Mostrando recursos 1 - 20 de 6.512

  1. Radiogenomics of clear cell renal cell carcinoma: preliminary findings of The Cancer Genome Atlas–Renal Cell Carcinoma (TCGA–RCC) Imaging Research Group

    Shinagare, Atul; Vikram, Raghu; Jaffe, Carl; Akin, Oguz; Kirby, Justin; Huang, Erich; Freymann, John; Sainani, Nisha I.; Sadow, Cheryl Ann; Bathala, Tharakeswara K.; Rubin, Daniel Brett; Oto, Aytekin; Heller, Matthew T.; Surabhi, Venkateswar R.; Katabathina, Venkat; Silverman, Stuart George
    Purpose: To investigate associations between imaging features and mutational status of clear cell renal cell carcinoma (ccRCC). Materials and methods: This multi-institutional, multi-reader study included 103 patients (77 men; median age 59 years, range 34–79) with ccRCC examined with CT in 81 patients, MRI in 19, and both CT and MRI in three; images were downloaded from The Cancer Imaging Archive, an NCI-funded project for genome-mapping and analyses. Imaging features [size (mm), margin (well-defined or ill-defined), composition (solid or cystic), necrosis (for solid tumors: 0%, 1%–33%, 34%–66% or >66%), growth pattern (endophytic, <50% exophytic, or ≥50% exophytic), and calcification (present,...

  2. Radiogenomics of clear cell renal cell carcinoma: preliminary findings of The Cancer Genome Atlas–Renal Cell Carcinoma (TCGA–RCC) Imaging Research Group

    Shinagare, Atul; Vikram, Raghu; Jaffe, Carl; Akin, Oguz; Kirby, Justin; Huang, Erich; Freymann, John; Sainani, Nisha I.; Sadow, Cheryl Ann; Bathala, Tharakeswara K.; Rubin, Daniel Brett; Oto, Aytekin; Heller, Matthew T.; Surabhi, Venkateswar R.; Katabathina, Venkat; Silverman, Stuart George
    Purpose: To investigate associations between imaging features and mutational status of clear cell renal cell carcinoma (ccRCC). Materials and methods: This multi-institutional, multi-reader study included 103 patients (77 men; median age 59 years, range 34–79) with ccRCC examined with CT in 81 patients, MRI in 19, and both CT and MRI in three; images were downloaded from The Cancer Imaging Archive, an NCI-funded project for genome-mapping and analyses. Imaging features [size (mm), margin (well-defined or ill-defined), composition (solid or cystic), necrosis (for solid tumors: 0%, 1%–33%, 34%–66% or >66%), growth pattern (endophytic, <50% exophytic, or ≥50% exophytic), and calcification (present,...

  3. Graphics Processing Unit–Accelerated Nonrigid Registration of MR Images to CT Images During CT-Guided Percutaneous Liver Tumor Ablations

    Tokuda, Junichi; Plishker, William; Torabi, Meysam; Olubiyi, Olutayo; Zaki, George; Tatli, Servet; Silverman, Stuart George; Shekher, Raj; Hata, Nobuhiko
    Rationale and Objectives: Accuracy and speed are essential for the intraprocedural nonrigid MR-to-CT image registration in the assessment of tumor margins during CT-guided liver tumor ablations. While both accuracy and speed can be improved by limiting the registration to a region of interest (ROI), manual contouring of the ROI prolongs the registration process substantially. To achieve accurate and fast registration without the use of an ROI, we combined a nonrigid registration technique based on volume subdivision with hardware acceleration using a graphical processing unit (GPU). We compared the registration accuracy and processing time of GPU-accelerated volume subdivision-based nonrigid registration technique...

