Decreased mebrofenin uptake in patients with non-colorectal liver tumors requiring liver volume augmentation-a single-center analysis.

BACKGROUND: Posthepatectomy liver failure (PHLF) remains a life-threatening complication after hepatectomy. To reduce PHLF, a preoperative assessment of liver function is indispensable. For this purpose, 99mTc-mebrofenin hepatobiliary scintigraphy with SPECT (MSPECT) can be used. The aim of the current study was to evaluate the predictive value of MSPECT for PHLF in patients with non-colorectal liver tumors (NCRLT) compared to patients with colorectal liver metastasis (CRLM) undergoing extended liver resection. METHODS: We included all patients undergoing extended liver resections via two-stage procedures between January 2019 and December 2021 at the University Medical Center Hamburg-Eppendorf, Germany. All patients received a preoperative MSPECT. RESULTS: Twenty patients were included. In every fourth patient, PHLF was observed. Four patients had PHLF grade C. There were no differences between patients with CRLM and NCRLT regarding PHLF rate and future liver remnant (FLR) volume. Patients with CRLM had higher mebrofenin uptake in the FLR compared to those with NCRLT (2.49%/min/m2 vs. 1.51%/min/m2; p = 0.004). CONCLUSION: Mebrofenin uptake in patients with NCRLT was lower compared to those patients with CRLM. However, there was no difference in the PHLF rate and FLR volume. Cut-off values for the mebrofenin uptake might need adjustments for different surgical indications, surgical procedures, and underlying diseases.

F-18 labelled PSMA-1007: biodistribution, radiation dosimetry and histopathological validation of tumor lesions in prostate cancer patients.

PURPOSE: The prostate-specific membrane antigen (PSMA) targeted positron-emitting-tomography (PET) tracer 68Ga-PSMA-11 shows great promise in the detection of prostate cancer. However, 68Ga has several shortcomings as a radiolabel including short half-life and non-ideal energies, and this has motivated consideration of 18F-labelled analogs. 18F-PSMA-1007 was selected among several 18F-PSMA-ligand candidate compounds because it demonstrated high labelling yields, outstanding tumor uptake and fast, non-urinary background clearance. Here, we describe the properties of 18F-PSMA-1007 in human volunteers and patients. METHODS: Radiation dosimetry of 18F-PSMA-1007 was determined in three healthy volunteers who underwent whole-body PET-scans and concomitant blood and urine sampling. Following this, ten patients with high-risk prostate cancer underwent 18F-PSMA-1007 PET/CT (1 h and 3 h p.i.) and normal organ biodistribution and tumor uptakes were examined. Eight patients underwent prostatectomy with extended pelvic lymphadenectomy. Uptake in intra-prostatic lesions and lymph node metastases were correlated with final histopathology, including PSMA immunostaining. RESULTS: With an effective dose of approximately 4.4-5.5 mSv per 200-250 MBq examination, 18F-PSMA-1007 behaves similar to other PSMA-PET agents as well as to other 18F-labelled PET-tracers. In comparison to other PSMA-targeting PET-tracers, 18F-PSMA-1007 has reduced urinary clearance enabling excellent assessment of the prostate. Similar to 18F-DCFPyL and with slightly slower clearance kinetics than PSMA-11, favorable tumor-to-background ratios are observed 2-3 h after injection. In eight patients, diagnostic findings were successfully validated by histopathology. 18F-PSMA-1007 PET/CT detected 18 of 19 lymph node metastases in the pelvis, including nodes as small as 1 mm in diameter. CONCLUSION: 18F-PSMA-1007 performs at least comparably to 68Ga-PSMA-11, but its longer half-life combined with its superior energy characteristics and non-urinary excretion overcomes some practical limitations of 68Ga-labelled PSMA-targeted tracers.

The influence of water content in a proton-conducting ionic liquid on the double layer properties of the Pt/PIL interface.

