磁共振扩散加权成像提示小儿脊柱的脑脊液转移瘤

骨科医师之家  2013年8月30日  阅读数:2361  字体:    

Drop metastases to the pediatric spine revealed with diffusion-weighted MR imaging

磁共振扩散加权成像提示小儿脊柱的脑脊液转移瘤

Abstract

摘要

Identifying drop metastases to the spine from pediatric brain tumors is crucial to treatment and prognosis.MRI is currently the gold standard for identifying drop metastases, more sensitive than CSF cytology, but imaging is not uncommonly inconclusive. Although diffusion-weighted imaging (DWI) of the brain is very useful in the evaluation of hypercellular tumors, DWI of the spine has not been clinically useful in children because of susceptibility artifacts and lack of spatial resolution. A new technique, readout-segmented echo planar imaging (EPI),has improved these images, allowing for identification ofhypercellular drop metastases. We report a case thatillustrates the utility of spine DWI in the detection ofmetastatic disease in children with primary central nervoussystem (CNS) tumors. This case suggests that DWI of thespine with readout-segmented EPI should be included in theevaluation for drop metastases.

识别由患儿脑瘤下移到脊柱的脑脊液转移瘤,对于治疗和预后至关重要。MRI是当前识别脑脊液转移瘤的黄金标准,它比脑脊液(CSF)的细胞学检查更敏感,但是影像是极具决定性的。尽管在评价增殖型肿瘤方面,大脑的弥散加权成像(DWI)非常有价值,但是脊柱的DWI在临床上不用于儿童,因为磁敏感性伪影和空间分辨率不足。((尽管大脑弥散加权成像(DWI)对于增生型肿瘤的评价非常有帮助,,但儿童脊柱的DWI还是没有临床价值的。因为脊柱内存在磁敏感性伪影,而且影像的空间分辨率不足。)一种新技术,读出分段回波平面成像(EPI),改善了这些图片,允许识别细胞过多的脑脊液转移瘤(使得增生性脑脊液转移瘤的识别成为可能)。我们报告的一个案例说明了脊柱DWI在儿童原发性中枢神经系统(CNS)肿瘤方面转移性疾病的检测上的效用。(儿童原发性中枢神经系统(CNS)肿瘤可能会发生转移,我们报道的病例阐明了脊柱DWI对于转移肿瘤的监测作用。)该案例表明脑脊液转移瘤的评价应包含脊柱DWIEPI分段读数。

Introduction

简介

Diffusion-weighted imaging (DWI) of the spine revealsdrop metastases (that might not be visible on conventionalsequences in children with hypercellular brain tumors). Wereport a case that illustrates the utility of spine DWI in thedetection of CSF-disseminated metastases in children withprimary central nervous system (CNS) tumors.

脊柱弥散加权成像(DWI)能显示一些脑脊液转移瘤,对于患有增生性肿瘤的儿童,这些转移瘤可能在常规序列上不可见。

 

Case report

病例报告

IRB approval was obtained for this report. A 2-year-old girlwith an atypical teratoid rhabdoid tumor (ATRT) of theposterior fossa presented for a routine follow-up MRI scanof the brain and spine. At the time of diagnosis, her primarytumor demonstrated restricted diffusion on MR andheterogeneous enhancement with gadolinium. She had noevidence of drop metastases to the spine. Subsequently, sheunderwent gross total resection, and was treated withintrathecal and intravenous chemotherapy in addition toposterior fossa radiation. She was negative for residualdisease for 16 months. She was off treatment for 3 monthsand asymptomatic with negative CSF cytology at the timeof the follow-up study. Her MRI scan, performed on a 1.5-TAvanto system (Siemens Medical Systems, Erlangen,Germany), revealed a single nodular focus of restricteddiffusion along the dorsal aspect of the spinal cord in the mid-thoracic region (Fig. 1). There was no correspondingsignal abnormality or abnormal enhancement at thislocation. Because of the diffusion abnormality, a conservative approach of short-interval follow-up imaging in 8 weekswas taken. The next MRI scan of the spine performedon the same scanner revealed an interval increase insize of the previously visualized nodular diffusionabnormality and new, extensive drop metastases, bestvisualized on the DWI sequences. Many of the dropmetastases were now apparent on the conventional T2-W and post-contrast T1-W sequences (Figs. 2 and 3).Her brain MRI remained negative without evidence forrecurrent intracranial tumor.

