New pictures from the inside of the body

Images from the inside of the body: hope for image-based diagnostics

21/11/2010

The company Siemens has presented a novel full-body scanner in Munich, which combines the measuring principles of magnetic resonance tomography (MRT) and post-ion emission tomography (PET) in one device.

When commissioning the new diagnostic device in the „Klinikum rechts der Isar“ The Technical University of Munich on Saturday, the developers said that it was for the first time succeeded in combining two techniques that hitherto technically mutually exclusive. With financial support from the German Research Foundation (DFG), Siemens Healthcare has developed a combination device that is the first system in the world to combine magnetic resonance imaging (MRI) and post-ion emission tomography (PET). In this way, images of the inside of the body can be created, opening up completely new perspectives for image-based diagnostics. Because the PET examination shows how strong the metabolism is in the tissue and shows how active and aggressive possible tumors are. By means of MRI, the corresponding images of the inside of the body are delivered in 3D and with millimeter precision, the developers explained.

Of the „Biographer mMR“ The physicians are hoping to significantly improve the diagnosis of many diseases, especially cancer and dementia. Professor Markus Schwaiger, Director of the Department of Nuclear Medicine at the „Klinikum rechts der Isar“ stressed: „Here we are entering a new dimension of image-based diagnostics“ thus underlining the importance of innovation in medicine.

With the „Biographer mMR“ In the future, full-body scanners will allow doctors to recognize on a whole body image, for example, where cancerous tumors are located in the body and how active they are. Thus, tumors and metastases can now be diagnosed much earlier with the help of image-based diagnostics. However, the new combination device also offers new options for aftercare in cancer medicine. Based on the full-body picture, the treating physicians can better estimate whether chemotherapy was successful or not. With a single examination, it can be determined whether the tumor has become smaller and how its metabolic activity behaves. This provides better clues in tumor diagnostics than before, in order to assess the success of the respective treatment approach in cancer patients.

Even neurodegenerative diseases can be combined with the „Biographer mMR“ prove better, so the hope of the doctors on „Klinikum rechts der Isar“. For in neurological diseases such as dementia, the metabolic activity in certain brain areas is reduced, which can be clearly determined with the new combination device. Thus, the physicians hope to be able to diagnose dementia before the onset of clear symptoms. The early diagnosis is particularly important in such diseases, because with an early treatment often a few years can be gained, in which the patients stay longer for everyday use. With the development of ever better medication, the progression of the disease could possibly even be stopped or at least significantly slowed down in the future, so the hope of the experts. Thus, the early diagnosis would play an even more important role, because after the onset of neurodegenerative diseases, patients have little chance of recovery.

Both MRI and PET have been used as research methods for many years and the combination of diagnostic procedures has been preceded by the development of the „Biographer mMR“ possible. However, two examination appointments and a considerable additional medical expenditure were necessary for this. In addition, they gave far less accurate results, because the diagnostic images had to be superimposed from the inside of the body subsequently. However, since patients often take exactly the same position in the whole-body scanner twice despite the specialist's efforts to ensure accuracy, the precision of the images has so far been limited accordingly. With the new „Biographer mMR“ These precision problems will be resolved and the investigation will only require a measurement time of 30 minutes in the future.

Until now, it was not possible to combine the different examination procedures in one device, since the strong magnetic fields necessary for the MRI scan had disturbed the sensitive sensors of the PET devices. However, Siemens Healthcare's developers have now used novel gamma-ray detectors that work well in strong magnetic fields, and cleverly miniaturized all the necessary components of the two diagnostic devices into a single combination device that is barely larger than any of the original devices.

The detectors of a PET device must be able to detect the gamma radiation caused by the so-called tracer. Tracers are injected into the bloodstream prior to examination, usually using glucose labeled with radioactive fluorine. The product called fluorine-18-deoxyglucose migrates in the body and is absorbed by all cells that use the sugar as an energy source. In this case, cells with increased energy expenditure, such as tumor cells, take up more of the radioactively labeled glucose used as tracer, and the gamma radiation resulting from radioactive decay can be detected by the detectors of the PET devices. Whereas scintillation detectors, which do not work in strong magnetic fields, have been used in conventional devices, the Siemens developers at the „Biographer mMR“ these sensors replaced by so-called avalanche photodiodes. The new diodes are so small that the currents flowing in them can not be influenced by the magnetic fields of the MRI system, the developers explained.

The new combination device that was put into operation at the Nuclear Medicine Clinic on November 19, in the presence of the Bavarian Prime Minister Horst Seehofer, is a prototype so far. Before the commercial launch of the „Biographer mMR“ in the coming years in a clinical application test carried out by the two Munich university hospitals to prove its efficiency. When and at what price the device will then be able to buy, the Siemens development at the initial start-up could not yet say. (Fp)

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Picture: by-sassi