The influence of the water content of 2-sulfoethylmethylammonium trifluoromethanesulfonate [2-Sema][TfO] on the double layer properties of the interface of platinum and the proton conducting ionic liquid (PIL) is investigated by means of impedance spectroscopy and cyclic voltammetry. By fitting the impedance spectra as complex capacitances, up to four differential double layer capacitances and corresponding time constants are obtained, depending on the potential (U = 0-1.6 V/RHE), water content (0.7-6.1 wt%) and temperature (T = 70-110 °C). Within the whole potential range investigated, a high frequency capacitance, C1, and a low frequency capacitance, C2, can be calculated. In the potential region of hydrogen underpotential deposition (HUPD), C1 can be separated into two parts, C1a and C1b. Whereas the high frequency capacitive processes can mainly be attributed to ion transport processes in the double layer, the low frequency process is ascribed to changes in the interfacial layer, including ad-/desorption and Faradaic processes. Alternative interpretations regarding the reorientation of ions, reconstruction of the metal surface and partial electron transfer between anions and Pt are considered.

Performance evaluation of a novel multi-pinhole collimator for dopamine transporter SPECT.

There is a tradeoff between spatial resolution and count sensitivity in SPECT with conventional collimators. Multi-pinhole (MPH) collimator technology has potential for concurrent improvement of resolution and sensitivity in clinical SPECT of 'small' organs. This study evaluated a novel MPH collimator specifically designed for dopamine transporter (DAT) SPECT with a triple-head SPECT camera. Count sensitivity was measured with a 99mTc point source placed on the lattice points of a 1 cm grid covering the whole field-of-view (FOV). Spatial resolution was assessed with a Derenzo type hot rod phantom. An anthropomorphic striatum phantom was scanned with total activity representative of a typical patient scan and different striatum-to-background activity concentration ratios. Recovery of striatum-to-background contrast was assessed by the contrast-recovery-coefficient. Measurements were repeated with double-head SPECT with fan-beam or low-energy-high-resolution-high-sensitivity (LEHRHS) collimators. A patient referred to DAT SPECT because of suspicion of Parkinson's disease was scanned with both LEHRHS and MPH collimators after a single tracer injection. The axial MPH sensitivity profile was approximately symmetrical around its peak, although it was shifted 7 cm towards the patient to simplify positioning. Peak sensitivity of the triple-head MPH system in the center of the FOV was 620 cps MBq-1 compared to 225 cps MBq-1 for the double-head fan-beam system. Sensitivity of the MPH system decreased towards the edges of the FOV. The full width of the sensitivity profile at 200 cps MBq-1 was 21 cm transaxially and 11 cm axially. In MPH SPECT of the Derenzo phantom all rods with ≥ 5 mm diameter were clearly visible. MPH SPECT improved striatal contrast recovery by ≥ 20% compared to fan-beam SPECT. The patient scan demonstrated good image quality of MPH SPECT with almost PET-like delineation of putamen and caudate nucleus. SPECT with dedicated MPH collimators provides considerable improvement of the resolution-sensitivity tradeoff in DAT SPECT compared to SPECT with fan-beam or LEHRHS collimators.

[The treatment of malignant tumors on venous leg ulcers. Case presentation and literature review]. / Therapie maligner Tumoren auf venösen Beinulzera. Kasuistik und Literaturübersicht.

Malignant changes in persistent venous leg ulcers are a grave complication of chronic impaired wound healing. In our case, a venous leg ulcer had persisted on the right calf for 30 years. Exophytic tumors in the ulcer with frequent bleeding prompted biopsies. A squamous cell carcinoma was found, but only in the second biopsy. The surgical procedure was planned so that in a single session both the tumor and the underlying causes of the chronic venous insufficiency in the leg could be treated appropriately. Extirpation of the enlarged lymph nodes in the groin was combined with crossectomy and removal of the long saphenous vein, followed by circular radial excision of the ulcer scar fascia (fasciotomy). The excised tissue was examined histologically. Muscle biopsies were taken from the site of suspicious adhesions of the fascia to the calf muscle. The large, circular defects on the lower leg were covered with the appropriate dressing to condition the wound bed. After three weeks the well-granulated area was covered with meshed split skin grafts. During the operation and in the post-operative phase, machine-assisted and manual decongestion was performed, an established therapy for lymphedema, chronic venous insufficiency and chronic venous ulcers.

A new setup for the quantitative analysis of drying by the use of gas-phase FTIR-spectroscopy.

