Digital subtraction angiography of the superior mesenteric artery: identifying arterial branches.

This "problem in diagnostic imaging" provides an overview of the technique of digital subtraction angiography. The possibility of artefacts arising from movement subsequent to the taking of the masking image is discussed. It is also important that contrast medium is allowed to backflow into the parent vessel (in this case the aorta) to ensure that there has been filling of the proximal branches of the vessel of interest (in this case the superior mesenteric artery). An accessory middle colic artery is demonstrated. Detection of such variant vessels is important not only to surgeons but also to specialist radiologists carrying out therapeutic embolization.

One-stage tubeless antegrade ureteric stenting: a safe and cost-effective option?

INTRODUCTION: Antegrade insertion of ureteric stent has become an established mode of management of upper tract obstruction secondary to ureteric pathology. It is conventionally performed as a two-stage procedure for various reasons but, more recently, a one-stage approach has been adopted. PATIENTS AND METHODS: We discuss our experience of primary one-stage insertion of antegrade ureteric stent as a safe and cost-effective option for the management of these difficult cases in this retrospective observational case cohort study of patients referred to a radiology department for decompression of obstructed upper tracts. Data were retrieved from case notes and a radiology database for patients undergoing one-stage and two-stage antegrade stenting. It was followed by telephone survey of regional centres about the prevalent local practice for antegrade stenting. Outcome measures like hospital stay, procedural costs, requirement of analgesia/antimicrobials and complication rates were compared for the two approaches. RESULTS: a one-stage approach was found to be suitable in most cases with many advantages over the two-stage approach with comparable or better outcomes at lower costs. Some of the limitations of the study were retrospective data collection, more than one radiologist performing stenting procedures and non-availability of interventional radiologist falsely raising the incidence of two-stage procedures. CONCLUSIONS: In the absence of any clinical contra-indications and subject to availability of an interventional radiologist's support, one-stage antegrade stenting could easily be adopted as a routine approach for the management of benign or malignant ureteric obstruction.

Successful intra-arterial alteplase infusion is a predictor of 12-month limb survival in patients with lower limb arterial occlusion.

AIM: To determine the factors predicting amputation of the affected lower limb 12 months after thrombolysis for acute arterial occlusion. MATERIALS AND METHODS: The clinical endpoints of 39 patients (24 men, 15 women; average age 69 years) 1 year after catheter-directed thrombolysis with alteplase (mean dose 30 mg, mean duration 24h) for lower limb arterial occlusion (30 native arteries, nine grafts) from January 2001 to June 2005 were assessed. The amputation rate at 12 months was analysed in relation to the thrombolytic outcome, type of vessel occluded, presence or absence of complications, and subsequent requirement for additional surgery on an elective basis using Fischer's exact test. RESULTS: Successful thrombolysis, defined as complete clot dissolution based on angiographic imaging, was achieved in 64.1% of cases (19 native artery, six bypass graft) with a total complication rate of 23% (n=9). The incidence of major haemorrhage was 7.5% (n=3, hypotension and haematemesis, groin haematoma and hypotension, haematemesis). No patient had an intracranial bleed. One year after thrombolysis, 28.2% (n=11) had further surgery (bypass graft, fasciotomy, embolectomy) and the amputation rate was 20.5% (n=8). Statistical analysis showed that the amputation rate was significantly higher for patients with failed compared with successful thrombolysis (p=0.02). The amputation rates did not reach statistical significance in relation to native artery or graft occlusion, presence or absence of complications, and whether or not additional surgery was required. CONCLUSION: Successful thrombolysis was a predictor for limb survival up to 12 months post-thrombolysis regardless of the type of vessel occlusion, presence of complications or additional surgical requirement.

Bimodal electric tissue ablation (BETA) - in-vivo evaluation of the effect of applying direct current before and during radiofrequency ablation of porcine liver.

