Fully automated atlas-based MR imaging volumetry in Huntington disease, compared with manual volumetry

Structural and microstructural neuroimaging signature of C9orf72-associated ALS: A multiparametric MRI study

BACKGROUND

ALS patients with hexanucleotide expansion in C9orf72 are characterized by a specific clinical phenotype, including more aggressive disease course and cognitive decline. Computerized multiparametric MRI with gray matter volumetry and diffusion tensor imaging (DTI) to analyze white matter structural connectivity is a potential in vivo biomarker.

OBJECTIVE

The objective of this study was to develop a multiparametric MRI signature in a large cohort of ALS patients with C9orf72 mutations. The aim was to investigate how morphological features of C9orf72-associated ALS differ in structural MRI and DTI compared to healthy controls and ALS patients without C9orf72 mutations.

METHODS

Atlas-based volumetry (ABV) and whole brain-based DTI-based analyses were performed in a cohort of n = 51 ALS patients with C9orf72 mutations and compared with both n = 51 matched healthy controls and n = 51 C9orf72 negative ALS patients, respectively. Subsequently, Spearman correlation analysis of C9orf72 ALS patients' data with clinical parameters (age of onset, sex, ALS-FRS-R, progression rate, survival) as well as ECAS and p-NfH in CSF was performed.

RESULTS

The whole brain voxel-by-voxel comparison of fractional anisotropy (FA) maps between C9orf72 ALS patients and controls showed significant bilateral alterations in axonal structures of the white matter at group level, primarily along the corticospinal tracts and in fibers projecting to the frontal lobes. For the frontal lobes, these alterations were also significant between C9orf72 positive and C9orf72 negative ALS patients. In ABV, patients with C9orf72 mutations showed lower volumes of the frontal, temporal, and parietal lobe, with the lowest values in the gray matter of the superior frontal and the precentral gyrus, but also in hippocampi and amygdala. Compared to C9orf72 negative ALS, the differences were shown to be significant for cerebral gray matter (p = 0.04), especially in the frontal (p = 0.01) and parietal lobe (p = 0.01), and in the thalamus (p = 0.004). A correlation analysis between ECAS and averaged regional FA values revealed significant correlations between cognitive performance in ECAS and frontal association fibers. Lower FA values in the frontal lobes were associated with worse performance in all cognitive domains measured (language, verbal fluency, executive functions, memory and spatial perception). In addition, there were significant negative correlations between age of onset and atlas-based volumetry results for gray matter.

CONCLUSIONS

This study demonstrates a distinct pattern of DTI alterations of the white matter and ubiquitous volume reductions of the gray matter early in the disease course of C9orf72-associated ALS. Alterations were closely linked to a more aggressive cognitive phenotype. These results are in line with an expected pTDP43 propagation pattern of cortical affection and thus strengthen the hypothesis that an underlying developmental disorder is present in ALS with C9orf72 expansions. Thus, multiparametric MRI could contribute to the assessment of the disease as an in vivo biomarker even in the early phase of the disease.

Reduced-penetrance Huntington's disease-causing alleles with 39 CAG trinucleotide repeats could be a genetic factor of amyotrophic lateral sclerosis

BACKGROUND

Expanded HTT alleles with 40 or more CAG repeats were recently found to be a rare cause of frontotemporal dementia and amyotrophic lateral sclerosis (ALS) spectrum diseases. The aim of this study was to investigate the role of HTT repeat expansions in a Taiwanese cohort with ALS.

METHODS

We analyzed the numbers of CAG repeats in exon 1 of HTT in a cohort of 410 Taiwanese patients with ALS and 1514 control individuals by utilizing polymerase chain reaction and amplicon fragment length analysis.

RESULTS

Only one of the 410 ALS patients carried a reduced-penetrance HD-causing allele with 39 CAG repeats, and none had an expanded HTT CAG repeats ≥40. The patient presented with rapidly progressive bulbar-onset ALS with disease onset at the age of 64 years. He had neither chorea nor cognitive impairment. He had a family history of chorea, but no other family member manifested with ALS. None of the 1514 control individuals carried an HTT expanded allele with CAG repeats larger than 37 repeats.

