Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Motion”

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 1,225 records · Page 68Linked to original sources
PubMed1996

Effect of motion and tension on injured flexor tendons in chickens.

This study was undertaken to evaluate the individual effects of motion and tension on the healing response of injured flexor profundus tendons in chickens. Partial midsection transverse lacerations of the profundus tendons were produced in 53 chickens. Postoperatively, they were assigned randomly to four management groups: both motion and tension; only motion, no tension; no motion, only tension; no motion and no tension. Biomechanical results at 4 weeks showed that breaking strength significantly increased with both motion and tension, significantly decreased with neither, and was intermediate with only motion or only tension. Histologic evaluation generally showed the greatest cellular activity with both motion and tension, the least with neither, and an intermediate response with one or the other alone. Collagen fiber staining was increased primarily in the tension groups. The finding that both motion and tension enhance the tendon's response to injury encourages the development of active mobilization protocols following tendon repair.

Animals↗
PubMed1983

Quantitative assessment of segmental wall motion abnormalities at rest and after atrial pacing using digital intravenous ventriculography.

Digital intravenous ventriculography lends itself readily to quantitative assessment of ventricular wall motion with computer algorithms. Forty-five patients referred for cardiac catheterization were studied by digital intravenous ventriculography (mask mode) and direct ventriculography in the 30 degrees right anterior oblique position. Quantitative wall motion was analyzed by a radial shortening method applied to both studies. Lower limits of normal radial shortening were determined for each technique and used to determine the presence or absence of wall motion disorders. The inter- and intraobserver variability of radial shortening measurements was +/- 5.3 and +/- 8.8%, respectively, with maximal discrepancies of -6 and +7% fractional shortening units. The overall agreement between the two techniques in wall motion assessment was 87% (274 of 315 radii). A subset of patients also underwent atrial pacing, and a second digital intravenous ventriculogram was obtained (5 normal subjects and 15 patients with coronary artery disease). Although analysis of wall motion at rest showed a poor sensitivity for detection of significant coronary stenoses, nine of nine patients with coronary artery disease and normal wall motion at rest showed a quantitative decrease in radial wall motion after atrial pacing. Thus, digital intravenous ventriculograms can be used to provide quantitative wall motion analyses that show a high degree of agreement with those of standard, direct left ventriculography. Atrial pacing can be used to increase the sensitivity of wall motion analysis for the detection of significant coronary disease.

Aged↗
PubMed1997

Automatic quantitation of regional myocardial wall motion and thickening from gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography.

OBJECTIVES: We developed an automatic quantitative algorithm for the measurement of regional myocardial wall motion and wall thickening from three-dimensional gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomographic images. BACKGROUND: The algorithm measures the motion of the three-dimensional endocardial surface using a modification of the centerline method, as well as wall thickening using both geometry (gaussian fit) and partial volume (counts). METHODS: The algorithm was tested using a "variable thickness" heart phantom, and the quantitative results were compared with visual segmental assessment of myocardial motion and thickening in 79 clinical patients with a wide range of ejection fractions (6% to 87%). RESULTS: Phantom measurements of simulated motion and thickening were accurate regardless of the camera used (dual or triple detector), the angular span of reconstructed data (180 degrees or 360 degrees), the amount of motion (3 or 6 mm) or the amount of thickening (33%, 50% or 100%). Quantitative measurements of segmental motion and thickening in the patients were correlated with visual scores (r = 0.668, exact agreement 72.6%, kappa 0.433 and r = 0.550, exact agreement 74.7%, kappa 0.408, respectively). Significant inverse linear relations exist between the global (summed) visual motion score and the average quantitative motion, and between the global (summed) visual thickening score and the average quantitative thickening. Automatic quantitative ejection fraction measurements correlated extremely well with average quantitative motion (r = 0.929) and thickening (r = 0.959). CONCLUSIONS: Our algorithm is accurate and may be the first automatic technique for the quantitative three-dimensional assessment of regional ventricular function in cardiology.

