Investigating Electrode-Ionomer Interface Phenomena for Electrochemical Energy Applications

The endeavor to develop high-performance electrochemical energy applications has underscored the growing importance of comprehending the intricate dynamics within an electrode's structure and their influence on overall performance. This review investigates the complexities of electrode-ionomer interactions, which play a critical role in optimizing electrochemical reactions. Our examination encompasses both microscopic and meso/macro scale functions of ionomers at the electrode-ionomer interface, providing a thorough analysis of how these interactions can either enhance or impede surface reactions. Furthermore, this review explores the broader-scale implications of ionomer distribution within porous electrodes, taking into account factors like ionomer types, electrode ink formulation, and carbon support interactions. We also present and evaluate state-of-the-art techniques for investigating ionomer distribution, including electrochemical methods, imaging, modeling, and analytical techniques. Finally, the performance implications of these phenomena are discussed in the context of energy conversion devices. Through this comprehensive exploration of intricate interactions, this review contributes to the ongoing advancements in the field of energy research, ultimately facilitating the design and development of more efficient and sustainable energy devices.

Differences in the Electrochemical Performance of Pt-Based Catalysts Used for Polymer Electrolyte Membrane Fuel Cells in Liquid Half- and Full-Cells

A substantial amount of research effort has been directed toward the development of Pt-based catalysts with higher performance and durability than conventional polycrystalline Pt nanoparticles to achieve high-power and innovative energy conversion systems. Currently, attention has been paid toward expanding the electrochemically active surface area (ECSA) of catalysts and increase their intrinsic activity in the oxygen reduction reaction (ORR). However, despite innumerable efforts having been carried out to explore this possibility, most of these achievements have focused on the rotating disk electrode (RDE) in half-cells, and relatively few results have been adaptable to membrane electrode assemblies (MEAs) in full-cells, which is the actual operating condition of fuel cells. Thus, it is uncertain whether these advanced catalysts can be used as a substitute in practical fuel cell applications, and an improvement in the catalytic performance in real-life fuel cells is still necessary. Therefore, from a more practical and industrial point of view, the goal of this review is to compare the ORR catalyst performance and durability in half- and full-cells, providing a differentiated approach to the durability concerns in half- and full-cells, and share new perspectives for strategic designs used to induce additional performance in full-cell devices.

Operando Identification of the Chemical and Structural Origin of Li-Ion Battery Aging at Near-Ambient Temperature

Integrated with heat-generating devices, a Li-ion battery (LIB) often operates at 20-40 °C higher than the ordinary working temperature. Although macroscopic investigation of the thermal contribution has shown a significant reduction in the LIB performance, the molecular level structural and chemical origin of battery aging in a mild thermal environment has not been elucidated. On the basis of the combined experiments of the electrochemical measurements, Cs-corrected electron microscopy, and in situ analyses, we herein provide operando structural and chemical insights on how a mild thermal environment affects the overall battery performance using anatase TiO₂ as a model intercalation compound. Interestingly, a mild thermal condition induces excess lithium intercalation even at near-ambient temperature (45 °C), which does not occur at the ordinary working temperature. The anomalous intercalation enables excess lithium storage in the first few cycles but exerts severe intracrystal stress, consequently cracking the crystal that leads to battery aging. Importantly, this mild thermal effect is accumulated upon cycling, resulting in irreversible capacity loss even after the thermal condition is removed. Battery aging at a high working temperature is universal in nearly all intercalation compounds, and therefore, it is significant to understand how the thermal condition contributes to battery aging for designing intercalation compounds for advanced battery electrode materials.

Bi-MOF derived micro/meso-porous Bi@C nanoplates for high performance lithium-ion batteries

Micro/meso-porous Bi@C nanoplates are synthesized by pyrolyzing Bi-based metal-organic frameworks (MOFs) prepared by a microwave-assisted hydrothermal method to overcome huge volume expansion and pulverization of anode materials during battery operation. The Bi@C nanoplates are composed of ∼10-50 nm Bi nanoparticles in an amorphous carbon shell. The material shows very high capacity (556 mA h g-1) after 100 cycles at 100 mA g-1 and good cycling performance. Moreover, the Bi@C nanoplates perform well at high current densities and have excellent cyclic stability; their capacity is 308 mA h g-1 after 50 cycles and 200 mA h g-1 after 1000 cycles at 3000 mA g-1. The outstanding performance of this anode is due to the nanosized Bi and amorphous carbon shell. The nanosized Bi reduces the diffusion length of Li ions, while the amorphous carbon shell improves the electrical conductivity of the anode and also restrains the pulverization and aggregation of the metal during cycling. The proposed hierarchical micro/meso-porous materials derived from MOFs are a new type of nanostructures that can aid the development of novel Bi-based anodes for LIBs.

