Pediatric head computed tomography with advanced modeled iterative reconstruction: focus on image quality and reduction of radiation dose Abstract Background Iterative reconstruction has become the standard method for reconstructing computed tomography (CT) scans and needs to be verified for adaptation. Objective To assess the image quality after adapting advanced modeled iterative reconstruction (ADMIRE) for pediatric head CT. Materials and methods We included image sets with filtered back projection reconstruction (the cFBP group, n=105) and both filtered back projection and ADMIRE reconstruction (the lower-dose group, n=109) after dose reduction. All five strength levels of ADMIRE and filtered back projection were adapted for the lower-dose group and compared with the cFBP group. Quantitative parameters including noise, signal-to-noise ratio and contrast-to-noise ratio and qualitative parameters including noise, white matter and gray matter differentiation of the supra- and infratentorial levels, sharpness, artifact, and diagnostic accuracy were also evaluated and compared with interobserver agreement. Results There was a mean dose reduction of 30.6% in CT dose index volume, 32.1% in dose length product, and 32.1% in effective dose after tube current reduction. There was gradual reduction of noise in air, cerebrospinal fluid and white matter with strength levels of ADMIRE from 1 to 5 (P<0.001). Signal-to-noise ratio and contrast-to-noise ratio in all age groups increased among strength levels of ADMIRE, in sequence from 1 to 5, with statistical significance (P<0.001). Gradual reduction of qualitative parameters was noted among strength levels of ADMIRE in sequence from 1 to 5 (P<0.001). Conclusion Use of ADMIRE for pediatric head CT can reduce radiation dose without degrading image quality.

The impact of 18 F-FDG PET on initial staging and therapy planning of pediatric soft-tissue sarcoma patients Abstract Background Soft-tissue sarcomas in children are a histologically heterogenous group of malignant tumors accounting for approximately 7% of childhood cancers. There is a paucity of data on the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for initial staging and whether PET influenced management of these patients. Objective The aim of this analysis is to assess the use of 18F-FDG PET exclusively, and as a supplement to cross-sectional imaging in comparison to typical imaging protocols (CT and magnetic resonance imaging [MRI]) for initial staging as well as therapy planning in pediatric soft-tissue sarcoma patients. Materials and methods The list of 18F-FDG PET/CT performed for soft-tissue sarcoma between March 2007 and October 2017 was obtained from the Hospital Information System database. Twenty-six patients who had received 18F-FDG PET, MRI and/or CT at initial diagnosis were included in the study. 18F-FDG PET and concurrent diagnostic CT and MRI at initial staging were independently reviewed to note the number of primary and metastatic lesions detected by each modality. A chart review was conducted to collect information on final diagnosis, staging and treatment plan. Results During the study period, 26 patients (15 females) ages 1.3–17.9 years (median age: 6 years) had received 18F-FDG PET/CT at initial diagnosis of soft-tissue sarcoma. Diagnostic CT was available for comparison in all 26 patients and MRI was available in 18 patients. The mean interval between cross-sectional imaging and 18F-FDG PET was 5.9 days (range: 0–30 days). All 26 primary lesions were equally detected by 18F-FDG PET compared to CT and MRI. From 84 metastatic lesions, 16 were detected by PET as well as CT and MRI, 12 by 18F-FDG PET only (included mainly lymph node metastases) and 56 by CT and MRI only (included mainly lung metastases). 18F-FDG PET changed therapy planning in 5 patients out of 26 (19%) by showing additional lesions not detected by CT and MRI. Conclusion 18F-FDG PET proved to be a valuable tool for precise initial staging of pediatric soft-tissue sarcoma patients, especially in detecting lymph node metastasis, and could be included in their initial work-up. Given the relative rarity and heterogeneity of this group of tumors, additional investigations are required to definitely establish a role for 18F-FDG PET in the initial staging and therapy planning of soft-tissue sarcoma in the pediatric population.

It’s time to recognize the perichondrium Abstract The perichondrium is a complex structure centered at the chondro-osseous junction of growing bones. It plays an important role in both normal skeletal development and in pathological conditions. This review illustrates the normal anatomy, function and imaging appearance of the perichondrium from fetal development to older childhood. The radiologic appearance of the perichondrium in skeletal trauma, infection and tumors in which it plays a role also are reviewed.

Inspiring advocacy: Abraham Jacobi

Modification of chest radiography exposure parameters using a neonatal chest phantom Abstract Background The acquisition of chest radiographs in neonates is of critical importance in diagnostics because of the risk of respiratory distress syndrome and pneumothorax in preterm infants. Objective To achieve a dose reduction while preserving a diagnostic image quality for chest radiographs of neonates. Materials and methods All radiographs, generated on a fully digital X-ray unit by using a neonatal chest phantom, were evaluated under variation of the tube voltage (40–70 kV) and mAs levels (1–10.2 mAs) with and without an additional 0.1-mm copper (Cu) filtration. Noise, contrast and contrast-to-noise ratio for bronchus, heart, lungs and vessels were determined. Visual assessment of the image quality was carried out by three radiologists using a Likert scale. To evaluate a maximally possible dose reduction, the dose of the radiographs with still acceptable image quality at a minimal dose was compared to the dose of the radiographs with the standard settings used in clinical routine. Results The noise showed decreasing values with increasing dose, while the contrast values were increased. For the contrast-to-noise ratio, a digressive course of the values as a function of the tube voltage was found. The visual evaluation of image quality showed the best evaluation of the structures at the lowest possible dose in the settings (44 kV, 3.36 mAs) with copper filtration and in the settings (44 kV, 1.56 mAs) without copper filtration. A maximum dose reduction from 8.29 μSv to 2.21 μSv (about 73%) was obtained. Conclusion A dose reduction while preserving diagnostic image quality in a digital X-ray system is generally possible by reducing the tube voltage and simultaneous adaptation of the mAs settings.

