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Thomas Gross

Publications and source records attributed to Thomas Gross.

9 recordsLinked to original sources
PubMed2004

Modality-based navigation.

Modality-based navigation (MBN) means the interactive tracking of instruments in a co-ordinate system defined by an imaging modality, eg, CT, MR, or a fluoroscope. During the registration process, a transformation matrix between the two co-ordinate systems of the digitizer and imaging modality is calculated. Navigation can start immediately after collection of the images without an intraprocedural registration process. Since the imaging modality belongs to the OR or the intervention suite, image update can be performed at any time. Following a step-by-step procedure with navigation and image update in a reasonable sequence, the risk for a virtual-real mismatch is minimized. For CT-MBN, we obtained a freehand absolute positioning accuracy of 1.9+/-1.1 mm in vitro. The in vivo freehand absolute positioning accuracy in pelvic fracture fixation was determined to be 3.1 mm (unpublished data). From our point of view, modality-based navigation is an efficient and safe alternative tool for computer aided interventions.

Fluoroscopy↗
PubMed2002

FDG-PET imaging and the diagnosis of non-small cell lung cancer in a region of high histoplasmosis prevalence.

STUDY OBJECTIVE: Determine the sensitivity and specificity of [F-18]-fluorine-2-deoxy-D-glucose positron emission tomography (FDG-PET) in differentiating non-small cell lung cancer (NSCLC) from benign solitary pulmonary nodules (SPNs) in a region with a high endemic rate of histoplamosis. DESIGN: Prospective, clinical study. SETTING: University, tertiary referral hospital in the upper Mississippi River valley. PATIENTS: Ninety patients with SPNs. INTERVENTIONS: Independent interpretation of FDG-PET imaging, computed tomography and pathologic evaluation of the SPNs. MEASUREMENTS AND RESULTS: To detect malignant SPNs, FDG-PET imaging had a sensitivity of 93%, a specificity of 40%, a positive predictive value (PPV) of 88% and a negative predictive value (NPV) of 55%. CONCLUSIONS: In a region with a high prevalence of pulmonary fungal infection, FDG-PET is sensitive but has a low specificity and NPV for identifying NSCLC. In our study cohort, FDG-PET does not appear to reduce the need for SPN biopsies.

Adult↗
PubMed2002

Peripheral blood intracellular cytokine analysis in children newly diagnosed with inflammatory bowel disease.

Patterns of cytokine profiles have emerged for different forms of inflammatory bowel disease with a predominance of type 1 cytokines in patients with Crohn disease and type 2 cytokine expression in patients with ulcerative colitis. Most of these studies have involved older patients with long-standing disease or after various therapeutic interventions, and patterns of cytokine expression were hypothesized to be influenced by these factors. To evaluate for these possibilities, we studied 23 patients (15 boys) with newly diagnosed Crohn disease (n = 14) or ulcerative colitis. Their mean age at diagnosis was 13.1 +/- 2.9 y (mean +/- SD). Healthy control subjects (n = 9) were previously obtained. Peripheral blood intracellular cytokine analysis was performed within 24 h using a modification of Becton Dickinson's FastImmune Cytokine system. Multiparametric flow cytometry and phenotyping of lymphocytes was performed. T-cell populations were defined as type 1 being CD69(+), CD3(+), and interferon-gamma(+) and type 2 being CD69(+), CD3(+), and IL-4(+). The median percent of type 1 T cells from normal subjects (2.8%) was similar to that of ulcerative colitis subjects (1.8%, p > 0.20) but greater than that of Crohn disease subjects (0.55%, p = 0.05). The median percent of type 2 lymphocytes in normal subjects (1.8%) was greater than that of ulcerative colitis subjects (0.35%, p = 0.02) but was similar to that of Crohn disease subjects (1.1%, p > 0.20). Serial determinations showed the median percent of type 2 T cells increased in ulcerative colitis patients as remission was induced. Reduced activated peripheral type 1 T cells of newly diagnosed, untreated children are similar to interferon-gamma expression in mucosa of adults with postoperative recurrence. Reduced type 2 cytokine expression patterns in subjects with ulcerative colitis are similar to lamina propria T-cell expression levels in adults and improve with disease remission.

Adolescent↗
PubMed2002

Estimation of performance and sequential selection of diagnostic tests in patients with lung lesions suspicious for cancer.

CONTEXT: Measuring variation in clinician test ordering behavior for patients with similar indications is an important focus for quality management and cost containment. OBJECTIVE: To obtain information from physicians and nonphysicians regarding their test-ordering behavior and their knowledge of test performance characteristics for diagnostic tests used to work up patients with lung lesions suspicious for cancer. DESIGN: A self-administered, voluntary, anonymous questionnaire was distributed to 452 multiple-specialty physicians and 500 nonphysicians in academic and private practice in Pennsylvania, Iowa, and North Carolina. Respondents indicated their estimates of test sensitivities for multiple tests used in the diagnosis of lung lesions and provided their test selection strategy for case simulations of patients with solitary lung lesions. Data were analyzed using descriptive statistics and the chi(2) test. RESULTS: The response rate was 11.2%. Both physicians and nonphysicians tended to underestimate the sensitivities of all minimally invasive tests, with the greatest underestimations reported for sputum cytology and transthoracic fine-needle aspiration biopsy. There was marked variation in sequential test selection for all the case simulations and no association between respondent perception of test sensitivity and their selection of first diagnostic test. Overall, the most frequently chosen first diagnostic test was bronchoscopy. CONCLUSIONS: Physicians and nonphysicians tend to underestimate the performance of diagnostic tests used to evaluate solitary lung lesions. However, their misperceptions do not appear to explain the wide variation in test-ordering behavior for patients with lung lesions suspicious for cancer.

Biopsy, Needle↗
PubMed2001

Imaging of chronic posttraumatic osteomyelitis.

Posttraumatic osteomyelitis is frequently characterized by chronicity and recurrent activation of infection. The diagnosis is usually made on the basis of clinical, laboratory, and imaging examinations. The conventional radiograph is the basic imaging study that provides important information about skeletal deformity, bone quality, identification of metallic implants, and consolidation of the former fracture site. Other imaging techniques are required to determine the grade of activity, to define the extent of infection and to delineate small sequestra, intraosseus fistula and abscesses. A variety of more sophisticated modalities, such as modern cross-sectional imaging and radionuclide studies, are available, and the decision to choose the most suitable method can be very difficult. This review gives an overview of definition, epidemiology, and pathophysiology of chronic posttraumatic osteomyelitis and discusses the value of currently used imaging modalities.

Aged↗
PubMedDate not supplied

[An unusual homicide case with subsequent suicide].

In the medicolegal literature reports on homicides followed by suicide, especially in elderly people, are rare. In the present case, the victim, a 79-year-old woman, showed a rather unusual injury pattern: 3 gunshots to the head (with only 2 entrance wounds and 3 intracranial projectiles) and 2 stabs from a knife. The tools used for inflicting the stab wounds (a hunting knife and a double-edged dagger) were left in the victim's body after the offense. The 89-year-old husband hanged himself with an aerial cable after killing his wife. The police investigations and the autopsy findings suggested a combined homicide-suicide. The motive for the offense could be a so-called delusion of poverty associated with symptoms of depression.

Aged↗