Papers by Pablo Villablanca
Annals of Neurology, 2007
Predicting hemorrhagic transformation (HT) is critical in the setting of recanalization therapy f... more Predicting hemorrhagic transformation (HT) is critical in the setting of recanalization therapy for acute stroke. Dedicated magnetic resonance imaging (MRI) sequences for detection of increased blood-brain barrier (BBB) permeability recently have been developed. We evaluated the ability of a novel MRI permeability technique to detect baseline derangements predictive of various forms of HT after recanalization therapy. We retrospectively analyzed the clinical and pretreatment MRI data on patients undergoing recanalization therapy for acute cerebral ischemia at a university medical center from January 2004 to November 2006. Pretreatment MRI permeability images derived from perfusion source data were compared with posttreatment imaging to evaluate whether baseline BBB permeability derangements may predict HT after recanalization therapy. The use of a novel permeability technique to illustrate BBB derangements was based on the detection of decreased signal intensity at later time points in perfusion MRI acquisition, signifying continued local accumulation of contrast caused by leakage. Among 32 patients, some degree of HT occurred in 12. Permeability image abnormalities at baseline were present in 7 of 12 patients with HT and none of the 20 patients without HT on follow-up images. The sensitivity of permeability abnormality for parenchymal hematoma was 83%. False-negative findings were noted in five cases, most commonly asymptomatic or minor HT after mechanical clot retrieval. Permeability images derived from pretreatment perfusion MRI source data may identify patients at risk for HT with high specificity. Our preliminary demonstration of permeability imaging based on standard perfusion data for prediction of hemorrhage merits further study with dedicated MRI BBB permeability acquisitions and multicenter validation.
Stroke; a journal of cerebral circulation, 2014
If magnetic resonance imaging (MRI) is to compete with computed tomography for evaluation of pati... more If magnetic resonance imaging (MRI) is to compete with computed tomography for evaluation of patients with acute ischemic stroke, there is a need for further improvements in acquisition speed. Inclusion criteria for this prospective, single institutional study were symptoms of acute ischemic stroke within 24 hours onset, National Institutes of Health Stroke Scale ≥3, and absence of MRI contraindications. A combination of echo-planar imaging (EPI) and a parallel acquisition technique were used on a 3T magnetic resonance (MR) scanner to accelerate the acquisition time. Image analysis was performed independently by 2 neuroradiologists. A total of 62 patients met inclusion criteria. A repeat MRI scan was performed in 22 patients resulting in a total of 84 MRIs available for analysis. Diagnostic image quality was achieved in 100% of diffusion-weighted imaging, 100% EPI-fluid attenuation inversion recovery imaging, 98% EPI-gradient recalled echo, 90% neck MR angiography and 96% of brain M...
AJNR. American journal of neuroradiology, 2000
Destructive lesions of the sinonasal tract, lacking a discernible etiology and referred to as mid... more Destructive lesions of the sinonasal tract, lacking a discernible etiology and referred to as midline destructive disease, have been pathologically classified in accordance with a variety of confusing terms. Development of new pathologic concepts and immunohistochemical techniques has provided a fresh understanding of these lesions, and, as a result, they can be unified into two distinct pathologic groups: Wegener's granulomatosis and non-Hodgkin's T-cell lymphoma. We retrospectively reviewed the imaging studies and pathologic specimens of seven patients with prior diagnoses included in the midline destructive disease group. The specimens were reviewed by an oral pathologist using currently accepted pathologic criteria and the newly available immunohistochemical markers CD20, CD45, and CD45RO. Lesions were classified as non-Hodgkin's T-cell lymphomas when positive for CD45 and CD45RO and negative for CD20, and as Wegener's granulomatosis in the presence of noncaseati...
