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William P Dillon

Publications and source records attributed to William P Dillon.

At least 19 recordsLinked to original sources
PubMed2006

Sex-based differences in the effect of intra-arterial treatment of stroke: analysis of the PROACT-2 study.

BACKGROUND AND PURPOSE: Sex influences outcome after intravenous thrombolysis. In a combined analysis of the tissue plasminogen activator clinical trials, a sex-by-treatment interaction was observed. We sought to confirm that observation in an independent data set. METHODS: Data were from the Pro-Urokinase for Acute Cerebral Thromboembolism-2 (PROACT-2) trial. Baseline factors were compared by sex. The primary outcome was an assessment of a sex-by-treatment interaction term within a logistic regression model, using a modified Rankin Scale score <or=2 at 90 days as the binary outcome. We also assessed whether there were differences in CT-scan appearance and recanalization at 2 hours post-treatment. RESULTS: In the PROACT-2 study of intra-arterial stroke thrombolysis, in both women and men, prourokinase resulted in better outcomes than control. A sex by prourokinase treatment interaction was observed, with women showing a larger treatment effect (20% absolute benefit) compared with men (10% absolute benefit). The reason for this interaction is that thrombolytic treatment nullifies the worse outcome for untreated women compared with men. The reasons for effect modification do not include improved recanalization at 2 hours among women. CONCLUSIONS: Women with middle cerebral artery ischemic stroke benefit more from intra-arterial therapy. Further study of how sex affects stroke outcome is needed.

Aged↗
PubMed2006

Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke.

BACKGROUND AND PURPOSE: Different definitions have been proposed to define the ischemic penumbra from perfusion-CT (PCT) data, based on parameters and thresholds tested only in small pilot studies. The purpose of this study was to perform a systematic evaluation of all PCT parameters (cerebral blood flow, volume [CBV], mean transit time [MTT], time-to-peak) in a large series of acute stroke patients, to determine which (combination of) parameters most accurately predicts infarct and penumbra. METHODS: One hundred and thirty patients with symptoms suggesting hemispheric stroke < or =12 hours from onset were enrolled in a prospective multicenter trial. They all underwent admission PCT and follow-up diffusion-weighted imaging/fluid-attenuated inversion recovery (DWI/FLAIR); 25 patients also underwent admission DWI/FLAIR. PCT maps were assessed for absolute and relative reduced CBV, reduced cerebral blood flow, increased MTT, and increased time-to-peak. Receiver-operating characteristic curve analysis was performed to determine the most accurate PCT parameter, and the optimal threshold for each parameter, using DWI/FLAIR as the gold standard. RESULTS: The PCT parameter that most accurately describes the tissue at risk of infarction in case of persistent arterial occlusion is the relative MTT (area under the curve=0.962), with an optimal threshold of 145%. The PCT parameter that most accurately describes the infarct core on admission is the absolute CBV (area under the curve=0.927), with an optimal threshold at 2.0 ml x 100 g(-1). CONCLUSIONS: In a large series of 130 patients, the optimal approach to define the infarct and the penumbra is a combined approach using 2 PCT parameters: relative MTT and absolute CBV, with dedicated thresholds.

Adult↗
PubMed2006

Human growth hormone-related iatrogenic Creutzfeldt-Jakob disease with abnormal imaging.

BACKGROUND: Although more than 160 cases of iatrogenic Creutzfeldt-Jakob disease (iCJD) from human growth hormone (hGH) treatment have been documented, to our knowledge abnormal cerebellar findings on magnetic resonance imaging (MRI) have not been reported. OBJECTIVE: To report a case of hGH-related iCJD with abnormal cerebellar MRI findings on fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted MRI (DWI). DESIGN: Case report. SETTING: Outpatient neurology clinic at a university medical center. PATIENT: A 33-year old man who had subacute gait ataxia and blurred vision. RESULTS: Beginning 19 years prior, this patient had received cadaveric pituitary-derived hGH treatment for at least 5 years. Magnetic resonance imaging revealed FLAIR and DWI abnormalities, particularly in the cerebellum. He died 7 months after disease onset of autopsy-confirmed iCJD. Pathological changes corresponded largely to MRI findings. CONCLUSIONS: To our knowledge, this is the first case of hGH-related iCJD with FLAIR and DWI abnormalities within the cerebellum. As symptoms referable to the cerebellum occur early in iCJD, it suggests that these MRI sequences may allow earlier diagnosis of this form of prion disease.

Adult↗
PubMed2006

Perfusion, diffusion and spectroscopy values in newly diagnosed cerebral gliomas.

