Fiber Catheter Research Articles

Dual modality intravascular catheter system combining pulse-sampling fluorescence lifetime imaging and polarization-sensitive optical coherence tomography.

The clinical management of coronary artery disease and the prevention of acute coronary syndromes require knowledge of the underlying atherosclerotic plaque pathobiology. Hybrid imaging modalities capable of comprehensive assessment of biochemical and morphological plaques features can address this need. Here we report the first implementation of an intravascular catheter system combining fluorescence lifetime imaging (FLIm) with polarization-sensitive optical coherence tomography (PSOCT). This system provides multi-scale assessment of plaque structure and composition via high spatial resolution morphology from OCT, polarimetry-derived tissue microstructure, and biochemical composition from FLIm, without requiring any molecular contrast agent. This result was achieved with a low profile (2.7 Fr) double-clad fiber (DCF) catheter and high speed (100 fps B-scan rate, 40 mm/s pullback speed) console. Use of a DCF and broadband rotary junction required extensive optimization to mitigate the reduction in OCT performance originating from additional reflections and multipath artifacts. This challenge was addressed by the development of a broad-band (UV-visible-IR), high return loss (47 dB) rotary junction. We demonstrate in phantoms, ex vivo swine coronary specimens and in vivo swine heart (percutaneous coronary access) that the FLIm-PSOCT catheter system can simultaneously acquire co-registered FLIm data over four distinct spectral bands (380/20 nm, 400/20 nm, 452/45 nm, 540/45 nm) and PSOCT backscattered intensity, birefringence, and depolarization. The unique ability to collect complementary information from tissue (e.g., morphology, extracellular matrix composition, inflammation) with a device suitable for percutaneous coronary intervention offers new opportunities for cardiovascular research and clinical diagnosis.

Midterm varicose vein recurrence rates after endovenous laser ablation: comparison of radial fibre and bare fibre tips.

We evaluated and compared midterm recurrence results of our patients with great saphenous vein insufficiency who were treated with a 1470-nm diode laser using 2 different types of fibre catheter kits. A total of 61 consecutive patients were treated between 2013 and 2014 with a bare fibre (BF) tip (BF group) and 60 consecutive patients were treated with a radial fibre (RF) tip (RF group) from 2014 to 2016. First-year venous clinical severity scores (VCSSs) were compared with VCSS before endovenous laser ablation and at the first-month follow-up. Patients were examined for recurrence and classified according to the system developed by Stonebridge. There was no significant difference between the 2 groups in terms of VCSS. Examination with Doppler ultrasonography showed no recurrence in the RF group, whereas recurrences were detected in 6 patients in the BF group, which was statistically significant (P = 0.028). All of the recurrences were type 1b (incompetent tributaries) varicose vein recurrences. The VCSS of the patients with recurrence were the same as the scores of patients without recurrence (0.5 ± 0.55). Varicose vein recurrence was more often seen in the BF group than in the RF group. Recanalization-induced and neovascularization-induced recurrences were not found in either group. Saphenofemoral side branch-induced recurrence was more significant in the group treated with the BF tip.

Microincision vitrectomy surgery: experimental visualization and quantification of vitreous contamination

BackgroundTo visualize and quantify vitreous contamination following microincision vitrectomy surgery (MIVS) using an experimental vitreous contamination model (EVCM).MethodsEnucleated porcine eyes with fluoresbrite carboxylate microspheres applied to the conjunctival surface were used as a type 1 EVCM. Twenty-five- or 27-gauge (G) trocar cannulas were inserted through the conjunctiva and sclera, followed by the placing and opening of an infusion cannula. These procedures were monitored by an intraocular fiber catheter. Secondly, condensed microspheres were applied to an excised sheet of porcine sclera to serve as type 2 EVCM. Twenty-five- or 27-G trocar cannulas were inserted perpendicularly through the top of the sclera where the condensed microspheres were applied, an infusion cannula was inserted, 0.1 mL of saline solution injected through the infusion cannula, and samples collected. The fluorescence strength of samples was then measured using fluorophotometry.ResultsWe visually detected fluorescent microspheres in 10/10 eyes with 25-G and 10/10 with 27-G MIVS. In the experimental quantification study, each MIVS gauge value was significantly higher than the control (P < 0.01). However, there was no significant difference between 25-G and 27-G MIVS.ConclusionsMIVS carries the risk of introducing contamination directly into the eyes when the trocar cannula is inserted and infusion cannula is opened, even when a 27-G MIVS is used. Our study has shown it is essential that the surgeon be aware of the possibility of introducing contamination from the conjunctiva at all times during MIVS.

