Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 6 de 6
Filter
1.
AJNR Am J Neuroradiol ; 35(5): 1016-21, 2014 May.
Article in English | MEDLINE | ID: mdl-24263696

ABSTRACT

BACKGROUND AND PURPOSE: SWI is a powerful tool for imaging of the cerebral venous system. The SWI venous contrast is affected by blood flow, which may be altered in sickle cell disease. In this study, we characterized SWI venous contrast in patients with sickle cell disease and healthy control participants and examined the relationships among SWI venous contrast, and hematologic variables in the group with sickle cell disease. MATERIALS AND METHODS: A retrospective review of MR imaging and hematologic variables from 21 patients with sickle cell disease and age- and sex-matched healthy control participants was performed. A Frangi vesselness filter was used to quantify the attenuation of visible veins from the SWI. The normalized visible venous volume was calculated for quantitative analysis of venous vessel conspicuity. RESULTS: The normalized visible venous volume was significantly lower in the group with sickle cell disease vs the control group (P < .001). Normalized visible venous volume was not associated with hemoglobin, percent hemoglobin F, percent hemoglobin S, absolute reticulocyte count, or white blood cell count. A hypointense arterial signal on SWI was observed in 18 of the 21 patients with sickle cell disease and none of the 21 healthy control participants. CONCLUSIONS: This study demonstrates the variable and significantly lower normalized visible venous volume in patients with sickle cell disease compared with healthy control participants. Decreased venous contrast in sickle cell disease may reflect abnormal cerebral blood flow, volume, velocity, or oxygenation. Quantitative analysis of SWI contrast may be useful for investigation of cerebrovascular pathology in patients with sickle cell disease, and as a tool to monitor therapies. However, future studies are needed to elucidate physiologic mechanisms of decreased venous conspicuity in sickle cell disease.


Subject(s)
Algorithms , Anemia, Sickle Cell/pathology , Cerebral Veins/pathology , Image Enhancement/methods , Image Interpretation, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Child , Female , Humans , Male , Reproducibility of Results , Retrospective Studies , Sensitivity and Specificity
2.
AJNR Am J Neuroradiol ; 34(7): 1450-5, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23436052

ABSTRACT

BACKGROUND AND PURPOSE: DIPG is among the most devastating brain tumors in children, necessitating the development of novel treatment strategies and advanced imaging markers such as perfusion to adequately monitor clinical trials. This study investigated tumor perfusion and 3D segmented tumor volume as predictive markers for outcome in children with newly diagnosed DIPG. METHODS: Imaging data were assessed at baseline, during, and after RT, and every other month thereafter until tumor progression for 35 patients (ages 2-16 years) with newly diagnosed DIPG enrolled in the phase I clinical study, NCT00472017. Patients were treated with conformal RT and vandetanib, a vascular endothelial growth factor receptor 2 inhibitor. RESULTS: Tumor perfusion increased and tumor volume decreased during combined RT and vandetanib therapy. These changes slowly diminished in follow-up scans until tumor progression. However, increased tumor perfusion and decreased tumor volume during combined therapy were associated with longer PFS. Apart from a longer OS for patients who showed elevated tumor perfusion after RT, there was no association for tumor volume and other perfusion variables with OS. CONCLUSIONS: Our results suggest that tumor perfusion may be a useful predictive marker for the assessment of treatment response and tumor progression in children with DIPG treated with both RT and vandetanib. The assessment of tumor perfusion yields valuable information about tumor microvascular status and its response to therapy, which may help better understand the biology of DIPGs and monitor novel treatment strategies in future clinical trials.


Subject(s)
Brain Stem Neoplasms/diagnosis , Glioma/diagnosis , Imaging, Three-Dimensional/methods , Magnetic Resonance Imaging/methods , Neuroimaging/methods , Adolescent , Antineoplastic Agents/therapeutic use , Blood Volume/drug effects , Blood Volume/radiation effects , Brain Stem Neoplasms/physiopathology , Brain Stem Neoplasms/radiotherapy , Child , Child, Preschool , Cohort Studies , Disease Progression , Echo-Planar Imaging/methods , Female , Follow-Up Studies , Glioma/physiopathology , Glioma/radiotherapy , Humans , Image Enhancement/methods , Image Processing, Computer-Assisted/methods , Male , Neoadjuvant Therapy , Piperidines/therapeutic use , Prospective Studies , Quinazolines/therapeutic use , Radiotherapy, Conformal/methods , Receptors, Vascular Endothelial Growth Factor/antagonists & inhibitors , Survival Rate , Treatment Outcome
3.
AJNR Am J Neuroradiol ; 32(2): 315-22, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21087935

ABSTRACT

BACKGROUND AND PURPOSE: Focal anaplasia characterized by T2 hypointensity, signal-intensity enhancement on postcontrast T1-weighted MR imaging and restricted water diffusion has been reported in a patient with juvenile pilocytic astrocytoma. We identified T2(HOF) with these MR imaging characteristics in children with DIPG and hypothesized that these represent areas of focal anaplasia; and may, therefore, have increased perfusion properties and should be characterized by increased perfusion. Thus, we used DSC to investigate our hypothesis. MATERIALS AND METHODS: We retrospectively reviewed the baseline MR imaging scans of 86 patients (49 girls, 37 boys; median age, 6.1 years; range, 1.1-17.6 years) treated for DIPG at our hospital (2004-2009). T2(HOF) with the described MR imaging characteristics was identified in 10 patients. We used a region of interest-based approach to compare the ADC, FA, rCBV, rCBF, and rMTT of T2(HOF) with those of the typical T2(HRT). RESULTS: The ADC of T2(HOF) with the specified MR imaging characteristics was significantly lower than that of T2(HRT) (range, 0.71-1.95 µm(2)/ms versus 1.36-2.13 µm(2)/ms; P < .01); and the FA (range, 0.12-0.34 versus 0.07-0.24; P = .03) and rCBV (range, 0.4-2.62 versus 0.23-1.57; P = .01) values of T2(HOF)s were significantly higher. CONCLUSIONS: Our data suggest that T2(HOF) in DIPG may represent areas of focal anaplasia and underline the importance of regional, rather than global, tumor-field analysis. T2(HOF) may be the ideal target when stereotactic biopsy of tumors that present with an inhomogeneous T2 signal intensity is considered.