Enhancement of service life of polymer electrolyte fuel cells through application of nanodispersed ionomer

In polymer electrolyte fuel cells (PEFCs), protons from the anode are transferred to the cathode through the ionomer membrane. By impregnating the ionomer into the electrodes, proton pathways are extended and high proton transfer efficiency can be achieved. Because the impregnated ionomer mechanically binds the catalysts within the electrode, the ionomer is also called a binder. To yield good electrochemical performance, the binder should be homogeneously dispersed in the electrode and maintain stable interfaces with other catalyst components and the membrane. However, conventional binder materials do not have good dispersion properties. In this study, a facile approach based on using a supercritical fluid is introduced to prepare a homogeneous nanoscale dispersion of the binder material in aqueous alcohol. The prepared binder exhibited high dispersion characteristics, crystallinity, and proton conductivity. High performance and durability were confirmed when the binder material was applied to a PEFC cathode electrode.

Edge-Terminated MoS2 Nanoassembled Electrocatalyst via In Situ Hybridization with 3D Carbon Network

Transition metal dichalcogenides, especially MoS₂ , are considered as promising electrocatalysts for hydrogen evolution reaction (HER). Since the physicochemical properties of MoS₂ and electrode morphology are highly sensitive factor for HER performance, designed synthesis is highly pursued. Here, an in situ method to prepare a 3D carbon/MoS₂ hybrid catalyst, motivated by the graphene ribbon synthesis process, is reported. By rational design strategies, the hybrid electrocatalysts with cross-connected porous structure are obtained, and they show a high HER activity even comparable to the state-of-the-art MoS₂ catalyst without appreciable activity loss in long-term operations. Based on various physicochemical techniques, it is demonstrated that the synthetic procedure can effectively guide the formation of active site and 3D structure with a distinctive feature; increased exposure of active sites by decreased domain size and intrinsically high activity through controlling the number of stacking layers. Moreover, the importance of structural properties of the MoS₂ -based catalysts is verified by controlled experiments, validating the effectiveness of the designed synthesis approach.

MRA of the skin: mapping for advanced breast reconstructive surgery

Autologous breast reconstruction using muscle-sparing free flaps are becoming increasingly popular, although microvascular free flap reconstruction has been utilised for autologous breast reconstructions for >20 years. This innovative microsurgical technique involves meticulous dissection of artery-vein bundle (perforators) responsible for perfusion of the subcutaneous fat and skin of the flap; however, due to unpredictable anatomical variations, preoperative imaging of the donor site to select appropriate perforators has become routine. Preoperative imaging also reduces operating time and enhances the surgeon's confidence in choosing the appropriate donor site for harvesting flaps. Although computed tomography angiography has been widely used for preoperative imaging, concerns over excessive exposure to ionising radiation and poor iodinated contrast agent enhancement of the intramuscular perforator course has made magnetic resonance angiography, the first choice imaging modality in our centre. Magnetic resonance angiography with specific post-processing of the images has established itself as a reliable method for mapping tiny perforator vessels. Multiple donor sites can be imaged in a single setting without concern for ionising radiation exposure. This provides anatomical information of more reconstruction donor site options, so that a surgeon can design a flap of tissue centralised around the best perforator, as well as a back-up perforator, and even a back-up flap option located on a different region of the body. This information is especially helpful in patients with a history of scar tissue from previous surgeries, where the primary choice perforator is found to be damaged or unsuitable intraoperatively. In addition, chest magnetic resonance angiography evaluates recipient site blood vessel suitability including vessel diameters, course, and branching patterns. In this article we provide a broad overview of various skin flaps, clinical indications, advantages and disadvantages of each of these flaps, basic imaging technique, along with advanced sequences for visualising tiny arteries in the groin and in the chest. Post-processing techniques, structure of the report and how automation of the reporting system improves workflow is described. We also describe applications of magnetic resonance angiography in postoperative imaging.

From grass to battery anode: agricultural biomass hemp-derived carbon for lithium storage

Biomass-derived carbon, as a low-cost material source, is an attractive choice to prepare carbon materials, thus providing an alternative to by-product and waste management. Herein, we report the preparation of carbon from hemp stem as a biomass precursor through a simple, low-cost, and environment-friendly method with using steam as the activating agent. The hemp-derived carbon with a hierarchically porous structure and a partial graphitization in amorphous domains was developed, and for the first time, it was applied as an anode material for lithium-ion battery. Natural hemp itself delivers a reversible capacity of 190 mA h g⁻¹ at a rate of 300 mA g⁻¹ after 100 cycles. Ball-milling of hemp-derived carbon is further designed to control the physical properties, and consequently, the capacity of milled hemp increases to 300 mA h g⁻¹ along with excellent rate capability of 210 mA h g⁻¹ even at 1.5 A g⁻¹. The milled hemp with increased graphitization and well-developed meso-porosity is advantageous for lithium diffusion, thus enhancing electrochemical performance via both diffusion-controlled intercalation/deintercalation and surface-limited adsorption/desorption. This study not only demonstrates the application of hemp-derived carbon in energy storage devices, but also guides a desirable structural design for lithium storage and transport.

Hemp-derived carbon was prepared by physical activation using only steam, and directly applied as an electrode for lithium storage.

