-
异位肾是肾脏定位出现异常,可异位于骨盆、髂窝、腹部、胸腔或双肾交叉异位。异位肾常伴肾旋转不良及其他畸形,如尿道下裂、隐睾等,但合并肛门闭锁较罕见。部分异位肾形态不规则,在临床上易被误认为是肿瘤而被切除,从而给患者造成伤害。肾动态显像不但可以反映肾血流灌注情况、上尿路引流排泄情况,还可以采用Gate′s法测定总肾及分肾肾小球滤过率(glomerular filtration rate,GFR),结合SPECT/CT融合显像,可以从解剖结构及功能方面对异位肾进行多方面地诊断及鉴别诊断。Gate′s法测定GFR的影响因素较多,如肾脏深度,但通过矫正,不管是从后位还是从前位进行矫正,都获得了较满意的GFR。笔者报道了先天性肛门闭锁患者成年后体检偶然发现异位肾,并通过查阅文献,对Gate′s法进行了较深入的分析学习。
-
患者男性,19岁,身高175 cm,体重63 kg,出生时肛门闭锁,出生后第3天在山西省儿童医院行肛门成形术。2016年9月17日因碰撞后出现左侧睾丸肿胀、触痛,于当地医院就诊,检查发现尿蛋白“++”,血肌酐、血尿酸水平稍高(具体数值不详)。2016年10月13日在我院复查,尿蛋白“++”、血肌酐水平为98.8 μmol/L(参考范围49.0~90.0 μmol/L)、血尿酸水平为446 μmol/L(参考范围210~440 μmol/L),泌尿系超声检查结果显示双肾区未探及肾脏轮廓,左下腹腹腔内可见一肾脏回声,大小约10.2 cm×5.1 cm,被膜光整,皮质回声均匀,肾窦居中未见分离,双侧输尿管未见扩张。提示:左下腹异位肾可能。
为进一步评估肾功能,2016年10月20日在我院行99Tcm-DTPA肾动态显像(采用德国西门子公司生产的Symbia T16型双探头SPECT/CT,配低能高分辨率平行孔准直器,能峰140 keV,窗宽±20%;99Tcm-DTPA由北京欣科思达医药科技有限公司提供),并采用双血浆法测定GFR。肾动态显像结果(后位图像):血流灌注相示正常双肾区未见血流灌注影,左下腹可见一较大团块状显像剂分布异常浓聚影;功能相(图 1中A)示双肾区未见双肾影,左下腹可见一具有肾脏功能组织的巨大显像剂分布异常增高影,考虑为腹腔内异位肾脏组织,双侧输尿管隐约显影。双血浆法GFR与Gate′s法GFR矫正前(后位图像勾画ROI,肾脏深度采用Tonnesen公式[1]计算)统一采用Gehan和George推导的体表面积公式[2]进行标化。最终结果:Gate′s法GFR矫正前为14.4 mL·min-1·1.73 m-2;双血浆法GFR为66.0 mL·min-1·1.73 m-2。
重新处理了前位图像(图 1中B)后发现肾脏轮廓在前位图像上明显比在后位图像上清晰,考虑异位肾位置靠前,明显偏离了肾脏的正常位置,根据Gate′s法的原理,需要对肾脏深度进行矫正。
若仅对肾脏深度进行矫正,只行CT扫描即可,但为了更好地观察异位肾的肾盂、输尿管集合及排泄情况,笔者做了SPECT/CT局部断层融合显像。经患者及家属知情同意,患者于常规肾动态显像检查的次日静脉注射179.5 MBq 99Tcm-DTPA,5 min后行SPECT/CT局部断层融合显像,结果(图 1中C、D)显示:双肾区未见肾组织,第3至5腰椎左前方可见单一肾影,大小约为8.8 cm×5.4 cm×9.6 cm(左右径×前后径×上下径),边界清楚,呈分叶状,其内可见显像剂分布弥漫性增高,并于左右两分叶内可见显像剂局灶性浓聚影,左侧明显,两者下极可见条状显像剂摄取影。考虑腹腔交叉融合异位肾,含有两个肾盂及两条输尿管,左肾体积基本正常,右肾体积缩小,发育不全。
根据CT断层图像,采用异位肾的最大横断面(图 1中E)测量了肾脏的后位深度H后(肾脏的中心到后背体表皮肤的垂直距离)和前位深度H前(肾脏的中心到腹部体表皮肤的垂直距离)。依据Gate′s法基本原理测得GFR前(处理前位图像且以肾脏的前位深度进行校正后获得的GFR)和GFR后(处理后位图像且以肾脏的后位深度进行校正后获得的GFR)。结果如下。
前位矫正:
$ \begin{array}{l} {{\rm{H}}_{前}} = \left( {{\rm{a + b}}} \right)/2 = 4.95\;{\rm{cm, }}\\ {\rm{GF}}{{\rm{R}}_{前}} = 60.6\;{\rm{mL}} \cdot {\min ^{ - 1}} \cdot 1.73\;{{\rm{m}}^{ - 2}}; \end{array} $ 后位矫正:
$ \begin{array}{l} {{\rm{H}}_{后}} = \left( {{\rm{c + d}}} \right)/2 = 12.36\;{\rm{cm, }}\\ {\rm{GF}}{{\rm{R}}_{后}} = 59.6\;{\rm{mL}} \cdot {\min ^{ - 1}} \cdot 1.73\;{{\rm{m}}^{ - 2}} \end{array} $ 其中,a为肾脏的前缘到腹部体表皮肤的垂直距离,b为肾脏的后缘到腹部体表皮肤的垂直距离,c为肾脏的前缘到背部体表皮肤的垂直距离,d为肾脏的后缘到背部体表皮肤的垂直距离。肾脏深度经过矫正后,前位、后位测得的GFR数值非常接近,并与目前国际公认的“金标准”双血浆法[3]测得的GFR数值差别不大,误差在可接受范围内[4]。本例患者最后诊断为腹腔交叉融合异位肾,肾功能轻度受损。
先天性肛门闭锁异位肾SPECT/CT显像一例
Ectopic kidney SPECT/CT imaging in a patient with congenital anal atresia
-
摘要: 笔者报道了先天性肛门闭锁异位肾SPECT/CT显像一例。异位肾患者由于早期缺乏特异性的临床症状,大多数患者都是体检时偶然发现。目前诊断异位肾主要靠超声及CT,但是对异位肾分肾肾功能的评价,肾动态显像具有明显的优势。笔者通过文献复习加深了对Gate's法的认识,结合该病例得出指导性结论:1、对已发现有一器官畸形的新生儿,应该留意是否合并其他器官的畸形,做到早发现早干预;2、SPECT/CT可对异位肾的形态及功能进行一站式诊断,优势明显;3、对于特殊肾脏的肾小球滤过率的测定,Gate's法需要适当的矫正。