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Objective To report the results of a clinical study investigating the diagnosis of malignant and dysplastic bladder lesions by protoporphyrin IX (PPIX) fluorescence and to compare them with those from earlier studies. Patients and methods The study included 55 patients with suspected bladder carcinoma (at initial diagnosis or at tumour follow-up visits); 130 bladder biopsies from 49 patients were classified by pathological analysis. All patients received an intravesical instillation of 50 mL of a 3% 5-aminolaevulinic acid (ALA) solution a mean of 135 min before cystoscopy, which was then performed under white and blue light. Malignant/dysplastic lesions showing red fluorescence under blue-light excitation were noted and the increase in detection rate calculated. Results There were 63 benign and 67 malignant/dysplastic areas biopsied; 10 malignant/dysplastic lesions (four transitional cell carcinoma, two carcinoma in situ, four dysplasia) were not detected during routine white-light cystoscopy but were identified under blue light. Fluorescence cystoscopy improved the overall diagnosis of malignant/dysplastic bladder lesions by 18% over standard white-light cystoscopy. The improvement was greater for dysplastic lesions and carcinoma in situ (50%). However, the improvement over standard cystoscopy was less than that found by other groups. Conclusion The ALA-based fluorescence detection system significantly enhanced the diagnosis of malignant/dysplastic bladder lesions. However, determining the optimum drug exposure time requires further investigation using well-characterized instrumentation and study protocols, which would then allow comparison of the results from different groups.

Wood formation and structure of 3-year-old 35S-rolC transgenic aspen (Populus tremula L. × tremuloides Michx.) were compared with the situation in non-transformed control aspen trees. The transgenics are characterized by reduced shoot growth and an earlier bud break. Their wood formation did not immediately follow bud break and leaf development but occurred after some delay, about the same time as wood formation was initiated in the control trees. Quantitatively, the wood structure of the transgenics and of the non-transformed controls was not significantly different; therefore the dwarfism of the transgenics is very likely due to a reduction in cell number. Atypical formation of latewood led to the assumption that the differentiation of cells is decelerated. Additionally, cells lacked both secondary walls and normal lignification, and discoloration of the wood and the formation of tyloses were conspicuous in all transgenics. In contrast, they did not occur in the non-transformed control aspen trees. The observations are discussed in relation to the widely accepted auxin hypothesis. It is suggested that 35S-rolC transgenic aspen trees may be a useful model to study the regulatory mechanisms of wood formation.

A relatively rapid 3-step fractionation method has been developed for the isolation of human alpha-fetoprotein from culture fluids of HepG2 cells applicable to large volumes. The protein exists as a complex with lipids or lipoproteins but an ethanol precipitation step is effective in separating it. Yields of 50-60% can be obtained from culture fluid containing 30-40 microg/ml. A minor fraction that appears to be a proteolytic product of the AFP is present in the final product.

Autoimmune pancreatitis (AIMP) is a recently described clinical entity causing chronic pancreatitis. It often presents with diffuse enlargement of the pancreas and/or a focal mass at the head of the pancreas causing common bile duct obstruction and jaundice. In most instances, AIMP is mistaken for pancreatic cancer. A number of laboratory abnormalities such as positive antinuclear antibody, hypergammaglobulinemia, and antibody to carbonic anhydrase are often present in these patients. Currently, pancreatic biopsy demonstrating characteristic histopathologic changes is essential to establish the diagnosis. We report the first case of AIMP presenting as a pancreatic tail mass and lower gastrointestinal bleed.

Purpose: We validate the usefulness of laser-induced autofluorescence for the detection of bladder carcinoma.Materials and Methods: We obtained and analyzed fluorescence spectra from 75 patients in whom bladder cancer was suspected. Tissue fluorescence was excited by a nitrogen laser using a quartz optical fiber placed in gentle contact with the area of interest. The laser-induced autofluorescence spectrum was recorded using an intensified optical multichannel analyzer system. Spectra were corrected for the spectral response of the optical system, and the ratios of laser-induced autofluorescence intensities (I) at 385 and 455 nm. (I385/I455) were determined. We had previously established this ratio as a diagnostic algorithm. We included only suspicious bladder lesions (erythematous, edematous, raised and so forth) that were difficult to diagnose by cystoscopy as well as areas from which random biopsies were obtained. The fluorescence ratio algorithm was applied to 130 bladder areas.Results: Of the...

The placebo effect will have a growing importance in the field of nuclear medicine as the potentials for palliative therapy with internal sources are realized. It is important for nuclear medicine physicians and their colleagues to be familiar with the role of placebo responses in clinical trials, especially when such trials involve the subjective assessment of pain. A summary of the literature on the placebo effect in pain studies is presented in which traditional values for placebo responses are contrasted with more current thinking in the field. The few published double-blind studies of pain relief after treatment with radiotherapeutic agents are summarized specifically with respect to their cited placebo response.

Demineralization has been shown to foster osteoinductive properties of cortical bone grafts, yet little is known about the process of demineralization and how to control it. The purpose of this study was to investigate the process of cortical bone demineralization by using scanning electron microscopy to evaluate how hydrochloric acid demineralizes cortical bone. Results showed that in the demineralization of diaphyseal cortical bone specimens using hydrochloric acid, a uniformly thick circumferential band of demineralized bone matrix surrounds an inner undecalcified bone core as the process of demineralization occurs. The interface between the demineralized and mineralized section of the bone specimens was extremely sharp. This interface between demineralized and undemineralized bone was noted to advance as a reaction front with increasing demineralization which resulted in continuous shrinkage of the inner cortical bone core. This study suggests that cortical bone demineralization can be best described using an advancing reaction front theory, and this explanation can be used for implementation of the concept of controlled demineralization.

