Influence of vitamins and food on the fluorescence spectrum of human urine

OBJECTIVES

Fluorescence spectroscopy of human urine is a method with the potential to gain importance as a diagnostic tool in the medical field, e.g., for measuring Coproporphyrin III (CPIII) as an indicator of cancer and acute types of porphyria. Food can change human urine's color, which could influence the urine fluorescence spectrum and the detection of CPIII in urine. To determine if there is a noticeable influence on the urine fluorescence spectrum or on the detection of CPIII in urine, 16 vitamin supplements, and three food items were tested. Such investigation may also prevent false interpretation of measured data.

METHODS

Urine samples were collected before and after (overnight, ca. 8 h) intake of each test substance. Samples were investigated by fluorescence spectrum analysis. At excitation wavelengths from 300 to 500 nm and emission wavelengths from 400 to 700 nm excitation-emission-matrices were measured. Data obtained from urine before intake were compared to the data from overnight urine. Furthermore, the investigation of any interference with the CPIII concentration was performed at an excitation wavelength of 407 ± 3 nm and emission wavelengths of 490-800 nm.

RESULTS

Only vitamin B2, but none of the other tested substances, showed noticeable influence on the urine fluorescence spectrum. None of the tested substances showed noticeable interference with the recovery rate of CPIII.

CONCLUSIONS

The correct interpretation of measured data by fluorescence spectroscopy is possible with the exception if vitamin B2 supplementation was performed; thus, the consumption of vitamin B2 supplements before fluorescence testing of the patient's urine should be avoided and/or must be requested. CPIII concentrations could reliably be measured in all cases.

Hyperspectral imaging for monitoring of free flaps of the oral cavity: A feasibility study

OBJECTIVES

Hyperspectral imaging (HSI) provides spectral information about hemoglobin, water and oxygen supply and has thus great potential in perfusion monitoring. The aim of the present study was to investigate the feasibility of HSI in the postoperative monitoring of intraoral free flaps.

METHODS

The 14 patients receiving reconstructive head and neck surgery with a radial forearm free flap were included. HSI was performed intraoperatively (t0), on Day 1 (t1), 2 (t2), 3-6 (t3), 7-9 (t4), 10-11 (t5) and 12-15 (t6) postoperatively. Flap tissue perfusion was assessed on defined regions of interest by calculating the perfusion indices Tissue Hemoglobin Index (THI), hemoglobin oxygenation (StO2 ), Near Infrared Perfusion Index (NIR Perfusion Index) and Tissue Water Index (TWI).

RESULTS

Image quality varied depending on location of the flap and time of measurement. StO2 was >50 intraoperatively and >40 on t1 for all patients. A significant difference was found solely for TWI between t0 and t2 and t0 and t4. No flap loss occurred.

CONCLUSIONS

The use of HSI in the monitoring of intraoral flaps is feasible and might become a valuable addition to the current clinical examination of free flaps.

Investigations on correlations between changes of optical tissue properties and NMR relaxation times

BACKGROUND

Accurate light dosimetry is a complex remaining challenge in interstitial photodynamic therapy (iPDT) for malignant gliomas. The light dosimetry should ideally be based on the tissue morphology and the individual optical tissue properties of each tissue type in the target region. First investigations are reported on using NMR information to estimate changes of individual optical tissue properties.

METHODS

Porcine brain tissue and optical tissue phantoms were investigated. To the porcine brain, supplements were added to simulate an edema or high blood content. The tissue phantoms were based on agar, Lipoveneous, ink, blood and gadobutrol (Gd-based MRI contrast agent). The concentrations of phantom ingredients and tissue additives are varied to compare concentration-dependent effects on optical and NMR properties. A 3-tesla whole-body MRI system was used to determine T1 and T2 relaxation times. Optical tissue properties, i.e., the spectrally resolved absorption and reduced scattering coefficient, were obtained using a single integrating sphere setup. The observed changes of NMR and optical properties were compared to each other.

RESULTS

By adjusting the NMR relaxation times and optical tissue properties of the tissue phantoms to literature values, recipes for human brain tumor, white matter and grey matter tissue phantoms were obtained that mimic these brain tissues simultaneously in both properties. For porcine brain tissue, it was observed that with increasing water concentration in the tissue, both NMR-relaxation times increased, while µa decreased and µs' increased at 635 nm. The addition of blood to porcine brain samples showed a constant T1, while T2 shortened and the absorption coefficient at 635 nm increased.

CONCLUSIONS

In this investigation, by changing sample contents, notable changes of both NMR relaxation times and optical tissue properties have been observed and their relations examined. The developed dual NMR/optical tissue phantoms can be used in iPDT research, clinical training and demonstrations.

Standard operating procedure to reveal prostate cancer specific volatile organic molecules by infrared spectroscopy

The growing number of prostate cancer cases is a real concern in modern society. Over 1.4 million new cases and about 400 thousand (>26%) deaths were registered worldwide in 2020 due to prostate cancer. The high mortality rate of prostate cancer is due to the lack of reliable early detection of the disease. Till now the most reliable diagnosis of cancer is tissue biopsy, which is an invasive process. A non-invasive or minimally invasive technique could lead to a diagnostic tool that will allow for saving or prolonging the lifespan of millions of lives. Metabolite-based diagnostics may have a better chance of early cancer detection. However, reliable detection techniques need to be developed. Infrared spectroscopy based gaseous-biofluid holds great promise towards the development of non-invasive diagnostics. A pilot study based on breath analysis by infrared spectroscopy showed promising results in distinguishing prostate cancer patients from healthy volunteers. Details of the spectral metabolic analysis are presented.

Non-Invasive Zinc Protoporphyrin Screening Offers Opportunities for Secondary Prevention of Iron Deficiency in Blood Donors

Background

Frequent blood donors are at high risk of developing iron deficiency. Currently, there is no potent screening during blood donation to detect iron deficient erythropoiesis (IDE) before anemia develops and deferral from donation is inevitable.

Study Design and Methods

In addition to capillary and venous hemoglobin, the iron status of 99 frequent blood donors was assessed by various venous blood parameters and zinc protoporphyrin IX (ZnPP). ZnPP was determined by high-performance liquid chromatography (HPLC) and a new prototype fiber-optic device was employed for non-invasive measurements of ZnPP through the blood collection tubing (NI-tubing) and on lip tissue (NI-lip). We aimed to evaluate the feasibility and diagnostic value of the NI-tubing measurement for early detection of severe iron deficiency in blood donors.

Results

NI-tubing and HPLC reference measurements of ZnPP showed narrow limits of agreement of 12.2 μmol ZnPP/mol heme and very high correlation (Spearman's Rho = 0.938). Using a cutoff of 65 μmol ZnPP/mol heme, NI-tubing measurements (n = 93) identified 100% of donors with iron deficiency anemia (IDA) and an additional 38% of donors with IDE. Accordingly, NI-tubing measurements would allow detection and selective protection of particularly vulnerable donors.

Conclusion

NI-tubing measurements are an accurate and simple method to implement ZnPP determination into the routine blood donation process. ZnPP was able to identify the majority of subjects with IDE and IDA and might therefore be a valuable tool to provide qualified information to donors about dietary measures and adjustments of the donation interval and thereby help to prevent IDA and hemoglobin deferral in the future.

Prospects of Endovenous Laser Ablation (EVLA) Standardization-Mid-Term Results of a Four-Zone Dosimetry Guiding Tool for 1940 nm Laser

BACKGROUND

Heterogeneity regarding dosimetry and reporting of endovenous laser ablation (EVLA) mandates the development of a standardized protocol. This study presents the mid-term results of EVLA with 1940 nm-laser and radial-fibre, supported by a four-zone dosimetry tool.

