PET Imaging in Dementia: Mini-Review and Canadian Perspective for Clinical Use.

PET imaging is increasingly recognized as an important diagnostic tool to investigate patients with cognitive disturbances of possible neurodegenerative origin. PET with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), assessing glucose metabolism, provides a measure of neurodegeneration and allows a precise differential diagnosis among the most common neurodegenerative diseases, such as Alzheimer's disease, frontotemporal dementia or dementia with Lewy bodies. PET tracers specific for the pathological deposits characteristic of different neurodegenerative processes, namely amyloid and tau deposits typical of Alzheimer's Disease, allow the visualization of these aggregates in vivo. [18F]FDG and amyloid PET imaging have reached a high level of clinical validity and are since 2022 investigations that can be offered to patients in standard clinical care in most of Canada.This article will briefly review and summarize the current knowledge on these diagnostic tools, their integration into diagnostic algorithms as well as perspectives for future developments.

Dosimetry of [18F]TRACK, the first PET tracer for imaging of TrkB/C receptors in humans.

BACKGROUND: Reduced expression or impaired signalling of tropomyosin receptor kinases (Trk receptors) are found in a vast spectrum of CNS disorders. [18F]TRACK is the first PET radioligand for TrkB/C with proven in vivo brain penetration and on-target specific signal. Here we report dosimetry data for [18F]TRACK in healthy humans. 6 healthy participants (age 22-61 y, 3 female) were scanned on a General Electric Discovery PET/CT 690 scanner. [18F]TRACK was synthesized with high molar activities (Am = 250 ± 75 GBq/µmol), and a dynamic series of 12 whole-body scans were acquired after injection of 129 to 147 MBq of the tracer. Images were reconstructed with standard corrections using the manufacturer's OSEM algorithm. Tracer concentration time-activity curves (TACs) were obtained using CT-derived volumes-of-interest. Organ-specific doses and the total effective dose were estimated using the Committee on Medical Internal Radiation Dose equation for adults and tabulated Source tissue values (S values). RESULTS: Average organ absorbed dose was highest for liver and gall bladder with 6.1E-2 (± 1.06E-2) mGy/MBq and 4.6 (± 1.18E-2) mGy/MBq, respectively. Total detriment weighted effective dose EDW was 1.63E-2 ± 1.68E-3 mSv/MBq. Organ-specific TACs indicated predominantly hepatic tracer elimination. CONCLUSION: Total and organ-specific effective doses for [18F]TRACK are low and the dosimetry profile is similar to other 18F-labelled radio tracers currently used in clinical settings.

Simultaneous PET/MRI: The future gold standard for characterizing motor neuron disease-A clinico-radiological and neuroscientific perspective.

Neuroimaging assessment of motor neuron disease has turned into a cornerstone of its clinical workup. Amyotrophic lateral sclerosis (ALS), as a paradigmatic motor neuron disease, has been extensively studied by advanced neuroimaging methods, including molecular imaging by MRI and PET, furthering finer and more specific details of the cascade of ALS neurodegeneration and symptoms, facilitated by multicentric studies implementing novel methodologies. With an increase in multimodal neuroimaging data on ALS and an exponential improvement in neuroimaging technology, the need for harmonization of protocols and integration of their respective findings into a consistent model becomes mandatory. Integration of multimodal data into a model of a continuing cascade of functional loss also calls for the best attempt to correlate the different molecular imaging measurements as performed at the shortest inter-modality time intervals possible. As outlined in this perspective article, simultaneous PET/MRI, nowadays available at many neuroimaging research sites, offers the perspective of a one-stop shop for reproducible imaging biomarkers on neuronal damage and has the potential to become the new gold standard for characterizing motor neuron disease from the clinico-radiological and neuroscientific perspectives.

Rapid Standardized CT-Based Method to Determine Lean Body Mass SUV for PET-A Significant Improvement Over Prediction Equations.

