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1.
Langenbecks Arch Surg ; 408(1): 103, 2023 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-36826595

RESUMO

PURPOSE: The association between sarcopenia of kidney transplant recipients and outcome after kidney transplantation (KT) has not yet been fully understood and is still considered controversial. The aim of our study was to analyze the impact of pre-transplant sarcopenia on graft function, postoperative complication rates, and survival of the patients after renal transplantation. METHODS: In this retrospective single-center study, all patients who underwent KT (01/2013-12/2017) were included. Demographic data, rejection rates, delayed graft function, and graft and patient survival rates were analyzed. Sarcopenia was measured in computed tomography images by the sex-adjusted Hounsfield unit average calculation (HUAC). RESULTS: During the study period, 111 single KTs (38 women and 73 men) were performed. Living donor kidney transplants were performed in 48.6%. In total, 32.4% patients had sarcopenia. Sarcopenic patients were significantly older (59.6 years vs. 49.8 years; p < 0.001), had a higher body mass index (BMI = 27.6 kg/m2 vs. 25.0 kg/m2; p = 0.002), and were more likely to receive deceased donor kidneys (72.2% vs. 41.3%; p = 0.002). Interestingly, 3 years after KT, the creatinine serum levels were significantly higher (2.0 mg/dl vs. 1.5 mg/dl; p = 0.001), whereas eGFR (39.9 ml/min vs. 53.4 ml/min; p = 0.001) and graft survival were significantly lower (p = 0.004) in sarcopenic transplant recipients. Sarcopenic patients stayed in hospital significantly longer postoperatively than those who were non-sarcopenic. CONCLUSIONS: At the time of kidney transplantation, sarcopenia was found to predict reduced long-term graft function and diminished graft survival after KT. The early identification of sarcopenic patients can not only enable an optimized selection of recipients, but also the initiation of pre-habilitation programs during the waiting period.


Assuntos
Transplante de Rim , Sarcopenia , Masculino , Humanos , Feminino , Transplante de Rim/efeitos adversos , Sobrevivência de Enxerto , Estudos Retrospectivos , Transplantados , Doadores de Tecidos , Rejeição de Enxerto
2.
Cell Tissue Bank ; 22(4): 651-664, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33893901

RESUMO

Antibiotic carrier particles of variable size might influence mechanic properties within impacted thermodisinfected and native cancellous bone different. Herafill®G containing calciumsulfate and calciumcarbonate provides high local concentrations of gentamicin being important for revision surgery in infected joint replacements. Native and thermodisinfected cancellous bone derived from 6 to 7 months old piglets was used for in vitro impaction bone grafting and supplemented each with Herafill®G granules of two different sizes. Micromovement of implants related to shear force was measured in 29 specimens distributed in 6 groups. Thermodisinfected cancellous bone revealed a significant higher shear force resistance than native bone with a mean difference of 423.8 mdeg/Nm (p < 0.001) ranging within 95% confidence interval from 181.5 to 666.0 mdeg/Nm. Adding small granules to thermodisinfected bone did not reduce shear force resistance significantly since adding large granules to native bone improved it by 344.0 mdeg/Nm (p < 0.003). Shear force resistance was found higher at the distal region of the implant compared to a proximal point of measurement throughout all specimens. Less impaction impulses were necessary for thermodisinfected bone. Thermodisinfected cancellous bone might achieve a higher degree of impaction compared with native bone resulting in increased resistance against shear force since impaction was found increased distally. Supplementation of thermodisinfected bone with small granules of Herafill®G might be considered for application of local antibiotics. Large granules appeared more beneficial for supplementation of native bone. Heterogeneity of bone graft and technical aspects of the impaction procedure have to be considered regarding the reproducibility of femoral impaction bone grafting.


