Non-Newtonian fluids with discontinuous-in-time stress tensor

We consider the system of equations describing the flow of incompressible fluids in bounded domain. In the considered setting, the Cauchy stress tensor is a monotone mapping and has asymptotically $(s-1)$-growth with the parameter $s$ depending on the spatial and time variable. We do not assume any smoothness of $s$ with respect to time variable and assume the log-H\"{o}lder continuity with respect to spatial variable. Such a setting is a natural choice if the material properties are instantaneously, e.g. by the switched electric field. We establish the long time and the large data existence of weak solution provided that $s\ge(3d+2)(d+2)$

Long-Term Survival After Surgical Resection of the Locoregional Gastric Adenocarcinoma Recurrence – A Case Report

Introduction. Recurrence is the leading cause of death of gastric cancer patients after curative resection. This report describes a 44-year-old woman with gastric adenocarcinoma and surgically resected locoregional recurrence, who has survived for more than 13 years after diagnosis.Case report. A 33-year-old woman was admitted to the Gastroenterology Clinic with an episode of epigastric pain and minor weight loss. Two years earlier she had been diagnosed with gastric adenocarcinoma G2 of the antrum, pT2N1M0 (IIA) stage. She had undergone total gastrectomy with D2 lymphadenectomy and Roux-en-Y anastomosis followed by postoperative chemotherapy. Further diagnostic investigation after two years revealed the presence of metastatic cancer in the gastric bed. An explorative laparotomy was performed, and the surgeons successfully excised the enlarged lymph node. Post-operative pathologic examination proved gastric cancer metastasis. Since April 2007 the patient has stayed recurrence-free, and there have been no signs of recurrence on either US or CT scan, as of April 2018. This patient represents a rare case of long-term survival of recurrent gastric adenocarcinoma successfully treated with surgery despite particularly poor prognosis.Conclusions. Surgery for gastric cancer recurrence is a valuable treatment in chosen patients, provided it is performed by a team of specialised surgeons.Abstract: Background: Recurrence is the leading cause of death of gastric cancer patients after curative resection. This report describes a 44-year-old woman with gastric adenocarcinoma and surgically resected locoregional recurrence who survives for more than 13 years after diagnosis. Case report: A 33-year-old woman was admitted to the Gastroenterology Clinic with an episode of epigastric pain and minor weight loss. Two years earlier she had been diagnosed with gastric adenocarcinoma G2 of the antrum, pT2N1M0 (IIA) stage. She had undergone total gastrectomy with D2 lymphadenectomy and Roux-en-Y anastomosis followed by postoperative chemotherapy. Further diagnostic investigation after 2 years revealed the presence of metastatic cancer in the gastric bed. An explorative laparotomy was performed and the surgeons successfully excised the enlarged lymph node. Post-operative pathologic examination proved gastric cancer metastasis. Since April 2007, patient stays recurrence-free and there have been no signs of recurrence on either US or CT scan, as of April 2018. This patient represents a rare case of long-term survival of recurrent gastric adenocarcinoma successfully treated with surgery despite particularly poor prognosis. Conclusions: Surgery for gastric cancer recurrence is a valuable treatment in chosen patients, provided that it is performed by a team of specialized surgeons

Cahn-Hillard and Keller-Segel systems as high-friction limits of Euler-Korteweg and Euler-Poisson equations

We consider a combined system of Euler--Korteweg and Euler--Poisson equations with friction and exponential pressure with exponent $\gamma > 1$. We show the existence of dissipative measure-valued solutions in the cases of repulsive and attractive potential in Euler--Poisson system. The latter case requires additional restriction on $\gamma$. Furthermore in case of $\gamma \geq 2$ we show that the strong solutions to the Cahn--Hillard--Keller--Segel system are a high-friction limit of the dissipative measure-valued solutions to Euler--Korteweg--Poisson equations

Długotrwałe przeżycie po resekcji chirurgicznej nawrotu lokoregionalnego gruczolakoraka żołądka — opis przypadku

Wstęp. Główną przyczyną zgonu u pacjentów z rakiem żołądka po radykalnej resekcji jest nawrót choroby. W niniejszej pracy opisano przypadek chorej z gruczolakorakiem żołądka, u której zastosowano resekcję chirurgiczną w leczeniu miejscowej wznowy. Pacjentka przeżyła ponad 13 lat od momentu rozpoznania choroby. Opis przypadku. Kobieta w wieku 33 lat została przyjęta do Kliniki Gastroenterologii z powodu bólu w nadbrzuszu i niewielkiej utraty masy ciała. Dwa lata wcześniej zdiagnozowano u niej gruczolakoraka żołądka G2 w stopniu zaawansowania pT2N1M0 (IIA), zlokalizowanego w antrum. U chorej wykonano całkowitą gastrektomię z limfadenektomią D2 i zespoleniem Roux en-Y, a następnie zastosowano chemioterapię pooperacyjną. Dalsze badania diagnostyczne wykonane po 2 latach ujawniły obecność przerzutów w loży żołądka. Wykonano laparotomię zwiadowczą oraz usunięto chirurgicznie powiększony węzeł chłonny. Pooperacyjne badanie patologiczne wykazało przerzuty raka żołądka. Od kwietnia 2007 roku chora jest wolna od nawrotu. W wykonanych do kwietnia 2018 roku badaniach USG i TK nie stwierdzono żadnych oznak wznowy nowotworu. Pacjentka ta stanowi rzadki przypadek długotrwałego przeżycia w nawrotowym gruczolakoraku żołądka po skutecznym leczeniu operacyjnym mimo złego rokowania. Wnioski. Operacyjne leczenie nawrotu raka żołądka jest ważną opcją terapeutyczną u wybranych chorych, pod warunkiem że zostanie przeprowadzone przez zespół wyspecjalizowanych chirurgów

