The resistive index (RI),

Clinical history and laboratory data were used to determine that 109 of these kidneys were in normal subjects and 50 were in patients with nondilated renal disease. There was a significant difference between the mean RI of the obstructed (0.77 ± 0.05) and the nonobstructed dilated (0.63 ± 0.06) kidneys (p < .01). Analysis of the receiver-operating-characteristic curve showed an RI of 0.70 to be a good discriminatory level for obstruction, resulting in a sensitivity of 92%, a specificity of 88%, and an accuracy of 90%. All 109 normal kidneys had an RI less than 0.70. Over half (27/50) of the kidneys in patients with nondilated renal disease had an elevated RI ( 0.70).Ninety-six patients had Doppler examinations on both kidneys, and in only six patients did the RI values of each kidney differ by more than 0.10; all six were proved to have unilateral obstruction. Use of duplex Doppler sonography should improve the specificity, and thus the accuracy, of sonography in the noninvasive diagnosis of obstruction and should be used when a dilated collecting system is identified.

Distinction of the obstructed from the nonobstructed dilated renal collecting system is a difficult problem often requiring interventional procedures and pressure measurements. The authors prospectively performed duplex Doppler ultrasound (US) evaluations in 21 kidneys (obstructed, n = 14; nonobstructed, n = 7) immediately before percutaneous nephrostomy. In addition, ten of the obstructed kidneys were evaluated with follow-up Doppler US after percutaneous nephrostomy. Renal obstruction caused a change in the Doppler waveform detected by means of the resistive index (RI). Thirteen of the 14 obstructed kidneys had a RI value greater than .70, while none of the nonobstructed kidneys had a RI value exceeding .70. Relief of the obstruction resulted in a reduced RI; in nine of ten kidneys, the RI was less than or equal to .70 (similar to that of the nonobstructed kidneys). When a dilated collecting system is being imaged, additional evaluation with duplex Doppler US may help distinguish obstructed from nonobstructed dilatation, which may be of particular benefit in patients with conditions that usually predispose them to collecting system dilatation.

No abstract

OBJECTIVE. CT findings in retroperitoneal plexiform neurofibromas have been described previously only in a few case reports. This study was performed to characterize the CT features in a larger group of patients with this benign neoplasm and to delineate those findings that suggest the presence of concurrent malignant tumors of the nerve sheath. MATERIALS AND METHODS. From a review of CT scans showing retroperitoneal masses in 25 patients with neurofibromatosis type 1 , we identified 16 patients whose clinical and CT features suggested the diagnosis of plexiform neurofibromas. The diagnosis was confirmed by biopsy of the mass in three patients. In the remaining 13

No abstract

No abstract

No abstract