Reduce Patient Radiation Exposure Research Articles

Intraoral Scanning Enables Virtual-Splint-Based Non-Invasive Registration Protocol for Maxillofacial Surgical Navigation.

Background/Objectives: Surgical navigation has advanced maxillofacial surgery since the 1990s, bringing benefits for various indications. Traditional registration methods use fiducial markers that are either invasively bone-anchored or attached to a dental vacuum splint and offer high accuracy but necessitate additional imaging with increased radiation exposure. We propose a novel, non-invasive registration protocol using a CAD/CAM dental splint based on high-resolution intraoral scans. Methods: The effectiveness of this method was experimentally evaluated with an ex vivo 3D-printed skull measuring the target registration error (TRE). Surgical application is demonstrated in two clinical cases. Results: In the ex vivo model, the new CAD/CAM-splint-based method achieved a mean TRE across the whole facial skull of 0.97 ± 0.29 mm, which was comparable to traditional techniques like using bone-anchored screws (1.02 ± 0.23 mm) and dental vacuum splints (1.01 ± 0.33 mm), while dental anatomical landmarks showed a lower accuracy with a mean TRE of 1.84 ± 0.44 mm. Multifactorial ANOVA confirmed significant differences in TRE based on the registration method and the navigated level of the facial skull (p < 0.001). In clinical applications, the presented method demonstrated high accuracy for both midfacial and mandibular surgeries. Conclusions: Our results suggest that this non-invasive CAD/CAM-splint-based method is a viable alternative to traditional fiducial marker techniques, with the potential for broad application in maxillofacial surgery. This approach retains high accuracy while eliminating the need for supplementary imaging and reduces patient radiation exposure. Further clinical trials are necessary to confirm these findings and optimize splint design for enhanced navigational accuracy.

A Whole-Spine Radiography Study to Reduce Patient Exposure Dose and Artifacts Using the EOS Imaging System.

Whole-spine radiography can be accomplished through two methods: (1) segmented imaging employing X-ray tube angulation and detectors, or (2) the Euronext Paris Advanced Orthopedic Solutions (EOS) 2D Imaging system that can capture the entire spine in a single image using X-ray tubes and detectors oriented at a 90-degree angle. This study aimed to establish optimal EOS examination parameters based on patient morphotype and scan speed to reduce patient radiation exposure, repeat examinations, heat stress on equipment, and X-ray tube cooling time. X-ray exposure conditions involved adjustments of scan speed ranging from two to four steps, contingent upon the patient's morphotype ('S', small body; 'M', medium body; and 'L', large body. Patient dose measurements were conducted 20 times for each set of conditions. When transitioning from an 'S' to an 'M' morphotype at a constant scan speed, the entrance skin dose (ESD) exhibited an increase of approximately 41.25 ± 4.57%. A similar change from an 'M' to an 'L' morphotype resulted in an ESD increase of roughly 59.56 ± 24.00%. A transition from an 'S' to an 'L' morphotype at the same scan speed manifested an ESD elevation of approximately 124.21 ± 26.96%. This study underscores significant variations in radiation dose, ranging from 40% to 50%, when altering morphotype while maintaining a consistent scan speed.

Current trends in radiological diagnostics of the temporal bone pyramid pathologies

