BACKGROUND AND OBJECTIVE
Focused ultrasound can produce thermal and/or mechanical effects deep within tissue. We investigated the capability of intense focused ultrasound to induce precise and ...predictable subepidermal thermal damage in human skin.
MATERIALS AND METHODS
Postmortem human skin samples were exposed to a range of focused ultrasound pulses, using a prototype device (Ulthera Inc.) emitting up to 45 W at 7.5 MHz with a nominal focal distance of 4.2 mm from the transducer membrane. Exposure pulse duration ranged from 50 to 200 ms. Thermal damage was confirmed by light microscopy using a nitroblue tetrazolium chloride assay, as well as by loss of collagen birefringence in frozen sections. Results were compared with a computational model of intense ultrasound propagation and heating in tissue.
RESULTS
Depth and extent of thermal damage were determined by treatment exposure parameters (source power, exposure time, and focal depth). It was possible to create individual and highly confined lesions or thermal damage up to a depth of 4 mm within the dermis. Thermal lesions typically had an inverted cone shape. A precise pattern of individual lesions was achieved in the deep dermis by applying the probe sequentially at different exposure locations.
DISCUSSION AND CONCLUSION
Intense focused ultrasound can be used as a noninvasive method for spatially confined heating and coagulation within the skin or its underlying structures. These findings have a significant potential for the development of novel, noninvasive treatment devices in dermatology.
Objective/Hypothesis
Mortality attribution can have significant implications for reimbursement, hospital/department rankings, and perceptions of safety. This work seeks to compare the accuracy of ...externally assigned diagnosis‐related group (DRG)‐based service line mortality attribution in otolaryngology to an internal review process that assigns mortality to the teams that cared for a patient during hospitalization.
Study Design
Retrospective case series.
Methods
Mortality events at Vanderbilt University Medical Center (VUMC) from 2012 to 2018 were compared. Included events were assigned to the otolaryngology service line (OSL) via the following methods: an external agency (Vizient) using DRG, utilization management assignment based on the service that provided care at admission (admission service), discharge (discharge service), or throughout hospitalization (major service line), or through the internal VUMC mortality review committee. Internal review was considered the standard for comparison.
Results
Of the 28 mortality events assigned to OSL by the DRG‐based external method, nine (32%) were actually attributable to OSL. Of the 23 total mortality events attributable to OSL at our institution, external DRG‐based review captured nine (39%). The designation of major service during hospitalization was correct 95% of the time and captured 87% of mortality events. Differences between external and internal attribution methods were statistically significant (P < .001).
Conclusions
DRG‐based models are frequently utilized but can be inaccurate when attributing mortality for an individual otolaryngology department. Otolaryngology mortalities appear to be captured and assigned more accurately by assigning deaths to the service that renders the majority of care during hospitalization.
Level of Evidence
4 Laryngoscope, 131:E1805–E1810, 2021
Background:
Intense therapeutic ultrasound (ITU) is an innovative ultrasound-based therapy where sound waves are concentrated into select musculoskeletal tissue. These focused waves generate thermal ...coagula at a controlled depth and space while preserving surrounding tissues. A multicenter study was conducted evaluating the efficiency, safety, and patient tolerance of ITU for the treatment of chronic plantar fasciitis (CPF) pain.
Methods:
Seventy-four CPF patients, having failed conservative and/or minimally invasive treatment, participated in the study. Randomized participants either received 2 ITU treatments or 2 sham ITU treatments in addition to standard-of-care therapy. Plantar fascia pain was assessed pretreatment and at 4, 8, 12, and 26 weeks after treatment. Diagnostic ultrasonographic images were analyzed to examine hypoechoic, perifascial lesions whose volumes were calculated until week 12. Function and patient satisfaction were measured using self-reported outcome measures.
Results:
The treated group reported significant average pain reduction (–26%, –33%, –43%) and hypoechoic lesion volume (–33%, –53%, –68%) at weeks 4, 8, and 12 compared to baseline. Although the control/sham group reported insignificant pain changes at the same time points (–5%, +8%, and +2%) and increased hypoechoic lesion volume (+15%, +28%, +58%). Treated patients reported a significant increase in daily living activities (+28%, +42%, +47%, +40%) compared to the sham/control group (+0.12%, +12%, +3%, +21%). Patient satisfaction remained more than 80% at weeks 8, 12, and 26 for all treatment groups.
Conclusion:
ITU is an effective pain relief treatment for CPF, which is refractory to either conservative measures or minimally invasive treatments.
Level of Evidence:
Level II.
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.
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.
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.
Category:
Sports
Introduction/Purpose:
Initial treatment of plantar fasciitis (PF), consisting of anti-inflammatories, stretching and in-shoe orthosis (heel pad, heel wedge, or arch support), leads ...to symptomatic resolution in over 90% of patients but takes 3-6 months. This study was conducted to test the effectiveness of a minimally invasive modality, intense therapeutic ultrasound (ITU), in accelerating the healing of chronic plantar fasciitis (PF). ITU uses high-frequency high-intensity focused ultrasound to create small thermal injury zones inside soft tissue without damage to surrounding structures. ITU has been shown to initiate a tissue repair cascade and promote collagen generation in dermal and musculoskeletal tissue and is FDA approved for use in non-surgical brow lifts 1,2. The goal of this study was to determine if ITU when combined with standard therapy could speed the healing of chronic PF.
Methods:
47 patients with chronic (greater than 3 months) heel pain due to PF were randomized to standard therapy (anti- inflammatory pills, stretching, and gel heel cups) plus ITU (“ITU”, n=33) or standard therapy plus sham ITU (“control”, n=14) groups. ITU treatments were administered at enrollment and two-weeks later using a custom 3.3 MHz therapeutic ultrasound system (Guided Therapy Systems, Mesa, AZ). Sham treatment utilized the same protocol but with the energy set to 0 Joules. Treatment effect was assessed at 2, 4, 6, and 12 weeks after the initiation of treatment using diagnostic ultrasound and patient reported outcomes (PROMIS physical function computer adaptive test, PROMIS global health, Foot Function Index pain subscale, and a non-validated heel pain specific questionnaire). Ultrasound images were analyzed to determine the size of lesions within the PF. Both the sonographer and the study coordinator administering the patient reported outcome instruments were blinded to group assignment.
Results:
38 patients completed the 12 week study (ITU: n=37, Control: n=11.). The ITU group reported a significantly greater reduction in heel pain scores Mean 8.27, SD 4.69, P=0.027 compared to the control group Mean 2.25, SD 5.92 (Figure 1). Ultrasound imaging showed an 81% decrease in perifascial lesion size in the treatment group, compared to a 26% increase in lesion size in the control group (Figure 2).
Conclusion:
Preliminary results of this clinical study of noninvasive ITU for the treatment of chronic PF showed that ITU treatment as compared to sham control lead to a larger and more rapid reduction of heel pain and perifascial lesion size. ITU holds promise as a potential therapy to accelerate the healing of chronic plantar fasciitis
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