Aged↗
PubMed1999

Cardiac phase contrast gradient echo MRI: measurement of myocardial wall motion in healthy volunteers and patients.

A number of methods have been proposed for the noninvasive measurement of myocardial wall motion. The paper describes a strategy for assessing myocardial motion based on the sensitivity of the phase of the MR-signal to motion using a breath-hold phase contrast technique. A motion-sensitized and a motion-compensated MR-signal are measured during successive scans. The difference between the two MR-signals is used to calculate myocardial velocity in all three spatial dimensions. Postprocessing includes the transformation of the measured velocities into an internal coordinate system of the left ventricle. Also various presentation modes and further processing of the received velocity information are provided including calculation of global motion parameters. We examined 20 patients suffering from myocardial infarction. The overall left ventricular motion can be characterized by appropriate parameters describing the rotation and contraction or expansion, respectively. Regional motional disturbances are visualized using parametric images. Contrary to the highly consistent interindividual data in normal volunteers, patients showed significant localized motion deficits.

Adult↗
PubMed1995

Flow motion in peripheral diabetic neuropathy.

1. Flow motion is the cyclical variation in blood flow owing to the rhythmical opening and closing of arterioles. Previous studies have suggested that cutaneous flow motion may be altered in diabetic neuropathy but have not been consistent in their findings. 2. In order to assess the effect of diabetic peripheral neuropathy on flow motion, we have examined the frequency and amplitude of flow motion in 12 patients with diabetic peripheral neuropathy, 10 age-matched diabetic patients without peripheral neuropathy and 10 age-matched non-diabetic controls. 3. Peripheral neuropathy was diagnosed by a history of foot ulceration or chronic painful neuropathy, clinical examination and abnormal peroneal nerve conduction velocities. Blood flow, using laser Doppler flowmetry, was measured at four sites on the dorsum of both hands and feet. Flow motion was analysed using fast Fourier transform analysis, between 0.05 and 0.2 Hz, and displayed on a power spectral density graph. Predominant frequency and relative amplitude of flow motion were calculated. 4. Relative amplitude and frequency of flow motion were similar in the hands of all three groups, as was the frequency in the feet of the three groups. Relative amplitude was significantly smaller in the feet of diabetic patients with neuropathy (median 7.2%, 95% confidence interval 4.9-9.4%) than in diabetic patients without neuropathy (median 13.5%, 95% confidence interval 6.3-21.5%, P < 0.02) or in non-diabetic control subjects (median 10.3%, 95% confidence interval 6.9-27.4%, P < 0.02). 5. Flow motion amplitude is reduced in diabetic peripheral neuropathy. The control of flow motion amplitude appears to be at least partly under neurological control.

Diabetes Mellitus↗
PubMed1999

Myocardial motion imaging: a new application of power color flow and frequency-based color flow Doppler in fetal echocardiography.

OBJECTIVE: Myocardial motion imaging is a new way of looking at the fetal heart using power color flow and frequency-based color flow Doppler to demonstrate heart wall movement in color. This study set out to assess the value of myocardial motion imaging in fetal echocardiography in a routine clinical setting. DESIGN: In our hospital, all patients at high risk of carrying a fetus with a cardiac abnormality are offered detailed ultrasound scanning, including fetal echocardiography, at 20 weeks' gestation. A prospective study was carried out over a 2-month period and, in addition to conventional fetal echocardiography, myocardial motion imaging was also carried out on all patients, by means of both power color flow and frequency-based color flow Doppler ultrasound. RESULTS: Myocardial motion imaging demonstrated fetal heart wall movement in 26 of the 27 patients. Myocardial motion imaging using power color flow gave a global view of fetal heart wall movement, demonstrating both atrial and ventricular contraction simultaneously. Myocardial motion imaging using frequency-based color flow Doppler demonstrated atrial and ventricular contractions separately. In addition, as the direction of fetal heart wall motion can be color coded, atrial contractions, ventricular relaxation and ventricular contraction were demonstrated, providing a functional assessment of fetal heart wall movement. Two cases of cardiac abnormality were also studied, one case of hypoplastic left heart syndrome and one case of atrioventricular septal defect. In both cases functional information was obtained using myocardial motion imaging, and the technique also highlighted the anatomical defect. CONCLUSIONS: Myocardial motion imaging produces both a global view of fetal cardiac anatomy and a functional assessment of individual chamber contraction in the normal and abnormal heart. It may prove to be a useful adjunct to conventional color flow Doppler assessment of the fetal heart.

