In Situ Mapping of Phase Evolutions in Rapidly Heated Zr-Based Bulk Metallic Glass with Oxygen Impurities

Metallic glasses exhibit unique mechanical properties. For metallic glass composites (MGC), composed of dispersed nanocrystalline phases in an amorphous matrix, these properties can be enhanced or deteriorated depending on the volume fraction and size distribution of the crystalline phases. Understanding the evolution of crystalline phases during devitrification of bulk metallic glasses upon heating is key to realizing the production of these composites. Here, results are presented from a combination of in situ small- and wide-angle X-ray scattering (SAXS and WAXS) measurements during heating of Zr-based metallic glass samples at rates ranging from 102 to 104 Ks-1 with a time resolution of 4ms. By combining a detailed analysis of scattering experiments with numerical simulations, for the first time, it is shown how the amount of oxygen impurities in the samples influences the early stages of devitrification and changes the dominant nucleation mechanism from homogeneous to heterogeneous. During melting, the oxygen rich phase becomes the dominant crystalline phase whereas the main phases dissolve. The approach used in this study is well suited for investigation of rapid phase evolution during devitrification, which is important for the development of MGC.

Alveolar epithelial cells are competent producers of interstitial extracellular matrix with disease relevant plasticity in a human in vitro 3D model

Alveolar epithelial cells (AEC) have been implicated in pathological remodelling. We examined the capacity of AEC to produce extracellular matrix (ECM) and thereby directly contribute towards remodelling in chronic lung diseases. Cryopreserved type 2 AEC (AEC2) from healthy lungs and chronic obstructive pulmonary disease (COPD) afflicted lungs were cultured in decellularized healthy human lung slices for 13 days. Healthy-derived AEC2 were treated with transforming growth factor ß1 (TGF-β1) to evaluate the plasticity of their ECM production. Evaluation of phenotypic markers and expression of matrisome genes and proteins were evaluated by RNA-sequencing, mass spectrometry and immunohistochemistry. The AEC2 displayed an AEC marker profile similar to freshly isolated AEC2 throughout the 13-day culture period. COPD-derived AECs proliferated as healthy AECs with few differences in gene and protein expression while retaining increased expression of disease marker HLA-A. The AEC2 expressed basement membrane components and a complex set of interstitial ECM proteins. TGF-β1 stimuli induced a significant change in interstitial ECM production from AEC2 without loss of specific AEC marker expression. This study reveals a previously unexplored potential of AEC to directly contribute to ECM turnover by producing interstitial ECM proteins, motivating a re-evaluation of the role of AEC2 in pathological lung remodelling.

Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

BACKGROUND

Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT.

METHODS

TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014-000096-80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890).

FINDINGS

From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9-81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88-1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74-2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53-8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67-1·94; p=0·64).

INTERPRETATION

In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT.

FUNDING

Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health.

Virtual Development of Process Parameters for Bulk Metallic Glass Formation in Laser-Based Powder Bed Fusion

The development of process parameters and scanning strategies for bulk metallic glass formation during additive manufacturing is time-consuming and costly. It typically involves trials with varying settings and destructive testing to evaluate the final phase structure of the experimental samples. In this study, we present an alternative method by modelling to predict the influence of the process parameters on the crystalline phase evolution during laser-based powder bed fusion (PBF-LB). The methodology is demonstrated by performing simulations, varying the following parameters: laser power, hatch spacing and hatch length. The results are compared in terms of crystalline volume fraction, crystal number density and mean crystal radius after scanning five consecutive layers. The result from the simulation shows an identical trend for the predicted crystalline phase fraction compared to the experimental estimates. It is shown that a low laser power, large hatch spacing and long hatch lengths are beneficial for glass formation during PBF-LB. The absolute values show an offset though, over-predicted by the numerical model. The method can indicate favourable parameter settings and be a complementary tool in the development of scanning strategies and processing parameters for additive manufacturing of bulk metallic glass.

Utilising an Accelerated Delphi Process to Develop Guidance and Protocols for Telepresence Applications in Remote Robotic Surgery Training

Context

The role of robot-assisted surgery continues to expand at a time when trainers and proctors have travel restrictions during the coronavirus disease 2019 (COVID-19) pandemic.

Objective

To provide guidance on setting up and running an optimised telementoring service that can be integrated into current validated curricula. We define a standardised approach to training candidates in skill acquisition via telepresence technologies. We aim to describe an approach based on the current evidence and available technologies, and define the key elements within optimised telepresence services, by seeking consensus from an expert committee comprising key opinion leaders in training.

Evidence acquisition

This project was carried out in phases: a systematic review of the current literature, a teleconference meeting, and then an initial survey were conducted based on the current evidence and expert opinion, and sent to the committee. Twenty-four experts in training, including clinicians, academics, and industry, contributed to the Delphi process. An accelerated Delphi process underwent three rounds and was completed within 72 h. Additions to the second- and third-round surveys were formulated based on the answers and comments from the previous rounds. Consensus opinion was defined as ≥80% agreement.

Evidence synthesis

There was 100% consensus regarding an urgent need for international agreement on guidance for optimised telepresence. Consensus was reached in multiple areas, including (1) infrastructure and functionality; (2) definitions and terminology; (3) protocols for training, communication, and safety issues; and (4) accountability including ethical and legal issues. The resulting formulated guidance showed good internal consistency among experts, with a Cronbach alpha of 0.90.

Conclusions

Using the Delphi methodology, we achieved international consensus among experts for development and content validation of optimised telepresence services for robotic surgery training. This guidance lays the foundation for launching telepresence services in robotic surgery. This guidance will require further validation.

Patient summary

Owing to travel restrictions during the coronavirus disease 2019 (COVID-19) pandemic, development of remote training and support via telemedicine is becoming increasingly important. We report a key opinion leader consensus view on a standardised approach to telepresence.

