Fibroblast Activation Protein Inhibitor-Positron Emission Tomography in Aortitis: Fibroblast pathology in active inflammation and remission

OBJECTIVES

Epigenetically modified fibroblasts contribute to chronicity in inflammatory diseases. Reasons for the relapsing character of large vessel vasculitis (LVV) remain obscure, including the role of fibroblasts, in part due to limited access to biopsies of involved tissue.68Ga FAPI-46 (FAPI)-PET/CT detects activated fibroblasts in vivo. In this exploratory pilot study, we tested the detection of fibroblast activation in vessel walls using FAPI-PET/CT in LVV with aortitis.

METHODS

8 LVV patients with aortitis and 8 age- and gender-matched controls were included. Distribution of FAPI uptake was evaluated in the aorta and large vessels. FAPI-uptake was compared with MRI inflammatory activity scores. Imaging results were compared with clinical parameters such as serum inflammatory markers, time of remission and medication.

RESULTS

Three aortitis patients were clinically active, five in remission. Irrespective of activity, FAPI uptake was significantly enhanced in aortitis compared with controls. Patients in remission had a mean duration of remission of 2.8 years (range 1-4 years), yet significant FAPI uptake in the vessel wall was found.In remitted aortitis, MRI inflammatory scores were close to be negative, while in 4/5 patients visually identifiable FAPI uptake was observed.

CONCLUSIONS

This pilot feasibility study shows significant tracer uptake in the aortic walls in LVV. FAPI positivity indicates ongoing fibroblast pathology in clinically remitted LVV.

Bestimmung von Einflußgrößen für den Therapieerfolg der Radioiodtherapie bei Patienten mit Morbus Basedow

Ziel der Studie war es, zu prüfen, inwieweit der Erfolg einer Radioiodtherapie (RIT) des Morbus Basedow (MB) von verschiedenen Parametern (Schilddrüsenvolumen [SDVol], Funktion, TRAK, Thyreostase, Therapiedosis, 131l-Uptake, effektive Halbwertszeit) abhängt. Methode: Bei 78 Patienten mit gesichertem MB wurden 626 ± 251 MBq 131 lod oral zur Ablation der Schilddrüse appliziert. 3 Monate nach RIT wurden 60 Patienten kontrolliert. Ergebnisse: Bei Patienten mit einer Hyperthyreose oder TRAK <11 U/l zu Beginn der RIT wurden eine signifikant niedrigere Therapiedosis bzw. Halbwertszeit gefunden als bei nichthyperthyreoten Patienten bzw. Patienten mit TRAK ≤11 U/l. Patienten mit einem SDVol ≤25 ml zeigten signifikant niedrigere 131l-Uptakewerte unter Therapie, jedoch signifikant höhere Relativuptakewerte (131l- Uptake/SDVol) als solche mit SDVol <25 ml. Alle Therapieversager wurden während der RIT thyreostatisch behandelt, sie wiesen im Mittel signifikant niedrigere Therapiedosen und Relativuptakewerte sowie signifikant höhere SdVol als Therapieerfolge auf. Durch die RIT reduzierte sich das SDVol der Patienten um 44%, wobei Versager eine signifikant geringere Volumenreduktion aufwiesen. Patienten mit einer Therapiedosis ≤250 Gy zeigten signifikant schlechtere Therapieresultate als solche mit <250 Gy, nur ein Versager erreichte mehr als 250 Gy, während immerhin 50% der Versager <200 Gy (aber >250 Gy) erreichten. Die Anwendung multivariater Analysen (MANOVA und Faktorenanalysen) ergab die Thyreostase als den entscheidenden Negativfaktor für den Erfolg einer RIT. Schlußfolgerung: Aufgrund der gehäuften Therapieversager bei Patienten mit Thyreostase empfehlen wir daher für diese Patienten eine Erhöhung der Zieldosis auf 250 Gy.

Untersuchungen zum Einfluß von »Ecstasy« auf den zerebralen Glukosemetabolismus: eine 18-FDG-PET-Studie

