Angiography In Children Research Articles

Tracheobronchial abnormalities on computed tomography angiography in children with congenital heart disease.

To evaluate the assortment of tracheobronchial abnormalities on computed tomography angiography (CTA) in children with congenital heart disease (CHD). In this study approved by the Institute ethics committee, CTA studies of 182 children (age range: 2 days-8 years) with CHD, performed from July 2021 to March 2023 were analyzed. Two pediatric radiologists independently assessed the tracheobronchial airways (from the trachea to lobar bronchi) for developmental and branching anomalies and airway compromise (narrowing). In cases which demonstrated airway compromise, the extent and the cause of airway narrowing were evaluated, and the etiology were divided into extrinsic and intrinsic causes. Interobserver agreement between the two radiologists was calculated using kappa statistics. One hundred children demonstrated normal airway anatomy and no luminal narrowing. Airway narrowing was observed in 63 (34.6%) children (κ: 0.954), and developmental airway anomalies were seen in 32 (17.5%) children (κ: 0.935). Of the 63 children with airway narrowing, 47 (25.8%) children had extrinsic cause for narrowing, 11 (6%) children had intrinsic causes for narrowing, and 5 (2.7%) children had both intrinsic and extrinsic causes attributing to airway compromise. Significant airway narrowing (>50% reduction) was seen in 35 (19.2%) children (κ: 0.945). Tracheobronchial airway abnormalities are frequently associated in children with CHD and need to be appraised preoperatively. Cross-sectional imaging with CTA provides excellent information on tracheobronchial airway anatomy and caliber as well as delineates the possible etiology of airway narrowing, thus accurately diagnosing airway anomalies.

Radiation dose analysis of computed tomography coronary angiography in Children with Kawasaki disease.

There is evolving role of computed tomography coronary angiography (CTCA) in non-invasive evaluation of coronary artery abnormalities in children with Kawasaki disease (KD). Despite this, there is lack of data on radiation dose in this group of children undergoing CTCA. To audit the radiation dose of CTCA in children with KD. Study (December 2013-February 2018) was performed on dual source CT scanner using adaptive prospective electrocardiography-triggering. The dose length product (DLP in milligray-centimeters-mGy.cm) was recorded. Effective radiation dose (millisieverts-mSv) was calculated by applying appropriate age adjusted conversion factors as per recommendations of International Commission on Radiological Protection. Radiation dose was compared across the groups (0-1, 1-5, 5-10, and > 10 years). Eighty-five children (71 boys, 14 girls) with KD underwent CTCA. The median age was 5 years (range, 2 mo-11 years). Median DLP and effective dose was 21 mGy.cm, interquartile ranges (IQR) = 15 (13, 28) and 0.83 mSv, IQR = 0.33 (0.68, 1.01) respectively. Mean DLP increased significantly across the age groups. Mean effective dose in infants (0.63 mSv) was significantly lower than the other age groups (1-5 years 0.85 mSv, 5-10 years 1.04 mSv, and > 10 years 1.38 mSv) (P < 0.05). There was no significant difference in the effective dose between the other groups of children. All the CTCA studies were of diagnostic quality. No child required a repeat examination. CTCA is feasible with submillisievert radiation dose in most children with KD. Thus, CTCA has the potential to be an important adjunctive imaging modality in children with KD.

OCT-Angiography Findings in Children with Anisometropic Amblyopia.

The purpose of this prospective study is to show findings of OCT angiography in children with anisometropic amblyopia with a statistically significant difference, regardless of the type of refractive disorder, between the amblyopic and the fellow eye. This research aimed to establish whether there is a difference in vascular density [VD] and size of the foveal avascular zone [FAZ] in the superficial capillary plexus [SCP]. All children between 9 and 18 years of age who were treated at the Outpatient Clinic for Orthoptics and Pleoptics of the Department of Ophthalmology, University Medical Centre Maribor from January 2020 to December 2022 due to unilateral anisometric amblyopia were enrolled in our study. Fourteen children met the criteria. Cirrus 5000 high-resolution OCT with AngioPlex OCT angiography was used to analyze the size of the FAZ and VD in the SCP and TCS. The paired t-test or Wilcox signed-rank test [p < 0.05] was used for statistical analysis of each parameter between the amblyopic and fellow eye. Mean child age was 13 years ± 2.9 and ranged from 9 to 18 years. Most of the children [85.7%] were boys. The VD of the SCP did not show statistically significant differences between the visually impaired and control eyes [p = 0.328]. The comparison of the FAZ area between the two eyes was also not statistically significant [p < 0.808]. There was also no statistically significant difference in central macular thickness [TCS] [p < 0.291]. Our research results show no statistically significant differences in the VD and the FAZ of the SCP, and in the TCS between the amblyopic and fellow eye in children with unilateral anisometropic amblyopia. Our research did not confirm the results of certain previous studies in which a lower density of the capillary network was present in the visually impaired eye. Further studies with more children are necessary to confirm our results.

