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.

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.

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: 1st 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.

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.

Recommandations de Swiss Memory Clinics pour le diagnostic des démences

Résumé. Le diagnostic précoce des atteintes cognitives, ressenties subjectivement ou rapportées par un tiers, est essentiel pour détecter des maladies neurodégénératives ou exclure des causes traitables telles que des pathologies de médecine interne, neurologiques ou psychiatriques. C’est la seule façon de garantir un traitement anticipé. Dans le cadre du projet 3.1 de la stratégie nationale en matière de démences 2014–2019 («Mise en place et extension d’un réseau de centres de compétences régionaux pour le diagnostic»), l’association Swiss Memory Clinics (SMC) s’est fixé pour objectif d’améliorer les normes de qualité en matière de diagnostic des démences et de soins de proximité dans ce domaine. Ces recommandations contiennent des directives d’ordre général sur le diagnostic et les différentes possibilités d’examens, et proposent des normes pour les procédures à appliquer. Elles expliquent en détail les différents éléments du diagnostic standard, tels que l’anamnèse, l’examen clinique, l’analyse de laboratoire, les tests neuropsychologiques et les procédures neuroradiologiques, et présentent des examens complémentaires pouvant alimenter les réflexions sur le diagnostic différentiel. Les principaux objectifs des recommandations SMC pour le diagnostic des démences sont les suivants: assurer l’accès à un diagnostic de haute qualité à un maximum de personnes atteintes, améliorer le diagnostic précoce de la démence, ainsi que proposer aux médecins de premier recours et aux collaborateurs de Memory Clinics un outil d’investigations diagnostiques utile.

Die Empfehlungen der Swiss Memory Clinics für die Diagnostik der Demenzerkrankungen

Zusammenfassung. Die Frühdiagnostik subjektiv wahrgenommener oder fremdanamnestisch beobachteter kognitiver Beeinträchtigungen ist essenziell, um neurodegenerative Erkrankungen nachzuweisen oder behandelbare Ursachen wie internistische, neurologische oder psychiatrische Störungen auszuschliessen. Nur dadurch wird eine frühzeitige Behandlung ermöglicht. Im Rahmen des Projekts 3.1 der Nationalen Demenzstrategie 2014–2019 («Auf- und Ausbau regionaler und vernetzter Kompetenzzentren für die Diagnostik») hat sich der Verein Swiss Memory Clinics (SMC) zum Ziel gesetzt, Qualitätsstandards für die Demenzabklärung zu entwickeln und die wohnortsnahe Versorgung in diesem Bereich zu verbessern. In den vorliegenden Empfehlungen werden allgemeine Richtlinien der Diagnostik und einzelne Untersuchungsmöglichkeiten vorgestellt, sowie Standards für die diesbezüglichen Abläufe vorgeschlagen. Einzelne Bereiche wie Anamneseerhebung, klinische Untersuchung, Laborparameter, neuropsychologische Testung und neuroradiologische Verfahren werden als Teil der Standarddiagnostik ausführlich diskutiert, ergänzende Untersuchungsmethoden für differenzialdiagnostische Überlegungen abgebildet. Die wichtigsten Ziele der SMC-Empfehlungen zur Diagnostik der Demenzerkrankungen sind, möglichst allen Betroffenen Zugang zu einer qualitativ hochstehenden Diagnostik zu ermöglichen, die Frühdiagnostik der Demenz zu verbessern und den Grundversorgern sowie den Mitarbeitenden der Memory Clinics ein nützliches Instrument für die Abklärung anzubieten.

Precise Localization of Dysfunctional Areas in Vertebrobasilar Infarction by FDGand 0-15-H20-PET Using Standardized Image Analysis and Image Registration to 3-D MR

The advantages of standardized multimodal image analysis are demonstrated in a case of symptomatic tremor after basilar thrombosis. Functionally and structurally lesioned areas were mapped in Talairach space using 3-D MRI, cerebral FDG-PET and 0-15-H20-PET. Structural lesions were found in the left midbrain, thalamus, putamen and cerebellar areas. Voxel-based statistics in comparison to a normal data base revealed hypometabolism in the left thalamus, left red nucleus, left cerebellar hemisphere including dentate nucleus and in the left inferior olivary nucleus. The 0-15-H20-PET investigation revealed metabolic uncoupling along the rubroolivocerebellar loop. Given the delicate anatomy of the structures involved, image registration and standardized image analysis techniques are essential for a synoptic multimodality analysis of morphological and functional pathology and should generally be used for cerebral PET investigations.

