bluuebunny/crossref_metadata_2025 huggingface dataset:
Ablation of endometriotic implants in rabbits by hematoporphyrin derivative photoradiation therapy using the gold vapor laser
Authors: Petrucco Oswald M. , Sathananden Muttukrishna , Petrucco Michael F. , Knowles Simon , McKenzie Lorraine , Forbes Ian J. , Cowled Prudence A. , Keye William E.
Published: March 2007

In a rabbit model, endometriotic lesions were utilized to study hematoporphyrin derivative (HPD) uptake and the effect of photoradiation using the gold vapor laser. Morphological studies confirmed successful induction of ectopic endometrial growth and the lesions displayed preferential HPD uptake compared to normal intraperitoneal structures. Gold vapor laser irradiation of the lesions in HPD pretreated animals produced necrosis of the endometriotic lesions leaving surrounding tissues healthy. Results from this study suggest that HPD‐mediated photodynamic therapy may be a suitable means of treating endometriosis in the human.
Dihematoporphyrin Ether‐Induced photosensitivity in laryngeal papilloma patients
Authors: Mullooly Virginia M. , Abramson Allan L. , Shikowitz Mark J.
Published: March 2007

Twenty‐six patients with recurrent laryngeal papillomatosis received 2.5 mg/kg of Dihematoporphyrin Ether (DHE) intravenously prior to photodynamic therapy. All patients experienced some degree of photosensitivity, the only known side effect of DHE.

Reported reactions included mild erythema and inflammation (88%), swelling (58%), blistering (23%), ocular discomfort (61.5%), pruritus (38%), and skin hyperpigmentation (46%). Length of sensitivity ranged from 4–17 weeks, with an average duration of 9 weeks. No long‐term debilitating sequelae were noted.

Degree of skin reaction mainly depended on how compliant the patient was in following precaution instructions. Although restrictive precautions were often difficult to strictly adhere to, most patients felt the potential benefits of the therapy far out‐weighed any inconvenience.
Infrared absorption spectra ranging from 2.5 to 10 μm at various layers of human normal abdominal aorta and fibrofatty atheroma in vitro
Authors: Arai Tsunenori , Mizuno Kyoichi , Fujikawa Akira , Nakagawa Masato , Kikuchi Makoto
Published: March 2007

The infrared absorption spectra ranging from 2.5 to 10 μm in wavelength at various layers of both the human normal abdominal aorta wall and the fibrofatty atheroma were measured by conventional transmission spectrophotometry. Optical specimens 7 μm in thickness were prepared using a cold microtome. Pathological examination was simultaneously performed to identify tissue type of the optical specimen. We found that the presence of characteristic absorption peaks at 5.75 and 3.4 μm was restricted to the atheromatous (fibrofatty) layer of the aorta wall. These peaks may be attributed to the accumulated cholesterol deposits. We also discovered that the normal media layer had strong absorption at 6.05 μm. The discrimination between normal media, fibrofatty atheroma, and aged intimal tissue was made possible by the normalized peak ratio which was based on the ratio of the 5.75‐and 6.05‐μm absorption peaks. These results may be significant for selective laser ablation of atheromatous tissue, as well as tissue diagnosis, to prevent artery perforation during laser angioplastic procedures.
Dependence of the XeCl laser cut rate of plaque on the degree of calcification, laser fluence, and optical pulse duration
Authors: Taylor Rod S. , Higginson Lyall A. J. , Leopold Kurt E.
Published: March 2007

A XeCl laser with an optical pulse duration of 35 ns was used to determine the cut depth per laser pulse of postmortem human aorta as a function of laser fluence for four main categories of plaque development. The data indicate that the cut depth per pulse progressively decreases as the degree of calcification increases even at very high (100 mJ/mm2) laser fluences. A comparison was made between the XeCl laser cut rate data obtained using the 35‐ns duration laser pulses to data obtained using 200‐ns duration pulses for each of the four plaque types. As the degree of tissue calcification increased higher XeCl laser fluences were required for the long pulse case to achieve the same cut depth per pulse as that observed using the shorter pulse duration.
Laser assisted fixation of ear prostheses after stapedectomy
Authors: Schlenk Erwin , Profeta Glen , Nelson J. Stuart , Andrews Jeffrey J. , Berns Michael W.
Published: March 2007

Three different lasers (erbium:YAG, holmium:YAG, alexandrite) were used to drill a hole at the end of the long process of the incus in order to fix an ear prosthesis after stapedectomy or small fenestra stapedectomy. The energy was coupled into a 250‐pm core diameter zirconium‐fluoride fiber. The operations were carried out on human temporal bone models from cadavers. The fiber was guided to the incus under the stereoscopic surgical microscope. The tissue response was examined under the scanning electron microscope, and after decalcification, histologi‐cally. These studies suggest the feasibility of using the erbium: YAG laser to improve the anchorage of the prosthesis on the incus and to increase the stability in ossicular chain reconstruction.
Laser‐irradiation‐induced relaxation of blood vessels in vivo
Authors: Gourgouliatos Zafirios F. , Welch Ashley J. , Diller Kenneth R. , Aggrwal Shanti J.
Published: March 2007

The response of blood vessels to laser irradiation invivo was studied in the dorsal skin flan glass window chamber model of hamsters. The vasodialatory response of venules was critically dependent on the wavelength of irradiating lasser. Relaxation was not produced in arterioles, althought it was tried repeatedly. Vessels were irradiated with the 514.5 nm single line argon laser with irradiances from 1 to 10 W/cm2 on a 1.2 mm‐diameter spot. Irradiation of venules with 2.2 W/cm2 and 4.25 W/cm2 produced reversible relaxation. Venules relaxed initially and after the interruption of irradiation returned to their orginal diameter. At higher irradiances (8.5 W/cm2) an irreversible relaxation was observed. At irradiances of 10 W/cm2 and above initial relaxation was accompanied with constriction, focal coaguli, and hemostasis. irradiation with the argon‐pumed dye laser at 595 nm did not produce any significant relaxation.
Nd:YAG‐laser in the microsurgery of frontobasal meningiomas
Authors: Waidhauser Erich , Beck Oskar J. , Oeckler Reinhardt C. T.
Published: March 2007

