Aortic Stiffness Is Independently Associated with Intracranial Carotid Artery Calcification in Patients with Ischemic Stroke.

INTRODUCTION: Intracranial carotid artery calcification (ICAC), as a strong contributor to the occurrence of ischemic stroke, might be present in the medial or intimal arterial layer. Traditional cardiovascular risk factors (CVRFs) are associated with ICAC; however, its association with new markers of vascular function is less understood. The paper aimed to evaluate the relationship between carotid-femoral pulse wave velocity (CF-PWV) and ICAC subtypes. METHODS: We enrolled 65 patients with ischemic stroke. CF-PWV, systolic, diastolic, mean blood pressure, and pulse pressure were measured within 6 ± 2 days after stroke onset, and CT was performed within 24 h. ICAC on the stroke site was classified by two methods: volume and score based. Tertiles of ICAC volume were determined, and low-grade ICAC (T1) was regarded as a reference. According to the score-based method, (dominant) medial and (dominant) intimal ICAC subtypes were determined. Data were analyzed with multivariate logistic regression. RESULTS: Medial and intimal ICAC subtypes were found in 34 (52%) and 24 (37%) patients, respectively. In 11% of patients, no ICAC calcifications were found. CF-PWV was higher in patients with high-grade ICAC (OR = 1.56, 95% CI = 1.03-2.35, p = 0.035). CF-PWV was higher in patients with the medial ICAC subtype (OR = 1.60, 95% CI = 1.00-2.55, p = 0.049) after adjustment for traditional CVRFs. CONCLUSION: Our study demonstrates that among patients with ischemic stroke, aortic stiffness is independently associated with ICAC and that medial ICAC, compared with intimal ICAC, is accompanied by more advanced aortic stiffness.

Assessment of the Carotid Bodies in Magnetic Resonance-A Head-to-Head Comparison with Computed Tomography.

OBJECTIVES: To evaluate carotid body visibility in contrast-enhanced magnetic resonance (MR) studies and to compare the results to contrast-enhanced computed tomography (CT). METHODS: Two observers separately evaluated MR and CT examinations of 58 patients. MR scans were acquired with contrast-enhanced isometric T1-weighted water-only Dixon sequence. CT examinations were performed 90 s after contrast agent administration. Carotid bodies' dimensions were noted and their volumes calculated. To quantify the agreement between both methods, Bland-Altman plots were computed. Receiver operating characteristic (ROC) and its localization-oriented variant (LROC) curves were plotted. RESULTS: Of the 116 expected carotid bodies, 105 were found on CT and 103 on MR at least by a single observer. Significantly more findings were concordant in CT (92.2%) than in MR (83.6%). The mean carotid body volume was smaller in CT (19.4 mm3) than in MR (20.8 mm3). The inter-observer agreement on volumes was moderately good (ICC (2,k) 0.42, p < 0.001), but with significant systematic error. The diagnostic performance of the MR method added up to 88.4% of the ROC's area under the curve and 78.0% in the LROC algorithm. CONCLUSIONS: Carotid bodies can be visualized on contrast-enhanced MR with good accuracy and inter-observer agreement. Carotid bodies assessed on MR had similar morphology as described in anatomical studies.

Vascular Abnormalities of the Parotid Region: An Uncommon Presentation of a Common Condition-A Case Series.

A variety of non-neoplastic diseases and benign and malignant lesions may involve parotid glands. In clinical practice, effective diagnosis is crucial to ensure proper treatment and achieve a good therapeutic effect. Unclear anamnesis and short medical history are factors that make diagnosis difficult, especially when cancer should be excluded. We present a case series of four patients who reported to the outpatient clinic with a unilateral nodule in the parotid region. The clinical presentation prevented an unequivocal diagnosis. The suspicion of a neoplastic disease resulted in profound diagnostics, including repeated cytology, ultrasound and magnetic resonance examination. Combining all the acquired information and follow-up, or a histopathologic examination, facilitated the final diagnosis. In all cases, thrombosis was diagnosed. We then analysed the diagnostic process and the associated difficulties. When thrombosis in vascular malformation occurs in the parotid region, it may have an unclear clinical and radiological presentation. Such an image can imitate both benign and malignant tumours. Ambiguous imaging in conjunction with blood cells in cytology should result in the inclusion of thrombosis in vascular malformations in the differential diagnosis.

