• Korean Journal of Radiology
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• v.25 no.5
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• pp.473-480
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• 2024

We systematically reviewed radiological abnormalities in patients with prolonged SARS-CoV-2 infection, defined as persistently positive polymerase chain reaction (PCR) results for SARS-CoV-2 for > 21 days, with either persistent or relapsed symptoms. We extracted data from 24 patients (median age, 54.5 [interquartile range, 44-64 years]) reported in the literature and analyzed their representative CT images based on the timing of the CT scan relative to the initial PCR positivity. Our analysis focused on the patterns and distribution of CT findings, severity scores of lung involvement on a scale of 0-4, and the presence of migration. All patients were immunocompromised, including 62.5% (15/24) with underlying lymphoma and 83.3% (20/24) who had received anti-CD20 therapy within one year. Median duration of infection was 90 days. Most patients exhibited typical CT appearance of coronavirus disease 19 (COVID-19), including ground-glass opacities with or without consolidation, throughout the follow-up period. Notably, CT severity scores were significantly lower during ≤ 21 days than during > 21 days (P < 0.001). Migration was observed on CT in 22.7% (5/22) of patients at ≤ 21 days and in 68.2% (15/22) to 87.5% (14/16) of patients at > 21 days, with rare instances of parenchymal bands in previously affected areas. Prolonged SARS-CoV-2 infection usually presents as migrating typical COVID-19 pneumonia in immunocompromised patients, especially those with impaired B-cell immunity.

• Korean Journal of Head & Neck Oncology
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• v.35 no.2
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• pp.11-17
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• 2019

Background/Objectives: Papillary thyroid carcinoma (PTC) has generally an indolent character with a good prognosis. However, recurrence remains a major concern for the patients during their lifetime. Despite the slowly progressing character of PTC, recurrence can occur within a short period after initial surgery. This study aimed to determine the clinical findings and cause of recurrence in patients who underwent re-operative surgery due to neck node recurrence by reviewing the CT (computed tomographic) scan imaging of the recurrence of PTC retrospectively. Materials & Methods: We reviewed the medical records of patients referred to Ajou University Hospital from January 2002 to January 2018. All patients had re-operative surgery due to neck node recurrence and CT scan results of preoperative evaluation and postoperative follow up. Over this period, 110 patients who underwent re-operation due to neck node recurrence with a CT scan were included in our cohort, resulting in a total of 220 re-operations. Results: The time from initial operation to first re-operation was examined in 110 patients. The median time to re-operation was 28 months, with a range of 4 months to 186 months. Most re-operations (82.7%) occurred within the first five years, 43.6% were in the first two years from the initial surgery. The result of the retrospective CT review showed newly developed cases (21,19.1%), missed diagnosis cases (42,38.2%), real recur cases after surgery (33,30.0%), and remnant lymph nodes (LNs) cases (14,12.7%). We further sub-analyzed 14 cases with remnant LNs. Reasons for remnant LNs included insufficient operation (N=5) and beyond general surgical extent. (N=9). Conclusion: Re-operation due to cervical lymph node recurrence is mostly a persistent disease. They included a missed diagnosis and incomplete operation. These finding may reduce the reoperation of cervical lymph node recurrence by accurate preoperative evaluation and complete surgical resection at the initial surgery.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.3-7
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• 2010

