Utility of high-resolution ultrasound in measuring subcutaneous fat thickness.

OBJECTIVE: Previous studies conclude that high-resolution ultrasound (HRUS) enables noninvasive and accurate measurements of subcutaneous fat thickness. The primary objective of this cross-sectional study was to better characterize subcutaneous fat thickness measurements in a diverse patient population using HRUS. Secondarily, we sought to correlate these measurements with patients' body image. METHODS: A cross-sectional study to measure subcutaneous fat measurements at seven distinct anatomic sites, including upper and lower extremities, submental, and torso regions, in 40 men and women of different ages and races using HRUS. Independent t-tests and analysis of variance were performed to analyze findings. RESULTS: In our patient population, on average, women had thicker subcutaneous fat than men at all anatomic sites. Asian patients had significantly reduced fat thickness at peripheral anatomic sites, such as arms when compared to patients who identified as Black and Other (p = 0.05 and p = 0.008, respectively). Lastly, women reported decreased total body satisfaction at all anatomic sites when compared to men. CONCLUSION: The information obtained and methods developed in this study may be utilized clinically during patient selection for fat reduction procedures, including for estimating the degree of likely benefit; for managing pathologies involving subcutaneous fat thickness alteration; and to monitor the progression of lipodystrophy secondary to disease or drugs.

Ultrasound for Aesthetic Applications: A Review of Biophysical Mechanisms and Safety.

Aesthetic ultrasound is used for fat reduction and to improve skin appearance. In this review, the fundamental mechanisms by which ultrasound can alter tissue are outlined. The technologies that are commercially available or under development are discussed. Finally, recommendations are made for safe and effective use of aesthetic ultrasound.

Subcutaneous infiltration of carbon dioxide (carboxytherapy) for abdominal fat reduction: A randomized clinical trial.

BACKGROUND: Noninvasive fat removal is preferred because of decreased downtime and lower perceived risk. It is important to seek new noninvasive fat removal treatments that are both safe and efficacious. OBJECTIVE: To assess the extent to which carboxytherapy, which is the insufflation of carbon dioxide gas into subcutaneous fat, results in reduction of fat volume. METHODS: In this randomized, sham-controlled, split-body study, adults (body mass index, 22-29 kg/m2) were randomized to receive 5 weekly infusions of 1000 cm3 of CO2 to 1 side of the abdomen, and 5 sham treatments to the contralateral side. The primary outcome measures were ultrasound measurement of fat layer thickness and total circumference before and after treatment. RESULTS: A total of 16 participants completed the study. Ultrasound measurement indicated less fat volume on the side treated with carboxytherapy 1 week after the last treatment (P = .011), but the lower fat volume was not maintained at 28 weeks. Total circumference decreased nominally but not significantly at week 5 compared with baseline (P = .0697). Participant body weights did not change over the entire course of the study (P = 1.00). LIMITATIONS: Limitations included modest sample size and some sources of error in the measurement of circumference and fat layer. CONCLUSION: Carboxytherapy provides a transient decrease in subcutaneous fat that may not persist. Treatment is well tolerated.

Effects of a focused training on first-year osteopathic medical students' ability to incorporate point-of-care ultrasound in assessment of the anterior knee.

