Major skull manifestations of skeletal dysplasias - pictorial essay.

Skeletal dysplasias are a large group of rare conditions with widely heterogeneous manifestations and a reputation for being diagnostically difficult. Involvement of the brain and craniovertebral junction are features familiar to the paediatric neuroradiologist. Involvement of the skull itself represents an area of overlap between the domains of the neuroradiologist and the skeletal dysplasia radiologist. In this pictorial essay, we review the principal skull manifestations of skeletal dysplasias as they present to the neuroradiologist.

Case 268: Bilateral Adrenal Hemorrhage in the Context of Sepsis.

History A 65-year-old man presented to the emergency department with a 1-week history of constipation, which was associated with increasing abdominal distention and not passing flatus. Four weeks prior to the current admission he had been diagnosed with metastatic primary adenocarcinoma of the appendix. One week ago, he had been hospitalized with small-bowel obstruction, for which he required laparotomy and loop ileostomy. His medical history included basal cell carcinoma, rheumatoid arthritis, and Barrett esophagus. Physical examination revealed a distended abdomen with tenderness at palpation within the right upper quadrant and lower abdomen and reduced bowel sounds at auscultation. Initial plain-film radiography of the abdomen at admission revealed dilated gas-filled small-bowel loops, suggestive of obstruction. His small-bowel obstruction was managed conservatively on this occasion. Nine days after admission, the patient became unwell and reported a productive cough. He became tachycardic, tachypneic, and hypotensive. Relevant blood tests at this stage revealed a C-reactive protein level of 206 mg/L (normal range, 0-10 mg/L), a white blood cell count of 24.5 × 109/L (normal range, [4.0-11.0] × 109/L), a red blood cell count of 3.39 × 1012/L (normal range, [4.5-5.5] × 1012/L), a hemoglobin level of 93 g/L (normal range, 130-170 g/L), and a hematocrit level of 0.27 (normal range, 0.4-0.5). CT of the abdomen and pelvis with intravenous contrast material (100 mL Omnipaque 350; GE Healthcare, Oslo, Norway) was performed.

Case 268.

History A 65-year-old man presented to the emergency department with a 1-week history of constipation, which was associated with increasing abdominal distention and not passing flatus. Four weeks prior to the current admission he had been diagnosed with metastatic primary adenocarcinoma of the appendix. One week ago, he had been hospitalized with small-bowel obstruction, for which he required laparotomy and loop ileostomy. His medical history included basal cell carcinoma, rheumatoid arthritis, and Barrett esophagus. Physical examination revealed a distended abdomen with tenderness at palpation within the right upper quadrant and lower abdomen and reduced bowel sounds at auscultation. Initial plain-film radiography of the abdomen at admission revealed dilated gas-filled small-bowel loops, suggestive of obstruction. His small-bowel obstruction was managed conservatively on this occasion. Nine days after his admission, the patient became unwell and reported a productive cough. He became tachycardic, tachypneic, and hypotensive. Relevant blood tests at this stage revealed a C-reactive protein level of 206 mg/L (normal range, 0-10 mg/L), a white blood cell count of 24.5 × 109/L (normal range, [4.0-11.0] × 109/L), a red blood cell count of 3.39 × 1012/L (normal range, [4.5-5.5] × 1012/L), a hemoglobin level of 93 g/L (normal range, 130-170 g/L), and a hematocrit level of 0.27 (normal range, 0.4-0.5). CT of the abdomen and pelvis with intravenous contrast material (100 mL Omnipaque 350; GE Healthcare, Oslo, Norway) was performed ( Figs 1 , 2 ). Figure 1a: (a) Axial and (b) curved reformatted contrast-enhanced CT images of the upper abdomen. Figure 1b: (a) Axial and (b) curved reformatted contrast-enhanced CT images of the upper abdomen. Figure 2a: (a) Axial and (b) coronal contrast-enhanced CT images of the upper abdomen obtained 12 days before the CT images shown in Figures 1a and 1b , respectively. Figure 2b: (a) Axial and (b) coronal contrast-enhanced CT images of the upper abdomen obtained 12 days before the CT images shown in Figures 1a and 1b , respectively.

Acoustic shadowing in pediatric kidney stone ultrasound: a retrospective study with non-enhanced computed tomography as reference standard.