Development of hypothermia measurable fiber radiometric thermometer for thermotherapy.

Temperature monitoring is extremely important during thermotherapy. Fiber-optic temperature sensors are preferred because of their flexibility and immunity to electromagnetic interference. Although many types of fiber-optic sensors have been developed, clinically adopting them remains challenging. Here, we report a silica fiber-based radiometric thermometer using a low-cost extended InGaAs detector to detect black body radiation between 1.7 and 2.4 μm. For the first time, this silica fiber-based thermometer is capable of measuring temperatures down to 35°C, making it suitable for monitoring hyperthermia during surgery. In particular, the thermometer has potential for seamless integration with current silica fiber catheters, which are widely used in laser interstitial thermotherapy. The feasibility, capability and sensitivity of tracking tissue temperature variation were proved through ex vivo tissue studies. After further improvement, the technology has the potential to be translated into clinics for monitoring tissue temperature.

Detection of blackbody radiation during fiber guided laser-tissue vaporization.

Laser-tissue vaporization through a fiber catheter is evolving into a major category of surgical operations to remove diseased tissue. Currently, during a surgery, the surgeon still relies on personal experience to optimize surgical techniques. Monitoring tissue temperature during laser-tissue vaporization would provide important feedback to the surgeon; however, simple and low-cost temperature sensing technology, which can be seamlessly integrated with a fiber catheter, is not available. We propose to monitor tissue temperature during laser-tissue vaporization by detecting blackbody radiation (BBR) between 1.6 µm-1.8 µm, a relatively transparent window for both water and silica fiber. We could detect BBR after passing through a 2-meter silica fiber down to ∼70°C using lock-in detection. We further proved the feasibility of the technology through ex vivo tissue studies. We found that the BBR can be correlated to different tissue vaporization levels. The results suggest that this simple and low-cost technology could be used to provide objective feedback for surgeons to maximize laser-tissue vaporization efficiency and ensure the best clinical outcomes.

Intra-cardiac Side-Firing Light Catheter for Monitoring Cellular Metabolism using Transmural Absorbance Spectroscopy of Perfused Mammalian Hearts.

Absorbance spectroscopy of cardiac muscle provides non-destructive assessment of cytosolic and mitochondrial oxygenation via myoglobin and cytochrome absorbance respectively. In addition, numerous aspects of the mitochondrial metabolic status such as membrane potential and substrate entry can also be estimated. To perform cardiac wall transmission optical spectroscopy, a commercially available side-firing optical fiber catheter is placed in the left ventricle of the isolated perfused heart as a light source. Light passing through the heart wall is collected with an external optical fiber to perform optical spectroscopy of the heart in near real- time. The transmission approach avoids numerous surface scattering interference occurring in widely used reflection approaches. Changes in transmural absorbance spectra were deconvolved using a library of chromophore reference spectra, providing quantitative measures of all the known cardiac chromophores simultaneously. This spectral deconvolution approach eliminated intrinsic errors that may result from using common dual wavelength methods applied to overlapping absorbance spectra, as well as provided a quantitative evaluation of the goodness of fit. A custom program was designed for data acquisition and analysis, which permitted the investigator to monitor the metabolic state of the preparation during the experiment. These relatively simple additions to the standard heart perfusion system provide a unique insight into the metabolic state of the heart wall in addition to conventional measures of contraction, perfusion, and substrate/oxygen extraction.

Noise-bias and polarization-artifact corrected optical coherence tomography by maximum a-posteriori intensity estimation.

We propose using maximum a-posteriori (MAP) estimation to improve the image signal-to-noise ratio (SNR) in polarization diversity (PD) optical coherence tomography. PD-detection removes polarization artifacts, which are common when imaging highly birefringent tissue or when using a flexible fiber catheter. However, dividing the probe power to two polarization detection channels inevitably reduces the SNR. Applying MAP estimation to PD-OCT allows for the removal of polarization artifacts while maintaining and improving image SNR. The effectiveness of the MAP-PD method is evaluated by comparing it with MAP-non-PD, intensity averaged PD, and intensity averaged non-PD methods. Evaluation was conducted in vivo with human eyes. The MAP-PD method is found to be optimal, demonstrating high SNR and artifact suppression, especially for highly birefringent tissue, such as the peripapillary sclera. The MAP-PD based attenuation coefficient image also shows better differentiation of attenuation levels than non-MAP attenuation images.

