Artifact Image Research Articles

전산화단층영상장비에서 패각을 이용한 방사선 융합차폐체의 표면 방사선량 감소율과 방사선 인공물 영상 평가

전산화단층영상장비에서 패각을 이용한 방사선 융합차폐체의 표면 방사선량 감소율과 방사선 인공물 영상 평가

Subjective and objective image differences in pediatric computed tomography cardiac angiography using lower iodine concentration.

Several recent studies showed the optimal contrast enhancement with a low-concentration and iso-osmolar contrast media in both adult and pediatric patients. However, low contrast media concentrations are not routinely used due to concerns of suboptimal enhancement of cardiac structures and small vessels. To evaluate the feasibility of using iso-osmolar contrast media containing a low iodine dose for CT cardiac angiography at 80kilovolts (kVp) in neonates and infants. The iodixanol 270 group consisted of 79 CT scans and the iopromide 370 group of 62 CT scans in patients ≤1year old. Objective measurement of the contrast enhancement was analyzed and contrast-to-noise ratios of the ascending aorta and left ventricle were calculated. Regarding subjective measurement, a four-point scale system was devised to evaluate degrees of contrast enhancement, image noise, motion artifact and overall image quality of each image set. Reader performance for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment was evaluated. Group objective and subjective measurements were nonsignificantly different. Overall sensitivity, specificity and diagnostic accuracy for correctly differentiating iodixanol 270 and iopromide 370 by visual assessment were 42.8%, 59%, and 50%, respectively. The application of iodixanol 270 achieved optimal enhancement for performing pediatric cardiac CT angiography at 80kVp in neonates and infants. Objective measurements of contrast enhancement and subjective image quality assessments were not statistically different in the iodixanol 270 and iopromide 370 groups.

Respiratory motion artifacts during arterial phase imaging with gadoxetic acid: Can the injection protocol minimize this drawback?

To determine which of three gadoxetic acid injection techniques best reduced the contrast-related arterial-phase motion artifacts. This Institutional Review Board (IRB)-approved, retrospective study included a cohort of 78 consecutive patients who each had serial gadoxetic acid-enhanced 3.0T magnetic resonance imaging (MRI) of the liver (0.025 mmol/kg body weight) performed with at least two of three injection techniques: M1 test bolus, undiluted, power-injected 1 mL/s; M2 test bolus, diluted 50% with saline, power-injected 1 mL/s; M3 fixed delay, undiluted, manually injected. Blinded to the injection method, three readers independently rated the randomized images for arterial-phase motion artifacts, arterial-phase timing, and arterial-phase lesion visibility using a four-point Likert scale. Regarding respiratory artifacts, gadoxetic acid arterial-phase images were judged better with M3 (2.7 ± 0.7) and were significantly less than those with M1 (2.1 ± 1.1) (P = 0.0001). Arterial-phase M2 (2.50 ± 0.89) images were rated significantly better than arterial-phase M1 images (P = 0.012), but the difference between arterial-phase images with M3 and M2 scores was not statistically significant (P = 0.49). Arterial-phase timing was significantly better for M1 compared to M3, and for M2 compared to M3 (P < 0.0001 for both). The area under the curve was 0.59-0.68. However, there was no significant difference between M1 and M2 (P = 0.35). With regard to arterial-phase lesion visibility, there was no significant difference in the ratings between any of the three injection techniques (P = 0.29-0.72). Interreader agreement was moderate to substantial (κ = 0.41-0.62). A diluted, power-injected protocol (M2) seems to provide good timing and minimize artifacts compared with two other injection methods. No significant difference was found in lesion visibility between these three methods. 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1107-1114.

Full and hybrid iterative reconstruction to reduce artifacts in abdominal CT for patients scanned without arm elevation.