Adolescent↗
PubMed1996

Cross-facial nerve grafting for facial reanimation: effect on normal hemiface motion.

Reinnervation of the paralyzed hemiface with a cross-facial nerve graft (CFNG) required division of facial nerve branches on the normal hemiface to serve as axon donors. There is therefore concern about whether any impairment of normal hemiface motion occurs in the postoperative period. To minimize the likelihood of donor-side impairment, donor branches are chosen from the bucco-zygomatic region which was extensive cross branching, as opposed to be the single temporal or marginal mandibular branches. This study chose to determine quantitatively if this practice does, in fact, adversely affect the normal side hemiface motion governed by these branches, viz., eye closure, pucker, and smile. Since surgical procedures near the facial nerve (such as superficial parotidectomy) may leave the patient with transient facial weakness, even in the absence of nerve transection, the hypothesis was that hemiface motion would be impaired on the donor side during the early postoperative period (first month) secondary to edema and/or neuropraxia. However, based on the clinical observation that donor-side facial motion is not demonstrably impaired late after surgery, a further hypothesis was that any early facial motion is not demonstrably impaired late after surgery, a further hypothesis was that any early facial motion impairment would return to normal by 3 months postoperatively. Seven patients underwent sural CFNG as a primary or secondary component of their facial animation procedure. Their facial motion was quantified preoperatively and in serial postoperative examinations using the Maximal Static Response Assay (MSRA) of facial motion. Careful selection of redundant bucco-zygomatic branches of the facial nerve on the normal side for CFNG did not ultimately ( > or = 3 months postoperative) impair the important motions of eye closure, smile, or pucker. Early postoperative ( < or = 1 month) weakness of the smile was seen on both X and Y axes, indicating that both the risorius and zygomatic muscles were transiently weakened. The ability to elevate the lower eyelid was unaffected at any postoperative time point. Movement of the normal hemiface did not appear to be permanently affected by CFNG when a careful choice of redundant bucco-zygomatic donor branches was made.

Adult↗
PubMedDate not supplied

Combined corrections for attenuation, depth-dependent blur, and motion in cardiac SPECT: a multicenter trial.

BACKGROUND: The diagnostic accuracy of cardiac single photon emission computed tomography (SPECT) is limited by image-degrading factors, such as heart or subject motion, depth-dependent blurring caused by the collimator, and photon scatter and attenuation. We developed correction approaches for motion, depth-dependent blur, and attenuation and performed a multicenter validation. METHODS AND RESULTS: Motion was corrected both transversely and axially with a cross-correlation technique. Depth-dependent blurring was corrected by first back-projecting each projection and then applying a depth-dependent Wiener filter row by row. Attenuation was corrected with an iterative, nonuniform Chang algorithm, based on a transmission scan-generated attenuation map. We validated these approaches in 112 subjects, including 36 women (20 healthy volunteers, 8 angiographically normal patients, and 8 patients with coronary artery disease [CAD] found by means of angiography) and 76 men (23 healthy volunteers, 10 angiographically normal patients, and 43 patients with CAD found by means of angiography). Either technetium 99m or thallium 201 was used for emission; either gadolinium 153 or Tc-99m was used for transmission. Images were reconstructed and blindly interpreted with a 5-point scale for receiver operating characteristic analysis in 2 ways: motion correction plus a Butterworth filter, and combined motion and blur and attenuation corrections. The interpretation by means of consensus was for the overall presence of CAD and vascular territory. The receiver operating characteristic curves for overall presence and each of the 3 main coronary arteries were all shifted upward and to the left and had larger areas under the curve, for combined corrections compared with motion correction and Butterworth. Sensitivity/specificity for motion correction and Butterworth were 84/69, 64/71, 32/94, and 71/81 overall for the left anterior descending, the right coronary artery, and circumflex territories, respectively, compared with 88/92, 77/93, 50/97, and 74/95, respectively, for the combined corrections. CONCLUSIONS: The proposed combined corrections for motion, depth-dependent blur, and attenuation significantly improve diagnostic accuracy, when compared with motion correction alone.