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 BRAF^V600E mutation and developed treatment resistance under BRAF inhibition despite initial treatment response. Genetic analyses of a newly developing ECD lesion revealed a somatic KRAS^Q61H mutation without the presence of BRAF^V600E 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.

Impact of obesity and bariatric surgery on metabolism and coronary circulatory function

Increases in intra-abdominal visceral adipose tissue have been widely appreciated as a risk factor for metabolic disorders such as dyslipidemia, hypertension, insulin resistance, and type 2 diabetes, whereas this is not the case for peripheral or subcutaneous obesity. While the underlying mechanisms that contribute to these differences in adipose tissue activity remain uncertain, increases in visceral fat commonly induce metabolic dysregulation, in part because of increased venous effluent of fatty acids and/or adipokines/cytokines to the liver. Increased body weight, paralleled by an increase in plasma markers of the insulin-resistance syndrome and chronic inflammation, is independently associated with coronary circulatory dysfunction. Recent data suggest that plasma proteins originating from the adipose tissue, such as endocannabinoids (EC), leptin, and adiponectin (termed adipocytes) play a central role in the regulation and control of coronary circulatory function in obesity. Positron emission tomography (PET) in concert with tracer kinetic modeling is a well established technique for quantifying regional myocardial blood flow at rest and in response to various forms of vasomotor stress. Myocardial flow reserve assessed by PET provides a noninvasive surrogate of coronary circulatory function. PET also enables the monitoring and characterization of coronary circulatory function in response to gastric bypass-induced weight loss in initially morbidly obese individuals, to medication and/or behavioral interventions related to weight, diet, and physical activity. Whether the observed improvement in coronary circulatory dysfunction via weight loss may translate to diminution in cardiovascular events awaits clinical confirmation.

Differential diagnoses of nocturnal fear and movement paroxysm: a case report

Recurrent nocturnal behavioural and movement paroxysms are a diagnostic challenge for the clinical pediatrician. We report on an adolescent girl who presents recurrent stereotypical nightmare-like episodes occurring during non-REM sleep stages 1-2 (N1 and N2). We discuss the differential diagnoses between epileptic and nonepileptic events and between nocturnal frontal and temporal seizures. The pathophysiological and unusual electroencephalographical features are discussed with respect to clinical features and results of interictal FDG-PET. Conclusion In case of stereotypical nightmare-like episodes in children or adolescents, an epileptic origin has to be ruled out before a parasomnia is diagnosed. In addition, a normal awake EEG or interictal sleep EEG in the diagnostic workup may not exclude an epileptic disorder. In case of nightly stereotypic motor or affective events, an epileptic disorder should be discussed.

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.

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.

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.

Widespread white matter changes in Kennedy disease: a voxel based morphometry study

OBJECTIVE

X linked spinobulbar muscular atrophy (Kennedy disease (KD)), which is clinically characterised mainly by neuromuscular and endocrine symptoms, has to be considered as a multisystem disorder. Based on clinical evidence of central nervous system involvement, potential KD associated cerebral volume alterations were analysed in vivo.

METHODS

Whole brain based analysis of optimised voxel based morphometry (VBM) was applied to three dimensional MRI data from 18 genetically confirmed KD patients and compared with age matched controls.

RESULTS

Subtle decreases in grey matter volume, mainly localised in frontal areas, were found, but extensive white matter atrophy was observed, particularly in frontal areas, but also involving multiple additional subcortical areas, the cerebellar white matter and the dorsal brainstem from the midbrain to the medulla oblongata.

CONCLUSION

The VBM results demonstrated a morphological correlate of central nervous system involvement in KD, in agreement with aspects of the clinical phenotype (behavioural abnormalities, central-peripheral axonopathy) and with pathohistological findings.

