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Clifford R Weiss

Publications and source records attributed to Clifford R Weiss.

12 recordsLinked to original sources
PubMed2006

CT pulmonary angiography is the first-line imaging test for acute pulmonary embolism: a survey of US clinicians.

RATIONALE AND OBJECTIVES: Our aim is to document current imaging practices for diagnosing acute pulmonary embolism (PE) among physicians practicing in the United States and explore factors associated with these practices. MATERIALS AND METHODS: Between September 2004 and February 2005, we surveyed by mail 855 physicians selected at random from membership lists of three professional organizations. Physicians reported their imaging practices and experiences in managing patients with suspected acute PE during the preceding 12 months. RESULTS: Completed questionnaires were received from 240 of 806 eligible participants (29.8%) practicing in 44 states: 86.7% of respondents believed that computed tomographic pulmonary angiography (CTPA) was the most useful imaging procedure for patients with acute PE compared with 8.3% for ventilation-perfusion (V-P) scintigraphy and 2.5% for conventional pulminary angiography (PA). After chest radiography, CTPA was the first imaging test requested 71.4% of the time compared with V-P scintigraphy (19.7%) and lower-limb venous ultrasound (5.8%). Participants received indeterminate or inconclusive results 46.4% of the time for V-P scintigraphy, 10.6% of the time for CTPA, and 2.2% of the time for PA. CTPA was available around the clock to 88.3% of participants compared with 53.8% for V-P scintigraphy and 42.5% for PA. A total of 68.6% of respondents received CTPA results in 2 hours or less (vs 37.5% for V-P scintigraphy and 22.9% for PA). CTPA also provided an alternative diagnosis to PE or showed other significant abnormalities 28.5% of the time, and these findings frequently altered management. CONCLUSION: US clinicians unequivocally prefer CTPA in patients with suspected acute PE. Reasons for this preference include availability and timely reporting, a lower rate of inconclusive results, and the additional diagnostic capabilities that CTPA can provide.

Angiography↗
PubMed2006

Scanning systems and protocols used during imaging for acute pulmonary embolism: how much do our clinical colleagues know?

RATIONALE AND OBJECTIVES: The imaging systems and protocols used during ventilation-perfusion lung (V-P) scintigraphy and computed tomographic (CT) pulmonary angiography (CTPA) can affect diagnostic performance. We investigated the level of awareness of these factors among US clinicians who refer patients for imaging for suspected acute pulmonary embolism. MATERIALS AND METHODS: Between September 2004 and February 2005, we conducted a mail survey of 855 physicians selected at random from three professional organizations. We asked participants how important the availability of state-of-the-art equipment was in their imaging decisions, whether V-P scintigraphy was performed with planar or single-photon emission CT (SPECT) equipment in their communities, to identify the most advanced type of CT scanner used for CTPA, and whether CT venography (CTV) was performed routinely after CTPA. RESULTS: We received completed surveys from 240 (29.8%) physicians practicing in 44 states. One hundred sixty-six respondents (70.9%) indicated that state-of-the-art equipment was an extremely or very important factor when they made imaging decisions. However, 191 clinicians (80.3%) did not know whether SPECT equipment was used for V-P scintigraphy, and 119 (50.6%) did not know the type of CT scanner used for CTPA in their communities. Of respondents, 39.2% reported access to multidetector row CT technology for CTPA, whereas 10.2% referred patients to facilities using single-detector CT. Only 9.3% of respondents indicated that CTV was performed routinely after CTPA. CONCLUSION: Although state-of-the-art equipment is important to them, clinicians practicing in the United States have limited knowledge of the equipment being used during CTPA and V-P scintigraphy scanning in their communities. Radiologists should intensify efforts to familiarize their clinical colleagues with the equipment they use.

Attitude of Health Personnel↗
PubMed2006

Intrabiliary MR imaging: assessment of biliary obstruction with use of an intraluminal MR receiver coil.

