Bokyung K. Han

Optimal timing for diagnostic cranial ultrasound in low-birth-weight infants: Detection of intracranial hemorrhage and ventricular dilation

Intracranial hemorrhage and posthemorrhagic ventricular dilation are common problems in small preterm infants. To determine the optimal timing for ultrasound diagnosis of these abnormalities, we studied 64 preterm infants (less than 1,500 gm) by sequential cranial ultrasonography from birth until one year of age or until death. The optimal timing for ultrasound diagnosis of intracranial hemorrhage is days 4 to 7 with follow-up at day 14. The most efficient time for ultrasound examination to diagnose ventricular dilation was day 14 with follow-up at 3 months. Intracranial hemorrhage was diagnosed by ultrasound in 35 of the 64 patients (55%). In 18 of the 64 infants (28%) significant ventricular dilation was diagnosed by ultrasound during the first three months.

Focal cortical dysplasia: comparison of MRI and FDG-PET.

PURPOSE The purpose of this work was to compare the use of MRI and [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the diagnosis of focal cortical dysplasia (FCD). METHOD Nineteen patients with surgically proven FCD were analyzed retrospectively. MRI was performed in all patients, and FDG-PET was performed in 17 patients. We compared the MR and FDG-PET findings of FCD according to the histologic findings that were classified into three grades. RESULTS Four cases were classified as Grade I, 4 cases as Grade II, and 11 cases as Grade III FCD. The lesions were detected on MRI in 9 (82%) of the 11 patients with Grade III FCD and in only 1 (13%) of the 8 patients with Grade I and II FCD. Cortical hypometabolism of the lesion was revealed on FDG-PET in 6 (86%) of the 7 patients with Grade I and II FCD and in 9 (90%) of the 10 patients with Grade III FCD. The extent of the cortical abnormality was larger on FDG-PET than on MRI in 11 (65%) of the 17 patients. CONCLUSION FDG-PET is more useful in delineating the cortical abnormality in patients with mild degrees of FCD. The extent of the lesion was larger or similar on FDG-PET compared with that of the MRI.

Thymic ultrasound. I. Intrathymic anatomy in infants

Background. The gross appearance and echogenicity of the normal thymus have been described, but specific intrathymic anatomy has not been evaluated with imaging. Subjects and methods. The thymus from a 34-week-gestation stillborn male was examined with ultrasound, and the images were correlated with microscopic findings. Thymic ultrasound was performed in 12 infants without any evidence of thymic abnormality, severe infection, or chronic illness. Images were evaluated focusing on intrathymic parenchymal anatomy and compared to the liver, spleen, and thyroid gland. Results. In the specimen thymus, ultrasound demonstrated connective-tissue septa as echogenic linear structures. The cortex was relatively hypoechoic, whereas the medulla was echogenic. The blood vessels within the septa were seen as discrete echoes. In vivo ultrasound demonstrated multiple branching echogenic linear structures and foci throughout the parenchyma, representing connective-tissue septa or blood vessels within the septa. The normal thymus was easily differentiated from the liver, spleen, and thyroid glands. Conclusion. Ultrasound is capable of demonstrating intrathymic anatomy, including the medulla, cortex, septa, and blood vessels in a fresh specimen. In vivo connective-tissue septa and blood vessels in the thymic parenchyma produce a unique echo pattern.

Thymic ultrasound. II. Diagnosis of aberrant cervical thymus.

Background. The aberrant cervical thymus is an uncommon entity to be considered in the differential diagnosis of neck masses in children, so a preoperative diagnosis has rarely been made. Objective. The purpose of this study was to assess the ultrasound features of aberrant cervical thymus and determine if recognition of the previously described unique intrathymic echo pattern allows us to make a specific diagnosis. Materials and methods. We present four patients with an aberrant cervical thymus and one patient with a cervical thymic cyst. All five patients had ultrasound, which was evaluated with special attention to the detailed echo pattern of the mass. In two patients, the mass was surgically removed. Four patients had MRI, which was evaluated. Medical records were reviewed. Results. In all cases, the mass was painless and nontender. All occurred in the expected path of the thymopharyngeal duct. In four patients, ultrasound demonstrated multiple echogenic linear structures and foci previously described as characteristic echo pattern of normal thymic tissue. In one patient, ultrasound showed a large cystic mass and echogenic solid component superiorly with a characteristic echo pattern of normal thymus. Conclusions. The ultrasound appearance of thymic tissue is unique, allowing a specific diagnosis of aberrant cervical thymus. Biopsy or other imaging is probably not indicated when it presents with typical clinical features.

