[Duplex Doppler ultrasonography of intra-renal arteries. Normal and pathological aspects]. / Echo-Doppler pulsé des artères intra-rénales. Aspects normaux et pathologiques.

Duplex Doppler ultrasonography may explore renal perfusion in frequent diseases such as renal obstruction, reno-vascular hypertension, acute or chronic renal failure or diabetic renal complications by measuring Pourcelot's resistive index (RI) of renal parenchyma arteries for each kidney. A statistical and prospective study was performed on 574 patients. In healthy patients, the RI values, equal for each kidney were included in 0.45 and 0.7 (mean RI = 0.59). For other values, there was a renal pathology. Patients with idiopathic hypertension (mean RI = 0.59) or non obstructive dilatation (mean RI = 0.61) did not have an RI significantly different from healthy patients. In cases of renal obstruction, there was a significant increase in the RI for the pathological kidney (mean RI of 0.73). The sensitivity and the specificity was 100% for acute obstructions examined during the first 48 hours. In contrast, in case of renal artery stenosis greater than 70% there was a significant decrease in the RI for pathological kidney. So the RI increased significantly in both kidneys: when there was renal failure with active disease within the tubulo-interstitial compartment (mean RI of 0.77); in all cases of diabetic nephropathy (mean RI of 0.74) where the RI increased early before laboratory signs. Duplex Doppler ultrasonography may be an original method for renal explorations by providing not only morphological data but also physiological data with the perfusion study.

Computed tomographic demonstration of the posterior pituitary.

From a series of 700 thin, axial, contrast-enhanced CT scans of the sellar region, the posterior lobe of the pituitary was studied. Empty sellae and pituitary lesions larger than 8 mm in diameter were excluded from the study. Of the 320 remaining axial contrast-enhanced CT scans, the posterior lobe of the pituitary was apparent in 124 (39%) as an oval lucency 3-4 mm thick, located medially or paramedially just in front of the dorsum sellae. Normally, the anterior limit of the posterior lobe is always regularly convex forward, but in the presence of a microadenoma of the anterior lobe it may be compressed. The lesser enhancement of the posterior lobe probably correlates with the different volumes of the interstitial spaces in the anterior and in the posterior lobes. The normal picture of the posterior lobe of the pituitary must not be confused with a posteriorly located microadenoma.