PURPOSE: The primary aim of this study was to determine whether intrabiliary magnetic resonance (MR) imaging is feasible in a clinical setting and to optimize MR imaging parameters for the technique. In addition, it was attempted to determine the accuracy of intrabiliary MR imaging in the setting of biliary obstruction of unknown cause. MATERIALS AND METHODS: Intrabiliary MR was performed prospectively in 15 patients with biliary obstruction of unknown cause. A 0.030-inch MR intravascular receiver coil was placed in an existing biliary tube. Intrabiliary MR was performed on a 1.5-T system. T1-weighted, T2-weighted, and single-shot fast spin-echo images were acquired. T1-weighted images were also acquired after the administration of a gadolinium contrast agent. Signal intensity analysis was conducted in the region of the common bile duct. Accuracy of intrabiliary MR, computed tomography (CT), MR, and cholangiography were determined by correlation with surgical pathologic findings. RESULTS: Intrabiliary MR was successfully performed in 14 of 15 patients. MR examinations were performed in less than 1 hour. The signal-to-noise ratio in the region of the common bile duct with the intrabiliary MR technique was increased by a factor of 9 compared with standard surface-coil MR imaging (P < .00001). The mean n-plane resolution achieved was 740 +/- 20 microm x 1,150 +/- 20 microm obtained with use of a field of view of 18 cm x 18 cm (range, 15-24 cm) and a matrix of 256 x 160. Of the pulse sequences tested, the gadolinium-enhanced T1-weighted image was the best for identifying tumor and delineating tumor margins. Intrabiliary MR had a higher sensitivity than CT (100% vs 50%), a higher specificity than cholangiography (80% vs 20%), and a better correlation (P = .015) with surgical pathologic findings than CT, MR imaging, or cholangiography. CONCLUSIONS: Intrabiliary MR was well tolerated in a clinical setting and provided high spatial resolution and excellent contrast between the biliary lumen and adjacent structures. Intrabiliary MR demonstrated an advantage in detecting the presence or absence of biliary malignancies compared with currently available standard imaging techniques. The technique may be useful to evaluate biliary obstruction of unknown cause.

Cholangiography↗
PubMed2005

Constitutively active HIF-1alpha improves perfusion and arterial remodeling in an endovascular model of limb ischemia.

OBJECTIVE: Hypoxia-inducible factor 1 (HIF-1) regulates the expression of angiogenic growth factors. We analyzed the effect of intramuscular (i.m.) delivery of AdCA5, an adenovirus encoding a constitutively active form of the HIF-1alpha subunit, in a novel model of limb ischemia. METHODS: AdCa5 or AdLacZ (6 x 10(8) pfu) was injected into male New Zealand White rabbits that were untreated or subjected to occlusion of the left superficial femoral artery by endovascular coils. Expression of mRNAs was quantified 1, 3, and 7 days after adenovirus injection into rabbits without occlusion. Calf blood pressure (BP), angiography, and immunohistochemical analyses were performed 14 days after arterial occlusion and adenovirus injection. RESULTS: AdCA5 increased the expression of HIF-1alpha, monocyte chemotactic protein-1, placental growth factor, platelet-derived growth factor B, stromal-derived factor 1alpha, and vascular endothelial growth factor (VEGF) mRNA as well as HIF-1alpha and VEGF protein. On day 14, AdCA5-injected limbs showed improved calf BP ratios (0.89+/-0.13 vs. 0.51+/-0.05, p=0.02), angiographic perfusion scores (3.50+/-0.56 vs. 8.33+/-1.31, p=0.007), and distal deep femoral artery diameter ratio (1.84+/-0.25 vs. 0.93+/-0.22, p=0.02) relative to those receiving AdLacZ. The capillary/myocyte ratio (0.93+/-0.03 vs. 0.78+/-0.06, p=0.04) and arterial luminal area (0.32+/-0.05 mm2 vs. 0.21+/-0.03 mm2, p=0.04) were significantly increased in the AdCA5 group. CONCLUSION: In a model that resembles atherosclerotic obstruction of peripheral arteries in patients, the i.m. administration of AdCA5 promoted arteriogenic and angiogenic responses.

