가토 간내에 Holmium-166 주입 후의 간 실질 변화

최병인,김명진,박영년,김주희,최병욱 대한자기공명의과학회 2001 Investigative Magnetic Resonance Imaging Vol.5 No.1

목적: 방사성 등위원소인 Holmium-166을 가토 간 실질 내에 경피적 주입한 후 나타나는 변화에 대한 조직학적 소견과 MR영상 소견을 알아보고자 하였다. 대상 및 방법: 12예의 가토의 간 실질 내에 Holmium-166 방사성 등위원소 10∼25 mCi를 초음파 유도하에 경피적 주입 후, MR 영상을 시행하기 전에 사망하지 않은 8예의 가토 중 4예는 급성기 (1-2주)에, 나머지 4예는 아급성기 (3-4주)에 MR 영상을 시행한 후 희생시켜, 조직표본을 얻었으며 , MR 영상을 시행하기 전에 사망한 4예 중 1예는 급성기에, 3예는 아급성기에 조직표본만을 검사하였다. 결과 괴사부위는 중심부의 액화괴사와 주변부의 응괴 괴사(coagulative necrosis). 과립성 입자의 침착, 출혈 등의 변화를 보였으며, 테두리에는 육아조직의 형성과 섬유화가 관찰되었는데, 섬유화는 급성기보다 아급성기에서 현저하였다. Holmium-166 주입양과 간 실질의 괴사 면적과는 비례하는 경향을 보였다. MR영상에서 괴사의 중앙부는 T1 강조영상에서는 저신호, T2 강조영상에서는 고신호를 나타냈으며, 조영후 역동적 영상에서는 조영증강이 되지 않았다 주변부는 T1 강조영상에서는 동등 신호 또는 약간 저신호, T2 강조영상에서는 저신호를 보였으며, 조명후 역동적 영상에서는 지 연기에서 약한 조영 증강이 말초부에서 관찰되었다. 테두리는 T1 강조영상에서는 저신호, T2 강조영상에서는 저신호, 조명후 역동적 영상에서는 초기에 약간 조영 증강하고, 후기에는 좀더 조영증강이 강해지는 소견을 보였다. 결론: 정상 간조직에 경피적으로 Holmium-166을 주입하였을 때, 조직학적으로 중앙부는 액화괴사, 주변부는 응고괴사, 테두리에는 육아 조직, 섬유화, 출혈과 과립성 입자의 침착이 관찰되었으며, MR 영상은 조직변화를 평가하는 데 유용할 것으로 생각한다. Purpose : To evaluate changes in rabbit liver parenchyma on MR images following percutaneous Holmium-166 injection, and to correlate those changes with histologic findings. Materials and methods. Holmium-166 (10-25 mCi) was percutaneously injected into the liver of rabbit (n=12) under sonographic guidance. MR images were obtained between one to two weeks (acute phasea) after the injection in four rabbits, and between two to four weeks (subacute phase) after the injection in four rabbits. Tissue specimens of these eight rabbits were obtained immediately after MR imaging. Tissue specimens were obtained without MR imaging in four rabbits (between one to two weeks in one rabbit and between three to four weeks in three rabbits). Results : Tissue specimens showed central liquefactive necrosis and peripheral coagulative necrosis containing deposition of small particles and hemorrhage. The peripheral margin of the lesions showed formation of the granulation tissue with fibrosis, which tended to be more prominent in subacute phase. The area of the necrosis tended to correlate with the dose of the radioactive Holmium-166. On MR images, the central portion of the necrosis showed hyperintensity on 72-weighted image, hypointensity on the precontrast T1-weighted images, and no enhancement on the dynamic MR images. The peripheral portion of the necrosis showed hypointensity on T2-weighted images, iso or mild hypointensity on the T1-weighted images, and mild peripheral enhancement on the delayed dynamic MR images. The peripheral margin of the lesion showed hypointensity on both T1- and T1-weighted images with increased enhancement on the delayed phase images of the dynamic MR images. Conclusion : After percutaneous Holmium-166 injection into rabbit liver parenchyma, the central portion showed liquefactive necrosis, the peripheral portion showed coagulative necrosis with granulation, fibrosis, hemorrhage and depostition of small granules. MR imaging may be helpful in evaluation of the histological change of the liver after percutaneous Holmium-166 treatment.

