Focal Distortion Research Articles

Sensors integration for smartphone navigation: performances and future challenges

Abstract. Nowadays the modern smartphones include several sensors which are usually adopted in geomatic application, as digital camera, GNSS (Global Navigation Satellite System) receivers, inertial platform, RFID and Wi-Fi systems. In this paper the authors would like to testing the performances of internal sensors (Inertial Measurement Unit, IMU) of three modern smartphones (Samsung GalaxyS4, Samsung GalaxyS5 and iPhone4) compared to external mass-market IMU platform in order to verify their accuracy levels, in terms of positioning. Moreover, the Image Based Navigation (IBN) approach is also investigated: this approach can be very useful in hard-urban environment or for indoor positioning, as alternative to GNSS positioning. IBN allows to obtain a sub-metrical accuracy, but a special database of georeferenced images (Image DataBase, IDB) is needed, moreover it is necessary to use dedicated algorithm to resizing the images which are collected by smartphone, in order to share it with the server where is stored the IDB. Moreover, it is necessary to characterize smartphone camera lens in terms of focal length and lens distortions. The authors have developed an innovative method with respect to those available today, which has been tested in a covered area, adopting a special support where all sensors under testing have been installed. Geomatic instrument have been used to define the reference trajectory, with purpose to compare this one, with the path obtained with IBN solution. First results leads to have an horizontal and vertical accuracies better than 60 cm, respect to the reference trajectories. IBN method, sensors, test and result will be described in the paper.

Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles

We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell's equations. Our HF-WEFS implementation is 2-4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens.

Mammographic and clinicopathological features of triple-negative breast cancer

Triple-negative breast cancer (TNBC) lacks effective treatment and has a poor prognosis. This study assessed mammographic findings and clinicopathological features of TNBC by comparing with non-TNBC in order to improve clinical diagnosis of TNBC. A total of 426 patients with pathologically confirmed breast cancer were retrospectively assigned into two groups, TNBC (n = 54) and non-TNBC (n = 372), and then analysed. TNBC frequently showed a high histological grade, presented with a mass (79.6%) and was less frequently associated with focal asymmetric density (11.1%), microcalcifications (5.6%) and distortion (3.7%) on mammography. TNBC mammographic masses were most frequently round/oval (58.1%) or lobular (30.2%) in shape and were less frequently irregular in shape (11.6%). Masses with circumscribed margins were the most frequent (37.2%), with microlobulated (25.6%) and obscured (16.3%) margins being commonly observed, but masses with spiculated margins were rare (9.3%). TNBC could have distinct mammographic and clinicopathological features compared with non-TNBC, and thus mammography may be useful in the diagnosis of TNBC. This study demonstrated distinct mammographic and clinicopathological features to help in diagnosis of Chinese patients with TNBC.

Dynamic control of spatial wavelength dispersion in holographic femtosecond laser processing

Dynamic control of spatial wavelength dispersion is effective due to a potentially large spectral bandwidth of femtosecond pulses, in particular, when using sub-100-fs pulses. We demonstrate spatial wavelength dispersion control, which drastically reduces focal spot distortion in the reconstruction of a hologram, using a pair of spatial light modulators. The improved diffraction spots had nearly diffraction-limited spot sizes, agreeing well with theoretical predictions. The dynamic control of dispersion is also demonstrated in order to restrain unnecessary processing given by the zeroth-order pulse.

Birads 3 Breast Lesions : Can Follow-up Replace Biopsy

Objective: To compare the two years follow-up versus biopsy in probably benign breastlesions (BIRADS3 category) with assessment of the malignancy potential in both conditions. Patients and Methods: This is a comparative descriptive record survey where records of all BIRADS 3 patients (number=575) who were admitted to the Women and Fetal Imaging (WAFI) center in Cairo-Egypt during the period from January 2007 to December 2010 were traced, however, only 464 were finally included and divided into: Group A (number = 395), those who were subjected to follow up protocol and Group B (number = 69), who underwent biopsy. Results: 85.1%of the cases underwent the two years follow up by mammography and ultrasonography through periodic imaging surveillance (group A), while 14.9% underwent biopsy and were allocated as (group B). Among the follow up cases 98.48%weretrue negative (benign cases) and six cases (1.52%) were upgraded in their follow up visits and were confirmed malignant by histopathology. In group (B) 97.1% were true negative while 2 cases (2.9%) were confirmed malignant (false negative).No significant difference between both groups as regards false negative results (p=0.339). When we investigated all false negative cases (cases proved malignant) in both groups, positive family history was the only variable that counts and favoring the malignant suspicion in all cases but other parameters like irregular lesions, subtle asymmetry, calcified masses, focal distortion and parenchymal disruption may direct the radiologists and physicians, to proceed to biopsy. Conclusion: In BIRADS 3 breast lesions interpreted by experienced radiologists and surgeons especially in absence of the parameters favoring malignancy, short term follow up can confidently replace biopsy.

