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Publication
Journal: ACS Nano
May/14/2012
Abstract
An object is characterized by its amplitude and phase. However, when acquiring optical data about such an object, using a recording medium such as a camera, phase information is lost. Crystallography experienced a breakthrough in phase retrieval for large molecular entities by Max Perutz's introduction of "heavy atoms" using the method of isomorphous replacement. The availability of scanning probe microscopy and its full integration with optical microscopy allows us to apply these X-ray concepts to implement "heavy atom" restoration of phase in optical phase retrieval. In analogy to the heavy atom method, we acquire Fourier intensities in place of an X-ray diffraction pattern, and in place of the heavy atom, we utilize a nanometrically translatable point source of light based on the propagating field of a cantilevered near-field scanning optical microscopic (NSOM) probe controlled by an atomic force microscope (AFM). This integration of NSOM/AFM technology with far-field imaging achieves robust phase retrieval independent of external parameters, leading to 3D optical imaging. The methodology has super-resolution potential, and thus, heavy atom restoration of phase with super-resolution (HARPS) shows the potential of transparently integrated scanning probe microscopy with optical and other imaging modalities such as electron or ion optical imaging.
Publication
Journal: Australian Health Review
February/15/2021
Abstract
ObjectiveThe aim of this study was to explore consumer experiences of care coordination within Barwon Health's Hospital Admission Risk Program (HARP) located in Geelong, Victoria.MethodsThe study design was qualitative description informed by phenomenology and inclusive and co-production methodology. Semi-structured interviews were conducted with a purposive sample of six consumers living with chronic conditions and other complex needs. Participants were asked about their lived experience related to accessing the service, communication, and health and supports before and after accessing the service using an interview guide. Interviews were audio-recorded and transcribed verbatim for thematic analysis.ResultsFive themes were identified: (1) experiencing authentic, values-based care; (2) collaborative care and working together; (3) gaining independence; (4) improved health and quality of life; and (5) limited understanding of HARP at the start. Overall, participants' experiences were positive, which related to improved health, quality of life, and sustainable supports. Although gains were experienced, most of the participants identified that their knowledge of HARP was limited when services commenced, which is an area for service improvement.ConclusionThis research begins to address the knowledge gap related to consumer experiences of care coordination. Findings highlight the importance of providing person-centred, authentic and values-based care, listening authentically, and promoting consumer voice within services. The study demonstrates that inclusive, co-design research is feasible in this service context, and further research is recommended into how stakeholders understand the function of care coordination services to promote health and prevent hospital readmissions, and improve consumer participation.What is known about the topic?Care coordination is multifaceted, with the primary purpose of facilitating person-centred care through appropriate and timely delivery of healthcare services. Despite the effectiveness of care coordination programs in preventing avoidable hospital admissions and reducing hospital length of stay, there is a paucity of research that has investigated consumer perspectives. There is also limited research that has adopted an inclusive research design of knowledge co-production where clinicians and consumers are included as equal members of the research team.What does this paper add?The study findings provide evidence into the value of care coordination from the perspective of consumers living with chronic conditions and other complex health and psychosocial issues. The findings also extend evidence into person- and consumer-centred care through understanding the qualities of care coordination practice that promote authenticity, integrity and positive health outcomes. Listening is identified as a critical element of authentic, values-based care, and as a care coordination intervention. Finally, the study demonstrates that inclusive, co-design research is feasible in this service context, and a larger-scale Experience-Based Co-Design study is recommended to investigate how stakeholders understand the function of care coordination services to promote health and prevent hospital readmissions and improve consumer participation.What are the implications for practitioners?The study informs practitioners of consumer lived experience of care coordination. Practitioners are recommended to apply the findings to practice by adopting an authentic, values-based and person-centred care approach described in the study findings. Service improvement initiatives are recommended to focus on increasing awareness of care coordination services through consumer participation and the meaningful inclusion of consumer voice, which could focus on education for referring health and social care professionals.
