Ionic and non-ionic contrast agent-mediated endothelial injury. Quantitative analysis of cell proliferation during endothelial repair.

PURPOSE: To quantitatively evaluate endothelial injury in vivo and to assess the time course of cellular repair after endothelial cell exposure to ionic and non-ionic contrast media. MATERIAL AND METHODS: Local changes at the cellular level following intraaortic injection of 1 ml of the ionic contrast agent ioxithalamate or 1 ml of the non-ionic contrast agent iomeprol, each with an iodine content of 300 mg/ml, were investigated using rat endothelium as an in vivo model. A sorbitol solution iso-osmolar to iomeprol served as control. Quantitative analysis of endothelial changes by autoradiography of 3H-thymidine-labeled endothelial cells was assessed after 3, 5 and 10 days, determining the 3H-thymidine index and the DNA synthesis rate. RESULTS: Ioxithalamate showed a clear harmful effect on the endothelium, with an elevated 3H-thymidine index of 7.68% on day 3 and 6.89% on day 5, versus 2.97% on day 3 and 2.55% on day 5 for iomeprol and 2.29% on day 3 and 1.91% on day 5 for the control. CONCLUSION: Ionic contrast agents lead to reversible transient focal endothelial cell injury. No such side effect was detectable for non-ionic contrast agents.

[Metal abrasion as an imaging artefact in nuclear spin tomography]. / Metallabrieb als Bildartefakt im Kernspintomogramm.

Eighteen patients with vertebral body fractures that had been stabilized by an internal spinal skeletal fixation system were prospectively examined by magnetic resonance (MR) imaging between February 1989 and November 1990 at the Department od Diagnostic Radiology of the University Hospital Freiburg 3-7 days after removal of the metallic implants. In most cases imaging artifacts in the paraspinal extensor muscles were evident on MR studies. These were found especially in the region of the previous site of the metal clip jaw bearing. In a few cases artifacts were also present within the vertebral body and/or vertebral arch, but only if the vertebral body had been surgically reconstructed by transpedicular spongiosa implantation. None or only minor artifacts by abrasion of metal were detected if the (modified Schanz's) screws appeared to be tight at surgical removal of the implants. Therefore, marked metal artifacts on MR imaging retrospectively indicate a chronic straining of the implants, which has been shown to be a risk factor for implant loosening. Additional in vitro studies with powdered metallic alloy showed that as little as 1 mg of metal could be detected as artifacts in routine spin-echo sequences. When the metallic pieces were large enough to be seen on conventional radiographs or computed tomograms, they caused severe, distorting artifacts on MR imaging. It is concluded that MR imaging is the method of choice for detection of small amounts of metal.

["Rare" urography by MRI: an alternative to IVU?]. / L'urographie "RARE" par IRM: une alternative à l'UIV?

The authors describe the technique of RARE sequences (Hennig, 1986) and their hydrographic application to urinary imaging, RARE urography. Heavily T2-weighted non-tomographic images of the urinary tract are obtained in less than 30 seconds, without contrast medium or ionizing radiation. The whole urinary tract is visualised on one image with a spatial resolution superior to that of sonography. The semiology of RARE urography is similar to that of the intravenous pyelogram. Silent kidneys are also visualised.

MR imaging of the pericardial cyst.

Findings obtained with magnetic resonance (MR) imaging in four patients with pericardial cyst are reported. MR imaging allowed not only localization and diagnosis in all four cases but characterization of cystic content. MR imaging, including RARE (rapid acquisition with relaxation enhancement) MR hydrography, which shows only liquids with T2s greater than 500 msec, proved to be useful in characterizing the fluid content of a mediastinal lesion and monitoring follow-up. In one case, MR imaging allowed differentiation of a pericardial cyst from a suspected necrotic lymph node in a patient with colic carcinoma, with subsequent correction of staging and therapy. The authors conclude that MR imaging is the method of choice for diagnosis (especially in unusual locations) and monitoring of pericardial cysts and for differential diagnosis of malignant mediastinal cystic tumors that show a solid part.

Traumatic fistula between internal iliac artery and external iliac vein.

Traumatic iliac arteriovenous fistulas (AVFs) are extremely rare, with only two cases reported in literature involving the internal iliac artery and the external iliac vein. We report the case of a 23-year-old man who sustained a gunshot injury to the left lower quadrant of his abdomen and subsequently developed unilateral leg edema of "elephantiasic proportions." Intra-arterial digital subtraction angiography six years later was essential for diagnosis and comprehension of the pathomechanism. The angiographic examination showed an internal iliac false aneurysm, as well as a high-flow arteriovenous communication between the left internal iliac artery and external iliac vein complicated by thrombotic occlusion of the left common iliac vein. The initial vascular injury and the surgical management of simple ligation were thought to be responsible for the iliac AVF and the subsequent thrombosis of the common iliac vein. On the one hand, the thrombotic occlusion of proximal vein led to a sharp increase of mean pressure in the proximal and distal arteries and in the distal vein, resulting in chronic venous insufficiency with incompetent varicose veins. On the other hand, the restriction of venous outflow produced extreme peripheral edema and large superficial veins serving as collaterals to bypass the fistula. Vascular surgery could repair the lesion by closing and bypassing the AVF.