Optimization of hybrid iterative reconstruction level in pediatric body CT.

OBJECTIVE: The objective of our study was to attempt to optimize the level of hybrid iterative reconstruction (HIR) in pediatric body CT. MATERIALS AND METHODS: One hundred consecutive chest or abdominal CT examinations were selected. For each examination, six series were obtained: one filtered back projection (FBP) and five HIR series (iDose(4)) levels 2-6. Two pediatric radiologists, blinded to noise measurements, independently chose the optimal HIR level and then rated series quality. We measured CT number (mean in Hounsfield units) and noise (SD in Hounsfield units) changes by placing regions of interest in the liver, muscles, subcutaneous fat, and aorta. A mixed-model analysis-of-variance test was used to analyze correlation of noise reduction with the optimal HIR level compared with baseline FBP noise. RESULTS: One hundred CT examinations were performed of 88 patients (52 females and 36 males) with a mean age of 8.5 years (range, 19 days-18 years); 12 patients had both chest and abdominal CT studies. Radiologists agreed to within one level of HIR in 92 of 100 studies. The mean quality rating was significantly higher for HIR than FBP (3.6 vs 3.3, respectively; p < 0.01). HIR caused minimal (0-0.2%) change in CT numbers. Noise reduction varied among structures and patients. Liver noise reduction positively correlated with baseline noise when the optimal HIR level was used (p < 0.01). HIR levels were significantly correlated with body weight and effective diameter of the upper abdomen (p < 0.01). CONCLUSION: HIR, such as iDose(4), improves the quality of body CT scans of pediatric patients by decreasing noise; HIR level 3 or 4 is optimal for most studies. The optimal HIR level was less effective in reducing liver noise in children with lower baseline noise.

Imatinib mesylate for plexiform neurofibromas in patients with neurofibromatosis type 1: a phase 2 trial.

BACKGROUND: Plexiform neurofibromas are slow-growing chemoradiotherapy-resistant tumours arising in patients with neurofibromatosis type 1 (NF1). Currently, there are no viable therapeutic options for patients with plexiform neurofibromas that cannot be surgically removed because of their proximity to vital body structures. We undertook an open-label phase 2 trial to test whether treatment with imatinib mesylate can decrease the volume burden of clinically significant plexiform neurofibromas in patients with NF1. METHODS: Eligible patients had to be aged 3-65 years, and to have NF1 and a clinically significant plexiform neurofibroma. Patients were treated with daily oral imatinib mesylate at 220 mg/m(2) twice a day for children and 400 mg twice a day for adults for 6 months. The primary endpoint was a 20% or more reduction in plexiform size by sequential volumetric MRI imaging. Clinical data were analysed on an intention-to-treat basis; a secondary analysis was also done for those patients able to take imatinib mesylate for 6 months. This trial is registered with ClinicalTrials.gov, number NCT01673009. FINDINGS: Six of 36 patients (17%, 95% CI 6-33), enrolled on an intention-to-treat basis, had an objective response to imatinib mesylate, with a 20% or more decrease in tumour volume. Of the 23 patients who received imatinib mesylate for at least 6 months, six (26%, 95% CI 10-48) had a 20% or more decrease in volume of one or more plexiform tumours. The most common adverse events were skin rash (five patients) and oedema with weight gain (six). More serious adverse events included reversible grade 3 neutropenia (two), grade 4 hyperglycaemia (one), and grade 4 increases in aminotransferase concentrations (one). INTERPRETATION: Imatinib mesylate could be used to treat plexiform neurofibromas in patients with NF1. A multi-institutional clinical trial is warranted to confirm these results. FUNDING: Novartis Pharmaceuticals, the Indiana University Simon Cancer Centre, and the Indiana University Herman B Wells Center for Pediatric Research.

Severe lateral tibial bowing with short stature in two siblings--a provisionally novel syndrome.

