MRI Findings of Rectal Submucosal Tumors

Rectal submucosal lesions encompass a wide variety of benign and malignant tumors involving the rectum. With optical colonoscopy, any mass-like protrusion covered by normal mucosa, whether the underlying process is intramural or extramural in origin, may be reported as a submucosal lesion. Whereas the assessment of submucosal lesions may be limited with performing optical colonoscopy, cross-sectional imaging such as CT, transrectal ultrasonography and MRI allows the evaluation of perirectal tissues and pelvic organs in addition to the entire thickness of the rectum, and so this is advantageous for the assessment of rectal submucosal tumors. Among these, MRI is the best investigative modality for soft tissue characterization. Therefore, knowledge of the MRI features of rectal submucosal tumors can help achieve accurate preoperative diagnoses and facilitate the appropriate management

A First Study on Distribution Characteristics of Common Dolphin in Korean Waters: A Study Using Data Collected during the Past 20 Years

The common dolphin (Delphinus delphis) is the second-most bycaught species in Korean waters. To provide key information about their habitat boundaries and hotspots for spatial conservation and management, the spatial use of this species was examined using data obtained from sighting and bycatch surveys of cetaceans in the past 20 years. The 95% minimum convex polygon and 95% density contour of fixed-kernel analysis suggested that the boundary of the home range of common dolphins is limited to the coastal region (Busan–Sokcho) of the East Sea/Sea of Japan. From 50% density contours drawn by kernel density estimation, it was suggested that their hotspots are around the coast of Ulsan–Pohang, Doghae, and Sokcho within the home range. Common dolphins were not observed in the Yellow Sea. Hence, shallow waters in the geographic area of the coastal region of the Yellow Sea are likely not a suitable habitat for common dolphins in this region

Predictive modeling of microhole profile drilled using a focused electron beam with backing materials

This study establishes a simple and rapid predictive model for a microhole profile drilled using a focused electron beam based on the finite difference method. Vertical irradiation and full penetration using a focused beam with a Gaussian distribution were reflected onto the three-dimensional mesh of metallic substrates. The predictive hole profiles on the substrate were estimated by analyzing the phase transition using predictive temperature distributions. To validate the predictive accuracy of model, experimental drilling processes on AISI 304 stainless steel substrates were conducted, and the experimental hole qualities were measured using microcomputed tomography. Comparisons between predictive and experimental results represented high predictive accuracy in three criteria: hole diameters, straightness, and geometrical hole shape. Applying the fractional energy absorptance dependent on the substrate depth significantly improved the prediction accuracy of model. The predictive results demonstrated that the thermal analysis with temperature distributions could predict the drilled hole qualities rapidly and accurately, avoiding the high computational loads from considerations for velocity fields or pressure distributions around the substrate

Portal venous perfusion steal causing graft dysfunction after orthotopic liver transplantation: serial imaging findings in a successfully treated patient

A 53-year-old male with hepatocellular carcinoma underwent orthotopic liver transplantation. Preoperative computed tomography revealed main portal vein luminal narrowing by flat thrombi and the development of cavernous transformation. On post-transplantation day 1, thrombotic portal venous occlusion occurred, and emergency thrombectomy was performed. Subsequent Doppler ultrasonography and contrast-enhanced ultrasonography confirmed the restoration of normal portal venous flow. The next day, however, decreased portal venous velocity was observed via Doppler ultrasonography, and serum liver enzymes and bilirubin levels remained persistently elevated. Direct portography identified massive perfusion steal through prominent splenorenal collateral veins. Stent insertion and balloon angioplasty of the portal vein were performed, and subsequent Doppler ultrasonography demonstrated normalized portal flow parameters. Afterwards, the serum liver enzymes and bilirubin levels rapidly normalized

Necrotic lymphoma in a patient with post-transplantation lymphoproliferative disorder: ultrasonography and CT findings with pathologic correlation

Seventeen months after kidney transplantation for the treatment of nephrotic syndrome, a retroperitoneal mass was incidentally detected in a 30-year-old man during routine follow-up. Ultrasonography revealed a mass measuring 5.5 cm×4.3 cm located between the liver and the atrophic right kidney, which showed markedly heterogeneous internal echogenicity. Contrast-enhanced computed tomography displayed a mild degree of enhancement only at the periphery of the mass, while the center lacked perceivable intensification. The patient underwent surgical resection. The final pathological diagnosis was non-Hodgkin lymphoma (diffuse large B-cell lymphoma), and extensive necrosis was observed on microscopic examination. We found that the prominent heterogeneous echogenicity of the mass (an unusual finding of lymphoma) demonstrated on ultrasonography is a result of extensive necrosis, which may sometimes occur in patients with post-transplantation lymphoproliferative disorder

