Clinical Evaluation of the First Automated Assay for the Detection of Stimulating TSH Receptor Autoantibodies.

Until recently, stimulating TSH receptor autoantibodies (sTRAbs) could only be measured by bioassays. A new assay system, which directly detects sTRAb in sera by applying bridge technology, has been established and is now available as automated chemiluminescence (bridge) immunoassay. We evaluated the automated bridge assay in clinical routine and compared it with a conventional automated TRAb assay (competition assay). Altogether, 226 Graves' disease (GD), 57 autoimmune thyroiditis, 74 non-autoimmune nodular goiter and 49 thyroid cancer patients, as well as 41 healthy controls were retrospectively evaluated. ROC plot analysis based on sera of newly diagnosed GD patients revealed an area under curve of 0.99 (95% CI: 0.99-1.0) indicating a high assay sensitivity and specificity. The highest sensitivity (100%) and specificity (99%) were seen at a cut-off level of 0.55 IU/l. The calculated positive predictive value was 94%, whereas the negative was 100%. Applying a ROC plot-derived cut-off of≥0.30 IU/l, derived from sera of GD patients already receiving antithyroid drug therapy for≤6 months, the sensitivity was 99% whereas the specificity was 98%. Detailed comparison of both assay systems used revealed a slightly different distribution of sTRAb and TRAb. Measurement of sTRAb during follow-up revealed a steady decline over one year of follow-up. In summary, our results demonstrate that the new automated bridge assay system for detecting sTRAb has a high sensitivity and specificity for diagnosing GD and to discriminate from other thyroid diseases, respectively. Our study, however, does not provide full evidence that the bridge assay is specific for sTRAb only.

Pharmacological treatment with L-DOPA may reduce striatal dopamine transporter binding in in vivo imaging studies.

Numerous neurologic and psychiatric conditions are treated with pharmacological compounds, which lead to an increase of synaptic dopamine (DA) levels. One example is the DA precursor L-3,4-dihydroxyphenylalanine (L-DOPA), which is converted to DA in the presynaptic terminal. If the increase of DA concentrations in the synaptic cleft leads to competition with exogenous radioligands for presynaptic binding sites, this may have implications for DA transporter (DAT) imaging studies in patients under DAergic medication. This paper gives an overview on those findings, which, so far, have been obtained on DAT binding in human Parkinson's disease after treatment with L-DOPA. Findings, moreover, are related to results obtained on rats, mice or non-human primates. Results indicate that DAT imaging may be reduced in the striata of healthy animals, in the unlesioned striata of animal models of unilateral Parkinson's disease and in less severly impaired striata of Parkinsonian patients, if animal or human subjects are under acute or subchronic treatment with L-DOPA. If also striatal DAT binding is susceptible to alterations of synaptic DA levels, this may allow to quantify DA reuptake in analogy to DA release by assessing the competition between endogenous DA and the administered exogenous DAT radioligand.

Cerebellar fMRI Activation Increases with Increasing Working Memory Demands.

The aim of the present study was to explore cerebellar contributions to the central executive in n-back working memory tasks using 7-T functional magnetic imaging (fMRI). We hypothesized that cerebellar activation increased with increasing working memory demands. Activations of the cerebellar cortex and dentate nuclei were compared between 0-back (serving as a motor control task), 1-back, and 2-back working memory tasks for both verbal and abstract modalities. A block design was used. Data of 27 participants (mean age 26.6 ± 3.8 years, female/male 12:15) were included in group statistical analysis. We observed that cerebellar cortical activations increased with higher central executive demands in n-back tasks independent of task modality. As confirmed by subtraction analyses, additional bilateral activations following higher executive demands were found primarily in four distinct cerebellar areas: (i) the border region of lobule VI and crus I, (ii) inferior parts of the lateral cerebellum (lobules crus II, VIIb, VIII, IX), (iii) posterior parts of the paravermal cerebellar cortex (lobules VI, crus I, crus II), and (iv) the inferior vermis (lobules VI, VIIb, VIII, IX). Dentate activations were observed for both verbal and abstract modalities. Task-related increases were less robust and detected for the verbal n-back tasks only. These results provide further evidence that the cerebellum participates in an amodal bilateral neuronal network representing the central executive during working memory n-back tasks.

