28 research outputs found
Comparing Regularized Kelvinlet Functions and the Finite Element Method for Registration of Medical Images to Sparse Organ Data
Image-guided surgery collocates patient-specific data with the physical
environment to facilitate surgical decision making in real-time. Unfortunately,
these guidance systems commonly become compromised by intraoperative
soft-tissue deformations. Nonrigid image-to-physical registration methods have
been proposed to compensate for these deformations, but intraoperative clinical
utility requires compatibility of these techniques with data sparsity and
temporal constraints in the operating room. While linear elastic finite element
models are effective in sparse data scenarios, the computation time for finite
element simulation remains a limitation to widespread deployment. This paper
proposes a registration algorithm that uses regularized Kelvinlets, which are
analytical solutions to linear elasticity in an infinite domain, to overcome
these barriers. This algorithm is demonstrated and compared to finite
element-based registration on two datasets: a phantom dataset representing
liver deformations and an in vivo dataset representing breast deformations. The
regularized Kelvinlets algorithm resulted in a significant reduction in
computation time compared to the finite element method. Accuracy as evaluated
by target registration error was comparable between both methods. Average
target registration errors were 4.6 +/- 1.0 and 3.2 +/- 0.8 mm on the liver
dataset and 5.4 +/- 1.4 and 6.4 +/- 1.5 mm on the breast dataset for the
regularized Kelvinlets and finite element method models, respectively. This
work demonstrates the generalizability of using a regularized Kelvinlets
registration algorithm on multiple soft tissue elastic organs. This method may
improve and accelerate registration for image-guided surgery applications, and
it shows the potential of using regularized Kelvinlets solutions on medical
imaging data.Comment: 17 pages, 9 figure
Surgical Patterns of Care in Patients with Invasive Breast Cancer Treated with Neoadjuvant Systemic Therapy and Breast Magnetic Resonance Imaging: Results of a Secondary Analysis of TBCRC 017
Neoadjuvant chemotherapy (NCT) down-stages advanced primary tumors, with magnetic resonance imaging (MRI) being the most sensitive imaging predictor of response. However, the impact of MRI evaluation on surgical treatment decisions in the neoadjuvant setting has not been well described. We report surgical patterns of care across 8 National Cancer Institute comprehensive cancer centers in women receiving both NCT and MRI to evaluate the impact of MRI findings on surgical planning
Magnetic Resonance Imaging as a Predictor of Pathologic Response in Patients Treated with Neoadjuvant Systemic Treatment for Operable Breast Cancer (TBCRC 017)
Increased pathologic complete response (pCR) rates observed with neoadjuvant chemotherapy (NCT) for some subsets of patients with invasive breast cancer has prompted interest in whether patients with pCR can be identified preoperatively and potentially spared the morbidity of surgery. This multicenter retrospective study was performed to estimate the accuracy of preoperative MRI in predicting pCR in the breast
K-Ras-Independent Effects of the Farnesyl Transferase Inhibitor L-744,832 on Cyclin B1/Cdc2 Kinase Activity, G2/M Cell Cycle Progression and Apoptosis in Human Pancreatic Ductal Adenocarcinoma Cells
Pancreatic ductal adenocarcinoma is a highly lethal malignancy that is resistant to traditional cytotoxic therapy. High rates of activating codon 12 K-Ras mutations in this disease have generated considerable interest in the therapeutic application of novel farnesyl transferase inhibitors (FTIs). However, a comprehensive analysis of the effects of FTI treatment on pancreatic cancer cells has not been performed. Treatment of five different human pancreatic cancer cell lines with FTI L-744,832 resulted in inhibition of anchorage-dependent growth, with wide variation in sensitivity among different lines. Effective growth inhibition by L-744,832 correlated with accumulation of cells with a tetraploid (4N) DNA content and high levels of cyclin B1/cdc2 kinase activity, implying cell cycle arrest downstream from the DNA damage-inducible G2/M cell cycle checkpoint. In addition, sensitive cell lines underwent apoptosis as evidenced by changes in nuclear morphology and internucleosomal DNA fragmentation. L-744,832 at a concentration of 1 ”M additively enhanced the cytotoxic effect of ionizing radiation, apparently by overriding G2/M checkpoint activation. The effects of FTI treatment on cell growth and cell cycle regulation were associated with changes in posttranslational processing of H-Ras and N-Ras, but not K-Ras. The results confirm the potential therapeutic efficacy of FTI treatment in pancreatic cancer, and suggest that farnesylated proteins other than K-Ras may act as important regulators of G2/M cell cycle kinetics