Mi-Jung Lee

Biliary Atresia: Color Doppler US Findings in Neonates and Infants

PURPOSEnTo describe color Doppler ultrasonographic (US) findings in livers of neonates with biliary atresia (BA) and to compare them with US findings in livers of neonates with non-BA and control subjects.nnnMATERIALS AND METHODSnInstitutional review board approval was obtained; acquisition of informed consent was exempted. US and color Doppler US findings were retrospectively reviewed in 64 patients with neonatal cholestasis and 19 control subjects. BA and non-BA were confirmed in 29 and 35 patients, respectively. Three pediatric radiologists assessed US and color Doppler US images, independently documented their findings, and resolved discrepancies by consensus. Triangular cord (TC) sign, gallbladder length, and hepatic artery and portal vein diameters were evaluated on US images. The presence of hepatic subcapsular flow was evaluated on color Doppler US images. Diagnostic value of TC sign and hepatic subcapsular flow in the diagnosis of BA were evaluated. Significance of hepatic artery and portal vein diameters in each group was assessed.nnnRESULTSnIn the diagnosis of BA, sensitivity and specificity of the TC sign on US images were 62% and 100%, respectively. On color Doppler US images, hepatic subcapsular flow was detected in all patients with BA and in five patients with non-BA. At the first review, there was a discrepancy between radiologists in interpretation of hepatic subcapsular flow in patients with non-BA. However, consensus was reached at the second review. There was no hepatic subcapsular flow in control subjects. Sensitivity and specificity of hepatic subcapsular flow on color Doppler US images were 100% and 80%-86%, respectively, on the basis of individual interpretations of reviewers. Sensitivity and specificity of hepatic subcapsular flow on color Doppler US images were 100% and 86%, respectively, on the basis of consensus reading. Mean diameter of the hepatic artery in patients with BA (2.1 mm +/- 0.7 [standard deviation]) was significantly larger than that in patients with non-BA (1.5 mm +/- 0.4, P < .001) and control subjects (1.5 mm +/- 0.4, P = .001).nnnCONCLUSIONnThe presence of hepatic subcapsular flow is useful for differentiating between BA and other causes of neonatal jaundice.

Age-related changes in liver, kidney, and spleen stiffness in healthy children measured with acoustic radiation force impulse imaging

OBJECTIVESnTo evaluate the feasibility and age-related changes of shear wave velocity (SWV) in normal livers, kidneys, and spleens of children using acoustic radiation force impulse (ARFI) imaging.nnnMATERIALS AND METHODSnHealthy pediatric volunteers prospectively underwent abdominal ultrasonography and ARFI. The subjects were divided into three groups according to age: group 1: <5 years old; group 2: 5-10 years old; and group 3: >10 years old. The SWV was measured using a 4-9 MHz linear probe for group 1 and a 1-4 MHz convex probe for groups 2 and 3. Three valid SWV measurements were acquired for each organ.nnnRESULTSnTwo hundred and two children (92 male, 110 female) with an average age of 8.1 years (± 4.7) were included in this study and had a successful measurement rate of 97% (196/202). The mean SWVs were 1.12 m/s for the liver, 2.19 m/s for the right kidney, 2.33 m/s for the left kidney, and 2.25 m/s for the spleen. The SWVs for the right and left kidneys, and the spleen showed age-related changes in all children (p<0.001). And the SWVs for the kidneys increased with age in group 1, and those for the liver changed with age in group 3.nnnCONCLUSIONSnARFI measurements are feasible for solid abdominal organs in children using high or low frequency probes. The mean ARFI SWV for the kidneys increased according to age in children less than 5 years of age and in the liver, it changed with age in children over 10.

Radiation dose reduction with the adaptive statistical iterative reconstruction (ASIR) technique for chest CT in children: an intra-individual comparison.

OBJECTIVEnTo retrospectively compare radiation dose and image quality of pediatric chest CT using a routine dose protocol reconstructed with filtered back projection (FBP) (the Routine study) and a low-dose protocol with 50% adaptive statistical iterative reconstruction (ASIR) (the ASIR study).nnnMATERIALS AND METHODSnWe retrospectively reviewed chest CT performed in pediatric patients who underwent both the Routine study and the ASIR study on different days between January 2010 and August 2011. Volume CT dose indices (CTDIvol), dose length products (DLP), and effective doses were obtained to estimate radiation dose. The image quality was evaluated objectively as noise measured in the descending aorta and paraspinal muscle, and subjectively by three radiologists for noise, sharpness, artifacts, and diagnostic acceptability using a four-point scale. The paired Students t-test and the Wilcoxon signed-rank test were used for statistical analysis.nnnRESULTSnTwenty-six patients (M:F=13:13, mean age 11.7) were enrolled. The ASIR studies showed 60.3%, 56.2%, and 55.2% reductions in CTDIvol (from 18.73 to 7.43 mGy, P<0.001), DLP (from 307.42 to 134.51 mGy×cm, P<0.001), and effective dose (from 4.12 to 1.84 mSv, P<0.001), respectively, compared with the Routine studies. The objective noise was higher in the paraspinal muscle of the ASIR studies (20.81 vs. 16.67, P=0.004), but was not different in the aorta (18.23 vs. 18.72, P=0.726). The subjective image quality demonstrated no difference between the two studies.nnnCONCLUSIONnA low-dose protocol with 50% ASIR allows radiation dose reduction in pediatric chest CT by more than 55% while maintaining image quality.