Background Abdominal computed tomography (CT) without arm elevation is associated with degraded image quality due to streak artifacts. Purpose To compare the degree of streak artifacts in abdominal CT images without arm elevation between full iterative reconstruction (IR), hybrid IR, and filtered back projection (FBP) using two commercially available scanners. Material and Methods First, a phantom study simulating CT examination without arm elevation was performed. Second, unenhanced axial images of 33 patients (17 and 16 patients for each vendor) who underwent CT without arm elevation were reconstructed with full IR, hybrid IR and FBP. A radiologist placed 50 parallel lines with lengths of 50 pixels vertical to the streaks and quantitatively evaluated the images for streak artifacts in the phantom study. Two radiologists evaluated the images of patients for streak artifacts (on the liver and the kidney) and diagnostic acceptability using a four-point scale. Results The phantom study indicated that full IR algorithms were more effective than FBP in reducing streak artifacts. In the clinical patient study, streak artifacts were significantly more reduced with full IR compared with FBP in both the liver and kidney ( P < 0.012). Streak artifact reduction was limited with hybrid IR. Model-based iterative reconstruction (MBIR) (one of the full IR algorithms) provided diagnostically more acceptable image quality ( P < 0.016) compared with FBP. Conclusion In abdominal CT without arm elevation, full IR enabled a more efficient streak artifact reduction compared with FBP and MBIR was associated with diagnostically more acceptable images.

Improving Archaeologists’ Online Archive Experiences Through User-Centred Design

Traditionally, the preservation of archaeological data has been limited by the cost of materials and the physical space required to store them, but for the last 20 years, increasing amounts of digital data have been generated and stored online. New techniques in digital photography and document scanning have dramatically increased the amount of data that can be retained in digital format, while at the same time reducing the physical cost of production and storage. Vast numbers of hand written notes, grey literature documents, images of assemblages, contexts, and artefacts have been made available online. However, accessing these repositories is not always straightforward. Superficial interaction design, sparsely populated metadata, and heterogeneous schemas may prevent users from working the data that they need within archaeological archives.In this article, we present the work of the Digging into Archaeological Data and Image Search Metadata project (DADAISM), a multidisciplinary project that draws together the work of researchers from the fields of archaeology, interaction design, image processing and text mining to create an interactive system that supports archaeologists in their tasks in online archives. By adopting a user-centred approach with techniques grounded in contextual design, we identified the phases of archaeologists work in online archives, which are distinctive to this user group. The insights from this work drove the design and evaluation of an interactive system that successfully integrates content-based image based retrieval and improved metadata searching to deliver a positive user experience when working with online archives.

The effects of metal artifact reduction on the retrieval ofattenuation values.

BackgroundThe quality of CT slices can be drastically reduced in the presence of high‐density objects such as metal implants within the patients’ body due to the occurrence of streaking artifacts. Consequently, a delineation of anatomical structures might not be possible, which strongly influences clinical examination.PurposeThe aim of the study is to clinically evaluate the retrieval of attenuation values and structures by the recently proposed Augmented Likelihood Image Reconstruction (ALIR) and linear interpolation in the presence of metal artifacts.Material and MethodsA commercially available phantom was equipped with two steel inserts. At a position between the metal rods, which shows severe streaking artifacts, different human tissue‐equivalent inserts are alternately mounted. Using a single‐source computer tomograph, raw data with and without metal rods are acquired for each insert. Images are reconstructed using the ALIR algorithm and a filtered back projection with and without linear interpolation. Mean and standard deviation are compared for a region of interest in the ALIR reconstructions, linear interpolation results, uncorrected images with metal rods, and the images without metal rods, which are used as a reference. Furthermore, the reconstructed shape of the inserts is analyzed by comparing different profiles of the image.ResultsThe measured mean and standard deviation values show that for all tissue classes, the metal artifacts could be reduced using the ALIR algorithm and the linear interpolation. Furthermore, the HU values for the different classes could be retrieved with errors below the standard deviation in the reference image. An evaluation of the shape of the inserts shows that the reconstructed object fits the shape of the insert accurately after metal artifact correction. Moreover, the evaluation shows a drop in the standard deviation for the ALIR reconstructed images compared to the reference images while reducing artifacts and keeping the shape of the inserts, which indicates a noise reduction ability of the ALIR algorithm.ConclusionHU values, which are distorted by metal artifacts, can be retrieved accurately with the ALIR algorithm and the linear interpolation approach. After metal artifact correction, structures, which are not perceptible in the original images due to streaking artifacts, are reconstructed correctly within the image using the ALIR algorithm. Furthermore, the ALIR produced images with a reduced noise level compared to reference images and artifact images. Linear interpolation results in a distortion of the investigated shapes and features remaining streaking artifacts.

