Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Thermometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1995

Use of infrared thermometry to measure lavage and intravenous fluid temperature.

A study was conducted to determine the accuracy of tympanic thermometers for measuring the temperature of warmed fluids in fluid bags and in tubing at the delivery site (ie, beside the intravenous [IV] catheter). One-liter 0.9% saline bags were warmed in a microwave oven. A thermocouple electronic temperature probe was then used to measure the reference temperature. The probe was inserted into each bag and bathed in the fluid. Temperature changes were recorded simultaneously over a 20-minute period using the probe and a First Temp Tympanic Thermometer (Intelligent Medical Systems, Inc, Carlsbad, CA). The warmed fluid was then allowed to run through microdrip IV tubing. Temperature of the effluent was measured in the tubing using the tympanic thermometer externally and the probe internally at the same point. The two measures were compared using linear regression and Student's t tests. Overall, the correlation between the two probes was r = 0.99 for both the fluid bags and the IV tubing. The overall mean differences were small, 0.7 degrees C and 1.2 degrees C for the bags and tubing, respectively, but they were statistically different (P > .05). Data were analyzed in three temperature ranges: < 36 degrees C, 36 degrees C to 41 degrees C, and 41 degrees C. Again, small differences were found on the order of 1 degree C. It was concluded that infrared thermometry is an accurate method for measuring the initial and delivery temperature of warmed fluids. Although tympanic thermometer measurements were statistically different from reference readings in certain temperature ranges, these differences were small and not clinically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed2005

In vivo MR thermometry of frozen tissue using R2* and signal intensity.

Cryoablation is one of several minimally invasive treatments that may be suitable for a targeted treatment of prostate cancer. Because efficacy is improved when a sufficiently cold end temperature is reached, the purpose of this work was to demonstrate an image-based thermometry method that could provide temperature maps throughout the frozen tissue. In five in vivo canine prostate cryoablation experiments performed under magnetic resonance imaging guidance, two MR parameters were measured and correlated to temperature: R2* and changes in signal intensity. R2* is elevated approximately linearly as tissue temperature decreases below the freezing point, while the signal intensity decreases exponentially. In vivo temperature maps with isotherms at -5 degrees C, -15 degrees C, and -30 degrees C are demonstrated.

Animals↗
PubMed2005

Infrared ear thermometry in the critically ill patient.

OBJECTIVE: The purpose of this clinical study was to determine the accuracy of infrared tympanic membrane thermometry compared to axillary temperature (tempAx) for detecting body temperature reliably in critically ill patients in the daily practice. MATERIALS AND METHODS: Fifty adult patients admitted to a medical-surgical intensive care unit of an acute-care teaching hospital in Seville, Spain, during a 2-month period underwent prospective and simultaneous measurements of body temperature using a mercury-in-glass thermometer placed at the axilla of the dominant arm for at least 3 minutes and an infrared thermometer (ThermoScan 07, Braun Corporation, Kronberg, Germany) in both ears. RESULTS: A total of 429 simultaneous measurements of axillary temperature (tempAx) and tympanic temperature (tempTT) were made. The mean +/- SD tempAx was 36.90 degrees C +/- 1.06 degrees C and the mean tempTT was 36.94 degrees C +/- 0.97 degrees C ( P = NS; 95% CI, -0.18 to 0.10), with a difference between tempTT and tempAx means of 0.04 degrees C. There was a statistically significant correlation between tempAx and tempTT ( r = 0.813, P < .0005). When 20 extreme readings of both methods (<34.2 degrees C and >39.8 degrees C) were excluded, the mean tempAx was 36.91 degrees C +/- 0.86 degrees C and the mean tempTT was 36.9 degrees C +/- 0.89 degrees C ( P = NS; 95% CI, -0.05 to 0.06), with a difference of 0.01 degrees C and a statistically significant correlation between both measurements ( r = 0.80, P < .0005). The sensitivity and specificity of tempTT for different thresholds were 74% and 85% for 37 degrees C, 70% and 95% for 38 degrees C, and 25% and 99.8% for 39 degrees C, respectively. The negative predictive value for 39 degrees C was 99%. CONCLUSIONS: In adult intensive care unit patients, the infrared tympanic thermometer (ThermoScan 07) produced highly reliable measurements when compared to tempAx measured using a conventional mercury-in-glass thermometer. Both methods correlated positively and significantly.

Adolescent↗
PubMedDate not supplied

Digitized infrared segmental thermometry: time requirements for stable recordings.

