血氧水平依赖磁共振成像评估食盐摄入变化诱导的肾脏血氧水平改变

Evaluation of salt intake alteration-induced variation in renal blood oxygen level with blood oxygenation level-dependent magnetic resonance imaging

目的利用血氧水平依赖磁共振成像(BOLD-MRI)评估食盐摄入变化对肾脏氧合水平的影响。方法招募中国人民武装警察部队后勤学院附属医院健康志愿者9名,进行正常膳食期(基线期)3d、高盐膳食期(高盐期,15g/d氯化钠)7d和低盐膳食期(低盐期,5g/d氯化钠)7d的干预试验,分别测量血压和心率,收集24h尿液,检测血和尿液电解质的变化,同时进行肾脏BOLD-MRI评估,比较肾脏皮质及髓质的表观-自旋弛豫率(R*2)。结果与基线期比较,高盐期第7天24h尿量、尿Na+、尿K+和肾脏髓质R*2值[(32.6±4.3)/s比(24.4±3.3)/s]明显升高;与高盐期第7天比较,低盐期第7天24h尿量、尿Na+、尿K+和肾脏髓质的R*2值[(25.0±3.1)/s比(32.6±4.3)/s,均P<0.05]降低;3个时期的肾脏皮质R*2值比较,差异均无统计学意义。结论食盐摄入变化能够引起肾脏氧合水平改变;BOLD-MRI是评估食盐摄入变化诱导肾脏氧合水平改变的一种无创、敏感的检查方法。

Objective To evaluate the effects of salt intake variation on renal oxygenation level by blood oxygenation level- dependent magnetic resonance imaging （BOLD-MRI）. Methods A dietary intervention experiment was performed in 9 healthy volunteers from Affiliated Hospital of Logistics University of Chinese People＇s Armed Police Forces, beginning with a 3-day normal diet followed by a 7-day high-salt diet （15 g/d NaCI） and a 7-day low-salt diet （5 g/d NaCI）. Blood pres- sure （BP） and heart rate were measured, and 24-h urine was collected for measurements of blood and urinary electrolytes. All volunteers underwent dynamic BOLD-MRI of the kidney to determine the apparent relaxation rates （R2 ·） of renal cortex and medulla. Results Compared with those in the baseline period, the 24-h urine volume, urine Na＋ , urine K＋ , and renal medullary R2 · values [（32.6±4. 3）/s vs （24. 4±3.3）/s, P〈0. 05] on the 7th day in high-salt diet were significant- ly higher. Compared with those on the 7th day in high-salt diet, the 24-h urine volume, urine Na＋ , urine K＋ , and renal medullary R2 · values [（25.0±3.1）/s vs （32.6 ± 4. 3）/s, P^0. 05] on the 7th day in the low-salt diet were signifieantly lower. There was no significant difference in R2 · values of renal cortex at the three stages. CondusiOlm Variation in salt intake eould lead to corresponding changes in renal oxygenation level, and BOLD-MRI offers a non-invasive and sensitive method for the assessment of salt intake alteration-induced variation in renal oxygenation levels.