Age-Related Deficits in Binaural Hearing: Contribution of Peripheral and Central Effects

Pure-tone audiograms often poorly predict elderly humans' ability to communicate in everyday complex acoustic scenes. Binaural processing is crucial for discriminating sound sources in such complex acoustic scenes. The compromised perception of communication signals presented above hearing threshold has been linked to both peripheral and central age-related changes in the auditory system. Investigating young and old Mongolian gerbils of both sexes, an established model for human hearing, we demonstrate age-related supra-threshold deficits in binaural hearing using behavioral, electrophysiological, anatomical, and imaging methods. Binaural processing ability was measured as the binaural masking level difference (BMLD), an established measure in human psychophysics. We tested gerbils behaviorally with "virtual headphones," recorded single-unit responses in the auditory midbrain and evaluated gross midbrain and cortical responses using positron emission tomography (PET) imaging. Furthermore, we obtained additional measures of auditory function based on auditory brainstem responses, auditory-nerve synapse counts, and evidence for central inhibitory processing revealed by PET. BMLD deteriorates already in middle-aged animals having normal audiometric thresholds and is even worse in old animals with hearing loss. The magnitude of auditory brainstem response measures related to auditory-nerve function and binaural processing in the auditory brainstem also deteriorate. Furthermore, central GABAergic inhibition is affected by age. Because the number of synapses in the apical turn of the inner ear was not reduced in middle-aged animals, we conclude that peripheral synaptopathy contributes little to binaural processing deficits. Exploratory analyses suggest increased hearing thresholds, altered binaural processing in the brainstem and changed central GABAergic inhibition as potential contributors.

Brain MRI in Progressive Supranuclear Palsy with Richardson's Syndrome and Variant Phenotypes

BACKGROUND

Brain magnetic resonance imaging (MRI) is used to support the diagnosis of progressive supranuclear palsy (PSP). However, the value of visual descriptive, manual planimetric, automatic volumetric MRI markers and fully automatic categorization is unclear, particularly regarding PSP predominance types other than Richardson's syndrome (RS).

OBJECTIVES

To compare different visual reading strategies and automatic classification of T1-weighted MRI for detection of PSP in a typical clinical cohort including PSP-RS and (non-RS) variant PSP (vPSP) patients.

METHODS

Forty-one patients (21 RS, 20 vPSP) and 46 healthy controls were included. Three readers using three strategies performed MRI analysis: exclusively visual reading using descriptive signs (hummingbird, morning-glory, Mickey-Mouse), visual reading supported by manual planimetry measures, and visual reading supported by automatic volumetry. Fully automatic classification was performed using a pre-trained support vector machine (SVM) on the results of atlas-based volumetry.

RESULTS

All tested methods achieved higher specificity than sensitivity. Limited sensitivity was driven to large extent by false negative vPSP cases. Support by automatic volumetry resulted in the highest accuracy (75.1% ± 3.5%) among the visual strategies, but performed not better than the midbrain area (75.9%), the best single planimetric measure. Automatic classification by SVM clearly outperformed all other methods (accuracy, 87.4%), representing the only method to provide clinically useful sensitivity also in vPSP (70.0%).

CONCLUSIONS

Fully automatic classification of volumetric MRI measures using machine learning methods outperforms visual MRI analysis without and with planimetry or volumetry support, particularly regarding diagnosis of vPSP, suggesting the use in settings with a broad phenotypic PSP spectrum. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Automatic covariance pattern analysis outperforms visual reading of 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET) in variant progressive supranuclear palsy

BACKGROUND

To date, studies on positron emission tomography (PET) with 18 F-fluorodeoxyglucose (FDG) in progressive supranuclear palsy (PSP) usually included PSP cohorts overrepresenting patients with Richardson's syndrome (PSP-RS).

OBJECTIVES

To evaluate FDG-PET in a patient sample representing the broad phenotypic PSP spectrum typically encountered in routine clinical practice.

METHODS

This retrospective, multicenter study included 41 PSP patients, 21 (51%) with RS and 20 (49%) with non-RS variants of PSP (vPSP), and 46 age-matched healthy controls. Two state-of-the art methods for the interpretation of FDG-PET were compared: visual analysis supported by voxel-based statistical testing (five readers) and automatic covariance pattern analysis using a predefined PSP-related pattern.

RESULTS

Sensitivity and specificity of the majority visual read for the detection of PSP in the whole cohort were 74% and 72%, respectively. The percentage of false-negative cases was 10% in the PSP-RS subsample and 43% in the vPSP subsample. Automatic covariance pattern analysis provided sensitivity and specificity of 93% and 83% in the whole cohort. The percentage of false-negative cases was 0% in the PSP-RS subsample and 15% in the vPSP subsample.

CONCLUSIONS

Visual interpretation of FDG-PET supported by voxel-based testing provides good accuracy for the detection of PSP-RS, but only fair sensitivity for vPSP. Automatic covariance pattern analysis outperforms visual interpretation in the detection of PSP-RS, provides clinically useful sensitivity for vPSP, and reduces the rate of false-positive findings. Thus, pattern expression analysis is clinically useful to complement visual reading and voxel-based testing of FDG-PET in suspected PSP. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Bifrontal electroconvulsive therapy leads to improvement of cerebral glucose hypometabolism in frontotemporal dementia with comorbid psychotic depression - a case report

BACKGROUND

Differentiating depression and dementia in elderly patients represents a major clinical challenge for psychiatrists. Pharmacological and non-pharmacological treatment options for both conditions are often used cautiously due to fear of adverse effects. If a clinically indicated therapy is not initiated due to fear of adverse effects, the quality of life of affected patients may significantly be reduced.

CASE PRESENTATION

Here, we describe the case of a 65-year-old woman who presented to the department of psychiatry of a university hospital with depressed mood, pronounced anxiety, and nihilistic thoughts. While several pharmacological treatments remained without clinical response, further behavioral observation in conjunction with ¹⁸F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) revealed the diagnosis of frontotemporal dementia (FTD). To counter the pharmacological treatment resistance of psychotic depression, we decided to perform electroconvulsive therapy (ECT). Remarkably, ten sessions of ECT yielded an almost complete remission of depressive symptoms. In addition, the patient's delusional ideas disappeared. A follow-up ¹⁸F-FDG PET/CT after the ECT series still showed a frontally and parieto-temporally accentuated hypometabolism, albeit with a clear regression compared to the previous image. The follow-up ¹⁸F-FDG PET/CT thus corroborated the diagnosis of FTD, while on the other hand it demonstrated the success of ECT.

CONCLUSIONS

In this case, ECT was a beneficial treatment option for depressive symptoms in FTD. Also, ¹⁸F-FDG PET/CT should be discussed as a valuable tool in differentiating depression and dementia and as an indicator of treatment response.