Coffee Waste-Derived Hierarchical Porous Carbon as a Highly Active and Durable Electrocatalyst for Electrochemical Energy Applications

Nitrogen-doped porous carbon materials have been highlighted as promising alternatives to high-cost platinum in various electrochemical energy applications. However, protocols to generate effective pore structure are still challenging, which hampers mass production and utilization of carbon materials. Here, we suggest a facile and effective method for hierarchical porous carbon by a single-step carbonization of coffee waste (CW) with ZnCl₂. The CW, which is one of the most earth-abundant organic waste, can be successfully converted to nitrogen-doped porous carbon. It shows outstanding oxygen reduction activity and durability comparable to the state-of-the-art platinum, and the half-wave potential is also comparable to the best metal-free electrocatalysts in alkaline media. Finally, we apply it to counter electrode of dye-sensitized solar cell, whose photovoltaic efficiency surpasses the one made with conventional platinum electrode. We demonstrate the feasibility of our strategies for highly efficient, cheap, and environment-friendly electrocatalyst to replace platinum in various electrochemical energy applications.

Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator

Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that cobaltocene could effectively convert polysulphides to Li₂S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g⁻¹_cathode capacity after 50 cycles, which is equivalent to 800 mAh g⁻¹_S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.

High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance.

Pharmacokinetics of sildenafil and its metabolite, N-desmethylsildenafil, in rats with liver cirrhosis and diabetes mellitus, alone and in combination

Pharmacokinetics of sildenafil and its metabolite, N-desmethylsildenafil, in humans and rats with liver cirrhosis (LC) and diabetes mellitus (DM), alone and in combination (LCD) did not seem to be reported. Sildenafil was administered intravenously (10 mg/kg) and orally (20 mg/kg) to control, LC, DM, and LCD rats. Expression of intestinal CYP isozymes in those rats was also measured. In LC, DM, and LCD rats, the areas under the curve (AUCs) of intravenous sildenafil were significantly greater (by 195%, 54.2%, and 127%, respectively) than controls. In LC and LCD rats, AUCs of oral sildenafil were significantly greater (3010% and 2030%, respectively) than controls. In LC, DM, and LCD rats, significantly greater AUCs of intravenous sildenafil were due to the slower hepatic extraction of sildenafil (because of decrease in the protein expression of hepatic CYP2C11 and 3A subfamily in LC and LCD rats, and CYP2C11 in DM rats). In LC and LCD rats, greater magnitude of increase in AUCs of oral sildenafil than those after the intravenous administration could be mainly due to the decrease in the intestinal extraction of sildenafil (because of decrease in the protein expression of intestinal CYP2C11 in LC and LCD rats).

Pharmacokinetics of oltipraz in diabetic rats with liver cirrhosis

BACKGROUND AND PURPOSE

The incidence of diabetes mellitus is increased in patients with liver cirrhosis. Oltipraz is currently in trials to treat patients with liver fibrosis and cirrhosis induced by chronic hepatitis types B and C and is primarily metabolized via hepatic cytochrome P450 isozymes CYP1A1/2, 2B1/2, 2C11, 2D1 and 3A1/2 in rats. We have studied the influence of diabetes mellitus on pharmacokinetics of oltipraz and on expression of hepatic, CYP1A, 2B1/2, 2C11, 2D and 3A in rats with experimental liver cirrhosis.

EXPERIMENTAL APPROACH

Oltipraz was given intravenously (10 mg x kg(-1)) or orally (30 mg x kg(-1)) to rats with liver cirrhosis induced by N-dimethylnitrosamine (LC rats) or with diabetes, induced by streptozotocin (DM rats) or to rats with both liver cirrhosis and diabetes (LCD rats) and to control rats, and pharmacokinetic variables measured. Protein expression of hepatic CYP1A, 2B1/2, 2C11, 2D and 3A was measured using Western blot analysis.

KEY RESULTS

After i.v. or p.o. administration of oltipraz to LC and DM rats, the AUC was significantly greater and smaller, respectively, than that in control rats. In LCD rats, the AUC was that of LC and DM rats (partially restored towards control rats). Compared with control rats, the protein expression of hepatic CYP1A increased, that of CYP2C11 and 3A decreased, but that of CYP2B1/2 and 2D was not altered in LCD rats.

CONCLUSIONS AND IMPLICATIONS

In rats with diabetes and liver cirrhosis, the AUC of oltipraz was partially restored towards that of control rats.

Selective control of cyanobacteria in eutrophic pond by a combined device of ultrasonication and water pumps

A combined device consisting of an ultrasonic apparatus and water pumps was operated in a eutrophic pond to study its effect on the control of cyanobacteria as compared with those of a non-treated, neighboring pond. The combined apparatus seemed to be enough to spread the sonicated water to the whole surface of a 9,000 m3 pond. Although the high rainfall in 2003 resulted in an overall dominance of diatoms, cyanobacterial growth was significantly inhibited by the apparatus in the treated pond. In addition, the chlorophyll-a concentration and total algae in the treated pond were 61 and 53%, respectively, of the levels in the control pond. The reduced algal growth (7% of the control) by the combined apparatus was mainly due to the inhibition on the growth of cyanobacteria. The cyanobacterial proportion in the treated pond, however, increased significantly for several days, when the apparatus was stopped. Meanwhile, the proportion of green algae increased in the treated pond. The successful selective control of cyanobacteria using the combined apparatus suggests that ultrasonication can be a practical method to control bloom and toxin production in eutrophic waters.

