Objective: Neuroendovascular treatments are less invasive than surgical clipping. However, the number of fluoroscopy runs may be greater when a contrast medium is used than when routine angiography is performed. Several recent studies have suggested that an iodinated contrast medium causes an increase in the radiation dose. Therefore, it is clinically important to identify physical factors causing amplification of the radiation dose. The purpose of this study was to investigate how dilution of a contrast medium with water influences the amplification effect of the radiation dose using simulation analysis.Methods: Three different types of commercially available contrast media, namely, iopamidol, iohexol, and iodixanol, were diluted 1.7-3.3 times with water and placed in the left brain parenchyma of a numerical brain phantom. Using the Monte Carlo simulation method, the phantom was exposed to X-ray beams under constant exposure conditions, and the energy absorbed in the entire region of the left brain parenchyma was estimated. At the same time, the content and volume of a contrast medium in the cerebral vessels were predicted on the basis of pharmacokinetic and fractal analyses. Results:The increase in absorbed energy was attributed to secondary electrons emitted from the contrast medium and varied depending on its content and volume. Interestingly, the amount of energy absorbed increased with increasing dilution of the contrast medium. Furthermore, the amplification effect of the radiation dose varied according to the type of contrast medium used. Conclusion:These results suggest that the amplification effect of the radiation dose is closely related to an increase in the cross-sectional area in which the X-rays interact with the contrast medium, which is caused by increased distribution of contrast medium in the cerebral vessels. When the contrast medium is diluted with water, its spread in the cerebral vessels plays a more important role than its content in the amplification effect of the radiation dose.
In this article, we report a case wherein a brain tumor was suspected based on computed tomography and magnetic resonance imaging findings. We made an initial diagnosis of malignant brain tumor based on methionine-positron emission tomography (PET) findings, but the correct diagnosis was dural arteriovenous fistula (DAVF). The patient was a 45-year-old man with DAVF who developed headache. Methionine-PET imaging showed high methionine uptake in the lesion. Although the tumor was strongly suspected from the findings of methionine-PET, the diagnosis of DAVF could be made correctly only by interpreting digital subtraction angiography and computed tomographic angiography. The findings of methionine-PET, which is considered useful in the diagnosis and denial of brain tumors, made the diagnosis of DAVF more difficult. The increased uptake of methionine-PET in DAVF is an important finding because, to our knowledge, this study is the first to report such finding. The results of this study might be useful for differential diagnoses when the diagnosis is uncertain.
Owing to the limited time since the introduction of the PulseRider (PR), inconsequential or rare complications that clinicians should be aware of remain unreported yet. Here, we report a rare complication of incomplete detachment.Case Presentation: A 50-year-old male underwent PR-assisted coil embolization for a basilar tip aneurysm. Coiling was completed, and the detachment procedure was performed using a detachment machine; the success signal was observed. The delivery microcatheter was subsequently advanced back up to the proximal markers, and no reapproximation of the proximal markers, which indicates successful detachment, was observed. However, only one of the proximal markers returned to the microcatheter, and incomplete detachment of only one leg was detected. Ultimately, electrical detachment was not possible, and physical separation by tension was achieved. Conclusion:Our case report presents a rare case of a detachment problem in the PR. The PR could not be detached, although the signal revealed successful detachment. Therefore, careful withdrawal of the delivery wire by checking not only the proximal markers but also the behavior of the entire PR and coil complex is important.
We report a case of subarachnoid hemorrhage in a 66-year-old man. A 3-mm aneurysm of the long circumflex branch of the P1 segment of the posterior cerebral artery was revealed by computed tomography angiography, and this was recognized as the bleeding source based on the hematoma distribution. In addition, the aneurysm was diagnosed as a flow-related aneurysm because the long circumflex branch was the main feeder of the tentorial dural arteriovenous fistula (dAVF). It was considered ideal to prevent re-rupture of the aneurysm and to treat the tentorial dAVF with simultaneous drainage occlusion by endovascular treatment. However, considering the shape of the aneurysm, preservation of the parent artery seemed to be difficult with endovascular treatment; therefore, only the ruptured aneurysm was treated by clipping first and then the tentorial dAVF was treated with endovascular treatment. The patient had a good clinical course without any complications. This case may be helpful in determining the ideal treatment in similar cases.
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