CONCLUSION

The HTT allele with 39 CAG repeats could be a genetic factor linked to ALS susceptibility.

Validating Automated Segmentation Tools in the Assessment of Caudate Atrophy in Huntington's Disease

Background: Neuroimaging shows considerable promise in generating sensitive and objective outcome measures for therapeutic trials across a range of neurodegenerative conditions. For volumetric measures the current gold standard is manual delineation, which is unfeasible for samples sizes required for large clinical trials. Methods: Using a cohort of early Huntington's disease (HD) patients (n = 46) and controls (n = 35), we compared the performance of four automated segmentation tools (FIRST, FreeSurfer, STEPS, MALP-EM) with manual delineation for generating cross-sectional caudate volume, a region known to be vulnerable in HD. We then examined the effect of each of these baseline regions on the ability to detect change over 15 months using the established longitudinal Caudate Boundary Shift Integral (cBSI) method, an automated longitudinal pipeline requiring a baseline caudate region as an input. Results: All tools, except Freesurfer, generated significantly smaller caudate volumes than the manually derived regions. Jaccard indices showed poorer levels of overlap between each automated segmentation and manual delineation in the HD patients compared with controls. Nevertheless, each method was able to demonstrate significant group differences in volume (p < 0.001). STEPS performed best qualitatively as well as quantitively in the baseline analysis. Caudate atrophy measures generated by the cBSI using automated baseline regions were largely consistent with those derived from a manually segmented baseline, with STEPS providing the most robust cBSI values across both control and HD groups. Conclusions: Atrophy measures from the cBSI were relatively robust to differences in baseline segmentation technique, suggesting that fully automated pipelines could be used to generate outcome measures for clinical trials.

SeSBAT: Single Subject Brain Analysis Toolbox. Application to Huntington's Disease as a Preliminary Study

Magnetic resonance imaging (MRI) biomarkers require complex processing routines that are time-consuming and labor-intensive for clinical users. The Single Subject Brain Analysis Toolbox (SeSBAT) is a fully automated MATLAB toolbox with a graphical user interface (GUI) that offers standardized and optimized protocols for the pre-processing and analysis of anatomical MRI data at the single-subject level. In this study, the two-fold strategy provided by SeSBAT is illustrated through its application on a cohort of 42 patients with Huntington’s disease (HD), in pre-manifest and early manifest stages, as a suitable model of neurodegenerative processes. On the one hand, hypothesis-driven analysis can be used to extract biomarkers of neurodegeneration in specific brain regions of interest (ROI-based analysis). On the other hand, an exploratory voxel-based morphometry (VBM) approach can detect volume changes due to neurodegeneration throughout the whole brain (whole-brain analysis). That illustration reveals the potential of SeSBAT in providing potential prognostic biomarkers in neurodegenerative processes in clinics, which could be critical to overcoming the limitations of current qualitative evaluation strategies, and thus improve the diagnosis and monitoring of neurodegenerative disorders. Furthermore, the importance of the availability of tools for characterization at the single-subject level has been emphasized, as there is high interindividual variability in the pattern of neurodegeneration. Thus, tools like SeSBAT could pave the way towards more effective and personalized medicine.

Semi-automatic magnetic resonance imaging based orbital fat volumetry: reliability and correlation with computed tomography