EXPERIMENTAL VISUALIZATION AND QUANTIFICATION OF VITREOUS CONTAMINATION FOLLOWING INTRAVITREAL INJECTIONS

To detect and quantify vitreous contamination after intravitreal injection using an experimental vitreous contamination model. Enucleated porcine eyes served as a Type 1 experimental vitreous contamination model with fluoresbrite carboxylate microspheres applied to the conjunctival surface. Saline solution (0.05 mL) was injected using a 27-, 30-, or 32-gauge (G) needle. Injection procedures were monitored using an intraocular fiber catheter. Condensed microspheres were applied to an excised sheet of porcine sclera (Type 2 experimental vitreous contamination model). Saline solution (0.05 mL) was injected from the top of an applied condensed microsphere through the sclera using a needle of one of the aforementioned gauges, and samples were then collected. The fluorescence strength of samples was measured using fluorophotometry. We visually detected fluorescent microspheres in 10/10, 9/10, and 9/10 eyes injected with 27-G, 30-G, and 32-G needles, respectively. In the experimental quantification study, values at all needle gauges were significantly higher than those of controls (P < 0.01). Fluorescence strength was significantly higher in the 27-G group than in the 30- (P < 0.01) and 32-G (P < 0.01) groups. Intravitreal injection carries the risk of introducing contamination directly into the eyes even when a 32-G needle is used. Furthermore, the 27-G needle carries the highest contamination risk.

Endoscopic high-resolution autofluorescence imaging and OCT of pulmonary vascular networks.

High-resolution imaging from within airways may allow new methods for studying lung disease. In this work, we report an endoscopic imaging system capable of high-resolution autofluorescence imaging (AFI) and optical coherence tomography (OCT) in peripheral airways using a 0.9 mm diameter double-clad fiber (DCF) catheter. In this system, AFI excitation light is coupled into the core of the DCF, enabling tightly focused excitation light while maintaining efficient collection of autofluorescence emission through the large diameter inner cladding of the DCF. We demonstrate the ability of this imaging system to visualize pulmonary vasculature as small as 12 μm in vivo.

Metal‐Organic‐Framework‐Coated Optical Fibers as Light‐Triggered Drug Delivery Vehicles

Physical delivery of anticancer drugs in controlled anatomic locations can complement the advances being made in chemo‐selective therapies. To this end, an optical fiber catheter is coated in a thin layer of metal organic framework UiO‐66 and the anticancer drug 5‐Fluorouracil (5‐FU) is deposited within the pores. Delivery of light of appropriate wavelength through the fiber catheter is found to trigger the release of 5‐FU on demand, offering a new route to localized drug administration. The system exhibits great potential with as much as 110 × 10−6 m of 5‐FU delivered within 1 min from one fiber.

Intraprostatic ethanol diffusion: comparison of two injection methods using ex vivo human prostates.

Intraprostatic injection of ethanol has been previously tested in clinical trials as a potential treatment of BPH, with variable outcomes. As evident from animal studies, the inconsistency was owing to various degrees of ethanol backflow along the needle tract. In acute canine experiments, we previously documented that using convection enhanced delivery (CED) eliminates backflow and improves ethanol distribution. The goal of this study was to compare the diffusion pattern between a microporous hollow fiber catheter (MiHFC) and a standard needle in human prostates from organ donors. Prostates were harvested from cadaveric organ donors immediately after removal of organs for transplant. After trimming off excess fat and weighing, prostates were injected with absolute ethanol. The total injected volume was 25% of the calculated prostate volume. One lateral lobe was injected using a single lumen 21-gauge control needle. The contralateral lobe was injected with the same volume but using a MiHFC. Immediately after injection, prostates were fixed en bloc in 10% neutral-buffered formalin, and then sectioned. Three-dimensional reconstruction was performed to determine lesion volume based on hematoxylin- and eosin-stained cross-sections. Three fresh human prostates were harvested and injected. The time from harvest to intraprostatic injection was 15-35 min. The lesion created by the MiHFC was 1.14±0.52 cm(3), whereas that from the control needle was 0.28±0.10 cm(3) (P=0.038). No backflow was observed along the needle tract of the MiHFC. This study shows that freshly harvested human prostates can be used to evaluate new treatments using intraprostatic injection. Similar to in vivo canine experiments, the ethanol lesion sizes were significantly bigger with the use of a MiHFC when compared with a standard single lumen needle.

