A Survey of Pediatric CT Protocols and Radiation Doses in South Korean Hospitals to Optimize the Radiation Dose for Pediatric CT Scanning

Children are at greater risk of radiation exposure than adults because the rapidly dividing cells of children tend to be more radiosensitive and they have a longer expected life time in which to develop potential radiation injury. Some studies have surveyed computed tomography (CT) radiation doses and several studies have established diagnostic reference levels according to patient age or body size; however, no survey of CT radiation doses with a large number of patients has yet been carried out in South Korea. The aim of the present study was to investigate the radiation dose in pediatric CT examinations performed throughout South Korea. From 512 CT (222 brain CT, 105 chest CT, and 185 abdominopelvic CT) scans that were referred to our tertiary hospital, a dose report sheet was available for retrospective analysis of CT scan protocols and dose, including the volumetric CT dose index (CTDIvol), dose-length product (DLP), effective dose, and size-specific dose estimates (SSDE). At 55.2%, multiphase CT was the most frequently performed protocol for abdominopelvic CT. Tube current modulation was applied most often in abdominopelvic CT and chest CT, accounting for 70.1% and 62.7%, respectively. Regarding the CT dose, the interquartile ranges of the CTDIvol were 11.1 to 22.5 (newborns), 16.6 to 39.1 (≤1 year), 14.6 to 41.7 (2-5 years), 23.5 to 44.1 (6-10 years), and 31.4 to 55.3 (≤15 years) for brain CT; 1.3 to 5.7 (≤1 year), 3.9 to 6.8 (2-5 years), 3.9 to 9.3 (6-10 years), and 7.7 to 13.8 (≤15 years) for chest CT; and 4.0 to 7.5 (≤1 year), 4.2 to 8.9 (2-5 years), 5.7 to 12.4 (6-10 years), and 7.6 to 16.6 (≤15 years) for abdominopelvic CT. The SSDE and CTDIvol were well correlated for patients <5 years old, whereas the CTDIvol was lower in patients ≥6 years old. Our study describes the various parameters and dosimetry metrics of pediatric CT in South Korea. The CTDIvol, DLP, and effective dose were generally lower than in German and UK surveys, except in certain age groups.

Correction: Characteristics of Pediatric Pancreatitis on Magnetic Resonance Cholangiopancreatography

[This corrects the article on p. 73 in vol. 18, PMID: 26157692.].

Characteristics of Pediatric Pancreatitis on Magnetic Resonance Cholangiopancreatography

Pediatric pancreatitis is not uncommon and results in considerable morbidity and mortality in the affected children. Unlike adults, pediatric pancreatitis is more frequently associated with underlying structural abnormalities, trauma, and drugs rather than an idiopathic etiology. Magnetic resonance cholangiopancreatography (MRCP) is a good imaging modality for evaluating pancreatitis and determining etiology without exposure to radiation. This article focuses on MRCP findings associated with various causes of pancreatitis in children, particularly structural abnormalities of the pancreaticobiliary system, as well as describing the feasibility, limitations, and solutions associated with pediatric MRCP.

Characterization of negative regulatory genes for the biosynthesis of rapamycin in Streptomyces rapamycinicus and its application for improved production

Sequence analysis of the rapamycin biosynthetic gene cluster in Streptomyces rapamycinicus ATCC 29253 identified several putative regulatory genes. The deduced product of rapY, rapR, and rapS showed high sequence similarity to the TetR family transcription regulators, response regulators and histidine kinases of two-component systems, respectively. Overexpression of each of the three genes resulted in a significant reduction in rapamycin production, while in-frame deletion of rapS and rapY from the S. rapamycinicus chromosome improved the levels of rapamycin production by approximately 4.6-fold (33.9 mg l(-1)) and 3.7-fold (26.7 mg l(-1)), respectively, compared to that of the wild-type strain. Gene expression analysis by semi-quantitative reverse transcription-PCR (RT-PCR) in the wild-type and mutant strains indicated that most of the rapamycin biosynthetic genes are regulated negatively by rapS (probably through its partner response regulator RapR) and rapY. Interestingly, RapS negatively regulates the expression of the rapY gene, and in turn, rapX encoding an ABC-transporter is negatively controlled by RapY. Finally, overexpression of rapX in the rapS deletion mutant resulted in a 6.7-fold (49 mg l(-1)) increase in rapamycin production compared to that of wild-type strain. These results demonstrate the role of RapS/R and RapY as negative regulators of rapamycin biosynthesis and provide valuable information to both understand the complex regulatory mechanism in S. rapamycinicus and exploit the regulatory genes to increase the level of rapamycin production in industrial strains.