Percutaneous left atrial appendage closure for thromboembolic prophylaxis in patients with atrial fibrillation. The impact of operator’s experience on the procedure course

Background. Left atrial appendage (LAA) closure represents an alternative strategy to oral anticoagulants in thromboembolic prophylaxis in patients with atrial fibrillation (AF). The LAA closure with the WATCHMAN™ device has been proved to be non-inferior to warfarin therapy. Nevertheless, this strategy is associated with numerous periprocedural complications. This study was conducted to determine whether the experience of the operating team affects the duration of the procedure and its complication rate. Methods. This retrospective single-centre study examined LAA percutaneous closure procedures in 43 consecutive AF patients with contraindications to oral anticoagulation (13 female, 30 male; mean age 70.98 ± 10.69 years). All device implantations were performed by two operators using the WATCHMAN™ device and the result was assessed by two echocardiographers. We compared the first 22 (group A) with the subsequent 21 procedures (group B). Results. For group B, a decrease in the overall procedure time (PT) by 28% (from 83.41 min ± 36.49 to 59.76 min ± 21.70; p = 0.006) was found, with a subsequent reduction in fluoroscopy time (FT) by 33% (from 16.59 min ± 7.25 to 11.2 min ± 7.21; p = 0.019) and the volume of contrast medium (CV) by 40% (from 129.14 mL ± 79.81 to 78.05 mL ± 33.82; p = 0.004). The incidence of periprocedural adverse events and complications was 55% (12 patients) in group A and 33% (7 patients) in group B. Conclusions. The increasing operators’ and echocardiographers’ experience in LAA closure is associated with reduction in procedure time, fluoroscopy time and contrast volume

Radiomics signature for automatic hydronephrosis detection in unenhanced low-dose CT

Purpose To investigate the diagnostic performance of an automatic pipeline for detection of hydronephrosis on kidneýs parenchyma on unenhanced low-dose CT of the abdomen. Methods This retrospective study included 95 patients with confirmed unilateral hydronephrosis in an unenhanced low-dose CT of the abdomen. Data were split into training (n = 67) and test (n = 28) cohorts. Both kidneys for each case were included in further analyses, whereas the kidney without hydronephrosis was used as control. Using the training cohort, we developed a pipeline consisting of a deep-learning model for automatic segmentation (a Convolutional Neural Network based on nnU-Net architecture) of the kidneýs parenchyma and a radiomics classifier to detect hydronephrosis. The models were assessed using standard classification metrics, such as area under the ROC curve (AUC), sensitivity and specificity, as well as semantic segmentation metrics, including Dice coefficient and Jaccard index. Results Using manual segmentation of the kidney’s parenchyma, hydronephrosis can be detected with an AUC of 0.84, a sensitivity of 75% and a specificity of 82%, a PPV of 81% and a NPV of 77%. Automatic kidney segmentation achieved a mean Dice score of 0.87 and 0.91 for the right and left kidney, respectively. Additionally, automatic segmentation achieved an AUC of 0.83, a sensitivity of 86%, specificity of 64%, PPV of 71%, and NPV of 82%. Conclusion Our proposed radiomics signature using automatic kidneýs parenchyma segmentation allows for accurate hydronephrosis detection on unenhanced low-dose CT scans of the abdomen independently of widened renal pelvis. This method could be used in clinical routine to highlight hydronephrosis to radiologists as well as clinicians, especially in patients with concurrent parapelvic cysts and might reduce time and costs associated with diagnosing hydronephrosis

Virtual non-contrast reconstructions of photon-counting detector CT angiography datasets as substitutes for true non-contrast acquisitions in patients after EVAR—performance of a novel calcium-preserving reconstruction algorithm