Diseases of the middle ear and the temporal bone pyramid remain one of the most common diseases in the structure of otorhinolaryngological pathologies, which have a significant impact on the quality of life of adults and children. Exudative processes, as well as their consequences, become one of the main causes of persistent hearing loss and are characterized by an asymptomatic course with a gradual evolution to chronic forms. It should be noted that in childhood the risk of impaired speech and intellectual development increases, leading to changes in the psycho-emotional status, social maladaptation of the child, and a decrease in the quality of life. Timely and complete diagnosis and high-quality follow-up takes a leading role in preventing the development of conductive hearing loss and other complicated pathologies of the temporal bone pyramid.&lt;br /&gt; Purpose of the study. To study the main predisposing factors, methods of radiological diagnosis and dynamic observation of patients, as well as some modern aspects of the treatment of the most common pathologies of the temporal bone pyramid.&lt;br /&gt; Methodology. We conducted an analytical review of open access sources from scientific databases such as Scopus, PubMed, Google Scholar, Web of Science, DisserCat, CyberLeninka. Key words used for the search: “chronic otitis media”, “cholesteatoma”, “mastoiditis”, “complications”, “magnetic resonance imaging”, “DWI”, “computed tomography”. Publications included in the literature review were full-text articles in English and Russian and dissertations in Russian. Exclusion criteria: brief reports, newspaper articles and personal communications. The search range was 5 years (2018-2023). A total of 108 sources were analyzed, of which 50 met the research objectives and inclusion criteria.&lt;br /&gt; Results and conclusions. In the diagnosis of temporal bone pathologies, the gold standard for diagnosis is computed tomography, but non-ionizing research techniques are increasingly used. Indications for the use of magnetic resonance imaging of the temporal bones are constantly expanding, and techniques for merging data with computed tomography data are being increasingly introduced. As a follow-up tool, magnetic resonance therapy is increasingly becoming a priority technique to reduce patient radiation exposure in the long term. In the treatment of complicated forms of diseases, endoscopic and laser correction techniques are used in foreign practice, helping to reduce the risk of recurrence and postoperative complications.&lt;br /&gt; &lt;b&gt;Key words&lt;/b&gt;: chronic otitis media, cholesteatoma, magnetic resonance imaging, computed tomography, treatment

Unsupervised Domain Adaptation for Low-Dose CT Reconstruction via Bayesian Uncertainty Alignment.

Low-dose computed tomography (LDCT) image reconstruction techniques can reduce patient radiation exposure while maintaining acceptable imaging quality. Deep learning (DL) is widely used in this problem, but the performance of testing data (also known as target domain) is often degraded in clinical scenarios due to the variations that were not encountered in training data (also known as source domain). Unsupervised domain adaptation (UDA) of LDCT reconstruction has been proposed to solve this problem through distribution alignment. However, existing UDA methods fail to explore the usage of uncertainty quantification, which is crucial for reliable intelligent medical systems in clinical scenarios with unexpected variations. Moreover, existing direct alignment for different patients would lead to content mismatch issues. To address these issues, we propose to leverage a probabilistic reconstruction framework to conduct a joint discrepancy minimization between source and target domains in both the latent and image spaces. In the latent space, we devise a Bayesian uncertainty alignment to reduce the epistemic gap between the two domains. This approach reduces the uncertainty level of target domain data, making it more likely to render well-reconstructed results on target domains. In the image space, we propose a sharpness-aware distribution alignment (SDA) to achieve a match of second-order information, which can ensure that the reconstructed images from the target domain have similar sharpness to normal-dose CT (NDCT) images from the source domain. Experimental results on two simulated datasets and one clinical low-dose imaging dataset show that our proposed method outperforms other methods in quantitative and visualized performance.

Comparison of Ultra-High-Resolution and Normal-Resolution CT-Angiography for Intracranial Aneurysm Detection in Patients with Subarachnoid Hemorrhage