Focus on GABA(A) receptor function. A comparative analysis of in vivo imaging studies in neuropsychiatric disorders.

UNLABELLED: Impairment of GABA(A) receptor function is increasingly recognized to play a major role in the pathophysiology of neuropsychiatric diseases including anxiety disorder (AD), major depressive disorder (MDD) and schizophrenia (SZ). PATIENTS, METHOD: We conducted a PUBMED search, which provided a total of 23 in vivo investigations with PET and SPECT, in which GABA(A) receptor binding in patients with the primary diagnosis of AD (n = 14, 160 patients, 172 controls), MDD (n = 2, 24 patients, 28 controls) or SZ (n = 6, 77 patients, 90 controls) was compared to healthy individuals. RESULTS: A retrospective analysis revealed that AD, MDD and SZ differed as to both site(s) and extent(s) of GABAergic impairment. Additionally, it may be stated that, while the decline of GABA(A) receptor binding AD involved the whole mesolimbocortical system, in SZ it was confined to the frontal and temporal cortex. CONCLUSION: As GABA is known to inhibit dopamine and serotonin, GABAergic dysfunction may be associated with the disturbances of dopaminergic and serotonergic neurotransmission in neuropsychiatric disorders.

Interim PET response criteria in paediatric non-Hodgkin's lymphoma. Results from a retrospective multicenter reading.

AIM: To evaluate the use and reliability of the PET-based response criteria for interim PET (iPET) in terms of interobserver variability in pediatric and adolescent patients suffering from non-Hodgkin´s lymphoma (NHL). Particular attention was given to the identification of visual cutoff to separate patients with a favourable outcome. PATIENTS, METHODS: Retrospective analysis of PET-datasets of 18 children and adolescents suffering from NHL who underwent iPET after two cycles of chemotherapy for response assessment. Datasets were evaluated and rated in three independent review centers (RC) (blinded-read, intra-center consensus) using a visual 5-point response scale. Ratings were compared to clinical outcome. Pairwise interobserver agreement was analysed with Cohen's kappa-test (κ). Overall agreement (between attended RCs) was assessed with Fleiss' κ-test. RESULTS: Four patients suffered relapse (early, n = 2; late, n = 2). Per region analyses on interobserver variability revealed a "substantial" agreement (Fleiss' κ = 0.618). Per patient analyses revealed concordant iPET-ratings in eight patients: iPET-negative (iPET-), n = 5; iPET-positive (iPET+), n = 2; iPET-inconclusive (iPET±), n = 1. Discordant ratings were found in the remaining patients. Patients with early relapse were concordantly identified using mediastinal blood pool structures (MBPS, score ≥ 3) as visual cutoff between iPET+ or iPET-, respectively. However, patients with late relapse were not concordantly identified taking the MBPS as visual cutoff. CONCLUSION: The iPET interpretation using a dedicated PET-based response scale assured a low interobserver variability in per-region but not in per-patient analyses in a multicenter read. Using a sensitive read out (iPET+, score ≥ 3) a reliable identification of patients suffering relapse was limited to those with early relapse.

Involvement of the cerebellar cortex and nuclei in verbal and visuospatial working memory: a 7 T fMRI study.

