Multiple-electrode radiofrequency ablations using Octopus(R)electrodes in an in vivo porcine liver model

Objectives

The objective of this study was to determine the in vivo efficacy of radiofrequency ablation (RFA) in porcine liver using Octopus® electrodes for creating a large coagulation compared with RFA using clustered electrodes.

Methods

A total of 39 coagulations were created using a 200-W generator and clustered electrodes or Octopus electrodes during laparotomy in 19 pigs. Radiofrequency was applied to the livers using four protocols: (1) Group A-1, monopolar mode using a clustered electrode (n=11); (2) Group A-2, monopolar mode using an Octopus electrode (n=11); (3) Group B-1, consecutive monopolar mode using three, clustered electrodes (n=8); and (4) Group B-2, switching monopolar mode using two Octopus electrodes (n=9). The energy efficiency, shape, diameters (D) and volume (V) of the coagulation volume were compared in each of the two groups.

Results

The mean maximum D and V of the coagulations in Group A-2 (4.7 cm and 33.1 cm³, respectively) were significantly larger than those in Group A-1 (4.1 cm and 20.3 cm³, respectively) (p<0.05). Furthermore, the mean minimum D, maximum D and V of the coagulations in Group B-2 were significantly larger than those in Group B-1, i.e. 5.3 vs 4.0 cm, 6.6 vs 4.9 cm and 66.9 vs 30.2 cm³, respectively (p<0.05). The energy efficiencies were also significantly higher in Groups A-2 and B-2 than in Groups A-1 and B-1 (p<0.05).

Conclusion

The Octopus electrodes were more efficient for creating a large ablation zone than clustered electrodes, and the efficacy of RFA with Octopus electrodes can be amplified in the switching monopolar mode.In recent years, image-guided percutaneous tumour ablation using radiofrequency (RF) energy has become increasingly popular and has gained wide acceptance as a valuable, minimally invasive treatment for primary and secondary liver malignancies [1]. Compared with conventional surgery, RF ablation (RFA) has many advantages in terms of reduced complications, morbidity and mortality as well as its cost-effectiveness. However, a major obstacle preventing the widespread use of RFA is its inability to reliably create adequate volumes of complete tumour destruction with sufficient safety margins, thus causing an increasing rate of marginal recurrence in large tumours due to the incomplete RFA. Most clinically available electrodes, including internally cooled electrodes, clustered electrodes, multitined expandable needle electrodes and perfusion electrodes, can induce coagulation necrosis in the range of 3–4 cm in diameter after a single ablation session [2,3]. Therefore, to treat liver tumours >3 cm in diameter, multiple overlapping ablations are often required to cover the entire tumour volume as well as the peripheral ablation margins [4,5]. However, in clinical practice, there is considerable difficulty repositioning the probe under ultrasound guidance during overlapping ablations as numerous microbubbles form in the heated tissue during RFA and may thus interfere with finding the electrode tip and the untreated portions of the target tumour on ultrasound [6].In order to avoid problems related to multiple overlapping ablations, including technical difficulties and a long procedure time, several approaches have been used to treat medium and large liver tumours. These include the use of cluster electrodes [7], multitined electrodes with saline infusion (RITA Medical Systems, Mountain View, CA) [2] and multiple electrodes in the switching monopolar mode or multipolar mode [8-11]. Although several previous studies demonstrated that the use clustered electrodes or multiple electrodes in the switching or multipolar modes could create larger coagulations [2,3,6,8-14], they also presented several potential unsolved problems. The clustered electrode problems include: (1) convergence of the three individual needles <5 mm; (2) limited access to the target tumour owing to narrow intercostal spaces; and (3) displacement of the liver due to its resistance to the electrode. Although RFA using multiple electrodes can successfully treat large liver tumours, it is still not widely used in clinical practice, primarily owing to its high cost and the complexity of using multiple electrodes.Recently, in order to improve the efficiency of clustered electrodes in creating a large ablation zone and to diminish any potential problems, we developed a separable clustered electrode (Octopus®; Taewoong Medical Co., Ltd, Goyang, Republic of Korea) with a specialised handle that can be incorporated into a larger handle in a single unit (Figure 1). Our electrode can be placed as a single electrode with variable interelectrode distances, according to the shape and size of the target tumour, or in a similar way to the clustered electrodes that are also composed of three electrodes as a single body at a fixed 5-mm interelectrode distance. Therefore, prior to their clinical application, we attempted to prove the in vivo efficacy of RFA using the Octopus electrodes to create a large area of coagulation necrosis in either the conventional or switching monopolar mode compared with RFA using a clustered electrode in porcine liver.Open in a separate windowFigure 1(a,b) Photographs of the Octopus® electrodes (Taewoong Medical Co., Ltd, Goyang, Republic of Korea), all of which have three individual needles. (c) Adaptor for the Octopus electrodes which connects the three cables to one port. (d) An illustration, which shows details of the connection between the needles and radiofrequency (RF) ablution system in a three Octopus electrodes system.     