MATERIALS AND METHODS

Four anatomical dosimetry zones for great saphenous veins (GSV) and two for small saphenous veins (SSV) were defined with set power levels. Zone-1G (4 W) extended from the inguinal ligament to the apex of femoral triangle, Zone-2G (4 W) from the apex of femoral triangle to the upper border of patella. Zone-3G (3 W) from the patella to the tibial tuberosity. Zone-4G (2 W) extended from the tibial tuberosity to the ankle. Zone-1S from the sapheno-popliteal junction to the tibial tuberosity. Zone-2S from the tibial tuberosity to the ankle. Power was increased by 1 W for veins >10 mm and decreased by 1 W when fibre sticking was encountered. Pullback-velocity was max. 1 mm/s.

RESULTS

A total of 152 consecutive patients (185 procedures) were recruited. Mean follow-up time was 11.9 months. Mean linear endovenous energy density for GSV was Zone-1G:42 J/cm, Zone-2G:33 J/cm, Zone-3G:27 J/cm, Zone-4G:22 J/cm, Zone-1S:34 J/cm, Zone-2S:27 J/cm. Occlusion rates were 98.9% (1-month) and 93.7% (12-months). Complications at 1 M were low, namely laser-induced paraesthesia (LIP) 2.2% and endovenous heat-induced thrombosis (EHIT) 1.6%. Persistent LIP (12 M) was observed in 0.5%.

CONCLUSION

The proposed four-zone guiding tool is a step towards standardizing dosimetry and documentation for EVLA with 1940 nm. This strategy shows good mid-term results with minimal complications. Long-term follow-up and application in further centres are necessary to prove its reproducibility. Such a guiding tool could improve the ability to analyse, compare and review different EVLA wavelengths and fibre types.

Interstitial Photodynamic Therapy of Glioblastomas: A Long-Term Follow-up Analysis of Survival and Volumetric MRI Data

BACKGROUND

The treatment of glioblastomas, the most common primary malignant brain tumors, with a devastating survival perspective, remains a major challenge in medicine. Among the recently explored therapeutic approaches, 5-aminolevulinic acid (5-ALA)-mediated interstitial photodynamic therapy (iPDT) has shown promising results.

METHODS

A total of 16 patients suffering from de novo glioblastomas and undergoing iPDT as their primary treatment were retrospectively analyzed regarding survival and the characteristic tissue regions discernible in the MRI data before treatment and during follow-up. These regions were segmented at different stages and were analyzed, especially regarding their relation to survival.

RESULTS

In comparison to the reference cohorts treated with other therapies, the iPDT cohort showed a significantly prolonged progression-free survival (PFS) and overall survival (OS). A total of 10 of 16 patients experienced prolonged OS (≥ 24 months). The dominant prognosis-affecting factor was the MGMT promoter methylation status (methylated: median PFS of 35.7 months and median OS of 43.9 months) (unmethylated: median PFS of 8.3 months and median OS of 15.0 months) (combined: median PFS of 16.4 months and median OS of 28.0 months). Several parameters with a known prognostic relevance to survival after standard treatment were not found to be relevant to this iPDT cohort, such as the necrosis-tumor ratio, tumor volume, and posttreatment contrast enhancement. After iPDT, a characteristic structure (iPDT remnant) appeared in the MRI data in the former tumor area.

CONCLUSIONS

In this study, iPDT showed its potential as a treatment option for glioblastomas, with a large fraction of patients having prolonged OS. Parameters of prognostic relevance could be derived from the patient characteristics and MRI data, but they may partially need to be interpreted differently compared to the standard of care.

Interstitial photodynamic therapy for newly diagnosed glioblastoma

PURPOSE

Innovative, efficient treatments are desperately needed for people with glioblastoma (GBM).

METHODS

Sixteen patients (median age 65.8 years) with newly diagnosed, small-sized, not safely resectable supratentorial GBM underwent interstitial photodynamic therapy (iPDT) as upfront eradicating local therapy followed by standard chemoradiation. 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX was used as the photosensitizer. The tumors were irradiated with light at 635 nm wavelength via stereotactically implanted cylindrical diffuser fibers. Outcome after iPDT was retrospectively compared with a positively-selected in-house patient cohort (n = 110) who underwent complete tumor resection followed by chemoradiation.

RESULTS

Median progression-free survival (PFS) was 16.4 months, and median overall survival (OS) was 28.0 months. Seven patients (43.8%) experienced long-term PFS > 24 months. Median follow-up was 113.9 months for the survivors. Univariate regression revealed MGMT-promoter methylation but not age as a prognostic factor for both OS (p = 0.04 and p = 0.07) and PFS (p = 0.04 and p = 0.67). Permanent iPDT-associated morbidity was seen in one iPDT patient (6.3%). Patients treated with iPDT experienced superior PFS and OS compared to patients who underwent complete tumor removal (p < 0.01 and p = 0.01, respectively). The rate of long-term PFS was higher in iPDT-treated patients (43.8% vs. 8.9%, p < 0.01).

CONCLUSION

iPDT is a feasible treatment concept and might be associated with long-term PFS in a subgroup of GBM patients, potentially via induction of so far unknown immunological tumor-controlling processes.

Development of a microstructured tissue phantom with adaptable optical properties for use with microscopes and fluorescence lifetime imaging systems

OBJECTIVES

For the development and validation of diagnostic procedures based on microscopic methods, knowledge about the imaging depth and achievable resolution in tissue is crucial. This poses the challenge to develop a microscopic artificial phantom focused on the microscopic instead of the macroscopic optical tissue characteristics.

METHODS

As existing artificial tissue phantoms designed for image forming systems are primarily targeted at wide field applications, they are unsuited for reaching the formulated objective. Therefore, a microscopy- and microendoscopy-suited artificial tissue phantom was developed and characterized. It is based on a microstructured glass surface coated with fluorescent beads at known depths covered by a scattering agent with modifiable optical properties. The phantom was examined with different kinds of microscopy systems in order to characterize its quality and stability and to demonstrate its usefulness for instrument comparison, for example, regarding structural as well as fluorescence lifetime analysis.

RESULTS

The analysis of the manufactured microstructured glass surfaces showed high regularity in their physical dimensions in accordance with the specifications. Measurements of the optical parameters of the scattering medium were consistent with simulations. The fluorescent beads coating proved to be stable for a respectable period of time (about a week). The developed artificial tissue phantom was successfully used to detect differences in image quality between a research microscope and an endoscopy based system. Plausible causes for the observed differences could be derived based on the well known microstructure of the phantom.

CONCLUSIONS

The artificial tissue phantom is well suited for the intended use with microscopic and microendoscopic systems. Due to its configurable design, it can be adapted to a wide range of applications. It is especially targeted at the characterization and calibration of clinical imaging systems that often lack extensive positioning capabilities such as an intrinsic z-stage.

The role of shikonin in improving 5-aminolevulinic acid-based photodynamic therapy and chemotherapy on glioblastoma stem cells

Glioblastoma multiforme remains a malignant neoplasia with a median survival of less than two years and without satisfactory therapeutic options. The so-called glioblastoma stem cells escape the established radio- and chemotherapies and lead to tumor recurrence in most cases. The alkaloid Shikonin with its various anti stem cell properties and the interstitial photodynamic therapy with 5-aminolevulinic acid seem to be promising new options in the therapy of glioblastoma. In this study, in vitro investigations were performed to observe the influence of Shikonin on viability, proliferation, induction of apoptosis and the capability of forming tumor spheres in U-87 MG and the primary glioblastoma cell line GB14. The combined effect with the chemotherapeutic temozolomide and photodynamic treatment on the mRNA expression of glioma specific stem cell markers and further examined intracellular protoporphyrin IX accumulation under Shikonin treatment was analyzed. Shikonin effectively inhibited the capability of forming tumor spheres and enhanced temozolomide effectiveness in the reduction of proliferation and in the induction of apoptosis. Additionally, Shikonin increased the mRNA expression of the tumor suppressing Neurofibromatosis type 1 (NF1) gene and showed modulating effects on intracellular protoporphyrin IX.