Publication
Journal: Journal of the Acoustical Society of America
March/20/2011
Abstract
The way a musical instrument radiates plays an important part in determining the instrument's sound quality. For the concert harp, the soundboard has to radiate the string's vibration over a range of 7 octaves. Despite the effort of instrument makers, this radiation is not uniform throughout this range. In a recent paper, Waltham and Kotlicki [J. Acoust. Soc. Am. 124, 1774-1780 (2008)] proposed an interesting approach for the study of the string-to-string variance based on the relationship between the string attachment position and the operating deflection shapes of the soundboard. Although the soundboard vibrational characteristics determine a large part of the instrument's radiation, it is also important to study directly its radiation to conclude on the origins of the string-to-string variation in the sound production. This is done by computing the equivalent acoustical sources on the soundboard from the far field sound radiation measured around the harp, using the acoustic imaging technique inverse frequency response function. Results show that the radiated sound depends on the correlation between these sources, and the played string's frequency and location. These equivalent sources thus determine the magnitude and directivity of each string's partial in the far field, which have consequences on the spectral balance of the perceived sound for each string.
Publication
Journal: Zootaxa
October/22/2018
Abstract
Although increased survey efforts using improved capture methods (particularly harp traps) have greatly expanded the quantity of Kerivoula specimens available in China, the understanding of the genus has been long constrained. After the recently published revision of the hardwickii-complex with the description of K. furva and re-evaluation of occurrence of K. titania in Taiwan, the critical overview of the previous data of Chinese Kerivoula (with the exception of K. picta, a strikingly colored and unmistakable species) is imperative. To clarify the taxonomy and distribution of the hardwickii-complex in China, 40 additional specimens collected from South China were studied through detailed morphological comparisons, multivariate statistical methods and phylogenetic inference. Our results evidently classified these specimens as K. furva instead of K. titania or K. hardwickii sensu stricto and together with the critical review of literature data indicate that all previous Chinese records of the two latter species were based on either misidentifications or outdated taxonomy. K. furva have so far been recorded in the Chinese provinces of Chongqing, Fujian, Guangdong, Guangxi, Hainan, Hunan, Jiangxi, Yunnan and Taiwan, but more field surveys are needed to confirm whether it could be found in other nearby provinces.
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Publication
Journal: Ontario dentist
March/9/1998
Authors
Publication
Journal: Physical review. E, Statistical, nonlinear, and soft matter physics
December/8/2015
Abstract
We present an analytical treatment of the acoustics of liquid-filled wine glasses, or "glass harps." The solution is generalized such that under certain assumptions it reduces to previous glass harp models, but also leads to a proposed musical instrument, the "inverted glass harp," in which an empty glass is submerged in a liquid-filled basin. The versatility of the solution demonstrates that all glass harps are governed by a family of solutions to Laplace's equation around a vibrating disk. Tonal analyses of recordings for a sample glass are offered as confirmation of the scaling predictions.
Publication
Journal: Respiratory Physiology and Neurobiology
January/3/2016
Abstract
Marine mammals are repeatedly exposed to elevated extra-thoracic pressure and alveolar collapse during diving and readily experience alveolar expansion upon inhalation - a unique capability as compared to terrestrial mammals. How marine mammal lungs overcome the challenges of frequent alveolar collapse and recruitment remains unknown. Recent studies indicate that pinniped lung surfactant has more anti-adhesive components compared to terrestrial mammals, which would aid in alveolar opening. However, pulmonary surfactant composition has not yet been investigated in odontocetes, whose physiology and diving behavior differ from pinnipeds. The aim of this study was to investigate the phosphatidylcholine (PC) composition of lung surfactants from various marine mammals and compare these to a terrestrial mammal. We found an increase in anti-adhesive PC species in harp seal (Pagophilus groenlandicus) and California sea lion (Zalophus californianus) compared to dog (Canus lupus familiaris), as well as an increase in the fluidizing PCs 16:0/14:0 and 16:0/16:1 in pinnipeds compared to odontocetes. The harbor porpoise (a representative of the odontocetes) did not have higher levels of fluidizing PCs compared to dog. Our preliminary results support previous findings that pinnipeds may have adapted unique surfactant compositions that allow them to dive at high pressures for extended periods without adverse effects. Future studies will need to investigate the differences in other surfactant components to fully assess the surfactant composition in odontocetes.