Macular superficial vascular density on optical coherence tomography angiography in children with unilateral anisometropic and bilateral hyperopic amblyopia

We analyzed whether macular superficial vascular density (SVD) and foveal vascular zone (FAZ) on optical coherence tomography angiography (OCTA) can distinguish between bilateral ametropic and anisometropic amblyopia. We included 42, 33, and 50 eyes in the bilateral ametropic amblyopia, anisometropic amblyopia, and normal control groups, respectively. Using macular swept-source optical coherence tomography angiography, we measured and analyzed the superficial FAZ areas and five sectoral macular SVDs after magnification correction. The anisometropic amblyopic eye group showed significantly increased foveal SVDs (p < 0.001) and significantly decreased superficial FAZ areas (p < 0.001), compared with the remaining groups. Additionally, the bilateral ametropic amblyopia group had significantly decreased nasal SVDs. SVDs and superficial FAZ areas differed among hyperopic amblyopia subtypes. These findings may reflect vascular distribution differences and macular changes in hyperopic amblyopia subtypes compared with normal eyes.

Macular changes obtained with optical coherence tomography angiography in children with type 1 diabetes mellitus - literature review

Macular changes obtained with optical coherence tomography angiography in children with type 1 diabetes mellitus - literature review

Precision (repeatability and reproducibility) of papillary and peripapillary vascular density measurements using optical coherence tomography angiography in children.

Optical coherence tomography angiography (OCTA) has been widely applied into children, however, few studies have assessed the repeatability and reproducibility of papillary and peripapillary VD in healthy children. To assess the precision of papillary and peripapillary vascular density (VD) measurements using optical coherence tomography angiography (OCTA) and analyze the effects of the signal strength index (SSI) and axial length (AL) on precision estimates. This was a prospective observational study. Seventy-eight children aged 6-16 years underwent 4.5 × 4.5 mm OCTA (RTVue XR Avanti) disc scans: two scans by one examiner (repeatability) and two additional scans by another examiner (reproducibility). Within-subject standard deviation (Sw), test-retest reproducibility (TRT), within-subject coefficient of variation (CoV), intraclass correlation coefficient (ICC), and Bland-Altman analysis were performed. In repeatability measurement, the fluctuation ranges (minimum to maximum) of VD between intraexaminer A/B in Sw, TRT, CoV, and ICC were (1.05-2.17)% / (1.16-2.32)%, (2.9-6)% / (3.21-6.44)%, (1.9-4.47)% / (2.08-5)%, and (0.588-0.783)% / (0.633-0.803)%, respectively. In reproducibility measurement, the fluctuation ranges of VD in Sw, TRT, CoV, and ICC were 1.11-2.13%, 3.07-5.91%, 1.99-4.41%, and 0.644-0.777%, respectively. VD was negatively correlated with SSI in most sectors of the peripapillary (e.g., inferior nasal, temporal inferior, temporal superior, superior temporal, and superior nasal). AL was positively correlated with inferior temporal VD and negatively correlated with superior nasal VD. Optical coherence tomography angiography showed moderate-to-good repeatability and reproducibility for papillary and peripapillary perfusion measurements in healthy children. The SSI value affects most of the peripapillary VD, while AL affects only the temporal inferior and nasal superior peripapillary VD.

Investigation of the optic disc and retinal microvasculature by optical coherence tomography angiography in children with asthma.