Neural Network Training With Asymmetric Crosspoint Elements.

Analog crossbar arrays comprising programmable non-volatile resistors are under intense investigation for acceleration of deep neural network training. However, the ubiquitous asymmetric conductance modulation of practical resistive devices critically degrades the classification performance of networks trained with conventional algorithms. Here we first describe the fundamental reasons behind this incompatibility. Then, we explain the theoretical underpinnings of a novel fully-parallel training algorithm that is compatible with asymmetric crosspoint elements. By establishing a powerful analogy with classical mechanics, we explain how device asymmetry can be exploited as a useful feature for analog deep learning processors. Instead of conventionally tuning weights in the direction of the error function gradient, network parameters can be programmed to successfully minimize the total energy (Hamiltonian) of the system that incorporates the effects of device asymmetry. Our technique enables immediate realization of analog deep learning accelerators based on readily available device technologies.

Feasibility of Intravoxel Incoherent Motion (IVIM) and Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) in Differentiation of Benign Parotid Gland Tumors.

Aim: The aim of this prospective study is to identify quantitative intravoxel incoherent motion and dynamic contrast-enhanced magnetic resonance imaging parameters of the most frequent benign parotid tumors, compare their utility and diagnostic accuracy. Methods: The study group consisted of 52 patients with 64 histopathologically confirmed parotid focal lesions. Parametric maps representing apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (FP) and transfer constant (Ktrans), reflux constant (Kep), extra-vascular extra-cellular volume fraction (Ve), and initial area under curve in 60 s (iAUC) have been obtained from multiparametric MRI. Results: Statistically significant (p < 0.001) inter-group differences were found between pleomorphic adenomas (PA) and Warthin tumors (WT) in all tested parameters but iAUC. Receiver operating characteristic curves were constructed to determine the optimal cut-off levels of the most significant parameters allowing differentiation between WT and PA. The Area Under the Curve (AUC) values and thresholds were for ADC: 0.931 and 1.05, D: 0.896 and 0.9, Kep: 0.964 and 1.1 and Ve: 0.939 and 0.299, respectively. Lesions presenting with a combination of ADC, D, and Ve values superior to the cut-off and Kep values inferior to the cut-off are classified as pleomorphic adenomas. Lesions presenting with combination of ADC, D, and Ve values inferior to the cut-off and Kep values superior to the cut-off are classified as Warthin tumors. Conclusions: DWI, IVIM and quantitative analysis of DCE-MRI derived parameters demonstrated distinctive features of PAs and WT and as such they seem feasible in differentiation of benign parotid gland tumors.

Bone Damage in Chronic Otitis Media.

The middle ear bone destruction in chronic otitis media is activated and regulated by inflammation. Chronic otitis media with granulation is a highly active inflammatory process in which many cytokines are released. The bone is degraded by osteoclasts but, at the same time, protected by cytokines, growth factors, adhesion molecules and osteotropic hormones. Tumor necrosis factor-α, interleukin (IL)-1, IL-6, and OPG/RANKL present in cholesteatoma and granulation accelerate bone lysis and increase the destructive effect on the middle ear.

Intrasalivary Thymic Carcinoma: A Case Report and Literature Review.

