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At least 469 records · Page 26Linked to original sources
PubMed2005

Concussion in professional football: biomechanics of the striking player--part 8.

OBJECTIVE: Concussive impacts in professional football were simulated in laboratory tests to determine the collision mechanics resulting in injury to the struck player and the biomechanics of the striking players, who were not concussed or neck-injured in the tackle. METHODS: Twenty-seven helmet-to-helmet collisions were reconstructed in laboratory tests using Hybrid III dummies. The head impact velocity, direction, and kinematics matched game video. Translational and rotational head accelerations and six-axis upper neck loads and moments were used to evaluate how the striking player delivered the concussive blow. The neck injury criterion, Nij, was calculated to assess neck injury risks in the striking player. RESULTS: The time-averaged impact force reached 6372 +/- 2486 N at 7.2 milliseconds because of 46.8 +/- 21.7 g head acceleration and 3624 +/- 1729 N neck compression force in the striking player. Fifty-seven percent of the load was contributed by neck compression. The striking players had their heads down and lined up the impact axis through their necks and torsos. This allowed momentum transfer with minimal neck bending and increased the effective mass of the striking player to 1.67 times that of the struck player at peak load. The impact caused 94.3 +/- 27.5 g head acceleration in the concussed players and 67.9 +/- 14.5 g without concussion (t = 2.06, df = 25, P = 0.025). The striking player's Nij was greater than tolerance in 9 of 27 cases by exceeding the 4000 N neck compression limit. For these cases, the average neck compression force was 6631 +/- 977 N (range, 5210-8194 N). Nij was 1.25 +/- 0.16 for eight cases above the tolerance Nij = 1.0. CONCLUSION: In the NFL, striking players line up their heads, necks, and torsos to deliver maximum force to the other player in helmet-to-helmet impacts. The concussive force is from acceleration of the striking player's head and torso load through the neck. Even though neck responses exceeded tolerances, no striking player experienced neck injury or concussion. A head-up stance at impact would reduce the torso inertial load in the collision and the risk of concussion in the struck player.

Biomechanical Phenomena↗
PubMed2003

Electromyographic analysis of abdominal muscle activity using portable abdominal exercise devices and a traditional crunch.

The purpose of this study was to compare the abdominal muscle activity elicited while using 4 portable abdominal training devices vs. a traditional crunch. Thirty-three adults participated in this study. The exercise devices tested included the Ab Roller Plus, Torso Track 2, AB-DOer Pro, and the Perfect Abs. All subjects were tested on the Perfect Abs in both a seated and supine position using low-, medium-, and high-resistance bands. The Torso Track 2 was also tested at low- and high-resistance settings. Surface electromyography (EMG) was recorded from the upper and lower portions of the rectus abdominis, external oblique, and the rectus femoris during each repetition. Statistical analyses were performed on the mean EMG values using a repeated analysis of variance (ANOVA) procedure. There was no significant difference in abdominal muscle activity between the Ab Roller Plus, the Torso Track 2 (high resistance), and a traditional crunch. The mean abdominal muscle activity was significantly lower than a normal crunch, however, when using the AB-DOer, Torso Track (low resistance), and the Perfect Abs seated with the low-resistance band. In contrast, the Perfect Abs, when used in the supine position with the medium- and high-resistance bands, elicited significantly greater mean abdominal muscle activity than a crunch. Of the 4 devices tested, only the Perfect Abs when used in the supine position with the medium- and high-resistance bands, elicited more abdominal activity than a crunch. The results suggest that portable abdominal devices are most effective if they not only mimic the mechanics of a traditional crunch, but also provide external resistance to increase the involvement of the abdominal musculature.

Abdominal Muscles↗
PubMed2001

An analysis of a discrete complex skill using Bernstein's stages of learning.

The purpose of this study was to provide quantitative data about changes in coordination after practicing a racquetball forehand drive serve. Novice women (N = 10) were videotaped before and after 10 min. of practicing a racquetball forehand drive serve on Day 1, and after 10-min. practice sessions on consecutive Days 2 through 5. The PEAK5 Motion Measurement System was used to evaluate the following dependent variables: (a) range of motion of the wrist, elbow, upper torso, and pelvis from backswing to ball contact: (b) racket head velocity at ball contact; and (c) coordination. Coordination was evaluated based on analysis of the angular velocity graphs of each performance to assess sequencing and timing of the segmental contributions. Shared positive contribution was assessed between adjacent 2-segment combinations: pelvis-torso and elbow-wrist. A repeated-measures analysis of variance indicated racket velocity, pelvic rotation, and upper torso rotation significantly increased over the 5 days of practice. Although participants increased their pelvic and torso ranges of motion and racket velocity, improvement in coordination was not documented.

