Evaluating the Diagnostic Efficacy of 99mTc-Methionine Single-Photon Emission Computed Tomography-Computed Tomography: A Head-to-Head Comparison with 11C-Methionine Positron Emission Tomography-Magnetic Resonance Imaging in Glioma Patients

Background: Amino acid positron emission tomography (PET) imaging plays a significant role in the diagnosis of gliomas and in differentiating tumor recurrence from necrosis. In this study, the authors have evaluated the diagnostic efficacy of [99mTc]Tc-methionine single-photon emission computed tomography-computed tomography (SPECT-CT) in comparison with [11C]methionine PET-magnetic resonance imaging (MRI) in delineating tumors. Methods: Thirty-one (primary: 16 and postoperative: 15) patients of confirmed (either MRI or histopathological proven) glioma underwent both [99mTc]Tc-methionine SPECT-CT and [11C]methionine PET-MRI. A comparative analysis was performed between SPECT, PET, and MR images to calculate the concordance between the modalities and to evaluate the diagnostic efficacy of the [99mTc]Tc-methionine SPECT. Results: [99mTc]Tc-methionine SPECT showed comparable uptake in the tumor lesions in comparison to [11C]methionine PET. A significant and strong positive correlation was observed between the volume of tumor (Vt) in PET and Vt MR (p < 0.004). Likewise, a significant and strong positive correlation was found between Vt SPECT and Vt MR. [99mTc]-methionine has a sensitivity and specificity of 91% and 75%, respectively, compared with 82% and 100% for [11C]methionine in postoperative cases to differentiate the tumor recurrence from necrosis. The sensitivity and specificity of [99mTc]Tc-methionine was 92% and 100%, respectively, compared with 92% and 67% for [11C]methionine in primary tumors. Conclusion: [99mTc]Tc-methionine SPECT-CT is as equally good as [11C]methionine for diagnosing and differentiating it from necrosis especially in high-grade glioma.

Role of whole body MRI in paraneoplastic/autoimmune syndromes: An MRPET study to standardize protocols, pattern interpretation, and establish yield of MRI

Imaging a case of autoimmune encephalitis (AIE) can be challenging as the underlying tumor may be occult. The aim of this retrospective case-based study is to evaluate role of whole-body MRI/Positron emission tomography (PET) in workup of AIE. Standardizing the whole-body MRI/PET protocol, Cross modality yield with serology and magnetic resonance/PET (MR/PET) and finally highlight the advantage of hybrid MR/PET. We present the retrospective review data from January 2016 to December 2019 referred for whole body MR/PET with suspected AIE/Paraneoplastic syndrome, per consensus criteria, treated at a single tertiary center. Analysis is done group wise based on referral being for oncological, immunological or neuropsychiatric condition. Detailed results with sensitivity and specificity are presented in tabular format with case-based review in our series for protocols and advantages of MR/PET. Among total of 600 MR/PET cases, 227 were suspected of AIE/paraneoplastic syndrome and were referred for whole body imaging. Distribution of Group 1 Known oncology group (n = 10), Group 2 Non oncological systemic illness group (n = 174) and group 3 the primary neuropsychiatric illness (n = 43) with Group 2 being largest. The gender distribution was similar and mean age was 42 years. Seronegative cases (n = 130) were greater than seropositive cases (n = 97). Seropositivity was in the following order Autoimmune > Paraneoplastic > Myositis panel. Whole body MRPET yielded occult malignancy in 9% and imaging abnormality in 88% of cases. Whole body MR/PET has an important role in workup of AIE. Selection of the appropriate protocol is important, especially when history and physical examination are nonspecific.

Alzheimer's Disease Is Associated with Increased Network Assortativity: Evidence from Metabolic Connectivity

Introduction: Unraveling the network pathobiology in neurodegenerative disorders is a popular and promising field in research. We use a relatively newer network measure of assortativity in metabolic connectivity to understand network differences in patients with Alzheimer's Disease (AD), compared with those with mild cognitive impairment (MCI). Methods: Eighty-three demographically matched patients with dementia (56 AD and 27 MCI) who underwent positron emission tomography-magnetic resonance imaging (PET-MRI) study were recruited for this exploratory study. Global and nodal network measures obtained using the BRain Analysis using graPH theory toolbox were used to derive group-level differences (corrected p < 0.05). The methods were validated in age, and gender-matched 23 cognitively normal, 25 MCI, and 53 AD patients from the publicly available Alzheimer's Disease Neuroimaging Initiative (ADNI) data. Regions that revealed significant differences were correlated with the Addenbrooke's Cognitive Examination-III (ACE-III) scores. Results: Patients with AD revealed significantly increased global assortativity compared with the MCI group. In addition, they also revealed increased modularity and decreased participation coefficient. These findings were validated in the ADNI data. We also found that the regional standard uptake values of the right superior parietal and left superior temporal lobes were proportional to the ACE-III memory subdomain scores. Conclusion: Global errors associated with network assortativity are found in patients with AD, making the networks more regular and less resilient. Since the regional measures of these network errors were proportional to memory deficits, these measures could be useful in understanding the network pathobiology in AD.