Automatic Registration Method for Fusion of ZY-1-02C Satellite Images

Automatic image registration (AIR) has been widely studied in the fields of medical imaging, computer vision, and remote sensing. In various cases, such as image fusion, high registration accuracy should be achieved to meet application requirements. For satellite images, the large image size and unstable positioning accuracy resulting from the limited manufacturing technology of charge-coupled device, focal plane distortion, and unrecorded spacecraft jitter lead to difficulty in obtaining agreeable corresponding points for registration using only area-based matching or feature-based matching. In this situation, a coarse-to-fine matching strategy integrating two types of algorithms is proven feasible and effective. In this paper, an AIR method for application to the fusion of ZY-1-02C satellite imagery is proposed. First, the images are geometrically corrected. Coarse matching, based on scale invariant feature transform, is performed for the subsampled corrected images, and a rough global estimation is made with the matching results. Harris feature points are then extracted, and the coordinates of the corresponding points are calculated according to the global estimation results. Precise matching is conducted, based on normalized cross correlation and least squares matching. As complex image distortion cannot be precisely estimated, a local estimation using the structure of triangulated irregular network is applied to eliminate the false matches. Finally, image resampling is conducted, based on local affine transformation, to achieve high-precision registration. Experiments with ZY-1-02C datasets demonstrate that the accuracy of the proposed method meets the requirements of fusion application, and its efficiency is also suitable for the commercial operation of the automatic satellite data process system.

Abstract P2-01-06: How much agreement can we expect on BI-RADS mammographic findings? Observer agreement among 10 expert mammographers

Abstract Purpose: To determine the agreement between expert readers on mammographic findings and calcification patterns. Materials and Methods: Ten academic radiologists from 5 centers reviewed 250 de-identified mammographic cases without prior exams which were previously assessed as BI-RADS 4 or 5 with subsequent pathologic diagnosis by percutaneous or surgical biopsy. For benign cases diagnosed by percutaneous biopsy, 1 year of benign or negative imaging follow-up was required. Using standardized forms, each radiologist assessed the presence of any suspicious mammographic findings (microcalcifications, asymmetry (1-vew), focal asymmetry (2-view), architectural distortion), and the morphology (none, round/punctate, amorphous, coarse heterogeneous, fine pleomorphic, fine linear branching) and distribution (none, diffuse, regional, grouped, linear, segmental) of any identified microcalcifications. Agreement between radiologists for presence/absence of findings, morphology, and distribution of calcifications was determined by calculating the Kappa (k) coefficient with 95% confidence interval (95% CI). The kappa coefficient proposed strength of agreement is ≤0 = poor, .01-.20 = slight, .21-.40 = fair, .41-.60 = moderate, .61-.80 = substantial, and .81-1 = almost perfect, as established by Landis and Koch.1 Results: Of the 250 lesions, 156 (62%) were benign and 94 (38%) malignant. Agreement among the 10 expert readers was strongest for recognizing the presence/absence of calcifications (k = 0.82, 95% CI: 0.80-84), “almost perfect”). There was substantial agreement among the readers for the identification of a mass (k = 0.67, 95% CI: 0.66-69), whereas agreement was fair for the presence of a focal (2-view) asymmetry (k = 0.21, 95% CI: 0.1900.23) or architectural distortion (k = 0.28, 95%CI: 0.26-0.30). Agreement for asymmetries (1-view) was slight (k = 0.09, 95%CI: 0.08-0.11). Among the 6 categories of microcalcification distribution and morphology, reader agreement was moderate (distribution k = 0.60, 95%CI:0.59-0.61; morphology k = 0.51, 95%CI: 0.50-0.52). Conclusion: When asked to characterize suspicious mammographic findings, this sampling of 10 expert academic breast imagers across 5 centers revealed varying strength of agreement for different findings, ranging from slight to almost perfect. Strongest agreement (“almost perfect”) was found for identifying the presence or absence of microcalcifications, although agreement drops to moderate when readers are asked to specify microcalcification morphology and distribution. 1 Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics.1977;33:159-174. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-01-06.