Purpose: We assessed the ability of laser induced autofluorescence to differentiate malignant from nonmalignant bladder lesions.Materials and Methods: We studied 53 patients with bladder cancer undergoing mucosal biopsies or transurethral resection of a bladder tumor. A quartz optical fiber was advanced through the working channel of a cystoscope and placed in gentle contact with the bladder. Tissue fluorescence was excited by 337 nm. light pulses (nitrogen laser). One fiber was used for transmission of the excitation and emission (fluorescence) light. An optical multichannel analyzer system was used to record fluorescence spectra of the sites of interest.Results: We analyzed the fluorescence spectra of 114 bladder areas (1 carcinoma in situ as well as 28 malignant, 35 inflammatory, 7 dysplastic, 1 squamous metaplastic and 42 normal areas). These lesions included 44 difficult to diagnose suspicious tumors (11 malignant and 33 nonmalignant). We developed an algorithm that used the I385:I455 nm. flu...

We investigated the kinetics of hydrochloric acid demineralization of human cortical bone with the objective of developing a method of controlled demineralization for structural bone allografts. It is known that the demineralization of cortical bone is a diffusion rate limited process with a sharp advancing reaction front. The demineralization kinetics of human cortical bone, described as the advance of the reaction front versus immersion time, were determined by measuring extraction of bone mineral in both planar and cylindrical geometries. Mathematical models based on diffusional mass transfer were developed to predict this process. The experimental data fit well with the behavior predicted by the model. The model for planar geometry is applicable to controlled demineralization of cortical bone allografts of irregular shapes such as cortical struts. The model for cylindrical geometry is appropriate when curved surfaces are involved such as in diaphyseal bone allografts. This method of demineralization has direct application to clinical modification of cortical bone allografts to potentially enhance their osteoinductive properties.

Background and Objective Surgical reconstruction of bony defects in the maxillofacial region involves fixation of bony fragments with mini and micro plates. Bone stabilization during hole drilling is often challenging due to the need to apply pressure when using a conventional mechanical Hall drill. In addition, fragmentation of the fragile bones may occur and complicate the reconstruction. The pulsed Er:YAG laser offers an attractive alternative drilling modality because it does not require physical contact with the bone in order to drill holes, cuts bone with minimal thermal damage, and allows precise control of bone cutting. The objective of this study was to investigate the pulsed Er:YAG laser as an alternative to the mechanical bur by comparing bone healing using both modalities. Study Design/Materials and Methods Bone healing in an inferior border defect of the rat mandible was examined using either an Er:YAG laser or a mechanical but for drilling. The healing of osteotomies in facial bones and of screw holes for plate stabilization of free bone fragments was studied. Results All defects healed by 4 weeks postoperatively. Histologic evaluation demonstrated no difference in the amount of newly formed woven bone at the osteotomy site or screw holes made by either the laser or the drill. The extent of thermal damage at the osteotomy sites was comparable in laser and mechanically cut bone fragments. Conclusions On the basis of this study we suggest that the Er:YAG laser can be used clinically in thin, fragile bones in the maxillofacial region. © 1996 Wiley-Liss, Inc.

Background and Objective To determine the survival of in vitro retinal pigment epithelium (RPE) cells subjected to laser-generated stress transients (shock waves) and compare it to that of other cell lines. Study Design/Materials and Methods Normal and transformed human retinal pigment epithelium cell lines were used. The cells were imbedded in a gel to prevent motion and cavitation and located in a thin layer at the bottom of a pipette tube closed at one end by a polyimide film. Stress transients were generated by pulsed excimer laser (193 nm and 248 nm wavelength) ablation of the polyimide film. Cell survival, compared to that of unirradiated cells, was assessed by counting surviving cells. The stress was varied from 300 to 740 bars and the number of shock wave pulses applied varied from 5 to 150. Results Cell survival decreased sharply at the higher stresses but some cells always survived. The lowest survival rate was 50%. Increasing the number of shock wave pulses did not increase cell killing after 20 pulses, demonstrating a saturation effect. In contrast to the transformed cell line, normal cells could not be killed at the highest stress available to us. Conclusion The susceptibility of RPE cells to damage by stress waves varies with cell line. Transformed retinal pigment epithelium cells are more susceptible than normal ones. Saturation of the damage versus number of pulses is observed and a threshold-like behavior for cell killing versus stress is found. Because at least 50% of the cells survived, normal cell growth can serve to replenish damaged cells. © 1996 Wiley-Liss, Inc.

Massive cortical autografts and allografts have been found to incorporate into host bone very slowly and thus are subject to complications such as fatigue fracture and infection. In order to understand and improve the process of osteogenesis in these types of bone grafts, a new experimental model was developed using bone discs from rat calvaria prepared by demineralization and drilling of 0.5 mm diameter holes with a pulsed, 2.94 microns wavelength Erbium:Yttrium-Aluminum-Garnet laser. Four types of bone discs were analyzed: untreated (Type I), demineralized (Type II), laser-ablated (Type III), and laser-ablated then demineralized (Type IV). The discs were transplanted into a subcutaneous site in adult Sprague-Dawley rats and followed for as long as 6 weeks. Histologic analysis of the discs at weekly intervals with use of hematoxylin and eosin staining confirmed the presence of new bone growth in Type-II and Type-IV discs. The amount of new bone growth in each disc was estimated by determining the mineral x-ray attenuation coefficient, which is proportional to mineral density, from digitized radiographs of the discs. The results showed that the processes of demineralization (P < 0.001) and laser ablation with demineralization (p < 0.05) were both significant in enhancing new bone growth in this model. This study demonstrated that osteoinduction can be fostered in cortical bone through the processes of demineralization and laser ablation. To the extent that laser ablation may allow maintenance of structural integrity while altering the surface geometry in such a way as to promote ingrowth of new bone, this experimental model represents an advance in understanding how osteogenesis in cortical bone grafts might be improved.