O-space with high resolution readouts outperforms radial imaging

PurposeWhile O-Space imaging is well known to accelerate image acquisition beyond traditional Cartesian sampling, its advantages compared to undersampled radial imaging, the linear trajectory most akin to O-Space imaging, have not been detailed. In addition, previous studies have focused on ultrafast imaging with very high acceleration factors and relatively low resolution. The purpose of this work is to directly compare O-Space and radial imaging in their potential to deliver highly undersampled images of high resolution and minimal artifacts, as needed for diagnostic applications. We report that the greatest advantages to O-Space imaging are observed with extended data acquisition readouts. Theory and methodsA sampling strategy that uses high resolution readouts is presented and applied to compare the potential of radial and O-Space sequences to generate high resolution images at high undersampling factors. Simulations and phantom studies were performed to investigate whether use of extended readout windows in O-Space imaging would increase k-space sampling and improve image quality, compared to radial imaging. ResultsExperimental O-Space images acquired with high resolution readouts show fewer artifacts and greater sharpness than radial imaging with equivalent scan parameters. Radial images taken with longer readouts show stronger undersampling artifacts, which can cause small or subtle image features to disappear. These features are preserved in a comparable O-Space image. ConclusionsHigh resolution O-Space imaging yields highly undersampled images of high resolution and minimal artifacts. The additional nonlinear gradient field improves image quality beyond conventional radial imaging.

Comparison of contrast media for visualization of the colon of healthy dogs during computed tomography and ultrasonography

OBJECTIVE To evaluate contrast agents for their ability to improve visualization of the colon wall and lumen during CT and ultrasonography. ANIMALS 10 healthy adult Beagles. PROCEDURES Food was withheld from dogs for 36 hours, after which dogs consumed 250 mL of polyethylene glycol solution. Dogs were then anesthetized, a contrast agent (tap water, diluted barium, or air; order randomly assigned) was administered rectally, iodine contrast medium (880 mg of I/kg) was administered IV, and CT and ultrasonography of the colon were performed. After a 1-week washout period, this process was repeated with a different contrast agent until all agents had been evaluated. Two investigators reviewed the CT and ultrasonographic images for colon wall thickness, conspicuity, artifacts, wall layering, and degree of lumen dilation at 4 sites. RESULTS Thickness of the colon wall was greatest in CT and ultrasonographic images with water used as contrast agent, followed by barium and then air. The CT images obtained after water administration had a smooth appearance that outlined the colonic mucosa and had the highest score of the 3 contrast agents for wall conspicuity. Although no substantial artifacts related to any of the contrast agents were identified on CT images, barium- and gas-induced shadowing and reverberation artifacts hindered wall evaluation during ultrasonography. For ultrasonography, the degree of conspicuity was highest with barium in the near-field wall and with water in the far-field wall. In contrast to CT, ultrasonography could be used to distinguish wall layering, and the mucosal and muscular layers were distinct with all contrast agents. CONCLUSIONS AND CLINICAL RELEVANCE Use of water as a contrast agent for both CT and ultrasonography of the colon in dogs compensated for each imaging modality's disadvantages and could be beneficial in the diagnosis of colon disease.

The Detection of Focal Liver Lesions Using Abdominal CT: A Comparison of Image Quality Between Adaptive Statistical Iterative Reconstruction V and Adaptive Statistical Iterative Reconstruction

To investigate image quality characteristics of abdominal computed tomography (CT) scans reconstructed with adaptive statistical iterative reconstruction V (ASIR-V) vs currently using applied adaptive statistical iterative reconstruction (ASIR). This institutional review board-approved study included 35 consecutive patients who underwent CT of the abdomen. Among these 35 patients, 27 with focal liver lesions underwent abdomen CT with a 128-slice multidetector unit using the following parameters: fixed noise index of 30, 1.25 mm slice thickness, 120 kVp, and a gantry rotation time of 0.5 seconds. CT images were analyzed depending on the method of reconstruction: ASIR (30%, 50%, and 70%) vs ASIR-V (30%, 50%, and 70%). Three radiologists independently assessed randomized images in a blinded manner. Imaging sets were compared to focal lesion detection numbers, overall image quality, and objective noise with a paired sample t test. Interobserver agreement was assessed with the intraclass correlation coefficient. The detection of small focal liver lesions (<10 mm) was significantly higher when ASIR-V was used when compared to ASIR (P <0.001). Subjective image noise, artifact, and objective image noise in liver were generally significantly better for ASIR-V compared to ASIR, especially in 50% ASIR-V. Image sharpness and diagnostic acceptability were significantly worse in 70% ASIR-V compared to various levels of ASIR. Images analyzed using 50% ASIR-V were significantly better than three different series of ASIR or other ASIR-V conditions at providing diagnostically acceptable CT scans without compromising image quality and in the detection of focal liver lesions.

