A case report of a prostate cancer metastasis in the pancreas exhibiting vascular encasement

We report a patient who presented with a 4-month history of intermittent epigastric pain. Computed tomography (CT) angiography of the abdomen demonstrated a stenotic celiac trunk but also encasement of the common proper hepatic artery, gastroduodenal artery, and proper hepatic artery by an ill-defined hypoattenuating mass of the pancreatic head. Biopsy confirmed metastatic prostate cancer to the pancreas that occurred 4 years after radiation and androgen deprivation therapy. A follow-up staging study demonstrated an osseous metastasis at the T4 spinous process. This case demonstrates an unusual case of prostate metastasis to the pancreas with the involvement of a main abdominal vessel. With treatment improvements leading to longer survival rates from prostate cancer, radiologists should be aware of atypical metastases that may arise in the long term.

Unexplained Acute Distal Pancreatitis: Association With Subsequent Diagnosis of Pancreatic Cancer

Background: Distal pancreatitis is an atypical imaging subtype of acute pancreatitis involving only the pancreatic body and tail, with sparing of the head. If no cause is identified, then suspicion for a small imaging-occult cancer may be warranted. Objective: To determine the frequency of subsequently diagnosed pancreatic cancer in patients with unexplained acute distal pancreatitis and to compare this frequency to that found in patients with unexplained nondistal pancreatitis. Methods: This retrospective study included patients who underwent contrast-enhanced CT between January 1, 2019 and December 31, 2020 showing acute pancreatitis without identifiable explanation. Studies were classified as showing distal or nondistal acute pancreatitis using a consensus process. Fisher's exact test was used to compare frequency of subsequent pancreatic cancer histologic diagnosis between groups; negative classification required ≥6 months of imaging follow-up and/or ≥12 months of clinical follow-up. Interreader agreement among seven readers of varying experience was assessed by Fleiss kappa. Results: Among 215 patients with acute pancreatitis, 116/215 (54%) had no identifiable explanation, forming the study sample. A total of 100/116 (86%) (57±18 years; 59 men, 41 women) patients had nondistal acute pancreatitis; 16/116 (14%) (66±14 years; 10 men, 6 women) had distal acute pancreatitis. Among patients with nondistal pancreatitis, none were subsequently diagnosed with pancreatic cancer; 62 had sufficient follow-up (median, 2.5 years) to be classified as negative for pancreatic cancer. Among patients with distal pancreatitis, nine were subsequently diagnosed with pancreatic cancer (median interval to suspected cancer on subsequent CT, 174 days); five had sufficient follow-up (median, 3.1 years) to be classified as negative for pancreatic cancer. Frequency of pancreatic cancer was higher (p<.001) in patients with distal (9/14 [64%]; 95% CI 35-87%) than with nondistal (0/62 [0%]; 95% CI, 0-6%) pancreatitis. Interreader agreement for distal versus nondistal pancreatitis classification was excellent (κ=0.81). Conclusion: Distal pancreatitis without identifiable cause on CT is an uncommon but unique imaging subtype of acute pancreatitis that is associated with a high frequency of pancreatic cancer. Clinical Impact: In patients with acute distal pancreatitis without identifiable cause, endoscopic ultrasound-guided biopsy should be considered to evaluate for an underlying small cancer.

Spectrum of MRI Features of Mucin-producing Neoplasms in the Abdomen and Pelvis

Mucin-producing neoplasms in the abdomen and pelvis are a distinct entity, separate from simple fluid-containing neoplasms and loculated fluid collections. Mucin is a thick gelatinous substance and-owing to its high water content-has imaging features that can be mistaken for those of simple fluid-containing neoplasms with multiple imaging modalities. However, mucin-producing neoplasms arise from specific organs in the abdomen and pelvis, with unique imaging appearances, knowledge of which is important to guide accurate diagnosis and management. With its large field of view and high soft-tissue resolution, MRI has advantages over other imaging modalities in characterizing these neoplasms. The authors focus on the spectrum of MRI features of such mucin-producing neoplasms and illustrate how-despite a varied organ origin-some of these neoplasms share similar MRI and histopathologic features, thereby helping narrow the differential diagnosis. One common finding in these tumors is that the presence of internal complexity and solid enhancing components increases as the degree of malignant transformation increases. Lack of internal complexity generally indicates benignity. These tumors have a varied range of prognosis; for example, a low-grade appendiceal mucinous neoplasm is indicative of a good prognosis, while a mucinous tumor of the rectum is known to manifest at an early age with aggressive behavior and poorer prognosis compared with its nonmucinous counterpart. Online supplemental material is available for this article. ^©RSNA, 2022.

Color variation in periodic Ag line arrays patterned by using electron-beam lithography

Periodic Ag line arrays with different line pitches from 500 nm to 950 nm on ITO coated glass substrates have been fabricated by using electron-beam lithography (EBL) technique for studying the color light guide in a display system. The patterned Ag line array is used as a light outcoupling and color-selection component due to the emission wavelength changed by the Ag line arrays with different periodic distances that could achieve color variation. We have demonstrated that the ITO coated glass substrates containing periodic Ag line arrays with varied line pitches can be used as a color filter in a display device. This means that with a proper metallic nanostructure layer, the red, green, and blue colors in a display system can be obtained without a traditional color filter for modern multi-applications of optoelectronic display devices.

