18F-FDG PET/CT在继发性肾淋巴瘤与肾脏免疫性疾病鉴别诊断中的价值

目的 探讨18F-氟脱氧葡萄糖（FDG ）PET/CT对继发性肾淋巴瘤（SRL）的诊断价值，并与肾脏免疫性疾病（RID）进行鉴别分析。 方法 回顾性分析2017年12月至2020年12月于天津市第一中心医院行18F-FDG PET/CT检查并经组织病理学检查证实或临床综合诊断确诊的12例SRL患者的临床和影像学资料，其中男性7例、女性5例，年龄（50±15）岁，设为SRL组。同时选取18F-FDG PET/CT显像阳性、最终诊断为RID的患者10例，其中IgG4相关性肾病2例、肾抗中性粒细胞胞浆抗体相关性血管炎8例；男性5例、女性5例，年龄（60±10）岁，设为RID组。选取18F-FDG PET/CT显像肾脏正常的健康受检者10例，其中男性5名、女性5名，年龄（55±10）岁，设为正常对照组。观察和记录肾脏以及肾外组织受累的18F-FDG PET/CT影像学表现，测量并计算肾脏病变或肾皮质最大标准化摄取值（SUV_max）、肾脏病变或肾皮质SUV_max与肝脏平均标准化摄取值（SUV_mean）的比值（SUV _ratio）及肾外受累组织SUV_max。3组受检者SUV_max、SUV_ratio的比较采用单因素方差分析，SRL组与RID组肾外受累病变18F-FDG摄取SUV_max的比较采用独立样本t检验。 结果 12例SRL患者中，受累肾脏18F-FDG PET/CT显像表现为双侧肾脏多发结节与肿物型6例，肾脏弥漫性肿胀型6例，病变摄取18F-FDG均异常增高。10例RID患者中，受累肾脏18F-FDG PET/CT显像均表现为双肾弥漫性肿胀型，肾实质弥漫性18F-FDG摄取增高，与肾脏弥漫性肿胀型SRL表现相似。在肾外受累病变方面，RID组多有常见好发的累及部位，SRL组多伴全身不同组织脏器的受累，分布无规律性。SRL组患者肾脏病变的SUV_max、SUV_ratio显著高于RID组（21.88±12.04对9.09±3.51、11.38±6.52对3.67±1.12），2组肾脏病变的SUV_max、SUV_ratio亦均显著高于正常对照组（SUV_max=3.23±0.39、SUV _ratio=1.47±0.25），且差异均有统计学意义（F=17.189、18.361，均P<0.001）。SRL组肾外受累病变的SUV_max明显高于RID组（27.67±15.09对7.55±3.70），且差异有统计学意义（t=?3.889，P=0.001）。 结论 18F-FDG PET/CT对SRL的诊断和全身受累范围的评估有较好的临床应用价值，且有助于与RID的鉴别。

Value of 18F-FDG PET/CT in the differentiation of secondary renal lymphoma and renal immune disease

Objective To evaluate the diagnostic value of 18F-fluorodeoxyglucose (FDG) PET/CT imaging in patients with secondary renal lymphoma (SRL) and its differential analysis with renal immune disease (RID). Methods The 18F-FDG PET/CT images and clinical characteristics of 12 patients with SRL confirmed by histopathological examination or clinical comprehensive diagnosis in Tianjin First Central Hospital from December 2017 to December 2020 were analyzed retrospectively. The patients in the SRL group comprised 7 males and 5 females, aged 50±15 years. At the same time, 10 patients with positive 18F-FDG PET/CT imaging and final diagnosis of RID were selected, including 2 cases of IgG4-related kidney disease and 8 cases of antineutrophil cytoplasmic antibody-associated vasculitis. These 5 males and 5 females, aged 60±10 years, comprised the RID group. Ten healthy subjects with normal kidneys by 18F-FDG PET/CT imaging were selected as the healthy control group (5 males and 5 females, aged 55±10 years). The 18F-FDG PET/CT features of renal and extrarenal invasion were observed and recorded. The maximal standardized uptake value (SUV_max) of renal lesion or renal cortex, the ratio of SUV_max in renal lesion or renal cortex to mean standardized uptake value (SUV_mean) of liver, and SUV_max of extrarenal invasions were measured and calculated. One-way ANOVA was used to compare SUV_max and ratio of standardized uptake value (SUV_ratio) among the three groups, and independent sample t test was used to compare SUV_max of extrarenal 18F-FDG uptake in the SRL group and RID group. Results The 12 patients with SRL exhibited multifocal masses (n=6) and diffuse nephromegaly (n=6) in bilater kidneys with abnormally increased 18F-FDG uptake. In 10 patients with RID, the 18F-FDG PET/CT imaging of the affected kidneys showed bilateral diffuse nephromegaly with increased 18F-FDG uptake of renal parenchyma, which was similar to diffuse nephromegaly in SRL. However, in terms of extrarenal involvement, the patients in the RID group had common sites of involvement, and the patients in the SRL group were mostly associated with the involvement of different tissues and organs of the whole body, with irregular distribution. Statistical analysis showed that SUV_max and SUV_ratio of renal lesions in the SRL group were significantly higher than those in the RID group (21.88±12.04 vs. 9.09±3.51 and 11.38±6.52 vs. 3.67±1.12, respectively), and SUV_max and SUV_ratio of renal lesions in the two groups were significantly higher than those in the healthy control group (SUV_max=3.23±0.39, SUV_ratio=1.47±0.25; F=17.189, 18.361; both P<0.001). 18F-FDG SUV_max of extrarenal lesions in the SRL group was significantly higher than that in the RID group (27.67±15.09 vs. 7.55±3.70, t=?3.889, P=0.001). Conclusion 18F-FDG PET/CT has a good clinical value in the diagnosis of SRL and the evaluation of systemic involvement, and it is helpful in distinguishing SRL from RID.