European journal of radiology
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Since 1975-80, worldwide but mostly in Europe and Japan, sonography has become the imaging technique of choice for guiding percutaneous interventional procedures for diagnostic or therapeutic purposes. In the last 10 years, the most important advances in interventional ultrasound have occurred in therapeutic applications, fostering and facilitating the development of the so-called minimally-invasive techniques. Among all these new applications for the treatment of fluid collections, inflammatory diseases, benign and malignant tumors, the most recent dramatic advances have occurred in primary and secondary liver malignancies, which will be the focus of this review. ⋯ Multiple fibers (beam splitters) are usually required to achieve a sufficiently wide necrosis volume. The reported success rate (complete necrosis and local control of tumor growth) ranges 45-75%) of the lesions, mostly liver metastates from colorectal carcinoma. An equally low rate of complications is reported for interstitial laser photocoagulation as for radiofrequency ablation, that is no more than 2-3% of cases. (ABSTRACT TRUNCATED)
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Transcranial color Doppler sonography permits the accurate assessment of intracranial arteries. The latest Doppler units, using the color and power techniques, can show even very small flow volumes (1 x 1 mm). Low frequency (2-2.5 MHz) and very focused transducers are used in transcranial color Doppler. The skull is a very strong barrier for ultrasounds, which requires the use of some acoustic windows like some thin portions of the skull bone or some natural skull foramina. The use of echocontrast agents in color Doppler seems to increase the applications of transcranial studies. ⋯ With reference to internal carotid stenoses, the main applications of transcranial color Doppler are the study of intracranial vessels, of intracranial arterial stenosis, of arteriovenous malformations and of Willis circle aneurysms, as well as the monitoring of blood flow velocity during carotid endarterectomy. Echocontrast agents play an important role in the visualization of intracranial vessels.
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Since the assessment of lymph node metastases in head and neck cancer patients remains a major problem, the findings of different imaging methods and the role of these methods in the clinical management are compared. ⋯ CT is superior to low field MRI in depicting small pathologic lymph nodes. Unlike lymph node structure, lymph node size is not a highly reliable criterion for malignancy. The findings must be correlated in relation to the primary disease. Since FNAC under US-guidance offers additional information about enlarged lymph nodes and since it can show malignancy in small lymph nodes not found by other methods, it can be recommended for most head and neck cancer patients irrespective of the use of CT or MRI.