A new software scheme for scatter correction based on a simple radiographic scattering model

In common radiography, image contrast is often limited due mainly to scattered x-rays and noise, decreasing the quantitative usefulness of x-ray images. Several scatter reduction methods based on software correction schemes have been extensively investigated in an attempt to overcome these difficulties, most of which are based on measurement, mathematical-physical modeling, or a combination of both. However, those methods require special equipment, system geometry, and extra manual work to measure scatter characteristics. In this study, we investigated a new software scheme for scatter correction based on a simple radiographic scattering model where the intensity of the scattered x-rays was directly estimated from a single x-ray image using a weighted l¹-norm contextual regularization framework. We implemented the proposed algorithm and performed a systematic simulation and experiment to demonstrate its viability. We also conducted some clinical image studies using patient's image data of breast and L-spine to verify the clinical effectiveness of the proposed scheme. Our results indicate that the degradation of image characteristics by scattered x-rays and noise was effectively recovered by using the proposed software scheme, thus improving radiographic visibility considerably. Graphical abstract The schematic illustrations of scatter suppression methods by using a an antiscatter grid and b a scatter estimation algorithm.

Correction to: Acceptability of HIV self-sampling kits (TINY vial) among people of black African ethnicity in the UK: a qualitative study

It has been highlighted that in the original article [1] there is a typesetting mistake in the name of I. Fakoya. This was incorrectly captured as F. Fakoya. This correction article clarifies the correct name of the author.

The Efficacy of Platelet-Rich Plasma on Tendon and Ligament Healing: A Systematic Review and Meta-analysis With Bias Assessment

BACKGROUND

There has been a surge in high-level studies investigating platelet-rich plasma (PRP) for tendon and ligament injuries. A number of meta-analyses have been published, but few studies have focused exclusively on tendon and ligament injuries.

PURPOSE

To perform a meta-analysis assessing the ability of PRP to reduce pain in patients with tendon and ligament injuries.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A comprehensive search of the literature was carried out in April 2017 using electronic databases PubMed, MEDLINE, and the Cochrane Library. Only level 1 studies were included. Platelet and leukocyte count, injection volume, kit used, participant age/sex, comparator, and activating agent used were recorded. The short-term and long-term efficacy of PRP was assessed using the visual analog scale (VAS) to measure pain intensity. Injury subgroups (rotator cuff, tendinopathy, anterior cruciate ligament, and lateral epicondylitis) were evaluated. Funnel plots and the Egger test were used to screen for publication bias, and sensitivity analysis was performed to evaluate the effect of potential outliers by removing studies one at a time.

RESULTS

Thirty-seven articles were included in this review, 21 (1031 participants) of which could be included in the quantitative analysis. The majority of studies published investigated rotator cuff injuries (38.1%) or lateral epicondylitis (38.1%). Seventeen studies (844 participants) reported short-term VAS data, and 14 studies (771 participants) reported long-term VAS data. Overall, long-term follow-up results showed significantly less pain in the PRP group compared with the control group (weighted mean difference [WMD], -0.84; 95% CI, -1.23 to -0.44; P < .01). Patients treated with PRP for rotator cuff injuries (WMD, -0.53; 95% CI, -0.98 to -0.09; P = .02) and lateral epicondylitis (WMD, -1.39; 95% CI, -2.49 to -0.29; P = .01) reported significantly less pain in the long term. Substantial heterogeneity was reported at baseline ( I² = 72.0%; P < .01), short-term follow-up ( I² = 72.5%; P < .01), long-term follow-up ( I² = 76.1%; P < .01), and overall ( I² = 75.8%; P < .01). The funnel plot appeared to be asymmetric, with some missingness at the lower right portion of the plot suggesting possible publication bias.

CONCLUSION

This review shows that PRP may reduce pain associated with lateral epicondylitis and rotator cuff injuries.