Coronary Disease↗
PubMedDate not supplied

Quantification of back motion during asymmetric lifting.

The objective of this study was to determine how trunk motion characteristics (in all three planes of the trunk) change as a free dynamic lifting task becomes more asymmetric. Trunk motion characteristics included range of motion, velocity (peak and average), and acceleration. Previous studies have shown that trunk motion characteristics affect trunk strength as well as the action of the trunk musculature. These trunk motion characteristics were quantified as a function of seven task asymmetries and three task weights. The experimental task required the subject to lift materials in positions commonly seen in the workplace. The range of motion, peak velocity, average velocity, and peak acceleration in each plane of the body were documented during the tasks. Generally, trunk motion characteristics in all three planes increased with an increase in task asymmetry. However, with an increase in task weight all the sagittal plane parameters and one transverse plane parameter decreased. Models were constructed to predict trunk motion characteristics given a task asymmetry and weight. When these motion components were compared to dynamic strength estimates from previous studies it was found that dynamic asymmetric lifts could reduce available strength up to 21% of maximum static strength. The results provide new insight into factors associated with the risk of developing low back disorders.

Adult↗
PubMed1975

Motility in Echinosphaerium nucleofilum. I. An analysis of particle motions in the axopodia and a direct test of the involvement of the axoneme.

The motion of particles in the axopodia of Echinosphaerium nucleofilum is saltatory. In the present study, photokymograph records of 123 motions from six axopodia have been analyzed. Particles followed rectilinear paths of from 1 to 15 mum while in continuous motion at an average velocity of 0.66 plus or minus 0.32 mum/s. The velocity of the particles was variable in 36% of the cases measured. Some motions were punctuated by pauses either before continuing in the same direction or reversing. Frequently, several particles were moving at the same velocity, but neighboring particles showed no motion or moved in the opposite direction. Two particles occasionally contacted one another and travelled as a unit for varying lengths of time but subsequently moved independently. These motions reflect the underlying mechanism of motive force production. Furthermore, a glass microneedle can be substituted for the microtubular axoneme in the axopodia. In these artificial axopodia, bidirectional particle motions occurred which were similar to those in normal axopodia. Colchicine, at the threshold dose for axonemal dissolution, had no affect on these particel motions. It is concluded that the microtubular axoneme is not responsible for particle motions and also that individual microtubules are unlikely candidates for motive force production in this system.

Animals↗
PubMed2003

An experimental investigation on intra-fractional organ motion effects in lung IMRT treatments.

Respiration-induced tumour motion can potentially compromise the use of intensity-modulated radiotherapy (IMRT) as a dose escalation tool for lung tumour treatment. We have experimentally investigated the intra-fractional organ motion effects in lung IMRT treatments delivered by multi-leaf collimator (MLC). An in-house made motor-driven platform, which moves sinusoidally with an amplitude of 1 cm and a period of 4 s, was used to mimic tumour motion. Tumour motion was simulated along cranial-caudal direction while MLC leaves moved across the patient from left to right, as in most clinical cases. The dose to a point near the centre of the tumour mass was measured according to geometric and dosimetric parameters from two five-field lung IMRT plans. For each field, measurement was done for two dose rates (300 and 500 MU min(-1)), three MLC delivery modes (sliding window, step-and-shoot with 10 and 20 intensity levels) and eight equally spaced starting phases of tumour motion. The dose to the measurement point delivered from all five fields was derived for both a single fraction and 30 fractions by randomly sampling from measured dose values of each field at different initial phases. It was found that the mean dose to a moving tumour differs slightly (<2-3%) from that to a static tumour. The variation in breathing phase at the start of dose delivery results in a maximum variation around the mean dose of greater than 30% for one field. The full width at half maximum for the probability distribution of the point dose is up to 8% for all five fields in a single fraction, but less than 1-2% after 30 fractions. In general, lower dose rate can reduce the motion-caused dose variation and therefore might be preferable for lung IMRT when no motion mitigation techniques are used. From the two IMRT cases we studied where tumour motion is perpendicular to MLC leaf motion, the dose variation was found to be insensitive to the MLC delivery mode.

