Patient Radiation Exposure Research Articles

Abstract 4138237: Clinical Utility of T2 Mapping for the Assessment of Myocardial Inflammation in Patients With Cardiac Sarcoidosis

Introduction: 18 F-FDG PET has been used for the evaluation of active inflammatory lesions in cardiac sarcoidosis (CS), but it is burdensome for patients to perform as a routine follow-up. Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) that can detect myocardial fibrosis is limited in its ability to assess active inflammation. T2 mapping has been shown to detect myocardial inflammation in myocardial diseases without radiation exposure and contrast agents (Figure). However, the ability of T2 mapping for discriminating inflammatory myocardium has not been fully clarified in patients with CS. Hypothesis: We assessed the hypothesis that T2 mapping has potential for the discrimination of inflammatory myocardium in patients with CS. Methods: Twenty-seven subjects who underwent CMR at 3T and 18 F-FDG PET to diagnose CS were enrolled. Fourteen subjects were diagnosed as CS due to LGE and myocardial FDG uptake on 18 F-FDG PET (PET-positive group). Thirteen subjects showed no myocardial FDG uptake (PET-negative group). NativeT1, T2, and extracellular volume fraction (ECV) were measured using a 16-segment model. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate T1 and T2 mapping in discriminating between active and inactive inflammatory segments in the PET-positive group. Results: Mean native T1, native T2 and ECV showed no significant differences between the PET-positive and the PET-negative groups. However, maximum T2 values, which were highest ones in the 16 segments, were significantly higher in the PET-positive group than the PET-negative group (51.3 ± 7.7 ms vs 45.7 ± 3.6 ms, p = 0.014). In the PET-positive group, ROC analysis showed AUC of 0.72 in native T2, 0.61 in native T1, and 0.68 in ECV for discriminating inflammatory myocardium. The optimal cutoff value of native T2 was 45.7 ms, and the diagnostic performance had a sensitivity of 44.4 %, specificity of 93.3 % , positive predictive value of 88.1 %, and negative predictive value of 60.1 %. Conclusion: T2 mapping is a promising approach for the discrimination of inflammatory myocardium without radiation exposure and contrast agents in patients with cardiac sarcoidosis.

Radiofrequency ablation guided by real-time cardiovascular magnetic resonance.

Cardiovascular magnetic resonance (CMR) is gaining ground in guiding electrophysiology (EP)-based ablation procedures of typical atrial flutter and atrial fibrillation, allowing for the avoidance of radiation exposure for patients and operators and reducing the risk of occupational illnesses. CMR allows comprehensive assessment of cardiac anatomy and provides tissue characterization by identifying pathological substrates, such as myocardial scars and edema, identified with the implementation of late gadolinium enhancement and T2-weighted short-tau inversion recovery sequences. Intraprocedural imaging is useful for real-time catheter tracking during the ablation procedure while simultaneously providing visualization of cardiac anatomy. Additionally, CMR facilitates the evaluation of the ablation procedure accuracy by acquiring edema-sensitive sequences, thereby aiding in preventing early complications. This report serves as a primer for radiologists and illustrates the value of CMR in planning and performing the ablation procedure, as well as its role in post-procedural imaging.

Comparative Analysis of CT Fluoroscopy Modes and Gastropexy Techniques in CT-Guided Percutaneous Radiologic Gastrostomy

Background/Objectives: This study was conducted to compare two modes of computed tomography fluoroscopy (CTF) and two gastropexy techniques used in CT-guided percutaneous radiologic gastrostomy (CT-PRG) aiming to identify the optimal techniques for image guidance and gastropexy and, thus, to overcome the current lack of consensus on the preferred modalities. Methods: We retrospectively identified 186 successful CT-PRG procedures conducted evenly across two university hospitals from January 2019 to December 2023. Patients were divided into two groups (intermittent multislice CT biopsy mode-guided technique (MS-CT BM) and retention anchor suture (T-fastener) versus real-time (RT-)CTF and gastropexy device) for descriptive analysis of demographics, indication for PRG, radiation exposure (DLP), procedural time, number of CT scans, gastropexy time, and complications. Differences were assessed for statistical significance using Fisher’s exact test and the Mann–Whitney U-test. Results: Our final study population comprised 100 patients (50 from each center; 62.52 ± 12.36 years, 73 men). There was a significant difference in radiation exposure between MS-CT BM (group 1) and RT-CTF (group 2), with an average dose-length product (DLP) of 56.28 mGycm×m ± 67.89 and 30.91 ± 27.53 mGycm×cm, respectively (p < 0.001). PRG with RT-CTF guidance was significantly faster than PRG with MS-CT BM, with an average difference of 10.28 min (p < 0.001). No significant difference in duration was found between the two gastropexy methods compared (retention anchor suture, 11.50 ± 5.239 s vs. gastropexy device, 11.17 ± 6.015 s; p = 0.463). Complication rates did not differ significantly either (p = 0.458). Conclusions: Our findings indicate comparable efficacy and safety of the two gastropexy methods and underscore that the choice of CTF mode for image guidance has only a small role in reducing radiation exposure in patients undergoing CT-PRG. Instead, it is essential to avoid control scans.

