Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5–10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies

Noise Reduction in Photoacoustic Imaging using Wavelet Transform

Fotoakustik mikroskop (Photoacoustic Microscopy, PAM) fotoakustik etki temeline dayanan ve son yıllarda geliştirilmeye başlayan hibrid bir görüntüleme tekniğidir. Optik kontrastı akustik olarak algılayan sistem yapısı sayesinde optik difüzyon sınırının ötesinde derin bir görüntülemeyi yüksek çözünürlükle sunabilmektedir. PAM sistemi ile görüntülemede kaydedilen sinyaller, sistem bileşenleri ve çevresel etkilerle gürültüye maruz kalmaktadır. Yapılan çalışmanın ilk aşamasında akustik dalga denkleminin çözümüyle oluşturulan akustik sinyal üzerine belirli oranlarda sentetik gürültüler eklenmiştir. Gürültülü sinyallere farklı ana dalgacıklar kullanılarak ayrık dalgacık dönüşümü ile filtreleme işlemi uygulanmış ve filtreleme performansının değerlendirilmesi için sinyaller üzerinde gürültü metrikleri hesaplanmıştır. İkinci aşamada, ilk aşamada elde edilen veriler doğrultusunda PA sinyallerin filtrelenmesi için uygun ana dalgacıklar seçilmiş filtrelenen sinyaller ile görüntüler oluşturularak, görüntüler üzerinde gürültü metrikleri incelenmiştir // Photoacoustic microscopy (PAM) is a hybrid imaging technique based on the photoacoustic effect and which has begun to develop in recent years. Thanks to the system structure that senses the optical contrast acoustically, it is able to present deep imaging with high resolution beyond the optical diffusion limit. Signals recorded in imaging with the PAM system are exposed to noise by system components and environmental effectcs. In the first stage of the work, a synthetic noise is added at a certain rate on the acoustic signal generated by the solution of the acoustic wave equation. Noisy signals are filtered using discrete wavelet transforms using different main wavelets and noise metrics are calculated on the signals to evaluate the filtering performance. In the second step, the noise metrics are examined on the images by generating the images with the filtered wavelet signals, which are suitable for filtering the PA signals in the direction of the data obtained in the first stage

Diagnostic and prognostic role of TFF3, Romo-1, NF-кB and SFRP4 as biomarkers for endometrial and ovarian cancers: a prospective observational translational study

Purpose: This study aimed to evaluate trefoil factor 3 (TFF3), secreted frizzled-related protein 4 (sFRP4), reactive oxygen species modulator 1 (Romo1) and nuclear factor kappa B (NF-κB) as diagnostic and prognostic markers of endometrial cancer (EC) and ovarian cancer (OC). Methods: Thirty-one patients with EC and 30 patients with OC undergone surgical treatment were enrolled together with 30 healthy controls in a prospective study. Commercial ELISA kits determined serum TFF-3, Romo-1, NF-кB and sFRP-4 concentrations. Results: Serum TFF-3, Romo-1 and NF-кB levels were significantly higher in patients with EC and OC than those without cancer. Regarding EC, none of the serum biomarkers differs significantly between endometrial and non-endometrioid endometrial carcinomas. Mean serum TFF-3 and NF-кB levels were significantly higher in advanced stages. Increased serum levels of TFF-3 and NF-кB were found in those with a higher grade of the disease. Regarding OC, none of the serum biomarkers differed significantly among histological subtypes. Significantly increased serum levels of NF-кB were observed in patients with advanced-stage OC than those with stage I and II diseases. No difference in serum biomarker levels was found between those who had a recurrence and those who had not. The sensibility and specificity of these four biomarkers in discriminating EC and OC from the control group showed encouraging values, although no one reached 70%. Conclusions: TFF-3, Romo-1, NF-кB and SFRP4 could represent new diagnostic and prognostic markers for OC and EC. Further studies are needed to validate our results

Border Terriers under primary veterinary care in England: demography and disorders

The Border Terrier is a working terrier type that is generally considered to be a relatively healthy and hardy breed. This study aimed to characterise the demography and common disorders of Border Terriers receiving veterinary care in England using de-identified electronic patient record data within the VetCompass™ Programme

