Color-coded Doppler sonography of renal vessels in childhood. I. Method and normal values

Doppler sonography allows measurement of renal blood flow velocities non invasively. Combination of pulsed Doppler with gray scale imaging (Duplex-scan) yields precise measurement of the flow in defined vessels. By means of the Duplex technique not only the flow parameters in the renal artery and vein can be measured, but also in the segmental, interlobar and interlobular arteries and veins. Colour coded Doppler sonography allows simultaneous display of the flow within the vessels and the gray scale image. With the help of colour coded Doppler sonography the sample volume of the pulsed Doppler device can be placed precisely within the vessels, which makes possible the determination of absolute flow velocities. Besides the flow velocities other different indices have been defined in the literature. All indices result from comparison of systolic and diastolic flow amplitudes in different ways. The flow parameters in the renal vessels are dependent on the site of the flow measurement and the age of the children. When pathologic flow parameters are analyzed the vessel and the age of the child have to be mentioned always. The interpretation of pathologic flow profiles becomes easier by knowledge of normal values for the flow velocities and the different indices.     

Abdominal Doppler sonography in childhood

With the help of pulsed Doppler sonography and colour coded Doppler sonography noninvasive measurements of blood flow within the abdominal vessels are possible. Cystic and tubular abdominal masses and vascular structures can be differentiated. Laminar and turbulent flow as well as arterial and venous flow can be distinguished. The direction of blood flow can be shown. Regarding liver circulation Doppler sonography of portal hypertension, portal vein thrombosis, veno-occlusive-disease, Budd-Chiari-Syndrome and transplant rejection or other vascular complications after liver transplantation can be shown. The circulation of the spleen should be examined if aneurysms, thrombosis or portal hypertension are suspected. Mesenterial circulation should be investigated in suspected vascular occlusion, arterial stenosis and necrotizing enterocolitis. Renal Doppler sonography is helpful for the diagnosis of renal artery stenosis, arterio-venous fistulas, renal vein thrombosis and acute transplant rejection.     

Unilateral renal artery stenosis. Color-coded Doppler sonography and captopril scintigraphy in a 13-year-old patient]

Modern noninvasive techniques, such as doppler sonography or color-encoded doppler sonography, have only rarely been used for diagnosis of renovascular hypertension in children. In the following case report, we describe the successful diagnosis of renovascular hypertension in a 13-year-old girl by using color-encoded doppler sonography and Captopril renal scintigraphy. The patient was admitted with hypertension of 180/130 mmHg. Laboratory findings showed elevated plasma renin and aldosterone concentrations. No abnormalities were found by abdominal sonography, isotope renography, intravenous pyelography, or in venous digital subtraction angiography. However, subsequent color-encoded doppler sonography clearly showed evidence of an artery stenosis of the right kidney. Furthermore, isotope renography one hour after oral administration of captopril revealed an almost complete loss of glomerular filtration rate of the right kidney. Based on these findings, arterial digital subtraction angiography, including transluminal angioplasty, was performed. During this treatment procedure, the right renal artery stenosis could be confirmed and was subsequently dilated without complication. In the following twelve months the patient remained normotensive and required no further antihypertensive drug treatment.     

Alterations in regional cerebral blood flow in neonatal stroke: preliminary findings with color Doppler sonography

Little information is available regarding alterations in regional cerebral blood flow and vascularity on cranial sonography in infants with focal ischemic brain injury. This study describes the use of color Doppler sonography in the characterization of these changes following acute neonatal stroke. Color Doppler examinations were performed as part of the series of clinically indicated cranial sonograms in eight infants with clinical, sonographic, and CT evidence of acute cerebral infarction. The cerebral vascularity of each hemisphere was assessed for symmetry and for presence of abnormal blood vessels. Initial Doppler study in four infants with hypoxic-ischemic infarcts showed increased size and number of visible vessels in the periphery of the infarct and increased mean blood flow velocity in vessels supplying or draining the infarcted areas. Diminished vessel number and size and frequency shifts suggestive of decreased hemispheric perfusion was identified in one infant with middle cerebral artery insufficiency. Repeat Doppler studies were performed on two infants. These showed the development of multiple small, irregular blood vessels in the periphery of the infarct. Focal abnormalities in regional cerebral blood flow may be present as part of the normal healing process following neonatal stroke, and can be demonstrated with color Doppler sonography.     

