Improved motion correction capabilities for fast spin echo T1 FLAIR propeller using non‐Cartesian external calibration data driven parallel imaging

Patient motion is a common challenge in the clinical setting and fast spin echo longitudinal relaxation time fluid attenuating inversion recovery imaging method with motion correction would be highly desirable. The motion correction provided by transverse relaxation time‐ and diffusion‐weighted periodically rotated overlapping parallel lines with enhanced reconstruction methods has seen significant clinical adoption. However, periodically rotated overlapping parallel lines with enhanced reconstruction with fast spin echo longitudinal relaxation time fluid attenuating inversion recovery‐weighting has proved challenging since motion correction requires wide blades that are difficult to acquire while also maintaining short echo train lengths that are optimal for longitudinal relaxation time fluid attenuating inversion recovery‐weighting. Parallel imaging provides an opportunity to increase the effective blade width for a given echo train lengths. Coil‐by‐coil data‐driven autocalibrated parallel imaging methods provide greater robustness in the event of motion compared to techniques relying on accurate coil sensitivity maps. However, conventional internally calibrated data‐driven parallel imaging methods limit the effective acceleration possible for each blade. We present a method to share a single calibration dataset over all imaging blades on a slice by slice basis using the APPEAR non‐Cartesian parallel imaging method providing an effective blade width increase of 2.45×, enabling robust motion correction. Results comparing the proposed technique to conventional Cartesian and periodically rotated overlapping parallel lines with enhanced reconstruction methods demonstrate a significant improvement during subject motion and maintaining high image quality when no motion is present in normal and clinical volunteers. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

Simple baseline correction for 1H MRSI data of the prostate

Proton magnetic resonance spectroscopic imaging of the prostate can detect and localise tumour tissue in patients with prostate cancer. Pattern recognition methods have the potential to discriminate tumour from normal tissue using the spectral patterns of magnetic resonance spectroscopic imaging data thus providing a powerful tool for diagnosis and monitoring treatment of prostate cancer. Prostate magnetic resonance spectroscopic imaging data acquisition has been optimized for a flat baseline, including a long echo time and the use of water and fat suppression pulses. Despite this acquisition method, lipid resonances may still occur particularly at the margins of the prostate. Correcting the baseline by removing lipid artifacts is, therefore, a necessary processing step. We propose a simple baseline correction method for prostate magnetic resonance spectroscopic imaging through subtraction of a single simulated‐Lorentzian resonance. This method is shown to restore flat baselines to a test set of spectra and compares favorably with a state‐space modeling approach. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

Baseline Correction of Intraoperative Electromyography using Discrete Wavelet Transform

Objective

In intraoperative analysis of electromygraphic signals (EMG) for monitoring purposes, baseline artefacts frequently pose considerable problems. Since artefact sources in the operating room can only be reduced to a limited degree, signal-processing methods are needed to correct the registered data online without major changes to the relevant data itself. We describe a method for baseline correction based on “discrete wavelet transform” (DWT) and evaluate its performance compared to commonly used digital filters.

Methods

EMG data from 10 patients who underwent removal of acoustic neuromas were processed. Effectiveness, preservation of relevant EMG patterns and processing speed of a DWT based correction method was assessed and compared to a range of commonly used Butterworth, Resistor–Capacitor and Gaussian filters.

Results

Butterworth and DWT filters showed better performance regarding artefact correction and pattern preservation compared to Resistor–Capacitor and Gaussian filters. Assuming equal weighting of both characteristics, DWT outperformed the other methods: While Butterworth, Resistor–Capacitor and Gaussian provided good pattern preservation, the effectiveness was low and vice versa, while DWT baseline correction at level 6 performed well in both characteristics.

Conclusions

The DWT method allows reliable and efficient intraoperative baseline correction in real-time. It is superior to commonly used methods and may be crucial for intraoperative analysis of EMG data, for example for intraoperative assessment of facial nerve function.

     

直线加速器机载锥形束CT图像散射的修正方法

目的 对直线加速器机载锥形束CT(CBCT)散射修正方法进行研究.方法 在CBCT射线源前放置一个"指交叉"形的阻挡光栅,对Catphan 504模体进行扫描,分别获得CBCT图像和扇形束CT图像.利用基于阈值的图像分割算法跟踪机架旋转过程中阻挡光栅在CBCT图像中的位置,提取散射样本后利用插值法估计散射信号分布,采用改进的半扇扫描重建算法重建散射修正后的图像.结果 散射修正后的Catphan 504模体图像与扇形束CT重建的图像接近.与散射修正前比较,散射修正后CT值误差从100.86 HU下降到15.74 HU,散射修正后低对比度分辨力平均提高1.37倍.结论 基于阈值的图像分割算法准确跟踪阻挡光栅的位置,在铅片区域可采集散射信号,其余区域可通过改进的半扇扫描算法完成单次扫描的图像重建.     

