Orthogonal Rings, Fiducial Markers, and Overlay Accuracy When Image Fusion is Used for EVAR Guidance.

OBJECTIVE: Evaluation of orthogonal rings, fiducial markers, and overlay accuracy when image fusion is used for endovascular aortic repair (EVAR). METHODS: This was a prospective single centre study. In 19 patients undergoing standard EVAR, 3D image fusion was used for intra-operative guidance. Renal arteries and targeted stent graft positions were marked with rings orthogonal to the respective centre lines from pre-operative computed tomography (CT). Radiopaque reference objects attached to the back of the patient were used as fiducial markers to detect patient movement intra-operatively. Automatic 3D-3D registration of the pre-operative CT with an intra-operative cone beam computed tomography (CBCT) as well as 3D-3D registration after manual alignment of nearby vertebrae were evaluated. Registration was defined as being sufficient for EVAR guidance if the deviation of the origin of the lower renal artery was less than 3 mm. For final overlay registration, the renal arteries were manually aligned using aortic calcification and vessel outlines. The accuracy of the overlay before stent graft deployment was evaluated using digital subtraction angiography (DSA) as direct comparison. RESULTS: Fiducial markers helped in detecting misalignment caused by patient movement during the procedure. Use of automatic intensity based registration alone was insufficient for EVAR guidance. Manual registration based on vertebrae L1-L2 was sufficient in 7/19 patients (37%). Using the final adjusted registration as overlay, the median alignment error of the lower renal artery marking at pre-deployment DSA was 2 mm (0-5) sideways and 2 mm (0-9) longitudinally, mostly in a caudal direction. CONCLUSION: 3D image fusion can facilitate intra-operative guidance during EVAR. Orthogonal rings and fiducial markers are useful for visualization and overlay correction. However, the accuracy of the overlaid 3D image is not always ideal and further technical development is needed.

Editor's choice. A randomized controlled trial of the fascia suture technique compared with a suture-mediated closure device for femoral arterial closure after endovascular aortic repair.

OBJECTIVES: The aim was to investigate whether the fascia suture technique (FST) can reduce access closure time and procedural costs compared with the Prostar technique (Prostar) in patients undergoing endovascular aortic repair and to evaluate the short- and mid-term outcomes of both techniques. METHODS: In this two center trial, 100 patients were randomized to access closure by either FST or Prostar between June 2006 and December 2009. The primary endpoint was access closure time. Secondary outcome measures included access related costs and evaluation of the short- and mid-term complications. Evaluation was performed peri- and post-operatively, at discharge, at 30 days and at 6 months follow up. RESULTS: The median access closure time was 12.4 minutes for FST and 19.9 minutes for Prostar (p < .001). Prostar required a 54% greater procedure time than FST, mean ratio 1.54 (95% CI 1.25-1.90, p < .001) according to regression analysis. Adjusted for operator experience the mean ratio was 1.30 (95% CI 1.09-1.55, p = .005) and for patient body mass index 1.59 (95% CI 1.28-1.96, p < .001). The technical failure rate for operators at proficiency level was 5% (2/40) compared with 28% (17/59) for those at the basic level (p = .003). The proficiency level group had a technical failure rate of 4% (1/26) for FST and 7% (1/14) for Prostar, p = 1.00, while corresponding rates for the basic level group were 27% (6/22) for FST and 30% (11/37) for Prostar (p = .84). There was a significant difference in cost in favor of FST, with a median difference of €800 (95% CI 710-927, p < .001). CONCLUSIONS: In aortic endovascular repair FST is a faster and cheaper technique than the Prostar technique.

Celiac trunk coverage in endovascular aneurysm repair.

BACKGROUND AND AIMS: This retrospective study was undertaken to examine the risks associated with obstruction of the coeliac trunk in the process of treating aneurysms with endografting. MATERIAL AND METHODS: 120 patients were treated by endografting for aneurysmal disease. Of these, a subgroup of 9 patients had their celiac trunk covered. If possible, a preoperative angiography was performed to evaluate collateral flow from the superior mesenteric artery. This was considered to predict the risk for ischemia. RESULTS: None of the patients had any severe clinical event of the celiac trunk occlusion or clinical signs of intestinal ischemia. Three patients had transient increase of liver enzymes. CONCLUSIONS: In cases where the distal landing zone of the descending thoracic aorta is to short for endografting, covering of the celiac trunk may be an option if no other surgical alter-native is apparent. Preoperative angiography to visualise the presence of collateral vessels from the superior mesenteric artery is recommended.

Magnetic resonance perfusion imaging with gadolinium-DTPA. A quantitative approach for the kinetic analysis of first-pass residue curves.

RATIONALE AND OBJECTIVES: To present a mathematic approach for the analysis of first-pass gadolinium (Gd)-DTPA kinetics and to validate the numerical tools using simulated and measured kinetics. METHODS: In a capillary plasma filter, pulsatile flow was varied between 7.4 and 12.6 mL/second. After contrast bolus injection, the arterial input curve and the residue curve were recorded simultaneously. Signal intensity versus time curves were converted to concentration versus time curves. By deconvolution of these curves and tracer kinetic analysis, the mean transit time of the contrast medium through the organ model was calculated. RESULTS: A satisfactory correlation (r = 0.98) between the inverse of mean transit time and flow measured volumetrically was demonstrated. CONCLUSIONS: The kinetic analysis of first-pass curves in an organ model indicates that this approach might be useful for in vivo assessment of organ blood flow.

Decreased distensibility of a passive vascular bed in diabetes mellitus: an indicator of microangiopathy?

This study was undertaken to determine whether the distensibility of a passive vascular bed is reduced in Type 1 (insulin-dependent) diabetic patients with microangiopathy. The change in blood flow induced by 45 degrees head-up tilting was studied in two systems: (a) following maximal ischaemic exercise and (b) in a vascular bed locally paralysed by the injection of papaverine. Five normal subjects, six patients with long-standing Type 1 diabetes and six non-diabetic patients with severe atherosclerosis affecting the legs were studied. Blood flow was measured in the anterior tibial muscle by the isotope washout technique. The median increase in blood flow produced by tilting was greater in normal subjects than in diabetic subjects in both the locally-relaxed bed (58% and 14% respectively) and after maximal ischaemic exercise (45% and 4% respectively). In the atherosclerotic subjects, the increase in blood flow in the locally relaxed bed was 77%. The results are consistent with the hypothesis that the reduced distensibility seen in the diabetic subjects was related to the presence of microvascular disease and that the behaviour of a vascular bed relaxed by the local injection of papaverine might be an appropriate model to study this condition.