Ziel: In der vorliegenden Studie sollte die Akutwirkung des »Ecstasy«- Analogons MDE (3,4-Methylendioxyethamphetamin) auf den zerebralen Glukosemetabolismus (rMRGIu) gesunder Probanden untersucht werden. Methode: In einer randomisierten Doppelblindstudie wurden 16 gesunde Probanden ohne Drogenanamnese mittels 18-FDG-PET 110-120 min nach oraler Verabreichung von 2 mg/kg KG MDE (n = 8) oder Plazebo (n = 8) untersucht. Zwei Minuten vor Injektion des Radio- pharmazeutikums startend erfolgte über insgesamt 32 min eine konstante kognitive Stimulation über ein Wortrepetitionsparadigma, um konstante und vergleichbare mentale Bedingungen während der zerebralen 18-FDG-Aufnahme zu gewährleisten. Die Darstellung der Indivi- dualanatomie erfolgte anhand T1-gewichteter 3D-flash MRT mit anschließender manueller Regionalisierung in 108 Regions-of-Interest und PET/MRT Overlay. Absolute Quantifizierung der rMRGIu sowie Normierung auf den Globalmetabolismus mit anschließendem Vergleich MDE versus Plazebo mittels U-Test nach Mann und Whitney. Ergebnisse: Gegenüber der Plazebo-Gruppe fand sich unter MIDE keine signifikante Änderung der globalen MRGIu (MDE: 41,8± 11,1 μmol/min/100 g, Placebo: 50,1 ± 18,1 μmol/min/100 g, p = 0,298). Die normierten metabolischen Daten zeigten eine signifikante Minderung der rMRGIu im beidseitigen Frontalkortex: links frontal posterior (-7,1%, p <0,05) und rechts präfrontal superior (-4,6 %, p <0,05). Signifikante Steigerungen der rMIRGIu fanden sich dagegen im beidseitigen Zerebellum (rechts: + 10,1%, p <0,01; links: +7,6 %, p <0,05) sowie im rechten Putamen (+6,2%, p <0,05). Schlußfolgerung: In der vorliegenden Studie konnten unter dem Akuteinfluß des »Ecstasy«-Analogons MDE neuro- metabolische Veränderungen im Sinne einer fronto-striato-cerebellären Dysbalance nachgewiesen werden, die Parallelen zu sowohl anderen psychotropen Substanzen als auch verschiedenen endogenen Psychosen aufweisen.

Altered Relationships Between rCBF in Different Brain Regions of Never-Treated Schizophrenics

Aim of this study was to investigate the relations between regiona cerebral blood flow (rCBF) of different brain regions in acute schizophrenia and following neuroleptic treatment.

Methods: Twenty-two never-treated, acute schizophrenic patients were examined with HMPAO brain SPECT and assessed psychopathological-ly, and reexamined following neuroleptic treatment (over 96.8 days) and psychopathological remission. rCBF was determined by region/cerebel-lar count quotients obtained from 98 irregular regions of interest (ROIs), summed up to 11 ROIs on each hemisphere. In acute schizophrenics, interregional rCBF correlations of each ROI to every other ROI were compared to the interregional correlations following neuroleptic treatment and to those of controls.

Results: All significant correlations of rCBF ratios of different brain regions were exclusively positive in controls and patients. In controls, all ROIs of one hemisphere except the mesial temporal ROI correlated significantly to its contralateral ROI. Each hemisphere showed significant frontal-temporal correlations, as well as cortical-subcortical and some cortico-limbic. In contrast, in acute schizophrenics nearly every ROI correlated significantly with every other ROI, without a grouping or relation of the rCBF of certain ROIs as in controls. After neuroleptic treatment and clinical improvement, this diffuse pattern of correlations remained.

Conclusions: These results indicate differences in the neuronal interplay between regions in schizophrenic and healthy subjects. In never-treated schizophrenics, diffuse interregional rCBF correlations can be seen as a sign of change and dysfunction of the systems regulating specificity and diversity of the neuronal functions. Neuroleptic therapy and psychopathologic remission showed no normalizing effect on interregional correlations.

One-year Follow-up of Neuropsychology, MRI, rCBF and Glucose Metabolism (rMRGlu) in Cerebral Microangiopathy

Background: MRI shows lacunar infarctions (LI), deep white matter lesions (DWML) and atrophy in cerebral microangiopathy, which is said to lead to vascular dementia. In a first trial series on 57 patients with confirmed pure cerebral microangiopathy (without concomitant macroangiopathy), neuropsychological impairment and (where present) brain atrophy correlated with decreased rCBF and rMRGlu. LI and DWML did not correlate with either neuropsychological impairment or decreased rCBF/rMRGIu. This study was done one year later to detect changes in any of the study parameters. Methods: 26 patients were re-examined for rCBF, rMRGlu, LI, DWML, atrophy and neuropsychological performance (7 cognitive, 3 mnestic, 4 attentiveness tests). Using a special head holder for exact repositioning, rCBF (SPECT) and rMRGlu (PET) were measured and imaged slice by slice. White matter/cortex were quantified using MRI-defined ROIs. Results: After one year the patients did not show significant decreases in rCBF or rMRGlu either in cortex or in white matter (p >0.05), nor did any patient show LI, DWML or atrophy changes on MRI. There were no significant neuropsychological decreases (p >0.05). Conclusions: Cerebral microangiopathy ought to show progressive neuropsychological, functional (rCBF, rMRGlu) and morphological deterioration over periods >1 year. It is unlikely that direct cortical damage (e.g., incomplete infarction) is responsible for neuropsychological impairment since one-year follow-up of our patients revealed no progression of brain atrophy or any other cortical damage.