An image processing algorithm to aid diagnosis of mesial temporal sclerosis in children: a case-control study Abstract Background Mesial temporal sclerosis (MTS) is an important cause of intractable epilepsy. Early and accurate diagnosis of MTS is essential to providing curative and life-changing therapy but can be challenging in children in whom the impact of diagnosis is particularly high. Magnetic resonance imaging (MRI) plays an important role in the diagnosis of MTS, and image processing of MRI is a recently studied strategy to improve its accuracy. Objective In a retrospective case-control study, we assessed the performance of an image processing algorithm (Correlative Image Enhancement [CIE]) for detecting MTS-related hippocampal signal abnormality in children. Materials and methods Twenty-seven pediatric MTS cases (9 males, 18 females; mean age: 16±standard deviation [SD] 6.7 years) were identified from a pathology database of amygdylo-hippocampectomies performed in children with epilepsy. Twenty-seven children with no seizure history (9 males, 18 females; mean age: 13.8±SD 2.8 years), and with normal brain MRI, were identified for the control group. Blinded investigators processed the MRI coronal FLAIR (fluid-attenuated inversion recovery) images with CIE, saved the processed images as a separate series, and made equivalent region of interest measurements on the processed and unprocessed series to calculate contrast-to-noise ratio. Six blinded reviewers then rated the randomized series for hippocampal signal abnormality and MTS disease status. Results CIE increased signal intensity and contrast-to-noise ratio in 26/27 hippocampi with pathologically confirmed MTS (96.3%) with the mean (SD) contrast-to-noise ratio of cases increasing from 14.9 (11.1) to 77.7 (58.7) after processing (P<0.001). Contrast-to-noise ratio increased in 1/54 normal control hippocampi (1.9%), with no significant change in the mean contrast-to-noise ratio of the control group after processing (P=0.57). Mean (SD) reader sensitivity for detecting abnormal signal intensity increased from 83.3% (14.2) to 94.8% (3.3) after processing. Mean specificity for abnormal signal intensity increased from 94.4% (7.3) to 96.3% (0). While sensitivity improved after processing for detection of MTS disease status in 4/6 readers, the mean reader sensitivity and specificity for MTS detection increased only minimally after processing, from 79.6% to 80.7% and from 95.7% to 96.3%, respectively. Conclusion The CIE image processing algorithm selectively increased the contrast-to-noise ratio of hippocampi affected by MTS, improved reader performance in detecting MTS-related hippocampal signal abnormality and could have high impact on pediatric patients undergoing work-up for seizures.

Introduction

The Children’s Oncology Group: an opportunity for pediatric radiologists

Rare malignant liver tumors in children Abstract Malignant hepatic tumors in children are rare, comprising 1.3% of all pediatric malignancies. Following hepatoblastoma, hepatocellular carcinoma is the second most common. Other malignant hepatic tumors seen in childhood include those of mesenchymal origin including undifferentiated embryonal sarcoma, angiosarcoma, rhabdomyosarcoma and epithelioid hemangioendothelioma, as well as biliary tumors such as cholangiocarcinoma. Diagnosis can be challenging because of their rarity, and the recognition of distinctive imaging features for certain tumors such as epithelioid hemangioendothelioma and biliary rhabdomyosarcoma can focus the differential diagnosis and expedite the diagnostic process. A complete MRI examination with hepatocyte-specific contrast media and diffusion-weighted imaging helps to focus the differential diagnosis, and, although findings are often nonspecific, in some cases typical features on MRI can be helpful in diagnosis. Histopathological analysis is usually required for definitive diagnosis. Hepatic tumors tend to be aggressive, and full staging is imperative to establish disease extent. Significant proportions are not amenable to upfront surgical resection and often require a multimodality approach including neoadjuvant chemotherapy within a multidisciplinary setting. Facilitating complete surgical resection is usually required for better survival. In this review, we emphasize pathology and imaging features for rare liver tumors that are useful in reaching a prompt diagnosis. We also discuss general clinical findings, prognosis and management of these tumors.

The clinical and radiologic features of paediatric rhabdomyosarcoma Abstract Rhabdomyosarcoma is the most common soft-tissue sarcoma in children. The most common sites are head and neck, genitourinary tract and extremities. In this review we outline the clinical and radiologic features of paediatric rhabdomyosarcoma, as well as imaging considerations and imaging of relapse.