Ruptured intracranial aneurysms (IAs) are the leading cause for atraumatic subarachnoid hemorrhage. In case of aneurysm rupture, patients may face life-threatening complications and require aneurysm occlusion. Detection of the aneurysm in computed tomography (CT) imaging is therefore essential for patient outcome. This study provides an evaluation of the diagnostic accuracy of Ultra-High-Resolution Computed Tomography Angiography (UHR-CTA) and Normal-Resolution Computed Tomography Angiography (NR-CTA) concerning IA detection and characterization. Consecutive patients with atraumatic subarachnoid hemorrhage who received Digital Subtraction Angiography (DSA) and either UHR-CTA or NR-CTA were retrospectively included. Three readers evaluated CT-Angiography regarding image quality, diagnostic confidence and presence of IAs. Sensitivity and specificity were calculated on patient-level and segment-level with reference standard DSA-imaging. CTA patient radiation exposure (effective dose) was compared. One hundred and eight patients were identified (mean age = 57.8 ± 14.1 years, 65 women). UHR-CTA revealed significantly higher image quality and diagnostic confidence (P < 0.001) for all readers and significantly lower effective dose (P < 0.001). Readers correctly classified ≥55/56 patients on UHR-CTA and ≥44/52 patients on NR-CTA. We noted significantly higher patient-level sensitivity for UHR-CTA compared to NR-CTA for all three readers (reader 1: 41/41 [100%] vs. 28/34 [82%], reader 2: 41/41 [100%] vs. 30/34 [88%], reader 3: 41/41 [100%] vs. 30/34 [88%], P ≤ 0.04). Segment-level analysis also revealed significantly higher sensitivity for UHR-CTA compared to NR-CTA for all three readers (reader 1: 47/49 [96%] vs. 34/45 [76%], reader 2: 47/49 [96%] vs. 37/45 [82%], reader 3: 48/49 [98%] vs. 37/45 [82%], P ≤ 0.04). Specificity was comparable for both techniques. We found Ultra-High-Resolution CT-Angiography to provide higher sensitivity than Normal-Resolution CT-Angiography for the detection of intracranial aneurysms in patients with aneurysmal subarachnoid hemorrhage while improving image quality and reducing patient radiation exposure.

Comparative analysis for variation of skeletal and dental parameters in bilateral cleft palate in central India population – A Nemoceph study

Introduction: An area of dentistry called orthodontics focuses on repositioning crooked teeth and regulating facial development. Orthodontists and oral surgeons use cephalometric analysis as a planning tool for their patient care. Conventional film-based radiography equipment has been replaced with direct digital devices, which have advantages such as reduced patient radiation exposure, immediate radiographic image generation, the removal of the need for darkrooms, and simple image sharing. The second-most typical craniofacial abnormality that results in birth abnormalities is cleft lip and palate. Such patients frequently do not receive cephalometric testing because of their hypoplastic growth and limited development. Research is needed to help plan a standard treatment regimen, perform orthognathic operations, and use a low-radiation analysis technique. Objectives: To evaluate skeletal and dental parameters for cleft lip and palate using Down analysis, Steiner's analysis, and Tweed's analysis using Nemoceph. Methods: Around 50 cases from cleft lip and palate and non-cleft lip and palate will be selected from the orthodontics department of Sharad Pawar Dental College and Hospital. Steiner's, Down's, and Tweed's analyses will be evaluated using Nemoceph. Further analysis will be conducted using the observational data from the readings. There will be millimetre-based measurements made. Comparative analysis will be done with one-way ANOVA and post hoc statistics and regression analysis will be done for association of demographic variables. Expected outcomes: This study will use the nasion as a stable landmark to evaluate point A in cleft lip and palate patients, making it easier to perform normal cephalometric analysis. This will enable the evaluation of the probable position of point A for performing cephalometric analysis in orthodontics.

Einsatz von Patienten-Strahlenschutzmitteln in der diagnostischen und interventionellen Radiologie

The use of patient contact shielding provides an opportunity to reduce patient radiation exposure. Recently, the use has been the subject of controversy. The Radiation Protection Committee has published arecommendation on the use of patient radiation shields by considering the recent findings on dose savings but also the risks of incorrect use. In this article, aspecification for the more frequently used types of X‑ray examination is given, which describes whether and which radiation contact shielding should be used. This is accompanied by arationale for the use or non-use of patient radiation protection agents. Problems and possible errors are explained, as well as how to deal with special situations such as pregnant women and children.

Efficacy of Optical Coherence Tomography-Guided Primary Percutaneous Coronary Intervention in Patients with Acute Coronary Syndrome.

