Hyperechoic foci in the thalamic region imaged via the posterior fontanelle: a potential mimic of thalamic pathology.

BACKGROUND: We have incidentally noted foci of increased thalamic echogenicity (FITE) on cranial sonographic images obtained via the posterior fontanelle (PF) that were not confirmed on images obtained while scanning through the anterior fontanelle (AF). Therefore, we postulated that this is a normal variant of PF imaging rather than true thalamic pathology. OBJECTIVE: The purpose of this study was to determine the incidence of FITE detected on posterior and anterior fontanelle images. MATERIALS AND METHODS: Parasagittal images were obtained bilaterally through the trigone of the lateral ventricles (including the thalami) via both the anterior and posterior fontanelles in 15 consecutive neonates (30 thalami) and evaluated independently by two pediatric radiologists for the presence or absence of FITE. Thalami were graded as grade 0 (no FITE), grade 1 (possible FITE), or grade 2 (definite FITE). Follow-up CT (n = 3) and MR (n = 1) were reviewed. RESULTS: FITE were absent in 87 % of thalami imaged via the AF, and possible FITE were present in 13 % of these cases. No cases of definite FITE were identified via the AF. However, possible FITE were identified in 33-40 % of thalami and definite FITE were seen in 33 % of thalami imaged via the PF. CONCLUSIONS: FITE seen only on images obtained through the PF on cranial sonography are a normal finding and should not be attributed to thalamic hemorrhage or ischemia.

Sonographic appearance of omental infarction in children.

BACKGROUND: Omental infarction has been previously reported in the adult surgical and imaging literature; however, the imaging features of this entity in children have received little attention. OBJECTIVE: The purpose of our study was to identify the sonographic features of omental infarction in nine children who had preoperative sonography and surgically proven omental infarction. MATERIALS AND METHODS: Sonographic images were reviewed and correlated with clinical information obtained from the patients' medical records, including clinical presentation, operative notes, and pathology reports. RESULTS: In seven of the children, sonography demonstrated a focal area of moderately increased echogenicity in the omental fat in the right abdomen (a previously described finding in omental infarction). This was an isolated finding in four of these cases. In the three cases where this was not an isolated finding, the more complex sonographic appearance led to incorrect preoperative imaging diagnoses. This finding of increased echogenicity in the omental fat was not present in the two remaining patients. CONCLUSION: Our study confirms that foci of moderately increased echogenicity in the omentum of the right abdomen, a sonographic finding described in omental infarction in a large series in adults (and in a single prior case report in children), can be seen in children as well. However, although this is a relatively unique finding, it may be absent in some cases or may be seen in conjunction with other sonographic findings which may preclude the correct preoperative sonographic diagnosis.

Correlation of ultrasound with postmortem neuropathologic studies in neonates.

We examined the correlation between cranial sonogram and postmortem examination neurodiagnoses in 51 infants (30 boys and 21 girls) who underwent cranial sonogram before death. The mean gestation of the infants at birth was 32 weeks 6 days; the mean birth weight, 1,992 gm; and the mean survival, 27 days. Most infants had several postmortem examination neurodiagnoses; therefore the postmortem examination diagnosis considered to be most significant in terms of clinical management and long-term neurologic function was chosen for each infant and designated as the primary diagnosis. The ability of the cranial sonogram to diagnose the primary diagnosis was then evaluated. The accuracy of the cranial sonogram in defining primary diagnoses was 59%. There were 21 cases (41%) in which cranial sonogram failed to define the primary diagnosis; nine of these could be explained on the basis of the timing of the ultrasound in relation to the age of the lesion or to the microscopic nature of the lesion. In 12 patients the factors causing the failure of cranial sonogram to define primary postmortem examination diagnoses could not be identified. The positive predictive value of a cranial sonogram diagnosis was 77%; the negative predictive value was 19%.

Hyperechoic caudate nuclei: a potential mimic of germinal matrix hemorrhage.

