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Ronald A Alberico

Publications and source records attributed to Ronald A Alberico.

9 recordsLinked to original sources
PubMed2005

Intraarterial reteplase and intravenous abciximab for treatment of acute ischemic stroke. A preliminary feasibility and safety study in a non-human primate model.

We performed a preliminary feasibility and safety study using intravenous (IV) administration of a platelet glycoprotein IIb/IIIa inhibitor (abciximab) in conjunction with intraarterial (IA) administration of a thrombolytic agent (reteplase) in a primate model of intracranial thrombosis. We introduced thrombus through superselective catheterization of the intracranial segment of the internal carotid artery in 16 primates. The animals were randomly assigned to receive IA reteplase and IV abciximab ( n =4), IA reteplase and IV placebo ( n =4), IA placebo and IV abciximab ( n =4) or IA and IV placebo ( n =4). Recanalization was assessed by serial angiography during the 6-h period after initiation of treatment. Postmortem magnetic resonance (MR) imaging was performed to determine the presence of cerebral infarction or intracranial hemorrhage. Partial or complete recanalization at 6 h after initiation of treatment (decrease of two or more points in pre-treatment angiographic occlusion grade) was observed in two animals treated with IA reteplase and IV abciximab, three animals treated with IA reteplase alone and one animal treated with IV abciximab alone. No improvement in perfusion was observed in animals that received IV and IA placebo. Cerebral infarction was demonstrated on postmortem MR imaging in three animals that received IA and IV placebo and in one animal each from the groups that received IA reteplase and IV abciximab or IV abciximab alone. One animal that received IV abciximab alone had a small intracerebral hemorrhage on MR imaging. IA reteplase with or without abciximab appeared to be the most effective regimen for achieving recanalization in our model of intracranial thrombosis. Further studies are required in experimental models to determine the optimal dose, method of administration and efficacy of these medications in acute ischemic stroke.

Abciximab↗
PubMed2005

Stereotactic gamma knife surgery for trigeminal neuralgia: detailed analysis of treatment response.

OBJECT: The purpose of this study was to assess the durability and completeness of pain relief in patients treated using stereotactic gamma knife surgery (GKS) for trigeminal neuralgia (TN). METHODS: Thirty-eight patients with refractory TN were treated with stereotactic GKS. All patients received a prescription radiation dose of 35, 40, or 45 Gy to the 50% isodose surface through a 4-mm collimator helmet. The group was assessed regularly based on physician-directed interviews for a median follow up of 24 months (range 6-27 months). Pain relief was classified as excellent (no pain without medication), good (well-controlled pain with continued medication), fair (decreased but residual pain with continued medication), or poor (unimproved or increased pain with the same or increased medication). Three months after treatment, pain relief was good or excellent in 71% of patients. By 24 months post-GKS, 50% of the original cohort had poor pain relief, 21% continued to have either excellent or good relief, 3% had fair relief, and 26% had not reached the 24-month follow up. Based on their status at the last follow up, 29% of patients had excellent and 16% had good pain relief. Thirty-seven percent experienced facial numbness, which was dose related. In addition, there was a significantly higher rate of complete pain relief in patients who had facial numbness following treatment (p = 0.003). CONCLUSIONS: Stereotactic GKS is an effective treatment in patients with TN; however, the durability of pain relief and the time to treatment response are limiting factors. As with other types of ablative treatment, facial numbness is strongly associated with better treatment response.

Adult↗
PubMed2004

Imaging in head and neck oncology.