Optical coherence tomography (OCT) is currently used as a guide for percutaneous coronary intervention (PCI), however its clinical benefit in comparison with intravascular ultrasound (IVUS) remains unclear in patients with acute coronary syndrome (ACS). The purpose of this study was to evaluate the clinical efficacy of OCT-guided PCI in comparison with IVUS-guided PCI in patients with ACS. The study participants comprised 280 consecutive ACS patients who underwent primary PCI for de novo culprit lesions under OCT or IVUS guidance. Compared with the IVUS-guided group, the OCT-guided group had lower Killip classification (p < 0.001) and lower creatinine level at baseline (0.80 ± 0.37 mg/dl vs. 1.13 ± 1.29 mg/dl, p = 0.004). Fluoroscopy time and total procedure time were significantly shorter in the OCT-guided group than in the IVUS-guided group (32 ± 13 min vs. 41 ± 19 min, p < 0.001, and 98 ± 39 min vs. 127 ± 47 min, p = 0.002, respectively). The major adverse cardiovascular event-free survival curves were similar between the OCT- and IVUS-guided groups after adjusting for clinical background using propensity score (log-rank p = 0.328). After adjusting for clinical background, OCT-guided PCI could provide comparable clinical outcomes to IVUS-guided PCI in patients with ACS. Shorter fluoroscopy time and total procedure time with OCT may reduce patient radiation exposure and also improve hospital workflow.

Radiation exposure in acute myeloid leukaemia, diffuse large B-cell lymphoma, and multiple myeloma patients in the first year following diagnosis.

Radiological examinations are critical in the evaluation of patients with haematological malignancies for diagnosis and treatment. Any dose of radiation has been shown in studies to be harmful. In this regard, we assessed the radiation exposure of 3 types of haematological malignancies (diffuse large B-cell lymphoma [DLBCL], acute myeloid leukaemia [AML], and multiple myeloma [MM]) in our centre during the first year after diagnosis. In the first year after diagnosis we retrospectively reviewed the radiation exposure data of 3 types of haematological malignancies (DLBCL, AML, and MM). The total and median CED value (cumulative effective radiation dose in millisieverts [mSv]) of each patient was used. Each patient's total and median estimated CED value was calculated using a web-based calculator and recorded in millisieverts (mSv). The total radiation doses in one year after diagnosis (CED value) were 46.54 ± 37.12 (median dose: 36.2) in the AML group; 63.00 ± 42.05 (median dose: 66.4) in the DLBCL group; and 28.04 ± 19.81 (median dose: 26.0) in the MM group (p = 0.0001). There was a significant difference between DLBCL and MM groups. In all 3 haematological malignancies, the radiation exposure was significant, especially in the DBLCL group, within the first year of diagnosis. It is critical to seek methods to reduce these dosage levels. In diagnostic radiology, reference values must be established to increase awareness and self-control and reduce patient radiation exposure. This paper is also the first to offer thorough details on the subject at hand, and we think it can serve as a guide for further investigation.

Helical CT versus intermittent CT fluoroscopic guidance for musculoskeletal needle biopsies: impact on radiation exposure, procedure time, diagnostic yield, and adverse events.

Image-guided percutaneous needle biopsies are essential in the workup of musculoskeletal (MSK) lesions. While helical CT (HCT) is well established, intermittent CT fluoroscopy (iCTF) is an increasingly used alternative. The purpose of this study is to establish whether differences in subject radiation exposure, procedure time, yield, or adverse events exist between HCT and iCTF guidance. This retrospective cohort study included consecutive MSK needle biopsies performed on a single-CT scanner over a 12-month period at a tertiary academic center. Subject demographics, radiation dose, and outcomes were abstracted from the medical record. Comparisons between the two cohorts were performed using Student's t-test for continuous data and using Fisher's exact test for categorical data and a two-tailed p value less than 0.05 was considered significant. Two hundred sixteen adults (115 (53.2%) females) with a mean age of 58.8 ± 18.4years, underwent 216 biopsies (109 (50.5%) HCT guided, 107 (49.5%) iCTF guided) between June 2017 and June 2018. Dose-length product (DLP) and volume CT dose index (CTDIvol) were significantly higher for the HCT cohort (HCT 698.9 ± 400.8 mGycm vs iCTF 312.8 ± 170.8 mGycm; p < 0.005 and HCT 19.1mGy ± 8.8 vs iCTF 6.9mGy ± 1.5, p < 0.001). No significant difference in diagnostic yield, procedure time, or adverse event rate was identified. For CT-guided MSK needle biopsies, iCTF decreases subject radiation dose compared to HCT without negatively affecting outcomes. iCTF should be strongly considered by radiologists performing MSK biopsies given the reduced patient radiation exposure.

