Doppler examination of the kidney in infants and children

Doppler sonography has become a reliable indicator of renal vascularization. Color Doppler permits mapping of regional intrarenal blood flow, as well as flow in the main renal artery and vein. The spectral display of the Doppler signal arising from the renal arteries yields valuable information about the state of the peripheral vascular bed. Our understanding of intrarenal Doppler curves has evolved from a simplistic model of pulsatility index number equals diagnosis to the more sophisticated concept that changes in these curves imply a change in the physiology of the kidney. This is a summary of current clinical applications of the Doppler technology to diseases of the kidney in the child.     

Colour Doppler ultrasonography evaluation of vascularization in the wrist and finger joints in rheumatoid arthritis patients and healthy subjects

Objectives

To evaluate the presence of blood flow by colour Doppler ultrasonography (CDUS) in the wrist and finger joints of rheumatoid arthritis (RA) patients and healthy subjects and to define a cut-off value of CDUS resistive index (RI).

Methods

Forty-three patients with RA and 43 healthy controls were examined by CDUS. The wrists, second and third metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints were evaluated in each patient and healthy subject. Spectral Doppler analysis was performed in order to characterize the type of flow and a mean RI was measured to define a cut-off level. The area under receiver operating characteristic curve was used to evaluate the screening method's performance.

Results

Flow was detected in 219 of the 430 total joints (50.9%) of RA patients (111 in the wrists, 49 in the MCP and 30 in the PIP joints). Healthy subjects had a quantifiable flow in 45 of the 430 joints (10.5%) and, in particular, 39 (86.4%) in the wrist, 5 (11.14%) in the MCP and 1 (2.2%) in the PIP joints. The intra- and inter-reader agreements for the detection of Doppler signal were very good (kappa 0.82 and 0.89, respectively). Mean RI values were 0.72 ± 0.06 in RA patients and 0.86 ± 0.06 in healthy subjects (p < 0.01). At cut-off point of RI < 0.79 the sensitivity was 89.6% and the specificity was 78.8% (positive likelihood ratio 4.22).

Conclusion

DUS is a useful tool for the detection of abnormal blood flow in inflammatory joints of RA patients.     

Ultrasound of the kidney: obstruction and medical diseases

Ultrasound has emerged as the primary imaging modality in conditions where either renal obstruction or renal medical disease is suspected on the basis of clinical and laboratory findings. In urinary tract obstruction, pathophysiologic changes affecting the pressure in the collecting system and kidney perfusion are well understood and form the basis for the correct interpretation of real-time US and color Doppler duplex sonography (CDDS). Ultrasound is very sensitive for the detection of collecting system dilatation ("hydronephrosis"); however, obstruction is not synonymous with dilatation, as either obstructive or nonobstructive dilatation may be present. To differentiate these conditions, CDDS with measurement of the resistive index (RI) in the intrarenal arteries is extremely helpful, as obstruction (except in the peracute stage) leads to intrarenal vasoconstriction with a consecutive increase of the RI above the upper limit of 0.7, whereas nonobstructive dilatation does not. Diuretic challenge to the kidney may further enhance these differences in RI between obstruction and dilatation. Based on these findings, the present value of US and CDDS in the assessment of the patient with flank pain or renal colic is suggested, especially with respect to promising results for spiral CT and based on cost analysis. In renal medical disease, distinguishing different pathologic conditions using gray-scale US and CDDS (RI) criteria is still very difficult. Nevertheless, US is the fist-line imaging modality in the patient with renal insufficiency. Electronic Publication     

Percutaneous intervention in the solitary kidney

The solitary kidney, either after nephrectomy or on a congential basis, may be impaired by infection, stones, obstruction, and trauma. Because of the possibility of further renal compromise by damage of the remaining nephron units, there is reluctance to utilize percutaneous techniques in cases of solitary kidney, and surgery is often used as an alternative. We report 15 cases of solitary kidney in which interventional radiologic techniques (i.e., percutaneous nephrostomy, ureteral stenting, ureteral dilatation, and stone extraction) were attempted for the preservation of renal function, either as a permanent solution or as a temporizing maneuver prior to definitive therapy. In each case, these goals were achieved and there were no complications.     

Doppler sonographic renal resistance index and resistance index ratio in children and adolescents with unilateral hydronephrosis