Evaluation of head and neck cancer with imaging is a topic that is far more extensive than can be covered in this article. The main reason for head and neck imaging is to evaluate the true extent of disease to best determine surgical and therapeutic options. This process includes evaluation of the size, location, and extent of tumor infiltration into surrounding vascular and visceral structures. Important anatomic variants must be pointed out so the surgeon can avoid potential intraoperative complications. These variant scan be evaluated with the appropriate multiplanar and three-dimensional images to provide as much information as possible to the surgeon preoperatively. Second, nodal staging should be assessed in an effort to increase the number of abnormal nodes detected by physical examination and, more important, to precisely define their location by a standard classification system that can be understood and consistently applied by the radiologist, surgeon, radiation oncologist, and pathologist. Although secondary to the previously described tasks, imaging frequently enables a limitation of the diagnostic and histologic possibilities based on lesion location and signal-attenuation characteristics, which may lead the clinical investigation along a different path. saving the patient unnecessary risk and shortening the time to diagnosis and ultimate treatment. This article has attempted to detail the current state of the controversy between CT, MRI, and other modalities, and has emphasized the constant evolution of this controversy because of the evolving imaging technology. Although CT and MRI are both well suited to evaluation of the deep spaces and submucosal spaces of the head and neck, each has some limitations.MRI has the advantages of higher soft tissue contrast resolution, the lack of iodine-based contrast agents, and high sensitivity for perineural and intracranial disease. The disadvantages of MRI include lower patient tolerance, contraindications in pacemakers and certain other implanted metallic devices, and artifacts related to multiple causes, not the least of which is motion. CT is fast, well tolerated, and readily available but has lower contrast resolution and requires iodinated contrast and ionizing radiation. The current authors' practice is heavily centered on CT for initial evaluation, preoperative planning, biopsy targeting, and postoperative follow-up. They reserve MRI for tumors that are suspicious for perineural,cartilaginous, or bony invasion on CT, or for tumors such as adenoid cystic carcinoma that are highly likely to spread by way of these routes. For patients who have head and neck cancer, a radiologist who is educated in the treatment options, patterns of tumor growth, and important surgical landmarks, and who has a well-established pattern of communication with the head and neck clinical services, including surgery, radiation oncology,and pathology, is key in providing accurate and useful image interpretation.

Carcinoma, Squamous Cell↗
PubMed2003

In vivo model of intracranial stent implantation: a pilot study to examine the histological response of cerebral vessels after randomized implantation of heparin-coated and uncoated endoluminal stents in a blinded fashion.

OBJECT: No animal model currently exists for the examination of time-dependent histological changes occurring in intracranial vessels after endoluminal stent placement. The authors' goal was to develop a reproducible in vivo model of stent implantation in intracranial vessels in dogs that was capable of demonstrating stent-related vascular changes after the implantation of coated and uncoated devices. METHODS: The authors implanted heparin-coated or uncoated stents in the basilar arteries (BAs) of 11 mongrel dogs. In a 12th animal, one coated stent was implanted in the BA and a second uncoated one was implanted in the distalanterior spinal artery. All the devices were oversized to induce intimal injury. Surviving animals were observed for 12 weeks, after which they underwent repeated angiography before planned death and removal of the brain. Histological studies and computer-assisted morphometric analyses were conducted on stent-treated and untreated sections of the BAs to assess the percentage of stenosis, neointimal proliferation, vessel injury, and inflammation. Perforating vessels partially covered by stent struts ("jailing") were studied for evidence of stenosis or occlusion. The pathologist, interventionists, histopathologist, histopathology technicians, and radiologist were blinded to the stent type. Seven stents (three uncoated and four coated) were removed from the six animals that were observed during the follow-up period. The mean neointimal proliferation was 0.42 mm2 in the group treated with uncoated stents and 0.18 mm2 in the group treated with heparin-coated devices (p = 0.04). Neointimal thickness was significantly increased in the group with uncoated stents (p = 0.04). The mean percentage of occlusion was less (12%) in the group with heparin-coated stents, compared with 22% in the group with uncoated devices (p = 0.07). When comparing results between the heparin-coated and uncoated devices implanted in the five animals that received a single stent only, greater differences (indicating a benefit from heparin-coated stents) were observed in neointimal area (p = 0.009), neointima/media ratio (p = 0.001), neointimal thickness (p = 0.002), and percentage of occlusion (p = 0.009). All brainstem perforating vessels covered by stent struts remained patent. CONCLUSIONS: This in vivo intracranial stent model was developed to assess proliferative and inflammatory responses to endoluminal stent implantation in the cerebrovasculature. The results indicate that a lower percentage of occlusion occurs 12 weeks after implantation of heparin-coated compared with uncoated stents.

Angiography↗
PubMedDate not supplied

Chlorophyll-a analogues conjugated with aminobenzyl-DTPA as potential bifunctional agents for magnetic resonance imaging and photodynamic therapy.