Patient radiation exposure from intraoperative computed tomography in spinal surgery

Intraoperative CT imaging is becoming increasingly used, but often little attention is paid to the underlying radiation exposure to the patient. This work showed that the dosimetrically assessed radiation exposure for cervical and lumbar 3D scans with an intraoperative CT is considerably higher than with a 3D C-arm. Therefore, proper selection of the intraoperative 3D imaging system is essential, and further technological developments and dose-saving protocols are warranted to further reduce patient radiation exposure.

Extended D-dimer cut-offs and machine learning for ruling out pulmonary embolism in individuals undergoing computed tomography pulmonary angiography

<b>Combining novel machine learning algorithms with extended D-dimer cut-offs may improve pulmonary embolism prediction and reduce patient radiation exposure resulting from avoidable scans</b>https://bit.ly/3oUKd7X

Effectiveness of a Real-Time X-ray Dosimetry Monitor in Reducing Radiation Exposure in Coronary Procedures: The ESPRESSO-Raysafe Randomized Trial.

Background—Several methods to reduce radiation exposure in the setting of coronary procedures are available on the market, and we previously showed that additional radiation shields reduce operator exposure during radial interventions. We set out to examine the efficacy of real-time personal dosimetry monitoring in a real-world setting of radial artery catheterization. Methods and Results—In an all-comer prospective, parallel study, consecutive coronary diagnostic and intervention procedures were performed with the use of standard radiation shield alone (control group) or with the addition of a real-time dosimetry monitoring system (Raysafe, Billdal, Sweden, monitoring group). The primary outcome was the difference in exposure of the primary operator among groups. Additional endpoints included patient, nurse, second operator exposure and fluoroscopy time. A total of 700 procedures were included in the analysis (n = 369 in the monitoring group). There were no differences among groups in patients’ body mass index (p = 0.232), type of procedure (intervention vs. diagnostic, p = 0.172), and patient sex (p = 0.784). Fluoroscopy time was shorter in the monitoring group (5.6 (5.1–6.2) min vs. 7.0 (6.1–7.7) min, p = 0.023). Radiation exposure was significantly lower in the monitoring group for the patient (135 (115–151) µSv vs. 208 (176–245) µSv, p < 0.0001) but not for the first operator (9 (7–11) µSv vs. 10 (8–11), p = 0.70) and the assistant (2 (1–2) µSv vs. 2 (1–2) µSv, p = 0.121). Conclusions—In clinical daily practice, the use of a real-time dosimetry monitoring device reduces patient radiation exposure and fluoroscopy time without an effect on operator radiation exposure.

Omission of Planning CT Reduces Patient Radiation Exposure during CT-Guided Bone Marrow Biopsy and Aspiration.