영상보정 및 다단계 정합을 통한 전립선 MR 영상과 병리 영상간 융합 (pp.700-704)

정주립(Julip Jung),조현희(Hyun Hee Jo),홍헬렌(Helen Hong) 한국정보과학회 2009 정보과학회 컴퓨팅의 실제 논문지 Vol.15 No.9

본 논문은 영상보정 및 다단계 정합을 통한 전립선의 MR 영상과 병리 영상 간의 융합방법을 제안한다. 제안 방법은 영상보정, 강체 정합, 비강체 정합, 영상융합의 네 단계로 이루어진다. 첫째, 영상보정 단계에서 T2 MR 강조 영상의 출혈 부위의 밝기값을 T1 MR 강조 영상의 밝기값으로 대체시키고, 2, 4장으로 분리된 병리 영상을 한장의 영상으로 만든 후 MR 영상과 동일한 해상도로 줄인다. 둘째, 전립선의 T2 MR 강조 영상과 병리 영상 간에 밝기값의 상호정보를 최적화하는 강체변환을 구한다. 셋째, TPS 와핑을 이용하여 병리 영상의 전립선 부위가 T2 MR 강조 영상의 전립선 부위에 정합되는 비강체변환을 구한다. 넷째, MR 영상과 변환을 적용시킨 병리 영상을 융합한다. 실험 결과 영상보정 및 다단계 정합 후의 전립선의 T2 MR 강조 영상과 병리 영상의 간의 평균 거리 오차는 0.8815 ㎜였고, 두 영상의 융합을 통해 T2 MR 강조 영상에서 전립선 암의 위치를 정확하게 볼 수 있었다. In this paper, we propose a method for combining MR image with histopathology image of the prostate using image correction and multi-stage registration. Our method consists of four steps. First, the intensity of prostate bleeding area on T2-weighted MR image is substituted for that on T1-weighted MR image. And two or four tissue sections of the prostate in histopathology image are combined to produce a single prostate image by manual stitching. Second, rigid registration is performed to find the affine transformations that to optimize mutual information between MR and histopathology images. Third, the result of affine registration is deformed by the TPS warping. Finally, aligned images are visualized by the intensity intermixing. Experimental results show that the prostate tumor lesion can be properly located and clearly visualized within MR images for tissue characterization comparison and that the registration error between T2-weighted MR and histopathology image was 0.0815㎜.

Comparison of Image Quality According to Phantom Fluid Material in MR-based Attenuation Correction PET Imaging in PET/MR

Chan Rok Park 한국자기학회 2021 Journal of Magnetics Vol.26 No.3

Integrated positron emission tomography (PET)/magnetic resonance (MR) imaging is gradually being used to improve the rate of cancer lesion detection in the medical field. To enhance the quality of PET/MR images, attenuation correction (AC) techniques are used by applying MR pulse sequences of the controlled aliasing in parallel imaging results in higher acceleration (CAIPI; MR ACDixon-Caipi) and the generation autocalibrating partially parallel acquisition (GRAPPA; MR ACDixon-Grappa), based on the T1-weighted two-point Dixon pulse sequence. In addition, quality control using a Jaszczak phantom filled with water and radioisotopes is frequently performed when scanning the patient. When acquiring MR-based AC PET images in the phantom study, artifacts are caused by high permittivity in water, and there is a limitation in the acquisition of uniform image quality. Therefore, the purpose of this study was to compare the image quality using phantom fluids with lower permittivity than water (sodium chloride (NaCl) NaCl+nickel sulfate (NiSO₄)) according to MR ACDixon-Caipi and MR ACDixon-Grappa pulse sequences using various quantitative analysis parameters: percent of non-uniformity (PNU), percent contrast recovery (PCR), signal to noise ratio (SNR), and coefficient of variation (COV). The results indicated that the image quality with NaCl+NiSO₄ fluid based on the results was 1.2-, 1.6-, 1.4-, and 1.1 times superior to that of NaCl fluid, respectively. In conclusion, NaCl+NiSO₄ fluid is suitable as a phantom fluid material in PET/MR images.