Ex vivo catheter-based imaging of coronary atherosclerosis using multimodality OCT and NIRAF excited at 633 nm.

While optical coherence tomography (OCT) has been shown to be capable of imaging coronary plaque microstructure, additional chemical/molecular information may be needed in order to determine which lesions are at risk of causing an acute coronary event. In this study, we used a recently developed imaging system and double-clad fiber (DCF) catheter capable of simultaneously acquiring both OCT and red excited near-infrared autofluorescence (NIRAF) images (excitation: 633 nm, emission: 680nm to 900nm). We found that NIRAF is elevated in lesions that contain necrotic core - a feature that is critical for vulnerable plaque diagnosis and that is not readily discriminated by OCT alone. We first utilized a DCF ball lens probe and a bench top setup to acquire en face NIRAF images of aortic plaques ex vivo (n = 20). In addition, we used the OCT-NIRAF system and fully assembled catheters to acquire multimodality images from human coronary arteries (n = 15) prosected from human cadaver hearts (n = 5). Comparison of these images with corresponding histology demonstrated that necrotic core plaques exhibited significantly higher NIRAF intensity than other plaque types. These results suggest that multimodality intracoronary OCT-NIRAF imaging technology may be used in the future to provide improved characterization of coronary artery disease in human patients.

Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis.

When microdialysis (MD) membrane exceeds molecular weight cut-off (MWCO) of 100 kDa, the fluid mechanics are in the ultrafiltration regime. Consequently, fluidic mass transport of macromolecules in the perfusate over the membrane may reduce the biological relevance of the sampling and cause an inflammatory response in the test subject. Therefore, a method to investigate the molecular transport of high MWCO MD is presented. An in vitro test chamber was fabricated to facilitate the fluorescent imaging of the MD sampling process, using fluoresceinylisothiocyanate (FITC) dextran and fluorescence microscopy. Qualitative studies on dextran behavior inside and outside the membrane were performed. Semiquantitative results showed clear dextran leakage from both 40 and 250 kDa dextran when 100 kDa MWCO membranes were used. Dextran 40 kDa leaked out with an order of magnitude higher concentration and the leakage pattern resembled more of a convective flow pattern compared with dextran 250 kDa, where the leakage pattern was more diffusion based. No leakage was observed when dextran 500 kDa was used as a colloid osmotic agent. The results in this study suggest that fluorescence imaging could be used as a method for qualitative and semiquantitative molecular transport and fluid dynamics studies of MD membranes and other hollow fiber catheter membranes.

Endovenous laser ablation for varicose veins: towards a personalized energy dose

Background: Endovenous laser ablation is a minimally invasive procedure in the treatment of great saphenous vein insufficiency. Procedural criteria (energy delivered according to the selected fluence) could affect outcome after treatment, potentially improving the success rate and reduc ing complications. However, the optimal values of the required energy per unit volume are not known, but on the basis of clinical experience, a range of optimal speed of retraction of the laser fiber catheter should exist and strictly depend on the actual vein dimensions. Methods: The study population included 21 patients. The equipment was a Diomed 30W ® laser, wavelength 810 nm. Before treatment, three segments of the great saphenous vein were mapped and their diameter measured and recorded. The energy delivered to each segment was recorded as well as its relationship with vein diameter being evaluated for each vein segment. Results: A 100% success rate was observed at 12-month follow-up assessment, the discomfort complaint 1 week after endovenous laser ablation by 19% of patients was always low (2 or 3 on a scale of pain of 10). On the basis of the actual result, which greatly improves our previous clinical experience, a range of effective values of speed of retraction of the laser fiber catheter (and of the energy per unit volume) is assessed, which strictly depends on the diameter of each segment of the vein. Conclusion: The speed of retraction of the laser fiber catheter should be properly tailored, in order to deliver the right energy dose depending on the actual vein diameter. A real-time procedure can be easily performed using a simple mathematical nomogram.