Publication
Journal: Journal of transplantation
December/24/2013
Abstract
During orthotopic liver transplantation (OLT), biliary tract perfusion occurs with hepatic artery reperfusion (HARP), commonly performed after the portal vein reperfusion (PVRP). We examined whether the average time interval between PVRP and HARP impacted on postoperative biliary strictures occurrence. Patients undergoing OLT from 2007 to 2009 were included if they were ≥18 years old, had survived 3 months postoperatively, and had data for PVRP and HARP. Patients receiving allografts from DCD donors were excluded. Patients were followed for 6 months post-OLT. Seventy-five patients met the study inclusion criteria. Of these, 10 patients had a biliary stricture. There was no statistical difference between those with and without biliary stricture in age, gender, etiology, MELD score, graft survival, and time interval between PVRP and HARP. Ninety percent of patients with biliary stricture had a PVRP-HARP time interval >30 minutes, as opposed to 77% of patients without biliary stricture. However, this was not statistically significant. The cold ischemia time was significantly different between the two groups. Time interval for HARP after PVRP did not appear to affect the development of biliary strictures. However, 30 minutes may be suggested as a critical time after which there is an increase in biliary stricture occurrence.
Publication
Journal: Pathologie-biologie
August/5/1999
Abstract
HARP (heparin affin regulatory peptide), also called pleiotrophin (PTN), belongs to the heparin binding growth factors (HBGFs) family. Several new data suggest a role for HARP during the various stages of angiogenesis. In vivo, HARP is localised in endothelial cells of blood capillaries. In vitro, HARP displays mitogenic activity on endothelial cells, induces the formation of capillary-like structures in collagen gel, and degrades extracellular matrix via stimulation of plasminogen activator activity. HARP is also involved in neoangiogenesis during tumor progression. This review discusses the possible role of HARP in tumor angiogenesis and its therapeutic implications.
Publication
Journal: European Journal of Cell Biology
March/27/2008
Abstract
Heparin affin regulatory peptide (HARP) or pleiotrophin seems to be involved in the progression of several tumors of diverse origin. In this study, we tried to determine the role of HARP in rat C6 glioma cells by using an antisense strategy for inhibition of HARP expression. Decrease of the expression of endogenous HARP in C6 cells (AS-C6 cells) significantly increased proliferation, migration, and anchorage-independent growth of cells. Implantation of AS-C6 cells onto chicken embryo chorioallantoic membranes resulted in a significant increase of tumor-induced angiogenesis compared with that induced by non-transfected or C6 cells transfected with the plasmid alone (PC-C6 cells). In the same line, conditioned medium from AS-C6 cells significantly increased endothelial cell proliferation, migration, and tube formation in vitro compared with the effect of conditioned medium from C6 or PC-C6 cells. Interestingly, vascular endothelial growth factor (VEGF) induced C6 cell proliferation and migration, and SU1496, a selective inhibitor of VEGF receptor 2 (VEGFR2), blocked increased glioma cell growth, migration, and angiogenicity observed in AS-C6 cell cultures. The above results seem to be due to a direct interaction between HARP and VEGF in the culture medium of C6 and PC-C6 cells, while AS-C6 cells secreted comparable amounts of VEGF that do not interact with HARP. Collectively, these data suggest that HARP negatively affects diverse biological activities in C6 glioma cells, mainly due to binding of HARP to VEGF, which may sequester secreted VEGF from signalling through VEGFR2.