The first aim of the present study was to extend previous findings of similar cerebellar cortical areas being involved in verbal and spatial n-back working memory to the level of the cerebellar nuclei. The second aim was to investigate whether different areas of the cerebellar cortex and nuclei contribute to different working memory tasks (n-back vs. Sternberg tasks). Young and healthy subjects participated in two functional magnetic resonance imaging (fMRI) studies using a 7 T MR scanner with its increased signal-to-noise ratio. One group of subjects (n=21) performed an abstract and a verbal version of an n-back task contrasting a 2-back and 0-back condition. Another group of subjects (n=23) performed an abstract and a verbal version of a Sternberg task contrasting a high load and a low load condition. A block design was used. For image processing of the dentate nuclei, a recently developed region of interest (ROI) driven normalization method of the dentate nuclei was applied (Diedrichsen et al., 2011). Whereas activated areas of the cerebellar cortex and dentate nuclei were not significantly different comparing the abstract and verbal versions of the n-back task, activation in the abstract and verbal Sternberg tasks was significantly different. In both n-back tasks activation was most prominent at the border of lobules VI and Crus I, within lobule VII, and within the more caudal parts of the dentate nucleus bilaterally. In Sternberg tasks the most prominent activations were found in lobule VI extending into Crus I on the right. In the verbal Sternberg task activation was significantly larger within right lobule VI compared to the abstract Sternberg task and compared to the verbal n-back task. Activations of rostral parts of the dentate were most prominent in the verbal Sternberg task, whereas activation of caudal parts predominated in the abstract Sternberg task. On the one hand, the lack of difference between abstract and verbal n-back tasks and the lack of significant lateralization suggest a more general contribution of the cerebellum to working memory regardless of the modality. On the other hand, the focus of activation in right lobule VI in the verbal Sternberg task suggests specific cerebellar contributions to verbal working memory. The verbal Sternberg task emphasizes maintenance of stimuli via phonological rehearsal, whereas central executive demands prevail in n-back tasks. Based on the model of working memory by Baddeley and Hitch (1974), the present results show that different regions of the cerebellum support functions of the central executive system and one of the subsidiary systems, the phonological loop.

Pitfalls in radiation oncology. "Myocardial metastasis" in PET-CT after palliative radiation treatment of the left 5th rib.

BACKGROUND: Positron emission tomography-computed tomography (PET-CT) is a useful diagnostic tool to detect metastases in patients with malignancy. False positives have been reported in cases of inflammation and tissue regeneration. CASE REPORT: Over a period of 2 years, a 32-year-old woman with hepatocellular carcinoma and multiple bone metastases received three treatments of radiation therapy to a bone metastasis in the 5th left rib. Restaging with [18F]fluorodeoxyglucose (FDG) PET-CT showed increased uptake within the cardiac apex highly suspicious for a myocardial metastasis. Because the patient was asymptomatic, additional magnetic resonance imaging (MRI) of the heart was performed demonstrating radiation-associated changes but no evidence for metastases. CONCLUSION: PET-CT is a well-established diagnostic tool in metastatic diseases but its results should always be correlated with the clinical picture of the patient and previous treatments to rule out false positives.

A comparison of rh-TSH and thyroid hormone withdrawal in patients with differentiated thyroid cancer: preliminary evidence for an influence of age on the subjective well-being in hypothyroidism.

We aimed to investigate the subjective well-being in patients with differentiated thyroid cancer after hormone withdrawal. Since this might be confounded by psycho-oncological processes unrelated to hypothyroidism we intended to minimize such factors by only including patients with a history of uneventful follow-up examinations for several years. We investigated 67 patients applying the General Health Questionnaire (GHQ-12) at 3 time points t1, t2, and t3. The time point t2 represented an intensified follow-up examination 5 years after thyroidectomy, which was performed either on hormone withdrawal (49 patients) or using rh-TSH (18 patients). The time points t1 and t3 took place during follow-up examinations 6 months before and after t2 in a euthyroid state. Additionally, we assessed the impact of age, gender, family status, and education on the GHQ-12 score at all 3 time points. Within the hormone withdrawal group the analyses demonstrated a significant difference between t1 and t2 as well as t3 and t2. Additionally, there was a significant negative correlation of age with GHQ-12 sum scores at t2, but not at t1 or t3. Subgroup analyses at t2 indicated that the subjective well-being in younger patients was more impaired compared to elderly patients. The between-group analysis showed no significant differences. However, concerning the age effect there was a significant difference between the subgroup of young hypothyroid patients and the total rh-TSH group at t2. We demonstrated preliminary evidence for an influence of age on the subjective well-being in hypothyroidism suggesting that younger subjects are subjectively more impaired by hypothyroidism than elderly ones.