Brain morphology alterations in the basal ganglia and the hypothalamus following prenatal exposure to antiepileptic drugs

If humans are exposed prenatally to antiepileptic drugs (AEDs), cognitive impairment may be the consequence. Driven by results of experimental work showing that AEDs may induce neuronal death in the developing rodent brain, we wanted to explore whether prenatal exposure to AEDs (PAE) may result in structural changes in the human brain. For this purpose we investigated a group of healthy young adults with PAE and a group of age-matched unexposed healthy controls by magnetic resonance imaging (MRI) of the brain. Local differences in cerebral morphology associated with PAE were analysed in volumetric MRI data by use of voxelwise comparisons of grey and white matter images. Significant regional decreases of grey matter volumes were found in PAE subjects in the area of the lentiform nucleus, including both pallidum and putamen bilaterally, and the hypothalamus. No significant regional differences in white matter volumes were found. We conclude that PAE causes subtle morphological changes in grey matter of the human brain which are conform with lower cell numbers in the basal ganglia and the hypothalamus.

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.

Patterns of regional brain hypometabolism associated with knowledge of semantic features and categories in Alzheimer's disease

The study of semantic memory in patients with Alzheimer's disease (AD) has raised important questions about the representation of conceptual knowledge in the human brain. It is still unknown whether semantic memory impairments are caused by localized damage to specialized regions or by diffuse damage to distributed representations within nonspecialized brain areas. To our knowledge, there have been no direct correlations of neuroimaging of in vivo brain function in AD with performance on tasks differentially addressing visual and functional knowledge of living and nonliving concepts. We used a semantic verification task and resting 18-fluorodeoxyglucose positron emission tomography in a group of mild to moderate AD patients to investigate this issue. The four task conditions required semantic knowledge of (1) visual, (2) functional properties of living objects, and (3) visual or (4) functional properties of nonliving objects. Visual property verification of living objects was significantly correlated with left posterior fusiform gyrus metabolism (Brodmann's area [BA] 37/19). Effects of visual and functional property verification for non-living objects largely overlapped in the left anterior temporal (BA 38/20) and bilateral premotor areas (BA 6), with the visual condition extending more into left lateral precentral areas. There were no associations with functional property verification for living concepts. Our results provide strong support for anatomically separable representations of living and nonliving concepts, as well as visual feature knowledge of living objects, and against distributed accounts of semantic memory that view visual and functional features of living and nonliving objects as distributed across a common set of brain areas.

When left becomes right and vice versa: mirrored vision after cerebral hypoxia

The combination of acquired mirror writing and reading is an extremely rare neurological disorder. It is encountered when brain damaged patients prefer horizontally mirrored over normal script in writing and reading. Previous theories have related this pathology to a disinhibition of mirrored engrams in the non-dominant hemisphere, possibly accompanied by a reversal of the preferred scanning direction. Here, we report the experimental investigation of PR, a patient who developed pronounced mirror writing and reading following septic shock that caused hypoxic brain damage. A series of five oculomotor experiments revealed that the patient's preferred scanning direction was indeed reversed. However, PR showed striking scanpath abnormalities and mirror reversals that cannot be explained by previous theories. Considered together with mirror phenomena she displayed in neuropsychological tasks and everyday activities, our findings suggest a horizontal reversal of visual information on a perceptual level. In addition, a systematic manipulation of visual variables within two further experiments had dramatic effects on her mirror phenomena. When confronted with moving, flickering or briefly presented stimuli, PR showed hardly any left-right reversals. Not only do these findings underline the perceptual nature of her disorder, but also allow interpretation of the pathology in terms of a dissociation between visual subsystems. We speculate that early visual cortices are crucially involved in this dissociation. More generally, her mirrored vision may represent an extreme clinical manifestation of the relative instability of the horizontal axis in spatial vision.