Case report: Early-onset Parkinson's disease with initial spastic paraparesis and hyperreflexia caused by compound heterozygous PRKN-gene exon 2 and 4 deletions

Pathogenic variants in the Parkin-gene (PRKN) are among the most common genetic causes of early onset Parkinson's disease (EOPD). Patients with EOPD can present with atypical clinical features and misdiagnosis is frequent. Here, we report a clinical phenotype with atypical signs and symptoms of a 35-year-old male patient with EOPD caused by a compound heterozygous PRKN-gene deletion of exons 2 and 4. After the initial diagnosis of stiff person syndrome, the patient was admitted to our department for a second opinion after 8 years of untreated disease progression. The patient presented with prominent spastic paraparesis pronounced on the right side and hyperreflexia as well as Parkinsonism with rigidity predominantly affecting the upper limbs, bradykinesia, and resting tremor. In the diagnostic assessment, magnetic evoked potentials to the anterior tibial muscles showed a low amplitude on the right side, compatible with pyramidal tract disturbance. However, an MRI of the head and the spine did not show any pathologies or atrophy. A [123I] FP-CIT SPECT scan revealed profoundly and left-pronounced reduced striatal uptake suggesting a neurodegenerative Parkinson's syndrome. Even though an acute levodopa challenge did not show marked improvement of symptoms, the chronic levodopa challenge with up to 450 mg/day significantly reduced the rigidity and bradykinesia. Surprisingly, spastic paraparesis and hyperreflexia diminished under dopaminergic treatment. Finally, genetic analysis by next-generation sequencing via copy number variant analysis (CNV) and multiplex ligation-dependent probe amplification (MLPA) confirmed compound heterozygous deletions of exons 2 and 4 in the PRKN-gene. As presented in this case, the awareness of atypical clinical symptoms of EOPD is essential to prevent misdiagnosis in young patients.

An unusual presentation of Huntington's disease

We describe the case of a 59-year-old woman who exhibited psychotic symptoms, cognitive dysfunction, and restlessness. While the clinical picture and 18F-FDG PET/CT suggested the presence of a tauopathy, especially frontotemporal dementia or progressive supranuclear palsy, genetic testing eventually revealed Huntington's disease.

Reduced microglia activity in patients with long-term immunosuppressive therapy after liver transplantation

Purpose

Calcineurin inhibitors (CNI) can cause long-term impairment of brain function. Possible pathomechanisms include alterations of the cerebral immune system. This study used positron emission tomography (PET) imaging with the translocator protein (TSPO) ligand ¹⁸F-GE-180 to evaluate microglial activation in liver-transplanted patients under different regimens of immunosuppression.

Methods

PET was performed in 22 liver-transplanted patients (3 CNI free, 9 with low-dose CNI, 10 with standard-dose CNI immunosuppression) and 9 healthy controls. The total distribution volume (V_T) estimated in 12 volumes-of-interest was analyzed regarding TSPO genotype, CNI therapy, and cognitive performance.

Results

In controls, V_T was about 80% higher in high affinity binders (n = 5) compared to mixed affinity binders (n = 3). Mean V_T corrected for TSPO genotype was significantly lower in patients compared to controls, especially in patients in whom CNI dose had been reduced because of nephrotoxic side effect.

Conclusion

Our results provide evidence of chronic suppression of microglial activity in liver-transplanted patients under CNI therapy especially in patients with high sensitivity to CNI toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05398-w.

Combined Brain-Perfusion SPECT and EEG Measurements Suggest Distinct Strategies for Speech Comprehension in CI Users With Higher and Lower Performance

Cochlear implantation constitutes a successful therapy of inner ear deafness, with the majority of patients showing good outcomes. There is, however, still some unexplained variability in outcomes with a number of cochlear-implant (CI) users, showing major limitations in speech comprehension. The current study used a multimodal diagnostic approach combining single-photon emission computed tomography (SPECT) and electroencephalography (EEG) to examine the mechanisms underlying speech processing in postlingually deafened CI users (N = 21). In one session, the participants performed a speech discrimination task, during which a 96-channel EEG was recorded and the perfusions marker 99mTc-HMPAO was injected intravenously. The SPECT scan was acquired 1.5 h after injection to measure the cortical activity during the speech task. The second session included a SPECT scan after injection without stimulation at rest. Analysis of EEG and SPECT data showed N400 and P600 event-related potentials (ERPs) particularly evoked by semantic violations in the sentences, and enhanced perfusion in a temporo-frontal network during task compared to rest, involving the auditory cortex bilaterally and Broca's area. Moreover, higher performance in testing for word recognition and verbal intelligence strongly correlated to the activation in this network during the speech task. However, comparing CI users with lower and higher speech intelligibility [median split with cutoff + 7.6 dB signal-to-noise ratio (SNR) in the Göttinger sentence test] revealed for CI users with higher performance additional activations of parietal and occipital regions and for those with lower performance stronger activation of superior frontal areas. Furthermore, SPECT activity was tightly coupled with EEG and cognitive abilities, as indicated by correlations between (1) cortical activation and the amplitudes in EEG, N400 (temporal and occipital areas)/P600 (parietal and occipital areas) and (2) between cortical activation in left-sided temporal and bilateral occipital/parietal areas and working memory capacity. These results suggest the recruitment of a temporo-frontal network in CI users during speech processing and a close connection between ERP effects and cortical activation in CI users. The observed differences in speech-evoked cortical activation patterns for CI users with higher and lower speech intelligibility suggest distinct processing strategies during speech rehabilitation with CI.

Severe Progressive Multifocal Leukoencephalopathy (PML) and Spontaneous Immune Reconstitution Inflammatory Syndrome (IRIS) in an Immunocompetent Patient

Background: Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection with JC-virus (JCV), a papova-virus, affecting mostly oligodendrocytes and the white matter of the central nervous system. Progressive Multifocal Leukoencephalopathy (PML) almost exclusively occurs in immunocompromised patients based on different underlying conditions of severe cellular immunodeficiency such as HIV/AIDS, secondary to neoplastic and autoimmune diseases, or during immunosuppressive therapy.

Case presentation: We present the case of an otherwise healthy and immunocompetent patient without immunosuppressive therapy who was admitted with hemianopsia to the right side, sensory aphasia and changes of behavior. Magnet resonance imaging (MRI) and laboratory testing confirmed the diagnosis of PML, although functional tests did not show any evidence for cellular immunodeficiency. Extensive immunological tests did not reveal an apparent immunodeficiency. During symptomatic therapy the patient developed seizures which were assumed to be caused by a spontaneous immune reconstitution inflammatory syndrome (IRIS) demonstrated by MRI. We added a high dose of intravenous corticosteroids to the antiepileptic treatment and seizures ended shortly thereafter. However, the impairments of vision, behavior and language persisted.

Conclusions: Our case report highlights that an apparently immunocompetent patient can develop PML and IRIS spontaneously. Therefore, MRI should be applied immediately whenever a rapid progression of PML symptoms occurs as treatment of IRIS with corticosteroids can result in a marked clinical improvement.

