Advanced Kidney Volume Measurement Method Using Ultrasonography with Artificial Intelligence-Based Hybrid Learning in Children.

In this study, we aimed to develop a new automated method for kidney volume measurement in children using ultrasonography (US) with image pre-processing and hybrid learning and to formulate an equation to calculate the expected kidney volume. The volumes of 282 kidneys (141 subjects, <19 years old) with normal function and structure were measured using US. The volumes of 58 kidneys in 29 subjects who underwent US and computed tomography (CT) were determined by image segmentation and compared to those calculated by the conventional ellipsoidal method and CT using intraclass correlation coefficients (ICCs). An expected kidney volume equation was developed using multivariate regression analysis. Manual image segmentation was automated using hybrid learning to calculate the kidney volume. The ICCs for volume determined by image segmentation and ellipsoidal method were significantly different, while that for volume calculated by hybrid learning was significantly higher than that for ellipsoidal method. Volume determined by image segmentation was significantly correlated with weight, body surface area, and height. Expected kidney volume was calculated as (2.22 × weight (kg) + 0.252 × height (cm) + 5.138). This method will be valuable in establishing an age-matched normal kidney growth chart through the accumulation and analysis of large-scale data.

Ultrasound Feature-Based Diagnostic Model Focusing on the "Submarine Sign" for Epidermal Cysts among Superficial Soft Tissue Lesions.

OBJECTIVE: To develop a diagnostic model for superficial soft tissue lesions to differentiate epidermal cyst (EC) from other lesions based on ultrasound (US) features. MATERIALS AND METHODS: This retrospective study included 205 patients who had undergone US examinations for superficial soft tissue lesions and subsequent surgical excision. The study population was divided into the derivation set (n = 112) and validation set (n = 93) according to the imaging date. The following US features were analyzed to determine those that could discriminate EC from other lesions: more-than-half-depth involvement of the dermal layer, "submarine sign" (focal projection of the hypoechoic portion to the epidermis), posterior acoustic enhancement, posterior wall enhancement, morphology, shape, echogenicity, vascularity, and perilesional fat change. Using multivariable logistic regression, a diagnostic model was constructed and visualized as a nomogram. The performance of the diagnostic model was assessed by calculating the area under the curve (AUC) of the receiver operating characteristic curve and calibration plot in both the derivation and validation sets. RESULTS: More-than-half-depth involvement of the dermal layer (odds ratio [OR] = 3.35; p = 0.051), "submarine sign" (OR = 12.2; p < 0.001), and morphology (OR = 5.44; p = 0.002) were features that outweighed the others when diagnosing EC. The diagnostic model based on these features showed good discrimination ability in both the derivation set (AUC = 0.888, 95% confidence interval [95% CI] = 0.825-0.950) and validation set (AUC = 0.902, 95% CI = 0.832-0.972). CONCLUSION: More-than-half-depth of involvement of the dermal layer, "submarine sign," and morphology are relatively better US features than the others for diagnosing EC.

Correlation of Serum Biomarkers and Magnetic Resonance Spectroscopy in Monitoring Disease Progression in Patients With Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes Due to mtDNA A3243G Mutation.

Background: Analysis of serum biomarkers and magnetic resonance spectroscopy (MRS) are useful for monitoring disease progression in patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). We evaluated the correlation of serum biomarkers and MRS parameters during changes associated with stroke-like episodes. Methods: In 13 symptomatic MELAS patients carrying the A3243G mutation, we retrospectively obtained 207 voxels from 41 MRS studies, which were divided into three groups according to the temporal association with stroke-like episodes. The MRS NAA/Cr, Cho/Cr, NAA/Cho ratios, the presence of a lactate peak, serum biomarkers, serum lactate level and the pyruvate (Lac/Pyr) ratio were determined. Results: In regions with acute infarcts, the severity of serum Lac/Pyr and that of the MRS lactate peak (P = 0.0007) correlated; serum lactate (P = 0.02), severity of elevated serum lactate (P = 0.04), and serum Lac/Pyr (P = 0.02) correlated weakly. In previously infarcted regions, the severity of the MRS lactate peak and serum Lac/Pyr (P = 0.03), as well as the severity of serum Lac/Pyr (P = 0.02) were weakly correlated. In structurally normal regions, we found a weak to moderate negative correlation between serum lactate and MRS NAA/Cr (P = 0.008), and between the severity of elevated serum lactate and MRS NAA/Cr (P = 0.002) as well as MRS NAA/Cho (P = 0.02). Conclusions: MRS parameters correlate with specific serum biomarkers, and are useful for monitoring changes in brain metabolites, particularly as related to stroke-like episodes.