Adult↗
PubMed2003

[The effects of backpack loading on the gait and corresponding compensatory strategy].

This study was designed to determine the effect of backpack loading on the gait pattern and corresponding compensatory strategy, which is important to the balance control of biped robot and military training. Five healthy subjects were instructed to walk at their preferred speed on level pathway taking three different loads i.e. 6 kg, 12 kg and 25 kg, on their backs. The results showed that the gait pattern was apparently influenced, and the dominant effects were found to be the flexion of hip, knee joints and pitch angle of torso. The stride speed decreased apparently with loading on their backs, but the stride length showed less changes. Besides, the responses to taking loads might be influenced by the strength of body. An apparent multi-joints coordination motor mode was employed to compensate the influences of loading, however, their contributions are different; hip, knee joints and torso pitch made dominant contributions to the compensation while ankle joints made minor. The anterior pitch of upper torso could be employed to adjust the overall center of mass while loading on their backs, the larger the magnitude of loading on their backs, the larger the anterior pitch angle of torso. After the heel touched the ground, the flexion of hip and knee joints were effective for the shock absorption, which means that the stiffness of hip and knee joints can be used to absorb the shock and avoid the trauma of each joints.

Adult↗
PubMed2004

Concentration of copper, iron, zinc, cadmium, lead, and nickel in bull and ram semen and relation to the occurrence of pathological spermatozoa.

In this study the concentration of copper, iron, zinc, cadmium, lead, and nickel in bull and ram semen and relation of these metals to spermatozoa morphology was investigated. Analysis by atomic absorption spectrophotometry showed that copper concentration was significantly higher (p<0.0001) in ram semen in comparison with bull semen. The zinc concentration was higher in bull semen in comparison with ram semen. The iron and cadmium concentrations in the semen were similar. Higher concentration of lead was found in ram semen. Higher levels of nickel were found in ram semen in comparison with bulls. In bull semen 11.79+/-4.88% of pathological spermatozoa was found. Higher occurrence of pathological spermatozoa was in ram semen (17.17+/-3.76) in comparison with the semen of bulls. Separated tail, tail torso, and knob twisted tail were the most frequent forms of pathological spermatozoa in both species. Correlation analysis in bulls showed high positive relation between iron and zinc (r = 0.72), nickel and separated tail (r = 0.76), separated tail and tail torso (r = 0.71), tail torso and total number of pathological spermatozoa (r=0.72), and between tail ball and total number of pathological spermatozoa (r = 0.78). In rams high positive correlation between cadmium and lead (r=0.98), nickel and separated tail (r=0.77), separated tail and total number of pathological spermatozoa (r=0.69), knob twisted tail and retention of cytoplasmic drop (r=0.78), and between knob twisted tail and other pathological spermatozoa (r = 0.71) was found. High negative correlation in ram semen was observed between copper and nickel (r=0.71), copper and separated tail (r=0.70), and between iron and tail torso (r=0.67). The results suggest that the studied metals have a direct effect on spermatozoa quality.

Animals↗
PubMed2005

[Isometric muscle strength measurements and assessment: a pilot study].

OBJECTIVE: To determine the anthropometric parameters and the isometric muscle strength in a working population sample in China, and to investigate the relationship between muscle strength and individual attributes, such as age, gender, height and weight. METHODS: The study population consisted of 146 male and 47 female people including workers, administrators and college students. Four types of muscle strength, i.e., handgrip, arm lift, shoulder lift, and torso pull, were measured. RESULTS: Left handgrip, right handgrip, arm lift, shoulder lift and torso pull of male workers were (42.07 +/- 7.20), (43.92 +/- 7.14), (26.79 +/- 4.64), (33.79 +/- 6.88), (88.56 +/- 17.98) kg, respectively while those of female workers were (21.29 +/- 5.09), (23.26 +/- 5.47), (13.29 +/- 3.37), (18.52 +/- 4.01), (41.06 +/- 12.04) kg, respectively. The female's strength was about 50% lower than the male's. The strength in the 40 approximately years old group was higher than that in other age groups. There were significant positive correlation between the gender and the isometric strength as well as between the body weight and the isometric strength. If the body weight served as the corrected parameter, there was no significant difference in the handgrip among the groups (P < 0.05), but the torso pull of male workers > college students > administrators. All relative muscle strengths except the torso pull were similar for all age groups. CONCLUSION: The body weight as the independent variable can be used for establishing the predictive equation of the muscle strength. Calculation of the relative muscle strength can relieve the interference of the body weight for the muscle strength.

