Vascular 3D Printing with a Novel Biological Tissue Mimicking Resin for Patient-Specific Procedure Simulations in Interventional Radiology: a Feasibility Study.

Three-dimensional (3D) printing of vascular structures is of special interest for procedure simulations in Interventional Radiology, but remains due to the complexity of the vascular system and the lack of biological tissue mimicking 3D printing materials a technical challenge. In this study, the technical feasibility, accuracy, and usability of a recently introduced silicone-like resin were evaluated for endovascular procedure simulations and technically compared to a commonly used standard clear resin. Fifty-four vascular models based on twenty-seven consecutive embolization cases were fabricated from preinterventional CT scans and each model was checked for printing success and accuracy by CT-scanning and digital comparison to its original CT data. Median deltas (Δ) of luminal diameters were 0.35 mm for clear and 0.32 mm for flexible resin (216 measurements in total) with no significant differences (p > 0.05). Printing success was 85.2% for standard clear and 81.5% for the novel flexible resin. In conclusion, vascular 3D printing with silicone-like flexible resin was technically feasible and highly accurate. This is the first and largest consecutive case series of 3D-printed embolizations with a novel biological tissue mimicking material and is a promising next step in patient-specific procedure simulations in Interventional Radiology.

Formation of light-emitting Si nanostructures in SiO(2) by pulsed anneals.

Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO(2) layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO(2) network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO(2). This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

Search for occult secondary osteoporosis: impact of identified possible risk factors on bone mineral density.

OBJECTIVES: To determine whether the use of more elaborate diagnostic tests can identify possible risk factors for secondary osteoporosis and to evaluate the impact of these possible risk factors on the severity of bone disease in the study population. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: We have investigated 377 subjects (285 females, 92 males) with osteoporosis (T-score less than -2.5 in dual energy X-ray absorption) or nontraumatic lumbar vertebral fractures; these patients were referred to our hospital, a secondary care centre, for evaluation and treatment of osteoporosis. RESULTS: Osteoporosis without attributable risk factor was diagnosed in 106 women (37%) and 30 men (33%). In 241 patients (179 women, 62 men) one or more possible risk factors for osteoporosis (in this paper also called subclinical disease) were revealed. The most common were lactose malabsorption, disturbed exocrine pancreatic function and renal tubular disturbances, including renal hypercalciuria, incomplete renal tubular acidosis and mild phosphate diabetes. The number of possible risk factors in the individual patient was significantly related to the severity of osteoporosis as assessed by Z-scores (Spearman correlation r = -0.43, P < 0.001, n = 172 for females; r = -0.28, P < 0.05, n = 65 for males). CONCLUSIONS: All the identified subclinical diseases would have remained undetected if the currently accepted guidelines for the investigation of patients with osteoporosis were applied. The statistically significant correlation between the number of identified possible risk factors and the severity of bone disease in the individual patient strongly suggests the pathogenetic significance of the identified subclinical diseases. It is yet to be shown, whether specific treatment of these subclinical diseases yields additional improvement of bone mass as compared with standard treatment of osteoporosis.