BACKGROUND: We have encountered bilateral hyperechoic foci in the region of the germinal matrix on cranial sonograms in neonates that have an appearance similar to germinal matrix hemorrhage (GMH), but are unusual either due to the age of the patient at presentation or to the evolution of the foci on follow-up. We believe that these findings represent hyperechoic caudate nuclei (HCN) rather than GMH. OBJECTIVE: To demonstrate that bilateral HCN can be seen on cranial sonography in neonates and can mimic bilateral GMH. MATERIALS AND METHODS: The cranial sonograms were reviewed in nine neonates (three term and six premature) who had HCN identified on at least one sonographic examination. CT (two patients) and MR (one patient) studies were also reviewed, as well as the neuropathological examination in one patient who died and had an autopsy. The patients' medical records were reviewed to identify any clinical markers for significant risk of perinatal ischemia. RESULTS: There was clinical evidence for risk of ischemia in five of the nine neonates. All nine patients had bilateral HCN on the initial or follow-up studies. Small cysts were seen sonographically in two patients. CT was normal in one patient and revealed a small unilateral focus of increased attenuation in one infant (very small compared to the bilateral HCN). MR was normal in one patient. Histopathological examination of the brain was normal in the one patient who died and had an autopsy. CONCLUSION: Hyperechoic caudate nuclei can occur in neonates either as a normal finding, or possibly related to ischemia, and should not always be attributed to GMH.

Simple renal cysts in children with AIDS.

Simple renal cysts are very uncommon among children. Of 50 children with AIDS that underwent computed tomography at our hospital, 4 had radiographically simple cysts. The incidence of simple renal cysts in this group of children is thus approximately 45 times that seen in normal children. To our knowledge, simple renal cysts have never been reported as a manifestation of AIDS in children. It is unknown whether or not these cysts are a manifestation of HIV nephropathy (HIVN), in which microcysts are seen pathologically. We suggest that simple renal cysts may be a finding compatible with the diagnosis of HIVN.

Medical students' attitudes toward radiology: comparison of matriculating and graduating students.

RATIONALE AND OBJECTIVES: To determine graduating medical students' perceptions of radiology and to document changes in their perceptions since they entered medical school. MATERIALS AND METHODS: A survey questionnaire was distributed to 213 graduating students. Questions were similar to those answered by the same group of students as they entered medical school nearly 4 years earlier. RESULTS: The survey was anonymously completed by 140 students. Seventy percent of students changed their choice of medical specialty since entering medical school. Factors with a major or important influence on specialty choice included intellectual excitement (96%), high patient contact (86%), opportunity for a good family life (72%), and regular hours (57%). Radiology was perceived to be a well-paid (89%), "high-tech" (86%) specialty with a healthy lifestyle (82%), regular hours (99%), and good family life (92%), but it was not perceived to offer high patient contact (1%) and was intellectually exciting to only 33% of students. This perception was unchanged from freshman year. CONCLUSIONS: This 4-year longitudinal study of a medical student class documents surprisingly little change in the perception of radiology throughout medical school. High patient contact and intellectual excitement, both factors of major or important influence on specialty choice, were thought to be lacking in radiology.

Mechanical factors associated with posterior rib fractures: laboratory and case studies.

OBJECTIVE: The objective of this study was to explore the mechanical factors associated with posterior rib fractures. MATERIALS AND METHODS: Radiographs were reviewed in ten cadavers where rib fractures were produced by opening a median sternotomy with a sternal retractor. A second study used CT to evaluate for rib fractures following digital sternal depression and anteroposterior bimanual thoracic compression in three rabbits. Lastly, two cases of accidental posterior rib fractures in children were reviewed. RESULTS: In the cadaver studies, ten rib fractures were noted, all at or medial to the costotransverse process articulations. In the rabbit study, 13 posterior rib fractures were noted, all occurring with excessive posterior levering of the ribs during bimanual compression. The accidental posterior rib fractures occurred with severe anteroposterior thoracic compression as children were decelerated into a car dashboard or struck by a car. CONCLUSION: Posterior rib fractures require excessive levering of the posterior ribs at the costotransverse process articulation. When these fractures occur in accidental situations, they require massive forces that entail similar mechanics to those occurring in abusive settings.