수술 후 요추 추간판 탈출증에서 역동적 조영증강 자기공명영상의 유용성

남지은 대한영상의학회 1999 대한영상의학회지 Vol.40 No.2

Purpose : To compare the usefulness of dynamic contrast enhanced lumber spine MR Imaging with that ofconventional delayed contrast enhanced MR imaging in the assessment of postoperative herniated lumbar disc.Materials and Methods : Forty-one postoperative herniated lumbar disc (HLD) lesions of 32 patients with back painwere examined with MR imaging(1.5T, Vision, Siemens, Germany). Five-phase dynamic 2D FLASH sagittalimages(TR/TE=118.1 msec) was obtained every 19 seconds with a 4 minutes delayed image after contrast injection. Asseen on delayed images, the discs were assessed as recurred, fibrosis, or no change. On dynamic images, thepattern of enhancement was evaluated as follows : Type I(no change in peripheral disc enhancement between theearly and late phase);or Type II(minimal internal extension of marginal smooth enhancement during the latephase);or Type III(marked internal extension f peripheral irregular enhancement). Dynamic and delayed imaging werecompared, and early epidural space enhancement with rapid wash-out was also evaluated. Results : of 41postoperative HLDs, 39 lesions showed peripheral contrast enhancement. Evaluation depended on delayed imaging, andwas as follows:recurred HLD(n=27);fibrosis(n=5);no change in postoperative disc(n=7). On dynamic contrast-enhancedimaging, enhancement patterns were Type I(n=29), Type II(n=7), and Type III(n=3). In 29 Type-I lesions, there wereno significant differences in image findings between dynamic and delayed images. However, in the lesions(typeII:n=7, type III:n=3), findings additional to those revealed by delayed images were demonstrated by dynamiccontrast-enhanced MR imaging. Nine of the ten Type-II and III lesions were diagnosed as recurred HLD. On dynamicOn dynamic images, five lesions showed early epidural space enhancement. Conclusion : dymamic contrast-enhancedlumbar spine MR imaging provided additional findings such as increased peripheral disc enhancement, and epiduralspace enhancement, which cannot be detected on conventional delayed images. Inrecurred postoperative herniatedlumbar discs, these findings are frequent.

Center Array-Sequencing 위상펼침 기법의 MR 온도영상 적용에 관한 기초연구

Kee Chin Tan,김태형,천송이,한용희,최기승,이광식,전재량,은충기,문치웅 대한자기공명의과학회 2008 Investigative Magnetic Resonance Imaging Vol.12 No.2

목적: 물체 내부의 온도를 비침습적으로 측정할 수 있는 양성자 공명 주파수 이동에 의한 MR 온도영상의 재구성에 center array-sequencing 위상펼침(PU) 기법을 적용시켜 그 성능 및 유용성을 평가하고자 하였다. 대상 및 방법: MR 온도 영상에 앞서 잡음 수준이 다른 타원형 팬텀들을 컴퓨터 모의 실험으로 제작하고 제안된 PU방법을 적용시켜 잡음에 대한 성능을 평가하였다. MR 실험은 PU 실험과 이를 이용한 온도분포영상획득 실험으로 구분하여 수행되었다. 1.5T MR 영상장치에서 무릎코일과 T2* 경사자장에코 펄스열을 이용하여 MR 영상을 얻었다. 물통, 오렌지, 아가젤 등의 팬텀을 실험 대상으로 하였고 자체 제작된 온수펌프 장치로 팬텀의 온도를 조절하였다. T 형 열전쌍 온도측정장치로 팬텀 온도를 측정하고 MR 온도영상 결과와 비교하였다. 획득된 MR영상의 위상분포는 제안된 PU방법으로 위상을 편 후 온도분포 영상을 재구성하였다. 가열 전 후의 온도변화와 MR 영상의 위상변화 관계를 이용하여 아가젤 팬텀 내의 MR온도분포 영상을 구하였다. 결과: 제안된 center array-sequencing PU 알고리즘을 이용하여 여러 팬텀에 대한 MR 위상영상의 접힘 현상을 기존 방법보다 간편하고 빠르게 제거할 수 있었고 이를 이용하여 MR 온도영상을 획득할 수 있었다. 결론: 본 연구는 제안된 center array-sequencing 위상펼침 방법이 잡음에 강하고 처리 속도가 빠를 뿐만 아니라 양성자 공명 주파수 이동의 성질을 이용한 MR 온도 영상 획득에 성공적으로 적용될 수 있음을 보였다.