PURPOSE: To evaluate perfusion, diffusion, and spectroscopy values in enhancing and non-enhancing lesions for patients with newly diagnosed gliomas of different grades. MATERIALS AND METHODS: Sixty-seven patients with newly diagnosed glioma were entered into the study 20 grade II, 26 grade III and 21 grade IV. MR data were acquired at 1.5T and included diffusion weighted images (59/67 patients), dynamic perfusion weighted images (30/67 patients) and 3D H-1 MR spectroscopy (64/67 patients). Enhancing and non-enhancing lesions were delineated by a neuroradiologist and applied to maps of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), relative anisotropy (RA) and metabolite intensities. RESULTS: The median rCBV within enhancing regions of grade IV gliomas was significantly elevated relative to enhancing regions in grade III gliomas and normal brain. ADC was elevated relative to normal brain, but was not significantly different between grades or between enhancing and non-enhancing regions. The RA was higher in the non-enhancing region of grade IV gliomas relative to grade II and grade III. Levels of lactate plus lipid were significantly elevated in grade IV relative to grade II and grade III gliomas. Both enhancing and non-enhancing regions in grade IV gliomas showed significant correlations between CBV, ADC and choline levels. CONCLUSION: The data were consistent with grade IV gliomas having higher membrane turnover, increased cell density and increased vascularity within enhancing lesions. Analysis of the correlations among parameters within grade IV gliomas suggested that high vascularity (high rCBV) was correlated with increased cellularity (low ADC) and increased membrane turnover (high choline) in these lesions. The non-enhancing region of grades II and III gliomas had MR parameters consistent with increased cellularity and/or membrane turnover.

Adult↗
PubMed2006

Noninvasive oxygen partial pressure measurement of human body fluids in vivo using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The oxygen partial pressure (pO2) of human body fluids reflects the oxygenation status of surrounding tissues. All existing fluid pO2 measurements are invasive, requiring either microelectrode/optode placement or fluid removal. The purpose of this study is to develop a noninvasive magnetic resonance imaging method to measure the pO2 of human body fluids. MATERIALS AND METHODS: We developed an imaging paradigm that exploits the paramagnetism of molecular oxygen to create quantitative images of fluid oxygenation. A single-shot fast spin echo pulse sequence was modified to minimize artifacts from motion, fluid flow, and partial volume. Longitudinal relaxation rate (R1 = 1/T1) was measured with a time-efficient nonequilibrium saturation recovery method and correlated with pO2 measured in phantoms. RESULTS: pO2 images of human and fetal cerebrospinal fluid, bladder urine, and vitreous humor are presented and quantitative oxygenation levels are compared with prior literature estimates, where available. Significant pO2 increases are shown in cerebrospinal fluid and vitreous following 100% oxygen inhalation. Potential errors due to temperature, fluid flow, and partial volume are discussed. CONCLUSIONS: Noninvasive measurements of human body fluid pO2 in vivo are presented, which yield reasonable values based on prior literature estimates. This rapid imaging-based measurement of fluid oxygenation may provide insight into normal physiology as well as changes due to disease or during treatment.

Adult↗
PubMed2006

Prognostic significance of angiographically confirmed large vessel intracranial occlusion in patients presenting with acute brain ischemia.

INTRODUCTION: Independent predictors of outcome for ischemic stroke include age and initial stroke severity. Intracranial large-vessel occlusion would be expected to predict poor outcome. Because large-vessel occlusion and stroke severity are likely correlated, it is unclear if largevessel occlusion independently predicts outcome or is simply a marker for stroke severity. METHODS: A consecutive series of patients with suspected stroke or transient ischemic attack were imaged acutely with computed tomography angiography (CTA). CTAs were reviewed for intracranial large-vessel occlusion as the cause of the stroke. Baseline National Institutes of Health Stroke Scale (NIHSS) score, discharge modified Rankin score, and patient demographics were abstracted from hospital records. Poor neurological outcome was defined as modified Rankin score exceeding 2. RESULTS: Seventy-two consecutive patients with acute ischemic stroke were imaged with CTA. The median (range) time from stroke symptom onset to CT imaging was 183 minutes (25 minutes to 4 days). Median NIHSS score was 6 (1-32) and intracranial large-vessel occlusion was found in 28 (38.9%) patients. Fifty-six percent of patients had a good neurological outcome. In multivariate logistic regression analysis, two variables predicted poor neurological outcome: baseline NIHSS score (OR 1.21, 95% CI [1.07-1.37]) and presence of intracranial large-vessel occlusion (OR 4.48, 95% CI [1.19-16.9]). The predictive value of large-vessel occlusion on outcome was similar to an 8-point increase in NIHSS score. CONCLUSION: In patients presenting with acute brain ischemia, intracranial large-vessel occlusion independently predicts poor neurological outcome at hospital discharge, as does the presence of a high NIHSS score. Performing routine intracranial vascular imaging on acute stroke patients may allow for more accurate determination of prognosis and may also guide therapy.