F-18-FDG Positron Imaging in Oncological Patients: Gamma Camera Coincidence Detection versus Dedicated PET

Aim of the present study was to investigate the feasibility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients with a dual head gamma camera modified for coincidence detection (MCD). Methods: Phantom studies were done to determine lesion detection at various lesion-to-background ratios, system sensitivity and spatial resolution. Thirty-two patients with suspected or known malignant disease were first studied with a dedicated full-ring PET system (DPET) applying measured attenuation correction and subsequently with an MCD system without attenuation correction. MCD images were first interpreted without knowledge of the DPET findings. In a second reading, MCD and DPET were evaluated simultaneously. Results: The phantom studies revealed a comparable spatial resolution for DPET and MCD (5.9 × 6.3 × 4.2 mm vs. 5.9 × 6.5 × 6.0 mm). System sensitivity of MCD was less compared to DPET (91 cps/Bq/ml/cmF0V vs. 231 cps/ Bq/ml/cmFOv). At a lesion-to-background ratio of 4:1, DPET depicted a minimal phantom lesion of 1.0 cm in diameter, MCD a minimal lesion of 1.6 cm. With DPET, a total of 91 lesions in 27 patients were classified as malignant. MCD without knowledge of DPET results revealed increased FDG uptake in all patients with positive DPET findings. MCD detected 72 out of 91 DPET lesions (79.1 %). With knowledge of the DPET findings, 11 additional lesions were detected (+12%). MCD missed lesions in six patients with relevance for staging in two patients. All lesions with a diameter above 18 mm were detected. Conclusion: MCD FDG imaging yielded results comparable to dedicated PET in most patients. However, a considerable number of small lesions clearly detectable with DPET were not detected by MCD alone. Therefore, MCD cannot yet replace dedicated PET in all oncological FDG studies. Further technical refinement of this new method is needed to improve image quality (e.g. attenuation correction).

Comparison of Different Methods for Attenuation Correction in Brain PET: Influence on the Calculation of the Metabolic Glucose Rate

Ziel: Für die Korrektur des Effektes der im Körpergewebe gestreuten oder absorbierten Photonen (Schwächungskorrektur) existieren bei der Positronen-Emissionstomographie (PET) verschiedene methodische Ansätze. Die vorliegende Arbeit untersucht den Einfluß der kalten (KT), heißen (PIT), segmentierten Transmission (ST) sowie eines rechnerischen Verfahrens (RV) auf die Schwächungskorrektur anhand der absoluten Bestimmung des regionalen zerebralen Glukosemetabolismus (rMRGIu). Methodik: 6 Patienten mit unterschiedlichen zerebralen Erkrankungen wurden mit einem ECAT Exact 922/47 unter Ruhebedingungen untersucht. Die durch die KT, PIT, RV und ST schwächungskorrigierten Daten wurden dann zur Beurteilung des regionalen Glukosemetabolismus in 16 ROIs (regions of interest) absolut quantifiziert. Ergebnisse: Bis auf drei Regionen (temporookzipital links und rechts sowie parietookzipital rechts) konnte kein signifikanter Unterschied des mit Hilfe der absoluten Quantifizierung in 16 ROIs ermittelten Glukosemetabolismus zwischen der KT und dem RV festgestellt werden. Im Gegensatz zum RV wurde sowohl bei der PIT als auch bei der ST in allen 16 ROIs ein signifikant niedrigerer Wert der regionalen zerebralen Glukoseutilisation gegenüber der KT nachgewiesen. Aufgrund dieser Resultate ergibt sich sowohl in der linken als auch in der rechten Hirnhälfte eine kontinuierliche Abnahme der metabolischen Werte (rMRGIu) in der Reihenfolge KT, RV, PIT und ST. Der globale, zerebrale Glukosemetabolismus zeigte keinen signifikanten Unterschied zwischen der KT und dem RV (p = 0,2489), während mit PIT (p = 0,03) und ST (p = 0,03) ein signifikant erniedrigter Glukosemetabolismus gegenüber der-KT nachzuweisen war. Schlußfolgerung: Bei den für die zerebralen PET-Studien am Patienten durchgeführten Schwächungskorrekturverfahren läßt sich bis auf drei Regionen quantitativ kein signifikanter Unterschied zwischen KT und RV nachweisen. Die rMRGIu der durch PIT und ST schwächungskorrigierten Bilder sind signifikant niedriger als in KT korrigierten Aufnahmen. Um eine zerebrale PET-Akquisition zu verkürzen, erscheint für die klinische Routine das RV als Alternative zur KT am besten geeignet.

