日本磁気共鳴医学会雑誌
Online ISSN : 2434-0499
Print ISSN : 0914-9457
最新号
選択された号の論文の6件中1~6を表示しています
総説
  • 吉田 学誉
    原稿種別: 総説
    2020 年 40 巻 2 号 p. 48-54
    発行日: 2020/05/15
    公開日: 2020/06/15
    ジャーナル フリー

     Contrast-enhanced magnetic resonance imaging (CE-MRI) has overcome the drawback of non-CE-MRI of incomplete image information. However, the use of contrast agents requires consideration of the side effects and accident risks during injection, and the ability to respond promptly requires knowledge of treatment and management for the same.

     Side effects of contrast agents and accidents during contrast injections occur with a fixed probability. Attached documents and manuals describing side effects of contrast agents are provided by pharmaceutical companies, and many hospitals prepare manuals based on such information. However, little is known about puncture accidents during contrast agent injection, and the knowledge of treatment in case of accidents is often obtained from experience.

     Preventive measures for accidents during contrast media injections are necessary. Here, we elaborate our ideas on these safety measures.

  • 対馬 義人
    原稿種別: 総説
    2020 年 40 巻 2 号 p. 55-61
    発行日: 2020/05/15
    公開日: 2020/06/15
    ジャーナル フリー

     In the European Society of Urogenital Radiology (ESUR) guidelines 10.0, the usefulness of premedication, such as steroids, which is widely used for patients with risk factors for acute (immediate) adverse effects, has been disproved, and the recommendation of premedication has been scrapped. Certainly, there is no evidence that premedication is effective for preventing the occurrence of adverse effects or reducing the severity. How this change would be applied in the actual clinical setting is controversial.

     There is no major change in management of acute adverse effects. For this point, however, recommendation no. 3 laid down by the Japan Medical Safety Research Organization in 2019 should be referred to. If anaphylaxis is suspected, 0.3 mg of adrenaline should be administered in the anterolateral thigh muscle without hesitation. Even if you are not convinced of anaphylaxis, an intramuscular injection of adrenaline must be given immediately. Moreover, adverse effects of intramuscular injections of 0.3 mg of adrenaline are not a cause for concern, as the injection route is not intravenous.

     The knowledge of nephrogenic systemic fibrosis (NSF) is already well established. This disease was first described in the 2018 edition of the Japanese National Examination Standard for Doctors. The use of linear gadolinium-based contrast agents with low chelate stability (except EOB Primovist) is extremely limited, and occurrence probability of NSF is extremely low as long as macrocyclic gadolinium-based contrast agents are used. Patient-related risk factors are eGFR <15 mL/min/1.73 m3 and dialysis.

     Gadolinium accumulation (retention) in the body and environmental diffusion have recently been described. Although the accumulation of gadolinium in the body is widely known, its clinical significance is unknown.

     Since gadolinium is an element, once it diffuses in the environment, it is almost impossible to recover it. However, its effect on humans is unknown.

  • 丸山 裕稔
    原稿種別: 総説
    2020 年 40 巻 2 号 p. 62-71
    発行日: 2020/05/15
    公開日: 2020/06/15
    ジャーナル フリー

     Optimization of scan parameter is important for acquiring high-quality image during MRI examination. This study describes the method of constructing a human-tissue-equivalent phantom useful in optimizing the scan parameter. The main ingredient of constructing phantom is gadolinium contrast agent. T1 and T2 values can be modulated by varying the concentration of gadolinium contrast agents and composing agarose. The construction of phantom is a time and effort intensive process. However, ample scan data are acquired using phantom scans.

     Comparing the phantom scans to that of volunteer scans will help objectively evaluate the quality of scanned images. Therefore, it is possible to set optimum scan parameter.

  • 𡈽井 司
    原稿種別: 総説
    2020 年 40 巻 2 号 p. 72-81
    発行日: 2020/05/15
    公開日: 2020/06/15
    ジャーナル フリー

     Recently, magnetic resonance imaging (MRI) of many medical devices has been allowed. However, risks of MRI of clothes, materials pasted on the body, body art, etc., are unclear. Moreover, the correspondence of the MRI operator with the patient varies. MRI is performed after removing such items that are removable. However, judgments regarding the items that are difficult to remove or cannot be removed are difficult to make. Operators need to correctly understand the risk level of each item to improve patient service and find out the appropriate method for performing MRI.

     As for dental implants, we need to understand their types, structure, and characteristics. For patients with tattoos, we must explain the risk of heating. Furthermore, we place a spacer between both legs, between a hand and gantry, when performing MRI to reduce the intensity of the induced current. As for nail art, thick gloves are effective for preventing suction and heating. As for thermal clothing, we should compare the risk level and frequency of occurrences of burns due to heating with fractures due to falling. When we perform MRI without removing thermal clothing, we should recognize the possibility of overheating and try to keep the patient from sweating. When we scanned cosmetics containing iron oxide with the upper limit level of the first standard management operation mode, the skin temperature rose by approximately 3℃ in approximately 10 min. When we perform MRI without removing makeup, we should tell the patient to use the emergency call instantly if a heat sensation is felt. When a heating test was performed under the same conditions as those created by cosmetics, the volunteers felt warm immediately after the start of the scan, and the scan had to be stopped within approximately 2 min because of heat. The temperature of hair rose to approximately 42℃. We should remove as much hair powder as possible because the head heats up and distorts the image. We performed MRI with a surgical hair cap on a patient. Risks posed by hair powder are higher than those posed by cosmetics. Furthermore, if hair powder splatters, the MRI scan becomes unusable. However, these items are not contraindications to MRI, and we may be able to perform MRI with adequate knowledge and attention. However, MRI cannot always be performed safely, and the highest risks during MRI are caused by incomplete knowledge and inappropriate techniques.

  • 土橋 俊男
    原稿種別: 総説
    2020 年 40 巻 2 号 p. 82-89
    発行日: 2020/05/15
    公開日: 2020/06/15
    ジャーナル フリー

     Magnetic resonance imaging (MRI) is increasingly being performed for emergency medical care purposes. Simultaneously, the number of reports of associated incidents and accidents are also increasing since MRI is performed in an environment with a strong magnetic field.

     Among the incidents and accidents during MRI scanning, adsorption of ferromagnetic materials, such as oxygen bottles and intravenous drip stands, are the most common. During nighttime and holidays, emergency MRI is mostly performed by radiological technologists who are not specialized in the field. Thus, emergency MRI differs from scheduled MRI.

     Here, I report cases of emergency MRI performed during nighttime or holidays.

     Hospitals should understand the shortcomings of MRI performed during nighttime or holidays and come up with solutions.

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