Enhancement patterns of hepatocellular carcinomas on multiphasicmultidetector row CT: comparison with pathological differentiation

Objective The objective of this study was to determine the incidence of typical and atypical enhancement patterns of hepatocellular carcinomas (HCCs) on multiphasic multidetector row CT (MDCT) and to correlate the enhancement patterns and morphological image findings of HCC with the degree of tumour differentiation. Methods MDCT images of 217 patients with 243 surgically proven HCCs were evaluated through consensus reading by two radiologists. Our MDCT protocol was composed of precontrast, arterial, portal and delayed phases. The reviewers analysed the CT images for degree of attenuation; relative timing of washout; presence of dysmorphic intratumoral vessels, aneurysms and necrosis; tumour size; tumour margin; presence of pseudocapsule; intratumoral heterogeneity; and determined enhancement pattern. The imaging features were correlated with tumour differentiation using Fisher's exact test or the χ(2) test. Results Among 243 HCCs, 137 (56.4%) showed the typical enhancement pattern of HCC, which is arterial enhancement and washout on portal or equilibrium phase images. In the arterial phase, 190 of 243 (78.2%) HCCs showed hypervascularity, with approximately three quarters of poorly differentiated (PD) (34 of 45, 75.6%) and moderately differentiated (MD) HCCs (92 of 123, 74.8%) showing washout during the portal or delayed phases, vs only 50% of well-differentiated (WD) HCCs (11 of 22; p<0.048). The presence of intratumoral vessels and aneurysms, tumour necrosis, attenuation of precontrast, the relative timing of washout, intratumoral attenuation heterogeneity, tumour margin and tumour size were correlated with the pathological differentiation of HCCs (p<0.05). Conclusion A typical enhancement of HCCs on MDCT was not unusual (43.6%) and WD and PD HCCs account for most of the atypical enhancement patterns. Early washout favoured MD and PD HCCs rather than WD HCCs, whereas in our study the presence of intratumoral aneurysm was a highly specific finding for PD HCC.     

The development of the Be Active & Relax ¿Vitality in Practice¿ (VIP) project and design of an RCT to reduce the need for recovery in office employees

ABSTRACT: BACKGROUND: There is strong evidence to suggest that multiple work-related health problems are preceded by a higher need for recovery. Physical activity and relaxation are helpful in decreasing the need for recovery. This article aims to describe (1) the development and (2) the design of the evaluation of a daily physical activity and relaxation intervention to reduce the need for recovery in office employees. METHODS: The study population will consist of employees of a Dutch financial service provider. The intervention was systematically developed, based on parts of the Intervention Mapping (IM) protocol. Assessment of employees needs was done by combining results of face-to-face interviews, a questionnaire and focus group interviews. A set of theoretical methods and practical strategies were selected which resulted in an intervention program consisting of Group Motivational Interviewing (GMI) supported by a social media platform, and environmental modifications. The Be Active & Relax program will be evaluated in a modified 2 X 2 factorial design. The environmental modifications will be pre-stratified and GMI will be randomised on department level. The program will be evaluated, using 4 arms: (1) GMI and environmental modifications; (2) environmental modifications; (3) GMI; (4) no intervention (control group). Questionnaire data on the primary outcome (need for recovery) and secondary outcomes (daily physical activity, sedentary behaviour, relaxation/detachment, work- and health-related factors) will be gathered at baseline (T0), at 6 months (T1), and at 12 months (T2) follow-up. In addition, an economic and a process evaluation will be performed. DISCUSSION: Reducing the need for recovery is hypothesized to be beneficial for employees, employers and society. It is assumed that there will be a reduction in need for recovery after 6 months and 12 months in the intervention group, compared to the control group. Results are expected in 2013. Trial registration: Netherlands Trial Register (NTR): NTR2553 KEYWORDS: Need for recovery, relaxation, physical activity, environmental modifications, group motivational interviewing, employees, RCT.     

cDNA recombinant plasmid complementary to mRNAs for light chains 1 and 3 of mouse skeletal muscle myosin.

