Morphologic changes correlating to different sensitivities of Escherichia coli and enterococcus faecalis to Nd:YAG laser irradiation through dentin

BACKGROUND AND OBJECTIVE: Previous studies demonstrated the disinfecting potential of Nd:YAG laser irradiation on the root canal system from an overall quantitative viewpoint. The aim of this study was to evaluate the specific effect of irradiation through dentin on gram-negative and gram-positive bacteria with regard to their cell structure. STUDY DESIGN/MATERIALS AND METHODS: Sterile dentin samples of standardized size were divided into two sets of four groups with eight samples each. The first set was inoculated with Escherichia coli as the gram-negative test strain, the second set was inoculated with Enterococcus faecalis, which served as the gram-positive test organism. The samples were then irradiated on the bacteria-free side in contact mode under constant scanning movement at an angle of 10 degrees by use of the fiber optic of the Nd:YAG laser. Upon laser treatment they were critical point dried and subjected to SEM investigation. Another two sets of samples were prepared and irradiated in the same manner and evaluated by standard microbiological procedures to verify whether the observed morphologic alterations correlated to cell death. RESULTS: SEM investigations revealed damage pattens that increased with the amount of energy applied. Whereas the gram-negative test organism showed immediate structural injury, the gram-positive test organism required repeated application of irradiation. The microbiological examination showed reduction of both bacterial strains, yet to different extents. CONCLUSION: Our study demonstrates the different morphologic impact of Nd:YAG laser irradiation through dentin on representatives of the two main groups of bacteria. It shows that the construction of the cell wall is crucial for their individual sensitivity to laser treatment.     

Delineation of brain tumor extent with [11C]L-methionine positron emission tomography: local comparison with stereotactic histopathology.

PURPOSE: Methyl-[11C]L-methionine ([11C]MET) positron emission tomography (PET) in brain tumors reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging in stereotactic biopsy planning. It remains unclear whether the increased [11C]MET uptake is limited to solid tumor tissue or even detects infiltrating tumor parts. EXPERIMENTAL DESIGN: In 30 patients, a primary or recurrent brain tumor was suspected on magnetic resonance imaging. Patients were investigated with [11C]MET-PET before stereotactic biopsy. The biopsy trajectories were plotted into the [11C]MET-PET images with a newly designed C-based software program. The exact local [11C]MET uptake was determined within rectangular regions of interest of 4 mm in width and length aligned with the biopsy specimen. Individual histologic specimens were rated for the presence of solid tumor tissue, infiltration area, and nontumorous tissue changes. RESULTS: Receiver operating characteristics analysis demonstrated a sensitivity of 87% and specificity of 89% for the detection of tumor tissue at a threshold of 1.3-fold [11C]MET uptake relative to normal brain tissue. At this threshold, only 13 of 100 tumor positive specimen were false negative mainly in grade 2 astrocytoma. In grade 2 astrocytoma, mean [11C]MET uptake in the infiltration area was significantly higher than in solid tumor tissue (P < 0.003). CONCLUSIONS: [11C]MET-PET detects solid parts of brain tumors, as well as the infiltration area at high sensitivity and specificity. High [11C]MET uptake in infiltrating tumor of astrocytoma WHO grade 2 reflects high activity in this tumor compartment. Molecular imaging, with [11C]MET, will guide improved management of patients with brain tumors.     

Staging of rectal cancer by double-contrast MR imaging using the rectally administered superparamagnetic iron oxide contrast agent ferristene and IV gadodiamide injection: results of a multicenter phase II trial

The aim of this study was to assess the accuracy of double-contrast magnetic resonance imaging (MRI) with rectal application of the superparamagnetic iron oxide contrast agent (SPIO) ferristene and IV gadodiamide for preoperative staging of rectal cancer. In a randomized phase II dose-ranging trial, 113 patients were studied preoperatively with one of four different formulations of ferristene (Abdoscan) as an enema before MRI. T1-weighted spin-echo (T1w SE) and T2w turbo spin-echo (TSE) single-contrast images were obtained as well as T1w SE and gradient-echo (GRE) double-contrast images after IV gadodiamide injection (Omniscan). Images were assessed qualitatively, and TNM tumor stage was compared with histopathology. High-viscosity ferristene formulations were superior to low-viscosity formulations in tumor staging (accuracy 90% vs 74%, P < 0.01). There was no significant difference between high and low iron content ferristene. MRI had a sensitivity of 97%, specificity of 50%, and accuracy of 82% for staging of rectal carcinoma higher than T2 stage. At receiver operator characteristic (ROC) analysis, MR differentiation between T1/T2 and T3/T4 tumor stages yielded a ROC index of 0.848. Double-contrast MRI is an accurate method for preoperative staging of rectal cancer.     

Contrast-enhanced color Doppler sonography for evaluation of enlarged cervical lymph nodes in head and neck tumors

OBJECTIVE: We determined whether contrast-enhanced color Doppler sonography can differentiate benign from malignant enlarged cervical lymph nodes in head and neck tumors. SUBJECTS AND METHODS: Ninety-four enlarged lymph nodes in 39 adult patients (32 men and seven women; age range, 30-81 years) were examined with B-mode sonography and with unenhanced and contrast-enhanced color Doppler sonography. All patients had carcinoma of the oral cavity. Histologically, lymphadenitis was found in 57 nodes and metastases in 37 nodes. Geometric dimension, texture, and margin of the node and detection and location of vessels were noted. Histology and imaging findings were correlated. RESULTS: The transverse-to-longitudinal diameter ratio in combination with texture and margin analysis resulted in a correct diagnosis in only approximately 79% of the nodes. With contrast-enhanced color Doppler sonography, 86% of nodes showed vessels, and 28% of nodes showed vessels with this technique exclusively. Characteristic configurations were identified: hilar vessels with branching indicated lymphadenitis (sensitivity, 98%; specificity, 100%), and predominantly peripheral vessels indicated metastases (100%, 98%). These findings changed the diagnosis in 13 nodes, changed the therapy in four patients, and led to an incorrect diagnosis in one patient. CONCLUSION: Enlarged lymph nodes can be characterized as metastatic or inflammatory with high diagnostic accuracy on the basis of their vascular architecture as seen on contrast-enhanced color Doppler sonography.     

Skleromyxödem

Scleromyxedema is a rare disorder that frequently affects multiple extracutaneous organ systems and is usually associated with monoclonal gammopathy. The pathogenesis of scleromyxedema is unknown. The clinical course is chronic and progressive and can lead to marked morbidity or death. The skin findings consist of multiple waxy papules and indurated plaques. Progressive skin involvement can lead to decreased mobility of the mouth and joints. Extracutaneous manifestations occur in the musculoskeletal or cardiovascular system, in the gastrointestinal or respiratory tract, or in the kidneys. There are no approved or evidence-based treatment options available for scleromyxedema. High-dose immunoglobulins are considered the treatment of choice, followed by lenalidomide (or thalidomide) and systemic glucocorticosteroids, or in severe cases even autologous hematopoetic stem cell transplantation. Long-term maintenance treatment is usually required and close clinical follow-up is necessary as recurrence of scleromyxedema is common after withdrawal of an effective therapy.