Forty‐three patients with big frontobasal meningiomas underwent a microsurgical removal of the tumor. The 1.32μm Nd: YAG‐laser has proved useful in this prospective series particularly with the contactless shrinkage of the tumors and the necrotization of the dural and bony attachments. Tumor shrinkage was achieved by radiating the tumor surface with the Nd: YAG‐loaser. This technique facilitated the microsurgical dissection and reduced the blood loos by half. The Nd: YAG‐laser necrotization of the dural and bony attachments reduced the recurrence rate following grade two resections from 20% to zero. The postoperative quality of life was excellent with a complete rehabilitation in 76% of the patients. The use of the 1.32 μm Nd:YAG‐laser improved significantly the results of microsurgery for frontobasal meningioma.
CO2‐welded venous anastomosis: Enhancement of weld strength with heterologous fibrin glue
Authors: Cikrit Dolores F. , Dalsing Michael C. , Weinstein Todd S. , Palmer Kevin , Lalka Stephen G. , Unthank Joseph L.
Published: March 2007

The milliwatt CO2 laser was used to perform end‐to‐end anastomoses in canine jugular veins. There was a high disruption rate (50%) in laser‐welded veins (n = 10). Fibrin glue (n = 17), formed from human fresh‐frozen plasma, enhanced the weld strength decreasing the disruption rate (18%), resulting in an 82% patency which nearly equaled the contralateral sutured vein patency (93%). The bursting strength was improved with fibrin glue. Transmural necrosis was present initially in all groups but extended for a longer distance in the vessel wall in laser‐welded anastomoses. Sutured anastomoses exhibited a greater inflammatory response. In laser‐welded anastomoses endothelial cells were not as confluent as in sutured anastomoses by six weeks.

Carbon dioxide laser‐welded end‐to‐end vein anastomoses appear to be impractical because they disrupt too easily. However, the addition of heterologous fibrin glue to the weld results in a reasonably strong anastomosis with histologic properties that may be beneficial in vein bypass grafts.
New instruments for laser surgery
Authors: Lanzafame Raymond J.
Published: March 2007

New instruments to facilitate laser operations are presented. These devices are based on the Kocher bronchocoele sound and are useful as dissecting tools and optical backstops to prevent iatrogenic injury.
Direct CO2 laser “revascularization” of the myocardium
Authors: Landreneau Rodney , Nawarawong Weerachai , Laughlin Harold , Ripperger Joseph , Brown Olen , McDaniel Wayne , McKown Daniel , Curtis Jack
Published: March 2007

Evidence of regional myocardial perfusion and contractile function after direct CO2 laser myocardial revascularization (DLR) is lacking. We examined myocardial segment shortening, adenine nucleotide concentrations, and regional blood flow after DLR of the left anterior descending coronary artery (LAD) distribution before and after its proximal ligation in seven anesthetized conditioned dogs. Sonomicrometry assessed myocardial fiber shortening and radioactive microspheres were used to estimate baseline regional blood flows. Cardiopulmonary bypass was followed by cardioplegia arrest. Laser channels (1 mm diameter) were made every 3 to 5 mm in the LAD region with an 80 watt Lasersonics CO2 unit. Bypass was terminated, the LAD occluded, and parameters reassessed. Core samples of myocardium from the lased LAD and control circumflex area were taken to assess adenine nucleotides. After occlusion, LAD distribution blood flow and myocardial shortening were reduced to pre‐lasing ischemic controls. Adenine nucleotides were reduced in the LAD region relative to the control CMX area. DLR cannot be relied upon to acutely revascularize the ischemic myocardium.
Laser‐induced photoacoustic injury of skin: Effect of inertial confinement
Authors: Yashima Yutaka , McAuliffe Daniel J. , Jacques Steven L. , Flotte Thomas J.
Published: March 2007

Argon‐fluoride (ArF) excimer laser‐induced acoustic injury was confirmed by ablating the stratum corneum (s.c.) inertially confined by water in vivo. Hairless rats were irradiated through a quartz chamber with flowing distilled water or air and a 2.5 mm aperture. The laser was adjusted to deliver 150 mJ/cm2 at the skin surface for both conditions. Partial and complete ablation of the s.c. was achieved with 12 and 24 pulses, respectively. Immediate damage was assessed by the transmission electron microscopy. Partial ablation of the s.c. through air produced no damage, whereas partial ablation through water damaged skin to a mean depth of 114.5 ± 8.8 μm (±SD). Full thickness ablation of the s.c. through air and water produced damage zones measuring 192.2 ± 16.2 and 293.0 ± 71.6 μm, respectively (P<0.05). The increased depth of damage in the presence of inertial confinement provided by the layer of water strongly supports a photoacoustic mechanism of damage. The damage induced by partial ablation of the s.c. provides evidence that photochemical injury is not a significant factor in the damage at a depth because the retained s.c. acts as a partial barrier to diffusion of photochemical products. Combined with our previous studies, these experiments demonstrate that pressure transients are responsible for the deep damage seen with 193 nm ablation and that photoacoustic effects must be considered when using short‐pulse, high‐peak power lasers.
Generation of “soft x‐rays” by using the free electron laser as a proposed means of diagnosing and treating breast cancer
Authors: Carroll Frank E.
Published: March 2007

The diagnosis and treatment of breast lesions may be markedly enhanced by the use of a unique new source of near‐monochromatic x‐rays.

