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Brian C Bowen

Publications and source records attributed to Brian C Bowen.

13 recordsLinked to original sources
PubMed2006

Contrast enhancement of central nervous system lesions: multicenter intraindividual crossover comparative study of two MR contrast agents.

PURPOSE: To prospectively compare gadobenate dimeglumine with gadopentetate dimeglumine (0.1 mmol per kilogram body weight) for enhanced magnetic resonance (MR) imaging of central nervous system (CNS) lesions. MATERIALS AND METHODS: This study was HIPAA-compliant at U.S. centers and was conducted at all centers according to the Good Clinical Practice standard. Institutional review board and regulatory approval were granted; written informed consent was obtained. Seventy-nine men and 78 women (mean age, 50.5 years +/- 14.4 [standard deviation]) were randomized to group A (n = 78) or B (n = 79). Patients underwent two temporally separated 1.5-T MR imaging examinations. In randomized order, gadobenate followed by gadopentetate was administered in group A; order of administration was reversed in group B. Contrast agent administration (volume, speed of injection), imaging parameters before and after injection, and time between injections and postinjection acquisitions were identical for both examinations. Three blinded neuroradiologists evaluated images by using objective image interpretation criteria for diagnostic information end points (lesion border delineation, definition of disease extent, visualization of internal morphologic features of the lesion, enhancement of the lesion) and quantitative parameters (percentage of lesion enhancement, contrast-to-noise ratio [CNR]). Overall diagnostic preference in terms of lesion conspicuity, detectability, and diagnostic confidence was assessed. Between-group comparisons were performed with Wilcoxon signed rank test. RESULTS: Readers 1, 2, and 3 demonstrated overall preference for gadobenate in 75, 89, and 103 patients, compared with that for gadopentetate in seven, 10, and six patients, respectively (P < .0001). Significant (P < .0001) preference for gadobenate was demonstrated for diagnostic information end points, percentage of lesion enhancement, and CNR. Superiority of gadobenate was significant (P < .001) in patients with intraaxial and extraaxial lesions. CONCLUSION: Gadobenate compared with gadopentetate at an equivalent dose provides significantly better enhancement and diagnostic information for CNS MR imaging.

Central Nervous System Diseases↗
PubMed2004

The brachial plexus: normal anatomy, pathology, and MR imaging.

The brachial plexus is the most technically and anatomically challenging area of the peripheral nervous system for diagnostic imaging. Marked improvements in spatial and contrast resolution of plexus images have resulted from the use of phased-array technology and newer MR pulse sequence designs. This article presents case material incorporating these improvements and discusses the primary factors that continue to limit MR image quality, such as inhomogenous fat suppression, motion artifacts, and small vessels that mimic or obscure plexus components, and potential solutions and imaging alternatives. Brachial plexus anatomy and its appearance on multiplanar MR images are reviewed. The morphologic features and MR signal characteristics that have been found useful in distinguishing between normal and abnormal plexus components,and in detecting neuropathic lesions, are addressed in the context of clinical indications for plexus imaging as follows: mass involving the plexus, traumatic injury, entrapment syndrome, posttreatment evaluation, and miscellaneous conditions.

Animals↗
PubMed2003

MR angiography of the spine: update.

The role of MRA, as an adjunct to conventional MR imaging of the spine and spinal cord, is evolving. The older MRA methods that have been applied to spinal vascular imaging include 2D and 3D phase contrast techniques and a derivative of 3D time-of-flight techniques with data acquired for about several minutes after gadolinium contrast injection (standard 3D CE MRA). Newer 3D gradient-echo techniques, which allow the acquisition of each volume of data in tens of seconds as a contrast bolus traverses the region of interest (fast 3D CE MRA), offer the possibility of temporally resolving intradural arteries and veins. The appearance of normal and abnormal intradural vessels, primarily veins, on the standard 3D CE MRA method has been described for the thoracolumbar region. Normal intradural arteries have been more difficult to detect, although preliminary results with the fast 3D CE MRA method, are promising. Only by establishing the MRA appearance of normal arteries and veins, can one begin to define "abnormal" with greater confidence (presuming that the variability in the appearance of normal vessels is not so great as to preclude differentiation). In striving for this goal, MRA has already encountered competition from CT angiography. In the characterization of spinal vascular lesions, the value of MRA has been demonstrated most convincingly for dural AVF. This lesion is more accurately localized and more sensitively detected (by neuroradiolologists and others experienced in spine imaging) with combined MR imaging and standard 3D CE MRA than with MR imaging alone. Preliminary results suggest that sensitivity and specificity may be further improved if fast 3D CE MRA is combined with conventional MR imaging. Although less well documented, the value of MRA in characterizing other lesions, such as AVMs and vascular tumors, has been reported in recent publications. In the future, the role of MRA will depend on technical advances, such as parallel acquisition techniques and possibly implantable RF coils, which permit improved detection of, and differentiation between, intradural arteries and veins. With these improvements, MRA may play an expanded role in the characterization of spinal vascular abnormalities, encompassing trauma and degenerative spine disease and vascular malformations and tumors.

