The role of MRI using liver-specific contrast agent in the assessment of focal liver lesion

Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUNIFESP, EPM, Depto. de Diagnóstico por ImagemSciEL

Tomographic aspects of xanthogranulomatous pyelonephritis and related complications

The authors present their experience involving seven patients with histopathologic diagnosis of xanthogranulomatous pyelonephritis who were submitted to preoperative computed tomography (CT). The results are the following: a) stones (86 percent of the cases), b) increase in renal volume, c) hydronephrosis, d) density measurements (from 14 to 29 HU), e) enhancement found in all cases, f) extrarenal involvement (all cases). CT has shown to be a reliable method in characterizing xanthogranulomatous xyelonephritis and extrarenal involvement.Os autores apresentam a sua experiência em 7 pacientes com diagnóstico anátomopatológico de Pielonefrite Xantogranulomatosa (PXG) submetidos a tomografia computadorizada (TC) pré-operatória. Os parâmetros estudados e seus resultados foram: a) presença de cálculos em 86% dos casos, b) volume renal frequentemente aumentado, c) hidronefrose, d) medidas de densidade variando entre 14 e 29 HU, e) presença de realce em todos os casos, f) comprometimento extra-renal, também presente em todos os casos. A TC demonstrou ser um método bastante fidedigno na caracterização da PXG e sua extensão extra-renal.Federal University of São Paulo Paulist School of Medicine Department of Imagery DiagnosisUNIFESP, Paulist School of Medicine Department of Imagery DiagnosisSciEL

Gadolinium-enhanced magnetic resonance angiography for hepatomesenteric vascular evaluation: single and double doses comparison in schistosomiasis patients

OBJECTIVE: To evaluate the visibility of hepatomesenteric vascular segments by 3D gadolinium-enhanced magnetic resonance (MR) angiography and to compare the method effectiveness between two different gadolinium doses (single and double doses). MATERIALS AND METHODS: A prospective study was performed with 36 schistosomiasis patients who were submitted to 3D contrast-enhanced MR angiography. Scans were performed in a high-field equipment (1.5 T), with body coil and power injector for intravenous contrast administration. Contrast double doses (Gd-DTPA 0.2 mmol/kg) and single doses (0.1 mmol/kg) were randomly used respectively in 21 and 15 patients. Studies were interpreted by consensus between two observers who have rated the visualization degree of 25 proximal vascular segments without knowing the dose used. RESULTS: Proximal and calibrous vascular segments have presented higher visualization degree in the greatest part of the sample studied. The celiac trunk, common hepatic artery, splenic artery, proximal and medium third of superior mesenteric artery, portal vein, splenic vein and superior mesenteric vein have presented grade 2 visualization in more than 70% of the sample studied. As regards comparison between different doses, there was no significant difference (p < 0.05) in the visualization degree of several structures evaluated, between double dose and single dose groups, except for an isolate case of evaluation of right hepatic artery (p = 0.008) in which the single dose group has presented a higher frequency of grade 2 visualization with statistical significance. CONCLUSION: The visualization degree of hepatomesenteric vascular segments by 3D gadolinium-enhanced MR angiography is high, especially in the proximal and calibrous segments. The comparison between groups using single and double contrast doses has demonstrated similar results.OBJETIVO: Determinar a freqüência de visualização dos segmentos da circulação hepatomesentérica pela angiografia por ressonância magnética (angio-RM) com contraste e comparar o valor do método, utilizando-se duas diferentes dosagens de gadolínio (doses simples e dupla). MATERIAIS E MÉTODOS: Estudo prospectivo de 36 pacientes esquistossomóticos submetidos a angio-RM. Os exames foram realizados em equipamento de RM de 1,5 T, usando-se bobina de corpo e bomba injetora para a administração endovenosa do contraste. Foram utilizadas, de maneira randomizada, dose dupla do contraste paramagnético (0,2 mmol/kg de Gd-DTPA) em 21 pacientes e dose simples (0,1 mmol/kg) em outros 15 pacientes. Os exames foram interpretados por dois observadores em consenso, que classificaram o grau de visualização de 25 segmentos vasculares estabelecidos para análise, sem conhecimento da dose de gadolínio utilizada. RESULTADOS: Os segmentos vasculares proximais e de maior calibre foram as estruturas com melhor grau de visualização na maioria da amostra em estudo. O tronco celíaco, a artéria hepática comum, a artéria esplênica, a croça e terço médio da artéria mesentérica superior, a veia porta, a veia esplênica e a veia mesentérica superior apresentaram grau 2 de visualização em mais de 70% da amostra. Quanto à comparação das diferentes dosagens, não houve diferença significante (p < 0,05) no grau de visualização das diversas estruturas analisadas entre os grupos dose simples e dose dupla, com uma exceção isolada: na avaliação da artéria hepática direita (p = 0,008), o grupo dose simples apresentou maior freqüência de visualização grau 2, com valor significante. CONCLUSÃO: O grau de visualização dos segmentos vasculares hepatomesentéricos pela angio-RM com contraste é elevado, sendo maior nos segmentos proximais e de maior calibre. A comparação entre os grupos que utilizaram dose simples e dupla de contraste demonstrou resultados semelhantes.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUNIFESP, EPM, Depto. de Diagnóstico por ImagemSciEL