Publication
Journal: Arkhiv anatomii, gistologii i embriologii
February/13/1991
Abstract
The harp seal adrenal gland studied is alike that of terrestrial mammals, but has some peculiarities. Firstly, this is presence of the fetal cortex in the adrenal gland without any signs of involution and degeneration in adult animals. This phenomenon has been previously described only for the horse adrenal gland. The glomerular zone of the cortex peculiar for the adrenals in the terrestrial mammals in the species studied has the form of arches. This property is also characteristic only to the horse gland. The absence of intermediate and juxtamedullary zones also differs the harp seal adrenal gland from that of terrestrial mammals.
Publication
Journal: Fukushima Journal of Medical Sciences
April/5/1993
Abstract
Eight environmental sounds, i.e., playing the harp, cuckoo's song, sound of the waves, cock's crow, noise of the subway, alarm of a clock, sound of a dentist's drill, scratching of the blackboard, and their temporally reverse sounds were presented for 20 sec to 16 college students in a sound-attenuated chamber. The subjects were requested to estimate the degree of pleasantness-unpleasantness and confidence in identifying each sound 10 sec after presentation. Electroencephalography was recorded at C3, C4, O1 and O2 (International 10-20 system), and the mean EEG powers of delta, theta, alpha-1, alpha-2, beta-1 and beta-2 bands during the sound presentations were computed by a signal processor. The results were as follows: 1) Even when the loudness and frequency component of the sounds were equivalent, there was big difference in pleasantness-unpleasantness estimation among the environmental sounds. 2) Inaccuracy in identifying the sounds presented backwards neutralized the pleasantness-unpleasantness estimation. 3) Powers of theta and low frequency alpha bands were higher during presentation of the pleasant sounds than during presentation of the unpleasant sounds. 4) Alpha activity was more closely related with subjective confidence in sound identification than with pleasantness-unpleasantness estimation of sound. These findings suggest that pleasantness-unpleasantness estimation of environmental sounds depends not only on their loudness level or frequency component but on the accuracy in sound identification and that modification of sound identification may be useful in alleviating the environment noise problem. Alpha activity seems to be closely related to the recognition of sound, but further research is needed on EEG activity in the relationship between the emotional state and sound identification.
Authors
Publication
Journal: Cutis
January/12/2009
Abstract
Musicians may develop skin problems resulting from playing their instruments. Dermatologic conditions in string players usually are secondary to allergic contact dermatitis (allergens include chromium, nickel, colophony, paraphenylenediamine, propolis, and exotic woods) and physical trauma (between either the fingers and the strings or the body and the instrument). A beginner harpist who developed harpist's finger--blister and subsequent callus of her left index finger from repeated trauma between the digit and the harp strings--is described, and string instrument-associated skin problems in musicians are reviewed.
Publication
Journal: Magnetic Resonance in Medicine
November/27/2018
Abstract
OBJECTIVE
To characterize cardiac-driven liver movements using a harmonic phase image representation (HARP) with an optical flow quantification and motion amplification method. The method was applied to define the cardiac trigger delay providing minimal signal losses in liver DWI images.
METHODS
The 16-s breath-hold balanced-SSFP time resolved 20 images/s were acquired at 3T in coronal and sagittal orientations. A peripheral pulse unit signal was recorded. Cardiac-triggered DWI images were acquired after different peripheral pulse unit delays. A steerable pyramid decomposition with multiple orientations and spatial frequencies was applied. The liver motion field-map was derived from temporal variations of the HARP representation filtered around the cardiac frequency. Liver displacements were quantified with an optical flow method; moreover the right liver motion was amplified.
RESULTS
The largest displacements were observed in the left liver (feet-head:3.70 ± 1.06 mm; anterior-posterior: 2.35 ± 0.51 mm). Displacements were statistically significantly weaker in the middle right liver (0.47 ± 0.11 mm; P = 0.0156). The average error was 0.013 ± 0.022 mm (coronal plane) and 0.021 ± 0.041 mm (sagittal plane). The velocity field demonstrated opposing movements of the right liver extremities during the cardiac cycle. DWI signal loss was minimized in regions and instants of smallest amplitude of both velocity and velocity gradient.