Transperineal ultrasonography for evaluation of the perianal fistula and abscess in pediatric Crohn disease: preliminary study

PURPOSE

To assess the feasibility and effectiveness of transperineal ultrasonography (TPUS) for the evaluation of perianal Crohn disease (PCD) in pediatric patients.

METHODS

Between September 2010 and August 2013, 64 TPUS examinations were performed in 43 patients (34 males and 9 females; mean age±standard deviation, 13.3±2.4 years; age range, 6 to 17 years) to evaluate PCD. The pain severity, location, and activity of perianal fistula, the presence of an abscess, and anal canal hyperemia were retrospectively evaluated. Spearman rank correlation analysis was performed to assess the relationship between the severity of the pain and the fistula activity, the presence of an abscess, and anal canal hyperemia.

RESULTS

All examinations were successfully performed. Thirty-nine examinations (60.9%) were performed without any pain experienced by the patient, 19 examinations (29.7%) with mild pain, five examinations (7.8%) with moderate pain, and one examination (1.6%) with severe pain. The pain severity was correlated with the fistula activity (P<0.01). An anterior fistula location was more common than a posterior location. Active fistulas and abscesses were identified during 30 examinations (46.9%) and 12 examinations (18.8%), respectively. Anal canal hyperemia was identified in 31 examinations (48.4%).

CONCLUSION

TPUS with a color Doppler study is useful for visualizing a perianal fistula or abscess and for assessing its inflammatory activity in pediatric Crohn patients.

Management of late-onset portal vein complications in pediatric living-donor liver transplantation

The purpose of this study was to evaluate retrospectively the results of PTA for late-onset PV complications after pediatric LDLT and to assess whether a meso-Rex shunt is a viable option for treating restenosis of the PV after PTA in selected cases. Seventy-five children who underwent adult-to-child LDLT were included in this study, and there were six late-onset PV complications (8.0%). The initial therapeutic approach was PTA, with or without stent: PTA with balloon dilation for three children, PTA with stent placement for one child, and failure to cannulate the occluded PV for two children. A meso-Rex shunt was performed in the two children after failed PTA: One suffered complete obstruction of the main PV, and the other, restenosis with total thrombosis after PTA with stent. The PTA was a technical and clinical success in four with PV stenosis of the six patients (66.7%), and successful application of a meso-Rex shunt in the other two children resulted in restoration of PV flow. In conclusion, PTA is a safe and effective procedure for treating late-onset PV stenosis after pediatric LDLT. However, in growing pediatric recipients with restenosis of the PV after PTA or chronic PV thrombosis, a meso-Rex shunt may be a better choice for late-onset PV complications.

Congenital internal hernia presented with life threatening extensive small bowel strangulation

Internal hernia (IH) is a rare cause of small bowel obstruction occurs when there is protrusion of an internal organ into a retroperitoneal fossa or a foramen in the abdominal cavity. IH can be presented with acute or chronic abdominal symptom and discovered by accident in operation field. However, various kinds of imaging modalities often do not provide the assistance to diagnose IH preoperatively, but computed tomography (CT) scan has a high diagnostic accuracy. We report a case of congenital IH in a 6-year-old boy who experienced life threatening shock. CT scan showed large amount of ascites, bowel wall thickening with poor or absent enhancement of the strangulated bowel segment. Surgical exploration was performed immediately and had to undergo over two meters excision of strangulated small bowel. To prevent the delay in the diagnosis of IH, we should early use of the CT scan and take urgent operation.

Characterization of FK506 biosynthetic intermediates involved in post-PKS elaboration

The post-PKS modification steps of FK506 biosynthesis include C9-oxidation and 31-O-methylation, but the sequence of these reactions and the exact route have remained unclear. This study details the post-PKS modification pathways in FK506 biosynthesis through the identification of all intermediates and in vitro enzymatic reactions of the cytochrome P450 hydroxylase FkbD and the methyltransferase FkbM. These results complete our understanding of post-PKS modification steps to FK506 showing the substrate flexibility of two enzymes involved and the existence of two parallel biosynthetic routes to FK506.

Interrupting gel layer between Double cuffs prevents fluid leakage past tracheal tube cuffs

BACKGROUND

Current tracheal tubes (TTs) cannot guarantee a perfect seal against pulmonary aspiration of upper airway secretions. The purpose of this study was to investigate whether a gel layer between the tracheal tube with double cuffs (Double cuffs) prevents fluid leakage past TT cuffs.

