Corrected Phase Values Research Articles

High dynamic range 3D measurement technique based on adaptive fringe projection and curve fitting.

This paper proposes a technique combining an adaptive fringe projection algorithm and a curve fitting algorithm for the three-dimensional (3D) reconstruction of highly reflective objects. First, an adaptive projection algorithm is proposed to avoid image saturation. The phase information obtained by projecting vertical and horizontal fringes is used to establish the pixel coordinate mapping between the camera image and the projected image, and the highlight area in the camera image is found and linearly interpolated. By modifying the mapping coordinates of the highlight area, the optimal light intensity coefficient template of the projection image is calculated, the coefficient template is mapped to the projector image, and it is multiplied by the standard projection fringes to obtain the adaptive projection fringes we need. Secondly, after obtaining the absolute phase map, the phase at the hole is calculated by fitting the correct phase values at both ends of the data hole, and the phase value closest to the actual surface of the object is obtained by performing a fitting in the horizontal and vertical directions. Multiple experimental results show that the algorithm can reconstruct high-quality 3D shapes for highly reflective objects, with high adaptability and reliability in high dynamic range measurements.

Observation on the changes of clinical symptoms, blood and brain copper deposition in Wilson disease patients treated with dimercaptosuccinic acid for 2 years

ObjectiveTo compare the clinical symptoms, brain copper deposition changes of Meso-2,3-dimercaptosuccinic acid (DMSA) and penicillamine therapy in patients with Wilson disease (WD) within 2 years. Methods68 drug-naive patients with WD were enrolled. 10 WD patients treated with zinc gluconate alone were used as the control group. Neurological symptoms were scored using the modified Young Scale. Liver function tests, copper indices and sensitive weighted imaging (SWI) examination were collected. The values of corrected phase (CP) were collected. WD patients were treated with DPA (group 1) or DMSA (group 2) for two years, and followed up every 2 months. ResultsThe ratio of neurological improvement in group 2 was higher than that in group 1 (P = 0.029). Higher rate of neurologic worsening was noticed in patients treated with DPA vs DMSA (P = 0.039). The post-treatment neurological score of DMSA group was lower than that of Zn group (P = 0.037). Hepatic function in 63.3% of patients was stable, while 16.7% was improved, and 20% was deteriorated, after DMSA therapy. Urinary copper levels were lower 1 month (p = 0.032), 4 months (p = 0.041), 12 months (p = 0.037) after initiation of treatment in group 2 than in group 1. At the first year of treatment, the CP values in globus pallidus and substantia nigra in group 2 were higher than those in group 1 (P = 0.034,0.039). At the second year of treatment, the CP values of substantia nigra in group 2 were higher (P = 0.041). Discontinuation was more common in patients on DPA therapy (P = 0 0.032). ConclusionsDMSA could remove metal from brain tissue faster than DPA. DMSA is effective for neurologic symptoms, while the outcome for hepatic symptoms is not entirely satisfactory. DMSA therapy is better tolerated than DPA.