The correlation between polarization modulated near-field optical images and the anisotropy of the probe

The true anisotropic images taken with the polarization modulation near-field optical microscope are often influenced by the linear dichroism of the tapered fibre probe. In this paper, we develop a new method to separate the anisotropic image form probe's dichroism. Our calculations show that the near-field optical image is simply a vector sum of the sample's dichroism and the probe's dichroism, when the probe's anisotropy is small. With this result, we demonstrate the true anisotropic images of poly(phenylene vinylene) (PPV) thin films. The PPV films show non-uniform mesoscale dichroic domains with average domain size, approximately 0.3 mm, and the coefficient for linear dichroism is 1.25 x 10(4) cm(-1).

Soluble electroluminescent poly(phenylene vinylene)s with balanced electron- and hole injections

We report a new route for the design of efficient soluble electroluminescent PPV-based copolymers bearing electron-deficient oxadiazole (OXD) moieties on side chains. The introduction of OXD through a long alkylene spacer with PPV backbone provides a molecular dispersion of OXD in the film; both the side chain OXD and the main chain PPV do retain their own electron-transport and emissive properties, respectively. The use of phenylene vinylene derivatives with asymmetric and branched substituents and a long spacer provides solubility for ease of device fabrication as well as amorphous structure to allow a well-mixing of OXD groups with the main chains. By properly adjusting the OXD content through copolymerization, we can tailor the chemical structure of electroluminescent material to give a balance of hole- and electron injections for various metal cathodes, such that the quantum efficiency is significantly improved and the turn-on voltage is reduced for the devices with aluminum and calcium. For the device with calcium fabricated in open air, a maximum brightness of 15000 cd/m(2) at 15 V/100 nm and a maximum luminance efficiency of 2.27 cd/A can be obtained, respectively, about 30 times brighter and 9.4 times more efficient than those with the corresponding homopolymer, poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV). The use of physical blends to simulate the copolymers provides no significant improvement, since phase-separation structures appear, causing an inefficient utilization of OXD and sometimes voltage-dependent emission spectra. The present route permits a fabrication of single layer PLED with high brightness, high efficiency, and low turn-on voltage.

Interactions between hydrophobic and hydrophilic silicon surfaces using a tapered probe in near-field scanning optical microscopy

We examined the tip-sample interaction of a Si(111) surface processed with HF solution. The interaction length of the probe with its hydrophobic surface is approximately 30, and the frequency responses show an interaction force of elastic type. By contrast, the damping curve on a hydrophilic surface, Si with thin oxide, operates on a longer length of 100. Here, the frequency responses indicate an interaction force of the viscous type.

Phase separation in polyaniline with near-field scanning optical microscopy

We report the studies of conjugated polymers, polyaniline thin films, with a near-field scanning optical microscope. Because of the absorption variation in different oxidation states, transmission-mode near-field scanning optical microscope images were employed to map out the distribution of the oxidation states on a submicrometer scale. When the near-field wavelength is varied (between 632.8 and 543.5 nm), the phase separation between the oxidized and the reduced repeated units, with domain sizes on a nanometer-length scale, is observed.

Two-dimensional near-field intensity distribution of tapered fiber probes

The near-field intensity distribution perpendicular to the light-propagation direction was measured by photochemical processes on conjugated-polymer thin films. The shape of the distribution is elliptical, with the long axis along the direction of the incident polarization. The results are compared with calculations based on the realistic tapered probe geometry. The asymmetry distribution is due to the simultaneous presence of horizontal and vertical electric fields in the near field.

Dual-optical-mode near-field scanning optical microscopy

The simultaneous operation of near-field scanning optical microscopy (NSOM) in reflection and transmission modes is demonstrated. In the transmission mode, a low-noise, large-area silicon photodetector was mounted between the piezoelectric transducer scanning stage and the sample. In the reflection mode, either a photomultiplier tube or two large-area silicon detectors was used for signal collection. The reflection-mode setup consisting of two silicon detectors provides a large numerical aperture of 0.9 as well as symmetrical detection of emitting photons. The dielectric thin films and the light-emitting polymers were used to demonstrate the capability of these two modes of NSOM. A comparison between these two different setups is also presented.

[Clinical application of a decoction of "fast-developing liquid for gastrointestinal ultrasound"]

B-ultrasound has been widely used in examination of the human organs. Because of the gas and mucus interference in the ultrasound, the ultrasonic examination of stomach so far has been still a knotty problem. On the basis of TCM theory that the drugs for promoting Qi flow and resolving dampness have the function of elimination of gas and mucus, the authors have successfully made a high effective Fast-developing Liquid for Gastrointestinal Ultrasound for B-ultrasound examination of stomach with satisfactory picture-developing results, excellent development rate of the control group and the gastric cancer group being 94.9% and more than 90%, respectively. After the decoction being taken, the tissue structures in the milieu interne were not changed physiologically and pathologically. The five layers of the gastric walls could be distinguished clearly and the values of the normal stomach be measured correctly. Some signs about the gastric cancer, e.g. the size and property of the cancer, the translocation of the cancer inside and outside the gastric cavity as well as of the other organs and lymph nodes could be observed distinctly. The consistent rate of B-ultrasound with gastroscopy, biopsy, X-ray and surgical operation diagnosis for the gastric cancer is over 94%. But no significant differences between B-ultrasound and the above other examinations were found statistically with all the P greater than 0.05. B-ultrasound diagnosis of the gastric cancer is not only highly efficient, but also can be used to observe the infiltration of the cancer cells into the lower layer of the mucous membrane.(ABSTRACT TRUNCATED AT 250 WORDS)