Biophysical Phenomena↗
PubMed2004

Online compensation for target motion with scanned particle beams: simulation environment.

Target motion is one of the major limitations of each high precision radiation therapy. Using advanced active beam delivery techniques, such as the magnetic raster scanning system for particle irradiation, the interplay between time-dependent beam and target position heavily distorts the applied dose distribution. This paper presents a simulation environment in which the time-dependent effect of target motion on heavy-ion irradiation can be calculated with dynamically scanned ion beams. In an extension of the existing treatment planning software for ion irradiation of static targets (TRiP) at GSI, the expected dose distribution is calculated as the sum of several sub-distributions for single target motion states. To investigate active compensation for target motion by adapting the position of the therapeutic beam during irradiation, the planned beam positions can be altered during the calculation. Applying realistic parameters to the planned motion-compensation methods at GSI, the effect of target motion on the expected dose uniformity can be simulated for different target configurations and motion conditions. For the dynamic dose calculation, experimentally measured profiles of the beam extraction in time were used. Initial simulations show the feasibility and consistency of an active motion compensation with the magnetic scanning system and reveal some strategies to improve the dose homogeneity inside the moving target. The simulation environment presented here provides an effective means for evaluating the dose distribution for a moving target volume with and without motion compensation. It contributes a substantial basis for the experimental research on the irradiation of moving target volumes with scanned ion beams at GSI which will be presented in upcoming papers.

Computer Simulation↗
PubMed2006

Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy.

Respiratory gating can reduce the apparent respiratory motion during imaging and treatment; however, residual motion within the gating window remains. Respiratory training can improve respiratory reproducibility and, therefore, the efficacy of respiratory-gated radiotherapy. This study was conducted to determine whether residual motion during respiratory gating is affected by patient, tumour or treatment characteristics. The specific aims of this study were to: (1) identify significant characteristics affecting residual motion, (2) investigate time trends of residual motion over a period of days (inter-session) and (3) investigate time trends of residual motion within the same day (intra-session). Twenty-four lung cancer patients were enrolled in an Institutional Review Board (IRB)-approved protocol. For approximately five sessions, 331 four-minute, respiratory motion traces were acquired with free breathing, audio instructions and audio-visual biofeedback for each patient. The residual motion was quantified by the standard deviation of the displacement within the gating window. The generalized linear model was used to obtain coefficients for each variable within the model and to evaluate the clinical and statistical significance. The statistical significance was determined by a p-value<0.05, while effect sizes of 0.1 cm (one standard deviation) were considered clinically significant. This data analysis was applied to patient, tumour and treatment variables. Inter- and intra-session variations were also investigated. The only variable that was significant for both inhale- and exhale-based gating was disease type. In addition, visual-training displacement, breathing type and Karnofsky performance status (KPS) values were significant for inhale-based gating, and dose-per-fraction was significant for exhale-based gating. Temporal respiratory variations within and between sessions were observed for individual patients. However inter- and intra-session analyses did not show significant time trends on average for any of the variables considered. The lack of significant time trends within and between sessions indicates that on average (1) there is no significant learning period for breathing training, (2) the patients did not experience training-related fatigue and (3) the margin component to account for residual motion during gated radiotherapy appears to remain constant throughout the treatment.

Computer Simulation↗
PubMed2006

Direct aperture optimization of breast IMRT and the dosimetric impact of respiration motion.