BACKGROUND: The usefulness of acoustic shadowing as a feature of pediatric kidney stone ultrasound (US) may be underestimated. OBJECTIVE: The hypothesis was that the majority of stones in children have acoustic shadowing and that its specificity is high (>90%) in pediatric kidney stones. MATERIALS AND METHODS: Our retrospective observational study included children who had undergone abdominal non-enhanced computed tomography (CT) for kidney stones in a pediatric renal stone referral centre between 2015 and 2016. US examinations prior to CT were retrospectively assessed for US features such as acoustic shadowing, twinkle artifact and stone size. These features were compared to CT as reference standard. RESULTS: Thirty-one patients (median age: 13 years, range: 1-17 years) with 77 suspected kidney stones were included. The median stone size was 5 mm (interquartile range [IQR]: 5 mm). For acoustic shadowing, sensitivity was 70% (95% confidence interval [CI] 56-80%) and specificity was 100% (95% CI 56-100%). All kidney stones with a diameter ≥9 mm demonstrated shadowing. Sensitivity for twinkle artifact was 88% (95% CI 72-96%), but specificity for twinkle artifact could not be calculated due to the lack of true negatives. All false-positive stones on US demonstrated twinkle artifact, but none showed shadowing. CONCLUSION: Acoustic shadowing was demonstrated in the majority of pediatric kidney stones. Specificity was high, but this was not significant. Twinkle artifact is a sensitive US tool for detecting (pediatric) kidney calculi, but with a risk of false-positive findings.

Post-Mortem Magnetic Resonance Imaging Appearances of Feticide in Perinatal Deaths.

OBJECTIVE: The aim of this study was to characterise the imaging features seen in fetuses having undergone feticide by intracardiac potassium chloride injection compared to those of non-terminated fetuses at post-mortem magnetic resonance imaging (PMMRI). METHODS: A case-control study was performed comparing PMMRI findings between two groups of patients - those having undergone feticide were matched to a control group of miscarried/stillborn fetuses. The groups were matched according to gestational age, weight, and time since death. Two independent readers reviewed the PMMRI for thoracic, abdominal, and musculoskeletal imaging features. The Fishers exact test was conducted for differences between the patient groups. RESULTS: Twenty-six cases of feticide (mean gestation 25 weeks [20-36]) and 75 non-terminated fetuses (mean gestation 26.7 weeks [19-36]) were compared. There was a higher proportion of feticide cases demonstrating pneumothorax (23.1 vs. 1.3%, p = 0.001), haemothorax (42.3 vs. 4%, p = 0.001), pneumopericardium (30.8 vs. 5.3%, p = 0.002), and haemopericardium (34.6 vs. 0%, p = 0.0001). Intracardiac gas and intra-abdominal findings were higher in the feticide group, but the differences were not statistically significant. CONCLUSION: Characteristic PMMRI features of feticide can help improve reporter confidence in differentiating iatrogenic from physiological/pathological processes.

Primary synovial sarcomas in the paediatric and young adult population: A pictorial review.

PURPOSE: To present a pictorial essay of paediatric primary synovial sarcomas from common and less documented anatomical locations. To review the literature for the imaging characteristics and prognostic factors of this rare but important childhood malignancy. METHOD: 24 primary synovial sarcoma cases (17 male, 7 female with an age range 4-21 years) were reviewed in a collaborative effort between St Jude Children's Research Hospital and Great Ormond Street Hospital for Children. Images from 19 cases were selected for inclusion, to demonstrate the spectrum of appearances across imaging modalities, in a range of different anatomical locations (upper limb, lower limb, chest/abdomen/pelvis, and head and neck). A literature review depicting the typical radiological features and the prognostic significance of these features, was also conducted. RESULTS AND CONCLUSIONS: Primary synovial sarcoma can occur in any anatomical location, but typically within the extremities and often in close association with joints. Rarer anatomical locations described in our essay include the gastrohepatic ligament and femoral nerve sheath. We detail the salient imaging characteristics, including the T2 'triple signal' pattern which is believed to be highly specific for this particular sarcoma and in many cases predicts a poor outcome. Other poor prognostic factors include haemorrhage, lack of calcification and tumour size >10 cm. A broad range of radiological appearances are described, and in some cases related to anatomical position and size, however the presence of a soft tissue mass close to a joint in a young patient are suggestive of this diagnosis.

The nasopharyngeal airway: Estimation of the nares-to-mandible and nares-to-tragus distance in young children to assess current clinical practice.