METHODS

In vitro fluid leakage tests were performed using the Double cuff with or without a gel layer between the two cuffs and four commercially available TTs (Euromedical Standard TT, Mallinckrodt Hi-Lo™, Microcuff, and Mallinckrodt TaperGuard™) when placed in artificial tracheas with three-different internal diameters (ID; 16, 20, and 22 mm). Blue-dyed water (5 ml) was placed above the cuff, and the extent of fluid leakage was observed for 48 h. Each test was repeated five times with new tubes at six different intracuff pressures (15, 20, 25, 30, 40, and 50 cm H2O).

RESULTS

In all of the conventional TTs and the Double cuff without a gel layer, fluid leakage was observed even at clinically acceptable intracuff pressures (25-30 cm H2O). However, in the Double cuff with a gel layer, no fluid leakage was observed for 48 h at all intracuff pressures in three-different sized artificial tracheas. At an intracuff pressure of 20 cm H2O in a 20 mm ID trachea, the average volume of injected gel was 2.0 ml. After removal of the TT, the mean volume of the remaining gel in the trachea was 0.10 ml.

CONCLUSIONS

A prototype TT with gel-layered Double cuffs completely blocked fluid leakage past the cuffs for 48 h in a bench-top model. Clinical studies are required to determine whether this TT reduces the risk of ventilator-associated pneumonia.

Assessment of the fatty liver index as an indicator of hepatic steatosis for predicting incident diabetes independently of insulin resistance in a Korean population

AIMS

Fatty liver disease, especially non-alcoholic fatty liver disease, is considered to be the hepatic manifestation of the metabolic syndrome, both closely associated with insulin resistance. Furthermore, fatty liver disease assessed by ultrasonography is known to be a predictor of the development of Type 2 diabetes mellitus. However, it remains unclear whether fatty liver disease plays a role in the pathogenesis of Type 2 diabetes independently of insulin resistance. In this study, we investigated whether fatty liver disease assessed by the fatty liver index can predict the development of Type 2 diabetes independently of systemic insulin resistance.

METHODS

We examined the clinical and laboratory data of 7860 subjects without diabetes who underwent general routine health evaluations at the Asan Medical Center in 2007 and had returned for follow-up examinations in 2011. Fatty liver index was calculated using an equation that considers serum triglyceride levels, γ-glutamyltransferase, waist circumference and BMI.

RESULTS

During a 4-year period, 457 incident diabetes cases (5.8%) were identified. The odds ratios for the development of Type 2 diabetes were significantly higher in the group with a fatty liver index ≥ 60 (fatty liver index-positive) than in the group with a fatty liver index < 20 (fatty liver index-negative) after adjusting for various confounding variables including homeostasis model assessment of insulin resistance. Odds ratios were significant regardless of the insulin resistance status at baseline.

CONCLUSIONS

Our results suggest that fatty liver index as a simple surrogate indicator of hepatic steatosis is valuable in identifying subjects at high risk for Type 2 diabetes. In addition, fatty liver disease itself contributes to the development of Type 2 diabetes independently of systemic insulin resistance.

Pro-apoptotic Effect of Pifithrin-α on Preimplantation Porcine In vitro Fertilized Embryo Development

The aim of this study was to investigate the impact of a reported p53 inhibitor, pifithrin-α (PFT-α), on preimplantation porcine in vitro fertilized (IVF) embryo development in culture. Treatment of PFT-α was administered at both early (0 to 48 hpi), and later stages (48 to 168 hpi) of preimplantation development, and its impact upon the expression of five genes related to apoptosis (p53, bak, bcl-xL, p66Shc and caspase3), was assessed in resulting d 7 blastocysts, using real-time quantitative PCR. Total cell numbers, along with the number of apoptotic nuclei, as detected by the in situ cell death detection assay, were also calculated on d 7 in treated and non-treated control embryos. The results indicate that PFT-α, when administered at both early and later stages of porcine IVF embryo development, increases the incidence of apoptosis in resulting blastocysts. When administered at early cleavage stages, PFT-α treatment was shown to reduce the developmental competence of porcine IVF embryos, as well as reducing the quality of resulting blastocysts in terms of overall cell numbers. In contrast, at later stages, PFT-α administration resulted in marginally increased blastocyst development rates amongst treated embryos, but did not affect cell numbers. However, PFT-α treatment induced apoptosis and apoptotic related gene expression, in all treated embryos, irrespective of the timing of treatment. Our results indicate that PFT-α may severely compromise the developmental potential of porcine IVF embryos, and is a potent apoptotic agent when placed into porcine embryo culture media. Thus, caution should be exercised when using PFT-α as a specific inhibitor of p53 mediated apoptosis, in the context of porcine IVF embryo culture systems.

