Focal fatty infiltration of the liver: analysis of prevalence and CT findings in children and young adults.

OBJECTIVE: Focal fatty infiltration of the liver, a benign entity that can be confused with a malignant lesion, is well characterized in adults but not in children. The goal of this study was to determine by CT the prevalence and characteristics of focal fatty infiltration in children and young adults. MATERIALS AND METHODS: We retrospectively analyzed 305 consecutive contrast-enhanced abdominal CT examinations of 218 children and young adults with no known liver disease, performed during 2 years at our institution, to identify focal fatty infiltration of the liver. The imaging criterion for focal fatty infiltration of the liver on helical CT was a geometric or ovoid low-attenuation area adjacent to the falciform ligament, gallbladder fossa, or porta hepatis. If a patient's findings met the CT criterion for focal fatty infiltration of the liver, all previous abdominal CT and MR imaging examinations performed for that patient were reviewed to assess the evolution of focal fatty infiltration of the liver. RESULTS: Of 218 children and young adults, 20 (9.2%) met the CT criterion for focal fatty infiltration of the liver. In our population, focal fatty infiltration of the liver was identified only adjacent to the falciform ligament. The prevalence of focal fatty infiltration of the liver increased significantly with advancing age: 0% for ages 1 month-4 years; 7.3% for 5-9 years; 10.2% for 10-14 years, and 25.6% for 15-19 years (p < 0.0001). CONCLUSION: Focal fatty infiltration of the liver was identified in 9.2% of patients in our population, and occurrence of this lesion in children increases significantly with advancing age. However, focal fatty infiltration of the liver is uncommon in infants and young children and should be a diagnosis of exclusion.

Pulmonary metastases at diagnosis of neuroblastoma in pediatric patients: CT findings and prognosis.

OBJECTIVE: We undertook this study to determine the frequency, CT appearance, and clinical implications of the rare occurrence of pulmonary metastases among children presenting with neuroblastoma. MATERIALS AND METHODS: A search of the Children's Cancer Group database revealed 21 of 567 children with reported lung metastases at original diagnosis of neuroblastoma. CT examinations available for 17 of these patients were analyzed retrospectively to determine if lung metastases were present, and if so, to characterize their radiographic features. RESULTS: Seventeen (3%) of 567 patients presenting with Evans stage IV neuroblastoma had confirmed pulmonary metastases at diagnosis. All had metastases to at least one site other than the lungs. The most common CT appearance of pulmonary lesions was of up to five, small, bilateral, noncalcified nodules. In nine patients (53%), the pulmonary nodules initially resolved with treatment. In this cohort, six children developed progressive disease and died, and three are still alive. All eight children whose lung lesion did not completely respond to treatment died. Overall, children with pulmonary metastases had unfavorable Shimada histology, a higher association with amplification of the MYCN oncogene (p = 0.0002), and a decreased event-free survival (p < 0.001) when compared with all children with stage IV neuroblastoma without pulmonary metastases. CONCLUSION: The search for neuroblastoma lung metastases, which occur more frequently than previously reported, is clinically important because their presence portends a poor prognosis.

Adynamic ileus after caesarean section mimicking intestinal obstruction: findings on abdominal radiographs.

The purpose of this study was to determine the spectrum of findings and the frequency of apparent distal colonic obstruction on abdominal radiographs in women with obstructive symptoms following Caesarean section. A search of radiology files yielded 21 patients who had abdominal radiographs because of obstructive symptoms during the early post-operative period. The radiographs were reviewed retrospectively to characterize the bowel gas patterns in these patients. Medical records were also reviewed to determine the treatment and patient course. Abdominal radiographs showed findings suggestive of distal colonic obstruction in 15 patients (71%), small bowel obstruction in 2 (10%), adynamic ileus in 3 (14%) and a normal bowel gas pattern in 1 (5%). In all 15 patients with apparent distal colonic obstruction, there was minimal or no gas in the rectosigmoid, with an associated pelvic mass representing the enlarged post-partum uterus, which compressed the rectosigmoid and prevented it from filling with gas. All 21 patients had rapid clinical or radiographic improvement on conservative management, indicating a transient post-operative ileus. Radiologists should be aware of the limitations of abdominal plain radiographs following Caesarean section so that a post-operative ileus is not mistaken for a distal colonic obstruction and conservative measures can be undertaken to decompress the bowel until the ileus resolves.

Cartilaginous path of physeal fracture-separations: evaluation with MR imaging--an experimental study with histologic correlation in rabbits.

PURPOSE: To define the transverse levels of intracartilaginous fractures by using magnetic resonance (MR) imaging and histologic analysis in experimental physeal fracture-separations. MATERIALS AND METHODS: Physeal fracture-separations were evaluated with MR imaging in 28 distal femurs and 28 proximal tibias of 22 immature rabbits. The intraphyseal transverse level of injury was graded as juxtaepiphyseal (germinal or proliferative zones) or juxtametaphyseal (hypertrophic zone or zone of provisional calcification). Histologic sections from 23 specimens were studied to assess correlations. We assessed nonenhanced and gadolinium-enhanced T1-weighted, intermediate-weighted, T2-weighted, and spoiled gradient-recalled-echo T1-weighted images. RESULTS: In all MR studies, the injury was visible as a cleft of signal intensity lower than the signal intensity of the physeal cartilage. Juxtaepiphyseal extension, seen in 18 (64%) of 28 fractures, was more frequent in the undulating central part of the distal femoral physis than in the flatter proximal tibial physis (P =.008). In 20 of 23 specimens, MR imaging and histologic findings had excellent correlation for the detection of fracture level and morphology. CONCLUSION: The course and level of injury within the cartilage in physeal fracture-separations can be defined with MR imaging. Extension into the juxtaepiphyseal physis, a potential risk factor for growth arrest, is detectable with MR imaging; MR imaging and histologic findings correlate well.

Gating charge differences between two voltage-gated K+ channels are due to the specific charge content of their respective S4 regions.

Voltage-gated ion channels that differ in their primary amino acid sequence in the putative voltage sensor, the S4 region, show distinct voltage-sensing characteristics. In this study, we directly compared two voltage-gated K+ channels, the mammalian RCK1 with the Drosophila Shab11, and correlated the specific amino acid content of their respective S4 regions with the distinct voltage-sensing properties they exhibit. We find that specific differences in the charge content of the S4 region are sufficient to account for the distinct gating valence of each channel. However, differences in residues inside the S4 region are not sufficient to account for each channel's characteristic voltage range of activation.