Assessing radiation doses and proposing DRLs for nuclear medicine procedures for pediatric and adult patients in Madinah, Saudi Arabia

BackgroundNuclear medicine diagnostic and treatment procedures represent significant sources of ionizing radiation exposure for both staff and patients. Consequently, assessing and optimizing radiation doses are crucial to minimize potential side effects. AimThis study seeks to evaluate the effective radiation doses associated with common diagnostic and treatment procedures, as well as propose diagnostic reference levels (DRLs), within two nuclear medicine centers in Madinah, Saudi Arabia. MethodologyData from 445 patients were gathered from two nuclear medicine centers in the Madinah region of Saudi Arabia. The data were categorized based on the type of nuclear medicine (NM) procedure, the chemical composition of the administered radiopharmaceutical, as well as patient age and weight. Effective radiation doses for prevalent NM procedures were computed, and suggested DRLs were formulated. ResultsEffective radiation doses were analyzed for 16 adult and 2 pediatric NM procedures (divided into 8 groups). The effective radiation doses for adult diagnostic nuclear medicine procedures range from 0.05 mSv (Nanocoloid) to 29 mSv (67Ga-citrate). For pediatric procedures, the doses range from 0.80 mSv (5-year-old undergoing renal DTPA) to 1.6 mSv (1-year-old undergoing renal DMSA). Furthermore, DRL values were determined for both adult and pediatric NM procedures. The study's findings demonstrated a high degree of concordance between effective radiation doses and DRL values, aligning well with previously published research. ConclusionWhile the effective radiation doses outlined in this study were generally within acceptable limits and consistent with prior research findings, optimizing radiation doses remains imperative, particularly for pediatric NM procedures.

Biological effects of radiation exposure in patients treated with X-ray guided endovascular aortic repair

Abstract Background X-ray guided cardiovascular interventions such as endovascular aortic repair (EVAR) expose patients and operators to significant amounts of repeated ionising radiation over a long period of time. The biological effect of such protracted radiation exposure is poorly understood. We have previously demonstrated a higher incidence of dicentric chromosome (DC) aberrations in high-volume endovascular interventionalists and differences in acute DNA damage in lymphocytes between individuals following in vitro irradiation. Studies suggested a higher incidence of cancer in patients who underwent EVAR compared with those who have had open aneurysm repair, but the evidence is inconclusive. Further work is required to evaluate the biological radiation risk of X-ray guided cardiovascular interventions. Purposes We aimed to examine radiation-induced genome instability from patients after complex EVAR. We also aimed to investigate the intrinsic response of each patient to radiation using biomarkers of acute DNA damage following in vitro irradiation of their blood and to correlate this response to the expression of radiation-responsive genes. Methods Lymphocytes were isolated from patients after complex (branched/fenestrated) EVAR and non-irradiated controls. DC, a type of chromosomal aberration caused by radiation exposure were enumerated. γ-H2AX, a marker of acute DNA damage/repair, was measured by immunofluorescence after in vitro irradiation at 0.2 Gy and 1 Gy, along with the expression of the radiation-responsive genes FDXR, CCNG1, P21 and PHPT1 using qPCR. Results 17 patients (82% male, median age 73[59 – 85years]) and 16 controls (56% male, median age 68[53 – 83years]) were recruited. The mean incidence of DC was 3.782 (95% CI 3.13 - 4.43) and 0.898 (95% CI 0.48 -1.32) per 1000 cells for patients and controls, respectively (P<0.0001). Patients had higher background of γ-H2AX foci than unexposed controls, (0.7056, 95% CI 0.316 - 1.10) vs (0.241 95% CI 0.077 - 0.405) per cell, P<0.05. FDXR expression was most increased following irradiation (P<0.0001), reaching a mean 13.1-fold and 11.4-fold increase at 4-hour and 24-hour time-point, respectively, but this upregulation was not significantly different between the two groups. Conclusion We have shown an increased frequency of chromosomal aberrations in patients after complex EVAR, a biological finding that may support a propensity to developing malignancies. Patients also have higher basal DNA damage/repair (γ-H2AX) activity. Expression of ferredoxin reductase, FDXR gene could be a potential radio-responsive biomarker to provide personalised biological dosimetry information for clinical monitoring. Our study further underlines the long-term radiation risk of X-ray guided cardiovascular interventions and the potential of biological assays that may guide personalised care.