Visualization of the auditory pathway in rats with 18F-FDG PET activation studies based on different auditory stimuli and reference conditions including cochlea ablation

Activation studies with positron emission tomography (PET) in auditory implant users explained some of the mechanisms underlying the variability of achieved speech comprehension. Since future developments of auditory implants will include studies in rodents, we aimed to inversely translate functional PET imaging to rats. In normal hearing rats, activity in auditory and non-auditory regions was studied using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET with 3 different acoustic conditions: sound attenuated laboratory background, continuous white noise and rippled noise. Additionally, bilateral cochlea ablated animals were scanned. 3D image data were transferred into a stereotaxic standard space and evaluated using volume of interest (VOI) analyses and statistical parametric mapping (SPM). In normal hearing rats alongside the auditory pathway consistent activations of the nucleus cochlearis (NC), olivary complex (OC) and inferior colliculus (IC) were seen comparing stimuli with background. In this respect, no increased activation could be detected in the auditory cortex (AC), which even showed deactivation with white noise stimulation. Nevertheless, higher activity in the AC in normal hearing rats was observed for all 3 auditory conditions against the cochlea ablated status. Vice versa, in ablated status activity in the olfactory nucleus (ON) was higher compared to all auditory conditions in normal hearing rats. Our results indicate that activations can be demonstrated in normal hearing animals based on ¹⁸F-FDG PET in nuclei along the central auditory pathway with different types of noise stimuli. However, in the AC missing activation with respect to the background advises the need for more rigorous background noise attenuation for non-invasive reference conditions. Finally, our data suggest cross-modal activation of the olfactory system following cochlea ablation–underlining, that ¹⁸F-FDG PET appears to be well suited to study plasticity in rat models for cochlear implantation.

Activation in the auditory pathway of the gerbil studied with 18F-FDG PET: effects of anesthesia

Here, we present results from an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) study in the Mongolian gerbil, a preferred animal model in auditory research. One major issue in preclinical nuclear imaging, as well as in most of the neurophysiological methods investigating auditory processing, is the need of anesthesia. We compared the usability of two types of anesthesia which are frequently employed in electrophysiology, ketamine/xylazine (KX), and fentanyl/midazolam/medetomidine (FMM), for valid measurements of auditory activation with ¹⁸F-FDG PET. Gerbils were placed in a sound-shielding box and injected with ¹⁸F-FDG. Two acoustic free-field conditions were used: (1) baseline (no stimulation, 25 dB background noise) and (2) 90 dB frequency-modulated tones (FM). After 40 min of ¹⁸F-FDG uptake, a 30 min acquisition was performed using a small animal PET/CT system. Blood glucose levels were measured after the uptake phase before scanning. Standardized uptake value ratios for relevant regions were determined after implementing image and volume of interest templates. Scans demonstrated a significantly higher uptake in the inferior colliculus with FM stimulation compared to baseline in awake subjects (+ 12%; p = 0.02) and with FMM anesthesia (+ 13%; p = 0.0012), but not with KX anesthesia. In non-auditory brain regions, no significant difference was detected. Blood glucose levels were significantly higher under KX compared to FMM anesthesia (17.29 ± 0.42 mmol/l vs. 14.30 ± 1.91 mmol/l; p = 0.024). These results suggest that valid ¹⁸F-FDG PET measurements of auditory activation comparable to electrophysiology can be obtained from gerbils during opioid-based anesthesia due to its limited effects on interfering blood glucose levels.

Feasibility of 15O-water PET studies of auditory system activation during general anesthesia in children

Background

¹⁵O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of ¹⁵O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered.

Results

It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p < 0.05 or p < 0.01 vs. p < 0.001) had to be applied. However, this lower cut-off was frequently associated with unexpected, “artificial” activations in eAR. These activations in eAR could be slightly reduced by the use of a stronger smoothing filter kernel during preprocessing of the data (e.g., [30 mm]³).

Conclusions

Our data indicate that it is feasible to detect auditory cortex activations in ¹⁵O-water PET during general anesthesia. Combined with the improved signal to noise ratios of modern PET scanners, this suggests reasonable prospects for further evaluation of the method for clinical use in auditory implant users. Adapted parameters for data analysis seem to be helpful to improve the proportion of signals in AR versus eAR.

Thyreoglobulin, 131J-Ganzkörperszintigraphie und Risikofaktoren in der Nachsorge des differenzierten Schilddrüsenkarzinoms

In einer retrospektiven Studie wurden Ergebnisse der 131J-Ganzkörperszintigraphie und der Bestimmung des Thyreoglobulins (Tg) in der Nachsorge von 85 Patienten mit differenziertem Schilddrüsenkarzinom untersucht. Alle Patienten waren nach abgeschlossener Therapie zunächst als tumorfrei eingestuft worden. Bei 11 Patienten trat jedoch im weiteren Verlauf ein Rezidiv auf. Von 24 wegen Rezidivverdachts durchgeführten 131J-Szintigraphien ergaben 5 die Lokalisation eines Rezidivs. Im Rahmen von 71 Routineuntersuchungen unter endogener TSH-Stimulation konnte in zwei Fällen jeweils ein Jahr nach abgeschlossener Therapie ein neuer pathologischer Befund erhoben werden. 10 der 11 Rezidive traten in einer high-risk Gruppe von 40 Patienten mit follikulärer Histologie oder Stadium III oder IV (UICC 1987) auf. Nur ein Rezidiv wurde in einer low-risk Gruppe von 41 Patienten mit papillärer Histologie und UICC-Stadium I oder II beobachtet. Später als ein Jahr nach Abschluß der Therapie wurde kein Rezidiv bei einem Patienten der low-risk Gruppe beobachtet. Die vorliegenden Ergebnisse sprechen für die Notwendigkeit von 131J-Szintigraphie und Tg-Bestimmung unter endogener TSH-Stimulation bei Rezidivverdacht und routinemäßig etwa ein Jahr nach der letzten Therapie bei allen Patienten. Bei unauffälligem Verlauf sollte jedoch später diese Diagnostik routinemäßig nur bei erhöhtem Rezidivrisiko durchgeführt werden. Mit einer cut-off Grenze zur Bewertung des Tg-Spiegels von 5 ng/ml im Vergleich zung/ml nahm die Zahl der falsch-negativen Tg-Befunde unter Suppressionstherapie deutlicher ab, als diejenige der »falsch-positiven« Befunde zunahm. Eine cut-off Grenze von 5 ng/ml dürfte notwendig sein, um die Zahl der falschnegativen Tg-Befunde zu minimieren; es ist zu hoffen, daß durch die neuen sensitiven IRMA-Methoden die Zahl der »falsch-positiven« Befunde verringert werden wird.