Assuntos
Artroplastia de Quadril , Substitutos Ósseos , Animais , Transplante Ósseo , Osso Esponjoso , Fêmur , Reoperação , Reprodutibilidade dos Testes , Suínos
3.
Eur Radiol ; 29(3): 1565-1573, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30159622

RESUMO

OBJECTIVES: The aim of this study was to assess native T1 mapping in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) before and 6 months after balloon pulmonary angioplasty (BPA) and compare the results with right heart function and pulmonary haemodynamics. METHODS: Magnetic resonance imaging at 1.5 T and right heart catheterisation were performed in 21 consecutive inoperable CTEPH patients before and 6 months after BPA. T1 values were measured within the septal myocardium, the upper and lower right ventricular insertion points, and the lateral wall at the basal short-axis section. In addition, the area-adjusted septal native T1 time (AA-T1) was calculated and compared with right ventricular function (RVEF), mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR). RESULTS: The mean AA-T1 value decreased significantly after BPA (1,045.8 ± 44.3 ms to 1,012.5 ± 50.4 ms; p < 0.001). Before BPA, native T1 values showed a moderate negative correlation with RVEF (r = -0.61; p = 0.0036) and moderate positive correlations with mPAP (r = 0.59; p < 0.01) and PVR (r = 0.53; p < 0.05); after BPA correlation trends were present (r = -0.21, r = 0.30 and r = 0.35, respectively). CONCLUSIONS: Native T1 values in patients with inoperable CTEPH were significantly lower after BPA and showed significant correlations with RVEF and pulmonary haemodynamics before BPA. Native T1 mapping seems to be indicative of reverse myocardial tissue remodelling after BPA and might therefore have good potential for pre-procedural patient selection, non-invasive therapy monitoring and establishing a prognosis. KEY POINTS: • BPA is a promising treatment option for patients with inoperable CTEPH • Native septal T1 values significantly decrease after BPA and show good correlations with right ventricular function and haemodynamics before BPA • Prognosis and non-invasive therapy monitoring might be supported in the future by native T1 mapping.


Assuntos
Angioplastia com Balão , Hemodinâmica , Hipertensão Pulmonar/diagnóstico por imagem , Hipertensão Pulmonar/terapia , Imageamento por Ressonância Magnética , Função Ventricular Direita , Idoso , Cateterismo Cardíaco , Doença Crônica , Feminino , Coração/diagnóstico por imagem , Coração/fisiopatologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Humanos , Hipertensão Pulmonar/complicações , Hipertensão Pulmonar/fisiopatologia , Masculino , Pessoa de Meia-Idade , Embolia Pulmonar/complicações , Embolia Pulmonar/diagnóstico por imagem , Embolia Pulmonar/fisiopatologia
4.
Clin Radiol ; 73(5): 502.e1-502.e8, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29329731

RESUMO

AIM: To evaluate the incidence, risk factors, and prognostic implications of contrast medium-induced acute kidney injury (CI-AKI) in patients undergoing transcatheter aortic valve implantation (TAVI) evaluation. MATERIALS AND METHODS: Datasets from 98 out of 207 consecutive patients referred for multidetector computed tomography (MDCT) for TAVI evaluation were eligible for evaluation and were analysed retrospectively. The incidence of CI-AKI was correlated to outcome and to potential risk factors: kidney function (estimated glomerular filtration rate [eGFR]), heart failure, diabetes, amount of contrast medium, and duration of examination period. RESULTS: CI-AKI occurred in 67 patients (68.4%) and mainly correlated with eGFR (p=0.01) and the amount of contrast medium as a function of eGFR (p=0.04). CI-AKI occurred before TAVI in 36 (53.7%) patients of which 13 (19.4%) did not undergo TAVI. In-hospital all-cause mortality was 21.4%, and of those 21 patients, 18 (85.7%) had CI-AKI and nine (42.9%) did not undergo TAVI. One-year all-cause mortality was 39.8%, and of those 39 patients who died within 1 year, 31 (79.5%) had CI-AKI. CONCLUSION: CI-AKI mostly occurs already before TAVI as a consequence of pre-procedural imaging, which therefore represents the main contributor for CI-AKI in relation to TAVI. Regarding the observation that some patients will ultimately have no benefit because TAVI is not performed and the poor prognosis linked to CI-AKI should encourage improvement in patient selection when referring to pre-procedural imaging.


