A Semi-Blind Calibration and Compensation Method for Dynamic Range Recovery of Low-Power Pre-Amplifiers in MRI Receive Chains

To enable wireless MRI receive arrays, per-channel power consumption must be reduced by a significant factor. To address this, a low-power SiGe alternative to industry standard MRI pre-amplifier blocks has been proposed and its impact on imaging performance evaluated in a benchtop environment. The SiGe amplifier reduces power consumption 28x, but exhibits increased non-linearity and reduced dynamic range relative to industry standard amplifiers. This distorts the images, causing reduced contrast and a blurring of fine features. In conjunction with the amplifier, a semi-blind calibration and compensation framework has been proposed to remove artifacts caused by this non-linearity. Requiring the knowledge of the calibration signal bandwidth, the associated peak transmit powers, and the distorted baseband signals, a second non-linearity is constructed that when cascaded with the receive chain produces a linear response. This method was evaluated for both knee and phantom image datasets of peak input power -20dBm with a -40dBm peak input power image as reference. In the benchtop environment, industry standard amplifiers produced input normalized RMSEs of 0.0199 and 0.0310 for phantom and knee datasets, respectively. The low-power SiGe amplifier resulted in RMSEs of 0.0869 and 0.1130 which were reduced to 0.0158 and 0.0168 following compensation, for phantom and knee images respectively. The ability to effectively compensate for this reduced dynamic range encourages further investigation of low-power SiGe amplifiers for power limited MRI receive arrays.

An 8 channel parallel transmit system with current sensor feedback for MRI-guided interventional applications

Background.Parallel transmit (pTx) has introduced many benefits to magnetic resonance imaging (MRI) with regard to decreased specific absorption rates and improved transmit field homogeneity, of particular importance in applications at higher magnetic field strengths. PTx has also been proposed as a solution to mitigating dangerous RF induced heating of elongated conductive devices such as those used in cardiac interventions. In this work we present a system that can augment a conventional scanner with pTx, in particular for use in interventional MRI for guidewire safety, by adjusting the amplitude and phase of each channel right before the start of the imaging pulses.Methods.The pTx system was designed to work in-line with a 1.5 T MRI while the RF synthesis and imaging control was maintained on the host MR scanner. The add-on pTx system relies on the RF transmit signal, unblanking pulse, and a protocol driven trigger from the scanner. The RF transmit was split into multiple fully modulated transmit signals to drive an array of custom transceiver coils. The performance of the 8-channel implementation was tested with regards to active and real-time control of RF induced currents on a standard guidewire, heating mitigation tests, and anatomical imaging in sheep.Results. The pTx system was intended to update RF shims in real-time and it was demonstrated that the safe RF shim could be determined while the guidewire is moved. The anatomical imaging demonstrated that cardiac anatomy and neighbouring superficial structures could be fully characterized with the pTx system inline.Conclusion.We have presented the design and performance of a real-time feedback control pTx system capable of adding such capabilities to a conventional MRI with the focus of guidewire imaging in cardiac interventional MRI applications.

Immunohistochemistry Aids in the Diagnosis of Blastic Plasmacytoid Dendritic Cell Neoplasm in a Patient with Multiple Cutaneous Plaques and Nodules

Introduction/Objective

Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) is a rare hematologic malignancy of plasmacytoid dendritic cell precursors with an estimated incidence of 0.04 cases per 100,000 in the US. Given the cutaneous tropism of BPDCN, it should be differentiated from other CD56+ hematopoietic neoplasms with skin involvement such as CD56+ AML, extranodal NK/T-cell lymphoma, and other T-cell lymphomas.

Methods/Case Report

A 71-year-old male presented to the emergency department with asymptomatic, pink- violaceous plaques/nodules on the trunk for 3 months. One month prior, a dermatologist diagnosed epidermal inclusion cysts that were left untreated. The nodules progressed and a course of steroids prescribed by a primary care physician provided short term improvement before the lesions flared again. Review of systems and vitals were normal. Biopsies of representative lesions sent for histologic examination showed a diffuse dermal infiltrate of small to medium atypical cells with irregular nuclear contours, fine chromatin, one to several nucleoli and scant cytoplasm. Immunohistochemistry showed these cells were positive for CD2, CD4, CD56 and CD45 with strong expression of BCL2 and focal CD123. The cells were negative for CD3, CD20, CD79a, CD8, CD30, ALK-1, MUM-1, CD10, Cyclin- D1, C-MYC, EBER, BCL6, Langerin, Granzyme, TIA1, CD68, CD163, MPO, and Lysozyme. The histology and immunoprofile were consistent with BPDCN. A bone marrow biopsy showed cells with similar morphology and staining pattern, including expression of CD123.Treatment with chemotherapy and Tagraxofusp, was initiated. Within a week, the patient showed near resolution of cutaneous lesions. Repeat bone marrow aspirate and flow cytometry a month later showed no malignant cells.

Results (if a Case Study enter NA)

NA

Conclusion

We present this case as a rare hematologic malignancy with a challenging clinical and histopathologic diagnosis. The histologic findings suggested either a high grade myeloid or lymphoid malignancy. The combination of CD3-/CD56+/CD4+/CD123+ in the lesional cells helped establish the diagnosis of BPDCN, allowing for prompt treatment.

