Characterization of interstimulus interaction in the multiple auditory steady-state responses at high sound levels.

Multiple auditory steady-state response (MASSR) is recommended to estimate hearing thresholds in difficult-to-test individuals. The multiple stimuli that evoke MASSR may present an interstimulus interaction (ISI) that is able to distort the generation of responses. No consensus exists on the effects of the ISI in MASSR when dealing with high sound level stimuli or cases of sensorineural hearing loss. This study investigated the effects of ISI on the amplitude and detectability of auditory steady-state responses, with a focus at and above 65 dB sound pressure level (SPL). Normal hearing (NH) and sensorineural hearing impaired (SNHI) adults were tested with different stimulus types [amplitude modulation (AM) One octave chirp (OC), and a weighted OC (WOC)], stimulus levels, and modalities (single or multiple stimuli). ISI typically attenuated response amplitude of a control stimulus caused by an interference stimulus one octave above the control stimulus. At and above 80 dB SPL, attenuations of around 50% decreased the number of detectable responses near SNHI thresholds, especially for OC and WOC. AM stimuli obtained a higher detection rate than OC and WOC when presented 10 dB above the behavioral hearing threshold of SNHI participants. Using OC in MASSR when assessing elevated thresholds might diminish accuracy on threshold estimation, and extend test duration.

The effectiveness of temperature control of thermocyclers in PCR optimization.

This study evaluated the effectiveness of thermocycler temperature control, considering the influence of other determinant factors for the optimization of PCR. The reduction in the number of repeated PCR tests, applied in the diagnosis and prognosis of chronic myeloid leukemia at the National Cancer Institute in Brazil, was used as a measure of effectiveness. This indicator was evaluated using samples obtained before and after the temperature control in the wells of the thermocyclers. There was a reduction of 18.9% in the number of repeated exams in the second sample. A structured interview with laboratory staff indicated that there was no change in the other determinant factors.

Assessment of frequency specific auditory steady-state response using amplitude modulation with 2-order exponential envelope.

This study investigated the performance of Frequency Specific Auditory Steady-State Response (FS-ASSR) detection elicited by the amplitude modulated tone with 2-order exponential envelope (AM2), using objective response detection (ORD) techniques of Spectral F-Test (SFT) and Magnitude Squared Coherence (MSC). ASSRs from 24 normal hearing adults were obtained during binaural multi-tone stimulation of amplitude-modulation (AM) and AM2 at intensities of 60, 45 and 30 dBSPL. The carrier frequencies were 500, 1000, 2000, and 4000 Hz, modulated between 77 and 105 Hz. AM2 achieve FS-ASSR amplitudes higher than AM by 16%, 18% and 12% at 60, 45 and 30 dBSPL, respectively, with a major increase at 500 Hz (22.5%). AMS2PL increased the Detection Rate (DR) up to 8.3% at 500 Hz for 30 dBSPL, which is particularly beneficial for FS-ASSR detection near the hearing threshold. In addition, responses in 1000 and 4000 Hz were consistently increased. The MSC and SFT presented no differences in Detection Rate (DR). False Detection Rate (FDR) was close to 5% for both techniques and tones. Detection times to reach DR over 90% were 3.5 and 4.9 min at 60 and 45 dBSPL, respectively. Further investigation concerning efficient multiple FS-ASSR is still necessary, such as testing subjects with hearing loss.

Recovery coefficients determination for partial volume effect correction in oncological PET/CT images considering the effect of activity outside the field of view.

OBJECTIVES: The partial volume effect (PVE) has a great impact in quantitative PET/CT imaging. Correction methods have been recently proposed by many authors to make the image quantification more accurate. This work presents a methodology for determining the recovery coefficients (RCs) for PVE correction in PET/CT images. It was taken into account the radioactivity outside the field of view (FOV), which is expected in a patient image acquisition. METHODS: The NEMA image quality phantom and the NEMA scatter phantom were used. The phantoms were filled with (18)F-FDG for different sphere-to-background ratios. The RCs have been determined from image acquisitions in a Siemens Biograph 16 Hi-Rez PET/CT scanner with and without the scatter phantom. RESULTS: The RC values that ranged from 0.38 to 1.00 without the scatter phantom exhibited a wider variation when this latter was taken into account (from 0.27 to 1.02). This more realistic estimation must be considered if one takes into account that an incorrect SUV measure in tumors leads to errors in the evaluation of the response to therapy based on PET/CT images. CONCLUSIONS: The activity outside the FOV should be considered in RCs determination to improve the RC-based PVE correction method.

Laboratório para inspeçäo de ventiladores pulmonares (LIVE) / Laboratory for inspection of pulmonary ventilators (LIVE)

Segundo classificação do Ministério da Saúde, Ventiladores Pulmonares (VP) se enquadram na lista dos equipamentos de alto risco. Este trabalho investiga as condições de emprego e manutenção dos VP de um hospital público de grande porte localizado no município do Rio de Janeiro. Os resultados proporcionaram subsídios para destacar a importância de um Laboratório de Inspeção de Ventiladores que atue no gerenciamento e adeuação desses equipamentos nas diversas unidades do hospital

Abstract - According to the classification of Ministry of Health, Lung Ventilators are included in the list of high risk medical devices. This paper investigates the conditions of employment and maintenance of Jung ventilators in a large public hospital located in the city of Rio de Janeiro. The results raised subsidies to point out the importance of a Laboratory for Inspection of Ventilators to act on the management and adequateness of these equipments in the hospital units