A multiple motion sensors index for motor state quantification in Parkinson's disease

AIM

To construct a Treatment Response Index from Multiple Sensors (TRIMS) for quantification of motor state in patients with Parkinson's disease (PD) during a single levodopa dose. Another aim was to compare TRIMS to sensor indexes derived from individual motor tasks.

METHOD

Nineteen PD patients performed three motor tests including leg agility, pronation-supination movement of hands, and walking in a clinic while wearing inertial measurement unit sensors on their wrists and ankles. They performed the tests repeatedly before and after taking 150% of their individual oral levodopa-carbidopa equivalent morning dose.Three neurologists blinded to treatment status, viewed patients' videos and rated their motor symptoms, dyskinesia, overall motor state based on selected items of Unified PD Rating Scale (UPDRS) part III, Dyskinesia scale, and Treatment Response Scale (TRS). To build TRIMS, out of initially 178 extracted features from upper- and lower-limbs data, 39 features were selected by stepwise regression method and were used as input to support vector machines to be mapped to mean reference TRS scores using 10-fold cross-validation method. Test-retest reliability, responsiveness to medication, and correlation to TRS as well as other UPDRS items were evaluated for TRIMS.

RESULTS

The correlation of TRIMS with TRS was 0.93. TRIMS had good test-retest reliability (ICC = 0.83). Responsiveness of the TRIMS to medication was good compared to TRS indicating its power in capturing the treatment effects. TRIMS was highly correlated to dyskinesia (R = 0.85), bradykinesia (R = 0.84) and gait (R = 0.79) UPDRS items. Correlation of sensor index from the upper-limb to TRS was 0.89.

CONCLUSION

Using the fusion of upper- and lower-limbs sensor data to construct TRIMS provided accurate PD motor states estimation and responsive to treatment. In addition, quantification of upper-limb sensor data during walking test provided strong results.

No-touch saphenous vein grafts in coronary artery surgery (SWEDEGRAFT): Rationale and design of a multicenter, prospective, registry-based randomized clinical trial

The SWEDEGRAFT study (ClinicalTrials.gov Identifier: NCT03501303) tests the hypothesis that saphenous vein grafts (SVGs) harvested with the "no-touch" technique improves patency of coronary artery bypass grafts compared with the conventional open skeletonized technique. This article describes the rationale and design of the randomized trial and baseline characteristics of the population enrolled during the first 9 months of enrollment. The SWEDEGRAFT study is a prospective, binational multicenter, open-label, registry-based trial in patients undergoing first isolated nonemergent coronary artery bypass grafting (CABG), randomized 1:1 to no-touch or conventional open skeletonized vein harvesting technique, with a planned enrollment of 900 patients. The primary end point is the proportion of patients with graft failure defined as SVGs occluded or stenosed >50% on coronary computed tomography angiography at 2 years after CABG, earlier clinically driven coronary angiography demonstrating an occluded or stenosed >50% vein graft, or death within 2 years. High-quality health registries and coronary computed tomography angiography are used to assess the primary end point. The secondary end points include wound healing in the vein graft sites and the composite outcome of major adverse cardiac events during the first 2 years based on registry data. Demographics of the first 200 patients enrolled in the trial and other CABG patients operated in Sweden during the same time period are comparable when the exclusion criteria are taken into consideration. RCT# NCT03501303.

Utilising the Delphi Process to Develop a Proficiency-based Progression Train-the-trainer Course for Robotic Surgery Training

CONTEXT

As the role of robot-assisted surgery continues to expand, development of standardised and validated training programmes is becoming increasingly important.

OBJECTIVE

To provide guidance on an optimised "train-the-trainer" (TTT) structured educational programme for surgical trainers, in which delegates learn a standardised approach to training candidates in skill acquisition. We aim to describe a TTT course for robotic surgery based on the current published literature and to define the key elements within a TTT course by seeking consensus from an expert committee formed of key opinion leaders in training.

EVIDENCE ACQUISITION

The project was carried out in phases: a systematic review of the current evidence was conducted, a face-to-face meeting was held in Philadelphia, and then an initial survey was created based on the current literature and expert opinion and sent to the committee. Thirty-two experts in training, including clinicians, academics, and industry, contributed to the Delphi process. The Delphi process underwent three rounds of survey in total. Additions to the second- and third-round surveys were formulated based on the answers and comments from the previous rounds. Consensus opinion was defined as ≥80% agreement.

EVIDENCE SYNTHESIS

There was 100% consensus that there was a need for a standardized TTT course in robotic surgery. A consensus was reached in multiple areas, including the following: (1) definitions and terminologies, (2) qualifications to attend, (3) course objectives, (4) precourse considerations, (5) requirement of e-learning, (6) theory and course content, and (7) measurement of outcomes and performance level verification. The resulting formulated curriculum showed good internal consistency among experts, with a Cronbach alpha of 0.90.

CONCLUSIONS

Using the Delphi methodology, we achieved an international consensus among experts to develop and reach content validation for a standardised TTT curriculum for robotic surgery training. This defined content lays the foundation for developing a proficiency-based progression model for trainers in robotic surgery. This TTT curriculum will require further validation.

PATIENT SUMMARY

As the role of robot-assisted surgery continues to expand, development of standardised and validated training programmes is becoming increasingly important. There is currently a lack of high-level evidence on how best to train trainers in robot-assisted surgery. We report a consensus view on a standardised "train-the trainer" curriculum focused on robotic surgery. It was formulated by training experts from the USA and Europe, combining current evidence for training with experts' knowledge of surgical training.