Keeping a Pan-Tilt-Zoom Camera Calibrated

Pan-tilt-zoom (PTZ) cameras are pervasive in modern surveillance systems. However, we demonstrate that the (pan, tilt) coordinates reported by PTZ cameras become inaccurate after many hours of operation, endangering tracking and 3D localization algorithms that rely on the accuracy of such values. To solve this problem, we propose a complete model for a PTZ camera that explicitly reflects how focal length and lens distortion vary as a function of zoom scale. We show how the parameters of this model can be quickly and accurately estimated using a series of simple initialization steps followed by a nonlinear optimization. Our method requires only 10 images to achieve accurate calibration results. Next, we show how the calibration parameters can be maintained using a one-shot dynamic correction process; this ensures that the camera returns the same field of view every time the user requests a given (pan, tilt, zoom), even after hundreds of hours of operation. The dynamic calibration algorithm is based on matching the current image against a stored feature library created at the time the PTZ camera is mounted. We evaluate the calibration and dynamic correction algorithms on both experimental and real-world datasets, demonstrating the effectiveness of the techniques.

Improvements to MISR stereo motion vectors

[1] This study evaluated the effects of recent major modifications to the Multiangle Imaging SpectroRadiometer (MISR) wind retrieval algorithm by repeating an earlier yearlong comparison with Meteosat-9 cloud motion vectors. Algorithm upgrades included an area-based stereo matcher, enhanced quality control, georegistration corrections to focal plane distortions, and increased retrieval resolution. The new winds had better quality at all levels, yielding a particularly large increase in coverage at middle and high levels. The upgrades had an overall neutral impact on the E-W wind comparison statistics, which were already quite good in the preceding MISR data set. The comparison statistics for the more error-prone N-S wind, however, improved significantly on all scales—global, zonal, and regional—and throughout the entire atmosphere. Both the negative N-S wind bias and root mean square difference decreased, and correlation increased substantially, with middle and high levels, and tropics and subtropics experiencing the largest improvements. Subpixel georegistration corrections reduced cross-swath variations in N-S wind and height by half. As the net effect of these improvements, the error characteristics of the previously more uncertain N-S wind component became comparable to those of the E-W wind component at low and middle levels. Despite the substantial reductions in N-S wind errors, which are highly correlated with stereo height errors, the MISR – Meteosat-9 height comparison did not generally improve, strongly suggesting Meteosat-9 height assignment errors as the primary driver of discrepancy.

Simultaneous spatial and temporal focusing for tissue ablation

Simultaneous spatial temporal focusing (SSTF) is used to deliver microjoule femtosecond pulses with low numerical aperture geometries (<0.05 NA) with characteristics that are significantly improved compared to standard focusing paradigms. Nonlinear effects that would normally result in focal plane shifts and focal spot distortion are mitigated when SSTF is employed. As a result, it is shown that SSTF will enable surgical implementations that are presently inhibited.

Automatic Camera Calibration in Close Range Photogrammetry

Automatic camera calibration via self-calibration with the aid of coded targets is now very much the norm in closerange photogrammetry. This is irrespective of whether the cameras to be calibrated are high-end metric, or the digital SLRs and consumer-grade models that are increasingly being employed for image-based 3D measurement. Automation has greatly simplified the calibration task, but there are real prospects that important camera calibration issues may be overlooked in what has become an almost black-box operation. This paper discusses the impact of a number of such issues, some of which relate to the functional model adopted for self-calibration, and others to practical aspects which need to be taken into account when pursuing optimal calibration accuracy and integrity. Issues discussed include interior orientation stability, calibration reliability, focal plane distortion, image point distribution, variation in lens distortion with image scale, colour imagery and chromatic aberration, and whether 3D object space control is warranted. By appreciating and accounting for these issues, users of automatic camera calibration will enhance the prospect of achieving an optimal recovery of scene-independent camera calibration parameters.