OBJECTIVES: Digitized infrared segmental thermometry (DIST) is a method for measuring and recording skin surface body temperatures. The project evaluated the required length of time for patients to acclimatize their core body temperature to ambient conditions to obtain stable DIST readings. METHODS: Seventeen subjects were allowed a 20-minute acclimatizing period in a temperature-controlled room. The bilateral DIST temperature was measured with thermistors in combination with infrared cameras (IRCs) at the C4 and L4 levels. All IRC temperatures were recorded after a 20-minute stabilization period. The room temperature and relative humidity were recorded throughout all trials. The acclimatization trend was computed from the 20- to 24-minute period for the IRCs, and the acclimatization trend was computed continuously for a total of 30 minutes (at 2-minute intervals) for 5 days. RESULTS: We discovered a stabilization trend in the early trial stages, with the thermistor recordings between 8 and 16 minutes. The IRC trend was also conclusive for the core temperature requirements. CONCLUSIONS: This study determined a core body temperature acclimatization trend tested among patients using thermistor recordings in a controlled environment. Based on these findings, we recommend acclimatization in a temperature- and humidity-controlled environment for a minimum 8-minute period, followed by an 8-minute maximum recording period with the patient in a prone position to obtain accurate DIST recordings.

Acclimatization↗
PubMed2005

Solid-state 27Al MRI and NMR thermometry for catalytic applications with conventional (liquids) MRI instrumentation and techniques.

Multidimensional images of Al2O3 pellets, cordierite monolith, glass tube, polycrystalline V2O5 and other materials have been detected by 27Al, 51V, and 23Na NMR imaging using techniques and instrumentation conventionally employed for imaging of liquids. These results demonstrate that, contrary to the widely accepted opinion, imaging of "rigid" solids does not necessarily require utilization of solid state NMR imaging approaches, pulse sequences and hardware even for quadrupolar nuclei which exhibit line widths in excess of 100 kHz, such as 51V in polycrystalline V2O5. It is further demonstrated that both 27Al NMR signal intensity and spin-lattice relaxation time decrease with increasing temperature and thus can potentially serve as temperature sensitive parameters for spatially resolved NMR thermometry.

Algorithms↗
PubMed2006

k-space inherited parallel acquisition (KIPA): application on dynamic magnetic resonance imaging thermometry.

In this study, a novel method for dynamic parallel image acquisition and reconstruction is presented. In this method, called k-space inherited parallel acquisition (KIPA), localized reconstruction coefficients are used to achieve higher reduction factors, and lower noise and artifact levels compared to that of generalized autocalibrating partially parallel acquisition (GRAPPA) reconstruction. In KIPA, the full k-space for the first frame and the partial k-space for later frames are required to reconstruct a whole series of images. Reconstruction coefficients calculated for different segments of k-space from the first frame data set are used to estimate missing k-space lines in corresponding k-space segments of other frames. The local determination of KIPA reconstruction coefficients is essential to adjusting them according to the local signal-to-noise ratio characteristics of k-space data. The proposed algorithm is applicable to dynamic imaging with arbitrary k-space sampling trajectories. Simulations of magnetic resonance thermometry using the KIPA method with a reduction factor of 6 and using dynamic imaging studies of human subjects with reduction factors of 4 and 6 have been performed to prove the feasibility of our method and to show apparent improvement in image quality in comparison with GRAPPA for dynamic imaging.

Algorithms↗
PubMed1993

Tympanic thermometry for recording basal body temperatures.

Evaluation of 12 menstrual cycles using oral, rectal, and TM temperature measuring devices (over 2,000 individual readings) confirmed the ovulatory thermal shift was equally detected with TM thermometry compared with the traditional methods. Although a single TM reading was satisfactory, an average of three successive readings provided a smoother graph (decreased variance). The device appears acceptable, and even preferred, for recording BBT charts, primarily because of its nearly instantaneous readings.

Adolescent↗
PubMed1995

Tympanic membrane thermometry in the care of out-of-hospital patients.

