• Journal of the Korean Society of Radiology
• /
• v.17 no.1
• /
• pp.53-62
• /
• 2023

The purpose of this study is to find an optimized imaging technique and evaluate its usefulness by comparing and analyzing the difference in contrast enhancement of lower extremity artery according to the patient's heart rate during lower extremity Computed Tomography Angiography examination. From January 2022 to August 22nd, 139 outpatients who visited Ajou University Hospital and underwent lower extremity angio CT examination were targeted. According to the heart rate, the groups were divided into four groups: A(HR ≤65), B(65 < HR < 80), C(80≤ HR). In addition, among patients with a heart rate of 65 or less, the heart rate was considered, and the scan was divided into D, E, F group with a delay time. The time of arrival of contrast medium and the average value of contrast enhancement were compared and analyzed. As a result of quantitative evaluation, B and C groups with a heart rate of more than 65 times had better HU values in the popliteal artery than A group (HR ≤ 65), and D group showed better HU improvement effects compared to A group (p<0.001). The comparative analysis with other groups was insignificant. The difference in heart rate affected the angiographic intensity of the lower extremities artery. Therefore, it is effective to apply the appropriate test timing for each patient by using the heart rate during the lower extremity angio CT Scan.

• Journal of the Korean Society of Radiology
• /
• v.84 no.1
• /
• pp.240-252
• /
• 2023

Purpose To assess the effect of deep learning image reconstruction (DLIR) for head CT in pediatric patients. Materials and Methods We collected 126 pediatric head CT images, which were reconstructed using filtered back projection, iterative reconstruction using adaptive statistical iterative reconstruction (ASiR)-V, and all three levels of DLIR (TrueFidelity; GE Healthcare). Each image set group was divided into four subgroups according to the patients' ages. Clinical and dose-related data were reviewed. Quantitative parameters, including the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), and qualitative parameters, including noise, gray matter-white matter (GM-WM) differentiation, sharpness, artifact, acceptability, and unfamiliar texture change were evaluated and compared. Results The SNR and CNR of each level in each age group increased among strength levels of DLIR. High-level DLIR showed a significantly improved SNR and CNR (p < 0.05). Sequential reduction of noise, improvement of GM-WM differentiation, and improvement of sharpness was noted among strength levels of DLIR. Those of high-level DLIR showed a similar value as that with ASiR-V. Artifact and acceptability did not show a significant difference among the adapted levels of DLIR. Conclusion Adaptation of high-level DLIR for the pediatric head CT can significantly reduce image noise. Modification is needed while processing artifacts.

• Archives of Craniofacial Surgery
• /
• v.16 no.2
• /
• pp.53-57
• /
• 2015

Background: Surgical outcomes after orbital wall decompression have focused on the degree of exophthalmos and intraocular pressure. The aim of this research was to evaluate intraorbital volume using computed tomography (CT) images following two-wall decompression using a combined subcilliary and endoscopic approaches. Methods: A retrospective review was performed for all patients who had undergone the two-wall decompression method. The pre/postoperative CT images were used to evaluate changes in intraocular volume. Intraocular pressure was evaluated using applanation tonometry. Surgical details are discussed within the body of text. Results: Two-wall decompression thru the medial wall and floor was associated with an average intraorbital volume change of $7.3cm^3$, with maximal accommodation up to $13cm^3$. Changes in intraocular pressures were not statistically significant. Conclusion: Two-wall decompression was effective in accommodation of up to $13cm^3$ of soft tissue herniation. There was no statistically significant association between changes in volume to pressure.

• Journal of Korean Neurosurgical Society
• /
• v.54 no.4
• /
• pp.280-288
• /
• 2013

