Clinical evaluation of PET image reconstruction using a spatial resolution model

Purpose

PET image resolution is variable across the measured field-of-view and described by the point spread function (PSF). When accounting for the PSF during PET image reconstruction image resolution is improved and partial volume effects are reduced. Here, we evaluate the effect of PSF-based reconstruction on lesion quantification in routine clinical whole-body (WB) PET/CT imaging.

Materials and methods

41 oncology patients were referred for a WB-PET/CT examination (Biograph 40 TruePoint). Emission data were acquired at 2.5 min/bed at 1 h pi of 400 MBq [18F]-FDG. Attenuation-corrected PET images were reconstructed on 336 × 336-matrices using: (R1) standard AW-OSEM (4 iter, 8 subsets, 4 mm Gaussian) and (R2) AW-OSEM with PSF (3 iter, 21 subsets, 2 mm). Blinded and randomised reading of R1- and R2-PET images was performed. Individual lesions were located and counted independently on both sets of images. The relative change in PET quantification (SUV_max, SUV_mean, volume) of lesions seen on R1 and R2 is reported as (R2 − R1)/R1. Furthermore, SUV_max and SUV_mean was measured for a 3 cm spherical norm region in the right lobe of the healthy liver for R1 and R2.

Results

Clinical reading revealed 91 and 103 positive lesions for R1 and R2, respectively. For all lesions SUV_max (R2) was higher than SUV_max (R1). Regression analysis indicated that the relative increase in SUV_max (and SUV_mean) decreased with lesion size, whilst it increased with increasing radial distance from the centre of the field of view (FOV). There was no significant difference in SUV_mean in homogenous liver tissue between R1 and R2.

Conclusion

In whole-body FDG-PET/CT using routine clinical protocols, PSF-based PET reconstruction increases lesion detection and affects SUV_max measurements compared to standard AW-OSEM PET reconstruction.     

Percutaneous lateral ulnar collateral ligament reconstruction

Purpose

Open surgical reconstruction of the lateral ulnar collateral ligament is the standard treatment for symptomatic posterolateral rotatory instability of the elbow. It involves dissection and retraction of the lateral elbow muscles, which have been shown to be secondary stabilizers of the lateral elbow. We introduce a new muscle-protecting technique for single-strand lateral ulnar collateral ligament reconstruction and report on the isometry and primary stability when compared with a conventional muscle-splitting procedure. It was hypothesized that percutaneous lateral ulnar collateral ligament reconstruction provided isometry over the range of motion and that stability was comparable with a conventional open procedure.

Methods

In sixteen human cadaver arms, the intact and the lateral collateral ligament complex-deficient situation was tested. Open lateral ulnar collateral ligament reconstruction was performed using a single-strand palmaris graft with humeral and ulnar tenodesis screw fixation. Posterolateral rotational stability was compared with a new reconstruction method, which percutaneously places a single-strand palmaris graft with humeral and ulnar tenodesis screw fixation.

Results

Both open and percutaneous lateral ulnar collateral ligament reconstruction provided isometry over the range of motion and restored posterolateral stability to that of the intact situation. No significant differences between open and percutaneous reconstruction were found.

Conclusions

Percutaneous lateral ulnar collateral ligament reconstruction aims to preserve the lateral elbow muscles and to minimize soft tissue dissection. It has been shown that in an in vitro setup, this new procedure provides isometry over the range of motion and sufficiently restores posterolateral rotatory stability.     

High resolution ultrasound in posterior interosseous nerve syndrome

Introduction: Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy of the PIN in the region of the supinator muscle, most common by the arcade of Frohse. We aimed to specify ultrasonographic findings in patients with PIN syndrome in comparison to healthy volunteers. Methods: Ultrasound images and clinical data of 13 patients with PIN syndrome confirmed by neurological examination and electrophysiological testing were evaluated retrospectively. Anteroposterior nerve diameters measured at the arcade of Frohse were compared with those of 20 healthy volunteers. The echotexture and the presence of a caliber change of the PIN were additionally assessed. Results: Enlargement of the PIN was seen in all patients with PIN syndrome, but not in volunteers (statistically significant difference in mean diameter P < 0.05). Furthermore, edema and caliber change of the PIN were present in all patients. Conclusions: High‐resolution ultrasound allows for differentiation between patients with PIN syndrome and healthy volunteers. Muscle Nerve 49 : 35–39, 2014     

Identifying emerging trends in recreational drug use; outcomes from the Psychonaut Web Mapping Project

Background

This paper presents the outcomes of the 2-year European Union funded Psychonaut Web Mapping Project which aimed at developing and implementing an integrated web mapping system to promptly identify and learn about novel psychoactive substances (NPS; “legal highs”) through the regular monitoring of the Internet.