STUDY OBJECTIVES: To determine the effectiveness of tympanic membrane (TM) thermometry in the out-of-hospital setting and to characterize the patients with abnormal out-of-hospital temperatures. DESIGN: Prospective, randomized, single-month study. SETTING: Inner city. PARTICIPANTS: Subjects transported by ambulance for whom consent was obtainable. RESULTS: TM probes set to rectal equivalent were assigned to three of the ambulance units of the local health department on randomly selected shifts during August 1992, one half at night and one half during the day. Simultaneous left and right ear temperatures at the scene and at the hospital, ambient temperatures, and patient's hospital temperatures were recorded. Other data recorded included each patient's mental status, activity level, and environment temperature. Paramedics noted whether they suspected a temperature problem before using the probe and whether any treatment was directed toward the patient's temperature. Regression, bias analysis, and chi 2 testing were performed; P was considered significant if it was less than .05. Right and left ear TM temperatures were correlated both at the scene and at the hospital (r = .91 and .92, respectively). TM temperatures and hospital temperatures were also correlated (r = .83 for right ear and .78 for left ear). Evaluation of agreement indicated that TM and hospital methods were equal, with a bias of -0.55 degrees F for oral and +0.66 degrees F for rectal temperatures. Thirty-two subjects (17%) were hyperthermic at the scene; of these, 9 of 32 (28%) were suspected before use of the probe. The paramedics initially treated 5 of the 9 suspected to have a temperature-related problem before using the probe and none of the 23 who were not suspected before using the probe (chi 2, P < .001). CONCLUSION: The TM probe functioned well despite a month of vigorous handling. Temperature correlation with the gold standard and between ears was acceptable in this setting. Presence of the probe did not help with the management of hyperthermic patients in this study.

Adolescent↗
PubMed1998

Magnetic resonance thermometry during hyperthermia for human high-grade sarcoma.

PURPOSE: To determine the feasibility of measuring temperature noninvasively with magnetic resonance imaging during hyperthermia treatment of human tumors. METHODS: The proton chemical shift detected using phase-difference magnetic resonance imaging (MRI) was used to measure temperature in phantoms and human tumors during treatment with hyperthermia. Four adult patients having high-grade primary sarcoma tumors of the lower leg received 5 hyperthermia treatments in the MR scanner using an MRI-compatible radiofrequency heating applicator. Prior to each treatment, an average of 3 fiberoptic temperature probes were invasively placed into the tumor (or phantom). Hyperthermia was applied concurrent with MR thermometry. Following completion of the treatment, regions of interest (ROI) were defined on MR phase images at each temperature probe location, in bone marrow, and in gel standards placed outside the heated region. The median phase difference (compared to pretreatment baseline images) was calculated for each ROI. This phase difference was corrected for phase drift observed in standards and bone marrow. The observed phase difference, with and without corrections, was correlated with the fiberoptic temperature measurements. RESULTS: The phase difference observed with MRI was found to correlate with temperature. Phantom measurements demonstrated a linear regression coefficient of 4.70 degrees phase difference per degree Celsius, with an R2 = 0.998. After human images with artifact were excluded, the linear regression demonstrated a correlation coefficient of 5.5 degrees phase difference per degree Celsius, with an R2 = 0.84. In both phantom and human treatments, temperature measured via corrected phase difference closely tracked measurements obtained with fiberoptic probes during the hyperthermia treatments. CONCLUSIONS: Proton chemical shift imaging with current MRI and hyperthermia technology can be used to monitor and control temperature during treatment of large tumors in the distal lower extremity.

Adult↗
PubMed1999

Transrectal ultrasound applicator for prostate heating monitored using MRI thermometry.

PURPOSE: For potential localized hyperthermia treatment of tumors within the prostate, an ultrasound applicator consisting entirely of nonmagnetic materials for use with magnetic resonance imaging (MRI) has been developed and tested on muscle tissue ex vivo and in vivo. METHODS AND MATERIALS: A partial-cylindrical intracavitary transducer consisting of 16 elements in a 4 x 4 pattern was constructed. It produced a radially propagating acoustic pressure field. Each element of this array (1.5 x 0.75 cm), operating at 1.5 MHz, could be separately powered to produce a desired energy deposition pattern within a target volume. Spatial and temporal temperature elevations were determined using the temperature-dependent proton resonant frequency (PRF) shift and phase subtraction of MR images acquired during ultrasonic heating. Four rabbits were exposed to the ultrasound to raise the local tissue temperature to 45 degrees C for 25 minutes. Six experiments compared thermocouple temperature results to PRF shift temperature results. RESULTS: The tests showed that the multi-element ultrasound applicator was MRI-compatible and allowed imaging during sonication. The induced temperature distribution could be controlled by monitoring the RF power to each transducer element. Therapeutic temperature elevations were easily achieved in vivo at power levels that were about 16% of the maximum system power. From the six thermocouple experiments, comparison between the thermocouple temperature and the PRF temperature yielded an average error of 0.34+/-0.36 degrees C. CONCLUSIONS: The MRI-compatible intracavitary applicator and driving system was able to control the ultrasound field and temperature pattern in vivo. MRI thermometry using the PRF shift can provide adequate temperature accuracy and stability for controlling the temperature distribution.

Animals↗
PubMed2001

Fiberoptic infrared radiometer for real time in situ thermometry inside an MRI system.