FDG-PET in the initial staging of squamous cell oesophageal carcinoma

Squamous cell oesophageal carcinoma is the most common carcinoma of the oesophagus worldwide. The tumour stage as most important prognostic factor determines the clinical management. Aim of this study was to evaluate the value of FDG-PET 1. in imaging the primary tumour and 2. in Nand M-staging of squamous cell oesophageal carcinoma. Patients, methods: In 20 patients with histological proven squamous cell carcinoma of the upper and middle oesophagus , FDG-PET was performed in standard technique prior to therapy. FDG uptake in the primary was determined by calculation of the SUVmax. NM-staging due to PET findings was performed as designated by the AJCC/UICC group classification and was compared with pathological and clinically based staging. Sensitivities, specificities and accuracies were calculated. Results: In 19 of 20 patients, primary squamous cell oesopohageal carcinoma was detected by FDG-PET findings with a maximum SUV of 12.5 (mean) ± 5.1 (median 11.5; range 4.8-23.8). One carcinoma in situ was missed. The sensitivity of FDG-PET in imaging the primary tumour was 96%. The sensitivities, specificities and accuracies were 20%, 100%, 58% for N-staging, and 60%, 86% and 93% for M-staging. PET findings caused changes of therapy in 5% (1 patient). Conclusions: FDGPET was excellent in imaging the primary of squamous cell oesophageal carcinoma in stage T1-T4 and was efficient in M-staging. The low sensitivity in N-staging is of inferior clinical importance. The efficacy of FDG-PET seems to be not significantly be influenced by the histological subtype of oesophageal carcinoma.

Characterization of radioiodine therapy failures in Graves’ disease

Aim of this study was a characterization of radioiodine therapy (RIT) failures in Graves’ disease without simultaneous Carbimazole. Method: 226 patients with a confirmed diagnosis of Graves’ disease received 686.8 ± 376.4 MBq of iodine-131 orally for thyroid ablation. Target dose was 250 Gy. All patients were followed up for 6 months. Therapy failures were compared with successes regarding possible influencing variables initial thyroid volume, thyroid function, immune activity (TRAb), 1-131 uptake, effective half-life, absorbed energy dose, age and gender. Results: 212 of 226 patients (93.8%) were treated successfully, 14 (6.2%) showed a hyperthyroidism relapse within 6 months which required a second radioiodine therapy. A success rate of 92.5% (62/67) could also be achieved with 67 patients who were hyperthyroid at the time of RIT. Compared to the therapy successes, the 14 failures achieved significantly lower absorbed doses (223.8 ±76.6 Gyvs. 285.2 ±82.1 Gy, ρ <0.005), but with no significant differences regarding age, thyroid volume, function or TRAb (all ρ >0.2). Of the 14 failures, η = 8 reached an absorbed dose <200 Gy and η = 1 a dose <250 Gy, although 5 of the failures reached an absorbed dose of >250 Gy. Stepwise logistic regression revealed only absorbed energy dose as a variable significantly influencing therapy success (p <0.005), but no influence of initial thyroid volume, function, TRAb value, age (all ρ >0.2) or gender (p = 0.13). Two-tailed Fisher’s exact test showed no significant influence of gender on success rates (failures/successes: male 1 /36, female 13/176, ρ = 0.48). Conclusions: Except for the absorbed energy dose, no other significant variable influencing the outcome of radioiodine therapy in Graves’ disease without simultaneous Carbimazole could be found. It should be noted, though, that 5 therapy failures (2.2%) reached an absorbed energy dose of >250 Gy.

Effects of tetrahydrocannabinol on glucose uptake in the rat brain

Δ⁹-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain. The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain. 21 male Sprague Dawley rats (12-13 w) were examined and received five different doses of THC ranging from 0.01 to 1 mg/kg. For data acquisition a Focus 120 small animal PET scanner was used and 24.1-28.0 MBq of [¹⁸F]-fluoro-2-deoxy-d-glucose were injected. The data were acquired for 70 min and arterial blood samples were collected throughout the scan. THC, THC-OH and THC-COOH were determined at 55 min p.i. Nine volumes of interest were defined, and the cerebral glucose uptake was calculated for each brain region. Low blood THC levels of < 1 ng/ml (injected dose: ≤ 0.01 mg/kg) corresponded to an increased glucose uptake (6-30 %), particularly in the hypothalamus (p = 0.007), while blood THC levels > 10 ng/ml (injected dose: ≥ 0.05 mg/kg) coincided with a decreased glucose uptake (-2 to -22 %), especially in the cerebellar cortex (p = 0.008). The effective concentration in this region was estimated 2.4 ng/ml. This glucose PET study showed that stimulation of CB1 receptors by THC affects the glucose uptake in the rat brain, whereby the effect of THC is regionally different and dependent on dose - an effect that may be of relevance in behavioural studies.