분자핵의학영상 개관

정준기 대한핵의학회 2004 핵의학 분자영상 Vol.38 No.2

Molecular imaging provides a visualization of normal as well as abnormal cellular processes at a molecular or genetic level rather than at a anatomical level. Conventional medical imaging methods utilize the imaging signals produced by nonspecific physico-chemical interaction. However, molecular imaging methods utilize the imaging signals derived from specific cellular or molecular events. Because molecular and genetic changes precede anatomical change in the course of disease development, molecular imaging can detect early events in disease progression. In the near future, through molecular imaging we can understand basic mechanisms of disease, and diagnose earlier and, subsequently, treat earlier intractable diseases such as cancer, neuro-degenerative diseases, and immunologic disorders. In beginning period, nuclear medicine started as a molecular imaging, and has had a leading role in the field of molecular imaging. But recently molecular imaging has been rapidly developed. Besides nuclear imaging, molecular imaging methods such as optical imaging, magnetic resonance imaging are emerging. Each imaging modalities have their advantages and weaknesses. The opportunities from molecular imaging look bright. We should try nuclear medicine continues to have a leading role in molecular imaging. (Korean J Nucl Med 38(2):111-114, 2004)

Cine MR의 임상적 유용성

송관영,하영일,강동수,박정하,최선욱 대한신경외과학회 1998 Journal of Korean neurosurgical society Vol.27 No.6

Cascaded Residual Dense Networks for Dynamic MR Imaging with Edge-Enhanced Loss Constraint

Ziwen Ke,Yanjie Zhu,Dong Liang 대한자기공명의과학회 2020 Investigative Magnetic Resonance Imaging Vol.24 No.4

Dynamic magnetic resonance (MR) imaging has generated great research interest, because it can provide both spatial and temporal information for clinical diagnosis. However, slow imaging speed or long scanning time is still a challenge for dynamic MR imaging. Most existing methods reconstruct dynamic MR images from incomplete k -space data under the guidance of compressed sensing (CS) or lowrank theory, which suffer from long iterative reconstruction time. Recently, deep learning has shown great potential in accelerating dynamic MR. Our previous work proposed a dynamic MR imaging method with both k-space and spatial prior knowledge integrated via multi-supervised network training. Nevertheless, there was still some smoothing needed in the reconstructed images at high acceleration. In this work, we propose cascaded residual dense networks for dynamic MR imaging with edge-enhanced loss constraint, dubbed cascaded residual dense networks (CRDN). Specifically, the cascaded residual dense networks fully exploit the hierarchical features from all the convolutional layers with both local and global feature fusion. We further use the higher-degree total variation loss function, which has the edge enhancement properties, for training the networks.