Assuntos
Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/cirurgia , Meios de Contraste/efeitos adversos , Nefropatias/induzido quimicamente , Imagem Multimodal , Substituição da Valva Aórtica Transcateter , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Testes de Função Renal , Masculino , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Resultado do Tratamento
5.
Radiologe ; 58(1): 3-9, 2018 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-29234820

RESUMO

Mesenchymal tumors in childhood comprise benign and malign entities and differ regarding typical sites of manifestation, age peak and clinical symptoms. In some cases biopsy is mandatory. If nephroblastoma is a possible diagnosis, biopsy must be avoided by all means in order to avoid biopsy tract metastasis. Imaging is used to narrow the differential diagnosis, describe the exact extent of the lesion and deliver complete staging. In pediatric patients sonography and MRI are the most important imaging modalities. Low-dose CT of the thorax serves for assessment of possible pulmonary metastases.


Assuntos
Neoplasias Abdominais , Mesenquimoma , Criança , Diagnóstico Diferencial , Humanos , Neoplasias Pulmonares , Imageamento por Ressonância Magnética , Tórax
6.
Orthopade ; 47(1): 39-51, 2018 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-29238859

RESUMO

BACKGROUND: The reconstruction of bony defects during endoprosthesis revision surgery using "impaction bone grafting" leads to the possibility of a longstanding osseous integration to achieve good clinical results. Native allogeneic cancellous bone is often used for the procedure. This study examines the influence of thermodisinfection on the impaction behaviour of cancellous bone of different geometries and on the cement distribution. METHODS: The cancellous bone was obtained from the femoral heads of 7­month old pigs. One half of the head was thermodisinfected while the other remained native. Bone chips with sizes of 3-5, 5-8 and 8-10 mm were produced. The impaction was performed in a cylinder model with an internal diameter of 30 mm and with standardized impaction force using an impactor with a weight of 1450 g. The best particle combination was used for the subsequent computer tomography examination of the cement distribution and the contact surface to the bone in different parts of the shaft in seven investigations. For statistic measurements two-dimensional variance analysis including repetitions of measurement and Bonferroni correction, the LSD post-hoc-zest and the Mann Whitney U Test were used. The error probability was set at α = 5%. The SPSS® for Windows software was used for the statistical analysis. RESULTS: The distribution of the cancellous and compacted bone also along the shaft revealed no significant difference between thermodisinfected and native cancellous bone at different levels (p > 0.05). Impacted native cancellous bone showed less inclusion of air, which resulted in a better distribution of density compared with thermodisinfected bone overall (p < 0.001). In the distal shaft area the cement volume was significantly larger in conjunction with the native bone. The overall area of cement penetration appeared to be significantly larger for native cancellous bone (p < 0.001). CONCLUSIONS: The impaction of thermodisinfected and native cancellous bone showed greater deformation of the processed bone without any significant difference in the maximum density reached at different levels. Cement volume and cement penetration were pronounced proximally in native and processed cancellous bone. The cement distribution was significantly more distal for the native bone. Distally, the stabilization of the shaft appears to be increasingly dependent on the density of the impacted spongiosa, while proximally, the penetration of the cement into cancellous bone seems to correlate with porosity.


Assuntos
Antibacterianos/administração & dosagem , Transplante Ósseo/métodos , Portadores de Fármacos , Procedimentos Ortopédicos/métodos , Osteomielite/tratamento farmacológico , Procedimentos de Cirurgia Plástica/métodos , Antibacterianos/efeitos adversos , Transplante Ósseo/efeitos adversos , Portadores de Fármacos/efeitos adversos , Seguimentos , Infecções Relacionadas à Prótese/cirurgia , Reoperação
7.
Anaesthesist ; 66(3): 211-226, 2017 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-28204834

RESUMO

Pulmonary embolism is a potentially fatal disorder and frequently seen in critical care and emergency medicine. Due to a high mortality rate within the first few hours, the accurate initiation of rational diagnostic pathways in patients with suspected pulmonary embolism and timely consecutive treatment is essential. In this review, the current European guidelines on the diagnosis and therapy of acute pulmonary embolism are presented. Special focus is put on a structured patient management based on the individual risk of early mortality. In particular risk assessment and new risk-adjusted treatment recommendations are presented and discussed in this article.


