RESUMO
BACKGROUND: The characterization of brain arteriovenous malformation (AVM) angioarchitecture remains rewarding in planning and predicting therapy. The increased signal-to-noise ratio at higher field strength has been found advantageous in vascular brain pathologies. PURPOSE: To evaluate whether 3.0T time-of-flight (TOF) magnetic resonance angiography (MRA) is superior to 1.5T TOF-MRA for the characterization of cerebral AVMs. MATERIAL AND METHODS: Fifteen patients with AVM underwent TOF-MRA at 3.0T and 1.5T and catheter angiography (DSA), which was used as the gold standard. Blinded readers scored image quality on a four-point scale, nidus size, and number of feeding arteries and draining veins. RESULTS: Image quality of TOF-MRA at 3.0T was superior to 1.5T but still inferior to DSA. Evaluation of nidus size was equally good at 3.0T and 1.5T for all AVMs. In small AVMs, however, there was a tendency of size overestimation at 3.0T. MRA at 3.0T had increased detection rates for feeding arteries (+21%) and superficial (+13%) and deep draining veins (+33%) over 1.5T MRA. CONCLUSION: 3.0T TOF-MRA offers superior characterization of AVM angioarchitecture compared with 1.5T TOF-MRA. The image quality of MRA at both 3.0 and 1.5T is still far from equal to DSA, which remains the gold standard for characterization of AVM.
Assuntos
Imageamento Tridimensional/métodos , Malformações Arteriovenosas Intracranianas/diagnóstico , Angiografia por Ressonância Magnética/métodos , Adulto , Angiografia Digital/métodos , Meios de Contraste/administração & dosagem , Feminino , Gadolínio DTPA , Humanos , Aumento da Imagem/métodos , Angiografia por Ressonância Magnética/instrumentação , Magnetismo , Masculino , Pessoa de Meia-Idade , Variações Dependentes do ObservadorRESUMO
BACKGROUND AND PURPOSE: Intracerebral hemorrhages after embolization of arteriovenous malformations (AVMs) are the most dreaded complications of this well-established therapy. Apart from the known risk factors, our center noticed a high incidence of complications during postinterventional monitoring in medical intensive care units (ICUs) and stroke units. MATERIALS AND METHODS: We report 125 consecutive interventions performed on 66 patients by using flow-dependent microcatheters and n-butyl cyanoacrylate as the embolic agent. Postinterventional intensive care monitoring was performed in an interdisciplinary operative ICU, a stroke unit, or a medical ICU. Patients were compared with regard to bleeding complications, AVM morphology, embolization result, postinterventional monitoring, and demographic factors. RESULTS: Intracerebral hemorrhages occurred in 7 patients. Significant differences in outcome were found between 66 patients monitored in the interdisciplinary operative ICU from medical ICU or stroke unit. This was also true when adjusted for age and extent of AVM reduction by using exact logistic regression. A partial AVM reduction of >60% was a considerable risk factor for hemorrhage (odds ratio [OR] = 18.8; 95% confidence interval [CI] [1.341, not available]. Age was also an essential risk factor. An age difference of 10 years leads to an OR of 2.545 (95% CI [1.56, 7.35]). DISCUSSION: A considerable AVM reduction in one session appears to increase the risk of hemorrhage technically. This suggests a distribution of the interventions in many partial steps.
Assuntos
Angiografia Cerebral , Hemorragia Cerebral/diagnóstico por imagem , Embolização Terapêutica , Malformações Arteriovenosas Intracranianas/terapia , Tomografia Computadorizada por Raios X , Adolescente , Adulto , Idoso , Criança , Cuidados Críticos , Feminino , Humanos , Malformações Arteriovenosas Intracranianas/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Equipe de Assistência ao Paciente , Retratamento , Estudos Retrospectivos , Fatores de RiscoRESUMO
Recent technical developments led to a change in the significance of the different imaging modalities in the whole spectrum of neuroradiology and thus also in the field of imaging of the cervical spine. The main part in diagnostic imaging of the upper cervical spine is taken by high-resolution multislice CT and MRI. Conventional X-rays serve as an initial screening technique if required.
