Factors Associated With Long-Term Weight Loss Following Bariatric Surgery Using 2 Methods for Repeated Measures Analysis.

We used electronic health record data from 162 patients enrolled in the NUgene Project (2002-2013) to determine demographic factors associated with long-term (from 1 to up to 9.5 (mean = 5.6) years) weight loss following Roux-en-Y gastric bypass surgery. Ninety-nine (61.1%) patients self-reported white, and 63 (38.9%) self-reported black, mixed, or missing race. The average percent weight loss was -33.4% (standard deviation, 9.3) at 1 year after surgery and -30.7% (standard deviation, 12.5) at the last follow-up point. We used linear mixed and semiparametric trajectory models to test the association of surgical and demographic factors (height, surgery age, surgery weight, surgery body mass index, marital status, sex, educational level, site, International Classification of Diseases code, Current Procedural Terminology code, Hispanic ethnicity, and self-reported race) with long-term percent weight loss and pattern of weight loss. We found that black, mixed, and missing races (combined) in comparison with white race were associated with a decreased percent weight loss of -4.31% (95% confidence interval: -7.30, -1.32) and were less likely to have higher and sustained percent weight loss (P = 0.04). We also found that less obese patients were less likely to have higher and sustained percent weight loss (P = 0.01). These findings may be helpful to patients in setting expectations after weight loss surgery.

Clinical perspectives on the modern laboratory.

Clinicians depend daily on the clinical laboratory in the conduct of patient care. The modern clinical laboratory is a sophisticated network of people, machines, and processes tightly coupled with the clinicians it serves. The modern laboratory seeks to support a wide variety of encyclopedic information, collections, status information, and results effectively and efficiently. The modern laboratory integrates information management and quality improvement methods to retrieve and deliver needed information accurately and in a timely fashion. Ultimately, the modern laboratory achieves its information flow seamlessly, with the clinician improving overall cost-effectiveness of the health care system.

A prospective experience with selective cholangiography.

A prospective study of patients with symptomatic cholelithiasis was undertaken to determine the effectiveness of identifying clinically significant choledocholithiasis with selective cholangiography. Between 1991 and 1995, 262 patients presented to the senior author (K.W.M.) with acute or chronic cholecystitis. Sixteen patients had a preoperative endoscopic retrograde cholangiopancreatography (ERCP) for an elevated alkaline phosphatase or total bilirubin greater than twice the normal value or an ultrasound finding suspecting choledocholithiasis. Ten of the ERCP patients had choledocholithiasis, with eight patients having successful clearance by ERCP. Ninety other patients had intraoperative cholangiography for abnormal serum liver biochemistries, a history of jaundice or pancreatitis, or a dilated common bile duct (CBD) (>6 mm) on ultrasound. Fourteen of the intraoperative cholangiography patients and the two remaining ERCP patients had choledocholithiasis requiring CBD exploration for clearance of their stones. There were no false-positive cholangiograms, and there were no bile duct injuries in this series. With 100 per cent follow-up of at least 2 years, only one patient required ERCP clearance of a retained CBD stone 13 months after cholecystectomy. The positive predictive value and the negative predictive value for the selective cholangiography criteria are 23 per cent and 99 per cent, respectively. In conclusion, clinically significant choledocholithiasis can be found effectively with selective cholangiography. Also, utilizing selective cholangiography reduces the number of routine cholangiograms by 60 per cent.

Prognostic factors associated with resectable adenocarcinoma of the head of the pancreas.

A retrospective study of patients with surgically resectable adenocarcinoma of the pancreatic head was undertaken to determine which prognostic factors are independently associated with improved survival. Thirty-four men and 41 women (mean age, 61.9 years) had resection for adenocarcinoma of the pancreatic head between 1980 and 1997 at Rush-Presbyterian-St. Luke's Medical Center. Surgical resections included 15 total pancreatectomies, 43 pyloric-preserving procedures, and 17 standard Whipple procedures. Thirty-six patients received adjuvant radiation and/or chemotherapy. Overall median survival was 13 months, with a 5-year survival of 17 per cent. Thirty-day surgical mortality was 1.3 per cent. Significant factors that negatively influenced survival using univariate Kaplan-Meier analysis were: positive resection margin (P = 0.01), intraoperative blood transfusion (P = 0.01), and lymph node metastases (P = 0.01). Presenting signs and symptoms, patient demographics, operative procedure, tumor size, histologic differentiation, and adjuvant therapy did not have a significant impact on survival. Using multivariate Cox regression analysis, the only significant independent factors improving survival were the absence of intraoperative blood transfusion (P = 0.02) and a negative resection margin (P = 0.04). Performing pancreaticoduodenectomy for adenocarcinoma of the head of the pancreas with negative microscopic margins of resection and without intraoperative transfusion significantly improves survival.

Manipulation of volumetric patient data in a distributed virtual reality environment.

Due to increases in network speed and bandwidth, distributed exploration of medical data in immersive Virtual Reality (VR) environments is becoming increasingly feasible. The volumetric display of radiological data in such environments presents a unique set of challenges. The shear size and complexity of the datasets involved not only make them difficult to transmit to remote sites, but these datasets also require extensive user interaction in order to make them understandable to the investigator and manageable to the rendering hardware. A sophisticated VR user interface is required in order for the clinician to focus on the aspects of the data that will provide educational and/or diagnostic insight. We will describe a software system of data acquisition, data display, Tele-Immersion, and data manipulation that supports interactive, collaborative investigation of large radiological datasets. The hardware required in this strategy is still at the high-end of the graphics workstation market. Future software ports to Linux and NT, along with the rapid development of PC graphics cards, open the possibility for later work with Linux or NT PCs and PC clusters.