Purpose: The usefulness of Positron Emission Tomography (PET) images in diagnosis, staging, recurrent and treatment response evaluation has already been known. However, tumors which are small size, located in lower lobe of lung or upper lobe of liver are shown misalignment, distortion and different Standard Uptake Value (SUV) by respiration in PET images. Therefore, if radiotherapy based on normal respiration, it may cause low treatment response or more side effects because targets which had to treat, out of treat range or over dose to normal tissue. The purpose of this study is to evaluate attenuation-correction with Average CT (ACT) for more accuracy SUV measurement and minimize artifact by respiration. Materials and Methods: 13 patients, who had tumors which are around the diaphragm, underwent ACT scan after Helical CT (HCT) scan with PET/CT (Discovery DSTE 8; GE Healthcare). We quantified the differences between attenuation corrected image with HCT and attenuation corrected image with ACT in artifact size and maximum SUV ($SUV_{max}$). Artifacts were evaluated by measurement of the curved photogenic area in the lower thorax of the PET images for all patients. $SUV_{max}$ was measured separately at the primary tumors. Analysis program was Advantage Workstation v4.3 (GE Healthcare). Patients were injected with 7.4 MBq (0.2 $mC_i$) per kg of $^{18}F$-FDG and scanned 1 hour after injection. The PET acquisition was 3 minute per bed. Results: Significantly lower artifact were observed in PET/ACT images than in PET/HCT images (below-thoracic artifacts caused by under corrected $1.5{\pm}3.5$ cm vs. $13.4{\pm}4.2$ cm). Significantly higher $SUV_{max}$ were noted in PET/ACT images than in PET/HCT images in the primary tumor. Compared with PET/HCT images, $SUV_{max}$ in PET/ACT images were higher by $5.3{\pm}3.9%$ (mean value) tumor. The highest difference was observed in Lower lobe of lung (7.7 to 8.7; 13%). Conclusion: Due to its significantly reduced artifacts in lower thoracic, attenuation corrected image with ACT images provided more reliable $SUV_{max}$ and may be helpful in monitoring treatment response. Moreover, ACT can separate upper lobe of liver and lower lobe of lung, it may be helpful in interpretation. ACT will be clinically useful, considering increased dose caused by ACT scan and adapt.

• Clinics in Shoulder and Elbow
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• v.26 no.4
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• pp.343-350
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• 2023

Background: Our purpose was to evaluate a custom reverse total shoulder arthroplasty glenoid baseplate for severe glenoid deficiency, emphasizing the challenges with this approach, including short-term clinical and radiographic outcomes and complications. Methods: This was a single-institution, retrospective series of 29 patients between January 2017 and December 2022 for whom a custom glenoid component was created for extensive glenoid bone loss. Patients were evaluated preoperatively and at intervals for up to 5 years. All received preoperative physical examinations, plain radiographs, and computed tomography (CT). Intra- and postoperative complications are reported. Results: Of 29 patients, delays resulted in only undergoing surgery, and in three of those, the implant did not match the glenoid. For those three, the time from CT scan to implantation averaged 7.6 months (range, 6.1-10.7 months), compared with 5.5 months (range, 2-8.6 months) for those whose implants fit. In patients with at least 2-year follow-up (n=9), no failures occurred. Significant improvements were observed in all patient-reported outcome measures in those nine patients (American Shoulder and Elbow Score, P<0.01; Simple Shoulder Test, P=0.02; Single Assessment Numeric Evaluation, P<0.01; Western Ontario Osteoarthritis of the Shoulder Index, P<0.01). Range of motion improved for forward flexion and abduction (P=0.03 for both) and internal rotation up the back (P=0.02). Pain and satisfaction also improved (P<0.01 for both). Conclusions: Prolonged time (>6 months) from CT scan to device implantation resulted in bone loss that rendered the implants unusable. Satisfactory short-term radiographic and clinical follow-up can be achieved with a well-fitting device. Level of evidence: III.

• Journal of Gastric Cancer
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• v.3 no.4
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• pp.195-200
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• 2003

Purpose: Advancement of computed tomography (CT) hardware and software has allowed thin section scanning and reconstruction of fascinating 2-dimentional (2D) and 3- dimentional (3D) images. Especially, the reconstruction of 3D images of gastrointestinal tract has been used in the detection and diagnosis of pre-malignant and malignant diseases. To compare the efficacy of CT gastrography with conventional upper gastrointenstinal series (UGIs) in gastric cancer patients. Materials and Methods: During Nov. 2002 and Mar. 2003, twenty-seven patients who had gastric cancer received both double contrast upper GI series and CT gastrography prior to radical surgery. Among these patients, nineteen had early gastric cancer (EGC) and 8 had advanced gastric cancer (AGC). Fifteen patients were male and 12 were female. The mean age was 54 yrs (range, $27\∼75$ yrs). The patients were placed on NPO and Stomach was distended with gas in fasting state prior to CT scanning. Double contrast upper GI series were performed as routine manual. CT scan was conducted in all patients using 8 or 16-channel multidetector CT in this study. The collimation and reconstruction for CT scanning were set at 2.5 mm and 1.25 mm, respectively. CT scanning was performed in the supine position. For image processing, CT gastrography, in which raysum and surface rendering images were constructed, virtual and 2D image in coronal and sagittal images were performed. The detectability of gastric cancer was assessed between UGIs and CT gastrography. Results: In AGCs, the detection rate of cancer using CT gastrography and virtual gastroscopy was higher than EGC cases. However, CT gastrography and virtual gastroscopy showed less favorable results than UGIs. Even though only a small number of cases had been studied, we might conclude that CT gastrography and virtual gastroscopy could replace UGIs in the detection of AGC cases. Conclusion: The detection rate used with CT gastrography and Virtual gastroscopy is not better than that of UGIs in early gastric cancer, however, in advanced gastric cancer cases, it is nearly equal to that of UGIs.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.84-89
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• 2013