Percutaneous Transhepatic Biliary Drainage in a Two-Month-Old Infant with Inspissated Bile Syndrome.

Inspissated bile syndrome (IBS) is a relatively rare condition. Many treatment options are available, including medication, surgery, and surgical interventions, such as insertion of cholecystostomy drain, endoscopic retrograde cholangiopancreatography, internal biliary drainage, and percutaneous transhepatic biliary drainage (PTBD). We herein report the first case of IBS that was successfully treated with PTBD in a two-month-old infant in Korea. PTBD was initiated on postnatal day 72. On postnatal day 105, we confirmed complete improvement and successfully removed the catheters. This report suggests that PTBD is a viable and safe treatment option for obstructive jaundice in very young infants.

Visceral fat thickness and its associations with pubertal and metabolic parameters among girls with precocious puberty.

PURPOSE: This study aimed to investigate associations of central obesity with sexual maturation and metabolic parameters in Korean girls with precocious puberty. METHODS: This retrospective study evaluated data from 72 girls under 8 years of age with a chief complaint of early breast development. The patients were categorized as central precocious puberty (CPP) subjects or non-CPP subjects based on their gonadotropin-releasing hormone stimulation test results. Visceral fat thickness (VFT) was measured using ultrasonography and defined as the distance from the linea alba to the aorta. Patient anthropometric, metabolic, and hormonal parameters were also evaluated. RESULTS: Increased VFT was correlated with an earlier onset of thelarche among all study subjects (r=-0.307, P=0.034). Overweight CPP subjects showed higher insulin resistance than normal weight CPP subjects. Insulin resistance was not significantly different between overweight and normal weight non-CPP subjects. VFT was not significantly different between CPP and non-CPP subjects (2.22±0.79 cm vs. 2.74±1.47 cm, P=0.169). However, overweight and obese CPP subjects (body mass index percentile>85%) had lower VFT than non-CPP obese subjects. CONCLUSION: Central obesity, defined using ultrasonography-measured VFT, might be associated with early pubertal development in Korean girls. However, VFT was not higher in CPP than non-CPP patients and was not significantly correlated with insulin resistance. Further longitudinal studies with a larger cohort are needed.

Motion effects on the measurement of stiffness on ultrasound shear wave elastography: a moving liver fibrosis phantom study.

AIMS: To evaluate the differences between shear wave velocities (SWVs) measured with ultrasound elastography during the continuous motion using liver fibrosis phantoms. MATERIALS AND METHODS: Elasticities were measured with convex and linear transducers of supersonic shear wave imaging (SSI) and acoustic radiation force impulse imaging (ARFI) using liver elasticity phantoms (3.0 and 16.9 kPa) at depths of 2, 3, 4, and 5 cm. Motion velocities were 30 and 60 rpm with the phantoms in an upright position on the Orbital shaker. To simulate different directional motion, the phantoms were laid on their side on the shaker. The values between moving and static status were compared, and the number of measurement failure was counted. Results: In SSI, the convex transducer was less affected by motion at 30 rpm with the 3 kPa phantom. In the higher velocity motion and in the higher stiffness phantom, most values from SSI were different comparing with static status, and there was a tendency for elasticity values to increase during movement. In ARFI, there were frequent measurement failures without stable results during the motion. CONCLUSIONS: Motion affected the measurement of elasticity differently in SSI and ARFI, according to the velocity, direction of the motion, and phantom stiffness. The convex transducer of SSI was less affected by motion in lower velocity motion and when using normal liver stiffness phantom.

Interobserver and Test-Retest Reproducibility of T1ρ and T2 Measurements of Lumbar Intervertebral Discs by 3T Magnetic Resonance Imaging.