Ultraviolet laser-induced fluorescence was examined in vivo to determine whether the technique can reliably distinguish between hyperplastic and adenomatous polyps of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, and 49 adenomatous polyps were recorded in vivo. Polyp type was independently determined by two senior pathologists who were unaware of the fluorescence measurement. A multivariate linear regression analysis was used to differentiate spectra from hyperplastic and adenomatous polyps and resulted in a sensitivity, specificity, predictive value positive, and predictive value negative for identifying adenomatous polyps of 86%, 80%, 86%, and 80%, respectively. These values were not significantly different from the accuracy of routine clinical pathology. Thus, ultraviolet laser-induced fluorescence appears to show promise as a means for distinguishing tissue types. However, further experience is needed before its routine clinical use can be recommended. Significant changes in the fluorescence spectra occurred postmortem, suggesting that future studies of laser-induced fluorescence of colonic tissue must use data acquired in vivo.

The ablation thresholds and patterns of collateral damage in cornea produced by Er:YAG (2.94 microns) and Er:YSGG (2.79 microns) lasers were measured. Two different pulse durations, 200 microseconds (normal spiking mode) and 100 ns (Q-switched mode), were used at both wavelengths. In the normal spiking mode, damage zones of 16 +/- 2 microns and 39 +/- 7 microns and ablation thresholds of 250 +/- 20 mJ/cm2 and 420 +/- 35 mJ/cm2 were measured at 2.94 microns and 2.79 microns, respectively. In the Q-switched mode, damage zones of 4 +/- 2 microns and ablation thresholds of 150 +/- 10 mJ/cm2 were found irrespective of the laser used. The similarity between the results using the Er:YAG and Er:YSGG lasers in the Q-switched mode suggest that either laser can be used with equal effectiveness for corneal trephination.

We investigate shock waves generated by excimer laser ablation of sheet polyimide confined in water. The velocities of the ablation-induced pressure waves in the water are determined by an optical probe system. We measure supersonic velocities up to a few hundred microns away from the irradiated surface, indicating the formation of shock waves. We use these velocities to calculate the corresponding pressures. They are already in the kbar range at fluences comparable to the threshold of ablation. The shock pressure varies as the square root of the incident laser fluence, a behavior that is explained by the rapid heating of the confined gaseous products of ablation. The initially planar shock waves propagate, become spherical, and decay within a few hundred microns in the surrounding water to acoustic waves. During spherical expansion the shock pressure drops as the inverse of the square of the propagation distance. The shock waves generated may be relevant in explaining photoacoustic damage observed in biological tissue after excimer-ablation at corresponding irradiances. They may also be important in material processing applications of excimer laser ablation of polymers as they can lead to plastic deformation.

The dynamics of tissue ablation using an Er:YAG laser were studied using flash photography and optical pump-probe techniques. Both normal-spiking-mode and Q-switched Er:YAG laser radiation were used to study the ablation of skin and bone. Time-resolved photographs of the ablation plume were obtained using a microscope-mounted camera together with pulsed illumination from an excimer-pumped dye laser. The velocity of the plume front, obtained from the photographs, was approximately 1400 m/s. The same velocity was also measured using an optical pump-probe technique. Both techniques indicate that material removal occurred after the end of the 90-ns-long Q-switched laser pulse and that each micropulse in the normal-spiking-mode pulse train was capable of ablating and rapidly ejecting tissue.

The wavelength dependence of the ablation threshold of a variety of tissues has been studied by using a tunable pulsed Co:MgF2 laser to determine how closely it tracks the optical absorption length of water. The Co:MgF2 laser was tuned between 1.81 and 2.14 microns, a wavelength region in which the absorption length varies by a decade. For soft tissues the ablation threshold tracks the optical absorption length; for bone there is little wavelength dependence, consistent with the low water content of bone. Thermal damage vs. wavelength was also studied for cornea and bone. Thermal damage to cornea has a weak wavelength dependence, while that to bone shows little wavelength dependence. Framing-camera pictures of the ablation of both cornea and liver show explosive removal of material, but differ as to the nature of the explosion.

Carcinoma of the mandible is a disease that evokes images of devastating functional and cosmetic outcomes. Most of these malignancies require treatment with surgical resection and perioperative irradiation (XRT). To minimize the incidence of postoperative complications, the timing of perioperative XRT has been questioned. This study reviewed 140 patients at M.D. Anderson Cancer Center over a 7-year period who underwent mandibular resection and reconstruction with a free fibular flap. The patients were divided into the following four groups: (1) preoperative XRT followed by immediate reconstruction, (2) preoperative XRT followed by delayed reconstruction, (3) postoperative XRT, and (4) no XRT. The complications studied included exposure of bone and hardware, orocutaneous fistula, osteoradionecrosis, partial and complete flap loss, and severe cervical contractures. Of the 140 patients studied, 59 (42%) had at least one complication. Complications per group were the following: group 1, 45%; group 2, 46%; group 3, 47%; and group 4, 28%. The results show that the incidence of complications is relatively equal between groups that received preoperative vs. postoperative XRT.

