No abstract available.
Fever* ; Thermometry* ; Ultrasonography*

PURPOSE: We performed invasive thermometry to verify the elevation of local temperature in the liver during hyperthermia. MATERIALS AND METHODS: Three 40-kg pigs were used for the experiments. Under general anesthesia with ultrasonography guidance, two glass fiber-optic sensors were placed in the liver, and one was placed in the peritoneal cavity in front of the liver. Another sensor was placed on the skin surface to assess superficial cooling. Six sessions of hyperthermia were delivered using the Celsius TCS electro-hyperthermia system. The energy delivered was increased from 240 kJ to 507 kJ during the 60-minute sessions. The inter-session cooling periods were at least 30 minutes. The temperature was recorded every 5 minutes by the four sensors during hyperthermia, and the increased temperatures recorded during the consecutive sessions were analyzed. RESULTS: As the animals were anesthetized, the baseline temperature at the start of each session decreased by 1.3degrees C to 2.8degrees C (median, 2.1degrees C). The mean increases in temperature measured by the intrahepatic sensors were 2.42degrees C (95% confidence interval [CI], 1.70-3.13) and 2.67degrees C (95% CI, 2.05-3.28) during the fifth and sixth sessions, respectively. The corresponding values for the intraperitoneal sensor were 2.10degrees C (95% CI, 0.71-3.49) and 2.87degrees C (1.13-4.43), respectively. Conversely, the skin temperature was not increased but rather decreased according to application of the cooling system. CONCLUSION: We observed mean 2.67degrees C and 2.87degrees C increases in temperature at the liver and peritoneal cavity, respectively, during hyperthermia. In vivo real-time thermometry is useful for directly measuring internal temperature during hyperthermia.
Anesthesia, General ; Animals ; Fever* ; Glass ; Liver* ; Peritoneal Cavity ; Skin ; Skin Temperature ; Swine ; Thermometry ; Ultrasonography

BACKGROUND: Measurement of body temperature is an important parameter inpatient management in many clinical condition. Failure to reach minimal acceptable and has necessitated the application of additional therapy. The authors developed a new, simple, accurate thermometry system, which could be used to undertake precise temperature measurement for various clinical conditions. MATERIALS AND METHODS: A new thermometry system using a specially designed temperature detecting and display system was developed. This system contains a temperature detecting sensor(LM 35CZ), which enables multiple serual checking of heat, data collection and processing computer, and 3-dimensional display system. It provides realtime volumetric visualization of temperature of a defined volume and stores and prints the data. RESULTS: With this system, temperature can be measured at multiple interesting sites simultaneously , demonstrated as a 3-dimensional temperature distribution and stored. In well-controlled, systematic experiments a significant correlation has been observed between standard temperature using this system at carious measuring points. CONCLUSION: This thermonetry system is a real-time measurement system, which can demonstrate 3-dimensional heat distribution in experimental phantom and human body and can be used for diagnosing abnormal conditions. In addition, this system reduces the nursing staff work load, providing them more time for long term care to patients.
Body Temperature ; Data Collection ; Hot Temperature ; Human Body ; Humans ; Inpatients ; Long-Term Care ; Nursing Staff ; Thermometry*

