[Magnetic resonance imaging and spectrometric study of the distribution of thermotherapeutic magnetofluid after intra-arterial administration in an experimental model of liver metastases]. / Administración intrarterial de un magnetofluido termoterapéutico en un modelo experimental de metástasis hepáticas. Estudio de distribución con resonancia magnética y espectrometría.

OBJECTIVE: To use imaging and laboratory techniques to evaluate the vascular distribution of magnetofluid in a rat model of liver metastases. MATERIAL AND METHODS: The livers of 33 WAG/Rij Crl rats were seeded with CC-531 colorectal cancer cells. After we checked tumor development, 10 rats received hepatic intra-arterial infusions of Lipiodol(®) with nanoparticles of Fe(3)O(4) in suspension, and 5 were reserved as controls. Axial STIR (TR: 3,600 ms/TE: 29 ms/TI: 130 ms) and gradient-echo (GE) (120/4 and 120/14) MRI sequences were acquired on a 1.5 T scanner. After necropsy, rats were classified into one of two stages according to tumor development: early (<10 metastases, each < 3mm) or advanced (>10 metastases, each >3 mm). Samples of liver and of metastases were taken from the 15 animals for quantification of iron concentrations by inductively coupled plasma mass spectrometry (ICP-MS). The data were analyzed using nonparametric tests; values of p < 0.05 were considered significant. RESULTS: Five animals had early tumor development and five had advanced tumor development. In the GE sequences, early stage metastases showed homogeneous signal reduction attributable to the presence of magnetofluid. Spectrometry found significant differences between the iron concentration in rats with early stage metastases and controls (p=0.002) as well as between rats with early stage metastases and those with late stage metastases (p=0.001). The ratio of exogenous iron in metastases and in liver in early stage rats was 2.6:1. The concentration of exogenous iron in the liver was significantly different from that in tumors only in early stage animals (p=0.043). CONCLUSIONS: MRI and spectrometry made it possible to evaluate the vascular distribution of magnetofluid in the liver and revealed the differences in its affinity for metastases in different stages of disease.

[Local thrombolysis in renal artery embolism]. / Fibrinolisis local en el embolismo de la arteria renal.

Renal artery embolism is an infrequent entity that occurs in patients with underlying cardiac diseases. Diagnosis is usually difficult unless the index of suspicion is high. Local thrombolysis with low-dose fibrinolytic agents is an useful therapeutic intervention. We present 2 cases of renal artery embolism treated with intra-arterial urokinase and review clinical features and therapeutic options.

[Ultrasonographic characterization of an experimental model of liver metastases from colon carcinoma in rats]. / Caracterización ecográfica de un modelo experimental de metástasis hepáticas de carcinoma de colon.

OBJECTIVE: To determine the ultrasonographic characteristics of liver metastases induced in a rat model; to evaluate the usefulness of ultrasonography in the noninvasive evaluation of tumor infiltration. MATERIAL AND METHODS: We seeded the livers of 46 WAG/RijCrl rats with CC-531 syngeneic colorectal carcinoma cells by intrasplenic inoculation. At 21, 28, 35, 42, 70 days after tumor seeding, we performed a series of ultrasonographic examinations to evaluate tumor induction in different groups of animals: 37 rats were studied with a 10 MHz linear probe and 9 were studied with a 6-18 MHz multifrequency probe. The following signs were considered indicative of tumor development: intrahepatic nodules, sinuate liver borders, lobe enlargement, and extrahepatic masses. Ultrasonographic findings were verified at autopsy. We determined the number of implants, size (less than 3mm, between 3 and 7 mm, or greater than 7 mm), and lobe location for each technique. RESULTS: Compared to the autopsy results, ultrasonography detected 64% of the animals with disease. All the extrahepatic masses were correctly diagnosed. Metastases were identified in 90% of the rats with lesions greater than 7 mm, in 75% of those with implants between 3 and 7 mm, and in 25% of those with lesions less than 3mm. In the group in which we used the 6-18 MHz probe, we detected 50% of the lesions less than 3mm. CONCLUSION: Ultrasonography was useful for monitoring the experimental model and enabled the noninvasive oncologic evaluation of the rat liver with reasonable sensitivity.