William H. Marshall

The most important complications of intravascular administration of contrast agents include idiosyncratic (anaphylactoid) reactions, shock, congestive heart failure, cardiac arrhythmias, acute renal failure, and neurotoxic effects. The incidence of serious neurotoxic effects is low. Entry of contrast agents into the central nervous system normally is limited but may be increased by osmotic opening of the blood-brain barrier with cerebral arteriography or arch aortography. Most neurotoxic effects are thought to represent direct effects of the contrast agent on brain or spinal cord. Adverse effects with arteriography include seizures, transient cortical blindness, brain edema, and spinal cord injury. Most cases of focal brain deficit (other than cortical blindness) are attributed to embolism secondary to the catheter. Seizures may occur with intravenous administration, especially in patients with brain tumors or other processes disrupting the blood-brain barrier. The most important adverse effects observed with myelographic agents include acute and chronic meningeal reactions with iophendylate, and seizures and transient encephalopathy with metrizamide.

Chronic beryllium disease results from beryllium exposure in the workplace and is characterized by CD4(+) T cell-mediated inflammation in the lung. Susceptibility to this disease is associated with particular HLA-DP alleles. We isolated beryllium-specific T cell lines from the lungs of affected patients. These CD4(+) T cell lines specifically responded to beryllium in culture in the presence of antigen-presenting cells that expressed class II MHC molecules HLA-DR, -DQ, and -DP. The response to beryllium was nearly completely and selectively blocked by mAb to HLA-DP. Additional studies showed that only certain HLA-DP alleles allowed presentation of beryllium. Overall, the DP alleles that presented beryllium to disease-specific T cell lines match those implicated in disease susceptibility, providing a mechanism for this association. Based on amino acid residues shared by these restricting and susceptibility DP alleles, our results provide insight into the residues of the DP beta-chain required for beryllium presentation.

PURPOSE: To correlate the imaging and pathologic features of undifferentiated (embryonal) sarcoma (UES) and account for the discrepancy between the solid appearance at ultrasound (US) and the almost cystlike appearance at computed tomography (CT) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: The clinical, pathologic, and imaging findings in 28 patients (age range, 3-49 years) with pathologically proved UES were retrospectively reviewed. All patients underwent at least one cross-sectional imaging study to include CT (27 patients), US (21 patients), and MR imaging (six patients). Tumor size, gross morphology (n = 27), histologic features, and proportion of solid and cystlike components were evaluated and correlated to the imaging findings. RESULTS: The mean transverse diameter of the tumors was 14 cm (range, 10-25 cm). At gross examination, the tumors were predominantly solid (mean, 83% of tumor volume), and pathologic and US findings were concordant. Conversely, CT scans showed low attenuation (approximately that of water) in 88% of the tumor volume and T2-weighted MR images showed high signal intensity (approximately equal to that of cerebrospinal fluid) in 89% of the tumor volume. CONCLUSION: UES shows a misleading cystlike appearance at CT and MR imaging compared with US and pathologic findings. In a child or young adult with a liver tumor, this finding is useful in making a prospective diagnosis and avoiding misguided attempts at drainage.

The CT scan with the 160 x 160 matrix demonstrated both the normal orbital anatomy and the abnormal orbital anatomy of Graves' ophthalmopathy in great detail. In Graves' ophthalmopathy, the cardinal pathologic feature of extraocular muscle enlargement was accurately reflected on the CT scan and was a distinctive, diagnostically reliable finding. Enlargement of the medial and lateral rectus muscles and of the apex of the muscle cone were the most consistent findings. The severity of the CT scan abnormalities correlated well with clinical severity. Because muscle cone abnormality was observed characteristically in those patients with sight loss, we suggest that pressure by the extraocular muscles on the optic nerve may contribute to visual acuity loss in this disease.