  4. Graphics Processing Unit–Accelerated Nonrigid Registration of MR Images to CT Images During CT-Guided Percutaneous Liver Tumor Ablations

    Tokuda, Junichi; Plishker, William; Torabi, Meysam; Olubiyi, Olutayo; Zaki, George; Tatli, Servet; Silverman, Stuart George; Shekher, Raj; Hata, Nobuhiko
    Rationale and Objectives: Accuracy and speed are essential for the intraprocedural nonrigid MR-to-CT image registration in the assessment of tumor margins during CT-guided liver tumor ablations. While both accuracy and speed can be improved by limiting the registration to a region of interest (ROI), manual contouring of the ROI prolongs the registration process substantially. To achieve accurate and fast registration without the use of an ROI, we combined a nonrigid registration technique based on volume subdivision with hardware acceleration using a graphical processing unit (GPU). We compared the registration accuracy and processing time of GPU-accelerated volume subdivision-based nonrigid registration technique...

  5. Estimated effective dose of CT-guided percutaneous cryoablation of liver tumors

    Park, Byung Kwan; Morrison, Paul T; Tatli, Servet; Govindarajulu, Usha; Tuncali, Kemal; Judy, Philip Frank; Shyn, Paul B.; Silverman, Stuart George
    Purpose: To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose. Materials and methods: Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015 mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis....

  6. Estimated effective dose of CT-guided percutaneous cryoablation of liver tumors

    Park, Byung Kwan; Morrison, Paul T; Tatli, Servet; Govindarajulu, Usha; Tuncali, Kemal; Judy, Philip Frank; Shyn, Paul B.; Silverman, Stuart George
    Purpose: To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose. Materials and methods: Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015 mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis....

  7. Cultural dimensions of psychiatric diagnosis. A comparison of DSM-III-R and illness explanatory models in south India

    Weiss, Mitchell Gralnick; Raguram, R.; Channabasavanna, S. M.
    BACKGROUND Cross-cultural research to examine the cultural validity of diagnostic categories and underlying concepts requires methods that integrate epidemiological and anthropological frameworks. METHOD The Explanatory Model Interview Catalogue (EMIC) and Structured Clinical Interview for DSM-III-R (SCID) were used to study 80 psychiatric out-patients with depressive neurosis at a clinic in south India. RESULTS Summary kappa values of 0.75 for the EMIC and 0.68 for the SCID confirmed interrater reliability. Comparison of patient explanatory models and SCID diagnoses showed that patients emphasised somatic experience while clinicians emphasised depressive diagnoses. More than half the patients (55%) received a non-specific or dual diagnosis. CONCLUSIONS These findings...

  8. Parasitic Diseases and Psychiatric Illness

    Weiss, Mitchell Gralnick
    Distinguishing parasitic diseases from other infections and tropical medical disorders based on microbiological classification is a matter of convenience. Organic brain syndromes are associated with both protozoan and helminthic infections; side-effects of drugs commonly used to treat parasitoses may impair mood and cause anxiety, agitation or psychosis. Emotional states may in turn affect the experience of medical illness. Psychiatrically significant features of medical illness are determined both by pathophysiology and by the personal and social context in which they occur. Many factors affect mental health in the tropics where the synergy of infection, emotional strengths, vulnerabilities, social supports and stressors...

  9. Tubular structure enhancement for surgical instrument detection in 3D ultrasound

    Ren, Hongliang; Dupont, Pierre E
    Three-dimensional ultrasound has been an effective imaging modality for diagnostics and is now an emerging modality for image-guided minimally-invasive interventions since it enables visualization of both instruments and tissue. Challenges to ultrasound-guided interventions arise, however, due to the low signal-to-noise ratio and the imaging artifacts created by the interventional instruments. Metallic instruments, in particular, are strong scatters and so produce a variety of artifacts. For many interventions, the manual or robotic instrument is comprised of a long curved tubular structure with specialized tooling at its tip. Toward the goal of developing a surgical navigation system, this paper proposes an image...

