Is radiation exposure from radiological diagnostics causal for the development of brain tumors?
In a large international Interphone study* involving nearly 6000 patients from 13 countries, radiation exposure in patients with proven brain tumors was compared with more than 6000 control subjects who matched the patient collective in age, sex, and place of residence. For the patients with brain tumors, radiation exposure to the head from diagnostic imaging performed at least five years before tumor diagnosis was calculated.
There was no statistically sound evidence between the level of radiation exposures from previous radiological examinations for gliomas, meningiomas, and acoustic neuromas. This also turned out to be true because the examinations leading in radiation exposure, such as cranial computed tomography or cerebral angiography, were analyzed again separately.
Incidence of meningiomas:
Dose-response relationship demonstrable in nuclear medicine diagnostics
For meningiomas, however, it was shown that a small risk increase for the occurrence of this benign tumor was seen with five or more skull scans. However, a direct dose-dependent trend was not evident. However, a dose-response relationship with respect to the occurrence of meningiomas was demonstrated for nuclear medicine diagnostics:
- After two examinations with radioisotopes, the risk increases by 62%,
- with three or more such examinations by at least 117 %.
Again, an overlap of confidence intervals was evident.
The authors conclude that no increased risk for the development of malignant brain tumors in connection with radiological diagnostics can be demonstrated. Except for the development of benign tumors - meningiomas - by repeated nuclear medicine examinations.
Limitations of the study:
- the dose calculation was based on patients' memories of examinations that had taken place,
- the nuclear medicine brain examination and the isotopes used and their dose were not specified.
*(Auvinen A. et al, Int. Journal of Epidemiology 2021; https://doi.org.10.1093/ije/dyab140)
Benefits of CT Angiography for Patients with Slowly Progressive Stroke
In a study* of 31 patients who had slow-progressive apoplexy and received CT angiography, the authors demonstrated that when collateralization was readily visible on KM-CT, the progression of the infarct area was significantly slower in a main stem vascular occlusion than in a comparison collective. The size of the infarct area was verified by MR 24 hours after CT angiography. This suggests that patients with these CT findings may benefit from late intervention with removal of the thrombus even more than 24 hours after the initial stroke event.
Use of AI holds many advantages
The authors see great opportunities in the use of artificial intelligence to evaluate CT angiography. This would enable many patients to be treated in a way that would significantly improve their subsequent state of health. This is especially true for their treatment in hospitals that have neither a specialized stroke outpatient clinic nor the corresponding expertise in evaluating CT angiography, but can perform an appropriate CT examination.
*(Mass. Gen. Hospital, Regenhardt,R. et al, Radiology, Nov 2021, https://doi.org.10.1148/radiol.2021210455 online publ.)
Future trends in interventional radiology
In a very good summary, *Dieter Enzmann has presented the current status and potential future developments of interventional radiology. He assumes that in the future interventional radiology will be more differentiated from other treatment areas as well as from other aspects of diagnostic radiology. As reasons for differentiation, he lists that
- interventional measures require special knowledge and
- new imaging techniques and
- the acquisition of technical treatment skills
necessary for the then focused applications.
Enzmann calls for a clear conceptual separation between diagnostic and interventional radiology. In connection with this, he advocates subspecialization in interventional therapeutic radiology with new examination techniques and treatment methods adapted to this field.
The author assumes that in the future special devices will be developed for the application area of therapeutic interventional radiology. He considers the integration of multimodal imaging as well as appropriately applied IT technologies to be obligatory.
*(Enzmann D. Trends that Impact IR’s Future. Fortschr Röntgenstr 2022; 194: 21 – 28)