Clinical characteristics of patients with delayed hepatolenticular degeneration

Objective: To evaluate the clinical manifestations, metal metabolism, imaging characteristics and treatment response in patients with delayed Wilson disease (WD). Methods: Patients with untreated WD (40 with delayed onset and 40 with non-delayed onset) were enrolled. Twenty healthy people were included as normal controls. All patients were evaluated with modified Young scale neural symptom scores, grade of Child liver function and mental symptoms rating scale, magnetic resonance imaging (MRI) scan, magnetic sensitive imaging (susceptibility weighted imaging, SWI), metal metabolism. Corrected phase (CP) was measured at SWI. After 2 week treatment, neurologic symptoms, liver function, and metal metabolism were reviewed. Results: The total score of neurological symptoms in WD patients with delayed onset was lower than that of non-delayed onset (13.00±6.87 vs. 21.13±5.53, P=0.033). The scores of SCL-90 and HAMA depression scales in patients with delayed onset were lower than those of non-delayed onset. On T(2) weighted imaging, areas including substantia nigra and thalamus, the caudate nucleus, globus pallidus, putamen presented high signal rate in patients with delated onset than those with non-delayed (P=0.022, 0.037, 0.022, 0.037, 0.029 respectively). The SWI CP values of cangbai sphere and shell nucleus in patients with delayed onset were lower than those with non-delayed onset. Patients with delayed onset had higher urinary copper than those with non-delayed onset before and after treatment (P=0.040, 0.036). After treatment, the score of abnormal tremor and gait in patients with delayed onset was decreased (P=0.037, 0.044), while as the occurrence of neurological symptoms was increased by 10%, and the liver function level in patients with delayed WD was decreased in 3 cases. Conclusions: The brain of WD patients with delayed onset is mainly composed of metal deposits, however the cell damage is not apparent. Clinical symptoms are characterized by significant liver injury, but relatively mild neurological and psychiatric symptoms. Patients with delayed WD have higher urinary copper excretion than those with non-delayed WD. Chelating agents improves the neurological symptoms in patients with delayed onset.

Clinical characteristics of the Wilson disease carrier

Objective: To study the clinical symptoms, copper metabolism and imaging characteristics of Wilson disease (WD) carriers and to explore the treatment strategy of WD carriers. Methods: Forty WD carriers, 40 WD patients and 20 normal controls from the First Affiliated Hospital of Sun Yat-sen University from July 2007 to May 2018 were included. The modified Young scale was used for neural symptom scoring, and Child grading of liver function, mental symptoms rating scale, magnetic resonance imaging (MRI) scan, susceptibility weighted imaging (SWI) inspection, metal metabolism tests were also applied to all the included subjects. Corrected phase (CP) was measured by SWI. WD carriers were divided into symptomatic group and asymptomatic group. Symptomatic WD carriers were treated with penicillamine for 2 weeks and zinc gluconate for 3 months, then their neurological symptoms, liver function grade, metal metabolism index were rechecked. Results: Six WD carriers presented with some clinical symptoms, including 5 with neurological symptoms and 4 with liver dysfunction. The score of Hamilton anxiety (HAMA) scale of symptomatic WD carriers was higher than that of normal control group (P=0.021). 85% of carriers had ceruloplasmin level less than 0.26 g/L. 80% of carriers had serum copper between normal controls and WD patients. The free copper level of WD carriers was lower than that of WD patients (P=0.012, 0.019). Urinary copper in symptomatic WD carriers was higher than normal controls (P=0.047). The CP values of thalamus, globus pallidus and putamen in symptomatic WD carriers were lower than those in normal control group. After treatment with penicillamine in symptomatic WD carriers, urinary copper was higher than that before treatment (P=0.036). After treatment, the liver enzymes of symptomatic WD carriers returned to normal, and the score of modified Young scale was lower than before treatment (P=0.031). Conclusions: Mild copper metabolism abnormality is seen in WD carriers. A few carriers have neurological symptoms such as limb tremors, or liver symptoms such as abnormal liver enzymes. Abnormal copper metabolism is more serious in symptomatic WD carriers than in asymptomatic WD carriers. Symptomatic WD carriers can be treated with zinc gluconate.

Application of high-field magnetic resonance imaging in Parkinson's disease.