CONTEXT: Patients frequently present to the outpatient clinic, urgent care, or emergency department with a painful, swollen knee. Differentiating the underlying etiology can be a challenge for both medical students and seasoned clinicians alike. Because this scenario can represent a time-sensitive emergency, developing skills to diagnose the underlying cause quickly and accurately is essential for proper management, whether the patient would benefit from osteopathic manipulation, prompt administration of antibiotics, or a more invasive procedure like joint aspiration or surgery. OBJECTIVES: The objectives are to determine the effects of a focused ultrasound training on first-year osteopathic medical students' ability to identify normal sonographic anatomy of the anterior knee and to differentiate between three common pathologies: joint effusion, prepatellar bursitis, and cellulitis. METHODS: First-year osteopathic medical students voluntarily participated in this cross-sectional study. The study protocol included a focused ultrasound training (online materials, brief didactic and single hands-on sessions) followed by a hands-on assessment. A written test and 5-point Likert scale questionnaire were administered before and after the focused training. Nine weeks later, students completed a follow-up written test. The proportion of students who correctly identified common pathologies on written tests before (pretest) and after (posttest) training and on the follow-up written test were compared utilizing the Fisher's exact test. A t test was utilized to compare data from the pretraining and posttraining questionnaires. RESULTS: Of 101 students completing the written pretest and pretraining questionnaire, 95 (94.1 %) completed the written posttest and posttraining questionnaire, and 84 (83.2 %) completed the follow-up written test. Students had limited previous experience with ultrasound; 90 (89.1 %) students had performed six or fewer ultrasound examinations before the focused ultrasound training. On written tests, students accurately identified joint effusion (22.8 % [23/101] pretest, 65.3 % [62/95] posttest, 33.3 % [28/84] follow-up test), prepatellar bursitis (14.9 % [15/101] pretest, 46.3 % [44/95] posttest, 36.9 % [31/84] follow-up test), and cellulitis (38.6 % [39/101] pretest, 90.5 % [86/95] posttest, 73.8 % [62/84] follow-up test). Differences were found between pretest and posttest for identification of all three pathologies (all p<0.001) and between the pretest and 9-week follow-up test for identification of prepatellar bursitis and cellulitis (both p≤0.001). For questionnaires, (where 1=strongly agree, 5=strongly disagree), the mean (standard deviation [SD]) confidence for correctly identifying normal sonographic anatomy of the anterior knee was 3.50 (1.01) at pretraining and 1.59 (0.72) at posttraining. Student confidence in the ability to differentiate joint effusion, prepatellar bursitis, and cellulitis utilizing ultrasound increased from 4.33 (0.78) at pretraining to 1.99 (0.78) at posttraining. For the hands-on assessment, 78.3 % (595 correct/760 aggregated responses) of the time students correctly identified specific sonographic landmarks of the anterior knee. When the evaluation combined real-time scanning with a prerecorded sonographic video clip of the anterior knee, 71.4 % (20/28) accurately identified joint effusion, 60.9 % (14/23) correctly diagnosed prepatellar bursitis, 93.3 % (28/30) recognized cellulitis, and 47.1 % (8/17) diagnosed the normal knee. CONCLUSIONS: Our focused training was effective at immediately increasing basic knowledge, as well as confidence of first-year osteopathic medical students when assessing the anterior knee with point-of-care ultrasound. However, spaced repetition and deliberate practice may be useful for learning retention.

Temporal evaluation of efficacy and quality of tissue repair upon laser-activated sealing.

Injuries caused by surgical incisions or traumatic lacerations compromise the structural and functional integrity of skin. Immediate approximation and robust repair of skin are critical to minimize occurrences of dehiscence and infection that can lead to impaired healing and further complication. Light-activated skin sealing has emerged as an alternative to sutures, staples, and superficial adhesives, which do not integrate with tissues and are prone to scarring and infection. Here, we evaluate both shorter- and longer-term efficacy of tissue repair response following laser-activated sealing of full-thickness skin incisions in immunocompetent mice and compare them to the efficacy seen with sutures. Laser-activated sealants (LASEs) in which, indocyanine green was embedded within silk fibroin films, were used to form viscous pastes and applied over wound edges. A hand-held, near-infrared laser was applied over the incision, and conversion of the light energy to heat by the LASE facilitated rapid photothermal sealing of the wound in approximately 1 min. Tissue repair with LASEs was evaluated using functional recovery (transepidermal water loss), biomechanical recovery (tensile strength), tissue visualization (ultrasound [US] and photoacoustic imaging [PAI]), and histology, and compared with that seen in sutures. Our studies indicate that LASEs promoted earlier recovery of barrier and mechanical function of healed skin compared to suture-closed incisions. Visualization of sealed skin using US and PAI indicated integration of the LASE with the tissue. Histological analyses of LASE-sealed skin sections showed reduced neutrophil and increased proresolution macrophages on Days 2 and 7 postclosure of incisions, without an increase in scarring or fibrosis. Together, our studies show that simple fabrication and application methods combined with rapid sealing of wound edges with improved histological outcomes make LASE a promising alternative for management of incisional wounds and lacerations.

Overview of therapeutic ultrasound applications and safety considerations.