In vivo imaging neurotransmitter function. The rat 6-hydroxydopamine model and its relevance for human Parkinson's disease.

This article gives an overview of those small animal imaging studies which have been conducted on neurotransmitter function in the rat 6-hydoxydopamine (6-OHDA) model of Parkinson's disease, and discusses findings with respect to the outcome of clinical studies on Parkinsonian patients.

Evaluation of interim PET response criteria in paediatric Hodgkin's lymphoma--results for dedicated assessment criteria in a blinded dual-centre read.

BACKGROUND: The aim of this study was to evaluate the use and reliability of the new positron emission tomography (PET)-based response criteria for interim positron emission tomography (iPET) in patients with paediatric Hodgkin's lymphoma (pHL). Particular emphasis was put on interobserver variability and on identification of a visual cut-off defining patients with very low risk for relapse. PATIENTS AND METHODS: The iPET scans of 39 pHL patients were evaluated in two independent centres by two PET-experienced specialists in nuclear medicine (blinded read, centre consensus) each. The iPET scans were interpreted using a 5-point scale and were compared with the outcome. Cohen's kappa-test (κ) was used to analyse the interobserver agreement. RESULTS: Concordant ratings were assessed in 19 patients with iPET-negative findings, in 11 patients with iPET-positive findings and in 2 patients with inconclusive ratings. A 'substantial agreement' between attended centres was achieved (κ = 0.748). All patients suffering relapse were concordantly identified, taking mediastinal blood pool structures (MBPS) as visual cut-off between PET-positive and PET-negative findings, respectively. All pHL patients with uptake lower than or equal to MBPS remained in complete remission. CONCLUSION(S): The iPET interpretation assured low interobserver variability. High sensitivity for identification of pHL patients suffering relapse is achieved if [18F]-fluorodeoxyglucose uptake above the MBPS value is rated as a PET-positive finding.

Neural traffic as voxel-based measure of cerebral functional connectivity in fMRI.

To access functional connectivity by in vivo brain imaging voxel-by-voxel, we developed a novel approach named neural traffic (NT). NT depicts the intensity of functional connectivity on a voxel-by-voxel basis in the whole brain. Functional magnetic resonance imaging (fMRI) experiments were carried out on eight individuals during either hearing or viewing words. The blood oxygen level dependant (BOLD) signal was taken as measure of neural activity. For each voxel, functional connectivity with all other brain voxels was determined by calculating Pearson correlation coefficients at two connectivity thresholds (r=0.35 and 0.65). Then, NT images were derived by counting the number of suprathreshold connections for each individual voxel. Calculations based on random networks indicate that statistically reliable NT images can be derived in individuals. With regard to group analysis, at r=0.35 NT images are similar though not identical with the first component of principal component analysis (PCA), displaying a widespread but not ubiquitous pattern of functionally connected cortical areas. At r=0.65, NT group images display functional connectivity confined to circumscribed cortical regions which reach beyond the corresponding primary sensory areas, their known associated areas and the default network. In conclusion, NT goes beyond the approach of correlating the BOLD signal with the external stimulus-presentation time course by computing linear functional connectivity between all brain voxels based on any BOLD time course. First results demonstrate that the NT approach is likely - on an individual base - to reveal novel cortical and subcortical connectivities involved in stimulus processing.

Graves' disease occurring after surgery of a multinodular goiter: a case report.

