Haneder Stefan, Budjan Johannes Michael, Schoenberg Stefan Oswald, Konstandin Simon, Schad Lothar Rudi, Hofheinz Ralf Dieter, Gramlich Veronika, Wenz Frederik, Lohr Frank, Boda-Heggemann Judit
Institute of Clinical Radiology and Nuclear Medicine, University Medical Centre Mannheim, University of Heidelberg, Mannheim, Germany.
Strahlenther Onkol. 2015 Apr;191(4):356-64. doi: 10.1007/s00066-014-0787-x. Epub 2014 Dec 2.
Combined radiochemotherapy (RCT) for gastric cancer with three-dimensional conformal radiotherapy (3D-CRT) results in ablative doses to the upper left kidney, while image-guided intensity-modulated radiotherapy (IG-IMRT) allows kidney sparing despite improved target coverage. Renal function in long-term gastric cancer survivors was evaluated with 3T functional magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) and (23)Na imaging.
Five healthy volunteers and 13 patients after radiotherapy were included: 11×IG-IMRT; 1×3D-CRT; 1× "positive control" with stereotactic body radiotherapy (SBRT) of a metastasis between the spleen/left kidney. Radiation doses were documented for the upper/middle/lower kidney subvolumes. Late toxicity was evaluated based on CTC criteria, questionnaire, and creatinine values. Morphological sequences, DWI images, and (23)Na images were acquired using a (1)H/(23)Na-tuned body-coil before/after intravenous water load (WL). Statistics for [(23)Na] (concentration) and apparent diffusion coefficient (ADC) values were calculated for upper/middle/lower renal subvolumes. Corticomedullary [(23)Na] gradients and [(23)Na] differences after WL were determined.
No major morphological alteration was detected in any patient. Minor scars were observed in the cranial subvolume of the left kidney of the 3D-CRT and the whole kidney of the control SBRT patient. All participants presented a corticomedullary [(23)Na] gradient. After WL, a significant physiological [(23)Na] gradient decrease (p < 0.001) was observed in all HV and IG-IMRT patients. In the cranial left kidney of the 3D-CRT patient and the positive control SBRT patient, the decrease was nonsignificant (p = 0.01, p = 0.02). ADC values were altered nonsignificantly in all renal subvolumes (all participants). Renal subvolumes with doses ≥ 35 Gy showed a reduced change of the [(23)Na] gradient after WL (p = 0.043). No participants showed clinical renal impairment.
Functional parameters of renal (23)Na MRI after gastric IG-IMRT are identical to those of healthy volunteers, in contrast to renal subvolumes after ablative doses in the control and 3D-CRT patient. While kidney doses to the cortex below 20-25 Gy in fractional doses of ~ 1 Gy in IG-IMRT (combined with intensified chemotherapy) do not seem to cause significant MRI morphological or functional alterations, doses of > 35 Gy in 1.5-2 Gy fractions clearly result in impairment.
采用三维适形放疗（3D-CRT）的胃癌联合放化疗（RCT）会使左上肾受到消融剂量照射，而图像引导调强放疗（IG-IMRT）尽管靶区覆盖有所改善，但仍能实现肾脏保护。采用3T功能磁共振成像（MRI），包括扩散加权成像（DWI）和（23）Na成像，对长期胃癌幸存者的肾功能进行评估。
纳入5名健康志愿者和13名放疗后患者：11例行IG-IMRT；1例行3D-CRT；1例行“阳性对照”，即对脾/左肾之间的转移灶进行立体定向体部放疗（SBRT）。记录上/中/下肾亚体积的辐射剂量。根据常见不良反应事件评价标准（CTC）、问卷和肌酐值评估晚期毒性。在静脉注射水负荷（WL）前后，使用（1）H/（23）Na调谐体线圈采集形态学序列、DWI图像和（23）Na图像。计算上/中/下肾亚体积的[（23）Na]（浓度）和表观扩散系数（ADC）值的统计数据。测定WL后的皮质髓质[（23）Na]梯度和[（23）Na]差异。
未在任何患者中检测到主要形态学改变。在3D-CRT患者左肾的颅侧亚体积和对照SBRT患者的整个肾脏中观察到轻微瘢痕。所有参与者均呈现皮质髓质[（23）Na]梯度。WL后，在所有健康志愿者和IG-IMRT患者中均观察到显著的生理性[（23）Na]梯度降低（p < 0.001）。在3D-CRT患者的左肾颅侧和阳性对照SBRT患者中，降低不显著（p = 0.01，p = 0.02）。所有肾亚体积（所有参与者）的ADC值均无显著改变。剂量≥35 Gy的肾亚体积在WL后[（23）Na]梯度变化减小（p = 0.043）。没有参与者出现临床肾功能损害。
与对照和3D-CRT患者接受消融剂量后的肾亚体积相比，胃癌IG-IMRT后肾脏（23）Na MRI的功能参数与健康志愿者相同。在IG-IMRT（联合强化化疗）中，分次剂量约1 Gy时，低于20 - 25 Gy的肾皮质剂量似乎不会引起显著的MRI形态学或功能改变，而1.5 - 2 Gy分次剂量>35 Gy则明显导致损害。
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