Comparative study of magnetic resonance defaecography and evacuation proctography in the evaluation of obstructed defaecation

AIM

Obstructed defaecation syndrome is a common condition of multifactorial aetiology and requires specialized evaluation. Accurate and reproducible pelvic floor imaging is imperative for multidisciplinary decision-making. Evacuation proctography (EP) and magnetic resonance defaecography (MRD) are the main imaging modalities used to assess dynamic pelvic floor function. The aim of this prospective study was to compare the findings and acceptability of MRD and EP in the same cohort of patients.

METHOD

This was a prospective comparative study of MRD vs EP in 55 patients with obstructed defaecation syndrome in a single National Health Service Foundation Trust.

RESULTS

Fifty-five patients were recruited and underwent both EP and MRD. Detection rates for rectocoele were similar (82% vs 73%, P = 0.227), but EP revealed a significantly higher number of trapping rectocoeles compared to MRD (75% vs 31%, P < 0.001). EP detected more rectal intussusceptions than MRD (56% vs 35%, P = 0.023). MRD appeared to underestimate the size of the identified rectocoele, although it detected a significant number of anatomical abnormalities in the middle and anterior pelvic compartment not seen on EP (1.8% enterocoele, 9% peritoneocoele and 20% cystocoele). Patients achieved higher rates of expulsion of rectal contrast during EP compared to MRD, but this difference was not significant (76% vs 64% in MRD, P = 0.092). Of the two studies, patients preferred MRD.

CONCLUSIONS

MRD provides a global assessment of pelvic floor function and anatomical abnormality. MRD is better tolerated by patients but it is not as sensitive as EP in detecting trapping rectocoeles and intussusceptions.

Pricing the urban cooling benefits of solar panel deployment in Sydney, Australia

Cities import energy, which in combination with their typically high solar absorption and low moisture availability generates the urban heat island effect (UHI). The UHI, combined with human-induced warming, makes our densely populated cities particularly vulnerable to climate change. We examine the utility of solar photovoltaic (PV) system deployment on urban rooftops to reduce the UHI, and we price one potential value of this impact. The installation of PV systems over Sydney, Australia reduces summer maximum temperatures by up to 1 °C because the need to import energy is offset by local generation. This offset has a direct environmental benefit, cooling local maximum temperatures, but also a direct economic value in the energy generated. The indirect benefit associated with the temperature changes is between net AUD$230,000 and $3,380,000 depending on the intensity of PV systems deployment. Therefore, even very large PV installations will not offset global warming, but could generate enough energy to negate the need to import energy, and thereby reduce air temperatures. The energy produced, and the benefits of cooling beyond local PV installation sites, would reduce the vulnerability of urban populations and infrastructure to temperature extremes.

Aflibercept as a Second Line Therapy for Neovascular Age Related Macular Degeneration in Israel (ASLI) study

PurposeThe purpose of this study is to evaluate an early switch to aflibecept in eyes with neovascular age-related macular degeneration (nvAMD) showing partial or lack of response for initial therapy with bevacizumab.MethodsThe Aflibercept as a Second Line Therapy for Neovascular Age Related Macular Degeneration in Israel (ASLI) was a prospective, multicenter, single-arm clinical trial. Eyes with nvAMD having incomplete response to 3-9 prior bevacizumab injections were recruited. Three monthly intravitreal aflibercept (2 mg) injections were administered, followed by two bi-monthly injections and a final examination at week 28. An optional injection was allowed at week 20.ResultsForty-seven eyes of 46 patients (mean±SD age 76±8 years) were recruited. The mean number of prior bevacizumab injections was 5.5±2.9. The mean visual acuity improved from 60.3±10 ETDRS letters at baseline to 63.1±15 letters at week 28 (P=0.02, paired t-test). The central subfield thickness (CST) reduced from 409±127 micron at baseline to 330±110 microns at week 4 (P=0.0002; paired t-test), and 277±70 microns at week 28 (P=0.00002; paired t-test). Twenty-two eyes had three to five prior bevacizumab injections (mean 5.1±0.7), and 25 eyes had six to nine prior injections (7.32±1.2). Both groups had reduced CST from baseline to week 28 (P=0.0004 and P=0.0007; paired t-test, respectively). Thirty-five (75%) eyes required the optional additional aflibercept injection at week 20.ConclusionsThe ASLI study demonstrated improved BCVA and reduced CST following an early switch to aflibercept therapy in eyes with prior incomplete response to initial therapy with three to nine bevacizumab injections.

The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

History matching of a complex epidemiological model of human immunodeficiency virus transmission by using variance emulation

Complex stochastic models are commonplace in epidemiology, but their utility depends on their calibration to empirical data. History matching is a (pre)calibration method that has been applied successfully to complex deterministic models. In this work, we adapt history matching to stochastic models, by emulating the variance in the model outputs, and therefore accounting for its dependence on the model's input values. The method proposed is applied to a real complex epidemiological model of human immunodeficiency virus in Uganda with 22 inputs and 18 outputs, and is found to increase the efficiency of history matching, requiring 70% of the time and 43% fewer simulator evaluations compared with a previous variant of the method. The insight gained into the structure of the human immunodeficiency virus model, and the constraints placed on it, are then discussed.