In 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) studies, maximum standardized uptake value (SUVmax) is the parameter commonly used to provide a measurement of the metabolic activity of a tumor. SUV normalized by body mass is affected by the proportions of body fat and lean tissue, which present high variability in patients with cancer. SUV corrected by lean body mass (LBM), denoted as SUL, is recommended to provide more accurate, consistent, and reproducible SUV results; however, LBM is frequently estimated rather than measured. Given the increasing importance of a quantitative PET parameter, especially when comparing PET studies over time to evaluate disease response clinically, and its use in oncological clinical trials, we set out to evaluate the commonly used equations originally derived by James (1976) and Janmahasatian et al. (2005) against computerized tomography (CT)-derived measures of LBM. Methods: Whole-body 18F-FDG PET images of 195 adult patients with cancer were analyzed retrospectively. Representative liver SUVmean was normalized by total body mass. SUL was calculated using a quantitative determination of LBM based on the CT component of the PET/CT study (LBMCT) and compared against the equation-estimated SUL. Bland and Altman plots were generated for SUV-SUL differences. Results: This consecutive sample of patients undergoing usual care (men, n = 96; women, n = 99) varied in body mass (38-127 kg) and in Body Mass Index (BMI) (14.7-47.2 kg/m2). LBMCT weakly correlated with body mass (men, r2 = 0.32; women, r2 = 0.22), and thus SUV and SULCT were also weakly correlated (men, r2 = 0.24; women, r2 = 0.11). Equations proved inadequate for the assessment of LBM. LBM estimated by James' equation showed a mean bias (overestimation of LBM compared with LBMCT) in men (+6.13 kg; 95% CI 4.61-7.65) and in women (+6.32 kg; 95% CI 5.26-7.39). Janmahasatian's equation provided similarly poor performance. Conclusions: CT-based LBM determinations incorporate the patient's current body composition at the time of a PET/CT study, and the information garnered can provide care teams with information with which to more accurately determine FDG uptake values, allowing comparability over multiple scans and treatment courses and will provide a robust basis for the use of PET Response Criteria in Solid Tumors (PERCIST) in clinical trials.

First In Vivo and Phantom Imaging of Cyclotron-Produced 133La as a Theranostic Radionuclide for 225Ac and 135La.

Theranostic isotope pairs have gained recent clinical interest because they can be labeled to the same tracer and applied for diagnostic and therapeutic purposes. The goals of this study were to investigate cyclotron production of clinically relevant 133La activities using natural and isotopically enriched barium target material, compare fundamental PET phantom imaging characteristics of 133La with those of common PET radionuclides, and demonstrate in vivo preclinical PET tumor imaging using 133La-PSMA-I&T. Methods:133La was produced on a 24-MeV cyclotron using an aluminum-indium sealed target with 150-200 mg of isotopically enriched 135BaCO3, natBaCO3, and natBa metal. A synthesis unit performed barium/lanthanum separation. DOTA, PSMA-I&T, and macropa were radiolabeled with 133La. Derenzo and National Electrical Manufacturers Association phantom imaging was performed with 133La, 132La, and 89Zr and compared with 18F, 68Ga, 44Sc, and 64Cu. In vivo preclinical imaging was performed with 133La-PSMA-I&T on LNCaP tumor-bearing mice. Results: Proton irradiations for 100 µA·min at 23.3 MeV yielded 214 ± 7 MBq of 133La and 28 ± 1 MBq of 135La using 135BaCO3, 59 ± 2 MBq of 133La and 35 ± 1 MBq of 135La using natBaCO3, and 81 ± 3 MBq of 133La and 48 ± 1 MBq of 135La using natBa metal. At 11.9 MeV, 135La yields were 81 ± 2 MBq, 6.8 ± 0.4 MBq, and 9.9 ± 0.5 MBq for 135BaCO3, natBaCO3, and natBa metal. BaCO3 target material recovery was 95.4% ± 1.7%. National Electrical Manufacturers Association and Derenzo phantom imaging demonstrated that 133La PET spatial resolution and scanner recovery coefficients were superior to those of 68Ga and 132La and comparable to those of 89Zr. The apparent molar activity was 130 ± 15 GBq/µmol with DOTA, 73 ± 18 GBq/µmol with PSMA-I&T, and 206 ± 31 GBq/µmol with macropa. Preclinical PET imaging with 133La-PSMA-I&T provided high-resolution tumor visualization with an SUV of 0.97 ± 0.17 at 60 min. Conclusion: With high-yield 133La cyclotron production, recovery of BaCO3 target material, and fundamental imaging characteristics superior to those of 68Ga and 132La, 133La represents a promising radiometal candidate to provide high-resolution PET imaging as a PET/α-therapy theranostic pair with 225Ac or as a PET/Auger electron therapy theranostic pair with 135La.

Clinicoanatomical substrates of selfish behaviour in amyotrophic lateral sclerosis - An observational cohort study.

