Claudia da Costa Leite

The Role of Conventional MR Imaging Sequences in the Evaluation of Neurocysticercosis: Impact on Characterization of the Scolex and Lesion Burden

BACKGROUND AND PURPOSE: There are few studies comparing the capacity of lesion detection of conventional MR imaging in neurocysticercosis (NCC). This study was designed to clarify its role in the evaluation of this disease, focusing on the total number of lesions identified and the characterization of the scolex. MATERIALS AND METHODS: MR images from 115 patients were prospectively collected during a 3-year interval, including axial spin-echo (SE) T1-weighted; axial fast SE T2-weighted; axial fluid-attenuated inversion recovery (FLAIR); and gadolinium-enhanced axial, coronal, and sagittal SE T1-weighted sequences. They were compared regarding the potential for detection of NCC lesions and specifically of the scolex. RESULTS: Comparing all sequences, we found that FLAIR images were more sensitive to the detection of the scolex (P < .003), whereas the last gadolinium-enhanced T1-weighted series (coronal or sagittal) identified the highest number of lesions (P < .001). CONCLUSION: When dealing with NCC, optimal MR imaging protocols should include FLAIR images to obtain maximal rates of scolex detection. Special attention should be paid to the last gadolinium-enhanced sequence, which maximizes the quantification of lesion load.

Multivoxel proton MR spectroscopy in malformations of cortical development.

BACKGROUND AND PURPOSE: Malformations of cortical development (MCD) are traditionally considered as a cause of epilepsy. Our aim was to study patients with focal MCD, by using multivoxel proton MR spectroscopy; we focused not only on the lesion but also on the normal-appearing contralateral side (NACS). Our hypothesis was that the metabolic abnormality extends to the NACS; therefore, it would be inadequate to consider NACS as an internal control. MATERIALS AND METHODS: We studied 16 patients with focal MCD. MR spectroscopy was performed by using a point-resolved spectroscopy sequence technique, including the MCD area and the NACS. In each volume of interest, a smaller volume of interest of 2.25 cm3 centered on the MCD was selected to study the N-acetylaspartate/creatine (NAA/Cr) ratio. In NACS, this ratio was studied by placing a symmetric voxel in comparison with the smaller MCD volume of interest. A control group (n = 30) was also studied to evaluate both white and gray matter by using the same MR spectroscopy protocol. RESULTS: From 16 analyzed volumes of interest with MCD, 9 were composed of gray matter heterotopia and 7 of cortical dysplasia. MR spectroscopy of both MCD lesions and NACS (n = 10) showed decreased NAA/Cr compared with that of the control group. NACS in these patients did not present significant differences regarding NAA/Cr in comparison with the affected side. CONCLUSIONS: MR spectroscopy demonstrated abnormal NAA/Cr in both MCD lesions and NACS in patients harboring focal MCD, giving support to the hypothesis that in MCD metabolic abnormalities extend far away from the limits of the lesion, reaching the contralateral side.

Varicella zoster CNS vascular complications: A report of four cases and literature review

This study evaluated the results of endovascular embolization of multiple intracranial aneurysms. A retrospective hospital chart and radiograph review were made of all patients with multiple intracranial aneurysms seen between March 2010 and January 2011. Ten patients presented with subarachnoid hemorrhage, four with mass effect, two with brain ischemia and twenty were incidental. These 36 patients harbored 84 aneurysms, 63 of which were treated with endovascular techniques, two by surgical clipping, and 19 were left untreated. Of the coil-treated lesions, a complete endovascular occlusion was achieved in 54 aneurysms (85.7%), and eight (12.7%) presented neck remnants with one (1.6%) stented only. Twenty-six patients (72.2%) underwent coil embolization of more than one aneurysm in the first session. Follow-up angiographic studies in 31 patients demonstrated an unchanged or improved result in 93.0% of the aneurysms (53 lesions) and coil compaction in 7.0% (four lesions). The overall clinical outcome was excellent in 33 patients (91.7%), good in one (2.8%) and fair in two (5.5%). Endovascular techniques may be a particularly suitable method for treating multiple intracranial aneurysms.This study explored the neurologic vascular complications of varicella zoster virus (VZV). We describe four patients presenting at our institution with neurologic involvement by VZV. MR and MRA studies of the intracranial arterial circulation in the head were read by board-certified radiologists using standard clinical procedures. On MRI, three patients had acute infarcts and in two instances irregularities and narrowings of vessels were visible. Many of these complications are recognized to be due to a vasculopathy affecting small or large vessels and resulting in cerebral infarctions and rarely hemorrhages. The pattern of cerebral infarction and vascular abnormalities is not specific and resembles those of vasculitis/vasculopathy from other causes. The central nervous system (CNS) vascular complications of VZV should be considered in the patients with simultaneous primary or prior VZV infection whose imaging studies show cerebral infarction and/or vasculitic appearing intracranial arteries.