Role of magnetoencephalography in predicting the epileptogenic zone and post-operative seizure outcome - A retrospective study

PURPOSE

Study assessed the role of MSI in predicting the post-operative seizure outcome.

METHODS

This retrospective study included patients who underwent MEG and epilepsy surgery and had a minimum 6 months of postoperative follow-up. Concordance of MEG cluster with post-surgical resection cavity was classified as follows Class I) Concordant and region-specific, Class II) Concordant and region non-specific, Class III) Concordant lateralization only and Class IV) Discordant lateralization. The relationship between MSI concordance and post-operative seizure outcome was assessed.

RESULTS

A total of 183 patients (M: F = 109:74) were included. The mean age at onset of seizures: 8.0 ± 6.4 years. The dipoles were frequent in 123(67.2 %). The primary cluster orientation was regular in 59 (32.2 %) and mixed in 124 (67.8 %) patients. Concordance between MEG and resection cavity: Class I - 124 (67.8 %), class II- 30 (16.4 %), class III- 23 (12.6 %), and class IV- 6 (3.3 %). The post-surgically mean duration of follow-up was 19.52 ± 11.27 months. At 6-month follow-up period, 144 (78.7 %) patients had complete seizure freedom out of which 106 (73.6 %) had class I concordance. Concordance of MEG with resection cavity was associated with a good outcome at 6 months (p = 0.001), 1 year (p = 0.001), 2 years (p = 0.0005) and 5 years (p = 0.04). MEG cluster characteristics had no association with seizure outcome except the strength of the cluster and outcome at 3 years (p = 0.02) follow-up.

CONCLUSION

The study supports that the complete resection of the MEG cluster had high chance of seizure-freedom and can be used as a complementary noninvasive presurgical evaluation tool.

Localisation of eloquent cortex using magnetoencephalography and its clinical implications

OBJECTIVES

This study aimed to localise the eloquent cortex and measure evoked field (EF) parameters using magnetoencephalography in patients with epilepsy and tumours near the eloquent cortex.

METHODS

A total of 41 patients (26 with drug-refractory epilepsy and 15 with tumours), with a mean age of 33 years, were recruited. Visual evoked field (VEF), auditory evoked field (AEF), sensory evoked field (SSEF), and motor-evoked field (MEF) latencies, amplitudes, and localisation were compared with those of a control population. Subgroup analyses were performed based on lobar involvement. Evoked Field parameters on the affected side were compared with those on the opposite side. The effect of distance from the lesion on nearby and distant evoked fields was evaluated.

RESULTS

AEF and VEF amplitudes and latencies were reduced bilaterally (p < 0.05). Amplitude in the ipsilateral SSEF was reduced by 29.27% and 2.16% in the AEF group compared to the contralateral side (p = 0.02). In patients with temporal lobe lesions, the SSEF amplitude was reduced bilaterally (p < 0.02), and latency was prolonged compared with controls. The MEF amplitude was reduced and latency was prolonged in patients with frontal lobe lesions (p = 0.01). EF displacement was 32%, 57%, 21%, and 16% for AEF, MEF, VEF, and SSEF respectively. Patients in the epilepsy group had distant EF abnormalities.

CONCLUSIONS

EF amplitude was reduced and latency was prolonged in the involved hemisphere. Distant EF amplitudes were more affected than latencies in epilepsy. Amplitude and distance from the lesion had negative correlation for all EF. EF changes indicated eloquent cortical displacement which may not be apparent on MRI.

A Rare Case of Asymmetric Progressive Supra Nuclear Palsy Diagnosed In vivo with Magnetic Resonance/Positron Emission Tomography

PSP and CBD are usually multi system sporadic disorders characterized by tau inclusions in neurons and glia. The clinical and neuroimaging features are different .However in some cases overlapping of features are noted. Here we present a case of a 65 years old female patient, presenting a 3 years history of insidious onset of asymmetric right upper and lower limb dystonia, followed by slowness, falls and injuries to the back, Parkinsonism, urinary incontinence and cognitive dysfunction and upward gaze palsy. MRI findings were suggestive of moderate cerebral and cerebellar atrophy with prominent ventricular system, reduced antero-posterior midline midbrain diameter, at the level of superior colliculus on axial imaging (morning glory sign was positive) on the left side. PET showed asymmetric hypo metabolism noted in the left superior and middle frontal gyrus, superior temporal and mid temporal gyrus in addition to striatum and thalamus, as well as midbrain, pons and right cerebellar hemisphere. Overall MR/PET was suggestive of unilateral PSP (left) and it corroborated with clinical history of unilateral dystonia and supranuclear gaze palsy. Based on MRI the differential considered was also CBD, but PET showed metabolic activity in the motor cortex. Additionally based on the hummingbird sign and morning glory sign a rare diagnosis of unilateral PSP could be made which also corroborated with the clinical picture.The case report emphasizes the utility of PETMRI simultaneously in situations like these to pick atypical variants or cases with overlapping pathology to reach a diagnosis with in vivo imaging methods.