Achilles tendon rupture: what you need to know

Heel pain and a history of a 'pop' or feeling 'something go' are the buzz phrases classically associated with Achilles tendon rupture. However, the diagnosis is often missed in clinical practice because of the assumption that this is a sporting injury suffered only by the young or middle-aged. In a sedentary older patient, the injury may be dismissed as an ankle sprain. If swelling is present but no injury is recalled then deep vein thrombosis is suspected, but Achilles rupture is not. The diagnosis of Achilles tendon rupture is clinical, based on history and examination. Radiological imaging (ultrasound scan) is useful to plan orthopaedic management and exclude concomitant deep vein thrombosis. In most cases, non-operative management with the ankle held plantar flexed in a boot is the current best practice.

Design and implementation of a low-cost, tabletop MRI scanner for education and research prototyping

While access to a laboratory MRI system is ideal for teaching MR physics as well as many aspects of signal processing, providing multiple MRI scanners can be prohibitively expensive for educational settings. To address this need, we developed a small, low-cost, open-interface tabletop MRI scanner for academic use. We constructed and tested 20 of these scanners for parallel use by teams of 2-3 students in a teaching laboratory. With simplification and down-scaling to a 1 cm FOV, fully-functional scanners were achieved within a budget of $10,000 USD each. The design was successful for teaching MR principles and basic signal processing skills and serves as an accessible testbed for more advanced MR research projects. Customizable GUIs, pulse sequences, and reconstruction code accessible to the students facilitated tailoring the scanner to the needs of laboratory exercise. The scanners have been used by >800 students in 6 different courses and all designs, schematics, sequences, GUIs, and reconstruction code is open-source.

Safe guidewire visualization using the modes of a PTx transmit array MR system

Purpose

MRI‐guided cardiovascular intervention using standard metal guidewires can produce focal tissue heating caused by induced radiofrequency guidewire currents. It has been shown that safe operation is made possible by using parallel transmit radiofrequency coils driven in the null current mode, which does not induce radiofrequency currents and hence allows safe tissue visualization. We propose that the maximum current modes, usually considered unsafe, be used at very low power levels to visualize conductive wires, and we investigate pulse sequences best suited for this application.

Methods

Spoiled gradient echo, balanced steady‐state free precession, and turbo spin echo sequences were evaluated for their ability to visualize a conductive guidewire embedded in a gel phantom when run in maximum current modes at very low power level. Temperature at the guidewire tip was monitored for safety assessment.

Results

Excellent guidewire visualization could be achieved using maximum current modes excitation, with the turbo spin echo sequence giving the best image quality. Although turbo spin echo is usually considered to be a high‐power sequence, our method reduced all pulses to 1% amplitude (0.01% power), and heating was not detected. In addition, visualization of background tissue can be achieved using null current mode, also with no recorded heating at the guidewire tip even when running at 100% (reported) specific absorption rate.

Conclusion

Parallel transmit is a promising approach for both guidewire and tissue visualization using maximum and null current modes, respectively, for interventional cardiac MRI. Such systems can switch excitation mode instantaneously, allowing for flexible integration into interactive sequences.

Does lateral lift-off occur in static and dynamic activity in a medially spherical total knee arthroplasty? A pulsed-fluoroscopic investigation

Objectives

The medially spherical GMK Sphere (Medacta International AG, Castel San Pietro, Switzerland) total knee arthroplasty (TKA) was previously shown to accommodate lateral rollback while pivoting around a stable medial compartment, aiming to replicate native knee kinematics in which some coronal laxity, especially laterally, is also present. We assess coronal plane kinematics of the GMK Sphere and explore the occurrence and pattern of articular separation during static and dynamic activities.

Methods

Using pulsed fluoroscopy and image matching, the coronal kinematics and articular surface separation of 16 well-functioning TKAs were studied during weight-bearing and non-weight-bearing, static, and dynamic activities. The closest distances between the modelled articular surfaces were examined with respect to knee position, and proportions of joint poses exhibiting separation were computed.

Results

Overall, 1717 joint poses were analyzed. At a 1.0 mm detection threshold, 37 instances of surface separation were observed in the lateral compartment and four medially (p < 0.001). Separation was activity-dependent, both laterally and medially (p < 0.001), occurring more commonly during static deep flexion in the lateral compartment, and during static rotation in the medial compartment. Lateral separation occurred more frequently than medial during kneeling (7/14 lateral vs 1/14 medial; p = 0.031) and stepping (20/1022 lateral vs 0/1022 medial; p < 0.001). Separation varied significantly between individuals during dynamic activities.

Conclusion

No consistent association between closest distances of the articular surfaces and knee position was found during any activity. Lift-off was infrequent and depended on the activity performed and the individual knee. Lateral separation was consistent with the design rationale. Medial lift-off was rare and mostly in non-weight-bearing activities.

Cite this article: S. Key, G. Scott, J.G. Stammers, M. A. R. Freeman†, V. Pinskerova, R. E. Field, J. Skinner, S. A. Banks. Does lateral lift-off occur in static and dynamic activity in a medially spherical total knee arthroplasty? A pulsed-fluoroscopic investigation. Bone Joint Res 2019;8:207–215. DOI: 10.1302/2046-3758.85.BJR-2018-0237.R1.

Getting It Right First Time: the national survey of surgical site infection rates in NHS trusts in England

INTRODUCTION

Surgical site infections are associated with increased morbidity and mortality in patients. The Getting It Right First Time surgical site infection programme set up a national survey to review surgical site infection rates in surgical units in England. The objectives were for frontline clinicians to assess the rates of infection following selected procedures, to examine the risk of significant complications and to review current practice in the prevention of surgical site infection.

METHODS

A national survey was launched in April 2017 to assess surgical site infections within 13 specialties: breast surgery, cardiothoracic surgery, cranial neurosurgery, ear, nose and throat surgery, general surgery, obstetrics and gynaecology, ophthalmology, oral and maxillofacial surgery, orthopaedic surgery, paediatric surgery, spinal surgery, urology and vascular surgery. All participating trusts prospectively identified and collected supporting information on surgical site infections diagnosed within the six-month study period.