A warm body emits radiation whose intensity I is dependent on the surface temperature T. For T near room temperature this radiation is mostly in the mid-IR. Radiometric measurement of I is often used for non contact thermometry. Temperature measurements in situ and in remote locations can be carried out using optical fibers, but one needs fibers that are highly transparent in the mid-IR. Our group has developed fibers made of silver halides. These are flexible, nontoxic, not hygroscopic and highly transparent in the mid IR. These fibers served for the development of a novel fiberoptic radiometer. Using this radiometer we have measured the temperatures of samples while being imaged in an MRI system. The presence of the fibers inside the MRI system did not interfere with the operation of the MRI nor did not the MRI system affect the radiometer. The temperature measurements were made with accuracy of 0.3 degrees C, response time of 1 s and spatial resolution of 1 mm. Fiberoptic radiometers would be highly suitable for temperature measurement of human tissues, for example during surgical procedures done inside an MRI system.

Calibration↗
PubMed2003

[Non invasive intracranial hyperthermia with Electric Capacitive Transference -ECT- Intratumoral and cerebral thermometry results].

The aim of this work is to present the results of thermic increase obtained at the brain and intratumoral levels through a non invasive technique -Electric Capacitive Transference- (ECT), developed in 1985 by Indiba. A review of the literature does not provide any reference of cerebral and intratumoral thermometry in real time with a non invasive technique of intracranial hyperthermia. In the 8 studied patients, the increases of temperature in the brain, ranged between 0.7 and 1.5 degrees C in relation to the depth of the thermometric probe and the incidence angle of the external electrode. Between tumoral and perilesional brain tissues, thermic increase was 0.3 to 0.7 degrees C greater at tumoral level. The observation that in no case the surrounding brain tissue registered a temperature over 39.2 degrees C supports the harmlessness of the technique regarding the potential damage to healthy brain tissue and seems to confirm previous data obtained in anatomopathological studies in animal experimentation performed in 1990, which showed an absence of lesions in tissues and organs. The greater and somewhat more prolonged thermic increase observed at tumoral level has been called the "greenhouse effect".

Brain Neoplasms↗
PubMed1996

Tympanic thermometry and minor ear surgery.

Infra-red tympanic thermometry is a relatively new technique for measuring body temperature which requires the minimum of co-operation and is quick and easy to use. It is therefore ideal for use in children. Its use is becoming more widespread and as it is theoretically possible that minor ear surgery may interfere with function its reliability in these patients may be in question. Twenty-two children (mean age 5.3 years) who underwent myringotomy +/- grommet insertion had the tympanic temperature of each ear measured immediately before, and 15 minutes after, surgery on the recovery ward. No difference was found between the pre- and post-operative temperatures (mean difference--0.1 degree C, p > 0.1, paired t-test, hypothesized difference of 0). This thermometer appears to be a reliable way of monitoring body temperature on a paediatric ENT recovery ward in patients who have undergone minor ear surgery.

Adolescent↗
PubMed2000

Monitoring temperature changes in capillary electrophoresis with nanoliter-volume NMR thermometry.

Nanoliter-volume proton nuclear magnetic resonance (NMR) spectroscopy is used to monitor the electrolyte temperature during capillary electrophoresis (CE). By measuring the shift in the proton resonance frequency of the water signal, the intracapillary temperature can be recorded noninvasively with subsecond temporal resolution and spatial resolution on the order of 1 mm. Thermal changes of more than 65 degrees C are observed under both equilibrium and nonequilibrium conditions for typical CE separation conditions. Several capillary and buffer combinations are examined with external cooling by both liquid and air convection. Additionally, NMR thermometry allows nonequilibrium temperatures in analyte bands to be monitored during a separation. As one example, a plug of 1 mM NaCl is injected into a capillary filled with 50 mM borate buffer. Upon reaching the NMR detector, the temperature in the NaCl band is more than 20 degrees C higher than the temperature in the surrounding buffer. Such observations have direct applicability to a variety of studies, including experiments which utilize sample stacking and isotachophoresis.

Electrophoresis, Capillary↗
PubMed2006

Raman thermometry measurements of free evaporation from liquid water droplets.

Recent theoretical and experimental studies of evaporation have suggested that on average, molecules in the higher-energy tail of the Boltzmann distribution are more readily transferred into the vapor during evaporation. To test these conclusions, the evaporative cooling rates of a droplet train of liquid water injected into vacuum have been studied via Raman thermometry. The resulting cooling rates are fit to an evaporative cooling model based on Knudsen's maximum rate of evaporation, in which we explicitly account for surface cooling. We have determined that the value of the evaporation coefficient (gamma(e)) of liquid water is 0.62 +/- 0.09, confirming that a rate-limiting barrier impedes the evaporation rate. Such insight will facilitate the formulation of a microscopic mechanism for the evaporation of liquid water.