Applications of ultrasound in medicine for therapeutic purposes have been accepted and beneficial uses of ultrasonic biological effects for many years. Low-power ultrasound of about 1 MHz has been widely applied since the 1950s for physical therapy in conditions such as tendinitis and bursitis. In the 1980s, high-pressure-amplitude shock waves came into use for mechanically resolving kidney stones, and "lithotripsy" rapidly replaced surgery as the most frequent treatment choice. The use of ultrasonic energy for therapy continues to expand, and approved applications now include uterine fibroid ablation, cataract removal (phacoemulsification), surgical tissue cutting and hemostasis, transdermal drug delivery, and bone fracture healing, among others. Undesirable bioeffects can occur, including burns from thermal-based therapies and severe hemorrhage from mechanical-based therapies (eg, lithotripsy). In all of these therapeutic applications of ultrasound bioeffects, standardization, ultrasound dosimetry, benefits assurance, and side-effect risk minimization must be carefully considered to ensure an optimal benefit to risk ratio for the patient. Therapeutic ultrasound typically has well-defined benefits and risks and therefore presents a manageable safety problem to the clinician. However, safety information can be scattered, confusing, or subject to commercial conflicts of interest. Of paramount importance for managing this problem is the communication of practical safety information by authoritative groups, such as the American Institute of Ultrasound in Medicine, to the medical ultrasound community. In this overview, the Bioeffects Committee of the American Institute of Ultrasound in Medicine outlines the wide range of therapeutic ultrasound methods, which are in clinical use or under study, and provides general guidance for ensuring therapeutic ultrasound safety.

Selective creation of thermal injury zones in the superficial musculoaponeurotic system using intense ultrasound therapy: a new target for noninvasive facial rejuvenation.

OBJECTIVES: To transcutaneously deliver intense ultrasound (IUS) energy to target the facial superficial musculoaponeurotic system (SMAS), to produce discrete thermal injury zones (TIZs) in the SMAS, and to demonstrate the relative sparing of adjacent nontargeted layers superficial and deep to the SMAS layer. METHODS: In 6 unfixed human cadaveric specimens, the SMAS layer was visualized and targeted using the ultrasound imaging component of the IUS device. Using 2 IUS handpieces, 202 exposure lines were delivered bilaterally in multiple facial regions by varying combinations of power and exposure time (0.5-8.0 J). Tissue was then excised and examined grossly and histologically for evidence of thermal injury using nitroblue tetrazolium chloride viability stain. RESULTS: Reproducible TIZs were produced selectively in the SMAS at depths of up to 7.8 mm, and sparing of surrounding tissue including the epidermis. Higher energy settings and high-density exposure line pattern produced a greater degree of tissue shrinkage. CONCLUSIONS: In human cadaveric facial tissue, IUS can noninvasively target and selectively produce TIZs of reproducible location, size, and geometry in the SMAS layer. The ability to produce focused thermal collagen denaturation in the SMAS to induce shrinkage and tissue tightening has not been previously reported and has significant implications for aesthetic facial rejuvenation.

Clinical pilot study of intense ultrasound therapy to deep dermal facial skin and subcutaneous tissues.

OBJECTIVE: To evaluate the clinical safety of intense ultrasound in the treatment of the dermis and subcutaneous tissues of the face and neck in terms of skin inflammation, pain, adverse events, and histologic features. DESIGN: In an open-label, phase 1 study, patients scheduled to undergo a rhytidectomy were enrolled into immediate (face-lift surgery within 24 hours of intense ultrasound treatment) and delayed (face-lift surgery 4-12 weeks after treatment) treatment groups. Intense ultrasound treatments were performed as a series of several linear exposures delivered 1.5 to 2.0 mm apart with the use of 1 of 3 available handpieces with different focal depths. Subject pain ratings and standardized digital photographs were obtained at uniform points. Photographs were blindly rated for inflammation. Histologic evaluation of treated tissues was performed with nitroblue tetrazolium chloride viability stain. RESULTS: Fifteen subjects with a mean +/- SD age of 53 +/- 7 years were enrolled. Seven subjects were nonrandomly assigned to the immediate group and 8 were in the delayed group. On histologic examination, thermal injury zones were consistently identified in the dermis at exposure levels greater than 0.5 J as focal areas of denatured collagen. At this threshold level or above, most patient exposures were associated with transient superficial skin erythema and slight to mild discomfort on a standardized pain scale. No other adverse effects were noted in any case. Thermal injury zones were produced in the expected linear pattern and were consistent in size and depth from zone to zone. Increasing source power did not increase the depth of the epicenter of the thermal injury zone. Epidermis was spared in all cases. CONCLUSION: In this first clinical study of intense ultrasound therapy to facial tissues, the intense ultrasound system allowed for the safe and well-tolerated placement of targeted, precise, and consistent thermal injury zones in the dermis and subcutaneous tissues with sparing of the epidermis.