RESULTS

Data were received from 95 NHS trusts. A total of 1807 surgical site infection cases were reported. There were variations in rates reported by trusts across specialties and procedures. Reoperations were reported in 36.2% of all identified cases, and surgical site infections are associated with a delayed discharge rate of 34.1% in our survey.

CONCLUSION

The Getting It Right First Time surgical site infection programme has introduced a different approach to infection surveillance in England. Results of the survey has demonstrated variation in surgical site infection rates among surgical units, raised the importance in addressing these issues for better patient outcomes and to reduce the financial burden on the NHS. Much work remains to be done to improve surgical site infection surveillance across surgical units and trusts in England.

A systematic review of short metaphyseal loading cementless stems in hip arthroplasty

AIMS

Short-stemmed femoral implants have been used for total hip arthroplasty (THA) in young and active patients to conserve bone, provide physiological loading, and reduce the incidence of thigh pain. Only short- to mid-term results have been presented and there have been concerns regarding component malalignment, incorrect sizing, and subsidence. This systematic review reports clinical and radiological outcomes, complications, revision rates, and implant survival in THA using short-stemmed femoral components.

MATERIALS AND METHODS

A literature review was performed using the EMBASE, Medline, and Cochrane databases. Strict inclusion and exclusion criteria were used to identify studies reporting clinical and radiological follow-up for short-stemmed hip arthroplasties.

RESULTS

A total of 28 studies were eligible for inclusion. This included 5322 hips in 4657 patients with a mean age of 59 years (13 to 94). The mean follow-up was 6.1 years (0.5 to 20). The mean Harris Hip Score improved from 46 (0 to 100) to 92 (39 to 100). The mean Oxford Hip Score improved from 25 (2 to 42.5) to 35 (12.4 to 48). The mean Western Ontario & McMaster Universities Osteoarthritis Index improved from 54 (2 to 95) to 22 (0 to 98). Components were aligned in a neutral coronal alignment in up to 90.9% of cases. A total of 15 studies reported component survivorship, which was 98.6% (92% to 100%) at a mean follow-up of 12.1 years.

CONCLUSION

Short-stemmed femoral implants show similar improvement in clinical and radiological outcomes compared with conventional length implants. Only mid-term survivorship, however, is known. An abundance of short components have been developed and used commercially without staged clinical trials. Long-term survival is still unknown for many of these components. There remains tension between innovation and the moral duty to ensure that the introduction of new implants is controlled until safety and patient benefit are demonstrated. Implant innovation and subsequent use should be driven by proven clinical outcomes, rather than market and financial forces, and ethical practice must be ensured. Cite this article: Bone Joint J 2019;101-B:502-511.

An MRI Compatible RF MEMs Controlled Wireless Power Transfer System

In magnetic resonance imaging (MRI), wearable wireless receive coil arrays are a key technology goal. An MRI compatible wireless power transfer (WPT) system will be needed to realize this technology. An MRI WPT system must withstand the extreme electromagnetic environment of the scanner and cannot degrade MRI image quality. Here, a WPT system is developed for operation in MRI scanners using new microelectromechanical RF switch (RF MEMs) technology. The WPT system includes a class-E power amplifier, RF MEMs automated impedance matching, a primary coil array employing RF MEMs power steering, and a flexible secondary coil with class E rectification. To adapt WPT technology to MRI, techniques are developed for operation at high magnetic field, and to mitigate the RF interactions between the scanner and WPT system. A major challenge was the identification and suppression of noise and harmonic interference, by gating, filtering, and rectifier topologies. The system can achieve 63% efficiency while exceeding 13 W delivery over a coil distance of 3.5 cm. For continuous WPT beyond 5W, added filters and full-wave class E rectification lowers harmonic generation at some cost to efficiency, while image SNR reaches about 32% of the ideal. RF-gated WPT, which interrupts power transfer in the MRI signal acquisition interval, achieves SNR performance to within 1 dB of the ideal. With further refinement, the inclusion of WPT technology in MRI scanners appears completely feasible.

Evaluation of a Flexible 12-Channel Screen-printed Pediatric MRI Coil

Background Screen-printed MRI coil technology may reduce the need for bulky and heavy housing of coil electronics and may provide a better fit to patient anatomy to improve coil performance. Purpose To assess the performance and caregiver and clinician acceptance of a pediatric-sized screen-printed flexible MRI coil array as compared with conventional coil technology. Materials and Methods A pediatric-sized 12-channel coil array was designed by using a screen-printing process. Element coupling and phantom signal-to-noise ratio (SNR) were assessed. Subjects were scanned by using the pediatric printed array between September and November 2017; results were compared with three age- and sex-matched historical control subjects by using a commercial 32-channel cardiac array at 3 T. Caregiver acceptance was assessed by asking nurses, technologists, anesthesiologists, and subjects or parents to rate their coil preference. Diagnostic quality of the images was evaluated by using a Likert scale (5 = high image quality, 1 = nondiagnostic). Image SNR was evaluated and compared. Results Twenty study participants were evaluated with the screen-printed coil (age range, 2 days to 12 years; 11 male and nine female subjects). Loaded pediatric phantom testing yielded similar noise covariance matrices and only slightly degraded SNR for the printed coil as compared with the commercial coil. The caregiver acceptance survey yielded a mean score of 4.1 ± 0.6 (scale: 1, preferred the commercial coil; 5, preferred the printed coil). Diagnostic quality score was 4.5 ± 0.6. Mean image SNR was 54 ± 49 (paraspinal muscle), 78 ± 51 (abdominal wall muscle), and 59 ± 35 (psoas) for the printed coil, as compared with 64 ± 55, 65 ± 48, and 57 ± 43, respectively, for the commercial coil; these SNR differences were not statistically significant (P = .26). Conclusion A flexible screen-printed pediatric MRI receive coil yields adequate signal-to-noise ratio in phantoms and pediatric study participants, with similar image quality but higher preference by subjects and their caregivers when compared with a conventional MRI coil. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Lamb in this issue.