Spectrum Analysis, Raman↗
PubMed2000

Microwave radiometric thermometry and its potential applicability to ablative therapy.

INTRODUCTION: [corrected] Current techniques for estimating catheter tip temperature in ablative therapy for cardiac arrhythmias rely on thermocouples or thermistors attached to or embedded in the tip electrode. These methods may reflect the electrode temperature rather than the tissue temperature during electrode cooling so that the highest temperature away from the ablation site may go undetected. A microwave radiometer is capable of detecting microwave radiation as a result of molecular motion. In this study, we evaluated microwave radiometric thermometry as a new technique to monitor temperature away from the electrode tip during ablative therapy utilizing a saline model. METHODS AND RESULTS: A microwave radiometer antenna and fluoroptic thermometer were inserted in a test tube with circulating room temperature saline kept constant at 23.5 degrees C while the surrounding saline bath was heated from 37 degrees C to 70 degrees C. For every degree rise in the warm saline bath placed either 5 mm or 8 mm from the radiometer antenna, the radiometer temperature changed 0.26 degrees C and 0.14 degrees C respectively while the fluoroptic temperature probe remained constant at 23.5 degrees C. The radiometer temperature was highly correlated with the warm saline bath temperature (R(2)=0.997 for warm saline 5 mm from the antenna, R(2)=0.991 for warm saline 8 mm from the antenna). CONCLUSIONS: Microwave radiometry can estimate distant temperatures by detecting microwave electromagnetic radiation. The sensitivity of the microwave radiometer is also distance-dependent. The microwave radiometer thus serves as a promising instrument for monitoring temperatures at depth away from the catheter-electrode tip in ablative therapy for cardiac arrhythmias.

Calibration↗
PubMed2006

[Clinical thermometry--theory and critical approach].

The assessment of fever is complex. It must not only focus on the patient in question. Rather, as a first factor to be considered, clinical thermometry has its technical and methodological problems. Every method has its own pitfalls. Second, any assessed body temperature reflects a "local" body temperature which, again, is affected by many factors. In addition, physiological set points of normal body temperature vary among individuals, and, even in a given individual, body temperature has its physiological variations. In all, intra- and interindividual variabilities in measured "normal" body temperature are large (< 2 degrees C) which makes it difficult to define normality. No question, all the factors mentioned are equally involved when body temperature is assessed in the febrile patient. Results (particularly those of tympanic measurements) may be deceptive and must be interpreted with scrutiny in the broad context of the patient assessment. In adults, fever should be measured by the sublingual method, in the non-cooperating patient, in the newborn and in toddlers rectally.

Adult↗
PubMed1998

[Verification of MR thermometry by means of an in vivo intralesional, fluoroptic temperature measurement for laser-induced thermotherapy ov liver metastases].

PURPOSE: To evaluate the correlation of MR-measured changes of signal intensity and invasive fluoroptic temperature measurements during MR-guided LITT of liver metastases. MATERIALS AND METHODS: In 15 patients with proven liver metastases of colorectal carcinoma, MR-guided LITT was performed with a percutaneous approach in a multiapplicator technique. Two temperature sensitive T1-weighted sequences (FLASH-2D- and TurboFLASH-sequences) were used to map the spatial and temporal distribution of Nd:YAG laser effects. Parallel fluoroptic temperature measurements were carried out by means of an inserted probe in a distance of 5-26 mm (mean: 14 mm) from the laser applicator. RESULTS: In both sequences a gradually increasing signal loss could be documented during laser application which proved to be reversible after cessation of energy deposition. the percentage of decrease in signal intensity correlated directly with the measured increase of temperature. Invasive fluoroptical evaluation of temperature distribution after 10 min exposure time showed at 5 mm distance from the applicator an increase of temperature of 35 degrees C, in 10 mm distance a mean increase of 9 degrees C +/- 1.7, in 15 mm a mean increase of 7 degrees C +/- 1.6 and in 20 mm a mean increase of 3 degrees C +/- 0.5. This is evidence of thermal tissue damage up to 3 cm in diameter with laser monoapplication. The qualitative evaluation revealed a reproducible correlation of the extent of signal loss around the applicator and the finally induced degree of necrosis. CONCLUSION: Invasive fluoroptical temperature measurements prove the diagnostic reliability of MR thermometry for the online monitoring of LITT of liver metastases.

Adult↗