Clinical Evaluation of Single-Use, Fiber-Optic, and Digital Ureterorenoscopes in the Treatment of Kidney Stones

<b><i>Introduction:</i></b> Indication of ureteroscopy for the treatment of urolithiasis has expanded immensely over the last decade. Fiber-optic and digital reusable instruments present the standard in clinical practice, but various newly available single-use devices might offer an exciting alternative. To date, the evidence is limited to clinical evaluation and efficacy of single-use ureteroscopes (URS) compared to standard instruments. Therefore, we evaluate a single-use instrument’s clinical characteristics and efficacy in direct comparison with a fiber-optic and digital device. <b><i>Methods:</i></b> A prospective study was conducted for patients undergoing endoscopic therapy for urolithiasis at a tertiary care center. We evaluated the different instruments’ clinical performance in categories of visibility, the stability of visibility, irrigation flow, and surgeon’s satisfaction. Statistical analyses were performed by SPSS using the Chi-Quadrat and Kruskal-Wallis test. A <i>p</i> value of <i>p</i> ≤ 0.05 was defined as statistically significant. <b><i>Results:</i></b> A total number of 77 patients were included and distributed as follows: 35 (46.7%) single-use, 19 (25.3%) digital, and 23 (28%) fiber-optic URS. Patients’ characteristics were homogenous over the three cohorts in sex, stone amount, and localization. The stone-free rate was equal in all three cohorts (<i>p</i> = 0.31). We identify stability of visibility, irrigation flow, and satisfaction were equal in all cohorts (<i>p</i> = 0.73; <i>p</i> = 0.20; <i>p</i> = 0.20). We report a significant difference in visibility, with 100% rated excellent in the digital URS group (<i>p</i> = 0.028). <b><i>Discussion/Conclusions:</i></b> Single-use URS achieve comparable clinical outcomes with equal stone-free rates in direct comparison with fiber-optic and digital reusable instruments. Accordingly, single-use devices present an adequate alternative for endoscopic therapy of urolithiasis.

Safety and efficacy of endovenous laser ablation (EVLA) using 1940 nm and radial emitting fiber: 3-year results of a prospective, non-randomized study and comparison with 1470 nm

OBJECTIVES

To evaluate the safety, efficacy and ≥36 months outcomes of endovenous laser ablation (EVLA) by means of 1940 nm laser with radial fiber for the treatment of truncal vein insufficiency and compare the results to a historical cohort, obtained via reviewing the literature.

METHODS

This prospective, non-randomized, single-center clinical study included 139 consecutive patients with 177 incompetent great saphenous (GSV, n = 135) and short saphenous veins (SSV, n = 42). The maximum laser power (Pmax. 10 W) and pullback velocity were adjusted individually (V_max  = 1 mm/s). The laser fiber was placed at the junction to the deep vein under duplex monitoring. Simultaneous phlebectomies were performed on all the patients. Regular follow up with clinical and duplex ultrasound examination (DUS) were carried out postoperatively at 1 month (1 M), 6 months (6 M), 12 months (12 M), 24 months (24 M), 36 months, and after that (≥36 M). The results were compared with three cohorts (total 616 EVLA procedures with 1470 nm laser and radial fiber) from literature (criteria: >100 procedures, follow-up of ≥2 years).

RESULTS

The follow-up rate was 100%, 91%, 73%, 48%, and 23% of the truncal veins at 1, 6, 12, 24, and ≥36 M, respectively. In comparison to the literature using 1470, a lower average linear endovenous energy density (LEED) (53 vs. 77-82 J/cm) resulted in 100% (6 M) and 96.5% (24 M) occlusion rates, reduced local ecchymosis (2.2% vs. 3.2%-18.7%) and reduced average postoperative pain levels (1.3 vs. 2.18). Regarding adverse events, induration (1.1% vs. 1.8%), skin burns (0% vs. 0.45%), endovenous heat-induced thrombus propagation (EHIT) in the deep veins (2.3% vs. 1.8%) and laser-induced persistent paresthesia (2.2% vs. 0.5%-2.9%) were comparable. Recanalizations observed in this study (GSV 0, SSV 3) were asymptomatic and required no treatment. At ≥36 M reflux in the accessory veins was observed in 5% versus 10.5% of patients. Reintervention was required in none (0% vs. 21%). At >36 M, short average stump lengths of 1 cm (GSV) and 0.3 cm (SSV) were observed.

CONCLUSION

EVLA with 1940 nm laser with radial emitting fiber is as safe and effective as 1470 nm laser for the treatment of truncal vein insufficiency. Lower postoperative pain, low analgesic requirements, short convalescence add to patients' comfort. EVLA with 1940 nm laser-guided by intraoperative DUS permits reproducible placement of the radial fiber at the saphenofemoral and saphenopopliteal junction, enabling further studies to assess the effect of shorter stump length on patterns and frequency of recurrence without increased risk of EHIT.

Evaluation of hyperspectral imaging to quantify perfusion changes during the modified Allen test

OBJECTIVES

To evaluate the capability of hyperspectral imaging (HSI), a contact-less and noninvasive technology, to monitor perfusion changes of the hand during a modified Allen test (MAT) and cuff occlusion test. Furthermore, the study aimed at obtaining objective perfusion parameters of the hand.

METHODS

HSI of the hand was performed on 20 healthy volunteers with a commercially available HSI system during a MAT and a cuff occlusion test. Besides gathering red-green-blue (RGB) images, the perfusion parameters tissue hemoglobin index (THI), (superficial tissue) hemoglobin oxygenation (StO2), near-infrared perfusion (NIR), and tissue water index (TWI) were calculated for four different regions of interest on the hand. For the MAT, occlusion (OI; the ratio between the condition during occlusion and before occlusion) and reperfusion (RI; the ratio between the non-occlusion state and the prior occlusion state) indices were calculated for each perfusion parameter. All data were correlated to the clinical findings.

RESULTS

False-color images showed visible differences between the various perfusion conditions during the MAT and cuff occlusion test. THI, StO2, and NIR behaved as expected from physiology, while TWI did not in the context of this study. During rest, mean THI, StO2, and NIR of the hand were 34 ± 2, 72 ± 9, and 61 ± 6, respectively. The RI for THI showed a roundabout threefold increase after reperfusion of both radial and ulnar artery and was thus, distinctly pronounced when compared with StO2 and NIR (~1.25). The OI was lowest for THI when compared with StO2 and NIR.

CONCLUSIONS

HSI with its parameters THI, StO2, and NIR proved to be suitable to evaluate perfusion of the hand. By this, it could complement visual inspection during the MAT for evaluating the functionality of the superficial palmary arch before radial or ulnar artery harvest. The presented RI might deliver useful comparative values to detect pathological perfusion disorders at an early stage. As microcirculation monitoring is crucial for many medical issues, HSI shows potential to be used, besides further applications, in the monitoring of (free) flaps and transplants and microcirculation monitoring of critically ill patients.