Potential risk and safety measures in laparoscopy in COVID-19 positive patients

Background. During the COVID-19 pandemic the question arises if laparoscopy, as an aerosol forming procedure, poses a potential risk for viral transmission of SARS-CoV-2 to healthcare workers. Methods. A literature search was conducted using PubMed, Embase and MEDLINE. Articles reporting information regarding COVID-19 or other relevant viruses and laparoscopy, surgical smoke, aerosols and viral transmission were included. Results. Although aerosols produced during laparoscopy do not originate from the respiratory tract, the main transmission route of SARS-CoV-2, research did show SARS-CoV-2 to be present in other body fluids. The transmission risk via this route is however considered very low. As previous research showed potential viral transmission during laparoscopy for viruses that spread through contaminated body fluids, there might be a potential risk of SARS-CoV-2 transmission during laparoscopy, albeit considered very small. Conclusion. Due to the small risk compared to widely known benefits of laparoscopy, there is no reason to replace laparoscopy by laparotomy due to COVID-19 infection. To avoid the potential small risk of viral transmission, additional safety measures are advised.Gynecolog

Preoperative weight gain is not related to lower postoperative weight loss but to lower total weight loss up to 3 years after bariatric-metabolic surgery

Introduction: Weight loss prior to bariatric-metabolic surgery (BMS) is recommended in most bariatric centers. However, there is limited high-quality evidence to support mandatory preoperative weight loss. In this study, we will evaluate whether weight gain prior to primary BMS is related to lower postoperative weight loss.Methods: A retrospective analysis of prospectively collected data was performed. Preoperative weight loss (weight loss from start of program to day of surgery), postoperative weight loss (weight loss from day of surgery to follow-up), and total weight loss (weight loss from start of program to follow-up) were calculated. Five groups were defined based on patients' preoperative weight change: preoperative weight loss of >5 kg (group I), 3-5 kg (group II), 1-3 kg (group III), preoperative stable weight (group IV), and preoperative weight gain >1 kg (group V). Linear mixed models were used to compare the postoperative weight loss between group V and the other four groups (I-IV).Results: A total of 1928 patients were included. Mean age was 44 years, 78.6% were female, and preoperative BMI was 43.7 kg/m2. Analysis showed significantly higher postoperative weight loss in group V, compared to all other groups at 12, 24, and 36 months follow-up. Up to three years follow-up, highest total weight loss was observed in group I.Conclusion: Weight gain before surgery should not be a reason to withhold a bariatric-metabolic operation. However, patients with higher preoperative weight loss have higher total weight loss. Therefore, preoperative weight loss should be encouraged prior to bariatric surgery.</p

Optical resolution photoacoustic imaging of multiple probes via single fiber laser with independently adjustable parameters

[No abstract available

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy

Photoacoustic imaging is based on the detection of generated acoustic waves through thermal expansion of tissue illuminated by short laser pulses. Fiber lasers as an excitation source for photoacoustic imaging have recently been preferred for their high repetition frequencies. Here, we report a unique fiber laser developed specifically for multiwavelength photoacoustic microscopy system. The laser is custom-made for maximum flexibility in adjustment of its parameters; pulse duration (5-10 ns), pulse energy (up to 10 μJ) and repetition frequency (up to 1 MHz) independently from each other and covers a broad spectral region from 450 to 1100 nm and also can emit wavelengths of 532, 355, and 266 nm. The laser system consists of a master oscillator power amplifier, seeding two stages; supercontinuum and harmonic generation units. The laser is outstanding since the oscillator, amplifier and supercontinuum generation parts are all-fiber integrated with custom-developed electronics and software. To demonstrate the feasibility of the system, the images of several elements of standardized resolution test chart are acquired at multiple wavelengths. The lateral resolution of optical resolution photoacoustic microscopy system is determined as 2.68 μm. The developed system may pave the way for spectroscopic photoacoustic microscopy applications via widely tunable fiber laser technologies. © The Author(s) 2016