The effect of buphthalmos on orbital growth in early childhood: increased orbital soft tissue volume strongly correlates with increased orbital volume.

PURPOSE: Our purpose was to evaluate the effect of increased orbital soft tissue volume on orbital growth. METHOD: Patients with unilateral or significantly asymmetric bilateral buphthalmos as determined by axial computed tomography scan were recruited. Volumetric determinations of the bony orbit with use of axial 1.5 mm sections on computed tomography were undertaken. Statistical analysis of the paired ocular length measurement and bony orbital volume measurements for each patient were performed. RESULTS: Eight patients (mean age 41 months) with a 15% or greater difference in axial length were enrolled. The mean axial length of the buphthalmic globes was 23% greater than that of the contralateral globes. Orbits harboring a buphthalmic globe had an orbital volume 11% greater than on the contralateral side. CONCLUSION: Increased orbital soft tissue volume as evidenced by buphthalmos was significantly associated with enlarged bony orbital volume. This indicates that soft tissue volume is a determinant of orbital volume and suggests that orbital tissue expanders might enhance bony development in patients with anophthalmos or microphthalmos and after early enucleation.

Temporal crescent syndrome with magnetic resonance correlation.

BACKGROUND: A young woman with a history of controlled hypertension noted a suddenly decreased peripheral temporal field in the left eye. This occurred after moderate peripartum hypertension. METHOD: A monocular peripheral temporal crescentic defect could be plotted on Goldmann visual fields despite a normal dilated peripheral retinal examination and normal disc appearance. RESULT: A dilated parieto-occipital sulcus could be seen on computed tomography, and magnetic resonance imaging showed changes consistent with atrophy and gliosis in the cuneus, precuneus, and anterior calcarine cortex surrounding the parieto-occipital sulcus. CONCLUSION: By magnetic resonance imaging, this can be seen to comprise less than 10% of the visual cortex, as suggested by the Horton and Hoyt revised Holmes map. The temporal crescent syndrome is a rare monocular retrochiasmatic visual field defect that can be correlated to a lesion along the parieto-occipital sulcus.

Detection of discrete white matter lesions after irreversible compression of MR images.

PURPOSE: To validate the use of techniques of irreversible compression of images, which can be performed using a block-based discrete cosine transform technique as defined by the Joint Photographic Experts Group, before they can be used in clinical applications, by evaluating the effect of compression on the ability of observers to detect discrete white matter lesions on MR images of the brain. METHODS: Sixty T2- and intermediate-weighted spin-echo images were compressed with varying degrees of coefficient quantization with compression ratios from 1:1 to more than 40:1, randomized, and evaluated by three observers blinded to the degree of compression. RESULTS: No significant difference in the number of lesions detected was apparent until compression ratios reached 40:1, despite a significant subjective loss in perceived image quality at 20:1. Only small (< or = 5 mm) lesions were missed at the highest degree of compression. No significant differences were observed in the detection of confluent periventricular white matter disease at any degree of compression tested. CONCLUSIONS: The use of high degrees of irreversible compression of MR images may be acceptable for diagnostic tasks.

Osmotic blood-brain barrier disruption: CT and radionuclide imaging.

PURPOSE: To compare CT and radionuclide imaging of osmotic blood-brain barrier disruption. To develop a quantitative method for imaging osmotic blood-brain barrier disruption and to see if iopamidol could be safely given intravenously in conjunction with blood-brain barrier disruption. METHODS: Forty-five blood-brain barrier disruption procedures were imaged with CT and radionuclide scans. The scans were evaluated with visual and quantitative scales. Patients were observed for adverse effects after blood-brain barrier disruption. RESULTS: There was a 4% rate of seizures in this study. There was good agreement between visual CT and radionuclide grading systems. Quantitative methods to grade disruption did not add useful information to visual interpretations. CONCLUSIONS: Nonionic iodine-based contrast medium has a lower incidence of seizures when injected intravenously in conjunction with osmotic blood-brain barrier disruption than ionic contrast material. Contrast-enhanced CT is the preferred method to image disruption because it has better spatial resolution than radionuclide techniques.

Intracranial arterial aneurysm due to birth trauma. Case report.

The authors present what is believed to be the first description of an intracranial arterial aneurysm attributable to birth trauma. A male neonate, the product of a precipitious, instrumented, footling breech delivery, exhibited seizures at the age of 18 hours. A computerized tomography scan of the head showed hemorrhage along the tentorium with a globular component at the incisura. Transfontanel Doppler ultrasound examination detected pulsatile arterial flow within the globular mass. Cerebral angiography demonstrated a 1.5-cm saccular aneurysm arising from a small distal branch of the superior cerebellar artery. The pathogenesis of aneurysms in children is obscure and controversial. Birth trauma may be responsible for some pediatric aneurysms that are currently classified as idiopathic or congenital, particularly aneurysms in the region of the tentorial incisura.

Intracranial meningioma.

This case shows many of the imaging features classically associated with meningiomas. The illustrations show common location, shape, and local effects as well as enhancement characteristics. Hyperostosis and bone destruction, a fluid "cleft" surrounding the extraaxial mass, gray-white interface displacement, and secondary intraparenchymal changes are correlated with gross pathology findings. These key features are summarized in Table 1 and the composite anatomic diagram (Fig. 6).

Identification of a patent paraumbilical vein by using Doppler sonography: importance in the diagnosis of portal hypertension.

The aim of this study was to determine if the addition of pulsed Doppler imaging to conventional sonography allows discrimination between true paraumbilical veins of portal hypertension and the apparent vein sometimes seen in the ligamentum teres in normal subjects. Conventional sonography and Doppler sonography of the ligamentum teres were performed in 33 normal subjects and in 39 patients with portal hypertension due to chronic liver disease. An apparent ligamentum teres vessel (i.e., hypoechoic channel) was identified on sonograms in 32 (97%) normal subjects (diameter 0.6-1.9 mm) and in 35 (90%) patients with portal hypertension (diameter 1.1-22 mm). In the portal hypertension group, the apparent vessel had a diameter of greater than 3 mm in only 20 patients (51%), but in 32 patients (82%) it was shown on Doppler examination to be a patent paraumbilical vein (i.e., hepatofugal venous signal). A patent paraumbilical vein on duplex Doppler sonography is therefore a specific sign of portal hypertension. The addition of Doppler imaging to conventional sonographic examination significantly increases the sensitivity for the diagnosis of portal hypertension by demonstration of a paraumbilical vein.