Adolescent↗
PubMed1986

Comparative cold responses of men and women to external and internal cold stimuli.

Experiments were conducted comparing the relative contribution of internal and external cold stimuli in the initiation of horripilation (cutis anserina or "goose flesh") in men and women. Five men and five women were compared. Subjects wore a water perfused vest which covered the entire thorax and allowed torso skin temperature to be maintained at either 34 degrees C, 30 degrees C, 26 degrees C, or 22 degrees C in four separate experiments. After stabilization, the subject's legs were immersed in water maintained at 16 degrees C for 20 min. After removing their legs from the water, subjects then pedalled a stationary bicycle ergometer at minimum resistance to facilitate the return of cooled venous blood to the thoracic core. Horripilation was episodic in both men and women but related significantly to torso skin temperature in men and percent body fat in women over the range of torso skin temperatures tested. There was no significant association between horripilation episodes and either the stabilization, immersion, or minimal exercise phase of the experiment. Core body temperature, as measured by rectal and esophageal thermistors, decreased significantly in men from 37.0 degrees C and 36.6 degrees C at 34 degrees C torso skin temperatures, but remained unchanged in women. The results suggest that skin cooling initiates horripilation whose occurrence and pattern are affected by different combinations of morphological or physiological variables in men and women.

Adult↗
PubMed1994

Personal identification from human remains using morphological characteristics and DNA analysis.

This report describes personal identification of four parts of a dismembered human body on the basis of physical characteristics and DNA analysis. A 69-year-old woman suffering from depression went missing from her home in May 1992. Five days after her disappearance, a female torso was found in a river. In a two-week period thereafter, a left forearm, a female head and neck and a right forearm were found consecutively in the same river. Although the end of the cervical vertebra was anatomically identical to that of the torso, the two forearms did not match. However, DNA analyses with a single-locus DNA probe pYNH24, DO alpha typing and a multi-locus DNA probe "Myo", indicated that these four parts came from the same person. The missing woman had undergone lobectomy of the right pulmonary upper lobe, and had suffered from slight scoliosis of the thoracic vertebrae and a second lumbar vertebral compression fracture. These characteristics were also observed in the torso. In order to obtain more conclusive evidence, DNA fingerprinting using DNA extracted from the torso, the missing woman's brother and her daughter was performed using the DNA probes described above. The data obtained indicated that the remains were those of the missing woman.

Aged↗
PubMed1996

Multiple signaling pathways establish both the individuation and the polarity of the oocyte follicle in Drosophila.

The development of the Drosophila oocyte depends upon a sequential series of interactions between the germline cells and the somatically derived follicle cells to produce individual follicles with appropriate polarities. In the germarium the control of germline cell division depends upon a proper interaction with somatic cells adjacent to the germline stem cells. Both gurken and brainiac are required in the germline, and the Egfr, daughterless, Notch, and Delta genes are required in the somatic cells to produce individual egg chambers with a continuous follicular epithelium. After a follicle forms, components in these same signaling pathways, plus additional genes, are then required for the establishment of the anterior-posterior polarity, followed by the dorsal-ventral polarity of the developing follicle. Initially, gurken mRNA is localized to the posterior edge of the oocyte, where it signals the posterior polar follicle cells to differentiate as posterior. The anterior-posterior assymmetry of the oocyte is then established by a reorganization of the microtubule network, which require a Notch-Delta-dependent signal sent from the posterior polar follicle cells to the oocyte and the activity of protein kinase A in the germ line. This reorganization leads to the localization of the maternal anterior-posterior determinants bicoid and oskar to opposite poles of the oocyte and the repositioning of the oocyte nucleus to the anterior-dorsal surface of the oocyte, gurken mRNA and protein are now concentrated between the oocyte nucleus and the adjacent anterior-dorsal follicle cells, where, in combination with Rhomboid, it locally activates the EGF receptor and its downstream cascade to direct the adjoining cells to adopt a dorsal fate. This process is thought to restrict the action of three follicle cell gene functions, encoded by windbeutel, nudal, and, pipe, to the ventral follicle cells, where they lead to the localized activation of a serine protease cascade required to produce the active Spätzle ligand to activate the Toll receptor. Finally, the termini of the embryo are dependent upon the activation of the Torso receptor, and this requires the localized expression of torso-like in a subset of follicle cells at the anterior and posterior poles of the follicle, which leads to the activation of Trunk, the putative ligand for Torso. In summary, the normal development of the oocyte requires a continuous sequence of germline-follicle cell interactions to provide the polarities responsible for normal development.