Post-processing analysis can provide valuable information for diagnosis and planning of orbital disorders. This cross-sectional study aims to evaluate the reliability of semi-automatic, orbital fat volumetry using magnetic resonance imaging (MRI). Two observers assessed the orbital fat volume using a standard MRI protocol (3T, T1w sequence) in 12 orbits diagnosed with Graves' orbitopathy (GO) and 10 healthy control orbits. MRI and computed tomography (CT) based analysis were compared. Intra-observer variability was good (intraclass correlation coefficient (ICC) 0.88; 95% confidence interval (CI) [0.70, 0.95]) and interobserver agreement was moderate (ICC 0.55; 95% CI [-0.09, 0.81]), which corresponds to a mean percentage difference of 1.3% and 17.9% of the total orbital fat volume. Mean differences between MRI and CT measurements were, respectively, 1.1 cm³ (P= 0.064, 95% CI [-0.20, 2.43]) and 1.4 cm³ (P=0.016, 95% CI [0.21, 2.56]) for the control and the GO group. MRI volumetry was strongly correlated with CT (Pearson's r= 0.7, P<0.001). We conclude that orbital fat volumetry is feasible with a semi-automatic segmentation procedure and standard MRI protocol. Correlation with CT volumetry is good, but considerable bias may derive from observer variability and these errors should be taken into account for the purpose of volumetric analysis. Better definition of error sources may increase measurement accuracy.

Volume estimation of brain ventricles using Cavalieri's principle and Atlas-based methods in Alzheimer disease: Consistency between methods

Automatic estimations of brain ventricles are needed to assess disease progression in neurodegenerative disorders such as Alzheimer Disease (AD). The objectives of this study are to evaluate the diagnostic performances of an automated volumetric assessment tool in estimating lateral ventricle volumes in AD and to compare this with Cavalieri's principle, which is accepted as the gold standard method. This is across-sectional volumetric study including 25 Alzheimer patients and 25 healthy subjects undergoing magnetic resonance images (MRI) with a 3D turbo spin echo sequence at 1.5 Tesla. The Atlas-based method incorporated MRIStudio software to automatically measure he volumes of brain ventricles. To compare the corresponding measurements, we used manual point-counting and semi-automatic planimetry methods based on Cavalieri's principle. Bland-Altman test results indicated an excellent agreement between Cavalieri's principle and the Atlas-based method in all volumetric measurements (p < 0.05). We obtained a 64% sensitivity and 92% specificity for lateral ventricular volumes according to the Atlas-based method. AD subjects had significantly larger left and right lateral ventricle volume (LVV) when compared to control subjects in respect to three volumetric methods (p < 0.01). Lateral ventricle-to-brain ratio (VBR) statistically increased 49.23% in measurements done with the point-counting method, 45.12% with the planimetry method, and 45.49% with the Atlas-based method in AD patients (p < 0.01). As a result, the Atlas-based method may be used instead of manual volumetry to estimate brain volumes. Additionally, this method provides rapid and accurate estimations of brain ventricular volumes in-vivo examination of MRI.

Combined cerebral atrophy score in Huntington's disease based on atlas-based MRI volumetry: Sample size calculations for clinical trials

INTRODUCTION

A volumetric MRI analysis of longitudinal regional cerebral atrophy in Huntington's disease (HD) was performed as a read-out of disease progression to calculate sample sizes for future clinical trials.

METHODS

This study was based on MRI data of 59 patients with HD and 40 controls recruited within the framework of the PADDINGTON study and investigated at baseline and follow-up after 6 and 15 months. Automatic atlas-based volumetry (ABV) of structural T1-weighted scans was used to calculate longitudinal volume changes of brain structures relevant in HD and to assess standardized effect sizes and sample sizes required for potential future studies.

RESULTS

Atrophy rates were largest in the caudate (-3.4%), putamen (-2.8%), nucleus accumbens (-1.6%), and the parietal lobes (-1.7%); the lateral ventricles showed an expansion by 6.0%. Corresponding effect sizes were -1.35 (caudate), -0.84 (putamen), -0.91 (nucleus accumbens), -1.05 (parietal lobe), and 0.92 (lateral ventricles) leading to N = 36 subjects per study group for detecting a 50% attenuation of atrophy for the best performing structure (caudate). A combined score of volume changes in non-overlapping compartments (striatum, parietal lobes, lateral ventricles) increased the effect size to -1.60 and substantially reduced the required sample sizes by 10 to N = 26 subjects per study group. This combined imaging score correlated significantly both with the CAP score and with the progression of the clinical phenotype.

