gms | German Medical Science

In-vivo studies as well as clinical practice have demonstrated that with modern miniature cryoprobes adequate tissuefreezes of bone without major complications for the organism are possible. In the present in-vitro study on human vertebra we want to examine if the placement of the cryoprobe and the navigation-controlled pre-surgical planning of the cryoablation are possible. As a primary location we have chosen the spinal vertebra since they are commonly affected by primary and secondary bone tumors.

We have performed cyoablation on 12 vertebra of 4 human spinal columns. CT images were obtained for planning. The transpedicular positioning of the cryoprobe was supported by CT-fluronavigation so that the entire freezing zone (3cm) laid within the vertebra. With the help of the virtual planning of therapy fields we were able to control the ablation in a way that neural structures were not affected. Temperature measurements were recorded at the posterior part of the vertebral body, within the myelon and the spinal nerve and surrounding the cryoprobe.

All measurements were able to show that an iatrogenic harm of neural structures can be avoided. The virtual-planed and actual therapy fields during ablation showed a high correlation. The application of the microprobe through CT-fluoromatching ensured an accurate positioning.

The cryoablation of vertebral bone tumors with navigation-controlled placement of miniature cryoprobes and virtual planning of therapy fields seem well practicable. Pre-existing software for spinal navigation can be used for planning of the therapy fields. A minimal invasive application of this method is practicable.