Search

This review discusses the current state of artificial intelligence (AI) in 18F-NaF-PET/CT imaging and the potential applications to come in diagnosis, prognostication, and improvement of care in patients with bone diseases, with emphasis on the role of AI algorithms in CT bone segmentation, relying on their prevalence in medical imaging and utility in the extraction of spatial information in combined PET/CT studies.

Background Omission errors in medical imaging can lead to missed diagnosis and harm to patients. The subject has been studied in conventional imaging, but no data is available for functional imaging in general and for PET/CT in particular. In this work, we evaluated the frequency and characteristics of perceptual omission errors in the PET component of oncologic PET/CT imaging and we analyze the hazardous scenarios prone to such modality-specific errors. Materials and methods Perceptual omission errors were collected in one tertiary center PET/CT clinic during routine PET/CT reporting over a 26-month period. The omissions were detected either in reporting follow-up PET/CT studies of the same patient or during multidisciplinary meetings. Results Significant omission errors were found in 1.2 % of the 2100 reports included in the study. The most common omissions were bone metastases and focal colon uptake. We identified six PET-specific causative factors contributing to the occurrence of omissions, and we propose solutions to minimize their influence. Conclusions The data presented here can help to promote the awareness of interpreting physicians to body areas that require higher attention and to implement reading strategies for improving the accuracy of PET/CT interpretation.

Introduction Coronavirus disease 2019 (COVID‐19) has infected over 215 million individuals worldwide. Chest radiographs (CXR) and computed tomography (CT) have assisted with diagnosis and assessment of COVID‐19. Previous reports have described peripheral and lower zone predominant opacities on chest radiographs. Whilst the most common patterns on CT are bilateral, peripheral basal predominant ground glass opacities (Wong et al., Radiology, 296, 2020, E72; Karimian and Azami, Pol J Radiol, 86, 2021, e31). This study describes the imaging findings in an Australian tertiary hospital population. Methods COVID‐PCR‐positive patients who had chest imaging (CXR, CT and ventilation perfusion (V/Q) scans) from January 2020 to August 2020 were included. Distribution, location and pattern of involvement was recorded. Evaluation of the assessors was performed using Fleiss Kappa calculations for review of radiographic findings and qualitative analysis of CT findings. Results A total of 681 studies (616 CXRs, 59 CTs, 6 V/Q) from 181 patients were reviewed. The most common chest radiograph finding was bilateral lower lobe predominant diffuse opacification and most common CT pattern being ground glass opacities. Of the CT imaging, 33 were CT Pulmonary Angiograms of which five demonstrated acute pulmonary emboli. There was good inter‐rater agreement between radiologists in assessment of imaging appearances on CXR (kappa 0.29–0.73) and CT studies. Conclusion A review of imaging in an Australian tertiary hospital demonstrates similar patterns of COVID‐19 infection on chest X‐ray and CT imaging when compared to the international population.

Background. Sinonasal diseases are widespread in childhood. Radiological studies, including computer tomography, are an optimal and effective method of diagnosis. The child's body is more sensitive to radiation exposure than adults. The threshold of exposure, which may induce internal organs injury in children, requires a precise selection of the radiological method with minimal radiation dose. There is currently no unified position in the professional community on the appropriateness of the use of ultra-low-dose computed tomography in pediatrics.We reviewed the data on the appropriateness and effectiveness of paranasal low-dose computed tomography in pediatrics.Materials. 57 domestic and foreign publications, for the period from January 2001 to November 2019. In order to achieve the objective, we analyzed relevant domestic and foreign publications in scientific libraries e-LIBRARY, PubMed, Google Scholar per the keywords: “low-dose CT”, “children”, “paranasal sinus”, “pediatric”, “diagnosis”, “children”, “low-dose computed tomography”, “sinusitis”, “paranasal sinuses”.Results. The analysis of the available literature allowed summarizing the current data on pediatric paranasal disease diagnostics and the use of computed tomography, as well as to identify possible options for reducing radiation dose.Conclusions. Conducting many radiological examinations in a child leads to the risk of cancer. However, these examinations are an effective way to diagnose paranasal diseases, and a CT scan is the “gold standard”. The actual task is to develop a CT technique with reduced radiation exposure without compromising image quality. The need to review and optimize the standard protocols of radiological studies to determine the efficacy and feasibility of studies with minimal radiation exposure to children is justified.

