• Korean Journal of Radiology
• /
• 제23권2호
• /
• pp.256-263
• /
• 2022

Objective: This study aimed to evaluate the image quality and dose reduction of low-dose three-dimensional (3D) rotational angiography (RA) for evaluating intracranial aneurysms. Materials and Methods: We retrospectively evaluated the clinical data and 3D RA datasets obtained from 146 prospectively registered patients (male:female, 46:100; median age, 58 years; range, 19-81 years). The subjective image quality of 79 examinations obtained from a conventional method and 67 examinations obtained from a low-dose (5-seconds and 0.10-μGy/frame) method was assessed by two neurointerventionists using a 3-point scale for four evaluation criteria. The total image quality score was then obtained as the average of the four scores. The image quality scores were compared between the two methods using a noninferiority statistical testing, with a margin of -0.2 (i.e., score of low-dose group - score of conventional group). For the evaluation of dose reduction, dose-area product (DAP) and air kerma (AK) were analyzed and compared between the two groups. Results: The mean total image quality score ± standard deviation of the 3D RA was 2.97 ± 0.17 by reader 1 and 2.95 ± 0.20 by reader 2 for conventional group and 2.92 ± 0.30 and 2.95 ± 0.22, respectively, for low-dose group. The image quality of the 3D RA in the low-dose group was not inferior to that of the conventional group according to the total image quality score as well as individual scores for the four criteria in both readers. The mean DAP and AK per rotation were 5.87 Gy-cm² and 0.56 Gy, respectively, in the conventional group, and 1.32 Gy-cm² (p < 0.001) and 0.17 Gy (p < 0.001), respectively, in the low-dose group. Conclusion: Low-dose 3D RA was not inferior in image quality and reduced the radiation dose by 70%-77% compared to the conventional 3D RA in evaluating intracranial aneurysms.

• Investigative Magnetic Resonance Imaging
• /
• 제1권1호
• /
• pp.75-78
• /
• 1997

인체의 하지 MR Angiography(MRA)를 위한 하지전용 dual birdcage RF 코일을 설계, 제작하였으며 Volunteer실험을 하여 그 유용성을 보였다. 제안된 코일은 인체의 하지 전체의 영상을 위한 코일로 허벅지로부터 종아리까지 전체를 두 번의 영상을 통해 cover하게 된다. 기존의 방식대로 한 개의 코일을 옮기며 두 번 촬영할 경우 코일을 도중에 옮기게 외어 다리를 움직일 수밖에 없어 두 set의 영상이 완전히 연결이 되지 않지만 제안된 코일의 경우 침대만 움직이게 되므로 이런 문제가 없게 된다. 제안된 코일의 성능은 Volunteer의 하지 MRI 및 MRA를 얻어 확인했으며 임상적으로 매우 유용한 것으로 확인되었다.

• Journal of Korean Neurosurgical Society
• /
• 제58권5호
• /
• pp.471-475
• /
• 2015

Intracerebral hemorrhage (ICH) is common among various types of storkes; however, it is rare in young patients and patients who do not have any risk factors. In such cases, ICH is generally caused by vascular malformations, tumors, vasculitis, or drug abuse. Basal ganglia ICH is rarely related with distal lenticulostriate artery (LSA) aneurysm. Since the 1960s, a total of 29 distal LSA aneurysm cases causing ICH have been reported in the English literature. Despite of the small number of cases, various treatment methods have been attempted : surgical clipping, endovascular treatment, conservative treatment, superficial temporal artery-middle cerebral artery anastomosis, and gamma-knife radiosurgery. Here, we report two additional cases and review the literature. Thereupon, we discerned that young patients with deep ICH are in need of conventional cerebral angiography. Moreover, initial conservative treatment with follow-up cerebral angiography might be a good treatment option except for cases with a large amount of hematoma that necessitates emergency evacuation. If the LSA aneurysm still persists or enlarges on follow-up angiography, it should be treated surgically or endovascularly.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1989년도 춘계학술대회
• /
• pp.35-37
• /
• 1989

A new MR angiography technique using a composite sequence for the suppression of static sample signals is proposed and verified with experiments. When the composite [$90^{\circ}-{\tau}-180^{\circ}-2{\tau}-180^{\circ}-{\tau}$] sequence is applied, the large signal from the static sample is sufficiently suppressed but the signal from fresh inflow sample of which amplitude. is observed without suppression. These properties are appropriate for angiographic applications. In this paper, a modified line scan method (Block line scan angiography) incorporated with the composite [$90^{\circ}-{\tau}-180^{\circ}-2{\tau}-180^{\circ}-{\tau}$] sequence is used to obtain flow-only images, i.e., angiograms. The block line scan method improves the resolution in the flow-direction at the expense of imaging time. With the composite sequence, there is no need for subtraction procedure as in the most conventional angiographic methods. Experimental results for a phantom and a normal volunteer with KAIS 2.0 Tesla MRI system are shown.

• 대한방사선기술학회지:방사선기술과학
• /
• 제44권5호
• /
• pp.465-471
• /
• 2021

Dual-energy X-ray imaging (DEI) techniques can provide X-ray images that a certain material is suppressed or emphasized by combining two X-ray images obtained from two different x-ray spectrum. In this paper, a single-shot DEI, which uses stacked two detectors (i.e., multilayer detector), is proposed to reduce the patient dose and increase throughput in angiography. The polymethyl methacrylate (PMMA) and aluminum (Al) were selected as two basis materials for material decomposition, and material-specific images are reconstructed as a vector combination of these two materials. We investigate the contrast and noise performance of material-decomposed images using iodine phantoms with various concentrations and diameters. The single-shot DEI shows comparable performances to the conventional dual-shot DEI. In particular, the single-shot DEI shows edge enhancement in material-decomposed images due to the different spatial-resolution characteristics of upper and lower detectors. This study could be useful for designing the multilayer detector including scintillators and energy-separation filter for angiography purposes.