To assess the optic disc and retinal microvasculature by optical coherence tomography angiography (OCTA) in asthmatic children. Thirty asthmatic children (asthma group) and 30 control age- and sex-matched healthy controls (control group) were included in this cross-sectional study. The asthma group was then divided into two subgroups according to the presence of inhaled steroid use. Demographic findings were noted. Retinal nerve fiber layer (RNFL) thickness and vessel density in different sections of the retina and optic nerve head were analyzed by OCTA. RNFL thickness for temporal quadrants and flow area for outer retina levels were significantly lower in the asthma group than the control group (72.58 ± 10.99 μm vs 77.73 ± 9.73μm, P = 0.015, and 0.60 ± 0.31mm2 vs. 0.72 ± 0.31mm2, P = 0.047, respectively). However, inside disc vascular densities were significantly higher in the asthma group when compared to controls (55.16% ± 3.71% vs. 52.08% ± 3.79%, P < 0.001). Inside disc vascular densities were also significantly higher, and RNFL thickness for temporal quadrants was significantly lower in the asthmatic patients without steroid use subgroup when compared to others (P < 0.001, P = 0.012, respectively). Lower values of temporal quadrant RNFL, and flow area for outer retina, but higher levels of inside disc vascular density seem to be associated with asthmatic children. OCTA findings in asthmatic children appear to be regardless of inhaled steroid use.

Evaluation of parafoveal and peripapillary vascular densities using optical coherence tomography angiography in children with thalassemia major.

Thalassemia major (TM) is an inherited anaemia caused by faulty haemoglobin synthesis. Reducing serum iron levels using iron chelating agents is an important step in the treatment of TM, and the effects on the eye of both the disease and these agents can be determined by regular eye examination. We evaluated macular and optic nerve vascular densities in children with TM and compared the results with healthy controls using optical coherence tomography angiography (OCTA). This is a prospective study. A total of 30 children with TM and 30 healthy controls were included in the study. The area of the foveal avascular zone (FAZ) and the vascular densities (VD) of the optic nerve head (ONH), radial peripapillary capillary (RPC) and deep and superficial retinal vascular networks were measured using OCTA. A statistically significant decrease in VD was observed in the whole image and the parafovea, superior hemi, superior and inferior parts of the superficial capillary plexus and in the whole image and the superior regions of the deep capillary plexus in the TM patient group compared with the control group (p < 0.05). A significant decrease in VD was also observed in the whole image and the inside disc, peripapillary, nasal, inferonasal and temporal regions of the ONH and in the whole image and the inside disc, peripapillary and inferonasal regions of the RPC network in patients with TM (p < 0.05). A significant positive correlation was observed between both serum ferritin levels and deferasirox dosage, on one hand, and both the superficial (p = 0.023 and p = 0.002, respectively) and deep FAZs (p = 0.015 and p = 0.045, respectively), on the other hand. A negative correlation was also found between the deferasirox dosage and the VDs of the superficial (p = 0.010) and deep (p = 0.001) foveal plexuses. Retinal VD and FAZ are affected in patients with TM. OCTA, which can noninvasively measure retinal VD in patients with TM, may be a useful tool for the early detection of retinal microvascular changes that may occur during the course of the disease.

Evaluation of macular microvascular structure with optical coherence tomography angiography in children with history of treatment for retinopathy of prematurity.

To compare macula vascular parameters in optical coherence tomography angiography (OCTA) of children with history of retinopathy of prematurity (ROP) who were treated with laser photocoagulation (LPC) or intravitreal Bevacizumab therapy. Forty eyes of 28 ROP children treated with LPC and 36 eyes of 22 ROP children treated with intravitreal Bevacizumab and 40 eyes of 40 age-gender matched term children were included the study. Capillary plexus densities in macula, FAZ parameters, outer retina and choriocapillaris flow rates, and central foveal thickness were measured. Foveal superficial and deep capillary plexus densities were found significantly higher in LPC and intravitreal Bevacizumab injection (IBI) groups compared to control group. FAZ area was found significantly lower in LPC and IBI groups compared to control group (p ‹ 0.001). Higher foveal superficial capillary plexus density, higher central foveal thickness, and lower FAZ area were found to be associated with poorer visual acuity in correlation analysis (p ‹ 0.05). In IBI group, earlier anti-VEGF therapy was found to be associated with lower foveal superficial capillary plexus density. Microvascular characteristics such as FAZ area and capillary plexus densities of macula are deteriorated in ROP. There is no significant difference between the treatment alternatives of ROP in terms of macular microvascular parameters.