Assuntos
Vértebras Cervicais , Imageamento por Ressonância Magnética , Doenças da Coluna Vertebral/diagnóstico , Fraturas da Coluna Vertebral/diagnóstico , Tomografia Computadorizada por Raios X , Angiografia , Articulação Atlantoaxial , Vértebras Cervicais/anormalidades , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/lesões , Cordoma/diagnóstico , Cordoma/diagnóstico por imagem , Diagnóstico Diferencial , Humanos , Mielografia , Sensibilidade e Especificidade , Doenças da Medula Espinal/diagnóstico , Doenças da Medula Espinal/diagnóstico por imagem , Doenças da Coluna Vertebral/diagnóstico por imagem , Disrafismo Espinal/diagnóstico , Fraturas da Coluna Vertebral/diagnóstico por imagem , Neoplasias da Coluna Vertebral/diagnóstico , Neoplasias da Coluna Vertebral/diagnóstico por imagem , Tomografia Computadorizada Espiral , Artéria Vertebral/diagnóstico por imagemRESUMO
PURPOSE: Comparison of metric analysis of spinal structures, exemplarily of the ligamentum flavum, obtained with computed tomography (CT) (soft tissue window and bone window) and magnetic resonance imaging (MRI) (T1 and T2 weighted images). MATERIAL AND METHODS: Forty-six lumbar ligamenta flava of 46 patients (25 women and 21 men) were examined at a Somatom Plus 4 (Siemens, Erlangen, FRG) and at a 1.5 T clinical scanner (Magnetom Vision, Siemens, Erlangen, FRG). Two independent neuroradiologists measured the thickness of the ligamenta flava in mm. Statistics included Pearson's correlation coefficient and the intra-class correlation coefficient. RESULTS: Mean values did not differ significantly. The correlation coefficients varied between 0.69 and 0.98. The best correlation occurred comparing the same techniques in different windowing and weighting (CT: r = 0.98; MRI: r = 0.95). Correlating different techniques the combination of CT bone window and T1 weighted images presented the best result (r = 0.75). CONCLUSIONS: Because of the excellent correlation between the examined techniques CT as well as MRI can equally be used to measure distances of spinal structures.
Assuntos
Ligamento Amarelo/patologia , Vértebras Lombares/patologia , Imageamento por Ressonância Magnética , Tomografia Computadorizada por Raios X , Pesos e Medidas Corporais , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Deslocamento do Disco Intervertebral/diagnóstico por imagem , Deslocamento do Disco Intervertebral/patologia , Deslocamento do Disco Intervertebral/cirurgia , Ligamento Amarelo/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/estatística & dados numéricos , Masculino , Estudos Retrospectivos , Estenose Espinal/diagnóstico por imagem , Estenose Espinal/patologia , Estenose Espinal/cirurgia , Tomografia Computadorizada por Raios X/métodos , Tomografia Computadorizada por Raios X/estatística & dados numéricosRESUMO
PURPOSE: To evaluate whether metabolic changes of the erector trunci muscle in patients with lumbar disc herniation can be detected with proton magnetic resonance spectroscopy ( (1)H-MRS). MATERIALS AND METHODS: In 10 patients with lumbar disc herniation and 16 healthy volunteers, proton spectra were obtained from the erector trunci muscle and analyzed for fat-water ratio. The axial images were evaluated for the degree of atrophy of the erector trunci muscle. The muscular tissue was histopathologically examined in 2 patients. RESULTS: The examination was well tolerated by all patients and volunteers and all acquired spectra could be analyzed. Patients with lumbar disc herniation have a significantly increased fat-water ratio of 0.19 compared to 0.09 in the control group, with a p-value of 0.003. This result correlates well with the bioptical findings of increased intracellular lipid deposits and lipomatous transformation of the muscle parenchyma. CONCLUSION: (1)H-MRS is a useful method to detect metabolic changes in lumbar back musculature and, as a non-invasive technique, might play a role in monitoring exercise in lumbar disc herniation. It can be expected that muscle regeneration will be shown as precisely as muscle degeneration. This hypothesis, however, remains to be proven.
Assuntos
Deslocamento do Disco Intervertebral/diagnóstico , Deslocamento do Disco Intervertebral/metabolismo , Vértebras Lombares , Espectroscopia de Ressonância Magnética , Músculo Esquelético/metabolismo , Adulto , Água Corporal/metabolismo , Gorduras/metabolismo , Feminino , Humanos , Deslocamento do Disco Intervertebral/complicações , Masculino , Atrofia Muscular/diagnóstico , Atrofia Muscular/etiologia , Atrofia Muscular/metabolismo , Prótons , Ciática/etiologia , Ciática/metabolismoRESUMO
Signal changes in activated brain areas are detectable by MRI and MR spectroscopy (MRS). Shifts in pH occur during brain activation. Our aim was to investigate the relationship between changes in pH and T2 relaxation times. T2 was determined in vitro at 24 MHz in various liquids at different pH using a Carr-Purcell-Meiboom-Gill (CPMG) spin-echo sequence. We also studied five Fisher rats were studied at 2.4 tesla with a double-tuneable surface coil. After baseline measurements, potassium cyanide was injected, producing intracerebral acidosis. Alternating series of 1H CPMG spin-echo sequences and 31P spectra were acquired. True T2 relaxation times were calculated from a CPMG multi-echo train. Changes in intracellular pH determined from 31P spectra. In vitro measurements demonstrated a correlation between T2 and pH that could be described by a quadratic fit curve. Depending on the initial pH, changes of 0.2 induced changes in T2 of up to 150 ms. In vivo measurements confirmed these findings. After intraperitoneal injection of a sublethal dose of cyanide, T2 decreased by about 5% in four cases, followed by recovery after 2 h. The in vitro measurements demonstrated that changes in pH can lead to significant signal change on T2- or T2*- weighted images. The dependence of T2 on pH in vitro was confirmed in vivo; it may contribute to signal change in activated brain areas.