Concentric beams of near‐monochromatic x‐ray photons may be generated by collision of the free electron laser (FEL) electron beam with the optical beam in an interaction zone that delivers the x‐rays to a shirtsleeve environment.

The absence of Compton scatter and the photoelectric interaction within tissues improves conspicuity of lesions by two to six times. Increased attenuation of x‐rays in malignant vs. normal tissues makes tumors more obvious. K‐edge subtraction allows chemical analysis of tumors in vivo—all at radiation doses that are one‐tenth to one‐fiftieth that delivered by the lowest‐dose mammographic x‐ray technique available. This allows for an increased sensitivity and specificity and permits prediction of histology, negating necessity for biopsies.

Selective bond‐breaking at depth in tissues as well as x‐ray‐activated photodynamic therapy are also being explored.
Excimer‐laser‐induced fluorescence of rabbit cornea: Radiometric measurement through the cornea
Authors: Ediger M. N.
Published: March 2007

The laser‐induced fluorescence spectrum of rabbit cornea irradiated at ablative intensities was measured. This system directly measured the radiant exposure of fluorescence transmitted through the cornea when the anterior surface of the cornea was irradiated by an ArF excimer laser. Evidence of changing spectral characteristics as a function of total laser dose suggests photochemical changes in the cornea may be occurring. Results are compared with previous data of laser‐induced fluorescence in other models and detection schemes.
Autofluorescence of normal and malignant bronchial tissue
Authors: Hung Jaclyn , Lam Stephen , Leriche Jean C. , Palcic Branko
Published: March 2007

In vivo autofluorescence spectra were obtained in 5 patients with carcinoma in situ, 26 patients with invasive tumors, and 1 patient with severe dysplasia. Significant spectral differences were observed between pre‐cancerous, cancerous, and normal bronchial tissues. This difference may afford a method to image and/or detect early lung cancer by using tissue autofluorescence alone.
Photodynamic therapy of the canine peritoneum: Normal tissue response to intraperitoneal and intravenous photofrin followed by 630 nm light
Authors: Tochner Z. , Mitchell J. B. , Hoekstra H. J. , Smith P. , Deluca A. M. , Barnes M. , Harrington F. , Manyak M. , Russo D. , Russo A.
Published: March 2007

A toxicity study was performed in a canine model to explore the feasibility of using intraperitoneal photodynamic therapy for patients with peritoneal carcinomatosis.

Dogs received 1.25 mg/kg Photofrin II both intravenously (48 hours) and intraperitoneally (2 hours) before intraperitoneal light treatment. The entire peritoneal surface was illuminated with 0.57–0.74 J/cm2 of red light (630 nm). Thirteen dogs were treated 4 control and 9 full treatment. Of the fully treated dogs, 5 received a single treatment and 4 received 3 treatments. The dogs were evaluated clinically and pathologically for immediate (4 days) and late (60 days) side effects.

All animals tolerated the treatment without significant morbidity. Postoperative blood tests were normal except for low lymphocyte counts and elevated liver transaminases, both of which normalized rapidly. Histopathologically, there was approximately a 50% incidence of mild inflammatory peritoneal response.

This study provides the basis for a Phase I human trial.
Light dosimetry model for photodynamic therapy treatment planning
Authors: Grossweiner Leonard I.
Published: March 2007

A light dosimetry model for photodynamic therapy is described leading to the dependence of necrosis depth on incident light dose. Semiempirical dosimetry relations are derived for four modes of light delivery. Results for Photofrin® II at 630 nm are summarized in graphical form. Numerical values of the parameters and necrosis depth calculations are compared with literature data.
Potential use of holmium lasers for angioplasty: Evaluation of a new solid‐state laser for ablation of atherosclerotic plaque
Authors: Haase Karl K. , Baumbach Andreas , Wehrmann Manfred , Duda Stefan , Cerullo Giulio , Rückle Benno , Steiger Erwin , Karsch Karl R.
Published: March 2007

Tissue effects of the mid‐IR Holmium laser (emitting at a wave‐length of 2130nm) were evaluated. This wavelength is attractive because it combines high water absorption and easy transmission through standard optical fibres. The laser was pulsed with pulse durations in the range of 100μsec and repetition rates between 2 and 6 Hertz. For all experiments a repetition rate of 2 Hertz was used. The laser beam was coupled into waterfree quartz fibers with core diameters of 200 and 800μm with an efficiency of 70 and 80%, respectively. Ablation of atherosclerotic plaque has been performed at an ablation threshold of 10J/cm2 for the 800μm and 40J/cm2 for the 200μm fibre. Removal of calcified plaque was possible. Ablation efficiency increased in a non‐linear fashion with increasing pulse energies. The ablation rate per pulse was approximately 2mm at energy fluences of 1000J/cm2 for the 200μm fibre and 1.25mm at energy fluences of 70J/cm2 for the 800μm fibre; a further increase in energy densities did not result in higher ablation rates. On macroscopic examination only very limited thermal injury was found in crater adjacent tissue structures. Crater edges were even and did not reveal signs of crater charring or debris in the crater lumen. However, the histologic specimens revealed zones of thermal damage extending 100 up to 1000μm lateral into adjacent tissue. Thermal damage increased with increasing radiant exposures and depended on the medium used.
Recanalization of arterial occlusions with a lensed fiber and a holmium:YAG laser
Authors: White Christopher J. , Ramee Stephen R. , Collins Tyrone J. , Mesa Juan E. , Paulsen Daniel B. , Murgo Joseph P.
Published: March 2007