Assuntos
Embolia Pulmonar/terapia , Guias como Assunto , Humanos , Embolia Pulmonar/diagnóstico , Medição de Risco
8.
Clin Radiol ; 71(3): 179-94, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26703119

RESUMO

Endometriosis is a common cause of chronic pelvic pain and infertility. It is defined as the occurrence of endometrial tissue outside the uterine cavity and can manifest as a peritoneal, ovarian or infiltrating form, the latter being referred to as deep infiltrating endometriosis (DIE). Surgery is essential in the treatment of DIE and depending on the severity of the disease, surgery can be difficult and extensive. Beside clinical examination and ultrasound, magnetic resonance imaging (MRI) has proven its value to provide useful information for planning surgery in patients with suspected DIE. To optimise the quality of MRI examinations, radiologists have to be familiar with the capabilities and also the limitations of this technique with respect to the assessment of DIE. MRI yields morphological information by using mainly T1- and T2-weighted sequences, but can also provide functional information by means of intravenous gadolinium, diffusion-weighted imaging or cine-MRI. In this article, these techniques and also adequate measures of patient preparation, which are indispensable for successful MRI imaging for the preoperative evaluation of DIE, are reviewed and a comprehensive protocol recommendation is provided.


Assuntos
Endometriose/patologia , Imageamento por Ressonância Magnética/métodos , Protocolos Clínicos , Meios de Contraste , Endometriose/cirurgia , Feminino , Humanos , Cuidados Pré-Operatórios
9.
Radiologe ; 56(8): 717-34, 2016 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-27369549

RESUMO

Signs in chest imaging are defined as typical findings which can be easily recognized on x­ray photographs or computed tomography (CT) scans of the chest. They are caused by different typical pathophysiological processes. Due to the association of a certain pathophysiological cause with a given sign, knowledge and use of these signs can allow the possible differential diagnoses to be narrowed down. If other imaging findings and clinical data are additionally taken into account, the diagnosis can be made with a high degree of confidence in many cases.


Assuntos
Intensificação de Imagem Radiográfica/métodos , Radiografia Torácica/métodos , Doenças Torácicas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Diagnóstico Diferencial , Medicina Baseada em Evidências , Humanos
10.
Radiologe ; 56(12): 1061-1068, 2016 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-27882402

RESUMO

The IgG4-associated diseases of connective tissue are caused by allergen-mediated autoimmune processes. The retroperitoneum, mesentery and mediastinum as well as other less common localizations, such as the neck, orbit and periarticular connective tissue can be affected. Inflammatory fibrosis is initially dominated by a lymphocytic and plasma cell-rich infiltrate and later by cell-poor storiform fibrosis. Stenosis and occlusion of vessels, ureters and intestines can cause severe complications. Computed tomography (CT) and magnetic resonance imaging (MRI) can be implemented in the diagnostic algorithm to narrow the differential diagnosis, delineate the distribution of fibrosis and reveal complications.


Assuntos
Doenças Autoimunes/diagnóstico por imagem , Doenças do Tecido Conjuntivo/diagnóstico por imagem , Imunoglobulina G/imunologia , Imageamento por Ressonância Magnética/métodos , Tomografia Computadorizada por Raios X/métodos , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Doenças do Tecido Conjuntivo/imunologia , Doenças do Tecido Conjuntivo/patologia , Diagnóstico Diferencial , Medicina Baseada em Evidências , Humanos
11.
Anaesthesist ; 65(2): 122-8, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26661080

