Biomedical subjects

David G Buck

Publications and source records attributed to David G Buck.

4 recordsLinked to original sources

PubMed2004

High temporal and spatial resolution 4D MRA using spiral data sampling and sliding window reconstruction.

Contrast-enhanced magnetic resonance angiography (CE-MRA) requires high spatial resolution to demonstrate detailed vasculature and high temporal resolution to capture the contrast bolus. Sparse bright voxels in MRA permit substantial undersampling in MRI data acquisition, allowing simultaneous high temporal and spatial resolution. We developed a time-resolved 3D MRA technique using the efficient spiral sampling trajectory, and performed off-resonance corrections using inhomogeneity field maps. View sharing and sliding window reconstruction were utilized to generate high temporal resolution. High-resolution 3D angiograms were generated at 1-2 s per frame, with a 5-8 ml gadolinium dose, in patients with vascular disease.

Arteriosclerosis↗

PubMed2003

Two-dimensional versus three-dimensional CT scan for aortic measurement.

PURPOSE: To examine if 3-dimensional (3D) reconstructions of computed tomographic (CT) data, by imaging perpendicular to blood flow, can improve aortic diameter measurement accuracy over axial (2D) CT. METHODS: Two independent, blinded observers used electronic calipers to measure the minor axis and the line perpendicular to it on 40 2.5-mm 2D CT scans from 31 patients. A circular electronic tool was used to estimate diameters on 3D reconstructions from the same 40 scans. Measurements of the aortic neck were obtained 5 mm below the renal arteries and the widest slice of the aneurysm was used to measure sac diameter. Only the minor axis was measured at the iliac arteries immediately above the left (LI) and right (RI) iliac bifurcations. Datasets were compared with an intraclass correlation coefficient (ICC), Bland and Altman variation assessments, and absolute differences. RESULTS: ICC between 2D and 3D scans demonstrated high correlation with 2D minor axis measurements (neck=0.9282, sac=0.8956, RI=0.8755, LI=0.7381). 3D to 2D major axis correlation was lower (neck=0.6388, sac=0.8995). Variation between 3D and 2D minor axis measurements was low (0.51-mm average variation from the mean for the minor axis and 1.30-mm variation for the major axis). Average absolute difference between 3D and 2D diameters was 1.01 mm (minor axis) versus 2.61 mm (major axis). Interobserver correlation was highest for sac measurements both in 2D minor axis (ICC=0.8990) and 3D (ICC=0.9518). CONCLUSIONS: Minor axis measurements on axial CT scan can substitute for diameters obtained from 3D reconstructions in most clinical situations.

Aortic Aneurysm, Abdominal↗

PubMed2003

Development of a branched stent-graft for endovascular repair of aortic arch aneurysms.

PURPOSE: To develop a branched stent-graft for endovascular repair of aortic arch aneurysm. METHODS: Four different prototypes of a branched aortic stent-graft were inserted into a rubber model of the human aortic arch under fluoroscopic guidance. Each prototype was tested, modified, and tested again through a series of 4 iterations. The first 3 prototypes had multiple short side branches, as docking sites for extensions into the branches of the aortic arch. The last iteration had only 1 short branch for an extension into the distal aorta and 1 long branch for direct perfusion of the innominate artery. RESULTS: With every re-design, the prototype aortic stent-graft became shorter, and its insertion site moved to a more proximally located arch artery. Stent-graft insertion, orientation, and extension also became quicker and easier with each change in device design. However, the only system to perform reliably was the last, which was subsequently used to treat a large, symptomatic pseudoaneurysm of the aortic arch in a high-risk patient. CONCLUSIONS: None of our multibranched systems was simple, safe, or durable enough for insertion into the aortic arch; only an iteration that had a short branch for an extension into the distal aorta and a long branch for direct perfusion of the innominate artery could be deployed without difficulty or delay.

Aortic Aneurysm, Thoracic↗

PubMed2002

Abdominal aortic aneurysm repair with the Zenith stent graft: short to midterm results.

PURPOSE: The purpose of this study was to assess the short-term and mid-term results of endovascular aneurysm repair with the Zenith stent graft in a single-center prospective study. METHOD: Between October 1998 and July 2001, we used the Zenith stent graft for elective endovascular aneurysm repair in 116 patients, six of whom were women. The mean age was 75 years, and the mean aneurysm diameter was 60.3 +/- 8.8 mm. Stent grafts were oversized 10% to 20% relative to computed tomographic (CT) scan-based diameter measurements. All repairs were performed in the operating room through surgically exposed femoral arteries. The results were assessed before discharge with three-phase, contrast-enhanced CT scan and plain abdominal radiograph. These studies were repeated at 1, 6, 12, and 24 months after operation. Follow-up periods ranged from 1 to 34 months. RESULTS: No failed insertions and no conversions to open surgery occurred. The diameter of the main body of the stent graft was 28 mm or more in 73 patients (63%). Additional stents were inserted during surgery to treat kinking in eight patients (6.9%) and renal artery encroachment in two patients (1.7%). Mean fluoroscopy time was 35.1 +/- 18.3 minutes, contrast load was 146 +/- 53 mL (350 mg/mL), and estimated blood loss was 249 +/- 407 mL. The major complication rate was 9.5%, and the minor complication rate was 10.3%. The perioperative complications were myocardial infarction in four patients, arrythmia in four patients, and pulmonary embolism, renal failure, stroke, small bowel obstruction, femoral stenosis, digital embolism, and graft limb thrombosis in one patient each. All 116 patients went home from the hospital, but one patient died 2 weeks later of a combination of pulmonary embolism and myocardial infarction. Endoleak was seen on the first CT scan in 16 patients (15%); 15 were type II, and one was type III. No endoleaks of type I or IV were seen. Additional interventions were performed for each of the following conditions: type II endoleak (n = 4), type III endoleak (n = 1), femoral clamp injury (n = 1), renal artery stenosis (n = 1), and graft limb occlusion (n = 1). One patient had acute aneurysm dilatation and rupture caused by a type II endoleak through the inferior mesenteric artery 6 months after stent graft implantation. No cases were seen of late graft occlusion, stent graft migration, stent fracture, barb fracture, or secondary endoleak. CONCLUSION: The Zenith device is safe, versatile, and effective in the short to medium term. Most patients need wide stent grafts (>or=28 mm proximally and >or=16 mm distally) to achieve 10% to 20% oversizing to prevent type I endoleak.

Aged↗