Pyloric gland adenoma of the cystic duct with malignant transformation: report of a case with a review of the literature

BackgroundPyloric gland adenoma consists of closely packed pyloric-type glands lined by mucus-secreting cells. To date, approximately 230 cases have been reported, mostly of gastric localization with a tumour size up to 3.5 cm and a mean age of occurrence around 70 years. Adenocarcinoma develops in about 40% of cases and may be difficult to detect due to relatively mild nuclear atypia.Case presentationWe present the first case of a pyloric gland adenoma of the cystic duct in a 62-year-old male patient and demonstrate the clinicopathologic characteristics, including radiographic, molecular, and cytogenetic findings. The 2 cm-tumour developed in the cystic duct and protruded into the hepatic and common bile duct. On microscopic examination, it displayed closely packed pyloric-type glands, and focal architectural distortion with mild nuclear atypia. Immunohistochemically, it expressed MUC1, MUC5AC, MUC6 and p53, but not MUC2 and CD10. The Ki67-proliferation index was 25%. Furthermore, high-grade intraepithelial neoplasia was observed in the surrounding bile duct. We detected chromosomal gains at 7p, 7q11q21, 15q, 16p, 20, losses at 6p23pter, 6q, 18, and amplifications at 1q and 6p21p22 in the pyloric gland adenoma by comparative genomic hybridization. A KRAS codon 12 mutation (c.35G>T; p.G12V) was detected in the pyloric gland adenoma and in the adjacent dysplasia by sequencing analysis. The diagnosis of pyloric gland adenoma was established with transition into well-differentiated adenocarcinoma and high-grade biliary intraepithelial neoplasia.ConclusionPyloric gland adenoma evolving in the cystic duct is a rare differential diagnosis of obstructive bile duct tumours. Other premalignant bile duct lesions may be associated. Due to the risk of developing adenocarcinoma, surgical resection should be performed.

Pointers and pitfalls of mycophenolate-associated colitis

AimsMycophenolate-associated colitis has been previously reported to show patterns of colonic mucosal injury mimicking a host of conditions, including graft-versus-host disease, ischaemia and inflammatory bowel disease (IBD). The aim of...

The design of a focused ultrasound transducer array for the treatment of stroke: a simulation study

High intensity focused ultrasound (HIFU) is capable of mechanically disintegrating blood clots at high pressures. Safe thrombolysis may require frequencies higher than those currently utilized by transcranial HIFU. Since the attenuation and focal distortion of ultrasound in bone increases at higher frequencies, resulting focal pressures are diminished. This study investigated the feasibility of using transcranial HIFU for the non-invasive treatment of ischemic stroke. The use of large aperture, 1.1–1.5 MHz phased arrays in targeting four clinically relevant vessel locations was simulated. Resulting focal sizes decreased with frequency, producing a maximum –3 dB depth of field and lateral width of 2.0 and 1.2 mm, respectively. Mean focal gains above an order of magnitude were observed in three of four targets and transducer intensities required to achieve thrombolysis were determined. Required transducer element counts are about an order of magnitude higher than what currently exists and so, although technically feasible, new arrays would need to be developed to realize this as a treatment modality for stroke.

지상기준점을 이용한 비측량용 카메라 렌즈 캘리브레이션

최근 비약적인 기술발전을 통해 8,000만 화소급 디지털 카메라가 등장했으며, 비측량용 디지털 카메라가 사진 측량 분야에서 다양하게 활용되고 있다. 본 연구에서는 항공사진과 지상기준점을 이용하여 렌즈 캘리브레이션을 수행하였다. 항공사진은 35mm 렌즈가 장착된 CMOS 2,110만 화소급 비측량용 디지털 카메라를 헬리콥터에 설치하여 취득하였고, 지상기준점은 1:1,000 도화원도에서 선점하였다. 그 결과 렌즈에 대한 초점거리, PPA, 방사왜곡계수를 계산할 수 있었다. 또한 렌즈 캘리브레이션 전후에 항공삼각측량을 수행하여 지상기준점의 평균제곱근오차와 최대 잔차를 비교하였으며, 캘리브레이션 후 정확도가 매우 큰 폭으로 향상됨을 알 수 있었다. The most recent, 80 mega pixels digital camera appeared through the development of digital technology, and nonmetric digital cameras have been using in various field of photogrammetry. In this study, we experimented lens calibration using aerial photographs and ground control points. The aerial photographs were taken a non-metric digital camera which is CMOS(Complementary Metal Oxide Semiconductor) 21.1 mega pixels sensor and 35mm lens at a helicopter. And the ground control points were selected on the 1:1,000 plotting origin data. As a result, we calculated focal length, PPA(Principal Point of Autocollimation) and symmetric radial distortion coefficients from the lens. Also, RMSE(root mean square error) and maximum residual of the ground control points from the aerial triangulation were compared before and after calibration. And we found that the accuracy of the after calibration was improved very significantly.

Treatment of Paget's Disease of Bone

Paget's disease of bone is the paradigm of bone focal distortion with accelerated bone turnover. Over the years, a number of different drugs have been used to control its activity but, since bisphosphonates were introduced for the treatment of the disease, they have become the preferred treatment. This review will update the therapeutic indications, available drugs and therapeutic response monitoring.