Serial Changes of MR Images Throughout the Stages of Infection of Spondylodiscitis

Kwon, Tae-Hyung,Shin, Zun-Zae,Kuh, Sung-Uk,Yoon, Young-Sul,Cho, Yong-Eun,Kim, Young-Soo The Korean Neurosurgical Society 2006 Journal of Korean neurosurgical society Vol.40 No.5

Objective : Spondylodiscitis has been diagnosed by clinical, radiological and laboratory methods. MR imaging is well known as an excellent diagnostic tool for spondylodiscitis. However, the changes in MR images throughout the treatment process has not been studied. Thus we have analyzed the serial changes of MR images throughout the stages of infection. Methods : Ten patients were selected for retrospective reviewed who had been treated at our institute for infectious spondylodiscitis between 2000 and 2005. These patients had been followed-up at least six months and had taken more than a couple of series of MR scans. We classified the MR images into four groups according to the stages of treatment for the infection and compared them to the clinical and laboratory findings. Results : MR image signals changed minimally or appeared to be normal in the early stages. The progression of spondylodiscitis was characterized by a low T1 WI signal and a high T2 WI signal in disc and vertebral body. The signal changes of the MR images were then propagated and the end plate was destructed. During the treatment, the destructed endplate became stabilized and the signal intensity of both T1 and T2 WI were fixed to low-or iso-intensity. Conclusion : We can determine the serial signal changes based on MR images according to the treatment of spondylodiscitis. We can therefore determine the status of the infection and the stage of treatment, as well as the diagnosis of spondylodiscitis using serial MR images.

고식적 저자장(0.2T) 견관절 자기공명영상: SLAP 병변의 진단

조용수,백창희,이경래,신윤학 대한영상의학회 2007 대한영상의학회지 Vol.56 No.6

목적: 저자장(0.2T) 자가공명영상을 이용해 SLAP(superior labrum anterior to posterior) 병변을 얼마나 정확하게 진단하는지 알아보고자 하였다. 대상과 방법: 7개월 동안 견관절 자기공명영상을 시행 받은 150명 중 관절경 수술로 확인이 된 46명을 대상으로 하였으며 수술 소견과 자기공명영상을 전향적으로 비교하였다. 관절경 수술은 자기공명영상 촬영 후 평균 8일 뒤에 시행되었다. 저자장 자기공명영상 기기를 이용해 스핀에코 횡단면, 관상사면 T1 강조영상과 관상사면, 시상사면 T2 강조영상을 얻었으며 경사에코 횡단면과 관상사면 T2 강조영상을 얻었다. 결과: 관절경 수술 소견은 다음과 같다: SLAP II 26명, SLAP III 1명, SLAP IV 1명, SLAP I 12명, 정상 관절순 6명. SLAP 병변 중 Type 2 이상에 대한 저자장 자기공영영상의 민감도는 85.7%, 특이도는 55.5%, 양성예측도는 75%, 음성예측도는 71%, 정확도는 74%였다. 결론: 고식적 저자장 자기공명영상으로도 SLAP 병변을 비교적 정확하게 진단할 수 있다. Purpose: To evaluate the diagnostic capabilities of the low-field (0.2T) magnetic resonance (MR) system in the detection of the superior labrum anterior to posterior (SLAP) lesion. Materials and Methods: One hundred fifty patients underwent magnetic resonance imaging of the shoulder over a 7-month period. Forty-six patients underwent arthroscopic surgery, and the surgical results were correlated with the findings of the MR imaging. Arthroscopic procedures were performed within a mean of 8 days after MR imaging. MR imaging of the shoulder was conducted as follows: shoulder coil; T1-weighted spin echo, coronal-oblique images; T2-weighted gradient echo, coronal-oblique and axial images; and T2-weighted spin echo, coronal-oblique and sagittal-oblique images. Prospectively, one radiologist interpreted the MR images. Results: The results of surgery were as follows: SLAP II in 26 shoulders, SLAP III in 1 shoulder, SLAP IV in 1 shoulder, normal labrum in 6 shoulders. For SLAP lesions with a higher grade than type 2, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the low-field MRI were 85.7%, 55.5%, 75%, 71%, and 74%, respectively. Conclusion: There was relatively good agreement for the comparison of the MR results obtained using a lowfield MR system with the surgical findings for identifying SLAP lesions.