NICE guidance in the rapid access chest pain clinic: does it work?

Abstract Background Rapid Access Chest Pain Clinics (RACPC) were developed following the publication of the National Service Framework for Coronary Heart Disease in 2000(1). The National Institute for Health and Care Excellence (NICE) produces guidelines for the management of patients with recent onset chest pain of suspected cardiac origin(2). In 2016 the guidance was updated and recommended the use of CT coronary angiography (CTCA) as the initial investigation for patients with chest pain which was typical or atypical of angina. Adherence to the guideline may be dependent upon factors such as local availability of CT scanners and clinician preference. The RACPC in this tertiary centre is nurse-run with no medical involvement. There is good engagement with the CT department and in July 2017 the NICE guidance was adopted in the clinic. Purpose To evaluate the use of CTCA as the first line investigation for patients with typical or atypical chest pain. Methods Data from all patients reviewed in the clinic between 01/07/2017 and 31/12/2023 were prospectively collected, entered into a database, and then retrospectively analysed. The data were organised into 3 groups: patients with typical chest pain; atypical pain and those with non-cardiac sounding chest pain. The number of patients in each group who underwent a CTCA, and the outcome of the scan were evaluated. The CT scans were categorised as showing significant coronary artery disease (CAD), non-obstructive CAD, no CAD, or as inconclusive. The outcome of patients who had a positive CTCA was also recorded. Results 2986 patients were reviewed in the RACPC in the above period. 14.2% of patients presented with typical pain, 47.4% with atypical pain, and 30.6% had non-cardiac pain. The remaining patients presented with other symptoms such as breathlessness. CTCA was used as the first investigation in the majority of patients with typical or atypical pain, unless alternative investigations or management were deemed to be more clinically appropriate. In 59.5% of typical and 78.5% of atypical presentations, the CT scan showed no CAD, or non-significant CAD. There was a low incidence of positive scans in both groups, however patients with typical pain were more likely to have significant CAD (Table). All patients who had a CTCA indicating significant CAD, were referred for invasive angiography. 88.0% of typical presentations, and 64.0% of those with atypical pain, underwent revascularisation. No patient who underwent invasive angiography was found to have normal coronary arteries. Conclusion Atypical pain is the most frequent presentation in the RACPC, however the majority of these patients, and most of those with typical pain, do not have significant CAD. Careful assessment and the use of CTCA as the initial investigation, enable the identification of those patients who need invasive angiography. This is a cost-effective strategy which also reduces risk and radiation exposure for patients.

Pediatric contrast-enhanced chest CT on a photon-counting detector CT: radiation dose and image quality compared to energy-integrated detector CT.