Towards reliable diagnostics of prostate cancer via breath

Early detection of cancer is a key ingredient for saving many lives. Unfortunately, cancers of the urogenital system are difficult to detect at early stage. The existing noninvasive diagnostics of prostate cancer (PCa) suffer from low accuracy (< 70%) even at advanced stages. In an attempt to improve the accuracy, a small breath study of 63 volunteers representing three groups: (1) of 19 healthy, (2) 28 with PCa, (3) with 8 kidney cancer (KC) and 8 bladder cancer (BC) was performed. Ultrabroadband mid-infrared Fourier absorption spectroscopy revealed eight spectral ranges (SRs) that differentiate the groups. The resulting accuracies of supervised analyses exceeded 95% for four SRs in distinguishing (1) vs (2), three for (1) vs (3) and four SRs for (1) vs (2) + (3). The SRs were then attributed to volatile metabolites. Their origin and involvement in urogenital carcinogenesis are discussed.

Quenched coumarin derivatives as fluorescence lifetime phantoms for NADH and FAD

Two-photon fluorescence lifetime imaging is a versatile laboratory technique in the field of biophotonics and its importance is also growing in the field of in vivo diagnostics for medical purposes. After years of experience in dermatology, endoscopic implementations of the technique are now posing new technical challenges. To develop, test, and compare instrumental solutions for this purpose suitable reference samples have been devised and tested. These reference samples can serve as reliable NADH- and FAD-mimicking optical phantoms for 2-photon fluorescence lifetime imaging, as they can be prepared relatively easily with reproducible and stable characteristics for this quite relevant diagnostic technique. The reference samples (mixtures of coumarin 1 and coumarin 6 in ethanol with suitable amounts of 4-hydroxy-TEMPO) have been tuned to exhibit spectral and temporal fluorescence characteristics very similar to those of NADH and FAD, the two molecules most frequently utilized to characterize cell metabolism.

Single center retrospective analysis of fifty-two prostate cancer patients with customized MR-guided transurethral ultrasound ablation (TULSA)

OBJECTIVES

MR-guided transurethral ultrasound ablation (TULSA) has primarily been investigated for whole-gland prostate ablation, even though the technology is also well-suited for partial gland treatment. The objectives were to perform a clinical service evaluation of partial to whole-gland TULSA for patients with localized prostate cancer (CaP). TULSA was also evaluated as a combined therapy for a subset of patients presenting with both cancer and concurrent benign prostate hyperplasia (BPH).

SUBJECTS AND METHODS

This retrospective, consecutive clinical service evaluation included men with histopathologically-confirmed CaP who underwent TULSA either as primary or salvage treatment. The planned ablation was dependent on the individual tumor characteristics, concurrent BPH and patient preferences. The Clavien-Dindo classification was used to record complications. Surgeon-assessed functional outcomes were reported. Early treatment success was defined by negative multiparametric MRI (mpMRI) and lack of prostate specific antigen (PSA) recurrence.

RESULTS

Fifty-two consecutive patients (47 treatment-naïve and 5 salvage) were included, with median follow-up of sixteen months and a max of thirty-six months. Baseline median (IQR) age and PSA were 67 years (63-76) and 8.0 ng/ml (5.2-13), respectively. Two Grade IIIa adverse events were observed, with no bowel-related complications. For urinary continence outcomes, 1 patient worsened to 1 pad per day. All patients who were previously potent maintained erectile potency. Of the patient subgroup also seeking treatment for BPH, 83% reported symptom improvement. Median (IQR) PSA nadir after primary treatment was 1.1 ng/ml (0.5-2.1). Early treatment success was 88%. Nine patients underwent a single repeat TULSA.

CONCLUSION

Customized prostate ablation with TULSA offers flexible ablation according to patients' disease characteristics and treatment expectations, providing favorable safety and promising early MRI and PSA results. TULSA is a feasible combination therapy for patients with both cancer and concurrent BPH.

Bioenergetic Alterations of Metabolic Redox Coenzymes as NADH, FAD and FMN by Means of Fluorescence Lifetime Imaging Techniques

Metabolic FLIM (fluorescence lifetime imaging) is used to image bioenergetic status in cells and tissue. Whereas an attribution of the fluorescence lifetime of coenzymes as an indicator for cell metabolism is mainly accepted, it is debated whether this is valid for the redox state of cells. In this regard, an innovative algorithm using the lifetime characteristics of nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD) to calculate the fluorescence lifetime induced redox ratio (FLIRR) has been reported so far. We extended the FLIRR approach and present new results, which includes FLIM data of the various enzymes, such as NAD(P)H, FAD, as well as flavin mononucleotide (FMN). Our algorithm uses a two-exponential fitting procedure for the NAD(P)H autofluorescence and a three-exponential fit of the flavin signal. By extending the FLIRR approach, we introduced FLIRR1 as protein-bound NAD(P)H related to protein-bound FAD, FLIRR2 as protein-bound NAD(P)H related to free (unbound) FAD and FLIRR3 as protein-bound NAD(P)H related to protein-bound FMN. We compared the significance of extended FLIRR to the metabolic index, defined as the ratio of protein-bound NAD(P)H to free NAD(P)H. The statistically significant difference for tumor and normal cells was found to be highest for FLIRR1.

Spectrophotometric evaluation of hemolysis in plasma by quantification of free oxyhemoglobin, methemoglobin, and methemalbumin in presence of bilirubin

Severe intravascular hemolysis leads to the simultaneous presence of free heme pigments (oxyhemoglobin, methemoglobin, and methemalbumin) and bilirubin in human plasma. Standard spectrophotometric methods used to assess in vivo hemolysis inadequately address this complex analytical situation. Thus, we propose a novel quantification algorithm to ensure the highest analytical specificity. A corresponding second-derivative fitting algorithm was validated according to the guideline of bioanalytical method validation from the European Medicines Agency using plasma specimens (n = 1759) spiked with different concentrations of oxyhemoglobin and methemoglobin. The results were compared to standard spectrophotometric quantification methods described by Harboe, Noe, and Fairbanks. Based on the second-derivative method, simultaneous quantification of oxyhemoglobin and methemoglobin/methemalbumin in samples with total bilirubin concentrations ≤4.9 mg/dL (83.8 μmol/L) provided robust results (inaccuracy ≤20%, imprecision ≤16%). Analyzing UV/VIS spectra of plasma from patients with confirmed severe intravascular hemolysis evidenced an underestimation of up to 33% for the combined free heme pigment content. The employed second-derivative algorithm allows for automated and highly specific quantification of the free heme pigment content in diluted human plasma, which cannot be realized with standard spectrophotometric evaluation methods. An Excel-based tool readily applicable to clinical datasets accompanies this manuscript.

Homogeneously Emitting, Mechanically Stable, and Efficient fs-Laser-Machined Fiber Diffusers for Medical Applications

BACKGROUND AND OBJECTIVES

Light delivery is an essential part of therapy forms like photodynamic therapy (PDT), laser-induced thermotherapy, and endovenous laser therapy. While there are approaches to the light application for all three therapies, there is no diffuser that can be used for all three approaches. This diffuser must meet the following criteria: Homogeneous radiation profile over a length of 40 mm, efficient light extraction in the diffuser area, mechanical breakage resistance as well as thermal stability when applying high power.

STUDY DESIGN/MATERIALS AND METHODS

An ultrashort pulse laser was used to inscribe inhomogeneities into the core of a fused-silica fiber core while scanning the laser focus within a linear arrangement of cuboids centered around the fiber axis. The manufactured diffuser was optically and mechanically characterized and examined to determine the maximum power that can be applied in a tissue environment.