An RF-gated wireless power transfer system for wireless MRI receive arrays

In MRI systems, cable-free receive arrays would simplify setup while reducing the bulk and weight of coil arrays and improve patient comfort and throughput. Since battery power would limit scan time, wireless power transfer (WPT) is a viable option to continuously supply several watts of power to on-coil electronics. To minimize added noise and decouple the wireless power system from MRI coils, restrictions are placed on the coil geometry of the wireless power system, which are shown to limit its efficiency. Continuous power harvesting can also cause a large increase in the background noise of the image due to diode rectifier up-conversion of noise around the frequency of the transmitted power. However, by RF gating the transmitted power off during the MRI receive time while continuing to supply power from a storage capacitor, WPT is demonstrated to have minimal impact on image quality at received power levels up to 11 W. The integration of WPT with a 1.5T scanner is demonstrated.

Abstract P6-11-01: CDK2 inhibition prevents ERpS294 and restores the ability of tamoxifen to induce regression in breast tumors expressing mutant ESR1

This abstract was withdrawn by the authors.

Hepatitis C virus among genitourinary clinic attenders in Scotland: unlinked anonymous testing

Our objective is to gauge the prevalence of hepatitis C virus (HCV) antibodies among a population at risk of contracting sexually transmitted infections (STIs) and, thus, the efficiency with which the virus is transmitted sexually. The investigators undertook an unlinked anonymous HCV antibody testing study of residual syphilis serology specimens taken from attenders of genitourinary clinics in Glasgow, Edinburgh and Aberdeen during 1996/97. The results were linked to non-identifying risk information. Anti-HCV prevalences among non-injecting heterosexual men and women, and non-injecting homosexual/bisexual males ranged between 0 and 1.2%; the only exception to this was a 7.7% (4/52) prevalence among homosexual/bisexual males in Aberdeen. The overall anti-HCV prevalence for homosexual/bisexual males was 0.6% (4/668), for heterosexual males 0.8% (32/4135), for heterosexual females 0.3% (10/3035) and for injecting drug users 49% (72/148). Only 3 (all female) of the 46 non-injectors who were antibody positive were non-UK nationals or had lived abroad. HCV antibody positive injectors were less likely to have an acute STI and more likely to know their HCV status than non-injectors; no differences in these parameters were found between positive and negative non-injectors on anonymous HCV antibody testing. Our findings are in keeping with the prevailing view that HCV can be acquired through sexual intercourse but, for most people, the probability of this occurring is extremely low. Interventions to prevent the spread of HCV should be targeted mainly at injecting drug user (IDU) populations.

A Millimeter-Wave Digital Link for Wireless MRI

A millimeter (mm) wave radio is presented in this work to support wireless MRI data transmission. High path loss and availability of wide bandwidth make mm-waves an ideal candidate for short range, high data rata communication required for wireless MRI. The proposed system uses a custom designed integrated chip (IC) mm-wave radio with 60 GHz as radio frequency carrier. In this work, we assess performance in a 1.5 T MRI field, with the addition of optical links between the console room and magnet. The system uses ON-OFF keying (OOK) modulation for data transmission and supports data rates from 200 Mb/s to 2.5 Gb/s for distances up-to 65 cm. The presence of highly directional, linearly polarized, on-chip dipole antennas on the mm-wave radio along with the time division multiplexing (TDM) circuitry allows multiple wireless links to be created simultaneously with minimal inter-channel interference. This leads to a highly scalable solution for wireless MRI.

The Dentin Matrix Protein 1 (Dmp1) is Specifically Expressed in Mineralized, but not Soft, Tissues during Development

Dentin Matrix Protein 1 ( Dmp1) was originally identified from dentin. However, its expression and function in vivo are not clear. To clarify these two issues, we have generated mice carrying a truncated Dmp1 gene by using gene targeting to replace exon 6 with a lacZ gene. Northern blot analysis shows the expected 5.8-kb Dmp1-lacZ fusion transcript and loss of the wild-type 2.8-kb Dmp1 transcript, confirmed by a lack of immunostaining for the protein. Using heterozygous animals, we demonstrate that Dmp1 is specific for mineralized tissues. Not previously shown, Dmp1 is also expressed in pulp cells. Dmp1-deficient embryos and newborns display no apparent gross abnormal phenotype, although there are a modest expansion of the hypertrophic chondrocyte zone and a modest increase in the long bone diameter. This suggests that DMP1 is not essential for early mouse skeletal or dental development.

UKCC staff set for showdown with ralph

The management dispute at nursing's regulatory body is expected to enter its final phase later this week, with eight senior staff set to issue an official grievance against Registrar Colin Ralph.