CONCLUSION

We propose ABV of the striatum together with parietal lobe and lateral ventricle volumes as a combined imaging read-out for progression studies including clinical trials in HD.

The applause sign in frontotemporal lobar degeneration and related conditions

The applause sign, i.e., the inability to execute the same amount of claps as performed by the examiner, was originally reported as a sign specific for progressive supranuclear palsy (PSP). Recent research, however, has provided evidence for the occurrence of the applause sign in various conditions. The aim of this study was to determine the prevalence of the applause sign and correlate its presence with neuropsychological and MRI volumetry findings in frontotemporal lobar degeneration and related conditions. The applause sign was elicited with the three clap test (TCT), with a higher score indicating poorer performance. Data were recorded from 272 patients from the cohort of the German consortium for frontotemporal lobar degeneration (FTLDc): 111 with behavioral variant frontotemporal dementia (bvFTD), 98 with primary progressive aphasia (PPA), 30 with progressive supranuclear palsy Richardson's syndrome, 17 with corticobasal syndrome (CBS) and 16 with amyotrophic lateral sclerosis with frontotemporal dementia (ALS/FTD). For comparison, 29 healthy elderly control subjects (HC) were enrolled in the study. All subjects underwent detailed language and neuropsychological assessment. In a subset of 156 subjects, atlas-based volumetry was performed. The applause sign occurred in all patient groups (40% in PSP, 29.5% in CBS, 25% in ALS/FTD, 13.3% in PPA and 9.0% in bvFTD) but not in healthy controls. The prevalence was highest in PSP patients. It was significantly more common in PSP as compared to bvFTD, PPA and HC. The comparison between the other groups failed to show a significant difference regarding the occurrence of the applause sign. The applause sign was highly correlated to a number of neuropsychological findings, especially to measures of executive, visuospatial, and language function as well as measures of disease severity. TCT scores showed an inverse correlation with the volume of the ventral diencephalon and the pallidum. Furthermore the volume of the ventral diencephalon and pallidum were significantly smaller in patients displaying the applause sign. Our study confirms the occurrence of the applause sign in bvFTD, PSP and CBS and adds PPA and ALS/FTD to these conditions. Although still suggestive of PSP, clinically it must be interpreted with caution. From the correlation with various cognitive measures we suggest the applause sign to be indicative of disease severity. Furthermore we suggest that the applause sign represents dysfunction of the pallidum and the subthalamic nucleus, structures which are known to play important roles in response inhibition.

Atrophy in the Thalamus But Not Cerebellum Is Specific for C9orf72 FTD and ALS Patients - An Atlas-Based Volumetric MRI Study

Background: The neuropathology of patients with frontotemporal dementia (FTD) or amyotrophic lateral sclerosis (ALS) due to a C9orf72 mutation is characterized by two distinct types of characteristic protein depositions containing either TDP-43 or so-called dipeptide repeat proteins that extend beyond frontal and temporal regions. Thalamus and cerebellum seem to be preferentially affected by the dipeptide repeat pathology unique to C9orf72 mutation carriers.

Objective: This study aimed to determine if mutation carriers showed an enhanced degree of thalamic and cerebellar atrophy compared to sporadic patients or healthy controls.

Methods: Atlas-based volumetry was performed in 13 affected C9orf72 FTD, ALS and FTD/ALS patients, 45 sporadic FTD and FTD/ALS patients and 19 healthy controls. Volumes and laterality indices showing significant differences between mutation carriers and sporadic patients were subjected to binary logistic regression to determine the best predictor of mutation carrier status.

Results: Compared to sporadic patients, mutation carriers showed a significant volume reduction of the thalamus, which was most striking in the occipital, temporal and prefrontal subregion of the thalamus. Disease severity measured by mini mental status examination (MMSE) and FTD modified Clinical Dementia Rating Scale Sum of Boxes (FTD-CDR-SOB) significantly correlated with volume reduction in the aforementioned thalamic subregions. No significant atrophy of cerebellar regions could be detected. A logistic regression model using the volume of the prefrontal and the laterality index of the occipital subregion of the thalamus as predictor variables resulted in an area under the curve (AUC) of 0.88 while a model using overall thalamic volume still resulted in an AUC of 0.82.