Squalene-induced extrinsic lipoid pneumonia: serial radiologic findings in nine patients.

PURPOSE The purpose of this work was to demonstrate the initial and follow-up radiologic findings of squalene-induced extrinsic lipoid pneumonia. METHOD Follow-up chest radiographs (n = 9) and high-resolution CT scans (n = 3) as well as initial radiographs (n = 9) and CT scans (n = 8) were obtained in nine patients with squalene-induced extrinsic lipoid pneumonia. The serial radiologic findings were analyzed retrospectively by three chest radiologists, focusing on the pattern and distribution of parenchymal abnormalities. RESULTS The most frequent pattern of parenchymal abnormalities on chest radiograph was areas of ground-glass opacity (n = 9, bilateral 6), followed by consolidation (n = 7, bilateral 3) and poorly defined small nodules (n = 4, bilateral 2). The abnormalities were distributed in the right lower lung (n = 9), left lower lung (n = 6), and right middle lung (n = 6) zones. Initial CT scans (n = 8) demonstrated bilateral areas of ground-glass attenuation (n = 8), poorly defined centrilobular nodules (n = 8), crazy paving (n = 6), and consolidation (n = 3). The abnormalities were distributed in the right middle lobe (n = 8) and in both lower lobes (n = 5). Follow-up chest radiograph (n = 9) showed complete disappearance (n = 2) and decrease (n = 7) in the extent of the parenchymal abnormalities. Follow-up CT scans (n = 3) demonstrated decrease (n = 2) and no change (n = 1) in the extent of the abnormalities. CONCLUSION Squalene-induced extrinsic lipoid pneumonia most commonly appears as areas of ground-glass attenuation mixed with poorly defined centrilobular nodules and crazy paving on CT, being distributed mainly in the right middle and both lower lobes. The lesions are indolent and remain after cessation of squalene ingestion.

Spectrum of neurogenic tumors in the thorax : CT and pathologic findings

Neurilemomas and neurofibromas appear as round soft tissue masses at CT. Variable enhancement with either homogeneity or heterogeneity is seen in neurilemomas. Attenuation of the tumors on enhanced CT depends on histology: the extent of Antoni A or B tissue and the amount of myxoid or cystic degeneration or hemorrhage. Neurofibromas are usually homogeneous low attenuation lesions on unenhanced CT. They show homogeneous enhancement or early central blush on enhanced scan. The extent of enhancement depends on the proportions of tumor components: nerve sheath cells, collagen bundles, and areas of myxoid degeneration. Malignant nerve sheath tumors show variable attenuation. Bony destruction, pleural effusion, and metastatic pulmonary nodules may also occur. Ganglioneuromas appear as oblong homogeneous low attenuation lesions on both enhanced and unenhanced CT. This low attenuation is due to their pathologic components, with an abundant amount of myxoid matrices and a relatively small amount of ganglion cells. Neuroblastomas appear as aggressive soft tissue lesions with calcification. Ganglioneuroblastomas may appear with features in between those of ganglioneuromas and neuroblastomas. The typical location of the posterior mediastinum or the aortopulmonary window and high enhancement with administration of contrast medium at CT suggest the diagnosis of paragangliomas.

Multiple Hamartomas Associated with Intracranial Malformation

Abstract: We examined a newborn infant with multiple hamartomas, including an epidermal nevus syndrome and a giant pigmented congenital nevocellular nevus, associated with other structural developmental abnormalities such as nevus flammeus, vascular malformation, cutis aplasia congenita of the scalp, cartilage hamartoma, and a lipodermoid of the conjunctiva. This child had a significant brain malformation, diagnosed by sonography and computerized tomography, consisting of a significant enlargement of the left hemisphere not associated with asymmetry of the skull or facial bones. We suggest a careful investigation of the intracranial structures by computerized tomography and/or ultrasonography in case of either extensive linear nevus sebaceous sequence and/or giant pigmented nevocellular nevus.

Pulmonary vascular sling with tracheobronchial stenosis and hypoplasia of the right pulmonary artery.

We present a case of pulmonary sling associated with tracheobronchial stenosis, and with hypoplasia of the right lung and right pulmonary artery. Radiologic studies showed evidence of pulmonary sling and hypoplasia of the right lung; associated hypoplasia of the right pulmonary artery was also present, but not recognized initially. Narrowing of the distal trachea and right main bronchus was present, not due to compression by the anomalous left pulmonary artery, but to congenital stenosis of the trachea and right main bronchus associated with complete cartilaginous tracheobronchial rings.