Animals↗
PubMed1982

Treatment of patients with stages I and II nonmediastinal Hodgkin's disease.

In this study, 95 patients with laparotomy-staged I and II nonmediastinal Hodgkin's disease were treated with involved fields (41 patients), mantle (17), extended fields (26), or involved fields followed by 6 cycles of MOPP (11). Eighty-five patients had upper torso presentations. Seventy had Stage I disease and 25 had stage II. Pathologic findings were nodular sclerosing, 33; mixed cellularity, 41; lymphocyte predominance, 20; and unclassified, one. Five-year overall survivals were excellent regardless of stage, pathologic findings, or treatment: 98% for involved fields or mantle, and 100% for both extended fields and involved fields followed by 6 cycles of MOPP. Corresponding disease-free survivals were 77%, 82%, and 86%, respectively. For patients with upper torso presentations, disease-free figures for the mantle (94%) were better than those for involved fields alone (67%). In addition, regression analysis proved involved fields to be a prognostic factor for a lower disease-free survival. No difference between extended fields or mantle radiotherapy could be detected using this model. Relapses usually occurred in nonirradiated upper torso sites. Only three of the 36 patients treated with involved fields and one of 21 treated with extended fields relapsed in the abdomen alone. Most patients in relapse were salvaged. Rescue treatment was most often radiotherapy and adjuvant combination chemotherapy. Based on this study, the use of mantle radiotherapy is recommended in treating laparotomy-staged I and II patients with nonmediastinal presentations, and the use of extended fields or adjuvant chemotherapy as primary prevention is not recommended.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Miniature-probe measurements of electric fields and currents induced by a 60-Hz magnetic field in rat and human models.

A miniaturized probe was designed and built to provide detailed data on fields induced by a uniform 60-Hz magnetic field in homogeneous models of rat and human. The probe employed three silver wires twisted and potted in an 8-cm hypodermic needle. The exposed tips of the wires formed three sensing electrodes with a centered ground; highly sensitive voltage measurements were enabled by a lock-in amplifier. Tests were conducted in a 1-mT rms field that was uniform within +/- 5%. The models were made by casting 1.5% agar at 1-S/m conductivity into plastic-foam molds. The rat model was scaled 1:1 as an adult (22 cm length; mass about 640 g). The human model was scaled 1:4 as an adult (height = 46.5 cm; mass 1.4 kg). The probe was inserted into each model in several regions, and readings of induced fields were made under different exposure geometries. Maximal strengths of fields induced near the surface of the torso were as high as 120 microV/cm in the laterally exposed rat model. Data extrapolated from the quarter-scale human model revealed that an induced field as high as 700 microV/cm could occur at the torso of a frontally exposed human adult. An overall size-scale factor of about 5 appears to be appropriate for experimental exposures of rats that are intended to simulate currents induced in human beings by magnetic fields. The average strength of electric fields induced in the torso by a 1-mT magnetic field is comparable to that by a vertical electric-field at 60 kV/m and 28 kV/m, respectively, for the rat and human.

Animals↗
PubMed2002

Exercise status and sexual orientation as moderators of body image disturbance and eating disorders in males.

OBJECTIVE: This study evaluated the moderating effects of sexual orientation and exercise status on measures of body image and eating disturbance in a sample of men. METHOD: One hundred and thirty-four men completed measures designed to index a range of body image facets (ideals, actual, partner's preference, overall dissatisfaction), eating disturbance (restrictive and bulimic levels), and overall self-esteem. RESULTS: There were few significant effects as a function of exercise status or sexual orientation. Bodybuilders were more satisfied on a global measure of body image and had a higher ideal and actual upper torso size rating. Gay men had a smaller actual upper torso rating than heterosexual men, but ideal size upper torso did not differ as a function of sexual orientation. DISCUSSION: Findings are discussed in terms of methodological limits of previous work and future examinations of moderating factors for body image and eating disturbance in men.

Analysis of Variance↗
PubMed1985

Estimating radiofrequency power deposition in body NMR imaging.

