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We have used a high-precision, high-resolution digital terrain model (DTM) of the NASA Mars 2020 rover Perseverance landing site in Jezero crater based on mosaicked images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (MRO HiRISE) camera as a reference dataset to evaluate DTMs based on Mars Express High Resolution Stereo Camera (MEX HRSC) and MRO Context camera (CTX) images. Results are consistent with our earlier HRSC-HiRISE comparisons at the Mars Science Laboratory (MSL) Curiosity landing site in Gale crater, confirming that those results were not compromised by the small area compared and potential problems with spatial registration. Specifically, height errors are on the order of half a pixel and correspond to an image matching error of 0.2–0.3 pixel but estimates of horizontal resolution are 10–20 pixels. Products from the HRSC team pipeline at DLR are smoother but more precise vertically than those produced by using the commercial stereo package SOCET SET®. The DLR products are also homogenous in quality, whereas the SOCET products are less smoothed and have higher errors in rougher terrain. Despite this weak variation, our results are consistent with a rule of thumb of 0.2–0.3 pixel matching precision based on many prior studies. Horizontal resolution is significantly coarser than the DTM ground sample distance (GSD), which is typically 3–5 pixels.

We have used high-precision, high-resolution digital terrain models (DTMs) of the NASA Mars Science Laboratory and Mars 2020 rover landing sites based on mosaicked images from the Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (MRO HiRISE) camera as a reference data set to evaluate DTMs based on Mars Express High Resolution Stereo Camera (MEX HRSC) images. The Next Generation Automatic Terrain Extraction (NGATE) matcher in the SOCET SET/GXP® commercial photogram- metric system produces DTMs with relatively good (small) horizontal resolution but high error, and results are terrain dependent, with poorer resolution and smaller errors on smoother surfaces. Multiple approaches to smoothing the NGATE DTMs give very similar tradeoffs between resolution and error. Smoothing the NGATE DTMs with a 5x5 lowpass filter is near optimal in terms of both combined resolution-error performance and local slope estimation, but smoothing with a single pass of an area-based matcher, which has been the standard approach for generating planetary DTMs at the U.S. Geological Survey to date results in similar errors and only slightly worse resolution. DTMs from the HRSC team processing pipeline fall within this same trade space but are less sensitive to terrain roughness. DTMs produced with the Ames Stereo Pipeline also fall in this space at resolutions intermediate between NGATE and the team pipeline. Although DTM resolution and error each vary by a factor of 2, the product of resolution and error is much more consistent, varying by ≤20% across multiple image sets and matching algorithms. Refinement of the stereo DTM by photoclinometry can yield significant quantitative improvement in resolution and some improvement in error (improving their product by as much as a factor of 2), provided that albedo variations over distances smaller than the stereo DTM resolution are not too severe.

A planetary body’s global shape provides both insight into its geologic evolution, and a key element of any Planetary Spatial Data Infrastructure (PSDI). NASA’s Cassini mission to Saturn acquired more than 600 moderate- to high-resolution images (

We report the first multiscale, systematic field-based testing of correlations between orbital scale advanced spaceborne thermal emission and reflection radiometer visible near-infrared (VNIR)/shortwave infrared (SWIR) reflectance and thermal infrared relative emissivity and outcrop scale Raman spectroscopy, VNIR reflectance, X-ray diffraction (XRD), and laser-induced breakdown spectroscopy (LIBS) mineralogy and chemistry in a saline dry lakebed. This article is one of three reports describing the evolution of salt deposits, meteorological record, and surface and subsurface salt mineralogy in Dalangtan, Qaidam Basin, a hyperarid region of the Tibet Plateau, China, as potential environmental, mineralogical, and biogeochemical analogs to Mars. We have successfully bridged remote sensing data to fine scale mineralogy and chemistry data. We have defined spectral end-members in the northwestern Qaidam Basin and classified areas within the study area on the basis of their spectral similarity to the spectral end-members. Results of VNIR/SWIR classification reveal zonation of spectral units within three large anticlinal domes in the study area that can be correlated between the three structures. Laboratory Raman, VNIR reflectance, XRD, and LIBS data of surface mineral samples collected along a traverse over Xiaoliangshan (XLS) indicate that the surface is dominated by gypsum, Mg sulfates, Na sulfates, halite, and carbonates, with minor concentrations of illite present in most samples as well. Our results can be used as a first step toward better characterizing the potential of orbital reflectance spectroscopy as a method for mineral detection and quantification in salt-rich planetary environments, with the benefit that this technique can be validated on the ground using instruments onboard rovers.