Primary non-refluxive megaureter in children: single-center experience and follow-up of 212 patients

PURPOSE

Primary non-refluxing megaureter (pMU) is a multifaceted and challenging congenital pathology of the urinary tract. We report our 23-year experience with this anomaly in terms of presentation, diagnostic work-up and management.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 212 children diagnosed with pMU between 1986 and 2009 at our institution. Mean follow-up was 45.17 (0-192) months.

RESULTS

Of the total, 168 (79 %) children presented with upper urinary tract dilation on perinatal ultrasound screening. In 44 (21 %) patients, the diagnosis was made following diagnostic work-up of a urinary tract infection (UTI, 18 %) or flank pain (3 %). In total, 203 of 254 pMUs (79.9 %) were successfully treated conservatively during the 23-year observation period. Forty-eight children (23 %) underwent ureteric reimplantation. UTIs occurred in 91 of 212 children (43 %). Of these, 41 (45 %) occurred despite antibacterial infection prophylaxis. Within the past three decades, there has been a marked shift from surgical toward conservative therapy at our institution.

CONCLUSION

Neonatal renal ultrasound is the method of choice to timely identify children with pMU and, alongside dynamic renography, to monitor the clinical course. Nowadays, only a minor subset of children with asymptomatic course requires surgical correction. Antibacterial prophylaxis has the potential to reduce the risk of febrile UTIs. Prospective randomized studies are warranted to provide evidence of the beneficial effect of antibacterial prophylaxis.

Haematopoietic toxicity of radium-223 in patients with high skeletal tumour burden

In patients with metastasized, castration resistant prostate cancer (mCRPC) treatment with radium-223 (Xofigo) is an attractive therapeutic option. In particular, patients with high tumour load seem to profit from this treatment in regard of survival and quality of live. Aim of this study was to stratify mCRPC patients according to a quantitative imaging marker derived from routine bone scans (EXINI bone) and analyze haematopoietic toxicity of Xofigo in these patients.

PATIENTS, METHODS

Toxicity and oncologic outcome were investigated in a cohort of 14 patients with high tumour load. Additionally, based on a web survey, experience of toxicity in 41 high tumour load patients in Germany in 2014 was collected.

RESULTS

In patients with a bone scan index (BSI) greater than 5, significant toxicity occurred in more patients than expected from the ALSYMPCA trial. This was associated with application of fewer cycles. Similar experiences have been made in other centers in Germany. Approximately 7% of these patients will need very long time or will not recover from grade ≥ 3 toxicity.

CONCLUSION

Close follow-up of haematopoietic indices and, in case of toxicity, early termination of therapy is in particular necessary in late stage disease where limited bone marrow reserve is likely.

[Perfusion brain imaging with SPECT-technique. German Guideline S1]

This paper describes the guideline for perfusion brain imaging with SPECT-technique published by the Association of the Scientific Medical Societies in Germany (AWMF).The purpose of this guideline is to provide practical assistance for indication, examination procedures, findings and their interpretation also reflecting the present state of the art. Information and instruction are given regarding indication, preparation of the patients and examination procedures of brain perfusion SPECT, including preparation and quality control of the tracer as well as the radiation dosimetry, technical performance of image acquisition with the gamma-camera and image processing. Also advices for interpretation of findings are given. In addition, possible pitfalls are described.

Hirnperfusions-SPECT mit 99mTc-Radiopharmaka

This paper describes the guideline for perfusion brain imaging with SPECT-technique published by the Association of the Scientific Medical Societies in Germany (AWMF). The purpose of this guideline is to provide practical assistance for indication, examination procedures, findings and their interpretation also reflecting the present state of the art. Information and instruction are given regarding indication, preparation of the patients and examination procedures of brain perfusion SPECT, including preparation and quality control of the tracer as well as the radiation dosimetry, technical performance of image acquisition with the gamma-camera and image processing. Also advices for interpretation of findings are given. In addition, possible pitfalls are described.

PET lung ventilation/perfusion imaging using (68)Ga aerosol (Galligas) and (68)Ga-labeled macroaggregated albumin