Brain atrophy in pure and complicated hereditary spastic paraparesis: a quantitative 3D MRI study

Hereditary spastic paraparesis (HSP) is a heterogeneous group of neurodegenerative disorders with progressive lower limb spasticity, categorized into pure (p-HSP) and complicated forms (c-HSP). The purpose of this study was to evaluate if brain volumes in HSP were altered compared with a control population. Brain volumes were determined in patients suffering from HSP, including both p-HSP (n = 21) and c-HSP type (n = 12), and 30 age-matched healthy controls, using brain parenchymal fractions (BPF) calculated from 3D MRI data in an observer-independent procedure. In addition, the tissue segments of grey and white matter were analysed separately. In HSP patients, BPF were significantly reduced compared with controls both for the whole patient group (P < 0.001) and for both subgroups, indicating considerable brain atrophy. In contrast to controls who showed a decline of brain volumes with age, this physiological phenomenon was less pronounced in HSP. Therefore, global brain parenchyma reduction, involving both grey and white matter, seems to be a feature in both subtypes of HSP. Atrophy was more pronounced in c-HSP, consistent with the more severe phenotype including extramotor involvement. Thus, global brain atrophy, detected by MRI-based brain volume quantification, is a biological marker in HSP subtypes.

Grey-matter abnormalities in boys with Tourette syndrome: magnetic resonance imaging study using optimised voxel-based morphometry

The genesis of Tourette syndrome is still unknown, but a core role for the pathways of cortico-striatal-thalamic-cortical circuitry (CSTC) is supposed. Volume-rendering magnetic resonance imaging data-sets were analysed in 14 boys with Tourette syndrome and 15 age-matched controls using optimised voxel-based morphometry. Locally increased grey-matter volumes (corrected P < 0.001) were found bilaterally in the ventral putamen. Regional decreases in grey matter were observed in the left hippocampal gyrus. This unbiased analysis confirmed an association between striatal abnormalities and Tourette syndrome, and the hippocampal volume alterations indicate an involvement of temporolimbic pathways of the CSTC in the syndrome.

Dose selection for radioiodine therapy of borderline hyperthyroid patients according to thyroid uptake of 99mTc-pertechnetate: applicability to unifocal thyroid autonomy?

PURPOSE

The aim of this study was to evaluate the feasibility of applying a previously described dose strategy based on (99m)Tc-pertechnetate thyroid uptake under thyrotropin suppression (TcTU(s)) to radioiodine therapy for unifocal thyroid autonomy.

METHODS

A total of 425 consecutive patients (302 females, 123 males; age 63.1+/-10.3 years) with unifocal thyroid autonomy were treated at three different centres with (131)I, using Marinelli's formula for calculation of three different absorbed dose schedules: 100-300 Gy to the total thyroid volume according to the pre-treatment TcTU(s) (n=146), 300 Gy to the nodule volume (n=137) and 400 Gy to the nodule volume (n=142).

RESULTS

Successful elimination of functional thyroid autonomy with either euthyroidism or hypothyroidism occurred at a mean of 12 months after radioiodine therapy in 94.5% of patients receiving 100-300 Gy to the thyroid volume, in 89.8% of patients receiving 300 Gy to the nodule volume and in 94.4% receiving 400 Gy to the nodule volume. Reduction in thyroid volume was highest for the 100-300 Gy per thyroid and 400 Gy per nodule strategies (36+/-19% and 38+/-20%, respectively) and significantly lower for the 300 Gy per nodule strategy (28+/-16%; p<0.01).

CONCLUSION

A dose strategy based on the TcTU(s) can be used independently of the scintigraphic pattern of functional autonomous tissue in the thyroid.

Brain activation during craving for alcohol measured by positron emission tomography

OBJECTIVE

Craving for alcohol is probably involved in acquisition and maintenance of alcohol dependence to a substantial degree. However, the brain substrates and mechanisms that underlie alcohol craving await more detailed elucidation.

METHOD

Positron emission tomography was used to map regional cerebral blood flow (CBF) in 21 detoxified patients with alcohol dependence during exposure to alcoholic and non-alcoholic beverages.

RESULTS

During the alcohol condition compared with the control condition, significantly increased CBF was found in the ventral putamen. Additionally, activated areas included insula, dorsolateral prefrontal cortex and cerebellum. Cerebral blood flow increase in these regions was related to self-reports of craving assessed in the alcoholic patients.

CONCLUSIONS

In this investigation, cue-induced alcohol craving was associated with activation of brain regions particularly involved in brain reward mechanisms, memory and attentional processes. These results are consistent with studies on craving for other addictive substances and may offer strategies for more elaborate studies on the neurobiology of addiction.