Simultaneous bilateral breast reconstruction with the transverse rectus abdominus musculocutaneous free flap

OBJECTIVE

The purpose of the study was to assess the results and morbidity associated with simultaneous bilateral TRAM free flap breast reconstruction and describe refinements in its surgical technique.

SUMMARY BACKGROUND DATA

Bilateral prophylactic total mastectomies might be an agreeable option for those patients at highest risk for breast cancer if autogenous tissue breast reconstruction could be performed with reasonable technical ease and acceptable morbidity. However, some surgeons harbor reservations regarding the extensiveness of the surgery, the associated morbidity, and the aesthetic quality of the resulting outcome.

METHODS

A multicenter retrospective review of clinical experience with 120 consecutive patients who underwent 240 simultaneous bilateral TRAM free flap breast reconstructions was developed.

RESULTS

The average operating time, including the time required for the breast ablative portion of the procedures, was 8.6 hours. The average length of hospitalization was 7.6 days. However, for the last 40 patients, these figures were reduced to 7.1 hours and 6.1 days, respectively. Nonautologous blood transfusions were needed in 33 cases (28%), but only 1 was required in the last 40 patients. Thromboses developed in six of 240 flaps (2.5%): 4 were arterial and 2 were venous. Re-exploration allowed us to restore circulation in five flaps, whereas one flap was unsalvageable and was replaced successfully with an alternate flap. An uncomplicated deep vein thromboses developed in one patient with a history of recurrent deep vein thromboses that had no adverse effect on her outcome. Minor complications developed in 18 patients (15%) (e.g., hematoma, partial wound necrosis, wound infection, or prolonged postoperative ileus) that did not affect the long-term outcome. Fourteen patients (11.6%) had abdominal wall weakness or hernias. Follow-up time averaged 37.2 months (range, 14-62 months). On last follow-up, patients' self-reported overall satisfaction with the procedure was 56% excellent, 40% good, and 4% fair.

CONCLUSIONS

Simultaneous bilateral free flap reconstruction is technically feasible with a high rate of success and an acceptable morbidity. When performed by experienced surgeons, bilateral prophylactic total mastectomies combined with simultaneous bilateral TRAM free flap reconstruction may provide an adequate surgical option with aesthetically acceptable results for patients at high risk for breast cancer.

TRAM flaps in patients with abdominal scars

Of 114 patients who had TRAM flap breast reconstruction, 46 (40 percent) had preexisting abdominal surgical scars. Sixty-six free TRAM flaps and 9 pedicled TRAM flaps were performed in the 46 patients. The records were analyzed to determine what impact, if any, abdominal scars had on postoperative complications. There were no reconstructive failures or significant (>25 percent) flap losses. Eight minor complications occurred in 7 patients (15 percent). The incidences of abdominal-wall weakness (4.3 percent), partial flap loss (4.3 percent), minor fat necrosis (4.3 percent), and donor-site wound problems (4.3 percent) were acceptable. Subcostal scars and multiple abdominal scars were found to predispose to skin complications. Right lower paramedian scars precluded free TRAM flaps because of damage to the inferior epigastric vessels in three of three patients. Both obesity (p = 0.003) and smoking (p = 0.05) were associated with a greater risk of wound-healing complications. We conclude that with certain technical modifications, TRAM flap reconstruction is a safe and effective procedure in patients with abdominal scars.

Microbial evaluation: 139 implants removed from symptomatic patients

Possible adverse effects of microbial organisms have been implicated in symptomatic silicone implant patients. In the literature, numerous authors have investigated the possible role of infection with respect to implant problems. To date, various bacterial species have been reported, including Staphylococcus aureus, Staphylococcus epidermidis, peptostreptococci, and Clostridium perfringens. Infections in polyurethane-coated prostheses also have been shown to prolong morbidity. Antibiotic use has been relatively empirical in this regard. The purpose of this study was, first, to determine the frequency, type, and clinical relevance of microbial colonization on implant surfaces removed from symptomatic patients and, second, to determine possible effects of microbial colonization on implant integrity (gel bleed, rupture). A total of 139 implants from 72 symptomatic patients were entered into the prospective clinical study between February of 1993 and July of 1994 at the UCLA Medical Center. The implant shell types included smooth (79 percent), polyurethane (8 percent), textured (7 percent), and smooth and Dacron (6 percent). The implant locations were subglandular (71 percent), submuscular (28 percent), and subcutaneous (1 percent). Of the 139 implants removed, 69 percent were intact and 31 percent were ruptured. Forty-seven percent of 139 implants were culture-positive. Propionibacterium acnes was isolated most frequently (57.5 percent), followed by Staphylococcus epidermidis (41 percent), and then Escherichia coli (1.5 percent). No fungal infections were identified. Culture positivity was not significantly associated with systemic symptoms. Sixty-seven percent of the positive culture implants were intact; 33 percent were ruptured. The frequency (47 percent) and types (P. acnes and S. epidermidis) of microbial colonization are determined in symptomatic silicone implant patients.

