Protoporphyrin IX fluorescence photobleaching is a useful tool to predict the response of rat ovarian cancer following hexaminolevulinate photodynamic therapy
ABSTRACT Accurate dosimetry was shown to be critical to achieve effective photodynamic therapy (PDT). This study aimed to assess the reliability of in vivo protoporphyrin IX (PpIX) fluorescence photobleaching as a predictive tool of the hexaminolevulinate PDT (HAL-PDT) response in a rat model of advanced ovarian cancer.
Intraperitoneal 10(6) NuTu 19 cells were injected in 26 female rats Fisher 344. Peritoneal carcinomatosis was obtained 26 days post-tumor induction. Four hours post-intraperitoneal HAL (Photocure ASA, Oslo, Norway) injection, a laparoscopic procedure (D-light AutoFluorescence system, Karl Storz endoscope, Tuttlingen, Germany) and a fluorescence examination were made for 22 rats. The first group (LASER group, n=26) was illuminated with laser light using a 532 nm KTP laser (Laser Quantum, Stockport, UK) on 1 cm(2) surface at 45 J/cm(2). The second group (NO LASER group, n=26) served as controls. Biopsies were taken 24 hours after PDT. Semi-quantitative histology was performed and necrosis value was determined: 0--no necrosis to 4--full necrosis. Fluorescence was monitored before and after illumination on complete responders (NV=3-4; n=20) and non-responders (NV=0-2; n=6).
High PpIX photobleaching corresponded with complete responders whereas low photobleaching corresponded with non-responders (P<0.05). A direct linear correlation was shown between photobleaching and necrosis (R(2)=0.89).
In vivo PpIX fluorescence photobleaching is useful to predict the tissue response to HAL-PDT.
- SourceAvailable from: Imran Rizvi[Show abstract] [Hide abstract]
ABSTRACT: Photodynamic therapy (PDT) dosimetry is an active area of study that is motivated by the need to reliably predict treatment outcomes. Implicit dosimetric parameters, such as photosensitizer (PS) photobleaching, may indicate PDT efficacy and could establish a framework to provide patient-customized PDT. Here, tumor destruction and benzoporphryin-derivative (BPD) photobleaching are characterized by systematically varying BPD-light combinations to achieve fixed PDT doses (M * J * cm-2) in a three-dimensional (3D) model of micrometastatic ovarian cancer (OvCa). It is observed that the BPD-light parameters used to construct a given PDT dose significantly impact nodule viability and BPD photobleaching. As a result, PDT dose, when measured by the product of BPD concentration and fluence, does not reliably predict overall efficacy. A PDT dose metric that incorporates a term for BPD photobleaching more robustly predicts PDT efficacy at low concentrations of BPD. These results suggest that PDT dose metrics that are informed by implicit approaches to dosimetry could improve the reliability of PDT-based regimens and provide opportunities for patient-specific treatment planning.Proceedings of SPIE - The International Society for Optical Engineering 03/2013; 8568:0S. DOI:10.1117/12.2010840 · 0.20 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Photodynamic therapy (PDT) is an innovative technique in oncologic urology. Its application appears increasingly realistic to all kind of cancers with technological progress made in treatment planning and light delivery associated with the emergence of novel photosensitizers. The aim of this study is to review applications of this technique in urology. We reviewed the literature on PDT for urological malignancies with the following key words: photodynamic therapy, prostate cancer, kidney cancer, urothelial cancer, penile cancer and then by cross-referencing from previously identified studies. Focal therapy of prostate cancer is an application of PDT. Clinical studies are ongoing to determine PDT efficacy and safety. PDT as salvage treatment after radiotherapy has been tested. Oncologic results were promising but important side effects were reported. Individual dosimetric planning is necessary to avoid toxicity. PDT was tested to treat superficial bladder carcinoma with promising oncologic results. Serious side effects have limited use of first photosensitizers generation. Second generation of photosensitizer allowed reducing morbidity. For upper urinary tract carcinoma and urethra, data are limited. Few studies described PDT application in penile oncology for conservative management of carcinoma in situ and premalignant lesions. For renal cancer, PDT was only tested on preclinical model despite of its potential application. No data is available concerning PDT application for testicular cancer. PDT clinical applications in urology have proved a kind of efficiency balanced with an important morbidity. Development of new photosensitizer generations and improvement in illumination protocols should permit to decrease side effects.Photodiagnosis and photodynamic therapy 09/2012; 9(3):261-73. DOI:10.1016/j.pdpdt.2012.01.005 · 2.52 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: We present an analytical method to compute the exact performance of algebraically decoded linear block codes in nonindependent channel errors. Performance is computed by rating decoding events. The block error distribution and the coset probabilities are of fundamental interest. A recursion in matrix notation is taken to compute the block error distribution. By using an automata model of the channel-decoder-cascade, coset probabilities can be computed directly in an original domain. Alternatively, the analysis can be performed in a spectral domain having a simpler structure. The relationship between both domains is given by a Walsh-Hadamard transform. Aspects of implementation are discussed and examples are presented to illustrate the efficiency of the methodCommunications, 1996. ICC 96, Conference Record, Converging Technologies for Tomorrow's Applications. 1996 IEEE International Conference on; 07/1996