The role of CT angiography in the evaluation of pediatric renovascular hypertension

Multimodal imaging approach in hyponatremic hypertensive syndrome. A rare case of pediatric unilateral hypoplasia of the main renal artery combined itself with stenosis and review of literature

Renal artery stenosis (RAS) accounts for approximately 5%-10% of secondary renovascular hypertension in the pediatric population. It can occur as an isolated entity, or as a hypoplasia combined itself with stenosis. Hypoplasia, or long-segment developmental narrowing, is a rare cause of renovascular hypertension. Hyponatremic hypertensive syndrome (HHS) is a malignant complication of unilateral RAS and/or renal artery hypoplasia. Hyponatremia, hypokalemic hypochloremic metabolic alkalosis, nephrotic range proteinuria, polyuria, polydipsia, and weight loss are the most common findings. In particular, hypertension remains refractory despite aggressive antihypertensive therapy. Laboratory findings of elevated plasma levels of renin in most case suggest that the stimulation of renin release from the ischemic kidney plays an important pathophysiologic role. HHS is a diagnostic and therapeutic challenge in children. We report a case of a unilateral right renal artery hypoplasia, complicated by a segmental narrowing, in a 17-month-old male, clinically symptomatic for hypertension. We emphasize the role of ultrasound, computed tomography, and digital subtraction angiography that should be planned as reliable and non-invasive multimodal imaging approach.

Validation of computed tomography angiography as a complementary test in the assessment of renal artery stenosis: a comparison with digital subtraction angiography

BACKGROUND

Renal artery stenosis is an important cause of hypertension in children, accounting for 5-10% of cases. When suspected, noninvasive imaging options include ultrasound (US), computed tomography (CT) angiography and magnetic resonance (MR) angiography. However, digital subtraction angiography (DSA) remains the gold standard.

OBJECTIVE

To investigate the accuracy and inter-reader reliability of CT angiography in children with suspected renal artery stenosis.

MATERIALS AND METHODS

This is a retrospective study of patients suspected of having renal artery stenosis evaluated by both CT angiography and DSA between 2008 and 2019 at a tertiary pediatric hospital. Only children who underwent CT angiography within 6 months before DSA were included. CT angiography studies were individually reviewed by two pediatric radiologists, blinded to clinical data, other studies and each other's evaluation, to determine the presence of stenosis at the main renal artery and 2nd- and 3rd-order branches. The sensitivity, specificity and accuracy were calculated using DSA as the reference. The effective radiation dose for CT angiography and DSA was also calculated. Kappa statistics were used to assess inter-reader agreement.

RESULTS

Seventy-four renal units were evaluated (18 girls, 19 boys). The patients' median age was 8 years (range: 1-21 years). Overall, CT angiography was effective in detecting renal artery stenosis with a sensitivity of 85.7%, specificity of 91.5% and accuracy of 88.9%. There was moderate inter-reader agreement at the main renal artery level (k=0.73) and almost perfect inter-reader agreement at the 2nd/3rd order (k=0.98). However, the sensitivity at the 2nd- and 3rd-order level was lower (14.3%). CT angiography provided excellent negative predictive value for evaluating renal artery stenosis at the main renal artery level (90.1%) and at the 2nd- or 3rd-order branches (82.7%). The median effective dose of CT angiography studies was 2.2 mSv (range: 0.6-6.3) while the effective dose of DSA was 13.7 mSv.

CONCLUSION

CT angiography has high sensitivity and specificity at the main renal artery level with a lower radiation dose than previously assumed. Therefore, it can be used as a diagnostic tool in patients with low to medium risk of renal artery stenosis, and as a screening and treatment planning tool in patients at high risk.

Diagnostic sensitivity and specificity of CT angiography for renal artery stenosis in children

BACKGROUND

Children with suspected renal artery stenosis (RAS) are screened with renal Doppler ultrasonography or computed tomography (CT) angiography/magnetic resonance (MR) angiography depending on institutional preference. CT angiography produces images with superior resolution, allowing higher quality multiplanar two-dimensional reformats and three-dimensional reconstructions. However, there is a paucity of data in the literature regarding the utility and diagnostic performance of renal CT angiography in pediatric RAS.

OBJECTIVE

The objective of this study is to retrospectively review our experience with renal CT angiography in the diagnosis of pediatric RAS relative to digital subtraction angiography (DSA) as the reference standard.

