Search PubMed⌕ Search

Biomedical subjects

G G Hartnell

Publications and source records attributed to G G Hartnell.

At least 55 records · Page 3Linked to original sources
PubMed1995

Magnetic resonance angiography of the central chest veins. A new gold standard?

PURPOSE: The systemic chest veins may be difficult to show comprehensively by contrast venography, especially if there is limited venous access or contraindications to intravenous contrast. As an alternative, can magnetic resonance angiography (MRA) reliably detect occluded chest veins and predict suitable sites for central venous access? PATIENTS AND METHODS: Eighty-four patients were examined using breath-hold time-of-flight MRA and three-dimensional image reconstruction. Thirty-three were evaluated to identify possible central venous access. Fifty-seven patients were examined to diagnose and stage central venous occlusion. RESULTS: The associated diagnoses were malignancy 46, parenteral nutrition 21, hemodialysis 6, chemotherapy 4, and other long-term venous access 7. Of the 28 patients in whom MRA predicted a patent site for central venous access, satisfactory access was achieved. In two patients, cannulation of veins shown to be occluded on MRA was attempted unsuccessfully. Correlation with contrast venography was available in 17. There was agreement with MRA concerning the level of occluded veins in all cases. Contrast venography did not show all patent veins, including some accessed during surgical line placement. CONCLUSION: Compared with surgical line placement or contrast venography, MRA of the systemic chest veins is accurate. Patent and occluded chest veins are reliably defined, including potential sites for central line placement, in a way that is not possible with other techniques. MRA may be the new "gold standard" for defining systemic venous anatomy in the chest.

Adult↗
PubMed1995

Percutaneous transfemoral repositioning of malpositioned central venous catheters.

Central venous catheters inserted by blind surgical placement may not advance into a satisfactory position and may require repositioning. Malpositioning via surgical insertion is common in patients in whom central venous catheters have previously been placed, as these patients are more likely to have central venous thrombosis and distortion of central venous anatomy. This is less of a problem when catheter placement is guided by imaging; however, even when insertion is satisfactory, central venous catheters may become displaced spontaneously after insertion (Fig. 1). Repositioning can be effected by direct manipulation using guidewires or tip-deflecting wires [1, 2], by manipulation via a transfemoral venous approach [3-5], and by injection of contrast material or saline [6]. Limitations of the direct approach include (1) the number and type of maneuvers that can be performed to effect repositioning when anatomy is distorted, (2) difficulty in accessing the catheter, and (3) the risk of introducing infection. Moreover, these patients are often immunosuppressed, and there is a risk of introducing infection by exposing and directly manipulating the venous catheter. Vigorous injection of contrast material or saline may be unsuccessful for the same reasons: It seldom exerts sufficient force to reposition large-caliber central venous catheters and may cause vessel damage or rupture if injection is made into a small or thrombosed vessel. We illustrate several alternative methods for catheter repositioning via a transfemoral venous approach.

Adult↗
PubMed1995

Interventional radiology and cross sectional imaging in venous access.

The role of radiology and the interventional radiologist in the care of patients requiring long term venous access is expanding. This role includes multimodality imaging for anatomic evaluation, guided catheter placement or repositioning, and diagnosis and treatment of catheter occlusion or related venous thrombosis. Interventional procedures have been developed for relief of venous obstruction, repositioning of catheters, and placement of unconventional access devices.

Catheterization↗
PubMed1994

Ebstein's anomaly presenting in adulthood: the role of cine magnetic resonance imaging in diagnosis.

Three adult patients with late presentation of Ebstein's anomaly were studied using MRI, including cine MRI. Spin-echo MRI demonstrated a large right atrium in each case and suggested an abnormal tricuspid valve in two. Systolic signal loss, on cine MRI, deep within the right ventricular cavity correctly indicated the presence of an abnormally positioned and incompetent tricuspid valve, and the diagnosis of Ebstein's anomaly in each patient. Selective presaturation MRI demonstrated an associated atrial septal defect in one patient. The diagnosis was confirmed by echocardiography in each case and cardiac catheterization with contrast angiography in one case. Cine MRI clearly demonstrates abnormal tricuspid valve morphology and function in Ebstein's anomaly and is a useful technique when other imaging is unclear.