Photon counting detector (PCD) CT benefits from reduced noise compared with conventional energy-integrating detector (EID) CT, which should translate to improved image quality and reduced radiation exposure for pediatric patients undergoing chest CT with IV contrast. To determine the differences in radiation exposure and image quality of PCD CT and EID CT in pediatric chest CT with intravenous (IV) contrast. In this institutional review board-approved retrospective observational study, 20 scan pairs (20 PCD CT; 20 EID CT) for children who underwent chest CT with IV contrast on both a PCD CT (Siemens NAEOTOM Alpha) and an EID CT (Siemens SOMATOM Definition Edge or Force) within 12months were reviewed independently by three pediatric radiologists for three subjective quality features on 5-point Likert scales: overall quality, small structure delineation, and motion artifact. Objective measures of image quality (image noise, signal-to-noise ratio, and contrast-to-noise ratio) were assessed by a single radiologist in several locations in the chest through region of interest measurement of Hounsfield units (HU) and standard deviation. Patient-related and radiation exposure parameters were collected for each scan and summarized with median and interquartile range (IQR). The Wilcoxon rank-sum test was utilized to compare groups. A P < 0.05 indicated statistical significance. Inter-observer agreement of subjective image quality metrics was analyzed using weighted kappa. Age (14.2years vs 13.8years, P= 0.15), height (P= 0.13), weight (P= 0.21), and BMI (P = 0.24) did not significantly differ between groups. There were 10 male and 3 female patients. Compared to EID CT, PCD CT showed lower radiation exposure parameters including volumetric CT dose index, 1.7mGy (IQR 1.1-2.4mGy) vs 3.8mGy (IQR 2.0-4.7mGy) (P< 0.01), and size-specific dose estimate, 2.6mGy (IQR 1.8-3.1mGy) vs 5.0mGy (IQR 3.3-6.2mGy) (P< 0.01). Objective image quality of lung parenchyma was improved on the PCD CT scanner, including image noise 119.5 HU (IQR 95.4-135.7 HU) vs 143.1 HU (IQR 125.4-169.8 HU) (P < 0.01), signal-to-noise ratio (SNR) -6.1 (IQR -8.4 to -4.8) vs -4.9 (IQR -5.6 to -3.8) (P= 0.01), and contrast-to-noise ratio -63.9 (-84.1 to -57.5) vs -60.5 (-76.3 to -52.5) (P = 0.01). Motion artifact was improved on the PCD CT scanner (P< 0.01). No significant differences in overall image quality or small structure delineation were identified (P= 0.06 and P= 0.31). PCD CT pediatric chest CT had significantly reduced radiation exposure, improved image quality, and reduced motion artifact compared with EID CT.

Radiation exposure of patients undergoing multiple-slice CT scans in Romania

Abstract Ionizing radiation is largely used in medicine due to its role in the diagnosis and treatment of patients. In the past 50 years computed tomography (CT) has become indispensable for medical practice because it offers sub-millimeter cross-sectional imaging of any region of the body. New CT scanners use thinner slices, providing more accurate results, but also an increased radiation exposure with possible long-term harmful effects for the patients. The parameter used as an indicator of radiation dose in CT is the dose-length product (DLP). The study included 4507 patients who were CT scanned using a 16, 32, 64 or 128-slice CT machine. DLP was measured for head, sinuses, thorax, abdomen, pelvis, abdomen+pelvis, and trunk scans - regions for which the health authorities have established national diagnostic reference levels (DRL - the expected radiation dose received by a patient in CT). One-way ANOVA was used to analyse data considering the use of contrast agents, the gender, age, and weight of patients. Average DLP values were higher (up to 80%) than national DRL for all regions in 64 and 128-slice scans. The highest DLP values were registered in contrast CT for all scanners (p &amp;lt; 0.01); the maximum average (a threefold increase compared to DRL) was measured in the 32-slice sinuses contrast CT. Average DLP correlated with patients’ gender and weight (p &amp;lt; 0.01), but the influence was lower compared to the use of contrast agents. In conclusion, CT scans acquired using thinner slices lead to more accurate results and high-quality images, but the study suggests an increased radiation exposure. CT has an uncontestable contribution to a precise and rapid diagnosis, but more attention must be given to the stochastic effects risks associated with the radiation dose received during a CT scan. Are all scans necessary? Do all patients really need to receive high doses? The role of the practitioner is decisive, and the justifiable process is “a must” in all radiodiagnosis practices. Key messages • CT doses must be kept “as low as reasonably achievable” while maintaining diagnostic image quality. • Justification, dose limitation, and optimisation are fundamental principles of radioprotection.

Tooth segmentation by low-dose CBCT for orthodontic treatment planning : Explorative ex vivo validation.

Three-dimensional imaging has become an increasingly important component of orthodontics. Associated with this, however, is ahigher radiation exposure for patients. New cone-beam computed tomography (CBCT) devices have been developed that can provide low-dose CBCT(LD-CBCT). We hypothesized that LD-CBCT is as precise and reproducible as standard high-dose CBCT (HD-CBCT) in segmenting roots and crowns as well as measuring tooth length. HD-CBCT and LD-CBCT scans were taken of four human cadaveric heads. Thirty single-rooted teeth were segmented twice by one investigator. The length of each tooth was also measured. Lin's concordance correlation coefficient (CCC) was calculated to assess the agreement of HD-CBCT and LD-CBCT measurements and the intraclass correlation coefficient (ICC) was calculated to assess intrarater reliability. Analyses were supported by Bland-Altman plots. Volume measurements obtained using HD-CBCT were significantly higher than those obtained using LD-CBCT (p < 0.001). CCC was 0.975 (95% confidence interval [CI] = 0.956-0.986) indicating excellent agreement between the two modalities. Intrarater reliability between the two sets of LD-CBCT and HD-CBCT volume measurements was excellent (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]). CCC for tooth length measurements was 0.991 (95% CI = 0.983-0.995), indicating excellent agreement between HD-CBCT and LD-CBCT. Intrarater reliabilities between the two sets of tooth length measurements were also excellent for both methods (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]). Within the limitations of this experimental setting, LD-CBCT is as valid as HD-CBCT for measuring tooth length. Regarding the volume differences, in vivo studies are required to determine their clinical relevance.