Thermal damage produced by continuous wave (cw) CO2 laser ablation of tissue in vitro was measured for irradiances ranging from 360 W/cm2 to 740 kW/cm2 in order to investigate the extent to which ablative cooling can limit tissue damage. Damage zones thinner than 100 microns were readily produced using single pulses to cut guinea pig skin as well as bovine cornea, aorta, and myocardium. Multiple pulses can lead to increased damage. However, a systematic decrease in damage with irradiance, predicted theoretically by an evaporation model of ablation, was not observed. The damage-zone thickness was approximately constant around the periphery of the cut, consistent with the existence of a liquid layer which stores heat and leads to tissue damage, and with a model of damage and ablation recently proposed by Zweig et al.

Objective. Previous studies have suggested that 5-aminolevulinic acid (ALA) may be used topically on the cervix to allow optical detection of cervical dysplasia, based on the fluorescence of protoporphyrin IX (PpIX) synthesized in situ from ALA. However, the uniformity of distribution of topically applied PpIX and the sensitivity and specificity of detection are not optimal. The current study was undertaken to demonstrate the feasibility of administering ALA by mouth (po) with the hypothesis that systemic administration might provide a more reliable diagnostic tool. Methods. Oral ALA was administered to 14 patients with abnormal Pap smears in a dose- and time-intensity design. Institutional review board approval was obtained. A starting dose of 10 mg/kg of po ALA was administered and colposcopy was performed in 3 patients at 1 h, 3 patients at 2 h, 6 patients at 3 h, and 2 patients at 4 h. The study was written with the intent to increase the dose in 10 mg/kg increments if fluorescence was not detected; however, fluorescence was detected at the first dose level. Liver function tests were checked pre and post ALA and follow-up telephone calls were made regarding possible side effects. Both white and blue light colposcopy examinations were performed by two blinded clinicians and biopsies of all abnormal areas were performed. Results. All patients tolerated po ALA well, with no systemic side effects. At the 10 mg/kg dose there was no reported nausea or photosensitivity. Optimal fluorescence was achieved at the 3-h time point, with quenching noted at the 4-h time point. Excellent absorption was documented with fluorescence of the lip demonstrated with Wood's lamp. In some cases fluorescence correlated with dysplasia on biopsy. Conclusion. 5-ALA given via the po route and at the dose and time period studied is well tolerated and affords fluorescence of the cervix. Future study is needed to demonstrate the successful identification of dysplastic lesions, with the ultimate goal of treating dysplasia of the lower genital tract with 5-ALA and light therapy.

Oral cancer and precancer overexpress the epidermal growth factor receptor (EGFR) and monoclonal antibodies against EGFR coupled to photoactive dyes may have a potential both as a diagnostic and treatment modalities for oral premalignancy. We asked whether an anti-EGFR mab (C225) conjugated with the fluorescence dye indocyanine Cy5.5 could detect dysplastic changes in the hamster cheek pouch carcinogenesis model. Secondly, we tested whether the same antibody conjugated with the photosensitizer chlorin (e6) could be used together with illumination to reduce levels of expression of EGFR as evaluated by the immunophotodetection procedure. Increased fluorescence appeared to correlate with development of premalignancy when the C225-Cy5.5 conjugate was used. Areas with increased fluorescence signal were found in carcinogen-treated but clinically normal cheek pouches, that revealed dysplastsic changes by histology. The immunophotodetection procedure was carried out after photoummunotherapy with the C225-ce6 conjugate, and showed a significant reduction in fluorescence in the illuminated compared to the non-illuminated areas in the carcinogen- treated but not the normal cheek pouch. The results demonstrate that the use of anti-EGFR Mab targeted photoactive dyes may serve as a feedback controlled optical diagnosis and therapy procedure for oral premalignant lesions.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optical engineering and imaging technology have played a major role in the evolving field of minimally invasive surgery (MIS) by making it possible to visualize the manipulation of tissue at remote internal sites. We assess and review the optical imaging technology used during a variety of MIS procedures from an engineering perspective. The field of MIS is evolving rapidly. Optic-based technologies have the potential to further improve diagnostic capabilities of MIS. Optical imaging technologies and instrument designs are discussed in relation to their current and future use in MIS procedures. Technical limitations in imaging technology are described, along with potential solutions. We review the current status and future role of optical imaging technology in MIS. In the future, synergistic benefits from engineering, imaging technology, and MIS are likely to improve diagnostic ability and patient care.

Neoadjuvant therapy is a relatively new weapon in the chemotherapeutic arsenal against breast carcinoma. However, there has been concern that preoperative chemotherapy might lead to an increased incidence of complications and delays in postoperative treatment. A retrospective study was performed at M.D. Anderson Cancer Center of all patients with locally advanced breast cancer who had undergone neoadjuvant therapy followed by mastectomy and immediate reconstruction with the transverse rectus abdominis musculocutaneous (TRAM) flap. Patients were evaluated for the incidence of complications and any delays in resumption of postoperative chemotherapy. Thirty-one patients underwent immediate reconstruction with the TRAM flap. Twenty-two patients were reconstructed with free TRAM flaps whereas 9 patients were reconstructed with pedicled TRAM flaps. Seventeen patients (55%) had complications postoperatively, but only 2 patients (6%) had a delay in the resumption of chemotherapy. Seven patients were smokers, five (71%) of whom had complications, which was not a significant difference from the rate in nonsmokers (50%). Although delays in postoperative chemotherapy occurred in smokers (29%, vs. 0% in nonsmokers), the number of patients was too small to attain statistical significance. Based on this study it is felt that immediate reconstruction with the TRAM flap can be performed safely in patients on a neoadjuvant protocol. Although not contraindicated, immediate reconstruction with the TRAM flap in smokers in this setting may be associated with higher morbidity.