RESUMO

BACKGROUND: Critically ill patients in intensive-care units are at high risk for pulmonary embolism (PE). As a result of modern multi-detector computed tomographic angiography (MDCT) increased visualization of peripheral pulmonary arteries, isolated subsegmental pulmonary embolisms (ISSPE) are increasingly being detected. AIM: The aim of this study was to investigate the rate, impact on treatment, and outcome of unsuspected ISSPE in critically ill patients receiving MDCT. The secondary aim was to investigate the potential impact of contrast media-induced nephropathy (CIN) in our cohort. METHODS: We conducted a retrospective single-centre analysis on critically ill adult patients treated between January 2009 and December 2012 who underwent a contrast-enhanced chest MDCT. We excluded patients with clinical suspicion of PE/ISSPE prior to CT and patients with MDCT confirmed central PE. Clinical findings, laboratory parameters, and outcome data were recorded. RESULTS: We identified 240 ICU patients not suspected for PE receiving MDCT. A total of 12 Patients (5%) showed unexpected ISSPE representing increased 24 h mortality (16.7 vs. 3.5%; p = 0.026) compared to non-ISPPE/non-PE patients. A 30-days mortality did not differ between the groups (33.3 vs. 33.8%; p = 0.53). Highest mean creatinine serum level in our cohort (n = 240) was found before MDCT with a significant decrease to day 5 (1.4 ± 1.1 vs. 1.1 ± 0.9 mg/dl: p < 0.0001) after contrast media administration. CONCLUSION: Critically ill patients are at relevant risk for ISSPE. ISSPE was associated with a poor 24 h outcome. In addition, in our cohort, contrast media application was not associated with increased serum creatinine.


Assuntos
Cuidados Críticos/métodos , Embolia Pulmonar/terapia , Adulto , Idoso , Angiografia , Estudos de Coortes , Meios de Contraste/efeitos adversos , Feminino , Humanos , Unidades de Terapia Intensiva , Nefropatias/induzido quimicamente , Nefropatias/epidemiologia , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Assistência Perioperatória , Embolia Pulmonar/diagnóstico por imagem , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Resultado do Tratamento
12.
HNO ; 63(5): 373-5, 2015 May.
Artigo em Alemão | MEDLINE | ID: mdl-24292222

RESUMO

We report on a 19-year-old patient who developed negative pressure pulmonary edema (NPPE) with respiratory insufficiency following abscess tonsillectomy. NPPE is an unpredictable and life-threatening postoperative complication characterized by respiratory insufficiency. It may arise immediately after extubation or later in the postoperative period. NPPE is frequently observed after laryngospasm or in combination with space-occupying lesions in the pharynx and larynx. Treatment comprises the immediate correction of hypoxemia, preferably by noninvasive respiratory support using continuous positive airway pressure (CPAP), although in some cases reintubation is necessary.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas , Abscesso Peritonsilar/complicações , Abscesso Peritonsilar/cirurgia , Edema Pulmonar/etiologia , Edema Pulmonar/terapia , Tonsilectomia/efeitos adversos , Humanos , Masculino , Edema Pulmonar/diagnóstico , Resultado do Tratamento , Adulto Jovem
13.
Radiologe ; 54(6): 589-98, 2014 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-24844855

RESUMO

CLINICAL/METHODICAL ISSUE: Cost-intensive measures and procedures, such as also employed in radiology, have far-reaching economic implications in respect to increasing expenditure with limited resources. STANDARD RADIOLOGICAL METHODS: Health technology assessment (HTA) describes the systematic evaluation of medical procedures and technologies which in recent years has been introduced by many countries into healthcare politics. ASSESSMENT: In many cases HTA analyses can be directly implemented into practice as shown by the examples given in this article; however, in the current form of HTA the practical implementation for radiology often presents the problem that the cost-benefit ratio does not yet have a comprehensive view in the HTA report but is limited to a subsection, e.g. current costs versus sensitivity of a method. Since its inception radiology has had a high power of innovation and new developments will also substantially determine the future years. These procedures must not only be evaluated with respect to feasibility but also in the sense of the HTA in the total concept. PRACTICAL RECOMMENDATIONS: In radiology there are also a large number of possibilities for radiologists not only as passive consumers of HTA reports but also to become active participants in this process, an opportunity which should be taken advantage of.


Assuntos
Tecnologia Biomédica/economia , Análise Custo-Benefício/métodos , Custos de Cuidados de Saúde , Modelos Econômicos , Radiologia/economia , Avaliação da Tecnologia Biomédica/economia , Avaliação da Tecnologia Biomédica/métodos , Alemanha
14.
Anaesthesist ; 63(3): 253-63, 2014 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-24577182

RESUMO

Acute pancreatitis is a potentially fatal disease with individually differing expression of systemic involvement. For this reason early diagnosis with subsequent risk stratification is essential in the clinical management of this frequent gastroenterological disorder. Severe forms of acute pancreatitis occur in approximately 20 % of cases often requiring intensive care monitoring and interdisciplinary therapeutic approaches. In the acute phase adequate fluid replacement and sufficient analgesic therapy is of major therapeutic importance. Concerning the administration of antibiotics and the nutritional support of patients with acute pancreatitis a change in paradigms could be observed in recent years. Furthermore, endoscopic, radiological or surgical interventions can be necessary depending on the severity of the disease and potential complications.