Purpose: Patients' movement during long image acquisition time for the fusion image of PET-CT (Positron Emission Tomography-Computed Tomography) results in unconformity, and greatly affects the quality of the image and diagnosis. The arm support fixtures provided by medical device companies are not manufactured considering the convenience and safety of the patients; the arm and head movements (horizontal and vertical) during PET/CT scan cause defects in the brain fundus images and often require retaking. Therefore, this study aims to develop patient-compensation device that would minimize the head and arm movements during PET/CT scan, providing comfort and safety, and to reduce retaking. Materials and Methods: From June to July 2012, 20 patients who had no movement-related problems and another 20 patients who had difficulties in raising arms due to shoulder pain were recruited among the ones who visited nuclear medicine department for PET Torso scan. By using Patient Holding System (PHS), different range of motion (ROM) in the arm ($25^{\circ}$, $27^{\circ}$, $29^{\circ}$, $31^{\circ}$, $33^{\circ}$, $35^{\circ}$) was applied to find the most comfortable angle and posture. The manufacturing company was investigated for the permeability of the support material, and the comfort level of applying bands (velcro type) to fix the patient's head and arms was evaluated. To find out the retake frequency due to movements, the amount of retake cases pre/post patient-compensation were analyzed using the PET Torso scan data collected between January to December 2012. Results: Among the patients without movement disorder, 18 answered that PHS and $29^{\circ}$ arm ROM were the most comfortable, and 2 answered $27^{\circ}$ and $31^{\circ}$, respectively. Among the patients with shoulder pain, 15 picked $31^{\circ}$ as the most comfortable angle, 2 picked $33^{\circ}$, and 3 picked $35^{\circ}$. For this study, the handle was manufactured to be adjustable for vertical movements. The material permeability of the patient-compensation device has been verified, and PHS and the compensation device were band-fixed (velcro type) to prevent device movements. A furrow was cut for head fixation to minimize the head and neck movements, fixing bands were attached for the head, wrist, forearm, and upper arm to limit movements. The retake frequency of PET Torso scan due to patient movements was 11.06% (191 cases/1,808 patients) before using the movement control device, and 2.65% (48 cases/1,732 patients) after using the device; 8.41% of the frequency was reduced. Conclusion: Recent change and innovation in the medical environment are making expensive medical image scans, and providing differentiated services for the customers is essential. To secure patient comfort and safety during PET/CT scans, ergonomic patient-compensation devices need to be provided. Therefore, this study manufactured a patientcompensation device with vertically adjustable ergonomic ROM according to the patient's body shape and condition during PET Torso scan. The defects in the basal ganglia images due to arm movements were reduced, and retaking was decreased.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.127-134
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• 2022

In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.

• Hip & pelvis
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• v.36 no.1
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• pp.26-36
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• 2024

Total hip arthroplasty (THA) is a frequently performed procedure; the objective is restoration of native hip biomechanics and achieving functional range of motion (ROM) through precise positioning of the prosthetic components. Advanced three-dimensional (3D) imaging and computed tomography (CT)-based navigation are valuable tools in both the preoperative planning and intraoperative execution. The aim of this study is to provide a thorough overview on the applications of CT scans in both the preoperative and intraoperative settings of primary THA. Preoperative planning using CT-based 3D imaging enables greater accuracy in prediction of implant sizes, leading to enhancement of surgical workflow with optimization of implant inventory. Surgeons can perform a more thorough assessment of posterior and anterior acetabular wall coverage, acetabular osteophytes, anatomical landmarks, and thus achieve more functional implant positioning. Intraoperative CT-based navigation can facilitate precise execution of the preoperative plan, to attain optimal positioning of the prosthetic components to avoid impingement. Medial reaming can be minimized preserving native bone stock, which can enable restoration of femoral, acetabular, and combined offsets. In addition, it is associated with greater accuracy in leg length adjustment, a critical factor in patients' postoperative satisfaction. Despite the higher costs and radiation exposure, which currently limits its widespread adoption, it offers many benefits, and the increasing interest in robotic surgery has facilitated its integration into routine practice. Conducting additional research on ultra-low-dose CT scans and examining the potential for translation of 3D imaging into improved clinical outcomes will be necessary to warrant its expanded application.