  10. Algorithms for design of continuum robots using the concentric tubes approach: A neurosurgical example

    Anor, Tomer; Madsen, Joseph Russell; Dupont, Pierre E
    We propose a novel systematic approach to optimizing the design of concentric tube robots for neurosurgical procedures. These procedures require that the robot approach specified target sites while navigating and operating within an anatomically constrained work space. The availability of preoperative imaging makes our approach particularly suited for neurosurgery, and we illustrate the method with the example of endoscopic choroid plexus ablation. A novel parameterization of the robot characteristics is used in conjunction with a global pattern search optimization method. The formulation returns the design of the least-complex robot capable of reaching single or multiple target points in a confined...

  11. Metal MEMS tools for beating-heart tissue approximation

    Butler, Evan J.; Folk, Chris; Cohen, Adam; Vasilyev, Nikolay; Chen, Rich; Del Nido, Pedro J.; Dupont, Pierre E
    Achieving superior outcomes through the use of robots in medical applications requires an integrated approach to the design of the robot, tooling and the procedure itself. In this paper, this approach is applied to develop a robotic technique for closing abnormal communication between the atria of the heart. The goal is to achieve the efficacy of surgical closure as performed on a stopped, open heart with the reduced risk and trauma of a beating-heart catheter-based procedure. In the proposed approach, a concentric tube robot is used to percutaneously access the right atrium and deploy a tissue approximation device. The device...

  12. Detection of curved robots using 3D ultrasound

    Ren, Hongliang; Vasilyev, Nikolay; Dupont, Pierre E
    Three-dimensional ultrasound can be an effective imaging modality for image-guided interventions since it enables visualization of both the instruments and the tissue. For robotic applications, its realtime frame rates create the potential for image-based instrument tracking and servoing. These capabilities can enable improved instrument visualization, compensation for tissue motion as well as surgical task automation. Continuum robots, whose shape comprises a smooth curve along their length, are well suited for minimally invasive procedures. Existing techniques for ultrasound tracking, however, are limited to straight, laparoscopic-type instruments and thus are not applicable to continuum robot tracking. Toward the goal of developing tracking...

  13. Real-time position control of concentric tube robots

    Dupont, Pierre E; Lock, Jesse; Itkowitz, Brandon
    A novel approach to constructing robots is based on concentrically combining pre-curved elastic tubes. By rotating and extending the tubes with respect to each other, their curvatures interact elastically to position and orient the robot's tip, as well as to control the robot's shape along its length. Since these robots form slender curves, they are well suited for minimally invasive medical procedures. A substantial challenge to their practical use is the real-time solution of their kinematics that are described by differential equations with split boundary equations. This paper proposes a numerically efficient approach to real-time position control. It is shown...

  14. Stiffness control of a continuum manipulator in contact with a soft environment

    Mahvash, M; Dupont, Pierre E
    Stiffness control of a continuum robot can prevent excessive contact forces during robot navigation inside delicate, uncertain and confined environments. Furthermore, it enables the selection of tip stiffnesses that match varying task requirements. This paper introduces a computationally-efficient approach to continuum-robot stiffness control that is based on writing the forward kinematic model as the product of two transformations. The first transformation calculates the non-contact kinematics of the robot and can be formulated based on the specific type of continuum robot under consideration. The second transformation calculates the tip deflection due to applied forces and is efficiently computed using the special...

  15. Quasistatic modeling of concentric tube robots with external loads

    Lock, Jesse; Laing, Genevieve; Mahvash, Mohsen; Dupont, Pierre E
    Concentric tube robots are a subset of continuum robots constructed by combining pre-curved elastic tubes. As the tubes are rotated and translated with respect to each other, their curvatures interact elastically, enabling control of the robot's tip configuration as well as the curvature along its length. This technology is projected to be useful in many types of minimally invasive medical procedures. Because these robots are flexible by design, they deflect considerably when applying forces to the external environment. Thus, in contrast to rigid-link robots, their kinematic and static force models are coupled. This paper derives a multi-tube quasistatic model that...