Individualization of levodopa treatment using a microtablet dispenser and ambulatory accelerometry

AIM

This 4-week open-label observational study describes the effect of introducing a microtablet dose dispenser and adjusting doses based on objective free-living motor symptom monitoring in individuals with Parkinson's disease (PD).

METHODS

Twenty-eight outpatients with PD on stable levodopa treatment with dose intervals of ≤4 hour had their daytime doses of levodopa replaced with levodopa/carbidopa microtablets, 5/1.25 mg (LC-5) delivered from a dose dispenser device with programmable reminders. After 2 weeks, doses were adjusted based on ambulatory accelerometry and clinical monitoring.

RESULTS

Twenty-four participants completed the study per protocol. The daily levodopa dose was increased by 15% (112 mg, P < 0.001) from period 1 to 2, and the dose interval was reduced by 12% (22 minutes, P = 0.003). The treatment adherence to LC-5 was high in both periods. The MDS-UPDRS parts II and III, disease-specific quality of life (PDQ-8), wearing-off symptoms (WOQ-19), and nonmotor symptoms (NMS Quest) improved after dose titration, but the generic quality-of-life measure EQ-5D-5L did not. Blinded expert evaluation of accelerometry results demonstrated improvement in 60% of subjects and worsening in 25%.

CONCLUSIONS

The introduction of a levodopa microtablet dispenser and accelerometry aided dose adjustments improve PD symptoms and quality of life in the short term.

Adverse Events during Inter-Hospital Transports on Extracorporeal Membrane Oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) may be a lifesaving rescue therapy in refractory, severe respiratory, and/or circulatory failure. To provide the best cost efficiency to the population served and patient outcome, ECMO therapy should be provided by specialized high volume ECMO centers. This requires dedicated transport teams to organize and perform these complex transports. Concerning adverse events and complications during these transfers, only a minimal amount of data has been published.

METHODS

To shed light on this matter, all medical transport records from transports on ECMO between January 2010 and June 2016 were analyzed. The data was classified in constituent groups and categorized to risk groups.

RESULTS

During the study period, 536 transports on ECMO were performed. The transport records could be identified in 514 of these cases (95.9%). In 163 (31.7%) transports 206 adverse events occurred. In 34 transports two or more adverse events passed on the same trip. No deaths occurred during transport. Sixty-five percent (134) of the complications were Patient related; the most prominent was loss of tidal volume with or without fluid flooding of the lung (n = 57, 43%). Lack of control of equipment was the most common Staff related flaw. Causes due to Equipment/technical (n = 30) could be traced to 14.6% of the events. Vehicle/transportation related complications were reported from 26 transfers, a sub-group in which 50% of the reports concerned malfunction of Ambulance utility/electrical, or Wrong ambulance size at hospital or airport.

CONCLUSIONS

If transporting on ECMO high-risk or sudden threat-of-life situations are inevitable and have to be dealt with immediately, sometimes within seconds. A well-trained staff and an experienced high-volume organization are recommended. Key words: extra corporeal membrane oxygenation; ECMO, transport; adverse event; complication.

Levodopa/carbidopa microtablets in Parkinson's disease: a study of pharmacokinetics and blinded motor assessment

Background

Motor function assessments with rating scales in relation to the pharmacokinetics of levodopa may increase the understanding of how to individualize and fine-tune treatments.

Objectives

This study aimed to investigate the pharmacokinetic profiles of levodopa-carbidopa and the motor function following a single-dose microtablet administration in Parkinson’s disease.

Methods

This was a single-center, open-label, single-dose study in 19 patients experiencing motor fluctuations. Patients received 150% of their individual levodopa equivalent morning dose in levodopa-carbidopa microtablets. Blood samples were collected at pre-specified time points. Patients were video recorded and motor function was assessed with six UPDRS part III motor items, dyskinesia score, and the treatment response scale (TRS), rated by three blinded movement disorder specialists.

Results

AUC_0–4/dose and C_max/dose for levodopa was found to be higher in Parkinson’s disease patients compared with healthy subjects from a previous study, (p = 0.0008 and p = 0.026, respectively). The mean time to maximum improvement in sum of six UPDRS items score was 78 min (±59) (n = 16), and the mean time to TRS score maximum effect was 54 min (±51) (n = 15). Mean time to onset of dyskinesia was 41 min (±38) (n = 13).

Conclusions

In the PD population, following levodopa/carbidopa microtablet administration in fasting state, the C_max and AUC_0–4/dose were found to be higher compared with results from a previous study in young, healthy subjects. A large between subject variability in response and duration of effect was observed, highlighting the importance of a continuous and individual assessment of motor function in order to optimize treatment effect.

Combination of Gadolinium and Dysprosium Chelates as a Cellular Integrity Marker in MR Imaging

A combination of gadolinium (Gd) and dysprosium (Dy) chelates was investigated as a potential marker of cell-membrane integrity by means of a double-contrast effect in MR imaging. Blood samples with varying hematocrit (Hct) levels containing intact or lysed cells were used as model systems. With intact cells, the agents were assumed to be distributed solely extracellularly and the highest Hct studied (69%) was assumed to mimic the ratio of extracellular to intracellular water in tissue. The combined effect on image intensity of Gd (in a concentration corresponding to 0.2 mmol/kg b.w. in humans) and Dy (0.6 mmol/kg b.w.) applied simultaneously was a marked difference in signal intensity between samples with intact and lysed cells in both the T1- and T2-weighted spin-echo images with a corresponding increase in the contrast-to-noise ratio. This was the result of a T1 reduction caused by Gd with a negligible Dy susceptibility effect in areas with lysed cells. On the other hand, the Dy susceptibility effect (i.e. reduced apparent T2) dominated in areas with intact cells. Thus, the combination of Gd and Dy may serve as a marker of cell-membrane integrity in MR examinations.

