Question 2 A 51-year-old Caucasian female with a past history of hypertension and hypothyroidism presented for a screening colonoscopy. Her surgical history was significant for a total abdominal hysterectomy. Abdominal examination was normal and laboratory findings were unremarkable. CT scan of the abdomen was performed which did not show any abnormalities or pathologies upon read...

Interpolation and especially thin plate spline is a popularly and widely used algorithm for warping and registration of medical images. This interpolation function is established based on certain relationship between two sets of landmark points in source and destination planes. Sensitivity analysis of mapping function to source and/or target points has not been carefully analyzed before. In this article, sensitivity analysis using analytical approach is performed on source and destination deviation. The method is applied to synthetic data, real and simulated Magnetic Resonance (MR) images. Our results demonstrate that sensitivity is highly related to landmark distribution in the source and target plane and the type of radial basis function (RBF) of the geometrical mapping. Particularly, we have shown that sensitivity is very high near landmarks that are close together and sensitivity approaches to zero near precisely extracted landmark.      

Background: The recognition of the popliteal artery and vein for transpopliteal angioplasty is difficult in some cases. The puncture site can be identified using arterial pulsation, Doppler guidance, fluoroscopy guidance, and anatomical landmarks. In this study, we aimed to evaluate the success rate of obtaining vascular access using an anatomical landmark. Methods: Totally, 59 participants were included in this study between September 2016 and October 2017. Eighteen cases were scheduled for venous angioplasty, and the rest were scheduled for arterial angioplasty. The procedures were performed with the patients in the prone position. The patients’ foot was rotated in the prone position so that the most distance between the external and internal tibial condyles could be found. Then, the popliteal vein was located on its medial side since lateral to this landmark passes the popliteal artery. This seems to be the most suitable approach to finding the best landmark. In these locations, 15 mL of Xylocaine was injected, and the needle was kept in place. For the prevention of septic arthritis, the injection was done 1 inch above the landmarks. Results: The success rate was excellent, with failure reported in only 2 cases. The failure was attributed to the complete occlusion of the popliteal artery due to extensive atheroma in 1 patient and the total occlusion of the popliteal vein by thrombosis in the other case. Conclusions: The transpopliteal approach using the anatomical landmarks of external and internal tibial condyles for arterial and venous access is a method with a high success rate for lower limb angioplasty.