In this report, we describe two siblings with short stature and severe lateral tibial bowing. In the younger sibling, the bowing was bilateral, while in the older sib, it was unilateral. However, both showed bilateral abnormalities of the distal tibial epiphyses and growth plates. Pseudoarthrosis of the left distal tibial metaphysis and subsequent spontaneous resolution of the abnormality occurred in the younger sibling. The fibulas of both children were of normal diameter and were straight, except for the distal ends. Surgery has almost completely corrected the lower leg bowing in both patients. The type of tibial bowing seen in these children can be associated with a number of syndromes, such as neurofibromatosis type I, Weismann-Netter syndrome, and a variety of environmental caused disorders, such as vitamin D deficient rickets. However, the severity of the bowing present in our patients and the absence of other clinical features differentiates this condition from those reported in the literature. We posit that the condition in the children presented here represents an as yet undescribed syndrome, which is likely to be of genetic origin.

Diagnostic errors from digital stitching of scoliosis images - the importance of evaluating the source images prior to making a final diagnosis.

BACKGROUND: Digital methods are used for scoliosis imaging. Separate images of the thoracic and lumbar/sacral spine are acquired. These are then stitched into a single image. This process has some potential disadvantages. OBJECTIVE: To assess anatomical errors in digitally stitched scoliosis films. MATERIALS AND METHODS: Eighty-six scoliosis studies were evaluated for stitching errors. The incidence of a stitching error resulting in an abnormality on the stitched image that could not be verified on the source images was calculated. Subgroups were analyzed based on the presence/absence of spinal hardware and standing/supine technique. RESULTS: Fourteen exams (16%) had stitching errors that could result in a false diagnosis if not correlated with the source images. The majority were errors of vertebral alignment. There was no significant difference in error rate with the presence or absence of hardware (P = 0.73) or patient positioning (P = 0.34). CONCLUSION: 16% of digital scoliosis exams had stitching errors that could result in a false diagnosis. The error rate was not influenced by spinal hardware or patient positioning. These results stress the importance of correlating any abnormality on the stitched image with the exam's source images; if not, a false diagnosis of abnormality will be made.

Marrow signal changes observed in follow-up whole-body MRI studies in children and young adults with neurofibromatosis type 1 treated with imatinib mesylate (Gleevec) for plexiform neurofibromas.

BACKGROUND: We observed bone marrow signal changes (BMSC) in patients with plexiform neurofibromas after treatment with imatinib mesylate (Gleevec). OBJECTIVE: To evaluate the pattern and natural history of BMSC. MATERIALS AND METHODS: The data were obtained from a pilot study of imatinib mesylate in patients with plexiform neurofibromas. All patients underwent baseline and sequential whole-body STIR 1.5-T MRI after treatment. The bone marrow signal on MRI was evaluated for abnormalities, location and pattern, and any change on follow-up studies. RESULTS: The study group included 16 patients (8 males) with a median age of 14 years (range 4 to 25 years). The mean whole-body MRI follow-up duration was 1.9 years. Of the 16 patients, 14 (88%) developed BMSC. The signal change was asymmetrical in 9 of the 14 patients (64%). The appendicular skeleton was involved in all 14 patients and the axial skeleton in 3 patients (21%). BMSC was followed in 13 patients and decreased signal was seen in 9 patients (69%) after a mean duration of 1.3 years of treatment (range 0.6 to 2.9 years); no complications were observed. CONCLUSION: BMSC appeared in most patients with neurofibromatosis type 1 following treatment with imatinib mesylate. BMSC was unusually asymmetrical and involved the lower extremities. On follow-up, BMSC often showed a decrease without complications.

Quality assurance: a comparison study of radiographic exposure for neonatal chest radiographs at 4 academic hospitals.

BACKGROUND: Little is known about exposure differences among hospitals. Large differences might identify outliers using excessive exposure. OBJECTIVE: We used the newly described exposure index and deviation index to compare the difference in existing radiographic exposures for neonatal portable chest radiographs among four academic children's hospitals. MATERIALS AND METHODS: For each hospital we determined the mean exposure index. We also set target exposure indices and then measured the deviation from this target. RESULTS: There was not a large difference in exposure index among sites. No site had an exposure index mean that was more than twice or less than half that of any other site. For all four sites combined, 92% of exposures had a deviation index within the range from -3 to +3. Thus exposures at each hospital were consistently within a reasonable narrow spectrum. CONCLUSION: Mean exposure index differences are caused by operational differences with mean values that varied by less than 50% among four hospitals. Ninety-two percent of all exposures were between half and double the target exposure. Although only one vendor's equipment was used, these data establish a practical reference range of exposures for neonatal portable radiographs that can be recommended to other hospitals for neonatal chest radiographs.