Oral Fluorescein Angiography with Ultra-Wide-Field Scanning Laser Ophthalmoscopy in Pediatric Patients Precis: Oral Fluorescein Angiography in Children.

Aims: To investigate the success rate of oral fluorescein angiography (oral FA) in children with ultrawide scanning laser ophthalmoscopy (SLO) system and whether it can provide images of sufficient quality compared with intravenous FA (IVFA). Methods: In this comparative case series study, a series of 40 consecutive pediatric patients of the age of 3–18 with retinal vascular diseases, in whom FA was needed for the diagnosis or treatment, were enrolled in this study. IVFA and oral FA were performed within one week and images were obtained with the SLO system. The image quality was scored blindly and compared based on: (I) visualization of the branch retinal vessel, (II) the foveal avascular zone (FAZ), and (III) clinically important findings, such as the presence of microaneurysms, neovascularization, leakage, or significant nonperfusion. All these were scored using a three-point scale. Results: In preschoolers (three to six years), all 19 children complete oral FA (100%), while only 7 (36.84%) complete IVFA (p < 0.0001). With the SLO system, the branch retinal vessels were well visualized both in oral and IV FA (all images were two scores). The visualization of FAZ was similar between oral and IV FA (p = 0.8972). The clinically important findings were well visualized in both groups (p > 0.9999). The overall image quality was similar between the two groups (p = 0.2500). Conclusion: Oral FA is more acceptable to preschoolers than IVFA owing to the needle-free procedure. With the SLO system, oral FA provided high-quality angiograms similar to IVFA. Oral FA is an effective alternative to IVFA and may be considered the first option for FA in pediatric patients, especially in preschoolers.

Ultra-widefield oral fluorescein angiography in children

Ultra-widefield fluorescein angiography (UWFA) has been used with intravenous fluorescein, largely in adults. We describe our experience using an oral UWFA protocol in a pediatric population.

Optical coherence tomographic angiography in children with anisometropic amblyopia

ObjectivesTo observe and compare the difference in retinal perfusion using optical coherence tomography angiography (OCTA) between anisometropic amblyopia in children and fellow eyes as well as age-matched controls.MethodsA total of 16 children with anisometropic amblyopia and 19 age-matched healthy subjects were enrolled. All participants underwent OCTA examination, with 3 mm × 3 mm and 6 mm × 6 mm scans in the macular region. Perfusion parameters of the superficial retinal layer were measured by built-in software, including the macular foveal avascular zone (FAZ) area, perimeter and circularity, as well as the vessel length density (VLD) and perfusion density (PD) of the foveal, parafoveal and perifoveal regions.ResultsAmong the 16 patients with anisometropic amblyopia, the FAZ area was significantly higher in diseased eyes (P = 0.027) than in fellow eyes. The VLD and PD of the foveal average and the VLD of the nasal quadrant of the perifoveal region in anisometropic amblyopic eyes were significantly lower than those in fellow eyes (P < 0.05). The VLD of the parafoveal average, the superior, temporal, inferior and nasal quadrants of the parafoveal region, and the nasal quadrant of the perifoveal region in anisometropic amblyopic eyes were significantly lower than those in healthy controls (P < 0.05). The PD of the parafoveal average, and the inferior quadrant of the parafoveal region in anisometropic amblyopic eyes were significantly lower than those in healthy controls (P < 0.05). The VLD of the parafoveal average, the superior, inferior and nasal quadrants of the parafoveal region, and the nasal quadrant of the perifoveal region in fellow eyes were significantly lower than those in healthy controls (P < 0.05). The PD of the parafoveal average, and the inferior quadrant of the parafoveal region in fellow eyes were significantly lower than those in healthy controls (P < 0.05).ConclusionsThe macular vessel density of the superficial capillary plexus is lower in anisometropic amblyopic children than in age-matched healthy children. Compared with the fellow eye, the perfusion of the amblyopic eye in children with anisometropic amblyopia also decreases.