Safe ischemia time in free-flap surgery: a clinical study of contact-surface cooling

Although the effectiveness of cooling in extending tolerable ischemia time is well-established experimentally, most free-flap surgeons are still concerned about this problem and try to limit the ischemic period to less than 1 hr. Clinically, contact-surface cooling has been used empirically to prolong the limits of ischemia time; however, its applications are unproven. It also remains unknown whether contact-surface cooling has detrimental effects on flap tissue, such as vessel spasm leading to thrombosis. The purpose of this study was to determine, in a clinical setting, if skin, muscle, and bone free flaps of considerable size could tolerate prolonged cold ischemia without adverse effects. Flap size, cold ischemia time, and surgical outcomes were studied in 189 consecutive free flaps. Microvascular thrombosis occurred in 5/378 (1.3 percent) of anastomoses. The overall flap complication/flap loss rate was 7/189 (3.7 percent). Mean ischemia time for all flaps was 2 hr and 6 min (range: 30 min to 5 hr, with one case at 6 hr and 8 min). The mean ischemia time for cases with flap complications was 2 hr 20 min, while ischemia time for cases with thrombosis averaged 2 hr 13 min. The one flap loss had an ischemia time of 1 hr 35 min. No statistically significant correlations existed between duration of ischemia time or duration of contact-surface cooling and the incidence of thrombosis, flap complication, or flap failure. Among the conclusions were that, within a 4-hr period of cold ischemia, the application of the surface-cooling technique is not detrimental to free flap surgery; thus, concern for ischemia, and especially the "no reflow" phenomenon, generally should not interfere with efficient and orderly free-flap surgery.

The use of cryopreserved microvenous allografts in the venous system without immunosuppression: an experimental study

Autogenous vein grafts are currently the number one choice in microsurgical practice for managing vessel length discrepancies. A significant percentage of these grafts is used in the venous system. Allografts may serve as a viable alternative source of vein grafts. Few studies in the past have described the use of cryopreserved vein grafts (1 mm in diameter) in the venous system. In the present study, we cryopreserved the femoral veins of rats and transplanted these across rat species (ACI to Lewis) as interpositional vein grafts into a defect in the femoral vein. Short-term patencies (21 days), expressions of systemic antigenicity, histology, and scanning electron microscopic studies were performed. We obtained 100% patencies with fresh control veins and cryopreserved veins at 21 days.

Capsular synovial metaplasia as a common response to both textured and smooth implants

Recent reports suggested that the presence of synovial metaplasia in the capsular tissues of breast implants is greater with textured-shelled implants compared with smooth. Textured implants, however, have become popular only in the last few years. Therefore, the studies do not address the possibility that synovial metaplasia may be a dynamic process related to time (e.g., implant age) rather than implant shell surface. In the current study, 159 implant capsules (85 patients) removed between February of 1992 and July of 1993 at UCLA Medical Center were evaluated histologically and correlated with clinical data, including the age of implants. Synovial metaplasia was identified in 40 percent (64 of 159) of the capsule specimens. A logistic regression analysis that removed the effect of implant age demonstrated no correlation of implant shell type (textured versus smooth) with the presence of synovial metaplasia. Gel bleed, implant location, pericapsular fluid, implant rupture, and capsular contracture also did not have any significant association with synovial metaplasia in the current study. The incidence of synovial metaplasia appears to decrease with age (77 percent at < 5 years; 22 percent at > 15 years). Our findings suggest that synovial metaplasia is not rare and in fact may be a fairly common transitional histologic finding. It may be part of the common progression that occurs at the implant-capsule interface. The clinical significance remains unknown.

Clinical significance of intracapsular fluid in patients' breast implants

Clinical reports on the incidence and clinical significance of intracapsular fluid are lacking in the literature. It remains unknown whether the presence of intracapsular fluid has any relation to implant infection or colonization. The purpose of this study was to determine the frequency and type of intracapsular fluid, specifically, whether intracapsular fluid causes implant infection, implant rupture, or bacterial colonization. A total of 139 implants from 72 symptomatic patients were entered into the prospective clinical study. Our study demonstrated the presence of intracapsular fluid in 21 of 139 (15%) implants. Positive microbial cultures were identified in 39% of the implants in the positive intracapsular fluid group, compared to 43% in the negative fluid group. There was no statistically significant difference between these groups. Also, no adverse clinical relationship was demonstrated between local symptoms and presence of intracapsular fluid. There was, however, a positive trend toward the presence of fluid when implant shell types were nonsmooth (polyurethane and textured silicone implants). Further studies are indicated to elucidate the fluid production mechanism and possible secretory activity of prosthetic capsules interfacing the textured breast implant surface.

Clinical experience with a microvascular anastomotic device in head and neck reconstruction

BACKGROUND

Despite numerous refinements in microsurgical technique and instrumentation, the microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions.

MATERIALS AND METHODS

Concurrent with the development of microsurgical techniques, various anastomotic coupling systems have been introduced in an effort to facilitate the performance and reliability of microvascular anastomoses. The microvascular anastomotic coupling device (MACD) studied here is a high-density, polyethylene ring-stainless steel pin system that has been found to be highly effective in laboratory animal studies. Despite its availability for human clinical use over the last 5 years, reported clinical series remain rare. Our clinical experience with this MACD in 29 head and neck free-tissue transfers is reported herein.