RESULTS

Based on the analysis of all examined diffusers, the manufactured diffuser exhibits an emission efficiency ε = (81.5 ± 5.9)%, an intensity variability of (19 ± 5)% between distal and proximal diffuser end, and a minimum bending radius R_b = (15.4 ± 1.5) mm. It was taken advantage of the fact that the outer areas of the fiber core do not undergo any structural changes due to the machining and therefore do not suffer a major loss of stability. Tissue experiments revealed that a maximal power of 15 W was deliverable from the diffuser without harming the diffuser itself.

CONCLUSIONS

It could be shown that a diffuser manufactured by ultrafast-laser processing can be used for low power applications as well as for high power applications. Further tests have to show whether the mechanical stability is still maintained after the application of high power in a tissue environment. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

CTIM-16. INTERSTITIAL PHOTODYNAMIC THERAPY WITH 5-ALA FOR MALIGNANT GLIOMA RECURRENCES

Interstitial photodynamic therapy (iPDT) using 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PPIX) as a cytotoxic photosensitizer has been shown to be a feasible treatment option for malignant gliomas. We present outcome measures and a risk profile analysis of salvage iPDT in a large monocentric cohort with local tumor recurrence following standard therapy. This study included consecutive adult patients undergoing salvage iPDT for small, circumscribed, biopsy-proven malignant glioma recurrences not deemed eligible for safe complete resection of contrast enhancing tumor. A modified 3-D treatment-planning software was used to calculate the treatment-volume and the position of the stereotactic light diffusers within the lesion. Outcome measurements included estimated time-to-treatment-failure (TTF), post-recurrence survival (PRS) and the risk profile of iPDT. Prognostic factors were obtained from logistic regression models. The institutional review board approved the study. A total of 44 patients (median age: 49.4 years, range 33.4–87.0 years, 17 female) were included. Recurrent tumors included 37/44 glioblastomas WHO grade IV and 7/44 anaplastic astrocytomas WHO grade III. Thirty (68.2%) tumors were MGMT methylated. Median treatment volume was 3.3 ccm (range, 0.5–22.8 ccm). A median number of 4 (range: 3–8) laser fibers were used. Median illumination time was 60min (range: 60–167 min). Symptomatic edema (8/44) or intratumoral hemorrhagic imbibition (7/44) did not result in any permanent morbidity. Median TTF was 7.1 months and median PRS was 13.0 months. The 2- and 5-years PRS rates were 25.0% and 4.5%. Treatment response was heterogeneous and not significantly associated with patient characteristics, treatment-related factors or molecular markers. In conclusion, iPDT was associated with promising outcome measurements in local malignant glioma recurrences in highly selected patients. Transient neurologic deterioration did not lead to any permanent morbidity. The procedure deserves further prospective evaluation particularly to identify mechanisms of favorable treatment response and prognostic factors associated with long-term survival.

Investigation of non-uniformly emitting optical fiber diffusers on the light distribution in tissue

The influence of inhomogeneities in the emission characteristics of optical fiber diffusers on the light distribution within biological tissue was evaluated by Monte Carlo (MC) simulations and by experiments on optical phantoms. Due to the strong scattering of light within biological tissue, inhomogeneities in the emission profile become blurred within a short light propagation distance, so that the light distribution within the tissue approaches that of a homogeneous diffuser. The degree of feature vanishing in the light distribution is mainly determined by the width of the inhomogeneities. It was shown that the influence of local inhomogeneities on top of a homogeneous light distribution fades away very effectively within 1 mm of tissue depth, which results in a light distribution very close to that for a homogeneously emitting diffuser. Emission profiles composed of multiple narrow peaks distributed over the full diffuser length with a peak-to-peak distance of less than 2 mm result in an almost homogeneous light distribution after approximately 1 mm of tissue depth. While this article is focused on the impact of diffuser inhomogeneities on the light distribution within the tissue, the importance of further investigations on the related thermal effects is also discussed.

Comparative investigation of reusable and single-use flexible endoscopes for urological interventions

In order to evaluate the technical adaptability of a type of disposable endoscope compared to reusable flexible endoscopes, in vitro and in vivo studies were conducted. A disposable digital ureteroscope ("chip on tip") and two reusable endoscopes were investigated with respect to spatial resolution, geometric distortion in air and water the maximum. Additionally, the clinical performance of the disposable device was tested during clinical procedures (n = 20). The disposable endoscope showed an optical resolution of 6.72 lines/mm at 10 mm distance, similar to the other devices. In comparison, the disposable endoscope showed a barrel-shaped image distortion in air of -24.2%, which is in the middle range, but was best under water (-8.6%). The bendability of 297° (275 µm fiber) and 316° (empty channel, 1.5 F basket) and the maximum irrigation (1 m: 58.1 ml/min, 2 m: 91.9 ml/min) were convincing. Clinically the maneuverability was very good in (13/20), good or satisfactory in (7/20). Visibility was evaluated as very good in (11/20), just in (1/20) either satisfactory or sufficient. The consistency of visibility was not affected in (19/20). In all cases there were no adverse events. The technical examination and clinical application of the disposable endoscope are of equal quality compared to reusable devices. Disposable endoscopes can be an alternative to reusable devices, but economic aspects such as reduction of repair costs, sterilization effort and additional waste must be taken into account.

Fluorescence and Treatment Light Monitoring for Interstitial Photodynamic Therapy

In interstitial photodynamic therapy, light is distributed to the tumor via light diffusers. The light dose and the related phototoxic effect achieved throughout the target volume critically depend on absorption, scattering and diffuser positioning. Using liquid tissue phantoms, we investigated the dependencies of treatment light transmission and protoporphyrin IX (PpIX) fluorescence on these parameters. This enabled monitoring hemoglobin oxygenation and methemoglobin formation during irradiation (635 nm, 200 mW cm^-1 diffuser length). Starting with two parallel cylindrical diffusers at 10 mm radial separation, the light transmitted between the fibers was largely determined by the minimal distance between the diffusers, but rather insensitive to an additional axial displacement or tilting of one fiber with respect to the other. For fixed distance between the diffusor centers, however, tilting up to direct contact resulted in a 10-fold signal increase. For hemoglobin within erythrocytes, irradiation leads to photobleaching of PpIX without marked change in hemoglobin oxygenation until hemolysis occurs. Afterward, hemoglobin is rapidly deoxygenized and methemoglobin is formed, leading to a dramatic increase in absorption. For lysed blood, these effects start immediately. A comparison of intraoperative monitoring of the signals with the experimental results might help prevent insufficient treatment by reconsidering treatment planning or prolonging irradiation.

MOP-dependent enhancement of methadone on the effectiveness of ALA-PDT for A172 cells by upregulating phosphorylated JNK and BCL2

BACKGROUND

Methadone, as a long-acting opioid analgesic, shows an ability to sensitize the treatment of ALA-PDT for glioblastoma cells (A172) in vitro by promoting apoptosis. However, the mechanisms how methadone enhances the effectiveness of ALA-PDT for tumor cells remains to be clarified.

METHODS

The expression of mu opioid receptor (MOP), apoptosis, phosphorylated c-Jun N-terminal kinase (JNK) and phosphorylated apoptosis regulator B cell lymphoma 2 (BCL2) were measured by flow cytometry. Cytotoxicity was determined using Cell Counting Kit-8 (CCK-8). A MOP antagonist, naloxone, was used to evaluate the role of MOP in the above process.

RESULTS

It was found that A172 cells show the expression of MOP and that naloxone inhibits the enhancement of the methadone effect on apoptosis following ALA-PDT (p < 0.05). Phosphorylated JNK and BCL2 induced by ALA-PDT were promoted in the presence of methadone (p < 0.05). These methadone effects were also inhibited by naloxone (p < 0.05).