Objective : Perfusion computed tomography (PCT) has the ability to measure quantitative value and produce maps of mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV). We assessed cerebral hemodynamics by using these parameters and acetazolamide (ACZ) challenge for pre- and post-procedural evaluation in patients with unilateral cerebrovascular stenotic disease. Methods : Thirty patients underwent pre-procedural PCT with ACZ challenge, and 24 patients (80%) was conducted follow up PCT after angioplasty with same protocol. The mean MTT, CBF, and CBV were measured and compared in both middle cerebral arterial (MCA) territories before and after ACZ challenge. Hemispheric ratio and percent change after ACZ challenge were calculated before and after angioplasty. Results : The mean stenosis rate was 76.6%. Significant increases in MTT (32.6%, p=0.000) and significant decreases in CBF (-14.2%, p=0.000) were found in stenotic side MCA territories. After ACZ challenge, there were significant changes in MTT (37.4%, p=0.000), CBF (-13.1%, p=0.000), and CBV (-10.5%, p=0.001) in pre-procedural perfusion study. However, no significant increases were found in MTT, or decreases in CBF and CBV in post-procedural study. There were no significant changes after ACZ challenge also. In addition, the degrees of these changes (before and after ACZ challenge) were highly correlated with the stenotic degrees in pre-procedural perfusion study. Conclusion : PCT with ACZ challenge appears to be a useful tool to assess the cerebral perfusion status especially in patients with unilateral symptomatic stenotic disease.

• Journal of Veterinary Clinics
• /
• v.37 no.1
• /
• pp.28-33
• /
• 2020

The aims of this study were to obtain the normal ranges of enhancement parameters for salivary gland in dynamic CT and to investigate the effects of fasting time on contrast enhancement in clinically normal beagle dogs. With five healthy beagle dogs, dynamic CT examination was performed according to fasting times (as fasting times, 12hours, 0 min, 20 min, 40 min, 1 hours, 6 hours, 24 hours). In normal beagles with 12hours fasting, enhancement parameters through the preliminary study were as follows: ImaxA - 472 .49 ± 19.01 HU; ImaxS - 138.95 ± 6.2 5 HU; TmaxA - 25.8 ± 1.79 sec; TmaxS - 69.0 ± 23.11 sec; Teq - 80.5 ± 6.61 sec; T-Aeq - 54.5 ± 5.51 sec (Imax - peak enhancement; Tmax - time to peak enhancement; Teq - time to equilibrium phase; T-Aeq - time between peak enhancement in the common carotid artery and onset of the equilibrium phase; A - common carotid; S - submandibular gland; HU - Hounsfield unit). Additionally, ImaxA and ImaxS were significantly increased in 40 min after eating. Because these results associated with postprandial hemodynamic changes can make the diagnosis of salivary gland diseases more difficult, sufficient fasting time is important for accurate diagnosis.

• Journal of the Korean Society of Radiology
• /
• v.84 no.4
• /
• pp.900-910
• /
• 2023

Purpose To assess normal CT scans with quantitative CT (QCT) analysis based on smoking habits and chronic obstructive pulmonary disease (COPD). Materials and Methods From January 2013 to December 2014, 90 male patients with normal chest CT and quantification analysis results were enrolled in our study [non-COPD never-smokers (n = 38) and smokers (n = 45), COPD smokers (n = 7)]. In addition, an age-matched cohort study was performed for seven smokers with COPD. The square root of the wall area of a hypothetical bronchus of internal perimeter 10 mm (Pi10), skewness, kurtosis, mean lung attenuation (MLA), and percentage of low attenuation area (%LAA) were evaluated. Results Among patients without COPD, the Pi10 of smokers (4.176 ± 0.282) was about 0.1 mm thicker than that of never-smokers (4.070 ± 0.191, p = 0.047), and skewness and kurtosis of smokers (2.628 ± 0.484 and 6.448 ± 3.427) were lower than never-smokers (2.884 ± 0.624, p = 0.038 and 8.594 ± 4.944, p = 0.02). The Pi10 of COPD smokers (4.429 ± 0.435, n = 7) was about 0.4 mm thicker than never-smokers without COPD (3.996 ± 0.115, n = 14, p = 0.005). There were no significant differences in MLA and %LAA between groups (p > 0.05). Conclusion Even on normal CT scans, QCT showed that the airway walls of smokers are thicker than never-smokers regardless of COPD and it preceded lung parenchymal changes.

