Time-resolved X-ray diffraction diagnostic development for the National Ignition Facility.

We present the development of an experimental platform that can collect four frames of x-ray diffraction data along a single line of sight during laser-driven, dynamic-compression experiments at the National Ignition Facility. The platform is comprised of a diagnostic imager built around ultrafast sensors with a 2-ns integration time, a custom target assembly that serves also to shield the imager, and a 10-ns duration, quasi-monochromatic x-ray source produced by laser-generated plasma. We demonstrate the performance with diffraction data for Pb ramp compressed to 150 GPa and illuminated by a Ge x-ray source that produces ∼7 × 1011, 10.25-keV photons/ns at the 400 µm diameter sample.

Penetrating radiography of imploding and stagnating beryllium liners on the Z accelerator.

The implosions of initially solid beryllium liners (tubes) have been imaged with penetrating radiography through to stagnation. These novel radiographic data reveal a high degree of azimuthal correlation in the evolving magneto-Rayleigh-Taylor structure at times just prior to (and during) stagnation, providing stringent constraints on the simulation tools used by the broader high energy density physics and inertial confinement fusion communities. To emphasize this point, comparisons to 2D and 3D radiation magnetohydrodynamics simulations are also presented. Both agreement and substantial disagreement have been found, depending on how the liner's initial outer surface finish was modeled. The various models tested, and the physical implications of these models are discussed. These comparisons exemplify the importance of the experimental data obtained.

Measurements of magneto-Rayleigh-Taylor instability growth during the implosion of initially solid Al tubes driven by the 20-MA, 100-ns Z facility.

The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast (∼100 ns) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of 25-400 µm were used to seed the instability. Radiographs with 15 µm resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to 50 µm wavelengths.

Metastatic renal cell carcinoma mimicking a meningioma.

We report a patient with renal cell carcinoma metastatic to the left trigone, which mimicked an intraventricular meningioma. The metastasis was recognized 1.3 years after removal of the primary tumor, a longer disease-free interval than any previously reported cases with brain metastases of renal cell carcinoma. The patient is now free of disease of years after resection and 17 years after the discovery of the primary tumor. Metastatic disease should be considered in all patients with prior resection of renal cell carcinoma who experience the onset of neurological disease, even after a prolonged disease-free interval. Long term survival is observed after the resection of solitary metastases, particularly if these appear after a prolonged disease-free interval.

Complications of metrizamide myelography.

Adverse neurobehavioral reactions have not been emphasized as a complication of metrizamide myelography. We encountered six such reactions in approximately 250 metrizamide myelograms. All reactions followed either cervical myelography or panmyelography via lumbar puncture. We also treated a single case of tonic-clonic seizure after intracranial spill of metrizamide in a patient without a history of seizure disorder, and a case of myoclonus following a thoracic metrizamide myelogram that showed a highgrade block. Metrizamide should not be used if an intrathecal block is suspected, or if the location to be studied makes intracranial spill difficult to avoid.

Metastasis of a rectal carcinoid to the posterior fossa.

We report the metastasis of a rectal carcinoid to the dura mater of the posterior fossa. The clinical presentation was unusual because of a 10-year latent period between resection of the primary rectal tumor and symptoms and signs of the posterior fossa metastasis; the radiological findings were atypical of a metastasis. Gastrointestinal carcinoids, apudomas, and the concept of the APUD endocrine cell family are reviewed.

Computed tomography and spinal dysraphism: clinical and phantom studies.

Two cases illustrating the value of CT in the assessment of spinal dysraphic tissue are presented. In one case, the configuration and origins of two osseous diastematomyelic spurs were shown well; in the second case, the CT recognition of a sacral lipoma led to air myelographic confirmation of the tumor and tethered cord. CT phantom studies indicated that dysraphic tissues, such as fat, cartilage, and fibrous tissue, are better identified and quantitated in the spinal canal when surrounded by air. Varying degrees of image degradation occur with water (simulating CSF) or metrizamide.

Multicentric reticulohistiocytosis (lipoid dermato-arthritis). An erosive polyarthritis with distinctive clinical, roentgenographic and pathologic features.

Detailed analysis of the progressive roentgenographic changes found in complete serial skeletal surveys of 2 men with multicentric reticulohistiocytosis (MR) have been correlated with pathologic finds and compared to features preivously reported. The lesions of MR predominate in skin and synovium and result in the following characteristic features: (1) sharply circumscribed, rapidly progressive, strikingly bilaterally symmetric erosions spreading from joint margins to articular surfaces; (2) interphalangeal joint predominance; (3) early and severe atlanto-axial involvement; (4) disproportion between severity of joint destruction and mildness of symptoms; (5) absent or minimal periosteal reaction; (6) absent or disproportionately mild osteoporosis compared to the severity of erosions; and (7) prominent, uncalcified soft tissue nodules. Since arthritis often precedes cutaneous manifestations, careful roentgenologic evaluation may play key role in early diagnosis.