Usually systemic photosensitizers (PS) require a long period of incubation (48-96h) after systemic admission. On the
other hand clearing from healthy skin needs weeks or months. Severe side effects on skin are possible in case of
uncontrolled light exposure. Topical PDT may solve this problem, but deep portions may not be sufficiently sensitized,
resulting in a survival of some tumor cell population after PDT and recurrence. The same problem counts for actinic
keratosis and Bowen's disease, but with even worse consequences as a resulting infiltrating growing squamous cell
carcinoma (SCC) is likely to produce metastatic lesions. Light dosimetry is crucial also. Wavelenght, fluence and total
energy may influence outcome of any PDT substantially.
17 patients with Bowen's disease or BCC where treated using a novel systemic PS (Fotolon®) and 665nm light from a
diode laser. Follow up time ranges between 2.5 and 1 years after treatment. 2 patients received a second PDT, in 15
patients one treatment was efficient. We found a remissions in 1, local control in 2 and no evidence of disease in 14
patients. Significant fluorescence was noted in all lesions. With a light protection protocol for only 48 hours no severe
side effects where seen. One patient developed mild redness of sunlight exposed skin sites 24h after being discharged
from light protection protocol.
In comparison with currently available topical PS Fotolon® offers some important advantages as secure photosenzitation
of deep portions, single treatment, high selectivity combined with a high cure rate. In comparison with currently
available systemic PS Fotolon® offers short incubation time, high selectivity and short time of elimination, while
efficiency was comparable to HPD (hematoporphyrin-derivate) PDT combined with ALA-5 PDT and without need for
additional local PS-application for PDD.
The effect of laser induced thermotherapy (LITT) as palliative method in otherwise pre-treated patients (irradiation, chemotherapy and/or surgery) with local recurrences of breast cancer should be investigated. In 7 women, an interstitial laser application was performed percutaneously into the center of the diseased tissue. The laser used was a Nd:YAG laser with a wavelength of 1064 nm. Heat expansion was controlled digitally and monitored by ultrasound and color coded duplex sonography (CCDS) respectively. This minimal invasive method enabled the precise coagulation of the tumor without destruction of the skin or ulceration, although the areas had been pre-treated by irradiation up to 60 Gy, before. All patients are scheduled in a long-time follow-up. The CCDS-guided interstitial laser therapy is a safe and minimal invasive method for palliative treatment of subcutaneous local recurrences of breast cancer.
Aim of the study was the comparative investigation of cutaneous and subcutaneous vascular lesions. By means of color coded duplex sonography (CCDS), laser doppler perfusion imaging (LDPI) and infrared thermography (IT) we examined hemangiomas, vascular malformations and portwine stains to get some evidence about depth, perfusion and vascularity. LDI is a helpful method to get an impression of the capillary part of vascular lesions and the course of superficial vessels. CCDS has disadvantages in the superficial perfusion's detection but connections to deeper vascularizations can be examined precisely, in some cases it is the only method for visualizing vascular malformations. IT gives additive hints on low blood flow areas or indicates arterial-venous-shunts. Only the combination of all imaging methods allows a complete assessment, not only for planning but also for controlling the laser treatment of vascular lesions.
KEYWORDS: Laser therapeutics, Skin, Argon ion lasers, Dye lasers, Glasses, In vitro testing, Temperature metrology, Thermal imaging cameras, Cameras, In vivo imaging
The purpose of this study was the evaluation of different combined cooling and compression techniques for the treatment of vascular disorders of the skin and subdermal layers. In combination with flashlamp pumped dye lasers, argon lasers and Nd:YAG-lasers the effectiveness of glass plates, a cooling chamber with a flexible membrane and continuous ice cube cooling were evaluated in vitro by temperature measurements with thermocouples and thermographic camera readings and in vivo by laser doppler flowmetry, color coded duplex sonography and comparison of photographic documents for effectiveness and occurrence of side effects. Experimental and clinical evaluations show excellent results for skin protection, effective treatment depth enhancement and minimalization of side effects as well as for pain perception.
Different laser systems and techniques are used for the treatment of hypertrophic scars, keloids and acne scars. Significant criteria in selecting a suitable laser system are the scar's vascularization, age and diameter. Flashlamp- pumped dye-lasers, CO2-lasers with scanner, Argon and Nd:YAG-lasers are used. Telangiectatic scars respond well to argon lasers, erythematous scars and keloids to dye-laser treatment. Using interstitial Nd:YAG-laser vaporization, scars with a cross-section over 1 cm can generally be reduced. For the treatment of atrophic and acne scars good cosmetic results are achieved with a CO2-laser/scanner system, which allows a precise ablation of the upper dermis with low risk of side-effects.