14-Vertex Heteroboranes with 14 Skeletal Electron Pairs: An Experimental and Computational Study

Three isomers of [(Cp*Ru)2 C2 B10 H12 ], the first examples of 14-vertex heteroboranes containing 14-skeletal electron pairs, have been synthesized by the direct electrophilic insertion of a {Cp*Ru(+) } fragment into the anion [4-Cp*-4,1,6-RuC2 B10 H12 ](-) . All three compounds have the same unique polyhedral structure having an approximate Cs symmetry and featuring a four-atom trapezoidal face. X-ray diffraction studies could confidently identify only one of the two cage C atoms in each structure. The other C atom position has been established by a combination of i) best fitting of computed and experimental (11) B and (1) H NMR chemical shifts, and ii) consideration of the lowest computed energy for series of isomers studied by DFT calculations. In all three isomers, one cage C atom occupies a degree-4 vertex on the short parallel edge of the trapezium.

Comparison of time to undetectable HIV viral load in the first 16 weeks after the start of three and four antiretroviral regimens

The aim of this paper is to compare the time to a viral load <50 copies/mL of three or four antiretroviral therapy (ART) regimens among ART naïve patients within the first 16 weeks after the start of treatment. A retrospective study was carried out on ART naïve patients who started HAART between 1 January 1999 and 1 January 2004. ART naïve patients with a viral load >5.3 log10 copies/mL at the time of treatment were routinely started on four ART regimens in one of the HIV centres in Edinburgh. These patients were compared with ART naïve patients with viral load >5.3 log10 copies/mL at the time of start of three ART regimens in the other centre within the study period. During the study period, of 93 ART naïve patients with a viral load >5.3 log10 copies/mL, 56 and 37 commenced four drug and three drug regimens, respectively. Patients in each group were matched for their age, prevalence of HCV, median age, and median viral load at the start of therapy; however, patients on three drug regimens had significantly lower CD4 counts ( P<0.01). The median time to undetectable viral load was 13.5 weeks for three and four drug regimens ( P>0.05). By the time of undetectable viral load, there was no difference in the CD4 count of patients on three or four drug regimens. Similar proportions of immunosuppressed patients on three and four ART regimens had undetectable viral load within the first 16 weeks of therapy.

Heterosexual men and women with HIV test positive at a later stage of infection than homo- or bisexual men

The current strategy of offering HIV testing to individuals with known risk has had no impact on the reduction in the number of patients diagnosed with immune suppression of infection. A prospective observational study to compare the baseline CD4+ T-cell counts in HIV-infected homosexual/bisexual men, intravenous drug users, heterosexual men and women diagnosed in GUM/RIDU and that of patients diagnosed during routine maternal screening for HIV between December 1999 and January 2003 was carried out at the Departments of Genitourinary Medicine (GUM), Regional Infectious Disease Unit (RIDU) and Obstetrics in Edinburgh.

Late presentation was defined as positive HIV test with baseline CD4+ T-cell count of less than 200 cells/mL.

During the study period, 189 patients tested in GUM/RIDU setting and 13 screened women were diagnosed with HIV infection. Thirty-four percent of the former and 38% of the latter group had CD4+ T-cell count of less than 200 cells/mL by the time of diagnosis. Heterosexual individuals contributed to 78% of HIV tests in the GUM/RIDU setting. Amongst the 78 HIV-infected heterosexual individuals diagnosed in GUM/RIDU 45% were late presenters. Significantly fewer homosexual men were late presenters. There was no difference between the proportion of late presenters amongst women screened at the antenatal (5/13) compared to heterosexual patients diagnosed in GUM/RIDU (35/78). A significant number of HIV infected heterosexual patients are late presenters in the HIV testing at GUM/RIDU. HIV screening programmes for heterosexual individuals in any medical encounter may reduce the number of late presenters.

Screen-printed flexible MRI receive coils

Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners.

Signal-to-noise ratio is one of the key factors that currently limit the diagnostic image quality and patient conditions of magnetic resonance imaging. Here, Corea et al. use fully printed flexible receive coils, conforming to patient bodies, to improve signals and patient comfort in clinical scanners.

Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised? A pulsed fluoroscopic investigation

OBJECTIVES

Throughout the 20th Century, it has been postulated that the knee moves on the basis of a four-bar link mechanism composed of the cruciate ligaments, the femur and the tibia. As a consequence, the femur has been thought to roll back with flexion, and total knee arthroplasty (TKA) prostheses have been designed on this basis. Recent work, however, has proposed that at a position of between 0° and 120° the medial femoral condyle does not move anteroposteriorly whereas the lateral femoral condyle tends, but is not obliged, to roll back - a combination of movements which equates to tibial internal/ femoral external rotation with flexion. The aim of this paper was to assess if the articular geometry of the GMK Sphere TKA could recreate the natural knee movements in situ/in vivo.

METHODS

The pattern of knee movement was studied in 15 patients (six male: nine female; one male with bilateral TKAs) with 16 GMK Sphere implants, at a mean age of 66 years (53 to 76) with a mean BMI of 30 kg/m(2) (20 to 35). The motions of all 16 knees were observed using pulsed fluoroscopy during a number of weight-bearing and non-weight-bearing static and dynamic activities.

RESULTS

During maximally flexed kneeling and lunging activities, the mean tibial internal rotation was 8° (standard deviation (sd) 6). At a mean 112° flexion (sd 16) during lunging, the medial and lateral condyles were a mean of 2 mm (sd 3) and 8 mm (sd 4) posterior to a transverse line passing through the centre of the medial tibial concavity. With a mean flexion of 117° (sd 14) during kneeling, the medial and lateral condyles were a mean of 1 mm (sd 4) anterior and 6 mm (sd 4) posterior to the same line. During dynamic stair and pivoting activities, there was a mean anteroposterior translation of 0 mm to 2 mm of the medial femoral condyle. Backward lateral condylar translation occurred and was linearly related to tibial rotation.