Background Nowadays, PET/CT plays a substantial role in the diagnosis of different types of tumor by its ability to provide combined functional and anatomic imaging in the same session. The purpose of this study is to evaluate the added value of PET/CT in staging and re-staging of primary malignant bone tumors. Results Out of the studied 40 patients, 7 patients were referred for primary staging of different types of histologically proven primary malignant bone tumors, their FDG-PET/CT studies yielded additional diagnostic information in 28.6% of them. Thirty three patients were referred either for assessment of treatment response or for follow-up to detect any viable lesions; FDG-PET/CT was more sensitive and specific than CT in follow-up and assessment of treatment response with PET/CT sensitivity 94.4%, specificity 86.7%, and total accuracy 90.9% and CT sensitivity 88.2%, specificity 81.2%, and total accuracy 84.8%. Conclusions PET/CT was an accurate imaging modality in evaluation of primary malignant bone tumors regarding tumor staging, assessment of therapeutic response and detection of metastatic disease as compared to CT.

Recently, machine learning has outperformed established tools for automated segmentation in medical imaging. However, segmentation of cardiac chambers still proves challenging due to the variety of contrast agent injection protocols used in clinical practice, inducing disparities of contrast between cavities. Hence, training a generalist network requires large training datasets representative of these protocols. Furthermore, segmentation on unenhanced CT scans is further hindered by the challenge of obtaining ground truths from these images. Newly available spectral CT scanners allow innovative image reconstructions such as virtual non-contrast (VNC) imaging, mimicking non-contrasted conventional CT studies from a contrasted scan. Recent publications have demonstrated that networks can be trained using VNC to segment contrasted and unenhanced conventional CT scans to reduce annotated data requirements and the need for annotations on unenhanced scans. We propose an extensive evaluation of this statement. We undertake multiple trainings of a 3D multi-label heart segmentation network with (HU-VNC) and without (HUonly) VNC as augmentation, using decreasing training dataset sizes (114, 76, 57, 38, 29, 19 patients). At each step, both networks are tested on a multi-vendor, multi-centric dataset of 122 patients, including different protocols: pulmonary embolism (PE), chest-abdomen-pelvis (CAP), heart CT angiography (CTA) and true non-contrast scans (TNC). An in-depth comparison of resulting Dice coefficients and distance metrics is performed for the networks trained on the largest dataset. HU-VNC-trained on 57 patients significantly outperforms HUonly trained on 114 regarding CAP and TNC scans (mean Dice coefficients of 0.881/0.835 and 0.882/0.416, respectively). When trained on the largest dataset, significant improvements in all labels are noted for TNC and CAP scans (mean Dice coefficient of 0.882/0.416 and 0.891/0.835, respectively). Adding VNC images as training augmentation allows the network to perform on unenhanced scans and improves segmentations on other imaging protocols, while using a reduced training dataset.

Objectives This study sought to assess training volumes and its relationship to learning and identify potential new thresholds for determining expertise. Background Competency-based medical education (CBME) is being rapidly adopted and therefore training programs will need to adapt and identify new and novel methods of defining, measuring, and assessing clinical skills. Methods Consecutive cardiac computed tomography (CT) studies were interpreted independently by trainees and expert readers, and their interpretations (Agatston score, coronary artery disease severity, and Coronary Artery Disease Reporting and Data System) were collected. Kappa agreements were measured between trainees and experts for every 50 consecutive cases. Agreements between trainees and experts were tracked and compared with the agreement between expert readers. Results A total of 36 trainees interpreted 14,432 cardiac CT studies. Agreement between trainees and experts increased with CT case volumes, but trainees learned at different rates. Using a threshold for expertise, skill of measuring coronary calcification was achieved within 50 cases, but expertise for coronary CT angiography appeared to require a mean case volume of 750, comprising 400 abnormal cases. Conclusions Current volume-based training guidelines may be insufficient and higher case volumes may be required. We demonstrate that tracking cardiac CT learners is feasible and that CBME could be incorporated into CT training programs.

