Focal laser ablation as clinical treatment of prostate cancer: report from a Delphi consensus project

PURPOSE

To define the role of focal laser ablation (FLA) as clinical treatment of prostate cancer (PCa) using the Delphi consensus method.

METHODS

A panel of international experts in the field of focal therapy (FT) in PCa conducted a collaborative consensus project using the Delphi method. Experts were invited to online questionnaires focusing on patient selection and treatment of PCa with FLA during four subsequent rounds. After each round, outcomes were displayed, and questionnaires were modified based on the comments provided by panelists. Results were finalized and discussed during face-to-face meetings.

RESULTS

Thirty-seven experts agreed to participate, and consensus was achieved on 39/43 topics. Clinically significant PCa (csPCa) was defined as any volume Grade Group 2 [Gleason score (GS) 3+4]. Focal therapy was specified as treatment of all csPCa and can be considered primary treatment as an alternative to radical treatment in carefully selected patients. In patients with intermediate-risk PCa (GS 3+4) as well as patients with MRI-visible and biopsy-confirmed local recurrence, FLA is optimal for targeted ablation of a specific magnetic resonance imaging (MRI)-visible focus. However, FLA should not be applied to candidates for active surveillance and close follow-up is required. Suitability for FLA is based on tumor volume, location to vital structures, GS, MRI-visibility, and biopsy confirmation.

CONCLUSION

Focal laser ablation is a promising technique for treatment of clinically localized PCa and should ideally be performed within approved clinical trials. So far, only few studies have reported on FLA and further validation with longer follow-up is mandatory before widespread clinical implementation is justified.

The prostate cancer prevention trial risk calculator 2.0 performs equally for standard biopsy and MRI/US fusion-guided biopsy

BACKGROUND

The Prostate Cancer Prevention Trial Risk Calculator 2.0 (PCPTRC) is a widely used risk-based calculator used to assess a man's risk of prostate cancer (PCa) before biopsy. This risk calculator was created from data of a patient cohort undergoing a 6-core sextant biopsy, and subsequently validated in men undergoing 12-core systematic biopsy (SBx). The accuracy of the PCPTRC has not been studied in patients undergoing magnetic resonance imaging/ultrasound (MRI/US) fusion-guided biopsy (FBx). We sought to assess the performance of the PCPTRC for straitifying PCa risk in a FBx cohort.

METHODS

A review of a prospective cohort undergoing MRI and FBx/SBx was conducted. Data from consecutive FBx/SBx were collected between August 2007 and February 2014, and PCPTRC scores using the PCPTRC2.0R-code were calculated. The risk of positive biopsy and high-grade cancer (Gleason ⩾7) on biopsy was calculated and compared with overall and high-grade cancer detection rates (CDRs). Receiver operating characteristic curves were generated and the areas under the curves (AUCs) were compared using DeLong's test.

RESULTS

Of 595 men included in the study, PCa was detected in 39% (232) by SBx compared with 48% (287) on combined FBx/SBx biopsy. The PCPTRC AUCs for the CDR were similar (P=0.70) for SBx (0.69) and combined biopsy (0.70). For high-grade disease, AUCs for SBx (0.71) and combined biopsy (0.70) were slightly higher, but were not statistically different (P=0.55).

CONCLUSIONS

In an MRI-screened population of men undergoing FBx, PCPTRC continues to represent a practical method of accurately stratifying PCa risk.

Utilization of multiparametric prostate magnetic resonance imaging in clinical practice and focal therapy: report from a Delphi consensus project

Purpose

To codify the use of multiparametric magnetic resonance imaging (mpMRI) for the interrogation of prostate neoplasia (PCa) in clinical practice and focal therapy (FT).

Methods

An international collaborative consensus project was undertaken using the Delphi method among experts in the field of PCa. An online questionnaire was presented in three consecutive rounds and modified each round based on the comments provided by the experts. Subsequently, a face-to-face meeting was held to discuss and finalize the consensus results.