The purpose of this study is to evaluate the impact of eliminating a preprocedural planning computed tomography during CT-guided bone marrow biopsy on the technical aspects of the procedure, including patient dose, sample quality, procedure time, and CT fluoroscopy usage. Retrospective analysis of 109 patients between 1 June 2018 and 1 January 2021 was performed. Patients were grouped based on whether they received a planning CT scan. Relative radiation exposure was measured using dose-length product (DLP). Secondary metrics included number of CT fluoroscopic acquisitions until target localization, total number of CT fluoroscopic acquisitions, biopsy diagnostic yield, and procedure time. A total of 43 bone marrow biopsies with planning CT scans (Group 1) and 66 bone marrow biopsies without planning CT scans (Group 2) were performed. The average total DLP for Group 1 and Group 2 was 268.73 mGy*cm and 50.92 mGy*cm, respectively. The mean radiation dose reduction between the groups was 81% (p < 0.0001). Significantly more CT fluoroscopy acquisitions were needed for needle localization in Group 2 than Group 1 (p < 0.0001). Total number of CT fluoroscopy acquisitions was four for Group 1 and eight for Group 2 (p = 0.0002). There was no significant difference between the groups in procedure time or diagnostic yield. Patients without a planning CT scan received more fluoroscopic CT acquisitions but overall were exposed to significantly less radiation without an increase in procedure time.

Interpreting Quality Improvement When Introducing New Technology: A Collaborative Experience in ASD Device Closures.

The objective of this study was to evaluate the impact of the regular introduction of new technologies into interventional cardiac catheterization procedures, in this case new atrial septal defect (ASD) closure devices, while conducting a multi-center collaborative initiative to reduce radiation usage during all procedures. Data were collected prospectively by 8 C3PO institutions between January 1, 2014 and December 31, 2017 for ASD device closure procedures in the cardiac catheterization lab during a quality improvement (QI) initiative aimed at reducing patient radiation exposure. Radiation exposure was measured in dose area product per body weight (µGy*m2/kg). Use of proposed practice change strategies at the beginning and end of the QI intervention period was assessed. Radiation exposure was summarized by institution and by initial type of device used for closure. This study included 602 ASD device closures. Without changes in patient characteristics, total fluoroscopy duration, or number of digital acquisitions, median radiation exposure decreased from 37 DAP/kg to 14 DAP/kg from 2014 to 2017. While all individual centers decreased overall median DAP/kg, the use of novel devices for ASD closure correlated with a temporary period of worsening institutional radiation exposure and increased fluoroscopy time. The introduction of new ASD closure devices resulted in increased radiation exposure during a QI project designed to reduce radiation exposure. Therefore, outcome assessment must be contextualized in QI projects, hospital evaluation, and public reporting, to acknowledge the expected variation during innovation and introduction of novel therapies.

Use of a 2 Dimensional Vessel Navigator Roadmap Decreases Patient Radiation Dose Compared to Standard 3D Mapping for Fenestrated Endovascular Aneurysm Repair

For fenestrated endovascular aneurysm repair (FEVAR), the implementation of the VesselNavigator (Philips Healthcare, Best, The Netherlands) to provide a 3-dimensional vessel roadmap has been shown to reduce patient radiation exposure. Unfortunately, FEVAR radiation doses remain substantial despite utilization of this technology. Traditionally, registration of the live fluoroscopy with the pre-operative CTA is performed via the acquisition of a low-dose cone-beam CT scan. However, this registration can also be accomplished with the acquisition of 2D X-rays using the c-arm in 2 different projection angles. We hypothesized that the 2D image acquisition for vessel roadmap development would result in a significant reduction in patient radiation dose in comparison to the 3D CT registration without compromising image quality or increasing procedural length. This single-center, retrospective study included FEVARs performed from January 2015 to May 2019. For patient data, the cumulative reference air kerma (RAK) was presented as geometric mean and standard deviation. A general linear model with log-normal distribution was used to test the difference in patient RAK between 2D X-ray and 3D CT VesselNavigator registration after adjusting for BMI and the number of vessel fenestrations (1 to 2 vs. 3 to 4). Fluoroscopy time was recorded and used as a surrogate for case complexity. All analyses were done in SAS 9.4 (SAS Institute, Inc., Cary, North Carolina). One hundred and sixty four FEVARs were performed on a Philips Allura Xper FD 20 fluoroscopy system equipped with clarity technology. The VesselNavigator registration was completed using 3D CT mapping in 99 cases and 2D X-rays in 65 procedures. On average, utilization of 2D mapping versus 3D mapping for the VesselNavigator resulted in a 20.4% reduction in patient RAK after controlling for BMI and number of vessel fenestrations, P = 0.0135. There was no significant difference in fluoroscopy time between the 2 study groups (P= 0.81) suggesting that image quality was not compromised by the use of 2D mapping leading to the need for additional fluoroscopy. Acquisition of 2D films rather than a 3D CT scan for VesselNavigator registration allows for a significant reduction in patient radiation dose during FEVAR without increasing the case complexity or compromising image quality.