Significant artifacts in schools: teacher and pupil perspectives

Drawing on the recent research ‘Dominant and demotic school culture: analysis of tensions fields’ this paper analyses found artifacts in 6 different Lithuanian secondary schools. The visual data was collected by making images of places and artifacts which were mentioned during the walks in the school territory with one teacher and one pupil afterwards. The analysis of images focuses particularly on two aspects: a) which artifacts are significant for teachers and pupils in the schools? b) What do these artifacts mean for teachers and pupils? Therefore, the analysis is based on comparing walks among teachers and pupils in all schools. The analysis shows obvious differences on re/presented artifacts among teachers and pupils. The teachers emphasized and showed those artifacts which on one way or another represent their schools’ achievements, like pupils’ sport achievements, pupils’ artworks, and honored pupils’ displays, and were related with aspects of pride. The paper argues the possible reasons for the importance of pride in schools. Meanwhile, pupils were highlighting spaces they like to gather around during non-learning time. Pupils appreciate less visible places because it is possible to have some privacy there. As analysis shows, different sitting artifacts (chairs, sofas, beanbags) play an important role for creating such private pupils’ ‘oases’. On the other hand, such artifacts, as pupils’ artworks, information displays, and sport achievements, seem to be meaningful for pupils if they were contributing in the creation process or were mentioned in these artifacts.

Constant time texture filtering

We present a novel texture-filtering method which can effectively separate the main image structures from textures even with high variations. Our nonlinear image decomposition is based on a variant of the weighted-median filter which incorporates structure and texture information into the guidance image. To guarantee effective texture filtering, the guidance image not only contains prominent structure edges of the input, but also reduces the contrast in texture regions. We develop a constant time algorithm for the generation of guidance image by formulating the calculation of local extrema as a histogram volume aggregation problem. The local nature of the algorithm enables an efficient parallel GPU implementation. In addition, we demonstrate the effectiveness of our texture-filtering method in the context of detail enhancement, JPEG artifact removal, inverse halftoning, image segmentation, edge detection, and image stylization.

Analysis of FIB-induced damage by electron channelling contrast imaging in the SEM.

We have investigated the Ga+ ion-damage effect induced by focused ion beam (FIB) milling in a [001] single crystal of a 316 L stainless steel by the electron channelling contrast imaging (ECCI) technique. The influence of FIB milling on the characteristic electron channelling contrast of surface dislocations was analysed. The ECCI approach provides sound estimation of the damage depth produced by FIB milling. For comparison purposes, we have also studied the same milled surface by a conventional electron backscatter diffraction (EBSD) approach. We observe that the ECCI approach provides further insight into the Ga+ ion-damage phenomenon than the EBSD technique by direct imaging of FIB artefacts in the scanning electron microscope. We envisage that the ECCI technique may be a convenient tool to optimize the FIB milling settings in applications where the surface crystal defect content is relevant.

TH-CD-202-02: A Preliminary Study Evaluating Beam-Hardening Artifact Reduction On CT Direct Electron-Density Images

Purpose: A prototype reconstruction algorithm that can provide direct electron density (ED) images from single energy CT scans is being currently developed by Siemens Healthcare GmbH. This feature can eliminate the need for kV specific calibration curve for radiation treatemnt planning. An added benefit is that beam-hardening artifacts are also reduced on direct-ED images due to the underlying material decomposition. This study is to quantitatively analyze the reduction of beam-hardening artifacts on direct-ED images and suggest additional clinical usages. Methods: HU and direct-ED images were reconstructed on a head phantom scanned on a Siemens Definition AS CT scanner at five tube potentials of 70kV, 80kV, 100kV, 120kV and 140kV respectively. From these images, mean, standard deviation (SD), and local NPS were calculated for regions of interest (ROI) of same locations and sizes. A complete analysis of beam-hardening artifact reduction and image quality improvement was conducted. Results: Along with the increase of tube potentials, ROI means and SDs decrease on both HU and direct-ED images. The mean value differences between HU and direct-ED images are up to 8% with absolute value of 2.9. Compared to that on HU images, the SDs are lower on direct-ED images, and the differences are up to 26%. Interestingly, the local NPS calculated from direct-ED images shows consistent values in the low spatial frequency domain for images acquired from all tube potential settings, while varied dramatically on HU images. This also confirms the beam -hardening artifact reduction on ED images. Conclusions: The low SDs on direct-ED images and relative consistent NPS values in the low spatial frequency domain indicate a reduction of beam-hardening artifacts. The direct-ED image has the potential to assist in more accurate organ contouring, and is a better fit for the desired purpose of CT simulations for radiotherapy.