Shear wave velocity measurements using acoustic radiation force impulse in young children with normal kidneys versus hydronephrotic kidneys

Purpose: To measure shear wave velocities (SWVs) by acoustic radiation force impulse (ARFI) ultrasound elastography in normal kidneys and in hydronephrotic kidneys in young children and to compare SWVs between the hydronephrosis grades. Methods: This study was approved by an institutional review board, and informed consent was obtained from the parents of all the children included. Children under the age of 24 months were prospectively enrolled. Hydronephrosis grade was evaluated on ultrasonography, and three valid ARFI measurements were attempted using a high-frequency transducer for both kidneys. Hydronephrosis was graded from 0 to 4, and high-grade hydronephrosis was defined as grades 3 and 4. Results: Fifty-one children underwent ARFI measurements, and three valid measurements for both kidneys were obtained in 96% (49/51) of the patients. Nineteen children (38.8%) had no hydronephrosis. Twenty-three children (46.9%) had unilateral hydronephrosis, and seven children (14.3%) had bilateral hydronephrosis. Seven children had ureteropelvic junction obstruction (UPJO). Median SWVs in kidneys with high-grade hydronephrosis (2.02 m/sec) were higher than those in normal kidneys (1.75 m/sec; P=0.027). However, the presence of UPJO did not influence the median SWVs in hydronephrotic kidneys (P=0.362). Conclusion: Obtaining ARFI measurements of the kidney is feasible in young children with median SWVs of 1.75 m/sec in normal kidneys. Median SWVs increased in high-grade hydronephrotic kidneys but were not different between hydronephrotic kidneys with and without UPJO.

Comparison of the reliability of two hydronephrosis grading systems: The Society for Foetal Urology grading system vs. the Onen grading system

AIMnTo compare the reliability of the conventional ultrasonography grading system for hydronephrosis as suggested by the Society for Fetal Urology (SFU) in 1993 and that developed by Onen in 2007.nnnMATERIALS AND METHODSnOne hundred and eighty kidneys in 90 paediatric patients were assessed by four radiologists using each of the two grading systems twice. The SFU system was graded 0-4 (0xa0=xa0no hydronephrosis; 1xa0=xa0visualized only renal pelvis; 2xa0=xa0plus a few caliceal dilatation; 3xa0=xa0all calyceal dilatation; 4xa0=xa0plus parenchymal thinning). The Onen system was graded 0-4 (0xa0=xa0no hydronephrosis; 1xa0=xa0only renal pelvic dilatation; 2xa0=xa0plus caliceal dilatation; 3xa0=xa0plus <50% renal parenchymal loss; 4xa0=xa0plus >50% renal parenchymal loss). Cohens kappa statistic was used to estimate intra- and interobserver agreement. The weighted least-squares approach was used to compare the intra-observer agreement, and bootstrapping was used to compare the interobserver agreement between the two systems.nnnRESULTSnIntra-observer agreement was substantial to almost perfect in both the SFU (κxa00.79-0.95) and the Onen (κ 0.66-0.97) grading system without difference. The overall interobserver agreement was substantial in both the SFU (κ 0.61-0.68) and the Onen (κxa00.66-0.76) grading system. However, interobserver agreement was fair to moderate for SFU grades 1 and 2 and Onen grades 2 and 3.nnnCONCLUSIONnBoth the SFU and Onen grading system are reliable with good intra- and interobserver agreement. However, decreased interobserver agreement was demonstrated for SFU grades 1 and 2 and Onen grades 2 and 3.

Sonographic appearance of intrathyroid ectopic thymus in children.

The aim of this study is to report the common location of intrathyroid ectopic thymus and describe the corresponding sonographic appearances in children.

Comparison of shear wave velocities on ultrasound elastography between different machines, transducers, and acquisition depths: a phantom study.

