tumors, regardless of therapeutic approach.

Progressive decline in fractional anisotropy on serial DTI examinations of the corpus callosum: a putative marker of disease activity and progression in SPMS.

INTRODUCTION: Clinical trials of secondary progressive multiple sclerosis (SPMS) is lacking reliable biomarkers or outcome measures that reflect tissue injury incurred within a 1- to 2-year observation period. Diffusion tensor imaging (DTI) is sensitive in detecting acute brain tissue damage. We monitored SPMS patients over 12 months for diffusion changes within the corpus callosum (CC). METHODS: Bimonthly MRI examinations over a 1-year period were performed on 11 SPMS patients. The protocol included postcontrast T1-weighted images and DTI. Based on the appearance of T1 enhancing lesion(s) during the study period, the patients were divided into enhancing (five patients) and nonenhancing (six patients) groups. Fractional anisotropy (FA) and mean diffusivity (MD) of the genu, body, and splenium of the CC were measured and temporal changes in mean FA and MD were evaluated for each group as well as between groups. Immunology data from peripheral blood mononuclear cells were also collected on a monthly basis. RESULTS: The enhancing group showed significant, progressive decrease in FA in body (p = 0.012) and splenium (p = 0.033) of CC, and significantly higher lymphotoxin-ß levels. No significant FA changes were seen in the nonenhancing group. Moreover, the FA decline in the enhancing group deviated significantly from the nonenhancing group, which remained essentially stable. Although MD increased slightly in both groups, there was no significant difference between the two groups. CONCLUSION: Based on the MR and immunology findings, the results of our study suggest that DTI undergo more rapid and longitudinal changes in SPMS patients with inflammatory activity.

Border zone infarcts: pathophysiologic and imaging characteristics.

Border zone or watershed infarcts are ischemic lesions that occur in characteristic locations at the junction between two main arterial territories. These lesions constitute approximately 10% of all brain infarcts and are well described in the literature. Their pathophysiology has not yet been fully elucidated, but a commonly accepted hypothesis holds that decreased perfusion in the distal regions of the vascular territories leaves them vulnerable to infarction. Two types of border zone infarcts are recognized: external (cortical) and internal (subcortical). To select the most appropriate methods for managing these infarcts, it is important to understand the underlying causal mechanisms. Internal border zone infarcts are caused mainly by hemodynamic compromise, whereas external border zone infarcts are believed to result from embolism but not always with associated hypoperfusion. Various imaging modalities have been used to determine the presence and extent of hemodynamic compromise or misery perfusion in association with border zone infarcts, and some findings (eg, multiple small internal infarcts) have proved to be independent predictors of subsequent ischemic stroke. A combination of several advanced techniques (eg, diffusion and perfusion magnetic resonance imaging and computed tomography, positron emission tomography, transcranial Doppler ultrasonography) can be useful for identifying the pathophysiologic process, making an early clinical diagnosis, guiding management, and predicting the outcome.