AIM: To examine the effect of applying increasing amounts of direct current (DC) before and during alternating current radiofrequency ablation of porcine liver. MATERIALS AND METHODS: Using a Radiotherapeutics RF3000 generator, a 9 V AC/DC transformer and a 16 G plain aluminium tube as an electrode, a control group of 24 porcine hepatic radiofrequency ablation zones was compared with 24 zones created using a bimodal electric tissue ablation (BETA) technique in three pigs. All ablations were terminated when tissue impedance rose to greater than 999 Omega or radiofrequency energy input fell below 5 W on three successive measurements taken at 1 min intervals. BETA ablations were performed in two phases: an initial phase of variable duration DC followed by a second phase during which standard radiofrequency ablation was applied simultaneously with DC. During this second phase, radiofrequency power input was regulated by the feedback circuitry of the RF3000 generator according to changes in tissue impedance. The diameters (mm) of each ablation zone were measured by two observers in two planes perpendicular to the plane of needle insertion. The mean short axis diameter of each ablation zone was subjected to statistical analysis. RESULTS: With increased duration of prior application of DC, there was a progressive increase in the diameter of the ablation zone (p<0.001). This effect increased sharply up to 300 s of pre-treatment after which a further increase in diameter occurred, but at a much lesser rate. A maximum ablation zone diameter of 32 mm was produced (control diameters 10-13 mm). CONCLUSION: Applying a 9 V DC to porcine liver in vivo, and continuing this DC application during subsequent radiofrequency ablation, results in larger ablation zone diameters compared with radiofrequency ablation alone.

Device to enhance visibility of needle or catheter tip at color Doppler US.

The authors tested a device that allows the tip of a needle to be visualized at color Doppler ultrasonography. The device directs an oscillating air column through a 0.016-inch inner-diameter hollow stylet, creating movement at only the needle tip. The movement is reliably and accurately displayed as a beacon of color at depths of 15 cm in vitro.

Insertion of Hickman central venous catheters by using angiographic techniques in patients with hematologic disorders.

During a 9-month period, 69 Hickman catheters were successfully inserted by using angiographic techniques in 59 patients with hematologic disorders. A pneumothorax, which did not require drainage, developed in one patient. No other significant complications occurred at the time of insertion. Eighteen catheters were removed electively, 15 are still in situ, six were removed for thrombosis, and five were accidentally removed. Infection precipitated removal in six subjects. Ten patients died with the catheter in place. Five catheters were removed in patients with refractory septicemia of unknown origin. One catheter burst during an injection and had to be removed. Three patients were lost to follow-up. There were 3.24 infectious episodes per 1000 days of catheterization, more than twice the rate found in some other series. The results of this study are compatible with the growing body of evidence in favor of the angiographic insertion of Hickman catheters. The apparently high rate of infection is ascribed to factors other than insertion in the angiography suite, including the high proportion of bone marrow transplantation patients.

Thrombin-soaked embolization coils: the effect on whole blood clotting time.

Embolization coils are well established as embolic agents for the treatment of various conditions. Several authors have commented on the increased 'thrombogenicity' of coils following soaking in thrombin solutions. We have carried out an in vitro study, carefully measuring the effect on whole blood clotting time (WBCT), of soaking coils in thrombin solutions of different concentrations (100, 200, 400, 1000 U/ml). Untreated steel coils are shown to have clot promoting activity (CPA) in vitro, reducing WBCT from 14.85 min to 5.53 min. Passing the coils down a saline-filled catheter slightly reduces their CPA, but not significantly (p = 0.21). With thrombin concentrations above 100 U/ml, a significant reduction in WBCT is recorded, but although there is a trend of increasing CPA with increasing thrombin concentration from 200-1000 U/ml, a plateau in WBCT is seen, and the difference is not significant. It therefore appears that the clot promoting activity of embolic coils is significantly increased by soaking them in a relatively weak thrombin solution. The use of such a solution (e.g. 200 U/ml) in vivo would have obvious value in limiting the potential systemic effects of thrombin.