Mapping of temporal and parietal cortex in progressive nonfluent aphasia and Alzheimer's disease using chemical shift imaging, voxel-based morphometry and positron emission tomography

Little and controversial evidence is available from neuroimaging studies in progressive nonfluent aphasia (PNA). The goal of this study was to combine information from different imaging modalities in PNA compared with Alzheimer's disease (AD). Chemical shift imaging (CSI), voxel-based morphometry (VBM) and fluorodeoxyglucose positron emission tomography (FDG-PET) were used in 5 PNA, 10 AD patients and 10 normal subjects. Group comparisons revealed left anterior lateral temporal abnormalities (BA20/21) in PNA using CSI, VBM and PET in comparison to normal subjects. AD patients showed more limited hypometabolism within the same area. In addition left lateral parietal (BA40) abnormalities were demonstrated in our PNA as well as our AD group using PET and VBM (AD group only). Combining information from all imaging modalities on a single case basis revealed pathology within the left anterior lateral temporal and lateral parietal lobe both in PNA and AD. PNA and AD patients differed significantly, however, with respect to the frequency of medial temporal lobe and posterior cingulate/precuneus involvement. Although our results might not be generalizable to all subgroups of PNA, we conclude that medial temporal and posterior cingulate/precuneus cortex pathology as assessed by CSI and VBM or PET distinguish PNA from AD, whereas lateral temporal and parietal areas are involved in both conditions.

Comparison of voxel-based 3-D MRI analysis and subtraction ictal SPECT coregistered to MRI in focal epilepsy

While voxel-based 3-D MRI analysis methods as well as assessment of subtracted ictal versus interictal perfusion studies (SISCOM) have proven their potential in the detection of lesions in focal epilepsy, a combined approach has not yet been reported. The present study investigates if individual automated voxel-based 3-D MRI analyses combined with SISCOM studies contribute to an enhanced detection of mesiotemporal epileptogenic foci. Seven consecutive patients with refractory complex partial epilepsy were prospectively evaluated by SISCOM and voxel-based 3-D MRI analysis. The functional perfusion maps and voxel-based statistical maps were coregistered in 3-D space. In five patients with temporal lobe epilepsy (TLE), the area of ictal hyperperfusion and corresponding structural abnormalities detected by 3-D MRI analysis were identified within the same temporal lobe. In two patients, additional structural and functional abnormalities were detected beyond the mesial temporal lobe. Five patients with TLE underwent epileptic surgery with favourable postoperative outcome (Engel class Ia and Ib) after 3-5 years of follow-up, while two patients remained on conservative treatment. In summary, multimodal assessment of structural abnormalities by voxel-based analysis and SISCOM may contribute to advanced observer-independent preoperative assessment of seizure origin.

Separating functional and structural damage in persistent vegetative state using combined voxel-based analysis of 3-D MRI and FDG-PET

Functional and structural damage in postanoxic persistent vegetative state (PVS) was analysed using 18fluorodeoxyglucose PET (FDG-PET) coregistered to 3-D MRI in combination with morphometric 3-D MRI analysis (voxel-based morphometry, VBM). In five patients in late stages of non-traumatic PVS, combined analysis using statistical parametric mapping (SPM2) was performed to compare metabolic impairment and structural loss. FDG-PET showed widespread hypometabolism at p<0.001 (corrected) in the parietal, parietooccipital and frontotemporal cortices, cingulum, frontal medial and precentral gyrus, and within the bilateral thalamus. VBM revealed multilocal structural loss at p<0.001 (corrected) in the inferior parietal and superior/medial frontal cortices, insula and operculum, superior and medial temporal lobes, cingulum and fusiform gyrus, caudate, midbrain, dorsal pons, and the cerebellum, but to a lesser extent in the thalamus. The selective vulnerability of the brain in a sample of PVS patients could be mapped in vivo, indicating that a complex structural and functional lesion pattern of the cerebral networks seems to be associated with this condition.