We have studied the application of direct aperture optimization (DAO) as an inverse planning tool for breast IMRT. Additionally, we have analysed the impact of respiratory motion on the quality of the delivered dose distribution. From this analysis, we have developed guidelines for balancing the desire for a high-quality optimized plan with the need to create a plan that will not degrade significantly in the presence of respiratory motion. For a DAO optimized breast IMRT plan, the tangential fields incorporate a flash field to cover the range of respiratory motion. The inverse planning algorithm then optimizes the shapes and weights of additional segments that are delivered in combination with the open fields. IMRT plans were generated using DAO with the relative weights of the open segments varied from 0% to 95%. To assess the impact of breathing motion, the dose distribution for the optimized IMRT plan was recalculated with the isocentre sampled from a predefined distribution in a Monte Carlo convolution/superposition dose engine with the breast simulated as a rigid object. The motion amplitudes applied in this study ranged from 0.5 to 2.0 cm. For a range of weighting levels assigned to the open field, comparisons were made between the static plans and the plans recalculated with motion. For the static plans, we found that uniform dose distributions could be generated with relative weights for the open segments equal to and below 80% and unacceptable levels of underdosage were observed with the weights larger than 80%. When simulated breathing motion was incorporated into the dose calculation, we observed a loss in dose uniformity as the weight of the open field was decreased to below 65%. More quantitatively, for each 1% decrease in the weight, the per cent volume of the target covered by at least 95% of the prescribed dose decreased by approximately 0.10% and 0.16% for motion amplitudes equal to 1.5 cm and 2.0 cm, respectively. When taking into account the motion effects, the most uniform and conformal dose distributions were achieved when the open segment weights were in the range of 65-80%. Within this range, high-quality IMRT plans were produced for each case. The study demonstrates that DAO with tangential fields provides a robust and efficient technique for breast IMRT planning and delivery when the open segment weight is selected between 65% and 80%.

Breast Neoplasms↗
PubMed2005

Three-dimensional structure-from-motion selectivity in the anterior superior temporal polysensory area, STPa, of the behaving monkey.

Human and non-human primates are able to perceive three-dimensional structure from motion displays. Three-dimensional structure-from-motion (object-motion) displays were used to test the hypothesis that neurons in the anterior division of the superior temporal polysensory area (STPa) of monkeys can selectively respond to three-dimensional structure-from-motion. Monkeys performed a reaction time task that required the detection of a change in the fraction of structure in three-dimensional transparent sphere displays. Neurons were able to distinguish structured and unstructured three-dimensional optic flow. These cells could differentiate the change in structure-from-motion at stimulus presentation and when the animal was detecting the amount of structure in the display. Some of these neurons were also tuned for characteristics of the sphere stimuli. Cells were also tested with navigational motion and many were found to respond both to three-dimensional structure-from-motion and navigational motion. These results suggest that STPa neurons represent specific aspects of three-dimensional surface structure and that neurons within STPa contribute to the perception of three-dimensional structure-from-motion.

Animals↗
PubMed2000

The morph server: a standardized system for analyzing and visualizing macromolecular motions in a database framework.

The number of solved structures of macromolecules that have the same fold and thus exhibit some degree of conformational variability is rapidly increasing. It is consequently advantageous to develop a standardized terminology for describing this variability and automated systems for processing protein structures in different conformations. We have developed such a system as a 'front-end' server to our database of macromolecular motions. Our system attempts to describe a protein motion as a rigid-body rotation of a small 'core' relative to a larger one, using a set of hinges. The motion is placed in a standardized coordinate system so that all statistics between any two motions are directly comparable. We find that while this model can accommodate most protein motions, it cannot accommodate all; the degree to which a motion can be accommodated provides an aid in classifying it. Furthermore, we perform an adiabatic mapping (a restrained interpolation) between every two conformations. This gives some indication of the extent of the energetic barriers that need to be surmounted in the motion, and as a by-product results in a 'morph movie'. We make these movies available over the Web to aid in visualization. Many instances of conformational variability occur between proteins with somewhat different sequences. We can accommodate these differences in a rough fashion, generating an 'evolutionary morph'. Users have already submitted hundreds of examples of protein motions to our server, producing a comprehensive set of statistics. So far the statistics show that the median submitted motion has a rotation of approximately 10 degrees and a maximum Calpha displacement of 17 A. Almost all involve at least one large torsion angle change of >140 degrees. The server is accessible at http://bioinfo.mbb.yale. edu/MolMovDB