The transition of toxic or nodular goiter to Graves' disease is known as a rare side effect of (131)I therapy. Here, we report the case of a 46-year-old German female with posttherapeutical Graves' disease after surgery of a multinodular goiter. Although the major part of the thyroid was excised the patient suffered from manifest Graves' disease including typical clinical and laboratory findings. Prior to surgery, no TSH receptor antibodies were found, although low TPO antibody titres could already be detected. It may thus be assumed that the therapeutic manipulation elicited the key change towards a TSH receptor antibody production in a predisposed organ or alternatively deteriorated a mild unapparent pre-existing Graves' disease. It might be concluded that the possibility of posttherapeutical Graves' disease should be considered in the presence of TPO antibodies prior to the surgical intervention.

Comparison of M22-based ELISA and human-TSH-receptor-based luminescence assay for the measurement of thyrotropin receptor antibodies in patients with thyroid diseases.

Previously, a new procedure for measuring serum TSH receptor autoantibodies (TRAb) was reported in which the autoantibodies inhibit binding of a human monoclonal thyroid stimulating antibody M22 to TSHR-coated ELISA plate wells (TRAb ELISA). The aim of the present study was to evaluate the clinical performance of this assay in comparison to the second generation TRAb assay (TRAb LIA) based on the recombinant human TSH-receptor and chemiluminescence technology (TRAb LIA). Among the 158 patients, 84 patients suffered from Graves' disease (GD), 34 patients had Hashimoto's thyroiditis (HT), and 40 patients had euthyroid nodular thyroid disease (NTD) without signs of autoimmunity. TRAb measurements were performed according to the manufacturer's instructions. Out of 84 GD patients, 80 (95.2%) were TRAb positive as detected by the TRAb LIA. One GD patient had TRAb values within the grey zone (1.0-1.5 IU/l). All patients with HT and NTD were negative except in 6 (8.1%) cases whose TRAb values were within the grey zone. On the basis of the recommended cutoff value (TRAb 1.0 IU/l), the TRAb ELISA found 78 of 84 (92.9%) GD patients to be TRAb positive. None of the patients with HT, but two cases (5.0%) with NTD were TRAb positive. The diagnostic sensitivity of the TRAb LIA and TRAb ELISA assays was 95.2 and 92.9%, while the specificity was 100% and 97.3%, respectively. There was a close correlation (r=0.968, p<0.0001) between both assays in 84 patients with GD. Additionally, the between-run imprecision close to the cutoff limit was assessed. The calculated between-run coefficient of variation (CV) of the TRAb ELISA was 28.2% at the recommended cutoff value of 1.0 IU/l. Due to the evaluated imprecision data we propose a higher cutoff value correlating with a between-run CV of 20% (functional assay sensitivity). Our results indicate that due to a worse imprecision the TRAb ELISA has a slightly lower sensitivity and specificity compared to the TRAb LIA assay. These findings suggest that the M22 monoclonal antibody-based TRAb ELISA is not as reliable as other second generation TRAb assays in the diagnosis of Graves' diseases.

Neural correlates of subliminal and supraliminal letter processing--an event-related fMRI study.

One problem of interpreting research on subconscious processing is the possibility that participants are weakly conscious of the stimuli. Here, we compared the fMRI BOLD response in healthy adults to clearly visible single letters (supraliminal presentation) with the response to letters presented in the absence of any behavioural evidence of visibility (subliminal presentation). No letter catch trials served as a control condition. Forced-choice responses did not differ from chance when letter-to-background contrast was low, whereas they were almost 100% correct when contrast was high. A comparison of fMRI BOLD signals for supraliminal and subliminal letters with the control trials revealed a signal increase in left BA 37 (fusiform gyrus). Comparison of supraliminal with subliminal letters showed a significant increase in the right inferior frontal gyrus (BA 44, partly extending to BA 9 and BA 45, as well as BA 46). Finally, a comparison of subliminal with supraliminal letters showed increases in the left middle temporal gyrus (BA 21) and the right extrastriate cortex (BA 19).

