Muscles of myositis patients examined with MRI demonstrate heterogeneous pathology ranging from unaffected muscle groups to severe inflammation, fat infiltration, and eventually, more serious fat replacement. The purpose of this investigation was to characterize myositic thigh muscles using diffusion-weighted imaging (DWI) and to examine fluid motion at various disease stages. We chose to characterize total fluid motion within the muscle using the model proposed by Le Bihan et al (6,7) in which the apparent diffusion coefficient (ADC), diffusion in the extra-and intracellular muscle compartments (D), perfusion in capillaries (pseudodiffusion) (D*), and volume fraction of capillary perfusion (f) are determined. Unaffected patient muscles have DWI coefficients equivalent to those of normal muscles. Inflamed muscles show elevated ADC and D values compared to normal muscles (P Ͻ 0.0005), and fatinfiltrated muscles have lower values than control muscles (P Ͻ 0.001). Inflamed muscles have lower f values than unaffected muscles (P Ͻ 0.009), suggesting decreased fractional volume of capillary perfusion. DWI provides quantitative data on molecular fluid motion in diseased muscles and affords the potential for longitudinal monitoring of myositic patients.

The underlying waveform has always been a shaping factor for each generation of the cellular networks, such as orthogonal frequency division multiplexing (OFDM) for the 4th generation cellular networks (4G). To meet the diversified and pronounced expectations upon the upcoming 5G cellular networks, here we present an enabler for flexible waveform configuration, named as filtered-OFDM (f-OFDM). With the conventional OFDM, a unified numerology is applied across the bandwidth provided, balancing among the channel characteristics and the service requirements, and the spectrum efficiency is limited by the compromise we made. In contrast, with f-OFDM, the assigned bandwidth is split up into several subbands, and different types of services are accommodated in different subbands with the most suitable waveform and numerology, leading to an improved spectrum utilization. After outlining the general framework of f-OFDM, several important design aspects are also discussed, including filter design and guard tone arrangement. In addition, an extensive comparison among the existing 5G waveform candidates is also included to illustrate the advantages of f-OFDM. Our simulations indicate that, in a specific scenario with four distinct types of services, f-OFDM provides up to 46% of throughput gains over the conventional OFDM scheme.

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