BACKGROUND: Nasopharygeal airways are used in urgent situations to alleviate airway obstruction. Guidelines for measuring the length of the NPA differ between national and international guidelines, and the evidence base for these measurements is lacking. The purpose of this study was to measure the nares-epiglottis and nares-vocal cord distances in young children (neonates to 12 years) on 3D reconstructed Magnetic Resonance Imaging (MRI) brain volume scans, and to examine the relationship of these distances with the nares-tragus and nares-mandible distances. METHOD: One-hundred and seventy-six scans were reviewed. All patients had undergone MRI 3D brain volume imaging. The anatomical landmarks were identified and the nares-tragus, nares-mandible distances measured and compared to nares-epiglottis and nares-vocal cord distance using Osirix. RESULTS: The nares-epiglottis and nares-vocal cords distances significantly correlated (p-value <0.05). The nares-tragus distance showed strong correlation with the nares-epiglottis and nares-vocal cord distance compared to the nares-mandible distance (p-value <0.05). CONCLUSION: In conclusion, the length of a nasopharyngeal airway in children under the age of twelve years can be predicted using the nares-tragus external anatomical distance minus 10 mm.

Chest radiographs versus CT for the detection of rib fractures in children (DRIFT): a diagnostic accuracy observational study.

BACKGROUND: Internationally, chest radiography is the standard investigation for identifying rib fractures in suspected physical abuse in infants. Several small observation studies in children have found that chest CT can provide greater accuracy than radiography for fracture detection, potentially aiding medicolegal proceedings in abuse cases; however, to our knowledge, this greater accuracy has not been comprehensively evaluated. We aimed to determine differences in rib fracture detection rates between post-mortem chest radiographs and chest CT images, using forensic autopsy as the reference standard. METHODS: In this retrospective diagnostic accuracy study, we searched the Great Ormond Street Hospital (London, UK) radiology information system for all children aged 0-16 years who had a post-mortem skeletal survey (ie, full-body radiography), CT, and full autopsy between Jan 1, 2012, and Jan 1, 2017, for a purpose of death investigation. Cases were excluded if the imaging was done for a reason other than a forensic investigation or if image quality was suboptimal. Radiologists were recruited as reporters on a voluntary basis via membership databases from international radiology and post-mortem imaging societies with no specific inclusion or exclusion criteria. Reporters were sent a set of chest radiographs on a password protected and encrypted USB flash drive or via a secure filesharing website and independently reported on the presence of rib fractures, fracture location, and the confidence level of their interpretation. They were masked to the clinical information of the images. 1 month later, the same reporters were sent CTs for the same cases in a random order and asked to report on the same features. The primary objective was to compare the accuracy of detection of rib fractures by use of post-mortem chest radiographs and CTs, with autopsy data as reference standard. Accuracy was assessed by comparison of diagnostic statistics, calculated using random-intercept multilevel logistic models with reporter and patient included as cross-classified random-effects. FINDINGS: 25 cases of children (aged 1 month to 7 years), with 136 rib fractures at autopsy with paired post-mortem chest radiographs and CTs, were selected for analysis. 38 radiologists were recruited as reporters from 23 international centres; 12 (32%) were consultants, median experience of 14·5 years (range 6-27), and 26 (68%) were registrars, median experience of 4 years (range 2-9). Across all radiologists, three times as many rib fractures were correctly detected by use of chest CTs compared with chest radiography (sensitivity 44·9% [95% CI 31·7-58·9] vs 13·5% [8·1-21·5]; difference 31·4% [23·3-37·8; p<0·001]). Sensitivity for detection on the correct rib was higher by use of CT than by use of radiography (62·4% [95% CI 44·9-77·1] vs 23·1% [12·9-37·8]; difference 39·3% [31·9-42·2; p<0·001]), as was diagnosis of a patient with any rib fracture or fractures (81·5% [75·8-86·0] vs 64·7% [57·3-71·4]; difference 16·7% [11·5-22·2; p<0·001]). Radiologist confidence was higher when using CT images than radiographs (highest confidence rating given on 3317 [63·6%] of 5218 fractures for CT vs 1518 [46·6%] of 3303 on radiographs) and was a predictor for accurate fracture detection. INTERPRETATION: Chest CT provides greater accuracy than conventional chest radiography for post-mortem rib fracture detection, irrespective of radiologist experience or fracture location, although both methods detected a substantial number of false positives. The diagnostic accuracy of CT should be studied further in live children ideally in a multicentre trial to assess the applicability of our results. FUNDING: Great Ormond Street Children's Charity, Medical Research Council, Royal College of Radiologists, Research Councils UK, National Institute for Health Research.