RESUMO
BACKGROUND: Cochlea sparing can reduce late ototoxicity in head and neck cancer patients treated with cisplatin-based radiochemotherapy. In this situation, a mean cochlear dose (MCD) constraint of 10â¯Gy has been suggested by others based on the dose-effect relationship of clinical data. We aimed to investigate whether this is feasible for primary and postoperative radiochemotherapy in locoregionally advanced tumors without compromising target coverage. PATIENTS AND METHODS: Ten patients treated with definitive and ten patients treated with adjuvant intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy were investigated. The cochleae and a planning risk volume (PRV) with a 3â¯mm margin were newly delineated, whereas target volumes and other organs at risk were not changed. The initial plan was recalculated with a constraint of 10â¯Gy (MCD) on the low-risk side. The quality of the resulting plan was evaluated using the difference in the equivalent uniform dose (EUD). RESULTS: A unilateral MCD of below 10â¯Gy could be achieved in every patient. The mean MCD was 6.8â¯Gy in the adjuvant cohort and 7.6â¯Gy in the definitive cohort, while the non-spared side showed a mean MCD of 18.7 and 30.3â¯Gy, respectively. The mean PRV doses were 7.8 and 8.4â¯Gy for the spared side and 18.5 and 29.8â¯Gy for the non-spared side, respectively. The mean EUD values of the initial and recalculated plans were identical. Target volume was not compromised. CONCLUSION: Unilateral cochlea sparing with an MCD of less than 10â¯Gy is feasible without compromising the target volume or dose coverage in locoregionally advanced head and neck cancer patients treated with IMRT. A prospective evaluation of the clinical benefit of this approach as well as further investigation of the dose-response relationship for future treatment modification appears promising.
Assuntos
Quimiorradioterapia/efeitos adversos , Cisplatino/efeitos adversos , Cóclea/efeitos dos fármacos , Cóclea/efeitos da radiação , Tratamentos com Preservação do Órgão , Neoplasias Otorrinolaringológicas/terapia , Radioterapia de Intensidade Modulada/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Quimiorradioterapia Adjuvante/efeitos adversos , Cisplatino/uso terapêutico , Terapia Combinada , Estudos de Viabilidade , Feminino , Humanos , Masculino , Gradação de Tumores , Estadiamento de Neoplasias , Neoplasias Otorrinolaringológicas/patologia , Doses de Radiação , Planejamento da Radioterapia Assistida por ComputadorRESUMO
PURPOSE: The purpose of this work was to determine the efficacy of MR angiography (MRA) in the detection and characterization of occlusive disease in the vertebrobasilar system. METHOD: We retrospectively reviewed the posterior circulation registry of our institution to select 42 consecutive patients with posterior circulation ischemic symptoms who underwent both MRA and angiography. The extracranial vertebral arteries (ECVAs) were examined by two-dimensional time-of-flight MRA above the C6 level, and the intracranial vertebral arteries (ICVAs) and basilar arteries (BAs) were examined by three-dimensional time-of-flight MRA. Sixty-two ECVAs, 63 ICVAs, and 39 BAs were examined by the readers. RESULTS: Occlusive disease was seen on angiography in 22 of the 42 patients. The sensitivity and specificity values for detection of lesions in 12 ECVA, 19 ICVA, and 12 BA abnormalities were as follows: ECVA, 92 and 96% for Reader A and 100 and 90% for Reader B; ICVA, 84 and 93% for Reader A and 74 and 82% for Reader B; and BA, 100 and 88% for Reader A and 100 and 78% for Reader B. For ICVA, the sensitivity of MRA was less than that of angiography because of lesions missed by the readers at the junctional area of the extra-and intracranial MRA. MRA accurately characterized 9 of the 12 (75%) ECVA, 10 of the 19 (43%) ICVA, and 11 of the 12 (92%) BA lesions. CONCLUSION: MRA is an effective method for detection of occlusive lesions in the ECVAs and BAs. Clinically important lesions can be missed by MRA in the ICVA. MRA is more accurate in characterization of occlusive lesions in BAs than in ECVAs or ICVAs.