Contrast Media↗
PubMed2003

MR angiography of the spine and spinal cord.

OBJECTIVES: This review has three objectives: 1) to describe spinal vascular anatomy, focusing on thoracolumbar intradural vessels detectable by both magnetic resonance angiography (MRA) and digital subtraction x-ray angiography (DSA), 2) to compare the MRA techniques that have been used to detect the major intradural vessels, and 3) to illustrate the clinical application of these MRA techniques, especially their efficacy in characterizing spinal dural arteriovenous fistulae (AVF). METHODS: MRA is an adjunct to conventional magnetic resonance imaging. MRA is usually implemented as a three-dimensional (3D) contrast-enhanced (CE) gradient-echo technique, with two approaches to data acquisition: 1) "standard" 3D CE MRA, requiring approximately 10 minutes per 3D volume, and 2) "fast" (bolus/dynamic) 3D CE MRA, requiring approximately 0.5 to 2 minutes per 3D volume depending on k-space sampling schemes. Vessels are displayed on targeted maximum intensity projection images. RESULTS: Normal intradural vessels detected on standard CE MRA are primarily veins (medullary and median), whereas both arteries and veins are detected on fast CE MRA. Identification of arteries (artery of Adamkiewicz, anterior spinal artery) is limited, and their differentiation from veins can be incomplete. Intradural vessels in patients with dural fistulae have abnormal features on MRI (length of flow voids and postcontrast serpentine enhancement) and standard 3D CE MRA (length, tortuosity, and qualitative size of dominant perimedullary vessel), which differ significantly from those of normal vessels. Standard MRA added to a conventional MRI study significantly (P=0.016) increased the rate of detection of the spinal level of a dural fistula. The correct level +/- one vertebral segment was identified in 73% of true-positive patients. CONCLUSIONS: Application of spinal MRA requires knowledge of vascular anatomy, specifically the major intradural vessels, and careful implementation of 3D CE MRA techniques. The standard technique allows for more effective noninvasive screening for vascular lesions, particularly dural AVF, than magnetic resonance imaging alone. Preliminary results indicate that the fast technique may further improve characterization of normal and abnormal intradural vessels, especially if continued technical advances yield greater temporal resolution while maintaining adequate spatial resolution.

Arterial Occlusive Diseases↗
PubMed2003

Proton MR spectroscopy of gliomatosis cerebri: case report of elevated myoinositol with normal choline levels.

A 69-year-old woman presented with clinical and imaging findings suspicious for gliomatosis cerebri, later confirmed by biopsy (moderately cellular, infiltrating glioma). Single voxel proton MR spectroscopy (TE 20 and TE 135) and spectroscopic imaging (TE 135) performed at admission showed normal choline, decreased N-acetyl, and elevated myo-inositol levels relative to creatine. The primary conclusion is that in suspected cases of gliomatosis cerebri, myo-inositol/creatine and myo-inositol/N-acetyl should be determined because they may provide evidence of tumor, even though choline/creatine is normal. A corollary to this conclusion is that choline/creatine may be misleading if used to demarcate infiltrating glioma from edema.

Aged↗
PubMed2002

A pilot study of cidofovir for progressive multifocal leukoencephalopathy in AIDS.

OBJECTIVE: To assess the safety, tolerability and effect of cidofovir for HIV-1 associated progressive multifocal leukoencephalopathy. DESIGN: Prospective, open-label study in nine AIDS Clinical Trials Units. PATIENTS AND METHODS: Twenty-four HIV-1-infected individuals, with neuroimaging and clinical findings consistent with PML, and symptoms for 90 days or less, whose diagnosis was confirmed by the detection of JC virus DNA in the cerebrospinal fluid or brain biopsy, received cidofovir 5 mg/kg intravenously at baseline and 1 week, followed by infusions every 2 weeks with the dose adjusted for renal function. Follow-up continued to 24 weeks. The safety of cidofovir and changes in neurological examination scores between baseline and week 8 were assessed. RESULTS: Seventeen subjects were receiving potent antiretroviral agents. Survival at 12 weeks was 54%. The CD4 cell count at entry was significantly associated with survival (P = 0.02). Five subjects discontinued treatment because of toxicity: a 50% or greater decrease in intraocular pressure in either eye in four, and proteinuria in one. Overall, magnetic resonance imaging abnormalities and neurological examination scores worsened. Only two subjects experienced a 25% or greater improvement in neurological examination scores at week 8, which were significantly better in subjects with HIV-1-RNA levels of 500 copies/ml or less at entry compared with those with HIV-1-RNA levels over 500 copies/ml (P = 0.05). CONCLUSION: Cidofovir did not improve neurological examination scores at week 8. However, such scores were significantly better in subjects who entered with suppressed plasma HIV-1-RNA levels, which could be the result of control of HIV-1 infection itself or cidofovir.

Adult↗
PubMed2002

Magnetic resonance spectroscopy in childhood brainstem tumors.