Adipose-Derived Stem Cells with the Control Release Vegf Polylactic Acid Fiber Catheters Gelatin Scaffold for Tissue Engineering

ABSTRACT Aim: The major obstacles of autologous fat grafting after surgery for breast cancer were low graft survival and high resorption rate. The purpose of this study was to explore adipose-derived stem cells with a new scaffold could control release vascular endothelial growth factor (VEGF) to promote transplant survival and neovascularization. Methods: Polylactic acid fiber catheters loaded with VEGF were included in a gelatin scaffold produced by freeze crosslinking. The release dose and persistence of VEGF from the tridimensional structures were determined using the enzyme-linked immunosorbent assay (ELISA). Human adipose-derived stem cells (hASCs) were extracted and expanded ex vivo, seeded to the scaffold and cultured to test the biocompatibility using the WST-1 assay. Three days after co-cultured with hASCs, the scaffolds were transplanted to the back of nude mice, the control groups were only inject hASCs, transplanted control scaffold with hASCs. Three months later, transplants volume and histology were evaluated and neovascularization was determined by the quantity of capillary and the positive of endothelial cell marker CD31 in immunohistochemistry. Results: The tridimensional structures could release VEGF stable and durable, which had no significant cytotoxicity on hASCs. The transplants volume and the capillary quantity of hASCs with the control release VEGF polylactic acid fiber catheters gelatin scaffold group was significantly larger than other two groups. Immunohistochemistry analysis revealed the transplants were rich in CD31-positive cells. Conclusions: Adipose-derived stem cells together with the control release VEGF polylactic acid fiber catheters gelatin scaffold could significantly promoted vasculogenesis and reduced absorption and necrosis after transplant. Disclosure: All authors have declared no conflicts of interest.

In vivo monitoring of glial scar proliferation on chronically implanted neural electrodes by fiber optical coherence tomography.

In neural prosthetics and stereotactic neurosurgery, intracortical electrodes are often utilized for delivering therapeutic electrical pulses, and recording neural electrophysiological signals. Unfortunately, neuroinflammation impairs the neuron-electrode-interface by developing a compact glial encapsulation around the implants in long term. At present, analyzing this immune reaction is only feasible with post-mortem histology; currently no means for specific in vivo monitoring exist and most applicable imaging modalities can not provide information in deep brain regions. Optical coherence tomography (OCT) is a well established imaging modality for in vivo studies, providing cellular resolution and up to 1.2 mm imaging depth in brain tissue. A fiber based spectral domain OCT was shown to be capable of minimally invasive brain imaging. In the present study, we propose to use a fiber based spectral domain OCT to monitor the progression of the tissue's immune response through scar encapsulation progress in a rat animal model. A fine fiber catheter was implanted in rat brain together with a flexible polyimide microelectrode in sight both of which acts as a foreign body and induces the brain tissue immune reaction. OCT signals were collected from animals up to 12 weeks after implantation and thus gliotic scarring in vivo monitored for that time. Preliminary data showed a significant enhancement of the OCT backscattering signal during the first 3 weeks after implantation, and increased attenuation factor of the sampled tissue due to the glial scar formation.

Optical coherence tomography to reveal vascular lesions after catheter-based renal nerve ablation with a novel multi-electrode EnligHTNTM system

A 72-year-old female with a history of sleep apnoea syndrome was referred to the Andreas Gruentzig Catheterisation Laboratories for catheter-based renal nerve ablation (RNA) due to drug-resistant, uncontrolled hypertension. After intravenously loading with aspirin, the RNA was obtained using the first generation multi-electrode EnligHTNTM system (St. Jude Medical, Westford, MA, USA) delivering 8 ablation runs on both the left and the right renal artery. Before and after the RNA procedure, optical coherence tomography (OCT) was performed using the C7-XR imaging system (LightLab Imaging, Inc., Westford, MA, USA) with a non-occlusive technique and a single-mode optical fibre catheter (frequency domain-OCT-catheter, DragonFlyTM, St. Jude Medical, Westford, MA, USA). The OCT catheter was advanced over a standard 0.014’’ angioplasty guidewire using a monorail lumen at the tip. To optimise pullback recordings, renal arteries were flashed of blood with Ultravist 300 (Bayer House, Berkshire, United Kingdom) at a flow rate of 8.0 mL/s and the application of an automated pullback speed of 20 mm/s. The post-procedural pullback visualised local oedemas (Fig. 1A, B) concomitant with significant thrombi formations (Fig. 1A, C) and small disruptions (Fig. 1D, arrow). The clinical course was uneventful and the patient was discharged home on the second day of hospitalisation. Catheter-based RNA has been recently approved for the treatment of resistant hypertension. During the RNA procedure, transmural lesions are delivered along the walls of the renal arteries to disrupt the sympathetic nerve network located within the arterial adventitia. Here, we report a case in which OCT was performed to reveal potential periprocedural vascular side effects. The RNA was obtained using a novel EnligHTNTM catheter delivering a basket with 4 radiopaque electrodes (Fig. 1E, inset). The design of the EnligHTNTM system enabled simultaneous ablation runs, minimising catheter manipulation (Fig. 1E, arrows). However, the performance of OCT revealed several local lesions including post-ablation oedemas, thrombi formations and tissue disruptions. OCT provides novel insights on vascular effects of RNA, suggesting the potential need for double antiplatelet therapy before the procedure. However, the safety and efficacy of the new catheter-based RNA devices require soon to be evaluated in greater detail.