Resting-State Functional MRI/PET Profile as a Potential Alternative to Tri-Modality EEG-MR/PET Imaging: An Exploratory Study in Drug-Refractory Epilepsy

Objective The study explores whether the epileptic networks associate with predetermined seizure onset zone (SOZ) identified from other modalities such as electroencephalogram/video electroencephalogram/structural MRI (EEG/VEEG/sMRI) and with the degree of resting-state functional MRI/positron emission tomography (RS-fMRI/PET) coupling. Here, we have analyzed the subgroup of patients who reported having a seizure on the day of scan as postictal cases and compared the findings with interictal cases (seizure-free interval).

Methods We performed independent component analysis (ICA) on RS-fMRI and 20 ICA were hand-labeled as large scale, noise, downstream, and epilepsy networks (Epinets) based on their profile in spatial, time series, and power spectrum domains. We had a total of 43 cases, with 4 cases in the postictal group (100%). Of 39 cases, 14 cases did not yield any Epinet and 25 cases (61%) were analyzed for the final study. The analysis was done patient-wise and correlated with predetermined SOZ.

Results The yield of finding Epinets on RS-fMRI is more during the postictal period than in the interictal period, although PET and RS-fMRI spatial, time series, and power spectral patterns were similar in both these subgroups. Overlaps between large-scale and downstream networks were noted, indicating that epilepsy propagation can involve large-scale cognition networks. Lateralization to SOZ was noted as blood oxygen level–dependent activation and correlated with sMRI/PET findings. Postoperative surgical failure cases showed residual Epinet profile.

Conclusion RS-fMRI may be a viable option for trimodality imaging to obtain simultaneous physiological information at the functional network and metabolic level.

Radiation Safety for Anesthesiologists and Other Personnel on Simultaneous PET/MRI: Possible Radiation Exposure from Patients While Performing Prolonged Duration Scans

This observational study was conducted owing to the challenges of the positron emission tomography/magnetic resonance imaging (PET/MRI) that requires longer duration scanning of radiopharmaceutical injected patient and added MRI environment. The aim of this study was to assess radiation dose at different distances from the patient and the radiation burden to anesthesiologist and other personnel in performing PET/MRI under general anesthesia or sedation. First, the pre- and postscan whole body radiation exposure (WBE) from the patient were obtained for 45 minutes (n = 109) after injection of the radiopharmaceutical. The WBE was obtained at specific distances from brain (10, 30, and 100 cm) and abdomen (10 and 30cm) of patients undergoing F18 fluorodeoxyglucose PET/MRI brain or whole body studies. Second, WBE of the anesthesiologist and other staff working was separately measured using pocket dosimeters during the whole procedure. In brain scans, the mean absorbed dose rates (ADR) of prescan (45 minutes) and postscan (45 minutes) were 44.4 and 31.1 μSv at 10 cm, 14.9 and 9.7μSv at 30 cm, and 3.5 and 2.8 μSv at 100 cm, respectively, from surface of head. Similarly, it was 54.8 and 30.3 μSv at 10 cm, 23 and 13.6μSv at 30 cm, respectively, from surface of abdomen. In WB scans, the mean ADR was higher than the brain scans. Anesthesiologist exposure overall was found to be 4.84 µSv/patient/scan (112 patients). The anesthesiologist receives a safe mean effective dose in PET/MRI scanning. With good training and adequate planning, it is possible to decrease the radiation exposure to all the concerned personnel including anesthesiologists.

Is Thalamic Lesion a Contributing Factor for Inappropriate Sexual Behavior in Older Adults with Cognitive Impairment?

Thalamus is a group of nuclei located deep inside the brain, well known for its sensory and cognitive functions. However, its role in the reward and behavior regulation is less explored. In this case series, we have presented four cases with inappropriate sexual behaviors (ISB) that are temporally related to thalamic infarction. We have discussed about the limbic part of thalamus and its extensive connections with other regions in regulating sexual behaviors. Although in all the four cases described there was underlying cognitive impairment that can itself increase the risk of ISB, there was potential contributing role of thalamic lesions.

Reflected image processing abnormalities in dementia - a case series and review

Dementia is a neurodegenerative condition with progressive decline in cognitive faculties and associated with different clinical phenomena. Mirror phenomenon in terms of both mirror agnosia and mirror image agnosia wherein there is difficulty in processing and perception of reflected images is not uncommonly seen, and understanding the same can contribute to early diagnosis and prognostication. We report two elderly women with Alzheimer's dementia and frontotemporal dementia, respectively, presenting with features of abnormalities in mirror image processing. The former had features of both mirror agnosia and mirror image agnosia and the latter had predominantly features of mirror image agnosia with preoccupation with her mirror image. Understanding neuroanatomical networks underlying these phenomena can help early identification and subtyping dementia. Clinically differentiating these phenomena from psychotic symptoms of dementia can help in initiating appropriate non-pharmacological measures rather than resorting to use of psychotropics, the use of which may be counterproductive.

