Neodymium Yttrium Aluminum Garnet Research Articles

Laser Examination as an Additional Nondestructive Method of Ink Differentiation

Abstract Twenty-two black, eight blue, and seven red inks were compared using the reflectance and luminescence mode of the Model J infrared instrument and the Laser Photonics, Inc., neodymium yttrium aluminum garnet (Nd:YAG) laser. These thirty-seven inks were compared from writing produced on Cascade Xerographic paper and Dixon Paper Company safety paper. Results indicate that, in addition to the Model J instrument and other traditional nondestructive examinations, Nd:YAG laser examination in several instances produces different results, adding another feasible link to nondestructive processes commonly used. Further, the outcome of the comparison process was affected significantly on some occasions by the type of paper on which the writing appeared.

Treatment of condylomata acuminata with the Nd-YAG laser

Condyloma acuminatum is a sexually transmitted lesion which is difficult to control since it recurs frequently after conventional treatment. In this study we used a neodymium-yttrium aluminium garnet (Nd-YAG) laser to vaporize extensive and/or recurrent condylomata in 20 patients. Sixteen patients (80%) were cured and remained free of disease after follow-up from ten to 33 months.

The effectiveness of the Nd-YAG laser in destroying superficial bladder tumours

Fifty-five bladder tumours, in 12 patients, were treated by coagulation using the neodymium-yttrium aluminium garnet (Nd-YAG) laser. All the tumours were superficial, grade I or II, and varied in size from 5 to 30 mm. Laser energy was applied using a quartz-fibre delivery system via a rigid cystoscope under general anaesthesia. Up to ten tumours were treated at any one cystoscopy. One patient underwent transurethral resection of tumours larger than 30 mm combined with laser coagulation of smaller lesions.

Bronchial leiomyoma: Report of a case successfully treated by endoscopic neodymium-yttrium aluminum garnet laser

A 40-year-old woman was admitted with dyspnea and episodes of bronchial infection. Leiomyoma of the right lateral basal bronchus was diagnosed and partially removed by a biopsy forceps, and neodymium-yttrium aluminum garnet laser therapy successfully destroyed the rest of this mass.

Neodymium-YAG laser intranasal photocoagulation in hereditary hemorrhagic telangiectasia: an update report.

Hereditary hemorrhagic telangiectasia is a challenging problem for the otolaryngologist since frequent, often severe epistaxis is the major symptom. Options for therapy in the past have included nasal packing, electrocautery, systemic estrogens, septal dermatoplasty, arterial embolization, and arterial ligation. Although successful treatment has been achieved with some of these methods, particularly septal dermatoplasty, other forms of therapy are needed prompting the use of laser photocoagulation. The neodymium yttrium-aluminum-garnet (Nd-YAG) laser was used to treat a group of 19 patients with hereditary hemorrhagic telangiectasia over a 4-year period without complications. Endonasal laser photocoagulation was effective in decreasing epistaxis in patients not requiring frequent transfusions prior to laser therapy. Three patients with the most severe epistaxis received minimal or no benefit from Nd-YAG laser photocoagulation. In most patients Nd-YAG photocoagulation is successful in treating epistaxis associated with hereditary hemorrhagic telangiectasia and should be a therapeutic option for this chronic disease having no available cure.

The use of endoscopic ultrasound and laser photocoagulation in the treatment of gastrointestinal tract tumours: early experience.

In recent years the neodymium yttrium aluminium garnet (Nd:YAG) laser has been used endoscopically to treat inoperable upper and lower gastrointestinal tract tumours. In the oesophagus and gastric cardia, malignant stenoses have been recanalised with a lower complication rate than dilation or intubation and probably with better symptomatic relief (Bown, 1986). In the rectum (and lower sigmoid), bleeding and diarrhoea from tumours have been controlled and stenosis and obstruction have been relieved (Bown et al, 1986). This laser technique is of great value in treating elderly patients, unfit and inappropriate for surgery.

Efficiency and safety of optically modified fiber tips for laser angioplasty

To evaluate the safety and efficiency of optically modified fiber tips, craters were created in human cadaver atherosclerotic arterial walls using sapphire contact probes and lensed fibers connected to a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. Laser energy was emitted at a constant level of 50 J. The sapphire contact probe catheter consisted of a round 2.2 mm diameter synthetic sapphire attached to an 8F catheter into which a 0.2 mm diameter optical fiber was inserted with the distal tip maintained at 3 mm from the sapphire. The lensed fiber catheter consisted of a 0.2 mm optical fiber at the end of which a 1 mm diameter lens was made. The fiber was inserted into a 5F low profile balloon catheter with the lens maintained 3 mm beyond the catheter tip. During laser emissions the catheter tips were maintained in a stationary position in contact with tissue targets immersed in blood at an angle of 90 degrees. The diameter of holes at the entry and exit of craters, the depth of craters and thermal injury to adjacent tissue (rim of carbonization and vacuolization) were measured with microscopy. The volume of tissue removed was derived from these values. Controlled effect index was determined as the ratio of diameter of holes and the extent of thermal injury. Efficiency was determined as the ratio of volume of tissue removed and the energy required to vaporize tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