Laser recanalization of totally occluded swine iliac arteries was performed to assess the safety and efficacy of a lensed fiber laser angioplasty system with a holmium:YAG (2.1 μm) laser. Silica lenses of 1.0 mm, 1.3 mm, and 1.5 mm in diameter attached to the distal end of a 300‐μm diameter silica fiber delivered fluences of 79.5 J/cm2, 31.4 J/cm2, and 25.5 J/cm2, respectively. The pulse duration of the laser was 250 μsec and the repetition rate was 4 Hz. The mean length of the total occlusions was 5.3 ± 2.0 cm (range 0.5 cm to 8.0 cm). Successful recanalization was obtained in 16/16 lesions without angiographic vessel perforation. Angiographically significant residual stenoses (>50%)remained in every case following successful laser recanalization. Histologically there was minimal evidence of thermal or acoustic tissue injury; however, in 4 of 16 arteries there was evidence of deep arterial dissection following laser recanalization. We conclude that this lensed fiber coupled with a holmium:YAG laser is a safe and effective method for crossing total occlusions in the relatively straight iliac arteries of this animal model.
CW laser ablation velocities as a function of absorption in an experimental one‐dimensional tissue model
Authors: Gijsbers Geert H. M. , Selten Frank M. , van Gemert Martin J. C.
Published: March 2007

One‐dimensional continuous‐wave laser tissue ablation models predict that the steady‐state ablation velocity is independent of the optical absorption of the tissue and proportional to laser power density. This theoretical result was tested in an experimental model that approximates the one‐dimensional situation. The model consists of 3 to 4 mm‐diameter polyacrylamide rods irradiated at one end with an argon laser beam with uniform power density. It was found that ablation velocity is indeed independent of the light absorption coefficient in the material and proportional to the incident power density. Analysis of the relation between the experimental velocities and the power density showed that approximately 40% of the incident laser light is reflected or attenuated in the escaping vapors. Furthermore, compared to the actual absorbed laser power, heat loss caused by thermal radiation and convection from the side surface of the rod is considerable during ablation, especially at lower power densities. This heat loss is not present in a true one‐dimensional geometry and creates therefore marked difference between the rod and one‐dimensional geometry. Computations show that in the pre‐ablation stage the heat losses from the rod can be neglected, compared to the absorbed energy. In this case the rod is a very good approximation of the true one‐dimensional situation.
Operative laparoscopy with the Nd:YAG laser in the treatment of endometriosis and pelvic adhesions
Authors: Shirk Gerald J. , Brumsted John R. , Gimpelson Richard J.
Published: March 2007

A multicenter, prospective trial was initiated to test the effectiveness and safety of the Nd:YAG laser equipped with artificial sapphire contact tips for the laparoscopic treatment of pelvic pain. Ninety‐three women were enrolled in the study, 37 with endometriosis alone, 47 with endometriosis complicated by pelvic adhesions, and 9 women with adhesions alone. In over 90% of adhesions and 96% of endometriotic implants the Nd:YAG laser could be delivered to the site and be used to restore normal anatomy. The exception was deep bowel involvement with endometriosis, which was not treated. The majority of women had marked reduction or resolution of their symptoms for up to 12 months postoperatively. We conclude that the use of the Nd:YAG laser is an appropriate method to laparoscopically treat pelvic pain resulting from endometriosis or pelvic adhesions.
Comparison of four laser types for experimental pain stimulation on oral mucosa and hairy skin
Authors: Svensson Peter , Bjerring Peter , Arendt‐Nielsen Lars , Nielsen Jens C. , Kaaber Svend
Published: March 2007

The use of different lasers for stimulation in human experimental pain research has provided a sensitive method for evaluation of thin nerve fiber functions. In this study, sensory and pain thresholds were compared to argon‐, copper vapour‐, Nd:YAG‐, and CO2 laser stimulation on hairy skin and on oral mucosa. The influence on thresholds with respect to laser type, stimulation site, surface colour, and stimulus parameters (laser beam diameter and pulse duration) was investigated. Significant differences in thresholds between the four lasers were found on both surfaces; however, no significant differences existed between thresholds on the skin and on the tongue when the same laser was used. The observations imply that wavelength‐dependent optical properties of the stimulated tissue influence on threshold determinations. Furthermore, the results indicate that temporal and spatial summation mechanisms may exist for laser induced warmth and pain perceptions. Laser stimulation may be a new tool for the investigation of origin and genesis of various orofacial pain syndromes.
Experimental treatment of thrombotic vascular occlusion
Authors: Labs Joseph D. , Caslowitz Pamela L. , White Robert I. , Anderson James H. , Melville Williams G.
Published: March 2007

The role of laser energy in the treatment of thrombotic vascular occlusion was evaluated in two sets of experiments. First, 10 polytetrafluoroethylene grafts were used to replace segments of the superficial femoral arteries in dogs and were thrombosed by distal ligation. Occlusion was maintained for one hour, or for 7, 14, 21, and 28 days in each of two grafts. Patency was restored in all 10 grafts without perforation or anastomotic disruption using a 2 mm hot tip probe powered by an Argon laser. However, increased organization of thrombus related to the duration of occlusion lead to decreased laser channel diameters, and 75% of the 28 day thrombus remained in the graft after recanalization.

