Vikki Hazelwood

Confocal mosaicing microscopy of human skin ex vivo : spectral analysis for digital staining to simulate histology-like appearance

Confocal mosaicing microscopy enables rapid imaging of large areas of fresh tissue, without the processing that is necessary for conventional histology. Mosaicing may offer a means to perform rapid histology at the bedside. A possible barrier toward clinical acceptance is that the mosaics are based on a single mode of grayscale contrast and appear black and white, whereas histology is based on two stains (hematoxylin for nuclei, eosin for cellular cytoplasm and dermis) and appears purple and pink. Toward addressing this barrier, we report advances in digital staining: fluorescence mosaics that show only nuclei, are digitally stained purple and overlaid on reflectance mosaics, which show only cellular cytoplasm and dermis, and are digitally stained pink. With digital staining, the appearance of confocal mosaics mimics the appearance of histology. Using multispectral analysis and color matching functions, red, green, and blue (RGB) components of hematoxylin and eosin stains in tissue were determined. The resulting RGB components were then applied in a linear algorithm to transform fluorescence and reflectance contrast in confocal mosaics to the absorbance contrast seen in pathology. Optimization of staining with acridine orange showed improved quality of digitally stained mosaics, with good correlation to the corresponding histology.

Biomedical engineering principles

Introduction: Modeling of Physiological Processes Cell Physiology and Transport Principles and Biomedical Applications of Hemodynamics A Systems Approach to Physiology The Cardiovascular System Biomedical Signal Processing Signal Acquisition and Processing Techniques for Physiological Signal Processing Examples of Physiological Signal Processing Principles of Biomechanics Practical Applications of Biomechanics Biomaterials Principles of Biomedical Capstone Design Unmet Clinical Needs Entrepreneurship: Reasons why Most Good Designs Never Get to Market An Engineering Solution in Search of a Biomedical Problem to Solve Tissue Engineering Future Trends in BME

Body Mass Index and Abdominal Ultrasound Image Quality A Pilot Survey of Sonographers

The objective was to assess the consensus among sonographers that the quality of abdominal ultrasound (US) images is related to the patient’s body mass index (BMI). Fourteen sonographers completed a 12-item questionnaire to evaluate their experience with abdominal US imaging with respect to image quality in correlation with the patient’s adipose tissue. Of the sonographers sampled, 85.7% agreed that there is an association between the amount of adipose tissue on a patient’s abdomen and the quality of US image obtained; 85.7% also agreed that a normal BMI of 18.5 to 24.9 provides the best US image. However, only 28.6% agreed that normal amounts of adipose tissue produce poor image quality. There appears to be agreement among sonographers that BMI is a factor in obtaining good quality abdominal US images. The general consensus was that the best abdominal US images were obtained in patients with normal BMI, whereas images obtained from patients with BMI 30.0 to 34.9 and to a lesser extent BMI 25.0 to 29.9 were limited in quality.

Evaluating the effect of bit rate on the quality of portable ultrasound video

This study analyzes the effect of bit rate on real time, wireless, and secure medical ultrasound video transmission quality. In order to achieve a thorough quality analysis, transmitted ultrasound video of varying bit rates was analyzed through both objective and subjective assessments. Objective assessment calculations of peak signal to noise ratio (PSNR) and structural similarity index (SSIM) indicate that as bit rate decreases, ultrasound video quality also decreases. For subjective assessments, ultrasound trained medical professionals evaluated the video and rated its quality using Mean Opinion Scores. The resulting data is used to develop a minimum bit rate threshold to ensure transmitted video is of adequate quality so that physicians may make an accurate diagnosis. A correlation is made and a minimum bit rate threshold of 1 Mbps is established. This bit rate threshold is the first quality standard for real time wirelessly transmitted ultrasound video, is needed to optimize quality and time delay, and can provide a reference bit rate for the transmission of other types of medical video.

A novel electrocautery device to increase coagulation rate and reduce thermal damage

Bleeding results in all surgical procedures. Current methods of coagulation result in thermal damage due to lack of thermal control. Tissue sticking to device tips as well as operating room fires are also common problems in current electrocautery and electrosurgery devices. We proposed to reduce bleeding and decrease thermal damage by designing an electrocautery device that transmits heat via conduction. The novel designs of the device will overcome the problems associated with current cautery and electrosurgery devices. Using three tests: set point determination, comparision to Bovie Cautery Pen, and stimulated perfusion, it is expected that the newly designed electrocautery device will reduce bleeding at a faster rate than existing methods without conductory danger and decreased thermal damage.