CONCLUSIONS
Cardiac-driven liver movements were quantified with combined cardiac frequency-filtered HARP and optical flow methods. A motion phase opposition between right liver extremities was demonstrated. Displacement amplitude and velocity were larger in the left liver especially along the vertical direction. Motion amplification visually emphasized cardiac-driven right liver displacements. The optimal cardiac timing minimizing signal loss in liver DWI images was derived.
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Publication
Journal: Acta Radiologica
November/12/2018
Abstract
BACKGROUND
Increased pulmonary blood flow (PBF) and shear stress may provoke irreversible vascular remodeling, yet invasive visualization of the microvasculature complicates monitoring. A non-invasive imaging methodology would therefore safely provide mechanistic insights into the progression of high PBF-induced vascular remodeling.
OBJECTIVE
To establish a novel microvasculature visualization method using synchrotron radiation pulmonary microangiography (SRPA) that can also calculate PBF velocity in vivo.
METHODS
A high PBF rat model was established by making a fistula between the abdominal aorta and inferior vena cava. After eight weeks, SRPA was performed and the dynamic density changes in the right lower pulmonary artery (PA) were calculated by software. SRPA was performed with a HARP (High-Gain Avalanche Rushing amorphous Photoconductor) receiver. PBF velocity was calculated by contrast medium transit time within the PA. All data were presented as mean ± standard error (SE). Student's t-test was used for comparison between the two groups.
RESULTS
High dynamic spatial and contrast resolution from SRPA in the PA allowed for clear pulmonary microangiography and accurate detection of higher PBF in the rat model (82.3 ± 8.5 mm/s high-PBF group vs. 46.1 ± 4.3 mm/s control group, P < 0.01).
CONCLUSIONS
These novel results demonstrate that SRPA was useful in both visualizing the dynamic flow distribution within the microvasculature and calculating PBF velocity. This newly developed, non-invasive technology may become a powerful tool in clarifying the mechanism of vascular remodeling associated with high PBF-induced shear stress.
Publication
Journal: Journal of Medical Primatology
October/11/2007
Abstract
BACKGROUND
The effectiveness of recorded harp music as a tool for relaxation for non-human primates is explored in this study.
METHODS
Konigsberg Instruments Model T27F-1B cardiovascular telemetry devices were implanted into nine African green monkeys (Chlorocebus aethiops). After post-surgical recovery, animals were exposed to recorded harp music. Telemetry data were collected on heart rate, mean blood pressure, respiratory rate, and body temperature for a 30-minute baseline period before music exposure; a 90-minute period of music exposure; and a 90-minute post-exposure period, where no music was played.
RESULTS
No statistical differences were noted in heart rate, mean blood pressure, respiratory rate, and body temperature between pre-exposure, exposure, and post-exposure periods.
CONCLUSIONS
The lack of response in these African green monkeys may be attributable to their generally calm demeanor in captivity; experiments with a more excitable species such as the rhesus macaque might demonstrate a significant relaxation response to music.
Publication
Journal: Journal of the Acoustical Society of America
May/10/2012
Abstract
The "gothic" style of harp was popular across most of Europe from the late medieval period to the Renaissance. These harps have a one-piece, longitudinally oriented hardwood soundboard, as opposed to the transverse-oriented bonded softwood structure on a modern instrument. In addition, the one-piece back is flexible, whereas the back of a modern instrument is a rigid molded shell. To study the gothic harp, one was constructed from plans created by the Boston Museum of Fine Arts from a late German model in their collection. The vibrational behaviors of the soundboard and soundbox were measured at various stages of construction. The completed instrument was subjected to modal analysis and radiativity measurements. The sound radiation is dominated by two breathing modes at 188 and 273 Hz, each with strong motion of the back, and modes around 350 Hz. Taken together, these modes function like the A0/T1 resonance pairs seen in the soundboxes of other instruments, and a comparison is made with the guitar. Also observed is that as the frequency increases, radiation is emitted from higher up the soundboard, and from higher soundholes. This feature has been observed in other harps, and is a consequence of the harp family's unique geometry.