CONCLUSIONS

The results suggest that apoptosis induced by ALA-PDT is enhanced by methadone, mostly MOP-mediated, through the upregulation of accumulation of phosphorylated JNK and BCL2, leading to a promotion of cytotoxicity of ALA-PDT for A172 cells.

Methadone enhances the effectiveness of 5-aminolevulinic acid-based photodynamic therapy for squamous cell carcinoma and glioblastoma in vitro

Although having shown promising clinical outcomes, the effectiveness of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) for squamous cell carcinoma (SCC) and glioblastoma remains to be improved. The analgesic drug methadone is able to sensitize various tumors to chemotherapy. In this in vitro study, the influence of methadone to the effectiveness of ALA-PDT for SCC (FADU) and glioblastoma (A172) was investigated on the protoporphyrin IX (PpIX) fluorescence, survival rates, apoptosis, and cell cycle phase, each with or without the presence of methadone. The production of PpIX was increased by methadone in FADU cells while it was decreased in A172 cells. The survival rates of both cell lines treated by ALA-PDT were significantly reduced by the combination with methadone (P < .05). Methadone also significantly increased the percentage of apoptotic cells and improved the effect of ALA-PDT on the cell cycle phase arrest in the G0/G1 phase (P < .05). This study demonstrates the potential of methadone to influence the cytotoxic effect of ALA-PDT for both SCC and glioblastoma cell lines.

Photothermal therapy enhanced the effectiveness of imiquimod against refractory cutaneous warts through boosting immune responses

Refractory cutaneous warts are difficult to eliminate. In situ photo-immunotherapy (ISPI) is an innovative treatment concept combining local photothermal therapy (PTT) and topical immunotherapy using imiquimod. To compare the efficacy of ISPI vs topical imiquimod alone, a prospective randomized controlled trial was performed with patients suffering from refractory cutaneous warts. In both groups, approximately 50% of the skin surface containing warts was treated for 6 weeks. On the basis of topical imiquimod, ISPI includes an additional 808 nm laser irradiation. Treatment response, temperatures during irradiation and histopathologic examination were evaluated. The complete response rate in the ISPI-group (22/36, 61.1%) was significantly higher than in the imiquimod alone group (11/34, 32.4%). In the ISPI-group, the mean maximum temperature was 44.5 ± 5.1°C, and obvious lymphocytic infiltration was found in the perivasculature of the dermis. There was no recurrence or worsening in both groups during the 12-month follow-up. No obvious adverse reaction was observed. This study demonstrates that ISPI can be used as an effective and safe treatment modality for refractory cutaneous warts.

Application of different noninvasive diagnostic techniques used in HMME-PDT in the treatment of port wine stains

BACKGROUND

Hematoporphyrin monomethyl ether photodynamic therapy (HMME-PDT) is an effective method for treating port wine stains (PWS). However, methods to evaluate the treatment of HMME-PDT for PWS effectively and objectively are lacking.

OBJECTIVE

This study aimed to describe the different noninvasive diagnostic techniques used in the evaluation of treatment response to HMME-PDT for PWS.

METHODS

Thirty-one lesions of 22 patients with PWS were treated with HMME-PDT. Four noninvasive diagnostic techniques including VISIA-CR™ system, dermoscopy, high-frequency ultrasound (HFUS), and laser speckle contrast imaging (LSCI) were used to obtain standard radiographic data on skin color, skin thickness, blood vessel morphology, blood vessel distribution, and blood perfusion from lesions and surrounding normal skin before and after HMME-PDT.

RESULTS

The standard image pattern of VISIA-CR™ system showed color change in the lesions of PWS after HMME-PDT. RBX red image of VISIA-CR™ system showed that erythema was highly aggregated even in invisible lesions at baseline but decreased after HMME-PDT. The erythema index reduced value d was related to the efficacy rating (γ = 0.631, P < 0.05). Dermoscopy showed that the number of spot-like and irregular linear vessels increased, which was correlated with the increase in clinical classification. After HMME-PDT, vascular rupture was observed by dermoscopy. The response rate of lesions with vascular rupture was 100.00% (20/20). Moreover, the response rate of lesions without vascular rupture was 63.64% (7/11). Vascular rupture sign was correlated with better efficacy (P < 0.05). HFUS showed that the dermis of PWS thickened and was arranged loosely with scattered linear hypoechoic signal. After HMME-PDT, the dermal layer of the lesions became thinner with a decreased linear hypoechoic signal. The response rate of the lesions with linear hypoechoic signal was 76.92% (10/13), and that without linear hypoechoic signal was 94.44% (17/18). The lesions without linear hypoechoic signal in the dermis showed better efficacy (P < 0.05). In some lesions, LSCI showed high blood perfusion signal in PWS lesions and blood perfusion reduction after HMME-PDT.

CONCLUSION

VISIA-CR™ system can be used to observe not only visible but also invisible lesions of PWS. Moreover, lesions fading after HMME-PDT can be described objectively by VISIA-CR™ system. Dermoscopy played an important role in the clinical classification of PWS, including assessing vascular injury after HMME-PDT, guiding the adjustment of therapeutic dose, and selecting the end point of treatment. Both HFUS and LSCI can be used to assist treatment response evaluation of HMME-PDT.

Introduction to the Biophotonics Congress 2018 feature issue

The guest editors introduce a feature issue containing papers based on research presented at the OSA Biophotonics Congress (the former BIOMED) held in Hollywood, FL, 2-6 April, 2018.

Holmium:yttrium-aluminum-garnet laser induced lithotripsy: in-vitro investigations on fragmentation, dusting, propulsion and fluorescence

The fragmentation efficiency on Bego artificial stones during lithotripsy and the propulsive effect (via video tracking) was investigated for a variety of laser settings. A variation of the laser settings (pulse energy, pulse duration, repetition rate) altered the total application time required for stone fragmentation, the stone break up time, and the propulsion. The obtained results can be used to develop lithotripsy devices providing an optimal combination of low stone propulsion and high fragmentation efficacy, which can then be evaluated in a clinical setting. Additionally, the fluorescence of human kidney stones was inspected endoscopically in vivo. Fluorescence light can be used to detect stone-free areas or to clearly distinguish calculi from surrounding tissue or operation tools.

Ultrafast dynamics of hard tissue ablation using femtosecond-lasers

Several studies on hard tissue laser ablation demonstrated that ultrafast lasers enable precise material removal without thermal side effects. Although the principle ablation mechanisms have been thoroughly investigated, there are still open questions regarding the influence of material properties on transient dynamics. In this investigation, we applied pump-probe microscopy to record ablation dynamics of biomaterials with different tensile strengths (dentin, chicken bone, gallstone and kidney stones) at delay times between 1 picosecond and 10 microseconds. Transient reflectivity changes, pressure and shock wave velocities and elastic constants were determined. The result revealed that absorption and excitation show the typical well-known transient behavior of dielectric materials. We observed for all samples a photomechanical laser ablation process, where ultrafast expansion of the excited volume generates pressure waves leading to fragmentation around the excited region. In addition, we identified tensile-strength-related differences in the size of ablated craters and ejected particles. The elastic constants derived were in agreement with literature values. In conclusion, pressure-wave-assisted material removal seems to be a general mechanism for hard tissue ablation with ultrafast lasers. This photomechanical process increases ablation efficiency and removes heated material, thus ultrafast laser ablation is of interest for clinical application where heating of the tissue must be avoided.