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PubMed2005

Comparative overview of brain perfusion imaging techniques.

BACKGROUND AND PURPOSE: Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. SUMMARY OF REVIEW: This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. CONCLUSIONS: For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting.

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PubMed2005

Incidence of contrast nephropathy from cerebral CT angiography and CT perfusion imaging.

The incidence of contrast-induced nephropathy was examined in 1,075 patients receiving routine CT angiography and CT perfusion brain imaging at a single institution. Fifty-two patients had a creatinine rise of > or =0.5 mg/dL. In four patients (0.37%), the administration of IV contrast medium possibly contributed to renal failure. Two patients (0.19%) received temporary hemodialysis during hospitalization. The incidence of contrast nephropathy in neurovascular patients is low.

Cohort Studies↗
PubMed2005

Quantitative apparent diffusion coefficients and T2 relaxation times in characterizing contrast enhancing brain tumors and regions of peritumoral edema.

PURPOSE: To investigate the potential value and relationship of in vivo quantification of apparent diffusion coefficients (ADCs) and T2 relaxation times for characterizing brain tumor cellularity and tumor-related edema. MATERIALS AND METHODS: A total of 26 patients with newly diagnosed gliomas, meningiomas, or metastases underwent diffusion-weighted and six-echo multisection T2-preparation imaging. Regions of interest (ROIs) were drawn on conventional MR images to include tumor (as defined by contrast agent enhancement) and immediate and peripheral edema. Areas of necrosis were excluded. Median values of ADCs and T2 in the ROIs were calculated. RESULTS: ADCs for gliomas were similar to those for meningiomas or metastases in all regions. Tumor T2 values for gliomas (159.5+/-30.6 msec) were significantly higher than those for meningiomas or metastases (125.0+/-31.1 msec; P=0.005). Immediate-edema T2 values for meningiomas or metastases (226.0+/-44.1 msec) were significantly higher than those for gliomas (203.5+/-32.8 msec; P=0.033). Peripheral-edema T2 values for gliomas (219.5+/-41.9 msec) were similar to those for meningiomas or metastases (202.5+/-26.5 msec; P=0.377). Both immediate- and peritumoral-edema ADCs and T2 values were significantly higher than those in tumor for both tumor types. ADCs and T2 values from all regions correlated significantly for gliomas (r=0.95; P<0.0001) and for meningiomas or metastases (r=0.81; P<0.0001). CONCLUSION: The higher immediate-edema T2 values for nonglial tumors than for gliomas suggest tumor-related edema (vasogenic vs. infiltrated) can be further characterized by using T2 values. There were significant correlations between ADC and T2 values.

Adult↗
PubMed2005

Measurement of cerebrospinal fluid oxygen partial pressure in humans using MRI.

Fluid-attenuated inversion recovery (FLAIR) images obtained during the administration of supplemental oxygen demonstrate a hyperintense signal within the cerebrospinal fluid (CSF) that is likely caused by T1 changes induced by paramagnetic molecular oxygen. Previous studies demonstrated a linear relationship between the longitudinal relaxation rate (R1 = 1/T1) and oxygen content, which permits quantification of the CSF oxygen partial pressure (P(csf)O2). In the current study, CSF T1 was measured at 1.5 T in the lateral ventricles, third ventricle, cortical sulci, and basilar cisterns of eight normal subjects breathing room air or 100% oxygen. Phantom studies performed with artificial CSF enabled absolute P(csf)O2 quantitation. Regional P(csf)O2 differences on room air were observed, from 65 +/- 27 mmHg in the basilar cisterns to 130 +/- 49 mmHg in the third ventricle. During 100% oxygen, P(csf)O2 increases of 155 +/- 45 and 124 +/- 34 mmHg were measured in the basilar cisterns and cortical sulci, respectively, with no change observed in the lateral or third ventricles. P(csf)O2 measurements in humans breathing room air or 100% oxygen using a T1 method are comparable to results from invasive human and animal studies. Similar approaches could be applied to noninvasively monitor oxygenation in many acellular, low-protein body fluids.