该报告已获得IRB批准。一个后颅窝有非典型畸胎横纹肌样瘤(ATRT)的2岁小女孩接受了一项常规随访:核磁共振扫描大脑和脊柱。诊断时,磁共振成像表明其原发性肿瘤扩散受限,钆造影后显示有不均匀强化。无迹象表明她脊柱中存在脑脊液转移瘤。(随后,对其实施了完全切除手术,术后对后颅窝进行放线治疗,并对鞘内和静脉进行化疗。16个月内,她体内残余癌症检测为阴性。随访研究期间,她停止了三个月的,阴性CSF细胞学检查无症状。用1.5-T扫描仪系统(德国埃尔兰根西门子医疗系统)进行核磁共振扫描,图像显示沿着胸椎中部的脊髓背侧,存在限制扩散的单个结节灶(图1)。在这个位置没有相应的信号异常或异常增强。由于扩散异常,我们采取了“8周内进行短间期的影像学随访”的保守方法。接下来在同样的扫描仪上进行的脊柱MRI扫描上显示,先前的可见结节性扩散异常面积周期性增加,而且在DWI序列上能清楚地看到新而且广泛存在的脑脊液转移瘤。现在,在常规T2-W和增强后的T1-W序列上明显可以看到很多脑脊液转移瘤(图23)。而她的脑部MRI仍然显示为阴性,无复发性颅内肿瘤的迹象。

Fig. 1Initial scan. Sagittal T1-W post-contrast (a), ADC map (b),isotropic DWI (c) and T2-W (d) images and axial T1-W post-contrastimage at the level of interest (e) demonstrate the lack of any abnormalsignal or enhancement at the location of the nodular diffusionabnormality at the dorsal aspect of the thoracic cord (arrows in band c)

1.初始扫描。矢状T1-W 增强后影响(a),ADC图(b),各向同性的DWIc)、T2-Wd图像和在感兴趣节段的轴向T1-W强反差影像(e)证明胸线背侧的结节状扩散异常位点缺乏任何异常信号或异常增强(bc上的箭头)。

 

 

Fig. 2Follow-up scan 2 months later. Sagittal T1-W post-contrast(a), ADC map (b), isotropic DWI (c) and T2-W (d) images and axialT1-W post-contrast image at the level of interest (e) demonstrateinterval increase in the size of the previously visualized nodulardiffusion abnormality (upper arrows in b and c), now also seen on theT2-W image (arrow in d). Another nodular diffusion abnormalityalong the ventral aspect of the lower thoracic cord is now clearlyvisible (lower arrows in b and c). Note the continued lack ofconspicuity on the T1-W post-contrast images (a and e)

2. 2个月后的后续扫描。矢状T1-W 增强后影响(a),ADC图(b),各向同性的DWIc)、T2-Wd)图像和在感兴趣节段的轴向T1-W强反差影像(e证明先前可见的结节状扩散异常面积(bc中的上方箭头)周期性增加,现在在T2-W图像(d中的箭头)中也可见。另一个沿腹侧方下胸线的结节状扩散异常现在也清晰可见(bc中的下方箭头)。注意这些扩散异常在T1-W反差增强后图像中仍不清晰(ae)。

 

Fig. 3Images of the thoracolumbar spine from initial scan (a–d) andfollow-up scan 2 months later (e–h). Initially negative T1-W post-contrast (a) and T2-W (b) images with possible tiny, nodular diffusionabnormality along the distal cauda equina on isotropic DWI (c) andADC map (d). Follow-up T1-W post-contrast image demonstratesenhancement within the distal thecal sac (arrow in e); T2-W imagedemonstrates nodularity along the cauda equina and within the distal

thecal sac (arrows in f); isotropic DWI and ADC map demonstratenodular and clumpy areas of restricted diffusion (arrows in g and h),consistent with drop metastases

3.来自最初扫描(a-d)和2个月后的后续扫描(e-h)的胸腰椎脊柱图像。最初,阴性T1-W增强后(a)以及T2-Wb)图像底片可能有细微不同,各向同性的DWIc)和ADC图(d)中结节性扩散异常沿着远端马尾发生。后续的T1-W增强后图像显示了在远端囊壁(e中箭头)的强化;T2-W图像显示了在远端囊壁内沿着马尾的结节状态;各向同性的DWIADC图显示限制扩散的结节状和块状区域(gh中箭头所指),符合脑脊液转移瘤。

 

References

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