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Biomedical subjects

R I White

Publications and source records attributed to R I White.

At least 37 records · Page 2Linked to original sources
PubMed1994

Staging of mediastinal non-small cell lung cancer with FDG PET, CT, and fusion images: preliminary prospective evaluation.

PURPOSE: To evaluate use of positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) in detection of mediastinal lymph node metastases from non-small cell lung cancer. MATERIALS AND METHODS: A prospective trial to compare FDG PET and computed tomography (CT) of the thorax was performed in 23 patients with newly diagnosed or suspected non-small cell lung cancer. Blinded interpretations of CT alone, PET alone, CT and PET together, and fusion images were performed, and the results were compared with pathologic results. RESULTS: Nineteen of 23 patients had non-small cell lung cancer. Prevalence of mediastinal involvement was 41%. In staging disease in the mediastinum, CT alone was 64% sensitive, 44% specific, and 52% accurate, whereas PET alone and fusion images were 82% sensitive, 81% specific, and 81% accurate (P < .05). CONCLUSIONS: FDG PET was more accurate than CT in staging disease in the mediastinum in patients with lung cancer and appears to be the preferred imaging method in this clinical setting.

Carcinoma, Non-Small-Cell Lung↗
PubMed1994

Clinical results of transvenous systemic embolotherapy with a neuroradiologic detachable balloon.

PURPOSE: To evaluate the efficacy of transvenous systemic embolotherapy with a neuroradiologic detachable balloon. MATERIALS AND METHODS: As part of a clinical trial, a detachable silicone balloon was used to occlude pulmonary arteriovenous malformations (PAVMs) in 35 patients and varicocele in 14 patients. In patients with PAVM, the indications for embolotherapy were prophylaxis against paradoxic embolization (n = 35) and dyspnea, fatigue, or both (n = 26); in patients with varicocele, they were pain or a discomforting lesion (n = 8) or infertility (n = 6). RESULTS: Balloon embolotherapy was successful in 79 (98%) of the 81 lesions in which it was attempted; 29 (37%) of these 79 balloons were used in conjunction with coils. Ninety-six (97%) of 99 balloons were successfully placed; the three technical failures had no substantial clinical sequelae, and in all three, occlusion was eventually achieved with either detachable balloons or coils. Of six late deflations, five occurred in balloons placed adjacent to coils; only one, which occurred between 1 day and 21 days after placement, resulted in recanalization. CONCLUSION: Transvenous embolization with this detachable balloon was relatively simple and provided cross-sectional occlusion of PAVMs and varicocele.

Angiography, Digital Subtraction↗
PubMed1994

Life-threatening pulmonary hemorrhage with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia.

The occurrence of significant pulmonary hemorrhage associated with pulmonary arteriovenous malformations (PAVMs) and hereditary hemorrhagic telangiectasia (HHT) and the incidence of PAVMs in family members of patients with PAVMs and HHT are poorly defined. We reviewed our experience in 143 patients with PAVMs and HHT. Eleven (8 percent) of the 143 patients with HHT and PAVMs had a history of either massive hemoptysis or of hemothorax which required hospitalization. One patient died directly related to the pulmonary hemorrhage. There were four men and seven women. Three of the seven women experienced pulmonary hemorrhage during pregnancy. Seven of the 11 families participated in screening for PAVMs. Thirty-six (80 percent) of the 45 screened family members were found to have HHT. Thirteen (36 percent) of the 36 family members with HHT were proven to have PAVMs by pulmonary angiography. Pulmonary hemorrhage due to spontaneous rupture of the PAVM is a potentially life-threatening complication that should be treated aggressively with transcatheter embolotherapy. It occurs more frequently than previously recognized in patients with PAVMs and HHT. In addition, because of the increased incidence of PAVMs in family members of patients with HHT and PAVM, screening of family members with HHT is recommended especially in women of childbearing age.

Adolescent↗
PubMed1992

In vivo evaluation of iophendylate-cyanoacrylate mixtures.

