Development and evaluation of a liquid chromatography-mass spectrometry assay and its application for the assessment of renal function.

In the present study we evaluated two commonly used iodinated contrast agents, iohexol and iodixanol, as potential markers of impaired renal function. A reversed phase LC-MS method has been developed in order to separate and quantify the two substances. The assay was linear between 0.02 and 9.7 micromol/L for iohexol and between 0.4 and 49.3 micromol/L for iodixanol (r(2) > 0.998). The recovery during sample preparation ranged from 89.1 to 112.4%. The intra- and inter-assay RSD values were 3.06-13.6% for iohexol and 4.32-12.7% for iodixanol. The validated method was subsequently applied to 17 patients scheduled for angiographic procedure displaying normal and impaired renal function. A mixture of iohexol and iodixanol was intra-arterially injected and their corresponding plasma levels were determined periodically over a 24h period following administration. The elimination of both contrast agents followed by the LC-MS approach allowed us to discriminate between patients with normal and impaired renal function at 4, 8 and 24h after administration. Our preliminary results support the predictive value of iohexol and/or iodixanol clearance in a clinical environment to screen and identify patients at risk of developing CIN.

Ultrasonography of foreign-body tenosynovitis.

A patient presented with cellulitis of the hand 4 weeks after she was injured by sea urchin spines. Ultrasonography proved useful in identifying three small fragments of spine and suggested tenosynovitis. This method should be considered the imaging technique of choice for wounds of the hand when foreign bodies are suspected.

Radio-contrast enhancement of urinary tract stones.

Most urologists treating stone disease with any method (ESWL, PCL, URS) have encountered problems of poor stone visualization with fluoroscopy. This difficulty to localize urinary tract (UT) stones or fragments may result in incomplete stone extraction, prolonged surgery and increased risk of recurrence and post-operative complications. We have sought and found means to increase the radioopacity of mineral UT stones by a simple pre-operative perfusion technique. The capacity of radioopacification has first been demonstrated in in vitro incubations of fragments of human mineral stones with aqueous solutions of barium, of the lanthanides and of the two natural actinides. Most of the incubations led to considerable radio-contrast enhancement and heavy metal incorporation, measured by X-ray fluorescence analysis. Dogs with implanted human stone fragments were used as an in vivo model. The UT were perfused through a retrograde pyelic catheter with heavy metal salts solutions, the ensuing radioopacification of the implanted UT-stones was estimated by abdominal radiographies and the metal incorporation was measured on the retrieved stones. Considerable radioopacity enhancement together with heavy metal incorporation was observed for the following elements: Sr, Ba and the lanthanides Gd and Yb. The pathological evaluation of the urothelial linings from animals treated with lanthanide salt showed no toxic effects.

[Transperineal echography of presacral masses]. / Echographie transpérinéale des masses présacrées.

We report three patients with presacral lesions, a mucocele, and abscess, and a recurrent rectal adenocarcinoma respectively. The ultrasonographic findings are described with emphasis on the transperineal approach.

[Echographic aspect of a hepatic artery aneurysm simulating a neoplastic mass of the porta hepatis]. / Aspect échographique de l'anévrisme de l'artère hépatique simulant une masse néoplasique du porta hepatis.

We report a patient with a hepatic artery aneurysm mimicking a neoplastic mass in the porta hepatis.