Drying rates are important for the manufacture of thin films and in specific for the production of electrodes used in electrochemical devices such as fuel cells and electrolyzers. The known procedures to investigate time-dependent sample compositions and selective evaporation rates are insufficient to obtain mean information about the full area instead of a single point analysis. Therefore, a new setup is presented using gas-phase Fourier-transform infrared spectroscopy. This method analyzes the gas-phase composition to recalculate the layer composition in electrode fabrication at any time during drying. According to the golden rule of measurement technology, manufacturer specifications are often overestimated. Therefore, our alternative procedures were used to evaluate the precision of devices used. The calculated measurement precision is confirmed by validation. The expected deviation is quantified to be less than 2% for the common application. Further on, the relative test-retest standard deviation is determined to be 0.3%-0.4%. As a result of the error propagation, the measurement precision is limited by the background gas flow rate precision for common application. At low volume fractions, the influence of the substance flow rate deviations becomes significant. However, further studies will focus on increasing the gas flow rate precision.

High-resolution imaging of the large non-human primate brain using microPET: a feasibility study.

The neuroanatomy and physiology of the baboon brain closely resembles that of the human brain and is well suited for evaluating promising new radioligands in non-human primates by PET and SPECT prior to their use in humans. These studies are commonly performed on clinical scanners with 5 mm spatial resolution at best, resulting in sub-optimal images for quantitative analysis. This study assessed the feasibility of using a microPET animal scanner to image the brains of large non-human primates, i.e. papio hamadryas (baboon) at high resolution. Factors affecting image accuracy, including scatter, attenuation and spatial resolution, were measured under conditions approximating a baboon brain and using different reconstruction strategies. Scatter fraction measured 32% at the centre of a 10 cm diameter phantom. Scatter correction increased image contrast by up to 21% but reduced the signal-to-noise ratio. Volume resolution was superior and more uniform using maximum a posteriori (MAP) reconstructed images (3.2-3.6 mm(3) FWHM from centre to 4 cm offset) compared to both 3D ordered subsets expectation maximization (OSEM) (5.6-8.3 mm(3)) and 3D reprojection (3DRP) (5.9-9.1 mm(3)). A pilot (18)F-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG) scan was performed on a healthy female adult baboon. The pilot study demonstrated the ability to adequately resolve cortical and sub-cortical grey matter structures in the baboon brain and improved contrast when images were corrected for attenuation and scatter and reconstructed by MAP. We conclude that high resolution imaging of the baboon brain with microPET is feasible with appropriate choices of reconstruction strategy and corrections for degrading physical effects. Further work to develop suitable correction algorithms for high-resolution large primate imaging is warranted.

A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers.

We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell.

Clinical and biochemical phenotype in 11 patients with mevalonic aciduria.

OBJECTIVE: Mevalonic aciduria is a consequence of the deficiency of mevalonate kinase, the first enzyme after 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the biosynthesis of cholesterol and nonsterol isoprenes. To establish the clinical and biochemical phenotype of mevalonic aciduria, the authors assembled their experience with 11 patients including attempts at therapeutic interventions. METHODS: Mevalonic acid in body fluids was determined by stable isotope dilution gas chromatography/mass spectroscopy with selected ion monitoring, ubiquinone-10 concentrations by reversed-phase high-pressure liquid chromatography. RESULTS: Varying degrees of severity of clinical illness were observed despite uniform, virtual absence of residual activity of the enzyme. The most severely affected patients have had profound developmental delay, dysmorphic features, cataracts, hepatosplenomegaly, lymphadenopathy, and anemia, as well as diarrhea and malabsorption, and have died in infancy. Less severely affected patients have had psychomotor retardation, hypotonia, myopathy, and ataxia. All patients have had recurrent crises in which there was fever, lymphadenopathy, increase in size of liver and spleen, arthralgia, edema, and a morbilliform rash. Neuroimaging studies revealed selective and progressive atrophy of the cerebellum. Mevalonic acid concentrations were found to be grossly elevated in body fluids of all patients. Concentrations of plasma cholesterol were normal or only slightly reduced. Concentrations of ubiquinone-10 in plasma were found to be decreased in most patients. Abnormalities such as hypoglycemia, metabolic acidosis, or lactic acidemia, the usual concomitants of disorders of organic acid metabolism, were conspicuously absent. CONCLUSIONS: These observations establish the broad range of clinical symptoms and biochemical findings in mevalonic aciduria. It is concluded that although patients with mevalonic aciduria have a recognizable phenotype of serious clinical manifestations, some patients are likely to remain undiagnosed and may be found in a variety of subspecialty clinics, including neurology, gastroenterology, cardiology, and genetics.