Results

mpMRI should be performed in patients with prior negative biopsies if clinical suspicion remains, but not instead of the PSA test, nor as a stand-alone diagnostic tool or mpMRI-targeted biopsies only. It is not recommended to use a 1.5 Tesla MRI scanner without an endorectal or pelvic phased-array coil. mpMRI should be performed following standard biopsy-based PCa diagnosis in both the planning and follow-up of FT. If a lesion is seen, MRI-TRUS fusion biopsies should be performed for FT planning. Systematic biopsies are still required for FT planning in biopsy-naïve patients and for patients with residual PCa after FT. Standard repeat biopsies should be taken during the follow-up of FT. The final decision to perform FT should be based on histopathology. However, these consensus statements may differ for expert centers versus non-expert centers.

Conclusions

The mpMRI is an important tool for characterizing and targeting PCa in clinical practice and FT. Standardization of acquisition and reading should be the main priority to guarantee consistent mpMRI quality throughout the urological community.

Electronic supplementary material

The online version of this article (doi:10.1007/s00345-016-1932-1) contains supplementary material, which is available to authorized users.

A fast fan-beam backprojection algorithm based on efficient sampling

We introduce a fast algorithm to backproject fan-beam tomographic projections. For typical configurations of computed tomography scanners, the algorithm reduces the number of computations and actual runtimes by an order of magnitude. Similar to fast algorithms for the parallel-beam geometry, this algorithm is a divide-and-conquer method that aggregates the projections in a hierarchical manner. The computational speedup results from the use of sparse sampling grids to represent images that are comprised of a small number of projections that are close together in view-angle. In the parallel beam case these sparse (Cartesian) sampling grids were constructed by exploiting the projection slice theorem. Extending the parallel beam algorithms to fan-beam is a significant step because there is no equivalent to the projection-slice theorem for the fan-beam geometry. This was achieved using a novel analysis of fan-beam backprojection that characterizes the spatially-varying frequency content. This analysis, which we present here, allows for the construction and use of the sparse (non-Cartesian) sampling grids.

Self-assembly of Silver Nanoparticles and Multiwall Carbon Nanotubes on Decomposed GaAs Surfaces

Atomic Force Microscopy complemented by Photoluminescence and Reflection High Energy Electron Diffraction has been used to study self-assembly of silver nanoparticles and multiwall carbon nanotubes on thermally decomposed GaAs (100) surfaces. It has been shown that the decomposition leads to the formation of arsenic plate-like structures. Multiwall carbon nanotubes spin coated on the decomposed surfaces were mostly found to occupy the depressions between the plates and formed boundaries. While direct casting of silver nanoparticles is found to induce microdroplets. Annealing at 300°C was observed to contract the microdroplets into combined structures consisting of silver spots surrounded by silver rings. Moreover, casting of colloidal suspension consists of multiwall carbon nanotubes and silver nanoparticles is observed to cause the formation of 2D compact islands. Depending on the multiwall carbon nanotubes diameter, GaAs/multiwall carbon nanotubes/silver system exhibited photoluminescence with varying strength. Such assembly provides a possible bottom up facile way of roughness controlled fabrication of plasmonic systems on GaAs surfaces.

Over 4000 nm bandwidth of mid-IR supercontinuum generation in sub-centimeter segments of highly nonlinear tellurite PCFs

We report broad bandwidth, mid-IR supercontinuum generation using a sub-cm (8 mm) length of highly nonlinear tellurite microstructured photonic crystal fiber (PCF). We pump the fiber at telecommunication wavelengths by using 1550 nm, 100 fs pulses of energy E=1.9 nJ. When coupled in the PCF, these pulses result in a supercontinuum (SC) bandwidth of 4080 nm extending from 789 to 4870 nm measured at 20 dBm below the peak spectral power. This bandwidth is comparable or in excess of previously reported spectra for other nonlinear glass fiber formulations despite the significantly shorter fiber length. In addition, besides offering a convenient pump wavelength, short fiber lengths enable smoother SC spectra, lower dispersion, and reduced material absorption at longer wavelengths making the use of this PCF particularly interesting.

Optical pulse compression in dispersion decreasing photonic crystal fiber

Improvements to tapered photonic crystal fiber (PCF) fabrication have allowed us to make up to 50 m long PCF tapers with loss as low as 30 dB/km. We discuss the design constraints for tapered PCFs used for adiabatic soliton compression and demonstrate over 15 times compression of pulses from over 830 fs to 55 fs duration at a wavelength of 1.06 lm, an order of magnitude improvement over previous results.