Adenoviridae↗
PubMed2005

Multidetector 3D CT of pulmonary embolism of a peripheral intravenous line.

Embolization of foreign objects to the pulmonary circulation is an uncommon occurrence. Traditionally, plain radiographs have been used to detect larger, radiodense objects, with axial CT used to localize smaller, less radiodense objects. More recently, the use of multidetector CT has permitted the detection and accurate localization of smaller, relatively radiolucent objects. This case demonstrates the utility of multidetector 3D CT to localize a small, subtle peripheral venous catheter, which can be easily missed on axial CT.

Adult↗
PubMed2005

Intrabiliary MR imaging.

The goal of this research is to illustrate the potential role of interventional MR imaging ina clinical setting. As shown by this study, IBMR is feasible, is well tolerated, and positively affects patient management. IBMR allowed for significantly decreased field of view and high in-plane resolution and provided contrast between the biliary lumen and adjacent structures with high diagnostic accuracy. This technique enabled clinicians not only to improve imaging of the biliary tree but also to make a more accurate diagnosis. Based on this pilot work, there are several potential avenues of further expansion for IBMR. For example, enhanced imaging of the biliary tree may allow for monitoring of new biliary treatment regimens such as photodynamic therapy or molecular targeting. In addition, this technique may also foster development of innovative new percutaneous procedures that may eventually treat some biliary disorders under MR imaging guidance.

Cholestasis, Intrahepatic↗
PubMed2005

Endovascular model of rabbit hindlimb ischemia: a platform to evaluate therapeutic angiogenesis.

PURPOSE: Current animal hindlimb ischemia models involve surgical ligation of the femoral artery and delivery of therapeutic angiogenic agents into the adductor compartment. The authors hypothesize that an endovascular model of hindlimb ischemia would be a more appropriate platform, closely resembling atherosclerosis by occluding the vessel from within, causing less inflammation, wound healing and subsequent collateralization. MATERIALS AND METHODS: The left superficial femoral artery in 17 rabbits was occluded by endovascular coil embolization (n=9) or surgical ligation (n=8). Animals (n=3; in each group) were sacrificed on day 3 to determine the arteriolar luminal area, number of arterioles, microsphere determined perfusion, and degree of inflammation. On day 28, the remaining animals underwent calf blood pressure measurements and angiography to determine the number of collaterals and diameter of vessels supplying the hindlimb. RESULTS: Immediate postprocedure (day 0) and presacrifice (day 3 or 28) occlusion rates were 89% (eight of nine rabbits) and 100% for the endovascular model; 100% and 100% for the surgical model, respectively. Hindlimb paralysis and muscle atrophy was found in one surgical animal. On day 3, there was an increase in hindlimb perfusion (surgery, 0.04+/-0.01; endovascular, 0.02+/-0.01; P=.02), an increase in arteriolar luminal area (surgery, 481 microm+/-240; endovascular, 345 microm+/-151; P=.04), and a trend toward more inflammation (surgery, 5.5+/-3.8; endovascular, 2.5+/-3.0; P=.08) in the surgical group. There was no difference in number of vessels between both groups. On day 28 there was no difference in the calf blood pressure ratios or in the number of collaterals. However, there was enlargement of the distal profunda femoris artery, the vessel closest to the surgical incision, in the surgical group (L/R ratio: immediate post-occlusion, 1.06+/-0.11; day 28, 1.27+/-0.08; P=.02). CONCLUSION: The endovascular model was efficacious in providing occlusion of the superficial femoral artery, and induced less of an arteriogenic response compared with the surgical model. The authors believe that this endovascular model is a superior platform for studying therapeutic angiogenic agents.

Angiogenesis Inducing Agents↗
PubMed2004

Therapeutic angiogenesis: the next frontier for interventional radiology.

