Absent peritoneal fluid on screening trauma ultrasonography in children: a prospective comparison with computed tomography.

BACKGROUND: Although the accuracy of focused abdominal sonography for trauma (FAST) in adults has been demonstrated, results of this technique in children have been conflicting with few comparisons against computed tomography (CT), the imaging gold standard. METHODS: A total of 160 hemodynamically stable pediatric trauma victims referred for abdominal CT initially underwent rapid screening sonography looking for free fluid. Both studies were interpreted in blinded fashion. RESULTS: Forty-four of the 160 patients had an intraabdominal injury on CT, 24 (55%) of which had normal screening sonography. Fifteen of the 44 (34%) had no free fluid on either modality. Accuracy of sonography compared with CT was 76% with a negative predictive value 81%. CONCLUSIONS: Sonography for free fluid alone is not reliable to exclude blunt intraabdominal injury in hemodynamically stable children given the considerable percentage of injured patients without free fluid. J Pediatr Surg 36:565-569.

Minimizing radiation dose for pediatric body applications of single-detector helical CT: strategies at a large Children's Hospital.

Adjustments of the standard helical CT protocols for adults can result in reduced radiation dose when imaging children. It is the radiologist's responsibility to critically evaluate the CT techniques used at their institution. Adjustments to CT protocols should be made to choose the appropriate mA and pitch when imaging children.

Splenic injury diagnosed with CT: US follow-up and healing rate in children and adolescents.

PURPOSE: To determine if pediatric splenic injury healing observed during ultrasonography (US) is related to the computed tomographic (CT) grade of injury severity, to review any delayed complications, and to formulate a grade-specific timetable for follow-up imaging. MATERIALS AND METHODS: Sixty-eight children and adolescents with CT-documented blunt splenic injury underwent US at approximate 6-week intervals to document injury healing (normal parenchyma or linear echogenic "scar"). Medical records of those not followed up to complete healing were reviewed. RESULTS: Forty-eight patients were followed up to complete injury healing: 14 of injury grade 1 (mean, 7 weeks; range, 4-12 weeks), 24 of injury grade 2 (mean, 9.5 weeks; range, 6-17 weeks), and 10 of injury grade 3 (mean, 16 weeks; range, 6-29 weeks). The difference in mean time to healing among all grades was significant (P < .02). Only two cysts were found; one decreased in size over time. No complications occurred in the 68 study patients. CONCLUSION: The time course to US-documented healing of blunt pediatric splenic injury is related to injury severity. This information can be used to tailor follow-up imaging and provide cost savings.

Tarsal coalition: a blinded comparison of MRI and CT.

OBJECTIVE: To determine how well MRI can detect tarsal coalition compared with CT, the current imaging standard. MATERIALS AND METHODS: Coronal and axial CT and MRI were performed within 3 weeks of each other on 40 feet in 20 consecutive patients referred with symptoms of possible tarsal coalition. Scans were read independently in blinded fashion by different imagers. Coalitions were either complete (osseous) or incomplete (non-osseous). Results were compared with available surgical data and clinical follow-up. RESULTS: Both modalities prospectively identified 15 coalitions (9 patients) and each missed 1 calcaneonavicular coalition. Twenty-three of the remaining 24 feet were negative for coalition on both CT and MRI. An atypical incomplete talocalcaneal coalition seen on CT was not identified prospectively on MRI. CONCLUSION: MRI is very good for detecting tarsal coalition and has a high rate of agreement with CT, the imaging "gold standard." When clinical suspicion for coalition is high, CT remains a more cost-effective diagnostic modality. If other causes for ankle pain are also entertained, MRI can be performed and provide nearly equivalent diagnostic accuracy for detecting tarsal coalition.

Fat necrosis after trauma: a benign cause of palpable lumps in children.

OBJECTIVE: Our objective is to describe the clinical entity and MR imaging appearance of fat necrosis after trauma, a benign cause of palpable soft-tissue lesions in children. A related objective is to establish MR imaging criteria that can be used reliably to differentiate this entity from other more serious causes of soft-tissue masses. CONCLUSION: Fat necrosis after trauma is a common cause of palpable lumps in children and has a benign course on long-term follow-up. When characteristic MR imaging findings are seen, conservative therapy is appropriate.

Splenic emergencies.

Of medical and surgical emergencies in the pediatric abdomen, those involving the spleen are relatively less common than other abdominal organs, though equally important to recognize. A more sophisticated clinical understanding of the important role of the spleen in immunocompetence has developed in parallel with advancements in imaging. A healthy respect for the preservation of splenic tissue has emerged, altering traditional surgical management of splenic emergencies. Non-invasive imaging has come to play a vital role in depicting acute abnormalities and in determining the need for conservative, interventional, or surgical management.

Asymptomatic, palpable, anterior chest wall lesions in children: is cross-sectional imaging necessary?