The Use of an Inflatable Adhesive External Compression Device for Maintenance of Hemostasis following Angiography in Children

PurposeTo assess the safety and efficacy of the posthemostasis use of an inflatable adhesive external compression device (SafeGuard) following angiography in children performed under general anesthesia. Materials and MethodsMedical records of 74 children (43 females) with a mean age of 8.9 years (range, 0.4–18.0 years) and mean weight of 44.0 kg (range, 7.3–115.7 kg) in whom an inflatable adhesive external compression device was used for maintaining hemostasis following angiography under general anesthesia were retrospectively reviewed. After establishing hemostasis with manual compression, the device was applied and inflated over the arteriotomy. The patients were assessed for access-related adverse events in the recovery unit and during postprocedural follow-up. ResultsThe inflatable adhesive external compression device was utilized to maintain hemostasis following 181 angiography procedures. The mean length of the procedure was 396 minutes. The common femoral artery (n = 170, 93.9%) was the most common access, using 4–5-F vascular sheath (n = 118, 65.2%) or 3–5-F sheathless (n = 8, 12.7%) catheters. The mean time to deflation was 93 minutes. There were no adverse events other than minor bleeding from the arteriotomy after deflation (n = 2, 1.1%) and early deflation of the device because of pain (n = 1, <1%). Follow-up ultrasonography (n = 109 procedures, 60.2% at a mean follow-up of 2.2 years) demonstrated patency of the access artery. ConclusionsThe use of an inflatable adhesive external compression device following angiography in children to maintain hemostasis during the emergence phase of anesthesia and recovery period is safe and effective. The use of this simple device may reduce the need for postprocedural sedation and facilitate early discharge.

Normal Distance Measurements Between the Origins of the Major Branches of the Abdominal Aorta on Computed Tomography Angiography in Children

Normal Distance Measurements Between the Origins of the Major Branches of the Abdominal Aorta on Computed Tomography Angiography in Children

Brain Magnetic Resonance Imaging and Angiography in Children with Sickle Cell Anaemia in Uganda in a Cross-Sectional Sample

Children with sickle cell anaemia (SCA) are highly susceptible to cerebrovascular injury. We performed brain magnetic resonance imaging and angiography (MRI-MRA) in Ugandan children with SCA to identify structural cerebrovascular abnormalities and examine their relationship to standardized clinical assessments. A sub-sample (n=81) was selected from a cross-sectional study of children attending SCA clinic, including 52 (64.2%) with and 29 (35.8%) without clinically detected abnormalities. Clinical evaluation included assessment for prior stroke, cognitive testing and cerebral arterial transcranial doppler (TCD) flow velocity. MRI-MRA scans were interpreted by at least two neuroradiologists. Mean age was 6.5±2.7 years, with 39 (48.1%) female. Mean haemoglobin was 7.3±0.9 g/dl. Overall, 13 (16.0%) were malnourished. Infarcts and/or stenoses were detected in 55 (67.9%) participants, with stenoses primarily in the anterior circulation. Infarcts were seen in those with normal 17/29 (58.6%) or abnormal 34/52 (65.4%) clinical testing (p=0.181). Neither abnormal MRI nor MRA was associated with age, sex, haemoglobin, or malnutrition. Abnormal MRA was highly associated with infarcts (p<0.0001). Participants with abnormal imaging had two-fold higher proportion of stroke on exam and/or impaired cognition. Stroke on exam was strongly associated with an imaging abnormality after adjusting for age, sex, malnutrition, and haemoglobin (OR 11.8, 95%CI 1.87-74.2). Over half of these SCA children had cerebrovascular infarcts and/or arterial stenoses. Cerebrovascular disease was frequently undetectable by clinical assessments. While rarely available in under-resourced settings, MRI-MRA brain imaging is an important tool for defining SCA cerebrovascular disease and for assessing impact of clinical intervention trials.

Safety of pediatric cerebral angiography.

Catheter-based cerebral angiography is commonly used for neurovascular diagnosis in children. In this work, the authors aimed to quantify the complication rate of cerebral angiography in children, characterize these complications, and identify risk factors for complications. Relevant clinical data were retrospectively obtained for 587 consecutive cerebral angiography procedures performed in 390 children from March 2002 to March 2020. Complications were categorized as neurological or nonneurological, and severity was graded using a standard schema. Incidences of complications were reported as point estimates. Associations between risk factors and complications were characterized in univariate analysis using the two-tailed Fisher exact test and in multivariate analysis using multiple logistic regression with bidirectional elimination based on the Akaike information criterion. In both univariate and multivariate analyses, statistical significance was corrected for multiple comparisons using the Benjamini-Hochberg method. Complications occurred in 6.5% of procedures, including neurological complications in 1.9% and nonneurological complications in 4.8%. Permanent deficits occurred in only 0.2% of cases. Overall, 0.5% of procedures resulted in major complications, while 6.0% resulted in minor complications. Female sex and a history of hypertension or ischemic stroke were associated with an increased risk of complications, while femoral artery access was associated with a decreased risk of complications. Pediatric cerebral angiography was shown to have a low rate of major or permanent complications. Children who were female and those with a history of hypertension or ischemic stroke were shown to be at higher risk of complications, while the use of femoral access carried a lower risk of complications.