The Fontan procedure: anatomy, complications, and manifestations of failure.

The Fontan procedure refers to any operation that results in the flow of systemic venous blood to the lungs without passing through a ventricle. It is performed to treat several complex congenital heart abnormalities including tricuspid atresia, pulmonary atresia with intact ventricular septum, hypoplastic left heart syndrome, and double-inlet ventricle. The original Fontan procedure included direct anastomosis of the right atrium to the main pulmonary artery; however, multiple modifications have been employed. Creation of Fontan circulation is palliative in nature, with good results in patients with ideal hemodynamics and substantial morbidity and mortality in those with poor hemodynamics. Complications of Fontan circulation include exercise intolerance, ventricular failure, right atrium dilatation and arrhythmia, systemic and hepatic venous hypertension, portal hypertension, coagulopathy, pulmonary arteriovenous malformation, venovenous shunts, and lymphatic dysfunction (eg, ascites, edema, effusion, protein-losing enteropathy, and plastic bronchitis). Magnetic resonance imaging is best for postoperative evaluation of patients who underwent the Fontan procedure, and cardiac transplantation remains the only definitive treatment for those with failing Fontan circulation.

Quality assurance: using the exposure index and the deviation index to monitor radiation exposure for portable chest radiographs in neonates.

BACKGROUND: Many methods are used to track patient exposure during acquisition of plain film radiographs. A uniform international standard would aid this process. OBJECTIVE: To evaluate and describe a new, simple quality-assurance method for monitoring patient exposure. This method uses the "exposure index" and the "deviation index," recently developed by the International Electrotechnical Commission (IEC) and American Association of Physicists in Medicine (AAPM). The deviation index measures variation from an ideal target exposure index value. Our objective was to determine whether the exposure index and the deviation index can be used to monitor and control exposure drift over time. MATERIALS AND METHODS: Our Agfa workstation automatically keeps a record of the exposure index for every patient. The exposure index and deviation index were calculated on 1,884 consecutive neonatal chest images. Exposure of a neonatal chest phantom was performed as a control. RESULTS: Acquisition of the exposure index and calculation of the deviation index was easily achieved. The weekly mean exposure index of the phantom and the patients was stable and showed <10% change during the study, indicating no exposure drift during the study period. CONCLUSION: The exposure index is an excellent tool to monitor the consistency of patient exposures. It does not indicate the exposure value used, but is an index to track compliance with a pre-determined target exposure.

Accurate localization of the position of the tip of a naso/orogastric tube in children; where is the location of the gastro-esophageal junction?

BACKGROUND: Abdominal radiographs are used to determine the location of the tip of a newly placed nasogastric tube. The precise location of the gastroesophageal junction has not been well described in the radiology literature. OBJECTIVE: To improve interpretation of radiographs taken to evaluate the location of the tip of a nasogastric tube. Using UGI barium studies, we determined the anatomical location and variability of the position of the gastroesophageal (GE) junction and the pylorus MATERIALS AND METHODS: We reviewed 200 upper gastrointestinal barium studies (50 in each of 4 age groups). We measured the vertebral levels and distance of the gastroesophageal junction and the pylorus from the spine, the vertical distance of the gastroesophageal junction from the dome of the diaphragm and the distance from the gastroesophageal junction to the pylorus. RESULTS: There is a constant location of the GE junction with no significant variation between age groups. There is a moderately constant location of the pylorus. The other measurements were very variable. CONCLUSION: The location of the GE junction is very constant, irrespective of age. Tube tips below the level of the vertebral disc between the 11th and 12th thoracic vertebra and/or more than 16 mm from the left side of the spine lie in the stomach and not the lower esophagus. Our results should help in accurate radiographic description of the location of the tip of an NG tube.