Simple theoretical estimates of the average, maximum, and spatial variation of the radiofrequency power deposition (specific absorption rate) during hydrogen nuclear magnetic resonance imaging are deduced for homogeneous spheres and for cylinders of biological tissue with a uniformly penetrating linear rf field directed axially and transverse to the cylindrical axis. These are all simple scalar multiples of the expression for the cylinder in an axial field published earlier (Med. Phys. 8, 510 (1981]. Exact solutions for the power deposition in the cylinder with axial (Phys. Med. Biol. 23, 630 (1978] and transversely directed rf field are also presented, and the spatial variation of power deposition in head and body models is examined. In the exact models, the specific absorption rates decrease rapidly and monotonically with decreasing radius despite local increases in rf field amplitude. Conversion factors are provided for calculating the power deposited by Gaussian and sinc-modulated rf pulses used for slice selection in NMR imaging, relative to rectangular profiled pulses. Theoretical estimates are compared with direct measurements of the total power deposited in the bodies of nine adult males by a 63-MHz body-imaging system with transversely directed field, taking account of cable and NMR coil losses. The results for the average power deposition agree within about 20% for the exact model of the cylinder with axial field, when applied to the exposed torso volume enclosed by the rf coil. The average values predicted by the simple spherical and cylindrical models with axial fields, the exact cylindrical model with transverse field, and the simple truncated cylinder model with transverse field were about two to three times that measured, while the simple model consisting of an infinitely long cylinder with transverse field gave results about six times that measured. The surface power deposition measured by observing the incremental power as a function of external torso radius was comparable to the average value. This is consistent with the presence of a variable thickness peripheral adipose layer which does not substantially increase surface power deposition with increasing torso radius. The absence of highly localized intensity artifacts in 63-MHz body images does not suggest anomalously intense power deposition at localized internal sites, although peak power is difficult to measure.

Humans↗
PubMed2005

Focused, eight-element transceive phased array coil for parallel magnetic resonance imaging of the chest--theoretical considerations.

A new transceive system for chest imaging for MRI applications is presented. A focused, eight-element transceive torso phased array coil is designed to investigate transmitting a focused radiofrequency field deep within the torso and to enhance signal homogeneity in the heart region. The system is used in conjunction with the SENSE reconstruction technique to enable focused parallel imaging. A hybrid finite-difference-time-domain/method-of-moments method is used to accurately predict the radiofrequency behavior inside the human torso. The simulation results reported herein demonstrate the feasibility of the design concept, which shows that radiofrequency field focusing with SENSE reconstruction is theoretically achievable.

Algorithms↗
PubMed1993

Body fluid distribution in man in space and effect of lower body negative pressure treatment.

The lack of hydrostatic forces in space eventually produces a fluid deficit within the circulatory system. This deficit may alter the circulatory regulation patterns. The aim of the present study was to determine how much of this fluid deficit is attributable to interstitial fluid losses and to determine the effects of lower body negative pressure (LBNP) treatment on fluid distribution. The body fluid distribution of one subject was assessed before, during, and after weightlessness using two electrical impedance methods: (a) standard quadripole impedance for the segments of upper torso, lower torso, thigh, and calf and (b) an electrical impedance tomography technique (applied potential tomography) for a thigh cross-section. To assess the content of interstitial free fluid a thigh cuff overlying the electrodes for applied potential tomography was inflated to suprasystolic values to ascertain how much fluid can be squeezed out of blood vessels and tissue of skin and muscle. After the first thigh cuff maneuver (CUFF I) the subject performed a cardiovascular stress test with LBNP to mimic the gravity-induced blood shift to the lower part of the body. Then the compression maneuver was repeated (CUFF II). (a) This experimental sequence demonstrated a reduction in interstitial fluid in weightlessness of roughly 40% at the thigh. (b) The CUFF I and LBNP experiment demonstrated a reduced ability to cope with blood pooling in microgravity. (c) The CUFF II experiment suggests that LBNP in microgravity can refill the interstitial spaces and counteract the associated cardiovascular deterioration. The impedance measurements provided estimates of the contribution of different body sections to the observed body weight loss of more than 6 kg. The chest contributed nothing of significance, the lower torso more than 0.5 l, and both calves roughly 1.5 l. The thigh segments of both legs contributed between 1.5 l and 2.0 l with an interstitial free fluid reduction in muscle and skin by 40%.

Adult↗
PubMed1985

Surface integration and least-squares procedures for the inverse recovery of cardiac multipole components.