Performance on the radiology component of a critical clinical skills examination.

RATIONALE AND OBJECTIVES: Clinical competence certification is now required in some specialties in medicine. A Comprehensive Clinical Assessment (CCA) was created to test mastery of critical skills by students at the end of the 3rd year of medical school. METHODS: The CCA is a series of stations that test skills the faculty consider important for all medical students (eg, breast examination, electrocardiogram reading, chest pain assessment, ophthalmology photographs). The radiology station was designed to evaluate imaging skills believed to be taught and learned in the core 3rd-year rotations. RESULTS: External measures (National Board Examinations, grade point average, and overall score) of clinical performance of the 608 medical students who completed the CCA examination between 1991 and 1993 were found to be correlated with the radiology station scores. CONCLUSION: The radiology station in the CCA examination is a reproducible measure of clinical performance.

Congenital mesoblastic nephroma metastatic to the brain: a report of two cases.

Congenital mesoblastic nephroma was originally believed to be a universally benign neoplasm. More recently, aggressive congenital mesoblastic nephromas have been described with local recurrence and/or metastases. We report two patients with documented congenital mesoblastic nephroma which later metastasized to the brain.

Estimation of total lung capacity from chest radiography and chest CT in children: comparison with body plethysmography.

OBJECTIVE: The purpose of this study was to evaluate two methods of estimating lung volume using chest radiographs and one using chest CT in children. Estimates made with these techniques were compared with total lung capacity calculated with body plethysmography. MATERIALS AND METHODS: CT scans and posteroanterior and lateral radiographs of the chest were obtained in 21 children (14 girls and seven boys) for follow-up evaluation after lung transplantation. Lung volume was measured by CT using a previously validated technique of tracing the margins of the lungs on each axial CT scan. Two methods were used to estimate lung volume on chest radiographs: a technique previously described in adults and children that requires 21 measurements on posteroanterior and lateral radiographs, and a modification of a simplified technique previously reported in adults that uses only two measurements on a posteroanterior radiograph alone. Estimated lung volumes from CT and from both methods using chest radiographs were compared with total lung capacity determined from body plethysmography using regression analysis, and 95% prediction intervals were generated. RESULTS: All three methods of estimating lung volumes from radiographs correlated well with total lung capacity from plethysmography (r = .89-.92). However, we found no statistically significant or clinically meaningful difference among the methods of estimating lung volume. CONCLUSIONS: Lung volumes in children can be accurately estimated from specific measurements made on chest radiographs and on CT scans. Of the two methods tested with chest radiographs, the technique that required only two measurements from a posteroanterior chest radiograph was as accurate as the more complicated technique that required 21 measurements.

MR of right aortic arch with mirror-image branching and a left ligamentum arteriosum: an unusual cause of a vascular ring.

An unusual case is presented of a vascular ring due to a right arch with mirror-image branching and a left ligamentum arteriosum from the descending aorta to the left pulmonary artery. There have been only four previous reports of this rare arch anomaly. In addition, the patient had no underlying congenital heart lesions, which is also very unusual in patients with right aortic arch with mirror-image branching.

Ureteropelvic junction obstruction in infants mimicking ureterovesical junction obstruction on sonography.

We present two infants with ureteropelvic junction obstruction with very large renal pelves, which extended to the level of the urinary bladder. In both cases, the distal aspect of the renal pelvis simulated a dilated distal ureter, leading to the incorrect sonographic diagnosis of ureterovesical junction obstruction. Awareness of this potential pitfall on sonography is important when imaging infants with prenatal diagnosis of hydronephrosis.

Splenic volume in children: simplified estimation at CT.

Measurements of splenic length, width, and thickness were obtained from axial computed tomographic (CT) scans in 50 consecutive children (26 male and 24 female patients, aged 8 days to 19 years) referred for abdominal CT. In addition, the outline of the spleen was traced on individual axial CT sections to obtain the splenic volume with use of the software program in the CT computer. The three splenic dimensions correlated well (r = .97) with the splenic volumes obtained with the more accurate technique of tracing the splenic outline on sequential CT sections.