Can High b Value Diffusion Be a Surrogate Marker for PET-A MR/PET Study in Neurooncology Set Up

Purpose: Hybrid whole-body magnetic resonance/positron emission tomography (MR/PET) systems are new diagnostic tools enabling the simultaneous acquisition of morphologic and multiparametric functional data, which allow for a diversified characterization of oncological diseases. This study aimed to compare the diagnostic ability of MRI with the diffusion-weighted image (DWI), and simultaneous integrated positron emission tomography MR/PET to detect malignant lesions and elucidate the utility and limitations of these imaging modalities in preoperative and postoperative follow up in cancer patients. Material and Methods: A total of 45 patients undergoing simultaneous MR/PET for CNS ICSOL in our institution between January 2016 and July 2020 were considered in this study. Post-processing was done in Siemens syngo software to generate a b2000 image. This image was then inverted to grayscale and compared with the NAC image of PET. Results: The lesion-based sensitivity, specificity, positive predictive value, and negative predictive value for DWI were 92.3, 83.3, 97.3, and 62.5%, respectively (at 95% CI and p was 0.000). The lesion-based sensitivity, specificity, positive predictive value, and negative predictive value for PET were 97.4, 71.4, 94.9, and 83.3%, respectively (at 95% CI and p was 0.000). The lesion-based sensitivity and specificity of DWI were comparable with those of PET. Conclusions: Although DWI and FDG-PET reflect different tissue properties, there is an association between the measures of both methods in CNS tumors probably because of the coupling of cellularity with tumor metabolism as seen on FDG and other PET tracers. Our study shows that DWI acts as a surrogate biomarker for FDG PET and other tracers in tumors. The method of DWI image generation is simple, radiation-free, and cost-effective in a clinical setup. The simultaneous DWI-PET study provides evidence and confirms the role of DWI in surveillance imaging of tumors.

Magnetic source imaging in presurgical evaluation of paediatric focal drug-resistant epilepsy and its predictive value of surgical outcome in lesional cases: A single-centre experience from South India

OBJECTIVE

This study aims to evaluate the utility of magnetoencephalography in presurgical planning and in predicting post-surgical seizure outcome.

METHODS

This study included a cohort of 231 children (1-18 years) with focal drug-resistant epilepsy who underwent MEG as a part of their presurgical workup. Characteristics of MEG observations were described in all children. The concordance and agreement of Magnetic Source Imaging (MSI) of interictal discharges (IED) was estimated with either of the 3 subgroups - MRI lesion; presumed epileptogenic zone (EZ); or resection cavity. In operated children group, MEG dipole characteristics between good and poor outcome groups were assessed.

RESULTS

A total of 153 cases (66.2%) showed frequent IEDs (60 spikes/60 min). Of the 173 cases where MSI showed clusters (74.9%), 151 had lesions and 22 were non-lesional. amongst patients with lesional epilepsy and MEG clusters, class I concordance (MEG localization either completely included or overlapped at least 60% with the MRI lesion) was seen in 60.92% with a Cohen's kappa of 0.608. In non-lesional epilepsy, class I concordance of MEG with presumed EZ was found in (81.81%) with an agreement of 0.317. Fifty-three children underwent surgery of whom 39 (73.58%) showed a good outcome (Engel I). In operated children, concordance between MEG focus and resection cavity was observed in 23 (58.97%) with good outcome and in 12 (86.72%) with poor outcome with no significant difference (p>0.05). However, MEG cluster regular organization and clusterectomy are associated with good seizure outcome postoperatively (p< 0.05). Presence of scatters were associated with poor outcome (p<0.05) in children with focal cortical dysplasia.

CONCLUSIONS

MEG provides useful information that can serve as a biomarker for prognosticating the surgical outcome in paediatric epilepsy. Cluster removal and regular cluster organization shows predictive power in post-surgical prognostication in children and the presence of scatters predicts poor outcome in children with focal cortical dysplasia.

Hydrocephalic Dementia: Revisited with Multimodality Imaging and toward a Unified Imaging Approach

Objective  Overlap of normal pressure hydrocephalus (NPH) and pathology proven cases of dementia is known. The objective of this paper is to correlate both the clinical and multimodality imaging findings in patients with imaging diagnosis NPH and give a hypothesis for association of clinical findings.

Methods  This is a retrospective observational analysis of 13 cases patients who were referred to molecular imaging center for imaging in 2016 to 2019, and they were divided into four groups based on structural imaging findings. Group 1 had magnetic resonance imaging (MRI) findings of diffuse effacement of sulcal spaces (DESH) and flow void, whereas Group 4 had none of these two. Group 3 had MRI findings of DESH but no flow void, and Group 2 had flow void but no DESH. Clinical presentation, MRI-PET findings of four groups are assessed.

Results  Groups with presence of flow void showed hypometabolism in the medial frontal and medial temporal lobe. Groups with presence of DESH has effacement of parietal sulci showed parietal hypo metabolism with clinical presentation AD/mixed dementia and absence of parietal effacement showed FTD-like presentation. Groups without flow void or DESH showed only mild medial temporal hypometabolism and presented with classical signs of NPH. ASL perfusion changes are in correlation with metabolism on positron emission tomography (PET)-MRI.

Conclusion  This study has led us to hypothesize the lack of outflow of brain protein and their deposition in parenchyma based on pressure gradient would be easier explanation to go with cluster of findings. MR-PET and other investigations each had different specificity and sensitivity and different pattern of presentation.