Color-coded Doppler evaluation of cholecystic varices in portal hypertension

A 11-year-old white girl presented with a diagnosis of thrombosis of the portal vein after newborn septicemia. Duplex sonography revealed significant narrowing of the portal vein and its right and left branches. A Doppler signal could only be obtained in certain short segments of the portal vein and indicated hepatopetal flow. Color-coded Doppler sonography showed extensive varicose veins in the gallbladder with a bigger draining vessel running to the porta hepatis. Documentation of varices like those in the gallbladder wall confirms the diagnosis of portal hypertension and may increase the sensitivity of Doppler sonography. Color mapping has the potential to detect unexpected flow and to analyze blood flow to better advantage.     

Diagnosis of bilateral renal vein thrombosis in infancy by pulsed Doppler sonography of the renal vessels

In a premature infant bilateral renal venous thrombosis and associated thrombosis of the inferior vena cava were diagnosed at the age of 6 weeks, using a 2-dimensional ultrasound sector scanner with integrated pulsed doppler ultrasound of the renal vessels. In contrast to 30 healthy children, who showed continuous forward flow in the renal arteries throughout systole and diastole, diastolic flow was decreased or even retrograde in renal venous thrombosis (RVT) according to the severity of thrombosis. Doppler recordings in renal veins normally showed continuous retrograde flow patterns, whereas in RVT venous flow was decreased or absent. Pulsed doppler ultrasound is a useful and noninvasive method for recording renal flow patterns, especially in renovascular disease.     

血液净化技术在儿童肾脏疾病中的应用

血液净化技术是从单纯超滤发展而来的一种血液净化疗法,其应用远远超出了肾脏病的范畴,已被用于各种原因引起的机体内环境紊乱的治疗.文章主要介绍儿童血液净化技术包括建立良好的血管通路、滤器的选择、何时需要进行体外循环预充、抗凝的方法、血液净化的参数凋节及血液净化压力监测,同时阐述血液净化技术在儿童肾脏疾病中的治疗现状及进展.     

Color Doppler sonography in the diagnosis of acute scrotum in boys.

Evaluation of acute painful scrotum is difficult and imaging studies have been reported to be unreliable in detecting testicular torsion. In order to assess the value of color Doppler sonography in acute scrotal disease, the authors reviewed 65 consecutive boys, ranging in age from 1 to 16 years. The study demonstrated absent or diminished flow signals in 11 patients. All of them had a surgical intervention, and in 8 of them, a testicular torsion was confirmed. 54 boys had a symmetrical or increased flow signal on the affected side. Just 5 boys among this group underwent surgical exploration. On follow up, none of the 54 patients with good flow signals proved to have a testicular torsion. Sonography and color Doppler sonography helped to differentiate epididymitis and torsion of a testicular appendage as a basis for further investigations and correct conservative therapy. In detecting a testicular torsion, color Doppler sonography yielded a positive predictive value of 73%, a sensitivity of 100% and a negative predictive value of 100%. We therefore conclude, that Doppler sonography can reliably rule out testicular torsion so that routine scrotal exploration in cases of acute scrotum is no longer necessary. By reducing the number of emergency operations and hospitalization days, color Doppler sonography can cut down the total cost of managing acute painful scrotum in boys.     

Evaluation by colour Doppler and pulsed Doppler sonography of blood flow velocities in intracranial arteries during the early neonatal period

Using a colour pulsed Doppler flow mapping system, we examined the intracranial arteries of 40 healthy infants. The anterior cerebral, basilar, intracranial internal carotid and middle cerebral arteries were visualized clearly enough to evaluate flow velocity at the success rates of 100%, 87.5%, 65% and 82.4%, respectively. In the anterior cerebral, intracranial internal carotid and middle cerebral arteries, the maximum blood flow velocity slightly decreased to a minimum at around 4–6h after birth, and then gradually increased. The minimum blood flow velocity pattern was similar. The maximum blood flow velocity in the basilar artery decreased from 0–3h, rapidly increased from 4–6h, and remained at a steady level thereafter. A possible mechanism for the chronological changes in the intracranial blood flow velocity is discussed.     

Portal venous blood flow in cystic fibrosis: assessment by Duplex Doppler sonography

Changes of portal venous hemodynamics were investigated in 32 patients with cystic fibrosis (CF) with a mean age of 11.6 years. Hepatic profile of these patients included total bilirubin and albumin together with determination of size and echogenicity of the liver and spleen, determination of the diameter of the portal vein by real-time sonography and quantitation of flow volume of the portal vein using Duplex Doppler sonography. As a control, 35 age matched healthy children were also examined. Diameter of the portal vein was significantly increased in CF patients versus controls. Comparison of the mean flow volume of the portal vein showed a significant increase in CF-patients over 12 y old versus controls. In patients less than 12 y no significant difference of flow volume of the portal vein between CF-patients and controls was noted. The increase of diameter and flow volume of the portal vein suggest an adaptive mechanism in the pressure-volume relationship of the portal venous system in patients with CF.     