In vivo demonstration of ultrasound power delivery to charge implanted medical devices via acute and survival porcine studies.

Animal studies are an important step in proving the utility and safety of an ultrasound based implanted battery recharging system. To this end an Ultrasound Electrical Recharging System (USER™) was developed and tested. Experiments in vitro demonstrated power deliveries at the battery of up to 600 mW through 10-15 mm of tissue, 50 mW of power available at tissue depths of up to 50 mm, and the feasibility of using transducers bonded to titanium as used in medical implants. Acute in vivo studies in a porcine model were used to test reliability of power delivery, temperature excursions, and cooling techniques. The culminating five-week survival study involved repeated battery charging, a total of 10.5h of ultrasound exposure of the intervening living tissue, with an average RF input to electrical charging efficiency of 20%. This study was potentially the first long term cumulative living-tissue exposure using transcutaneous ultrasound power transmission to an implanted receiver in situ. Histology of the exposed tissue showed changes attributable primarily due to surgical implantation of the prototype device, and no damage due to the ultrasound exposure. The in vivo results are indicative of the potential safe delivery of ultrasound energy for a defined set of source conditions for charging batteries within implants.

Multiplex real-time PCR detection and relative quantification of periodontal pathogens.

Periodontitis is a chronic inflammatory disease, which is strongly associated with certain pathogenic bacteria. The aim of this study was to develop a real-time multiplex polymerase chain reaction (PCR) assay to detect and quantify bacterial species associated with periodontitis. We targeted detection and relative quantification of the following five bacterial species relevant to periodontal diseases: Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. The conserved regions of the genome of these species were targeted with oligos and TaqMan probes in real-time PCR assays. The species-specific TaqMan oligos and TaqMan probes showed no cross-amplification, and there was no loss of amplification yield in multiplex real-time PCR assays. All five bacterial targets were amplified analogous to the template concentrations used in these assays. This multiplex real-time PCR strategy could potentially be used to detect the bacterial species in periodontal pockets of patients with periodontal diseases. This assay may also serve as a quick tool for profiling and quantifying bacteria relevant to periodontal diseases and likely be a valuable tool for clinical translational research.

Miniaturized ultrasound arrays for interstitial ablation and imaging.

A potential alternative to extracorporeal, noninvasive HIFU therapy is minimally invasive intense ultrasound ablation that can be performed laparoscopically or percutaneously. An approach to minimally invasive ablation of soft tissue using miniaturized linear ultrasound arrays is presented here. Recently developed 32-element arrays with aperture 2.3 x 49 mm, therapy frequency 3.1 MHz, pulse-echo bandwidths >42% and surface acoustic energy density >80 W/cm2, are described. These arrays are integrated into a probe assembly, including a coupling balloon and piercing tip, suitable for interstitial ablation. An integrated electronic control system allows therapy planning and automated treatment guided by real-time interstitial B-scan imaging. Image quality, challenging because of limited probe dimensions and channel count, is aided by signal processing techniques that improve image definition and contrast, resulting in image quality comparable to typical transabdominal ultrasound imaging. Ablation results from ex vivo and in vivo experiments on mammalian liver tissue show that this approach is capable of ablation rates and volumes relevant to clinical applications of soft tissue ablation such as treatment of liver cancer.

Assessment of skin blood flow following spinal manual therapy: a systematic review.

Skin blood flow (SBF) indexes have been used to describe physiological mechanisms associated with spinal manual therapy (SMT). The aims of the current review were to assess methods for data collection, assess how investigators interpreted SBF changes, and formulate recommendations to advance manual medicine research. A database search was performed in PubMed, Cochrane Library, the Physiotherapy Evidence Database, and the Cumulative Index to Nursing and Allied Health Literature through April 2014. Articles were included if at least 1 outcome measure was changes in 1 SBF index following SMT. The database search yielded 344 records. Two independent authors applied the inclusion criteria. Twenty studies met the inclusion criteria. Selected studies used heterogeneous methods to assess short-term post-SMT changes in SBF, usually vasoconstriction, which was interpreted as a general sympathoexcitatory effect through central mechanisms. However, this conclusion might be challenged by the current understanding of skin sympathetic nervous activity over local endothelial mechanisms that are specifically controlling SBF. Evaluation of SBF measurements in peripheral tissues following SMT may document physiological responses that are beyond peripheral sympathetic function. Based on the current use of SBF indexes in clinical and physiological research, 14 recommendations for advancing manual medicine research using laser Doppler flowmetry are presented.