Dy-DTPA-BMA as an Indicator of Tissue Viability in MR Imaging

The aim of this study was to investigate whether dysprosium (Dy) induced signal intensity (SI) loss in infarcted tissue in MR imaging. Myocardial infarction was induced in 12 pigs and Dy-DTPA-BMA (1.0 mmol/kg b.w.) was administered i.v. to 6 pigs 4 hours after occlusion and allowed to accumulate in the infarctions for 2 hours. Dy was analysed by inductively coupled plasma atomic emission spectrometry in infarcted and non-ischaemic tissue samples. The remaining 6 pigs, not administered contrast medium, served as controls. The infarctions demonstrated a high SI in the proton density- and T2-weighted sequences in both groups ( ex vivo), although the Dy-DTPA-BMA group demonstrated a 3-fold greater concentration of Dy in infarcted compared with non-ischaemic myocardium. The lack of SI loss after Dy accumulation indicates that susceptibility effects are minor or absent in infarcted myocardium.

Superparamagnetic Particles as an Mri Contrast Agent for the Gastrointestinal Tract

Non-biodegradable superparamagnetic particles containing magnetite were evaluated as a potential contrast agent for the gastrointestinal tract. The particles were administered to pigs perorally either suspended in water or mixed with food. The gastrointestinal tract structures were excellently depicted through a lowered signal intensity of their content in both T1 and T2 weighted images. Relatively large volumes with low particle concentration seemed to give a good contrast agent distribution, especially when the administration was extended over a period of time. Problems with artefacts and blurring in the images caused by a too high local concentration of the contrast agent should also be minimized by using low particle concentrations.

Effect of Superparamagnetic Particles as Oral Contrast Medium at Magnetic Resonance Imaging

Non-biodegradable superparamagnetic particles were used as an oral contrast medium in different concentrations, and evaluated in 25 human volunteers. The aim of the study was to determine the most appropriate concentration of the contrast medium, and to evaluate the effect, distribution, safety and tolerance. With the concentration of 1.0 g/l a substantial reduction of the signal intensity in the bowel was achieved in both T1 and T2 weighted images. The intraabdominal structures were well differentiated from the bowels containing contrast medium. ‘Metal’ artifacts and blurring of adjacent structures, probably due to an increased local concentration, were observed at higher dosages. The distribution of the preparation in the gastrointestinal tract varied between individuals. As a rule a good contrast effect was achieved in the small bowel with the exception of the duodenum. The contrast medium was well accepted and did not cause any side effects of clinical importance. The results suggest that the preparation is well tolerated by humans and may be a useful contrast medium for abdominal MR imaging.

Oral Superparamagnetic Particles for Magnetic Resonance Imaging

As a potential gastrointestinal MR contrast medium magnetic particles have been evaluated in preclinical studies as well as in healthy volunteers. The main problem was to achieve an even distribution of the aqueous suspension of magnetic particles in the entire intestine. To improve the distribution of the contrast medium, a viscosity-increasing agent was added to the preparation. In the plain aqueous suspension the magnetic particles sedimented rapidly and caused artifacts, whereas no such sedimentation occurred in the viscous preparation. The contrast effect, as well as the presence of artifacts, increased with particle concentration. The general contrast effect was good in all 5 volunteers, and the contrast medium was well distributed in the small intestine, including the duodenum. There were no artifacts observed, and the contrast medium was well tolerated. The viscosity-increasing agent will thus be introduced in further clinical studies.

MR Imaging in Cerebral Gliomas

A comparative analysis between MR examinations and histopathologic whole-brain sections regarding tumour components was performed in 5 brain specimens from patients with malignant glial brain tumours. All cases were examined with MR imaging in vitro and in 2 cases a close comparison with the MR examinations in vivo was also possible. The most homogeneous hypercellular area in malignant gliomas, giving the highest tumour grade, was not visualised on MR imaging as an isolated entity, either in vitro or in vivo. The most conspicuous tumour component, reflecting the heterogeneity of malignant gliomas, was necrosis. This feature was best depicted in the T2WI. In 4 of 5 cases, distant tumour spread of benign-looking tumour cells was found in areas visualised as normal on T2WI, outside the margins of the peritumoural oedema. In 2 cases, estimation of water content was performed immunohistochemically and a close correlation was found in each case between peritumoural and periventricular hyperintensity on T2WI and areas of pallor on the haematoxylin-eosin-stained whole-brain sections. These areas corresponded to microscopical oedema. MR imaging reflects underlying heterogeneous histopathology in malignant gliomas. The degree of malignancy of the lesion as a whole can thus be assessed by MR imaging. However, the method does not allow malignant gliomas to be correctly delineated.

MR Imaging of Cerebrospinal Fluid Dynamics in Health and Disease

The CSF flows in the aqueduct and at the foramen magnum were examined in 5 patients with communicating hydrocephalus (HC) and in 10 with benign intracranial hypertension (BIH) as well as in 5 healthy volunteers. As compared to normal individuals, the aqueductal flow in HC was about 10 times larger and the cervical flow was half as large. In BIH the CSF flows were not different from those of normal volunteers. The decreased arterial expansion as reflected in the reduced cervical flow in HC may be due to pathologic changes in the arteries and paravascular spaces. The large aqueductal flow in HC reflects a large brain expansion, causing increased transcerebral mantle pressure gradient and ventricular dilatation. In BIH there is a normal brain expansion (aqueductal flow) and consequently no ventricular dilatation. It is argued that BIH be caused by an obstruction on the venous side, as opposed to the vascular alterations in HC, which are on the arterial side.