Mid-infrared methane detection in a photonic bandgap fiber using a broadband optical parametric oscillator

We demonstrate methane sensing using a photonic bandgap fiber-based gas cell and broadband idler pulses from a periodically-poled lithium niobate femtosecond optical parametric oscillator. The hollow core of the fiber was filled with a methane:nitrogen mixture, and Fourier transform spectroscopy was used to measure transmission spectra in the 3.15-3.35 mum methane absorption region. The method has applications in gas sensing for remote or hazardous environments and potentially at very low concentrations.

Delivery of sub-100fs pulses through 8m of hollow-core fiber using soliton compression

We report soliton compression in a tapered hollow-core photonic bandgap fiber. We compress unchirped 195fs input pulses at 800 nm wavelength to less than 100fs after single-mode propagation through 8m of fiber, at pulse energies of around 50nJ.

High nonlinearity glass photonic crystal nanowires

Soft glass photonic crystal fibers (PCFs) have been fabricated for the first time with the stack and draw process. The same SF6-PCFs have been successfully tapered using a brush flame method. The transverse structure of the PCF does not collapse in the tapering process and core dimensions of the fabricated photonic nanowire has been measured to be 400 nm in diameter. Supercontinuum radiation in excess of one octave has been generated in both the untapered and tapered PCF and, in the latter case, pulse energy thresholds of 65 picojoules at a pump wavelength of 1550 nm were observed.

An improved photonic bandgap fiber based on an array of rings

We describe the modeling, fabrication and characterization of a silica-core photonic bandgap fiber based on a 2-d array of raised-index cladding rings. The use of rings to form the cladding is shown to re-order the cladding modes in such a way as to broaden the photonic band gaps and reduce bend sensitivity. We compare the performance of the ring fiber with that of a similar fiber made using solid rods.

Zero-dispersion wavelength decreasing photonic crystal fibers for ultraviolet-extended supercontinuum generation

We report the fabrication of photonic crystal fibers with a continuously-decreasing zero-dispersion wavelength along their length. These tapered fibers are designed to extend the generation of supercontinuum spectra from the visible into the ultraviolet. We report on their performance when pumped with both nanosecond and picosecond sources at 1.064 microm. The supercontinuum spectra have a spectral width (measured at the 10 dB points) extending from 0.372 microm to beyond 1.75 microm. In an optimal configuration a flat (3 dB) spectrum from 395 to 850 nm, with a minimum spectral power density of 2 mW/nm was achieved, with a total continuum output power of 3.5 W. We believe that the shortest wavelengths were generated by cascaded four-wave mixing: the continuous decrease of the zero dispersion wavelength along the fiber length enables the phase-matching condition to be satisfied for a wide range of wavelengths into the ultraviolet, while simultaneously increasing the nonlinear coefficient of the fiber.

Spectrally smooth supercontinuum from 350 nm to 3 mum in sub-centimeter lengths of soft-glass photonic crystal fibers

The conversion of light fields in photonic crystal fibers (PCFs) capitalizes on the dramatic enhancement of several optical nonlinearities. We present here spectrally smooth, highly broadband supercontinuum radiation in a short piece of high-nonlinearity soft-glass PCF. This supercontinuum spans several optical octaves, with a spectral range extending from 350 nm to beyond 3000 nm. The selection of an appropriate propagation-length determines the spectral quality of the supercontinuum generated. Experimentally, we clearly identify two regimes of nonlinear pulse transformation: when the fiber length is much shorter than the dispersion length, soliton propagation is not important and a symmetric supercontinuum spectrum arises from almost pure self-phase modulation. For longer fiber lengths the supercontinuum is formed by the breakup of multiple Raman-shifting solitons. In both regions very broad supercontinuum radiation is produced.

Three-level neodymium fiber laser incorporating photonic bandgap fiber

We report a neodymium fiber laser incorporating an all-solid photonic bandgap fiber to suppress the four-level laser transition 4F(3/2)-4I(11/2). We demonstrate lasing at 907 nm on the three-level transition 4F(3/2)-4I(9/2) when pumping at 808 nm. The maximum slope efficiency obtained was 32% with a threshold pump power of 70 mW.