Adult↗
PubMed2005

Serial diffusion-weighted magnetic resonance imaging in cases of glioma: distinguishing tumor recurrence from postresection injury.

OBJECT: Diffusion-weighted magnetic resonance (MR) imaging is an invaluable tool in the diagnosis of acute stroke and other types of brain injury. Abnormalities in and around the resection cavity on diffusion-weighted imaging have been observed following surgery for infiltrating glioma. The purpose of this study was to investigate prospectively the incidence, time course, and ultimate outcome of these abnormalities. METHODS: Forty-four consecutive patients with newly diagnosed gliomas were prospectively observed using serial MR imaging including diffusion-weighted sequences. Clinical and surgical data were also collected. Immediately postoperatively neuroimaging identified 28 patients (64%) in whom areas of reduced diffusion appeared in or around the resection cavity (mean volume 8.2 +/- 1.5 cm3). Complete resolution of this reduced diffusion was demonstrated within 90 days in 24 patients (86%). On subsequent neuroimages these areas demonstrated Gd enhancement as early as postoperative Day 15 and as late as Day 198 and ultimately took on the appearance of encephalomalacia in 26 (93%) of 28 cases. Postoperative reduced diffusion was not predicted by the clinical or surgical parameters that were assessed. No clinical deficits were attributable to the reduced diffusion. CONCLUSIONS: An abnormality related to diffusion-weighted sequences on postoperative MR imaging can occur after resection of newly diagnosed gliomas. In this study the abnormality typically resolved and was replaced by contrast enhancement on follow-up imaging, ultimately demonstrating encephalomalacia on long-term follow up. Findings on neuroimaging during the period of enhancement could be confused with recurrent tumor and interpreted as early treatment failure. Based on the findings of this study the authors strongly suggest that the inclusion of diffusion-weighted sequences in postoperative MR imaging is essential, as is MR imaging immediately before radiation therapy to monitor disease progression. A new enhancement observed after glioma surgery should be interpreted in the context of the diffusion-weighted image obtained immediately postoperatively.

Adult↗
PubMed2005

Spontaneous intracranial hypotension associated with transdural thoracic osteophyte reversed by primary. dural repair. Case report.

Spontaneous intracranial hypotension (SIH) is an increasingly recognized syndrome associated with a specific set of clinical and imaging findings; however, determining the site of spinal cerebrospinal fluid (CSF) leakage in these patients is often difficult, and indications for surgical intervention need to be better defined. The authors report on a 55-year-old woman who presented with posture-related headache, disorientation, and memory impairment. Imaging features were consistent with SIH. Computerized tomography myelography demonstrated a large T2-3 anterior transdural osteophyte associated with a CSF fistula. After an unsuccessful trial of conservative therapy, the patient underwent median sternotomy, T2-3 discectomy and removal of osteophyte, which allowed adequate exposure for primary dural repair. Postoperatively, there was immediate and prolonged resolution of all of her symptoms. This case of SIH was caused by transdural penetration by an anterior osteophyte and CSF leakage in the upper thoracic spine, which was treated effectively by anterior exposure and primary dural repair. Aggressive surgical intervention may be required to treat upper thoracic CSF leaks refractory to other measures.

Diskectomy↗
PubMed2005

Accuracy of dynamic perfusion CT with deconvolution in detecting acute hemispheric stroke.

BACKGROUND AND PURPOSE: Dynamic perfusion CT (PCT) with deconvolution produces maps of time-to-peak (TTP), mean transit time (MTT), regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV), with a computerized automated map of the infarct and penumbra. We determined the accuracy of these maps in patients with suspected acute hemispheric stroke. METHODS: Forty-six patients underwent nonenhanced CT and dynamic PCT, with follow-up CT or MR imaging. Two observers reviewed the nonenhanced studies for signs of stroke and read the PCT maps for TTP, MTT, rCBF, and rCBV abnormalities. Sensitivity, specificity, accuracy, and interobserver agreement were compared (Wilcoxon tests). Nonenhanced CT and PCT data were reviewed for stroke extent according to previously reported methods. Sensitivity, specificity, and accuracy of the computerized maps in detecting ischemia and its extent were determined. RESULTS: Compared with nonenhanced CT, PCT maps were significantly more accurate in detecting stroke (75.7-86.0% vs. 66.2%; P <.01), MTT maps were significantly more sensitive (77.6% vs. 69.2%; P <.01), and rCBF and rCBV maps were significantly more specific (90.9% and 92.7%, respectively, vs. 65.0%; P <.01). Regarding stroke extent, PCT maps were significantly more sensitive than nonenhanced CT (up to 94.4% vs. 42.9%; P <.01) and had higher interobserver agreement (up to 0.763). For the computerized map, sensitivity, specificity, and accuracy, respectively, were 68.2%, 92.3%, and 88.1% in detecting ischemia and 72.2%, 91.8%, and 87.9% in showing the extent. CONCLUSION: Dynamic PCT maps are more accurate than nonenhanced CT in detecting hemispheric strokes. Despite limited spatial coverage, PCT is highly reliable to assess the stroke extent.

