Diagnostic value of micrographia in Parkinson's disease : a study with [I-123]FP-CIT SPECT

Micrographia is a common symptom of Parkinson's disease (PD), and it may precede other motor symptoms. Despite the high prevalence of micrographia in PD, its neurobiological mechanisms are not known. Given that levodopa may alleviate consistent micrographia and that nondopaminergic essential tremor (ET) is not associated with micrographia, micrographia could possibly be used as an ancillary diagnostic method that reflects nigrostriatal dopamine function. We evaluated the usefulness of micrographia as a simple one-sentence writing test in differentiating PD from ET. A total of 146 PD patients, 42 ET patients and 38 healthy controls provided writing samples and were scanned with brain [I-123]FP-CIT dopamine transporter (DAT) SPECT imaging with ROI-based and voxelwise analyses. The diagnostic accuracy of micrographia was evaluated and compared to that of DAT binding. Compared to ET and healthy controls, PD patients showed micrographia (consistent, 25.6% smaller area of handwriting sample in PD compared to ET, p = 0.002, and 27.2% smaller area of handwriting compared to healthy controls, p = 0.004). PD patients showed 133% more severe progressive micrographia compared with ET patients (median b = - 0.14 in PD, b = - 0.06 in ET, p = 0.021). In early unmedicated cognitively normal patients, consistent micrographia showed 71.2% specificity and 87.5% sensitivity in PD versus ET differentiation, but micrographia had no correlation with striatal or extrastriatal [I-123]FP-CIT binding in patients with PD. The one-sentence micrographia test shows moderately good accuracy in PD versus ET differentiation. The severity of micrographia has no relationship with DAT binding, suggesting nondopaminergic mechanism of micrographia in PD. ClinicalTrials.gov identifier: NCT02650843 (NMDAT study).Peer reviewe

Diagnostic value of micrographia in Parkinson's disease: a study with [I-123]FP-CIT SPECT

Micrographia is a common symptom of Parkinson's disease (PD), and it may precede other motor symptoms. Despite the high prevalence of micrographia in PD, its neurobiological mechanisms are not known. Given that levodopa may alleviate consistent micrographia and that nondopaminergic essential tremor (ET) is not associated with micrographia, micrographia could possibly be used as an ancillary diagnostic method that reflects nigrostriatal dopamine function. We evaluated the usefulness of micrographia as a simple one-sentence writing test in differentiating PD from ET. A total of 146 PD patients, 42 ET patients and 38 healthy controls provided writing samples and were scanned with brain [123I]FP-CIT dopamine transporter (DAT) SPECT imaging with ROI-based and voxelwise analyses. The diagnostic accuracy of micrographia was evaluated and compared to that of DAT binding. Compared to ET and healthy controls, PD patients showed micrographia (consistent, 25.6% smaller area of handwriting sample in PD compared to ET, p = 0.002, and 27.2% smaller area of handwriting compared to healthy controls, p = 0.004). PD patients showed 133% more severe progressive micrographia compared with ET patients (median b = - 0.14 in PD, b = - 0.06 in ET, p = 0.021). In early unmedicated cognitively normal patients, consistent micrographia showed 71.2% specificity and 87.5% sensitivity in PD versus ET differentiation, but micrographia had no correlation with striatal or extrastriatal [123I]FP-CIT binding in patients with PD. The one-sentence micrographia test shows moderately good accuracy in PD versus ET differentiation. The severity of micrographia has no relationship with DAT binding, suggesting nondopaminergic mechanism of micrographia in PD. ClinicalTrials.gov identifier: NCT02650843 (NMDAT study).</p

Frequency-Domain Equalization in Single-Carrier Transmission: Filter Bank Approach

This paper investigates the use of complex-modulated oversampled filter banks (FBs) for frequency-domain equalization (FDE) in single-carrier systems. The key aspect is mildly frequency-selective subband processing instead of a simple complex gain factor per subband. Two alternative low-complexity linear equalizer structures with MSE criterion are considered for subband-wise equalization: a complex FIR filter structure and a cascade of a linear-phase FIR filter and an allpass filter. The simulation results indicate that in a broadband wireless channel the performance of the studied FB-FDE structures, with modest number of subbands, reaches or exceeds the performance of the widely used FFT-FDE system with cyclic prefix. Furthermore, FB-FDE can perform a significant part of the baseband channel selection filtering. It is thus observed that fractionally spaced processing provides significant performance benefit, with a similar complexity to the symbol-rate system, when the baseband filtering is included. In addition, FB-FDE effectively suppresses narrowband interference present in the signal band