Developing technology-enhanced active learning for medical education: challenges, solutions, and future directions.

Growing up in an era of video games and Web-based applications has primed current medical students to expect rapid, interactive feedback. To address this need, the A.T. Still University-School of Osteopathic Medicine in Arizona (Mesa) has developed and integrated a variety of approaches using technology-enhanced active learning for medical education (TEAL-MEd) into its curriculum. Over the course of 3 years (2010-2013), the authors facilitated more than 80 implementations of games and virtual patient simulations into the education of 550 osteopathic medical students. The authors report on 4 key aspects of the TEAL-MEd initiative, including purpose, portfolio of tools, progress to date regarding challenges and solutions, and future directions. Lessons learned may be of benefit to medical educators at academic and clinical training sites who wish to implement TEAL-MEd activities.

Use of real-time physiologic parameter assessment to augment osteopathic manipulative treatment training for first-year osteopathic medical students.

CONTEXT: The first 2 years of osteopathic medical school involve training in osteopathic principles and practice, including understanding the tenets of osteopathic medicine and developing palpatory skills for clinical application. Although this training emphasizes the link between somatic dysfunction and physiologic function, it does not include the opportunity for students to quantitatively assess the physiologic effect of osteopathic manipulative treatment (OMT) using physiologic measurements. OBJECTIVE: To evaluate an approach for integrated OMT training coupled with physiologic measurements of relevant parameters, whereby first-year osteopathic medical students assess the quantitative, real-time changes in specific physiologic signals during instruction. METHODS: During mandatory musculoskeletal and cardiovascular demonstration laboratories at a single osteopathic medical school, students were divided into small groups and performed OMT on each other while recording real-time measurements of physiologic functions such as maximum clench force, time to fatigue for the forearm flexor muscles, heart rate, and peripheral vascular flow. After data were collected, students analyzed pre- and post-OMT measurements and discussed underlying physiologic principles in a large group format. At the end of the sessions, students completed a brief survey on the usefulness of the integrated laboratories. RESULTS: Overall, 13 of 28 student groups (46.4%) measured a pre- to post-OMT increase in maximum clench force, and 16 (57.1%) observed an increase in time to fatigue for the forearm flexor muscles. Twenty-three of 27 student groups (85.2%) observed a reduction in heart rate and 19 (70.4%) measured an increase in peripheral vascular flow after OMT. Student satisfaction was generally favorable, with overall mean (SD) ratings of 6.38 (1.86) for the musculoskeletal laboratory and 7.81 (1.69) for the cardiovascular laboratory out of a maximum of 10 points. In open-ended comments, students deemed the combined laboratories as clinically applicable but desired more time for completing the laboratories. CONCLUSION: Measurement of specific physiologic musculoskeletal and cardiovascular parameters before and after OMT enabled quantification of physiologic responses to OMT. Students' favorable feedback indicated that the quality of learning in the laboratories was enhanced by the addition of physiologic measurements.

Training and use of lasers in postgraduate orthodontic programs in the United States and Canada.

This study was designed to determine if orthodontic residents are being trained to use lasers in the postgraduate orthodontic residency programs of the United States and Canada. An anonymous electronic survey was sent to the program director/chair of each of the seventy orthodontic residency programs, and thirty-seven (53 percent) of the programs responded. Of these thirty-seven programs, twenty-eight (76 percent) reported providing patient treatment with lasers in the orthodontic graduate program, eight (22 percent) said they do not provide treatment in the orthodontic graduate program, and one program (3 percent) reported providing laser training but not using lasers on patients. Gingivectomy and canine exposure were reported as the most common procedures that residents perform with a laser, while debonding of orthodontic brackets was the least common procedure performed with a laser. A diode laser was the most common type of laser used. Of the eight programs (22 percent) not offering laser training, four indicated having no plans to begin using lasers or training on their use. The other four indicated that they have plans to incorporate laser use in the future.

Treatment of rabbit liver cancer in vivo using miniaturized image-ablate ultrasound arrays.