Ergebnisse der Radiojodtherapie der manifesten Hyperthyreose und der autonomen Struma mit Euthyreose

In 200 patients follow-up examinations were performed up to one year after radioiodine therapy (RITh) with individual dose calculation. The mean applied dose was significantly lower in patients with immunogenic hyperthyroidism (Graves’ disease) as compared to patients with non-immunogenic hyperthyroidism (disseminated/multifocal autonomy, HYDA). In Graves’ disease the rate of recurrent hyperthyroidism was significantly higher and that of posttreatment hypothyroidism lower. Considering the high recurrence rate in Graves’ disease a higher dose, e. g. 150 Gy, seems to be appropriate. In patients with HYDA who received antithyroid drugs during RITh, recurrence of hyperthyroidism appeared slightly more, and posttreatment hypothyroidism slightly less, frequent. The efficiency of RITh was not significantly reduced by additional treatment with antithyroid drugs. Posttreatment hypothyroidism in patients with euthyroid goiter and disseminated/multifocal autonomy (EUDA) occurred significantly more frequent if the basal TSH level was ≥0.5 µlE/ml before therapy. The goiter size was reduced independent of the basal TSH level. In this group protection by thyroxine could avoid posttreatment hypothyroidism without impairing the reduction of goiter. In HYDA patients after thyroid surgery recurrence appeared less, and in those with EUDA posttreatment hypothyroidism significantly more, frequent. A lower dose seems to be suitable in patients who underwent thyroid surgery before. In patients with focal autonomy after RITh no recurrence of hyperthyroidism was observed. In 9% a suppressed basal TSH level indicating persistent autonomy was seen. Posttreatment hypothyroidism in focal autonomy appeared only in patients without manifest hyperthyroidism before RITh and was significantly more frequent in this group as compared to the other groups of patients. In patients with focal autonomy who developed hypothyroidism the dose calculation was based on a significantly higher volume of the adenoma. In 3 cases cystic parts of the adenoma were not subtracted. This caused a higher radiation dose to the paranodular tissue, which might have been one reason for the high rate of posttreatment hypothyroidism in this group of patients.

[18F]Fluoride PET Indicates Reduced Bone Formation in Severe Glucocorticoid-induced Osteoporosis

A 61-year-old female patient presenting with mixed connective tissue disease (Sharp syndrome), underwent a long-term high dose glucocorticoid treatment because of multiple organ manifestations. Under steroid therapy she developed severe osteoporosis resulting in multiple fractures. A dynamic [18F]fluoride PET study in this patient revealed reduced fluoride influx in non-fractured vertebrae. This finding corresponds to pathogenetic concepts which propose an inhibition of bone formation as major cause of glucocorticoid-induced osteoporosis. In the light of the presented case it seems to be promising to evaluate the diagnostic benefit of [18F]fluoride PET in osteoporosis.

123I-IBZM SPECT: Reconstruction Methodology and Results in Parkinsonism and Dystonia

In 58 patients with Parkinsonism or dystonia striatal dopamine D2 receptors were investigated using 123l-iodobenzamide (123I-IBZM) single-photon emission computed tomography (SPECT). The influence of SPECT reconstruction methodology on semiquantification and the clinical value of 123I-IBZM SPECT were evaluated. Delineation of the striatal uptake and striatum/frontal cortex (ST/FC) ratios were improved by the use of compensation procedures for scatter and attenuation as well as the choice of an adequate filter. Satisfactory results were achieved using a Metz prefilter with a comparatively high order number (i. e. high cut-off and low suppression of higher frequencies via roll-off). Regarding clinical diagnoses it was not possible to differentiate between advanced idiopathic Parkinson’s disease (IP) and Parkinsonism of other aetiology (OP) on the basis of 123I-IBZM SPECT. But patients with IP and favourable response to L-Dopa showed significantly higher ST/FC ratios than those with fluctuating response. In patients with dystonia ST/FC ratios were significantly higher compared to patients with IP or OP.

Assessment of the incorporation of revascularized fibula grafts used for mandibular reconstruction with F-18-PET

Aim: Determination of the range of regional blood flow and fluoride influx during normal incorporation of revascularized fibula grafts used for mandibular reconstruction. Evaluation, if healing complications are preceded by typical deviations of these parameters from the normal range. Assessment of the potential influence of using “scaled population-derived” instead of “individually measured” input functions in quantitative analysis. Methods: Dynamic F-l 8-PET images and arterialized venous blood samples were obtained in 11 patients early and late after surgery. Based on kinetic modeling regional blood flow (K1) and fluoride influx (Kmlf) were determined. Results: In uncomplicated cases, early postoperative graft K1 - but not Kmlf -exceeded that of vertebrae as reference region. Kmn values obtained in graft necrosis (n = 2) were below the ranges of values observed in uncomplicated healing (0.01 13-0.0745 ml/min/ml) as well as that of the reference region (0.0154-0.0748). Knf values in mobile non-union were in the lower range - and those in rigid non-union in the upper range of values obtained in stable union (0.021 1-0.0694). If scaled population-derived instead of measured input functions were used for quantification, mean deviations of 23 ± 17% in K1 and 12 ± 16% in Kmlf were observed. Conclusions: Normal healing of predominantly cortical bone transplants is characterized by relatively low osteoblastic activity together with increased perfusion. It may be anticipated that transplant necrosis can be identified by showing markedly reduced F− influx. In case that measured input functions are not available, quantification with scaled population-derived input functions is appropriate if expected differences in quantitative parameters exceed 70%.

[123I]β-CIT SPECT imaging of dopamine and serotonin transporters in Parkinson’s disease and multiple system atrophy

Aims: Definition of the regional pattern of dopamine transporter (DAT) dysfunction in advanced Parkinson’s disease (PD) and evaluation of a potential correlation between DAT binding and symptoms; elucidation of the role of DAT imaging in the differential diagnosis of PD and multiple system atrophy (MSA); assessment and comparison of serotonin transporter (SERT) binding in PD and MSA. Methods: [123I]ß-CIT SPECT was performed in 14 patients with advanced PD, 10 with moderate MSA and 20 healthy persons. Specific to nonspecific tracer binding ratios (V3’’) were calculated via ROI analysis of uptake images at 4 h (SERT binding) and 24 h (DAT binding) p. i. Results: In PD bilateral reduction of striatal DAT binding (63-70%) was seen. The caudate ipsilateral to the clinically predominantly affected side showed relatively the least impairment. Significant correlations (r = -0.54 to -0.64) between DAT binding and Hoehn and Yahr stage, UPDRS-scores and duration of disease were found. In MSA DAT binding was less reduced (40-48%) targeting the putamen contralateral to the side of clinical predominance. Significantly lower SERT binding was observed in PD midbrain and MSA hypothalamus compared to controls – and in MSA relative to PD mesial frontal cortex. Conclusions: In advanced PD striatal DAT binding is markedly reduced with the least reduction in caudate ipsilateral to the clinically predominantly affected side. In moderate MSA with asymmetrical symptoms DAT dysfunction is predominant in the contralateral putamen, a pattern seen in early PD. The reduction of SERT in the midbrain area of PD patients suggests additional tegmental degeneration while in MSA the serotonergic system seems to be more generally affected.

Imaging in hearing using radiotracers

Radiotracers offer unique options for brain imaging of functional and molecular processes related to hearing. Such imaging can be applied in a broad spectrum of situations from preclinical research to clinical patient care. Functional imaging to assess activation in brain regions and networks involved in auditory processing uses markers of blood flow or energy-metabolism in well-defined conditions with and without auditory stimulation. Molecular markers can be used in hearing research for example to study changes in inhibitory neurotransmission systems related to hearing loss. For imaging either positron emission tomography (PET) or single-photon emission computed tomography (SPECT) are employed. Data analysis can encompasses voxel-wise statistical analysis of activation and calculation of quantitative parameters like receptor binding-potentials based on bio-kinetic modeling. Functional imaging has been frequently used in the context of auditory implantation. Before implantation it aims to assess intactness of the central auditory pathway and prognosis. After implantation it is used to improve understanding of the outcome with respect to auditory function and finally speech understanding, e.g. by measuring correlates of central auditory processing and neuroplasticity.