Mars once supported globally-distributed river systems; these flowed more recently and more intensely than previously thought., Mars is dry today, but numerous precipitation-fed paleo-rivers are found across the planet’s surface. These rivers’ existence is a challenge to models of planetary climate evolution. We report results indicating that, for a given catchment area, rivers on Mars were wider than rivers on Earth today. We use the scale (width and wavelength) of Mars paleo-rivers as a proxy for past runoff production. Using multiple methods, we infer that intense runoff production of >(3–20) kg/m2 per day persisted until 1 Ga. Our improved history of Mars’ river runoff places new constraints on the unknown mechanism that caused wet climates on Mars.

Surface debris covers much of the western portion of the McMurdo Ice Shelf and has a strong influence on the local surface albedo and energy balance. Differential ablation between debris-covered and debris-free areas creates an unusual heterogeneous surface of topographically low, high-ablation, and topographically raised (‘pedestalled’), low-ablation areas. Analysis of Landsat and MODIS satellite imagery from 1999 to 2018, alongside field observations from the 2016/2017 austral summer, shows that pedestalled relict lakes (‘pedestals’) form when an active surface meltwater lake that develops in the summer, freezes-over in winter, resulting in the lake-bottom debris being masked by a high-albedo, superimposed, ice surface. If this ice surface fails to melt during a subsequent melt season, it experiences reduced surface ablation relative to the surrounding debris-covered areas of the ice shelf. We propose that this differential ablation, and resultant hydrostatic and flexural readjustments of the ice shelf, causes the former supraglacial lake surface to become increasingly pedestalled above the lower topography of the surrounding ice shelf. Consequently, meltwater streams cannot flow onto these pedestalled features, and instead divert around them. We suggest that the development of pedestals has a significant influence on the surface-energy balance, hydrology and flexure of the ice shelf.

On 2 March 2016, several small en échelon tabular icebergs calved from the seaward front of the McMurdo Ice Shelf, and a previously inactive rift widened and propagated by ~3 km, ~25% of its previous length, setting the stage for the future calving of a ~14 km2 iceberg. Within 24 h of these events, all remaining land-fast sea ice that had been stabilizing the ice shelf broke-up. The events were witnessed by time-lapse cameras at nearby Scott Base, and put into context using nearby seismic and automatic weather station data, satellite imagery and subsequent ground observation. Although the exact trigger of calving and rifting cannot be identified definitively, seismic records reveal superimposed sets of both long-period (>10 s) sea swell propagating into McMurdo Sound from storm sources beyond Antarctica, and high-energy, locally-sourced, short-period (

Small-crater counts on Mars light-toned sedimentary rock are often inconsistent with any isochron; these data are usually plotted then ignored. We show (using an 18-HiRISE-image, >10^4 crater dataset) that these non-isochron crater counts are often well-fit by a model where crater production is balanced by crater obliteration via steady exhumation. For these regions, we fit erosion rates. We infer that Mars light-toned sedimentary rocks typically erode at ~10^2 nm/yr, when averaged over 10 km^2 scales and 10^7-10^8 yr timescales. Crater-based erosion-rate determination is consistent with independent techniques, but can be applied to nearly all light-toned sedimentary rocks on Mars. Erosion is swift enough that radiolysis cannot destroy complex organic matter at some locations (e.g. paleolake deposits at SW Melas), but radiolysis is a severe problem at other locations (e.g. Oxia Planum). The data suggest that the relief of the Valles Marineris mounds is currently being reduced by wind erosion, and that dust production on Mars, Accepted by Icarus. 8 figures

Lakes existed on Mars later than 3.6 billion years ago, according to sedimentary evidence for deltaic deposition. The observed fluviolacustrine deposits suggest that individual lake-forming climates persisted for at least several thousand years (assuming dilute flow). But the lake watersheds’ little-weathered soils indicate a largely dry climate history, with intermittent runoff events. Here we show that these observational constraints, although inconsistent with many previously proposed triggers for lake-forming climates, are consistent with a methane burst scenario. In this scenario, chaotic transitions in mean obliquity drive latitudinal shifts in temperature and ice loading that destabilize methane clathrate. Using numerical simulations, we find that outgassed methane can build up to atmospheric levels sufficient for lake-forming climates, if methane clathrate initially occupies more than 4% of the total volume in which it is thermodynamically stable. Such occupancy fractions are consistent with methane production by water–rock reactions due to hydrothermal circulation on early Mars. We further estimate that photochemical destruction of atmospheric methane curtails the duration of individual lake-forming climates to less than a million years, consistent with observations. We conclude that methane bursts represent a potential pathway for intermittent excursions to a warm, wet climate state on early Mars.