Adult↗
PubMed2005

Differentiation of low-grade oligodendrogliomas from low-grade astrocytomas by using quantitative blood-volume measurements derived from dynamic susceptibility contrast-enhanced MR imaging.

BACKGROUND AND PURPOSE: Histopathologic evaluation remains the reference standard for diagnosis of glioma and classification of histologic subtypes, but is challenged by subjective criteria, tissue sampling error, and lack of specific tumor markers. Anatomic imaging is essential for surgical planning of gliomas but is limited by its nonspecificity and its inability to depict beyond morphologic aberrations. The purpose of our study was to investigate dynamic susceptibility contrast-enhanced (DSC) MR imaging characteristics of the two most common subtypes of low-grade infiltrating glioma: astrocytoma and oligodendroglioma. We hypothesized that tumor blood-volume measurements, derived from DSC MR imaging, would help differentiate the two on the basis of differences in tumor vascularity. METHODS: We studied 25 consecutive patients with treatment-naive, histopathologically confirmed World Health Organization grade II astrocytoma (n = 11) or oligodendroglioma (n = 14). All patients underwent anatomic and DSC MR imaging immediately before surgical resection. Histologic confirmation was obtained in all patients. Anatomic MR images were analyzed for morphologic features, and DSC MR data were processed to yield quantitative cerebral blood volume (CBV) measurements. RESULTS: The maximum relative CBV (rCBV(max)) in tumor ranged from 0.48 to 1.34 (0.92 +/- 0.27, median +/- SD) in astrocytomas and from 1.29 to 9.24 (3.68 +/- 2.39) in oligodendrogliomas. The difference in median rCBV(max) between the two tumor types was significant (P < .0001). CONCLUSION: The tumor rCBV(max) measurements derived from DSC MR imaging were significantly higher in low-grade oligodendrogliomas than in astrocytomas. Our findings suggest that tumor rCBV(max) derived from DSC MR imaging can be used to distinguish between the two low-grade gliomas.

Adult↗
PubMed2005

The "small, dark tonsil" in patients presenting with metastatic cervical lymphadenopathy from an unknown primary.

When squamous cell carcinoma (SCC) involves the palatine tonsils, they are generally enlarged and demonstrate intermediate to high signal intensity on T2-weighted MR images and enhance after gadolinium administration. We have identified two patients with SCC of the tonsil where the affected tonsil has low signal intensity on T2-weighted MR images and is smaller than the contralateral normal tonsil. We present the "small, dark tonsil" as an alternative imaging presentation of SCC and a new sign to look for when evaluating the patient with metastatic lymphadenopathy from an unknown primary tumor.

Adult↗
PubMed2004

Neurotoxicity of intra-arterial papaverine preserved with chlorobutanol used for the treatment of cerebral vasospasm after aneurysmal subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Papaverine is used to vasodilate cerebral arteries undergoing vasospasm from subarachnoid hemorrhage. However, papaverine inhibits cellular respiration in vitro and could cause neurotoxicity in humans. METHODS: We studied 5 consecutive patients with cerebral vasospasm who were treated with intra-arterial papaverine preserved with chlorobutanol and imaged with MRI fluid-attenuated inversion recovery and diffusion-weighted imaging after treatment. One patient had histological analysis of the brain at autopsy. RESULTS: All 5 patients exhibited marked neurological decline immediately after treatment, and this was sustained through hospital discharge. In all cases, MRI images showed selective gray matter-only signal changes within the vascular territory treated with papaverine. Histological analysis of 1 case brought to autopsy showed selective injury to islands of neurons with relative sparing of white matter. CONCLUSIONS: Intra-arterial delivery of papaverine preserved with chlorobutanol into vasospastic anterior cerebral arteries may result in marked neurological deterioration with selective gray matter changes on MRI imaging. This effect is consistent with a permanent toxic effect to human brain. It is unclear whether this toxicity is caused by papaverine or chlorobutanol, and its use in the treatment of cerebral vasospasm should be reserved for cases without alternatives.

Aged↗