Five children with brainstem tumors and two control patients had magnetic resonance spectroscopy studies of the brainstem. Two of the malignant tumor patients had magnetic resonance spectroscopy studies before and after radiation therapy. The third was irradiated 14 years earlier but developed new symptoms and a new brainstem lesion on MRI. Magnetic resonance spectroscopy demonstrated a different degree of malignancy between the old and new lesion. The fourth patient had magnetic resonance spectroscopy of a chronic, large pontine lesion 6 years after diagnosis and radiation. The spectral pattern suggested a low degree of malignancy. The fifth patient had neurofibromatosis type 1 with brainstem lesions. Magnetic resonance spectroscopy suggested neoplastic tissue of low malignancy. These results suggest that magnetic resonance spectroscopy offers additional information for anticipating the degree of anaplasia in children with brainstem tumors.

Adolescent↗
PubMed2002

Effects of physiologic human brain motion on proton spectroscopy: quantitative analysis and correction with cardiac gating.

SUMMARY: Proton MR spectroscopy is a powerful noninvasive method that enables measurement of certain brain metabolites in healthy subjects and patients with diseases. A major difficulty with clinical and research applications of in vivo proton MR spectroscopy is the variability of metabolite concentrations, especially in regions with substantial physiologic motion. In our preliminary evaluation, we tested the hypothesis that physiologic brain motion leads to lower mean metabolite concentrations and higher SDs for the measured metabolite concentrations.

Adult↗
PubMed2002

Detection of spinal dural arteriovenous fistulae with MR imaging and contrast-enhanced MR angiography: sensitivity, specificity, and prediction of vertebral level.

BACKGROUND AND PURPOSE: MR imaging and contrast-enhanced MR angiography have been used to detect evidence of spinal dural arteriovenous fistulae (AVF); however, the sensitivity and specificity of these techniques have not been shown. The purpose of this study was to establish the sensitivity, specificity, and accuracy of MR imaging alone compared with MR imaging plus MR angiography in determining whether dural AVF are present and to establish the accuracy of MR angiography in predicting fistula level. METHODS: Twenty patients with surgically proven dural AVF (diagnosed with radiographic digital subtraction angiography) and 11 control patients who had normal digital subtraction angiography findings underwent routine MR imaging plus 3D contrast-enhanced MR angiography of the spine. Images were reviewed in two stages (stage I, MR images only; stage II, MR images plus MR angiograms) by three neuroradiologists who were blinded to the final diagnoses. RESULTS: The sensitivity, specificity, and accuracy of the three reviewers in detecting the presence of fistulae ranged from 85% to 90%, from 82% to 100%, and from 87% to 90%, respectively, for stage I, compared with values of 80% to 100%, 82%, and 81% to 94%, respectively, for stage II. For each reviewer, there was no significant difference between the values for stages I and II; however, among the reviewers, one of the more experienced neuroradiologists had significantly greater sensitivity than a less experienced neuroradiologist for stage II. On average, the percentage of true positive results for which the correct fistula level was predicted increased from 15% for stage I to 50% for stage II, and the correct level +/- one level was predicted in 73% for stage II. MR evidence of increased intradural vascularity was significantly greater in patients with dural AVF. CONCLUSION: The addition of MR angiography to standard MR imaging of the spine may improve sensitivity in the detection of spinal dural fistulae. The principal benefit of MR angiography is in the improved localization of the vertebral level of the fistula, which potentially expedites the subsequent digital subtraction angiography study.

Adult↗
PubMedDate not supplied

Proton magnetic resonance spectroscopy of the thalamus in patients with chronic neuropathic pain after spinal cord injury.

BACKGROUND AND PURPOSE: Spinal cord injury (SCI) results in a number of consequences; one of the most difficult to manage is chronic neuropathic pain. Thus, defining the potential neural and biochemical changes associated with chronic pain after SCI is important because this may lead to development of new treatment strategies. Prior studies have looked at the thalamus, because it is a major sensory relay station. The purpose of our study was to define alterations in metabolites due to injury-induced functional changes in thalamic nuclei by using single-voxel stimulated echo acquisition mode MR spectroscopy. METHODS: Twenty-six men were recruited: 16 patients with SCI and paraplegia (seven with pain, nine without pain) and 10 healthy control subjects. Pain was evaluated in an interview, which included the collection of information concerning the location, quality, and intensity of pain, carefully identifing the dysesthetic neuropathic pain often seen in SCI. Localized single-voxel (8-cm(3) volume) proton spectra were acquired from the left and right thalami. RESULTS: The concentration of N-acetyl (NA) was negatively correlated with pain intensity (r = -0.678), and the t test showed that NA was significantly different between patients with pain and patients without pain (P =.006). Myo-inositol was positively correlated with pain intensity (r = 0.520); difference between patients with pain and those without pain was almost significant (P =.06). CONCLUSION: The observed differences in metabolites in SCI patients with and pain and in those without pain suggest anatomic, functional, and biochemical changes in the thalamic region.

Adult↗