Mouse Hepatic Tumor Vascular Imaging by Experimental Selective Angiography

<div><p>Purpose</p><p>Human hepatocellular carcinoma (HCC) has unique vascular features, which require selective imaging of hepatic arterial perfusion and portal venous perfusion with vascular catheterization for sufficient evaluation. Unlike in humans, vessels in mice are too small to catheterize, and the importance of separately imaging the feeding vessels of tumors is frequently overlooked in hepatic tumor models. The purpose of this study was to perform selective latex angiography in several mouse liver tumor models and assess their suitability.</p><p>Materials and Methods</p><p>In several ectopic (Lewis lung carcinoma, B16/F10 melanoma cell lines) and spontaneous liver tumor (<i>Albumin-Cre/MST1^fl/fl/MST2^fl/fl</i>, <i>Albumin-Cre/WW45^fl/fl</i>, and <i>H-ras12V</i> genetically modified mouse) models, the heart left ventricle and/or main portal vein of mice was punctured, and latex dye was infused to achieve selective latex arteriography and/or portography.</p><p>Results</p><p><i>H-ras12V</i> transgenic mice (a HCC and hepatic adenoma model) developed multiple liver nodules that displayed three different perfusion patterns (portal venous or hepatic artery perfusion predominant, mixed perfusion), indicating intra-tumoral vascular heterogeneity. Selective latex angiography revealed that the Lewis lung carcinoma implant model and the <i>Albumin-Cre/WW45^fl/fl</i> model reproduced conventional angiography findings of human HCC. Specifically, these mice developed tumors with abundant feeding arteries but no portal venous perfusion.</p><p>Conclusion</p><p>Different hepatic tumor models showed different tumor vessel characteristics that influence the suitability of the model and that should be considered when designing translational experiments. Selective latex angiography applied to certain mouse tumor models (both ectopic and spontaneous) closely simulated typical characteristics of human HCC vascular imaging.</p></div

Selective latex arteriography of an <i>Albumin-Cre/MST1</i>^<i>fl/fl</i><i>/MST2</i>^<i>fl/fl</i> mouse that developed multiple spontaneous hepatocellular carcinomas.

<p>(A) Histologic examination (hematoxylin and eosin staining, ×100). (B) The whole liver and (C, D) magnified images from a surgical microscope display a hypervascular mass supplied by feeding arteries (black arrow) and enlarged prominent arteries (white arrow) in the tumor-free background liver. The dotted box in (B) indicates the region magnified in (C, D).</p

Selective angiography using blue latex dye.

<p>(A) Systemic arteriography and (B) direct portography in a wild-type mouse. The stomach, duodenum, and jejunum were removed to allow a clear view of the vessels. (C-E) Magnified images of the liver after selective angiography and subsequent tissue clearing procedures (upper panels) and histological assessment (lower panels, hematoxylin-eosin staining) were performed. (C) Arteriography, (D) portography, and (E) hepatic venography specimens are shown. Blue latex dye particles are seen only in the target vascular compartment (yellow arrows), which seems to have been slightly dilated during injection (single arrow, hepatic artery; double arrow, portal vein; thick arrow, central vein). Blue latex dye particles are not detectable in non-target vascular compartments (white arrows).</p

Conventional angiography of human hepatocellular carcinoma and latex angiography in mouse Lewis lung carcinoma model.

<p>(A) Representative images of conventional angiography of a typical case of human hepatocellular carcinoma. From left, superior mesenteric arterial angiography, indirect portography, celiac trunk arterial angiography (early phase), and celiac trunk arterial angiography (late phase) images are shown. The branches of the tumor-feeding artery supplying the medial portion of the mass (white arrow) and displaced portal veins (black arrow) are clearly visible. Note that the main mass (white arrowheads) and the multiple small satellite nodules are extremely hypervascular in nature. (B-E) Selective latex angiography of a liver Lewis lung carcinoma ectopic tumor model. (B-C) Selective latex arteriography and the subsequent tissue clearance procedure were performed in a liver Lewis lung carcinoma-bearing mouse. (B) Gross image of the whole liver and (C) sectioned slices demonstrate the hypervascular mass (arrows) supplied by the hepatic artery. The enlarged, slightly tortuous tumor-feeding artery (red arrow) is clearly visible. (D-E) Selective latex portography and the subsequent tissue clearance procedure were performed in a liver Lewis lung carcinoma-bearing mouse. (D) Gross image of the whole liver and (E) sectioned slices show that portal venules do not enter the mass (arrows).</p

Summary of the angiography procedures performed in each tumor model.

<p>Summary of the angiography procedures performed in each tumor model.</p