A dual encoder LDCT image denoising model based on cross-scale skip connections

LDCT image denoising is crucial in medical imaging as it aims to minimize patient radiation exposure while maintaining diagnostic image quality. However, current convolutional neural network-based denoising methods struggle to incorporate global contexts, often focusing solely on local features. This limitation poses a significant challenge. To address this, a dual encoder denoising model is introduced that utilizes the Transformer model’s proficiency in capturing long-range dependencies and global context. This model integrates the Transformer branch and the convolutional branch in the encoder. By concatenating the features of these two different branches, the model can capture both global and local image features, substantially enhancing denoising efficacy. A cross-scale skip connection mechanism is introduced to integrate the encoder’ s low-level features with the decoder’ s high-level features, enriching contextual information and preserving image details. In addition, to meet the requirements of multi-scale feature fusion, the decoder is equipped with different multi-scale convolution modules to optimize feature processing. The number of layers in these modules gradually decreases as the depth of the decoder increases. In order to enhance the discriminative ability of the model, a multi-scale discriminator is also introduced, which effectively improves the recognition ability of the image by extracting features from four different scales. Consequently, our approach demonstrates remarkable performance in reducing noise and improving LDCT image quality, as evidenced by the substantial improvements in PSNR (17.75%) and SSIM (7.31%) values.

Enteroscopy-assisted ERCP in patients with surgically altered anatomy: multicenter prospective registry (SAMISEN-B) using Motorized Spiral Enteroscopy

BACKGROUND &amp; STUDY AIMS: Prospective study of efficacy and safety of Motorized Spiral Enteroscopy (MSE) to perform biliary endoscopic retrograde cholangiopancreatography (ERCP) in patients with surgically altered anatomy at 5 European centers. PATIENTS &amp; METHODS: Consecutive patients with biliary indications for enteroscopy-assisted ERCP. Objectives were technical success, adverse event rate and patient radiation exposure. RESULTS: 89 patients were enrolled, 1 pancreatic indication excluded, all with variations of Billroth II reconstruction (29.5%) or Roux-en-Y reconstruction (70.5%), either with naive papilla (39%) or hepaticojejunostomy (61%). Main indications were anastomotic stricture treatment and/or biliary stone removal. Enteroscopy to reach the bile duct was possible in 65/88 patients (74%), bile duct cannulation in 54/88 (61%) and therapeutic ERCP was technically successful in 48/88 (54%). In Billroth II variations technical success was achieved in 13/26 (50%) compared to 35/62 (57%, p=0.5792 Chi square) in Roux-en-Y reconstructions (including bariatric gastric bypass). ERCP with intact papilla was successful in 17/34 (50%) compared to 31/54 (57%, p=0.4968 Chi square) in hepaticojejunostomy. In July 2023 the study was prematurely terminated since MSE was withdrawn by the manufacturer because of safety issues. Overall, in 12/88 (14%) patients adverse events (AE) were recorded and 6 (7%) were considered serious. Only 1 SAE was attributable to MSE enteroscopy: perforation of the proximal oesophagus during enteroscope insertion. CONCLUSIONS: This prospective multicenter study was prematurely discontinued due to withdrawal of the MSE by the manufacturer because of safety issues. Technical success of MSE-assisted biliary ERCP in different types of surgically altered anatomy was 54%, which was lower than anticipated. There was one oesophageal perforation attributable to the use of MSE. (clinicaltrials.gov: NCT05129449)

Factors affecting radiation exposure in patients undergoing endoscopic treatment for urolithiasis.