OBJECTIVE: To investigate the interobserver and test-retest reproducibility of T1ρ and T2 measurements of lumbar intervertebral discs using 3T magnetic resonance imaging (MRI). MATERIALS AND METHODS: This study included a total of 51 volunteers (female, 26; male, 25; mean age, 54 ± 16.3 years) who underwent lumbar spine MRI with a 3.0 T scanner. Amongst these subjects, 40 underwent repeat T1ρ and T2 measurement acquisitions with identical image protocol. Two observers independently performed the region of interest measurements in the nuclei pulposi of the discs from L1-2 through L5-S1 levels. Statistical analysis was performed using intraclass correlation coefficient (ICC) with a two-way random model of absolute agreement. Comparison of the ICC values was done after acquisition of ICC values using Z test. Statistical significance was defined as p value < 0.05. RESULTS: The ICCs of interobserver reproducibility were 0.951 and 0.672 for T1ρ and T2 mapping, respectively. The ICCs of test-retest reproducibility (40 subjects) for T1ρ and T2 measurements were 0.922 and 0.617 for observer A and 0.914 and 0.628 for observer B, respectively. In the comparison of the aforementioned ICCs, ICCs of interobserver and test-retest reproducibility for T1ρ mapping were significantly higher than T2 mapping (p < 0.001). CONCLUSION: The interobserver and test-retest reproducibility of T1ρ mapping were significantly higher than those of T2 mapping for the quantitative assessment of nuclei pulposi of lumbar intervertebral discs.

A Case of Pulmonary Interstitial Emphysema Treated by Percutaneous Catheter Insertion in Extremely Low Birth Weight Infant.

The pulmonary interstitial emphysema (PIE) is a life-threatening illness in premature infants with mechanical ventilation. While most are managed conservatively, decompression would be necessary. Here, we report the first case of PIE treated by percutaneous catheter insertion in an extremely low birth weight (ELBW) infant in Korea. The patient, born with 660 g in 23+2 weeks of gestation, showed PIE in left lower lung on postnatal day 12. Percutaneous catheter insertion was performed on postnatal day 25. The size of PIE decreased, but didn't disappear completely. On postnatal day 42, we exchanged catheter and inserted additional catheter in pleural space. However, sudden desaturation and pneumothorax occurred on postnatal day 44. We changed catheter in pleural space, and pneumothorax and PIE improved. Finally, we successfully removed catheters, and weaned patient out. As in our case, percutaneous catheter insertion would be a useful option for ELBW infants with PIE.

Ultrasound measurement of pediatric visceral fat thickness: correlations with metabolic and liver profiles.

PURPOSE: Abdominal obesity is a fundamental factor underlying the development of metabolic syndrome. Because of radiation exposure and cost, computed tomography or dual-energy X-ray absorptiometry to evaluate abdominal adiposity are not appropriate in children. Authors evaluated whether ultrasound results could be an indicator of insulin resistance and nonalcoholic fatty liver disease (NAFLD). METHODS: We enrolled 73 subjects (aged 6-16 years) who were evaluated abdominal adiposity by ultrasound. Subcutaneous fat thickness was defined as the measurement from the skin-fat interface to the linea alba, and visceral fat thickness (VFT) was defined as the thickness from the linea alba to the aorta. Anthropometric and biochemical metabolic parameters were also collected and compared. The subjects who met 2 criteria, radiologic confirmed fatty liver and alanine aminotransferase >40, were diagnosed with NAFLD. RESULTS: There was a strong positive correlation between VFT and obesity. VFT was highly correlated with the homeostasis model assessment for insulin resistance score (r=0.403, P<0.001). The area under the curve for VFT as a predictor of NAFLD was 0.875 (95% confidence interval [CI], 0.787-0.964). VFT of 34.3 mm was found to be the discriminating cutoff for NAFLD (sensitivity, 84.6%; specificity, 71.2%, respectively). CONCLUSION: Ultrasound could be useful in measuring VFT and assessing abdominal adiposity in children. Moreover, increased VFT might be an appropriate prognostic factor for insulin resistance and NAFLD.

Accuracy of Diffusion Tensor Imaging for Diagnosing Cervical Spondylotic Myelopathy in Patients Showing Spinal Cord Compression.