Cyanoacrylate glue is a rapidly polymerizing agent used for vascular embolization. Polymerization occurs when the glue comes into contact with ions in the blood or on the vascular endothelium. Mixing iophendylate with cyanoacrylate causes slowing of polymerization, allowing flow-directed embolization into the nidus of an arteriovenous malformation (AVM) or the central neovascularity of a tumor or hemangioma. The authors attempted to define the relationship between the iophendylate-glue ratio and polymerization time with an in vivo swine model. In this model, glue setup occurred much more rapidly than predicted on the basis of in vitro studies. This appeared to be due to glue polymerizing on the endothelium at vessel bifurcations and at areas of acute angulation or marked vessel narrowing. On the basis of these data, the authors substantially increased the iophendylate-glue ratio in their most recent AVM embolization procedures and achieved nidus occlusion in each case. With use of the authors' guidelines, it is possible to achieve optimal distal flow-directed embolization with cyanoacrylate.

Angiography↗
PubMed1991

Experimental treatment of thrombotic vascular occlusion.

The role of laser energy in the treatment of thrombotic vascular occlusion was evaluated in two sets of experiments. First, 10 polytetrafluoroethylene grafts were used to replace segments of the superficial femoral arteries in dogs and were thrombosed by distal ligation. Occlusion was maintained for one hour, or for 7, 14, 21, and 28 days in each of two grafts. Patency was restored in all 10 grafts without perforation or anastomotic disruption using a 2 mm hot tip probe powered by an Argon laser. However, increased organization of thrombus related to the duration of occlusion lead to decreased laser channel diameters, and 75% of the 28 day thrombus remained in the graft after recanalization. The second experiments tested the added benefit of thrombolytic infusion following laser recanalization. Bilateral external iliac artery thrombosis was induced in dogs by operative vessel isolation, de-endothelialization, and thrombin injection. At 7 days the efficacy of laser-assisted thrombolysis (LAT) versus enzymatic thrombolysis (ET) alone was compared. Eight vessels underwent ET by urokinase (4000 I.U./min.); 14 vessels were laser recanalized prior to thrombolytic infusion. LAT was performed from a carotid artery approach in 8 vessels (antegrade) and from a femoral artery in 6 vessels (retrograde). In contrast to studies using the hot tip alone, both ET and LAT accomplished complete thrombus removal. However, LAT lead to significant iliac arterial flow in 9 +/- 8 min. (antegrade) and 25 +/- 8 min. (retrograde) while ET required 109 +/- 47 min (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Transcatheter detachable balloon embolotherapy for catheter-induced pulmonary artery pseudoaneurysm.

Pulmonary artery pseudoaneurysm formation may be due to various etiologies, including trauma, pulmonary artery catheterization, infection, and tumor. Transcatheter embolization is a nonsurgical management technique that may be utilized in many of these patients to occlude the affected artery and to prevent further extravasation. Recently, two patients with pulmonary artery pseudoaneurysm formation after balloon-tipped catheter placement were successfully managed with transcatheter embolotherapy with detachable silicone balloons. The article describes their diagnosis and management.

Aged↗
PubMed1991

The natural history of epistaxis in hereditary hemorrhagic telangiectasia.

The purpose of this retrospective study is to document the natural history of epistaxis in patients with hereditary hemorrhagic telangiectasia. A telephone questionnaire was administered to 73 patients who had been previously screened for pulmonary arteriovenous malformations (PAVMs). The incidence of epistaxis in this population was 93%, with a mean onset age of epistaxis of 12 years, a mean frequency of bleeding of 18 episodes per month, and a mean duration of bleeding of 7.5 minutes. More than 90% of patients experienced the onset of epistaxis before the age of 21 and symptoms were progressive with age. There were no differences in the age of onset, frequency of epistaxis, or duration of epistaxis between patients with PAVMs versus those without PAVMs. Although the natural history of epistaxis does not predict the presence or absence of pulmonary arteriovenous malformations, epistaxis is an early marker of the disease, hereditary hemorrhagic telangiectasia, and might guide screening for pulmonary and cerebral arteriovenous malformations in children of affected parents.

Adolescent↗
PubMed1990

Ex-vivo results using a new pullback atherectomy catheter (PAC).