TU‐H‐207A‐05: Automated Early Identification of An Excessive Air‐In‐Oil X‐Ray Tube Artifact That Mimics Acute Cerebral Infarct

Purpose:There is an infrequent but serious CT artifact that occurs when there is too much air in the cooling oil of an x‐ray tube. This artifact manifests as patchy hypodensities and mimics acute cerebral infarct. Routine quality control testing is unlikely to detect this artifact before it is observed in patient images. The purpose of this project was to develop an automated, quantitative method that increased the likelihood of identifying and preventing such artifacts.Methods:Using QC phantom images with a known air‐in‐oil artifact, a 1D radial representation of the 2D noise power spectrum(NPS) was calculated and compared against that for artifact‐free images. The QC program software used at our institution to analyze daily phantom images was modified to include measuring the average frequency of NPS within the water section of daily phantom scans. The threshold values developed for each CT system were incorporated into our daily QC program and email notification system.Results:The NPS for the known air‐in‐oil artifact images included a large low frequency peak compared with artifact‐free images; the average NPS frequency for these images were 0.197 and 0.319 (1/mm), respectively. The average NPS frequency values (mean+/− standard deviation) for the GE CT750, GE VCT, GE Lightspeed Xtra, and Siemens SOMATOM Definition Flash scanners were 0.322+/− 0.0058, 0.324+/−0.0024, 0.320+/−0.0020, and 0.303+/−0.0039 (1/mm), respectively. Threshold values were chosen to be the average plus or minus twice the standard deviation. Automated QC successfully identified an air‐in‐oil artifact in the Lightspeed Xtra before any detrimental clinical effect occurred; the average NPS frequency value that triggered service was 0.307, which is six standard deviations smaller than average.Conclusion:Clinically serious problems associated with the air‐in‐oil artifact can be detected earlier and mitigated/avoided by incorporating the average frequency of NPS measurements of daily phantom images into an automated QC program.

Multiscale coherence regularization reconstruction using a nonlocal operator for fast variable-density spiral imaging

PurposeNonlinear reconstruction can suppress pseudo-incoherent aliasing artifacts from variable-density spiral (VDS) trajectories when interleaves are undersampled for acquisition acceleration during MR imaging. However, large-scale aliasing artifact suppression often conflicts with fine-scale structure preservation and may cause deterioration of image quality in the reconstructed images. To address this issue, a sequential, multiscale coherence regularization algorithm using a nonlocal operator (mCORNOL) is proposed. MethodsmCORNOL is formed by exploiting the scale-control capacity of nonlocal operators in image structure measurement. By changing the scale of the structure measurement, the smoothing constraint scales can be adjusted. Starting with a large value, mCORNOL gradually reduces the smoothing constraint scale until it reaches the same level as the noise. Therefore, the large-scale smoothing constraint dominates the first few iterations of the reconstruction and removes aliasing artifacts as well as fine structures. In the following iterations, the smoothing constraint is restricted to a smaller and smaller scale, so the fidelity term progressively dominates and restores lost structures. Thus, aliasing artifact removal and structure preservation can be decoupled and achieved sequentially, which alleviates the conflicts between them. ResultsNumerical simulation and in vivo experiment results demonstrate the superiority of mCORNOL for aliasing artifact suppression and image structure preservation at high reduction factors, compared to SENSE, Total Variation and the original CORNOL reconstruction. ConclusionsmCORNOL reconstruction provides an effective way to improve image quality for undersampled VDS acquisitions.

Multi-Objective Memetic Search for Robust Motion and Distortion Correction in Diffusion MRI.