Diagnosis of brain death by transcranial Doppler sonography.

The blood flow velocities in the basal cerebral arteries can be recorded at any age by transcranial Doppler sonography. We examined nine children with either initial or developing clinical signs of brain death. Soon after successful resuscitation increased diastolic flow velocities indicated a probable decrease in cerebrovascular resistance; this was of no particular prognostic importance. As soon as there was a clinical deterioration, there was a reduction in flow velocities with retrograde flow during early diastole, probably due to an increase in cerebrovascular resistance; this indicated a doubtful prognosis. In eight of the nine children with clinical signs of brain death a typical reverberating flow pattern was found, which was characterised by a counterbalancing short forward flow in systole and a short retrograde flow in early diastole. This indicated arrest of cerebral blood flow. One newborn showed normal systolic and end diastolic flow velocities in the basal cerebral arteries for two days despite clinical and electroencephalographic signs of brain death. Shunting of blood through the circle of Willis without effective cerebral perfusion may explain this phenomenon. No patient had the typical reverberating flow pattern without being clinically brain dead. Transcranial Doppler sonography is a reliable technique, which can be used at the bedside for the confirmation or the exclusion of brain death in children in addition to the clinical examination.     

Angiotensin II type 1 receptor antibodies in childhood kidney transplantation

Angiotensin II type 1 receptor antibodies (AT₁RAb) have emerged as non‐HLA Ab present in patients with acute AMR and risk of graft loss. Furthermore, AT₁RAb have been shown to increase angiotensin II sensitivity which may play a role in the development of CVD and hypertension. Data on AT₁RAb in stable transplant recipients are lacking. The aim of this study was to analyze the levels of AT₁RAb in a cohort of stable patients after kidney transplantation (tx) in childhood. A cross‐sectional study of 30 children (median age 14, range 3–19 yr, median time since tx five yr) and 28 adults who were transplanted in childhood (median age 26, range 20–40 yr, median time since tx 18 yr) transplanted between 1993–2006 and 1983–2002, respectively, was performed. Healthy controls were 51 healthy children (5–8 yr) and 199 healthy donors (median age 56.5 yr, range 42–83 yr). Plasma AT₁RAb were analyzed by immunoassay. Median total AT₁RAb IgG concentration was significantly higher in the pediatric‐tx group as compared to the adult‐tx group (40.0 and 10.95 U/mL, p < 0.0001). For both groups, the tx group showed higher levels: the pediatric‐tx group vs. control group (40.0 vs. 13.3 U/mL, p = 0.0006) and the adult‐tx group vs. adult control group (10.95 vs. 6.5 U/mL, p < 0.0001). Age was the strongest indicator of high levels of AT₁RAb IgG (p = 0.0003). AT₁RAb total IgG levels are significantly higher in a stable pediatric‐tx cohort as compared to adult‐tx patients and healthy controls of comparable age groups. The relevance of our findings in relation to age, time since tx, previous or future rejection, and CVD risk merits future studies.     

The relevance of duplex Doppler sonography in pediatrics

Since the introduction of duplex Doppler sonography the noninvasive assessment of hemodynamic changes in children has become possible. The clinical application comprises the depiction of cerebral hemodynamics in infants, where characteristic flow patterns can be found in patent ductus arteriosus, hypoxic-ischemic encephalopathy, cerebral hemorrhage, hydrocephalus or in brain death. Moreover, Duplex Doppler Sonography play an important role in the evaluation of renal hemodynamics, especially in kidney transplants. Finally, the examination of the portal venous system can demonstrate thrombosis of the portal vein, portosystemic collaterals or a hepatofugal flow in severe portal hypertension. Thus, invasive investigative procedures may become unnecessary in certain cases. The future potential of this technique lies in the development of quantitative measurements of volume flow and in Doppler color flow imaging.     

Reliability of color Doppler and power Doppler sonography in the evaluation of intussuscepted bowel viability

In two similar cases of irreducible intussusception with wall necrosis and perforation, symptoms had begun 24 h before admission and the plain radiographs showed signs of small-bowel obstruction. The sonographic (US) appearances, however, were different: color Doppler (CD) US showed vascular flow in the intussuscepted bowel in one case and no flow in the other. After radio-clinical assessment, both children underwent surgery and an intestinal resection had to be performed, manual reduction being impossible. The reliability of the US findings and the prognostic value of CD and power Doppler US in determining the viability of the intussuscepted bowel are discussed with a review of the literature. Accepted: 24 November 1997