Longitudinal Changes in Brain Diffusion MRI Indices during and after Proton Beam Therapy in a Child with Pilocytic Astrocytoma: A Case Report

Proton beam therapy (PBT) is an effective pediatric brain tumor treatment. However, the resulting microstructural changes within and around irradiated tumors are unknown. We retrospectively applied diffusion tensor imaging (DTI) and free-water imaging (FWI) on diffusion-weighted magnetic resonance imaging (dMRI) data to monitor microstructural changes during the PBT and after 8 months in a pilocytic astrocytoma (PA) and normal-appearing white matter (NAWM). We evaluated the conventional MRI- and dMRI-derived indices from six MRI sessions (t0–t5) in a Caucasian child with a hypothalamic PA: at baseline (t0), during the PBT (t1–t4) and after 8 months (t5). The tumor voxels were classified as “solid” or “fluid” based on the FWI. While the tumor volume remained stable during the PBT, the dMRI analyses identified two different response patterns: (i) an increase in fluid content and diffusivity with anisotropy reductions in the solid voxels at t1, followed by (ii) smaller variations in fluid content but higher anisotropy in the solid voxels at t2–t4. At follow-up (t5), the tumor volume, fluid content, and diffusivity in the solid voxels increased. The NAWM showed dose-dependent microstructural changes. The use of the dMRI and FWI showed complex dynamic microstructural changes in the irradiated mass during the PBT and at follow-up, opening new avenues in our understanding of radiation-induced pathophysiologic mechanisms in tumors and the surrounding tissues.

Robust Lp-Norm Inversion for High-Resolution Fluid Contents from Nuclear Magnetic Resonance Measurements

Fluid content computed from nuclear magnetic resonance (NMR) has proved to be an accurate and reliable tool for petrophysical property estimation. To overcome the limitations of conventional NMR measurements, high spatial resolution NMR (HSR-NMR) has been introduced to achieve the desired resolution for cores of any size. However, inversion of fluid contents from HSR-NMR data suffers from nonreliable measurements at the ends of the cores due to the heterogeneities of the magnetic fields caused by the relatively small size of the coil. A robust Lp-norm inversion algorithm, developed for geophysical inverse problems, has been implemented and applied on the inversion of NMR measurements. The estimated fluid content from Lp inversion matches well with the kerogen content in the cores both visually and quantitively. The resolution of the inverted fluid contents is as high as 1 inch. Further testing on the raw data with large derivations demonstrated that reliable results can only be achieved by using Lp inversion with low p’s values within the range of (1, 1.1].

The Modeling for Coupled Elastoplastic Geomechanics and Two-Phase Flow With Capillary Hysteresis in Porous Media

We study new constitutive relations employing the fundamental theory of elastoplasticity for two coupled irreversible processes: elastoplastic geomechanics and two-phase flow with capillary hysteresis. The fluid content is additively decomposed into elastic and plastic parts with infinitesimal transformation assumed. Specifically, the plastic fluid content, i.e., the total residual (or irrecoverable) saturation, is also additively decomposed into constituents due to the two irreversible processes: the geomechanical plasticity and the capillary hysteresis. The additive decomposition of the plastic fluid content facilitates combining the existing two individual simulators easily, for example, by using the fixed-stress sequential method. For pore pressure of the fluid in multi-phase which is coupled with the geomechanics, the equivalent pore pressure is employed, which yields the well-posedness of coupled multi-phase flow and geomechanics, regardless of the capillarity. We perform an energy analysis to show the well-posedness of the proposed model. And numerical examples demonstrate stable solutions for cyclic imbibition/drainage and loading/unloading processes. Employing the van Genuchten and the Drucker Prager models for capillary and the plasticity, respectively, we show the robustness of the model for capillary hysteresis in multiphase flow and elastoplastic geomechanics.

A case of congenital deformity

The fact that a low fluid content in the fetal bladder, or oligohydramnia, is usually accompanied by deformities, is confirmed by the following interesting case.

Imaging diagnosis of paranasal sinus mucocele in a Yorkshire Terrier dog

An 8-year-old, neutered male Yorkshire Terrier dog presented with left ventromedial canthus swelling over a one-month period, refractory to pharmacological therapy. There was no history of trauma. On ultrasonography, the lesion had a cystic character filled with anechoic fluid and hyperechoic sedimenting debris. The computed tomography (CT) and CT-dacryocystography showed a cystic lesion protruding from the lacrimal sac fossa and occupying a defect in the orbital plate and an ethmoidal ectoturbinate surrounded by a bony structure with an intact nasolacrimal system. The dog underwent the surgical resection of the cyst and its fluid content was aspirated. Ethmoid mucocele was diagnosed based on the CT, cytologic examination, bacterial culture and histopathologic findings. This case describes the imaging characteristics of an ethmoid mucocele and highlights the importance of CT and CT-dacryocystography in dogs with ventromedial canthus swelling that had poor response to medical treatment.