The aim of this study was to evaluate Doppler renal resistance index (RI) and RI ratio (RIR) in differentiating between obstructive and nonobstructive hydronephrosis in children and adolescents. The RI and RIR were measured in 32 healthy examinees (control group) and 29 patients with unilateral hydronephrosis. Ten patients had acute obstruction caused by a ureteric stone. Seven had obstructive hydronephrosis due to uretero-pelvic junction (UPJ) obstruction. Twelve patients had nonobstructive hydronephrosis. In controls the mean RI±S.D. was 0.615±0.04, and RIR 1.045±0.033. In children with acute obstruction RI was 0.692±0.035 and RIR 1.148±0.037. In UPJ obstruction RI was 0.631±0.054 and RIR 1.059±0.047. In nonobstructive dilatation RI was 0.61±0.038 and RIR 1.043±0.042. The RI and RIR differences were statistically significant between controls and patients with acute colic (p<0.01), and between patients with acute obstruction and with nonobstructive hydronephrosis (p<0.01). In detecting acute obstruction RI≥0.70 was found to have a 70% sensitivity and a 92% specificity. The RIR≥1.10 was found optimal to distinguish obstructive from nonobstructive dilatation (sensitivity 90%, specificity 83%). Both RI and RIR are significantly elevated in patients with acute obstruction. Renal Doppler seems to be useful in children and adolescents for the detection of acute renal obstruction, although it cannot differentiate chronic obstruction due to the UPJ obstruction and nonobstructive renal collecting system dilatation. Electronic Publication     

Doppler examination of the allografted kidney

A comprehensive ultrasound examination of the transplanted kidney includes a Doppler examination. Duplex Doppler, color Doppler and power Doppler can all reveal important information. In addition, calculation of the resistance and pulsatility indices to quantify changes in the spectral Doppler waveform can be of great help, particularly in the first weeks and months following a transplantation. The Doppler part of the examination should evaluate the vessels to and from the transplant, as well as the parenchyma with calculations of indices to detect the presence of increased vascular resistance. The conclusions drawn from the Doppler-derived information combined with the results from gray-scale scanning and clinical information will very often be of clinical significance for the handling of the patient.     

Contrast-enhanced power Doppler US in the diagnosis of renal pseudotumors

The term "pseudotumor" is used to refer to several anatomic variants that can simulate a renal mass, the most frequent of which are hypertrophied column of Bertin, persistence of fetal lobation, and the dromedary or splenic hump. We describe the findings of power Doppler US after the ultrasound contrast agent (Levovist, Schering, Berlin, Germany) administration in 4 patients with a renal focal lesion in whom gray-scale and baseline power Doppler US was not able to certainly differentiate pseudotumor from neoplasm.     

传统二维及彩色多普勒超声对肾细胞癌的诊断价值

目的:通过分析肾细胞癌的超声表现及特征,评价传统二维及彩色多普勒超声对肾细胞癌的诊断价值.方法:对2005年1月～2010年11月经手术病理证实的24例肾细胞癌患者的超声声像图进行分析.结果:17例直径＞3 cm的肾细胞癌二维超声表现为内部回声不一,强弱不等,无特征性表现.7例直径≤3 cm的肾细胞癌有6例表现为等回声...     

Normal differential renal function does not indicate a normal kidney after partial ureteropelvic obstruction and subsequent relief in 2-week-old piglets

Purpose  We investigated the functional consequences of relieving ureteric obstruction in young pigs with experimental hydronephrosis (HN) induced by partial unilateral ureteropelvic obstruction. Materials and methods  Three groups of animals were followed from the age of 2 weeks to the age of 14 weeks: Eight animals had severe or grades 3–4 HN throughout the study. Six animals had relief of the obstruction after 4 weeks. Six animals received sham operations at both ages. Morphological and functional examinations were performed at age 6 weeks and again at age 14 weeks and consisted of magnetic resonance imaging (MRI), technetium-diethylenetriaminepentaaceticacid (^99mTc-DTPA) renography, renal technetium-dimercaptosuccinicacid (^99mTc-DMSA) scintigraphy, and glomerular filtration rate (GFR) measurement. Results  After relief of the partial obstruction, there was reduction of the pelvic diameter and improvement of urinary drainage. Global and relative kidney function was not significantly affected by either obstruction or its relief. Renal ^99mTc-DMSA scintigraphy showed a change in both the appearance of the kidney and a change in the distribution within kidneys even after relief of obstruction. Conclusion  This study shows that partial ureteric obstruction in young pigs may be associated with little effect on global and differential kidney function. However, even after relief of HN, the distribution of ^99mTc-DMSA in the kidney remains abnormal suggesting that a normal differential renal function may not represent a normal kidney.     

肾脏血流阻力指数对实验性单侧输尿管部分梗阻的诊断价值

目的判断肾脏血流阻力指数(RI)对实验性单侧输尿管部分梗阻的诊断价值。方法40只成年大白兔制作成单侧输尿管部分梗阻模型,应用彩色多普勒超声仪在术前、术后1、2、4、8周随机测量10只动物的双侧肾脏RI,并计算双侧RI的差值(△RI)和比率(RIR)。以RI≥0.7,△RI≥0.1,RIR≥1.10为标准计算其诊断梗阻的准确性。结果随着梗阻时间的延长,RI进行性升高,RI,△RI和RIR诊断梗阻的准确性依次提高。结论梗阻发生后RI是一个时间相关性的生理参数,比较双侧肾脏的RI值可显著提高其诊断梗阻的准确性。     