Assuntos
Pancreatite/terapia , Doença Aguda , Analgésicos/uso terapêutico , Antibacterianos/uso terapêutico , Colangiopancreatografia Retrógrada Endoscópica , Colecistectomia , Endoscopia , Nutrição Enteral , Hidratação , Humanos , Apoio Nutricional , Dor/etiologia , Manejo da Dor , Pancreatite/complicações , Pancreatite/diagnóstico , Pancreatite/cirurgia , Pancreatite Necrosante Aguda/complicações , Pancreatite Necrosante Aguda/diagnóstico , Pancreatite Necrosante Aguda/cirurgia , Pancreatite Necrosante Aguda/terapia
15.
Klin Padiatr ; 224(7): 448-52, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23070864

RESUMO

Pediatric scurvy is a rare condition characterized by perifollicular petechiae and bruising, hemorrhagic gingivitis and musculoskeletal symptoms, all assumed to be predominantly related to abnormal collagen structure. We report on a 9-year-old autistic boy with vitamin C deficiency due to a highly limited food range presenting with multiple petechiae, gum bleeding and debilitating bone pain, in whom platelet aggregometry revealed a distinctly reduced thrombocyte aggregation, normalizing after vitamin C supplementation. This observation indicates that platelet dysfunction may additionally contribute to the hemorrhagic diathesis in scurvy, and demonstrates that ascorbic acid deficiency should be considered in children with an otherwise unexplained acquired thrombocytopathy.


Assuntos
Agregação Plaquetária/fisiologia , Escorbuto/sangue , Transtorno Autístico/sangue , Transtorno Autístico/complicações , Paralisia Cerebral/sangue , Paralisia Cerebral/complicações , Criança , Contusões/sangue , Contusões/etiologia , Deficiências do Desenvolvimento/sangue , Deficiências do Desenvolvimento/complicações , Diagnóstico Diferencial , Hemorragia Gengival/sangue , Hemorragia Gengival/etiologia , Hematoma/sangue , Hematoma/etiologia , Humanos , Masculino , Agregação Plaquetária/efeitos dos fármacos , Púrpura/sangue , Púrpura/etiologia , Escorbuto/diagnóstico , Escorbuto/tratamento farmacológico
16.
Eur J Nucl Med Mol Imaging ; 38(1): 138-52, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20922522

RESUMO

PURPOSE: The combination of positron emission tomography (PET) and magnetic resonance (MR) tomography in a single device is anticipated to be the next step following PET/CT for future molecular imaging application. Compared to CT, the main advantages of MR are versatile soft tissue contrast and its capability to acquire functional information without ionizing radiation. However, MR is not capable of measuring a physical quantity that would allow a direct derivation of the attenuation values for high-energy photons. METHODS: To overcome this problem, we propose a fully automated approach that uses a dedicated T1-weighted MR sequence in combination with a customized image processing technique to derive attenuation maps for whole-body PET. The algorithm automatically identifies the outer contour of the body and the lungs using region-growing techniques in combination with an intensity analysis for automatic threshold estimation. No user interaction is required to generate the attenuation map. RESULTS: The accuracy of the proposed MR-based attenuation correction (AC) approach was evaluated in a clinical study using whole-body PET/CT and MR images of the same patients (n = 15). The segmentation of the body and lung contour (L-R directions) was evaluated via a four-point scale in comparison to the original MR image (mean values >3.8). PET images were reconstructed using elastically registered MR-based and CT-based (segmented and non-segmented) attenuation maps. The MR-based AC showed similar behaviour as CT-based AC and similar accuracy as offered by segmented CT-based AC. Standardized uptake value (SUV) comparisons with reference to CT-based AC using predefined attenuation coefficients showed the largest difference for bone lesions (mean value ± standard variation of SUV(max): -3.0% ± 3.9% for MR; -6.5% ± 4.1% for segmented CT). A blind comparison of PET images corrected with segmented MR-based, CT-based and segmented CT-based AC afforded identical lesion detectability, but slight differences in image quality were found. CONCLUSION: Our MR-based attenuation correction method offers similar correction accuracy as offered by segmented CT. According to the specialists involved in the blind study, these differences do not affect the diagnostic value of the PET images.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Tomografia por Emissão de Pósitrons/métodos , Imagem Corporal Total/métodos , Adulto , Idoso , Automação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
17.
J Orthop ; 22: 414-421, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33029046