The second experiments tested the added benefit of thrombolytic infusion following laser recanalization. Bilateral external iliac artery thrombosis was induced in dogs by operative vessel isolation, de‐endothelialization, and thrombin injection. At 7 days the efficacy of laser‐assisted thrombolysis (LAT) versus enzymatic thrombolysis (ET) alone was compared. Eight vessels underwent ET by urokinase (4000 I. U./min.); 14 vessels were laser recanalized prior to thrombolytic infusion. LAT was performed from a carotid artery approach in 8 vessels (antegrade) and from a femoral artery in 6 vessels (retrograde). In contrast to studies using the hot tip alone, both ET and LAT accomplished complete thrombus removal. However, LAT lead to significant iliac arterial flow in 9 ± 8 min. (antegrade) and 25 ± 8 min. (retrograde) while ET required 109 ± 47 min (p < 0.01). Further, the rate of clot lysis during antegrade LAT was twice that of enzyme infusion without laser recanalization: 14.6 ± 6.2 vs 7.8 ± 1.1 mm3/min.(p < 0.01). LAT, therefore, achieved the treatment objectives: rapid, atraumatic, and complete removal of thrombus from the vasculature.
In vitro production of viable bacteriophage in carbon dioxide and argon laser plumes
Authors: Matchette Stephanie L. , Faaland Robert W. , Royston David D. , Ediger Marwood N.
Published: March 2007

Both CO2 and argon laser ablation of an agar substrate containing high titres of bacteriophage ϕX174 create plumes which disperse viable phage particles. Irradiances at the beam impact site ranged from 73 to 215 W/cm2 for the CO2 laser and from 40 to 227 W/cm2 for the argon laser. To increase the absorption of argon laser radiation, oxidized hemoglobin was added to the target material. Plume‐borne viable phage were observed to be associated with particles large enough to settle out from the plume within 100 mm of the beam impact site. The ratio of the number of dispersed viable phage to the number of viable phage potentially dispersible by a single, 1‐second laser exposure was on the order of 10−6 to 10−5.
Argon laser therapy for perianal Bowen's disease: A case report
Authors: Boynton Kathleen K. , Bjorkman David J.
Published: March 2007

Bowen's disease (intraepithelial squamous cell carcinoma) may occasionally occur in anal canal or perianal region. Surgical excision in this area may result in significant complications and a recurrence rate of 9–19%.

A case of successful treatment of anal and perianal Bowen's disease using argon laser therapy is presented. No acute or chronic complications resulted from laser therapy. Twenty‐eight months after the initial diagnosis the patient is disease free. Laser therapy also provides the potential for repeated treatment of recurrent lesions without significant patient discomfort or inconvenience. Argon laser therapy should be considered as a therapeutic option in the treatment of Bowen's disease.
Water‐jet‐cooled Nd:YAG laser coagulation: Selective destruction of rat liver metastases
Authors: van Hillegersberg Richard , Kort Will J. , Ten Kate Fiebo J. W. , Terpstra Onno T.
Published: March 2007

The photocoagulating properties of the water‐jet‐cooled Nd:YAG laser (1,064 nm) have been studied in a rat tumor model. A colon carcinoma CC531 was implanted in the liver; 20 days after inoculation, laser therapy was performed with 600 J, 850 J, 1,200 J, 1,700 J, or 2,400 J at a power setting of either 10 or 20 W. Liver damage was determined in tissue specimen on day 1 after treatment and by serum levels of alanine aminotransferase and aspartate aminotransferase on day 1 and 2. Tissue specimen of day 36 were used to evaluate tumor remission. Liver function was assessed by antipyrine clearance on day 2. Light microscopic examination on day 1 showed coagulative necrosis up to 10 mm in diameter at 1,700 J and 20 W. At 20 W, liver damage was 22% larger than at 10 W (P = 0.0001). A significant relationship was found between laser energy and liver damage with complete tumor destruction in all animals at 2,400 J. No deterioration in liver function was found. The results of this study show the ability of the water‐jet‐cooled Nd:YAG laser to produce tumor coagulation necrosis with minor liver damage.
New laser delivery device for laparoscopic procedures
Authors: Bhatta Krishna M. , Rattner David W. , Haw Thomas E. , Nishioka Norman S.
Published: March 2007

A new device to facilitate laser delivery and improve mechanical advantage during surgical procedures is described. In the device, a quartz fiber is used to transmit laser energy to a forked metal tip. The utility of the device was assessed in five pigs. In three pigs a laparoscopic cholecystectomy was performed and in two pigs a laparoscopic lymph node dissection was performed. Advantages of the device included reduced smoke, clearer dissection planes, tactile feedback, and excellent mechanical advantage when used for blunt dissection. The device was qualitatively superior to both sculpted tip quartz fibers and electrocautery.
In vivo canine coronary artery laser irradiation: Photodynamic therapy using dihematoporphyrin ether and 632 nm laser. A safety and dose‐response relationship study
Authors: Mackie R. William , Vincent G. Michael , Fox Jolene , Orme Eric C. , Hammond M. Elizabeth H. , Chang‐Zong Cui , Johnson Michael D.
Published: March 2007

This study examined the safety and dose‐response relationships of 632‐nm laser irradiation of photosensitized normal coronary arteries in 27 dogs. Fifteen received 2.5 mg/kg dihematoporphyrin ether (DHE), seven received no sensitizer, and five had coronary instrumentation but no laser (sham laser procedures) at nine coronary sites—four sensitized, five non‐sensitized. Laser energy of 82 to 1,640 J/cm2 was delivered via a 584 μm diffusingtip optical fiber, providing estimated tissue fluences of 20 to 410 J/cm2. Serial electrocardiograms and selective coronary arteriograms were performed up to 1 month post laser irradiation. Histologic examination was performed of all treated sites. Tissue fluences <200 J/cm2 produced no permanent electrocardiographic or angiographic changes; reversible spasm occurred in 2/8 photosensitized‐lased, 0/2 non‐photosensitized‐lased. Minor medial damage occurred in 1/8 sensitized‐lased, 1/2 non‐sensitized‐lased, and 0/9 sham‐lased sites.