Investigation of optical properties of dissected and homogenized biological tissue

Knowledge of tissue optical properties, in particular the absorption μa and the reduced scattering coefficient μs', is required for diagnostic and therapeutic applications in which the light distribution during treatment has to be known. As it is generally very difficult to obtain this information with sufficient accuracy in vivo, optical properties are often approximately determined on ex vivo tissue samples. In this case, the obtained optical properties may strongly depend on the sample preparation. The extent of the expectable preparation-dependent differences was systematically investigated in comparative measurements on dissected and homogenized porcine tissue samples (liver, lung, brain, and muscle). These measurements were performed at wavelengths 520, 635, 660, and 785 nm, using a dual-step reflectance device and at a spectral range of 515 to 800 nm with an integrating sphere setup. In a third experiment, the density of tissue samples (dissected and homogenized) was investigated, as the characteristic of the packaging of internal tissue structures strongly influences the absorption and scattering. The standard errors of the obtained absorption and reduced scattering coefficients were found to be reduced in case of homogenized tissue. Homogenizing the tissues also allows a much easier and faster sample preparation, as macroscopic internal tissue structures are destroyed in the homogenized tissue so that a planar tissue sample with well-defined thickness can easily and accurately be prepared by filling the tissue paste into a cuvette. Consequently, a better reproducibility result was obtained when using homogenized samples. According to the density measurements accomplished for dissected and homogenized tissue samples, all types of tissues, except lung, showed a decrease in the density due to the homogenization process. The presented results are in good agreement for μs' regardless of the preparation procedure, whereas μa differs, probably influenced by blood content and dehydration. Because of faster and easier preparation and easier sample positioning, homogenization prior to measurement seems to be suitable for investigating the optical properties ex vivo. Additionally, by means of using the homogenization process, the sample size and thickness do not need to be particularly large, as is the case for most biopsies from the OR.

Rapid spectrophotometric quantification of urinary porphyrins and porphobilinogen as screening tool for attacks of acute porphyria

Autosomal-dominant acute porphyria, a group of rare diseases, can lead to life-threatening neurovisceral attacks. No efficient screening test is available today. Elevated urinary porphobilinogen in addition to elevated porphyrins is highly specific for an attack of acute porphyria. This study proposes and evaluates a custom-made device, algorithm, and methods for a two-step quantification of urinary porphyrins and porphobilinogen. The first step is oxidation of the nonfluorescent porphyrinogens and subsequent fluorescence-spectroscopic determination of total urinary porphyrins (TUP) using second derivative spectral fitting. Photo-oxidation is compared with chemical oxidation methods. The second step is the quantification of porphobilinogen in case of elevated TUP. Heat-induced conversion products of porphobilinogen, namely uroporphyrin and porphobilin, are quantified by fluorescence and absorption spectroscopy. Results show that the preferred method combination is TUP quantification (lower limit of quantification: 0.2  μmol  /  L) after photo-oxidation with subsequent absorption-spectroscopic determination of porphobilin after heating for indirect quantification of porphobilinogen (quantification range: 0 to 20  mg  /  L). Urinary porphobilinogen and porphyrins of one acute porphyria patient were quantified with <10  %   deviation from an external reference determination. The spectrophotometric approach requires only minimal sample processing and yields a result within 15 min, thus closing the screening gap for acute porphyria.

A second-derivate fitting algorithm for the quantification of free hemoglobin in human plasma

BACKGROUND

Assessment of hemolysis in vivo is becoming increasingly relevant in critical care. Current methods (Harboe, 1959) for quantifying the free hemoglobin (fHb) content produce unsatisfactory results in case of hyperbilirubinemia, a frequent condition in patients at risk for intravascular hemolysis.

METHODS

A novel evaluation method based on second-derivative fitting to quantify fHb content was developed. The method uses spectrophotometric data from 350 to 650 nm recorded with standard instruments as input. To evaluate the power of the new method, plasma of patients and non-icteric plasma of healthy volunteers were spiked with fHb concentrations up to 2000 mg/L and compared to methods described in the literature by Harboe, Noe and Fairbanks. All measurements were done in compliance with the bioanalytical method validation protocol from the European Medicines Agency.

RESULTS

Both the second-derivative fitting algorithm as well as the methods of Harboe, Noe and Fairbanks quantified fHb accurately in non-icteric samples, with inaccuracy and imprecision below 10%. For icteric specimen, false high results were obtained with the established formulas for fHb concentrations below 700 mg/L. In contrast, no interference was found with the second-derivate fitting method for bilirubin concentrations up to 465 μmol/L. The lower limits of quantifications for the second-derivative fitting algorithm were specified in agreement with the EMA guideline with 25 mg/L fHb for both non-icteric and icteric specimens.

CONCLUSIONS

A user-friendly, computer-based algorithm is reported that allows the accurate quantification of fHb concentrations in the presence of high bilirubin concentrations. The new method allows for uniform sample preparation with only a single dilution step and can be readily implemented in any laboratory on standard spectrophotometers using the provided supplementary Microsoft Excel macro.

In vitro investigations of propulsion during laser lithotripsy using video tracking

OBJECTIVES

Ureteroscopic laser lithotripsy is an important and widely used method for destroying ureter stones. It represents an alternative to ultrasonic and pneumatic lithotripsy techniques. Although these techniques have been thoroughly investigated, the influence of some physical parameters that may be relevant to further improve the treatment results is not fully understood. One crucial topic is the propulsive stone movement induced by the applied laser pulses. To simplify and speed up the optimization of laser parameters in this regard, a video tracking method was developed in connection with a vertical column setup that allows recording and subsequently analyzing the propulsive stone movement in dependence of different laser parameters in a particularly convenient and fast manner.

MATERIALS AND METHODS

Pulsed laser light was applied from below to a cubic BegoStone phantom loosely guided within a vertical column setup. The video tracking method uses an algorithm to determine the vertical stone position in each frame of the recorded scene. The time-dependence of the vertical stone position is characterized by an irregular series of peaks. By analyzing the slopes of the peaks in this signal it was possible to determine the mean upward stone velocity for a whole pulse train and to compare it for different laser settings. For a proof of principle of the video tracking method, a specific pulse energy setting (1 J/pulse) was used in combination with three different pulse durations: short pulse (0.3 ms), medium pulse (0.6 ms), and long pulse (1.0 ms). The three pulse durations were compared in terms of their influence on the propulsive stone movement in terms of upward velocity. Furthermore, the propulsions induced by two different pulse energy settings (0.8 J/pulse and 1.2 J/pulse) for a fixed pulse duration (0.3 ms) were compared. A pulse repetition rate of 10 Hz was chosen for all experiments, and for each laser setting, the experiment was repeated on 15 different freshly prepared stones. The latter set of experiments was compared with the results of previous propulsion measurements performed with a pendulum setup.

RESULTS

For a fixed pulse energy (1 J/pulse), the mean upward propulsion velocity increased (from 120.0 to 154.9 mm · s^-1 ) with decreasing pulse duration. For fixed pulse duration (0.3 ms), the mean upward propulsion velocity increased (from 91.9 to 123.3 mm · s^-1 ) with increasing pulse energy (0.8 J/pulse and 1.2 J/pulse). The latter result corresponds roughly to the one obtained with the pendulum setup (increase from 61 to 105 mm · s^-1 ). While the mean propulsion velocities for the two different pulse energies were found to differ significantly (P < 0.001) for the two experimental and analysis methods, the standard deviations of the measured mean propulsion velocities were considerably smaller in case of the vertical column method with video tracking (12% and 15% for n = 15 freshly prepared stones) than in case of the pendulum method (26% and 41% for n = 50 freshly prepared stones), in spite of the considerably smaller number of experiment repetitions ("sample size") in the first case.