Cerebral microglia activation in hepatitis C virus infection correlates to cognitive dysfunction

Hepatitis C virus (HCV) infection may induce chronic fatigue and cognitive dysfunction. Virus replication was proven within the brain and HCV-positive cells were identified as microglia and astrocytes. We hypothesized that cerebral dysfunction in HCV-afflicted patients is associated with microglia activation. Microglia activation was assessed in vivo in 22 patients with chronic HCV infection compared to six healthy controls using [(11) C]-PK11195 Positron Emission Tomography (PET) combined with magnetic resonance tomography for anatomical localization. Patients were subdivided with regard to their PCR status, Fatigue Impact Scale score (FIS) and attention test sum score (ATS). A total of 12 patients (54.5%) were HCV PCR positive [of which 7 (58.3%) had an abnormal FIS and 7 (58.3%) an abnormal ATS], 10 patients (45.5%) were HCV PCR negative (5 (50%) each with an abnormal FIS or ATS). Patients without attention deficits showed a significantly higher accumulation of [(11) C]-PK11195 in the putamen (P = 0.05), caudate nucleus (P = 0.03) and thalamus (P = 0.04) compared to controls. Patients with and without fatigue did not differ significantly with regard to their specific tracer binding in positron emission tomography. Preserved cognitive function was associated with significantly increased microglia activation with predominance in the basal ganglia. This indicates a probably neuroprotective effect of microglia activation in HCV-infected patients.

Effect of Deep Brain Stimulation on Regional Cerebral Blood Flow in Patients with Medically Refractory Tourette Syndrome

In this study, alterations in brain perfusion have been investigated in patients with Tourette syndrome (TS) compared with control subjects. In addition, we investigated the effects of deep brain stimulation (DBS) in both globus pallidus internus (GPi) and centromedian-parafascicular/ventralis oralis internus nuclei of the thalamus (CM/Voi) and sham (SHAM) stimulation on cerebral blood flow. In a prospective controlled, randomized, double-blind setting, five severely affected adult patients with TS with predominant motor or vocal tics (mean total tic score on the Yale Global Tic Severity Scale: 39) underwent serial brain perfusion single photon emission computed tomography with (99m)Tc-ECD. Results were compared with data from six age-matched control subjects. All patients were investigated at four different time points: once before DBS implantation (preOP) and three times postoperatively. Postoperative scans were performed in a randomized order, each after 3 months of either GPi, CM/Voi, or SHAM stimulation. At each investigation, patients were injected at rest while awake, but scanned during anesthesia. This procedure ensured that neither anesthesia nor movement artifacts influenced our results. Control subjects were investigated only once at baseline (without DBS or anesthesia). At baseline, cerebral blood flow was significantly reduced in patients with TS (preOP) compared with controls in the central region, frontal, and parietal lobe, specifically in Brodmann areas 1, 4-9, 30, 31, and 40. Significantly increased perfusion was found in the cerebellum. When comparing SHAM stimulation to preOP condition, we found significantly decreased perfusion in basal ganglia and thalamus, but increased perfusion in different parts of the frontal cortex. Compared with SHAM condition both GPi and thalamic stimulation resulted in a significant decrease in cerebral blood flow in basal ganglia and cerebellum, while perfusion in the frontal cortex was significantly increased. Our results provide substantial evidence that, in TS, brain perfusion is altered in the frontal cortex and the cerebellum and that these changes can be reversed by both GPi and CM/Voi DBS.

Diagnostic accuracy of cadmium-zinc-telluride-based myocardial perfusion SPECT: impact of attenuation correction using a co-registered external computed tomography

INTRODUCTION

Computed tomography (CT)-based attenuation correction (AC) improves the accuracy of standard myocardial perfusion SPECT. Most dedicated cadmium-zinc-telluride (CZT) SPECT cameras are not equipped with an integrated CT component. We aimed to determine the impact of AC on diagnostic performance of CZT SPECT using co-registration with an external low-dose CT.

METHODS

Sixty patients underwent CZT SPECT (GE Discovery 530c) with (99m)Tc-sestamibi at rest and following regadenoson stress. Using commercial software, SPECT images were co-registered with a low-dose CT acquired on a separate system (GE Discovery 670NMCT). Attenuation corrected and non-corrected (NC) images were reconstructed using an iterative algorithm. Accuracy was measured in 44 patients who had undergone invasive angiography within 6 months. Normalcy was compared in the remaining 16 patients who had a low pre-test likelihood (<5%) of coronary artery disease (CAD).

RESULTS

Summed stress and rest scores were significantly lower in AC images (9 ± 8 vs. 13 ± 9 and 6 ± 7 vs. 10 ± 9, P = 0.01), while summed difference score did not differ. According to angiography, 38 patients had significant CAD in 71 vascular territories. Attenuation correction improved accuracy globally (P = 0.03) and in RCA territory (P = 0.008). Specificity improved both globally (100 vs. 40%, P < 0.05) and in each individual territory (LAD: 63 vs. 36%, LCX: 70 vs. 33%, RCA: 81 vs. 19%, P < 0.01). Normalcy was 100% for AC and 62.5% for NC images (P < 0.05).

CONCLUSION

Attenuation correction with a co-registered external CT is feasible using CZT cameras and improves diagnostic accuracy mostly by improving specificity over uncorrected images.

Positron Emission Tomography Imaging Reveals Auditory and Frontal Cortical Regions Involved with Speech Perception and Loudness Adaptation

Considerable progress has been made in the treatment of hearing loss with auditory implants. However, there are still many implanted patients that experience hearing deficiencies, such as limited speech understanding or vanishing perception with continuous stimulation (i.e., abnormal loudness adaptation). The present study aims to identify specific patterns of cerebral cortex activity involved with such deficiencies. We performed O-15-water positron emission tomography (PET) in patients implanted with electrodes within the cochlea, brainstem, or midbrain to investigate the pattern of cortical activation in response to speech or continuous multi-tone stimuli directly inputted into the implant processor that then delivered electrical patterns through those electrodes. Statistical parametric mapping was performed on a single subject basis. Better speech understanding was correlated with a larger extent of bilateral auditory cortex activation. In contrast to speech, the continuous multi-tone stimulus elicited mainly unilateral auditory cortical activity in which greater loudness adaptation corresponded to weaker activation and even deactivation. Interestingly, greater loudness adaptation was correlated with stronger activity within the ventral prefrontal cortex, which could be up-regulated to suppress the irrelevant or aberrant signals into the auditory cortex. The ability to detect these specific cortical patterns and differences across patients and stimuli demonstrates the potential for using PET to diagnose auditory function or dysfunction in implant patients, which in turn could guide the development of appropriate stimulation strategies for improving hearing rehabilitation. Beyond hearing restoration, our study also reveals a potential role of the frontal cortex in suppressing irrelevant or aberrant activity within the auditory cortex, and thus may be relevant for understanding and treating tinnitus.