Patients' Radiation Shielding in Interventional Radiology Settings: A Systematic Review.

As a result of the increasing risk of developing radiation-related complications, many approaches aimed at reducing this risk and enhancing the outcomes of the patient, doctor or device operator have been developed. In this systematic review, we aim to discuss previous investigations that studied patient shielding or protection within the context of selected interventional radiology procedures. We included original studies that used Ka,r, and PKA for the assessment of the outcomes of two procedures: transjugular intrahepatic portosystemic shunt creation (TIPS) and hepatic arterial chemoembolization (HAE). A thorough search strategy was conducted on relevant databases to identify all relevant studies. We included 13 investigations, including 12 cross-sectional studies and one randomized controlled trial. Significant diversity was found among all these studies in terms of the used modalities, which made them hard to compare. However, almost all studies agreed that using novel imaging and interventional modalities is useful when obtaining better outcomes and reducing patient radiation exposure. The use of ultrasound-guided procedures and providing adequate lead curtains has also been recommended by the identified studies in order to minimize the frequency of radiation exposure. The reported Ka,r, and PKA were also variable between studies and were discussed within this study. Our findings indicate that unified guidelines for patient radiation shielding should be urgently investigated.

Optimized Diagnostic Approach to Patients Suspected of Superior Semicircular Canal Dehiscence.

Current methods of diagnosing superior semicircular canal dehiscence syndrome (SCDS) include a clinical exam, audiometric testing, temporal bone computer tomography (CT) imaging, and vestibular evoked myogenic potential (VEMP) testing. The main objective of this study was to develop an improved diagnostic approach to SCDS optimized for accuracy, efficiency, and safety that utilizes clinical presentation, audiometric testing, CT imaging, high-frequency cervical VEMP (cVEMP) testing, and patient treatment preference. A secondary aim was to investigate the cost associated with the current versus proposed diagnostic paradigms. All patients who underwent cVEMP testing since introduction of the 2 kHz cVEMP in our clinical protocol in July 2018 were screened. Patients suspected of SCDS based upon symptoms who also had available audiogram, CT scan, and 2 kHz cVEMP were included (58 ears). Patients were categorized as dehiscent, thin, or not dehiscent based on their CT scan. Symptom prevalence and cVEMP outcomes were analyzed and compared for all groups. The accuracy of the 2 kHz cVEMP was calculated using CT imaging as the standard. Using a combination of patient symptomatology, audiometric, CT and 2 kHz cVEMP data, as well as patient preference, a best clinical practice approach was developed. The cost associated with this approach was calculated and compared with cost of the current SCDS diagnostic workup using Medicare reimbursement rates. In the overall patient population suspected of SCDS based on clinical presentation, the sensitivity and specificity of 2 kHz cVEMP were 76% and 100%, respectively, while the positive and negative predictive values were 100% and 84.6%, assuming that the CT scan finding was correct. Autophony was the most common symptom in patients who had both superior semicircular canal dehiscence on CT imaging plus abnormal 2 kHz cVEMP (p < 0.001). Combining patient symptomatology, 2 kHz normalized peak to peak cVEMP amplitude, and patient treatment preference to determine, which patients should undergo CT scanning resulted in a potential cost reduction between 45% and 61%. In patients suspected of SCDS based on their clinical presentation, the combination of symptomatology, 2 kHz cVEMP data, and patient preference can be used to determine which patients should undergo CT scanning, resulting in a diagnostic cost reduction and reduced patient radiation exposure.