RESULTS

Thirty-five of 37 (95%) attempted anastomoses were completed with 100% flap survival with a variety of donor flaps, recipient vessels, and clinical contexts. Two anastomoses were converted to conventional suture technique intraoperatively, and one late postoperative venous thrombosis occurred after fistulization and vessel exposure.

CONCLUSIONS

We conclude that the MACD studied here is best suited for the end-to-end anastomosis of soft, pliable, minimally discrepant vessels. Previous radiation therapy does not appear to be a contraindication to its use. Interpositional vein grafts may also be well suited to anastomosis with the device. When carefully and selectively employed by experienced microvascular surgeons, this MACD can be a safe, fast, and reliable adjunct in head and neck free-tissue transfer reconstructions, greatly facilitating the efficiency and ease of application of these techniques.

Residual silicone detection using MRI following previous breast implant removal: case reports

The current controversy surrounding the safety of silicone gel breast implants has resulted in an increasing number being removed. Although previous reports have suggested that remnants of the implant capsule are reabsorbed after explantation surgery, the persistence of the capsule in fact may be associated with implant fragments and silicone gel leakage. In this study we have used magnetic resonance imaging (MRI) to identify residual silicone gel and silicone granulomas following the removal of silicone gel breast implants. Four representative clinical case reports are presented. These patients, who had residual silicone present in their bodies, presented to us with breast pain, palpable masses, or abnormal calcific mass densities apparent on a mammogram. High-resolution MRI images were found to be helpful in identifying local and remote collections of silicone gel, silicone granulomas, and residual capsules that were incompletely removed from previous explantation surgery. MRI breast images demonstrated high resolution and provided the accurate anatomical locations of residual silicone gel and silicone granulomas in all the regions of breast parenchyma, chest wall muscles, and axillae. Patients with persistent local symptoms following explantation surgery may benefit from an evaluation of the breast using MRI.

Injected liquid silicone, chronic mastitis, and undetected breast cancer

Although the use of injected liquid silicone for breast augmentation has all but ceased since its widespread use in the 1960s, patients with injected silicone are still seen with a multitude of symptoms. Silicone mastitis is a well-documented phenomenon; however, there has been a paucity of information regarding cancer detection in this group of patients. We report 2 patients who presented with chronic mastitis but on further workup were found to have breast cancer. In both patients, early cancer detection was adversely affected by the presence of free liquid silicone. In view of this and other similar case reports, we advise that simple mastectomy be recommended to those patients with breasts inspissated with liquid silicone who not only have suspicious masses but present with recurrent mastitis or a family history of breast cancer.

Evaluation of autogenous tissue breast reconstruction using MRI

Recent controversy encountered with silicone breast implants has increased the use of autogenous tissue for breast reconstruction following mastectomy. Surveillance of patients who have undergone autogenous tissue reconstruction is important in the evaluation of recurrent or new cancer. Magnetic resonance imaging (MRI) has proven to be a useful technique in the delineation of soft tissues and provides excellent resolution. Recently, MRI has been reported to be a valuable diagnostic imaging modality for the evaluation of augmented breast implant patients with regard to implant rupture detection, silicone granuloma identification, and silicone gel migration delineation. In this study, various autologous tissue donor sites currently available for breast reconstruction were imaged by MRI. The following donor flaps were included: fleur-de-lis, TRAM, gluteal, and tensor fasciae latae. A total of 10 clinical cases were investigated. The anatomic basis of each flap type is illustrated, and various tissue components of flap tissue (skin, fat, and muscle) are demonstrated on MRI scan. Anatomic knowledge of autogenous tissue types and MRI appearance of the flap-breast-chest-wall interface are critical in the surveillance and follow-up of breast cancer patients.

Silicone implant rupture diagnosis using computed tomography: a case report and experience with 22 surgically removed implants

Silicone elastomer shell rupture is a complication of silicone implants. To date, the rate of implant rupture has not been well documented. Magnetic resonance imaging and sonography are noninvasive breast implant imaging modalities that have been shown to be useful in evaluating the integrity of implants. We present a case of rupture detection using a follow-up computed tomographic (CT) scan of a breast cancer patient, which prompted us to use CT scans to evaluate explants of patients undergoing implant removal surgery. The purpose of the investigation was to evaluate the effectiveness of CT scan in detecting rupture. CT scan was performed on 22 explants with intact capsules, for which 17 ruptures were confirmed: 16 true-positive ruptures, 5 true-negative ruptures, O false-positive ruptures, and 1 false-negative rupture were identified. CT scan was shown to be highly sensitive and specific in rupture detection, comparable to magnetic resonance imaging. Although CT scans are consistently reliable, patients are exposed to ionizing radiation; therefore, it is not recommended for patients with augmentation mammoplasty. This study characterizes the appearance of implant rupture on CT scan, which may be useful in evaluating breast cancer patients reconstructed with silicone implants.

Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants

With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

Regional silicone-gel migration in patients with ruptured implants

The current literature is reviewed, and four clinical cases of silicone-gel migration are reported. All 4 patients reported here had histories of closed capsulotomy, and all were symptomatic. Preoperative magnetic resonance imaging demonstrated the anatomical locations of silicone-gel migration into the chest wall muscles, axillae, and upper extremity. Intraoperative and pathological findings correlated with the presence of silicone-gel migration and granulomas in various anatomical regions. With the recent advances in diagnostic breast imaging of silicone-implant patients, intracapsular rupture can be identified. Implant removal may be indicated for intracapsular ruptures to prevent silicone-gel migration into parenchyma, chest wall muscles, axillae, and the upper extremity.