CONCLUSION

The proposed vertical column method with video tracking appears advantageous compared to the pendulum method in terms of the statistical significance of the obtained results. This may partly be understood by the fact that the entire motion of the stones contributes to the data analysis, rather than just their maximum distance from the initial position. The key difference is, however, that the pendulum method involves only one single laser pulse in each experiment run, which renders this method rather tedious to perform. Furthermore, the video tracking method appears much better suited to model a clinical lithotripsy intervention that utilizes longer series of laser pulses at higher repetition rates. The proposed video tracking method can conveniently and quickly deliver results for a large number of laser pulses that can easily be averaged. An optimization of laser settings to achieve minimal propulsive stone movement should thus be more easily feasible with the video tracking method in connection with the vertical column setup. Lasers Surg. Med. 50:333-339, 2018. © 2017 Wiley Periodicals, Inc.

Laser-assisted fixation of a nitinol stapes prosthesis

BACKGROUND AND OBJECTIVE

Otosclerosis is an inner ear bone disease characterized by fixation of the stapes and consequently progressive hearing loss. One treatment option is the surgical replacement of the stapes by a prosthesis. When so called "smart materials" like nitinol are used, prosthesis fixation can be performed using a laser without manual crimping on the incus. However, specific laser-prosthesis interactions have not been described yet. The aim of the present study was to elucidate the thermo-mechanical properties of the NiTiBOND® prosthesis as a basis for handling instructions for laser-assisted prosthesis fixation.

STUDY DESIGN AND MATERIALS AND METHODS

Closure of the NiTiBOND® prosthesis was induced ex vivo by either a diode laser emitting at λ = 940 nm or a CO₂ laser (λ = 10,600 nm). Total energy for closure was determined. Suitable laser parameters (pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis) were assessed. Specific laser-prosthesis interactions were recorded.

RESULTS

Especially the diode laser was found to be an appropriate energy source. A total energy deposit of 60 mJ by pulses in near contact application was found to be sufficient for prosthesis closure ex vivo. Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter. Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account.

CONCLUSION

NiTiBOND® stapes prosthesis can be closed by very little energy when appropriate energy sources like diode lasers are used, suggesting a relatively safe application in vivo. Lasers Surg. Med. 50:153-157, 2018. © 2017 Wiley Periodicals, Inc.

Volumetric Optoacoustic Temperature Mapping in Photothermal Therapy

Photothermal therapy and ablation are commonplace medical procedures employed for treatment of tumors, vascular and brain abnormalities as well as other disorders that require selective destruction of tissues. Yet, accurate mapping of the dynamic temperature field distribution in the treated region represents an unmet clinical need, strongly affecting the clinical outcome of these interventions. We introduce a fast three-dimensional temperature mapping method based on real-time optoacoustic sensing of the treated region coupled with a thermal-diffusion-based model of heat distribution in tissues. Deviations of the optoacoustic temperature readings provided at 40  ms intervals remained below 10% in tissue-mimicking phantom experiments for temperature elevations above 3 °C, as validated by simultaneous thermocouple measurements. Performance of the new method to dynamically estimate the volumetric temperature distribution was further showcased in post-mortem mouse imaging experiments. The newly discovered capacity to non-invasively measure the temperature map in an entire treated volume with both high spatial and temporal resolutions holds potential for improving safety and efficacy of light-based therapeutic interventions.

Remission spectrometry for blood vessel detection during stereotactic biopsy of brain tumors

Stereotactic biopsy is used to enable diagnostic confirmation of brain tumors and treatment planning. Despite being a well-established technique, it is related to significant morbidity and mortality rates mostly caused by hemorrhages due to blood vessel ruptures. This paper presents a method of vessel detection during stereotactic biopsy that can be easily implemented by integrating two side-view fibers into a conventional side-cutting biopsy needle. Tissue within the needle window is illuminated through the first fiber; the second fiber detects the remitted light. By taking the ratio of the intensities at two wavelengths with strongly differing hemoglobin absorption, blood vessels can be recognized immediately before biopsy sampling. Via ray tracing simulations and phantom experiments, the dependency of the remission ratio R = I₅₇₈ /I₆₅₀ on various parameters (blood oxygenation, fiber-to-vessel and inter-fiber distance, vessel diameter and orientation) was investigated for a bare-fiber probe. Up to 800-1200 µm away from the probe, a vessel can be recognized by a considerable reduction of the remission ratio from the background level. The technique was also successfully tested with a real biopsy needle probe on both optical phantoms and ex-vivo porcine brain tissue, thus showing potential to improve the safety of stereotactic biopsy. Dual-wavelength remission measurement for the detection of blood vessels during stereotactic biopsy.

Protoporphyrin IX fluorescence as potential indicator of psoriasis severity and progression

BACKGROUND AND OBJECTIVES

In psoriatic lesions, fluorescence diagnosis with blue light can detect protoporphyrin IX accumulation, especially after topical 5-aminolaevulinic acid (ALA) application. However, variable fluorescence distributions, interpersonal variations and long incubation time limit its wide application in clinic. This study is aimed to identify a consistent and convenient method to facilitate diagnosis and evaluation of psoriatic lesions.

METHODS

104 psoriatic lesions from 30 patients were evaluated. Single lesion PSI scoring and fluorescence by macrospectrofluorometry were recorded on each lesion before and after treatment with narrow-band UVB.

RESULTS

Punctate red fluorescence, emitted mainly by protoporphyrin IX, is observed in some psoriatic lesions. According to psoriasis severity index, fluorescence-positive lesions are more severe than lesions without fluorescence. We found a significant positive correlation between psoriasis severity and fluorescence intensity from protoporphyrin IX.

CONCLUSIONS

Protoporphyrin IX-induced red fluorescence can be used as a novel and convenient approach for psoriasis diagnosis and progression evaluation.

Micro-endoscopy of the human vas deferens: a feasibility study of a novel device in several ex vivo models

The aim of this study was to show limitation as well as potential of micro-endoscopy techniques as an innovative diagnostic and therapeutic approach in andrology. Two kinds of custom-made micro-endoscopes (ME) were tested in ex vivo vas deferens specimen and in post-mortem whole body. The semi-rigid ME included a micro-optic (0.9 mm outer diameter [OD], 10.000 pixels, 120° vision angle [VE], 3-20 mm field depth [FD]) and an integrated fibre-optic light source. The flexible ME was composed of a micro-optic (OD = 0.6 mm, 6.000 pixels, 120° VE, 3-20 mm FD). The ex vivo study included retrograde investigation of the vas deferens (surgical specimen n = 9, radical prostatectomy n = 3). The post-mortem investigation (n = 4) included the inspection of the vas deferens via both approaches. The results showed that antegrade and retrograde rigid endoscopy of the vas deferens were achieved as a diagnostic tool. The working channel enabled therapeutic use including biopsies or baskets. Using the flexible ME, the orifices of the ejaculatory ducts were identified. In vivo cadaveric retrograde cannulation of the orifices was successful. Post-mortem changes of verumontanum hindered the examinations beyond. Orifices were identified shaded behind a thin transparent membrane. Antegrade vasoscopy using flexible ME was possible up to the internal inguinal ring. Further advancement was impossible because of anatomical angle and lack adequate vision guidance. The vas deferens interior was clearly visible and was documented by pictures and movies. Altogether, the described ME techniques were feasible and effective, offering the potential of innovative diagnostic and therapeutic approaches for use in the genital tract. Several innovative indications could be expected.