An Attempt to Characterize Malignant Lymphoma in Spleen, Liver and Lymph Nodes with Magnetic Resonance Imaging

An attempt was made to explore whether relaxation times and/or normalized image intensities obtained from magnetic resonance imaging (MRI) can separate malignant and non-malignant lymphomatous tissue. Spin-echo (SE) techniques with repetition times of 500 and 1500 ms and echo times of 35 and 70 ms were used for estimating T1 and T2. Estimation of T1 and T2 with such a low number of spin-echo sequences resulted in considerable variation in the data especially when T1 was long. Similar information was also extracted by normalizing the image intensities to the ‘proton density’ image (1500/35), and the spread of the data was then markedly reduced. Therefore, the method of normalizing was considered a more appropriate way of handling the image data when only a few sequences were available. No significant difference could be discerned in the MRI parameters between normal spleens and spleens infiltrated with malignant lymphoma, between normal livers and livers in patients with malignant lymphoma and between lymph nodes with low or high grade non-Hodgkin lymphoma. Lymphomatous tissue had similar MRI characteristics irrespectively of whether the cells were malignant or not, or located in spleens or in lymph nodes. The main biologic explanation for variation in data seems to be mostly the variable amounts of fibrosis, necrosis, oedema and/or iron content.

Signal Alterations, Artifacts and Image Distortion Induced by a Superparamagnetic Contrast Medium; a Phantom Study in a 0.3 Tesla MR System

In a phantom study using a 0.3 tesla MR system the signal alterations, artifacts and image distortion induced by a bowel contrast medium containing superparamagnetic magnetite particles were evaluated. A concentration of 20 mg iron/1 was most useful because it caused a significant signal reduction without disturbing artifacts and image distortion. The signal reduction was most pronounced on long TR/TE spin echo sequences. The appearance and distribution of artifacts are related to the direction of the static magnetic field and frequency encoding gradient. The size of artifacts is related to the concentration of the contrast medium and the band width used.

MR Imaging of Gadolinium-DTPA-BMA-Enhanced Reperfused and Nonreperfused Porcine Myocardial Infarction

To investigate whether Gd-DTPA-BMA-enhanced MR imaging permits differentiation between reperfused and nonreperfused myocardial infarction, myocardial infarction was induced in 12 domestic pigs. In 6 pigs, Gd-DTPA-BMA, 0.3 mmol/kg b.w. was administered i.v. 60 min after the occlusion. In 6 other pigs, the infarctions were reperfused 80 min after the occlusion, followed by injection of Gd-DTPA-BMA after 20 min of reperfusion. Radiolabeled microspheres were used to confirm zero-flow during the occlusion period and reperfusion in the infarcted myocardium. All pigs were killed 20 min after injection of contrast medium, and the hearts were excised and imaged with MR. The Gd concentration was measured in infarcted and nonischemic myocardium by ICPAES. In the reperfused hearts, the infarctions were strongly highlighted, corresponding to a 5-fold higher Gd concentration in infarcted vis-à-vis nonischemic myocardium. In the hearts subjected to occlusion without reperfusion, there was only a rim of enhancement in the peripheral part of the infarctions.

Magnetic Resonance Imaging with Maximum Contrast between Two Selected Tissues Composed of Recordings with Three Repetition Times

A method is presented which in a composed image maximizes the image intensity difference between two selected tissues. The composition is made from several magnetic resonance (MR) images from the same slice but with different MR imaging parameters. The method is illustrated with a patient with liver metastases for whom the technique was used to emphasize metastases above normal liver parenchyma.

Effect of Superparamagnetic Particles in Agarose Gels

The effect of different preparations of superparamagnetic particles, designed as potential MR contrast media for the gastrointestinal tract (oral magnetic particles, OMP, diameter of 3.5 μm, iron content 20% by weight) and for the reticuloendothelial system (intravenous magnetic particles, IMP, mean diameter of 0.3 μm, iron content 30% by weight), were evaluated in agarose gels in vitro, using a 0.5 T whole body MR system. The iron content ranged from 2.1 × 10−4 to 2.1 × 10−1 mg Fe/ml in both preparations. Both preparations reduced the signal intensities substantially over a range of concentrations in spin echo sequences. Generally, the signal intensity decreased monotonously with concentration, except for IMP at low concentrations, at which a minor signal intensity increase was observed on T1 and proton density weighted images. The reduction of the signal intensity was stronger in gradient echo and phase contrast sequences, as compared to corresponding spin echo sequences with similar timing. Both IMP and OMP had a pronounced T2 effect, the effect of IMP being stronger than that of OMP. IMP had a relatively smaller T1 effect, whereas T1 was almost unaffected by OMP. Susceptibility artifacts occurred at higher concentrations of both OMP and IMP, in all sequences used. Thus, OMP reduced the signal intensity, without causing significant artifacts, on both T1 and T2 weighted images over a relatively wide range of concentrations.

Delineation of Gliomas with Magnetic Resonance Imaging Using Gd-DTPA in Comparison with Computed Tomography and Positron Emission Tomography

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas with increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I–II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences used was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.

Field-Echo Pulse Sequences Used under Suspended Respiration for Detection of Liver Metastases

To obtain a fast MRI sequence for detection of liver metastases under suspended respiration, two healthy volunteers were examined with the field echo sequence FLASH, using a large number of repetition times, echo times, flip angles and matrix sizes. The spleen was used to simulate liver metastases and contrast-to-noise ratios between liver and spleen were calculated and the sequence with the highest ratio was considered optimal. The different FLASH sequences were also compared with spin echo sequences using short repetition and echo times. A FLASH sequence with a repetition time of 140 ms, an echo time of 14 ms, a flip angle of 80 to 100 degrees and a matrix size of 128×256 was considered the most suitable for detecting liver metastases. This sequence, together with other FLASH and spin echo sequences, were used for examination of five patients with liver metastases from endocrine gastrointestinal tumours.