Hemispheric asymmetries of hypometabolism associated with semantic memory impairment in Alzheimer's disease: a study using positron emission tomography with fluorodeoxyglucose-F18

Considerable disagreement exists about the neuroanatomical basis of conceptual-semantic impairments observed in a subgroup of patients with Alzheimer's disease (AD) at mild to moderate stages of the disease. Several studies of groups of patients have shown correlations between focal hypometabolism or hypoperfusion in left hemispheric areas and measures of verbal semantic memory impairment in AD patients. The question remains, however, whether left hemispheric hypometabolism is sufficient to produce such impairment in the single case and whether nonverbal semantic knowledge is also affected. We used positron emission tomography (PET) with fluorodeoxyglucose-F18 (FDG), statistical parametric mapping (SPM), and tests of verbal and nonverbal semantic memory in 11 AD patients with a mean score on the Mini-Mental State Examination of 22.6 (+/-2.8). Naming impairment was significantly associated with left hemispheric asymmetry of hypometabolism on a single-case basis. Our correlation analysis showed that metabolism in left anterior temporal, posterior inferior temporal, inferior parietal and medial occipital areas (Brodmann areas: 21/38, 37, 40 and 19) correlated with both verbal and nonverbal semantic performance. We conclude that left hemispheric synaptic dysfunction, as measured by regional glucose hypometabolism, was sufficient to produce semantic impairments in our patients. The majority of areas affected in our patients with semantic impairments were involved in multimodal or supramodal (verbal and nonverbal) semantic knowledge.

Thalamic atrophy in Huntington's disease co-varies with cognitive performance: a morphometric MRI analysis

The pattern of motor, behavioral and cognitive symptoms in Huntington's disease (HD) implicates dysfunction of basal-ganglia-thalamo-cortical circuits. This study explored if cognitive performance in HD is correlated with localized cerebral changes. Psychomotor functions were investigated by verbal fluency, Stroop color word and Digit Symbol tests in 44 HD patients and 22 controls. Three-dimensional magnetic resonance imaging (MRI) data were analyzed with regard to regional gray matter changes by use of the observer-independent whole-brain-based approach of voxel-based morphometry (VBM). Using statistical parametric mapping, the MRI data of the HD patients were analyzed in an ANCOVA including the individual results of the neuropsychological tests. Besides striatal areas, symmetrical regional atrophy of the thalamus was found to co-vary significantly with cognitive performance (P < 0.001, corrected for multiple comparisons). In particular, thalamic subnuclei projecting to prefrontal areas (dorsomedial subnucleus) and connected to the striatum (centromedian/parafascicular and ventrolateral nuclear complex) displayed volume loss, in agreement with neuropathological studies. These results suggest that thalamic degeneration contributes in an important way to the impairment of executive function in early HD. Patients who are impaired in executive tests display structural double lesions of the basal-ganglia-thalamo-cortical circuitry both at the striatal and at the thalamic level.

Global cerebral atrophy in early stages of Huntington's disease: quantitative MRI study

Global brain atrophy was determined in 70 patients suffering from Huntington's disease (HD) and 70 healthy controls, using brain parenchymal fractions calculated from 3D MRI data in a standardized procedure. In HD patients, brain parenchymal fractions were significantly reduced compared to controls in all age groups; the physiological decline with age was less pronounced in HD. However, brain parenchymal fraction values did not allow the prediction of clinical impairment (as assessed by clinical scores). Global brain parenchyma reduction seems to be an early or even constitutional feature of HD, but clinical symptoms appear to reflect regional rather than global atrophy. Overall, MRI-based brain volume quantification correlated with clinical scores clarifies the functional impact of morphological brain alterations.

18FDG-PET in epilepsies of infantile onset with pharmacoresistant generalised tonic-clonic seizures

AIMS

To investigate the pathophysiology of pharmacoresistant epilepsies with cryptogenic generalised tonic-clonic seizures (GTCS) from infancy.

METHODS

18F-Deoxy-Glucose-Positron Emission Tomography 18FDG-PET) with statistical parametric mapping (SPM). Inclusion criteria were: pharmacoresistant chronic epilepsy with GTCS commencing in infancy, no focal seizures except alternating hemiconvulsions and no focal epileptic discharges in the EEG during the first year of the disease, no focal changes upon routine neuroradiological investigations, no indication of brain damage according to history and clinical examination.