Morphometric Analysis of the Internal Auditory Canal by Computed Tomography Imaging

Background: Many clinical and experimental studies have been done to analyze the anatomical and functional aspects of the internal auditory canal (IAC) in human beings since there are great inter-individual variability and structural variations that may occur regarding the other adjacent structures.Objectives: the purpose of this study was to characterize the morphology of the internal auditory canal (IAC) during development using high resolution computed tomography (CT) and to analyze its dimensions, which will be determined by measuring the nearby areas and structures using a system of digital image processing.Patients and Methods: CT images of the IAC of 110 normal subjects aged 1 to 92 years (mean age, 46.5 years) of both genders were reviewed to determine the shape, area, opening width (OW), longitudinal length (LL), vertical diameter (VD) and distance from the vestibular aqueduct.Results: the shapes observed in children and adults were funnel-shaped (74% and 58.3%, respectively), cylindrical (22% and 30.9%, respectively) and bud-shaped (4% and 10.8%, respectively). the measurements by CT in children were: area= 50.30 mm(2), OW = 7.53 mm, length = 11.17 mm, VD = 4.82 mm and the distance between the IAC and the vestibular aqueduct (VA) = 12.63 mm. in adults, the measurements were: area = 44.64 mm(2), OW = 7.10 mm, length = 9.84 mm, VD = 4.47 mm and the distance between IAC and VA = 11.17 mm.Conclusions: CT images showed that the IAC has different shapes and when the measurements obtained for children were compared with those of adults, the parameters that presented statistically significant differences in either gender were length and diameter. Copyright (C) 2012, Tehran University of Medical Sciences and Iranian Society of Radiology. Published by Kowsar Corp. All rights reserved.Universidade Federal de São Paulo, Dept Morphol & Genet, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diag Image, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Phys, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diag Image, São Paulo, BrazilUniversidade Federal de São Paulo, Inst Phys, São Paulo, BrazilWeb of Scienc

Acute pyelonephritis: frequency of findings in patients submitted to computed tomography

OBJECTIVE: The present study was aimed at establishing the frequency of renal/perirenal and extrarenal computed tomography findings in patients with acute pyelonephritis, and evaluating the interobserver agreement. MATERIALS AND METHODS: Retrospective study based on the analysis of computed tomography images of 47 patients with clinical and laboratory findings of acute pyelonephritis. Two independent observers evaluated the main renal/perirenal and extrarenal alterations. The frequency of tomographic findings and interobserver agreement were analyzed by the kappa (k) test. RESULTS: The frequency of tomographic findings for the several parameters was the following: striated nephrogram, 100%; renal enlargement, 65%; perirenal fat heterogeneity, 62.5%; renal calculi, 16.6%; abscesses, 21%; pleural effusion, 36%; thickened gallbladder wall, 32.5%; periportal edema, 32.5%. The k test for interobserver agreement demonstrated reproducibility ranging between moderate (k = 0.511 for renal enlargement) to almost perfect (k = 0.87 for striated nephrogram) for all of the parameters analyzed, except for perirenal fat heterogeneity (k = 0.268). CONCLUSION: The frequency of findings of acute pyelonephritis on computed tomography is high. Overall, striated nephrogram was the most frequent finding. Peri- and extra-renal alterations were found in about 2/3 of the cases. Computed tomography demonstrated a good interobserver agreement.OBJETIVO: Estimar a freqüência das alterações tomográficas renais e extra-renais em pacientes com pielonefrite aguda e avaliar o grau de concordância interobservador. MATERIAIS E MÉTODOS: Realizamos trabalho retrospectivo a partir da análise dos exames de tomografia computadorizada de 47 pacientes com diagnóstico clínico e laboratorial de pielonefrite aguda. Dois examinadores independentes avaliaram as principais alterações renais, perirrenais e extra-renais. Foi medida a freqüência dos achados tomográficos e a concordância interobservador por meio do teste kappa (kapa). RESULTADOS: A freqüência dos achados tomográficos para os diversos parâmetros estudados foi: nefrograma heterogêneo, 100%; nefromegalia, 65%; heterogeneidade da gordura, 62,5%; nefrolitíase, 16,6%; abscessos, 21%; derrame pleural, 36%; espessamento da vesícula biliar, 32,5%; edema periportal, 32,5%. O teste kapa para a concordância interobservador demonstrou reprodutibilidade variando entre moderada (kapa = 0,511 para nefromegalia) e quase perfeita (kapa = 0,87 para nefrograma heterogêneo) para todos os parâmetros estudados, exceto para a heterogeneidade da gordura perirrenal (kapa = 0,268). CONCLUSÃO: A freqüência dos diversos achados tomográficos de pielonefrite aguda é elevada, sendo o nefrograma heterogêneo o sinal mais comum. Alterações perinefréticas e extra-renais são observadas em até dois terços dos casos. A tomografia computadorizada apresenta boa concordância interobservador.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemHospital São Luiz Serviço de US, TC e RMHospital São Luiz Serviço de TCUNIFESP, EPM, Depto. de Diagnóstico por ImagemSciEL