OBJECTIVE: To assess the performance of diffusion tensor imaging (DTI) for the diagnosis of cervical spondylotic myelopathy (CSM) in patients with deformed spinal cord but otherwise unremarkable conventional magnetic resonance imaging (MRI) findings. MATERIALS AND METHODS: A total of 33 patients who underwent MRI of the cervical spine including DTI using two-dimensional single-shot interleaved multi-section inner volume diffusion-weighted echo-planar imaging and whose spinal cords were deformed but showed no signal changes on conventional MRI were the subjects of this study. Mean diffusivity (MD), longitudinal diffusivity (LD), radial diffusivity (RD), and fractional anisotropy (FA) were measured at the most stenotic level. The calculated performance of MD, FA, MD∩FA (considered positive when both the MD and FA results were positive), LD∩FA (considered positive when both the LD and FA results were positive), and RD∩FA (considered positive when both the RD and FA results were positive) in diagnosing CSM were compared with each other based on the estimated cut-off values of MD, LD, RD, and FA from receiver operating characteristic curve analysis with the clinical diagnosis of CSM from medical records as the reference standard. RESULTS: The MD, LD, and RD cut-off values were 1.079 × 10(-3), 1.719 × 10(-3), and 0.749 × 10(-3) mm(2)/sec, respectively, and that of FA was 0.475. Sensitivity, specificity, positive predictive value and negative predictive value were: 100 (4/4), 44.8 (13/29), 20 (4/20), and 100 (13/13) for MD; 100 (4/4), 27.6 (8/29), 16 (4/25), and 100 (8/8) for FA; 100 (4/4), 58.6 (17/29), 25 (4/16), and 100 (17/17) for MD∩FA; 100 (4/4), 68.9 (20/29), 30.8 (4/13), and 100 (20/20) for LD∩FA; and 75 (3/4), 68.9 (20/29), 25 (3/12), and 95.2 (20/21) for RD∩FA in percentage value. Diagnostic performance comparisons revealed significant differences only in specificity between FA and MD∩FA (p = 0.003), FA and LD∩FA (p < 0.001), FA and RD∩FA (p < 0.001), MD and LD∩FA (p = 0.024) and MD and RD∩FA (p = 0.024). CONCLUSION: Fractional anisotropy combined with MD, RD, or LD is expected to be more useful than FA and MD for diagnosing CSM in patients who show deformed spinal cords without signal changes on MRI.

Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle.

OBJECTIVE: To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. MATERIALS AND METHODS: Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. RESULTS: A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. CONCLUSION: T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.

Radiation dose and image quality in pediatric chest CT: effects of iterative reconstruction in normal weight and overweight children.

BACKGROUND: New CT reconstruction techniques may help reduce the burden of ionizing radiation. OBJECTIVE: To quantify radiation dose reduction when performing pediatric chest CT using a low-dose protocol and 50% adaptive statistical iterative reconstruction (ASIR) compared with age/gender-matched chest CT using a conventional dose protocol and reconstructed with filtered back projection (control group) and to determine its effect on image quality in normal weight and overweight children. MATERIALS AND METHODS: We retrospectively reviewed 40 pediatric chest CT (M:F = 21:19; range: 0.1-17 years) in both groups. Radiation dose was compared between the two groups using paired Student's t-test. Image quality including noise, sharpness, artifacts and diagnostic acceptability was subjectively assessed by three pediatric radiologists using a four-point scale (superior, average, suboptimal, unacceptable). RESULTS: Eight children in the ASIR group and seven in the control group were overweight. All radiation dose parameters were significantly lower in the ASIR group (P < 0.01) with a greater than 57% dose reduction in overweight children. Image noise was higher in the ASIR group in both normal weight and overweight children. Only one scan in the ASIR group (1/40, 2.5%) was rated as diagnostically suboptimal and there was no unacceptable study. CONCLUSION: In both normal weight and overweight children, the ASIR technique is associated with a greater than 57% mean dose reduction, without significantly impacting diagnostic image quality in pediatric chest CT examinations. However, CT scans in overweight children may have a greater noise level, even when using the ASIR technique.