Cerebral haemodynamics during hypo- and hypercapnia: determination with simultaneous 15O-butanol-PET and transcranial Doppler sonography.

AIM: Transcranial Doppler sonography (TCD) is increasingly used in cerebrovascular disease for monitoring brain perfusion. It allows estimation of cerebral blood flow (CBF) by the measurement of cerebral blood flow velocity (CBFV). The CBFV as well as CBF are intimately associated with the intravascular CO2-concentration. Thus, hyper- or hypocapnia can be used to induce a defined range of blood flows. The aim of our study was the comparison of vasomotor reactivity assessed with simultaneous TCD and quantitative regional CBF-measurements (rCBF) by PET (serving as the reference method for in-vivo quantification of rCBF). PATIENTS, METHODS: Six healthy young volunteers participated in this study. CBF was measured using 15O-butanol PET. A flow and dispersion-model was fitted to the measured time activity curves using arterial input curves. Each subject underwent five scans at five different end-tidal CO2 levels (EtCO2): 25, 32, 40, 48, and 55 mmHg. CBFV was assessed by continuous bilateral TCD of the middle cerebral artery (MCA). Volumes of interest for rCBF determination were placed in grey matter of the prefrontal cortex (PFC) as determined from individual MRIs. Comparisons between the rCBF, EtCO2 and CBFV were carried out with regression and correlation analysis and paired t-tests. RESULTS: Strong positive linear correlations of rCBF and CBFV with the CO2-concentration and linear relationships between rCBF and CBFV were found in each individual. Normalised CO2-reactivities measured by TCD and PET were closely correlated. CONCLUSIONS: TCD-measurements of vascular reactivity in healthy volunteers show a high correlation to those acquired with PET that serves as the reference method of quantitative rCBF-measurement. The results of the MCA insonation are a close approximation of the rCBF changes induced by variations of EtCO2.

Depression and anxiety in different thyroid function states.

Previous studies on hypothyroid subjects have indicated serious psychiatric symptoms affecting the patients' quality of life. The present prospective cross-sectional study's aim was to examine these symptoms in thyroid patients with different functional states. A total of 254 patients (age: 56 +/- 14 years [mean +/- standard deviation], 181 female, 73 male) referred to a hospital for radioiodine treatment of hyperthyroidism or for follow-up of differentiated thyroid cancer, respectively, were included. All patients underwent the twelve-item general health questionnaire, which is an instrument for detecting mood disturbances. Euthyroid and hyperthyroid patients did not differ significantly in their general health questionnaire score (11 +/- 5 vs. 11 +/- 7), nor did subclinical hyperthyroid (11 +/- 6) or subclinical hypothyroid subjects (12 +/- 5). In contrast, hypothyroid patients showed a significantly higher mean score (17 +/- 7, p < 0.001, ANOVA). Binary logistic regression revealed that hypothyroidism increases age and gender-adjusted risk for critical mood deterioration by seven-fold. Thus, hypothyroidism represents a widely underestimated functional condition that may severely affect mental health.

When planning fails: individual differences and error-related brain activity in problem solving.

The neuronal processes underlying correct and erroneous problem solving were studied in strong and weak problem-solvers using functional magnetic resonance imaging (fMRI). During planning, the right dorsolateral prefrontal cortex was activated, and showed a linear relationship with the participants' performance level. A similar pattern emerged in right inferior parietal regions for all trials, and in anterior cingulate cortex for erroneously solved trials only. In the performance phase, when the pre-planned moves had to be executed by means of an fMRI-compatible computer mouse, the right dorsolateral prefrontal cortex was again activated jointly with right parahippocampal cortex, and displayed a similar positive relationship with the participants' performance level. Incorrectly solved problems elicited stronger bilateral prefrontal and left inferior parietal activations than correctly solved trials. For both individual ability and trial-specific performance, our results thus demonstrate the crucial involvement of right prefrontal cortex in efficient visuospatial planning.