MATERIALS AND METHODS

All patients 0-18 years of age who underwent CT angiography for evaluation of RAS as a cause of hypertension between January 2012 and May 2019 were identified for the study. A total of 131 patients were identified, 23 of whom had DSA correlation.

RESULTS

Twenty-three patients (17 boys, 6 girls) with a mean age of 6 years 3 months (range: 3 months to 14 years 7 months) were included in this study. Of the 59 renal arteries studied by DSA, 22 were abnormal on CT angiography and 20 were abnormal on DSA. Of the 59 renal arteries, CT angiography was true positive in 18 and true negative in 35. The sensitivity and specificity of CT angiography for RAS diagnosis were 90.0% and 89.7%, respectively. CT angiography identified all cases of main RAS.

CONCLUSION

Renal CT angiography has a high sensitivity and specificity for pediatric RAS diagnosis in patients referred for DSA.

Renovascular hypertension in children

Paediatric hypertension, defined as systolic blood pressure > 95th percentile for age, sex and height is often incidentally diagnosed. Renovascular hypertension (RVH) is responsible for 5-25% of hypertension in children. Renal artery stenosis and middle aortic syndrome can both can be associated with various conditions such as fibromuscular dysplasia, Williams syndrome & Neurofibromatosis type 1. This paper discusses the approaches to diagnosis and interventional management and outcomes of renovascular hypertension in children. Angiography is considered the gold standard in establishing the diagnosis of renovascular disease in children. Angioplasty is beneficial in the majority of patients and generally repeated angioplasty is considered more appropriate than stenting. Surgical options should first be considered before placing a stent unless there is an emergent requirement. Given the established safety and success of endovascular intervention, at most institutions it remains the preferred treatment option.

Optimization of Pediatric Body CT Angiography: What Radiologists Need to Know

OBJECTIVE. Pediatric CT angiography (CTA) presents unique challenges compared with adult CTA. Because of the ionizing radiation exposure, CTA should be used judiciously in children. The pearls offered here are observations gleaned from the authors' experience in the use of pediatric CTA. We also present some potential follies to be avoided. CONCLUSION. Understanding the underlying principles and paying meticulous attention to detail can substantially optimize dose and improve the diagnostic quality of pediatric CTA.

Imaging studies in pediatric fibromuscular dysplasia (FMD): a single-center experience

BACKGROUND

Fibromuscular dysplasia (FMD) is a non-inflammatory vascular disease that in children unlike in adults shows no sex predilection. FMD is often underdiagnosed, and its pathophysiology is unclear. Delayed diagnosis may lead to refractory hypertension and decreases the chance of successful treatment. Doppler ultrasound (US), magnetic resonance angiography (MRA), computed tomography angiography (CTA), and catheter-based angiography (angiography) are currently used to help make a clinicoradiological diagnosis of FMD. The main aim of the study was to compare the efficacy of imaging modalities which can allow for earlier and improved detection. Furthermore, an anatomical mapping of the location of lesions can help determine the best treatment modalities.

METHODS

All patients with non-syndromic non-inflammatory renovascular hypertension were recruited from the Nephrology Department at the Children's Hospital of Philadelphia (CHOP) and enrolled in the U.S. FMD Registry maintained at the University of Michigan. Clinical presentation and imaging findings on US, CT, and MRI of children diagnosed with FMD were evaluated.

RESULTS

Mean age at diagnosis was 7 ± 4.9 years (4 months-17 years). Family history of hypertension (HTN) (52%), FMD (8.7%), Caucasian (60%), headache (48%), and HTN (80%) were the most prevalent symptom and sign at presentation. Bruits were 100% specific for renal artery stenosis (RAS) diagnosis but were heard in the minority of patients (3 patients, 12%). FMD was mainly unifocal within a single site (68%) or multiple sites (28%) and involved the main or first order renal branch in about 68% of children. Isolated distal lesions beyond the second order branches were found in about 25% of children. US imaging was significantly less sensitive than angiography (28%, p = 0.003). MRA had a better sensitivity (62.5%, p = 0.3) than US. Overall, CTA had the best sensitivity (84.2%, p = 0.4) compared to angiography; however, only angiography showed distal vessel disease.

CONCLUSIONS

Limitations of the study include the sample size and biases-only patients diagnosed with FMD were included in this study and most patients were referred to a pediatric nephrologist for unexplained hypertension. Angiography should be performed as part of the initial work-up of any child suspected of having renovascular FMD, regardless of the findings seen on US, MRA, or CTA.