Radiological tele-immersion for next generation networks.

Since the acquisition of high-resolution three-dimensional patient images has become widespread, medical volumetric datasets (CT or MR) larger than 100 MB and encompassing more than 250 slices are common. It is important to make this patient-specific data quickly available and usable to many specialists at different geographical sites. Web-based systems have been developed to provide volume or surface rendering of medical data over networks with low fidelity, but these cannot adequately handle stereoscopic visualization or huge datasets. State-of-the-art virtual reality techniques and high speed networks have made it possible to create an environment for clinicians geographically distributed to immersively share these massive datasets in real-time. An object-oriented method for instantaneously importing medical volumetric data into Tele-Immersive environments has been developed at the Virtual Reality in Medicine Laboratory (VRMedLab) at the University of Illinois at Chicago (UIC). This networked-VR setup is based on LIMBO, an application framework or template that provides the basic capabilities of Tele-Immersion. We have developed a modular general purpose Tele-Immersion program that automatically combines 3D medical data with the methods for handling the data. For this purpose a DICOM loader for IRIS Performer has been developed. The loader was designed for SGI machines as a shared object, which is executed at LIMBO's runtime. The loader loads not only the selected DICOM dataset, but also methods for rendering, handling, and interacting with the data, bringing networked, real-time, stereoscopic interaction with radiological data to reality. Collaborative, interactive methods currently implemented in the loader include cutting planes and windowing. The Tele-Immersive environment has been tested on the UIC campus over an ATM network. We tested the environment with 3 nodes; one ImmersaDesk at the VRMedLab, one CAVE at the Electronic Visualization Laboratory (EVL) on east campus, and a CT scan machine in UIC Hospital. CT data was pulled directly from the scan machine to the Tele-Immersion server in our Laboratory, and then the data was synchronously distributed by our Onyx2 Rack server to all the VR setups. Instead of permitting medical volume visualization at one VR device, by combining teleconferencing, tele-presence, and virtual reality, the Tele-Immersive environment will enable geographically distributed clinicians to intuitively interact with the same medical volumetric models, point, gesture, converse, and see each other. This environment will bring together clinicians at different geographic locations to participate in Tele-Immersive consultation and collaboration.

Limitations of distributed segmentation for three-dimensional radiological modeling.

While the use of three-dimensional models has been shown to be useful clinically, the specialized computational equipment and expertise necessary for their construction and use keeps these tools out of reach of most physicians. This paper explores the construction of a Web-based Java application that allows medical radiological models to be built on a remote server and navigated locally on the physician's desktop PC. This paper will also address issues that arose from a public, unrestricted testing of usability over the Internet, such as model size management, easy navigation, processor loading and security. Based on observations and data collected, we suggest what steps are necessary to make a telemedicine application useable in a true clinical setting.

Autocolorization of three-dimensional radiological data.

It requires skill, effort, and time to visualize desired anatomic structures from radiological data in three-dimensions. There have been many attempts at automating this process and making it less labor intensive. The technique we have developed is based on mutual information for automatic multi-modality image fusion (MIAMI Fuse, University of Michigan). The initial development of our technique has focused on the autocolorization of the liver, portal vein, and hepatic vein. A standard dataset in which these structures had been segmented and assigned colors was created from the full color Visible Human Female (VHF) and then optimally fused to the fresh CT Visible Human Female. This semi-automatic segmentation and coloring of the CT dataset was subjectively evaluated to be reasonably accurate. The transformation could be viewed interactively on the ImmersaDesk, in an immersive Virtual Reality (VR) environment. This 3D segmentation and visualization method marks the first step to a broader, standardized automatic structure visualization method for radiological data. Such a method, would permit segmentation of radiological data by canonical structure information and not just from the data's intrinsic dynamic range.

Fractionated irradiation of the regenerated rat liver.

Fractionated radiation therapy after liver resection for metastatic cancer has traditionally been a palliative procedure. Here, we consider that radiation may be an appropriate adjuvant therapy for cure after liver resection for metastases. This pilot study in rats establishes a model for evaluating the effects of fractionated irradiation posthepatectomy. Sixty Sprague-Dawley rats were randomized to four groups. The groups underwent laparotomy, laparotomy and radiation, hepatectomy, and hepatectomy and radiation. We found that the rats treated with radiation had statistically significant (P < 0.0001) clinical radiation change by liver function tests at 6 months. This damage was resolved to normal at 1 year regardless of hepatectomy. In fact, we demonstrate the possibility of a protective effect from radiation damage in the regenerated liver. We also demonstrate statistically significant histologic change at 8 months (P < 0.01) in the radiation-treated rats which does not resolve at 1 year.

The Virtual Pelvic Floor, a tele-immersive educational environment.

This paper describes the development of the Virtual Pelvic Floor, a new method of teaching the complex anatomy of the pelvic region utilizing virtual reality and advanced networking technology. Virtual reality technology allows improved visualization of three-dimensional structures over conventional media because it supports stereo vision, viewer-centered perspective, large angles of view, and interactivity. Two or more ImmersaDesk systems, drafting table format virtual reality displays, are networked together providing an environment where teacher and students share a high quality three-dimensional anatomical model, and are able to converse, see each other, and to point in three dimensions to indicate areas of interest. This project was realized by the teamwork of surgeons, medical artists and sculptors, computer scientists, and computer visualization experts. It demonstrates the future of virtual reality for surgical education and applications for the Next Generation Internet.