Worldwide Variation in the Use of Nuclear Cardiology Camera Technology, Reconstruction Software, and Imaging Protocols

ObjectivesThis study sought to describe worldwide variations in the use of myocardial perfusion imaging hardware, software, and imaging protocols and their impact on radiation effective dose (ED). BackgroundConcerns about long-term effects of ionizing radiation have prompted efforts to identify strategies for dose optimization in myocardial perfusion scintigraphy. Studies have increasingly shown opportunities for dose reduction using newer technologies and optimized protocols. MethodsData were submitted voluntarily to the INCAPS (International Atomic Energy Agency Nuclear Cardiology Protocols Study) registry, a multinational, cross-sectional study comprising 7,911 imaging studies from 308 labs in 65 countries. The study compared regional use of camera technologies, advanced post-processing software, and protocol characteristics and analyzed the influence of each factor on ED. ResultsCadmium-zinc-telluride and positron emission tomography (PET) cameras were used in 10% (regional range 0% to 26%) and 6% (regional range 0% to 17%) of studies worldwide. Attenuation correction was used in 26% of cases (range 10% to 57%), and advanced post-processing software was used in 38% of cases (range 26% to 64%). Stress-first single-photon emission computed tomography (SPECT) imaging comprised nearly 20% of cases from all world regions, except North America, where it was used in just 7% of cases. Factors associated with lower ED and odds ratio for achieving radiation dose ≤9 mSv included use of cadmium-zinc-telluride, PET, advanced post-processing software, and stress- or rest-only imaging. Overall, 39% of all studies (97% PET and 35% SPECT) were ≤9 mSv, while just 6% of all studies (32% PET and 4% SPECT) achieved a dose ≤3 mSv. ConclusionsNewer-technology cameras, advanced software, and stress-only protocols were associated with reduced ED, but worldwide adoption of these practices was generally low and varied significantly between regions. The implementation of dose-optimizing technologies and protocols offers an opportunity to reduce patient radiation exposure across all world regions.

In Vivo Pretargeting Based on Cysteine-Selective Antibody Modification with IEDDA Bioorthogonal Handles for Click Chemistry.

Pretargeted imaging has emerged as an effective multistep strategy aiming to improve imaging contrast and reduce patient radiation exposure through decoupling of the radioactivity from the targeting vector. The inverse electron-demand Diels-Alder (IEDDA) reaction between a trans-cyclooctene (TCO)-conjugated antibody and a labeled tetrazine holds great promise for pretargeted imaging applications due to its bioorthogonality, rapid kinetics under mild conditions, and formation of stable products. Herein, we describe the use of functionalized carbonylacrylic reagents for site-specific incorporation of TCO onto a human epidermal growth factor receptor 2 (HER2) antibody (THIOMAB) containing an engineered unpaired cysteine residue, generating homogeneous conjugates. Precise labeling of THIOMAB-TCO with a fluorescent or radiolabeled tetrazine revealed the potential of the TCO-functionalized antibody for imaging the HER2 after pretargeting in a cellular context in a HER2 positive breast cancer cell line. Control studies with MDA-MD-231 cells, which do not express HER2, further confirmed the target specificity of the modified antibody. THIOMAB-TCO was also evaluated in vivo after pretargeting and subsequent administration of an 111In-labeled tetrazine. Biodistribution studies in breast cancer tumor-bearing mice showed a significant activity accumulation on HER2+ tumors, which was 2.6-fold higher than in HER2- tumors. Additionally, biodistribution studies with THIOMAB without the TCO handle also resulted in a decreased uptake of 111In-DOTA-Tz on HER2+ tumors. Altogether, these results clearly indicate the occurrence of the click reaction at the tumor site, i.e., pretargeting of SK-BR-3 HER2-expressing cells with THIOMAB-TCO and reaction through the TCO moiety present in the antibody. The combined advantages of site-selectivity and stability of TCO tagged-antibodies could allow application of biorthogonal chemistry strategies for pretargeting imaging with minimal side-reactions and background.