• Journal of Trauma and Injury
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• v.27 no.4
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• pp.145-150
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• 2014

Purpose: To assess the accuracy and role of single-contrast computed tomography (CT) in the management of anterior abdominal stab wound (AASW). Methods: During 8-years period, single-contrast CT was performed in 21 hemodynamically stable AASW patients (age range, 22-64 years; median age, 45 years), including 19 men and 2 women. CT scans were evaluated by one trauma surgeon and one senior resident to determine the depth of injury(peritoneal violation or not), and abnormal findings of intraperitoneal cavity associated with stab injury. We retrospectively reviewed medical records regarding operative findings. Results: Nine patients underwent abdominal surgery and 12 patients nonoperative management. In the abdominal surgery group, abnormal CT findings included peritoneal violation in 14 patients and abnormal intraperitoneal cavity findings in 5 patients. There was no statistical significant difference regarding abnormal CT findings between abdominal surgery group and nonoperative management group. Among the nine abdominal surgery patients, therapeutic laparotomy was performed on 4 patients. The positive predictive value (PPV) and negative predictive value (NPV) of peritoneal violation to predictive therapeutic laparotomy were 28.6% and 100%, respectively. In addition, the PPV and NPV of abnormal intraperitoneal cavity CT findings to predict therapeutic laparotomy were 40.0% and 87.5%, respectively. There was no statistical significant difference regarding the abnormal CT findings between therapeutic laparotomy group and non therapeutic laparotomy group. Conclusion: CT is a good adjunctive method to evaluate hemodynamicaly stable AASW patients. If peritoneal violation is not seen on CT scan, conservative treatment on local wound may be safely performed without additional abdominal surgery. However, further study is warranted to evaluate the exact role of CT in the diagnostic workup of AASW patients.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.36-40
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• 2011

Purpose: $^{18}F$-FDG injected dose to the patient is quite different between the recommended dose from manufacturer and the actual dose applied to each of hospitals. injection of inappropriate $^{18}F$-FDG dose may not only increase the exposed dose to patients but also reduce the image quality. we thus evaluated the proper $^{18}F$-FDG injected dose to decrease the exposed dose to patients considering the image quality. Materials And Methods: NEMA Nu2-1994 phantom was filled with $^{18}F$-FDG increasing hot cylinder radioactivity concentration to 1, 3, 5, 7, 9 MBq/kg based on the ratio of 4:1 between the hot cylinder and background activity. after completing the transmission scan using ct, emission scan was acquired in 3D mode for 2 minutes 30 seconds/bed. ROI was set up on hot cylinder and background radioactivity region. after measuring $SUV_{max}$ those regions, then analyzed SNR at the points. clinical experiment has been conducted the object of patients who have came to smc from november 2009 to august 2010, 97 patients without having a hepatic lesions were selected. ROI was set up in the liver and thigh area. after measuring $SUV_{max}$, the image quality was compared following the injected dose. Results: in phantom study, as the injected radioactivity concentration per unit mass was 1, 3, 5, 7, 9 MBq/kg, $SUV_{max}$ was 23.1, 24.1, 24.3, 22.8, 23.6 and SNR was shown 0.48, 0.54, 0.56, 0.55, 0.55. according to increment of the injected dose, $SUV_{max}$ and SNR was increased under 5 MBq/kg but they were decreased over 7 MBq/kg. in case of clinical experiment, as increased the injected radioactivity concentration per unit mass was 4.72, 5.34, 6.16, 7.41, 8.68 MBq/kg, $SUV_{max}$ was 2.68, 2.67, 2.26, 1.88, 1.95 and SNR was shown 0.52, 0.53, 0.46, 0.46, 0.44. if the injected dose exceeds 5 MBq/kg, showed a decrease pattern as phantom study. Conclusion: increasing $^{18}F$-FDG injected dose considered patient's body weight improve image quality within a certain range. if it exceeds the range, it can be reduced image quality due to random and scatter coincidences. this study indicates that the optimal injected dose was 5 MBq/kg per unit mass the injected radioactivity concentration in 3d wb pet/ct.