Perspectives of interventional and diagnostic radiology in gene therapy ofcancer

The radiologist has the opportunity to be involved at every level of the ge ne therapy effort: characterizing the disease, choosing sites for gene ther apy, contributing to gene delivery, monitoring uptake in tissues of interes t, measuring levers of target gene expression, and evaluating clinical resp onse. Development of practical and efficient methods to introduce genetic m aterial into target cells is a prerequisite to its successful use in oncolo gy. Ultrasound, computed tomography (CT) and magnetic resonance imaging (MR I) provide guidance far biopsies and intratumoral injections in the course of the therapy Besides percutaneous application, delivery via organ-specifi c vascular supply and other anatomically preformed routes are being evaluat ed. Catheters, balloons and stents will be adopted as carrier devices from vascular to oncologic gene therapy. Control of gene transcription by ionizi ng radiation in vivo represents another novel method of spatial and tempora l regulation of gene-based cancer treatment. Because of the risks involved in delivery, confirmation of the effect at the genome or phenotypic level i s highly appreciated. Radiologic monitoring during gene delivery offers an opportunity to limit the effect of inadequate targeting. The demand for ima ging gene expression in vivo by probing the molecular substrates that readi ly bind to imaging labels such as radioactive or paramagnetic metal ions is evident. Gene transfer can be visualized with scintigraphy and MRI in cell culture as well as in vivo. There is a potential usefulness of MRI in dire ctly monitoring expression of gene products with paramagnetic properties su ch as melanin.