Abnormal structural connectivity in progressive supranuclear palsy-Richardson syndrome

OBJECTIVES

Progressive supranuclear palsy-Richardson syndrome (PSP-RS) is characterized by symmetrical parkinsonism with postural instability and frontal dysfunction. This study aims to use the whole brain structural connectome (SC) to gain insights into the underlying disconnectivity which may be implicated in the clinical features of PSP-RS.

METHODS

Sixteen patients of PSP-RS and 12 healthy controls were recruited. Disease severity was quantified using PSP rating scale (PSPRS), and mini-mental scale was applied to evaluate cognition. Thirty-two direction diffusion MRIs were acquired and used to compute the structural connectome of the whole brain using deterministic fiber tracking. Group analyses were performed at the edge-wise, nodal, and global levels. Age and gender were used as nuisance covariates for all the subsequent analyses, and FDR correction was applied.

RESULTS

Network-based statistics revealed a 34-edge network with significantly abnormal edge-wise connectivity in the patient group. Of these, 25 edges were cortical connections, of which 68% were frontal connections. Abnormal deep gray matter connections were predominantly comprised of connections between structures of the basal ganglia. The characteristic path length of the SC was lower in PSP-RS, and nodal analysis revealed abnormal degree, strength, local efficiency, betweenness centrality, and participation coefficient in several nodes.

CONCLUSIONS

Significant alterations in the structural connectivity of the whole brain connectome were observed in PSP-RS. The higher degree of abnormality observed in nodes belonging to the frontal lobe and basal ganglia substantiates the predominant frontal dysfunction and parkinsonism observed in PSP-RS. The findings of this study support the concept that PSP-RS may be a network-based disorder.

Incremental Utility of Tc-99m Glucohepatonate Single-Photon Emission Computed Tomography over 18F-Flourodeoxyglucose Positron Emission Tomography in Diagnosis of Brain Tumor Recurrence - Old is Gold

Detection of recurrence of a brain tumor after treatment is one of the most important and challenging diagnostic problems in neuro-oncological practice. In spite of technical advances in imaging modalities, sometimes, certain clinical presentations and manifestations can lead to a diagnostic dilemma even with the best of the technical know-how. We present a case of recurrence of anaplastic oligoastrocytoma (World Health Organization Grade III), where the patient's initial clinical presentation and the F-18 flourodeoxyglucose positron emission tomography (PET) magnetic resonance imaging findings were suggestive of stroke-like migraine attacks after radiation therapy syndrome. Due to a seizure episode before PET image acquisition, intense gyral uptake was noted in the left parietal lobe which made it difficult to ascertain the presence of a tumor recurrence. However, Tc-99m glucohepatonate single-photon emission computed tomography done after 1 week revealed radiotracer uptake within the site corresponding to the primary tumor, and a diagnosis of recurrence was made.

Posterior Quadrant Disconnection for Childhood Onset Sub-Hemispheric Posterior Head Region Epilepsy: Indications in an Indian Cohort and Outcome

BACKGROUND

Posterior quadrant disconnection (PQD) is an under-utilized surgical technique in the management of refractory epilepsy. There is a dearth of data pertinent to post-PQD seizure outcomes.

METHODS

This retrospective study analyzed patients with drug-resistant childhood-onset epilepsy who underwent PQD at our center from 2009 to 2018. The clinical, imaging, and electrophysiological data were reviewed. The seizure outcome was noted from the latest follow-up in all patients.

RESULTS

Fifteen patients underwent PQD, with a mean age at onset of epilepsy of 3.3 ± 4.6 years. All patients had seizure onset in childhood with focal onset of seizures, and in addition, 5 had multiple seizure types. All cases underwent presurgical workup with MRI, video-EEG, psychometry, while PET/MEG was done if required. Engel Ia and ILAE I outcomes were considered to be favorable. The histology of the specimen showed 9 patients (60%) had gliosis, 4 (26.7%) had focal cortical dysplasia (FCD), while 1 patient had nodular heterotopia and another had polymicrogyria-pachygyria complex. Postoperative follow-up was available in 14 cases. One patient was lost to follow-up. Mean follow-up duration for the cohort was 45 + 24 months. At last, follow-up (n = 14), 66.7% (10 cases) had favorable outcome (Engel Ia). At the end of 1-year follow-up, up to 73% (n = 11) of the patients were seizure-free. Four patients developed transient hemiparesis after surgery which improved completely by 3-6 months.

CONCLUSIONS

Gliosis was more common etiology requiring PQD in our series than Western series, where FCD was more common. PQD is a safe and effective surgical modality in childhood-onset epilepsy with posterior head region epileptogenic focus.

Multilingualism and semantic dementia - A case report

Language is a vital component of cognition essential for communication. Proficiency in more than one language has become a norm for many in the current era of globalisation. In neurogenerative conditions decline in language ability leads to early dependency. Studies have reported higher cognitive reserve in multilingual compared to monolinguals. Determining preserved language skills in a patient presenting with cognitive concerns helps in understanding the cognitive reserve, early signs of dementia, the extent of impairment due to language deficits and planning for cognitive stimulation. In this article, we have described an elderly woman with multilinguistic abilities who presented with semantic dementia.