The present study aimed to observe the structural changes of the extracorticospinal tract in Parkinson's disease (PD) using susceptibility-weighted imaging (SWI) and diffusion tensor imaging (DTI) magnetic resonance (MR) scans. The association of DTI parameters and brain-iron accumulation with PD was examined and imaging signs useful in the diagnosis of PD were explored. The study included 30 patients with PD and 30 age- and gender-matched healthy controls who underwent routine MR, SWI and DTI scans. The corrected phase (CP) values of the substantia nigra (SN), red nucleus (RN), globus pallidus (GP) and putamen (PUT) were measured, and fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained. Significant differences were found in the CP values between the PD and control groups in the SN, RN and PUT, but there were no differences in other regions of interest (ROIs). The FA values of the SN and PUT in the PD group were significantly decreased compared with those of the control group, but there was no significant difference in the FA values of the GP. Furthermore, there was no significant inter-group difference in the ADC values of any ROIs. In conclusion, SWI is a method useful for evaluating brain-iron deposition in PD. Increasing iron storage levels have previously been shown to be associated with PD pathogenesis but not with the degree of PD severity. FA values may be useful for diagnosing PD, and DTI may offer some insight into PD pathomechanisms and clinical diagnosis.

Characterizing brain mineral deposition in patients with Wilson disease using susceptibility-weighted imaging.

The aim of this study was to evaluate the feasibility of characterizing the brain-mineral deposition in patients with Wilson disease (WD) using susceptibility-weighted imaging (SWI). The study enrolled 30 WD patients and 20 age-matched healthy controls. Neurological symptoms were scored using the modified Young Scale. The hepatic function indices, serum and urinary copper content, and serum iron content were determined. All study objects received the magnetic resonance imaging (MRI) and SWI test of the brain. The values of corrected phase (CP) were calculated on SWI. The relationship between CP values and the clinical status were evaluated. The serum iron content of WD patients was higher than the normal. The CP values of substantia nigra, caudate nucleus, and globus pallidus of WD were lower than the normal values, while the CP value of substantia nigra was the lowest. No correlations were determined between the CP values and the iron and copper parameters. There was negative correlation between the scores of dysarthria and the CP values of the globus pallidus. There was negative correlation between the scores of tremor and the CP values of caudate nucleus. Some regions, which had high signals on T2-weighted image, had low signals on SWI. There might be abnormal iron metabolism in patients with WD. The decreased CP values might reflect a deposition of both copper and iron. SWI may be more sensitive than the ordinary MRI. The mineral deposition may contribute to the neural symptoms.

SWI phase asymmetries in deep gray matter of healthy adults: is there an association with handedness?

To explore the handedness effects on phase asymmetries in deep gray matter of healthy adults by using magnetic susceptibility-weighted imaging (SWI) phase. Thirty left-handed (16 men, 14 women; age range, 20 to 57years) and 30 age- and sex-matched right-handed (16 men, 14 women; age range, 20 to 58years) healthy adults were examined at 3.0T MRI. For each subject, phase values were detected in bilateral frontal white matters (FWM), caudate nucleus (CA), putamen (PU), globus pallidus (GP), thalamus (TH), red nucleus (RN) and substantia nigra (SN) on phase images. Statistical analysis was performed with paired-samples t-test and independent-samples t-test. In both handedness groups, the corrected phase values in the left hemisphere were significantly lower than those in the right one in FWM, CA, PU, GP (P < 0.05) and there was no significant hemispheric asymmetry in TH, RN and SN (P > 0.05). Differences in corrected phase values in corresponding brain regions of the same hemisphere between left-handed and right-handed groups were not statistically significant (P > 0.05). Hemispheric asymmetry of SWI phase in deep gray matter may not associate with handedness in adult brain.

Central nervous system damage due to acute paraquat poisoning: A neuroimaging study with 3.0 T MRI

Paraquat (PQ) is an organic heterocyclic herbicide that is widely used throughout the world. Epidemiological and neuropathological studies have shown that chronic exposure to PQ increases the risk of Parkinson's disease. Patients with acute PQ poisoning show damage to the lungs, liver, and kidneys, and some also show symptoms of central nervous system (CNS) toxicity. However, few studies have focused on the acute neurotoxic changes caused by PQ. Dynamic pathological changes in the human brain cannot be explored in animal models. Thus, to elucidate the impact of acute PQ poisoning on the CNS, neuroimaging studies of poisoned victims, and especially survivors, should be performed. This study reports the first application of magnetic resonance imaging (MRI) techniques on patients with acute PQ poisoning, including survivors. We found significant abnormal signals in the brains of two patients during the acute post-poisoning phase. Using susceptibility weighted imaging (SWI), we documented changes in the corrected phase values for the extrapyramidal ganglia of survivors, and these values correlate with excessive iron deposition. Our diffusion tensor imaging (DTI) results were suggestive of microstructural changes in the extrapyramidal ganglia and hippocampus after PQ poisoning. These neuroimaging results provide an indirect demonstration that acute PQ neurotoxicity exerts a sustained effect during the acute and recovery stages of poisoning.