Use of loss of resistance, to carbon dioxide, in identifying the epidural space

1. Bernards CM. Epidural and spinal anesthesia. In: Barash PG, Cullen FB, Stoelting RK, Cahalan MK, Stock MC, editors. Clinical Anesthesia. 6th ed. Philadelphia:Lippincott William and Wilkins; 2009.p. 927-54. 2. Horlocker T. Neurologic complications of regional anesthesia. In: Complications of central Neuraxial blockade. ANZCA: Asm20006. 3. Michael GR, Richard NW. The effects of needle bevel orientation during epidural catheter insertion in laboring parturients. Anesth Analg 1999;88:352-6. 4. Cappiello E, Tsen LC. Complications and side effects of central neuraxial techniques. In: Cynthia AW, Cynthia W, editor. A complete hands-on guide to todays spinal and epidural anesthesia practice. New York: McGraw-Hill Professional; 2006. p. 151-82. 5. Horlocker TT. Complications of spinal and epidural anesthesia. Anesthesiol Clin North Am 2000;18:461-85. 6. Auroy Y, Narchi P, Messiah A, Litt L, Rouvier B, Samii K. Serious complications related to regional anesthesia. Anesthesiology 1997;87:479-86. 7. Myers RR, Sommer C. Methodology for spinal neurotoxicity studies. Reg Anesth 1993;18:439-47.

Heated humidified air for hypothermic resuscitation

In a battlefield setting, current re-warming techniques for treating patients suffering from hypothermia are inadequate, resulting in unnecessary morbidity and mortality. The authors propose the application of heated, humidified air to a patients airway as a complement to pre-existing hypothermia treatment techniques in order to improve this deficiency.

Epidural space localization with CO 2 and compliance

An increasing number of complications associated with standard loss of resistance (LOR) technique used during epidural injections shows a growing need for an improvement in correct identification of epidural space and minimization of possible risks. A prototype was constructed for delivery CO2 gas into a standard epidural syringe and coupled with compliance sensing apparatus to evaluate effectiveness of localization of the epidural space in bovine spine sections. The safety of the prototype was tested under pressurized conditions. The accuracy of the compliance measurement was tested in muscle, cartilage, and adipose tissues. The CO2 delivery system failure was estimated at approximately 50 psi. The prototypes level of sensitivity correctly distinguished a change in compliance during the perforation of the adipose tissue in epidural space.

Confocal mosaicing microscopy of basal-cell carcinomas ex vivo: progress in digital staining to simulate histology-like appearance

Confocal mosaicing microscopy enables rapid imaging of large areas of fresh tissue, without the processing that is necessary for conventional histology. Using acridine orange (1 milliMolar, 20 seconds) to stain nuclei, basal cell carcinomas were detected in fluorescence confocal mosaics of Mohs surgical excisions with sensitivity of 96.6% and specificity of 89.2%. A possible barrier toward clinical acceptance is that confocal mosaics are based on a single mode of contrast and appear in grayscale, whereas histology is based on two (hematoxylin for nuclei, eosin for cellular cytoplasm and dermis) and appears purple-and-pink. Toward addressing this barrier, we report progress in developing a multispectral analytical model for digital staining: fluorescence confocal mosaics, which show only nuclei, are digitally stained purple and overlaid on reflectance confocal mosaics, which show only cellular cytoplasm and dermis, and digitally stained pink, to mimic the appearance of histology. Comparison of digitally stained confocal mosaics by our Mohs surgeon to the corresponding Mohs histology shows good correlation for normal and tumor detail. Digitally stained confocal mosaicing microscopy may allow direct examination of freshly excised tissue and serve as an adjunct for rapid pathology at-the-bedside.

Agreement between clinical methods for the assessment of body fat

In recent years, the medical community and the public have become more aware that body composition assessment is an important factor in combating obesity. Various body composition methods exist, both for research and clinical use. A study was conducted on fifty-four (n=54) young adults, of varying body build, in order to evaluate bioelectrical impedance analysis (BIA) and skinfold thickness (SKF) measurements. By means of results from measurements by SKF and BIA, an attempt has been made to asses the agreement between the methods for the prediction of the quantity of fat in the body. Body fat percentage (BF%) was the primary outcome variable. The mean BF% (plusmnSD) that resulted from the SKF device was 19.96 (plusmn7.51) and was not statistically different from the leg-to-leg BIA result of 20.15 (plusmn7.74). However, the arm-to-arm 16.27 (plusmn8.03) BIA results for BF% were statistically different from both the SKF and the leg-to-leg BIA by a post ANOVA Tukeys Multiple Comparison test. As previous papers have suggested, the results of this study indicate several factors that limit the valid applications of both BIA and SKF measurements. A direction for effective improvement is provided.