PURPOSE: To investigate the feasibility and accuracy of Proton Resonance Frequency (PRF) shift based magnetic resonance (MR) temperature mapping utilizing the selfdeveloped center array-sequencing phase unwrapping (PU) method for non-invasive temperature monitoring. MATERIALS AND METHODS: The computer simulation was done on the PU algorithm for performance evaluation before further application to MR thermometry. The MR experiments were conducted in two approaches namely PU experiment, and temperature mapping experiment based on the PU technique with all the image postprocessing implemented in MATLAB. A 1.5T MR scanner employing a knee coil with T2* GRE (Gradient Recalled Echo) pulse sequence were used throughout the experiments. Various subjects such as water phantom, orange, and agarose gel phantom were used for the assessment of the self-developed PU algorithm. The MR temperature mapping experiment was initially attempted on the agarose gel phantom only with the application of a custom-made thermoregulating water pump as the heating source. Heat was generated to the phantom via hot water circulation whilst temperature variation was observed with T-type thermocouple. The PU program was implemented on the reconstructed wrapped phase images prior to map the temperature distribution of subjects. As the temperature change is directly proportional to the phase difference map, the absolute temperature could be estimated from the summation of the computed temperature difference with the measured ambient temperature of subjects. RESULTS: The PU technique successfully recovered and removed the phase wrapping artifacts on MR phase images with various subjects by producing a smooth and continuous phase map thus producing a more reliable temperature map. CONCLUSION: This work presented a rapid, and robust self-developed center arraysequencing PU algorithm feasible for the application of MR temperature mapping according to the PRF phase shift property.
Artifacts ; Citrus sinensis ; Computer Simulation ; Heating ; Hot Temperature ; Knee ; Magnetic Resonance Spectroscopy ; Protons ; Sepharose ; Thermography ; Thermometry ; Water

PURPOSE: The objective of this study is to determine the effect of physical changes on MR temperature imaging at 7.0T and to examine proton-resonance-frequency related changes of MR phase images and T1 related changes of MR magnitude images, which are obtained for MR thermometry at various magnetic field strengths. MATERIALS AND METHODS: An MR-compatible capacitive-coupled radio-frequency hyperthermia system was implemented for heating a phantom and swine muscle tissue, which can be used for both 7.0T and 3.0T MRI. To determine the effect of flip angle correction on T1-based MR thermometry, proton resonance frequency, apparent T1, actual flip angle, and T1 images were obtained. For this purpose, three types of imaging sequences are used, namely, T1-weighted fast field echo with variable flip angle method, dual repetition time method, and variable flip angle method with radio-frequency field nonuniformity correction. RESULTS: Signal-to-noise ratio of the proton resonance frequency shift-based temperature images obtained at 7.0T was five-fold higher than that at 3.0T. The T1 value increases with increasing temperature at both 3.0T and 7.0T. However, temperature measurement using apparent T1-based MR thermometry results in bias and error because B1 varies with temperature. After correcting for the effect of B1 changes, our experimental results confirmed that the calculated T1 increases with increasing temperature both at 3.0T and 7.0T. CONCLUSION: This study suggests that the temperature-induced flip angle variations need to be considered for accurate temperature measurements in T1-based MR thermometry.
Bias (Epidemiology) ; Fever ; Heating ; Hot Temperature ; Magnetic Fields ; Magnetic Resonance Imaging ; Methods ; Protons ; Signal-To-Noise Ratio ; Swine ; Thermometry

This article reviews the historical development and up-to-date state of thermometric technologies for measuring human body temperature (BT) from two aspects: measurement methodology and signifi cance interpretation. Since the fi rst systematic and comprehensive study on BT and its relation to human diseases was conducted by Wunderlich in the late 19th century, BT has served as one of the most fundamental vital signs for clinical diagnosis and daily healthcare. The physiological implication of BT set point and thermoregulatory mechanisms are briefl y outlined. Infl uential determinants of BT measurement are investigated thoroughly. Three types of BT measurement, i.e., core body temperature, surface body temperature and basal body temperature, are categorized according to its measurement position and activity level. With the comparison of temperature measurement in industrial fi elds, specialties in technological and biological aspects in BT measurement are mentioned. Methodologies used in BT measurement are grouped into instrumental methods and mathematical methods. Instrumental methods utilize results of BT measurements directly from temperature-sensitive transducers and electronic instrumentations by the combination of actual and predictive measurement, invasive and noninvasive measurement. Mathematical methods use several numerical models, such as multiple regression model, autoregressive model, thermoregulatory mechanism-based model and the Kalman fi lter-based method to estimate BT indirectly from some relevant vital signs and environmental factors. Thermometry modalities are summarized on the dichotomies into invasive and noninvasive, contact and noncontact, direct and indirect, free and restrained, 1-D and n-D. Comprehensive interpretation of BT has an equal importance as the measurement of BT. Two modes to apply BT are classifi ed into real-time applications and long-term applications. With rapid advancement in IoT infrastructure, big data analytics and AI platforms, prospects for future development in thermometry and interpretation of BT are discussed.
Basal Bodies ; Body Temperature ; Delivery of Health Care ; Diagnosis ; Human Body ; Humans ; Methods ; Thermometers ; Thermometry ; Transducers ; Vital Signs