Hybrid photonic crystal fiber

We present a hybrid photonic crystal fiber in which a guided mode is confined simultaneously by modified total internal reflection from an array of air holes and antiresonant reflection from a line of high-index inclusions. Experimental results demonstrate that this fiber shares properties of both index-guided and photonic bandgap structures.

Splice-free interfacing of photonic crystal fibers

We report a new method for making low-loss interfaces between conventional single-mode fibers and photonic crystal fibers (PCFs). Adapted from the fabrication of PCF preforms from stacked tubes and rods, this method avoids the need for splicing and is versatile enough to interface to virtually any type of index-guiding silica PCF. We illustrate the method by forming interfaces to two problematic types of PCF, highly nonlinear and multicore. In particular, we believe this to be the first method capable of individually coupling light into and out of all the cores of a fiber with multiple closely spaced cores, without input or output cross talk.

All-solid photonic bandgap fiber

We describe the design and fabrication of a photonic bandgap fiber formed with two different glasses. As in a hollow-core fiber, light is guided in a low-index core region because of the antiresonances of the high-index strands in the fiber cladding. The structure described represents an ideal bandgap fiber that exhibits no interface modes and guides over the full width of multiple bandgaps.

Effect of acute ketoacidosis on the myocardium in diabetes

Abnormalities of left ventricular function are often present in patients with diabetes who are in a stable metabolic state. To determine whether acute metabolic abnormalities may contribute to pathogenesis, patients with diabetes and ketoacidosis (Group 1) or hyperglycemia without ketosis (Group 2) were studied. They were assessed noninvasively for evidence of acute injury or dysfunction of the myocardium. Left ventricular function was assessed on admission and after clinical recovery. Myocardial enzyme release was examined during the acute phase. In Group 1, plasma glucose averaged 32 mM/L and carbon dioxide content 12.4 mEq/L. On echocardiography, the initial circumferential shortening velocity of 1.85 + 0.07 circumferences per second was significantly higher than the final circumferential shortening velocity of 1.31 + 01 (P < 0.005). The systolic time interval ratio, pre-ejection period/left ventricular ejection time, was significantly lower on the initial day compared with the second study. These data are consistent with enhanced ventricular performance. In group 2, plasma glucose averaged 29 mM/L, and carbon dioxide content was normal. The initial circumferential shortening velocity of 1. 1 circumferences per second and pre-ejection period/left ventricular ejection time ratio of 0.38 were normal and remained unchanged. There was no significant alteration of heart rate or arterial pressure in either group. In both groups, total serum lactate dehydrogenase and creatinine phosphokinase levels, as well as their cardiac isoenzymes, were within normal limits. Therefore, the initial increase of myocardial performance and subsequent restoration to normal, as well as the lack of cardiac enzyme increase in plasma, support the view that shortterm ketoacidosis does not contribute to the abnormalities of ventricular function in diabetes.

Comparison of dobutamine and exercise echocardiography for detecting coronary artery disease

There has been no study comparing the efficacy of dobutamine and exercise echocardiography in detecting coronary artery disease (CAD) or their physiologic effects at ischemic threshold in the same group of patients. To accomplish this, 52 patients presenting for coronary angiography underwent supine ergometer exercise and dobutamine echocardiography. Compared with angiography, the overall sensitivity of detecting CAD was 78% for exercise and 86% for dobutamine echocardiography (p = NS). The sensitivities of detecting patients with 1-, 2-, 3- and multivessel CAD with exercise echocardiography were 63, 80, 100 and 90%, respectively, and with dobutamine echocardiography 75, 90, 100 and 95%, respectively (p = NS, exercise vs dobutamine). The specificity of both tests was 87%. At ischemic threshold, heart rate was significantly lower with dobutamine than with exercise echocardiography (91 +/- 3 vs 114 +/- 3 beats/min; p < 0.001), systolic blood pressure was significantly lower with dobutamine testing (155 +/- 5 vs 176 +/- 6 mm Hg; p < 0.01), and rate-pressure product was significantly lower with dobutamine stress (14.1 +/- 0.7 vs 19.8 +/- 0.8 x 10(3) beats/min x mm Hg; p < 0.001). It is concluded that the efficacy of detecting CAD by exercise and dobutamine echocardiography is comparable, and the physiology at ischemic threshold of the 2 methods is significantly different and suggests a different means of inducing myocardial ischemia.