Zhonghua Sun

Short to midterm outcomes of fenestrated endovascular grafts in the treatment of abdominal aortic aneurysms: a systematic review

Purpose: To perform a systematic review of the short to midterm outcomes of fenestrated endovascular grafts in patients with abdominal aortic aneurysms (AAA). Methods: A search of PubMed and Medline databases for English-language literature was performed to find studies published between 1999 and 2006. Studies investigating the short to midterm results of fenestrated endovascular grafts for AAA were analyzed for clinical outcomes and postprocedural complications. Results: Nineteen studies involving fenestrated endovascular grafting were retrieved, and 6 of them met criteria for inclusion in the analysis. The remaining studies were excluded because they dealt with technical or case reports or cumulative addition of previous cases. Pooled estimates (95% confidence interval) of postprocedural complications were 1.1% (0.4%-2.7%) for 30-day mortality; 8.3% (2.9%-13.6%) for late mortality; 97% (92%–100%) and 90% (85%–95%) for perfusion of fenestrated vessels at perioperative and late follow-up, respectively; 13.3% (4.1%–22.5%) for postprocedural renal dysfunction; and 11.2% (3.2%–22.5%) and 9.4% (2.6%–16.3%) for early and late endoleak, respectively. There was correlation between preoperative renal insufficiency and postprocedural renal dysfunction, although this was not a statistically significant difference (p=0.2). Conclusion: Our systematic review showed that fenestrated endovascular grafting provides an alternative technique to treat patients with complex aneurysm necks, achieving lower mortality than open repair under comparable conditions. Preoperative renal impairment is a strong indicator of postoperative renal dysfunction. Long-term stability and patency of the fenestrated vessels deserves to be validated.

Three-Dimensional Visualization of Suprarenal Aortic Stent-Grafts: Evaluation of Migration in Midterm Follow-up

Purpose: To investigate the midterm results of transrenal fixation of abdominal aortic stent-grafts with regard to device migration and encroachment of stent wires on the renal and visceral branches. Methods: Imaging data from 18 patients (15 men; mean age 75 years, range 63–84) undergoing transrenal stent-graft fixation for abdominal aortic aneurysm (AAA) were included in the study. Computed tomographic angiographic data acquired within 1 week of stent-graft implantation were compared to the latest follow-up images. Postprocessing methods generated 3-dimensional (3D) maximum intensity projections (MIP) and virtual intravascular endoscopy (VIE) for evaluation of the relationship between suprarenal stents and aortic branches. Aortic neck angulation was measured in each patient for correlation with the incidence of stent migration. Results: The mean follow-up period was 40 months. 3D image visualizations showed that the stent-graft moved caudally in all patients (range 2.6–14.2 mm), with migration (>10 mm) observed in 4 (22%) patients. Corresponding VIE images documented changes in stent wire encroachment on the aortic branch ostia in 11 patients, including the number and position of crossing stent wires. There was no close relationship between aortic neck angulation and stent migration. Conclusion: The current study demonstrated that migration occurs at midterm follow-up in transrenally deployed stent-grafts. 3D images were valuable for the assessment of stent migration, as well as its relationship with aortic branch ostia. Long-term follow-up of transrenal fixation deserves to be investigated, especially after observing stent migration relative to aortic ostial encroachment.

Patient-specific three-dimensional printed pulmonary artery model: A preliminary study

Background and Objectives: Three-dimensional (3D) printing has potential value in medical applications with increasing reports in the diagnostic assessment of cardiovascular diseases. The use of 3D printing in replicating pulmonary artery anatomy and diagnosing pulmonary embolism is very limited. The purpose of this study was to develop a 3D printed pulmonary artery model and test different computed tomography (CT) scanning protocols for determination of an optimal protocol with acceptable image quality but low radiation dose. Materials and Methods: A patient-specific 3D printed pulmonary artery model was created based on contrast-enhanced CT images in a patient with suspected pulmonary embolism. Different CT pulmonary angiography protocols consisting of 80, 100, and 120 kVp, pitch 0.7, 0.9, and 1.2 with 1 mm slice thickness, and 0.6 mm reconstruction interval were tested on the phantom. Quantitative assessment of image quality in terms of signal-to-noise ratio (SNR) was measured in the images acquired with different protocols. Measurements in pulmonary artery diameters were conducted and compared between pre- and post-3D printed images and 3D printed model. Results: The 3D printed model was found to replicate normal pulmonary artery with high accuracy. The mean difference in diameter measurements was <0.8 mm (<0.5% deviation in diameter). There was no significant difference in SNR measured between these CT protocols (P = 0.96–0.99). Radiation dose was reduced by 55% and 75% when lowering kVp from 120 to 100 and 80 kVp, without affecting image quality. Conclusions: It is feasible to produce a 3D printed pulmonary artery model with high accuracy in replicating normal anatomy. Different CT scanning protocols are successfully tested on the model with 80 kVp and pitch 0.9 being the optimal one with resultant diagnostic images but at much lower radiation dose.

Patient-specific 3D printed model in delineating brain glioma and surrounding structures in a pediatric patient

Background and Objectives: Three-dimensional (3D) printing has been increasingly used in medicine with applications in the diagnostic assessment of disease extent, medical education and training, preoperative planning, and surgical simulation. The use of 3D printing in brain tumors is very limited. In this study, we presented our preliminary experience of creating patient-specific 3D printed model of a brain tumor in a pediatric patient and demonstrated the feasibility of using 3D printing in delineating brain anatomy and tumor. Materials and Methods: A life-size 3D printed brain model of a 6-year-old girl, who was diagnosed with pilocytic astrocytoma, was generated. The model was created using high-resolution magnetic resonance images which were postprocessed and segmented to demonstrate normal anatomical structures and the tumor. The tumor was confirmed to be Grade I pilocytic astrocytoma after neurosurgery. Results: 3D printed model was found to provide realistic visualization of brain anatomical structures and tumor, and enhance understanding of pathology in relation to the surrounding structures. The mean difference in diameter measurements of the brain tumor was 0.53 mm (0.98%) between the 3D printed model and computerized model. Conclusions: This study shows it is feasible to generate a 3D printed model of brain tumor with encouraging results achieved to replicate brain anatomy and tumor. 3D printed model of brain tumor could serve as an excellent tool for preoperative planning and simulation of surgical procedures, which deserve to be investigated in further studies.