Characterizing the inflammatory tissue response to acute myocardial infarction by clinical multimodality noninvasive imaging

BACKGROUND

Myocardial infarction (MI) triggers a systemic inflammatory response which determines subsequent healing. Experimentally, cardiac positron emission tomography and magnetic resonance imaging have been used successfully to obtain mechanistic insights. We explored the translational potential in patients early after MI.

METHODS AND RESULTS

Positron emission tomography/computed tomography and cardiac magnetic resonance were performed in 15 patients <7 days after first MI. Cardiac magnetic resonance showed regional transmural late gadolinium enhancement and edema exceeding the area of late gadolinium enhancement. Using F-18 deoxyglucose with heparin pretreatment, metabolic rate of glucose (MRGlc) was significantly increased in infarct versus remote myocardium (median, 2.0 versus 0.4 mg/min per 100 mL; P=0.0001). MRGlc in infarct correlated with remote myocardium (ρ=0.64; P=0.01), spleen (ρ=0.82; P=0.0002), and bone marrow(ρ=0.57; P=0.03), but not with muscle or liver. Regionally, F-18 deoxyglucose score was highest in segments with late gadolinium enhancement versus edema only and remote (median, 2.0 versus 1.8 versus 0.4; P<0.0001). Patients requiring repeat intervention during preliminary follow-up of 11±5 months tended to have higher early post-MI MRGlc. Five patients with chronic, stable MI served as controls. Opposite to acute MI, MRGlc was lower in infarct (median infarct/remote ratio, 0.6 versus 3.2 for acute MI; P=0.001), and there was no correlation with bone marrow or spleen MRGlc.

CONCLUSIONS

Increased glucose utilization after heparin-induced suppression of myocyte uptake appears to mostly reflect inflammatory activity in damaged myocardium early after MI. Consistent with prior preclinical observations, and in contrast to chronic MI, this is associated with activity in spleen and bone marrow as sources of inflammatory cells. Positron emission tomography and cardiac magnetic resonance multimodality characterization of the acutely infarcted, inflamed myocardium may provide multiparametric end points for clinical studies aiming at support of infarct healing.

Anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis show distinct patterns of brain glucose metabolism in 18F-fluoro-2-deoxy-d-glucose positron emission tomography

Background

Pathogenic autoantibodies targeting the recently identified leucine rich glioma inactivated 1 protein and the subunit 1 of the N-methyl-D-aspartate receptor induce autoimmune encephalitis. A comparison of brain metabolic patterns in ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography of anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis patients has not been performed yet and shall be helpful in differentiating these two most common forms of autoimmune encephalitis.

Methods

The brain ¹⁸F-fluoro-2-deoxy-d-glucose uptake from whole-body positron emission tomography of six anti-N-methyl-D-aspartate receptor encephalitis patients and four patients with anti-leucine rich glioma inactivated 1 protein encephalitis admitted to Hannover Medical School between 2008 and 2012 was retrospectively analyzed and compared to matched controls.

Results

Group analysis of anti-N-methyl-D-aspartate encephalitis patients demonstrated regionally limited hypermetabolism in frontotemporal areas contrasting an extensive hypometabolism in parietal lobes, whereas the anti-leucine rich glioma inactivated 1 protein syndrome was characterized by hypermetabolism in cerebellar, basal ganglia, occipital and precentral areas and minor frontomesial hypometabolism.

Conclusions

This retrospective ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography study provides novel evidence for distinct brain metabolic patterns in patients with anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis.

Repair of segmental long-bone defects by stem cell concentrate augmented scaffolds: a clinical and positron emission tomography--computed tomography analysis

PURPOSE

Treating segmental long-bone defects remains a major challenge. For defects >3 cm, segmental transport represents the gold standard, even though the method is time consuming and afflicted with several complications. The aim of this study was to evaluate healing of such defects after grafting an osteogenic scaffold previously seeded with stem cell concentrate.

METHODS

We evaluated five patients with segmental long-bone defects (3-14 cm) treated with bone marrow aspirate concentrates (BMAC) seeded onto a bovine xenogenous scaffold. The healing process was monitored by X-rays and positron emission tomography-computed tomography (PET-CT) three months after surgery.

RESULTS

Centrifugation led to a concentration of leukocytes by factor 8.1 ± 7.5. Full weight bearing was achieved 11.3 ± 5.0 weeks after surgery. PET analysis showed an increased influx of fluoride by factor 8.3 ± 6.4 compared with the contralateral side (p < 0.01). Bone density in the cortical area was 75 ± 16 % of the contralateral side (p < 0.03). The patient with the largest defect sustained an implant failure in the distal femur and finally accomplished therapy by segmental transport. He also had the lowest uptake of fluoride of the patient collective (2.2-fold increase).

CONCLUSION

Stem cell concentrates can be an alternative to segmental bone transport. Further studies are needed to compare this method with autologous bone grafting and segmental transport.

Deep brain stimulation of nucleus accumbens region in alcoholism affects reward processing

The influence of bilateral deep brain stimulation (DBS) of the nucleus nucleus (NAcc) on the processing of reward in a gambling paradigm was investigated using H₂[¹⁵O]-PET (positron emission tomography) in a 38-year-old man treated for severe alcohol addiction. Behavioral data analysis revealed a less risky, more careful choice behavior under active DBS compared to DBS switched off. PET showed win- and loss-related activations in the paracingulate cortex, temporal poles, precuneus and hippocampus under active DBS, brain areas that have been implicated in action monitoring and behavioral control. Except for the temporal pole these activations were not seen when DBS was deactivated. These findings suggest that DBS of the NAcc may act partially by improving behavioral control.

Estimation of glomerular filtration rate in liver-transplanted children: comparison of simplified procedures using 51Cr-EDTA and endogenous markers with Sapirstein's method as a reference standard

This study evaluated simple procedures for GFR determination in 48 liver-transplanted children. After injection of (51)Cr-EDTA, blood samples were obtained up to four h, and activity retention in the body was measured for 60 min with scintillation probes. As a reference, GFR was calculated according to Sapirstein. Simplified calculations were performed according to Brochner-Mortensen, Russel, Devaux and Oberhausen. Additionally, GFR was determined using plasma creatinine and cystatin C according to Schwartz and Filler, respectively. The reference revealed mildly reduced GFR (62 +/- 20 mL/min/1.73 m(2)). Russel's method provided the highest degree of correlation (r(2) = 0.95), the smallest bias in GFR determination (-2%), and only one false exclusion plus one false diagnosis of chronic kidney disease. Oberhausen's method with blood sampling at one h post-injection performed slightly worse (r(2) = 0.67, bias: 3%). All other methods resulted in significantly different GFR estimates compared to the reference. Nevertheless, notably, the second narrowest 95% limits of agreement (-31% to 45%) was observed using cystatin C. In conclusion, this data implies to prefer Russel's method as a simplified procedure, and if patients cannot be available long enough (four h) for measurements, Oberhausen's method instead. If radiotracer methods are not available at all or for screening GFR, cystatin C appears to be the procedure of choice.