Conclusion: Our data show that thalamic atrophy in C9orf72 mutation carriers goes beyond the expected atrophy in the prefrontal and temporal subregion and is in good agreement with the cortical atrophy pattern described in C9orf72 mutation carriers, indicating a retrograde degeneration of functionally connected regions. Clinical relevance of the detected thalamic atrophy is illustrated by a correlation with disease severity. Furthermore, the findings suggest MRI volumetry of the thalamus to be of high predictive value in differentiating C9orf72 mutation carriers from patients with sporadic FTD.

Differentiation of neurodegenerative parkinsonian syndromes by volumetric magnetic resonance imaging analysis and support vector machine classification

BACKGROUND

Clinical differentiation of parkinsonian syndromes is still challenging.

OBJECTIVES

A fully automated method for quantitative MRI analysis using atlas-based volumetry combined with support vector machine classification was evaluated for differentiation of parkinsonian syndromes in a multicenter study.

METHODS

Atlas-based volumetry was performed on MRI data of healthy controls (n = 73) and patients with PD (204), PSP with Richardson's syndrome phenotype (106), MSA of the cerebellar type (21), and MSA of the Parkinsonian type (60), acquired on different scanners. Volumetric results were used as input for support vector machine classification of single subjects with leave-one-out cross-validation.

RESULTS

The largest atrophy compared to controls was found for PSP with Richardson's syndrome phenotype patients in midbrain (-15%), midsagittal midbrain tegmentum plane (-20%), and superior cerebellar peduncles (-13%), for MSA of the cerebellar type in pons (-33%), cerebellum (-23%), and middle cerebellar peduncles (-36%), and for MSA of the parkinsonian type in the putamen (-23%). The majority of binary support vector machine classifications between the groups resulted in balanced accuracies of >80%. With MSA of the cerebellar and parkinsonian type combined in one group, support vector machine classification of PD, PSP and MSA achieved sensitivities of 79% to 87% and specificities of 87% to 96%. Extraction of weighting factors confirmed that midbrain, basal ganglia, and cerebellar peduncles had the largest relevance for classification.

CONCLUSIONS

Brain volumetry combined with support vector machine classification allowed for reliable automated differentiation of parkinsonian syndromes on single-patient level even for MRI acquired on different scanners. © 2016 International Parkinson and Movement Disorder Society.

Patterns of Eye Movement Impairment Correlate with Regional Brain Atrophy in Neurodegenerative Parkinsonism

BACKGROUND

One common feature of neurodegenerative parkinsonism including Parkinson's disease (PD), multisystem atrophy (MSA), and progressive supranuclear palsy (PSP) is altered eye movement control. Characteristic regional structural atrophy patterns in MRI can be observed in PD, MSA, and PSP.

OBJECTIVE

To investigate the association between eye movement disturbances and regional brain atrophy in patients with PD, MSA, and PSP.

METHODS

High-resolution 3-dimensional T1-weighted MRI images and video-oculographic recordings (EyeLink®) were obtained from 39 PD, 32 PSP, and 18 MSA patients and 24 matched healthy control subjects. Automatic regional volumetric assessment was performed using atlas-based volumetry (ABV).

RESULTS

The prevalence of saccadic intrusions as a measure of inhibitory control was significantly increased in PD patients compared to controls (p < 0.001) and negatively correlated with whole brain volume, cerebral brain volume, and occipital lobe volume (p = 0.0057, p = 0.0049, and p = 0.0059, respectively; all p values are false discovery rate corrected). In MSA, smooth pursuit was disturbed by characteristic "catch-up" saccades (p < 0.001) and it was significantly correlated with cerebellar volume (p = 0.004) and pontine volume (p < 0.001). The hallmark of PSP was pathologically slowed vertical peak eye velocities (p < 0.001); the lower the peak eye velocity, the more marked midbrain atrophy (p = 0.007).

