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Objective: To compare Dixon-based MRI techniques for intramuscular fat quantification at 3 T with MR spectroscopy (MRS) in vitro and in vivo. Methods: In vitro, two- three- and four-point mDixon (Philips Medical Systems, Best, Netherlands) sequences with 10°, 20° and 30° flip angles were acquired from seven test phantoms with sunflower oil-water percentages of 0-60% sunflower oil and calculated fat-water ratios compared with MRS. In vivo, two- three- and four-point mDixon sequences with 10° flip angle were acquired and compared with MRS in the vastus medialis of nine healthy volunteers (aged 30.6 ± 5.3 years; body mass index 22.2 ± 2.6). Results: In vitro, all mDixon sequences correlated significantly with MRS (r>0.97, p<0.002). The measured phantom percentage fat depended significantly on the flip angle (p⩽0.001) and mDixon sequence (p = 0.005). Flip angle was the dominant factor influencing agreement with MRS. Increasing the flip angle significantly increased the overestimation of the mDixon sequences compared with MRS. In vivo, a significant difference was observed between sequences (p<0.001), with all mDixon sequences overestimating the intramuscular fat content of the vastus medialis muscle compared with MRS. Two-point mDixon agreed best with MRS and had comparable variability with the other mDixon sequences. Conclusion: This study demonstrates that mDixon techniques have good linearity and low variability for use in intramuscular fat quantification. To avoid significant fat overestimation with short repetition time, a low flip angle should be used to reduce T1 effects. Advances in knowledge: This is the first study investigating the optimal mDixon parameters for intramuscular fat quantification compared with MRS in vivo and in vitro. [ABSTRACT FROM AUTHOR]

Evidence suggests that sigmoid-colonic motility is increased in patients with irritable bowel syndrome (IBS). 5-Hydroxytryptamine (5-HT) plays a role in the control of motility, but its involvement in the dysmotility seen in IBS remains unclear. To investigate the relationship between platelet depleted plasma 5-HT (PDP 5-HT) concentration and sigmoid-colonic motility in patients with IBS and healthy volunteers. Pre- and postprandial PDP 5-HT concentrations were assessed while recording sigmoid-colonic motility in 35 IBS patients (aged 19–53 years, eight male) and 16 healthy volunteers (aged 18–39 years, six male). Motility was recorded using a five-channel solid-state catheter introduced to a depth of 35 cm into an unprepared bowel. 5-Hydroxytryptamine concentration was measured by reverse-phase HPLC with fluorimetric detection. Irritable bowel syndrome patients had elevated concentrations of PDP 5-HT under fasting ( P < 0.004) and fed ( P = 0.079) conditions compared with controls. Likewise, they exhibited increased sigmoid-colonic motility under fasting (activity index: P < 0.02) and fed ( P < 0.05) conditions compared with controls. Platelet depleted plasma 5-HT concentration positively correlated with colonic activity index under both fasting ( r = 0.402; P = 0.003) and fed ( r = 0.439; P = 0.001) conditions. These data show a possible relationship between endogenous concentrations of 5-HT and sigmoid-colonic motility recorded in both IBS and healthy subjects. [ABSTRACT FROM AUTHOR]

A single-slice magnetic resonance (MR) compatible positron emission tomography (PET) system with a transaxial field of view ∼6 cm has been designed and is currently under construction. It will consist of four concentric rings of lutetium oxyorthosilicate (LSO) scintillation crystals, each coupled to one of eight multi-channel photomultplier tubes (PMTs) via 3.5 m optical fibers. The annulus containing the crystals has an outside diameter of 12 cm and is placed within the MR field of view whilst the PMTs are located outside the main magnetic field. A highly reproducible method that optimizes the amount of scintillation light that reaches the PMTs has been established. Two small sections of the scanner, each containing 4 by 4 crystal arrays, demonstrated good flood position histograms with all sixteen channels clearly identifiable. The light loss through a fiber of length of 3.25 m was approximately 70%. The spatial resolution of the two arrays in coincidence was measured at 1.6 mm full-width half-maximum (FWHM), and the temporal resolution of one array in coincidence with a single LSO crystal was measured to be 10.9 ns. The design incorporates a novel technique for improving sampling at the center of the field of view within the scanner. The concentric rings are offset with respect to one another by one quarter of the crystal width between layers resulting in significantly improved sampling. The results indicate that the PET scanner will have a performance comparable with that of current small animal systems and it will be used to investigate the utility and potential applications of combining PET and MR in small animals. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Basic investigations on the performance of a normoxic polymer gel with tetrakis-hydroxy-methyl-phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence" in the 2006 issue.