Repair of a segmental long bone defect in human by implantation of a novel multiple disc graft

Large segmental defects of the weight bearing long bones are very difficult to reconstruct. Current treatment options are afflicted with several limitations and disadvantages. We describe a novel approach to regenerate a segmental long bone defect in a patient using a multiple disc graft. Decellularized bovine trabecular bone discs were seeded with autologous bone marrow cells and cultured in a perfusion chamber for three weeks. Multiple cell-seeded discs were implanted to close a 72 mm defect of the distal tibia in a 58-year-old woman, and fixed by an intramedullary nail. Bone formation was assessed non-invasively by plain radiographs and 18F-labeled sodium fluoride-based co-registration of positron emission- and computed tomography (PET/CT). Bone was actively formed around the grafted defect as early as six weeks after surgery. Because the tibia was sufficiently stabilized, the patient was able to freely walk with full weight bearing 6 weeks after surgery. The uneventful two-year follow-up and the satisfaction of the patient demonstrated the success of the procedure. Therefore the use of multiple cell-seeded disc grafts can be considered as a treatment alternative for patients with segmental long bone defects.

Radiotracer imaging studies in hepatic encephalopathy: ISHEN practice guidelines

There is lack of consensus on radiotracer usage in hepatic encephalopathy (HE). We have focused our attention on three main areas: (i) radiotracer imaging in animal models of HE, (ii) methodological issues of radiotracer imaging in HE and (iii) radiotracer imaging studies on the pathophysiology and (new) therapies in HE. We suggest the following: 1. Positron emission tomography (PET) and single photon emission computed tomography lend themselves to the study of animal models of HE, but the models that are suitable depend on the specific research question. Magnetic resonance imaging (MRI) may be a useful alternative technique. 2. Owing to the cost of the technique, there is a need for multicentre human PET studies to overcome the problem of underpowered small studies being undertaken in individual research centres. There should be a unified PET protocol with central, anonymised data analysis in one centre, using validated methodology, on behalf of all participating centres. Such studies would be useful for the assessment of early intervention in patients with subtle neuropsychiatric symptoms, or for clarification of the effect of liver transplantation on HE. 3. While radiotracer imaging modalities remain useful research tools for the study of pathogenesis and for the assessment of treatment effects, there is no consensus on the use of imaging in routine clinical practice for diagnosis and prognosis. The most promising objective tools appear to be magnetic resonance spectroscopy (MRS) and volumetric MRI, which can be performed in multiple centres without the difficulties that radiotracer imaging entail.

Hepatitis C virus infection and the brain

There is growing evidence that hepatitis C virus (HCV)-infection may affect the brain. About half of the HCV-infected patients complain of chronic fatigue irrespective of their stage of liver disease or virus replication rate. Even after successful antiviral therapy fatigue persists in about one third of the patients. Many patients, in addition, report of deficits in attention, concentration and memory, some also of depression. Psychometric testing revealed deficits in attention and verbal learning ability as characteristic for HCV-afflicted patients with normal liver function. Magnetic resonance spectroscopic studies showed alterations of the cerebral choline, N-acetyl-aspartate, and creatine content in the basal ganglia, white matter and frontal cortex, respectively. Recently, pathologic cerebral serotonin and dopamine transporter binding and regional alterations of the cerebral glucose utilisation compatible with alterations of the dopaminergic attentional system were observed. Several studies detected HCV in brain samples or cerebro-spinal fluid. Interestingly, viral sequences in the brain often differed from those in the liver, but were closely related to those found in lymphoid tissue. Therefore, the Trojan horse hypothesis emerged: HCV-infected mononuclear blood cells enter the brain, enabling the virus to reside within the brain (probably in microglia) and to infect brain cells, especially astrocytes.

Correlates of local cerebral blood flow (CBF) in normal pressure hydrocephalus patients before and after shunting--A retrospective analysis of [(15)O]H(2)O PET-CBF studies in 65 patients

OBJECTIVES

Findings in local cerebral blood flow (rCBF) in Normal pressure hydrocephalus (NPH) have always been challenged by the variable and inconsistent relation to clinical symptoms before and after shunt treatment. [(15)O]H(2)O PET data from a consecutive cohort of 65 idiopathic NPH patients were retrospectively analyzed questioning whether the functional status before and after shunt treatment might correlate with local blood flow.

PATIENTS AND METHODS

Using statistical parametric mapping (SPM99, Wellcome Department of Cognitive Neurology, London), the [(15)O]H(2)O uptake was correlated with the preoperative clinical scores, graded according to a modified Stein and Langfitt score. Furthermore, differences in the uptake in the pre-and post-shunt treatment study after seven to 10 days in patients with and without clinical improvement were studied.

RESULTS

A higher clinical score significantly correlated with a reduced tracer uptake in mesial frontal (k=1,239 voxel, Z=4.41) and anterior temporal (k=469, Z=4.07) areas. In the mesial frontal areas, tracer uptake showed significant reciprocal changes in the clinically improved vs. the unimproved patients.

CONCLUSION

Matched with the existing literature, the regional blood flow alterations are suggested relevant to the NPH syndrome and to post-treatment functional changes. The present rCBF findings warrant prospective studies on the accuracy of neuroimaging studies as they may provide a more specific insight into disease mechanisms.

Computed tomography assessment of cerebral perfusion using a distributed parameter tracer kinetics model: validation with H(2)((15))O positron emission tomography measurements and initial clinical experience in patients with acute stroke

We describe a distributed parameter (DP) model for tracer kinetic analysis in brain and validate the derived perfusion values with positron emission tomography (PET) scans. The proposed model is applied on actual clinical cases of hemispheric stroke. Nine patients with experienced transient ischaemic attack or minor stroke and a stenosis of the internal carotid artery were referred for computed tomography (CT) and PET imaging. The applicability of the DP model in clinical practice was tested in seven patients with acute stroke who received a baseline perfusion CT study and a noncontrast follow-up CT study after 2.4+/-1.8 days. The mean blood flow (F) value for all patients with carotid stenosis in the pooled data (54 regions of interest (ROIs)) was 37.9+/-11.2 mL/min per 100 g in perfusion CT and 35.6+/-9.8 mL/min per 100 g in perfusion PET imaging [r=0.77 (P=0.00)]. Regression analysis of the pooled ROIs for every patient revealed significant correlation between F values in seven patients [r=0.50 to 0.79 (r(2)-values ranged from 0.45 to 0.79), (0.01 < or = P < or = 0.05)]. Parametric maps that corresponded to all physiologic parameters were generated for every perfusion CT in the patients with acute stroke using the DP model. The ischaemic area was better delineated in F, intravascular blood volume and lag time (t(lag)) maps. The correlation coefficient comparing the visually outlined regions of abnormality between the t(lag) parametric map and the follow-up CT scans was 0.81 (P=0.003). In conclusion, DP physiological model using more realistic pharmacokinetics is feasible in dynamic contrast-enhanced CT of the brain in patients with acute and chronic cerebrovascular disease.

Bradykinesia in cirrhotic patients with early hepatic encephalopathy is related to a decreased glucose uptake of frontomesial cortical areas relevant for movement initiation

BACKGROUND/AIMS

Bradykinesia is one of the first symptoms of hepatic encephalopathy (HE). Recently it has been suggested that bradykinesia in HE is due to disturbances in movement initiation. Areas involved in self-initiated movement are the motor- and premotor cortex, the supplementary motor cortex, the motor areas of the cingulate gyrus, and part of the frontomesial- and parietal cortex. The present study aimed to test the hypothesis that bradykinesia in HE is due to a functional disturbance of these areas.