Anti-COVID-19 vaccination has created new challenges. Lymphadenopathy (LA) with increased uptake in patients undergoing PET/CT may mislead to unnecessary further evaluation. We have analyzed routinely performed PET/CT studies following Pfizer-BioNTech vaccination to familiarize with PET/CT appearances with various PET tracers and to prevent consequences of misinterpretation. Methods: 1281 PET/CT studies performed between January 01 2021 and February 15 2021 were analyzed. Information about dates and site of vaccination was collected. Visual and semi-quantitative analysis of axillary - neck LA and arm uptake was correlated with immunization data. Results: Increased uptake in unilateral axillary LA was observed in 66% vaccinated patients, in 55% vaccinated once and in 69% vaccinated twice. Intensity of uptake decreased over time. 64/315 patients (20%) had simultaneous increased activity in the posterior arm and ipsilateral axillary LA ("double sign" [DS]). Sensitivity, specificity, PPV and NPV of axillary LA and DS were 55.4%, 83.6%, 86.7%, 49.2% and 38.6%, 100%, 100% and 66.1%, respectively. No DS was observed later than 10 and 21 days after first and the second vaccinations, respectively. None of the non-vaccinated patients had arm uptake or DS. Conclusion: Anti-COVID-19 vaccination frequently causes non-specific axillary LA with increased PET tracer activity. In one fifth of our study population this was associated with increased uptake at the vaccination site, DS. DS was 100% specific with 100% PPV for p/vaccination LA hence enabling to avoid misinterpretation of PET/CT studies and further unnecessary evaluation.

Objective Identify acceptable implant corridors in the normal canine thoracic vertebrae (T) from T1 to T9. Study design Retrospective study. Sample population Computed tomographic (CT) studies of normal canine thoracic spines (n = 39). Methods CT imaging studies of normal T1-T9 canine spines were evaluated by five independent observers. Each identified a proposed corridor, measured the width, length, and angle off mid-sagittal that the corridor occupied. Results CT studies were from 39 dogs weighing 3.19-60 kg (mean 10.72, SD 9.9 kg). Vertebral corridors ranged in average width from 3.8 to 5.2 mm, the widest being located at T1. They ranged in average length from 13.3 to 17.5 mm, shortest being T1 and longest being T6. The angle of corridors varied the most between individual vertebrae at T1-T3. The average corridor angles were: T1 = 38°, T2 = 32°, T3 = 27°, T4 = 26°. T5-T9 angle ranged from 23° to 24°. Conclusion The average dimensions of corridors measured in dogs weighing 3.1-60 kg were consistent with those of commercially available cortical screws and pins. Clinical significance Corridor trajectories identified in this population can be achieved from a dorsal approach between T5 and T9. A dorsal approach for implant placement would be challenging for T1-T4 due to the variability found in these vertebrae as well as regional anatomical constraints.

The very high cycle fatigue (VHCF) behavior of an additively manufactured aluminum alloy, AlSi10Mg-T6, has been studied to better understand the role of process-related defects on fatigue life and, in particular, initiation and small crack propagation behavior. Ultrasonic fatigue methodologies were used for the determination of an operative fatigue strength for lifetimes in the range of 108-109 cycles. Fatigue crack growth rates were determined for small fatigue cracks that initiated and grew from artificially produced (FIB) surface defects in specimens subjected to ultrasonic fatigue. X-ray computed tomography (CT) was used in an effort to detect possible crack initiation and growth in specimens cycled for fractions of the nominal VHCF fatigue strength. From the baseline fatigue experiments using fully reversed loading (R = − 1), a nominal fatigue strength of 90 MPa was established for lifetimes in the 108-109 range, and this maximum stress value was used in subsequent crack growth and CT studies. Using ultrasonic fatigue allowed very slow average crack growth rates on the order of 10−11 m/cycle at a °ΔK of 1.5 Mpa m1/2. Small crack growth from FIB-produced micronotches appeared to be transgranular and non-crystallographic. While modest increase in size of some features identified by x-ray CT for interrupted fatigue tests, particularly at defects characterized as flat or oblate spheroids, no definitive evidence of the emergence of a fatal crack from a single defect was observed. This contrasts with the fatigue behavior of as-built AM AlSi10Mg alloy, where porosity-dominated fatigue crack initiation and the size and type of defects can be correlated with fatigue lifetimes.

