Delgado Jorge, Bedoya Maria A, Adeb Melkamu, Carson Robert H, Johnson Ann M, Khrichenko Dmitry, Canning Douglas A, Darge Kassa
Department of Radiology, The Children's Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA, 19104, USA,
Pediatr Radiol. 2015 Aug;45(9):1333-43. doi: 10.1007/s00247-015-3324-x. Epub 2015 Mar 20.
Current protocols for functional MR urography (fMRU) require long scan times, limiting its widespread use.
Our goal was to use pre-defined criteria to reduce the number of sequences and thus the examination time without compromising the morphological and functional results.
The standard fMRU protocol in our department consists of eight sequences, including a 17-min dynamic post-contrast scan. Ninety-nine children and young adults (43 male, 56 female, mean age 7 years) were evaluated with this protocol. Each sequence was retrospectively analyzed for its utility and factors that affect its duration.
Mean scan time to perform the eight sequences, without including the variable time between sequences, was 40.5 min. Five sequences were categorized as essential: (1) sagittal T2 for planning the oblique coronal plane, (2) axial T2 with fat saturation for the assessment of corticomedullary differentiation and parenchymal thickness, (3) coronal 3-D T2 with fat saturation for multiplanar and 3-D reconstructions, (4) pre-contrast coronal T1 with fat saturation to ensure an appropriate scan prior to injecting the contrast material and (5) the coronal post-contrast dynamic series. Functional information was obtained after 8 min of dynamic imaging in the majority of children. The coronal fat-saturated T2, coronal T1, and post-contrast sagittal fat-saturated T1 sequences did not provide additional information. Because of the effects of pelvicalyceal dilation and ureteropelvic angle on the renal transit time, prone position is recommended, at least in children with high-grade pelvicalyceal dilation.
Comprehensive fMRU requires approximately 19 min for sequence acquisition. Allowing for time between sequences and motion correction, the total study time can be reduced to about 30 min. Four pre-contrast sequences and a shortened post-contrast dynamic scan, optimally with the child in prone position, are sufficient.
目前的磁共振尿路造影（fMRU）协议需要较长的扫描时间，限制了其广泛应用。
我们的目标是使用预定义标准减少序列数量，从而缩短检查时间，同时不影响形态学和功能结果。
我们科室的标准fMRU协议包括八个序列，其中包括一个17分钟的动态增强扫描。使用该协议对99名儿童和青年（43名男性，56名女性，平均年龄7岁）进行了评估。对每个序列进行回顾性分析，评估其效用以及影响其持续时间的因素。
执行这八个序列的平均扫描时间（不包括序列之间的可变时间）为40.5分钟。五个序列被归类为必需序列：（1）矢状位T2用于规划斜冠状面；（2）脂肪抑制轴位T2用于评估皮质髓质分化和实质厚度；（3）脂肪抑制冠状位三维T2用于多平面和三维重建；（4）脂肪抑制冠状位T1加权像用于在注射造影剂前确保合适的扫描；（5）冠状位增强后动态序列。大多数儿童在动态成像8分钟后即可获得功能信息。冠状位脂肪抑制T2、冠状位T1以及增强后矢状位脂肪抑制T1序列未提供额外信息。由于肾盂肾盏扩张和肾盂输尿管夹角对肾脏转运时间的影响，建议采用俯卧位，至少对于重度肾盂肾盏扩张的儿童应如此。
完整的fMRU序列采集大约需要19分钟。考虑到序列之间的时间和运动校正，总研究时间可减少至约30分钟。四个增强前序列和缩短的增强后动态扫描，最佳状态是儿童处于俯卧位，就足够了。