• Journal of Korean Neurosurgical Society
• /
• 제42권4호
• /
• pp.342-345
• /
• 2007

The azygos anterior cerebral artery, a rare anomaly in the circle of Willis in which only a single vessel supplies the medial aspects of both anterior cerebral hemispheres, is closely associated with saccular aneurysms. We present three cases of azygos anterior cerebral artery aneurysms among the 781 cerebral aneurysms surgically treated at our institution in an 11-year period. These three cases all involved elderly women who presented with subarachnoid hemorrhage. Conventional cerebral angiography and CT angiography revealed small saccular aneurysms at the distal ends of the azygos anterior cerebral arteries. These aneurysms were clipped successfully using a bifrontal interhemispheric approach. Hence, the pathogenesis of these particular aneurysms relating to hemodynamic change, associated anomalies, and surgical pitfalls is discussed with review of literature.

• 한국방사선학회논문지
• /
• 제13권5호
• /
• pp.713-720
• /
• 2019

본 연구의 목적은 컴퓨터단층 혈관조영술에서 혈관 직경을 정확하게 측정할 수 있는 새로운 측정 방법인 상대적 측정법의 기초연구 자료를 제공하고자 한다. 비이온성 요오드 조영제를 자체 제작한 관류 팬텀에 일정한 속도로 흐르게 한 후 컴퓨터단층 혈관조영술 검사를 시행하였다. 원시 데이터를 얻은 후 다중평면재구성 및 최대강도투사법으로 영상을 재구성하였고 장비 사에서 제공하는 거리측정 장치를 사용하여 팬텀의 직경을 측정하였다. 측정법은 고식적 측정법과 본 연구에서 제안하는 상대적 측정법을 사용하였다. 관류팬텀의 평균 직경은 다중평면재구성기법과 최대강도투사법 모두에서 상대적 측정법이 기존 측정법 보다 실측에 더 가깝게 나타났다(34% VS 24%, p<0.05). 하지만 두 가지 측정법 모두 실측보다 여전히 확대된 결과를 나타내고 있음을 확인하였다. 따라서 상대적 측정 방법에 대한 추가 연구가 필요한 실정이며, 이에 본 연구가 기초 자료를 제공할 수 있을 것이라 사료된다.

• 대한영상의학회지
• /
• 제81권1호
• /
• pp.119-134
• /
• 2020

복강 내 혹은 소화기계의 활동성 출혈이 있는 경우, 원인이 되는 동맥 혈관을 파악하는 것이 중요하다. 조영증강 컴퓨터단층촬영술을 이용한 혈관조영술과 고식적인 카테터 혈관조영술에서 원인이 되는 동맥을 파악하기 위해서는 기본적인 혈관 해부학을 숙지하고 있어야 한다. 기본 해부학을 숙지하고 있다면 혈관의 기원과 주행에 다양한 변이가 있다고 하더라도 이에 대한 접근이 한결 쉬워질 것이다. 영상의학에 갓 입문한 초심자들을 대상으로 하여, 복강 내 혹은 소화기계 활동성 출혈의 원인이 될 수 있는 혈관들을 파악하는 데 도움이 될만한 기본 해부학을 설명하고자 한다.

• Korean Journal of Radiology
• /
• 제24권7호
• /
• pp.681-689
• /
• 2023

Objective: Three-dimensional rotational angiography (3D-RA) is increasingly used for the evaluation of intracranial aneurysms (IAs); however, radiation exposure to the lens is a concern. We investigated the effect of head off-centering by adjusting table height on the lens dose during 3D-RA and its feasibility in patient examination. Materials and Methods: The effect of head off-centering during 3D-RA on the lens radiation dose at various table heights was investigated using a RANDO head phantom (Alderson Research Labs). We prospectively enrolled 20 patients (58.0 ± 9.4 years) with IAs who were scheduled to undergo bilateral 3D-RA. In all patients' 3D-RA, the lens dose-reduction protocol involving elevation of the examination table was applied to one internal carotid artery, and the conventional protocol was applied to the other. The lens dose was measured using photoluminescent glass dosimeters (GD-352M, AGC Techno Glass Co., LTD), and radiation dose metrics were compared between the two protocols. Image quality was quantitatively analyzed using source images for image noise, signal-to-noise ratio, and contrast-to-noise ratio. Additionally, three reviewers qualitatively assessed the image quality using a five-point Likert scale. Results: The phantom study showed that the lens dose was reduced by an average of 38% per 1 cm increase in table height. In the patient study, the dose-reduction protocol (elevating the table height by an average of 2.3 cm) led to an 83% reduction in the median dose from 4.65 mGy to 0.79 mGy (P < 0.001). There were no significant differences between dose-reduction and conventional protocols in the kerma area product (7.34 vs. 7.40 Gy·cm², P = 0.892), air kerma (75.7 vs. 75.1 mGy, P = 0.872), and image quality. Conclusion: The lens radiation dose was significantly affected by table height adjustment during 3D-RA. Intentional head off-centering by elevation of the table is a simple and effective way to reduce the lens dose in clinical practice.

• 대한의용생체공학회:의공학회지
• /
• 제2권2호
• /
• pp.109-116
• /
• 1981

The objective of this research is to develop the hardware and software systenls of the digital intravenous angiographic system. The system will be used in clinical diagnosis of cardiovascular and cerebrovascular diseases. By utilizing computer image processing technique and digital subtraction method, the system can decrease the patient's harzard and expenses in performing intravenous angiography, as compared with conventional angiograms of the arterial injection.