Superior Mesenteric Artery Syndrome Leading to Acute Gastric Dilatation in a Woman with Bulimia

Superior mesenteric artery (SMA) syndrome is a rare clinical disease defined as compression of the third part of the duodenum between the aorta and the SMA. Severe complications of SMA syndrome include acute gastric dilatation which is uncommon but potentially fatal and requires immediate intervention. This report describes a 29-year-old woman with SMA syndrome complicated by acute gastric dilatation. It was diagnosed by computerized tomography. The patient had a history of treatment of bulimia nervosa but defaulted 3 months ago. She presented with severe abdominal distension and extreme abdominal pain due to massive gastric dilatation after an eating binge. Gastric decompression was successful with a modified gastric lavage tube with additional large holes at the tip.

Perpendicular magnetic anisotropy in amorphous ferromagnetic CoSiB/Pt multilayers

Magnetic anisotropy properties of amorphous ferromagnetic CoSiB/Pt multilayers with perpendicular magnetic anisotropy (PMA, K(u)) were systematically investigated as a function of CoSiB layer thickness (t(coSiB)) and Pt layer thickness (t(Pt)). In two series of [CoSiB t(coSiB)Pt t(P1)]5 multilayers, the perpendicular coercivity (H(c)) increased to reach a maximum and then decreased with further increase in both t(coSiB) and t(Pt), due to intermixing of CoSiB/Pt interfaces. Particularly, using the amorphous soft magnetic CoSiB, the coercivity became very sensitive to the CoSiB thickness. These multilayer films exhibited a high K(u) of 2 x 10(6) erg/cc and a high H(c) of 360 Oe with marked squareness. It was found that even after annealing at 350 degrees C, the CoSiB/Pt multilayers had a high PMA and their H(c) increased.

Early-onset Charcot-Marie-Tooth patients with mitofusin 2 mutations and brain involvement

Mutations of the mitofusin 2 (MFN2) gene have been reported to be the most common cause of the axonal form of Charcot-Marie-Tooth disease (CMT). A prospective brain MRI study was performed on 18 early-onset CMT patients with MFN2 mutations, and a high frequency (39%) of brain abnormalities was found. Early-onset patients showed multiple scattered or confluent brain lesions that involved gray matter as well as white matter. Patterns of brain involvement in early-onset patients differed from those of late-onset patients and other hereditary peripheral neuropathies. In addition, one CMT patient demonstrated a brain lesion before the development of peripheral neuropathy.

Visually isoattenuating pancreatic adenocarcinoma at dynamic-enhanced CT: frequency, clinical and pathologic characteristics, and diagnosis at imaging examinations

PURPOSE

To retrospectively determine the frequency, clinical and pathologic characteristics, and computed tomographic (CT) findings of visually isoattenuating pancreatic adenocarcinomas and to investigate the utility of magnetic resonance (MR) imaging and positron emission tomography (PET)/CT for detecting them.

MATERIALS AND METHODS

Institutional review board approval was obtained. Patient informed consent was waived. Of 743 consecutive patients with pathologically proved pancreatic cancer, 644 patients (392 men, 252 women; mean age, 60 years ± 9.5 [standard deviation]) who had undergone both arterial and portal phase contrast material-enhanced CT were included. Visually isoattenuating pancreatic adenocarcinoma was defined as lesion isoattenuation in both scan phases. Serum levels of carbohydrate antigen 19-9, immunoglobulin G (IgG), and IgG fraction 4 (IgG4), survival after curative-intent surgery; and pathologic findings of visually isoattenuating pancreatic adenocarcinomas were analyzed. CT findings of visually isoattenuating pancreatic adenocarcinomas and the sensitivity of MR imaging and PET/CT for detecting them were determined.