Relaxation Enhancement of the Dog Liver and Spleen by Biodegradable Superparamagnetic Particles in Proton Magnetic Resonance Imaging

Bio-degradable superparamagnetic particles of about 0.5 μm diameter were investigated in 2 dogs as potential intravenous contrast enhancing agents for the reticuloendothelial system. The particles lowered the MRI signal of the liver for all investigated sequences, while the signal of the spleen was lowered only in T2 weighted sequences. No clear effect was seen on signals of fat and muscle. There was a pronounced effect on T 2 in both liver and spleen but relatively little effect on T1. Diminishing contrast effect with time indicates that the particles degrade. The particles did not have any adverse effects on the general state of the dogs or on routine liver and kidney function tests.

MR Imaging of Double-Contrast Enhanced Porcine Myocardial Infarction

MR imaging was performed to investigate whether Gd-DTPA-BMA-induced contrast enhancement of myocardial infarction is counteracted by Dy-DTPA-BMA. Myocardial infarction was induced in 5 pigs. Microdialysate probes were inserted in ischemic and nonischemic myocardium. Gd-DTPA-BMA (0.3 mmol/kg b.w.) and Dy-DTPA-BMA (1.0 mmol/kg b.w.) were administered i.v. 4 hours post occlusion. The microdialysate was collected every 10 min and measured for Gd and Dy using inductively coupled plasma atomic emission spectrometry. The pigs were sacrificed 2 hours after administration of contrast media. The concentration of both contrast agents was 3 times higher in infarcted myocardium than in nonischemic myocardium. The infarctions displayed high signal intensity in spin-echo sequences ex vivo. This lack of detectable susceptibility effects from Dy may be caused by loss of cell membrane integrity in infarcted tissue as shown by our microdialysate and biopsy data.

Mr Imaging, Flow and Motion

The present work is intended as a nonmathematical review of the role of flow and motion in nuclear magnetic resonance (MR) imaging. A historical review of MR flow measurement techniques is given, followed by a short overview of flow models in vitro and in vivo. The theory behind the influence of motion on the modulus and phase MR signal information is discussed and effects such as washin/washout, flow-induced signal void, phase offset, and phase dispersion are defined. A simple approach to the concept of MR angiography is given, and methods for quantitative flow measurements such as the phase mapping technique, are surveyed. Aspects of the measurement of diffusion and mirocirculation are given, and finally, an overview of the role of MR flow imaging in present and future clinical application is given.

Magnetic Resonance Imaging in Primary Amyloidosis

Twelve patients with primary amyloidosis (AL) were investigated with magnetic resonance imaging (MRI). In 9 patients an abnormal thickening of the heart walls was present and in 2 macroglossia was found at MRI. T1 was significantly increased in liver (p<0.05) and subcutaneous fat (p<0.01) while it was decreased in the spleen (p<0.05). T2 was significantly decreased (p<0.01) in the spleen in patients with amyloidosis, while it was not significantly altered in the liver or subcutaneous fat. After therapy T1 of the liver was reduced towards normal values in 4 patients. It is concluded that MRI might be a method to quantitate the amount of amyloid deposits in the tissue, and that the effect of therapy may be monitored with this technique.

Magnetic Resonance Imaging of Acute Myocardial Infarction in Pigs Using Gd-Dtpa

Six pigs with coronary artery occlusion were investigated with MR imaging before and subsequently for about 2.5 hours at repeated intervals after the intravenous administration of Gd-DTPA (0.4 mmol/kg). The animals were sacrificed after a total occlusion time of 6 hours and the hearts were excised. The excised hearts were then reexamined in the MR equipment and stained with TTC (triphenyl tetrazolium) in order to define areas of infarction. Four control hearts with 6-hour-old infarctions were only imaged ex vivo without any previous administration of contrast media. In vivo, there was no clear demarcation of infarction with or without Gd-DTPA. Ex vivo, without any contrast media, the infarctions were poorly discriminated with a discretely increased signal intensity relative to normal myocardium in the T2 weighted images. Gd-DTPA was found to accumulate in the infarctions, which caused an elevated signal intensity most pronounced in the T1 weighted images. This considerably improved the delineation of the infarcted area.

Motion Associated Susceptibility Artifacts

A bowel labeling agent is important for improving abdominal MR. Besides providing contrast between the bowel and other organs, the contrast agent itself is a potential source of artifacts. The artifacts created by superparamagnetic particles (SPP) subjected to motion have been studied in vitro at 0.5 T, and compared to artifacts created by a paramagnetic compound. Apart from the expected static effects of the SPP, movement induced additional artifacts were seen as signal displacements in the phase-encoding direction. The artifacts were obvious at an iron concentration of 1 mg Fe/ml, barely visible at 0.2 mg Fe/ml, and completely absent at 0.1 mg Fe/ml. Artifacts were also evident with the SPP outside the imaging slice. This further emphasizes the importance of choosing the lowest effective dose when using SPP contrast agents. For the paramagnetic agent, motion propagated artifacts consisted of high and low signal regions in a mosaic pattern.

Double-Contrast Enhanced Mr Imaging of Myocardial Infarction in the Pig

Myocardial infarction was induced by ligating a diagonal branch of the left anterior descending artery in 18 pigs. All pigs were sacrificed 6 h after the occlusion. Dysprosium diethylenetriaminepentaacetic acid bismethylamide (Dy-DTPA-BMA, 1.0 mmol/kg) was administered i.v. to 6 pigs, starting 3 min before sacrifice (injection time approximately 1 min). In a second group of 6 pigs, a double-contrast technique was used, consisting of an i.v. injection of gadolinium-DTPA-BMA (0.4 mmol/kg) 2 h before sacrifice, followed by an i.v. injection of Dy-DTPA-BMA (1.0 mmol/kg) 3 min before sacrifice. Six additional pigs, subjected to 6 h of coronary artery occlusion without administration of contrast medium, served as controls. The hearts were excised and imaged with MR. In the control animals, the infarctions demonstrated an increased signal intensity in the proton density- and T2-weighted images. Administration of Dy-DTPA-BMA primarily improved infarct visualization in the proton density- and T2-weighted images, due to reduction of signal intensity in nonischemic myocardium. The double-contrast technique further improved infarct visualization in all sequences.

