Robert C. DeNovo

Development of an advanced hyperspectral imaging (HSI) system with applications for cancer detection.

An advanced hyper-spectral imaging (HSI) system has been developed having obvious applications for cancer detection. This HSI system is based on state-of-the-art liquid crystal tunable filter technology coupled to an endoscope. The goal of this unique HSI technology being developed is to obtain spatially resolved images of the slight differences in luminescent properties of malignant versus non-malignant tissues. In this report, the development of the instrument is discussed and the capability of the instrument is demonstrated by observing mouse carcinomas in-vivo. It is shown that the instrument successfully distinguishes between normal and malignant mouse skin. It is hoped that the results of this study will lead to advances in the optical diagnosis of cancer in humans.

Balloon photodynamic therapy of esophageal cancer: Effect of increasing balloon size

Photodynamic therapy is currently being used to treat various malignancies including esophageal cancer. The effect of photodynamic therapy depends upon the concentration of photosensitizing drug, light energy delivered to tissue, and the presence of oxygen in the targeted tissue. We have found that an esophageal centering balloon improves light delivery to esophageal mucosa. However, balloon pressure on esophageal mucosa could possibly reduce mucosal blood flow and oxygenation, therefore reducing the effect of photodynamic therapy. This study was conducted to investigate the effect of balloon pressure on the esophageal wall during photodynamic therapy in the canine esophageal model.

A centering balloon for photodynamic therapy of esophageal cancer tested in a canine model.

Delivery of uniform circumferential light is desirable during photodynamic therapy of early or advanced esophageal cancer in human beings. Studies were performed in the canine esophagus to investigate whether use of a centering balloon would improve circumferential illumination of esophageal mucosa for photodynamic therapy of esophageal cancer. When the centering balloon was used, photodynamic therapy produced uniform and circumferential injury. With the cylindrical diffuser used in human studies, non-uniform and focal esophageal injury occurred. Placement of isotropic probes on the balloon wall allowed measurement and verification of relatively uniform light doses delivered to esophageal mucosa during balloon photodynamic therapy. The centering balloon has a potential role in improving light dosimetry during esophageal photodynamic therapy.

Dual modality fluorescence and reflectance hyperspectral imaging: principle and applications

We present the principles and applications of our dual-modality fluorescence and reflectance hyperspectral imaging (DMHSI) system. In this paper we report on background work done using laser induced fluorescence (LIF) by the group in the early detection of esophageal cancer. We then demonstrate the capabilities of our new DMHSI system. The system consists of a laser, endoscope, AOTF, and two cameras coupled with optics and electronics. Preliminary results, performed on mouse tissue, show that the system can delineate normal and malignant tissue regions in real-time.

Hiatal hernia and diaphragmatic eventration in a leopard ( Panthera pardus).

Abstract A 1-yr-old male leopard (Panthera pardus) presented for intermittent anorexia, emaciation, and generalized muscle wasting. Plain radiographs, ultrasonography, and esophageal endoscopy led to a diagnosis of diaphragmatic eventration with probable concurrent hiatal hernia. An exploratory laparotomy confirmed both diagnoses, and surgical repair and stabilization were performed. After surgery, the leopard was maintained on small liquid meals for 4 days, with a gradual return to normal diet over 2 wk. By 4 wk after surgery, the leopard was eating well and gaining weight, and it showed no recurrence of clinical signs for 2 yr subsequently, becoming mildly obese.

Development of a Fluorescence Detection System Using Optical Parametric Oscillator (OPO) Laser Excitation for in Vivo Diagnosis