Pilot Allocation and Computationally Efficient Non-Iterative Estimation of Phase Noise in OFDM

This letter proposes a pilot subcarrier allocation approach for orthogonal frequency division multiplexing systems, which enables construction of symbol-wise phase-noise (PN) estimates with high efficiency and low overhead in a non-iterative manner. The complexity and performance of the overall PN suppression algorithm together with the proposed pilot allocation approach are evaluated in 5G single-user-multiple-input multiple-output (MIMO) and multi-user-MIMO radio links at 28 GHz carrier frequency, showing clear complexity-performance benefits against a state-of-the-art reference algorithm.acceptedVersionPeer reviewe

Frequency-Domain Equalization in Single-Carrier Transmission: Filter Bank Approach

This paper investigates the use of complex-modulated oversampled filter banks (FBs) for frequency-domain equalization (FDE) in single-carrier systems. The key aspect is mildly frequency-selective subband processing instead of a simple complex gain factor per subband. Two alternative low-complexity linear equalizer structures with MSE criterion are considered for subband-wise equalization: a complex FIR filter structure and a cascade of a linear-phase FIR filter and an allpass filter. The simulation results indicate that in a broadband wireless channel the performance of the studied FB-FDE structures, with modest number of subbands, reaches or exceeds the performance of the widely used FFT-FDE system with cyclic prefix. Furthermore, FB-FDE can perform a significant part of the baseband channel selection filtering. It is thus observed that fractionally spaced processing provides significant performance benefit, with a similar complexity to the symbol-rate system, when the baseband filtering is included. In addition, FB-FDE effectively suppresses narrowband interference present in the signal band.</p

Channel Equalization in Filter Bank Based Multicarrier Modulation for Wireless Communications

Channel equalization in filter bank based multicarrier (FBMC) modulation is addressed. We utilize an efficient oversampled filter bank concept with 2x-oversampled subcarrier signals that can be equalized independently of each other. Due to Nyquist pulse shaping, consecutive symbol waveforms overlap in time, which calls for special means for equalization. Two alternative linear low-complexity subcarrier equalizer structures are developed together with straightforward channel estimation-based methods to calculate the equalizer coefficients using pointwise equalization within each subband (in a frequency-sampled manner). A novel structure, consisting of a linear-phase FIR amplitude equalizer and an allpass filter as phase equalizer, is found to provide enhanced robustness to timing estimation errors. This allows the receiver to be operated without time synchronization before the filter bank. The coded error-rate performance of FBMC with the studied equalization scheme is compared to a cyclic prefix OFDM reference in wireless mobile channel conditions, taking into account issues like spectral regrowth with practical nonlinear transmitters and sensitivity to frequency offsets. It is further emphasized that FBMC provides flexible means for high-quality frequency selective filtering in the receiver to suppress strong interfering spectral components within or close to the used frequency band

Channel Equalization in Filter Bank Based Multicarrier Modulation for Wireless Communications

Channel equalization in filter bank based multicarrier (FBMC) modulation is addressed. We utilize an efficient oversampled filter bank concept with 2x-oversampled subcarrier signals that can be equalized independently of each other. Due to Nyquist pulse shaping, consecutive symbol waveforms overlap in time, which calls for special means for equalization. Two alternative linear low-complexity subcarrier equalizer structures are developed together with straightforward channel estimation-based methods to calculate the equalizer coefficients using pointwise equalization within each subband (in a frequency-sampled manner). A novel structure, consisting of a linear-phase FIR amplitude equalizer and an allpass filter as phase equalizer, is found to provide enhanced robustness to timing estimation errors. This allows the receiver to be operated without time synchronization before the filter bank. The coded error-rate performance of FBMC with the studied equalization scheme is compared to a cyclic prefix OFDM reference in wireless mobile channel conditions, taking into account issues like spectral regrowth with practical nonlinear transmitters and sensitivity to frequency offsets. It is further emphasized that FBMC provides flexible means for high-quality frequency selective filtering in the receiver to suppress strong interfering spectral components within or close to the used frequency band.</p