Methods

More than 200 discussion forums, social media, online shops, websites and other Internet resources (e.g. YouTube, eBay, Google, Google Insight) have been extensively and regularly monitored in 7 European countries (UK, Finland, Norway, Belgium, Germany, Italy and Spain) for emerging trends of NPS throughout the period of the study.

Results

Key online resources have been identified as “leading edge” which have provided accurate and timely information on novel emerging compounds. In total more than 400 substances/products have been recorded. NPS have been noted online before reaching wider audiences.

Discussion

Although a high number of novel psychoactive substances have been identified in the 2-year duration of the project, not all have become trends that needed public health response. Conversely, new recreational drug phenomena such as “spice drugs,” mephedrone and naphyrone were all identified as emerging trends in forums and websites. In addition, it has been possible for the first time to collate detailed information on these and several more compounds even though no or limited scientific publications were available. It is therefore recommended that these monitoring activities are to be continued, that more countries, researchers and health professionals are involved, and that the findings are widely shared with all the relevant agencies, health professionals and future research projects.Implications, advantages and limitations of using the Internet as primary source for identifying emerging trends are also discussed.     

Crystal structure of the sodium-potassium pump (Na+,K+-ATPase) with bound potassium and ouabain

The sodium-potassium pump (Na⁺,K⁺-ATPase) is responsible for establishing Na⁺ and K⁺ concentration gradients across the plasma membrane and therefore plays an essential role in, for instance, generating action potentials. Cardiac glycosides, prescribed for congestive heart failure for more than 2 centuries, are efficient inhibitors of this ATPase. Here we describe a crystal structure of Na⁺,K⁺-ATPase with bound ouabain, a representative cardiac glycoside, at 2.8 Å resolution in a state analogous to E2·2K⁺·Pi. Ouabain is deeply inserted into the transmembrane domain with the lactone ring very close to the bound K⁺, in marked contrast to previous models. Due to antagonism between ouabain and K⁺, the structure represents a low-affinity ouabain-bound state. Yet, most of the mutagenesis data obtained with the high-affinity state are readily explained by the present crystal structure, indicating that the binding site for ouabain is essentially the same. According to a homology model for the high affinity state, it is a closure of the binding cavity that confers a high affinity.     

Social cognitive bias and neurocognitive deficit in paranoid symptoms: evidence for an interaction effect and changes during treatment

Persistent paranoid symptoms are best understood as having multiple causal mechanisms. An enhanced multidimensional understanding of paranoia may result from the convergence of two distinct measurement paradigms, experimental psychopathology and social cognitive research. This study investigated the role of neurocognitive deficits and emotion misperception bias as they relate to paranoid symptoms at two different time points in a sample of individuals with severe mental illness (primarily schizophrenia spectrum disorders [N=91]) undergoing intensive psychosocial rehabilitation. Before intensive rehabilitation (but after initial stabilization), paranoid symptoms were related to a tendency to misperceive emotion as disgust. The impact of this social cognitive bias was amplified by perseveration (as measured by the COGLAB Card Sorting Task). Perseverative errors were associated with paranoid symptoms at both time points. After 6 months of treatment, there were significant reductions in paranoid symptoms and perseverative errors but no significant changes in emotion misperception biases. This study is one of few to date to evaluate the contribution of both neurocognitive deficits and social cognitive biases to paranoid symptoms. The results demonstrate how social cognitive biases can interact with neurocognitive deficits in expression of paranoid symptoms, and how these relationships change during treatment.     