In order to assess the effects of radiofrequency-induced local hyperthermia on the normal liver, histopathologic findings and biochemical changes after localized hyperthemia in canine liver were studied. Hyperthermia was externally administered using the Thermotron RF-8 (Yamamoto Vinyter Co., Japan; Capacitive type heating machine) with parallel opposed electrodes. Thirteen dogs were used and allocated into one control group (N=3) and two treatment groups according to the treatment temperature. GroupI(N=5) was heated with 42.5+/-0.5degree C for 30 minutes, and GroupII(N=5) was heated with 45+/-0.5degree C for 15-30 minutes. Samples of liver tissue were obtained through a needle biopsy immediately afterhyperthermia and 7, 14 and 28 days after treatment and examined for SGOT, SGPT and alkaline phosphatase. Although SGOT and SGPT were elevated after hyperthermia in both groups (three of five in each group), there was no liver cell necrosis or hyperthermia related mortality in GroupI. A hydropic swelling of hepatocytes was prominent histologic finding. Hyperthermia with 45degree C for 30 minutes was fatal and showed extensive liver cell necrosis. In conclusion, liver damage day heat of 42.5+/-0.5degree C for 30 minutes is reversible, and liver damage by heat of 45+/-0.5degree C for 30 minutes can be fatal or irreversible. However, these results cannot be applied directly to human trial. Therefore, in order to apply hyperthermic treatment on human liver tumor safely, close observation of temperature with proper thermometry is mandatory. Hyperthermic treatment should be confined to the tumor area while sparing a normal liver as much as possible.
Alanine Transaminase ; Alkaline Phosphatase ; Animals ; Aspartate Aminotransferases ; Biopsy, Needle ; Dogs ; Electrodes ; Fever ; Heating ; Hepatocytes ; Hot Temperature ; Humans ; Hyperthermia, Induced* ; Japan ; Liver* ; Mortality ; Necrosis ; Thermometry

Magnetic resonance-guided focused ultrasound (MRgFUS) is a new emerging neurosurgical procedure applied in a wide range of clinical fields. It can generate high-intensity energy at the focal zone in deep body areas without requiring incision of soft tissues. Although the effectiveness of the focused ultrasound technique had not been recognized because of the skull being a main barrier in the transmission of acoustic energy, the development of hemispheric distribution of ultrasound transducer phased arrays has solved this issue and enabled the performance of true transcranial procedures. Advanced imaging technologies such as magnetic resonance thermometry could enhance the safety of MRgFUS. The current clinical applications of MRgFUS in neurosurgery involve stereotactic ablative treatments for patients with essential tremor, Parkinson's disease, obsessive-compulsive disorder, major depressive disorder, or neuropathic pain. Other potential treatment candidates being examined in ongoing clinical trials include brain tumors, Alzheimer's disease, and epilepsy, based on MRgFUS abilities of thermal ablation and opening the blood-brain barrier. With the development of ultrasound technology to overcome the limitations, MRgFUS is gradually expanding the therapeutic field for intractable neurological disorders and serving as a trail for a promising future in noninvasive and safe neurosurgical care.
Acoustics ; Alzheimer Disease ; Blood-Brain Barrier ; Brain Neoplasms ; Depressive Disorder, Major ; Epilepsy ; Essential Tremor ; High-Intensity Focused Ultrasound Ablation ; Humans ; Magnetic Resonance Imaging ; Nervous System Diseases ; Neuralgia ; Neurosurgery* ; Neurosurgical Procedures ; Obsessive-Compulsive Disorder ; Parkinson Disease ; Skull ; Thermometry ; Transducers ; Ultrasonography*