RESUMO

INTRODUCTION: Morphology and mechanic properties of impacted cancellous bone are affected by carrier substances which provide high local concentrations of antibiotics. METHODS: Bone chips were taken from the femoral head of 6-7 months old piglets. One half was thermodisinfected and the other remained native. Ten specimens each were mixed with Herafill® antibiotic pellets and a control group of each 10 specimens respectively was examined. The cancellous bone was impacted according to Exeter technique and the implants were cemented. The distribution of the particles and the pores were defined with three dimensional computertomographic scan and shear force resistance was measured until failure. RESULTS: Shear force resistance was not measured significantly less for thermodisinfected (2.7 Nm) compared with native bone (3.5 Nm) and addition of antibiotic pellets reduced shear force resistance in both groups since this was significant for the native group. The average pore volume of the native bone specimens appeared significant smaller compared to the thermodisinfected group (p = 0.011) and the pore volume showed a negative correlation with shear force resistance (p = 0.044). Pore volume around the pellets was found significantly increased and it appeared smaller for native bone. The number of pellets located next to the implant showed a negative correlation with shear force resistance (p = 0.034) and the negative correlation increased for pellets below the tip of the shaft model (p = 0.024). CONCLUSION: Adding antibiotic pellets to native and thermodisinfected impacted cancellous bone increased pore volume since the area around the pellets showed increased porosity which correlated with reduced shear force resistance. Computertomographic three dimensional measurement of porosity might predict shear force resistance of impacted cancellous bone and improve impaction of bone grafting intraoperatively.

18.
Rofo ; 180(5): 402-9, 2008 May.
Artigo em Alemão | MEDLINE | ID: mdl-18438742

RESUMO

PURPOSE: To compare highly accelerated parallel MRI of the bowel with conventional balanced FFE sequences in children with inflammatory bowel disease (IBD). MATERIALS AND METHODS: 20 children with suspected or proven IBD underwent MRI using a 1.5 T scanner after oral administration of 700 -1000 ml of a Mannitol solution and an additional enema. The examination started with a 4-channel receiver coil and a conventional balanced FFE sequence in axial (2.5 s/slice) and coronal (4.7 s/slice) planes. Afterwards highly accelerated (R = 5) balanced FFE sequences in axial (0.5 s/slice) and coronal (0.9 s/slice) were performed using a 32-channel receiver coil and parallel imaging (SENSE). Both receiver coils achieved a resolution of 0.88 x 0.88 mm with a slice thickness of 5 mm (coronal) and 6 mm (axial) respectively. Using the conventional imaging technique, 4 - 8 breathholds were needed to cover the whole abdomen, while parallel imaging shortened the acquisition time down to a single breathhold. Two blinded radiologists did a consensus reading of the images regarding pathological findings, image quality, susceptibility to artifacts and bowel distension. The results for both coil systems were compared using the kappa-(kappa)-coefficient, differences in the susceptibility to artifacts were checked with the Wilcoxon signed rank test. Statistical significance was assumed for p = 0.05. RESULTS: 13 of the 20 children had inflammatory bowel wall changes at the time of the examination, which could be correctly diagnosed with both coil systems in 12 of 13 cases (92 %). The comparison of both coil systems showed a good agreement for pathological findings (kappa = 0.74 - 1.0) and the image quality. Using parallel imaging significantly more artifacts could be observed (kappa = 0.47) without impairing the diagnostic impact. The comparison of the bowel distension showed no significant differences. CONCLUSION: The highly accelerated parallel MRI using the SENSE technique and a 32-channel surface coil enables the examination of the entire bowel in a single breathhold without relevant restrictions in image quality and diagnostic impact.