Pulmonary imaging using ventilation/perfusion (V/P) single-photon emission tomography (V/P scan) with Tc-99m-labeled radiotracers is a well-established diagnostic tool for clinically suspected pulmonary embolism (PE). Ga-68 aerosol (Galligas) and Ga-68-labeled macroaggregated albumin (MAA) are potential tracers for positron emission tomography (PET) lung V/P imaging and could display an advantage over conventional V/P scans in terms of sensitivity and specificity. After radiochemical and animal studies, the clinical applicability of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was investigated in an exploratory study in patients with clinical suspicion of PE. PET scans were acquired using a 16-slice Gemini TF positron emission tomography/computed tomography (PET/CT) scanner. The acquisition protocol included low-dose computed tomography (CT) for attenuation correction (AC). Dosimetry calculations and continuative phantom measurements were performed. Structural analyses showed no modification of the particles due to the labeling process. In addition, in vitro experiments showed stability of Ga-68 MAA in various media. As expected, Ga-68-labeled human serum albumin microspheres (HSAM) were completely retained in the lung of the animals. In clinical use, PET lung ventilation and perfusion imaging using Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was successful in all cases. In one case a clinically suspected PE could be detected and verified. The administered activity of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA may be reduced by more than 50%, resulting in comparable radiation exposure to conventional V/P scans. In conclusion, Ga-68 aerosol (Galligas) and Ga-68-labeled MAA are efficient substitutes for clinical use and could be an interesting alternative with high accuracy for lung V/P imaging with Tc-99m-labeled radiotracers, especially in times of Mo-99 shortages and increasing use and spread of PET/CT scanners and Ga-68 generators, respectively.

[German guidelines for brain tumour imaging by PET and SPECT using labelled amino acids]

For the primary diagnosis of brain tumours, morphological imaging by means of magnetic resonance imaging (MRI) is the current method of choice. The complementary use of functional imaging by positron emitting tomography (PET) and single photon emitting computerized tomography (SPECT) with labelled amino acids can provide significant information on some clinically relevant questions, which are beyond the capacity of MRI. These diagnostic issues affect in particular the improvement of biopsy targeting and tumour delineation for surgery and radiotherapy planning. In addition, amino acid labelled PET and SPECT tracers are helpful for the differentiation between tumour recurrence and non-specific post-therapeutic tissue changes, in predicting prognosis of low grade gliomas, and for metabolic monitoring of treatment response. The application of dynamic PET examination protocols for the assessment of amino acid kinetics has been shown to enable an improved non-invasive tumour grading. The purpose of this guideline is to provide practical assistance for indication, examination procedure and image analysis of brain PET/SPECT with labelled amino acids in order to allow for a high quality standard of the method. After a short introduction on pathobiochemistry and radiopharmacy of amino acid labelled tracers, concrete and detailed information is given on the several indications, patient preparation and examination protocols as well as on data reconstruction, visual and quantitative image analysis and interpretation. In addition, possible pitfalls are described, and the relevant original publications are listed for further information.

Advocating neuroimaging studies of transmitter release in human physical exercise challenges studies

This perspective attempts to outline the emerging role of positron emission tomography (PET) ligand activation studies in human exercise research. By focusing on the endorphinergic system and its acclaimed role for exercise-induced antinociception and mood enhancement, we like to emphasize the unique potential of ligand PET applied to human athletes for uncovering the neurochemistry of exercise-induced psychophysiological phenomena. Compared with conventional approaches, in particular quantification of plasma beta-endorphin levels under exercise challenges, which are reviewed in this article, studying opioidergic effects directly in the central nervous system (CNS) with PET and relating opioidergic binding changes to neuropsychological assessments, provides a more refined and promising experimental strategy. Although a vast literature dating back to the 1980s of the last century has been able to reproducibly demonstrate peripheral increases of beta-endorphin levels after various exercise challenges, so far, these studies have failed to establish robust links between peripheral beta-endorphin levels and centrally mediated behavioral effects, ie, modulation of mood and/or pain perception. As the quantitative relation between endorphins in the peripheral blood and the CNS remains unknown, the question arises, to what extent conventional blood-based methods can inform researchers about central neurotransmitter effects. As previous studies using receptor blocking approaches have also revealed equivocal results regarding exercise effects on pain and mood processing, it is expected that PET and other functional neuroimaging applications in athletes may in future help uncover some of the hitherto unknown links between neurotransmission and psychophysiological effects related to physical exercise.

Central opioidergic neurotransmission in complex regional pain syndrome

Objective: Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by sensory, motor, and autonomic symptoms. It develops after limb trauma and may be associated with relevant psychiatric comorbidity. As there is evidence for central pathophysiology which might be related to an altered opioidergic neurotransmission, we investigated the cerebral opioid receptor status under resting conditions in this patient population.

Methods: In this case-control study, 10 patients with CRPS and 10 age- and gender-matched healthy subjects underwent a PET scan using the subtype-nonselective opioidergic radioligand [18F]fluoroethyl-diprenorphine. As a surrogate for regional cerebral opioid receptor availability, the opioid receptor binding potential (OR-BP) was assessed by means of the modified Logan plot with reference region input for categorical group comparison and correlation with clinical data in the patient group.