A clinically relevant photosensitizer, 3-devinyl-3-(1-hexyloxyethyl)pyropheophorbide-a (HPPH, a chlorophyll-a derivative), was conjugated with Gd(III)-aminobenzyl-diethylenetriaminepentaacetic acid (DTPA), an experimental magnetic resonance (MR) imaging agent. In vivo reflectance spectroscopy confirmed tumor uptake of HPPH-aminobenzyl-Gd(III)-DTPA conjugate was higher than free HPPH administered intraveneously (iv) to C3H mice with subcutaneously (sc) implanted radiation-induced fibrosarcoma (RIF) tumor cells. In other experiments, Sprague-Dawley (SD) rats with sc implanted Ward Colon Carcinoma cells yielded markedly increased MR signal intensities from tumor regions-of-interest (ROIs) 24 h post-iv injection of HPPH-aminobenzyl-Gd(III)-DTPA conjugate as compared to unconjugated HPPH. In both in vitro (RIF tumor cells) and in vivo (mice bearing RIF tumors and rats bearing Ward Colon tumors) the conjugate produced significant increases in tumor conspicuity at 1.5 T and retained therapeutic efficacy following PDT. Also synthesized were a series of novel bifunctional agents containing two Gd(III) atoms per HPPH molecule that remained tumor-avid and PDT-active and yielded improved MR tumor conspicuity compared to their corresponding mono-Gd(III) analogues. Administered iv at a MR imaging dose of 10 micromol/kg, these conjugates produced severe skin phototoxicity. However, by replacing the hexyl group of the pyropheophorbide-a with a tri(ethylene glycol) monomethyl ether (PEG-methyl ether), these conjugates produced remarkable MR tumor enhancement at 8 h post-iv injection, significant tumoricidal activity (80% of mice were tumor-free on day 90), and reduced skin phototoxicity compared to their corresponding hexyl ether analogues. The poor water-solubility characteristic of these conjugates was resolved by incorporation into a liposomal formulation. This paper presents the synthesis of tumor-avid contrast enhancing agents for MR imaging and thus represents an important milestone toward improving cancer diagnosis and tumor characterization. More importantly, this paper describes a new family of bifunctional agents that combine two modalities into a single cost-effective "see and treat" approach, namely, a single agent that can be used for contrast agent-enhanced MR imaging followed by targeted photodynamic therapy.

Aminobenzoates↗
PubMedDate not supplied

Gadolinium-enhanced computed tomographic angiography: current status.

This article reviews the research to date, as well as our clinical experience from two institutions, on gadolinium-enhanced computed tomographic angiography (gCTA) for imaging the body. gCTA may be an appropriate examination for the small percentage of patients who would benefit from noninvasive vascular imaging, but who have contraindications to both iodinated contrast and magnetic resonance imaging. gCTA is more expensive than CTA with iodinated contrast, due to the dose of gadolinium administered, and gCTA has limitations compared with CTA with iodinated contrast, in that parenchymal organs are not optimally enhanced at doses of 0.5 mmol/kg or lower. However, in our experience, gCTA has been a very useful problem-solving examination in carefully selected patients. With the advent of 16-64 detector CT, in combination with bolus tracking, we believe that the overall dose of gadolinium needed for diagnostic CTA examinations, while relatively high, can be safely administered.

Angiography↗
PubMedDate not supplied

Gadopentetate dimeglumine is potentially an alternative contrast agent for three-dimensional computed tomography angiography with multidetector-row helical scanning.

OBJECTIVE: To demonstrate that gadopentetate dimeglumine is potentially an alternative contrast medium for computed tomographic angiography (CTA). METHODS: One 12.2-kg Beagle dog was studied as proof of principle; the cervical vessels of three adult human patients were imaged for presurgical planning of the neck. Gadopentetate dimeglumine, 0.5 mol/l (Berlex Laboratories, Wayne, NJ, U.S.A.), a LightSpeed QX/i CT (General Electric Medical Systems, Milwaukee, WI, U.S.A.), and an Ultra Sparc II (SUN Microsystems, Santa Clara, CA, U.S.A.) running Advantage Windows 3.1 (General Electric Medical Systems) were used. RESULTS: Sufficient enhancement for CTA of the thoracic aorta, cervical vessels, and abdominal vessels was produced in the experimental dog, and the cervical vessels were clearly defined in all three patients. CONCLUSION: In that subset of patients with contraindications to iodinated contrast medium and for whom magnetic resonance angiography is inappropriate, gadopentetate dimeglumine may be an alternative contrast medium for CTA.

Angiography↗