Early Formative Stage of Human Focal Cortical Gyration Anomalies: Fetal MRI

Limited information is available about the development of focal cortical gyration anomalies in the human brain. Using prenatal MRI, we characterized focal cortical gyration anomalies at an early formative stage and sought clues about the mechanisms of their development. From a large prenatal MRI database, 30 cases (gestational age, ≤ 24 weeks) with reported focal distortion of the cortical rim profile were selected. Eight cases were matched with histologic examinations; another seven had prenatal MRI, MRI autopsy, or postnatal MRI follow-up; and 15 had no follow-up but did present analogous abnormal cortical features. Focal cortical gyration anomalies were detectable when the brain was still smooth (i.e., physiological lissencephaly). Four patterns of cortical plate anomaly were identified: wartlike (11 cases), abnormal invaginating sulcus (11 cases), sawtooth (six cases), and single or multiple bumps (two cases). A thinned or blurred subplate and intermediate zone in the focal cortical gyration anomaly site was detected in 80% of cases. All but two cases had other intracranial anomalies. Seven cases were classified as hypoxic-ischemic, five as genetic, and three as infective. In 15 cases, the cause could not be established. In five fetuses with further intrauterine or postnatal MRI, focal cortical gyration anomalies increased in complexity, fulfilling postnatal imaging criteria of polymicrogyria. Focal cortical gyration anomalies can be detected at the early sulcation process stage. The process leading to abnormal gyration may evolve faster than physiologic ones and seems to be related to alterations of parenchymal layering occurring before 24 weeks' gestation. Most focal cortical gyration anomalies evolve toward what is currently considered polymicrogyria.

Tratamiento de la enfermedad ósea de Paget

Paget's disease of bone is the paradigm of bone focal distortion with accelerated bone turnover. Over the years, a number of different drugs have been used to control its activity but, since biphosphonates were introduced for the treatment of the disease, they have become the preferred treatment. This review will update the therapeutic indications, available drugs and therapeutic response monitoring.

A Comparison Between Two Imaging Techniques for the Diagnosis of Subacute Thyroiditis (De Quervain Thyroiditis)

Subacute thyroiditis (SAT) or de Quervain thyroiditis is a relatively frequent and self-limited condition with a triphasic clinical course. Its symptoms can mimic other thyroid, upper respiratory, and ear infections. Thyroid ultrasonography (TUS), radioactive iodine uptake (RAIU), and thyroid scintigraphy (TS) may be used for differential diagnosis. To assess and compare the diagnostic value of thyroid TUS and TS in patients on the first phase of a clinically diagnosed SAT. Twenty-two patients (18 women and 4 men, age, 37.2 ± 9.83 years) with clinical diagnosis of SAT were prospectively studied. Thyroid stimulating hormone, T3, free T4, antithyroperoxidase antibodies, thyroglobulin, polymerase chain reaction, complete blood count and differential, TUS, TS, and RAIU at 2 and 24 hours were performed. All patients were on thyrotoxic phase with a thyroid stimulating hormone mean of 0.03 ± 0.030 mU/L (range: 0.005-0.13); antithyroperoxidase antibodies were positive in 3 patients (≥75 UI/mL); thyroglobulin was elevated in 16 patients (≥55 ng/mL). RAIU at 2 hours was 1.94% ± 0.85% (range: 1%-4%), and at 24 hours, 0.98% ± 1.24% (range: 0.10%-5%). TS showed low uptake in all patients. On TUS, only 8 patients were compatible with SAT. In 13 patients, TUS was consistent with goiter, diffuse type in 8, multinodular in 5, and normal in 1 patient. Low thyroid scan uptake with I-131 at 2 hours (<4%) and 24 hours (<5%), and poor thyroid visualization on TS seem to be more prevalent than focal distortion and heterogeneity in TUS in thyrotoxic phase of SAT.

Parallel direct laser writing in three dimensions with spatially dependent aberration correction

We propose a hologram design process which aims at reducing aberrations in parallel three-dimensional direct laser writing applications. One principle of the approach is to minimise the diffractive power of holograms while retaining the degree of parallelisation. This reduces focal distortion caused by chromatic aberration. We address associated problems such as the zero diffraction order and aberrations induced by a potential refractive index mismatch between the immersion medium of the microscope objective and the fabrication substrate. Results from fabrication in diamond, fused silica and lithium niobate are presented.