Results: Patients with CRPS showed reduced OR-BP in contralateral amygdala and parahippocampal gyri and increased OR-BP in contralateral prefrontal cortical areas. When OR-BP in the midcingulate cortex and the ipsilateral temporal cortex was low, the McGill pain rating index was high. In general, when anxiety and depression scales were high, contralateral temporal OR-BP was high as well. In addition, the anxiety scale decreased with increasing OR-BP in the contralateral parahippocampal cortex.

Conclusions: These results demonstrate altered central opioidergic neurotransmission in CRPS. The correlation of regional opioid receptor availability to measures of pain, anxiety, and depression underlines the clinical importance of these findings.

6-18F-fluoro-L-dihydroxyphenylalanine positron emission tomography is superior to 123I-metaiodobenzyl-guanidine scintigraphy in the detection of extraadrenal and hereditary pheochromocytomas and paragangliomas: correlation with vesicular monoamine transporter expression

CONTEXT

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) may be better detected by (18)F-fluorodihydroxyphenylalanine-positron emission tomography (FDOPA-PET) than (123)I-metaiodobenzyl-guanidine (123-I-MIBG) scintigraphy.

OBJECTIVE

The objective of the study was to correlate functional imaging results with immunohistochemical, molecular-genetic, and biochemical findings.

DESIGN AND SETTING

Thirty consecutive patients with suspected PHEO/PGL presenting at a tertiary referral centre were investigated in a prospective study.

PATIENTS

Twenty-five patients had confirmed PHEO/PGL. Thirteen of 25 patients had a hereditary PHEO/PGL syndrome (two multiple endocrine neoplasia II, six succinate dehydrogenase complex, subunit D, two succinate dehydrogenase complex, subunit B, one von Hippel Lindau tumor suppressor protein, two Neurofibromatosis-1), and 12 of 25 were classified as sporadic. Five patients had hormonally inactive adrenal incidentalomas.

MAIN OUTCOME MEASURES

In all patients computed tomography scan and/or magnetic resonance imaging as well as both 123-I-MIBG scintigraphy and FDOPA-PET were performed. Resected tumors were examined by immunohistochemistry for expression of the vesicular monoamine transporter (VMAT)-1 and -2 and other markers.

RESULTS

A total of 64 lesions were found with both functional imaging modalities. FDOPA-PET detected 62 lesions, whereas only 34 lesions were detected by 123-I-MIBG scintigraphy. This resulted in an overall sensitivity and specificity for FDOPA-PET of 98 and 100% and for MIBG of 53 and 91%, respectively. Comparable sensitivities were found for adrenal and extraadrenal abdominal lesions (94 vs. 97%), whereas in thoracic/cervical lesions, the sensitivity for 123-I-MIBG scintigraphy (15%) was inferior to that of FDOPA-PET imaging (100%). Immunohistochemistry demonstrated a lack of VMAT-1 expression in all MIBG-negative tumors. Clinical predictors for MIBG negativity were a predominant norepinephrine/normetanephrine secretion, an age less than 45 yr, and a hereditary cause.

CONCLUSION

FDOPA-PET is superior to 123-I-MIBG scintigraphy in patients with extraadrenal, predominantly noradrenaline-secreting, and hereditary types of PHEO/PGL. The lack of VMAT-1 expression predicts negativity for MIBG-scintigraphy.

Cortical control of thermoregulatory sympathetic activation

Thermoregulation enables adaptation to different ambient temperatures. A complex network of central autonomic centres may be involved. In contrast to the brainstem, the role of the cortex has not been clearly evaluated. This study was therefore designed to address cerebral function during a whole thermoregulatory cycle (cold, neutral and warm stimulation) using 18-fluordeoxyglucose-PET (FDG-PET). Sympathetic activation parameters were co-registered. Ten healthy male volunteers were examined three times on three different days in a water-perfused whole-body suit. After a baseline period (32 degrees C), temperature was either decreased to 7 degrees C (cold), increased to 50 degrees C (warm) or kept constant (32 degrees C, neutral), thereafter the PET examination was performed. Cerebral glucose metabolism was increased in infrapontine brainstem and cerebellar hemispheres during cooling and warming, each compared with neutral temperature. Simultaneously, FDG uptake decreased in the bilateral anterior/mid-cingulate cortex during warming, and in the right insula during cooling and warming. Conjunction analyses revealed that right insular deactivation and brainstem activation appeared both during cold and warm stimulation. Metabolic connectivity analyses revealed positive correlations between the cortical activations, and negative correlations between these cortical areas and brainstem/cerebellar regions. Heart rate changes negatively correlated with glucose metabolism in the anterior cingulate cortex and in the middle frontal gyrus/dorsolateral prefrontal cortex, and changes of sweating with glucose metabolism in the posterior cingulate cortex. In summary, these results suggest that the cerebral cortex exerts an inhibitory control on autonomic centres located in the brainstem or cerebellum. These findings may represent reasonable explanations for sympathetic hyperactivity, which occurs, for example, after hemispheric stroke.