MRI analysis of extra-capsular ganglia at the gastrocnemius origin and their association with osteoarthritis

AIM

To evaluate the prevalence, clinical relevance, and magnetic resonance imaging (MRI) features of extra-capsular ganglia at the gastrocnemius origin and to assess their association with internal derangement and osteoarthritis of the knee.

MATERIALS AND METHODS

One hundred consecutive knee MRI examinations, obtained within a 6-month period from patients with no history of recent knee trauma, recent injections, inflammatory arthritis, infection, or tumours, were evaluated retrospectively for the presence of ganglia at the gastrocnemius origin. The lesions were divided into two groups: an intra-capsular and an extra-capsular group. Cyst morphology (size, shape, and internal septa), internal derangement of the knee (cartilage lesion, cruciate ligament injury, meniscal tear, and corner injury on MRI, and osteoarthritis of the knee on radiographs) were evaluated. The chi-square, Fisher's exact, and t-tests were used to compare the two groups, in addition to multivariate stepwise logistic regression analysis.

RESULTS

Thirty-nine ganglia with an extra-capsular location were identified on 100 knee MRI (39 %). Rounded shape and internal septa were more common in the extra-capsular than in the intra-capsular group (p<0.001). Frequencies of high-grade cartilage, meniscal tear, and high-grade osteoarthritis significantly differed between the groups (p≤0.038). In multivariate analysis, the only significant association was between high-grade osteoarthritis and the extra-capsular group.

CONCLUSION

Extra-capsular ganglia at the gastrocnemius origin were not uncommon on knee MRI and had features typical of ganglia found at other sites. High-grade osteoarthritis was significantly associated with extra-capsular ganglia.

Polymerization-Induced Self-Assembly of Micelles Observed by Liquid Cell Transmission Electron Microscopy

In this paper, we describe the use of liquid cell transmission electron microscopy (LCTEM) for inducing and imaging the formation of spherical micelles from amphiphilic block copolymers. Within the irradiated region of the liquid cell, diblock copolymers were produced which self-assembled, yielding a targeted spherical micellar phase via polymerization-induced self-assembly (PISA). Critically, we demonstrate that nanoparticle formation can be visualized in situ and that in the presence of excess monomer, nanoparticle growth occurs to yield sizes and morphologies consistent with standard PISA conditions. Experiments were enabled by employing automated LCTEM sample preparation and by analyzing LCTEM data with multi-object tracking algorithms designed for the detection of low-contrast materials.

Development of a new analgesic index using nasal photoplethysmography

Although surrogate measures to quantify pain intensity have been commercialised, there is a need to develop a new index with improved accuracy. The aim of this study was to develop a new analgesic index using nasal photoplethysmography data. The specially designed sensor was placed between the columella and the nasal septum to acquire nasal photoplethysmography in surgical patients. Nasal photoplethysmography and Surgical Pleth Index^® (GE Healthcare) data were obtained for 14 min both in the absence (pre-operatively) or presence (postoperatively) of pain in a group of surgical patients, each patient acting as their own control. Various dynamic photoplethysmography variables were extracted to quantify pain intensity; the most accurate index was selected using logistic regression as a classifier. The area under the curve of the receiver-operating characteristic curve was measured to evaluate the accuracy of final model predictions. In total, 12,012 heart beats from 89 patients were used to develop a new Nasal Photoplethysmography Index for analgesic depth quantification. The two-variable model (a combination of diastolic peak point variation and heart beat interval variation) was most accurate in discriminating between the presence and absence of pain (numerical rating scale (NRS) ≥ 3). The accuracy and area under the curve of the receiver-operating characteristic curve for the Nasal Photoplethysmography Index were 75.3% and 0.8018, respectively, and 64.8% and 0.7034, respectively, for the Surgical Pleth Index. The Nasal Photoplethysmography Index clearly distinguished pain (NRS ≥ 3) in awake surgical patients with postoperative pain. The Nasal Photoplethysmography Index performed better than the Surgical Pleth Index. Further validation studies are needed to evaluate its feasibility to quantify pain intensity during general anaesthesia.