OBJECTIVE: ALS primarily affects motor functions, but cognitive functions, including social understanding, may also be impaired. Von Economo neurons (VENs) are part of the neuronal substrate of social understanding and these cells are histopathologically altered in ALS. We investigated whether activity in areas including VENs is associated with an impairment of cognitive tasks that mirror social functioning. METHODS: In this observational prospective study, ALS patients (N = 26) were tested for cognitive behavioural function, encompassing different aspects of empathetic understanding (interpersonal reactivity index, IRI), social behaviour (ultimatum game), recognition of faux-pas situations, and general cognitive functioning (Edinburgh Cognitive and Behavioural ALS Screen, ECAS). For in vivo pathological staging according to Braak, DTI-MRI was performed to determine those ALS patients with expected pathological involvement of VENs (B ALS stages 3 + 4) compared to those without (B ALS stages 1 + 2). Expected hypometabolism of cerebral areas was determined with 18F-FDG PET in N = 20 ALS patients and compared to N = 20 matched healthy controls. Volume of interest analysis was performed in the anterior cingulate cortex (ACC) and the anterior insular cortex (AIC), which contain high numbers of VENs. RESULTS: Compared to those without expected pathological involvement of VENs (B/B ALS stages 1 + 2), ALS patients with anticipated pathological involvement of VENs (B/B ALS stages 3 + 4) presented with significantly reduced fantasy to understand the mindset of others (IRI) and, social behaviour was more selfish (ultimatum game) despite the fact that cognitive understanding of socially inappropriate behaviour of others (faux-pas) was unimpaired. 18F-FDG-PET showed hypometabolism in ACC and AIC in ALS patients with anticipated pathological involvement of VENs compared to those without and this was significantly correlated to cognitive-behavioral functions in certain tasks. CONCLUSION: Here, we present evidence of altered social behaviour in ALS patients associated with regional 18FDG-PET hypometabolism in areas with a high density of VENs, thereby suggesting a possible causal association.

FOXM1 Inhibitors as Potential Diagnostic Agents: First Generation of a PET Probe Targeting FOXM1 To Detect Triple-Negative Breast Cancer in†vitro and in†vivo.

The FOXM1 protein controls the expression of essential genes related to cancer cell cycle progression, metastasis, and chemoresistance. We hypothesize that FOXM1 inhibitors could represent a novel approach to develop 18 F-based radiotracers for Positron Emission Tomography (PET). Therefore, in this report we describe the first attempt to use 18 F-labeled FOXM1 inhibitors to detect triple-negative breast cancer (TNBC). Briefly, we replaced the original amide group in the parent drug FDI-6 for a ketone group in the novel AF-FDI molecule, to carry out an aromatic nucleophilic (18 F)-fluorination. AF-FDI dissociated the FOXM1-DNA complex, decreased FOXM1 levels, and inhibited cell proliferation in a TNBC cell line (MDA-MB-231). [18 F]AF-FDI was internalized in MDA-MB-231 cells. Cell uptake inhibition experiments showed that AF-FDI and FDI-6 significantly decreased the maximum uptake of [18 F]AF-FDI, suggesting specificity towards FOXM1. [18 F]AF-FDI reached a tumor uptake of SUV=0.31 in MDA-MB-231 tumor-bearing mice and was metabolically stable 60 min post-injection. These results provide preliminary evidence supporting the potential role of FOXM1 to develop PET radiotracers.

Selective resection of cushing microadenoma guided by preoperative hybrid 18-fluoroethyl-L-tyrosine and 11-C-methionine PET/MRI.

PURPOSE: 11-C-methionine (MET)-positron emission tomography (PET) as an adjunct to magnetic resonance imaging (MRI) has been proposed as a suitable molecular imaging modality for localizing pituitary adenomas in Cushing's disease. 18-F-Fluoroethyl-L-tyrosine (FET)-PET, which is more widely available has not yet been reported in this context. METHODS: Retrospective double-center cohort study on 15 patients who underwent transsphenoidal surgery for biochemically proven Cushing's disease between 2011 and 2019. Preoperative MET-PET/MRI and/or FET-PET/MRI were compared with intraoperative and histopathological examinations using the Mann Whitney U test and the Fisher's Exact test, along with positive predictive value calculations. RESULTS: Fifteen patients were included, with a mean age of 47.2 (18-69) years. Six patients received either a MET-PET/MRI or a FET-PET/MRI and 3 patients both exams, respectively. 67% of the tumors were detected by MRI (MET-PET-group [56%]; FET-PET-group [78%]). All tumors were microadenomas with a mean adenoma volume of 0.19 cm3 (0.02-0.78), all of which displayed a circumscribed pathological FET- and/or MET-uptake. FET-PET/MRI results positively correlated with the localization of the tumor confirmed intraoperatively and histopathologically in all cases, resulting in a sensitivity and specificity of FET-PET/MRI for tumor localization of 100% (95% CI 66.37-100%). One MET-PET/MRI suggested a localization contralateral to the expected spot. The sensitivity and specificity of MET-PET for tumor localization hence was 89% (95% CI 51.75-99.72%). CONCLUSIONS: Preoperative hybrid FET-PET/MRI and MET-PET/MRI have a high predictive value in localizing corticotroph adenoma for selective adenomectomy in Cushing's disease.

