Controlled thermal injury of bone. Report of a percutaneous technique using radiofrequency electrode and generator.

Percutaneous ablation of the trigeminal ganglion using radiofrequency energy is an accepted treatment for trigeminal neuralgia. To test the applicability of this system to the percutaneous ablation of bone neoplasms, the authors studied its effects in the normal femurs of four living dogs. Lesions were made of various duration and spaced over time to determine the extent of injury and the natural history of healing. Bone and bone marrow necrosis was limited to a sphere approximately 1 cm in diameter, regardless of the probe size or duration of heating. No complications were encountered. This technique may be useful in the treatment of certain benign neoplasms of bone that are otherwise resected.

"Single-exposure" dual energy digital radiography in the detection of pulmonary nodules and calcifications.

We studied the detectability of mineralized and non-mineralized simulated pulmonary nodules with dual energy digital radiography. "Soft tissue" and "bone" images (pixel size = 0.2 mm, 10 bits deep) were obtained with subtraction image processing after a single simultaneous exposure (100 kVp, 8 mAs, 17 mR skin exposure dose) of two storage phosphors with an interleaved 0.9 mm copper wafer. Three classes of paraffin-based nodules (0.5 to 3.0 cm) of varying mineral concentration (0, 120 and 190 mg/cm3 K2HPO4) were randomly positioned on the chest wall of two healthy volunteers to simulate calcified and non-calcified nodules. The average receiver operating characteristics (ROC) area of six readers (n = 2880 observations) showed that digital "bone" images (ROC area: 0.77 +/- 0.03) were significantly better (P less than 0.04) than conventional radiographs (OC Film, Lanex medium screens, 141 kVp, 19 mR skin exposure dose) (ROC area: 0.71 +/- 0.05) in detecting calcification in nodules. The unsubtracted digital images of lower kilovoltage were not superior to the 141 kVp conventional radiographs in a subgroup of two readers (ROC area: 0.73 +/- 0.02). Digital "soft tissue" images were equivalent to conventional chest radiographs in detecting soft tissue pulmonary nodules (ROC areas: 0.92 +/- 0.04 and 0.92 +/- 0.05, respectively.

Small bowel hemorrhage: angiographic localization and intervention.

Occult bleeding in the small bowel was localized with mesenteric angiography in 64 patients. Two groups of patients were identified. In the first group comprising 38 patients, bleeding sites were localized by the demonstration of contrast extravasation. In the second group of 26 patients, there was no extravasation. However, other angiographic findings suggested the source of bleeding. No active bleeding was necessary for a positive study in the second group. We conclude that in patients with suspected occult small bowel hemorrhage, mesenteric angiography helps localize the bleeding site. Clinically active bleeding is not always necessary, as angiographic findings other than extravasation may localize the source of hemorrhage.