As a high number of metastases grow in the liver, new treatment methods have been developed. Laser-induced thermotherapy (LITT) has recently applied for a minimally invasive technique in local treatment of liver metastases. Laser light was performed using Neodymium yttrium aluminum garnet (Nd-YAG, wavelength 1064 nm) delivered through a quartz fiber optic with a diameter of 400 micrometer with diffuse light emission. Laser light is converted into heat in the target area with an ensuing coagulative necrosis, secondary degeneration and atrophy, tumor shrinkage with minimal damage to surrounding structures. The size of heated volume depends on laser power, laser irradiation time, the way it reaches the target area and optical and thermal characteristics of the treated tissue. Pilot clinical studies have demonstrated that this technique is practical for the palliation of hepatic tumors. The clinical success of the thermotherapy depends on the optimal localization of the laser applicator in the center of the lesion, an optimal 'online monitoring' of thermal changes in the treated tissue and an exact documentation of the therapy effect and the local tumor controlrate. The individual optimization of two special developed thermosensitive sequences allows an exact monitoring of the progress of LITT to the treated lesion and surrounding structures. The purpose of this paper is to describe our experimental and clinical experience with MR-guided LITT for treatment of liver metastases and follow-up evaluation in larger series.
Martin Mack, Thomas Vogl, Petra Mueller, Carsten Philipp, H. Boettcher, Andre Roggan, M. Juergens, W. Pegios, W. Scholz, J. Balzer, V. Jahnke, Roland Felix
Interstitial laser-induced thermotherapy (LITT) is a recently developed, minimally invasive technique for local tumor destruction within solid organs. Low-power laser, with delivery of light energy through thin optical fibers, results in a well-defined area of coagulative necrosis. Thus, laser can destroy tumor by direct heating, while greatly limiting damage to surrounding structures. Experimental work has shown that a well defined area of coagulative necrosis is obtained around the fiber tip, with minimal damage to surrounding structures. Pilot clinical studies have demonstrated that this technique is practical for the palliation hepatic tumors. The success of LITT is dependent on delivering the optical fibers to the target area, real time monitoring of the effects of the treatment and subsequent evaluation of the extent of thermal damage. The key to achieving these objectives is the imaging methods used. The magnetic resonance (MR) findings of LITT in the experimental setting have been described, but the clinical role of MRI during and after LITT has been only described in a small series of patients.
The in vivo model of the chorioallantoic membrane of fertilized chicken embryos (CAM) was employed for studying the fluorescence characteristics of tumor tissue in comparison with non tumorous tissue. Tumors were grown from the murine fibrosarcoma cell line SSK II and murine 3T3 fibroblasts (clone A31) were used for cultivating non tumorous tissue. Autofluorescence and xenofluorescence intensities induced by 5-aminolaevulinic acid (5-ALA) were compared. Exogenous administration of 5-ALA, an early precursor in haem synthesis, induces accumulation of endogenous photoactive porphyrins, in particular protoporphyrin IX (PpIX). Fluorescence investigations were performed after 3-4d of incubation, when the tissues had reached macroscopically three dimensional stages of growth. Fluorescences were excited with a HBO-X 100 W lamp (Carl Zeiss) at a wavelength (lambda) equals 405 plus or minus 5 nm. Emissions were detected in the spectral range above 630 nm and visualized by real time digital image processing (Argus 10, HAMAMATSU) using an ICCD camera (HAMAMATSU). After administration of 0.4 mmolar 5-ALA solution to the CAM inoculated tissues the SSK II tumors exhibited higher fluorescence intensities than the 3T3 non tumorous tissues. Autofluorescence intensities of both types of tissues were not distinguishable. Furthermore, the effects of several biochemicals on the xenofluorescence intensities of the fibrosarcoma and fibroblast tissues were investigated.