Diagnosis and management of systemic hypertension due to renovascular and aortic stenosis in patients with Williams-Beuren syndrome

SUMMARY AIM To describe the incidence, diagnosis, and management of systemic arterial hypertension related to renal artery stenosis in patients with Williams-Beuren syndrome. METHODS Sixty-five patients with Williams-Beuren syndrome were evaluated for hypertension. Enrolled patients underwent Doppler sonography of the renal arteries and Doppler echocardiography. Those with Doppler sonography-detected lesions or with normal Doppler sonography but severe hypertension underwent computed tomography or gadolinium-enhanced magnetic resonance angiography of the aorta and renal vessels. Patients needing vascular therapeutic intervention underwent conventional angiography. RESULTS Systemic arterial hypertension was diagnosed in 21/65 patients with Williams-Beuren syndrome (32%; 13 male) with a mean age of 13.9 years (5mo-20yrs). In 8/21 patients renovascular hypertension was detected. Angioplasty was unsuccessful in five patients with renal artery stenosis, requiring additional treatment. Doppler echocardiography showed cardiac abnormalities in 16/21 (76%) hypertensive patients. CONCLUSION Cardiac abnormalities and hypertension in patients with Williams-Beuren syndrome are common. Thus, thorough evaluation and follow-up are necessary to reduce cardiovascular risks and mortality of these patients

Non-invasive imaging cannot replace formal angiography in the diagnosis of renovascular hypertension

OBJECTIVES

Renovascular disease (RVD) is found in about 10 % of secondary childhood hypertension. Digital subtraction angiography (DSA) is the gold standard to diagnose RVD. Non-invasive imaging methods like Doppler ultrasound (US), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are increasingly used. Our aim was to evaluate the role and accuracy of US, MRA, and CTA compared to DSA in diagnosing RVD in children.

PATIENTS AND METHODS

A retrospective review of 127 children with suspected renovascular hypertension was performed in children referred to Great Ormond Street Hospital between 2006 and 2014 due to clinical suspicion of renovascular hypertension and/or findings on US and/or MRA or CTA.

RESULTS

Ninety-nine of 127 children (78 %) were diagnosed with renovascular disease and 80 were treated with percutaneous transluminal angioplasty during the same procedure. The median age at presentation was 5.6 (range, 2.5-10.6) years. Thirty-six children had unilateral renal artery stenosis in major extraparenchymal vessels, 47 bilateral stenosis and 16 intrarenal small vessel disease. US had a sensitivity of 63 % and specificity of 95 %. MRA and CTA were performed in 39 and 34 children, respectively. CTA sensitivity was slightly higher than that of MRA, 88 vs. 80 %, and specificity 81 vs. 63 %.

CONCLUSIONS

The sensitivity of MRA and CTA is still too low to reliably rule out renovascular disease in children with a strong suspicion of this diagnosis. DSA remains the gold standard to diagnose renovascular hypertension and is recommended when clinical and laboratory criteria are highly suggestive of renovascular disease even with normal radiological investigations from non-invasive methods.

[Renovascular disease in children - a rare diagnosis with few symptoms]

BACKGROUND To estimate the prevalence, symptoms, causes and treatment of renovascular disease in children, and also to assess the degree of secondary organ damage to the heart, kidneys and eyes (end organ damage).MATERIAL AND METHOD Retrospective review of data for all children (0 - 16 years) who were examined for resistant hypertension in the period 1998 - 2013 at Oslo University Hospital Rikshospitalet.RESULTS A total of 21 children/adolescents (median age 8.5 years, 11 girls) were assessed and treated for resistant hypertension in the study period. Altogether had 38 % no symptoms at the time of diagnosis and 19 % had classical symptoms of hypertension. Fifteen patients received invasive treatment in the form of percutaneous transluminal renal angioplasty (PTRA) (n = 5), nephrectomy (n = 6), coiling (n = 1), autotransplantation (n = 1) or a combination of these (n = 2). Blood pressure improved following treatment in 10 of 14 patients for whom outcomes were recorded in the medical records. End organ damage to the heart and retina was observed in 60 % and 50 % of patients, respectively.INTERPRETATION Children with severely elevated blood pressure as a result of renovascular disease often have unspecific or no symptoms. Blood pressure improved following invasive treatment in 10 of 14 children and few complications were recorded. Invasive treatment may be considered in children and adolescents when standard treatment for hypertension is insufficient.