Clinical trials of topical ALA in photodynamic therapy (PDT) of basal cell carcinoma (BCC) show significant recurrence rates. Exogenous 5-aminolevulinic acid (ALA) is converted by intracellular enzymes to photoactive protoporphyrin IX (PpIX) in human tissues. PpIX generates cytotoxic singlet oxygen when irradiated with visible light in the 400–640 nm range. To evaluate variability and heterogeneity in PpIX production by tumors in such trials, and to assess the usefulness of PpIX for marking skin tumors, we measured PpIX fluorescence distribution in BCC after topical application of 20% ALA cream. ALA cream was applied under occlusion for periods ranging from 3 to 18 h (average 6.9 h, SD 4 h) to 16 BCCs. ALA conversion to PpIX in the BCCs was assessed by in vivo photography, ex vivo video fluorescence imaging, and fluorescence microscopy. External macroscopic PpIX fluorescence, as assessed by in vivo and ex vivo imaging, correlated with the clinical presence of BCC. Examination by a digital imaging fluorescence microscope revealed inter- and intratumor fluorescence variability and heterogeneity. PpIX fluorescence corresponding to full tomor thickness was found in six superficial and four nodular tumors, and partial-thickness fluorescence was observed in five nodular tumors, but no PpIX fluorescence was observed in some areas of superficial, nodular and infiltrating tumors. In a significant number of nodular and infiltrating BCCs, topical ALA appeared to provide little or no PpIX in deep tumor lobules. In addition, no selectivity for tumor tissue versus normal epidermis was seen. The grossly brighter external PpIX fluorescence over tumors may be due, therefore, to enhanced penetration through tumor-reactive stratum corneum and to the tumor thickness. The absence of reproducible fluorescence marking of nodular and infiltrating BCC suggests that topical ALA, at least under the present delivery protocols, may not be a reliable regimen for photodynamic treatment of these BCCs.

The indolealkaloids aspidospermine and quebrachamine have been isolated in crystalline form by a relatively rapid fractionation from the extract of a powdered material designated “Quebracho” derived from an Aspidosperma tree species. We present a novel isocratic LC method that provides baseline resolution of these two compounds and of the structurally related yohimbine in less than 15 min. Gas chromatography—mass spectrometry was employed to identify these compounds as well as several minor derivatives of aspidospermine during and after the purification process. Aspidospermine and quebrachamine like yohimbine have been found to possess adrenergic blocking activities for a variety of urogenital tissues.

Topical application of aminolevulinic acid (ALA) is known to lead to enhanced concentrations of protoporphyrin IX (PpIX) in skin tumors versus normal tissue several hours after application. As PpIX is an effective photosensitizer, topical ALA is being used in several clinical trials to treat skin malignancies, with variable success rates to date. As PpIX is highly fluorescent, we have initiated a clinical trial to determine the PpIX distribution in normal and tumor tissue after the application of ALA via fluorescent imaging. Subjects apply ALA topically several hours prior to surgical excision of basal cell carcinomas, and the resulting PpIX distributions in normal and tumor tissue are examined on a macroscopic and microscopic scale. This information allows us to determine the exact degree of correlation between PpIX distribution and tumor tissue, and gain insight into the mechanism for the specificity of PpIX for tumor tissue. In addition, we are exploring the possibility of using the PpIX fluorescence as a guide to the excision of skin tumors.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The ability of laser-induced fluorescence (LIF) to detect flat dysplasia has not been carefully studied. A multi- excitation wavelength LIF system was used to develop analgorithm to detect chemically-induced dysplasia in the rat urinary bladder. Dysplasia was generated using intravesicaldoses of N-methyl-N-nitrosourea (MNU). A total of the 108randomly selected sites, 1 5 untreated controls and 93 MNU- treated, were examined. Of the treated sites, 34% were histologically classified as dysplasia, 1 1% as carcinoma insitu (CIS), 15% as squamous metaplasia, 12% as hyperplasiaand 28% as being normal. For fluorescence measurements, 6excitations wavelengths from 360 nm to 425 nm were usedand complete emission spectra recorded. The data were splitinto neoplastic (dysplastic and CIS sites) and non-neoplastic (normal and hyperplastic sites) groups using 3 different scoring criteria and a stepwise multivariate linear regression analysis was performed on the excitation-emission matrix. In one algorithm, only 3 excitation-emission pairs

Radiation synovectomy is a potential weapon in the therapeutic armamentarium of nuclear medicine. It is an attractive alternative to surgical or chemical synovectomy for the treatment of rheumatoid arthritis. In this article the clinical results obtained with radiation synovectomy from the 1950s through 1992 are summarized and reviewed. Even after taking into account the paucity of well-controlled trials and rigorous clinical follow-up, it is clear that radiation synovectomy is efficacious in controlling the symptoms of rheumatoid arthritis. However, the procedure is not widely used because of concerns about leakage of radioactivity from the treated joint, and the resulting high doses that can be delivered to nontarget organs. New approaches to the preparation of radiolabeled particles for use in radiation synovectomy promise to minimize this leakage and thus allow the full potential of this important radiotherapy to be realized.