Shape Profile of Corpus Callosum As a Signature to Phenotype Different Dementia

Background  Phenotyping dementia is always a complex task for a clinician. There is a need for more practical biomarkers to aid clinicians. Objective  The aim of the study is to investigate the shape profile of corpus callosum (CC) in different phenotypes of dementia. Materials and Methods  Our study included patients who underwent neuroimaging in our facility as a part of clinical evaluation for dementia referred from Geriatric Clinic (2017-2018). We have analyzed the shape of CC and interpreted the finding using a seven-segment division. Results  The sample included MPRAGE images of Alzheimer' dementia (AD) ( n = 24), posterior cortical atrophy- Alzheimer' dementia (PCA-AD) ( n = 7), behavioral variant of frontotemporal dementia (Bv-FTD) ( n = 17), semantic variant frontotemporal dementia (Sv-FTD) ( n = 11), progressive nonfluent aphasia (PNFA) ( n = 4), Parkinson's disease dementia (PDD) ( n = 5), diffuse Lewy body dementia ( n = 7), progressive supranuclear palsy (PSP) ( n = 3), and corticobasal degeneration (CBD) ( n = 3). We found in posterior dementias such as AD and PCA-AD that there was predominant atrophy of splenium of CC. In Bv-FTD, the genu and anterior half of the body of CC was atrophied, whereas in PNFA, PSP, PDD, and CBD there was atrophy of the body of CC giving a dumbbell like profile. Conclusion  Our study findings were in agreement with the anatomical cortical regions involved in different phenotypes of dementia. Our preliminary study highlighted potential usefulness of CC in the clinical setting for phenotyping dementia in addition to clinical history and robust biomarkers.

Psychotic symptoms in frontotemporal dementia with right frontotemporal atrophy

Frontotemporal dementia (FTD) often mimics a primary psychiatric disorder. A subset of patients with FTD presents with psychotic symptoms either during the course of illness and less often prior to the onset of cognitive decline. This leads to delay in diagnosis and inappropriate exposure to high dose antipsychotic medication. Among the predictors for psychotic symptoms, the involvement of specific anatomical regions such as right frontotemporal lobe has been reported in few studies. We report a case of FTD presenting as late-onset psychosis with right frontotemporal atrophy.

Clinical utility of 18F-FDG-PET/MRI brain in dementia: Preliminary experience from a geriatric clinic in South India

BACKGROUND

¹⁸F-FDG-PET is a potential sensitive biomarker indicating neuronal damage. ¹⁸F-FDG-PET has proven to be useful in subtyping dementia. Utility of simultaneous ¹⁸F-FDG-PET and MRI-brain was investigated in the evaluation of dementia in this facility.

METHOD

All case notes of patients who underwent 18 F-FDG-PET/MRI brain attending the Geriatric Clinic for 18 month period between January 2017 and June 2018 were retrospectively reviewed. Their socio-demographic details, MRI-brain finding, ¹⁸F- FDG-PET findings and comorbid illnesses were studied.

RESULTS

A total of 21 patients underwent ¹⁸F-FDG-PET/MRI brain during study period. The mean age was 61.23, SD-8.6 years (range: 36-75 years). Among them 5 (23.8%) had Mild Cognitive Impairment (MCI) and 16 (76.2%) had dementia. Majority of patients had early onset cognitive decline (76.2%). Based on the pattern of hypometabolism, the MCI group had one patient each indicative of AD, Semantic-Frontotemporal dementia (Semantic-FTD), mixed Alzheimer's dementia (AD + FTD) and two patients had patterns suggestive of Behaviour Variant of FTD (Bv-FTD). In Dementia group the pattern of hypometabolism was indicative of Bv-FTD in seven, AD in four, Posterior Cortical Atrophy (PCA) in one, Semantic-FTD in one, Mixed AD-Diffuse Lewy Body Dementia (DLBD) in one and no specific pattern in two patients. MRI and 18 F-FDG-PET brain had concordance in 9 (56.26%) patients.

DISCUSSION

¹⁸F-FDG-PET/MRI helped in overall clinical diagnosis and management in 19 (90.5%) patients especially with early onset dementia. In MCI group it indicated underlying aetiology and in dementia group it helped in subtyping.

CONCLUSION

The study supports the role of ¹⁸F-FDG-PET/MRI as an emerging diagnostic tool to assist in dementia evaluation in India.

Tumefactive Demyelination versus Primary Central Nervous System Lymphoma on 18F-Fluorodeoxyglucose Positron Emission Tomography Magnetic Resonance Imaging: A Twist in the Tale

Demyelinating lesions of the central nervous system (CNS) are classically known to be hypometabolic on ¹⁸F-Flurodeoxyglucose Positron Emission Tomography (¹⁸F-FDG PET). However, demyelinating lesions may show increased tracer uptake on ¹⁸F-FDG PET and can radiologically mimic neoplasm. Delayed tracer uptake on FDG PET is one of the diagnostic hallmarks of primary CNS lymphoma (PCNSL). Here, we present two cases in which the brain lesions showed increased FDG uptake on delayed integrated PET Magnetic Resonance Imaging (MRI), which were pathologically proven as CNS demyelination. Such demyelinating lesions may also act as "sentinel lesions" and potential harbinger of PCNSL on follow-up.