Publication
Journal: Canadian Journal of Zoology
May/9/1970
Publication
Journal: Data in Brief
May/8/2020
Abstract
This data article is about bats observed from fragmented forest understories interspaced by agricultural plantations, utility corridors, and man-made structures within rural areas of Setiu (Bukit Kesing Forest Reserve and Ladang Tayor TDM) and Hulu Terengganu (Pengkalan Utama and Sungai Buweh, Kenyir) that are situated in Terengganu state, Peninsular Malaysia. Surveys were conducted from October 2018 until January 2019. These bats were captured using harp traps and mist nets that were set 30 m apart across flyways, streams, rivers and less cluttered trees in the 50 m transect zones (identified at each site). All animals captured were distinguished by morphology and released at the same location it was caught. The data comprise of 15 species of bats from four family groups, namely Hipposideridae, Pteropodidae, Rhinolophidae and Vespertilionidae. The data were interpreted into weight-forearm length (W-FA) to inform about bats Body Condition Index (-0.25 to 0.25).
Publication
Journal: Brain, Behavior and Evolution
July/18/2017
Abstract
Histological data from terrestrial, semiaquatic, and fully aquatic mammal vibrissa (whisker) studies indicate that follicle microstructure and innervation vary across the mystacial vibrissal array (i.e. medial microvibrissae to lateral macrovibrissae). However, comparative data are lacking, and current histological studies on pinniped vibrissae only focus on the largest ventrolateral vibrissae. Consequently, we investigated the microstructure, medial-to-lateral innervation, and morphometric trends in harp seal (Pagophilus groenlandicus) vibrissal follicle-sinus complexes (F-SCs). The F-SCs were sectioned either longitudinally or in cross-section and stained with a modified Masson's trichrome stain (microstructure) or Bodian's silver stain (innervation). All F-SCs exhibited a tripartite blood organization system. The dermal capsule thickness, the distribution of major branches of the deep vibrissal nerve, and the hair shaft design were more symmetrical in medial F-SCs, but these features became more asymmetrical as the F-SCs became more lateral. Overall, the mean axon count was 1,221 ± 422.3 axons/F-SC and mean axon counts by column ranged from 550 ± 97.4 axons/F-SC (medially, column 11) to 1,632 ± 173.2 axons/F-SC (laterally, column 2). These values indicate a total of 117,216 axons innervating the entire mystacial vibrissal array. The mean axon count of lateral F-SCs was 1,533 ± 192.9 axons/ F-SC, which is similar to values reported in the literature for other pinniped F-SCs. Our data suggest that conventional studies that only examine the largest ventrolateral vibrissae may overestimate the total innervation by ∼20%. However, our study also accounts for variation in quantification methods and shows that conventional analyses likely only overestimate innervation by ∼10%. The relationship between axon count and cross-sectional F-SC surface area was nonlinear, and axon densities were consistent across the snout. Our data indicate that harp seals exhibit microstructural and innervational differences between their microvibrissae (columns 8-11) and macrovibrissae (columns 1-7). We hypothesize that this feature is conserved among pinnipeds and may result in functional compartmentalization within their mystacial vibrissal arrays.