7 The principles and use of the neodymium-YAG laser in gynaecological surgery

The neodymium-yttrium aluminium garnet (Nd-YAG) laser is one of the most recent surgical instruments to be exploited by gynaecologists. This review discusses the manner in which this laser interacts with tissue compared to other surgical lasers. The safety precautions necessary in using this laser are outlined in view of the potential risk of injury to theatre personnel. This is particularly important with respect to the eye. The most valuable application of the Nd-YAG laser to the gynaecologist is its use in ablating the endometrium in cases of menorrhagia. This technique is successful on account of the coagulating properties of this laser. The endometrium is destroyed to a depth sufficient to ablate the basal layer and bleeding is controlled by the coagulation of vessels. Much of the clinical part of this paper deals with this subject, detailing the choice of patients and the particular risks of the technique and discussing some of the problems. Other uses are outlined. Many of these are equally well treated by other and better-established methods. Undoubtedly the future will see many developments and more applications will become apparent.

Comparison of continuous-wave lasers for endarterectomy of experimental atheromas

The standard surgical lasers, argon ion, neodymium-yttrium aluminum garnet, and carbon dioxide, are often operated as continuous wave lasers with specific uses. Clinical trials of laser therapy for arteriosclerotic cardiovascular disease are underway with all three lasers. Therefore, we compared these three lasers under controlled experimental conditions. A thoracoabdominal exploration was performed in 17 arteriosclerotic rabbits. The aorta was isolated, heparin administered, and multiple endarterectomies were performed in each rabbit with each of the lasers. A line of laser craters was created at the proximal and distal ends of an atheroma. Continuous-wave laser radiation was used to connect the craters and thereby form proximal and distal end points. The plaques were dissected free from the aorta with laser light and the end points were fused by laser. The aortas were removed for light microscopy and the animals were killed. The endarterectomy surfaces and end points were serially sectioned and graded according to light microscopic findings (1 = worst, 4 = best). Argon ion laser endarterectomy (N = 16) required 106 +/- 10 J/cm2. The surface score was 3.5 and end point score 3.4. Neodymium-yttrium aluminum garnet laser endarterectomy (N = 13) required 1,289 +/- 115 J/cm2 with a surface score of 2.4 (p less than 0.001 from argon ion) and an end point score of 1.3 (p less than 0.001 from argon ion). Carbon dioxide laser endarterectomy (N = 9) required 30 +/- 5J/cm2 with a surface score of 2.0 (p less than 0.001 from argon ion) and and end point score of 1.6 (p less than 0.001 from argon ion). Perforation occurred in one of 16 argon ion studies (technical error, not laser), in 11 of 13 neodymium-yttrium aluminum garnet studies, and in six of nine carbon dioxide studies. This study demonstrates that of the currently available clinical continuous-wave lasers, the argon ion laser is superior for endarterectomy of experimental atheromas.

Neodymium‐yag laser photocoagulation of hemangiomas of the head and neck

Hemangiomas of the head and neck region can be a therapeutic challenge depending on their size, flow rate, and location. The neodymium-yttrium aluminum garnet (Nd-YAG) laser was used to treat 16 pediatric and adult patients with cavernous, capillary, and mixed hemangiomas as well as hypertrophic port-wine stains of the head and neck. Low-power energy and intermittent short exposure accomplished photocoagulation with minimal damage to surrounding tissue. Follow-up study in these patients has ranged from 1 to 3 years with excellent results in 14 of 16 patients. Few complications and no major morbidity or mortality occurred. Photocoagulation of hemangiomas of the head and neck using the Nd-YAG laser appears to be an exciting new therapeutic option for this difficult problem. Further clinical study and follow-up appear to be warranted.

Development and experimental application of contact probe catheter for laser angioplasty

A sapphire contact probe laser catheter was developed to increase the dimensions of tunnels created by laser angioplasty. The device consisted of a round sapphire probe (2.2 mm diameter) attached to an 8F catheter into which a 0.2 mm optical fiber was inserted with a tip maintained at 3 mm from the sapphire. The fiber was connected to a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. A saline perfusate was circulated through the catheter during laser emissions to prevent excessive heating of the fiber tip. The system was used in vitro on 16 sections of atherosclerotic calcified human cadaver aortic walls, using diluted blood as a medium, at powers ranging from 10 to 40 W and exposure times from 1 to 4 seconds. Six craters were created at each energy level. The system was also used on six human cadaver, agar-embedded, obstructed iliac and femoral arteries, using 40 W and 2 second laser emissions. Dimensions of probe-created craters were compared with those obtained using bare fibers. The shape of the probe craters was that of a truncated cone with the entry hole wider than the exit, as opposed to the cylindrical shape created with unmodified bare fibers. At 120 J (seconds X watts), areas of entry and exit probe-formed holes were greater than those created with the bare fibers (6.7 +/- 0.5 and 3.4 +/- 0.6 versus 0.2 +/- 0.01 mm2, respectively, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasonic flowmetry and neodymium-yttrium aluminum garnet laser for nephrolithotomy.