RESULTS

15 boys and 15 girls with a mean age of 6.4 years (range l-14 years) were included. All still suffered from seizures despite past treatment with a mean of five drugs. Nearly all were mentally retarded, 19 to a severe and 10 to a minor degree. Fifteen were ataxic and 11 hypotonic. The EEG in 23 showed irregular generalised spike-wave discharges. PET SPM analysis revealed bioccipital hypometabolism related to sedation. Pathological monofocal hypometabolic areas were found in three, multifocal hypometabolic areas in 22 and diffuse bilateral hypometabolism in three patients. Frontal hypometabolism correlated to the degree of mental retardation, hypotonia, and ataxia. Temporomesial hypometabolism correlated to the occurrence of obtunded states and prominent delta rhythms in the EEG. Central and parietal changes were associated with the occurrence of myoclonic seizures and spike-wave discharges.

CONCLUSIONS

18FDG-PET in many of these children with cryptogenic generalised epilepsies showed multifocal hypometabolic areas of unknown aetiology. Primary cortical microdysgenesis and secondary changes due to the severe and long-standing epilepsy must be considered. Only a minority of patients showed restricted focal hypometabolism as a possible indication for surgical treatment.

Topography of cerebral atrophy in early Huntington's disease: a voxel based morphometric MRI study

OBJECTIVES

To analyse grey matter changes in early stages of Huntington's disease using magnetic resonance imaging (MRI) and the technique of voxel based morphometry (VBM).

METHODS

Forty four patients with a molecularly confirmed clinical diagnosis of Huntington's disease based on the presence of motor signs were included in the study. Patients were clinically rated using the Unified Huntington's Disease Rating Scale; all were in early clinical stages of the disease (that is, Shoulson stages I and II). High resolution volume rendering MRI scans (MP-RAGE) were acquired. MRI data were volumetrically analysed in comparison to an age matched normal database by VBM, using statistical parametric mapping (SPM99).

RESULTS

In Huntington's disease, robust regional decreases in grey matter density (p<0.001, corrected for multiple comparisons)-that is, atrophy-were found bilaterally in striatal areas as well as in the hypothalamus and the opercular cortex, and unilaterally in the right paracentral lobule. The topography of striatal changes corresponded to the dorso-ventral gradient of neuronal loss described in neuropathological studies. Stratification according to clinical severity showed a more widespread involvement extending into the ventral aspects of the striatum in the group of more severely affected patients.

CONCLUSIONS

The topography of cerebral volume changes associated with Huntington's disease can be mapped using VBM. It can be shown that cerebral grey matter changes co-vary with clinical severity and CAG repeat length.

Quantification of brain atrophy in patients with myotonic dystrophy and proximal myotonic myopathy: a controlled 3-dimensional magnetic resonance imaging study

Myotonic dystrophy (DM1) and proximal myotonic myopathy (PROMM or DM2) are two distinct muscular disorders with multisystemic involvement. Both have previously been reported to be associated with cognitive impairment and white matter lesions detected by cerebral magnetic resonance imaging (MRI). In this study, the extent of brain atrophy was investigated in vivo in ten DM1 and nine PROMM patients in comparison to age-matched healthy controls for each group. The diagnosis was confirmed by DNA analysis of all patients. As a quantitative marker, the ratio of brain parenchymal to intracranial volume, called brain parenchymal fraction (BPF), was calculated from 3-dimensional MRI data using an automated analysis technique. Compared to age-matched healthy controls (mean BPF 0.852 +/- 0.032), the BPF in DM1 patients (0.713 +/- 0.031) was highly significantly decreased (P < 0.001). In contrast, the PROMM patients (mean BPF 0.792 +/- 0.029) showed only slightly decreased BPF values (P < 0.05). BPF was not significantly correlated to any of the clinical or genetic parameters in both diseases (disease duration, motor score, educational level, and number of CTG repeats in the expanded allele). In summary, global brain atrophy was demonstrated to occur in both diseases, but was more severely manifestated in DM1 patients.