Summary Fibro-osseous diseases of the craniofacial bones share many characteristics, including radiologic patterns. Some of these lesions appear to evolve in a similar biologic fashion, beginning as a radiolucency composed essentially of fibrous matrix with minimal calcification and maturing to progressively more radiopaque lesions containing more mineralized tissue. The clinician has a number of modalities at his or her discretion for the radiologic evaluation of a suspected fibro-osseous lesion. Conventional intraoral and panographic radiography remain the mainstay of initial evaluation. CT, however, is extremely helpful for the detection of abnormal calcification and ossification, as well as osteoclastic and osteoblastic activity. CT is somewhat limited in its ability to detect soft-tissue lesions when compared with MR imaging, but it can be used to detect subtle bone erosion. The Dentascan and similar reconstructive programs have the ability to format CT data in panographic and other planes to optimally define these lesions. MR imaging is an especially useful technology for assessing the involvement of adjacent soft tissues with the pathologic process, for diagnosing osteomyelitis complicating FOD, and for establishing the extent of involvement of the marrow spaces for a variety of different fibro-osseous lesions. MR imaging is a relatively sensitive imaging modality, but can be nonspecific for the detection and characterization of lesional calcifications.

In this paper, a Bayesian framework is used to infe r HiRISE-equivalent rock density from CTX image features without needing to explicitly identify rocks. The statistical relationship between HiRISE rock density and CTX image features is modeled using Bayesian Networks. The model is enriched by including geological features—specifically, geomorphic units. The geomorphic units are identified by geologists based on different surface features visible in a variety of orbital da ta. The inclusion of geomorphology in the Bayesian framework makes it possible to not only infer HiRISE-equivalent rock density directly from CTX image features, but also to make a preliminary assessment of the representative geomorphic units. HiRISE and CTX images of the Mars Phoenix mission landing area are used in this study. Rock density e stimates from HiRISE images are used as ground truth to train the Bayesian Network using features extracted from corresponding CTX images. The approach is evaluated on a few test cases using a probabilistic estimate of landing safety based on inferred rock density from CTX image features. The initial results of this exploratory study show that predicted landing safety from the inferred rock density is very close to that obtained using actual HiRISE roc k density estimates.

Epithelium-lined cysts of the jaw can be either odontogenic or non-odontogenic. Cysts that exhibit keratinization of their epithelial lining are called odontogenic keratocysts. They compose approximately 8% of all odontogenic cysts. There is a frequent association with unerrupted teeth, and a high incidence of occurrence of keratocysts in the multiple basal cell nevus syndrome. The significance of odontogenic keratocysts is their high potential for recurrence after their removal. There is no specific radiographic feature, however, that distinguishes them from non-keratinized odontogenic cysts. High resolution computed tomography (CT) studies can exquisitely determine the extent of these lesions and pinpoint areas of cortical breakthrough as well as involvement of the teeth. This information is invaluable in surgical planning for excision of these lesions.

Distal biceps tendon rupture is a rare injury. While plain radiographs are usually not helpful in visualizing the defect, evaluation of the tendon with MRI has proven to be useful as it depicts complete anatomic detail of the tendon and associated structures. Its multiplanar imaging capability and superior soft tissue contrast resolution makes MRI a prime diagnostic tool in the diagnosis of tendon disorders. We report a case of complete rupture of the biceps tendon diagnosed by MRI.

A patient with a surgically proven intracanalicular archnoid cyst was studied using computed tomography, magnetic resonance imaging, and air CT cisternography. The lesion had a similar radiographic appearance to acoustic neuroma and therefore, although rare, must be considered in the differential diagnosis of intracanalicular mass lesions. We report a case in which examination was performed, in evaluating the lesion, utilizing high-resolution air CT cisternography and magnetic resonance imaging (MRI).

Gas has been identified within diarthrodial joints for more than eight decades. From a radiologic standpoint, the so-called “vacuum phenomenon” is the most common demonstration of gas. We retrospectively reviewed computed tomographic scans of 495 feet and ankles performed over a 24-month period. We found 12 patients (2.4%) with clearly demonstrable gas within the tibiotalar or subtalar joints. This gas was not associated with the presence of fixation hardware or infection. Each patient with gas in the subtalar joint had plain radiographic changes consistent with subtalar arthritis. We conclude that gas in the subtalar joint can be effectively demonstrated by high-resolution CT techniques in the subtalar and tibiotalar joints in patients with advanced degenerative disease.

This is a case report which shows the potential benefit of magnetic resonance imaging in accurately visualizing occult metastatic lesions to bone. The case involves a relatively young patient with metastatic colon carcinoma to the calcaneus who ultimately required amputation.

Avulsion of the triceps tendon is a rare injury. We report a case of complete avulsion of the triceps tendon diagnosed by magnetic resonance imaging (MRI) and confirmed surgically. The excellent soft tissue contrast and multiplanar imaging capability of MRI makes it an ideal tool to diagnose this disorder. To our knowledge, this is the first reported case of MRI diagnosis of complete avulsion of the triceps tendon.