At tissue fluences >200 J/cm2 4/7 sensitized‐lased animals died prematurely—one due to immediate and irreversible coronary spasm and Q wave infarction, one due to fibrillation during 48‐hour follow‐up coronary angiography (normal angiograms), two with normal electrocardiograms and angiograms within one day of undetermined death; 0/5 non‐sensitized‐lased animals expired or had coronary spasm; and 3/7 sensitized‐lased and 0/5 non‐sensitized/lased had significant medial to adventitial histologic damage. Coronary irradiation at <200 J/cm2 appears to be safe for photodynamic treatment of atherosclerotic lesions. Pretreatment for coronary spasm is appropriate.
Temperature response of biological materials to pulsed non‐ablative CO2 laser irradiation
Authors: Brugmans Marco J. P. , Kemper Jim , Gijsbers Geert H. M. , van der Meulen Freerk W. , van Gemert Martin J. C.
Published: March 2007

This paper presents surface temperature responses of various tissue phantoms and in vitro and in vivo biological materials in air to non‐ablative pulsed CO2 laser irradiation, measured with a thermocamera. We studied cooling off behavior of the materials after a laser pulse, to come to an understanding of heat accumulation and related thermal damage during (super) pulsed CO2 laser irradiation. The experiments show a very slow decay of temperatures in the longer time regime. This behavior is well predicted by a simple model for one‐dimensional heat flow that considers the CO2 laser radiation as producing a heat flux on the material surface. The critical pulse repetition frequency for which temperature accumulation is sufficiently low is estimated at about 5 Hz. Although we have not investigated the ablative situation, our results suggest that very low pulse frequencies in microsurgical procedures may be recommended.
Histochemical evaluation of the coagulation depth after argon laser impact on a port‐wine stain
Authors: Neumann Reinhard A. , Knobler Robert M. , Leonhartsberger Helmut , Böhler‐Sommeregger Kornelia , Gebhart Walter
Published: March 2007

A two‐step excisional treatment of a port‐wine stain (PWS) on the back of a 43‐yr‐old female patient was performed. Immediately before the first surgical treatment, two corresponding series of argon laser impacts were performed, each on one PWS half. Different laser parameters with irradiances ranging from 95 to 382 W/cm2 and energy fluences ranging from 19 to 114,6 J/cm2 were used. Laser spots on the first part to be excised were biopsied 10 min after laser treatment and prepared for histochemical analysis by staining with nitro blue tetrazolium chloride (NBTC). Reduction of this redox dye by nicotinamide adenine dinucleotide diaphorase (NADH‐diaphorase) leads on frozen tissue sections to an intense blue precipitate. The activity of NADH‐diaphorase subsides immediately upon cell damage. All vital epidermal and dermal cells presented a dense blue granular pigment in their cytoplasm, sparing the nuclei. Laser induced arc‐shaped epidermal and dermal necrosis did not stain, showing a clear demarcation from surrounding vital tissue. The depth of the thermal injury ranged from 0.28 to 0.45 mm; it did not correlate with the chosen fluences. With these penetration depths, the vast majority of PWS vessels was affected. Assessment of the remaining part of the PWS 8 months later yielded blanching of all laser‐treated areas. With the NBTC method, an accurate definition of laser‐induced tissue damage is feasible. It could be shown that the exposure time is the most relevant parameter influencing the penetration depth.
Laser Raman spectrum of calcified human aorta
Authors: Klug Dennis D. , Singleton Donald L. , Walley Virginia M.
Published: March 2007

Raman spectra of highly calcified areas of areas of human aorta were obtained using long wavelength excitation at 740 nm minimize background fluorescence interference. Raman spectra resembling that of hydroxyapatite were obtained for segments of highly calcified aorta that were thawed frozen samples, from which the surface layer had been removed, or were dired. These are the first reported spectra obtained in air or in normal saline solution showing the hydroxyapatite peak in calcified plaque for samples which were untreated except for freezing, which is encouraging for the application of Raman spectroscopy as a method of detection of plaque during laser angioplasty. Spectra obtained from calcified aorta using excitation at 514.5 nm did not show evidence of the hydroxykapatite band because of the severe interference by background fluorescence generated at this wave length.
Detection of calcified atherosclerotic plaque by laser‐induced plasma emission
Authors: Deckelbaum Lawrence I. , Scott John J. , Stetz Mark L. , O'Brien Kenneth M. , Baker Glenn
Published: March 2007

The use of fluorescence spectroscopy to discriminate atherosclerotic from normal tissue is limited by a lower sensitivity for calcified than noncalcified atherosclerotic plaque (65% vs. 93%, respectively). To evaluate plasma emission as a means to detect calcified plaque, 325 normal and atherosclerotic cadaveric aortic sites were irradiated through a 100‐μm silica fiber in blood by a pulsed holmium laser (λ = 2.1 μm, fluence =4 J/mm2). A photo‐diode positioned near the proximal end of the fiber detected plasma emission during a laser pulse. Plasma emission was detected at 0% (0/110) of normal, 0% (0/107) of noncalcified atherosclerotic tissue, and 91% (98/108) of calcified atherosclerotic sites. Spectroscopic analysis confirmed the presence of calcium lines in the plasma emission from calcified atherosclerotic plaque. Although ablative fluences (> 3 J/mm2) were required for plasma generation, a single laser pulse ablated only to a depth of 67 ± 16 μm in normal tissue. In an additional 10 calcified atherosclerotic sites, laser ablation was continued as long as plasma emission was detected. In all cases, plaque ablation was terminated before arterial perforation. Furthermore, the adjunctive use of plasma detection improved the accuracy of fluorescence spectroscopic classification of normal and atherosclerotic tissue. In conclusion, plasma detection has a high sensitivity (91%) and specificity (100%) for calcified atherosclerotic plaque and may be a useful adjunct for laser angioplasty guidance. Furthermore, plasma detection can be implemented both simply and inexpensively.
Comparative study of laser and scalpel nerve transections
Authors: Fligny Isabelle , Wu Justin S. , Samonte Bernadette R. , Fried Marvin P.
Published: March 2007