The purpose of this study was to evaluate virtual-non contrast reconstructions of Photon-Counting Detector (PCD) CT-angiography datasets using a novel calcium-preserving algorithm (VNC(PC)) vs. the standard algorithm (VNC(Conv)) for their potential to replace unenhanced acquisitions (TNC) in patients after endovascular aneurysm repair (EVAR). 20 EVAR patients who had undergone CTA (unenhanced and arterial phase) on a novel PCD-CT were included. VNC(Conv)- and VNC(PC)-series were derived from CTA-datasets and intraluminal signal and noise compared. Three readers evaluated image quality, contrast removal, and removal of calcifications/stent parts and assessed all VNC-series for their suitability to replace TNC-series. Image noise was higher in VNC- than in TNC-series (18.6 ± 5.3 HU, 16.7 ± 7.1 HU, and 14.9 ± 7.1 HU for VNC(Conv)-, VNC(PC)-, and TNC-series, p = 0.006). Subjective image quality was substantially higher in VNC(PC)- than VNC(Conv)-series (4.2 ± 0.9 vs. 2.5 ± 0.6; p < 0.001). Aortic contrast removal was complete in all VNC-series. Unlike in VNC(Conv)-reconstructions, only minuscule parts of stents or calcifications were erroneously subtracted in VNC(PC)-reconstructions. Readers considered 95% of VNC(PC)-series fully or mostly suited to replace TNC-series; for VNC(Conv)-reconstructions, however, only 75% were considered mostly (and none fully) suited for TNC-replacement. VNC(PC)-reconstructions of PCD-CT-angiography datasets have excellent image quality with complete contrast removal and only minimal erroneous subtractions of stent parts/calcifications. They could replace TNC-series in almost all cases

Optimal conspicuity of liver metastases in virtual monochromatic imaging reconstructions on a novel photon-counting detector CT—effect of keV settings and BMI

In dual-energy CT datasets, the conspicuity of liver metastases can be enhanced by virtual monoenergetic imaging (VMI) reconstructions at low keV levels. Our study investigated whether this effect can be reproduced in photon-counting detector CT (PCD-CT) datasets. We analyzed 100 patients with liver metastases who had undergone contrast-enhanced CT of the abdomen on a PCD-CT (n = 50) or energy-integrating detector CT (EID-CT, single-energy mode, n = 50). PCD-VMI-reconstructions were performed at various keV levels. Identical regions of interest were positioned in metastases, normal liver, and other defined locations assessing image noise, tumor-to-liver ratio (TLR), and contrast-to-noise ratio (CNR). Patients were compared inter-individually. Subgroup analyses were performed according to BMI. On the PCD-CT, noise and CNR peaked at the low end of the keV spectrum. In comparison with the EID-CT, PCD-VMI-reconstructions exhibited lower image noise (at 70 keV) but higher CNR (for ≤70 keV), despite similar CTDIs. Comparing high- and low-BMI patients, CTDI-upregulation was more modest for the PCD-CT but still resulted in similar noise levels and preserved CNR, unlike the EID-CT. In conclusion, PCD-CT VMIs in oncologic patients demonstrated reduced image noise–compared to a standard EID-CT–and improved conspicuity of hypovascularized liver metastases at low keV values. Patients with higher BMIs especially benefited from constant image noise and preservation of lesion conspicuity, despite a more moderate upregulation of CTDI

Radiomics-based machine learning model for diagnosis of acute pancreatitis using computed tomography

In the early diagnostic workup of acute pancreatitis (AP), the role of contrast-enhanced CT is to establish the diagnosis in uncertain cases, assess severity, and detect potential complications like necrosis, fluid collections, bleeding or portal vein thrombosis. The value of texture analysis/radiomics of medical images has rapidly increased during the past decade, and the main focus has been on oncological imaging and tumor classification. Previous studies assessed the value of radiomics for differentiating between malignancies and inflammatory diseases of the pancreas as well as for prediction of AP severity. The aim of our study was to evaluate an automatic machine learning model for AP detection using radiomics analysis. Patients with abdominal pain and contrast-enhanced CT of the abdomen in an emergency setting were retrospectively included in this single-center study. The pancreas was automatically segmented using TotalSegmentator and radiomics features were extracted using PyRadiomics. We performed unsupervised hierarchical clustering and applied the random-forest based Boruta model to select the most important radiomics features. Important features and lipase levels were included in a logistic regression model with AP as the dependent variable. The model was established in a training cohort using fivefold cross-validation and applied to the test cohort (80/20 split). From a total of 1012 patients, 137 patients with AP and 138 patients without AP were included in the final study cohort. Feature selection confirmed 28 important features (mainly shape and first-order features) for the differentiation between AP and controls. The logistic regression model showed excellent diagnostic accuracy of radiomics features for the detection of AP, with an area under the curve (AUC) of 0.932. Using lipase levels only, an AUC of 0.946 was observed. Using both radiomics features and lipase levels, we showed an excellent AUC of 0.933 for the detection of AP. Automated segmentation of the pancreas and consecutive radiomics analysis almost achieved the high diagnostic accuracy of lipase levels, a well-established predictor of AP, and might be considered an additional diagnostic tool in unclear cases. This study provides scientific evidence that automated image analysis of the pancreas achieves comparable diagnostic accuracy to lipase levels and might therefore be used in the future in the rapidly growing era of AI-based image analysis