Computer Graphics↗
PubMed1997

The effects of motion on the performance of pulse oximeters in volunteers (revised publication).

BACKGROUND: Pulse oximetry is considered a standard of care in both the operating room and the postanesthetic care unit, and it is widely used in all critical care settings. Pulse oximeters may fail to provide valid SpO2 data in various situations that produce low signal-to-noise ratio. Motion artifact is a common cause of oximeter failure and loss of accuracy. This study compares the accuracy and data dropout rates of three current pulse oximeters during standardized motion in healthy volunteers. METHODS: Ten healthy volunteers were monitored by three different pulse oximeters: Nellcor N-200, Nellcor N-3000, and Masimo SET (prototype). Sensors were placed on digits 2, 3, and 4 of the test hand, which was strapped to a mechanical motion table. The opposite hand was used as a stationary control and was monitored with the same pulse oximeters and an arterial cannula. Arterial oxygen saturation was varied from 100% to 75% by changing the inspired oxygen concentration. While SpO2 was both constant and changing, the oximeter sensors were connected before and during motion. Oximeter errors and dropout rates were digitally recorded continuously during each experiment. RESULTS: If the oximeter was functioning before motion began, the following are the percentages of time when the instrument displayed an SpO2 value within 7% of control: N-200 = 76%, N-3000 = 87%, and Masimo = 99%. When the oximeter sensor was connected after the beginning of motion, the values were N-200 = 68%, N-3000 = 47%, and Masimo = 97%. If the alarm threshold was chosen SpO2 less than 90%, then the positive predictive values (true alarms/total alarms) are N-200 = 73%, N-3000 = 81%, and Masimo = 100%. In general, N-200 had the greatest SpO2 errors and N-3000 had the highest dropout rates. CONCLUSIONS: The mechanical motions used in this study significantly affected oximeter function, particularly when the sensors were connected during motion, which requires signal acquisition during motion. The error and dropout rate performance of the Masimo was superior to that of the other two instruments during all test conditions. Masimo uses a new paradigm for oximeter signal processing, which appears to represent a significant advance in low signal-to-noise performance.

Adult↗
PubMed1988

Patient motion in thallium-201 myocardial SPECT imaging. An easily identified frequent source of artifactual defect.

Because Tl-201 SPECT requires that patients remain in an awkward position for a prolonged time, patient motion is a potentially serious source of artifactual defects on tomographic reconstructions. Thus, a simple method was developed for detection and correction of motion from SPECT images using a Co-57 point source placed on the lower anterior chest, an area remaining in the camera's field of view throughout imaging. In the absence of motion, this point source inscribes a straight line on planar summation of the 32 projections over 180 degrees. Movement is detected by deviation from this line. The number of pixels of motion is used to shift images so that the resultant images of the point source are linear. The method of motion detection and correction was tested in 48 consecutive patients undergoing Tl-201 SPECT. The corrected and uncorrected images were reconstructed and long and short axis tomographic cuts were quantitatively analyzed using circumferential profiles of maximal counts with comparison to the lower limits of normal. Motion was detected in eight of 48 patients (17%). The amount of motion was 2 pixels in three patients and 1 pixel in five patients. Quantitative defect extent was less after correction in seven of eight patients, with a mean decrease of 71% in patients with 2 pixel motion and 44% in patients with 1 pixel motion. This corresponded with a definite reduction in the size of the tomographic defect by visual analysis, and closer resemblance to quantitatively analyzed planar images performed either before or after tomography in the same patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