The Control of Electromagnetic Fields at Work Regulations (2016) implement the requirements of the EU Physical Agents (Electromagnetic Fields) Directive 2013 into UK Law. These regulations prohibit exposure of employees to electromagnetic fields above defined exposure limit values (ELVs). However, for MRI work activities, there is an exemption from this requirement provided that exposures are reduced to a level that is as low as is reasonably practicable. There are additional requirements for an adequate risk assessment, provision for staff training and monitoring of any health effects.This document provides specific guidance on achieving compliance with the regulations in the MRI setting. Consideration of what level of exposure is 'reasonable' is key to the proper application of these regulations. The ELVs, as defined in the regulations, are presented in terms of their relevance to exposures in the MRI-setting, what the direct and indirect effects of exposures are likely to be and what reasonable control measures can be put in place. Worked examples provide a step-by-step guide to achieving compliance with the regulations.For typical MRI working practices, it is unlikely that any permanent health effects will be experienced. Indeed, any effects that are experienced are likely to be transient and have no long-term consequences. Control measures to minimise the risks to workers in the MRI environment should already be in place in well-run units and there should be no need to implement additional control measures for exposures above the ELVs., Competing Interests: Conflicts of InterestThe authors have no conflicts of interest to declare.

Introduction: Complex cases of multiple allergies can be particularly difficult to diagnose using standard methods such as skin prick tests and assessment of a patient's allergic history. Multiplex allergy testing may improve outcomes for allergy patients by avoiding misdiagnosis and providing reassurance. The ImmunoCAP Immuno Solid-Phase Allergen Chip (ISAC) 112 is a CE-marked, molecular, multiplex, allergy test that can test for IgE antibodies to 112 components from 51 allergen sources. However, its clinical utility is unknown and is difficult to estimate due to the complexity of the diagnostic pathway in which it is used., Objective: To assess how the ImmunoCAP ISAC 112 is currently being used in UK practice. The patient populations in which it may have the most benefit were examined, and the sequence of other tests implemented alongside ISAC was determined., Methods: A retrospective audit of 100 patient cases from 2 UK tertiary allergy clinics was performed. Fifty paediatric and fifty adult cases were selected for audit. The indications for ordering an ISAC test, the other tests used alongside ISAC, and changes in management actioned by the ISAC test were investigated., Results: 73.6% of paediatric and 78% of adult patients referred for an ISAC test were suspected to have multiple sensitizations. The sequence of testing varied greatly between cases, but 70% of adult and 98% of paediatric patients had at least one other investigation prior to an ISAC test. In most cases, ISAC testing confirmed clinical suspicion., Conclusions: A prospective research study is necessary to further investigate the clinical utility and cost-effectiveness of the ISAC. A UK national registry would be of great benefit but will require a large resource base., (© 2020 S. Karger AG, Basel.)

Background: Stereotactic ablative body radiotherapy (SABR) is increasingly being used to treat oligometastatic cancers, but high-level evidence to provide a basis for policy making is scarce. Additional evidence from a real-world setting is required. We present the results of a national study of patients with extracranial oligometastases undergoing SABR, representing the largest dataset, to our knowledge, on outcomes in this population so far., Methods: In 2015, National Health Service (NHS) England launched a Commissioning through Evaluation scheme that funded a prospective, registry-based, single-arm, observational, evaluation study of patients with solid cancer and extracranial oligometastases treated with SABR. Prescribed doses ranged from 24-60 Gy administered in three to eight fractions. The study was done at 17 NHS radiotherapy centres in England. Patients were eligible for the scheme if aged 18 years or older with confirmed primary carcinoma (excluding haematological malignancies), one to three extracranial metastatic lesions, a disease-free interval from primary tumour development to metastases of longer than 6 months (with the exception of synchronous colorectal liver metastases), a WHO performance status of 2 or lower, and a life expectancy of at least 6 months. The primary outcome was overall survival at 1 year and 2 years from the start of SABR treatment. The study is now completed., Findings: Between June 15, 2015, and Jan 30, 2019, 1422 patients were recruited from 17 hospitals in England. The median age of the patients was 69 years (IQR 62-76), and the most common primary tumour was prostate cancer (406 [28·6%] patients). Median follow-up was 13 months (IQR 6-23). Overall survival was 92·3% (95% CI 90·5-93·9) at 1 year and 79·2% (76·0-82·1) at 2 years. The most common grade 3 adverse event was fatigue (28 [2·0%] of 1422 patients) and the most common serious (grade 4) event was increased liver enzymes (nine [0·6%]). Notreatment-related deaths were reported., Interpretation: In patients with extracranial oligometastatic cancer, use of SABR was associated with high overall survival and low toxicity. 'The study findings complement existing evidence from a randomised, phase 2 trial, and represent high-level, real-world evidence supporting the use of SABR in this patient cohort, with a phase 3 randomised, controlled trial to confirm these findings underway. Based on the selection criteria in this study, SABR was commissioned by NHS England in March, 2020, as a treatment option for patients with oligometastatic disease., Funding: NHS England Commissioning through Evaluation scheme., (Copyright © 2021 Elsevier Ltd. All rights reserved.)