Intraoperative Doppler flowmetry was used for localization of the intrarenal arteries. To reduce blood loss during nephrolithotomy, a neodymium-yttrium aluminum garnet (YAG) laser beam was used clinically as a cutting instrument. The combination of intraoperative localization of intrarenal arteries by Doppler flowmetry and cutting through renal parenchyma using the neodymium-YAG laser beam was used in 7 patients with stag-horn calculi or recurrent stones. The average blood loss was only 185 ml. Postoperative renal function was normal. Intravenous pyelograms revealed prompt function and no evidence of contrast extravasation. The data indicate that this technique is effective, diminishes blood loss, and does not impair renal function.

Contact neodymium:YAG laser surgery in gastroenterology. An updated report.

Eighty-eight patients have been successfully treated endoscopically without complications using contact neodymium yttrium aluminum garnet: (YAG) laser probes (endoprobes) for tumors and bleeding and during open surgery (laser scalpel) to perform hepatic and pancreatic resections. The contact probes, made from a synthetic sapphire crystal with its optical properties, geometric design, thermal conductivity, and high melting temperature (2030 degrees C), have proven to be more effective than the current conventional non-contact method of delivering laser energy through a quartz fiber. Advantages include greater precision, sterility, avoidance of the tip melting, and lower neodymium: YAG laser energy required, resulting in reduced tissue damage. The configuration of the probes allows coagulation, cutting, or vaporization, depending on the clinical condition being treated.

Histopathology after Nd-YAG laser percutaneous transluminal angioplasty of peripheral arteries

Laser recanalization of occluded femoral or popliteal arteries was performed in 12 patients using a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. The histologic findings of the laser-irradiated arterial segments in two of these patients are reported. The specimens were obtained 2 and 4 weeks after the laser procedure. The laser-irradiated vessel in Patient 1 had been partially recanalized with reduction of the atherosclerotic occlusion from 3 to 1 cm. The lased arterial lumen manifested thermal injury to the inner quarter of the arterial wall with vacuolization and a rim of carbonization occupying 10% of the width of the arterial wall, but without thrombus formation. Histologic examination in Patient 2 revealed no fibrin deposits, atherosclerotic debris or thrombi at the intimal arterial edge. At the crater site, thermal injury was apparent with vacuolization of the intimal fibrous tissue. The histologic sections obtained 4 weeks after the procedure revealed new fibrous intimal tissue without endothelialization in some of the heavily calcified tissue sections. Where the plaques were noncalcified, reendothelialization was noted with only minimal damage to the surrounding tissue. No medial or elastic fiber disruption was seen, and no aneurysmal dilation had occurred. Intimal splitting with a cleft between the tunica media and the intima was noted at the site of previous balloon angioplasty. In conclusion, the follow-up histologic findings 2 and 4 weeks after laser angioplasty in two patients using a specially designed catheter delivery system and cooling blood perfusate revealed thermal injury to the inner quarter of the arterial vessel wall and no evidence of thrombus formation.

Flammability of endotracheal tubes during Nd-YAG laser application in the airway.

The effects of the neodymium-yttrium aluminum garnet (Nd-YAG) laser on several commonly used endotracheal tubes were examined. Six different types of tubes were tested for flammability. Three tubes were clear, transparent polyvinylchloride with black lettering on the surface. One was yellow-green silicone rubber with green lettering on the surface. One, which was opaque gray with no printing or marks on it, was designed specifically for use with the carbon dioxide (CO2) laser, and one was opaque red rubber with black letters printed on the surface. The latter was tested with and without a wrapping of reflective aluminum tape. On each tube a clear, unmarked area and an area with printing were tested. In each area the tube was impacted by the laser at three to five points. Pulsed and continuous patterns of laser impact were used. Power ranged from 20 to 50 W. The clear polyvinylchloride tubes were not damaged by a pulsed pattern of exposure in unmarked areas. Segments with black printing or marks were consistently damaged. Continuous laser exposure consistently damaged clear portions of the tube. In clear unmarked areas, silicone rubber tubes were damaged with the pulsed pattern when exposure reached 50 W for 1 s. Areas with green lettering were damaged at the lowest level of exposure. Continuous laser exposure at 30 W damaged clear portions of these tubes after 7 s. Opaque red rubber and opaque gray tubes were damaged at the lowest levels of exposure in both clear and marked areas with pulsed and continuous laser emission. A wrapping of reflective aluminum tape offered no protection.(ABSTRACT TRUNCATED AT 250 WORDS)