This investigation was designed to compare standard scalpel transections of the tibial branch of the rat sciatic nerve with those performed using either a milliwatt carbon dioxide (CO2) or a potassium titanyl phosphate (KTP/532) laser. Four transection groups consisted of nerves sectioned with (1) scalpel (control), (2) milliwatt CO2 laser, (3) KTP/532 with microscope attachment, and (4) KTP/532 laser with 400‐n‐m bare fiber. Each laser was used with the same parameters: 10 watts, 0.4‐mm spot size, and continuous‐wave mode. Horseradish peroxidase (HRP) was applied to the proximal stump for 30 min, and the animals were sacrificed 24 h later. Horseradish peroxidase (HRP)‐labeled motoneuron cell bodies in the lumbar spinal cord were then counted. The average numbers of labeled neurons in each group were as follows: group I (n = 14) 518, group II (n = 8) 424, group III (n = 8) 351, and group IV (n = 8) 283. The standard deviations were quite large, however.

When all laser transections were pooled and compared with paired scalpel transections, we found a significant difference, both by the paired t‐test (P = 0.016) and by the Wilcoxon matched‐paired test (P = 0.02). We conclude that laser transection significantly diminishes the number of neurons labeled by the retrograde transport of HRP.
Holmium:YAG laser ablation of human intervertebral disc: Preliminary evaluation
Authors: Gottlob Charles , Kopchok George E. , Peng Shi‐Kaung , Tabbara Marwan , Cavaye Douglas , White Rodney A.
Published: March 2007

Percutaneous discetomy has become a viable alternative in the treatment of herniated intervertebral disc. This study determined the effectiveness of holmium:YAG laser for ablation of human disc tissue. Human cadaveric intervertebral disc was harvested and stored in cold saline‐soaked gauze for evaluation within 24 hr of removal. Using a specially designed apparatus, a 600 μm diameter fiber was advanced perpendicular through the annulus fibrosis at a controlled force of 0.098 Newtons (10 g). Samples were lased in air (n = 17) and in room temperature saline (n = 32). The laser energy was delivered at 5 Hz, 250 μsec pulsewidth, and from 50 mJ/mm2 to 1,100 mJ/mm2 fluence. Three to six holes were lased using identical parameters in each tissue specimen and were evaluated histologically and by morphometric analysis. The maximum zone of thermal necrosis and thermal denaturation occurred at 700–1,100 mJ/mm2; 140 μm and 590μm in air and 80 μm and 730μm in saline, respectively. At fluences between 200 and 700 mJ/mm2, the thermal necrosis ranged from 20 to 60 μm in air and from 10 to 50μm in saline, the zone of denaturation also being less. The holes created with the 600μm fiber were circular in shape, with a mean diameter of 500 μm (n = 3). The etch rates (penetration/pulse) appeared to increase with increasing fluences. In saline, the etch rate ranged from 7 to 53 μm/pulse (r = 0.57, P ≤ 0.10), and, in air, the values ranged from 7 to 65 μm/pulse (r = 0.79, P ≤ 0.03). No tissue ablation occurred at 50 mJ/mm2, suggesting that the ablation threshold lies between 50 and 200 mJ/mm2. This study demonstrates that controlled ablation of human disc tissue can be accomplished with the hol‐mium:YAG laser, the degree of thermal injury being related to the amount of energy delivered.
Correlation between photodynamic efficacy of differing porphyrins and membrane partitioning behavior
Authors: Okunaka Tetsuya , Eckhauser Mark L. , Kato Harubumi , Bomaminio Anthony , Yamamoto Hideki , Aizawa Katsuo , Sarasua Martha M. , Koehler Karl A.
Published: March 2007

The ability of a photosensitizer to partition into membrane is determined by its structure and physical properties. Partitioning behavior can be quantitated as the partition coefficient (Kp) for a particular drug. This property may be an important determinant of cytocidal efficacy in photodynamic therapy. The Kp of five photoactive drugs—13,17‐ditetraammonium protoporphyrin (PH1008), photofrin II (PII), hematoporphyrin (Hp), benzopor‐phyrin derivative monoacid (BPD‐MA), coproporphyrin (Cp), and uroporphyrin (Up)—was determined using a simple liposome system composed of sonicated egg phosphatidylcholine single bi‐layer vesicles. The cytocidal efficacy of each drug was compared by determining the concentration of drug resulting in 50% maximal lysis (C50) obtained by measuring the hemoglobin absor‐bance at 414 nm released from lysed human red blood cells. The percentage lysis at 1 μM final drug concentration was also determined. An argon‐dye laser was used to administer light of 630‐nm wavelength for a total exposure of 5 J/cm2. Porphyrins with a greater tendency to partition into phosphocholine bilayer membranes demonstrated a greater lytic efficacy in the rbc system utilized. The comparison of physical properties with lytic ability may be useful in understanding the mechanism by which PDT exerts its effects and in predicting the clinical efficacy of different drugs.
Magnetic resonance imaging of interstitial laser photocoagulation in brain
Authors: Tracz Robert A. , Wyman Douglas R. , Little Peter B. , Towner Rheal A. , Stewart Wendy A. , Schatz Stanley W. , Pennock Paul W. , Wilson Brian C.
Published: March 2007