Adult↗
PubMed1994

Mediastinal Castleman disease: MR and MRA features.

Castleman disease is a rare lymphproliferative disorder that most commonly occurs in the mediastinum. The tumor is very vascular, and biopsy is dangerous. We report magnetic resonance angiography findings, to our knowledge previously undescribed, of prominent feeding vessels; this might draw attention to the possible diagnosis and avoid inappropriate biopsy.

Blood Vessels↗
PubMed1994

Steps in the evolution of extracranial time-of-flight MR angiography.

Magnetic resonance (MR) angiography is not a set technique but is constantly evolving. This article illustrates changes in image quality in extracranial MR angiography that have been achieved over the past few years by the introduction of several technical developments. Images from patients examined at intervals of 12 months or more demonstrate the improvements in image quality that have resulted from these technical changes. These include bandwidth optimization for operation at 1.0 T and changes in flip angle section thickness, repetition time, and echo time. Improved image quality was assessed with objective measures of contrast-to-noise and signal-to-noise ratios. The cases illustrated show the use of MR angiography to evaluate the portal or systemic veins in patients being evaluated for liver transplantation, venous occlusion, and other venous disease. Improvements in image quality are subjectively apparent and emphasize the importance of keeping pace with technical improvements in MR angiography.

Humans↗
PubMed1994

MR imaging of the thoracic aorta: comparison of spin-echo, angiographic, and breath-hold techniques.

PURPOSE: To compare magnetic resonance (MR) angiography and fast MR imaging with spin-echo (SE) and non-MR imaging techniques in examination of the thoracic aorta. MATERIALS AND METHODS: Eighty-nine patients underwent breath-hold or cine MR angiography; SE was used in 67 patients and fast MR imaging in 28. A comparison was made with non-MR imaging (transthoracic echocardiography in 49 patients, transesophageal echocardiography in 18, and arteriography in 33) findings and those from surgery or autopsy (16 patients). RESULTS: MR angiography enabled differentiation of slow flow from thrombus, demonstrated aortic valve anatomy and aortic regurgitation, and accurately showed anatomy with only one error. It demonstrated two communications, flaps, and three branch stenoses better than SE, which produced some artifacts that mimicked thrombus or flaps. Fast MR imaging often produced artifacts or poor image quality (10 of 28 patients). CONCLUSION: Compared with SE MR imaging, MR angiography provides additional useful anatomic and functional information concerning diseases of the thoracic aorta, usually gained only with echocardiography or arteriography.

Aorta, Thoracic↗
PubMed1994

MR angiography as the sole method in evaluating abdominal aortic aneurysms: correlation with conventional techniques and surgery.

PURPOSE: To compare magnetic resonance (MR) angiography with conventional preoperative imaging techniques and surgical findings in the evaluation of abdominal aortic aneurysms (AAAs). MATERIALS AND METHODS: MR angiography was performed in 40 patients with an AAA. Two-dimensional time-of-flight MR angiography with maximum intensity projections was compared with conventional angiography, ultrasound, computed tomography, and surgery. RESULTS: In 18 of 20 patients, MR angiography demonstrated more extensive disease than did angiography. MR angiography depicted 41 of 43 renal arteries and seven of eight renal artery stenoses (one false-negative finding of mild stenosis) identified at angiography. When iliac arteries were imaged (30 patients), good correlation with angiography was seen in all but one patient (resulting from surgical clip artifact). Ten iliac stenoses were seen at both studies. Angiography caused underestimation of the extent of seven iliac aneurysms. CONCLUSION: MR angiography can provide all of the necessary preoperative information for evaluation of AAA and can replace conventional angiography in many cases.