In this work, the development and applications of a fluorescence detection system using optical parametric oscillator (OPO) laser excitation for in vivo disease diagnosis including oral carcinoma are described. The optical diagnosis system was based on an OPO laser for multi-wavelength excitation and time-resolved detection. The pulsed Nd-YAG-pumped OPO laser system (6 ns, 20 Hz) is compact and has a rapid, broad, and uniform tuning range. Time-gated detection of intensified charge-coupled device (ICCD) making use of external triggering was used to effectively eliminate the laser scattering and contribute to the highly sensitive in vivo measurements. Artificial tissue-simulating phantoms consisting of polystyrene microspheres and tissue fluorophores were tested to optimize the gating parameters. 51-ns gate width and 39-ns gate delays were determined to be the optimal parameters for sensitive detection. in vivo measurements with the optical diagnosis system were applied to esophagus, stomach, and small intestine using an endoscope in canine animal studies. The rapid tuning capability of the optical diagnosis system contributed greatly to the optimization of wavelength for the observation of porphyrin in the small intestine. When the small intestine was thoroughly washed with water, the emission band which corresponds to porphyrin disappeared. Based on this observation, it was concluded that the detected signal was yielded by porphyrin-containing bile secretion. Also, multispectral analyses using multiple excitations from 415 to 480 nm at 5 nm intervals confirmed the porphyrin detection in the small intestine. The optical diagnosis system was also applied to the detection of human xenograft of oral carcinoma in mice using 5-aminolevulinic acid (5-ALA) which is a photodynamic therapy (PDT) drug. Significant differences in protoporphyrin IX fluorescence intensity between normal and tumor tissue could be obtained 2 hours after the injection of 5-ALA into mice due to the preferential accumulation of 5-ALA in tumors. Results reported herein demonstrate potential capabilities of the LIF-OPO system for in vivo disease diagnosis.

Photodynamic therapy using Verteporfin and 630-nm laser light in canine esophagus

Objective: The goal ofthis study was to determine a relationship between light dose and the delay time between administration of Verteporfin and light to ablate canine esophageal mucosa. Materials and Methods: Verteporfin was administered IV (0.75 mg/lg). 630-nm light from KTP/Dye laser was delivered using a 9-cm diffuser inside a specially designed reflective 7-cm windowed balloon. Initially, animals were treated at doses of 160 J/cm, 180 J/cm, 200 J/cm, and 220 J/cm 2-3 hours after Verteporfin injection. Based on the acute response in these animals and the plasma Verteporfin clearance, other treatments were devised and tested at 60 J/cm (at 1 5 minutes), 80 J/cm (22 minutes), 100 J/cm (30 minutes), and 145 J/cm (60 minutes). Results: In initial animals, 200 J/cm at 2 hours induced acceptable mucosal ablation. Using this light dose and the plasma drug clearance, subsequent treatments were tested resulting in similar injuries using 60 3/cm (15 minutes), 80 3/cm (22 minutes), 100 3/cm (30 minutes), and 145 J/cm (60 minutes). Conclusions: A relationship was established relating the light dose and the delay time between administration oflight and Verteporfin for ablation ofnormal canine esophageal mucosa.

Balloon photodynamic therapy of esophageal cancer: effect of increasing balloon size

We have found that an esophageal centering balloon improves light delivery to esophageal mucosa during photodynamic therapy (PDT). However, balloon pressure on esophageal mucosa could possibly reduce mucosal blood flow and oxygenation, therefore reducing the photodynamic therapy effect. Studies were performed in the canine esophagus of 10 animals to investigate whether increasing the size of the centering balloon and hence the pressure on esophageal mucosa would alter the tissue effect of PDT. It was concluded that increasing balloon size resulted in reduced tissue damage when mucosal equivalent light dose was administered during photodynamic therapy. Proper sizing of centering balloons will be necessary for balloon PDT of esophageal mucosal dysplasia or cancer.

Comparison between pulsed and continuous-wave lasers for photodynamic therapy

A study was conducted in the normal canine esophagus to compare continuous wave (argon- pumped dye-laser) and pulsed (KTP/532-pumped dye-laser) laser light for photodynamic therapy with PHOTOFRINR. 48 hours post injection, 630 nm laser light was delivered using a 24 mm diameter cylindrical esophageal PDT balloon positioned at either distal or proximal esophagus. A 1.0 cm cylindrical diffuser placed in the center of the balloon delivered 300 J/cm of light at an intensity of 400 mW/cm. Three dogs received continuous wave (CW) light proximally and pulsed light distally. Four dogs received CW light distally and pulsed light proximally. The light dose delivered to the esophageal mucosa was measured using three isotropic probes placed on the balloon wall. Similar mucosal light doses were verified for sites receiving pulsed or CW laser light. Two days after PDT, the severity of the esophageal lesions were evaluated endoscopically, grossly and histologically. While some response variability was observed among different animals, endoscopic examination of the lesions revealed comparable injury from CW and pulsed light in each subject. Based on the gross and histological examination of the lesions, the CW and pulsed laser-induced injuries could not be distinguished.