Measurements of T1 and T2 over Time in Formalin-Fixed Human Whole-Brain Specimens

Abstract

T1 and T2 were measured in 5 formalin-fixed human whole-brain specimens as a function of time. Gray matter/white matter contrast reversal was observed around the 4th day and was considered to be due to the greater decrease in T1 in gray than in white matter. A possible explanation for this is that the decomposition of the myelin phospholipid structure by formalin somewhat counteracts the general reductive effect of the fixation procedure on relaxation times.

Low Flip Angle Gradient Echo Magnetic Resonance Imaging of the Cervical Spine at 0.3 Tesla

The influence of flip angle and TR on signal to noise ratio and contrast between cerebrospinal fluid (CSF) and cord was evaluated in cervical spine imaging in 5 volunteers, using gradient echo technique. All experiments were performed on a 0.3 tesla Fonar β-3000 M scanner using solenoidal surface coils. The most useful sequence was considered to be TR/TE=300/12 ms and 10° flip angle. This sequence provided images with a ‘myelographic appearance’ with good delineation of cord, CSF and epidural space. The grey and white matter was also regularly visualized. The acquisition time was considerably shorter than would have been necessary if a long TR/TE spin echo sequence had been used to obtain the same contrast pattern and the sequence was not as sensitive to motion as was the spin echo sequence. The sequence was also evaluated in 10 patients with degenerative disease and in 5 with lesions in the cord. The gradient echo sequence was found to be equal to or better than short and long TR/TE spin echo sequences in demonstrating narrowing of the spinal canal and cord lesions. The drawback is the limited signal to noise ratio.

MR-Cholangiography with a Double Contrast Technique

The combination of superparamagnetic particles (SPP) as a ‘negative’ contrast agent for the liver parenchyma and Cr-HIDA as a ‘positive’ one for the bile ducts was tested in dogs. The maximum effect of SPP was present about 30 minutes after injection with a reduction of the image intensity of the liver close to the background noise level at the highest dosages. This effect lasted for about 4 to 5 hours and it had disappeared after 24 hours. Before any contrast administration or after Cr-HIDA the bile ducts were not discernible, but a high signal in the gallbladder was present 15 to 30 minutes after injection of Cr-HIDA. After SPP the wider bile ducts were discernible because of the lowering of the signal intensity in the liver. When SPP were followed by Cr-HIDA, the bile had a higher signal intensity, and even tiny bile ducts were visible. After cholecystokinin visualization of the choledochus duct was achieved as well as contrast filling of the duodenum. The blood, urine and liver function tests were found normal during the experiments. The combination of superparamagnetic particles and Cr-HIDA seems to be a promising method for MR-cholangiography. An evaluation of the anatomic structures of the liver should be possible with this method in different pathologies.

Mr Imaging of Acute Myocardial Infarction in Pigs Using GD-Dtpa-Labeled Dextran

Myocardial infarctions were induced in 12 pigs. In 6 pigs, dextran-(Gd-DTPA)15 (≈0.1 mmol Gd/kg b.w.) was injected i.v. 4 to 4.5 hours after coronary artery occlusion. ECG gated MR images were obtained repeatedly before (n = 4) and after (n = 6) contrast medium injection. Relaxation times in blood samples were measured repeatedly. The animals were sacrificed 2 hours after contrast medium administration. The hearts were excised, reexamined in the MR equipment and stained with triphenyltetrazolium chloride (TTC) in order to define areas of infarction. The remaining 6 pigs were sacrificed 6 hours after occlusion without administration of contrast medium. These hearts were only imaged ex vivo. In vivo, the infarctions could not be identified with or without dextran-(Gd-DTPA)15. Ex vivo, without contrast medium, the infarctions had an increased signal intensity, most pronounced in the T2-weighted images. Dextran-(Gd-DTPA)15 caused a prolonged, pronounced shortening of T1 and T2 in blood samples. The infarct demarcation improved in the T1-weighted images after injection of dextran-(Gd-DTPA)15, due to a moderate enhancement in normal myocardium and a stronger enhancement at the periphery of the infarctions, while the central parts of the infarctions were only weakly enhanced.

Willingness-to-pay for benefits associated with basal insulin treatment of type 2 diabetes

Data from a 20-week trial comparing insulin detemir and neutral protamine Hagedorn (NPH) insulin in insulin-naïve people with type 2 diabetes were analyzed using willingness-to-pay (WTP) data, a proxy for patient preference. The advantages of insulin detemir relative to NPH insulin with respect to a lower hypoglycemia rate and less weight gain were associated with a value of €27.87 per month.

Long-term cost-effectiveness of insulin detemir versus NPH insulin in type 2 diabetes in Sweden

AIM

To evaluate the cost-effectiveness of insulin detemir vs. NPH insulin once daily, in patients with type 2 diabetes in the Swedish setting based on clinical data from a published randomized controlled trial.

METHODS

Projections of long-term outcomes were made using the IMS CORE Diabetes Model (CDM), based on clinical data from a 26-week randomized controlled trial that compared once daily insulin detemir and NPH insulin, when used to intensify insulin treatment in 271 patients with type 2 diabetes and body mass index (BMI) 25-40 kg/m(2). Trial results showed that insulin detemir was associated with a significantly lower incidence of hypoglycemic events and significantly less weight gain in comparison with NPH insulin. The analysis was conducted from a third party payer perspective and the base case analysis was performed over a time horizon of 40 years and future costs and clinical outcomes were discounted at a rate of 3% per year.