Background: Brain iron promotes oxidative damage and protein oligomerization that result in highl... more Background: Brain iron promotes oxidative damage and protein oligomerization that result in highly prevalent age-related proteinopathies such as Alzheimer's disease (AD), Parkinson's disease (PD), and Dementia with Lewy Bodies (DLB). Men are more likely to develop such diseases at earlier ages than women but brain iron levels increase with age in both genders. We hypothesized that brain iron may influence both the age-and gender-related risks of developing these diseases. Methods: The amount of iron in ferritin molecules (ferritin iron) was measured in vivo with MRI by utilizing the field dependent relaxation rate increase (FDRI) method. Ferritin iron was measured in four subcortical nuclei [caudate (C), putamen (P), globus pallidus (G), thalamus (T)], three white matter regions [frontal lobe (Fwm), genu and splenium of the corpus callosum (Gwm, Swm)] and hippocampus (Hipp) in 165 healthy adults aged 19-82. Results: There was a high correlation (r > 0.99) between published post-mortem brain iron levels and FDRI. There were significant age-related changes in ferritin iron (increases in Hipp, C, P, G, and decreases in Fwm). Women had significantly lower ferritin iron than men in five regions (C, T, Fwm, Gwm, Swm). Conclusions: This is the first demonstration of gender differences in brain ferritin iron levels. It is possible that brain iron accumulation is a risk factor that can be modified. MRI provides the opportunity to assess brain iron levels in vivo and may be useful in targeting individuals or groups for preventive therapeutic interventions.
Medical Imaging 2001: Visualization, Display, and Image-Guided Procedures, 2001
ABSTRACT MR-guided neurosurgery may offer greater accuracy in surgical localization and resection... more ABSTRACT MR-guided neurosurgery may offer greater accuracy in surgical localization and resection of brain tumors. Proper utilization of MRI for surgical guidance requires real-time consultation with a neuroradiologist during typically lengthy procedures. We sought to build a system that allows fast and efficient tele-radiologic consultation in the MR- surgical suite. We modeled the imaging tasks and data flow for representative MR-guided neurosurgical procedures. Customized viewing modes, which associate specific data and tasks, were designed accordingly. We implemented application sharing in order to allow teleconsultation between the surgeon and a remotely located radiologist during a case. The system described here provides an effective and efficient method for expert tele-consultation during MR-guided neurosurgery.
Medical Imaging 2005: Physiology, Function, and Structure from Medical Images, 2005
Numerical simulations of pulsatile blood flow were conducted in a patient-specific model of an an... more Numerical simulations of pulsatile blood flow were conducted in a patient-specific model of an anterior communicating artery aneurysm that was found to grow over time. The effect of changes in inflow parameters on the numerical simulation results was also investigated since patient-specific velocity measurements were not available to be used as inflow conditions. It was found that shear stress distribution
Surgical Neurology International, 2013
The purpose of this article is to explain the anatomy of the pterygopalatine ganglion (PPG), its ... more The purpose of this article is to explain the anatomy of the pterygopalatine ganglion (PPG), its location in the pterygopalatine fossa (PPF) in the skull, and the relationship it has to the Vidian nerve terminal branches and the fifth cranial nerve. An overview of the neuro-anatomical/clinical correlations, a spectrum of pathologies affecting the seventh cranial nerve and some therapies both medical and surgical are noted. The focus is the pterygopalatine region with discussion of the proximal courses of the seventh and fifth cranial nerves and their pathological processes. The ganglion is used as an example of neuro-anatomical model for explaining cluster headaches (CH). Radiological correlation is included to clarify the location of the PPF and its clinical importance.
Stroke, 2012
Background-Determinants of successful recanalization likely differ for Merci thrombectomy(MT) and... more Background-Determinants of successful recanalization likely differ for Merci thrombectomy(MT) and intra-arterial pharmacologic fibrinolysis interventions. While the amount of thrombotic material to be digested is an important consideration for chemical lysis, mechanical debulking may be more greatly influenced by other target lesion characteristics.
Neurosurgery, 1999
Animal and human studies have shown increased delivery of radiolabeled compounds across the blood... more Animal and human studies have shown increased delivery of radiolabeled compounds across the blood-brain-tumor barrier using intra-arterial (IA) Cereport (RMP-7; Alkermes Inc., Cambridge, MA) with a radiolabeled tracer. This present study assesses the safety, tolerance, and preliminary efficacy of the IA administration of carboplatin with Cereport. An open-label dose escalation study of IA Cereport (10-300 ng/kg) with 100 mg of IA carboplatin was conducted in 11 patients with recurrent malignant gliomas and 1 patient treated adjuvantly after radiation therapy. Tumor size and laboratory and clinical statuses were assessed. Adverse events were mainly neurological in nature and corresponded to the anatomic location of the tumor. Karnofsky performance scale scores did not decline, overall, for those patients who had tumor response. Tumor shrinkage was observed in three of six evaluable patients who received a dose of 300 ng/kg with durable responses of 60, 64, and 106+ weeks. Previous studies have demonstrated increased permeability in human gliomas using IA Cereport. This study demonstrates durable imaging responses using 100 mg of IA carboplatin in combination with Cereport. The drug combination in this patient population seems to be safe and acceptable, providing a novel means of antitumor dose intensification.