Reduced Diffusion in Neurocysticercosis: Circumstances of Appearance and Possible Natural History Implications

BACKGROUND AND PURPOSE: Few studies discuss DWI findings in patients with NCC, and their conclusions are variable and contradictory. The aim of our study was to describe DWI findings of a cohort of patients with NCC, emphasizing the frequency of reduced diffusion. MATERIALS AND METHODS: This retrospective study included 48 patients with NCC. Two neuroradiologists analyzed MR images regarding location, number, and stage of NCC lesions. On the basis of visual analysis, they defined, by consensus, the presence of high signal within NCC lesions on DWI and measured their ADC values when feasible. RESULTS: The total number of lesions was 342: parenchymal (263), subarachnoid (65), and intraventricular (14); 83 were DWI hyperintense. The first pattern was a small eccentric hyperintense dot/curvilinear structure on DWI (representing the scolex) noted in intraparenchymal lesions in vesicular (41 lesions, 29%) and colloidal vesicular (18 lesions, 19%) stages, in 14 (22%) subarachnoid lesions, and 2 (14%) intraventricular lesions; rADC calculations were hampered by the intrinsic small dimensions of this finding. The second pattern was the presence of total/subtotal DWI hyperintensity in intraparenchymal lesions, 5 in the colloidal vesicular stage (5%) and 1 in the granular nodular phase (3%). Two subarachnoid lesions also showed the same presentation; in this second pattern, reduced diffusion was present in different degrees, measured by rADC calculations. CONCLUSIONS: DWI may identify the scolex, increasing diagnostic confidence for NCC. Total/subtotal DWI hyperintensity, related to the stage of the lesion, though uncommon, allows including NCC as a consideration in the differential diagnosis of lesions with reduced diffusion and ring enhancement.

MR Spectroscopy Detects Lipid Peaks in Cerebrotendinous Xanthomatosis

SUMMARY: CTX is a rare lipid-storage disease. Novel MRS findings from 3 patients, using a short TE, were the presence of lipid peaks at 0.9 and 1.3 ppm in the depth of the cerebellar hemisphere; this might represent an additional marker of disease that is CNS-specific and noninvasive. A decrease in NAA concentration was also detected and attributed to neuroaxonal damage. One patient presented an increase in mIns concentration, pointing to gliosis and astrocytic proliferation.

Correlation of magnetization transfer and diffusion magnetic resonance imaging in multiple sclerosis.

The aim of this study was to correlate diffusion to magnetization transfer (MT) magnetic resonance imaging (MRI) results in multiple sclerosis (MS), in order to establish if the former technique provides complementary information. Magnetization transfer ratio (MTR) and apparent diffusion coefficient (ADC) were measured in 156 different regions of interest (ROIs) of 14 MS patients, where 84 corresponded to T1 hypointense lesions, 60 to T1 isointense lesions and 12 to regions of normal appearing white matter (NAWM). MTR mean value was higher for T1 isointense than for T1 hypointense lesions, and lower when compared to NAWM. ADC mean value for T1 isointense lesions was higher than for NAWM, but lower than for T1 hypointense lesions. A significant negative correlation was found between ADC and MTR for hypointense lesions (Pearson’s r =- 0.758, PB < 0.001), whereas this correlation was much weaker for T1 isointense lesions (Pearson’s r =- 0.256, P = 0.049). There was no correlation between ADC and MTR for NAWM. The fact that ADC and MTR show a strong correlation only for T1 hypointense lesions indicates that, when tissue integrity is not severely compromised, as in the case of T1 isointense lesions or NAWM, ADC and MTR might be sensitive to different pathological processes.