AbstractObjectivesTo investigate consistency in shear wave velocities (SWVs) on ultrasound elastography using different machines, transducers and acquisition depths.MethodsThe SWVs were measured using an elasticity phantom with a Young’s modulus of 16.9 kPa, with three recently introduced ultrasound elastography machines (A, B and C from different vendors) and two transducers (low and high frequencies) at four depths (2, 3, 4 and 5xa0cm). Mean SWVs from 15 measurements and coefficient of variations (CVs) were compared between three machines, two transducers and four acquisition depths.ResultsThe SWVs using the high frequency transducer were not acquired at 5xa0cm depth in machine B, and a high frequency transducer was not available in machine C. The mean SWVs in the three machines were different (pu2009≤u20090.002). The CVs were 0–0.09 in three machines. The mean SWVs between the two transducers were different (pu2009<u20090.001) except at 4 and 5xa0cm depths in machine A. The SWVs were affected by the acquisition depths in all conditions (pu2009<u20090.001).ConclusionThere is considerable difference in SWVs on ultrasound elastography depending on different machines, transducers and acquisition depths. Caution is needed when using the cutoff values of SWVs in different conditions.Key Points• The shear wave velocities (SWVs) are different between different ultrasound elastography machinesn • The SWVs are also different between different transducers and acquisition depthsn • Caution is needed when using the cutoff SWVs measured under different conditions

Superb microvascular imaging for the detection of parenchymal perfusion in normal and undescended testes in young children

OBJECTIVESnTo compare the detectability of perfusion difference between normal and undescended testes (UDT) in young children using conventional Power Doppler Imaging (PDI) and Superb Microvascular Imaging (SMI).nnnMETHODSnWe prospectively performed testicular ultrasonography including PDI and SMI for the evaluation of microvascular flow in young children. Microvascular flow was categorized into four grades (grade 0-4). Statistical analysis was performed to compare the differences between undescended and normal testes.nnnRESULTSnWe imaged 40 testes from 20 boys (age, 2-29 months). Testes sizes and volumes were similar between the 29 normal and 11 UDT. PDI demonstrated low grade flow in most normal (19/29) and UDT (11/11) without difference (P=0.130). However, SMI detected differences in flow grades between normal and UDT (P<0.001). In univariate analysis, age (odds ratio [OR], 0.829; P=0.012) and low grade flow on SMI (OR of grade 0, 51.886 with P<0.001 and OR of grade 1, 14.29 with P=0.017) were associated with UDT. These parameters were also significant in multivariate analysis with larger area under the curve, compared with the results using PDI (0.892 vs. 0.726, P=0.002).nnnCONCLUSIONSnSMI can detect perfusion difference between normal and UDT in young children better than PDI.

Radiation dose reduction and image quality in pediatric abdominal CT with kVp and mAs modulation and an iterative reconstruction technique

OBJECTIVEnThe objective of this study was to compare the radiation dose and image quality of pediatric abdominal computed tomography (CT) using a protocol reconstructed with filtered back projection (FBP) and a protocol with both kVp and mAs modulation and sinogram-affirmed iterative reconstruction (SAFIRE).nnnMATERIALS AND METHODSnWe retrospectively reviewed pediatric abdominal CT examinations performed with both kVp and mAs modulation. These raw data were reconstructed with SAFIRE at different strengths from 2 to 4 (SAFIRE groups 2-4). Another set of age/sex-matched pediatric abdominal CT examinations were also reviewed, which were performed during the same period with only mAs modulation and FBP (control group). The radiation dose and image quality were compared between groups. The image quality was objectively evaluated as the noise measured in the liver, aorta, and spleen at the level of the main portal vein and the image quality was subjectively reviewed by two radiologists for diagnostic acceptability using a four-point scale (0: unacceptable; 1: worse than the control group, but acceptable; 2: comparable with the control group; and 3: better than the control group). An independent t test was used in order to compare the radiation dose. An independent t test with Bonferroni correction and generalized estimating equations were used for the comparison of the objective and subjective image quality, respectively.nnnRESULTSnTwenty-nine patients (M:F=19:10; mean age, 10.0 years) were enrolled in each group. The SAFIRE group, using the size-specific dose estimates calculation method showed a 64.2% radiation dose reduction (from 8.1 to 2.9 mGy, P<.05), compared with the results of the control group. The objective image noise of the SAFIRE groups 2 and 3 was comparable to that of the control group. The subjective image quality was the best in SAFIRE group 3 [odds ratio (OR) 3.015, P<.001 when comparing to SAFIRE group 0; OR 1.513, P<.001 when comparing to SAFIRE group 2].nnnCONCLUSIONSnImage acquisition with both kVp and mAs modulation and iterative reconstruction using SAFIRE with strength 3 can preserve the objective and subjective image quality of pediatric abdominal CT scans with less than half the radiation dose.

Spina bifida occulta: Not to be overlooked in children with nocturnal enuresis

Previous reports have suggested that the incidence of spina bifida occulta in patients with nocturnal enuresis is higher than in the general population. However, the effect of spina bifida occulta on the response to nocturnal enuresis treatment is controversial. The purpose of this study was to investigate the relationship between spina bifida occulta and response to treatment of nocturnal enuresis.