Subject(s)
Brain Stem Neoplasms/pathology , Contrast Media , Diffusion Magnetic Resonance Imaging/methods , Glioma/pathology , Adolescent , Biopsy , Brain Stem Neoplasms/blood supply , Child , Child, Preschool , Female , Glioma/blood supply , Humans , Infant , Male , Necrosis , Retrospective Studies
4.
AJNR Am J Neuroradiol ; 31(5): 901-6, 2010 May.
Article in English | MEDLINE | ID: mdl-20053806

ABSTRACT

BACKGROUND AND PURPOSE: SWI is known for its detailed visualization of the cerebral venous system and seems to be a promising tool for early detection of cerebrovascular pathologies in children, who are frequently sedated for MR imaging. Because sedation influences cerebral hemodynamics, we hypothesized that it would affect cerebral venous contrast in SWI. MATERIALS AND METHODS: SWI (125 examinations) of 26 patients (age, 2-16 years) was reviewed in this study. Images were acquired of patients sedated with propofol. Reviewers classified the images by weak or strong venous contrast. Physiologic data, such as etCO(2), BP, age, and CBF by arterial spin-labeling, were monitored and collected during MR imaging. A generalized estimating equation approach was used to model associations of these parameters with venous contrast. RESULTS: EtCO(2) and CBF were found to correlate with venous contrast, suggesting that patients with high etCO(2) and CBF have weak contrast and patients with low etCO(2) and CBF have strong contrast. BP was also found to correlate with the venous contrast of SWI, suggesting that patients with high BP have strong venous contrast. No significant correlations were found for any other physiologic parameters. CONCLUSIONS: We found that the venous contrast in SWI is affected by propofol sedation in spontaneously breathing patients. We also found that low etCO(2), low CBF, and high BP are associated with strong venous contrast. Reviewing SWI data in light of physiologic measures may therefore help prevent potential misinterpretations of weak venous contrast in SWI examinations under propofol sedation.


Subject(s)
Artifacts , Cerebral Veins/drug effects , Cerebral Veins/pathology , Magnetic Resonance Angiography/methods , Propofol/administration & dosage , Respiratory Mechanics , Adolescent , Child , Child, Preschool , Female , Humans , Male , Reproducibility of Results , Sensitivity and Specificity
5.
J Magn Reson Imaging ; 14(6): 795-9, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11747038

ABSTRACT

In this contribution, a rapid and robust technique for quantitative T(1) mapping of the human lung is presented. Based on a series of Snapshot FLASH tomograms acquired after a single inversion pulse, high quality and quantitative T(1) parameter maps acquired in under five seconds were obtained from six healthy volunteers. The measured T(1) values are in good agreement with previously reported literature values. T(1) maps were also acquired with the volunteers breathing room air or 100% O(2). The T(1) difference between breathing room air and 100% O(2) is statistically significant at P < 0.0001.


Subject(s)
Lung/anatomy & histology , Magnetic Resonance Imaging/methods , Oxygen/administration & dosage , Adult , Feasibility Studies , Female , Humans , Image Enhancement , Lung/physiology , Male , Oxygen/physiology , Reference Values , Respiration
6.
Am Rev Respir Dis ; 141(6): 1434-40, 1990 Jun.
Article in English | MEDLINE | ID: mdl-1693479

ABSTRACT

Electrical stimulation of the vagus nerve of rats is known to produce plasma extravasation in the trachea, presumably by releasing substance P or other tachykinins from sensory nerves. We sought to determine whether the tachyphylaxis that develops after prolonged vagal stimulation results from an inability of sensory nerves to release tachykinins or from an inability of tracheal blood vessels to respond to tachykinins. To induce tachyphylaxis, we electrically stimulated the right vagus nerve of Long-Evans rats for 5 min (5 V, 1 ms, 20 Hz). Then, 10 min later, we gave intravenous injections of capsaicin (0.3 mumol/kg), histamine (18 mumols/kg), or substance P (2.2 nmol/kg), which produce equivalent amounts of plasma extravasation as assessed by the extravasation of Evans blue dye. We found that vagal stimulation reduced the amount of dye extravasation produced by capsaicin but not the amount produced by either histamine or substance P. We also found that pretreating neonatal rats with capsaicin, which destroys tachykinin-containing sensory nerves, reduced the amount of dye extravasation produced by capsaicin but not the amount produced by either histamine or substance P. This finding suggests that capsaicin produces plasma extravasation in the trachea by releasing tachykinins from sensory nerves, whereas histamine and substance P do so by acting directly on tracheal blood vessels. Taken together, our results indicate that prolonged vagal stimulation reduces the ability of sensory nerves to release tachykinins but that tracheal blood vessels remain fully responsive to both histamine and substance P.


Subject(s)
Capillary Permeability/physiology , Tachykinins/metabolism , Tachyphylaxis/physiology , Trachea/innervation , Vagus Nerve/physiology , Animals , Capsaicin/pharmacology , Electric Stimulation , Female , Histamine/pharmacology , Rats , Stimulation, Chemical , Substance P/pharmacology
SELECTION OF CITATIONS
SEARCH DETAIL
...