Quality of abdominal computed tomography angiography: hand versus mechanical intravenous contrast administration in children

BACKGROUND

Abdominal CT angiography has been increasingly used for evaluation of various conditions related to abdominal vasculature in the pediatric population. However, no direct comparison has evaluated the quality of abdominal CT angiography in children using hand versus mechanical administration of intravenous (IV) contrast agent.

OBJECTIVE

To compare hand versus mechanical administration of IV contrast agent in the quality of abdominal CT angiography in the pediatric population.

MATERIALS AND METHODS

We retrospectively reviewed the electronic medical record to identify pediatric patients (≤18 years) who had abdominal CT angiography between August 2012 and August 2013. The information obtained includes: (1) type of administration of IV contrast agent (hand [group 1] versus mechanical [group 2]), (2) size (gauge) of IV catheter, (3) amount of contrast agent administered and (4) rate of contrast agent administration (ml/s). Two reviewers independently performed qualitative and quantitative evaluation of abdominal CT angiography image quality. Qualitative evaluation of abdominal CT angiography image quality was performed by visual assessment of the degree of contrast enhancement in the region of interest (ROI) based on a 4-point scale. Quantitative evaluation of each CT angiography examination was performed by measuring the Hounsfield unit (HU) using an ROI within the abdominal aorta at two levels (celiac axis and the inferior mesenteric artery) for each child. Analysis of variance (ANOVA) using the F-test was applied to compare contrast enhancement within the abdominal aorta at two levels (celiac axis and inferior mesenteric artery) between hand administration and mechanical administration of IV contrast methods with adjustment for age.

RESULTS

We identified 46 pediatric patients (24 male, 22 female; mean age 7.3 ± 5.5 years; range 5 weeks to 18 years) with abdominal CT angiography performed during the study period. Of these patients, 16 (35%; 1.7 ± 2.2 years; range 5 weeks to 5 years) had hand administration of IV contrast agent and 30 (65%; 10.2 ± 4.2 years; range 4-18 years) had mechanical administration of IV contrast agent. All 46 abdominal CT angiography studies were of diagnostic quality based on qualitative evaluation (all ≥3). All abdominal CT angiography studies from both groups showed diagnostic quality of contrast enhancement (>150 HU) at both the celiac axis and the inferior mesenteric artery (IMA) levels. The contrast enhancement of the abdominal aorta was not significantly different between the IV contrast administration methods at either the celiac axis level (360 ± 158 vs. 353 ± 116, P = 0.24) or the IMA level (340 ± 140 vs. 351 ± 90, P = 0.27), adjusting for age.

CONCLUSION

Diagnostic-quality abdominal CT angiography can be achieved using hand administration of IV contrast agent in infants and young children (≤5 years).

Diagnostic and medical strategy for renovascular hypertension: report from a monocentric pediatric cohort

Renovascular hypertension accounts for 5-10 % of hypertension cases in children; there is currently no consensus on treatment. Here, we report on our clinical experience with this disease and outline the different pathways in which to investigate it. We report retrospectively on ten children diagnosed with renovascular hypertension at the University Hospital of Nantes from 2001 to 2012. The main findings were obtained by fortuitous screening of children aged 2 months to 14 years old with neurofibromatosis (n = 2) and fibromuscular dysplasia (n = 8). The hypertension was always severe yet asymptomatic. Lesions were complicated in nine out of ten cases and included bilateral, multiple, mid-aortic syndrome and aneurysm. Doppler ultrasound associated with computed tomography allowed for a precise diagnosis in seven out of ten cases. Where ambiguities persisted, they were highlighted by arteriography, the gold standard investigation. Medical treatment was insufficient, leading to invasive procedures in nine out of ten children: 2 nephrectomies, 2 autotransplantations, and 21 repetitive percutaneous transluminal angioplasties. After invasive procedures, blood pressure control improved in four cases and was resolved in three.

CONCLUSION

Arteriography remains to be the gold standard technique for renovascular hypertension in children and can be combined with angioplasty when medical treatment is rendered obsolete. The role of computed tomography is controversial. Despite the heterogeneity of the children studied, we present a general medical and therapeutic management pathway for the treatment of this disease.