Comparison of ultrasound examination with bone scintiscan in the diagnosis of stress fractures.

BACKGROUND: We wanted to compare an ultrasound examination with the bone scintiscan to diagnose stress fractures. METHODS: Using the bone scintiscan as the reference standard, we conducted a prospective, double-blind study of 78 patients (87 percent were men, mean age 24 years) referred for bone scintiscan to rule out tibial stress fractures. After the participants were injected with radionuclide, we examined each tibia once using ultrasound adjusted for an active intensity of 2.0 W/cm2 and again with the wand turned off. The patient was blinded to the mode used. The patient's response to the ultrasound was considered positive if the patient reported pain as the wand passed over the tibia. A bone scintiscan was considered positive according to the criteria of Zwas. One sonography technician performed all examinations; both he and the nuclear medicine department were blinded to the other's findings. The final results were tabulated by a third, uninvolved party. A positive correlation between the scintiscan and ultrasound examination consisted of pain with active ultrasound and any degree of stress fracture in any part of the same tibia as found on the bone scintiscan. RESULTS: Thirty-five stress fractures were found on bone scintiscan, whereas only 15 were detected by ultrasound examination (sensitivity 43 percent). With ultrasound testing there were 22 false positives (specificity 49 percent) and 20 false negatives. These findings resulted in a positive predictive value of 41 percent and a negative predictive value of 51 percent. CONCLUSION: Ultrasound is not reliable in the diagnosis of tibial stress fractures. Bone scintiscan remains the test of choice.

Acute focal bacterial pyelonephritis.

Acute focal bacterial pyelonephritis is a renal inflammatory disease that has similarities to both pyelonephritis and renal abscess. The diagnosis is based on clinical symptoms of pyelonephritis and renal abnormalities detected on radiologic imaging studies (ultrasonography and computed tomographic scanning). Ultrasonographic examination demonstrates mass lesions in the renal cortex that resolve after appropriate antibiotic therapy. Computed tomographic studies reveal localized, wedge-shaped or circular, poorly enhancing, hypodense areas and/or swelling of the superior pole of the kidney. A voiding cystourethrogram should be done to rule out reflux as an underlying cause. Magnetic resonance imaging is not required for diagnosis or follow-up evaluation. Escherichia coli is the most common etiologic agent. All reported cases have responded to conservative therapy with extended courses of oral bactericidal antibiotics. Resolution is typically complete in one to three months. A follow-up evaluation with ultrasonography is required to document resolution.

Nonesterified fatty acids modulate steroidogenesis in mouse Leydig cells.

The effects of nonesterified fatty acids (NEFA) in modulating testosterone synthesis stimulated by luteinizing hormone (LH, 10 ng/sample) were investigated in isolated adult mouse Leydig cells. LH-stimulated testosterone production was inhibited by triglycerides (0-500 mg/dl, 50 mg/dl, 94% of the control and 500 mg/dl, 40%) and by a mixture of NEFA (100 microM, 70% of control, 200 microM, 54%, and greater than 200 microM, less than 50%). Oleic acid was a more potent inhibitor than linoleic, stearic, or palmitic acids. 8-Bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP, 5 mM) stimulated testosterone production comparable to LH but failed to reverse the inhibition of steroidogenesis produced by the NEFA. The inhibition produced by NEFA was dependent on extracellular Ca2+; and a Ca2+ channel antagonist, verapamil (10 microM), enhanced the inhibition of chylomicrons and fatty acids. 22(R)-hydroxycholesterol (10 microM) reversed the inhibition produced by NEFA. The inhibitory effects of NEFA were reversible by removal of the fatty acids. The results indicate that NEFA are potent modulators of testosterone synthesis in Leydig cells stimulated with either LH, cAMP, or intracellular Ca2+. NEFA inhibit steroidogenesis at one of the steps preceding conversion of cholesterol to pregnenolone.