Cerebral Glutamine Concentration and Lactate–Pyruvate Ratio in Patients with Acute Liver Failure

Aim  Hyperammonemia causes brain edema and high intracranial pressure (ICP) in acute liver failure (ALF) by accumulation of glutamine in brain. Since a high-level glutamine may compromise mitochondrial function, the aim of this study was to determine if the lactate–pyruvate ratio is associated with a rise in the glutamine concentration and ICP. Patients and Methods  In 13 patients with ALF (8F/5M; median age 46 (range 18–66) years) the cerebral extracellular concentrations of glutamine, lactate, and pyruvate were measured by in vivo brain microdialysis together with ICP and cerebral perfusion pressure (CPP). Results  The cerebral glutamine concentration was 4,396 (1,011–9,712) μM, lactate 2.15 (1.1–4.45) mM, and pyruvate 101 (43–255) μM. The lactate–pyruvate ratio was 21 (16–40), ICP 20 (2–28) mmHg, and CPP 72 (56–115) mmHg. Cerebral glutamine concentration correlated with the lactate–pyruvate ratio (r = 0.89, P < 0.05). Also the ICP, but not CPP, correlated to the lactate–pyruvate ratio (r = 0.64, P < 0.05). Conclusion  ICP and the cerebral glutamine concentration in patients with ALF correlate to the lactate–pyruvate ratio. Since CPP was sufficient in all patients the rise in lactate–pyruvate ratio indicates that accumulation of glutamine compromises mitochondrial function and causes intracranial hypertension.     

Limited diagnostic value of enzyme analysis in patients with mitochondrial tRNA mutations

We evaluated the diagnostic value of respiratory chain (RC) enzyme analysis of muscle in adult patients with mitochondrial myopathy (MM). RC enzyme activity was measured in muscle biopsies from 39 patients who carry either the 3243A>G mutation, other tRNA point mutations, or single, large‐scale deletions of mtDNA. Findings were compared with those obtained from asymptomatic relatives with the 3243A>G mutation, myotonic dystrophy patients, and healthy subjects. Plasma lactate concentration, maximal oxygen uptake, and ragged‐red fibers/cytochrome c–negative fibers in muscle were also determined. Only 10% of patients with the 3243A>G point mutation had decreased enzyme activity of one or more RC complexes, whereas this was the case for 83% of patients with other point mutations and 62% of patients with deletions. Abnormal muscle histochemistry was found in 65%, 100%, and 85% of patients, respectively, in these three groups. The results indicate that RC enzyme analysis in muscle is not a sensitive test for MM in adults. In these patients, abnormal muscle histochemistry appears to be a better predictor ofMM. Muscle Nerve, 2010     

The 2009 Schizophrenia PORT Psychosocial Treatment Recommendations and Summary Statements

The Schizophrenia Patient Outcomes Research Team (PORT) psychosocial treatment recommendations provide a comprehensive summary of current evidence-based psychosocial treatment interventions for persons with schizophrenia. There have been 2 previous sets of psychosocial treatment recommendations (Lehman AF, Steinwachs DM. Translating research into practice: the Schizophrenia Patient Outcomes Research Team (PORT) treatment recommendations. Schizophr Bull. 1998;24:1–10 and Lehman AF, Kreyenbuhl J, Buchanan RW, et al. The Schizophrenia Patient Outcomes Research Team (PORT): updated treatment recommendations 2003. Schizophr Bull. 2004;30:193–217). This article reports the third set of PORT recommendations that includes updated reviews in 7 areas as well as adding 5 new areas of review. Members of the psychosocial Evidence Review Group conducted reviews of the literature in each intervention area and drafted the recommendation or summary statement with supporting discussion. A Psychosocial Advisory Committee was consulted in all aspects of the review, and an expert panel commented on draft recommendations and summary statements. Our review process produced 8 treatment recommendations in the following areas: assertive community treatment, supported employment, cognitive behavioral therapy, family-based services, token economy, skills training, psychosocial interventions for alcohol and substance use disorders, and psychosocial interventions for weight management. Reviews of treatments focused on medication adherence, cognitive remediation, psychosocial treatments for recent onset schizophrenia, and peer support and peer-delivered services indicated that none of these treatment areas yet have enough evidence to merit a treatment recommendation, though each is an emerging area of interest. This update of PORT psychosocial treatment recommendations underscores both the expansion of knowledge regarding psychosocial treatments for persons with schizophrenia at the same time as the limitations in their implementation in clinical practice settings.