Ectopic thymic carcinomas are rarely diagnosed in the thyroid gland, let alone in extrathyroid tissues. In the currently available literature, only five cases of extrathyroidal malignancies with thymic differentiation have been reported as arising in the major salivary glands. A 69-year-old female presented with a slow-growing palpable mass in the left parotid gland. Fine needle aspiration biopsy suggested metastatic cancer, whereas core needle biopsy revealed high-grade squamous cell carcinoma. The patient underwent left radical parotidectomy with selective ipsilateral lymph node dissection and subsequent radiation therapy. The surgical specimen was taken for histopathological examination. Microscopically, the tumor resembled thymic carcinoma. It was composed of large nests of squamoid cells with smooth contours, focally with a syncytial growth pattern, and accompanied by abundant lymphocytes with reactive lymphoid follicles. This appearance resembled a micronodular thymic carcinoma with lymphoid hyperplasia. Moreover, the tumor displayed expression of squamous markers (p40 and p63) and markers of thymic carcinoma (CD5 and CD117). Therefore, the final diagnosis of intrasalivary thymic carcinoma was rendered. The molecular analysis including next-generation sequencing demonstrated no variants of the strong, potential, or unknown clinical significance. The patient remains disease-free at 1-year follow-up. In the current case, we comprehensively present a clinical, microscopic, molecular, and radiological picture of CD5-positive squamous cell carcinoma of the parotid. We postulate that similar cases should be designated as intrasalivary thymic carcinoma analogically to similar thyroid tumors. Our case and the limited literature data indicate they should be distinguished from conventional squamous cell carcinoma of major salivary glands due to their rather favorable prognosis.

Juvenile psammomatoid ossifying fibroma.

Juvenile psammomatoid ossifying fibroma (JPOF) is an uncommon benign and locally aggressive tumor. We report an unusual head tumour with extremely rare extensiveness and aggressivness. The patient was 18-year-old female with three-day-lasting headache and repetitive oral bleeding. Computed tomography revealed a large, well-circumscribed, expansile mass occupying ethmoid cells, nasal cavities and ventral part of the sphenoid sinus, with extention into the anterior cranial fossa. Pterional craniotomy was carried out. On one-year follow-up recurrence of the lesion was identified and the second surgery was performed. The lesion is under supervision now, due to incomplete removal.

Efficacy comparison of multi-phase CT and hepatotropic contrast-enhanced MRI in the differential diagnosis of focal nodular hyperplasia: a prospective cohort study.

BACKGROUND: Different clinical behaviour influences the importance of differentiating focal nodular hyperplasia (FNH) from other focal liver lesions (FLLs). The aim of this study was to compare the efficacy of contrast-enhanced CT and MRI in the diagnosis of FNH. METHODS: 157 patients with equivocal FLLs detected in ultrasonography subsequently underwent multi-phase CT and MRI with the use of hepatotropic contrast agent (Gd-BOPTA) in a 1.5 T scanner. Examinations were evaluated by three independent readers. Diagnostic efficacy of different radiological signs of FNH in both CT and MRI was compared and AFROC analysis was performed. RESULTS: 4 hepatocellular adenomas, 95 hepatocellular carcinomas, 98 hemangiomas, 138 metastases and 45 FNHs were diagnosed. In both CT and MRI the radiological sign of the highest accuracy was the presence of the central scar within FNH (0.93 and 0.96 relatively). The sum of two radiological signs in MRI: homogeneous enhancement in hepatic arterial phase (HAP) and enhancing lesion in hepatobiliary phase (HBP) was characterized with high values of sensitivity (0.89), specificity (0.97), PPV (0.82), NPV (0.98) and accuracy (0.96). After inclusion of clinical data into analysis the best discriminating feature in MRI was the presence of enhancing lesion in HBP in patients without cirrhosis. In this regard, efficacy parameters increased to 1.00, 0.99, 0.94, 1.00 and 0.99 accordingly. The area under the curve in AFROC analysis of MRI performance was significantly larger than of CT (p = 0.0145). CONCLUSION: Gd-BOPTA-enhanced MRI is a more effective method in the differential diagnosis of FNH than multi-phase CT.

