ABSTRACTS 757

possible risk of nosocomial transmission of blood borne pathogens. The aim of this study is to document the risk of contamination of radiologist's eyes during invasive vascular procedures. Radiologists performing these examinations were asked to wear glasses through- out. After each examination the glasses were inspected for droplets.

150 procedures were performed on 123 patients. Ten procedures (6.7%) resulted in splashes to glasses. In four of these cases the radiologist was not aware of the "eye splash" nor was there a spray event to account for it. Radiologists were aware of 13 spray events (8.7% of all procedures).

There was a significantly increased risk of spray events and eye splashes during thrombolysis (p < 0.001) and of spray events during angioplasty when compared to perfemoral arteriography (p < 0.01). Procedures lasting greater than 30 minutes were associated with a significantly increased risk of spray events (p < 0.02). Significantly more eye splashes were associated with more than two catheter changes (p < 0.01) and where there were greater than two guidewire changes (p < 0.01). It is suggested that protective eye wear should be used routinely during invasive vascular procedures.

CARDIOVASCULAR

MYOCARDIAL PERFUSION SCINTIGRAPHY (MPS) MAKES CLEAR CORONARY ANGIOGRAPHY (CAG) G. WALSH and G. C. VIVIAN Department of Diagnostic Imaging, Derriford Hospital, Plymouth

The choice between surgical interventions and medical treatment in patients with Coronary Artery Disease (CAD) depends on the signifi- cance of stenoses. We have investigated the effect o f performing MPS on the management of patients with multiple lesions demonstrated by coronary angiography (CAG).

From Nov 1992 Nov 1993, 38 patients were referred for MPS following CAG. 400 MBq Tc-99m MIBI was injected at rest and stress (2-day protocol). 180 ~ SPECT acquisitions were made using an IGE 400 ACT gamma camera and processed on Nuclear Diagnostics Gamma 11 computer. Studies were analysed visually and with a Bulls Eye projection. CAG lesions were assessed visually.

Results: 36 CAG showed 1, 2 or 3V disease with 1 or 2V < 70%.

C MPS Treatment 2 N N none

11 1/2V N medical 7 1/2V l V PTCA 8 2/3V 2/3V CABG 7 Post CABG/ 3N medical

PTCA 3 1 "V" PTCA 1 3 "V" re. CABG

2 patients were inadequately stressed on MPS. MPS underestimated disease severity in one patient who subse-

quently had a CABG performed. MPS is a useful adjunct to CAG with significant implications for

patient management.

DOSE REDUCTION IN CORONARY ARTERIOGRAPHY C. REEK and R. KEAL Glenfield General Hospital, Leicester

Coronary arteriography involves a relatively high dose of radiation. As part of our quality assurance dose reduction programme we regularly review dose area product readings on all patients undergoing cardiac catheterisation.

The opening of a new digital catheter suite in January 1994 allowed us to compare doses for old (1982) and new (1991) cine angiographic systems with modern digital cardiac rooms. We have analysed the results with respect to operator experience, patient age and body mass index, screening time and catheter size.

Mean patient doses in the two cine angiographic rooms were 2380 cG/sq cm (1982) and 3193 cG/sq cm (1991). Of the three digital rooms two produced comparable doses (1993 and 2070cG/sq cm) but the third was higher at 2315cG/sq cm. This discrepancy is currently being investigated by the manufacturer. Of the recorded variables the use of smaller catheters, 6F rather than 7F, was shown to increase the average patient dose by almost one third in the hands of trainee operators.

We conclude that routine quality assurance checks and audit of radiation doses are essential in the running of a modern cardiac catheter

department. The use of smaller catheters can cause a significant increase in radiation dose and their use should be restricted to experienced operators.

DYNAMIC MYOCARDIAL MRI FOLLOWING ACUTE MYOCARDIAL INFARCTION G. R. CHERRYMAN, A. R. MOODY, A. JIVAN, J. TRANTER, S. BOLTON, M. A. HORSFIELD, M. EARLY and N. HUDSON University of Leicester, Department of Radiology, Leicester

To demonstrate the utility of dynamic MRI studies of myocardial perfusion in patients recently admitted with myocardial infarction. Fast gradient echo MRI through the myocardium were obtained before, during and after the bolus injection of iv. Gadolinium BOPTA Dime- glumine (0.05mmol/kg Bracco s.p.a.) in 30 patients with acute myo- cardial infarction. Serial MRI images through the short axis of the heart clearly demonstrate areas of reduced or absent perfusion. When compared with Thallium imaging of the myocardium obtained between 24 and 48 hours of the MRI we found the abnormal areas were easier to detect and delineate on MRI and that fewer artefacts arising from chest wall and breast are found on the MRI. We conclude dynamic MRI of the myocardium in the post infarct period is possible. The images and quantitative data obtained are comparable with that obtained with Thallium imaging.

IMPROVED DEMONSTRATION OF THORACIC AORTA ABNORMALITIES BY THREE-DIMENSIONAL MAGNETIC RESONANCE ANGIOGRAPHY G. G. HARTNELL, S, JORDAN, M. C. COHEN, L. A. HUGHES and J. P. F INN Department of Radiological Sciences and Cardiovascular Division, Deaconess Hospital, Harvard Medical School, Boston, MA, USA

Imaging of thoracic aortic disease by two dimensional techniques, including magnetic resonance imaging (MRI) can be difficult in patients with complicated three dimensional (3D) anatomy. We com- pared 3D MR angiography (MRA) of the thoracic aorta to alternative imaging for clarifying thoracic aortic anatomy.

In forty-three patients the thoracic aorta was examined using multi- level MRA (FLASH or segmented Kspace FLASH). Images were reconstructed into 3D projectional angiograms using a maximum intensity projection algorithm. Major indications for 3D MRA was suspected aneurysm (11 patients), dissection (16), branch stenosis (5), congenital anomaly (5), relationship to tumor (6), source of embolus (2), post-operative (4).

When comparing MRA to alternative imaging for each case:

Spiral CT Transthoracic Echo Angiography Agree 4 19 8 (includes all 8/8) Disagree 0 0 0 (branch stenoses)

The wide field of view of 3D MRA enabled more complete examination than alternatives (especially transthoracic echo), defined relationships to branch vessels and tumors and made interpretation of complex 3D anatomy easier.

3D MRA of the thoracic aorta rapidly and accurately defines thoracic aortic and adjacent anatomy, irrespective of orientation. In patients with congenital or acquired thoracic aortic disease 3D MRA is a valuable adjunct to conventional MRI.

THE ROLE OF RENAL ARTERY ANGIOPLASTY IN THE TREATMENT OF CONGESTIVE HEART FAILURE C. G. MISSOURIS, T. BUCKENHAM*, A.-M. BELLI*, P. J. T. VALLANCEt and G. A. MacGREGOR Blood Pressure Unit, *Department of Radiology, tDepartment of Clinical Pharmacology, St George's Hospital Medical School, London

Introduction: Renal artery stenosis is a well-known cause of high blood pressure and renal failure. It has also been described as a cause of recurrent pulmonary oedema. We studied five patients with symptoms and signs of congestive heart failure in whom renal artery stenosis appeared to be underlying cause and revascularisation led to resolution of the apparent heart failure.

Subjects and Methods: We report two of these patients who have shown the most marked response to revascularisation. At the time of presentation blood pressure was elevated despite treatment and they had signs of congestive heart failure. An echocardiogram showed