[Neurocognition and PET. Strategies for data analysis in activation studies on working memory]. / Neurokognition and PET: datenanalytische Strategien bei Aktivierungsstudien zum Arbeitsgedächtnis.

AIM: In cognitive neuroscience regional cerebral blood flow (rCBF) imaging with positron-emission-tomography (PET) is a powerful tool to characterize different aspects of cognitive processes by using different data analysis approaches. By use of an n-back verbal working memory task (varied from 0- to 3-back) we present cognitive subtraction analysis as basic strategy as well as parametric and covariance analyses and discuss the results. METHODS: Correlation analyses were performed using the individual performance rate as an external covariate, computing inter-regional correlations, and as network analysis applying structural equation modelling to evaluate the effective connectivity between the involved brain regions. RESULTS: Subtraction analyses revealed a fronto-parietal neuronal network also including the anterior cingulate cortex and the cerebellum. With higher memory load the parametric analysis evidenced linear rCBF increases in prefrontal, pre-motor and inferior parietal areas including the precuneus as well as in the anterior cingulate cortex. The rCBF correlation with the individual performance as external covariate depicted negative correlations in bilateral prefrontal and inferior parietal regions, in the precuneus and the anterior cingulate cortex. The network analysis demonstrated mainly occipito-frontally directed interactions which were predominantly left-hemispheric. Additionally, strong linkages were found between extrastriate and parietal regions as well as within the parietal cortex. CONCLUSION: The data analysis approaches presented here contribute to an extended and more elaborated understanding of cognitive processes and their different sub-aspects.

Topographic segregation and convergence of verbal, object, shape and spatial working memory in humans.

This functional magnetic resonance imaging study investigates commonalties and differences in working memory (WM) processes employing different types of stimuli. We specifically sought to characterize topographic convergence and segregation with respect to prefrontal cortex involvement using verbal, spatial, real object and shape memory items in a two-back WM task. Both the dorsolateral and ventrolateral prefrontal cortices are conjointly activated across all stimulus types. No stimulus-specific differences in the activation patterns of the prefrontal cortex could be demonstrated giving support to the view of an amodal prefrontal involvement during WM processes. However, extra-frontal regions specialized on feature processing and involved in the preprocessing of the stimuli were selectively activated by these different subtypes of WM. These selectively activated regions are assigned to parts of the ventral and dorsal stream.

[The (11C) acetate positron emission tomography in prostatic carcinoma. New prospects in metabolic imaging]. / Die [11C]Acetat-Positronenemissionstomographie beim Prostatakarzinom. Neue Perspektiven in der metabolischen Bildgebung.

The exact staging of prostate cancer is mandatory to allow selection of the appropriate primary therapy. In addition, if the PSA level rises again it is extremely important to find the site(s) of local recurrence or metastatic spread as soon as possible. However, with the morphological and metabolic imaging techniques currently available it is often not possible to answer these questions with adequate sensitivity and specificity, since small metastases < or = 1 cm in diameter are likely to remain undetected by them. In the last few years new radioactive labelled tracers have been introduced for use in positron emission tomography (PET), and it is hoped that the shortcomings in the diagnostic procedures used for prostate carcinoma might be compensated by their use. Besides 11C- or 18F-labelled choline, [11C]Acetate is also attracting attention as a promising PET tracer. In this paper we review the various PET tracers available and evaluate the advantages and the drawbacks of [11C]Acetate in three case studies by comparing [11C]Acetate-PET with histology and with other imaging techniques. The use of [11C]Acetate appears to be feasible and helpful in the diagnosis of prostate carcinoma. However, its final value relative to other imaging techniques needs further investigation, with special reference to initial lymph node involvement, early localisation of recurrence and possible noninvasive differentiation between prostate cancer, prostatis and benign hyperplasia of the prostate.