Quantum calculations for photodetachment cross sections of H− in an inhomogeneous electric field

We calculate the photodetachment cross sections of H− in a gradient electric field based on traditional quantum approach. The system provides a rare example that the formulas for the cross sections can be explicitly derived by both the quantum approach and closed-orbit theory. The quantum results are compared with those of the closed-orbit theory. The correct phase values in the closed-orbit theory are essential and necessary to produce accurate cross sections. Our quantum results remove some previous ambiguities in assigning the phase values in the closed-orbit theory (G. C. Yang and M. L. Du 2007 Phys. Rev. A 75 029904E).

Multi-STFT for adaptive SCPS phase determination

AbstractThis paper presents a fast and reliable approach for phase modulo 2π-calculation from a single fringe pattern. It calculates correct phase values even for very complex and variable shape gradients based on a locally variable fringe period determined for the entire image. In the paper, a new two-step method for wrapped phase calculation is proposed. It is performed through the use of a method based on a multiple local fast Fourier transform for estimation of a local fringes period map and a 5-point spatial carrier phase shifting (SCPS) formula for phase modulo 2π-calculation. The described approach is verified by a correct demodulation of a real fringe pattern taken by a 3D-shape measurement system.

Improvement of Reflectarray Performances at Millimeter Waves by Reduction of the Cell Size

In this paper we discuss the advantages and limitations of reducing the cell size of reflectarrays elements. Reflectarrays have demonstrated their utility at mm-Wave because of their compactness, flexibility and quasi-optical feed that reduces losses. Several applications have been covered such as the automotive cruise control including beam scanning. Most of them use λ/2 cell sizes. We have investigated and compared performances of reflectarrays with 15mm and 50mm diameters using λ/2 and λ/4 cell sizes at 94GHz. Measurements on reduced cell size reflectarrays have demonstrated a loss of 1 dB over 60◦ beam scanning whereas it is of 3 dB for the λ/2 structure in the case of the smaller reflector. Nevertheless, this effect is not demonstrated on the largest one because of the phase compensation range that is limited by the variation in the patch dimensions. The maximum corrected phase values are of 320◦ and 240◦ for λ/2 and λ/4 cells respectively. Furthermore a program based on the ray tracing theory has been developed in order to evaluate the influence of the cell size on the array performances.

Phase-unwrapping algorithm in the presence of discontinuities using a system with crossed grating

A new phase-unwrapping algorithm for the phase map containing discontinuities by the use of a system with crossed grating is described in this paper. A crossed grating is projected onto the object in the usual way, the deformed grating image acquired is Fourier transformed and the frequency spectra for the individual gratings are separated. Using both phase distributions which have different sensitivities, the correct phase values in the presence of discontinuities, especially those caused by the object with height steps, can be obtained. This algorithm is fast and accurate. The results of the measurement of a three-dimensional object with height steps are presented.

Correction of phase wrapping in magnetic resonance imaging.

In phase reconstruction MR imaging, e.g., for velocity measurement, phase shifts beyond +/- pi radians will "wrap around" to smaller apparent phases. Such large phase shifts could arise either due to large background (non-flow-related) phase variations or due to large velocity-induced phase shifts. For sufficiently smooth phase variation, such discontinuities can be automatically recognized and corrected, thus restoring the correct phase values and extending the effective dynamic range of such phase imaging techniques.