Clinical experience with the 3M microvascular coupling anastomotic device in 100 free-tissue transfers

The microvascular surgical anastomosis remains one of the most technically sensitive aspects of free-tissue transfers. To facilitate these often time-consuming, difficult anastomoses, various anastomotic coupling systems have been introduced. The 3M microvascular anastomotic coupling device, a polyethylene ring-pin device, was found to be highly successful in numerous animal studies. It has been available for use in human subjects for the last 4 years, but clinical experience remains sparse. Our clinical experience with the 3M coupler is reported in 100 free-tissue transfers. The average anastomotic time was 4 minutes. Mean follow-up was 8.6 months, and flap survival was 100 percent. The overall success rate for 3M (MACD) coupler use in microvascular anastomoses is 98.4 percent (121 of 123). Nine abandoned anastomoses were converted to sutured anastomoses intraoperatively. The over-all failure rate for 3M coupler anastomoses is 1.6 percent (2 of 123). We conclude that the 3M device is best suited for minimally discrepant, soft, pliable venous microvascular anastomoses and is unsuitable for end-to-side anastomoses in clinical situations. When carefully and selectively employed by a trained microvascular surgeon, the 3M coupler can be a safe, fast, and reliable adjunct for free-tissue transfers.

In vivo anatomic study of cutaneous perforators in free flaps using magnetic resonance imaging

Adequate knowledge of perforator location preoperatively will enable the surgeon to achieve optimal flap design and flap survival. Most previous attempts have relied on the use of Doppler ultrasound and earlier anatomic knowledge. With ultrasound, there may at times be signals from overlapping blood vessels. Magnetic resonance imaging (MRI) is sensitive to flowing blood and, on an MRI scan, dark-flow void characterization is used to identify perforators. This study was undertaken to evaluate the anatomic location and the number of perforators in the flap zone, based on inherent blood flow, and to determine information about the dominant perforators for free-flap design, using MRI. The CSMEMP technique allowed the characterization of flow void signals, which appeared in the image as dark spots. This technique also enabled differentiation of the surrounding tissue, with a high degree of accuracy. The relationship of the perforators aided in an "ideal" flap design. No necrosis was noted in any of these cases. It appears from this study that MRI can be a useful imaging modality, to assess the location and number of perforators in musculocutaneous flaps.

Analysis of suturing techniques in the microvascular anastomosis of vessels of unequal diameter

A rat model has been devised to study the determinants of microvascular anastomotic patency in the setting of diameter discrepancy. Isogeneic interposition grafts of rat inferior vena cava were used to repair a femoral artery defect (diameter ratio 4.5:1). Three methods for compensating for diameter discrepancy were studied. The anastomoses were explored on postoperative days 3, 7, and 14. By 2 weeks, tapered grafts were shown to result in higher patency rates (p < 0.05) compared with nontapered and spatulated grafts. Hemodynamic, histological, and scanning electron microscopic analysis suggested that turbulence caused by large velocity gradients predisposes to thrombosis. This animal model was shown to be sensitive to experimental hemodynamic alterations and may be useful in elucidating the effect of technical or pharmacological manipulations on patency in the setting of vessel diameter discrepancy.

Silicone breast implant rupture: comparison between three-point Dixon and fast spin-echo MR imaging

OBJECTIVE

This study was designed to compare the three-point Dixon technique with our present MR protocol incorporating T2-weighted fast spin echo and fast spin echo with water suppression to detect ruptured silicone breast implants.

SUBJECTS AND METHODS

Eighty-two symptomatic women with silicone breast implants were examined with both the three-point Dixon technique and fast spin-echo MR sequences. Of these patients, 41 had surgery to remove their implants. Four radiologists reviewed the images from only those patients who had surgery and graded each for rupture by using a scale of 1-5. Receiver-operating-characteristic analysis was performed.

RESULTS

Of 81 implants removed, 18 were ruptured. Silicone implant ruptures were identified more frequently on the fast spin-echo sequence than on the three-point Dixon sequence, with areas under the ROC curves of .95 and .84, respectively. Although the difference was not statistically significant, the sensitivity for detecting silicone implant rupture was 89% for the fast spin-echo sequence and 61% for the three-point Dixon sequence. The specificity was 97% for both sequences.

CONCLUSION

Silicone implant ruptures were detected more frequently with fast spin-echo MR sequences than with the three-point Dixon technique, although the difference was not significant. The greater spatial resolution used for the fast spin-echo sequence partially accounts for the difference in detection of implant ruptures in this study.

Silicone breast implant ruptures in an animal model: comparison of mammography, MR imaging, US, and CT

PURPOSE

To determine the most accurate imaging modality for detection of silicone implant ruptures.