A recombinant plasmid with a cDNA sequence transcribed from mouse skeletal muscle RNA is shown to hybridize with mRNAs for myosin light chains LC1F and LC3F. The inserted fragment corresponds exclusively to the 3'-noncoding region of the mRNA. It hybridizes almost exclusively with the two light chain messengers from fast skeletal muscle RNA of adult mouse. Slight hybridization is seen with RNA from heart muscle and embryonic skeletal muscle. The implications of the conservation of the 3'-noncoding regions between the two mRNAs are discussed.     

Soluble mediators from mononuclear cells increase the synthesis of glycosaminoglycan by dermal fibroblast cultures derived from normal subjects and progressive systemic sclerosis patients

Dermal fibroblast cultures from patients with progressive systemic sclerosis (PSS) synthesize up to 5 times more glycosaminoglycan (GAG) than normal cultures. In an in vitro model of fibroblast-lymphocyte interactions, we show that the supernatants of activated mononuclear cells (MNC) modulate GAG synthesis, as measured by the incorporation of 3H-glucosamine into GAG following incubation of the confluent fibroblast monolayers with active supernatant preparations. GAG accumulation was selectively increased up to 18 times in normal dermal fibroblast cultures. Cell viability was not affected, and 3H-thymidine uptake and cell numbers were depressed in cultures treated with the supernatants. In contrast to normal dermal fibroblast cultures, PSS fibroblasts responded to MNC supernatants by only a 1-2-fold increase in GAG. Supernatants of concanavalin A-activated PSS MNC had higher stimulatory activity than those of normal MNC. Supernatants made with MNC that had been depleted of monocytes on Sephadex G-10 columns were only minimally stimulatory. The GAG-stimulatory supernatants modulated the synthesis, but not the degradation of GAG. Gel filtration on a calibrated Sephadex G-100 column indicated the presence of stimulatory activity in both the 50,000 and 15,000 molecular weight fractions. These activities were trypsin-sensitive, but had different susceptibilities to heat. The active column fractions also contained interleukin-1 activity, as shown in an assay measuring proliferation of mouse thymocytes. Like our factors, interleukin-1 preparations increased GAG in normal and PSS dermal fibroblasts. Products of activated MNC may modulate normal and pathologic processes in human skin.     

Externalization of annexin I from a folliculo-stellate-like cell line

Our recent studies on rat pituitary tissue suggest that the annexin I-dependent inhibitory actions of glucocorticoids may not be exerted directly on endocrine cells but indirectly via folliculo-stellate (FS) cells. FS cells contain glucocorticoid receptors and abundant annexin I. We have studied the localization of annexin I in FS cells and the ability of dexamethasone to induce annexin I secretion by an FS (TtT/GF) cell line, using Western blotting and immunofluorescence microscopy. Exposure of TtT/GF cells to dexamethasone (0.1 micro M, 3 h) caused an increase in the amount of annexin I protein in the intracellular compartment and attached to the surface of the cells. In nonpermeabilized cells, immunofluorescence labeling revealed that annexin I immunoreactivity was associated with the cell surface and concentrated in focal patches on the ends of cytoplasmic processes; dexamethasone (0.1 micro M, 3 h) increased both the number and intensity of these foci. Immunogold electron microscopy confirmed in anterior pituitary tissue the presence of immunoreactive-annexin at the surface of FS cell processes contacting endocrine cells. These data support our hypothesis that annexin I is released by FS cells in response to glucocorticoids to mediate glucocorticoid inhibitory actions on pituitary hormone release via a juxtacrine mechanism.     

The extended Kalman filter for continuous glucose monitoring

Glucose monitoring is a problem with evolving solutions using sensors and data processing techniques that are continually improving. This paper presents the development and application of the extended Kalman filter to the problem of real-time estimation of blood glucose levels and is consistent with sensors based on optical, electrical, or chemical processes. The structure of the extended Kalman filter provides the capability to systematically accommodate new information as it develops. This flexibility and the potential for performance improvement are demonstrated by processing patient data files generated using the Medtronic (Northridge, CA) MiniMed continuous glucose monitoring system (CGMS).