Solving the Riddle of "Idiopathic" in Idiopathic Intracranial Hypertension and Normal Pressure Hydrocephalus: An Imaging Study of the Possible Mechanisms - Monro-Kellie 3.0

Background

Idiopathic intracranial hypertension (IIH) and normal pressure hydrocephalus (NPH) represent a cluster of typical clinical and imaging findings, with no evident etiological cause noted. In this study, we have proposed a model for IIH and NPH called Monroe-Kellie 3.0 (MK 3.0). IIH and NPH may be entities which represent opposite sides of the same coin with venous system and cerebrospinal fluid (CSF) as core drivers for both these entities.

Materials and Methods

IIH and NPH volume data were collected, voxel-based morphometry analysis was performed without normalization, and the distribution of the individual volumes of gray matter, white matter, and CSF was statistically analyzed. Visual morphometry analyses of segmented data were performed, and the findings in routine magnetic resonance imaging (MRI) were noted to build a model for IIH and NPH.

Results

In IIH and NPH when the volumes were compared with controls, the distribution was similar. Furthermore, the morphometric changes noted in the MRI and segmented volume data were analyzed and the results were suggestive of changes in elastic property of brain causing a remodeling of brain shape and resulting in minor brain shift in the skull vault, and the resulting passive displacement of CSF which has been termed as MK 3.0.

Conclusion

This model helps to put the clinical and imaging findings and complications of treatment in single perspective.

Precuneus and psychiatric manifestations: Novel neurobiological formulations through lesion based connectivity mapping of psychopathology

Lesion-based investigations of psychopathology have preceded contemporary network-neuroscience initiatives. However, brain-lesions detected in routine psychiatric practice are often considered incidental and therefore ignored. Here, we illustrate a strategy to combine individual subject-level lesion information with open-source normative functional-connectomics data to make putative, neuroscience-informed symptom interpretation. Specifically, we report a patient with left precuneus granulomatous lesion and seizures followed by two distinct symptoms - kinetopsia and delusions of nihilism and guilt - which had a differential treatment response. The lesion-based brain-mapping approach could identify correlated (default-mode) and anti-correlated (temporo-parieto-occipital) networks, which enabled a neurobiological formulation of these diverse clinical manifestations.

Posterior cortical atrophy variant of Alzheimer's dementia-A case report

Alzheimer's dementia (AD) is the commonest type of dementia presenting with initial episodic memory decline followed by involvement of other cognitive domains. Posterior cortical atrophy (PCA) is one of the variants of Alzheimer's dementia (AD) characterized by the atypical presentation of relatively persevered memory in the initial stage. PCA is an uncommon early onset dementia affecting adults between 50 and 65 years. It presents predominantly with visuo-spatial and visuo-perceptual deficits. PCA is a phenotype with varied etiology most common being Alzheimer's disease. The complex and atypical presentation with preserved memory and insight in patients with PCA poses challenge to clinicians in diagnosing at initial stages. There is also paucity of research on prevalence, course, prognosis and management of PCA. In this article we describe a middle aged gentlemen presenting with clinical features suggestive of PCA. We also discussed relevant literature.

Role of Corpus Callosum Volumetry in Differentiating the Subtypes of Progressive Supranuclear Palsy and Early Parkinson's Disease

Background and Objective

Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disorder. Classic PSP or Richardson-Steele phenotype (PSP-RS) and parkinsonian phenotype (PSP-P) are the common subtypes of PSP. At the early stage, differentiating the subtypes of PSP as well as differentiating PSP from other parkinsonian disorders, especially Parkinson's disease (PD) is challenging. Microstructural abnormalities of corpus callosum (CC) have been reported both in PSP and PD. The objective of this study was to compare the volumes of various segments of CC between patients with PSP-P, PSP-RS, and early PD.

Methodology

This study included 32 patients with PSP (RS: 18, P: 14), 20 patients with early PD, and 25 controls. All subjects underwent 3-Tesla MRI. An automated surface-based analysis package (FreeSurfer) was used to divide CC into five segments: anterior (CC1), midanterior (CC2), central (CC3), midposterior (CC4), and posterior (CC5). Volumes of these segments were compared among the four groups.

Results

The PSP-RS group had significantly lower CC volume in all segments except in CC1 and CC5, whereas the volumes of the five segments of CC were comparable among PSP-P, PD and controls. The PSP-RS group had lower CC3 volume compared to the PSP-P group, and the PSP-RS group had lower volume of both CC2 and CC3 compared to the PD group.

Conclusions

The lower volume of the central segment of CC (CC3) might help in differentiating PSP-RS from PSP-P. There is no significant difference in the pattern of CC atrophy in PSP-P and early PD. Studies with higher sample sizes are warranted to confirm the results of our study.

