Yildirim Erkan, Kirbas Ismail, Teksam Mehmet, Karadeli Elif, Gullu Hakan, Ozer Ismail
Baskent University Medical School, Department of Radiology, Ankara, Turkey.
Eur J Radiol. 2008 Jan;65(1):148-53. doi: 10.1016/j.ejrad.2007.03.007. Epub 2007 May 29.
The purpose of our study was to evaluate perfusion and diffusion of kidneys in renal artery stenosis (RAS) and any correlation between stenosis and ADC values and whether this imaging modality may be a noninvasive complementary assessment technique to MR angiography before interventional procedures.
Twenty consecutive patients suspected of having renal artery stenosis were evaluated with renal MR angiography to exclude stenosis and were then included in the study. Transverse DW multisection echo-planar MR imaging was performed. In the transverse ADC map, rectangular regions of interest were placed in the cortex on 3 parts (upper, middle, and lower poles) in each kidney. ADCs of the kidneys were calculated separately for the low, average, and high b-values to enable differentiation of the relative influence of the perfusion fraction and true diffusion. The ADC values of 39 kidneys (13 with renal artery stenosis and 26 normal renal arteries) were compared, and the relationship between stenosis degree and ADC values was calculated.
RAS was detected in 11 of 20 (55%) patients with MRA. Thirteen of 39 kidneys demonstrated RAS, and 26 were normal. The ADClow (1.9+/-0.2 versus 2.1+/-0.2; P=.020), ADCaverage (1.7+/-0.2 versus 1.9+/-0.1; P=.006), and ADChigh (1.8+/-0.2 versus 2.0+/-0.1; P=.012) values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries. Statistical analysis revealed that stenosis degree correlated strongly with ADClow (r=-.819; P=.001), ADCaverage (r=-.754; P=.003), and ADChigh (r=-.788; P=.001). The ADClow, ADCaverage, and ADChigh values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries.
We think that DW MR imaging of kidneys with RAS can help determine the functional status of a renal artery stenosis.
本研究的目的是评估肾动脉狭窄（RAS）患者肾脏的灌注和扩散情况，以及狭窄与表观扩散系数（ADC）值之间的相关性，探讨这种成像方式是否可作为介入治疗前磁共振血管造影（MRA）的一种非侵入性补充评估技术。
连续纳入20例疑似肾动脉狭窄的患者，先行肾脏MRA检查以排除狭窄，然后纳入本研究。进行横轴位扩散加权多层面回波平面磁共振成像。在横轴位ADC图上，于每个肾脏的皮质3个部位（上极、中极和下极）放置矩形感兴趣区。分别计算低、中、高b值时肾脏的ADC值，以区分灌注分数和真正扩散的相对影响。比较39个肾脏（13个肾动脉狭窄和26个肾动脉正常）的ADC值，并计算狭窄程度与ADC值之间的关系。
20例患者中11例（55%）经MRA检测出RAS。39个肾脏中13个显示RAS，26个正常。肾动脉狭窄患者肾脏的低b值ADC（1.9±0.2对2.1±0.2；P = 0.020）、中b值ADC（1.7±0.2对1.9±0.1；P = 0.006）和高b值ADC（1.8±0.2对2.0±0.1；P = 0.012）值显著低于肾动脉正常患者。统计分析显示狭窄程度与低b值ADC（r = -0.819；P = 0.001）、中b值ADC（r = -0.754；P = 0.003）和高b值ADC（r = -0.788；P = 0.001）密切相关。肾动脉狭窄患者肾脏的低、中、高b值ADC值显著低于肾动脉正常患者。
我们认为RAS患者肾脏的扩散加权磁共振成像有助于确定肾动脉狭窄的功能状态。