沃尔比重评分修正及在医院财务绩效评价中的应用

沃尔比重评分法是财务绩效评价所应用的一种综合分析法。文章结合医院实际情况,在对沃尔比重评分法修正的基础上对医院财务综合绩效进行评价,旨在准确反映医院运营业绩,为管理者提供决策支持与参考。     

Feasibility and safety of on table extubation after corrective surgical repair of tetralogy of Fallot in a developing country: A case series

Fast-track extubation is an established safe practice in pediatric congenital heart disease (CHD) surgical patients. On table extubation (OTE) in acyanotic CHD surgical patients is well established with validated safety profile. This practice is not yet reported in tetralogy of Fallot (TOF) cardiac surgical repair patients in developing countries. Evidence suggests that TOF total correction patients should be extubated early, as positive pressure ventilation has a negative impact on right ventricular function and the overall increase in post-TOF repair complications such as low cardiac output state and arrhythmias. The objective of the case series was to determine the safety and feasibility of OTE in elective TOF total correction cardiac surgical patients with an integrated team approach. To the best of our knowledge, this is the first reported case series. A total of 8 elective male and female TOF patients were included. Standard anesthetic, surgical and perfusion techniques were used in these procedures. All patients were extubated in the operating room safely without any complications with the exception of one patient who continued to bleed for 3 h of postextubation at 2–3 ml/kg/h which was managed with transfusion of fresh frozen plasma at 15 mL/kg, packed red blood cells 10 mL/kg and bolus of transamine at 20 mg/kg. Apart from better surgical and bypass techniques, the most important factor leading to successful OTE was an excellent analgesia. On the basis of the case series, it is suggested to extubate selected TOF cardiac surgery repair patients on table safely with integrated multidisciplinary approach.     

PROPELLER MRI: clinical testing of a novel technique for quantification and compensation of head motion

While head motion is considered a significant problem in magnetic resonance imaging (MRI), there is no data to quantify its extent, severity, or effect on image quality. PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) MRI offers a novel means of quantifying and compensating for head motion. We performed axial T2-weighted PROPELLER (motion corrected: P-CR; uncorrected: P-UNCR) and conventional MRI (CONV), with equal scan times, in five normal volunteers and 35 clinical subjects. Volunteers were examined lying still and performing two separate head movements (shake "no" and nod "yes") to assess detection and compensation of in-plane motion by PROPELLER MRI. Images were examined by three radiologists for motion artifact and for overall image quality. Head rotation and translation was detected in all subjects during each slice acquisition, with expected changes occurring with volunteer head motion. Motion artifact was less commonly seen on PROPELLER than CONV MR (chi(2) test P < 0.001). PROPELLER was preferred over CONV in all subjects (P < 0.05) and P-CR was judged superior to P-UNCR (P = 0.02). Intracranial pathology was equally or better demonstrated with PROPELLER. PROPELLER MRI offers a means of quantifying head motion, reducing motion artifact, and improving image quality.     

无衰减校正对~(18)F-FDGPET全身肿瘤显像结果的影响

目的　探讨无衰减校正对18F 脱氧葡萄糖 (FDG)PET全身肿瘤显像定性和半定量分析结果的影响。方法　对 12例正常体检者和 5 2例肿瘤患者行18F FDGPET全身显像 ,分别用68Ge旋转棒源进行分割法衰减校正和无衰减校正图像重建。对PET图像进行定性和半定量分析。结果　经衰减校正图像的体内解剖结构比无衰减校正图像清晰 ,64例患者在经衰减校正图像上共检出 12 6个病灶 ,在无衰减校正图像上亦均检出。有无衰减校正显像的病灶与本底放射性计数比值 (L/B)差异无显著性 (t=1.89,P >0 .0 5 ) ,且两者明显相关 (r =0 .93)。结论　无衰减校正18F FDGPET肿瘤全身显像定性诊断价值与衰减校正显像近似 ,可计算L/B值 ,但病灶的解剖定位不如衰减校正显像     

Restoration of motion-related signal loss and line-shape deterioration of proton MR spectra using the residual water as intrinsic reference.

A postprocessing method to restore motion-related signal loss and line-shape deterioration in single-volume proton MR spectroscopy (MRS) is presented. Each acquisition is corrected by its phase offset and frequency shift, extracted from the residual water signal prior to averaging. Requirements are good gradient selection and selective suppression of CSF in residual water. Stimulated echo acquisition mode (STEAM) spectra (TE = 30 ms) were analyzed using the LCModel program to study gains in metabolite signal and spectral quality in five brain regions. Increases of total N-acetyl-aspartate concentrations of up to 5% were observed. The method may be beneficial for clinical examinations of less compliant subjects and for dynamic spectroscopy.     

Late results of nasal septum injury in children

In the period 1973-1982 241 children with nasal injuries were treated in ORL Clinics in Prague-Motol. The pathological septal findings were confirmed at the time by rhinoscopy in 98 cases (40%). In these cases, deviation, subluxation, or fracture were found 73 times, subperichondrial abscess 12 times, and hematoma 13 times. At the time of control examination 2-10 years after the injury, the unfavourable effects of the injury on the septum or the nasal passage were confirmed. Deviation of the septum was found in 55% of children; bad or insufficient rhinomanometric values in 62%. The septal deviation was associated with snoring in 52%, with colds in 56%, and in 37% with bronchitis and sinusitis. It was found necessary to carry out surgical correction of the nasal septum in several children of the 10-12 year age group; rhinotomy was not deemed necessary in any case.