Temporal Dynamics of the Default Mode Network Characterize Meditation-Induced Alterations in Consciousness

Current research suggests that human consciousness is associated with complex, synchronous interactions between multiple cortical networks. In particular, the default mode network (DMN) of the resting brain is thought to be altered by changes in consciousness, including the meditative state. However, it remains unclear how meditation alters the fast and ever-changing dynamics of brain activity within this network. Here we addressed this question using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to compare the spatial extents and temporal dynamics of the DMN during rest and meditation. Using fMRI, we identified key reductions in the posterior cingulate hub of the DMN, along with increases in right frontal and left temporal areas, in experienced meditators during rest and during meditation, in comparison to healthy controls (HCs). We employed the simultaneously recorded EEG data to identify the topographical microstate corresponding to activation of the DMN. Analysis of the temporal dynamics of this microstate revealed that the average duration and frequency of occurrence of DMN microstate was higher in meditators compared to HCs. Both these temporal parameters increased during meditation, reflecting the state effect of meditation. In particular, we found that the alteration in the duration of the DMN microstate when meditators entered the meditative state correlated negatively with their years of meditation experience. This reflected a trait effect of meditation, highlighting its role in producing durable changes in temporal dynamics of the DMN. Taken together, these findings shed new light on short and long-term consequences of meditation practice on this key brain network.

The Relevance of Interictal Bold Changes to Lateralize Seizure Focus Using Simultaneous EEG-fMRI

Background and Purpose:

The main challenge in assessing patients with epilepsy is the localization of neuronal networks involved in seizure generation and the lateralization of seizure onset. Electro encephalogram-functional magnetic resonance imaging (EEG-fMRI) is a noninvasive multimodal imaging technique for epilepsies where the data is acquired based on the interictal epileptiform discharges (IED). Since this is a new technique, the specificity for lateralizing epileptic focus is yet to be established. The peak blood oxygen level dependent (BOLD) signal in an interictal recording is known to correlate with seizure onset focus. In this study we are proposing a simple and practical method without the need for high end post processing techniques of fmri data. The peak BOLD signal derived from EEG-fMRI aids to lateralise seizure focus in a given cerebral lobe (region of interest, ROI). This is a very useful tool in a clinical setting on a given individual clinical case, when other modalities may be conflicting or inconclusive.

Methods:

We analyzed simultaneous EEG-fMRI of 10 different types of refractory epilepsy. The lateralization index was calculated from the statistical significant clusters obtained between the different ROI and results were validated with other modalities.

Results:

Lateralization of seizure focus corroborated well in temporal and extratemporal lobe epilepsy, reflex epilepsy and lesional epilepsy. The only drawback of EEG-fMRI in our study was if insignificant BOLD changes were associated with the given IED.

Conclusions:

EEG-fMRI can be helpful additional tool in the pre-surgical work-up of refractory epilepsy particularly when lateralization with other modalities is conflicting or inconclusive.

Imaging characteristics of supratentorial ependymomas: Study on a large single institutional cohort with histopathological correlation

Background:

Supratentorial ependymoma (STE) is a tumor whose unique clinical and imaging characteristics have not been studied. Histopathologically, they resemble ependymoma elsewhere. We retrospectively reviewed the imaging findings with clinicopathological correlation in a large number of patients with STE to identify these characteristics.

Materials and Methods:

Computed tomography (CT) magnetic resonance images (MRI), pathology reports, and clinical information from 41 patients with pathology-confirmed STE from a single institution were retrospectively reviewed. CT and MRI findings including location, size, signal intensity, hemorrhage, and enhancement pattern were tabulated and described separately in intraventricular and intraparenchymal forms.

Results:

STE was more common in pediatric age group and intraparenchymal was more common than intraventricular form. The most common presentation was features of raised intracranial tension. There were equal numbers of Grade II and Grade III tumors. The imaging characteristics in adult and pediatric age group were similar. The tumor was large and had both solid and cystic components. Advanced imaging such as diffusion, perfusion, and spectroscopy were suggestive of high-grade tumor. Only differentiating factor between Grade II and Grade III was the presence of calcification. 1234 rule and periwinkle sign which we have described in this article may help characterize this tumor on imaging.

Conclusion:

This series expands the clinical and imaging spectrum of STE and identifies characteristics that should suggest consideration of this uncommon diagnosis.

Cerebral tubercular thrombophlebitis presenting as venous infarct: Magnetic resonance imaging and pathologic correlation

Central nervous system involvement by tuberculosis to produce basal meningitis, hydrocephalus, arteritis and infarcts is well-known, the brunt of the pathology being borne by the arterial vasculature to produce neurological sequelae. However, tuberculous thrombophlebitis causing venous infarction is exceedingly rare. We present imaging and pathological features of two autopsy proven cases of tuberculous thrombophlebitis with venous infarcts involving superficial venous system in one and deep venous system in the other. This is the first study presenting radiopathologic correlation of this rare complication. Tuberculous thrombophlebitis should be suspected if basal exudates and multiple white matter T2 hyperintensities are seen on neuroimaging and the imaging protocol should include both magnetic resonance arteriogram and venogram.