Topical treatment of venous leg ulcers with a prostacyclin hydrogel: a double blind trial.

In a randomized, double-blind, placebo controlled study in patients with venous leg ulcers, the efficacy and tolerability of topical applications of a prostacylin hydrogel (iloprost) was investigated. 34 patients were allocated to the placebo treatment and 65 patients were allocated to the iloprost treatment. The iloprost treatment commenced with 10 micrograms/ml for the first 3 days and was increased to 40 micrograms/ml for the remaining treatment period if well tolerated. Maximally 3 ml of the hydrogel were applied daily on the ulcer base for a period of 8 weeks. The total area of the ulcers at the last individual assessment was chosen as the main criterion for evaluation of efficacy. Both concentrations of iloprost were well tolerated with almost the entire trial population on iloprost being treated with the 40 micrograms/ml iloprost hydrogel. With regards to efficacy, no significant difference was found in favour of the iloprost treatment.

N-Isovalerylalanine and N-isovalerylsarcosine: two new minor metabolites in isovaleric acidemia.

Besides N-isovalerylglycine, isovaleric, 3-hydroxyisovaleric, 4-hydroxyisovaleric, methylsuccinic, mesaconic, 3-hydroxyisoheptanoic and N-isovalerylglutamic acids the excretion of hitherto unreported N-isovalerylalanine and N-isovalerylsarcosine, two minor but characteristic constituents of the organic acid profile in isovaleric acidemia, is described. The new metabolites are assumed to be formed from isovaleryl-CoA by action of the enzyme glycine N-acylase on alanine and sarcosine, respectively.

[2-Methyl-3-oxovaleric acid: a characteristic metabolite in propionic acidemia]. / 2-Methyl-3-oxovaleriansäure: ein charakteristischer Metabolit bei Propionacidämie.

Urine samples from 9 patients with propionic acidemis were analyzed with respect to secondary propionyl-CoA metabolites by means of gas chromatography-mass spectrometry. A wide range of variation was observed. The presence of methylcitric and 2-methyl-3-oxovaleric acids, however, was demonstrable in all urines investigated in considerable amounts. For laboratories analyzing urinary organic acids as their methyl esters, 2-methyl-3-oxovaleric acid is considered to be of diagnostic value. In addition to the usual metabolites, the excretion of N-2-methylbutyrylglycine has been demonstrated in the urine of one patient with propionic acidemia.

Synthesis of 13C-labeled chenodeoxycholic, hyodeoxycholic, and ursodeoxycholic acids for the study of bile acid metabolism in liver disease.

In order to study the glycosidic conjugation of chenodeoxycholic, hyodeoxycholic, and ursodeoxycholic acids in patients with cholestasis after oral administration of pharmacological amounts of the respective bile acids avoiding the application of radioactive tracers we synthesized [24-13C]chenodeoxycholic, [24-13C]hyodeoxycholic, and [24-13C]ursodeoxycholic acids. The reaction intermediates of the bile acid syntheses were characterized by infrared spectroscopy. Purity was confirmed using thin-layer chromatography as well as gas chromatography-mass spectrometry. The 13C atom excess of approximately 90% of the synthesized bile acids was the same as the 13C atom excess of the sodium [13C]cyanide used for the labeling reaction confirming the successful synthesis. After oral administration of 0.5 g of [24-13C]ursodeoxycholic acid to a healthy volunteer, 13C label was detected in the nonamidated and glycine- or taurine conjugated glucosides and the N-acetylglucosaminide of ursodeoxycholic acid in urine. This establishes ursodeoxycholic acid as the first bile acid so far known to undergo both of the recently described glycosidic conjugation reactions in humans.