Identify. Quantify. Predict. Why Immunologists Should Widely Use Molecular Imaging for Coronavirus Disease 2019.

Molecular imaging using PET/CT or PET/MRI has evolved from an experimental imaging modality at its inception in 1972 to an integral component of diagnostic procedures in oncology, and, to lesser extent, in cardiology and neurology, by successfully offering in-vivo imaging and quantitation of key pathophysiological targets or molecular signatures, such as glucose metabolism in cancerous disease. Apart from metabolism probes, novel radiolabeled peptide and antibody PET tracers, including radiolabeled monoclonal antibodies (mAbs) have entered the clinical arena, providing the in-vivo capability to collect target-specific quantitative in-vivo data on cellular and molecular pathomechanisms on a whole-body scale, and eventually, extract imaging biomarkers possibly serving as prognostic indicators. The success of molecular imaging in mapping disease severity on a whole-body scale, and directing targeted therapies in oncology possibly could translate to the management of Coronavirus Disease 2019 (COVID-19), by identifying, localizing, and quantifying involvement of different immune mediated responses to the infection with SARS-COV2 during the course of acute infection and possible, chronic courses with long-term effects on specific organs. The authors summarize current knowledge for medical imaging in COVID-19 in general with a focus on molecular imaging technology and provide a perspective for immunologists interested in molecular imaging research using validated and immediately available molecular probes, as well as possible future targets, highlighting key targets for tailored treatment approaches as brought up by key opinion leaders.

Appropriate use criteria for dementia amyloid imaging in Switzerland - mini-review and statement on behalf of the Swiss Society of Nuclear Medicine and the Swiss Memory Clinics.

While FDG-PET imaging of the brain for the differential diagnosis of dementia has been covered by the compulsory health insurance in Switzerland for more than a decade, beta-amyloid-PET just recently has been added to the catalogue of procedures that have been cleared for routine use, provided that a set of appropriate use criteria (AUC) be followed. To provide guidance to dementia care practitioners, the Swiss Society of Nuclear Medicine and the Swiss Memory Clinics jointly report a mini-review on beta-amyloid-PET and discuss the AUC set into effect by the Swiss Federal Office of Public Health, as well as their application and limitations.

Effect of cocoa on the brain and gut in healthy subjects: a randomised controlled trial.

Dark chocolate is claimed to have effects on gastrointestinal function and to improve well-being. This randomised controlled study tested the hypothesis that cocoa slows gastric emptying and intestinal transit. Functional brain imaging identified central effects of cocoa on cortical activity. Healthy volunteers (HV) ingested 100 g dark (72 % cocoa) or white (0 % cocoa) chocolate for 5 d, in randomised order. Participants recorded abdominal symptoms and stool consistency by the Bristol Stool Score (BSS). Gastric emptying (GE) and intestinal and colonic transit time were assessed by scintigraphy and marker studies, respectively. Combined positron emission tomography-computed tomography (PET-CT) imaging assessed regional brain activity. A total of sixteen HV (seven females and nine males) completed the studies (mean age 34 (21-58) years, BMI 22·8 (18·5-26·0) kg/m2). Dark chocolate had no effect on upper gastrointestinal function (GE half-time 82 (75-120) v. 83 (60-120) min; P=0·937); however, stool consistency was increased (BSS 3 (3-5) v. 4 (4-6); P=0·011) and there was a trend to slower colonic transit (17 (13-26) v. 21 (15-47) h; P=0·075). PET-CT imaging showed increased [18F]fluorodeoxyglucose (FDG) in the visual cortex, with increased FDG uptake also in somatosensory, motor and pre-frontal cortices (P<0·001). In conclusion, dark chocolate with a high cocoa content has effects on colonic and cerebral function in HV. Future research will assess its effects in patients with functional gastrointestinal diseases with disturbed bowel function and psychological complaints.