MATERIALS AND METHODS

Forty single-lumen silicone implants were surgically placed in 20 rabbits. Each rabbit received one intact and one ruptured implant and was examined with mammography, magnetic resonance (MR) imaging, ultrasound (US), and computed tomography (CT). Five radiologists reviewed all images in a random fashion and graded each for rupture. The radiologist who performed US also graded her impression during examination with US. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

MR imaging and CT were the most accurate modalities in detection of implant ruptures, with areas under the ROC curves (Az) of .95 and .91. Mammography and US were statistically significantly inferior, with Az of .77 for each (P < .05).

CONCLUSION

MR imaging and CT are statistically more accurate than US and mammography for detection of intracapsular silicone implant ruptures when only the images are reviewed.

Silicone breast implants: US evaluation

PURPOSE

To determine the value of breast ultrasonography (US) in the assessment of silicone breast implants for rupture.

MATERIALS AND METHODS

Seventy-four women with local or systemic symptoms related to silicone implants underwent breast US. Of these, 28 underwent surgical removal of the implants.

RESULTS

Of 57 implants removed, 37 were intact. The most reliable sign of an intact implant was an anechoic interior, although reverberation artifact and radical folds could be seen. Of 20 ruptured implants, 16 were intracapsular and four were extracapsular ruptures. The most reliable US sign of rupture was echogenic, horizontal ("stepladder") lines (14 of 20 ruptures). Two of the four extracapsular ruptures were accurately identified as echogenic nodules outside the implant; two were false-negative findings. Three intracapsular ruptures identified at US were false-positive; six were false-negative. Overall sensitivity for rupture was 70%, specificity was 92%, positive predictive value was 82%, and negative predictive value was 85%.

CONCLUSION

Breast US is capable of depicting intracapsular and extracapsular rupture of breast implants.

MR imaging of the breast in patients with silicone-gel implants: spectrum of findings

Because of recent concerns about the potential dangers of rupture and leakage of silicone-gel implants, radiologists are often requested to evaluate the integrity of normal breast implants. Clinical studies suggest that MR imaging can accurately depict implant rupture. The purpose of this pictorial essay is to illustrate the spectrum of MR appearances of breasts in patients with silicone-gel implants. Types of prostheses range from the more common single-lumen silicone-gel implants to the rare foam-filled implants. Recognition of the variable appearance of intact implants is emphasized in order to distinguish these from intracapsular or extracapsular ruptures. Finally, we briefly review various investigational MR sequences designed to improve the evaluation of the integrity of silicone-gel implants and the localization of free silicone. This article is based on our experience in performing MR imaging in more than 350 patients with breast implants. In more than 50% of these patients, the MR imaging findings have been correlated with surgical and pathologic findings.

Definitive diagnosis of breast implant rupture using magnetic resonance imaging

Breast implant rupture is an important complication of augmented and reconstructed breasts. Although several techniques such as mammography, xeromammography, ultrasound, thermography, and computed tomographic (CT) scanning have been proven to be useful to detect implant rupture, they have several disadvantages and lack specificity. In the current study, we have established magnetic resonance imaging (MRI) as a definitive, reliable, and reproducible technique to diagnose both intracapsular and extracapsular ruptures. The study was conducted in 100 symptomatic patients. Our imaging parameters were able to identify ruptures in implants with silicone shells. All the ruptures showed the presence of wavy lines, free-floating silicone shell within the gel ("free-floating loose-thread sign" or "linguine sign"). We had a 3.75 percent incidence of false-positive and false-negative results. The sensitivity for detection of silicone implant rupture was 76 percent, with a specificity of 97 percent. In addition, we also were able to identify the artifacts that may interfere with the definitive diagnosis of implant rupture.

Silicone breast implants in vivo: MR imaging

This study was designed to evaluate pulse sequences and patient positioning for MR imaging of silicone breast implants in patients. One hundred forty-three patients (281 silicone implants) underwent imaging over a 21-month period. The combination of a T2-weighted fast spin echo technique (SE), T2-weighted fast SE with water suppression, and T1-weighted SE with fat suppression is recommended to reliably differentiate silicone from other breast tissues and to identify intracapsular and extracapsular ruptures or leaks. Seventy of the 143 patients underwent removal of their silicone implants. The sensitivity for detection of silicone implant rupture was 76%, with a specificity of 97%. Positioning the patient prone improved image quality.

Microvascular free flaps in breast reconstruction

There is no longer any doubt that free flaps can achieve the best breast reconstruction. Proof is the rapidly increasing popularity of the method. Its many advantages, the indications for each flap, and the technical refinements are presented.

Superior aspect of the perirenal space: anatomy and pathological correlation

To study the anatomy of the superior aspect of the perirenal space, we analysed 50 computed tomographic (CT) scans with reference to the anatomy of Gerota's fascia, and dissected five cadavers laying special emphasis on the ascent of Gerota's fascia. We also reviewed 10 scans of patients with a large lesion in the right upper abdomen regarding localisation of the lesion. We conclude that Gerota's fascia does not cover the upper portion of the kidney and adrenal gland so that the superior aspect of the perirenal space is open towards the upper abdominal extraperitoneal space. Thus, a large lesion arising from the right adrenal gland or kidney easily invaginates the liver through the bare area mimicking a hepatic lesion, and vice versa. This explains the difficulty in localising a large lesion in the right upper abdomen.