Facts and artefacts in mevalonic aciduria: development of a stable isotope dilution GCMS assay for mevalonic acid and its application to physiological fluids, tissue samples, prenatal diagnosis and carrier detection.

A stable isotope dilution assay using D3-mevalonic acid was developed and applied to the study of mevalonic aciduria. The method also appears to be suitable for the evaluation of different therapeutic regimens in patients with hypercholesterolemia. Mevalonic acid was isolated by liquid partition chromatography and quantified as the underivatized lactone by means of ammonia chemical ionization selected ion monitoring capillary gas chromatography-mass spectrometry. In heterozygotes there was significantly greater urinary excretion of mevalonic acid, while the range of enzymatic activity of mevalonate kinase showed an overlap with that of controls. The analysis of amniotic fluids of two pregnancies at risk for mevalonic aciduria showed a 3277-fold elevation as compared to controls in the first case, diagnostic of an affected fetus, and a normal value in the second one. Mevalonic acid concentration was much increased in tissues of the affected and aborted fetus. Concentrations ranged from 840 to 1120 mumol/kg in various tissues and were as high as 1810 mumol/kg in brain. Concentrations in control fetal tissues were approximately 1 mumol/kg.

The influence of intravenous medium- and long-chain triglycerides and carnitine on the excretion of dicarboxylic acids.

Four groups of male Wistar rats were alimented parenterally for 3 days. Groups 1 and 2 received medium-chain triglycerides (MCT) and groups 3 and 4 long-chain triglycerides (LCT). Groups 2 and 4 were supplemented with 100 mg L-carnitine/kg/day. The MCT-alimented rats presented with a distinct excretion of the dicarboxylic acids: adipic acid (C6), suberic acid (C8), and sebacic acid (C10). The acids excreted corresponded to the infused pattern of monocarboxylic acids: caproic acid (C6), caprylic acid (C8), and capric acid (C10). Dicarboxylic acid excretion after MCT administration may reflect an insufficient capacity of beta-oxidation on one hand or a preferential omega-oxidation of medium-chain fatty acids on the other. Carnitine supplementation lead to a further increase of the dicarboxylic acids in the MCT-group. beta-OH-butyric acid excretion decreased after carnitine in the MCT as well as in the LCT group. An increased transport of fatty acid-carnitine compounds out of the mitochondria is discussed as an important effect of carnitine supplementation. Hereby medium-chain fatty acids may be more accessible for omega-oxidation.

Primary systemic carnitine deficiency under successful therapy: clinical, biochemical, ultrahistochemical and renal clearance studies.

Systemic carnitine deficiency is an often fatal, but treatable metabolic disorder which should be considered in any child with repeated episodes of a Reye-like syndrome or a cardiomyopathy. A 4-year-old girl with a typical history and clinical findings was successfully treated with oral carnitine. Despite low liver carnitine, ketogenesis upon fasting was normal. Normal muscle function under therapy was associated with unchanged low muscle carnitine levels. Improvement of mitochondrial structure and function was demonstrated by controlled ultrahistochemical studies. A renal carnitine leak, evident from renal clearance studies, may contribute to the pathogenesis of systemic carnitine deficiency.

Metabolic cause of Reye-like syndrome.

The most frequent metabolic cause of Reye-like syndrome is medium chain acyl-CoA dehydrogenase (MCAD) deficiency. The authors describe a gypsy boy who was repeatedly hospitalised due to symptoms of Reye-like syndrome (serious hypoglycemia, loss of consciousness, seizures, increased values of aminotransferases, decreased values of free carnitine). The diagnosis of MCAD deficiency was established by analysis of plasmatic acylcarnitines by use of tandem mass spectrometry. DNA analysis proved the most common K329E (G985) mutation in gene for MCAD deficiency in homozygous state. The authors have emphasised the advantage of tandem mass spectrometry in the diagnosis of disorders of fatty acid beta-oxidation. This highly sophisticated method can detect most of these disorders from dry blood spots disregarding the symptoms and type of mutation.

NEMA NU 4-2008 validation and applications of the PET-SORTEO Monte Carlo simulations platform for the geometry of the Inveon PET preclinical scanner.