[18F]FDG positron emission tomography in patients presenting with suspicion of giant cell arteritis-lessons from a vasculitis clinic.

Aims: The usefulness of [18F] fluorodeoxyglucose-positron emission tomography/computed tomography ([18F]FDG-PET/CT) for diagnosing giant cell arteritis (GCA) has been previously reported. Yet, the interpretation of PET scans is not clear-cut. The present study aimed at determining the best method to analyse PET/CT in a large, real-life cohort of patients presenting with suspicion of GCA. Methods and results: One hundred and three patients with clinical suspicion of GCA undergoing PET/CT between 2006 and 2012 were included. Clinical data were retrieved from patients' charts. PET/CT was categorized by visual scoring of the uptake and by the artery/liver standardized uptake values (SUV) ratios. Diagnosis of GCA was confirmed in 68 patients and excluded in 35 patients, which served as the controls. GCA patients were older (median age 75 vs. 68 years), and presented more often with ischaemic symptoms. The best discrimination between GCA patients and controls was achieved for PET/CT findings within the supra-aortic arteries (sensitivity 0.71, specificity 0.91 for a SUV/LE cut-off value of 1.0). Specificity of PET/CT for the aorta and the iliofemoral arteries was lower (<0.34). Visual scoring correlated poorly to SUV measurements (Kendall Tau-b 0.13-0.55) and had a lower diagnostic accuracy (sensitivity 0.77, specificity 0.75). Prednisone treatment for ≥10 days significantly reduced PET/CT sensitivity (P = 0.009). Conclusion: SUV based analysis of PET/CT enhances diagnostic accuracy with best discrimination in the supra-aortic region, particularly in steroid naïve patients. For discrimination based on the aorta and the iliofemoral region, higher cut-off values have to be applied, resulting in lower sensitivities for diagnosing GCA.

Intrinsic functional connectivity alterations in progressive supranuclear palsy: Differential effects in frontal cortex, motor, and midbrain networks.

BACKGROUND: The topography of functional network changes in progressive supranuclear palsy can be mapped by intrinsic functional connectivity MRI. The objective of this study was to study functional connectivity and its clinical and behavioral correlates in dedicated networks comprising the cognition-related default mode and the motor and midbrain functional networks in patients with PSP. METHODS: Whole-brain-based "resting-state" functional MRI and high-resolution T1-weighted magnetic resonance imaging data together with neuropsychological and video-oculographic data from 34 PSP patients (22 with Richardson subtype and 12 with parkinsonian subtype) and 35 matched healthy controls were subjected to network-based functional connectivity and voxel-based morphometry analysis. RESULTS: After correction for global patterns of brain atrophy, the group comparison between PSP patients and controls revealed significantly decreased functional connectivity (P < 0.05, corrected) in the prefrontal cortex, which was significantly correlated with cognitive performance (P = 0.006). Of note, midbrain network connectivity in PSP patients showed increased connectivity with the thalamus, on the one hand, whereas, on the other hand, lower functional connectivity within the midbrain was significantly correlated with vertical gaze impairment, as quantified by video-oculography (P = 0.004). PSP Richardson subtype showed significantly increased functional motor network connectivity with the medial prefrontal gyrus. CONCLUSIONS: PSP-associated neurodegeneration was attributed to both decreased and increased functional connectivity. Decreasing functional connectivity was associated with worse behavioral performance (ie, dementia severity and gaze palsy), whereas the pattern of increased functional connectivity may be a potential adaptive mechanism. © 2017 International Parkinson and Movement Disorder Society.

Trametinib after disease reactivation under dabrafenib in Erdheim-Chester disease with both BRAF and KRAS mutations.

Major advances have been made in understanding the pathogenesis of Erdheim-Chester disease (ECD) leading to novel treatment strategies. Targeted therapies such as BRAF inhibition have shown a significant impact on disease management, emphasizing the importance of the activated mitogen-associated protein kinase pathway in this disease. However, incomplete responsiveness, potentially limiting adverse effects, and the occurrence of treatment resistance to BRAF inhibition observed in other BRAF-mutant malignancies imply the importance of therapeutic strategies beyond BRAF inhibition. We report a patient with ECD who carried the BRAFV600E mutation and developed treatment resistance under BRAF inhibition despite initial treatment response. Genetic analyses of a newly developing ECD lesion revealed a somatic KRASQ61H mutation without the presence of BRAFV600E Accordingly, the addition of MEK-inhibiting trametinib to BRAF-inhibiting dabrafenib was able to overcome acquired partial treatment resistance. This is the first report of treatment resistance as a result of a secondary MAPK pathway-activating mutation during BRAF inhibition in ECD. This case contributes to the ongoing efforts of simultaneous BRAF/MEK inhibition as a promising strategy in ECD.