METHODS

Fourteen cirrhotics with grade 0-I HE were examined. Patients with alcoholic cirrhosis or concomitant cerebral disorder were excluded. Patients underwent a 3-dimensional computer-assisted movement analysis for forearm pronation and supination, hand tapping and finger tapping and a (18)F-fluorodesoxy-glucose-PET-examination during rest, analysed with statistical parametric mapping (SPM99).

RESULTS

The frequency of finger- and hand tapping was significantly correlated to the glucose metabolism of the motor area of the cingulate gyrus and frontomedial, frontodorsal and parietal cortical areas known to be activated with self-initiated movements. A decrease of movement frequency was associated with a reduction of glucose metabolism within these areas.

CONCLUSIONS

These data support the hypothesis that bradykinesia in cirrhotics with HE is caused by an alteration of movement initiation.

Chorea-acanthocytosis in monozygotic twins: clinical findings and neuropathological changes as detected by diffusion tensor imaging, FDG-PET and 123I-β-CIT-SPECT

We report on two 33 years old monozygotic twins with chorea-acanthocytosis (ChAc) misdiagnosed as schizophrenia and Tourette syndrome, respectively. Although the patients shared several clinical similarities, there were also some clear differences: twin 1 presented initially with an acute episode of a paranoid schizophrenia, while twin 2 suffered from generalized epileptic seizures. In both twins, MRI demonstrated caudate nucleus atrophy and an increased apparent diffusion coefficient (ADC) in the striatum bilaterally with right sided predominance. (18)F-FDG PET showed bilaterally reduced glucose utilization in the striatum with clearly pronounced reduction on the right side compared to the left and in twin 1 compared to twin 2. Ratios of binding to striatal dopamine transporters (DAT) and serotonin transporters in the hypothalamus midbrain area as determined using (123)I-beta-CIT-SPECT fell within the normal ranges. However, in twin 1 a significant difference in binding to presynaptic DAT with marked reduction on the right hemisphere was observed. Right hemispheric accentuated changes measured by MRI, FDG-PET, and (123)I-beta-CITSPECT correspond to more severe hyperkinetic movements on the left part of the body in both twins. Different neuro-psychiatric features in this monocygotic twin pair suggest that not only genetic but also environmental factors contribute to the clinical symptomatology. Our findings suggest that the main neuropathological process in ChAc is located in the striatum, involving microstructural alterations, and disturbance of metabolism and dopaminergic neurotransmission.

Spontaneous Intracranial Hypotension: Correlation of Imaging Findings with Clinical Features

BACKGROUND

Spontaneous intracranial hypotension (SIH) is increasingly recognized as a clinically variable and likely underdiagnosed syndrome caused by non-traumatic CSF leaks. The aim of this study was to correlate the findings of imaging studies - magnetic resonance imaging (MRI), radionuclide cisternography - with clinical features and CSF pressure in SIH in order to improve the diagnostic yield and management in patients with SIH.

METHODS

Clinical case study of 10 consecutive cases of SIH, MRI, radio-isotope cisternography.

RESULTS

5 out of 10 patients had unusual clinical symptoms of SIH(2 subdural haematomas, 1 gait ataxia, 1 tinnitus, 1 haemodialysis-associated headache). In 7 patients pachymeningeal gadolinium enhancement was detected in MRI accompanied by a reduced CSF opening pressure. In contrast, the 3 patients with normal MRI also had a normal CSF pressure. Radio-isotope cisternography was abnormal in all patients tested. There was no correlation between the severity of clinical symptoms and MRI or radionuclide cisternography findings.

CONCLUSIONS

The spectrum of clinical symptoms and imaging findings in SIH is highly variable. There- fore the diagnosis of SIH is often delayed. Radio-isotope cisternography is an important additional diagnostic method to detect CSF leaks or pathological kinetics of radio-isotope movement particularly in cases with normal MRI findings.

Monoaminergic neurotransmission is altered in hepatitis C virus infected patients with chronic fatigue and cognitive impairment

BACKGROUND

The majority of patients with hepatitis C virus (HCV) infection suffer from disabling fatigue, cognitive dysfunction, and quality of life reduction. Meanwhile, there is increasing evidence that HCV infection can affect brain function. Recent studies have shown that fatigue and psychomotor slowing may resolve in patients with hepatitis C after treatment with ondansetron. This observation indicates alteration of serotonergic neurotransmission in HCV infected patients with chronic fatigue.

METHODS

Data from 20 HCV infected patients who were referred to our clinic because of disabling fatigue and cognitive decline of unknown cause were analysed retrospectively. Patients had undergone a diagnostic programme, including clinical and psychometric examination, electroencephalogram (EEG), magnetic resonance imaging of the brain, cerebrospinal fluid analysis, and I-123-beta-CIT (2beta-carbomethoxy-3-beta-(4-[(123)I]iodophenyl)tropane) single photon emission computerised tomography (SPECT) studies of serotonin and dopamine transporter binding capacity.

RESULTS

All patients had pathological results on the fatigue impact scale. Two thirds of patients showed pathological attention test results. EEG, magnetic resonance imaging, and cerebrospinal fluid analysis were normal. Pathological dopamine transporter binding was present in 12/20 (60%) patients and pathological serotonin transporter binding in 8/19 (50%) patients. Patients with normal SPECT results did not significantly differ from controls with regard to psychometric test results. Interestingly, patients with both decreased serotonin and dopamine transporter binding showed significantly impaired performance in most of the tests applied. Comorbidity that could have impaired cerebral function was excluded in all patients.

CONCLUSION

Our findings indicate alteration of serotonergic and dopaminergic neurotransmission in HCV infected patients with chronic fatigue and cognitive impairment.

Feasibility of central cannabinoid CB1 receptor imaging with [124I]AM281 PET demonstrated in a schizophrenic patient

We studied central cannabinoid CB1 receptors in a schizophrenic patient using the pyrazole derivative AM281 labelled with the positron-emitting nuclide iodine-124. A dynamic positron emission tomography (PET) acquisition with simultaneous blood sampling was performed up to 1.5 h post-injection. The classical Logan plot analysis was applied to generate a three-dimensional map of distribution volume (DV). The map was spatially normalised into the Montreal Neurological Institute stereotactic space. Using a volume of interest (VOI) template, mean values of DV were extracted from multiple grey matter regions and white matter (as a reference). As a measure of regional receptor availability, ratios of DV in grey matter to DV in white matter minus one (DVR-1) were calculated. The highest receptor binding was observed in the striatum and the pallidum (DVR-1: 0.35-0.37). Binding in basal ganglia regions was lower on the left than the right side. Moderately high binding was seen in the frontal cortex (0.22), the temporal cortex (0.18) and the cerebellum (0.15). In conclusion, 124I-AM281 PET can be used to reveal areas with prominent CB1 receptor binding. Nevertheless, limited image contrast and relatively high radiation exposure (physical half-life of 124I: 4 days) have to be taken into account. Asymmetric receptor binding may possibly reflect pathologic changes in schizophrenia.