CONCLUSION

The GMK Sphere TKA in our study group shows movements similar in pattern, although reduced in magnitude, to those in recent reports relating to normal knees during several activities. Specifically, little or no translation of the medial femoral condyle was observed during flexion, but there was posterior roll-back of the lateral femoral condyle, equating to tibiofemoral rotation. We conclude that the GMK Sphere is anteroposteriorly stable medially and permits rotation about the medial compartment.Cite this article: Professor G. Scott. Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised?: A pulsed fluoroscopic investigation. Bone Joint Res 2016;5:80-86. DOI: 10.1302/2046-3758.53.2000621.

Controlling radiofrequency-induced currents in guidewires using parallel transmit

PURPOSE

Elongated conductors, such as pacemaker leads, neurostimulator leads, and conductive guidewires used for interventional procedures can couple to the MRI radiofrequency (RF) transmit field, potentially causing dangerous tissue heating. The purpose of this study was to demonstrate the feasibility of using parallel transmit to control induced RF currents in elongated conductors, thereby reducing the RF heating hazard.

METHODS

Phantom experiments were performed on a four-channel parallel transmit system at 1.5T. Parallel transmit "null mode" excitations that induce minimal wire current were designed using coupling measurements derived from axial B1 (+) maps. The resulting current reduction performance was evaluated with B1 (+) maps, current sensor measurements, and fluoroptic temperature probe measurements.

RESULTS

Null mode excitations reduced the maximum coupling mode current by factors ranging from 2 to 80. For the straight wire experiment, a current null imposed at a single wire location was sufficient to reduce tip heating below detectable levels. For longer insertion lengths and a curved geometry, imposing current nulls at two wire locations resulted in more distributed current reduction along the wire length.

CONCLUSION

Parallel transmit can be used to create excitations that induce minimal RF current in elongated conductors, thereby decreasing the RF heating risk, while still allowing visualization of the surrounding volume.

The exopolyhedral ligand orientation (ELO) in 3-(nitrato-κO)-3,3-bis(triphenylphosphane-κP)-3-rhoda-1,2-dicarba-closo-dodecaborane(11) dichloromethane 2.2-solvate

In the title compound, [Rh(C2H11B9)(NO3)(C18H15P)2]·2.2CH2Cl2, studied as a 2.2-solvate of what was assumed to be dichloromethane, the nitrate ligand liesciswith respect to both cage C atoms. Accordingly, the compound displays a pronounced preferred exopolyhedral ligand orientation (ELO) which is traced to both the greatertransinfluence of the cage B over the cage C atoms and the greatertransinfluence of the triphenylphosphane ligands over the nitrate ligand. The overall molecular architecture therefore agrees with that of a number of similar 3-L-3,3-L′2-3,1,2-closo-MC2B9H11species in the literature.

Physiologically Based Models in Regulatory Submissions: Output From the ABPI/MHRA Forum on Physiologically Based Modeling and Simulation

Under the remit of the Ministerial Industry Strategy Group (MISG), the Association of the British Pharmaceutical Industry (ABPI) and Medicines and Healthcare products Regulatory Agency (MHRA) hosted a meeting to explore physiologically based pharmacokinetic modeling and simulation, focusing on the clinical component of regulatory applications. The meeting took place on 30 June 2014 with international representatives from industry, academia, and regulatory agencies. Discussion topics were selected to be complementary to those discussed at an earlier US Food and Drug Administration (FDA) meeting. This report summarizes the meeting outcomes, focusing on the European regulatory perspective.

Strategies for distinguishing between B and C atoms in metallacarborane cages

Carboranes and metallacarboranes demonstrate diverse geometric structures. Carborane cages are comprised of a mixture of carbon and boron vertices whereas metallacarboranes contain one or more metal atoms in addition to C and B atoms. The most common structure is the 12 vertex icosahedron but sub-icosahedral and supraicosahedral (13 vertex and even 14 and 15 vertex) cages are known. A common problem in structural studies of such species is how to distinguish between C and B given their very similar X-ray scattering powers. Usually in crystallography, displacement parameters and the Hirshfeld test are used as tools to check whether elemental assignment is correct. Although these are very useful in many circumstances, there are occasions when the displacement parameters are less well-defined and the Hirshfeld results consequently unreliable. Since correct element assignment is crucial in understanding the chemistries of carboranes and metallacarboranes we have developed new techniques to distinguish the C atom positions from the B atom positions in these cages. At Heriot-Watt University we have recently reported the Vertex-to-Centroid Distance (VCD) method [1] and a complementary approach, the Boron–H Distance (BHD) method [2], which was first communicated in 2002 [3]. The VCD and BHD methods have been used to distinguish between cage B and cage C atoms in a wide range of crystallographically-determined structures, both leading to the same clear conclusions and thus allowing the identities of these species to be established unambiguously. The methods are particularly useful when traditional approaches, e.g. using displacement parameters, fail, as demonstrated for asymmetric 14-vertex metallacarboranes [2] (Figure).

Single-stage revision for the infected total knee replacement: results from a single centre

Peri-prosthetic infection is amongst the most common causes of failure following total knee replacement (TKR). In the presence of established infection, thorough joint debridement and removal of all components is necessary following which new components may be implanted. This can be performed in one or two stages; two-stage revision with placement of an interim antibiotic-loaded spacer is regarded by many to be the standard procedure for eradication of peri-prosthetic joint infection. We present our experience of a consecutive series of 50 single-stage revision TKRs for established deep infection performed between 1979 and 2010. There were 33 women and 17 men with a mean age at revision of 66.8 years (42 to 84) and a mean follow-up of 10.5 years (2 to 24). The mean time between the primary TKR and the revision procedure was 2.05 years (1 to 8). Only one patient required a further revision for recurrent infection, representing a success rate of 98%. Nine patients required further revision for aseptic loosening, according to microbiological testing of biopsies taken at the subsequent surgery. Three other patients developed a further septic episode but none required another revision. These results suggest that a single-stage revision can produce comparable results to a two-stage revision. Single-stage revision offers a reduction in costs as well as less morbidity and inconvenience for patients.