GafChromic RTQA Film을 이용한 광역학적 치료용 레이저의 선질 측정

Abstract: Purpose: The purposes of this study were to measure the dose distribution of Photodynamic ther-apy(PDT) laser with 635 nm wavelength using GafChromic film. Method & Result: We made each output 300 J bychanging mW and sec using the laser beam radiation mode such as C.W(Continuous Wave) mode, Pulse mode andBurst Pulse mode and measured the does at 0 mm and 5 mm of distance from optic fiber catheter end to the film,and at 5 mm distance by changing the angle of the end of the optic fiber catheter as 0 o and 0.5 o . The radiated filmwas scanned and OD(Optical Density) was compared. And two-dimensional isodose curves were obtained and theconsistency of shapes was compared. It was confirmed that there was consistency between optic density and thedose radiated on the film when we radiated GafChromic film by changing distance and angle of 300 J output in eachradiation mode coordinating mW and sec. Conclusion: In this study, we could identify the stability according tochanges in laser beam modes, changes in output according to distance, changes in uniformity according to angle, andbeam profiles using GafChromic film, and we could also get two-dimensional isodose curve. It was found that smallchange in the distance and angle that is made when optic fiber catheter was contacted on the treatment area did notmake big effects on the output of beam and the uniformity of dose, and it was also found that GafChromic film couldbe utilized for the purpose of QA of PDT laser beam.Key words: GafChromic film, change in radiation mode, beam profile, two-dimensional isodose curve

In vivo feasibility of endovascular Doppler optical coherence tomography

Feasibility of detecting intravascular flow using a catheter based endovascular optical coherence tomography (OCT) system is demonstrated in a porcine carotid model in vivo. The effects of A-line density, radial distance, signal-to-noise ratio, non-uniform rotational distortion (NURD), phase stability of the swept wavelength laser and interferometer system on Doppler shift detection limit were investigated in stationary and flow phantoms. Techniques for NURD induced phase shift artifact removal were developed by tracking the catheter sheath. Detection of high flow velocity (~51 cm/s) present in the porcine carotid artery was obtained by phase unwrapping techniques and compared to numerical simulation, taking into consideration flow profile distortion by the eccentrically positioned imaging catheter. Using diluted blood in saline mixture as clearing agent, simultaneous Doppler OCT imaging of intravascular flow and structural OCT imaging of the carotid artery wall was feasible. To our knowledge, this is the first in vivo demonstration of Doppler imaging and absolute measurement of intravascular flow using a rotating fiber catheter in carotid artery.

Comparison of Intraprostatic Ethanol Diffusion Using a Microporous Hollow Fiber Catheter Versus a Standard Needle

Transurethral intraprostatic ethanol chemoablation of the prostate has shown promising preliminary clinical results for benign prostatic hyperplasia with some variability in clinical outcome. This is likely due to the uneven prostate diffusion caused by varying resistance of the tissue type in which the tip of the needle is embedded. We examined whether the distribution of the injectable in the canine prostate could be improved using a microporous hollow fiber catheter (Twin Star Medical, Minneapolis, Minnesota). The prostate was exposed in 9 mongrel dogs. A single injection of 98% ethanol was delivered in each lobe using a microporous hollow fiber catheter and a standard needle. Prostates were harvested and fixed in 10% formalin. After injection 2.5 mm step sections were obtained and scanned. The ethanol induced tissue lesions were traced on hematoxylin and eosin sections. Three-dimensional reconstructions were created and the volume of each prostate lesion was calculated using stereology. Ethanol induced tissue changes were seen bilaterally in 8 of 9 ethanol injected prostates. In all cases the lesion created by microporous hollow fiber catheter injection was larger than that in the contralateral lobe injected with the control needle. When data were pooled, the hollow fiber catheter injection produced significantly greater tissue changes than the control needle injection (p = 0.03). Improved distribution and absent backflow were seen when using the microporous hollow fiber catheter, supporting its potential as a new method to treat prostate disease.