Nondermatomal somatosensory deficits in patients with chronic pain disorder: clinical findings and hypometabolic pattern in FDG-PET.

Patients with chronic pain disorders often show somatosensory disturbances that are considered to be functional. This paper aims at a more precise clinical description and at a documentation of functional neuroimaging correlates of this phenomenon. We examined 30 consecutive patients with unilaterally accentuated chronic pain not explained by persistent peripheral tissue damage and ipsilateral somatosensory disturbances including upper and lower extremities and trunk. The patients were assessed clinically and with conventional brain CT or MRI scan. In the last 11 patients functional neuroimaging was carried out (18-fluordeoxyglucose positron emission tomography=FDG-PET). Depressive symptoms were assessed with the Hamilton depression scale (HAMD-17) and pain intensity was rated with a visual analogue scale for pain (VAS). All patients suffered from mild to moderate depressive symptoms. All patients had experienced a prolonged antecedent phase of severe emotional distress; most of them remembered a "trigger episode of somatic pain" on the affected side. Somatosensory deficits were a replicable hyposensitivity to touch and heat perception of nondermatomal distribution. Conventional imaging procedures (brain CT or MRI scans) showed no structural changes. However, in 11 patients functional imaging with FDG-PET showed a significant hypometabolic pattern of changes in cortical and subcortical areas, mainly in the post-central gyrus, posterior insula, putamen, and anterior cingulate cortex. In summary, pain-related nondermatomal somatosensory deficits (NDSDs) are a phenomenon involving biological as well as psychosocial factors with replicable neuroperceptive clinical findings and a complex neurodysfunctional pattern in the FDG-PET.

FDG uptake in giant cell tumor of the tendon sheath in a patient restaged for gastrointestinal stroma tumor (GIST).

A 70-year-old man known for recurrent abdominal gastrointestinal stroma tumor presented with a suspicious peritoneal mass demonstrated by an abdominal CT scan. Whole-body PET showed focal FDG uptake in the right hip, whereas the peritoneal mass was FDG negative. Histologic work-up of the PET positive lesion surprisingly revealed a giant cell tumor of the tendon sheath. The benignity of the peritoneal mass was confirmed by its disappearance in repeated CT scans. In general, focally increased FDG uptake should be subject to further investigations, especially in localizations that are not consistent with typical metastatic pathways of the former primary tumor.

Different regional brain volume loss in pure and complicated hereditary spastic paraparesis: a voxel-based morphometric study.

Three-dimensional magnetic resonance imaging of the brain was analyzed using optimized voxel-based morphometry in 21 patients with pure hereditary spastic paraparesis (pHSP) and 12 patients with complicated HSP (cHSP). PHSP patients showed only small regional grey matter volume reduction, whereas significantly decreased grey matter volumes were localized pericentrally in cHSP. In the white matter, several small areas of regional volume reduction were observed in the pHSP patients, whereas the cHSP group exhibited large robust volume reduction involving the entire corpus callosum, a result that was reproduced by an additional region-based MRI analysis. It could be demonstrated that the topography of cerebral volume changes differed markedly in pHSP or cHSP at group level. Corpus callosum thinning seems to be a general feature of cHSP.

Cortical grey matter alterations in idiopathic restless legs syndrome: An optimized voxel-based morphometry study.

An impairment of central somatosensory processing is assumed in restless legs syndrome (RLS). Although functional neuroimaging in RLS gave evidence to the presence of widespread functional changes in various brain areas, structural changes at the cortical level were not reported to be RLS-associated to date. Here, an analysis of high-resolution three-dimensional magnetic resonance imaging (MRI) was performed in 63 patients with idiopathic RLS by use of optimized voxel-based morphometry, in order to investigate if cortical areas might be altered in volume at group level according to the phenomenology of RLS. The comparison of the RLS patients versus controls yielded significant regional decreases of gray matter volume at corrected P < 0.05 in the bihemispheric primary somatosensory cortex, which additionally extended into left-sided primary motor areas. All clusters correlated both with the severity of RLS symptoms and with disease duration. These results, for the first time, give in vivo evidence to structural neocortical gray matter alterations in RLS patients. The alterations in the sensorimotor cortices might add to the pathophysiological concepts of idiopathic RLS.