Prevalence of significant pathology on MRI of brain and orbits in patients presenting with visual disturbance.

PURPOSE: The aim of our study was to determine the frequency and variety of abnormalities detected on MRI studies of the brain and orbits (MRBO), in patients referred for investigation of visual disturbance from a tertiary ophthalmology centre in Ireland. A secondary objective was to assess the various imaging pathologies identified in this cohort of patients. METHODS: The inclusion criteria were patients who underwent an Magnetic resonance imaging (MRI) brain or MRI brain and orbits over a 12-month period for investigation of first episode of visual disturbance, who were over 18 years of age, with visual disturbance of unknown aetiology. Statistical analysis was performed to calculate the percentage of abnormalities and corresponding 95% confidence interval (CI). Additionally, logistic regression was used to investigate any association between age, gender and the pathologies which presented. RESULTS: 135 MRI brain and orbit examinations fulfilled the inclusion criteria. Abnormalities were identified on 86 of the 135 examinations (63.7%; 95% CI: 55.3% to 71.3%). Nonspecific T2 hyperintensities were identified on 28 (20.7%) of the examinations, 13 (9.6%) examinations showed images suggestive of demyelination and 11 (8.1%) showed optic neuropathy. The logistic regression analysis showed no evidence of an association between age (p = 0.223), gender (p = 0.307) and abnormalities in this study. CONCLUSION: This represents a relatively high detection rate of abnormalities on MRBO when compared with similar studies and shows the important role MRI has in patients with a visual disturbance.

Preoperative CT in patients with surgically resectable pancreatic adenocarcinoma: does the time interval between CT and surgery affect survival?

PURPOSE: The preoperative imaging-to-surgery time interval (ISI) influences the risk of unexpected progression (UP) found at surgery for pancreatic adenocarcinoma. We aimed to assess whether ISI influences disease recurrence and/or survival. METHODS AND MATERIALS: A single-institution, ethics board-approved retrospective analysis of all patients who underwent attempted resection of pancreatic (PDAC) or periampullary adenocarcinoma (AmpAC) between 1st January 2010 and 31st December 2015 was performed. All patients underwent preoperative abdominal computed tomography (CT). Exclusion criteria were borderline resectable disease and neoadjuvant chemo/radiotherapy. Patients were followed up until 30th June 2016. The population was divided into ISI ≥/<25 days. Kaplan-Meier and Cox regression survival analyses were performed. RESULTS: 239 patients underwent surgical exploration. UP was found in 29 (12.1%) and these patients had longer ISI (median 46 vs. 29 days, p < 0.05). When intention-to-treat analysis was performed, there was no difference in overall survival (OS) between patients with ISI ≥/<25. In those who underwent resection, ISI did not influence disease-free survival (DFS) or OS for PDAC (n = 174). For AmpAC (n = 36), ISI ≥ 25 days was associated with longer OS (p < 0.05) but did not influence DFS. Longer ISI was independently associated with improved OS on regression analysis for AmpAC. CONCLUSION: Performing surgery for resectable pancreatic adenocarcinoma within 25 days of abdominal CT reduces the chance of UP but does not confer a survival benefit. For those who undergo resection of AmpAC, a longer ISI was associated with longer OS. This probably represents a more biologically indolent disease in this cohort.

Nanosecond colloidal quantum dot lasers for sensing.

Low-threshold, gain switched colloidal quantum dot (CQD) distributed-feedback lasers operating in the nanosecond regime are reported and proposed for sensing applications for the first time to the authors' knowledge. The lasers are based on a mechanically-flexible polymeric, second order grating structure overcoated with a thin-film of CQD/PMMA composite. The threshold fluence of the resulting lasers is as low as 0.5 mJ/cm² for a 610 nm emission and the typical linewidth is below 0.3 nm. The emission wavelength of the lasers can be set at the design stage and laser operation between 605 nm and 616 nm, while using the exact same CQD gain material, is shown. In addition, the potential of such CQD lasers for refractive index sensing in solution is demonstrated by immersion in water.

Distributed feedback laser for biosensing applications.

We present an organic semiconductor distributed feedback laser biosensor and demonstrate its sensing capabilities. Optimization of the gain layer thickness to maximize the response to refractive index changes and bulk sensing results are shown. Desthiobiotin-avidin sensing assay results are also presented and the potential to perform multiple, repeated sensing measurements is demonstrated.