A simulation study was performed to evaluate different recovery procedures for computing the multipole components of the cardiac electrical activity. A series of dipolar potential distributions was first generated on a realistic numerical model of the human torso. Then, different procedures based on surface integration (SI) and least-squares (LS) minimization were used to compute the multipole components. The parameters of a single moving dipole (SMD) computed from the estimated multipoles were compared with those of the original dipole source. For a finite and homogeneous simulation as well as recovery medium, the results showed that SI employing the potentials over all 1216 surface elements of the torso model was not affected by the various numerical approximations used to perform the integration (e.g., rms error for the SMD position, p = 0.7 mm). By integrating the potentials with truncated capping surfaces at the neck and the waist, the recovery errors increased (p = 2.1 mm). Sampling the potentials at 63 sites, followed by interpolation over the rest of the torso surface, severely affected the SI results for the SMD (p = 6.4 mm), as compared with LS minimization using also 63 values (p = 0.9 mm). With lungs and intraventricular blood masses in the simulation medium but a finite and homogeneous recovery medium, SI was less effective (p = 10.8 mm) than LS (p = 8.6 mm). Adequate compensation for the effects of lungs was obtained by including regions of lower electrical conductivity in the recovery medium for LS, and by a correction matrix for SI. In general, LS gave better results than SI, but with a higher initial computation time.

Electrocardiography↗
PubMed1998

Accuracy of single-dipole inverse solution when localising ventricular pre-excitation sites: simulation study.

Different factors are investigated that may affect the accuracy of an inverse solution that uses a single-dipole equivalent generator, in a standardised inhomogeneous torso model, when localising the pre-excitation sites. An anatomical model of the human ventricular myocardium is used to simulate body surface potential maps (BSPMs) and magnetic field maps (MFMs) for 35 pre-excitation sites positioned on the epicardial surface along the atrioventricular ring. The sites of pre-excitation activity are estimated by the single-dipole method, and the measure for the accuracy of the localisation is the localisation error, defined as the distance between the location of the best-fitting single dipole and the actual site of pre-excitation in the ventricular model. The findings indicate that, when the electrical properties of the volume conductor and lead positions are precisely known and the 'measurement' noise is added to the simulated BSPMs and MFMs, the single-dipole method optimally localises the pre-excitation activity 20 ms after the onset of pre-excitation, within 0.71 +/- 0.28 cm and 0.65 +/- 0.30 cm using BSPMs and MFMs, respectively. When the standard torso model is used to localise the sites of onset of the pre-excitation sequence initiated in four individualised torso models, the maximum errors are as high as 2.6-3.0 cm (even though the average error, for both the BSPM and MFM localisations, remains within the 1.0-1.5 cm range). In spite of these shortcomings, it is thought that single-dipole localisations can be useful for non-invasive pre-interventional planning.

Body Surface Potential Mapping↗
PubMed2002

Correction of nonuniform attenuation and image fusion in SPECT imaging by means of separate X-ray CT.

Improvements in image quality and quantitation measurement, and the addition of detailed anatomical structures are important topics for single-photon emission tomography (SPECT). The goal of this study was to develop a practical system enabling both nonuniform attenuation correction and image fusion of SPECT images by means of high-performance X-ray computed tomography (CT). A SPECT system and a helical X-ray CT system were placed next to each other and linked with Ethernet. To avoid positional differences between the SPECT and X-ray CT studies, identical flat patient tables were used for both scans; body distortion was minimized with laser beams from the upper and lateral directions to detect the position of the skin surface. For the raw projection data of SPECT, a scatter correction was performed with the triple energy window method. Image fusion of the X-ray CT and SPECT images was performed automatically by auto-registration of fiducial markers attached to the skin surface. After registration of the X-ray CT and SPECT images, an X-ray CT-derived attenuation map was created with the calibration curve for 99mTc. The SPECT images were then reconstructed with scatter and attenuation correction by means of a maximum likelihood expectation maximization algorithm. This system was evaluated in torso and cylindlical phantoms and in 4 patients referred for myocardial SPECT imaging with Tc-99m tetrofosmin. In the torso phantom study, the SPECT and X-ray CT images overlapped exactly on the computer display. After scatter and attenuation correction, the artifactual activity reduction in the inferior wall of the myocardium improved. Conversely, the incresed activity around the torso surface and the lungs was reduced. In the abdomen, the liver activity, which was originally uniform, had recovered after scatter and attenuation correction processing. The clinical study also showed good overlapping of cardiac and skin surface outlines on the fused SPECT and X-ray CT images. The effectiveness of the scatter and attenuation correction process was similar to that observed in the phantom study. Because the total time required for computer processing was less than 10 minutes, this method of attenuation correction and image fusion for SPECT images is expected to become popular in clinical practice.

Algorithms↗