Mercury Strain-Gauge Plethysmography Venous Mode: Non-Invasive Technique of Choice in Vascular Pathology

Mercury strain-gauge plethysmography venous mode is a non-invasive technique for exploration of the haemodynamics of the extremities. The plethysmographic parameters used are: (1) the venous inflow (in ml/100 ml/min); (2) the venous outflow (in ml/100 ml/min); (3) the venous capacity in ml/100ml; (4) the venous distensibility index in ml/100 ml/ mmHg; and (5) the venous pressure measured by ‘hysteresis curve’. This method permits us to analyse the venous haemodynamics of both extremities simultaneously (the normal limb serving as the control), to obtain a precise diagnosis and to appreciate the efficacy of treatment at follow-up.

The aetiology of the swollen limb can be precisely identified in 95% of the studied cases: oedema in superficial venous insufficiency, oedema in the deep venous insufficiency, oedema of inflammatory origin, oedema in the arterial insufficiency, oedema of cardiac origin, lymphoedema.

During the last 3 years, we have followed up 580 patients with this method.

Tauopathy PET and amyloid PET in the diagnosis of chronic traumatic encephalopathies: studies of a retired NFL player and of a man with FTD and a severe head injury

Single, severe traumatic brain injury (TBI) which elevates CNS amyloid, increases the risk of Alzheimer's disease (AD); while repetitive concussive and subconcussive events as observed in athletes and military personnel, may increase the risk of chronic traumatic encephalopathy (CTE). We describe two clinical cases, one with a history of multiple concussions during a career in the National Football League (NFL) and the second with frontotemporal dementia and a single, severe TBI. Both patients presented with cognitive decline and underwent [(18)F]-Florbetapir positron emission tomography (PET) imaging for amyloid plaques; the retired NFL player also underwent [(18)F]-T807 PET imaging, a new ligand binding to tau, the main constituent of neurofibrillary tangles (NFT). Case 1, the former NFL player, was 71 years old when he presented with memory impairment and a clinical profile highly similar to AD. [(18)F]-Florbetapir PET imaging was negative, essentially excluding AD as a diagnosis. CTE was suspected clinically, and [(18)F]-T807 PET imaging revealed striatal and nigral [(18)F]-T807 retention consistent with the presence of tauopathy. Case 2 was a 56-year-old man with personality changes and cognitive decline who had sustained a fall complicated by a subdural hematoma. At 1 year post injury, [(18)F]-Florbetapir PET imaging was negative for an AD pattern of amyloid accumulation in this subject. Focal [(18)F]-Florbetapir retention was noted at the site of impact. In case 1, amyloid imaging provided improved diagnostic accuracy where standard clinical and laboratory criteria were inadequate. In that same case, tau imaging with [(18)F]-T807 revealed a subcortical tauopathy that we interpret as a novel form of CTE with a distribution of tauopathy that mimics, to some extent, that of progressive supranuclear palsy (PSP), despite a clinical presentation of amnesia without any movement disorder complaints or signs. A key distinguishing feature is that our patient presented with hippocampal involvement, which is more frequently seen in CTE than in PSP. In case 2, focal [(18)F]-Florbetapir retention at the site of injury in an otherwise negative scan suggests focal amyloid aggregation. In each of these complex cases, a combination of [(18)F]-fluorodeoxyglucose, [(18)F]-Florbetapir and/or [(18)F]-T807 PET molecular imaging improved the accuracy of diagnosis and prevented inappropriate interventions.

Pharmacological approach to diabetic macular edema

Diabetic macular edema (DME) is a highly prevalent cause of vision loss and has a remarkable impact on public health, and on the quality of life of diabetic patients. Even though laser photocoagulation has been the standard of care for decades, a substantial group of patients are unresponsive and fail to improve after laser treatment. Recently, new pharmacological approaches based on the use of intravitreal drugs, such as corticosteroids and anti-vascular endothelial growth factor, have revolutionized the treatment of DME. The use of intravitreal drugs is supported by the improvement in visual acuity reported by several clinical trials and can limit the potentially destructive effects of the laser treatment. Encouraging results also emerged from studies evaluating the use of a combination therapy, or the association of intravitreal drugs and laser treatment. This review aims at providing a brief synopsis of the main investigations regarding the current pharmacological approach to DME.

Proposed Rabi-Kondo correlated state in a laser-driven semiconductor quantum dot

Spin exchange between a single-electron charged quantum dot and itinerant electrons leads to an emergence of Kondo correlations. When the quantum dot is driven resonantly by weak laser light, the resulting emission spectrum allows for a direct probe of these correlations. In the opposite limit of vanishing exchange interaction and strong laser drive, the quantum dot exhibits coherent oscillations between the single-spin and optically excited states. Here, we show that the interplay between strong exchange and nonperturbative laser coupling leads to the formation of a new nonequilibrium quantum-correlated state, characterized by the emergence of a laser-induced secondary spin screening cloud, and examine the implications for the emission spectrum.