PURPOSE: To review results from cross-sectional imaging studies performed to evaluate asymptomatic anterior chest wall lesions in children. MATERIALS AND METHODS: All magnetic resonance (MR) images or computed tomographic (CT) scans of the chest obtained from 1989 to 1996 for evaluation of asymptomatic, palpable, focal, anterior chest wall lesions in otherwise healthy children were reviewed. Fifty-one children were considered for the study. Findings from 27 examinations in 27 children (13 underwent MR imaging, and 14 underwent CT) were included in the study. All children had normal radiographs of the region. Twenty-four patients did not meet the inclusion criteria and were excluded. RESULTS: The cause of the lesion palpated at physical examination was identified in 26 of 27 patients: prominent anterior convex ribs in 10 patients; "tilted" sternum in six; prominent asymmetric costal cartilage in four; bifid rib in one; and well-defined, small (< 1-cm) subcutaneous nodule adjacent to costal cartilage in five. One examination demonstrated no abnormality. Of the 27 patients, none required treatment. CONCLUSION: All palpable, asymptomatic, anterior chest wall lesions were benign and usually related to normal variations in the bone or cartilage of the chest wall. The low yield of cross-sectional imaging performed for evaluation of these asymptomatic "bumps" should be considered when decisions are made with regard to imaging.

Normal changes in the MR appearance of the spleen during early childhood.

OBJECTIVE: During the first year of life, the spleen undergoes histologic changes as the lymphoproliferative system matures. The purposes of this study were to describe the normal MR appearance of the spleen during infancy and early childhood and to correlate imaging findings with age-related histologic changes. MATERIALS AND METHODS: The spleen was evaluated on 28 abdominal MR studies obtained during the first 23 months of life. Splenic signal intensity was compared to that of the liver. Selected autopsy specimens were compared with the imaging results. RESULTS: The T2-weighted signal intensity of the spleen gradually increased from isointense to hypointense relative to the liver during the first week of life to moderately hyperintense to the liver by 8 months of age. T1-weighted splenic signal intensity gradually decreased. These findings corresponded to histological increases in white-pulp-red-pulp ratios. CONCLUSION: Before the lymphoid system completely matures, the T2-weighted signal intensity of the normal neonatal spleen appears decreased compared with the moderately hyperintense splenic signal seen in older children and adults. This finding should not be mistaken for disease.

Perflubron as a gastrointestinal MR imaging contrast agent in the pediatric population.

OBJECTIVE: To evaluate the safety and efficacy of orally administered perflubron for bowel recognition on MR imaging in a pediatric population. MATERIALS AND METHODS: A multicenter trial evaluated 39 pediatric subjects before and after ingestion of perflubron with T1-, proton-density, and T2-weighted sequences through the abdomen and/or pelvis. Post-contrast images were compared with pre-contrast images. Safety was evaluated through assessment of adverse events, clinical laboratory parameters, and vital signs. RESULTS: With regard to efficacy analysis, improvement in the percent of bowel darkened was observed for 85 % of the subjects on T1-weighted images and for 95 % of the subjects on proton-density and T2-weighted images. For images of the abdominal region, the percent of bowel darkened was improved for 90-92 % of the subjects across pulse sequences. Improvement rates for the images of the pelvic region ranged from 71 % to 100 %. For at least 75 % of the subjects, proton-density and T2-weighted images of the body and tail of the pancreas, left lobe of the liver, mesenteric fat, and pathological tissue were improved relative to predosing images. Twenty-three percent of the subjects experienced some adverse effects, most of which were minor and related to the digestive system. Clinical laboratory and vital sign evaluations revealed no trends associated with the administration of perflubron. CONCLUSION: Perflubron is a relatively safe and effective gastrointestinal MR contrast agent in the pediatric population.

MR imaging of soft-tissue masses: diagnostic efficacy and value of distinguishing between benign and malignant lesions.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of MR imaging in predicting the pathologic diagnosis of soft-tissue masses, both neoplastic and nonneoplastic, and in distinguishing benign from malignant lesions. MATERIALS AND METHODS: The imaging features of 225 soft-tissue tumors (179 benign, 46 malignant) in 222 patients were analyzed. Univariate analysis of multiple individual imaging features was done, along with stepwise logistic regression analysis of combinations of imaging features, to determine how useful these are for predicting malignancy or benignity. A subjective (group consensus) analysis of each case was done prospectively, and each tumor was placed into one of three diagnostic categories: (1) benign, diagnostic of a specific entity; (2) nonspecific, most likely benign; or (3) nonspecific, most likely malignant. Results were compared with the final diagnosis established by pathologic examination (n = 184) or imaging/clinical data (n = 41). RESULTS: By quantitative analysis, no single imaging feature or combination of features could reliably be used to distinguish benign from malignant lesions. For the subjective analysis, a correct and specific benign diagnosis could be made on the basis of MR imaging findings in 100 (44%) of the 225 tumors. For the entire cohort, the sensitivity was 78%, the specificity was 89%, the positive predictive value was 65%, and the negative predictive value was 94% for a malignant diagnosis. When the diagnostic benign tumors were excluded, the specificity and negative predictive value decreased to 76% and 86%, respectively, whereas the sensitivity and positive predictive value remained the same. CONCLUSION: Many benign soft-tissue masses can be correctly and confidently diagnosed with MR imaging. The prevalence of benign lesions among soft-tissue masses accounts for the relatively high specificity and negative predictive value that can be achieved with MR imaging for tissue characterization. However, the accuracy of MR imaging declines when these characteristic benign tumors are excluded from analysis. A significant percentage of malignant lesions may appear deceptively "benign" with the currently used criteria. For lesions whose imaging appearance is nonspecific, MR imaging is not reliable for distinguishing benign from malignant tumors, and these lesions warrant biopsy in most cases.