Diagnostic Imaging of Hepatocellular Carcinoma - A Pictorial Essay.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, which develops mostly in the setting of chronic liver disease. European Association for the Study of the Liver (EASL) and European Organization for Research and Treatment of Cancer (EORTC) prepared guidelines for screening, follow-up and diagnosis of HCC to facilitate decision making and optimize both diagnostic and therapeutic protocols. The review briefly describes etiology, epidemiology and histopathology of HCC and presents EASL-EORTC guidelines for surveillance and diagnosis of HCC. Target population and screening algorithm is presented in the surveillance section. Ultrasound imaging of HCC and the role of contrast enhanced ultrasound are described as well as the value of laboratory tests in screening. Further, radiological features of HCC in multiphase CT and dynamic contrast enhanced MRI and diagnostic criteria are presented. Additionally, the advantages of advanced techniques in MRI such as diffusion weighed imaging and the use of hepatocyte-specific contrast agents are discussed. Lastly, the EASL-EORTC guidelines are compared with the guidelines of the American Association for the Study of Liver Diseases and the Japan Society of Hepatology. Also LI-RADS and the Barcelona Clinic Liver Cancer classification are mentioned. In the near future, due to the ongoing advances in imaging a revision of the guidelines may be expected.

Predictive value of apparent diffusion coefficient in evaluation of colorectal carcinoma hepatic metastases' response to radiofrequency ablation.

PURPOSE: To establish the apparent diffusion coefficient (ADC) suitability to evaluate the radiofrequency ablation (RFA) outcome in patients with chemotherapy resistant or partially responding colorectal adenocarcinoma liver metastases. MATERIALS AND METHODS: A total of 56 patients with 116 metastatic foci over 10 mm in diameter were examined with 1.5 Tesla MRI scanner 1 day before percutaneous RFA treatment. Lesions were evaluated in echo-planar diffusion-weighted images with b = 0, 15 and 500 s/mm(2) . On basis of computed tomography scan at 6 weeks, 3 and 6 months after RFA and serum CEA (carcinoembryonic antigen) level lesion were recognized as responding or nonresponding lesions. ADC values for b = 0-15 and 0-500 s/mm(2) of responding and nonresponding lesions were compared. RESULTS: Noncomplete ablation concerned 28 lesions. Mean pretreatment ADC values for b = 0-15 and 0-500 s/mm(2) of responding metastases were significantly lower (2.14 and 1.48 × 10(-3) mm(2) /s) than those of nonresponding tumors (2.7 and 1.74 × 10(-3) mm(2) /s). Sensitivity, specificity, and accuracy of ADC values for b = 0-15 s/mm(2) were 79 (95%CI = 59-92), 85 (95%CI = 76-92), 84%; and for b = 0-500 s/mm(2) , the efficacy parameters were, respectively, 78 (95%CI = 56-92), 78 (95%CI = 67-86), and 78%. The P value was under 0.001 for both b parameters. CONCLUSION: The pretreatment ADCs values of chemotherapy resistant or partially responding colorectal adenocarcinoma liver metastatic lesion can be predictive factor of tumors response to RFA therapy.

Is hepatotropic contrast enhanced MR a more effective method in differential diagnosis of hemangioma than multi-phase CT and unenhanced MR?

BACKGROUND: Cavernous hemangiomas are the most frequent neoplasms of the liver and in routine clinical practice they often need to be differentiated from malignant tumors and other benign focal lesions. The purpose of this study is to evaluate whether diagnostic accuracy of magnetic resonance imaging (MRI) of hepatic hemangiomas, showing atypical pattern on US, improves with the use of Gd-BOPTA in comparison with contrast-enhanced multi-phase computed tomography (CT). METHODS: 178 consecutive patients with ambiguous hepatic masses showing atypical hyperechoic pattern on grey-scale US, underwent unenhanced and contrast-enhanced multi-phase multi-detector CT and MR (1.5T) with the use of liver-specific contrast medium gadobenate dimeglumine (Gd-BOPTA). After intravenous contrast administration arterial (HAP), venous-portal (PVP), equilibrium phases (EP) both in CT and MR and additionally hepatobiliary phase (HBP) in MR were obtained. 398 lesions have been detected including 99 hemangiomas and 299 other lesions. RESULTS: In non-enhanced MDCT examination detection of hemangiomas was characterized by sensitivity of 76%, specificity of 90%, PPV of 71%, NPV of 92% and accuracy of 86%.Non-enhanced MR examination showed sensitivity of 98%, specificity of 99%, PPV of 99%, NPV of 99% and accuracy of 99%.After intravenous administration of contrast medium in MR the mentioned above parameters did not increase significantly. CONCLUSION: Gd-BOPTA-enhanced MR in comparison with unenhanced MRI does not improve diagnostic accuracy in discriminating hemangiomas that show non-specific appearance in ultrasound examination. Unenhanced MR as a method of choice should directly follow US in course of diagnostic algorithm in differentiation of hemangiomas from other liver tumors.