Assuntos
Arteriopatias Oclusivas/diagnóstico , Artéria Basilar , Angiografia por Ressonância Magnética , Artéria Vertebral , Idoso , Idoso de 80 Anos ou mais , Angiografia , Angiografia Digital , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Valor Preditivo dos Testes , Estudos Retrospectivos , Sensibilidade e EspecificidadeAssuntos
Meios de Contraste/história , Metrizamida/história , Medula Espinal/diagnóstico por imagem , Tomografia Computadorizada por Raios X/história , Meios de Contraste/administração & dosagem , História do Século XX , Humanos , Injeções Espinhais/história , Região Lombossacral , Metrizamida/administração & dosagem , Neurologia/históriaAssuntos
Malformação de Arnold-Chiari/diagnóstico , Imageamento por Ressonância Magnética , Siringomielia/diagnóstico , Malformação de Arnold-Chiari/fisiopatologia , Líquido Cefalorraquidiano/fisiologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Humanos , Fatores de Risco , Siringomielia/fisiopatologia , Sístole/fisiologiaAssuntos
Medicina , Neurorradiografia , Publicações Periódicas como Assunto , Editoração , Especialização , AutoriaRESUMO
The purpose of this work was to see if the alkylpyrroleviologen redox polymer technology previously developed for a reagentless nitrate biosensor based on nitrate reductase (NaR) from Escherichia coli (Cosnier, S.; Innocent, C.; Jouanneau, Y. Anal. Chem. 1994, 66, 3198-3201) could be applied to the isozyme from Aspergillus niger. In particular, the enzyme viability after immobilization was of great interest, as Cosnier et al. reported a residual activity of only 0.33% of the amount initially applied. The present work showed that A. niger NaR lost 99.2% of soluble activity on vacuum-drying in the presence of 2.5 nM N-methyl-N'-(12-[pyrrol-1-yl]dodecyl)-4,4'-bipyridinium ditetrafluoroborate monomer (C12V2+) and that most of this loss was due to monomer inhibition (91%). The loss due to dehydration was only 8%. In the biosensor configuration, the enzyme gave a residual activity of 0.18% of the amount originally applied and a specific response of 1.7 mA M-1 cm-2, but all activity was lost after 4 d storage at 4 degrees C in phosphate buffer. It was concluded that for practical biosensors and bioreactors, modification of the redox polymer format was needed, for example by covalent immobilization, to effect higher loading of viable NaR and improved enzyme stability.
Assuntos
Reatores Biológicos , Técnicas Biossensoriais , Enzimas Imobilizadas/química , Nitrato Redutases/química , Nitrato Redutases/metabolismo , Paraquat/análogos & derivados , Eletrodos , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Nitrato Redutase (NAD(P)H) , Oxirredução , Paraquat/química , Polímeros/químicaRESUMO
Our purpose was to assess the effect of alterations in the cranial venous outflow on cerebrospinal fluid (CSF) flow waveforms using phase-contrast MRI. Thirteen healthy subjects were assessed for CSF flow and cerebral vascular flow at the C2-3 level, both before and after jugular venous compression (JVC). The flow waveforms were assessed both as an aggregate, and after dividing subjects in two groups based on percent jugular venous flow (PJVF) i.e. jugular outflow expressed as percent of cerebral arterial inflow. Group 1:7 subjects with PJVF more than and including median (predominantly jugular outflow); Group 2:6 subjects with PJVF less than median (predominantly extra-jugular outflow). CSF waveforms: JVC produced rounding of contours and flattening of dicrotic waves, with the effect being greater in group 1 than group 2. In group 1, systolic upslopes of the waveforms increased. No significant aggregate amplitude changes were noted; amplitudes increased in group 1 (P = 0.001), and decreased in group 2 (P = 0.03). Temporal interval to the maximum CSF systolic flow significantly increased in group 1. Vascular flow: Arterial flow significantly decreased in group 1. Jugular flow significantly decreased in both groups. The results suggest that CSF flow waveforms are sensitive to alterations in the cranial venous outflow. Changes in group 1 are most likely because of an elevation in intracranial pressure. Analysis of CSF flow waveforms appears a promising noninvasive tool for assessment of cranial compartment.
Assuntos
Encéfalo/irrigação sanguínea , Líquido Cefalorraquidiano/fisiologia , Imagem Cinética por Ressonância Magnética/métodos , Pressão Venosa/fisiologia , Adulto , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Feminino , Hemodinâmica/fisiologia , Humanos , Veias Jugulares , Masculino , Pletismografia , Estudos RetrospectivosRESUMO
Our purpose in this investigation was to explain the heterogeneity in the cerebrospinal fluid (CSF) flow pulsation amplitudes. To this end, we determined the contributions of the cerebral arterial and jugular venous flow pulsations to the amplitude of the CSF pulsation. We examined 21 healthy subjects by cine phase-contrast MRI at the C2-3 disc level to demonstrate the CSF and vascular flows as waveforms. Multiple regression analysis was performed to calculate the contributions of (a) the arterial and venous waveform amplitudes and (b) the delay between the maximum systolic slopes of the arterial and venous waveforms (AV delay), in order to predict the amplitude of the CSF waveform. The contribution of the arterial waveform amplitude was positive (r = 0.61; p = 0.003) to the CSF waveform amplitude and that of the venous waveform amplitude was negative (r = -0.50; p = 0.006). Both in combination accounted for 56% of the variance in predicting the CSF waveform amplitude (p < 0.0006). The contribution of AV delay was not significant. The results show that the variance in the CSF flow pulsation amplitudes can be explained by concurrent evaluation of the CSF and vascular flows. Improvement in the techniques, and controlled experiments, may allow use of CSF flow pulsation amplitudes for clinical applications in the non-invasive assessment of intracranial dynamics by MRI.