  16. Mechanics of Dynamic Needle Insertion into a Biological Material

    Mahvash, M.; Dupont, Pierre E
    During needle-based procedures, transitions between tissue layers often lead to rupture events that involve large forces and tissue deformations and produce uncontrollable crack extensions. In this paper, the mechanics of these rupture events is described, and the effect of insertion velocity on needle force, tissue deformation, and needle work is analyzed. Using the J integral method from fracture mechanics, rupture events are modeled as sudden crack extensions that occur when the release rate J of strain energy concentrated at the tip of the crack exceeds the fracture toughness of the material. It is shown that increasing the velocity of needle...

  17. Ultrasound-based servoing of manipulators for telesurgery

    Stoll, Jeff; Dupont, Pierre E; Howe, Robert D.
    Certain minimally invasive surgical procedures involve the treatment of highly precise target locations within deformable tissues. While preoperative MRI and CT models can be used for surgical planning, they provide only coarse guidance during surgery due to their limited resolution and owing to tissue deformation. Ultrasound imaging is a promising means of obtaining real-time intraoperative data for target localization that is particularly well suited to minimally invasive surgery due to its portability, speed, and safety. This paper presents a system, in which ultrasound images are used to guide a manipulator to a surgical site. Electromagnetic tracking of the ultrasound probe...

  18. Dexterity optimization by port placement in robot-assisted minimally invasive surgery

    Selha, Shaun; Dupont, Pierre E; Howe, Robert D.; Torchiana, David Fitzgerald
    A computer-based algorithm has been developed which uses preoperative images to provide a surgeon with a list of feasible port triplets ranked according to tool dexterity and endoscopic view quality at each surgical site involved in a procedure. A computer simulation allows the surgeon to select from among the proposed port locations. The procedure selected for the development of the system consists of a coronary artery bypass graft (CABG). In this procedure, the interior mammary artery (IMA) is mobilized from the interior chest wall, and one end is attached to the coronary arteries to provide a new blood supply for...

  19. Titin mutations in iPS cells define sarcomere insufficiency as a cause of dilated cardiomyopathy

    Hinson, John Travis; Chopra, Anant; Nafissi, N.; Polacheck, William; Benson, Craig Carlyle; Swist, S.; Gorham, Joshua McClean; Yang, Luhan; Schafer, S.; Sheng, Calvin Chen; Haghighi, Alireza; Homsy, Jason George; Hubner, N.; Church, George McDonald; Cook, S. A.; Linke, Wolfgang; Chen, Christopher; Seidman, Jonathan G.; Seidman, Christine Edry
    Human mutations that truncate the massive sarcomere protein titin [TTN-truncating variants (TTNtvs)] are the most common genetic cause for dilated cardiomyopathy (DCM), a major cause of heart failure and premature death. Here we show that cardiac microtissues engineered from human induced pluripotent stem (iPS) cells are a powerful system for evaluating the pathogenicity of titin gene variants. We found that certain missense mutations, like TTNtvs, diminish contractile performance and are pathogenic. By combining functional analyses with RNA sequencing, we explain why truncations in the A-band domain of TTN cause DCM, whereas truncations in the I band are better tolerated. Finally,...

  20. Community Psychiatry Clinics at Sundarban: a clinical and cultural experience.

    Chowdhury, Atif Newaz; Sanyal, D; Chakraborty, A; De, R; Banerjee, S; Weiss, Mitchell Gralnick
    A series of Community Psychiatric Clinics were conducted in different blocks of Sundarban region of West Bengal. One of the primary objectives of this was to collect clinical epidemiological data on psychiatric morbidity in the region. A total of 26 clinics were conducted in Sagar, Kakdwip, Canning and Gosaba block of the Sundarban region during the period from end 1998 to end 2000. A total of 451 psychiatric cases with diagnostic categories (male 239, female 212) and 215 non-psychiatric cases (male 107 and female 108) were seen in these clinics. Diagnostic Interview Schedules (SCID) and Clinical rating scales like Hamilton...

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