Wajid Ali

Oslo University Hospital, Kristiania (historical), Oslo County, Norway

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Publications (8)8.99 Total impact

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    Surgical Endoscopy 04/2010; · 3.43 Impact Factor
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    ABSTRACT: The objective of this work is to evaluate a new concept of intraoperative three-dimensional (3D) visualization system to support hepatectomy. The Resection Map aims to provide accurate cartography for surgeons, who can therefore anticipate risks, increase their confidence and achieve safer liver resection. In an experimental prospective cohort study, ten consecutive patients admitted for hepatectomy to three European hospitals were selected. Liver structures (portal veins, hepatic veins, tumours and parenchyma) were segmented from a recent computed tomography (CT) study of each patient. The surgeon planned the resection preoperatively and read the Resection Map as reference guidance during the procedure. Objective (amount of bleeding, tumour resection margin and operating time) and subjective parameters were retrieved after each case. Three different surgeons operated on seven patients with the navigation aid of the Resection Map. Veins displayed in the Resection Map were identified during the surgical procedure in 70.1% of cases, depending mainly on size. Surgeons were able to track resection progress and experienced improved orientation and increased confidence during the procedure. The Resection Map is a pragmatic solution to enhance the orientation and confidence of the surgeon. Further studies are needed to demonstrate improvement in patient safety.
    Surgical Endoscopy 02/2010; 24(9):2327-37. · 3.43 Impact Factor
  • Int. J. Image Graphics. 01/2010; 10:155-174.
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    ABSTRACT: Surgery is evolving towards a safer minimally invasive approach, driven by different technological advances. Augmented reality systems are gradually being adopted by surgeons to support their orientation and improve their accuracy, like the example of the Resection Map for the support of hepatectomies. There are also several AR prototypes, like the Endoclamp Positioning System and the ARIS*ER RFA system, with a great potential to reduce errors and increase safety in MIS heart clamping and needle ablations/biopsies respectively. The development and adoption of AR technologies is one of the main drivers in today's surgical revolution. Research efforts in this field are directed in several directions. One crucial aspect is the reduction of the technological burden in the OR, with solutions like the tracking of surgical tools based in video analysis. Another is to find the scientific and technological grounds to provide haptic and tactile feedback in robotic systems. And one of the most difficult challenges is to solve the problem of organ deformation and shift during soft tissue surgery. And last but not least, it is necessary to highlight the importance in this field of research of a fluent and coordinated multidisciplinary dialogue and effort in the R&D team. User centred design techniques, where surgeons, engineers and human factor specialists are involved in all the development phases (concept, design, implementation and testing), are strongly advised.
    Augmented Reality, 01/2010; , ISBN: 978-953-7619-69-5
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    ABSTRACT: The development of expert decision-making systems, which improve task performance and reduce errors within an intra-operative clinical workspace, is critically dependent on two main aspects: (a) Analyzing the clinical requirements and cognitive processes within the workflow and (b) providing an optimal context for accurate situation awareness through effective intra-operative information visualization. This paper presents a workflow centered framework and its theoretical underpinnings to design expert decision-making systems. The framework integrates knowledge of the clinical workflow based on the requirements within the clinical workspace. Furthermore, it builds upon and integrates the theory of situation awareness into system design to improve decision-making. As an application example, this framework has been used to design an intra-operative visualization system (IVS), which provides image guidance to the clinicians to perform minimally invasive procedure. An evaluative study, comparing the traditional ultrasound guided procedure with the new developed IVS, has been conducted with expert intervention radiologists and medical students. The results reveal significant evidence for improved decision-making when using the IVS. Therefore, it can be stated that this study demonstrates the benefits of integrating knowledge of cognitive processes into system development to support clinical decision-making and hence improvement of task performance and prevention of errors.
    Journal of Biomedical Informatics 08/2009; 43(1):60-74. · 2.13 Impact Factor
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    ABSTRACT: This paper evaluates and improves the capability of the endoscopic surgical robot AESOP (ComputerMotion Inc., Goleta, CA, USA) to carry out tasks autonomously. First, the Cartesian position accuracy of the robot is measured using an optical tracking system. Since the obtained results are not satisfactory, the tracking system is then used to correct the position of the robot. Two approaches are presented: in the first one, the relation between the tracking and the robot reference frames is determined and is kept constant during the execution of a task, while in the second one, some parameters involved in this relation are updated at each sampled time of the system by means of a Kalman filter. The algorithms have been implemented in the real tracking-robot system and numerical results are reported in this paper, showing that the proposed solutions clearly improve the autonomous performance of the original system.
    Industrial Electronics, 2008. ISIE 2008. IEEE International Symposium on; 08/2008
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    ABSTRACT: The European research network “Augmented reality in Surgery” (ARIS*ER) developed a system that supports percutaneous radio frequency ablation of liver tumors. The system provides interventionists, during placement and insertion of the RFA needle, with information from pre-operative CT images and real-time tracking data. A visualization tool has been designed that aims to support (1) exploration of the abdomen, (2) planning of needle trajectory and (3) insertion of the needle in the most efficient way. This work describes a first evaluation of the system, where user performances and feedback of two visualization concepts of the tool – needle view and user view – are compared. After being introduced to the system, ten subjects performed three needle placements with both concepts. Task fulfillment rate, time for completion of task, special incidences, accuracy of needle placement recorded and analyzed. The results show ambiguous results with beneficial and less favorable effects on user performance and workload of both concepts. Effects depend on characteristics of intra-operative tasks as well as on task complexities depending on tumor location. The results give valuable input for the next design steps.
    Proc SPIE 04/2008;
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    ABSTRACT: This paper presents an adaptive control scheme for improving the performance of a surgical robot when it executes tasks autonomously. A commercial tracking system is used to correlate the robot with the preoperative plan as well as to correct the position of the robot when errors between the real and planned positions are detected. Due to the noisy signals provided by the tracking system, a Kalman filter is proposed to smooth the variations and to increase the stability of the system. The efficiency of the approach has been validated using rigid and flexible endoscopic tools, obtaining in both cases that the target points can be reached with an error less than 1mm. These results make the approach suitable for a range of abdominal procedures, such as autonomous repositioning of endoscopic tools or probes for percutaneous procedures.
    Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 02/2008; 11(Pt 2):587-94.

Publication Stats

36 Citations
8.99 Total Impact Points


  • 2008–2010
    • Oslo University Hospital
      • The Intervention Centre
      Kristiania (historical), Oslo County, Norway
  • 2009
    • University of Oslo
      Kristiania (historical), Oslo County, Norway
    • Delft University Of Technology
      • Faculty of Industrial Design Engineering
      Delft, South Holland, Netherlands