Out of sight, but not out of mind? Greater reported pain in patients who spontaneously look away during venepuncture

BACKGROUND

Various external factors can influence patients' experiences of noxious stimuli, but little is known of how patients' natural behaviour may be relevant. We ascertained how often patients spontaneously look or look away during venepuncture and associated reports of pain during a previously reported experimental randomized study. The study was conducted in the outpatient department of a U.K. district general hospital.

METHODS

Patients were randomized to hearing 'sharp scratch' or the verbal cue 'ready?' immediately before venepuncture. Whether patients looked or looked away during needle insertion was recorded. Patients were asked to rate their pain using a verbal numerical rating score (VNRS) and verbal response scale (VRS).

RESULTS

One hundred ninety-two patients were included; mean age 51.7 years, 55% male. During needle insertion, 73% spontaneously looked away, whereas 27% looked. There was no significant difference in the proportion of these patients assigned to the 'sharp scratch' or 'ready?' groups, nor was there any difference in mean age or gender. For the group that looked, mean VNRS was 0.48 and VRS was 1.27, significantly less than the group that looked away (mean VNRS 0.94, p = 0.014; VRS 1.61, p = 0.002). As previously reported, pain ratings between 'sharp scratch' and 'ready?' groups were not significantly different.

CONCLUSIONS

Almost three quarters of patients spontaneously look away during venepuncture, but their pain ratings are almost twice that of the quarter of patients who look. It is unclear why this may be, but previous experimental studies indicate that observing the body when a noxious stimulus is applied can have an analgesic effect.

Interventional device visualization with toroidal transceiver and optically coupled current sensor for radiofrequency safety monitoring

PURPOSE

The development of catheters and guidewires that are safe from radiofrequency (RF) -induced heating and clearly visible against background tissue is a major challenge in interventional MRI. An interventional imaging approach using a toroidal transmit-receive (transceive) coil is presented. This toroidal transceiver allows controlled, low levels of RF current to flow in the catheter/guidewire for visualization, and can be used with conductive interventional devices that have a localized low-impedance tip contact.

METHODS

Toroidal transceivers were built, and phantom experiments were performed to quantify transmit power levels required for device visibility and to detect heating hazards. Imaging experiments in a pig cadaver tested the extendibility to higher field strength and nonphantom settings. A photonically powered optically coupled toroidal current sensor for monitoring induced RF currents was built, calibrated, and tested using an independent image-based current estimation method.

RESULTS

Results indicate that high signal-to-noise ratio visualization is achievable using milliwatts of transmit power-power levels orders of magnitude lower than levels that induce measurable heating in phantom tests. Agreement between image-based current estimates and RF current sensor measurements validates sensor accuracy.

CONCLUSION

The toroidal transceiver, integrated with power and current sensing, could offer a promising platform for safe and effective interventional device visualization.

Antifungal step-down therapy based on hospital intravenous to oral switch policy and susceptibility testing in adult patients with candidaemia: a single centre experience

AIMS

Echinocandins are recommended for the treatment of candidaemia in moderately severe to severely ill patients. Step-down or de-escalation from echinocandin to fluconazole is advised in patients who are clinically stable but data in relation to step-down therapy are sparse. Using our hospital intravenous to oral switch therapy (IVOST) policy to guide antifungal de-escalation in patients with candidaemia, we aimed to determine what proportion of patients are de-escalated to fluconazole, the timescale to step-down, associated reduction in consumption of echinocandins and antifungal cost savings.

METHODOLOGY

Patients with candidaemia were followed from April 2011 to March 2013.

RESULTS

A total of 37 episodes of candidaemia were documented during the study period. Twenty-seven patients were commenced on an echinocandin or voriconazole and 19 (70.3%) were de-escalated to fluconazole based on the IVOST policy. The mean and median number of days to de-escalation of therapy was 4.6 and 5 days, respectively. One patient whose therapy was de-escalated relapsed. The overall 30 day crude mortality was 37.1%. The step-down approach led to significant saving in antifungal drug cost of £1133.88 per candidaemic episode and £2208.08 per de-escalation.

CONCLUSION

Implementation of IVOST policy led to streamlining of antifungal therapy.

A case of multicentric Castleman's disease in HIV infection with the rare complication of acquired angioedema

Multicentric Castleman's disease (MCD), a polyclonal lymphoproliferative disorder of unknown aetiology, is a well-recognised complication of HIV disease. We present a case of MCD in an HIV-positive patient that is unusual on two counts: our patient's MCD first presented in the context of an immune restoration inflammatory syndrome (IRIS), following the initiation of highly active antiretroviral therapy (HAART). In addition, her MCD was associated with the unusual complication of acquired angioedema (AAE), which resolved following treatment of the MCD. While AAE is frequently found to have an underlying diagnosis of a lymphoproliferative disease, this is the first reported case linking AAE to MCD.

Cardiac responses to 24 hrs hyperoxia in Bmp2 and Bmp4 heterozygous mice

BACKGROUND

Hyperoxia or clinical oxygen (O2) therapy is known to result in increased oxidative burden. Therefore, understanding susceptibility to hyperoxia exposure is clinically important. Bone morphogenetic proteins (BMPs) 2 and 4 are involved in cardiac development and may influence responses to hyperoxia.