Preoperative evaluation of patients with medically refractory complex partial seizures requires intensive EEG monitoring. Part of this process may include insertion of depth electrodes into temporal lobe structures. Although many imaging methods have been used for stereotactic placement of the electrodes, only computed tomography (CT) has been used to verify position after implantation. We studied 30 patients in whom magnetic resonance imaging (MRI) was used to visualize the position of stainless-steel electrodes stereotactically implanted in the temporal lobes. The procedure is noninvasive, does not utilize radiation, and has the additional advantages of multiplanar capability, increased soft tissue contrast, and lack of bony artifacts commonly associated with CT.

To the Editor. —After reviewing the Letter to the Editor by Drs Kasper and Chandler,1we wish to bring your attention to the fact that no talc products have been used in the manufacturing of Kimono and Sagami lubricated condoms (Sagami, Japan). On January 13, 1995, Mayer Laboratories Inc informed Kasper and Chandler of this fact. However, they apparently did not incorporate this information in the material submitted toJAMA. Mayer Laboratories Inc is the principal US distributor of Kimono and other condoms manufactured by Sagami. We support all efforts to eliminate the use of talc in the manufacturing of latex condoms because there may be pathologic consequences from exposure to talc.

Lipomas are very common benign soft tissue neoplasms arising from fatty tissue and may occur anywhere in the body. They are usually slow growing, painless masses often noted in the extremities of adult women. Occurrence in the hands and feet is unusual and those found in the digits are extremely rare. We describe a case of a lipoma presenting as a soft tissue mass of the index finger and show how computed tomography was extremely helpful in preoperative assessment by accurately defining the size of the lesion, the degree of bone involvement, and even giving indication of its underlying pathology.

Summary Injection of Teflon lateral to the vocalis muscle improves voice quality, cough, and helps prevent aspiration in patients with unilateral vocalfold paralysis. Unsatisfactory results may be associated with Teflon being injected either too superficially or in excessive or insufficient quantities. Evaluation and treatment of patients with poor results following Teflon injection of the vocal folds are notoriously difficult. Although radiologic studies are not used widely in these patients, they may be extremely helpful. Cross-sectional imaging using computed tomography of a larynx after Teflon injection demonstrates the position and amount of the material easily and may be especially helpful in planning revision surgery

Diagnosis and differential diagnosis of an eosinophilic granuloma of right pedicle of an 8 1/2-year-old male child are discussed. Roentgenograms, a tomogram and histological studies are presented.

Intraoperative pancreatic ultrasound can be useful to identify small masses or cysts that are not readily palpable at surgery. In our case, a small (2.0 cm diameter) pseudocyst was demonstrated preoperatively by ultrasound and computed tomography, but could not be palpated at surgery. Intraoperative ultrasound located and helped to guide needle aspiration of the pancreatic pseudocyst. Other indications for intraoperative pancreatic ultrasound are reviewed.

Abdominal computed tomography (CT) scans of 55 patients who had ingested Gastrografin (meglumine diatrizoate and diatrizoate sodium) diluted to 2% with tap water and flavored with a commercial fruit juice base were reviewed. Twenty patients (36%) demonstrated intraluminal precipitation of Gastrografin shown by focal areas of markedly increased attenuation within the gastric lumen or trapped within gastric folds. Beam-hardening artifact produced by precipitation was observed, which limited the diagnostic value of some examinations. In vitro CT scans of the same Gastrografin solution titrated with hydrochloric acid or sodium hydroxide showed that by raising the pH of the solution, precipitation was virtually eliminated. Fifty-one CT scans of the abdomen using a buffered Gastrografin solution demonstrated precipitation in only five patients. Properly buffered dilute oral Gastrografin solutions should significantly decrease the prevalence of precipitation during abdominal CT examinations.

• The giant cholesterol cyst is a clinical entity distinct from cholesterol granulomas and other destructive lesions of the petrous bone. Preoperative assessment by computed tomographic scan and magnetic resonance imaging is extremely helpful. Attempts at total resection of the lesion are not necessary. Adequate surgical drainage may be established through the mastoid or middle fossa. ( Arch Otolaryngol Head Neck Surg 1988;114:451-453)

Inelastic scattering of 480 MeV and 340 MeV α particles on 208Pb, 116Sn and 58Ni has been used in a search for high excitation energy giant multipole resonances, up to E* = 60 MeV for 208Pb and E* = 45 MeV for 116Sn and 58Ni. Above the well known quadrupole and monopole resonances, there is clear evidence for a very wide set of negative parity modes (including the already known high energy octupole), followed and mixed with another very wide set of positive parity resonances, extending up to the limits of the experimental spectra.

The systematics of the excitation energy of the giant dipole, monopole, and quadrupole resonances are shown to exhibit an isotopic effect. For a given element, the excitation energy of the transition decreases faster with the increasing neutron number than the empirical laws fitting the overall data. This effect is discussed in terms of the available models.