Differentiation between focal malignant marrow-replacing lesions and benign red marrow deposition of the spine with T2*-corrected fat-signal fraction map using a three-echo volume interpolated breath-hold gradient echo Dixon sequence.

OBJECTIVE: To assess the feasibility of T2*-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. MATERIALS AND METHODS: We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. RESULTS: The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. CONCLUSION: Fat-signal fraction measurement using T2*-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.

Ultrasonographic findings of type IIIa biliary atresia.

PURPOSE: To describe the ultrasonographic (US) findings of type IIIa biliary atresia. METHODS: We retrospectively reviewed a medical database of patients pathologically confirmed to have biliary atresia, Kasai type IIIa, between January 2002 and May 2013 (n=18). We evaluated US findings including the visible common bile duct (CBD), triangular cord thickness, gallbladder size and shape, and subcapsular flow on color Doppler US; laboratory data; and pathological hepatic fibrosis grades. We divided them into two groups-those with visible (group A) and invisible (group B) CBD on US-and compared all parameters between the two groups. RESULTS: CBD was visible on US in five cases (27.8%; group A) and invisible in 13 cases (72.2%; group B). US was performed at an earlier age in group A than in group B (median, 27 days vs. 60 days; P=0.027) with the maximal age of 51 days. A comparison of the US findings revealed that the triangular cord thickness was smaller (4.1 mm vs. 4.9 mm; P=0.004) and the gallbladder length was larger (20.0 mm vs. 11.7 mm; P=0.021) in group A. The gallbladder shape did not differ between the two groups, and the subcapsular flow was positive in all cases of both groups. There was no significant difference in the laboratory data between the two groups. Upon pathological analysis, group A showed low-grade and group B showed low- to high-grade hepatic fibrosis. CONCLUSION: When CBD is visible on US in patients diagnosed with type IIIa biliary atresia, other US features could have a false negative status. A subcapsular flow on the color Doppler US would be noted in the type IIIa biliary atresia patients.

Effects of adaptive statistical iterative reconstruction on radiation dose reduction and diagnostic accuracy of pediatric abdominal CT.

BACKGROUND: Since children are more radio-sensitive than adults, there is a need to minimize radiation exposure during CT exams. OBJECTIVE: To evaluate the effects of adaptive statistical iterative reconstruction (ASIR) on radiation dose reduction, image quality and diagnostic accuracy in pediatric abdominal CT. MATERIALS AND METHODS: We retrospectively reviewed the abdominal CT examinations of 41 children (24 boys and 17 girls; mean age: 10 years) with a low-dose radiation protocol and reconstructed with ASIR (the ASIR group). We also reviewed routine-dose abdominal CT examinations of 41 age- and sex-matched controls reconstructed with filtered-back projection (control group). Image quality was assessed objectively as noise measured in the liver, spleen and aorta, as well as subjectively by three pediatric radiologists for diagnostic acceptability using a four-point scale. Radiation dose and objective image qualities of each group were compared with the paired t-test. Diagnostic accuracy was evaluated by reviewing follow-up imaging studies and medical records in 2012 and 2013. RESULTS: There was 46.3% dose reduction of size-specific dose estimates in ASIR group (from 13.4 to 7.2 mGy) compared with the control group. Objective noise was higher in the liver, spleen and aorta of the ASIR group (P < 0.001). However, the subjective image quality was average or superior in 84-100% of studies. Only one image was subjectively rated as unacceptable by one reviewer. There was only one case with interpretational error in the control group and none in the ASIR group. CONCLUSION: Use of the ASIR technique resulted in greater than a 45% reduction in radiation dose without impairing subjective image quality or diagnostic accuracy in pediatric abdominal CT, despite increased objective image noise.

A case of eosinophilic fasciitis presenting as pitting edema of the lower extremities.

Eosinophilic fasciitis is a rare disease characterized by diffuse fasciitis with peripheral eosinophilia and progressive induration and thickening of the skin and soft tissues. We report a 19-year-old female who presented with pitting edema in both lower extremities. She had a history of excessive physical activity before her symptoms developed. Physical examination revealed 2+ pitting edema in both lower legs. She complained of mild pain in both knee joints and feet, with no tenderness or heating sensations. Laboratory results were unremarkable except for severe eosinophilia. Parasite infection, venous thrombosis, and cardiac and renal problems were excluded. A magnetic resonance imaging study of both lower extremities revealed increased signal intensity in the subcutaneous lesions, consistent with superficial inflammation of the fascia. Mixed perivenular lymphoplasmacytic and eosinophilic infiltration in the subcutaneous lesion were observed on biopsy. The patient was treated with corticosteroids, resulting in remarkable improvement in both edema and eosinophilia.