Indications and technique for endoscopic laser resections in bronchology: A critical analysis based upon 2,284 resections

Over a period of 6 years, we have treated 1,310 patients in 2,284 sessions using a neodymium-yttrium aluminum garnet laser. Indications are more often palliative than curative, with the primary goal to relieve an obstructed airway in a single treatment. The effectiveness of such resections is widely recognized, but indications for such a technique with its limitations deserve emphasis. The use of a rigid bronchoscope is important to provide satisfactory operating conditions and especially to manage hemorrhage rapidly while maintaining a satisfactory airway.

Safety precautions for bronchoscopic Nd-YAG laser surgery.

The application of the neodymium-yttrium aluminum garnet (Nd-YAG) laser in bronchoscopy originated in Europe in 1981 and is now widespread in the United States. Transmissible through flexible fiberoptic quartz fibers and an efficient coagulator of tissue, the Nd-YAG laser deeply penetrates tissue not readily predictable by the endoscopist. Dangers associated with the Nd-YAG laser include complications secondary to inadvertent exposure to normal tissues or structures, tracheobronchial accidents (perforation, hemorrhage, fire), and complications related to anesthetic technique (respiratory depression). Hypoxemia related to persistent hemorrhage, accumulation of secretions or debris or both, or anesthesia-induced respiratory depression is the common denominator of most intraoperative and postoperative complications. Careful selection of patients, intraoperative monitoring of ventilation and blood gases, and techniques of rigid bronchoscopy are stressed to avoid complications.

Nd-YAG laser fusion of human atheromatous plaque-arterial wall separations in vitro

The hypothesis that thermal fusion of disrupted layers of atheromatous arterial wall can be achieved with a neodymium-yttrium aluminum garnet (Nd-YAG) laser was tested. Fresh postmortem human atheromatous plaque was separated from the underlying arterial wall to simulate a dissection in 1-cm 2 arterial wall sections. With the plaque and underlying arterial wall subsequently compressed between glass slides, 17 W of continuous-wave Nd-YAG laser radiation were delivered through an optical fiber to the luminal surface of the plaque over a 4-mm 2 area. Fusion of the plaque to the underlying arterial wall invariably occurred when tissue compression was applied during lasing and a thin blood film was present between the tissues. The load supported by tissue welds depended on plaque thickness, plaque composition, and exposure duration and was as great as 25 g. In postmortem, blood-filled, whole-artery segments, in which plaque had been completely separated from the media, this technique was applied intraluminally during angioplasty with a prototype balloon catheter. Lateral dispersion of Nd-YAG radiation from the termination of an optical fiber within the balloon allowed fusion of plaque to the underlying arterial wall during balloon inflation to 2 atm. Histologic examination of laser-treated tissues showed coagulation of tissues at the junction between the intimal plaque and media. It is concluded that thermal fusion of separated layers of atheromatous arterial wall can be achieved with Nd-YAG laser irradiation. This concept may be useful in the treatment of arterial dissections.

Palliative treatment of malignant airway obstruction by Nd-YAG laser

Photoresection using the neodymium-yttrium aluminum garnet (Nd-YAG) laser is an accepted modality for the treatment of unresectable symptomatic endobronchial lesions. The safety and efficacy of this technique when performed through a rigid bronchoscope have already been established. Forty-two such photoresection procedures were performed through a flexible fiberoptic bronchoscope at the Cleveland Clinic Foundation. The preoperative workup included sector computed tomography (CT) scanning of the mediastinum and/or magnetic resonance (MR) imaging of the chest. The results indicate that Nd-YAG laser photoresection can be safely performed using the flexible bronchoscope. Anatomic information provided by MR and sector CT may add to the safety of this procedure by allowing avoidance of major vessel perforation.

Histologic changes in rat brain tissue caused by neodymium-yttrium aluminum garnet laser irradiation. II. cerebellum

Histologic changes after neodymium-yttrium aluminum garnet laser irradiation were evaluated in the rat cerebellum. Irradiation of 60 W (corresponds to 45.2 W/mm 2) to the posterior fossa was dangerous even in adult rats, although this value was safe for the rat cerebral hemisphere as previously reported. The histologic changes caused by neodymium-yttrium aluminum garnet laser irradiation were similar to those caused by thermal energies. To the adult rat cerebellum, 45 W (35.2 W/mm 2) can safely be applied. For the further use of the neodymium-yttrium aluminum garnet laser in neurosurgery, our findings should be taken into consideration.