Laser-induced thermotherapy
The laser-induced thermotherapy (LITT) is a minimally invasive , d. H. Gentle therapy method for the local treatment of malignant liver tumors . By means of a laser applicator placed in the tissue, laser light with a wavelength of 1064 nm is transmitted to the tumor tissue via glass fiber, which is heated directly and thus tumor cells are destroyed. A serves as an energy source YAG laser: Nd ( neodymium - doped yttrium - aluminum - garnet - Laser ).
application areas
Laser-induced thermotherapy is increasingly being used for liver metastases (partly also in the lungs ) which, due to their unfavorable location in the body or due to previous illnesses, cannot be treated conventionally, i.e. by surgical removal. This procedure does not replace established procedures such as operations and / or chemotherapy, but rather should represent a further effective option in the interdisciplinary therapy concept. In the case of already systemic diseases, the local thermal ablation procedure LITT can be performed in addition to necessary chemotherapy and optimize the success of the treatment.
execution
First, there is a detailed preliminary examination and the patient is informed about the possible risks of the procedure. The liver tumor is usually punctured under local anesthesia in a computer tomograph (CT) , or alternatively under ultrasound control . In the next step, the laser applicator is pushed through a small hole in the abdominal skin ( percutaneously ) directly into the liver tissue. In a magnetic resonance tomograph (MRT) , the progress of the therapy can then be assessed with the help of special temperature-sensitive imaging. The duration of the procedure is about half an hour. During this time, the patient is awake (taking pain medication and sedatives) and can leave the clinic after a short stay in the hospital.
Treatment goals
The involvement of the liver is a decisive factor for the survival of the patient in a large number of oncological clinical pictures. The only therapeutic method with the aim of healing the patient is currently the surgical removal of the affected liver segment. However, since every surgical procedure can be associated with complications and poses a risk for the patient, less invasive therapy methods have been developed, which in addition to the LITT also include RFA (Radio Frequency Ablation) , AL (Afterloading) and MFH (Magnet Fluid Hyperthermia) belong. They offer the advantage of a more patient-friendly therapy with comparable prognoses and the possibility of repeated use.
restrictions
There are also some restrictions on patient use. These arise initially from the indication within the framework of the interdisciplinary, patient-specific therapy concept. Liver metastases from colon cancer or breast cancer are usually treated with this method. Other diseases, such as gastric or pancreatic cancer , are already regarded as systemic diseases when liver metastases occur and are often treated primarily with systemic chemotherapy . However, surgical removal of the tumor or LITT can also be used in selective patients. In general and in very simplified terms, there should be no pronounced metastases outside of the liver , since the focus here is always on the systemic therapy concept. Furthermore, in general terms, there must not be more than five tumors in the liver, and these must not exceed a diameter of 5 cm. These parameters are based on clinical experience and the technical limitations of LITT, whose maximum lesion size is currently limited to 5 cm.
Further developments and trends
Miniaturized applicator system
A new type of miniaturized laser applicator has now been developed. This further development of the instruments makes laser-induced thermotherapy a more patient-friendly and less complicated therapy option for the treatment of malignant liver tumors .
Treatment in open high-field MRI (oMRT)
In the future, minimally invasive procedures such as LITT are to be carried out completely with the help of magnetic resonance tomography , as this does not represent any radiation exposure for the patient and provides a far better image quality for the doctor compared to computer tomography . A generation of open high-field MRT systems (1.0 Tesla ) has recently become available for performing minimally invasive interventions, in which the complete patient care is carried out from therapy planning to treatment and follow-up examinations and monitored in a real-time process can. In contrast to conventional, tunnel-configured MRIs, these open magnetic resonance tomographs offer the great advantage that they give the doctor enough space for treatment on the patient. In addition, the open MRT systems offer more comfort, especially for anxious children and adults with claustrophobia as well as for larger patients. The work of the oMRT in the "high field" range at 1.0 Tesla also ensures good image quality and thus enables the LITT to be carried out with great precision and safety.
literature
- T Vogl, M Mack, R Straub, S Zangos, D Woitaschek, K Eichler, K. Engelmann: Thermal ablation of liver metastases. Current status and prospects . In: Radiologe , 2001 Jan, 41 (1), pp. 49-55, PMID 11220097
- T. Schmitz-Rode: Miniaturization and related trends in technology: not applicable for radiology? In: Rofo , 2003 Feb, 175 (2), pp. 152–155, PMID 12584612 (German)
- N. Hosten et al .: Laser-induced thermotherapy (LITT) of lung metastases: description of a miniaturized applicator, optimization and first patient treatments . In: Fortschr. Röntgenstrasse , Vol. 175, pp. 393-400, PMID 12635017