Assuntos
Encéfalo/metabolismo , Hipóxia-Isquemia Encefálica/líquido cefalorraquidiano , Animais , Gânglios da Base/metabolismo , Córtex Cerebral/metabolismo , Concentração de Íons de Hidrogênio , Hipóxia-Isquemia Encefálica/induzido quimicamente , Espectroscopia de Ressonância Magnética , Ratos , Cianeto de SódioRESUMO
Cynomolgus monkeys were anaesthetized with either intramuscular ketamine (10 mg/kg or intramuscular ketamine 2 mg/kg and medetomidine 50 microg/kg. Various physiological measurements were made once the animals were safe to handle and again 10 min later. Cardiovascular and respiratory function were well maintained with both regimens but the heart rate was lower and arterial-alveolar carbon dioxide gradient was higher in the animals that received medetomidine. In those animals that received medetomidine, atipamezole was given to reverse the medetomidine but there was no difference in recovery times between the two regimens. Anaesthesia was not entirely reliable with medetomidine/ketamine and we recommend caution when using this mixture.
Assuntos
Agonistas alfa-Adrenérgicos , Anestesia/veterinária , Anestésicos Combinados , Anestésicos Dissociativos , Ketamina , Macaca fascicularis/fisiologia , Medetomidina , Agonistas alfa-Adrenérgicos/administração & dosagem , Antagonistas Adrenérgicos alfa , Anestesia/métodos , Anestésicos Combinados/administração & dosagem , Anestésicos Dissociativos/administração & dosagem , Animais , Gasometria/veterinária , Pressão Sanguínea , Temperatura Corporal , Frequência Cardíaca , Imidazóis , Injeções Intramusculares/veterinária , Ketamina/administração & dosagem , Masculino , Medetomidina/administração & dosagem , Distribuição Aleatória , RespiraçãoRESUMO
PURPOSE: Conventional myelography involves side effects and complications due to puncture of CSF space and injection of contrast medium. On the other hand, MR-myelography (MRM) is a new noninvasive method requiring neither puncture nor contrast medium and causing no side effects. The diagnostic value and accuracy of MRM was evaluated in comparison with conventional myelography. MATERIALS AND METHODS: In this prospective comparative study, 41 patients (17 male, 24 female, mean age 42 years) with radicular symptoms underwent conventional lumbar myelography and were also submitted to MRM. Evaluation was performed in a blind manner by two independent examiners. RESULTS: The specificity and sensitivity of the methods are identical. MRM shows 35 cases of thecal indentation with amputation of a nerve root sheath and 6 cases of spinal stenosis. The results of conventional myelography and MRM were surgically confirmed in 38 patients. CONCLUSIONS: Both methods have the same diagnostic accuracy, but MRM requires neither puncture nor contrast medium nor x-rays.
Assuntos
Imageamento por Ressonância Magnética , Síndromes de Compressão Nervosa/diagnóstico , Raízes Nervosas Espinhais/patologia , Estenose Espinal/diagnóstico , Coluna Vertebral/patologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mielografia , Estudos Prospectivos , Sensibilidade e Especificidade , Método Simples-CegoRESUMO
Perfluorodecalin (PFD) was demonstrated in a human eye with fluorine-19 magnetic resonance (MR) imaging by employing a standard two-dimensional fast low-angle shot (FLASH) sequence. The presence and intraocular distribution of PFD were revealed despite the posterior eye segment being obscured by a narrow pupil, multiple small intraocular gas bubbles, and an intraocular hemorrhage. This examination can be performed with standard sequences on MR imaging systems equipped with a fluorine channel.
Assuntos
Olho/química , Flúor , Fluorocarbonos/química , Imageamento por Ressonância Magnética , Extração de Catarata , Criança , Feminino , Humanos , Período Pós-OperatórioRESUMO
We have developed an apparatus and techniques that permit repeated, undisturbed blood sampling and concurrent assessment of activity in rats. The apparatus also allows experimental control of conditioning stimuli and contingencies without the need to transfer the rat to a separate chamber. In the experimental apparatus, body weights remain stable at approximately 90% of the original body weight. Plasma corticosterone and prolactin levels in the apparatus are comparable to levels obtained in undisturbed free-ranging rats and remain at basal levels for the 7 day duration of this experiment. Additionally, circadian activity rhythms in the apparatus are similar to those seen in free-ranging rats. This technique has potential applications for investigators who need to be able to control shock delivery, monitor activity, and sample blood without disturbing rats.