Imaging techniques, such as computed tomography (CT) and fluoroscopy, are essential for the diagnosis and treatment of urolithiasis. There is increasing concern regarding the cumulative radiation dose associated with medical imaging and its adverse effects. This study aimed to assess radiation exposure in patients undergoing endoscopic management of urolithiasis and to identify factors associated with increased exposure.A retrospective analysis of all consecutive symptomatic urolithiasis cases who underwent endoscopic surgery over a two-year period at a tertiary referral center was performed. The cumulative radiation dose was recorded per stone episode, and the effective dose (ED) then calculated. Multivariable regression analysis was performed to determine the association between ED and patient, stone, and procedural characteristics.Between January 2020 and December 2021, 250 patients underwent endoscopic intervention for urolithiasis; 71% (n = 178) were male with a median age of 48 years (IQR 35-59). The median stone size was 6mm (IQR, 5-8mm) and the median stone volume was 110 mm3 (IQR, 60-206 mm3). Most stones were located in the distal ureter (46%, n = 114). The median ED received per stone episode was 3.99 mSv (IQR 2.9-7 mSv). On multivariable analysis, BMI, number of CT scans performed, CT protocol used, and repeat procedures strongly predicted increased radiation dose (p < 0.01).It is important for urologists to consider the cumulative radiation dosage in patients with urolithiasis. Strategies to minimize exposure, such as avoiding re-imaging, low-dose CTs, and collimation of the region of interest with judicious magnification, should be considered during treatment.

Introduction and evaluation of size-specific DLP for radiation dose estimation in CT examinations.

The increased utilization of computed tomography (CT) has raised concerns about patient radiation exposure. Effective dose (ED), which requires precise estimation, is crucial for assessing and managing these risks. Traditional ED estimation methods, which are based on the dose-length product (DLP), often lack accuracy due to variations in patient size and anatomy. This study aims to evaluate the efficacy of size-specific DLP (SS-DLP), a novel metric that combines the size-specific dose estimate (SSDE) with scan length, to provide a more accurate estimation of radiation exposure from CT examinations. Focusing on adult chest-abdomen-pelvis (CAP) scans, we calculated SSDE and SS-DLP and utilized two simulation tools, Radimetrics and WAZA-ARI, for a detailed analysis. Our findings indicate that SS-DLP is highly correlated with EDs from Monte Carlo simulations, suggesting its reliability. Additionally, SS-DLP showed a moderate reduction in errors based on patient sex and body mass index compared to traditional DLP-based methods. Thus, SS-DLP offers a more accurate and personalized radiation exposure estimate, potentially enhancing patient safety.

Comparative Analysis of Transradial and Transfemoral Approaches in Transarterial Radioembolization for Liver Tumors: A Systematic Review and Meta-Analysis.

Transarterial radioembolization (TARE) is a minimally invasive therapy combining embolization and radiation for cancer treatment. This meta-analysis compares radiation exposure, quality of life, and safety of the transradial (TRA) versus transfemoral (TFA) approaches in TARE for liver tumors. We searched PubMed, SCOPUS, Cochrane, EMBASE, and Web of Science for studies comparing TRA versus TFA in TARE for liver tumors. Our primary outcomes focused on various measures of patient radiation exposure, including procedure time, fluoroscopy time, air kerma, and dose-area product (DAP). For secondary outcomes, we evaluated safety parameters, such as overall pain experienced during the procedure, pain in the recovery room post-procedure, the incidence of adverse events, and the impact on quality of life. Study quality was assessed using Cochrane's ROB 2 tool for RCTs and the Newcastle-Ottawa scale for observational studies. Data analysis was conducted with REVMAN 5.4.1 software. Six studies, comprising one RCT and five cohort studies with 1,209 patients, underwent comprehensive analysis. The aggregated findings revealed a significant reduction in procedure duration associated with TRA (MD =- 6.30, 95% CI [- 9.88, - 2.73], P = 0.005). However, no statistically significant differences were found between TRA and TFA groups concerning fluoroscopy time, recovery time, air kerma, DAP, pain in the recovery room, overall pain during the procedure, quality of life measuring mental health and physical function or adverse events. TRA and TFA showed comparable results in TARE for liver tumors, but TRA offered a shorter procedure time. Further RCTs with larger samples are needed to confirm these findings. Future studies should assess long-term efficacy for a more complete evaluation.