The Coexistence Of Two Different Epithelial Ovarian Tumors: A Rare Case

Background: Epithelial tumors are the most common subgroup and are seen in 60-70% of all ovarian tumors. Serous cystadenoma and mucinous cystadenoma are the most common benign epithelial tumors. Serous cystadenomas are ovarian tumors with the highest bilateral incidence. The coexistence of tumors with different histopathology in the ovaries is extremely rare and has only been reported in a few cases in the literature. We present a case of bilateral ovarian tumor that was diagnosed as serous and mucinous cystadenoma after laparoscopic surgery. Case report: A 45-year-old female patient was admitted to our center with swelling in the pelvic region and pain in the left lumbar region. US imaging showed a cystic lesion in the right adnexal area, 4x2cm in size, well-circumscribed, containing a few thin septa, and a low echo fluid content. A cystic lesion with 6x4cm sized multilocular, well-circumscribed, slightly high echo fluid content was observed in the left adnexal area. On CT, a complex cystic lesion measuring 6x4cm was observed in the left adnexal area, pushing the left ureter laterally and causing the hydroureter. In addition, a 4x2cm cystic lesion was observed in the right adnexal area and hydroureter was observed on the right side proximal to this lesion. Both lesions were removed by surgery. On histopathologic examination, the left-sided cystic lesion was diagnosed as mucinous cystadenoma, and the right-sided cystic lesion was diagnosed as serous cystadenoma. Conclusion: The coexistence of different ovarian tumor subtypes is rare. In this article, we presented a case in which serous and mucinous cystadenoma lesions were seen together for the fourth time in the literature, according to our knowledge.

Caldera’s Breathing: Poroelastic Ground Deformation at Campi Flegrei (Italy)

Ground deformation at Campi Flegrei has fuelled a long-term scientific debate about its driving mechanism and its significance in hazard assessment. In an active volcanic system hosting a wide hydrothermal circulation, both magmatic and hydrothermal fluids could be responsible, to variable degrees, for the observed ground displacement. Fast and large uplifts are commonly interpreted in terms of pressure or volume changes associated with magma intrusion, while minor, slower displacement can be related to shallower sources. This work focuses on the deformation history of the last 35 years and shows that ground deformation measured at Campi Flegrei since 1985 is consistent with a poroelastic response of a shallow hydrothermal system to changes in pore pressure and fluid content. The extensive literature available for Campi Flegrei allows constraining system geometry, properties, and conditions. Changes in pore pressure and fluid content necessary to cause the observed deformation can then be calculated based on the linear theory of poroelasticity. The predicted pore pressure evolution and fluid fluxes are plausible and consistent with available measurements and independent estimates.

Toxic Keratoconjunctivitis from Coral Reef

A 25-year-old woman presented with right eye pain, lid edema, conjunctival injection and chemosis, and mild corneal epitheliopathy after exposure to fluid content from an aquarium coral reef. Topical moxifloxacin and prednisolone were started 4 times daily, with full clinical resolution after 2 weeks. Toxin-mediated keratoconjunctivitis may occur after exposure to zoanthid coral reef, particularly in aquarium enthusiasts. Topical corticosteroids in tandem with topical antibiotics appear to be effective in mild disease. However, in severe cases that exhibit corneal infiltrates and stromal thinning, close observation is warranted in case of possible keratolysis.

Genetic Types and Main Control Factors of Microfractures in Tight Oil Reservoirs of Jimsar Sag

Microfractures are key for migrating and aggregating hydrocarbon source rocks and fracturing oil-gas exploitation in tight reservoirs. In this study, rock samples from the Lucaogou Formation tight reservoirs in Xinjiang, China, were studied using multidisciplinary techniques to investigate the genetic types and main control factors of microfractures. Results indicated that the Lucaogou Formation mainly developed diagenetic microfractures followed by tectonic microfractures, with slight formations of granular microfractures. These observations were used to clarify the relationship between the development of microfractures and the pore fluid content, lithology, mineral composition, and stratum thickness. A higher pore fluid content corresponded to a lower compressive strength of the rocks and a larger ring count, resulting in a higher probability of failure and microfracture formation. Tight reservoirs containing more quartz and carbonate minerals were found to develop more microfractures. Quartz grains showed fractures at the margins under stress, which increased the pore permeability of rocks. Carbonate minerals tended to form microfractures owing to corrosion. Microfracture formation mechanisms differed depending on lithology, and microfractures were found to develop most in dolomite and dolomitic siltstones and least in mudstone. Muddy rocks developed fewer tectonic fractures because they can easily absorb stress and undergo plastic deformation. Within a certain stratum thickness range, the average single-well fracture space and stratum thickness showed positive correlations. Moreover, the fracture space increased and the fracture density decreased as the stratum thickness increased. When the stratum thickness was less than 2.5 m, the fracture space increased linearly with the stratum thickness, and when the stratum thickness was greater than 2.5 m, the fracture space remained constant. This study will provide an essential scientific basis for enhancing tight oil recovery.