The present study uses photodynamic therapy (PDT) for the treatment of IH in the rat carotid artery model. PDT is a relatively new cancer treatment technique which utilizes light-activated photosensitizers (PS) to produce injury to targeted cells. PS have no cytotoxic effects unless they are activated by the appropriate wavelength of light. Upon absorption of a photon, the activated PS can either by directly cytotoxic or give rise to cytotoxic oxygen species, commonly singlet oxygen, via energy transfer to the ground state molecular oxygen. Singlet oxygen then becomes the mediator of cellular injury by affecting cellular membranes and subcellular organelles.

✓ The ability of laser-induced fluorescence spectroscopy to delineate tumor margins intraoperatively was studied using a rat intracerebral glioma model. A fluorescent dye, chloro-aluminum phthalocyanine tetrasulfonate (ClAlPcS4), was injected intravenously 24 hours before tumor resection. The animals underwent tumor resection under the operating microscope, guided by laser-induced fluorescence measurement in one group (Group 1) and visual assessment in the other (Group 2). The Group 1 rats had a significantly reduced volume of residual tumor following resection (0.5 ± 0.2 cu mm vs. 13.7 ± 4.0 cu mm, mean ± standard error of the mean, p < 0.02). Three of the nine animals in Group 1 were tumor-free at 2 weeks following resection, compared with none of the 10 rats in Group 2 (p < 0.05). Interference from brain autofluorescence was minimized using spectrally resolved detection and the ClAlPcS4 dye, which has a 680-nm fluorescence peak significantly higher than the 470-nm autofluorescence peak of normal brain. Contrast ratios of up to 40:1 were found for glioma:normal brain fluorescence signals. Spatially-resolved spectra were acquired in approximately 5 seconds using a fiberoptic probe. This study demonstrates the ability of an intraoperative laser-induced fluorescence system to detect tumor margins that could not be identified with the operating microscope.

Medical applications of laser-induced fluorescenceKevin T. Schomacker, Joan K. Frisoli,Thomas F. Deutsch,Massachusetts General HospitalBoston, MA 021141. INTRODUCTIONAlthough lasers have traditionally been used in medicine as therapeutic devices,there has been considerable interest in using them as diagnostic tools. A numberof groups have been studying the medical applications of Laser-InducedFluorescence (LIF)1'2. We describe three projects examining the potential use ofLIF in medicine. They involve the classification of colonic polyps, the LIF-.guided resection of brain tumors, and the advantages of LIF for studyingphotosensitizer pharmacokinetics. All three projects are only summarized;complete descriptions will appear elsewhere.2. LASER-INDUCED AUTOFLUORESCENCE OF COLONIC TISSUE:BASIC BIOLOGY AND DIAGNOSTIC POTENTIALRecently, several groups have used LIF to diagnose premalignant colorectallesions, i.e., to distinguish adenomatous polyps from normal colonic tissue andhyperplastic polyps3'4. Hyperplastic polyps are non-neoplastic lesions caused bythe failure of mature epithelial cells to detach normally. Adenomatous polypsare benign hyperproliferative neoplasms consisting of immature, poorly-differentiated epithelial cells with differing degrees of dysplasia. The vastmajority of colorectal carcinomas arise from adenomatous polyps.This study had three goals: 1) to evaluate the feasibility of using LIF to detectcolonic neoplasia and, in particular, to distinguish adenomatous from hyperplasticpolyps in vivo; 2) to test the transportability of published algorithms forevaluating our colonic LIF and 3) to examine the LIF spectra ofdifferent colonic tissue types along with spectral changes with time afterresection and relate the changes to the biology and structure of the tissue. Amore quantitative understanding of these spectral changes with tissue type wasobtained by decomposing the fluorescence spectra into the contributions ofindividual tissue components (fluorophores and absorbers). This spectraldecomposition approach was also used to quantify the differences between in vivoand in vitro LIF spectra as well as the changes in the observed in vitro spectraas a function of time after resection. In addition, the depth to which the LIFmeasurement probes was estimated from measurements of fluorescence intensity offrozen sections as a function of tissue thickness. Finally, the entire study usedcolonic polyps as a model system for understanding the potential and limitationsof autofluorescence for tissue diagnosis. Only the diagnostic potential will bedescribed here.The LIF system is shown schematically in Figure 1. The output of a pulsed-nitrogen laser (337 nm, 3-ns pulses at 10 Hz and 200-jzJ pulse energies) wascoupled via a quartz lens into a single 600-jLm-core-diameter quartz optical fiber.Typical energies delivered to tissue were 40 jzJ. Fluorescence from the tissue wastransmitted through the same optical fiber and optically coupled to a quartz

Rhenium-186 (tin)hydroxyethylidene diphosphonate (HEDP) is a new radiopharmaceutical that localizes in skeletal metastases in patients with advanced cancer. A single intravenous administration of approximately 34 mCi (1,258 MBq) resulted in significant improvement in pain in 33 of 43 evaluable patients (77%) following the initial injection, and in 7 of 14 evaluable patients (50%) following a second treatment. Patients responding to treatment experienced an average decrease in pain of about 60%, with one in five treatments resulting in a complete resolution of pain. The only adverse clinical reaction was the occurrence after about 10% of the administered doses of a mild, transient increase in pain within a few days following injection. Statistically significant but clinically unimportant decreases in total white blood cell counts and total platelet counts were observed within the first 8 weeks following the injection; no other toxicity was apparent. Rhenium-186(Sn)HEDP is a useful new compound for the palliation of painful skeletal metastases.

