MR guided placement of afterloading tubes in case of head and neck malignancies
Cell Transformation, Viral
Receptors, Cell Surface
In case of recurrencies of squamous cell carcinomas of the head and neck region the possibilities of further surgery or radiotherapy are limited, if not impossible. Since the 1960's the interstitial brachytherapy with the intratumoral placement of afterloading tubes has successfully been used as therapy. For maximum tumor control, the exact placement of the tubes is mandatory to optimize intratumoral isodose distribution. Up to date ultrasound and CT have been used as guidance methods for tube placement, but the appliance of ultrasound is limited because of wave absorbent structures like air and bone. The CT has the disadvantage of radiation exposure of both surgeon and patient. We developed a new method of placing the afterloading tubes under real time imaging condition in the open MRI. Under general anesthesia the 3D flashpoint system with a mounted biopsy needle is placed on the skin and the location and angle of penetration corrected according to the virtual line produced by the flash point system. During penetration the location and direction of the needle is guided by the obtained real time image to achieve an exact placement of the tubes within the margins of the tumor and to avoid traumatisation of adjacent structures, ie carotid artery. Using the Seldinger technique, catheters in progressing sizes were pulled over the wire until the catheter diameter was large enough for the tubes to be inserted. So far we treated 10 patients with recurrent local tumor (3 patients), recurrent metastatic lymphnode (4 patients) and boost treatment of primary radiated N3 lymphnodes (3 patients). We conclude that the open MRI offers a new possibility of guided placement of afterloading tubes. Especially in externally or endoscopically not visible tumors this method guarantees the exact and parallel placement of the tubes within the tumor margins to achieve optimal isodose distribution. The continuous real time imaging during penetration avoids traumatisation of adjacent structures.