6771 New onset Graves’ Disease in a Patient with Hashimoto's Thyroiditis and Positive Thyroid Peroxidase Autoantibodies. Case Report

Abstract Disclosure: M.M. Eid: None. J.L. Zapater: None. Introduction: Hashimoto’s Thyroiditis (HT) and Graves’ Disease (GD) are the most common thyroid autoimmune disorders. Transition of GD to HT is common, but transition of HT to GD is rare. Case: A 55 year old, female with depression, HTN and fibromyalgia. She was referred for evaluation of chronic fatigue and reduction in functional capacity. Five years earlier, she had also been evaluated for fatigue. Labs at that time: TSH 3.80 µIU/ml (0.35-3.74 µIU/ml), free T4 0.8 ng/dl (0.76-1.46 ng/dl), thyroid peroxidase antibody (anti-TPO) 605.6 U/ml (0-60 U/ml), and anti-thyroglobulin antibody (anti-TG) 37.2 U/ml (0-60 U/ml). Subclinical hypothyroidism was diagnosed, but no levothyroxine was initiated. Her TSH was found to be normal in 2019 and 2021. At the current clinical encounter, other than fatigue she denies weight/voice change, tremor, palpitation, anxiety, recent flu like illness or radiation exposure, neck swelling/pain, heat intolerance, or difficulty swallowing. Her daily medications are amlodipine 10mg and duloxetine 20mg. She had menopause 2 years ago. She has no known allergy. She has a brother with rheumatoid arthritis. She denies smoking or alcohol consumption. On exam, vital signs are normal, and BMI is 28.1. There is diffuse, firm thyromegaly without a palpable nodule. There is no cervical lymphadenopathy, tremor, neck tenderness, exophthalmos, or lid lag. Creatinine, liver enzymes are normal but hemoglobin is 9gm/dl. Anti-tissue transglutaminase and anti-gliadin antibodies were negative. Her thyroid labs were: TSH &amp;lt;0.008 uIU/ml, free T4 1.06ng/dl, free T3 4.07 pg/ml (2.3-4.2 pg/ml), total T3 1.74 ng/ml (0.60-1.81 ng/ml), anti-TPO antibody 12,414 U/ml, anti-TG antibody 22 U/ml, thyrotropin receptor antibody (TRAB) 15.24 IU/L (0-1.75 IU/L), and thyroid stimulating immunoglobulin (TSI) 331% (&amp;lt;130%). Thyroid uptake scan showed 49% iodine-131 uptake in symmetric and homogenous uptake, and no hot or cold nodules. GD was diagnosed, methimazole 5mg daily was initiated. Conclusion: Our case had subclinical HT with positive anti-TPO antibodies 5 years preceding the onset of GD. Causes of autoimmune conversion are not well understood. Viral infection or radiation exposure in genetic susceptible patients have been assumed as triggers (1). The blocking and stimulating action of TRAB on TSH receptors is considered as a possible mechanism of switching between hypothyroidism and hyperthyroidism. Clinical and biochemical evaluation for possible conversion to GD in patients with HT is recommended (2).

P104-3 Comprehensive genomic analysis of advanced melanoma with low to no UV radiation exposure in Asian patients

P104-3 Comprehensive genomic analysis of advanced melanoma with low to no UV radiation exposure in Asian patients

CT image reconstruction: integrating iterative methods with Ml-EM algorithm and deep learning models

Computed Tomography (CT) imaging faces limitations, including low spatial resolution and noise, particularly in low-radiation-dose imaging. To address these challenges, researchers are exploring CT image reconstruction from sinogram data. Sinograms represent X-ray absorption throughout the body, and sophisticated image reconstruction methods, including machine learning algorithms and generative adversarial networks (GANs), can improve precision and resolution without increasing patient radiation exposure. This study proposes an iterative reconstruction approach that combines filters from deep learning models (Convolutional Neural Networks and UNet) with the Maximum Likelihood Expectation Maximization (ML-EM) algorithm and the Enhanced Super-Resolution Generative Adversarial Networks (ESRGAN) model. Our method aims to enhance image quality and reconstruction speed. Experimental results show significant improvements in image quality and resolution, with the proposed method (DL-MLEM-IR-UNET-ESRGAN) achieving an average SSIM of 0.9980 and PSNR of 53.2119, outperforming other methods. Additionally, our method reduces reconstruction time, with an average runtime of 131 seconds.

Assessment of occupational radiation exposure during a specific endoscopic retrograde cholangiopancreatography procedure.

