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SENSE Factor와 Shot 수 변화에 따른 IRIS Multi-Shot Diffusion의 영상변화에 관한 연구
허주,정재윤,조성봉,대창민 대한자기공명기술학회 2018 대한자기공명기술학회 학술대회 Vol.2018 No.04
Pulpose:Diffusion-weighted imaging is an useful technique to diagnose brain disease such as discriminating between acute and subacute phase of cerebral infarction, as well as detecting tiny nodules. Moreover, owing to its recognized clinical utility in muscle and skeletal field, Diffusion-weighted imaging is widely used for assessment of benign nodule and soft tissue cancer which records low-sensitivity on general MRI. However, differences in magnetization sensitivity due to the anatomical structure and the use of the EPI technique under the Diffusion Imaging in patients who have inserted metallic materials make it difficult to evaluate the correct clinical diagnosis by image distortion and artifact. In this study, we investigated the improvement of image quality due to the change of each parameter of IRIS Multi-shot Diffusion technique. which produces less metallic susceptibility artifact compared to Single-shot EPI technique based on Diffusion imaging. Materials and Methods:For the artifact evaluation on magnetization sensitivity and various other image assessments of the IRIS DWI technique, a phantom was made by inserting surgical metal pin into pork meat that is similar to the human body. The phantom images were acquired using IRIS multi-shot DWI technique. In order to check the distortion and image changes of magnetization sensitivity, the SENSE factor was set to 1, 2, 3 and 4 and the number of shot was changed to 2, 4, and 6 for each SENSOR factor value. All parameters except these two were applied in the same value. The equipment used was Philips medical system Ingenia 3.0T and the signal acquisition coil was a 32 channel SENSE head coil. All evaluation data were measured using INFINITT PACS from Infinitt healthcare. 5 professional radiologists with 5 or more years of MRI experience were measured five times each, and the mean values were calculated. Results:At the same SENSE factor, by increasing of the number of shots, distortion of magnetization susceptible artifact was decreased. Also, at the same number of shot, distortion of magnetization susceptible artifact was reduced even with increase of SENSE factor. Distortion of magnetization susceptible artifact decreased with increasing SENSE factor and shot number, however after a certain high factor, it showed the same value. It was confirmed that the change of the SENSE factor affects the image quality rather than the change of the number of shot, and the image quality was deteriorated when an excessive SENSE factor was used. Ghost artifact occurred when the SENSE factor was set to 4 or higher and the use of an excessively high SENSE factor caused a SENSE ghost artifact, which requires precise settings. Conclusion:In this study, we found efficient ways of reducing various artifacts and shortening the scan time by changing the SENSE factor and shot count of the IRIS DWI technique. Furthermore, the use of the IRIS DWI technique was able to complement the problems of the existing single shot DWI technique and it was a meaningful experiment to obtain better image quality in various body parts. By using the results of this study it will be possible to acquire images with higher diagnostic value depending on the patient's condition and the purpose of the referral evaluation.
뇌혈관 조영술에서 Neurologic complication과 Foreign-material에 대한 연구
민부기,안승원,김종만,대창민,고중석,민관홍,김성룡 대한인터벤션영상기술학회 2012 대한인터벤션영상기술학회지 Vol.15 No.1
목적: 뇌혈관 조영술 (Transfemoral Cerebral Angiogrphy: TFCA)의 부작용 (complication)에 대해 알아보고, 뇌혈관 조영술에 사용되는 시술재료에서 발생될 수 있는 Foreign material에 의한 Micro-embolism Risk에 대해 알아보고자 한다. 대상 및 방법: 뇌혈관 조영술에 사용되는 시술재료 중 공통적으로 쓰이는 조영제 자동주입기 연결선과 진단용 카테터를 대상으로 실험하였다. 실험은 뇌혈관 조영술과 동일한 조건으로 재현하였고, 새 제품과 재사용 제품을 비교하여 재사용 제품의 안전성을 분석하였다. 검사는 Filtration Method와 Cut and Microscope Method로 관찰, 분석하였다. 이때 측정 편차에 따른 오차를 줄이기 위해 방사선사 3명, 연구원 2명이 각각 동일한 방법으로 실험에 참여하였다. 결과: 실험결과 80개의 시술재료에서 8건의 Foreign material이 관찰되었다. Filtration Method에서는 Foreign material이 관찰되지 않았으나, Cut and Microscope Method에서 Foreign material이 발견되었다. 새 제품과 재사용 제품에서 모두 Foreign material이 발견되었고, 크기는 두 제품 공통적으로 100μm 미만이었다. 측정결과 발견된 Foreign material의 크기는 조영제 자동주입기 연결선에서 33.07~63.95μm, 진단용 카테터에서 24.84~52.71μm였다. 결론: 실험결과 Foreign material이 발견 되었지만 실제 시술과정을 재현한 Filtration method에서는 검출되지 않았다. Cut and Microscope method에서 발견된 7개의 입자 크기가 모두 100μm 미만으로 현미경으로 확인이 가능한 작은 입자였다. 그러나 Joseph H. Rapp는 60-100μm 미만의 입자에서도 뇌경색 (Infarction)이 발생할 수 있다.'고 발표 하였다.1 따라서 실험에서 발견된 Foreign material의 크기가 작고, 실제 조영제 주입시에 검출되지 않았더라도 complication 발생 가능성을 염두에 두고 시술에 임하여야 할 것이다.