RESULTS

The frequency of visually isoattenuating pancreatic adenocarcinomas among pancreatic cancers was 5.4% (35 of 644). Serum levels of carbohydrate antigen 19-9, IgG, and IgG4 were elevated in 51.5% (17 of 33), 8.3% (one of 12), and 8.3% (one of 12) of patients, respectively. Visually isoattenuating pancreatic adenocarcinoma, compared with usual pancreatic adenocarcinoma, was independently associated with a better survival after curative-intent surgery: Adjusted hazard ratio was 0.430 (P = .006). Thirty surgically resected visually isoattenuating pancreatic adenocarcinomas were 1.5-4 cm (median, 3 cm). Their pathologic findings differed from those of usual pancreatic adenocarcinomas: lower tumor cellularity, more frequent intratumoral acinar tissue and islet cells, and less prominent tumor necrosis. Visually isoattenuating pancreatic adenocarcinomas showed various abnormalities at CT, which may suggest an isoattenuating mass or nodule. Sensitivities of MR imaging and PET/CT were 79.2% (19 of 24) and 73.7% (14 of 19), respectively.

CONCLUSION

Visually isoattenuating pancreatic adenocarcinoma represents a small but meaningful subset of pancreatic cancer and has characteristic clinical and pathologic features. MR imaging and PET/CT may be useful as subsequent examinations when the patient is suspected of having the lesion at CT.

A randomised phase II study of modified FOLFIRI.3 vs modified FOLFOX as second-line therapy in patients with gemcitabine-refractory advanced pancreatic cancer

Background:

Only a few clinical trials have been conducted in patients with advanced pancreatic cancer after failure of first-line gemcitabine-based chemotherapy. Therefore, there is no current consensus on the treatment of these patients. We conducted a randomised phase II study of the modified FOLFIRI.3 (mFOLFIRI.3; a regimen combining 5-fluorouracil (5-FU), folinic acid, and irinotecan) and modified FOLFOX (mFOLFOX; a regimen combining folinic acid, 5-FU, and oxaliplatin) regimens as second-line treatments in patients with gemcitabine-refractory pancreatic cancer.

Methods:

The primary end point was the 6-month overall survival rate. The mFOlFIRI.3 regimen consisted of irinotecan (70 mg m⁻²; days 1 and 3), leucovorin (400 mg m⁻²; day 1), and 5-FU (2000 mg m⁻²; days 1 and 2) every 2 weeks. The mFOLFOX regimen was composed of oxaliplatin (85 mg m⁻²; day 1), leucovorin (400 mg m⁻²; day 1), and 5-FU (2000 mg m⁻²; days 1 and 2) every 2 weeks.

Results:

Sixty-one patients were randomised to mFOLFIRI.3 (n=31) or mFOLFOX (n=30) regimen. The six-month survival rates were 27% (95% confidence interval (CI)=13–46%) and 30% (95% CI=15–49%), respectively. The median overall survival periods were 16.6 and 14.9 weeks, respectively. Disease control was achieved in 23% (95% CI=10–42%) and 17% patients (95% CI=6–35%), respectively. The number of patients with at least one grade 3/4 toxicity was identical (11 patients, 38%) in both groups: neutropenia (7 patients under mFOLFIRI.3 regimen vs 6 patients under mFOLFOX regimen), asthaenia (1 vs 4), vomiting (3 in both), diarrhoea (2 vs 0), and mucositis (1 vs 2).

Conclusion:

Both mFOLFIRI.3 and mFOLFOX regimens were tolerated with manageable toxicity, offering modest activities as second-line treatments for patients with advanced pancreatic cancer, previously treated with gemcitabine.

Reduced expression of angiopoietin-1 in Hantaan virus-infected human umbilical vein endothelial cell increases their permeability

Hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus (HTNV) is characterized by vascular hemorrhage and acute renal failure. Angiopoietin-1 (Ang-1) is a glycoprotein that maintains vessel integrity and reduces endothelial permeability. We found that in HTNV-infected human umbilical vein endothelial cells (HUVECs) the levels of Ang-1 mRNA and protein were reduced on days 2 and 3 post-infection (p.i.), when endothelial permeability was increased. The HTNV-stimulated permeability was reduced by treatment of HUVECs with Ang-1. The plasma Ang-1 level was lower in HFRS patients than in healthy persons. Paired plasma samples of HFRS patients revealed markedly lower Ang-1 levels during the acute phase of HFRS as compared to the convalescent phase. These findings suggested that HTNV reduced the Ang-1 expression in endothelial cells that might play an important role in the increase of vascular permeability in HFRS.

Atomic scale structure and chemical composition across order-disorder interfaces

Through a combination of aberration-corrected high-resolution scanning transmission electron microscopy and three-dimensional atom probe tomography, the true atomic-scale structure and change in chemical composition across the complex order-disorder interface in a metallic alloy has been determined. The study reveals the presence of two interfacial widths, one corresponding to an order-disorder transition, and the other to the compositional transition across the interface, raising fundamental questions regarding the definition of the interfacial width in such systems.