BackgroundThe rigorous elicitation of user needs is a crucial step for both medical device design and purchasing. However, user needs elicitation is often based on qualitative methods whose findings can be difficult to integrate into medical decision-making. This paper describes the application of AHP to elicit user needs for a new CT scanner for use in a public hospital.MethodsAHP was used to design a hierarchy of 12 needs for a new CT scanner, grouped into 4 homogenous categories, and to prepare a paper questionnaire to investigate the relative priorities of these. The questionnaire was completed by 5 senior clinicians working in a variety of clinical specialisations and departments in the same Italian public hospital.ResultsAlthough safety and performance were considered the most important issues, user needs changed according to clinical scenario. For elective surgery, the five most important needs were: spatial resolution, processing software, radiation dose, patient monitoring, and contrast medium. For emergency, the top five most important needs were: patient monitoring, radiation dose, contrast medium control, speed run, spatial resolution.ConclusionsAHP effectively supported user need elicitation, helping to develop an analytic and intelligible framework of decision-making. User needs varied according to working scenario (elective versus emergency medicine) more than clinical specialization. This method should be considered by practitioners involved in decisions about new medical technology, whether that be during device design or before deciding whether to allocate budgets for new medical devices according to clinical functions or according to hospital department.

One of the main vital signs used in patient monitoring during Magnetic Resonance Imaging (MRI) is Electro-Cardio-Gram (ECG). Unfortunately, magnetic fields gradients induce artefacts which severely affect ECG quality. Adaptive Noise Cancelling (ANC) is one of the preferred techniques for artefact removal. ANC involves the adaptive estimation of the impulse response of the system constituted by the MRI equipment, the patient and the ECG recording device. Least Mean Square (LMS) adaptive filtering has been traditionally employed because of its simplicity: anyway, it requires the choice of a step-size parameter, whose proper value for the specific application must be estimated case by case: an improper choice could yield slow convergence and unsatisfactory behaviour. Recursive Least Square (RLS) algorithm has, potentially, faster convergence while not requiring any parameter. As far as the authors' knowledge, there is no systematic analysis of performances of RLS in this scenario. In this study we evaluated the performance of RLS for adaptive removal of artefacts induced by magnetic field gradients on ECG in MRI, in terms of efficacy of suppression. Tests have been made on real signals, acquired via an expressly developed system. A comparison with LMS was made on the basis of opportune performance indices. Results indicate that RLS is superior to LMS in several respects.

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Background: An inadequate shielding of radio-frequency cabins for magnetic resonance imaging devices can affect clinical images with artifacts. For this reason, periodic measurements of shielding effectiveness are recommended. However, a wide gap exists between the international reference standard currently available for shielding effectiveness measurement (IEEE-Std 299/2006) and the practical approach, mainly because of the poor applicability of the standard to any situation. Objective: The aim of this work is to suggest a novel procedure for the measurement of the shielding effectiveness of radiofrequency cabins for clinical magnetic resonance imaging devices. The application of the cabin door measurements for shielding effectiveness assessment is proposed. Methods: Based on the only international standard currently available, some critical aspects of shielding effectiveness measurements are highlighted. Taking into account theoretical considerations, a novel approach is suggested in order to simplify the applicability of the standard. Frequency ranges and measurement points were reduced by considering the specific device inside the shield. Results: Results obtained by the application of the proposed protocol were compared with the results obtained by the application of the standard procedure IEEE-Std 299/2006. No significant discrepancies between measurements have been found. It was observed that the time to perform measurements reduced by almost three times. Conclusion: A time-saving method for measurement of shielding effectiveness in a narrow range of frequencies is proposed.

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