Amplitude coded-colour Doppler sonography in paediatric renal disease

The aim of our study was to assess the ability of amplitude coded-colour Doppler sonography (ACDS) to depict altered perfusion in paediatric renal disease in a prospective study. Colour Doppler sonography (CDS) and ACDS examinations were performed in 180 renal units (90 patients; age range newborn to 16 years) with unilateral or bilateral renal disease (e. g. reflux nephropathy, renal scars, end-stage renal disease, ureteropelvic junction obstruction, urinary tract infection, renal failure, haemolytic uraemic syndrome, nephrotic syndrome, systemic lupus erythematosus (LE), renal biopsy, congenital dysplasia, tumour/infiltration). The ACDS results were compared with scintigraphy or CT as well as to clinical findings. Amplitude colour-coded Doppler sonography accurately demonstrated normal vasculature in 49 of 51 healthy kidneys ( = 96 %); 3 healthy kidneys could not be evaluated due to motion/artefacts. In 39 of 43 kidneys with focally altered perfusion ACDS could be performed and correctly depicted focally impaired vasculature/perfusion in 35 kidneys ( = 89.7 %). Seventy-three of 83 kidneys with diffusely impaired perfusion could be evaluated by ACDS and altered pattern was correctly depicted in 58 kidneys ( = 79.4 %), with an overall percentage of agreement of 87.1 %. Amplitude CDS appears to be useful in infants and children. Compared with CDS it improves visualisation of especially focally impaired vasculature/perfusion and should be considered a valuable adjunct to conventional investigations. Received: 12 June 1999 Revised: 10 December 1999 Accepted: 11 August 2000     

Pitfalls in the ultrasound diagnosis of upper urinary tract obstruction

Evaluation for possible obstruction of the upper urinary tract with ultrasound can be complicated by pitfalls. Representative examples of pitfalls are reviewed and illustrated in this essay. Since both overdiagnosis and underdiagnosis of urinary obstruction can lead to grave consequences, one must be aware of these pitfalls when performing and interpreting renal ultrasound studies.     

Duplex Doppler analysis of interlobular arteries in transplanted kidneys

The aim of our study was to analyze changes in spectral Doppler waveforms between interlobar and interlobular arteries in renal transplants and to determine whether sampling location at interlobular level can be suitable for intrarenal resistive index (RI) measurements. Paired series of spectral tracings from interlobar arteries and respective interlobular branches were obtained in 62 consecutive renal transplants at 6.5-MHz Doppler frequency. The values of peak systolic velocity (PSV), end diastolic velocity (EDV) and RI were significantly (P < 0.01) reduced when calculated at interlobular level. In 38 % of cases, an interlobar RI higher than 0.70 corresponded to a normal interlobular RI. The values of PSV, EDV, and RI did not differ significantly at interlobular level between allograft subsets with normal and elevated serum creatinine level. Both intra- and interobserver variation were higher at interlobular than at interlobar level when performing the RI. During a conventional study of renal vasculature, an underestimation of abnormal RI findings can be expected from the incidental evaluation of interlobular tracings. We recommend sonologists to pay attention in accurately locating the sample volume at interlobar–arcuate level when evaluating intrarenal RI. Received 30 December 1996; Revision received 16 May 1997; Accepted 3 September 1997     

Metastatic RCC arising in a transplant kidney

We report a case of metastatic renal cell carcinoma arising in a cadaver transplant kidney 6 years after transplantation. Due to molecular analysis of the tumor tissue we could prove that the carcinoma originated from the male donor. After tumor resection and interruption of immunotherapy, the concomitant bone and lymph node metastases resolved with alpha-interferon and interleukin-2-based immunotherapy. Received 28 August 1997; Revision received 23 December 1997; Accepted 29 December 1997     

彩色多普勒在宫外孕中的应用价值

目的 评价彩色多普勒在宫外孕诊断中的价值。方法 对临床拟诊的宫外孕62例患者经二维图像、彩色多普勒显像、频普多普勒技术分析与病理结果对照，分析其诊断的正确性。结果 62例超声诊断的宫外孕中55例正确诊断，诊断符合率为887％。结论 彩色多普勒诊断宫外孕具有重要价值。     

Balance impairment in kidney transplant recipients without concurrent peripheral neuropathy

Kidney transplant recipients (KTRs) present with compromised functional capacity, low levels of physical activity, muscle atrophy, and peripheral nerve dysfunction that may result in high postural instability. This study aimed to compare the static balance control of 19 KTRs with 19 healthy adults (HA). All participants completed the Romberg test on a stabilometric platform with eyes open (EO), eyes closed (EC) and during a dual task (DT) condition. Centre of pressure (COP) measures (COP velocity (COPv) and sway area (SA)), as well as position-based outcomes such as anterior-posterior (AP) and medio-lateral (ML) ranges of COP displacements were recorded. Independent ANCOVA revealed an overall lower performance of KTRs compared to HA (p < 0.05) with the EC condition exhibiting the worst relative performance for KTRs, suggesting a poorer capacity of relying on proprioceptive information when maintaining the upright posture. The addition of a cognitive task did not further worsen balance performance in KTRs. As impaired postural control is one of the main predictors of falls in elderly subjects, these data might also indicate that this constitutes an equivalent risk factor for falling in middle-aged KTRs.