Activation of a residual cortical network during painful stimulation in long-term postanoxic vegetative state: a 15O-H2O PET study

Survivors of prolonged cerebral anoxia often remain in the persistent vegetative state (PVS). In this study, long-term PVS patients were investigated by 15O-H(2)O PET to analyze their central processing of pain. The study was approved by the local Ethics Committee, the experiments were performed in accordance with the Helsinki Declaration of 2000. Seven patients remaining in PVS of anoxic origin for a mean of 1.6 years (range 0.25-4 years) were investigated. We performed functional PET of the brain using 15O-labelled water during electrical nociceptive stimulation. Additionally, a brain metabolism study using 18F-fluorodeoxyglucose (FDG) PET and multi-sequence MRI (including a 3-D data set) were acquired in all patients. PET data were analyzed by means of Statistical Parametric Mapping (SPM99) and coregistered to a study-specific brain template. MRI and FDG PET showed severe cortical impairment at the structural and the functional level, that is, general atrophy of various degrees and a widespread significant hypometabolism, respectively. Pain-induced activation (hyperperfusion) was found in the posterior insula/secondary somatosensory cortex (SII), postcentral gyrus/primary somatosensory cortex (SI), and the cingulate cortex contralateral to the stimulus and in the posterior insula ipsilateral to the stimulus (P<0.05, small-volume-corrected). No additional areas of the complex pain-processing matrix were significantly activated. In conclusion, the regional activity found at the cortical level indicates that a residual pain-related cerebral network remains active in long-term PVS patients.

Add-on rTMS for treatment of depression: a pilot study using stereotaxic coil-navigation according to PET data

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is regarded as a potentially new tool to treat depression. In a double-blind, randomized, sham-controlled pilot study we investigated the efficacy of neuronavigated rTMS, guided according to the prefrontal metabolic state determined by positron emission tomography (PET).

METHODS

25 patients with major depression were included. Prior to rTMS, PET scans were obtained. For the real stimulation condition, the dorsolateral prefrontal cortex (DLPFC) with lower metabolic activity compared to the contralateral hemisphere was selected, if detected by prior PET. Stimulation parameters were 15 Hz, 110% motor threshold (MT), 3000 stimuli/day, for 10 days. A neuronavigational system was used to place the magnetic coil above each individuals' selected cortical region (real condition: DLPFC, sham: midline parieto-occipital, intensity 90% of MT). RTMS was administered add-on to medication. Depression-related symptoms were rated with Beck's, Hamilton's (HAM-D), and Montgomery-Asberg's (MADRS) depression rating scales.

RESULTS

Real stimulation improved depression according to HAM-D and MADRS moderately but significantly better compared to sham at the end of the stimulation sessions. In the real condition, four out of 13 patients responded with a mean improvement in HAM-D and/or MADRS of at least 50%, whereas none responded to sham. Antidepressant effects of stimulation of the relatively hypometabolic DLPFC were comparable to stimulation in absence of metabolic differences.

CONCLUSIONS

A moderate improvement of depressive symptoms after rTMS was observed. Our preliminary data show that stimulation of prefrontal hypometabolism may not be advantageous to stimulation irrespective of the metabolic state.

High social desirability and prefrontal cortical activity in cancer patients: a preliminary study

BACKGROUND

Social desirability is sometimes associated with poor prognosis in cancer patients. Psycho-neuro-immune interaction has been hypothesized as an underlying mechanism of the negative clinical outcome. Purpose of this study was to examine possible effects of high social desirability on the regional brain activity in patients with malignant diseases.

MATERIAL/METHODS

Brain metabolism of 16 patients with various malignant diseases was measured by PET with 18F-fluorodeoxyglucose (FDG). Patients were divided into 2 groups using median split on Marlowe & Crown's Social Desirability Scale (MC), controlling for age, gender, and for severity of depression and anxiety, the possible two major influential factors. A group comparison of the regional cerebral activity was calculated on a voxel-by-voxel basis using statistical parametric mapping (SPM).

RESULTS

The subgroup comparison showed that the high social desirability was associated with relatively increased metabolism in the cortical regions in the prefrontal, temporal and occipital lobes as well as in the anterior cingulate gyrus.

CONCLUSIONS

High social desirability seems to be associated with increased activity in the prefrontal and other cortical areas. The finding is in an accordance with previous studies that demonstrated an association between prefrontal damage and anti-social behavior. Functional neuroimaging seems to be useful not only for psychiatric evaluation of major factors such as depression and anxiety but also for further psychosocial factors in cancer patients.