Publication
Journal: Magnetic Resonance Imaging
November/13/2018
Abstract
Cardiac MRI tagging is a valuable technique for evaluating regional heart function. Currently, there are a number of different techniques for analyzing the tagged images. Specifically, k-space-based analysis techniques showed to be much faster than image-based techniques, where harmonic-phase (HARP) and sine-wave modeling (SinMod) stand as two famous techniques of the former group, which are frequently used in clinical studies. In this study, we compared HARP and SinMod and studied inter-observer variability between the two techniques for evaluating myocardial strain and apical-to-base torsion in numerical phantom, nine healthy controls, and thirty diabetic patients. Based on the ground-truth numerical phantom measurements (strain = -20% and rotation angle = -4.4°), HARP and SinMod resulted in overestimation (in absolute value terms) of strain by 1% and 5% (strain values), and of rotation angle by 0.4° and 2.0°, respectively. For the in-vivo results, global strain and torsion ranges were -10.6% to -35.3% and 1.8°/cm to 12.7°/cm in patients, and -17.8% to -32.7% and 1.8°/cm to 12.3°/cm in volunteers. On average, SinMod overestimated strain measurements by 5.7% and 5.9% (strain values) in the patients and volunteers, respectively, compared to HARP, and overestimated torsion measurements by 2.9°/cm and 2.5°/cm in the patients and volunteers, respectively, compared to HARP. Location-wise, the ranges for basal, mid-ventricular, and apical strain in patients (volunteers) were -8.4% to -31.5% (-11.6% to -33.3%), -6.3% to -37.2% (-17.8% to -33.3%), and -5.2% to -38.4% (-20.0% to -33.2%), respectively. SinMod overestimated strain in the basal, mid-ventricular, and apical slices by 4.7% (5.7%), 5.9% (5.5%), and 8.9% (6.8%), respectively, compared to HARP in the patients (volunteers). Nevertheless, there existed good correlation between the HARP and SinMod measurements. Finally, there were no significant strain or torsion measurement differences between patients and volunteers. There existed good inter-observer agreement, as all measurement differences lied within the Bland-Altman ± 2 standard-deviation (SD) difference limits. In conclusion, despite the consistency of the results by either HARP or SinMod and acceptable agreement of the generated strain and torsion patterns by both techniques, SinMod systematically overestimated the measurements compared to HARP. Under current operating conditions, the measurements from HARP and SinMod cannot be used interchangeably.
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Publication
Journal: International journal of computer assisted radiology and surgery
June/3/2013
Abstract
OBJECTIVE
Cardiac strain calculated from tagged magnetic resonance (MR) images provides clinicians information about abnormalities of heart-wall motion in patients. It is important to develop an accurate method to determine the cardiac strain efficiently. An adaptive windowed harmonic phase (AWHARP) method is proposed for cardiac strain calculation.
METHODS
AWHARP is based on adaptive windowed Fourier transform (AWFT) and 2D Gabor wavelet transform (2D-GWT). The AWFT provides a spatially varying representation of the signal spectra, which allows the harmonic phase (HARP) image to be extracted with high accuracy. Instantaneous spatial frequencies are calculated using 2D-GWT, and the widths of the adaptive windows are then determined according to the instantaneous spatial frequencies for multi-resolution analysis of phase extraction. The proposed method was studied using simulated images and patients' MR images. Both single tagged images (SPAMM) and subtracted tagged images (CSPAMM) were generated using our simulation method, and their results calculated using AWHARP and HARP methods were compared. Normal and pathological tagged MR images were also processed to evaluate the performance of our method.
RESULTS
Our experimental results show that the accuracies of phase and strain images calculated using the AWHARP method are higher than that calculated using the HARP method especially for large tag line deformation. The improvement in accuracies can be up to 3.2 strain (E1) and 17.3 calculation from MR images reveals that the cardiac strain in the end-systolic state is significantly reduced for patients with hypertrophic cardiomyopathy (HCM) compared to that of healthy subjects.
CONCLUSIONS
The proposed AWHARP is an accurate and efficient method for cardiac strain estimation from MR images. This new algorithm can help clinicians to detect left ventricle dysfunctions and myocardial diseases with accurate cardiac strain analysis.
Publication
Journal: Veterinary Pathology
September/7/1994
Publication
Journal: Canadian Journal of Zoology
May/19/1976
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