Non-cardiovascular findings on chest CT angiography in children with congenital heart disease: How important are they?

BackgroundThere are only a few publications about the non-cardiovascular findings in children with congenital heart diseases explored by chest CT angiography. The purpose of our study is to evaluate the prevalence of non-cardiovascular findings on chest CT angiographies in children with congenital heart disease and to raise awareness about their importance among the radiologists.MethodsWe retrospectively reviewed the 272 chest CT angiographies performed in our pediatric radiology department between January 2017 and march 2021 and extracted the data of the 180 patients positive for a congenital heart disease. Then from that pool, we sorted out the non-cardiovascular findings into significant and non-significant in regard of their relevance or not in the patient’s management.ResultsNon-cardiovascular lesions were found in 58% (105/180) of our patients, and 49% (88/180) of them presented at least one significant non-cardiac lesion. Lung and airways abnormalities were found in 41% (74/180) of the cases, representing the majority of the non-cardiovascular findings. Syndromic associations were found in 17% (28/180) of our patients, including 14 cases of heterotaxic syndrome.ConclusionNon-cardiovascular findings are common in children with congenital heart disease. Reporting these associated lesions is a requisite for an optimal therapeutic management of these children. Radiologists should never forget that a Chest CT angiography in children is first and foremost a chest CT.

Intraoperative OCT Angiography in Children with Incontinentia Pigmenti

OCT angiography detects vascular abnormalities in incontinentia pigmenti not apparent on fluorescein angiography, and therefore may serve as helpful tool to detect early macular ischemia in children during examination under anesthesia.

Coronary computed tomography angiography in children

Imaging the coronary arteries of children, with their faster heart rates, small vessel size and common inability to lie still or breath-hold, has been a major challenge. With numerous advances in technology, CT examinations can now be performed quickly, often with children free-breathing and with much lower radiation doses than previously. This has led to increased use in children. Care must be taken with technique and choice of electrocardiogram (ECG)-gating technique to obtain adequate imaging for a diagnosis while keeping radiation dose as low as reasonably achievable (ALARA). In this paper, we discuss techniques and tips for CT imaging of the coronary arteries in children, including use of dual-source- and ultrawide-detector CT scanners.

The utility of magnetic resonance angiography in children with nutcracker syndrome

Background/aim The presented study aimed to evaluate the utility of magnetic resonance angiography (MRA) in the pediatric population with nutcracker syndrome.Materials and methods Patients with suggestive clinical symptoms and laboratory findings and got the diagnosis of nutcracker syndrome with Doppler ultrasonography between January 2011–2019 were included in the study. In addition, children who had renal MRA due to hypertension were evaluated as the control group. MRA images of all patients were examined retrospectively by three radiologists at different levels of experience, and the superior mesenteric artery angle, aorta-mesenteric distance, left renal vein diameter both in the regions of aorta-mesenteric, and renal hilum were recorded. ResultsForty-five patients diagnosed with nutcracker syndrome were included in the study. The mean age of patients was 12 (4–16) and 30 (67%) were female. As the control group, 25 patients with hypertension who had MRA were included and they had a mean age of 12 (1–18) and 19 (76%) were male. The mean superior mesenteric artery angle was 26.5 ° (16–73 ± 12) in the patient group and 57.8 ° (25–139, ± 33) in the control group (p < 0.001); the mean aorta-mesenteric distance was 3.3 mm (1.7–6.5, ± 1.1) in the patient group and 8 mm (3.4–32, ± 5.9) in the control group (p < 0.001). MRA measurements of three radiologists were consistent with each other.ConclusionMRA imaging can be applied as an alternative diagnostic method for Doppler ultrasonography and multidetector CT examinations by radiologists with different experience levels in pediatric patients with nutcracker syndrome.