In order to evaluate the feasibility of performing definitive atheromatous plaque removal using a novel retrograde cutting (Pullback) atherectomy catheter, pullback atherectomy was performed in 13 severely diseased cadaveric superficial femoral arteries. All experiments were performed using cadaver tissue either mounted in a perfusion/mounting chamber (n = 10) or left in situ (n = 3). In general, a single cut was made with each of three sequentially larger atherectomy catheters (2.5 mm, 3.0 mm, and then 3.5 mm devices). The results were evaluated by angiography and by light microscopy. Nine of the 13 experiments were performed in totally occluded vessels. The mean pre-atherectomy stenosis (all specimens) was 95 +/- 3%, with a final mean postatherectomy stenosis of 21 +/- 5%. There was one vessel performation. We conclude from these preclinical studies that retrograde atherectomy with the Pullback Atherectomy Catheter is a feasible means of performing definitive atherectomy. Despite the promising potential of retrograde atherectomy, little can be said with certainty about the clinical utility of such a device at this early stage.

Arteriosclerosis↗
PubMed1990

Status of admitting privileges for university-affiliated diagnostic radiology departments.

Members of the Society of Chairmen of Academic Radiology Departments (SCARD) from 135 university hospitals in Canada and the United States were surveyed regarding their experience in admitting patients to diagnostic radiology departments between 1986 and 1989. One hundred departments (74%) replied; of these, 33 departments (33%) admitted patients during 1989. From 1986 to 1989 the percentage of diagnostic radiology departments admitting patients rose from 20% to 33%. Forty-one departments had admitting privileges, and nine departments had applied for admitting privileges. The remaining 50 departments were content to admit patients to medical and/or surgical services or had no interest in obtaining admitting privileges. The rapid growth of noncardiac interventional procedures, the obvious benefit to patients whose disease is manageable with imaging-guided therapy, the increasing interest of nonradiologists in performing interventional radiologic procedures, and the potential financial benefits to the hospital that are associated with short patient stays provide incentive for diagnostic radiologists to admit patients for cardiovascular and interventional procedures.

Hospital Departments↗
PubMed1989

Ocular manifestations in hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease).

Although hereditary hemorrhagic telangiectasia is a cause of blood tears from the conjunctival telangiectasias, visual loss from intraocular vascular malformations is a rare complication. We examined 20 patients with hereditary hemorrhagic telangiectasia to determine the prevalence of ocular abnormalities in this disease. Seven patients (35%) had conjunctival telangiectasias and two (10%) had retinal vascular malformations.

Adolescent↗
PubMed1989

Benign postoperative biliary strictures. Operate or dilate?

At The Johns Hopkins Hospital from 1979 through 1987, 42 patients had 45 procedures for benign postoperative biliary strictures. Three patients were managed with both surgery and balloon dilatation. Twenty-five patients underwent surgical repair with Roux-Y choledocho- or hepaticojejunostomy with postoperative transhepatic stenting for a mean of 13.8 +/- 1.3 months. Twenty patients had balloon dilatation a mean of 3.9 times and were stented transhepatically for a mean of 13.3 +/- 2.0 months. The two groups were similar with respect to multiple parameters that might have influenced outcome. Mean length of follow-up was 57 +/- 7 and 59 +/- 6 months for surgery and balloon dilatation, respectively. No patients died after any of the procedures. The same definition of a successful outcome was applied to both groups and was achieved in 88% of the surgical and in only 55% of the balloon dilatation patients (p less than 0.02). Significant hemobilia occurred more often with balloon dilatation (20% vs. 4%, p less than 0.02). The total hospital stay and cost of balloon dilatation was not significantly different from surgery. We conclude that surgical repair of benign postoperative strictures results in fewer problems that require further therapy. Nevertheless balloon dilatation is an alternative for patients who are at high risk or who are unwilling to undergo another operation.

Catheterization↗
PubMed1989

Porcine model for the development of interventional techniques in the gallbladder.

A technique that permits repeated access to the porcine gallbladder through a surgically placed 18 French latex catheter is described and experience with this system in 22 swine is discussed. This porcine gallbladder model produces a reliable and reproducible means for studying clinically applicable interventional procedures.

Abdominal Muscles↗