RESULTS

Insulin detemir was associated with higher mean (SD) quality-adjusted life expectancy (5.42 [0.10] vs. 5.31 [0.10] quality-adjusted life years [QALYs]) and lower overall costs (SEK 378,539 [10,372] vs. SEK 384,216 [11,230]; EUR 33,794 and EUR 34,300, respectively, where 1 EUR=11.2015 SEK) compared with NPH insulin. Sensitivity analysis showed that the principal driver of the benefits associated with insulin detemir was the lower rate of hypoglycemic events (major and minor events) vs. NPH insulin, suggesting that detemir might also be cost-saving over a shorter time horizon. Limitations of the analysis include the use of data from a trial outside Sweden in the Swedish setting.

CONCLUSIONS

Based on clinical input data derived from a previously published randomized controlled trial, it is likely that in the Swedish setting insulin detemir would be cost-saving in comparison with NPH insulin for the treatment of patients with type 2 diabetes.

Willingness to pay for health improvements associated with anti-diabetes treatments for people with type 2 diabetes

OBJECTIVES

This study aimed to investigate the most important consequences of diabetes medication, as measured by the patients' willingness to pay (WTP).

RESEARCH DESIGN AND METHODS

People in Sweden were recruited using existing nationwide e-mail panels if they were adults (>or=18 years) with type 2 diabetes and were receiving pharmacological anti-diabetes treatment(s). Data were collected electronically and results were analysed using a standard statistical model designed for choice games (conditional logit). Six characteristics relating to treatment of diabetes were examined: weight (gain or loss), mean glycated haemoglobin level (HbA(1c)), hypoglycaemic events, nausea, need for injections (with or independently of meals), and blood glucose testing.

RESULTS

A total of 461 people with type 2 diabetes (291 males; 170 females) completed an internet questionnaire and were eligible for inclusion. Participants placed high value on weight loss and nausea avoidance; they would pay 176 Swedish Krona (SEK)/euro15.61 per month to lose 1 kg, and would pay SEK 560 (euro49.67) per month to avoid nausea completely. Patients wanting to reduce the number of hypoglycaemic events from three per month to none were willing to pay SEK 419 (euro37.17) per month. Patients valued a 1 percentage point reduction in HbA(1c) at SEK 414 (euro36.72) per month. Participants preferred taking tablets to injections and required a compensation of SEK 376 (euro33.35) to accept one injection/day. Injections independent of meals were preferred to injections with meals (WTP: SEK 140/euro12.42 per month). Potential limitations of this study are that the preferences expressed may not match preferences in real-life situations, and bias through the use of electronic questionnaire, which restricted participation to those with access to, and experience with, the internet.

CONCLUSION

People with type 2 diabetes were willing to pay a considerable amount of money each month to lose weight, reduce or avoid hypoglycaemic events and reduce HbA(1C).

MEK-inhibitor U0126 in hyperglycaemic focal ischaemic brain injury in the rat

BACKGROUND

Hyperglycaemia aggravates ischaemic brain injury, possibly due to activation of signalling pathways involving mitogen-activated protein kinases (MAPK). In this study, the activation of MAPK/ERK was inhibited using the upstream inhibitor of MAPK-ERK-kinase (MEK) U0126, and the effects on focal brain ischaemia were evaluated during normo- and hyperglycaemia.

MATERIALS AND METHODS

Temporary (90 min) middle cerebral artery occlusion (MCAO) was induced in five groups of rats. U0126 (400 microg kg(-1)) or vehicle was given as 60-min intravenous infusions starting either 30 min prior to MCAO or 30 min prior to reperfusion. The infarct size was determined by perfusion with tetrazolium red after 24 h of survival, and the neurology was tested with the 4-level scale of Bederson and performance on an inclined plane. The inhibitory effect on the targeted MEK enzyme was investigated by analysing the phosphorylation of the downstream target ERK with western immunoblotting. Two subgroups were investigated with magnetic resonance imaging (MRI), including diffusion-weighted (DWI) and perfusion-weighted imaging (PWI).

RESULTS

U0126 effectively reduced the infarct size and improved neurology in hyperglycaemic rats both when given before and after ischemic onset. This effect was not accompanied by any detectable changes in cerebral blood flow on MRI. Normoglycaemic rats had generally milder injuries compared with the hyperglycaemic and there was a nonsignificant trend for U0126 to reduce damage also in the nonhyperglycaemic groups.

CONCLUSIONS

In conclusion, U0126 appears to be neuroprotective in this model of hyperglycaemic ischaemic brain injury. The findings support the pathogenic importance of the MEK-ERK pathway in hyperglycaemic-ischaemic brain injury.

A pilot study of facial, cranial and brain MRI morphometry in men with schizophrenia: part 2

This pilot study applies a new 3D morphometric MR method to test the hypothesis that men with schizophrenia (vs. controls) have deviant facial shapes and landmark relations in cranio/facial/brain (CFB) regions. This constitutes Part 2 of paired articles in this issue of Psychiatry Research: Neuroimaging, in which Part 1 presents the new method in detail. MRI coordinates from CFB landmarks of 23 patients and 15 controls were identified and then aligned with the Procrustes model, leaving shape as the only unit-less geometrical information. Men with schizophrenia had significantly longer mid- and lower-facial heights, and greater lower (left) facial depth, with a tendency toward rotation along the facial midline. This supports findings from earlier anthropometric and 3D studies of the "exterior" (face). In contrast, none of the patient-control differences for the new "interior" (cranial-brain) distances reached statistical significance. These results need to be retested on a larger sample of both sexes.