11 research outputs found
Anatomically Constrained Video-CT Registration via the V-IMLOP Algorithm
Functional endoscopic sinus surgery (FESS) is a surgical procedure used to
treat acute cases of sinusitis and other sinus diseases. FESS is fast becoming
the preferred choice of treatment due to its minimally invasive nature.
However, due to the limited field of view of the endoscope, surgeons rely on
navigation systems to guide them within the nasal cavity. State of the art
navigation systems report registration accuracy of over 1mm, which is large
compared to the size of the nasal airways. We present an anatomically
constrained video-CT registration algorithm that incorporates multiple video
features. Our algorithm is robust in the presence of outliers. We also test our
algorithm on simulated and in-vivo data, and test its accuracy against
degrading initializations.Comment: 8 pages, 4 figures, MICCA
Endoscopic navigation in the absence of CT imaging
Clinical examinations that involve endoscopic exploration of the nasal cavity
and sinuses often do not have a reference image to provide structural context
to the clinician. In this paper, we present a system for navigation during
clinical endoscopic exploration in the absence of computed tomography (CT)
scans by making use of shape statistics from past CT scans. Using a deformable
registration algorithm along with dense reconstructions from video, we show
that we are able to achieve submillimeter registrations in in-vivo clinical
data and are able to assign confidence to these registrations using confidence
criteria established using simulated data.Comment: 8 pages, 3 figures, MICCAI 201
Interaction of the Deubiquitinating Enzyme Ubp2 and the E3 Ligase Rsp5 Is Required for Transporter/Receptor Sorting in the Multivesicular Body Pathway
Protein ubiquitination is essential for many events linked to intracellular protein trafficking. We sought to elucidate the possible involvement of the S. cerevisiae deubiquitinating enzyme Ubp2 in transporter and receptor trafficking after we (this study) and others established that affinity purified Ubp2 interacts stably with the E3 ubiquitin ligase Rsp5 and the (ubiquitin associated) UBA domain containing protein Rup1. UBP2 interacts genetically with RSP5, while Rup1 facilitates the tethering of Ubp2 to Rsp5 via a PPPSY motif. Using the uracil permease Fur4 as a model reporter system, we establish a role for Ubp2 in membrane protein turnover. Similar to hypomorphic rsp5 alleles, cells deleted for UBP2 exhibited a temporal stabilization of Fur4 at the plasma membrane, indicative of perturbed protein trafficking. This defect was ubiquitin dependent, as a Fur4 N-terminal ubiquitin fusion construct bypassed the block and restored sorting in the mutant. Moreover, the defect was absent in conditions where recycling was absent, implicating Ubp2 in sorting at the multivesicular body. Taken together, our data suggest a previously overlooked role for Ubp2 as a positive regulator of Rsp5-mediated membrane protein trafficking subsequent to endocytosis
Endoscopic Laser Surface Scanner for Minimally Invasive Abdominal Surgeries
© 2018, Springer Nature Switzerland AG. Minimally invasive surgery performed under endoscopic video is a viable alternative to several types of open abdominal surgeries. Advanced visualization techniques require accurate patient registration, often facilitated by reconstruction of the organ surface in situ. We present an active system for intraoperative surface reconstruction of internal organs, comprising a single-plane laser as the structured light source and a surgical endoscope camera as the imaging system. Both surgical instruments are spatially calibrated and tracked, after which the surface reconstruction is formulated as the intersection problem between line-of-sight rays (from the surgical camera) and the laser beam. Surface target registration error after a rigid-body surface registration between the scanned 3D points to the ground truth obtained via CT is reported. When tested on an ex vivo porcine liver and kidney, root-mean-squared surface target registration error of 1.28 mm was achieved. Accurate endoscopic surface reconstruction is possible by using two separately calibrated and tracked surgical instruments, where the trigonometry between the structured light, imaging system, and organ surface can be optimized. Our novelty is the accurate calibration technique for the tracked laser beam, and the design and the construction of laser apparatus designed for robotic-assisted surgery