In the preclinical studies reported here, VX2 cancer within rabbit liver has been treated by bulk ultrasound ablation employing miniaturized image-ablate arrays. Array probes were constructed with 32 elements in a 2.3 × 20 mm(2) aperture, packaged within a 3.1 mm stainless steel tube with a cooling and coupling balloon for in vivo use. The probes were measured capable of 50% fractional bandwidth for pulse-echo imaging (center frequency 4.4 MHz) with >110 W/cm(2) surface intensity available at sonication frequencies 3.5 and 4.8 MHz. B-scan imaging performance of the arrays was measured to be comparable to larger diagnostic linear arrays, although nearfield image quality was reduced by ringdown artifacts. A series of in vivo ablation procedures was performed using an unfocused 32-element aperture firing at 4.8 MHz with exposure durations 20-70.5 s and in situ spatial average, temporal average intensities 22.4-38.5 W/cm(2). Ablation of a complete tumor cross-section was confirmed by vital staining in seven of 12 exposures, with four exposures ablating an additional margin >1 mm beyond the tumor in all directions. Analysis suggests a threshold ablation effect, with complete ablation of tumor cross-sections for exposures with delivery of >838 J acoustic energy. The results show feasibility for in vivo liver cancer ablation using miniaturized image-ablate arrays suitable for interstitial deployment.

Selective transcutaneous delivery of energy to porcine soft tissues using Intense Ultrasound (IUS).

OBJECTIVE: Various energy delivery systems have been utilized to treat superficial rhytids in the aging face. The Intense Ultrasound System (IUS) is a novel modality capable of transcutaneously delivering controlled thermal energy at various depths while sparing the overlying tissues. The purpose of this feasibility study was to evaluate the response of porcine tissues to various IUS energy source conditions. Further evaluation was performed of the built-in imaging capabilities of the device. MATERIALS AND METHODS: Simulations were performed on ex vivo porcine tissues to estimate the thermal dose distribution in tissues after IUS exposures to determine the unique source settings that would produce thermal injury zones (TIZs) at given depths. Exposures were performed at escalating power settings and different exposure times (in the range of 1-7.6 J) using three IUS handpieces with unique frequencies and focal depths. Ultrasound imaging was performed before and after IUS exposures to detect changes in tissue consistency. Porcine tissues were examined using nitro-blue tetrazolium chloride (NBTC) staining sensitive for thermal lesions, both grossly and histologically. The dimensions and depth of the TIZs were measured from digital photographs and compared. RESULTS: IUS can reliably achieve discrete, TIZ at various depths within tissue without surface disruption. Changes in the TIZ dimensions and shape were observed as source settings were varied. As the source energy was increased, the thermal lesions became larger by growing proximally towards the tissue surface. Maximum lesion depth closely approximated the pre-set focal depth of a given handpiece. Ultrasound imaging detected well-demarcated TIZ at depths within the porcine muscle tissue. CONCLUSION: This study demonstrates the response of porcine tissue to various energy dose levels of Intense Ultrasound. Further study, especially on human facial tissue, is necessary in order to understand the utility of this modality in treating the aging face and potentially, other cosmetic applications.

Bulk ablation of soft tissue with intense ultrasound: modeling and experiments.

Methods for the bulk ablation of soft tissue using intense ultrasound, with potential applications in the thermal treatment of focal tumors, are presented. An approximate analytic model for bulk ablation predicts the progress of ablation based on tissue properties, spatially averaged ultrasonic heat deposition, and perfusion. The approximate model allows the prediction of threshold acoustic powers required for ablation in vivo as well as the comparison of cases with different starting temperatures and perfusion characteristics, such as typical in vivo and ex vivo experiments. In a full three-dimensional numerical model, heat deposition from array transducers is computed using the Fresnel approximation and heat transfer in tissue is computed by finite differences, accounting for heating changes caused by boiling and thermal dose-dependent absorption. Similar ablation trends due to perfusion effects are predicted by both the simple analytic model and the full numerical model. Comparisons with experimental results show the efficacy of both models in predicting tissue ablation effects. Phenomena illustrated by the simulations and experiments include power thresholds for in vivo ablation, differences between in vivo and ex vivo lesioning for comparable source conditions, the effect of tissue boiling and absorption changes on ablation depth, and the performance of a continuous rotational scanning method suitable for interstitial bulk ablation of soft tissue.