Histiocytosis: a review focusing on neuroimaging findings

OBJECTIVEnHistiocytosis is a systemic disease that usually affects the central nervous system. The aim of this study is to discuss the neuroimaging characteristics of Langerhans cell histiocytosis (LCH), the most common of these diseases; and the non-Langerhans cells histiocytosis (NLCH), which includes entities such as hemophagocytic syndrome, Erdheim-Chester and Rosai-Dorfman diseases.nnnMETHODnLiterature review and illustrative cases with pathologic confirmation.nnnRESULTSnIn LCH, the most common findings are 1) osseous lesions in the craniofacial bones and/or skull base; 2) intracranial, extra-axial changes; 3) intra-axial parenchymal changes (white and gray matter); 4) atrophy. Among the NLCH, diagnosis usually requires correlation with clinical and laboratory criteria. The spectrum of presentation includes intraparenchymal involvement, meningeal lesions, orbits and paranasal sinus involvement.nnnCONCLUSIONnIt is important the recognition of the most common imaging patterns, in order to include LCH and NLCH in the differential diagnosis, whenever pertinent.

Selecting the most relevant brain regions to discriminate Alzheimer's disease patients from healthy controls using multiple kernel learning: A comparison across functional and structural imaging modalities and atlases

Background Machine learning techniques such as support vector machine (SVM) have been applied recently in order to accurately classify individuals with neuropsychiatric disorders such as Alzheimers disease (AD) based on neuroimaging data. However, the multivariate nature of the SVM approach often precludes the identification of the brain regions that contribute most to classification accuracy. Multiple kernel learning (MKL) is a sparse machine learning method that allows the identification of the most relevant sources for the classification. By parcelating the brain into regions of interest (ROI) it is possible to use each ROI as a source to MKL (ROI-MKL). Methods We applied MKL to multimodal neuroimaging data in order to: 1) compare the diagnostic performance of ROI-MKL and whole-brain SVM in discriminating patients with AD from demographically matched healthy controls and 2) identify the most relevant brain regions to the classification. We used two atlases (AAL and Brodmanns) to parcelate the brain into ROIs and applied ROI-MKL to structural (T1) MRI, 18F-FDG-PET and regional cerebral blood flow SPECT (rCBF-SPECT) data acquired from the same subjects (20 patients with early AD and 18 controls). In ROI-MKL, each ROI received a weight (ROI-weight) that indicated the regions relevance to the classification. For each ROI, we also calculated whether there was a predominance of voxels indicating decreased or increased regional activity (for 18F-FDG-PET and rCBF-SPECT) or volume (for T1-MRI) in AD patients. Results Compared to whole-brain SVM, the ROI-MKL approach resulted in better accuracies (with either atlas) for classification using 18F-FDG-PET (92.5% accuracy for ROI-MKL versus 84% for whole-brain), but not when using rCBF-SPECT or T1-MRI. Although several cortical and subcortical regions contributed to discrimination, high ROI-weights and predominance of hypometabolism and atrophy were identified specially in medial parietal and temporo-limbic cortical regions. Also, the weight of discrimination due to a pattern of increased voxel-weight values in AD individuals was surprisingly high (ranging from approximately 20% to 40% depending on the imaging modality), located mainly in primary sensorimotor and visual cortices and subcortical nuclei. Conclusion The MKL-ROI approach highlights the high discriminative weight of a subset of brain regions of known relevance to AD, the selection of which contributes to increased classification accuracy when applied to 18F-FDG-PET data. Moreover, the MKL-ROI approach demonstrates that brain regions typically spared in mild stages of AD also contribute substantially in the individual discrimination of AD patients from controls.

Gasserian ganglion neurosarcoidosis mimicking trigeminal schwannoma.

AMRIofa59-year-oldmalewithrighthemifacialhypoesthe-siashowedalowsignalT2-weightedexpansivemassintherightMeckel’s cave. After failure of initial conservative treatment(Figure 1), surgery was done with partial lesion resection(Figure 2). The pathology and chest CT were consistent withgranulomatous disease: neurosarcoidosis. On follow-up thelesion increased in size but after corticosteroids it reversed(Figure 3). The involvement of the trigeminal nerve is very rarewith only few cases described in literature. Although rare, sar-coid infiltration of the Gasserian ganglion must be consideredinthedifferentialdiagnosisofanisolatedmassatMeckel ’scave,especially if it has T2 hypointensity signal.

