An Optical Surface Applicator for Intraoperative Photodynamic Therapy.

BACKGROUND AND OBJECTIVES: Intraoperative photodynamic therapy (IO-PDT) is typically administered by a handheld light source. This can result in uncontrolled distribution of light irradiance that impacts tissue and tumor response to photodynamic therapy. The objective of this work was to characterize a novel optical surface applicator (OSA) designed to administer controlled light irradiance in IO-PDT. STUDY DESIGN/MATERIALS AND METHODS: An OSA was constructed from a flexible silicone mesh applicator with multiple cylindrically diffusing optical fibers (CDF) placed into channels of the silicone. Light irradiance distribution, at 665 nm, was evaluated on the OSA surface and after passage through solid tissue-mimicking optical phantoms by measurements from a multi-channel dosimetry system. As a proof of concept, the light administration of the OSA was tested in a pilot study by conducting a feasibility and performance test with 665-nm laser light to activate 2-(1'-hexyloxyethyl) pyropheophorbide-a (HPPH) in the thoracic cavity of adult swine. RESULTS: At the OSA surface, the irradiance distribution was non-uniform, ranging from 128 to 346 mW/cm2 . However, in the tissue-mimicking phantoms, beam uniformity improved markedly, with irradiance ranges of 39-153, 33-87, and 12-28 mW/cm2 measured at phantom thicknesses of 3, 5, and 10 mm, respectively. The OSA safely delivered the prescribed light dose to the thoracic cavities of four swine. CONCLUSIONS: The OSA can provide predictable light irradiances for administering a well-defined and potentially effective therapeutic light in IO-PDT. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Prophylactic sternal plating with pectoralis advancement flaps after sternotomy in patients with a history of chest irradiation.

Deep sternal infections secondary to bony instability and malunion, can result in mediastinitis. Previous authors have described the use of prophylactic rigid plate fixation in high-risk patients. The purpose of our study is to review the use of prophylactic sternal platting with pectoralis advancement flaps in high-risk patients with a history of chest irradiation. Fourteen patients (July 2003-September 2008) with a history of chest irradiation who underwent a median sternotomy followed by prophylactic rigid plate fixation of the sternum were reviewed. Breast cancer was the most common etiology of chest irradiation (n=11, 78%). The average EuroSCORE was 24.06% with 72% of patients having a preoperative New York Heart Association (NYHA) class≥III. There were no episodes of sternal non-union, mediastinitis or death. Follow-up was 100% with a 0% 30-day and a 7.1% one-year mortality rate (non-cardiac). A comparison between mean preoperative left ventricular ejection fraction (LVEF) (49.6%) and postoperative LVEF (59.7%) was statistically significant (P<0.0001). All living patients currently maintain a NYHA class I/II. Prophylactic rigid plate fixation and pectoralis flap coverage decreases the risk of developing sternal dehiscence and postoperative wound complications and should therefore be considered in high-risk patients with a history of chest irradiation.

Extrapleural pneumonectomy, photodynamic therapy and intensity modulated radiation therapy for the treatment of malignant pleural mesothelioma.

Intensity modulated radiation therapy (IMRT) has recently been proposed for the treatment of malignant pleural mesothelioma (MPM). Here, we describe our experience with a multimodality approach for the treatment of mesothelioma, incorporating extrapleural pneumonectomy, intraoperative photodynamic therapy and postoperative hemithoracic IMRT. From 2004-2007, we treated 11 MPM patients with hemithoracic IMRT, 7 of whom had undergone porfimer sodium-mediated PDT as an intraoperative adjuvant to surgical debulking. The median radiation dose to the planning treatment volume (PTV) ranged from 45.4-54.5 Gy. For the contralateral lung, V20 ranged from 1.4-28.5%, V5 from 42-100% and MLD from 6.8-16.5 Gy. In our series, 1 patient experienced respiratory failure secondary to radiation pneumonitis that did not require mechanical ventilation. Multimodality therapy combining surgery with increased doses of radiation using IMRT, and newer treatment modalities such as PDT , appears safe. Future prospective analysis will be needed to demonstrate efficacy of this approach in the treatment of malignant mesothelioma. Efforts to reduce lung toxicity and improve dose delivery are needed and provide the promise of improved local control and quality of life in a carefully chosen multidisciplinary approach.