The field of interventional radiology has traditionally relied on mechanical methods to treat vascular disease, such as angioplasty balloons and stents. Although there have been a number of important technical advances in endovascular devices, there are still a number of patients who are not candidates for percutaneous or surgical revascularization. As we approach the technical limits of these newer devices, therapeutic angiogenesis may play an ever-increasing role in the future. Interventional radiologists have unique delivery skills that would complement the on-going research in this area. It is the goal of this article to serve as a primer for interventional radiologists on the agents and techniques used in this exciting field.

Angiogenesis Inducing Agents↗
PubMed2004

Extracorporeal expulsion of a vascular endograft used to treat a mycotic aneurysm.

A 65-year-old woman with a right common iliac artery mycotic aneurysm and an overlying sacral pressure ulcer was treated with placement of a vascular endograft. The mycotic aneurysm was successfully excluded, but 3 months after the procedure, the endograft was expelled through the wound. Fortunately, the patient had minimal clinical sequelae. This case emphasizes the importance of frequent noninvasive imaging of mycotic aneurysms treated with endografts. A rigorous postoperative imaging protocol is proposed based on the current regimen for abdominal aortic aneurysm surveillance after endograft implantation.

Aged↗
PubMed2003

Stunned, infarcted, and normal myocardium in dogs: simultaneous differentiation by using gadolinium-enhanced cine MR imaging with magnetization transfer contrast.

PURPOSE: To simultaneously differentiate stunned, infarcted, and normal myocardial regions by using gadolinium-enhanced cine magnetic resonance (MR) imaging with magnetization transfer contrast. MATERIALS AND METHODS: Twelve dogs were imaged on days 1 and 8 after transient 90-minute coronary artery occlusion. A magnetization transfer contrast with echo-train readout (MTET) MR sequence was performed before and 30 minutes after gadolinium contrast enhancement. Ex vivo analysis consisted of MR imaging, microsphere blood flow analysis, and triphenyltetrazolium chloride (TTC) staining. A paired two-tailed t test was used to compare wall thickening from day 1 to day 8. Linear regression and Bland-Altman analyses were used to compare infarct size depicted with MTET imaging with that seen on TTC-stained tissue. RESULTS: Severe wall motion abnormalities were detected in all dogs. At TTC analysis, seven dogs had evidence of myocardial infarction and five had evidence of stunned myocardium. The mean percentages of left ventricular wall thickening in infarcted, stunned, and remote myocardial regions were 2% +/- 4 (SD), 4% +/- 8, and 33% +/- 5, respectively. Wall thickening did not improve in the infarcted zones, but it improved to nearly normal levels in the stunned region 1 week after induced occlusion (mean, 40% +/- 8; P <.02). MTET images clearly depicted infarcted myocardium as brighter than both the normal and stunned myocardial regions but darker than the blood pool. In vivo MTET infarct volume correlated with ex vivo TTC analysis data (y = 1.01x + 0.00, R = 0.98, standard error of the estimate = 0.019). CONCLUSION: One day after myocardial ischemia, MTET during one MR imaging examination enabled simultaneous differentiation of infarcted, stunned, and normal myocardial regions on the basis of gadolinium enhancement and regional function.

Animals↗
PubMedDate not supplied

Computed tomography appearance of an intra-aortic balloon pump: a potential pitfall in diagnosis.

The case of a patient with an indwelling intra-aortic balloon pump (IABP) who underwent computed tomography (CT) to rule out mesenteric ischemia is reported. Three-dimensional reconstruction revealed regularly spaced air-fluid levels within the aorta. Intra-aortic balloon pump function is reviewed, and it is shown that its artifactual appearance on CT results from the phase difference between the cardiac cycle and gantry speed. Recognizing and understanding the appearance of an IABP is important so as not confuse it with intra-aortic air, which suggests ischemia.

Angioplasty, Balloon, Coronary↗