METHODS

Bmp2(+/)(-). Bmp4(+/)(-) and wild-type mice were exposed to hyperoxia (100% O2) for 24 hrs. Electrocardiograms (ECG) were recorded before and during exposure by radio-telemetry.

RESULTS

At baseline, a significantly higher low frequency (LF) and total power (TP) heart rate variability (HRV) were found in Bmp2(+/)(-) mice only (p < 0.05). Twenty-four hours hyperoxia-induced strain-independent reductions in heart rate, QTcB and ST-interval and increases in QRS, LF HRV and standard deviation of RR-intervals were observed. In Bmp4(+/)(-) mice only, increased PR-interval (PR-I) (24 hrs), P-wave duration (P-d; 18 and 21-24 hrs), PR-I minus P-d (PR - Pd; 24 hrs) and root of the mean squared differences of successive RR-intervals (24 hrs) were found during hyperoxia (p < 0.05).

DISCUSSION

Elevated baseline LF and TP HRV in Bmp2(+/)(-) mice suggests an altered autonomic nervous system regulation of cardiac function in these mice. However, this was not related to strain specific differences in responses to 24 hrs hyperoxia. During hyperoxia, Bmp4(+/-) mice were the most susceptible in terms of atrioventricular conduction changes and risk of atrial fibrillation, which may have important implications for patients treated with O2 who also harbor Bmp4 mutations. This study demonstrates significant ECG and HRV responses to 24 hrs hyperoxia in mice, which highlights the need to further work on the genetic mechanisms associated with cardiac susceptibility to hyperoxia.

The neural guidance receptor Plexin C1 delays melanoma progression

Plexin C1 is a type I transmembrane receptor with intrinsic R-Ras GTPase activity, which regulates cytoskeletal remodeling and adhesion in normal human melanocytes. Melanocytes are pigment-producing cells of the epidermis, precursors for melanoma, and express high levels of Plexin C1, which is lost in melanoma in vitro and in vivo. To determine if Plexin C1 is a tumor suppressor for melanoma, we introduced Plexin C1 into a primary human melanoma cell line, and phenotypes including migration, apoptosis, proliferation and tumor growth in mice were analyzed. Complimentary studies in which Plexin C1 was silenced in human melanocytes were performed. Plexin C1 significantly inhibited migration and proliferation in melanoma, whereas in melanocytes, loss of Plexin C1 increased migration and proliferation. In mouse xenografts, Plexin C1 delayed tumor growth of melanoma at early time points, but tumors eventually escaped the suppressive effects of Plexin C1, due to Plexin C1-dependent activation of the pro-survival protein Akt. R-Ras activation stimulates melanoma migration. Plexin C1 lowered R-Ras activity in melanoma and melanocytes, consistent with inhibitory effects of Plexin C1 on migration of melanocytes and melanoma. To determine if R-Ras is expressed in melanocytic lesions in vivo, staining of tissue microarrays of nevi and melanoma were performed. R-Ras expression was highly limited in melanocytic lesions, being essentially confined to primary melanoma, and almost completely absent in nevi and metastatic melanoma. These data suggest that loss of Plexin C1 in melanoma may promote early steps in melanoma progression through suppression of migration and proliferation, but pro-survival effects of Plexin C1 ultimately abrogate the tumor suppressive effects of Plexin C1. In primary melanoma, loss of Plexin C1 may function in early steps of melanoma progression by releasing inhibition of R-Ras activation, and stimulating migration.

Untethered 4,1,2-MC2B10 supraicosahedral metallacarboranes, their C,C'-dimethyl 4,1,6-, 4,1,8- and 4,1,12-MC2B10 analogues, and DFT study of the (4,)1,2- to (4,)1,6-isomerisations of C2B11 carboranes and MC2B10 metallacarboranes

Reduction of the tethered carborane 1,2-μ-(CH(2)SiMe(2)CH(2))-1,2-closo-C(2)B(10)H(10) followed by metallation with {CpCo} or {(p-cymene)Ru} fragments affords both C,C'-dimethyl 4,1,2-MC(2)B(10) and 4,1,6-MC(2)B(10) species. DFT calculations indicate that the barriers to isomerisation of both 4-Cp-4,1,2-closo-CoC(2)B(10)H(12) and 4-(η-C(6)H(6))-4,1,2-closo-RuC(2)B(10)H(12) to their respective 4,1,6-isomers are too high for this to be the origin of the unexpected formation of 4,1,6-MC(2)B(10) products (in marked contrast to the related isomerisation of 1,2-closo-C(2)B(11)H(13) to 1,6-closo-C(2)B(11)H(13)), and, indeed, the 4,1,2-species are recovered unchanged from refluxing toluene. Equally, the DFT-calculated profile for the isomerisation of [7,8-nido-C(2)B(10)H(12)](2-) to [7,9-nido-C(2)B(10)H(12)](2-) suggests that the unexpected formation of 4,1,6-metallacarboranes is unlikely to result from isomerisation of a reduced (nido) carborane following desilylation. Instead, the source of the 4,1,6-MC(2)B(10) compounds is traced to desilylation of 1,2-μ-(CH(2)SiMe(2)CH(2))-1,2-closo-C(2)B(10)H(10) by Li or Na prior to reduction. The supraicosahedral metallacarboranes 1,8-Me(2)-4-Cp-4,1,8-closo-CoC(2)B(10)H(10), 1,12-Me(2)-4-Cp-4,1,12-closo-CoC(2)B(10)H(10) and 1,12-Me(2)-4-(p-cymene)-4,1,12-closo-RuC(2)B(10)H(10) are also reported with all new species characterised both spectroscopically and crystallographically.