Laser-induced fluorescence (LIF) of colonic tissue was examined both in vitro and in vivo to assess the ability of the technique to distinguish neoplastic from hyperplastic and normal tissue and to relate the LIF spectra to specific constituents of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, 49 adenomatous polyps, and 7 adenocarcinomas were recorded both in vivo and in vitro. With 337-nm excitation, the fluorescence spectra all had peaks at 390 and 460 nm, believed to arise from collagen and NADH, and a minimum at 425 nm, consistent with absorption attributable to hemoglobin. The spectra of colonic tissue recorded both in vivo and in vitro are different, primarily in the NADH fluorescence component, which decays exponentially with time after resection. When normal colonic tissue is compared to hyperplastic or adenomatous polyps, the predominant changes in the fluorescence spectra are a decrease in collagen fluorescence and a slight increase in hemoglobin reabsorption. A multivariate linear regression (MVLR) analysis was used to distinguish neoplastic tissue from non-neoplastic tissue with a sensitivity, specificity, predictive value positive, and predictive value negative toward neoplastic tissue of 80%, 92%, 82%, and 91%, respectively. When the MVLR technique was used to distinguish neoplastic polyps from non-neoplastic polyps, values of 86%, 77%, 86%, and 77% respectively, were obtained. The data suggest that the LIF measurements sense changes in polyp morphology, rather than changes in fluorophores specific to polyps, and it is this change in morphology that leads indirectly to discrimination of polyps.

Alpha-Fetoprotein (AFP) is a product of specific fetal tissues and of neoplastic cells of hepatocyte or germ cell origin in adults. This protein belongs to a gene family that is phylogenetically most closely related to serum albumin. Its primary, secondary, and tertiary structural aspects appear similar to the three-domain concept proposed for the latter protein. The primary sequence of AFP departs most widely from serum albumin in the first 135 amino acid residues, with about 42% of the remaining 590 residues of the human proteins being identical. Some evidence exists that there are limited sequence differences in the AFP of a given animal species. AFP shows considerable charge heterogeneity that appears to relate mostly to its glycoid moiety. The proteins of some species such as the rat show more pronounced heterogeneities than that of humans. The variations in extent and type of glycosylations are evidenced by differences in the binding to various lectins. These interactions are being extensively explored in attempts to differentiate the sources of the protein produced by various normal and neoplastic cells and may provide valuable diagnostic methods. AFP, like serum albumin, shows relatively strong binding affinities for a variety of ligands. The most notable difference is the strong preferential binding of polyunsaturated fatty acids by AFP. This protein may play a role in transporting these substances to developing and to malignant cells. Various agents affect the synthesis of this protein both by specific fetal tissues and by neoplastic cells. Marked differences in the responses of cells, particularly those of neoplastic types, are indicative of variations in the genetic factors responsible for control of its synthesis. The subject of the genomic repression of the synthesis of AFP seen in fetal life upon maturation of the liver and the reoccurrence of synthesis upon malignant conversion of hepatocytes and of certain germ cells are of particular interest. The regulation of the closely related AFP and albumin genes is providing a powerful and attractive model to examine molecular events in the activation and inactivation of specific genes during development and in oncogenic processes. Extensive measurements of AFP during pregnancy and in the course of neoplasias, notably hepatoma, are being made to aid in following changes in such developments. Various specific physiological roles for this protein are also being proposed. One of these is its possible action in the regulation of immune processes.(ABSTRACT TRUNCATED AT 400 WORDS)

We study acoustic effects associated with the ablation of polyimide under water confinement. Ablation launches a shock in the target. After the shock propagates into the surrounding water we measure its velocity with an optical probe system. In the water the shocks decay after propagating a few hundred microns. The peak shock pressure scales with the square root of the laser fluence. Our observations can be explained by a simple model that interprets the generated pressures as being due to the heating of a confined ideal gas.

The use of pulsed infrared lasers for tissue ablation has led to increased control over thermal damage to tissue and to more precise control over material removal. Tissue removal is mediated by the explosive vaporization of water, which can lead to clinically significant tissue effects.

The use of high peak power laser pulses in the short and ultrashort time domains has opened a variety of novel laser-tissue interactions with potential for application in clinical medicine. Photodisruption (optical breakdown) of nominally transparent tissues within the eye, excimer laser tissue ablation, and femtosecond laser tissue ablation are three examples of such tissue effects. Laser tissue interactions in these time domains will be reviewed and selected techniques for investigation of the time scale and damage mechanisms of these interactions will be presented.

Treated calcium/oxyanion-containing particles are disclosed for enhancing medical diagnostic imaging such as magnetic resonance imaging ("MRI"), magnetic resonance spectroscopy ("MRS"), magnetic resonance spectroscopy imaging ("MRSI"), X-ray diagnostic imaging, and ultrasound imaging. Novel coating and manufacturing techniques are disclosed to control particle size and particle aggregation resulting in compositions for organ specific imaging of the liver, spleen, or tissue disease states is obtained. Depending on the diagnostic imaging technique, calcium/oxyanion-containing particles are treated to be paramagnetic, radiopaque, or echogenic. Also disclosed are diagnostic compositions and methods of performing medical diagnostic procedures which involve administering to a warm-blooded animal a diagnostically effective amount of the above-described particles and then performing the medical diagnostic procedure.