An analysis of injuries and risks using high frequency (HF) and lasers in medicine based on a literature search with MEDLINE was performed. The cases reported in the literature were classified according to the following criteria: (1) Avoidable in an optimal operational procedure. These kind of injuries are caused by a chain of unfortunate incidents. They are in principle avoidable by the 'right action at the right time' which presupposes an appropriate training of the operating team, selection of the optimal parameters for procedure and consideration of all safety instructions. (2) Avoidable, caused by malfunction of the equipment and/or accessories. The injuries classified into this group are avoidable if all safety regulations were fulfilled. This includes a pre-operational check-up and the use of medical lasers and high frequency devices only which meet the international safety standards. (3) Avoidable, caused by misuse/mistake. Injuries of this group were caused by an inappropriate selection of the procedure, wrong medical indication or mistakes during application. (4) Unavoidable, fateful. These injuries can be caused by risks inherent to the type of energy used, malfunction of the equipment and/or accessories though a pre-operational check-up was done. Some risks and complications are common to high frequency and laser application. But whereas these risks can be excluded easily in laser surgery there is often a great expenditure necessary or they are not avoidable if high frequency if used. No unavoidable risks due to laser energy occur.
During the period of January 1984 - July 1993, we have treated 611 children with more than 2000 lesions of congenital vascular disorders (CVD) such as hemangiomas and vascular malformations. This number does not include the patients with port wine stains, which also have been treated by means of laser. Most of the CVD patients (n equals 467) presented hemangiomas of the face, the anogenital region, and the extremities, some were located in the trachea or mouth or in the urogenital tract. All of these hemangiomas were growing prior to intervention or showed complications such as bleeding, ulceration, superinfection, or obstruction. Nearly a quarter (n equals 144) of the patients presented vascular malformations, either of singular vessel type involvement or of mixed vascular genesis (venous, arterio- venous, veno-lymphatic or lymphatic) with various complications like tracheal obstruction or recurrent thrombophlebitis. According to our step program, which is based on a clinical classification, the hemangiomas were treated as early as possible, while the vascular malformations were only treated with laser when no other therapeutic technique (embolization, resection) was suitable. All patients were referred for laser treatment from other centers. The lasers used were Nd:YAG and Argon lasers with transcutaneous application with or without continuous ice-cube surface cooling or interstitial laser application. The treatments were performed either on in- or outpatient basis according to age, localization and with good to excellent results in most cases and a complication rate of less than 2%.
Since 1984 we use the interstitial application of laser induced thermotherapy (LITT) for the treatment of congenital vascular disorders (CVD) such as hemangiomas and vascular malformations. In most of the procedures a 600 micron core bare fiber is used to deliver the radiation of a cw Nd:YAG laser emitting at 1064 nm into the diseased tissue. As most of the CVD treated this way are located subcutaneously, the localization of the fiber and the interstitial laser coagulation (ILC) is controlled by transillumination and palpitation of the heat expansion of the skin surface, this way a crepitation can also be detected during the ILC. As the ILC in deeper body structures cannot be controlled directly we use color coded duplex sonography (CCDS), both for diagnostic and treatment control. In the procedures where we use the B-scan image for puncture control, a color signal is displayed representing tissue movements. These movements caused by degasification and vapor are those detectable as crepitations when using direct control. The color signal starts, changes, and moves in a reproducible pattern following the heat distribution and the subsequently occurring degasification in the tissue. Also the changes in perfusion are detectable by the means of CCDS. The precise extent of the coagulation is visible in the B-scan several minutes after laser exposure. The clinical experience and an extensive experimental evaluation has proven that CCDS is a valuable real time method to monitor the tissue reaction in ILC-procedures. For two years we have performed ILC-procedures with CCDS control in patients with CVD (n equals 65) successfully. Because of its reliable imaging and the clinical advantages recently we applied this type of ILC-control to the palliative treatment of nonresectable primary and secondary liver tumors (n equals 3) and subcutaneous metastases of mamma carcinoma. (n equals 6).
The aim of our experimental and clinical studies was to investigate the suitability of Color- Coded Duplex Sonography (CCDS) for on-line monitoring of the Laser-Induced Thermotherapy procedures. Both the changes in the CCDS imaging during irradiation as well as the thresholds at which a `color bruit' occurs were investigated. Furthermore we have evaluated the correlation between the B-scan imaging of the damaged area and the size of coagulation in pathology measurements.
Because of the different step programs concerning the preoperative diagnostic and the onset of therapy for the various types of congenital vascular disorders (CVD) a clear classification is important. One has to discern the vascular malformations, including the port wine stain, from the real hemangiomas which are vascular tumors. As former classification, mostly based on histological findings, showed little evidence to a clinical step program, we developed a descriptive classification which allows an early differentiation between the two groups of CVD. In most cases this can be done by a precise medical history of the onset and development of the disorder, a close look to the clinical signs and by Duplex-Ultrasound and MRI-diagnostic. With this protocol and the case adapted use of different lasers and laser techniques we have not seen any severe complications as skin necrosis or nerve lesions.
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