• Korean Journal of Radiology
• /
• v.22 no.4
• /
• pp.502-512
• /
• 2021

Objective: To objectively and subjectively assess and compare the characteristics of monoenergetic images [MEI (+)] and polyenergetic images (PEI) acquired by dual-energy CT (DECT) of patients with breast cancer. Materials and Methods: This retrospective study evaluated the images and data of 42 patients with breast cancer who had undergone dual-phase contrast-enhanced DECT from June to September 2019. One standard PEI, five MEI (+) in 10-kiloelectron volt (keV) intervals (range, 40-80 keV), iodine density (ID) maps, iodine overlay images, and Z effective (Z_eff) maps were reconstructed. The contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) were calculated. Multiple quantitative parameters of the malignant breast lesions were compared between the arterial and the venous phase images. Two readers independently assessed lesion conspicuity and performed a morphology analysis. Results: Low keV MEI (+) at 40-50 keV showed increased CNR and SNR_{breast lesion} compared with PEI, especially in the venous phase ([CNR: 40 keV, 20.10; 50 keV, 14.45; vs. PEI, 7.27; p < 0.001], [SNR_{breast lesion}: 40 keV, 21.01; 50 keV, 16.28; vs. PEI, 10.77; p < 0.001]). Multiple quantitative DECT parameters of malignant breast lesions were higher in the venous phase images than in the arterial phase images (p < 0.001). MEI (+) at 40 keV, ID, and Z_eff reconstructions yielded the highest Likert scores for lesion conspicuity. The conspicuity of the mass margin and the visual enhancement were significantly better in 40-keV MEI (+) than in the PEI (p = 0.022, p = 0.033, respectively). Conclusion: Compared with PEI, MEI (+) reconstructions at low keV in the venous phase acquired by DECT improved the objective and subjective assessment of lesion conspicuity in patients with malignant breast lesions. MEI (+) reconstruction acquired by DECT may be helpful for the preoperative evaluation of breast cancer.

• Journal of the Korean Society of Radiology
• /
• v.16 no.3
• /
• pp.281-288
• /
• 2022

In this study, four algorithms (Soft, Standard, Detail, Bone) were used for general CT scan (Before MAR) images and MAR (After MAR) images for patients with metal implants inserted into the hip joint. was applied to compare and analyze Noise, SNR, and CNR to find out the optimal algorithm for quantitative evaluation. As the analysis method, Image J program, which can calculate image analysis and area and pixel values on the image reconstructed with four algorithms, was used. In order to obtain Noise, SNR, and CNR, the HU mean value and HU SD value were obtained by designating the bone (ischium) closest to the metal implant in the image for the measurement site, and the background noise was the surrounding muscle. The region of interest (ROI) was equally designated as 15 × 15 mm in consideration of the size of the bone, and the values of SNR and CNR were calculated according to the given equation. As a result, for noise, After MAR and Soft algorithms showed the lowest noise, and SNR and CNR showed the highest for Before MAR and Soft algorithms. Therefore, the soft algorithm is judged to be the most appropriate algorithm for metal implant hip joint CT.

• Journal of the Korean Society of Radiology
• /
• v.8 no.6
• /
• pp.279-285
• /
• 2014

This study is to have dose reduction and minimization of excessive use of contrast medium in the pediatric cardiac computed tomography and to suggest the optimization plan to acquire the enhancement image of the 4 chambers at the same time by formulating scan delay time in empirical method with considering variables such as contrast medium injection velocity and cardiac approaching time. Quantitative, qualitative and dose assessment were carried out for 30 pediatric patients who had taken the cardiac examination. In conclusion, image enhancement in 4 chambers of the cardiac shows over 300 HU which is proper to pediatric cardiac reading by applying the empirical method with calculating scan delay time according to weight and contrast medium volume and injection velocity. Qualitative image assessments in confidence sharpness and noise have excellence qualitatively. Exposure dose to pediatrics also decreases precisely. Therefore this study is judged to take a important role of making optimization images with advantages of dose reduction and less side effects caused by it's excessive use in clinic.

• Journal of the Korean Society of Radiology
• /
• v.5 no.6
• /
• pp.369-375
• /
• 2011

In dental radiography, panoramic views cause distortion and thus may bring about inaccurate results in the process of quantitative analysis. In this connection, there has recently been an increasing use of cone beam computed tomography (CBCT) that is known to provide high-resolution images and positional information. In this study, a dental computed tomography unit, 'DCT-90-P IMPLAGRAPHY (Vatech, Korea)', was applied to 20 patients for 24 seconds respectively, with a tube voltage of 85kVp and a tube current of 7mA. The data of CBCT were three-dimensionally reconstructed by use of a computer program, and were histomorphometrically analyzed. The results showed that the diameter of mandibular canal is less distorted at a certain inclination of the mandibular body. The image tends to seem more distended in proportion to the distance between the subject and film. Also, the image tends to be affected according as it is out of focus. In conclusion, it requires that the image should be reconstructed in light of anatomic position and structure.