CONCLUSIONS

Foci of regional atrophy correlated with disease-specific eye movement alterations in all investigated parkinsonian syndromes. Oculomotor impairment in PD, predominantly the result of executive dysfunction, was linked to cerebral atrophy. Impairment in the corresponding oculomotor pathways was associated with atrophy of pontocerebellar oculomotor structures in MSA and midbrain atrophy in PSP.

Neurofilament as a blood marker for diagnosis and monitoring of primary progressive aphasias

Objective:

To assess the utility of serum neurofilament for diagnosis and monitoring of primary progressive aphasia (PPA) variants.

Methods:

We investigated neurofilament light chain (NF-L) levels in blood of 99 patients with PPA (40 with nonfluent variant PPA [nfvPPA], 38 with semantic variant PPA [svPPA], 21 with logopenic variant PPA [lvPPA]) and compared diagnostic performance with that reached by CSF NF-L, phosphorylated neurofilament heavy chain (pNF-H), β-amyloid (Aβ1-42), tau, and phosphorylated tau. The longitudinal change of blood NF-L levels was measured and analyzed for correlation with functional decline and brain atrophy.

Results:

Serum NF-L is increased in PPA compared to controls and discriminates between nfvPPA/svPPA and lvPPA with 81% sensitivity and 67% specificity (cutoff 31 pg/mL). CSF NF-L, pNF-H, tau, phosphorylated tau, and Aβ1-42achieved similar performance, and pNF-H was the only marker for discrimination of nfvPPA from svPPA/lvPPA. In most patients with nfvPPA and svPPA, but not lvPPA, serum NF-L increased within follow-up. The increase correlated with functional decline and progression of atrophy of the left frontal lobe of all patients with PPAs and the right middle frontal gyrus of patients with nfvPPA and svPPA.

Conclusions:

Blood level of NF-L can aid the differential diagnosis of PPA variants, especially in combination with CSF pNF-H. Because serum NF-L correlates with functional decline and atrophy in the disease course, it qualifies as an objective disease status marker. Extended follow-up studies with cases of known neuropathology are imperative.

Classification of evidence:

This study provides Class I evidence that in patients with PPA, blood levels of NF-L can distinguish the logopenic variant from the nonfluent/agrammatic and semantic variants.

Computer-based magnetic resonance imaging as a tool in clinical diagnosis in neurodegenerative diseases

Magnetic resonance imaging (MRI) is one of the core elements within the differential diagnostic work-up of patients with neurodegenerative diseases such as dementia syndromes, Parkinsonian syndromes, and motor neuron diseases. Currently, computerized MRI analyses are not routinely used for individual diagnosis; however, they have improved the anatomical understanding of pathomorphological alterations in various neurodegenerative diseases by quantitative comparisons between patients and controls at the group level. For multiparametric MRI protocols, including T1-weighted MRI, diffusion-weighted imaging, and intrinsic functional connectivity MRI, the potential as a surrogate marker is a subject of investigation. The additional value of MRI with respect to diagnosis at the individual level and for future disease-modifying multicentre trials remains to be defined. Here, we give an overview of recent applications of multiparametric MRI to patients with various neurodegenerative diseases. Starting from applications at the group level, continuous progress of a transfer to individual diagnostic classification is ongoing.

Atlas based brain volumetry: How to distinguish regional volume changes due to biological or physiological effects from inherent noise of the methodology

