Marchiafava-Bignami disease: CT and MR findings

We describe characteristic findings in a patient with Marchiafava-Bignami disease who was serially imaged with CT and MR. Involvement of the entire corpus callosum was visualized with both types of imaging. Following administration of gadolinium-DTPA, the lesion was clearly enhanced in the subacute stage. Correspondence to: S. Otake     

Non-Cartesian data reconstruction using GRAPPA operator gridding (GROG).

A novel approach that uses the concepts of parallel imaging to grid data sampled along a non-Cartesian trajectory using GRAPPA operator gridding (GROG) is described. GROG shifts any acquired data point to its nearest Cartesian location, thereby converting non-Cartesian to Cartesian data. Unlike other parallel imaging methods, GROG synthesizes the net weight for a shift in any direction from a single basis set of weights along the logical k-space directions. Given the vastly reduced size of the basis set, GROG calibration and reconstruction requires fewer operations and less calibration data than other parallel imaging methods for gridding. Instead of calculating and applying a density compensation function (DCF), GROG requires only local averaging, as the reconstructed points fall upon the Cartesian grid. Simulations are performed to demonstrate that the root mean square error (RMSE) values of images gridded with GROG are similar to those for images gridded using the gold-standard convolution gridding. Finally, GROG is compared to the convolution gridding technique using data sampled along radial, spiral, rosette, and BLADE (a.k.a. periodically rotated overlapping parallel lines with enhanced reconstruction [PROPELLER]) trajectories.     

通过MR扩散张量成像了解与年龄相关的豆状核变化

目的探讨MR扩散张量成像（DTI）观察豆状核年龄相关性变化的价值与意义。方法69名健康志愿者纳入本研究。入组对象按年龄分为3组：≤30岁（I）组，22例；31～50岁（Ⅱ）组，24例；〉50岁（Ⅲ）组，23例。利用DTI分别测量受试者大脑左右两侧壳核、苍白球的表观扩散系数（ADC）值、部分各向异性（FA）值及扩散张量特征值λ1、λ2、λ3。分析不同年龄组间ADC、FA、λ1、λ2、λ3值的差异及与年龄的相关性。结果I、Ⅱ、Ⅲ组的壳核ADC值分别为：（6．68±0．40）×10^-4、（6．47±0．36）×10^-4、（6．44±0．34）×10^-4mm^2／s，苍白球ADC值分别为：（6．13±0．50）×10^-4、（6．05±0．33）×10^-4、（6．05±0．52）×10$-4mm^2／s。I、Ⅱ、Ⅲ组的壳核FA值分别为：0．20±0．03、0．23±0．03、0．25±0．03，苍白球FA值分别为：0.35±0．03、0．36±0．03、0．37±0．04。各年龄组内壳核ADC值大于苍白球，而FA值小于苍白球。壳核FA值的组问差异有统计学意义（F=10．082，P=0.000），壳核I、Ⅱ、Ⅲ组入，值分别为（5．35±0．45）×10^-4、（5．04±0．46）×10^-4、（4．90±0．44）×10^-4mm^2／s，差异亦有统计学意义（F=5．675，P=0．005）；壳核FA值与年龄呈正相关（r=0．555，P〈0．01），λ3值与年龄呈负相关（r=-0.440，P〈0．01）。结论壳核FA值随年龄的增长而上升，λ3值随年龄的增长而下降。     

Spontaneous regression of optic pathways gliomas in three patients with neurofibromatosis type I and critical review of the literature

Case reports The authors report their experience about three children (two girls, one boy; average age 1.6 years) with a spontaneous regression of optic gliomas. All of them had a previous diagnosis of neurofibromatosis type 1 (NF 1). None of them underwent surgery or biopsy nor received chemotherapy or radiotherapy. The complete regression was documented by MRI scans performed during a mean follow-up of 6.3 years.Literature review Moreover, the authors analyze the features of the 16 cases previously reported in English literature of spontaneously regressed optic gliomas with an overview of the different therapeutic strategies. The knowledge that this kind of tumor, particularly in young patients, may regress is important in the decision of the best therapeutic approach.     

肝腺瘤的影像学诊断

目的探讨影像学(US、CT、MRI及DSA)诊断肝腺瘤的价值。方法回顾性分析经手术、病理证实的11例肝腺瘤的影像学表现,其中11例行US和CT检查(有1例行CT灌注成像,CTP),5例行MRI扫描,4例行DSA检查,并与手术病理所见对照。结果11例肝腺瘤均为单发肿块,无肝硬化背景,直径2.0～10.0cm。影像学表现:US检查,10例呈稍低或不均匀稍强回声,边界清晰,6例见低回声晕,彩色多普勒显示肿块内有较丰富的血流;CT检查,10例为稍低或等密度,8/10例动脉期全瘤明显强化,门脉期轻度强化,延迟期呈等密度,1例平扫和延迟期呈等密度,动脉期中度强化,门脉期轻度强化,误诊为血管瘤。1/11例CT灌注成像(CTP)检查,肝动脉灌注量(HAP)=1.08ml/(min.ml),门静脉灌注量(PVP)=0.19ml/(min.ml),肝动脉灌注指数(HPI)=0.85,各参数值与肝癌均有明显不同;MRI检查,5例肝腺瘤均能显示完整包膜,T1WI上2例稍高于肝脏信号,1例呈等信号,2例为稍低信号,T2WI上5例均表现为以稍高信号为主的混杂信号,脂肪抑制像(STIR)1例呈略低信号,4例信号与T2WI相似,行增强扫描的4例病灶动脉期显著强化,门脉期强化减退,平衡期呈等信号。DSA检查,3/4例病灶见粗细不均的异常血管影,实质期可见肿瘤染色表现。结论肝腺瘤的US和DSA表现均缺乏特异性,CT、MRI则具有一定的特点。CTP对肝腺瘤可能具有诊断和鉴别诊断价值。     

Array compression for MRI with large coil arrays.

Arrays with large numbers of independent coil elements are becoming increasingly available as they provide increased signal-to-noise ratios (SNRs) and improved parallel imaging performance. Processing of data from a large set of independent receive channels is, however, associated with an increased memory and computational load in reconstruction. This work addresses this problem by introducing coil array compression. The method allows one to reduce the number of datasets from independent channels by combining all or partial sets in the time domain prior to image reconstruction. It is demonstrated that array compression can be very effective depending on the size of the region of interest (ROI). Based on 2D in vivo data obtained with a 32-element phased-array coil in the heart, it is shown that the number of channels can be compressed to as few as four with only 0.3% SNR loss in an ROI encompassing the heart. With twofold parallel imaging, only a 2% loss in SNR occurred using the same compression factor.     

Hip Arthroscopy: Surgical Indications

Successful outcomes of hip arthroscopy are most clearly dependent on selecting appropriate patients. The indications are numerous and continue to evolve. These indications are summarized in this report. The anatomic architecture of the hip region imposes unique challenges to performing this procedure. As a surgeon’s experience evolves, so will his or her indications for this operation. It is imperative to be knowledgeable about the technique, to exercise care with the procedure, and to be certain that it is being performed for proper reasons.