In vivo molecular imaging of somatostatin receptors in pancreatic islet cells and neuroendocrine tumors by miniaturized confocal laser-scanning fluorescence microscopy

The aim of the study was to evaluate real time in vivo molecular imaging of somatostatin receptors (sstrs) using a handheld miniaturized confocal laser scan microscope (CLM) in conjunction with fluorescein-labeled octreotate (OcF) in healthy mice and murine models of neuroendocrine tumors. For CLM a small rigid probe (diameter 7 mm) with an integrated single line laser (488 nm) was used (optical slice thickness 7 mum; lateral resolution 0.7 mum). OcF was synthesized via Fmoc solid-phase peptide synthesis and purified by HPLC showing high-affinity binding to the sstr2 (IC(50) 6.2 nmol). For in vitro evaluation, rat and human pancreatic cancer cells were used and characterized with respect to its sstr subtype expression and functional properties. For in vivo confocal imaging, healthy mouse pancreatic islet and renal tubular cells as well as immunoincompetent nude mice harboring sstr-expressing tumors were evaluated. Incubation of sstr-positive cells with OcF showed a specific time- and dose-dependent staining of sstr-positive cells. CLM showed rapid internalization and homogenous cytoplasmatic distribution. After systemic application to mice (n = 8), specific time-dependent internalization and cytoplasmatic distribution into pancreatic islet cells and tubular cells of the renal cortex was recorded. After injection in tumor-harboring nude mice (n = 8), sstr-positive cells selectively displayed a cell surface and cytoplasmatic staining. CLM-targeted biopsies detected sstr-positive tumor cells with a sensitivity of 87.5% and a specificity of 100% as correlated with ex vivo immunohistochemistry. CLM with OcF permits real-time molecular, functional, and morphological imaging of sstr-expressing cell structures, allowing the specific visualization of pancreatic islet cells and neuroendocrine tumors in vivo.

Hyperechogenicity of the substantia nigra in healthy controls is related to MRI changes and to neuronal loss as determined by F-Dopa PET

Transcranial ultrasound (TCS) has been shown to reveal hyperechogenicity of the substantia nigra (SN) in Parkinsonian patients and in about 10% of healthy controls. It is hypothesized that SN hyperechogenicity in healthy subjects is a vulnerability marker for idiopathic Parkinson's disease (IPD). Although there is strong evidence that the echomarker results from increased local iron content, the exact pathophysiological mechanisms remain incompletely understood. Thus, prognostic impact can only be estimated. We examined 14 subjects with SN hyperechogenicity (SN+) (7 IPD patients and 7 controls) and 7 healthy controls without the echomarker (SN-) by a magnetic resonance imaging method (MRI; T2 relaxation times) known to reveal tissue inhomogeneity following abnormal iron content and by F-Dopa PET to assess nigrostriatal function.

Sympathetic activity at rest and motor brain areas: FDG-PET study

Although recent studies identified brain areas which are involved in short term activation of the sympathetic nervous system, little is known about brain mechanisms which generate the individual variability of basal autonomic activity. In this fluorodeoxyglucose positron emission tomography study (FDG-PET), we aimed to identify brain regions, which covary with function parameters of the autonomic nervous system at rest. Therefore, FDG-PET (Siemens, Germany) was performed twice in 14 healthy resting subjects (7 m, 7 f; mean age 29.5 years) while different parameters of autonomic function were assessed simultaneously: Blood pressure, heart rate, power spectra of heart rate variability (HF/LF ratio) and plasma catecholamines. In order to control for attention, subjects had to focus visual affective neutral presentations during the experiment. Correlation analysis was performed as a region of interest analysis using SPM2 software (p<0.001 uncorrected). Sympathetic activity at rest varied substantially between subjects. There were significant positive correlations between increase of regional cerebral glucose metabolism (rCGM) of the heads of caudate nuclei on both sides and the HF/LF ratio of heart rate variability. Furthermore, significant negative correlations between both heart rate and plasma catecholamines and rCGM decreases of caudate nuclei heads were found. In addition, there was a positive correlation between plasma catecholamines and primary motor cortex activation. Autonomic nervous system at rest seems to be partially interlocked with activity of motor brain regions - the caudate nuclei and the motor cortex. This might have clinical implications for the understanding of stress-related disorders, which are frequently accompanied by increased sympathetic activity as well as muscle tone.

Antiamphiphysin-positive stiff-person syndrome associated with small cell lung cancer

The paraneoplastic amphiphysin(+) stiff-person syndrome (SPS) has so far only been described in women with breast adenocarcinoma. Here, we describe the rare case of a female patient with antiamphiphysin(+) SPS due to small cell cancer of the lung.