Abstract: SPECT/CT imaging was conducted on an ectopic kidney in a patient with congenital anal atresia. Most cases of ectopic kidney are found by chance during physical examination given the lack of the specific clinical symptoms of this condition during its early stage. At present, the diagnosis of ectopic kidneys mainly depends on ultrasound and CT. Renal dynamic imaging, however, provides advantages for the evaluation of the individual functions of ectopic kidneys. Gate's method was used to detect the glomerular filtration rate of an ectopic kidney. Literature review was performed to obtain a deep understanding of Gate's method. The following guiding conclusions were drawn:1. The co-occurrence of other organ malformations in newborns with kidney malformations should receive close attention. Early detection and intervention are necessary to manage ectopic kidneys. 2. SPECT/CT enables the advantageous one-stop diagnosis of the morphology and function of ectopic kidneys. 3. Gate's method requires proper correction for the glomerular filtration rate determination of kidneys with special characteristics.
-
Key words:
-
[1] Tonnesen KH, Mogensen P, Wolf H, et al. Residual kidney function after unilateral nephrectomy. Pre-and postoperative estimation by renography and clearance measurements[J]. Scand J Urol Nephrol, 1976, 10 (2):130-133. DOI:10.3109/00365597609179672. [2] Gehan EA, George SL. Estimation of human body surface area from height and weight[J]. Cancer Chemother Rep, 1970, 54 (4):225-235. [3] Blaufox MD, Aurell M, Bubeck B, et al. Report of the Radionuclides in Nephrourology Committee on renal clearance[J]. J Nucl Med, 1996, 37 (11):1883-1890. DOI:10.1016/S0022-5347 (01)62326-7. [4] 杨红, 刘育青, 李聪革, 等. γ照相法GFR与双血浆标本法GFR的比较[J].中华核医学杂志, 2000, 20 (2):74. DOI:10.3760/cma.j.issn.0253-9780.2000.02.022.
Yang H, Liu YQ, Li CG, et al. Comparison of glomerular filtration rate measurements with gamma camera methods and two plasma sample methods[J]. Chin J Nucl Med, 2000, 20 (2):74. doi: 10.3760/cma.j.issn.0253-9780.2000.02.022[5] Joung HS, Guerrero AL, Tomita S, et al. Imperforate Anus with Jejunal Atresia Complicated by Intestinal Volvulus:A Case Report[J]. J Neonatal Surg, 2016, 5 (4):59. DOI:10.21699/jns.v5i4.458. [6] Tveter KJ, Fonkalsrud EW, Goodwin WE. Single vaginal ectopic ureter and solitary kidney, associated with imperforate anus and other malformations. A case report[J]. Scand J Urol Nephrol, 1980, 14 (1):119-121. doi: 10.3109/00365598009181203 [7] Eckford SD, Westgate J. Solitary crossed renal ectopia associated with unicornuate uterus, imperforate anus and congenital scoliosis[J]. J Urol, 1996, 156 (1):221. doi: 10.1016/S0022-5347(01)66005-1 [8] Gates GF. Computation of glomerular filtration rate with Tc-99m DTPA:an in-house computer program[J]. J Nucl Med, 1984, 25 (5):613-618. [9] 麻广宇, 邵明哲, 陈云爽, 等.肾脏深度对SPECT测定肾小球滤过率的影响[J].中国医学影像技术, 2013, 29 (5):800-804. DOI:10.13929/j.1003-3289.2013.05.034.
Ma GY, Shao MZ, Chen YS, et al. Impact of kidney depth on the measurement of glomerular filtration rate with SPECT[J]. Chin J Med Imaging Technol, 2013, 29 (5):800-804. doi: 10.13929/j.1003-3289.2013.05.034[10] 李乾, 张春丽, 王荣福.肾动态显像测定肾小球滤过率的影响因素[J].中国医学影像技术, 2004, 20 (6):962-964. DOI:10.3321/j.issn:1003-3289.2004.06.046.
Li Q, Zhang CL, Wang RF. Influence elements in the process of dynamic renal imaging to measure glomerular filtration rate[J]. Chin J Med Imaging Technol, 2004, 20 (6):962-964. doi: 10.3321/j.issn:1003-3289.2004.06.046