Effective image-based artifact correction is an essential step in the analysis of diffusion MR images. Many current approaches are based on retrospective registration, which becomes challenging in the realm of high b -values and low signal-to-noise ratio, rendering the corresponding correction schemes more and more ineffective. We propose a novel registration scheme based on memetic search optimization that allows for simultaneous exploitation of different signal intensity relationships between the images, leading to more robust registration results. We demonstrate the increased robustness and efficacy of our method on simulated as well as in vivo datasets. In contrast to the state-of-art methods, the median target registration error (TRE) stayed below the voxel size even for high b -values (3000 s ·mm-2 and higher) and low SNR conditions. We also demonstrate the increased precision in diffusion-derived quantities by evaluating Neurite Orientation Dispersion and Density Imaging (NODDI) derived measures on a in vivo dataset with severe motion artifacts. These promising results will potentially inspire further studies on metaheuristic optimization in diffusion MRI artifact correction and image registration in general.

Neutron imaging using a conventional small-angle neutron scattering instrument

Neutron imaging has enjoyed a flurry of activity and application in recent years. The construction of dedicated beamlines at various neutron sources has demonstrated the significant interest among the science and engineering communities, with particular relevance to industrial applications, the nondestructive testing of components and imaging of precious archaeological artefacts. Here two methods are demonstrated of how neutron imaging can be performed using a conventional small-angle neutron scattering (SANS) instrument, such as D33 at the Institut Laue–Langevin, with spatial resolutions down to about 100 µm. The first is a magnified imaging technique from a quasi-point-like source with the magnified image recorded on the usual low-resolution SANS detector. The second method uses a fine beam in a raster-scan measurement over the area of interest. Images can be reconstructed either using the transmitted beam, as in conventional radiographic imaging, or from scattering data, giving access to transmission radiographic images as well as the dark-field or scattering contrasts and phase-contrast images.

MRI-based dynamic tracking of an untethered ferromagnetic microcapsule navigating in liquid

ABSTRACTThe propulsion of ferromagnetic objects by means of MRI gradients is a promising approach to enable new forms of therapy. In this work, necessary techniques are presented to make this approach work. This includes path planning algorithms working on MRI data, ferromagnetic artifact imaging and a tracking algorithm which delivers position feedback for the ferromagnetic objects, and a propulsion sequence to enable interleaved magnetic propulsion and imaging. Using a dedicated software environment, integrating path-planning methods and real-time tracking, a clinical MRI system is adapted to provide this new functionality for controlled interventional targeted therapeutic applications. Through MRI–based sensing analysis, this article aims to propose a framework to plan a robust pathway to enhance the navigation ability to reach deep locations in the human body. The proposed approaches are validated with different experiments.

P wave velocity structure below India and Tibet incorporating anisotropic delay time effects

AbstractWe incorporate the effects of anisotropy to refine the continental‐scale 3‐D isotropic velocity model previously produced for India and Tibet by inverting 52,050 teleseismic P wave residuals. We have exploited a total of 1648 individual SKS splitting parameters to calculate the P wave travel time corrections due to azimuthal anisotropy. Our results suggest that anisotropy affects the P wave delays significantly (−0.3 to +0.5 s). Integration of these corrections into the 3‐D modeling is achieved in two ways: (a) a priori adjustment to the delay time vector and (b) inverting only for anisotropic delays by introducing strong damping above 80 km and below 360 km depths and then subtracting the obtained anisotropic artifact image from the isotropic image, to get the corrected image. Under the assumption of azimuthal anisotropy resulting from lattice preferred orientation (LPO) alignment due to horizontal flow, the bias in isotropic P wave tomographic images is clear. The anisotropy corrected velocity perturbations are in the range of ±1.2% at depths of around 150 km and reduced further at deeper levels. Although the bias due to anisotropy does not affect the gross features, it does introduce certain artifacts at deeper levels.

Before they pass away. De verhalen achter de foto’s Hannelore Vandenbussche Uitgeverij Brandt, Amsterdam, 2015

Before they pass away is ‘ [A] historic volume [that ]showcases tribal cultures around the world. With globalization, these societies are to be prized for their distinctive lifestyles, art and traditions. They live in close harmony with nature, now a rarity in our modern era. Jimmy Nelson not only presents us with stunning images of customs and artifacts, but also offers insightful portraits of people who are the guardians of a culture that they – and we – hope will be passed on to future generations in all its glory. Nelson's large-plate eld camera captures every intricate detail and ne nuance for posterity. What's more, this splendid pageantry is set against a vivid backdrop of some of the world's most pristine landscapes’.