Aged↗
PubMed1994

Developments in echocardiography.

Over the last 25 years, echocardiography has progressed from being an interesting technical achievement to a major cardiac diagnostic tool. Echocardiography has many advantages, including widespread availability, safety, and low cost. These features, combined with its accuracy in providing structural and functional information, have led to its introduction into many areas of cardiac diagnosis. Recent technologic developments have further increased the amount of information provided by echocardiography.

Echocardiography↗
PubMed1993

Correct positioning for cardiac angiography: insights from MRI.

The recommended angiographic projections for optimally demonstrating various cardiac structures vary, and do not always achieve their aim. To determine the most appropriate radiographic projections to optimally demonstrate cardiac structures, we reviewed the orientations of major cardiac structures and the associated great vessels, as demonstrated by axial MRI. Measurements were made from 187 MRI examinations of the heart. These measurements confirmed that the optimum angiographic projections for various cardiac structures are at variance with a number of the recommended views. Recommendations for the angiographic projections most likely to provide optimum display of various cardiac structures and associated great vessels in different patient populations are presented.

Angiocardiography↗
PubMed1993

Are routine chest radiographs prior to angiography of any value?

Chest radiographs are frequently requested prior to diagnostic angiography, though there is no published evidence of their clinical utility. This study was undertaken to evaluate their contribution to patient management. The routine chest radiographs obtained prior to peripheral and coronary angiography in 240 patients were prospectively reviewed for abnormalities likely to affect management. Two hundred and twenty (91.7%) examinations were performed, of which 164 were obtained within 24 h of angiography. Previous radiographs were available in 154 patients (64.2%). One hundred and sixteen radiographs were normal. There were 117 abnormalities on the radiographs of 104 patients, mainly cardiac enlargement and heart failure. No angiogram was postponed or cancelled because of abnormalities detected on a routine radiograph, although radiographic findings led to a change in the volume of contrast medium injected into dilated aortic roots in 10 patients undergoing cardiac catheterization. Pre-angiography radiographs had no effect on the practice of peripheral angiography. In only one patient were further investigations and therapy instigated because of findings, but even in this case these findings were present on previous studies. We conclude that routine pre-angiography chest radiographs are not necessary in the absence of specific clinical indications.

Adult↗
PubMed1993

Limitations of chest radiography in discriminating between aortic dissection and myocardial infarction: implications for thrombolysis.

It has been stated that chest radiographic features of aortic dissection are a contraindication to intravenous thrombolysis in patients with suspected acute myocardial infarction. Excluding aortic dissection could significantly delay such treatment in patients who would benefit from thrombolysis. Initial chest radiographs of 18 patients with acute aortic dissection and 25 patients with acute myocardial infarction were evaluated. The radiographs were studied by two experienced radiologists for signs of aortic dissection. No radiographic signs or combinations of signs accurately distinguished aortic dissection from myocardial infarction. Patients with chest radiographic signs suggesting aortic dissection but with clinical features suggesting myocardial infarction should not be denied the benefits of immediate intravenous thrombolysis.

Aortic Dissection↗
PubMed1993

Ultrasonic thrombus ablation: in vitro assessment of a novel device for intracoronary use.

An ultrasonic thrombolysis device designed for intracoronary use was developed and evaluated in vitro to assess efficacy in achieving clot ablation without deleterious effects, such as heat generation and production of large particles during clot ablation. Studies on 31 samples with a bench-top version demonstrated that clot ablation was rapid (typically 2 mL in under 2 minutes) and no macroscopic particles were released. The fluid produced did not reclot. Studies with a clinical version of the device that can be passed through a 10 Fr PTCA guiding catheter confirmed that clot ablation was rapidly achieved. Little particulate material was produced and the maximum temperature achieved did not exceed 52 degrees C. The device functions well in vitro, releasing little particulate material and causing limited local heating. It seems suitable for intracoronary use and will undergo further in vivo testing.

Catheter Ablation↗