MRI of surgical repair of transposition of the great vessels.

OBJECTIVE: Our objectives are to review the surgical procedures that have been performed for the treatment of transposition of the great vessels. Using MRI, we illustrate the normal postoperative findings and many of the long-term complications for each of the surgical procedures. CONCLUSION: MRI is an extremely useful imaging method for evaluation of normal and abnormal findings after surgical repair of transposition of the aorta and pulmonary artery.

Pediatric CT radiation dose: how low can you go?

OBJECTIVE: There is a known risk from radiation. The objective of this article is to answer the following question regarding CT: Is there a risk of lowering the radiation exposure so low that the risk of missing a diagnosis from excessive noise in the image begins to exceed the risk of the radiation itself? CONCLUSION: When performing CT, adequate radiation dose must be used to make a confident and accurate diagnosis. The total population radiation exposure can be reduced effectively by numerous other means, including aggressively reducing the number of CT examinations performed for poor clinical indications, scanning only the anatomic region of interest, and not performing both unenhanced and contrast-enhanced scanning unless absolutely necessary.

CT with a computer-simulated dose reduction technique for detection of pediatric nephroureterolithiasis: comparison of standard and reduced radiation doses.

OBJECTIVE: The purpose of this study was to compare the diagnostic capabilities of standard- and reduced-dose CT in the detection of nephroureterolithiasis in children. MATERIALS AND METHODS: Forty-five patients 20 years old or younger divided into two groups weighing 50 kg or less and more than 50 kg underwent unenhanced 16-MDCT in the evaluation of acute flank pain. An investigational computer-simulated tube current reduction tool was used to produce additional 80- and 40-mA examination sets (total number of image sets=135). Three independent blinded readers ranked random images for stones (confidence scale, 1-5, least to most), hydronephrosis, noise-based image quality, and presence of nonrenal lesions. RESULTS: Compared with the standard tube current used for the original CT scans, there was no significant reduction (p=0.37) in detection of renal stones at the 80-mA setting (mean dose reduction, 67%; range, 43-81%); and at the 40-mA setting (mean dose reduction, 82%; range, 72-90%), the detection rate was significantly lower (p=0.05). At the 40-mA setting, there was no significant difference among the children weighing 50 kg or less (p=0.4). Detection of ureteral stones and hydronephrosis was not significantly different at 80 and 40 mA; however, disease frequency was low, and no definite conclusion can be made. CONCLUSION: Simulated dose reduction is a useful tool for determining diagnostic thresholds for MDCT detection of renal stones in children. Use of the 80-mA setting for all children and 40 mA for children weighing 50 kg or less does not significantly affect the diagnosis of pediatric renal stones.

Making preliminary radiographic reports available to referring clinicians: current status.

RATIONALE AND OBJECTIVES: To investigate current practice regarding the release of resident's preliminary imaging reports to physicians providing clinical care to patients. The second objective was to evaluate compliance with the American College of Radiology (ACR) practice guidelines. MATERIALS AND METHODS: With the assistance of the Society of Chairman of Academic Radiology Departments (SCARD), a survey was sent to its members. This survey asked if members felt that residents' preliminary reports should be released to referring physicians. If yes, the survey requested information as to how this was done and the mechanism by which the referring physicians were informed that the report was preliminary. RESULTS: Twenty-eight surveys were completed. Twenty-five respondents felt that preliminary reports should always be made easily available to referring physicians; three did not. In 25 of 28 institutions, the referring clinicians can obtain preliminary information by talking to the trainee face-to-face or by phone. In 12 institutions, clinicians could obtain preliminary reports by phoning into the hospital dictation system and listening to the dictated report. Twenty-six of the 28 institutions permit referring clinicians to obtain preliminary reports by viewing/reading these reports in picture archiving and communication system (PACS) or hospital information system (HIS) systems, before they are finalized. CONCLUSIONS: Almost all academic radiology departments responding to this survey do make electronic trainee reports available to referring clinicians. Compliance with ACR guidelines is good, but not perfect. Most institutions no longer provide the ability to listen to the dictation.