The pulsed ultraviolet excimer laser has been used to produce tissue ablation with a high degree of precision and with minimal thermal damage to adjacent structures. In comparative studies of excimer laser ablation of the cornea and crystalline lens using 193 nm and 248 nm radiation, threshold fluence for corneal and lens ablation was higher at 248 nm than at 193 nm. Ablation of corneal stroma at 193 nm produced the most precise cuts. When examined by transmission electron microscopy, a narrow zone of damaged tissue (0.1 to 0.3 micron) was seen immediately adjacent to the tissue removed by the laser. Ablation with 248 nm radiation produced incisions with ragged edges and with a wider and more severe zone of damage in adjacent stroma. Ultraviolet spectral transmission studies of the corneal stroma showed that absorption is 10 times greater at 193 nm than at 248 nm. The excimer laser was effective in producing well controlled ablation of the crystalline lens in vitro, with effects parallel to those seen in the cornea.

A technique for maskless writing of metal films with submicrometer dimensions is described. An ultraviolet beam from a cw or pulsed laser is used to photodissociate an organometallic gas near a gas–solid interface. The liberated metal atoms then condense in an area of dimensions comparable to the laser spot size. Experiments which elucidate the essential physics of the process have been performed.

We studied the use of a short-pulse, flashlamp-pumped dye laser, emitting at 666 nm, to create ab interno sclerotomies in cynomolgus monkeys using a fiberoptic delivery system. Because of the low optical absorption of the sclera in the visible portion of the spectrum, ablation of sclera by continuous wave lasers emitting in this region requires high energies and produces significant thermal damage to surrounding tissues. To enhance the optical absorption of sclera, methylene blue dye was applied iontophoretically; patent sclerotomies were obtained in all 10 eyes of six cynomolgus monkeys, with energies ranging from 15 to 50 mj/pulse. Thermal damage to the adjacent sclera was confined to 300 microns. Complications included mild intraoperative hyphema at all pulse energies and iridodialysis at higher pulse energies. Filtration blebs routinely failed within 7 days; the use of 5-fluorouracil postoperatively significantly prolonged bleb duration. The small incision technique described allows ab interno sclerotomies to be created with low pulse energies without the need for conjunctival dissection, thereby avoiding the problems associated with conjunctival wounds. An advantage of this technique is that it can be modified to create ab interno sclerotomies noninvasively by delivering pulsed visible radiation through the cornea with a gonioscopic-slitlamp system.

The effects of picosecond laser-induced optical breakdown on tissue were investigated using high-intensity 40 ps Nd:YAG laser pulses at 1.06 microns. Tissue damage was evaluated using the corneal endothelium in vitro as a model system. Systematic studies were performed to determine the scaling of the tissue damage and damage range with pulse energy. For suprathreshold lesions, the radius of the damage zone varies as the cube root of the pulse energy, in agreement with simple physical scaling laws. A minimum damage range of less than 100 microns was observed for pulse energies of 8 muJ. Damage morphology was investigated by scanning electron microscopy. Three different damage patterns were observed; cell damage, cell removal, and rupture of Descemet's membrane. Different irradiation geometries were used to study damage mediated by either the shock wave or the cavitation bubble. Comparative studies using 10 ns pulses demonstrated that picosecond pulses yielded a significant reduction in collateral tissue damage.

• Laser endophotocoagulation is an important technique in vitreoretinal surgery. We performed successful retinal endophotocoagulation in the eyes of Dutch-belted rabbits, using high-power phased-array semiconductor lasers, emitting at 808 and 817 nm. The laser itself measured 25 × 30 × 21 mm, was air cooled, and was portable. At a treatment power of 100 mW, uniformly white photocoagulation lesions were seen at exposure durations of 0.2 to 1.0 s. Lesions were similar in appearance to argon laser photocoagulation lesions, as determined by ophthalmoscopy and fluorescein angiography. Thin-section histologic examination of acute lesions revealed injury localized to the outer retina; chorioretinal scar formation was noted ten days after photocoagulation. To our knowledge, this study is the first in which therapeutically useful lesions were produced using a diode laser and demonstrates the feasibility of using these highly efficient and compact laser sources for ophthalmic photocoagulation.

Laser endarterectomy, a promising new method of reopening stenotic or occluded arteries, has been limited by difficulties in ablating calcified plaque. This study demonstrates that pulsed, visible laser radiation (482 nm, 1 μs duration, 40-80 mJ/pulse) can ablate calcified plaque at intensities (50 MW/cm2) that are readily transmit, ted down flexible (320 μm diameter) optical fibers and at fluences which are below the threshold for ablating normal artery. The ablative process is characterized by a loud snapping sound, a luminescent plume, ejection of fine debris, and an ablation efficiency as high as 10 mg/J, suggesting that removal of material occurs primarily by formation of a plasma and fracturing of the plaque, rather than by thermal vaporization. The presence of a plasma associated with ablation of calcified plaque was documented by emission spectrum measurements.

A focused, ultraviolet (UV) laser beam has been used to produce micrometer-sized chemical processes on solid surfaces. These processes are initiated by the photodissociatlon of a molecular gas in the vicinity of the gas-solid interface. Depending on whether the active photofragment reacts with or is adsorbed on the solid, microetching or microdeposition occurs. Both the surface properties of the solid and the gas-phase kinetics contribute to the process localization. Metal alkyls and methyl halides have been used as parent molecules for deposition and etching, respectively. A focused, 3 mW UV laser is sufficiently intense to produce satisfactory rates for both processes. Several applications of this small-scale photochemistry to microelectronics have been investigated.