Cerebrovascular Diseases, 2006
Cerebral microbleeds (CMB) detected on gradient-echo T2*-weighted MRI have been associated with c... more Cerebral microbleeds (CMB) detected on gradient-echo T2*-weighted MRI have been associated with cognitive impairment and the potential for increased risk of intracranial hemorrhage. We evaluated risk factors for these microangiopathic lesions in a cohort of stroke and transient ischemic attack patients. Presence and number of CMB in consecutive acute stroke patients admitted to a university hospital stroke service over an 18-month period were rated. Multivariate models were generated to determine the contribution of 21 demographic and clinical variables to the frequency and number of CMB. Of 164 patients (mean age 71 years, 52% female), 57 (35%) had CMB evident on gradient-echo T2*-weighted MRI. CMB were more commonly noted among patients with small vessel disease ischemic stroke mechanism (47%) than large vessel atherothromboembolic (12%) or cardioembolic (18%, p = 0.0001). In univariate analysis, patients with CMB were older, (p = 0.008), more likely to have been on >1 antihypertensive prior to admission (p = 0.024) than those without CMB. In multivariate logistic regression analyses, presumed small vessel stroke subtype, history of atrial fibrillation, being on >1 antihypertensive prior to admission, and smoking were independent factors increasing the risk of CMB. Logistic regression analysis by number of CMB showed almost similar findings. CMB are more frequently noted in hospitalized stroke and transient ischemic attack patients with small vessel ischemia, as well as those with important modifiable vascular risk factors like atrial fibrillation and smoking.
Alzheimer's & Dementia, 2009
Background: Apolipoprotein E (APOE) e4 allele is a well-known genetic risk factor of Alzheimer's ... more Background: Apolipoprotein E (APOE) e4 allele is a well-known genetic risk factor of Alzheimer's disease (AD). The influence of APOE e4 allele on cerebral ß-amyloid (Aß) deposition in cognitive normal elderly has not been investigated yet. This study aimed to test if presence of the APOE e4 allele is associated with increased cerebral Aß deposition and decreased glucose metabolism in cognitively normal elderly. Methods: 22 cognitive normal participants were included in the study of whom 8 were APOE e4 carriers and age-matched 14 were APOE e4 non-carriers. PIB-PET and FDG-PET were performed. Comparisons between APOE e4 carriers and non-carriers for mean cerebral regional binding potential (BP) of Aß burden and cerebral glucose metabolism were investigated with volume of interest (VOI) analysis. Results: BPs were significantly higher in APOE e4 carriers than APOE e4 non-carriers in the caudate, thalamus, and superior temporal pole (p ¼ 0.037; p ¼ 0.048; p ¼ 0.031). Compared to APOE e4 non-carriers, APOE e4 carriers had significant decrease of cerebral glucose metabolism in the precuneus (p ¼ 0.032). Conclusions: Although the exact mechanism underlying vulnerability in APOE e4 carriers is still unclear, these findings indicate that the cognitive normal elderly with genetic risk factor of Alzheimer's disease is associated with increased Aß burden in the limbic area and decreased glucose metabolism in the precuneus.
Alzheimer's & Dementia, 2008
Alzheimer's & Dementia: The Journal of the Alzheimer's Association, Volume 4, Issue... more Alzheimer's & Dementia: The Journal of the Alzheimer's Association, Volume 4, Issue 4, Pages T75, July 2008, Authors:George Bartzokis; Po-Haong Lu; Kathleen Tingus; Mario Mendez; Aurora Richards; Douglas Peters; Pablo Villablanca; Paul Finn; Paul Thompson; Jim Mintz. ...
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Papers by Pablo Villablanca