Assuntos
Processamento de Imagem Assistida por Computador/instrumentação , Doenças Inflamatórias Intestinais/diagnóstico , Imageamento por Ressonância Magnética/instrumentação , Respiração , Administração Oral , Adolescente , Adulto , Artefatos , Criança , Pré-Escolar , Meios de Contraste/administração & dosagem , Enema , Feminino , Humanos , Intestinos/patologia , Masculino , Manitol , Sensibilidade e Especificidade , Estudos de Tempo e Movimento
19.
Acta Otorhinolaryngol Ital ; 28(2): 79-82, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18669072

RESUMO

Isolated congenital malformations of semicircular canals are rare abnormalities. Most inner ear abnormalities occur in syndromes and are associated with hearing loss. Unilateral or bilateral single aplasia of one semicircular canal does not usually result in vertigo, but these become clinically important if there are clinical complaints of vertigo. Computed tomography imaging and high resolution magnetic resonance imaging may reveal inner ear abnormalities. The case is presented here of a 46-year-old male with a 10-year history of recurrent positional vertigo with strong onset when changing position to the left side. Magnetic resonance imaging of the inner ear showed a bilateral posterior semicircular canal aplasia as well as an enlarged vestibule on both sides. Dix-Hallpike positional manoeuvre revealed a positional nystagmus in the left head-hanging position of short duration and latency of a few seconds. When rising, vertigo occurred, but no nystagmus was visible. The fast phase of the nystagmus was mainly vertical down-beating with a slight torsional component to the uppermost ear. Although benign paroxysmal vertigo of the anterior canal was suspected, physical therapy was not effective using a modified liberatory manoeuvre. Brandt-Daroff therapy was effective permanently.


Assuntos
Canais Semicirculares/fisiopatologia , Vertigem/diagnóstico , Vertigem/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Canais Semicirculares/diagnóstico por imagem , Canais Semicirculares/patologia , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X
20.
Rofo ; 179(6): 566-71, 2007 Jun.
Artigo em Alemão | MEDLINE | ID: mdl-17377873

RESUMO

PURPOSE: To investigate the potential of ECG-triggered MRI for the evaluation of postoperative anatomy and function of the heart and conduit following implantation of a left-ventricular apico-aortic conduit. MATERIALS AND METHODS: 5 patients (2 female, 3 male, mean age 72.5 years) were examined using a 1.5 Tesla whole-body MRI (Gyroscan Intera, Philips Medical Systems, Best, The Netherlands) following apico-aortic conduit surgery due to severe aortic valve stenosis. The reason for performing conduit implantation instead of aortic valve replacement was the risk of injuring a bypass graft from prior coronary artery bypass surgery. Cine steady-state-free-precession (SSFP) sequences were used to assess ventricular function, navigator-gated 3D-SSFP and breath-hold, time-resolved contrast-enhanced MR angiography was used to display the postoperative anatomy, and 2D-gradient echo sequences with an inversion pulse to suppress the signal of the healthy myocardium were used to evaluate potential myocardial scarring. Flow sensitive gradient echo sequences were performed to determine the blood flow in the conduit. RESULTS: In all patients the apico-aortic conduit proved to be open with a maximum flow velocity of 126 (+ 43) cm/s. The postoperative anatomy was able to be evaluated in all patients and perioperative myocardial infarction was able to be ruled out. The mean ejection fraction of the left ventricle was 44.2 + 6.2 % with a mean volume of 80 + 20.6 ml per heart beat. CONCLUSION: ECG-triggered MRI is a reliable method for the evaluation of postoperative anatomy and function following implantation of a left ventricular apico-aortic conduit.


Assuntos
Estenose da Valva Aórtica/cirurgia , Valva Aórtica , Implante de Prótese Vascular/métodos , Prótese Vascular , Miocárdio/patologia , Função Ventricular Esquerda , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Infarto do Miocárdio/patologia , Remodelação Ventricular
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