MEDICA.de spoke with Prof. Stefan Schönberg, Director of the Institute of Clinical Radiology and Nuclear Medicine at the University Medical Center Mannheim, Germany, about the use of a new computer tomograph and its benefits for patients.
Prof. Schönberg, why is it so hard to conduct evidence-based studies in radiation therapy?
Prof. Stefan Schönberg: Evidence-based studies that are meant to generate a high level of evidence are generally geared towards the treatment success for patients. This creates problems in traditional – pure diagnostic – radiology. That’s because diagnostic processes are subordinate to clinical decisions, which have an immediate influence on the outcome for patients, so that the contribution of diagnostic radiology is often difficult to determine in terms of outcome. These limitations can only be overcome through a strong and early-specified interdisciplinary integration of radiology into clinical trials. However, with deep integration of modern radiology into trials where clinical treatment decisions are prospectively made based on new functional and quantitative molecular data, there is the chance of generating strong evidence for these procedures. Thanks to the very close clinical, exemplary and practical, formal and infrastructural collaboration created by the Mannheim research campus M2OLIE with clinical academic subjects, radiology and nuclear medicine, respectively, we were already able to largely implement this in our facility. One good example for this is the M2TreatIT process chain defined within the scope of M2OLIE for the diagnosis and treatment of patients with liver cancer. Based on a functional 4D CT and MRT image data set fused before an intervention, patients are specifically treated with the ZEEGO interventional robotic imaging system before a scheduled transarterial chemoembolization.
How does the CT at the research campus differ from other devices?
Schönberg: Unlike traditional CT systems, the Somatom FORCE CT system available at the research campus delivers ultra rapid CT analysis at a tube voltage of just 70 kV. This low tube voltage cannot be used with adult patients in other systems, since the ejection fraction of conventional X-ray tubes is not sufficient in this voltage range. However, aside from a significant reduction in radiation dose with 70 kV exams, this technology also allows an increase in image contrast thanks to an increased presentation of even the tiniest amount of iodinated contrast agents. Thanks to the combination of these two advantages, so-called temporal resolution of dynamic 4D CT perfusion scans to measure microvascular tissue blood flow is clinically applicable in the first place and ethically justifiable due to the dose reduction.
Have you already started a study that is able to prove the advantages of the new CT scan?
Schönberg: All patients examined with the Somatom Force are studied in clinical trials based on the establishment of our newly created translational CT center at the Mannheim research campus, which is sponsored by the German Federal Ministry of Education and Research (BMBF). Numerous phantom studies have been conducted that prove the advantages of this new CT system. The focus of our studies are radiation dose reduction, the reduction of iodinated contrast agents that potentially damage the kidneys, as well as an ultra rapid CT to use with children and patients, who are not able to hold their breath during an exam. These topics are incorporated into our current oncological studies on functional microvascular imaging in oncology and therefore into the diagnostic process as defined by the research campus and the interventional treatment of patients with so-called "oligometastastic" cancer.
Why is it so difficult to show primary cancer in imaging?
Schönberg: During conventional CT scans, which are only performed during a specific timeframe after the contrast agent has been applied, very small primary cancers often show similar density values compared to the surrounding healthy tissue and can thus escape detection. Thanks to the multiple 4D CT perfusion scans done at different times, now you can quantitatively measure the microvascular blood flow in the tissue in addition to the pure density data. Even the tiniest lesions can thus be better detected through this additional multiparametric information on tissue blood flow, tissue blood volume, tissue permeability as well as the transit time of a contrast agent through the tissue.
How is the collaboration with the oncologists?
Schönberg: We are very fortunate in that we achieved excellent teamwork between radiology, oncology, radiation therapy, surgery and cardiology in Mannheim. This close collaboration enables us to provide our clinical colleagues with an understanding of functional and molecular procedures that have partially just been developed during the past few years. This ensures that this information can also be used to the patient's full benefit. This is not just important from a clinical point of view, but it is also an ethical obligation. As radiologists, we learn to truly research the questions that are clinically relevant to our colleagues thanks to this tightly knit cooperative partnership.