Monte Carlo-based simulation of positron emission tomography (PET) data plays a key role in the design and optimization of data correction and processing methods. Our first aim was to adapt and configure the PET-SORTEO Monte Carlo simulation program for the geometry of the widely distributed Inveon PET preclinical scanner manufactured by Siemens Preclinical Solutions. The validation was carried out against actual measurements performed on the Inveon PET scanner at the Australian Nuclear Science and Technology Organisation in Australia and at the Brain & Mind Research Institute and by strictly following the NEMA NU 4-2008 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction and count rates, image quality and Derenzo phantom studies. Results showed that PET-SORTEO reliably reproduces the performances of this Inveon preclinical system. In addition, imaging studies showed that the PET-SORTEO simulation program provides raw data for the Inveon scanner that can be fully corrected and reconstructed using the same programs as for the actual data. All correction techniques (attenuation, scatter, randoms, dead-time, and normalization) can be applied on the simulated data leading to fully quantitative reconstructed images. In the second part of the study, we demonstrated its ability to generate fast and realistic biological studies. PET-SORTEO is a workable and reliable tool that can be used, in a classical way, to validate and/or optimize a single PET data processing step such as a reconstruction method. However, we demonstrated that by combining a realistic simulated biological study ([(11)C]Raclopride here) involving different condition groups, simulation allows one also to assess and optimize the data correction, reconstruction and data processing line flow as a whole, specifically for each biological study, which is our ultimate intent.

Scatter correction for large non-human primate brain imaging using microPET.

The baboon is well suited to pre-clinical evaluation of novel radioligands for positron emission tomography (PET). We have previously demonstrated the feasibility of using a high resolution animal PET scanner for this application in the baboon brain. However, the non-homogenous distribution of tissue density within the head may give rise to photon scattering effects that reduce contrast and compromise quantitative accuracy. In this study, we investigated the magnitude and distribution of scatter contributing to the final reconstructed image and its variability throughout the baboon brain using phantoms and Monte Carlo simulated data. The scatter fraction is measured up to 36% at the centre of the brain for a wide energy window (350-650 keV) and 19% for a narrow (450-650 keV) window. We observed less than 3% variation in the scatter fraction throughout the brain and found that scattered events arising from radioactivity outside the field of view contribute less than 1% of measured coincidences. In a contrast phantom, scatter and attenuation correction improved contrast recovery compared with attenuation correction on its own and reduced bias to less than 10% at the expense of the reduced signal-to-noise ratio. We conclude that scatter correction is a necessary step for ensuring high quality measurements of the radiotracer distribution in the baboon brain with a microPET scanner, while it is not necessary to model out of field of view scatter or a spatially variant scatter function.

Attenuation correction for the large non-human primate brain imaging using microPET.

Assessment of the biodistribution and pharmacokinetics of radiopharmaceuticals in vivo is often performed on animal models of human disease prior to their use in humans. The baboon brain is physiologically and neuro-anatomically similar to the human brain and is therefore a suitable model for evaluating novel CNS radioligands. We previously demonstrated the feasibility of performing baboon brain imaging on a dedicated small animal PET scanner provided that the data are accurately corrected for degrading physical effects such as photon attenuation in the body. In this study, we investigated factors affecting the accuracy and reliability of alternative attenuation correction strategies when imaging the brain of a large non-human primate (papio hamadryas) using the microPET Focus 220 animal scanner. For measured attenuation correction, the best bias versus noise performance was achieved using a (57)Co transmission point source with a 4% energy window. The optimal energy window for a (68)Ge transmission source operating in singles acquisition mode was 20%, independent of the source strength, providing bias-noise performance almost as good as for (57)Co. For both transmission sources, doubling the acquisition time had minimal impact on the bias-noise trade-off for corrected emission images, despite observable improvements in reconstructed attenuation values. In a [(18)F]FDG brain scan of a female baboon, both measured attenuation correction strategies achieved good results and similar SNR, while segmented attenuation correction (based on uncorrected emission images) resulted in appreciable regional bias in deep grey matter structures and the skull. We conclude that measured attenuation correction using a single pass (57)Co (4% energy window) or (68)Ge (20% window) transmission scan achieves an excellent trade-off between bias and propagation of noise when imaging the large non-human primate brain with a microPET scanner.