The 2006 Henry N. Wagner Lecture: Of mice and men (and positrons)--advances in PET imaging technology.

There have been major advances in PET technology that cumulatively have helped improve image quality, increased the range of applications for PET, and contributed to the more widespread use of PET. Examples of these technologic advances include whole-body imaging, 3-dimensional imaging, new scintillator materials, iterative reconstruction algorithms, combined PET/CT, and preclinical PET. New advances on the immediate horizon include the reintroduction of time-of-flight PET, which takes advantage of the favorable timing properties of newer scintillators; the integration of PET and MRI scanners into a dual-modality imaging system; and the possibility of further significant improvements in spatial resolution in preclinical PET systems. Sensitivity remains a limiting factor in many PET studies. Although, conceptually, huge gains in sensitivity are still possible, realizing these gains is thwarted largely by economic rather than scientific concerns. Predicting the future is fraught with difficulty; nonetheless, it is apparent that ample opportunities remain for new development and innovation in PET technology that will be driven by the demands of molecular medicine, notably sensitive and specific molecular diagnostic tools and the ability to quantitatively monitor therapeutic entities that include small molecules, peptides, antibodies, nanoparticles, DNA/RNA, and cells.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

3D PET using a conventional multislice tomograph without septa

A conventional multislice positron emission tomography scanner was modified to operate without interplane septa to evaluate its performance in collecting and reconstructing data in a three-dimensional (3D) format, thereby significantly increasing system sensitivity. A 3D filtered backprojection algorithm was implemented and tested, using both computer simulations and phantom measurements. No artifacts were apparent in the test images, although the algorithm was shown to lead to a 11% degradation in transaxial resolution in the outer planes. Following septa removal, sensitivity was found to increase by a factor of 7 with an increase in scatter fraction from 16 to 41%. Axial resolution degraded from 6.9 to 7.7 mm full width at half maximum at the center of the field of view. The maximum count rate without septa was 2.4 x 10(5) cps, at a concentration of 0.4 microCi/ml, compared with 1.3 x 10(5) cps at 1.5 microCi/ml with septa. Brain studies were performed with volunteers using 18F-fluorodeoxyglucose, 18F-fluorodopa, and H2 15O to compare noise-equivalent count rates and qualitatively assess image quality over a wide range of imaging conditions.     

用于筛选天然产物中脲酶抑制剂的脲酶活性测试方法的建立

抑制幽门螺杆菌产生的脲酶具有治疗胃炎和消化性溃疡的作用。用酚红指示剂和Ｂｅｒｔｈｅｌｏｔ试剂在９６孔培养板上检测重组脲酶活性，其灵敏度指标酚红法每ｍｇ酶蛋白引起的每分钟吸光度变化。△Ａ为６．９，而Ｂｅｒｔｈｅｌｏｔ法每ｍｇ酶蛋白引起的每分钟吸光度比值变化△Ａ为３１３。结果表明用Ｂｅｒｔｈｅｌｏｔ试剂检测重组脲酶活性适宜在９６孔培养板上大规模筛选天然产物中的脲酶抑制剂。