Resolution of splenic injury after nonoperative management.

Numerous studies have demonstrated success with nonoperative management of splenic injuries in pediatric patients. However, the resolution of the splenic injury has not been previously evaluated. The records of 50 pediatric patients with splenic injuries from blunt trauma treated nonoperatively between 1984 to 1992 were reviewed retrospectively. Abdominal computed tomography (CT) was performed at the time of injury and 6 weeks postinjury in 25 patients. These scans were reviewed and categorized by a modification of a previously reported grading system for parenchymal injury. All patients had healing of the splenic injuries, with complete resolution of the healing process observed at 6 weeks postinjury in 44%. Even those with shattered spleens (n = 6) had consistent improvement in splenic architecture, with resolution of fractures and/or contusions and return of splenic perfusion. Ten (77%) of 13 grade 1 and 2 injuries were completely resolved by the 6-week follow-up examination, whereas only one (8%) of 12 grade 3 to 5 injuries showed radiological resolution of splenic injuries. None of the 25 follow-up CT scans affected clinical decision-making or led to a deviation from the established protocol, which included a 3-month period of reduced activity. All 50 patients did well, without evidence of morbidity, mortality, or complications after return to full activity 3 months postinjury.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiographic lung disease and response of persistent pulmonary hypertension to mean airway pressure and alkalosis.

Persistent pulmonary hypertension of the newborn (PPHN) is associated with multiple cardiopulmonary diseases. Therapy often includes hyperventilation/alkalosis despite little evidence as to its efficacy in diverse conditions. To determine (1) if part of the improvement of arterial oxygen tension (PaO2) attributed to alkalosis is actually related to increased mean airway pressure (P(aw)) and (2) if the presence of radiographic pulmonary disease predicts the response to alkalosis or mean airway pressure, we reviewed records of 19 newborns with well-documented PPHN. Arterial blood gases and corresponding ventilator settings were recorded during the first day of life. To adjust for lower FiO2, corrected PaO2 (cPaO2) was calculated when the FiO2 < 1.0, such that cPaO2 = calculated arterial/alveolar oxygen ratio x (713 - PaCO2/0.8). Regression equations were obtained and mean slopes of these were compared for P(aw) vs. cPaO2, and pH vs. cPaO2 by one group t-tests (with assumed population slope of zero). There was no correlation between P(aw) and cPaO2 (mean slope +/- SD = -8.4 +/- 30.8, P = 0.25), but there was a moderate correlation between pH and cPaO2 (mean slope = 333.1 +/- 480.5, P = 0.007). Patients were then classified by chest radiographs as having severe or minimal/no lung disease. Relationships of P(aw) and pH to cPaO2 were then re-examined. No correlation was present between P(aw) and cPaO2 in 11 patients with PPHN and severe radiographic disease (mean slope = -7.4 +/- 26.9, P = 0.38) or in eight patients with PPHN and minimal/no lung disease (mean slope = -9.8 +/- 37.5, P = 0.48).(ABSTRACT TRUNCATED AT 250 WORDS)

Radiation dose reduction in CT of the pediatric pelvis.

PURPOSE: To determine whether a lower radiation dose technique can be used for computed tomography (CT) of the pediatric pelvis without significant loss of diagnostic image quality. MATERIALS AND METHODS: Thirty-six pediatric patients underwent CT at 80 mAs (experimental group), and 42 underwent CT at 240 mAs (control group). Anatomic details, image quality, and the degree of confidence in reaching a diagnosis were graded on a scale of 1 (poor) to 4 (excellent). RESULTS: The difference in perceived image quality between the experimental and control groups was not statistically significant. The mean scores for scans evaluated by the first reader were 3.88 for the experimental group and 3.92 for the control group (P = .2804). The mean scores for the second reader were 3.78 and 3.77 for the experimental and control groups, respectively (P = .8131). CONCLUSION: A substantial dose reduction can be achieved if pelvic CT is performed at 80 mAs, without a recognizable deterioration of diagnostic image quality.