Magnetic resonance (MR) imaging can be used to monitor the development of thermal lesions induced in tissue using interstitial laser photocoagulation (ILP). A potential application for ILP is the treatment of surgically inaccessible brain tumors. For the successful clinical application of MR‐monitored ILP, it is necessary to relate MR images of ILP lesions to the actual induced lesions. In this preliminary study we performed ILP in the normal brains of anesthetized cats by delivering interstitially 1.0, 1.5, and 2.0 W of continuous‐wave Nd:YAG laser energy (1,064 nm) for 1,000 s via a plane‐cut 400 p,m core optical fiber. At 48 h post‐irradiation the lesions consisted of four sharply demarcated concentric zones of thermal damage. Lesion diameter increased linearly with delivered power. T2‐weighted proton spin‐echo images acquired during ILP showed a region of complete or near signal loss that underestimated the actual lesion at 48 h. Gadolinium‐enhanced T1‐weighted spin‐echo images acquired immediately post‐irradiation showed the actual lesion precisely. © 1992 Wiley‐Liss, Inc.
Nd:YAG laser bipolar dissector—preliminary results
Authors: Nishiwaki Yoshiro , Daikuzono Norio , Joffe Stephen N.
Published: March 2007

We have developed a laser bipolar dissector (LBD) which uses the 1,064 nm Nd:YAG wavelength. The laser emits from the inner surface of the distal 7 mm of each probe made of synthetic sapphire. With low laser power (15–25 W), the bipolar provides hemostatic cutting of larger blood vessels. Animal experiments were carried out using New Zealand white rabbits. The LED he‐mostatically cut through veins up to 5 mm and arteries up to 2 mm in diameter. Rebleeding did not occur. Transection of parenchymal organs such as liver and lung was easily performed with complete hemostasis. In chronic experiments a partial hepatectomy with splenectomy and left nephrectomy was performed using the LBD alone without any ligation. Up to 3 weeks postoperatively there were no direct complications related to using the LBD. In conclusion the LBD could perform a hemostatic transection of large vessels and might have clinical application in the dissection of vascular parenchymal organs. © 1992 Wiley‐Liss, Inc.
Nd:YAG laser treatment of colorectal malignancies: An experience of 4 ½ years
Authors: Dittrich K. , Armbruster C. , Hotter F. , Tuchmann A. , Dinstl K.
Published: March 2007

Between 1985 and 1990, 517 patients were treated for colorectal malignancies at our department of surgery. Nd:YAG laser therapy was used in 37 cases (7.1%). The mean age of these 22 men and 15 women was 71.4 years (range: 22–96 years). One hundred‐twenty‐nine Nd:YAG laser treatments were performed. Indications for laser treatment were (1) palliative tumor reduction (n = 21), (2) preresectional laser recanalization for obstructing carcinoma (n = 6), and (3) curative treatment (n = 10). Laser related complications included one perforation of the rectum and one rectovaginal fistula. One fatal pulmonary embolism occurred. After palliative treatment, five patients died because of tumor progression (mean survival time: 16 months), two because of other reasons. All patients with obstructing tumors could be recanalized successfully. After curative treatment, eight patients are still alive without tumor recurrence (mean survival time: 25.5 months), and two died of other causes. Palliative Nd:YAG laser treatment of colorectal malignancies is a competitive alternative to conventional surgery. Recanalization of obstructing tumors is an excellent treatment for large bowel obstruction, making one‐stage resections possible. Curative treatment should be reserved for special cases only. © 1992 Wiley‐Liss, Inc.
Thermal effects in tissues from combined simultaneous coaxial CO2 and Nd:YAG laser beams
Authors: Judy Millard M. , Matthews J. Lester , Goodson J. Rush , Hults Donald F. , Viherkoski Esa , Aronoff Billie L.
Published: March 2007

This study examines the depth of thermal coagulation and charring in swine liver, kidney cortex, tongue (inferior surface), skeletal muscle, inflated lung, and skin resulting from in vivo incision with simultaneous coaxial CO2 and Nd:YAG (1.064 μM) laser beams. At values of 20 w and 40 w, respectively, and at values of 30 w and 60 w, respectively, of combined CO2 and Nd:YAG laser radiation, coagulation depths determined histologically in liver were significantly greater (P<0.01) than in the other tissues and were significantly less in inflated lung (P<0.05) than in other tissues for the larger laser power settings employed. Coagulation depths achieved at 10 w and 20 w, respectively, and at 20 w and 40 w, respectively, of CO2 and Nd:YAG laser power were comparable to those obtained by other workers in liver and other relatively vascular tissues using a contact Nd:YAG laser tip. Charring depths obtained at power settings of 30 w (CO2) and 60 w (Nd:YAG) were greater in liver (P<0.001) than in all other tissues examined. Hemostasis during incision was achieved only for values of the ratio of CO2 to Nd:YAG laser power in the range 2–3 in the more vascular tissues, liver and kidney cortex, whereas hemostasis was achieved also in the lesser vascular tissues at higher values. These results strongly suggest the usefulness of combined simultaneous CO2 and Nd:YAG laser beams in surgery of the more vascular organs and tissues. © 1992 Wiley‐Liss, Inc.
Pathologic changes occurring in the prostate following transurethral laser prostatectomy
Authors: Johnson Douglas E. , Price Roger E. , Cromeens Douglas M.
Published: March 2007

Serial gross and histopathologic examinations of the prostate following transurethral laser prostatectomy in the canine model demonstrated an immediate well‐demarcated sphere of thermal necrosis measuring 2.7 cm in diameter, which, within 24 hours, had begun liquefaction and was showing multiple areas of cavitation. By the end of the 1st week, the areas of cavitation had coalesced to form a central cavity lined by a narrow layer of necrotic tissue clinging to the thin surviving peripheral belt of prostatic glandular parenchyma. At 3 weeks, the bluish‐black discoloration resulting from breakdown of blood in the necrotic tissue had subsided, leaving masses of coagulonecrotic tissue within the central cavity. Within 5 weeks, the ectatic central cavity was lined by transitional epithelium. These postmortem pathologic observations confirm our surgical and clinical impressions of being able to satisfactorily perform an effective transurethral prostatectomy using neodymium:YAG (Nd:YAG) laser photoirradiation. © 1992 Wiley‐Liss, Inc.