Myoinositol reduction in medial prefrontal cortex of obsessive compulsive disorder: a proton magnetic resonance spectroscopy study

Background: Late Onset Alzheimer’s Disease (LOAD) is one of the most common debilitating causes of dementia worldwide with heritability estimates ranging from 50 – 70%. Genome-wide association studies (GWAS) have identified more than 20 genetic loci in addition to APOEe4 that are associated with increased risk for LOAD. While most of these genes have weak effects, using a polygenic risk profile score (RPS) approach – a method that allows exploration of the influence of the cumulative effect of risk alleles we and others have shown the negative influence of LOAD risk genes on brain structure (Chauhan et al., 2015) and function (Xiao et al., 2015 HBM) even in healthy volunteers. Identifying mechanisms, particularly genetic mechanisms that confer resilience to the detrimental effect of LOAD related risk genes on brain structure and function could provide a viable avenue to identify novel therapeutic targets for LOAD. To that end, in the current study, we explored the role of polymorphisms in the gene encoding Reelin (RELN), a glycoprotein that has been shown to be critical for neuronal development and synaptic plasticity (Kramer et al. 2011), on the detrimental effect of LOAD RPS on hippocampal function. Studies have shown that normal RELN levels are necessary to prevent abnormal phosphorylation of tau (Ohkubo et al., 2003) and beta-amyloidinduced suppression of long term potentiation and NMDA receptors (Durakoglugil et al., 2009). Methods: BOLD functional MRI images (GE 3 T MRI scanner, TR/TE 1⁄4 2000/28ms, flip angle 1⁄4 90 deg, FOV 1⁄4 64x64, 24 axial slices, 170 volumes) were collected for 265 right-handed Caucasian healthy volunteers (116 male, 149 female) from the age of 18 to 86 years (SD 1⁄4 14.17) while they performed a simple declarative memory task (SDMT). Images were motion-corrected, normalized to MNI space, and spatially smoothed (8mm FWHM) using SPM5. Odd’s ratios of 22 independent SNPs, with Po1 10-5 in Hollingworth’s metaanalysis1 comprising four Alzheimer’s disease GWAS datasets (GERAD1, EADI1, TGEN1, ADNI), spanning the regions of ABCA7, APOC4, APOE, BCAM, BCL3, BIN1, C16orf88, CDK1, CEACAM1E, CLPTMI, CLU, CNTN5, CR1, CR2, CUX2, EXOC3L2, IQCK, LRRC68, MS4A4A, MS4A4E, MS4A6A, PICALM, PVR, PVRL2, and TOMM40 genes, were used to calculate the RPS for each individual subject using the approach described by Purcell et al.3. Association between RPS and hippocampal activation during the neutral encoding phase of the SDMT was tested using SPM12. To control for population stratification, 5 MDS components based on 8M SNP genotypes from a GWAS analysis extracted with EIGENSOFT5.01 were included in the analysis as covariates along with age, gender, SNAV, and genotyping batch labels. A region of interest analysis was performed using bilateral hippo-parahippocampal masks from the Anatomical Automatic Labeling Atlas. Influence of RELN on association between LOAD related AD RPS and hippocampal activation was examined separately for five independent Reelin polymorphisms (rs736707, rs362691, rs7341475, rs6943822, and rs4298437.) previously implicated in Alzheimer’s disease or Autism Spectrum Disease using flexible factorial analysis in SPM12. Results: fMRI analysis showed a significant negative correlation between LOAD RPS and hippocampal activation (left: PFWE_corrected 1⁄4 0.005, MNI coordinates x 1⁄4 -39, y 1⁄4 -24, z 1⁄4 -12, right: PFWE_corrected 1⁄4 0.139, Puncorrectedo0.001, MNI coordinates x 1⁄4 39, y 1⁄4 -18, z 1⁄4 -18) during the neutral encoding phase of SDMT. There were no significant positive correlations. In addition, there was a significant interactive effect (left: PFWE_corrected 1⁄4 0.076, MNI coordinates x 1⁄4 -30, y 1⁄4 -30, z 1⁄4 -6, right: PFWE_corrected 1⁄4 0.368, Puncorrected1⁄4 0.002, MNI coordinates x 1⁄4 27, y 1⁄4 -33, z 1⁄4 -9) of rs362691 genotype (a G-C missense variant) and LOAD RPS on activation. Furthermore, in the left hippocampus, minor allele C carriers (N1⁄4 56) showed a significant negative relationship (r1⁄4 -0.47, p1⁄4 0.0002, post-hoc analysis in R) between RPS and hippocampal activation, while the major allele G homozygotes (N1⁄4 208) showed no such relationship (r1⁄4 0.0071, p1⁄4 0.9186). None of the other RELN polymorphisms tested showed a significant effect. Conclusions: Our results, while showing a cumulative deleterious effect of several LOAD related risk genes on hippocampal function in healthy volunteers, also illustrate that this relationship is modulated by a missense SNP (rs362691) in the RELN gene. In particular, only the minor allele C carriers show a significant negative relationship between RPS and hippocampal function suggesting that homozygosity for the G allele in this polymorphism could potentially confer a protective effect.