CT venography for deep vein thrombosis using a low tube voltage (100 kVp) setting could increase venous enhancement and reduce the amount of administered iodine.

OBJECTIVE: To investigate the validity of the 100 kVp setting in CT venography (CTV) in the diagnosis of deep vein thrombosis (DVT), and to evaluate the feasibility of reducing the amount of administered iodine in this setting. MATERIALS AND METHODS: After receiving the contrast medium (CM) of 2.0 mL/kg, 88 patients underwent CTV of the pelvis and lower extremities by using one of four protocols: Group A, 120 kVp setting and 370 mgI/mL CM; group B, 120 kVp and 300 mgI/mL; group C, 100 kVp and 370 mgI/mL; group D, 100 kVp and 300 mgI/mL. The groups were evaluated for venous attenuation, vein-to-muscle contrast-to-noise ratio (CNR(VEIN)), DVT-to-vein contrast-to-noise ratio (CNR(DVT)), and subjective degree of venous enhancement and image quality. RESULTS: Venous attenuation and CNR(VEIN) were significantly higher in group C (144.3 Hounsfield unit [HU] and 11.9), but there was no significant difference between group A (118.0 HU and 8.2) and D (122.4 HU and 7.9). The attenuation value of DVT was not significantly different among the four groups, and group C had a higher absolute CNR(DVT) than the other groups. The overall diagnostic image quality and venous enhancement were significantly higher in group C, but there was no difference between groups A and D. CONCLUSION: The 100 kVp setting in CTV substantially help improve venous enhancement and CNR(VEIN). Furthermore, it enables to reduce the amount of administered iodine while maintaining venous attenuation, as compared with the 120 kVp setting.

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

OBJECTIVES: To 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. MATERIALS AND METHODS: Healthy 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. RESULTS: Two 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. CONCLUSIONS: ARFI 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.

Computed tomographic venography for varicose veins of the lower extremities: prospective comparison of 80-kVp and conventional 120-kVp protocols.

OBJECTIVE: To prospectively investigate the feasibility of an 80-kilovolt (peak) (kVp) protocol in computed tomographic venography for varicose veins of the lower extremities by comparison with conventional 120-kVp protocol. METHODS: Attenuation values and signal-to-noise ratio of iodine contrast medium (CM) were determined in a water phantom for 2 tube voltages (80 kVp and 120 kVp). Among 100 patients, 50 patients were scanned with 120 kVp and 150 effective milliampere second (mAs(eff)), and the other 50 patients were scanned with 80 kVp and 390 mAs(eff) after the administration of 1.7-mL/kg CM (370 mg of iodine per milliliter). The 2 groups were compared for venous attenuation, contrast-to-noise ratio, and subjective degree of venous enhancement, image noise, and overall diagnostic image quality. RESULTS: In the phantom, the attenuation value and signal-to-noise ratio value for iodine CM at 80 kVp were 63.8% and 33.0% higher, respectively, than those obtained at 120 kVp. The mean attenuation of the measured veins of the lower extremities was 148.3 Hounsfield units (HU) for the 80-kVp protocol and 94.8 HU for the 120-kVp protocol. Contrast-to-noise ratio was also significantly higher with the 80-kVp protocol. The overall diagnostic image quality of the 3-dimensional volume-rendered images was good with both protocols. The subjective score for venous enhancement was higher at the 80-kVp protocol. The mean volume computed tomography dose index of the 80-kVp (5.6 mGy) protocol was 23.3% lower than that of the 120-kVp (7.3 mGy) protocol. CONCLUSION: The use of the 80-kVp protocol improved overall venous attenuation, especially in perforating vein, and provided similarly high diagnostic image quality with a lower radiation dose when compared to the conventional 120-kVp protocol.