The role of MR imaging in detection of hepatic iron overload in patients with cirrhosis of different origins.

BACKGROUND: There are many pathological conditions with hepatic iron overload. Classical definite diagnostic methods of these disorders are invasive and based on a direct tissue biopsy material. For the last years the role of MR imaging in liver diagnostics has been increasing. MRI shows changes of liver intensity in patients with hepatic iron overload. Changes in MR signal are an indirect consequence of change of relaxation times T2 and T2*, that can be directly measured. The purpose of the study was to evaluate usefulness of MR imaging in the detection of hepatic iron overload in patients with cirrhosis of different origins. METHODS: MR imaging at 1.5T was prospectively performed in 44 patients with liver cirrhosis who had undergone liver biopsy with histopathological assessment of hepatic iron deposits. In all patients the following sequences were used: SE, Express, GRE in T2 and T1-weighted images. Signal intensity (SI) was measured on images obtained with each T2 weighted sequence by means of regions of interest, placed in the liver and paraspinal muscles. The correlation between iron overload, histopathological score, serum ferritin and SI ratio was analyzed. RESULTS: In 20 patients with iron overload confirmed by the biopsy, the liver parenchyma demonstrated lower signal intensity than that of paraspinal muscles. This effect was visible only in 8 patients with hepatic iron overload in Express T2-weighted images. Higher signal intensity of liver than that of skeletal muscles on GRE - T2 weighted images was noted in 24 patients with cirrhosis and without elevated hepatic iron concentration. We observed a correlation between low and high iron concentration and liver to muscle SI ratio. CONCLUSION: MR imaging is a useful and fast noninvasive diagnostic tool for the detection of liver iron overload in patients with cirrhosis of different origins.Liver to muscle SI ratio in GRE-T2-weighted sequence facilitates to differentiate patients with low and high degree of hepatic iron overload, which correlates with the origin of liver cirrhosis.

Convex dynamics: unavoidable difficulties in bounding some greedy algorithms.

A greedy algorithm for scheduling and digital printing with inputs in a convex polytope, and vertices of this polytope as successive outputs, has recently been proven to be bounded for any convex polytope in any dimension. This boundedness property follows readily from the existence of some invariant region for a dynamical system equivalent to the algorithm, which is what one proves. While the proof, and some constructions of invariant regions that can be made to depend on a single parameter, are reasonably simple for convex polygons in the plane, the proof of boundedness gets quite complicated in dimension three and above. We show here that such complexity is somehow justified by proving that the most natural generalization of the construction that works for polygons does not work in any dimension above two, even if we allow for as many parameters as there are faces. We first prove that some polytopes in dimension greater than two admit no invariant region to which they are combinatorially equivalent. We then modify these examples to get polytopes such that no invariant region can be obtained by pushing out the borders of the half spaces that intersect to form the polytope. We also show that another mechanism prevents some simplices (the simplest polytopes in any dimension) from admitting invariant regions to which they would be similar. By contrast in dimension two, one can always get an invariant region by pushing these borders far enough in some correlated way; for instance, pushing all borders by the same distance builds an invariant region for any polygon if the push is at a distance big enough for that polygon. To motivate the examples that we provide, we discuss briefly the bifurcations of polyhedra associated with pushing half spaces in parallel to themselves. In dimension three, the elementary codimension one bifurcation resembles the unfolding of the elementary degenerate singularity for codimension one foliations on surfaces. As the subject of this paper is new for the communities most interested in Chaos, we take some care in describing various links of our problem to classical issues (in particular linked to Diophantine approximation) as well as to various technological or commercial issues, exemplified, respectively, by digital printing and a problem in scheduling.