Analysis of the effect of renal excretory system cooling during thermal radiofrequency ablation in an animal model

Objective: Analysis of renal excretory system integrity and efficacy of radiofrequency ablation with and without irrigation with saline at 2 o C (SF2). Materials and Methods: The median third of sixteen kidneys were submitted to radiofrequency (exposition of 1 cm) controlled by intra-surgical ultrasound, with eight minutes cycles and median temperature of 90 o C in eight female pigs. One excretory renal system was cooled with SF2, at a 30ml/min rate, and the other kidney was not. After 14 days of post-operatory, the biggest diameters of the lesions and the radiological aspects of the excretory system were compared by bilateral ascending pyelogram and the animals were sacrificed in order to perform histological analysis. Results: There were no significant differences between the diameters of the kidney lesions whether or not exposed to cooling of the excretory system. Median diameter of the cooled kidneys and not cooled kidneys were respectively (in mm): anteroposterior: 11.46 vs. 12.5 (p = 0.23); longitudinal: 17.94 vs. 18.84 (p = 0.62); depth: 11.38 vs. 12.25 (p = 0.47). There was no lesion of the excretory system or signs of leakage of contrast media or hydronephrosis at ascending pyelogram. Conclusion: Cooling of excretory system during radiofrequency ablation does not significantly alter generated coagulation necrosis or affect the integrity of the excretory system in the studied model.Pontifical Catholic University of Campinas Faculty of MedicineRadium InstituteFederal University of São PauloUniversity of Campinas School of Medical SciencesUNIFESPSciEL

Robust Disturbance Rejection Control of DC/DC Interleaved Boost Converters with Additional Sliding Mode Component

Interleaved DC/DC boost converters are nowadays widely studied due to their properties of reducing the current ripple and increasing fault tolerance. This paper describes a control method that allows good output voltage regulation, together with robustness against parameter uncertainties, deviation of the supply voltage of the source, and load deviation. These objectives are obtained by determining an equivalent circuital scheme of the interleaved boost and associating to this scheme a linear mathematical model by means of the exact linearization method. Subsequently, trajectory tracking control techniques are employed based on disturbance compensation and a sliding mode component is added to cope with parameter uncertainties and possible compensation errors. The controller, applied to the above equivalent conventional boost model, allows to command the duty cycle of single phases of the Mosfets. This controller uses the output voltage and the currents flowing in the phases of the converter as feedback variables. Simulation results show the validity of the proposed approach

Analysis Of The Effect Of Renal Excretory System Cooling During Thermal Radiofrequency Ablation In An Animal Model.

Analysis of renal excretory system integrity and efficacy of radiofrequency ablation with and without irrigation with saline at 2°C (SF2). The median third of sixteen kidneys were submitted to radiofrequency (exposition of 1 cm) controlled by intra-surgical ultrasound, with eight minutes cycles and median temperature of 90°C in eight female pigs. One excretory renal system was cooled with SF2, at a 30mL/min rate, and the other kidney was not. After 14 days of post-operatory, the biggest diameters of the lesions and the radiological aspects of the excretory system were compared by bilateral ascending pyelogram and the animals were sacrificed in order to perform histological analysis. There were no significant differences between the diameters of the kidney lesions whether or not exposed to cooling of the excretory system. Median diameter of the cooled kidneys and not cooled kidneys were respectively (in mm): anteroposterior: 11.46 vs. 12.5 (p = 0.23); longitudinal: 17.94 vs. 18.84 (p = 0.62); depth: 11.38 vs. 12.25 (p = 0.47). There was no lesion of the excretory system or signs of leakage of contrast media or hydronephrosis at ascending pyelogram. Cooling of excretory system during radiofrequency ablation does not sig¬nificantly alter generated coagulation necrosis or affect the integrity of the excretory system in the studied model.4093-