Fully-automated regional brain volumetry based on structural magnetic resonance imaging (MRI) plays an important role in quantitative neuroimaging. In clinical trials as well as in clinical routine multiple MRIs of individual patients at different time points need to be assessed longitudinally. Measures of inter- and intrascanner variability are crucial to understand the intrinsic variability of the method and to distinguish volume changes due to biological or physiological effects from inherent noise of the methodology. To measure regional brain volumes an atlas based volumetry (ABV) approach was deployed using a highly elastic registration framework and an anatomical atlas in a well-defined template space. We assessed inter- and intrascanner variability of the method in 51 cognitively normal subjects and 27 Alzheimer dementia (AD) patients from the Alzheimer's Disease Neuroimaging Initiative by studying volumetric results of repeated scans for 17 compartments and brain regions. Median percentage volume differences of scan-rescans from the same scanner ranged from 0.24% (whole brain parenchyma in healthy subjects) to 1.73% (occipital lobe white matter in AD), with generally higher differences in AD patients as compared to normal subjects (e.g., 1.01% vs. 0.78% for the hippocampus). Minimum percentage volume differences detectable with an error probability of 5% were in the one-digit percentage range for almost all structures investigated, with most of them being below 5%. Intrascanner variability was independent of magnetic field strength. The median interscanner variability was up to ten times higher than the intrascanner variability.

Frontal corpus callosum alterations in progressive supranuclear palsy but not in Parkinson's disease

BACKGROUND

Frontal lobe involvement is considered a clinical and magnetic resonance imaging (MRI) feature in later stages of progressive supranuclear palsy (PSP).

OBJECTIVE

Diffusion tensor imaging (DTI) was used to investigate the integrity of frontal pathways in PSP and Parkinson's disease (PD) patients.

METHODS

DTI and 3-D MRI were performed in 15 PSP patients (parkinsonism subtype: n = 8; Richardson subtype: n = 7), 15 PD patients, and 18 matched controls. DTI analysis was performed in order to identify differences along frontal white matter structures including the corpus callosum (CC) and was complemented by atlas-based volumetry and planimetry.

RESULTS

Significantly reduced regional fractional anisotropy was observed for PSP patients versus controls and PSP versus PD patients, respectively, in frontal areas including the area II of the CC and bilaterally in the callosal radiation. The DTI findings correlated with frontal lobe volumes. These differences were not observed between PD patients and controls.

CONCLUSION

DTI identified a PSP-associated microstructural alteration pattern in the frontal lobes and in the CC area II including the corresponding bilateral callosal radiation tracts that could not be identified in both control samples, supporting the prominent PSP-associated frontal involvement as a potential neuroimaging marker.

Volumetric assessment of optic nerve sheath and hypophysis in idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

Idiopathic intracranial hypertension is a headache syndrome characterized by increased CSF pressure. Compression of the hypophysis and distension of the optic nerve sheath are reliable imaging signs. The purpose of the study was to validate, in patients with idiopathic intracranial hypertension, MR imaging-based volumetric measurements of the optic nerve sheath and hypophysis as an objective observation method for more accurate diagnosis and posttreatment follow-up.

MATERIALS AND METHODS

Twenty-three patients with idiopathic intracranial hypertension as well as age-, sex-, and body mass index-matched controls underwent volumetric measurements of the optic nerve, optic nerve sheath, and hypophysis on high-resolution T2-weighted MR images by using a 7-cm surface coil, followed by correlation with CSF opening pressures and clinical symptom scores of visual disturbances and headache.

RESULTS

Mean values of optic nerve sheath (341.86 ± 163.69 mm(3) versus 127.56 ± 53.17 mm(3), P < .001) and hypophysis volumes (554.59 ± 142.82 mm(3) versus 686.60 ± 137.84 mm(3), P < .05) differed significantly between healthy and diseased subjects. No significant differences between mean optic nerve volumes were observed. Receiver operating characteristic analysis showed optic nerve sheath volumes of >201.30 mm(3) (sensitivity, 86.96%; specificity, 91.30%) and hypophysis volumes of <611.21 mm(3) (sensitivity, 78.26%; specificity, 69.57%) to be indicative of idiopathic intracranial hypertension diagnosis. In patients with idiopathic intracranial hypertension, no correlations were found between optic nerve sheath and hypophysis volumes and CSF opening pressures or clinical scores of visual disturbances and headache.

CONCLUSIONS

Semiautomated volumetric measurement of optic nerve sheath and hypophysis has the potential to more accurately diagnose and follow patients with idiopathic intracranial hypertension.