The aim of this study was to evaluate the occupational radiation exposure of staff during endoscopic retrograde cholangiopancreatography (ERCP), with a focus on individuals closest to the radiation source, and to identify potential increases in exposure to hands and eye lenses. Patient radiation exposure during ERCP was also assessed. Staff organ doses were monitored using a Philips Allura Xper FD 20 fluoroscopy system, during 24 ERCP procedures for a period of 7months. Staff doses were measured using thermoluminescence dosemeters and electronic personal dosemeters, and patient effective doses were simulated and calculated. Physicians' annual organ doses ranged from 0.2 to 1.6mSv for shoulders, 0.1 to 0.4mSv for eye lenses, and 0.3 to 1.6mSv for fingers. The annual organ dose of the nursing staff ranged from 0.08 to 2.4mSv for shoulders, 0.02 to 2.3mSv for eye lenses, and 1.2 to 5.3mSv for fingers. The effective dose to patients ranged from 0.009 to 0.46mSv. Staff doses were within safe limits, but patient doses were high, emphasizing the need for improved radiation protection.

Improving Image Quality and Diagnostic Performance of CCTA in Patients with Challenging Heart Rate Conditions using a Deep Learning-based Motion Correction Algorithm

Challenging HR conditions, such as elevated Heart Rate (HR) and Heart Rate Variability (HRV), are major contributors to motion artifacts in Coronary Computed Tomography Angiography (CCTA). This study aims to assess the impact of a deep learning-based motion correction algorithm (MCA) on motion artifacts in patients with challenging HR conditions, focusing on image quality and diagnostic performance of CCTA. This retrospective study included 240 patients (mean HR: 88.1 ± 14.5 bpm; mean HRV: 32.6 ± 45.5 bpm) who underwent CCTA between June, 2020 and December, 2020. CCTA images were reconstructed with and without the MCA. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured to assess objective image quality. Subjective image quality was evaluated by two radiologists using a 5-point scale regarding vessel visualization, diagnostic confidence, and overall image quality. Moreover, all vessels with scores ≥ 3 were considered clinically interpretable. The diagnostic performance of CCTA with and without MCA for detecting significant stenosis (≥ 50%) was assessed in 34 patients at both per-vessel and per-patient levels, using invasive coronary angiography as the reference standard. The MCA significantly improved subjective image quality, increasing the vessel interpretability from 89.9% (CI: 0.88-0.92) to 98.8% (CI: 0.98-0.99) (p < 0.001). The use of MCA resulted in significantly higher diagnostic performance in both patient-based (AUC: 0.83 vs. 0.58, p = 0.04) and vessel-based (AUC: 0.92 vs. 0.81, p < 0.001) analyses, with the vessel-based accuracy notably increased from 79.4% (CI: 0.72-0.86) to 91.2% (CI: 0.85-0.95) (p = 0.01). There were no significant differences in objective image quality between the two reconstructions. The mean effective dose in this study was 2.8 ± 1.1 mSv. The use of MCA allows for obtaining high-quality CCTA images and superior diagnostic performance with low radiation exposure in patients with elevated HR and HRV.

Evaluation of the prostate cancer and its metastases in the [ 68 Ga]Ga-PSMA PET/CT images: deep learning method vs. conventional PET/CT processing.

This study demonstrates the feasibility and benefits of using a deep learning-based approach for attenuation correction in [ 68 Ga]Ga-PSMA PET scans. A dataset of 700 prostate cancer patients (mean age: 67.6 ± 5.9 years, range: 45-85 years) who underwent [ 68 Ga]Ga-PSMA PET/computed tomography was collected. A deep learning model was trained to perform attenuation correction on these images. Quantitative accuracy was assessed using clinical data from 92 patients, comparing the deep learning-based attenuation correction (DLAC) to computed tomography-based PET attenuation correction (PET-CTAC) using mean error, mean absolute error, and root mean square error based on standard uptake value. Clinical evaluation was conducted by three specialists who performed a blinded assessment of lesion detectability and overall image quality in a subset of 50 subjects, comparing DLAC and PET-CTAC images. The DLAC model yielded mean error, mean absolute error, and root mean square error values of -0.007 ± 0.032, 0.08 ± 0.033, and 0.252 ± 125 standard uptake value, respectively. Regarding lesion detection and image quality, DLAC showed superior performance in 16 of the 50 cases, while in 56% of the cases, the images generated by DLAC and PET-CTAC were found to have closely comparable quality and lesion detectability. This study highlights significant improvements in image quality and lesion detection capabilities through the integration of DLAC in [ 68 Ga]Ga-PSMA PET imaging. This innovative approach not only addresses challenges such as bladder radioactivity but also represents a promising method to minimize patient radiation exposure by integrating low-dose computed tomography and DLAC, ultimately improving diagnostic accuracy and patient outcomes.