Can the channelized Hotelling observer including aspects of the human visual system predict human observer performance in mammography?

PURPOSE: In mammography, images are processed prior to display. Model observers (MO) are candidates to objectively evaluate processed images if they can predict human observer performance for detail detection. The aim of this study was to investigate if the channelized Hotelling observer (CHO) can be configured to predict human observer performance in mammography like images. METHODS: The performance correlation between human observers and CHO has been evaluated using different channel-sets and by including aspects of the human visual system (HVS). The correlation was investigated for the detection of disk-shaped details in simulated white noise (WN) and clustered lumpy backgrounds (CLB) images, representing respectively quantum noise limited and mammography like images. The images were scored by the MO and five human observers in 2-alternative forced choice experiments. RESULTS: For WN images the most useful formulation of the CHO to predict human observer performance was obtained using three difference of Gaussian channels without adding HVS aspects (RLR2=0.62). For CLB images the most useful formulation was the partial least square channel-set without adding HVS aspects (RLR2=0.71). The correlation was affected by detail size and background. CONCLUSIONS: This study has shown that the CHO can predict human observer performance. Due to object size and background dependency it is important that the range of object sizes and allowed variability in background are specified and validated carefully before the CHO can be implemented for objective image quality assessment.

[Piperacillin: comparison of antibacterial activity in vitro during the triennium 1986-88 versus the biennium 1981-82]. / Piperacillina: verifica dell'attività antibatterica in vitro nel triennio 1986-88 versus quella del biennio 1981-82.

The antibacterial activity in vitro of piperacillin on strains commonly isolated in hospital practice in 1986-88 was compared with that obtained for piperacillin from 1981 to 1982 and with the activity of other antibiotics usually employed. Piperacillin showed a good antibacterial activity on Gram-positive and Gram-negative strains, while few resistant strains were found.

[Reliability of the bacterial identification tests and of antibiotic sensitivity tests made with automatic methods]. / Attendibilità delle prove di identificazione batterica e degli antibiogrammi ottenuti con metodi automatici.

A "MS-2 Microbiology System" (Abbott) has been used to identify and to assess the susceptibility patterns of clinically isolated bacteria from highly compromised patients. Automatically obtained results by the analysis of 300 specimens were compared to those of traditional methods. The automated system was in good agreement with API (81%) while in 4% of the strains there were major discrepancies, and 5% of the experiments were carried out with slow growing bacteria which normally give poor results in automatic systems. Antimicrobial susceptibility testing was satisfactory in 84% of the specimens with 7% of minor discrepancies and 9% of major ones. The evaluation of MIC for slow growing organisms like Haemophilus, Diplococcus and anaerobes belonging to the Bacteroides genus, was the same using either automatic or standard procedures.

[Automated direct antimicrobial susceptibility testing of urine specimens]. / Automazione dell'antibiogramma diretto sulle urine.

Two microscopical screening methods have been used to assay the suitability of urine samples for automated direct antimicrobial susceptibility testing by the means of a "MS-2 Microbiology System" apparatus. Gram stained smears showed if specimens were monomicrobic and fresh-mount bacterioscopy gave information about presumptive counts to establish inoculum size. The results obtained by the automated method have been compared with those of the direct disk diffusion method and the classical Stokes method on a single isolated colony. The three systems were reliable and only 7% of specimens gave major discrepancies and 15% minor errors. The influence of each antibiotic drug and of each bacterial species on the discrepancies has been discussed. Direct susceptibility testing by MS-2 seems to be accurate and in the same time so fast (5-6 h vs. 18-24 h) to appear very useful in the rational guide of chemotherapy in the more severe UTI.

On-site geropsychiatric services to guests of residential homes.

During a 7.5-year liaison between a 152-bed residential (multi-level care) home for the aged and a psychiatrist-social worker team, 58 of the 339 residents were referred to the team. With increasing expertise of the staff of the home and with early psychosocial intervention, the need for psychiatric hospitalization dropped virtually to zero. Of the 23 persons currently referred, 65 percent are recovering well with psychiatric-social-nursing support and psychotropic drugs; another 26 percent are achieving significant behavioral improvement without change in their chronic mental confusion. The average time required of the psychiatrist proved to be four hours monthly; telephone consultations averaged two hours monthly. About half an hour per week was spent in conference between the psychiatrist and social worker, to allow achievement of mutual goals. Appropriate one-site psychiatric-social therapy permitted continuity of care and usually prevented threatened disruption of the residnets' lives. Thus the modest investment of time by the psychiatrist and social worker improved the level of life satisfaction, not only for the patients but for the Home.