Background. In the structure of malignant neoplasms, basal cell skin cancer (BCC) occupies a leading position. In the initial stages of a malignant neoplasm, the main treatments are local treatment methods, both surgical and radiation. However, in about 1.3 % of cases, BCC can become locally or metastatic in which local treatment methods are limited. With the development of targeted drugs, such as the Hedgehog pathway inhibitor, the possibilities for effective and safe treatment of this category of patients have appeared.The objective is to present the clinical case of treating a patient with BCC who is receiving systemic therapy with a Hedgehog signaling pathway inhibitor.Case report. According to the patient, a tumor in the lower eyelid of the left eye appeared in 2000, did not seek medical help. In 2011, he applied to the clinic and was diagnosed with skin cancer of the lower eyelid of the left eye T2bN0M0. The patient refused the proposed treatment. Reapplied only in June 2017 already with a locally distributed process. The case is recognized as unresectable. From June 30, 2017 to September 4, 2017, he underwent a course of a radical program of radiotherapy, with a positive effect. 07/01/2019, he relapsed with a relapse of an orbital tumor on the left. From July 16, 2019, the patient began taking the drug wismodegib 150 mg once a day. Against the background of the treatment, control CT studies on 11/24/2019 and 11/03/2020 compared with CT data from 07/09/2019 reduced the volume of the tumor by 78 and 82 %. The patient currently continues to take wismodegib.Conclusion. The clinical case demonstrates successful treatment of locally advanced basal cell skin cancer with a Hedgehog signaling pathway inhibitor.

Highly permeable asphalt mixtures are prone to moisture damage leading to reduction in pavement service life. This study correlates dense-graded asphalt mixture’s air voids with its permeability. As permeability initiates due to significant interconnectivity of air voids, the relation between total air voids (TAVs) and connected air voids (CAVs) requires a critical review. Permeability of laboratory-compacted asphalt specimens was measured in the laboratory using four different permeameters. Conventional and Baily methods were utilized to develop aggregate gradations for asphalt mixtures. Different testing techniques were also used to ascertain the amount of CAVs, as aggregate gradation affects the airvoids significantly. An equation, based upon Darcy’s law, while assuming equilibrium of inflow/outflow of water to and from asphalt sample was proposed to determine the CAVs in the asphalt mix. The digital images of asphalt specimens were captured, and digital computed tomography (CT) technique was employed using ImageJ software for validation of the CAVs estimated from the relationship. It was observed that air voids, especially CAVs, and type of aggregate gradation have significant effects on permeability of asphalt mixture. The Baily modified mixes exhibited lower permeability. The permeability also increased with an increase in nominal maximum aggregate size. The interconnected pores, determined with the help of digital CT technique, validate the values of air voids estimated from the proposed relationship.

Background A retrospective multicentric study gathered 1439 CT chest studies with suspected coronavirus disease 2019 (COVID-19) affection. Three radiologists, blinded to other results, interpreted all studies using both lexicons with documentation of applicability and preferred score in assessing every case. The purpose of the study is to assess COVID-19 standardized assessment schemes’ (CO-RADS and COVID-RADS lexicons) applicability and diagnostic efficacy. Results This study included 991 RT-PCR-confirmed CT studies. An almost perfect agreement was found in COVID-RADS among the three observers (Fleiss Kappa = 0.82), opposed by a substantial agreement in CO-RADS (Κ = 0.78). The preference records favor COVID-RADS/CO-RADS in 78.5%/12.5%, 75.5%/24.5%, and 73.4%/24.5% regarding the three radiologists’ records, respectively. The distinguishability between positive and negative RT-PCR cases was 0.92 for COVID-RADS, while it was 0.85 for CO-RADS. On the other hand, both lexicons’ performance regarding clinical diagnosis and clinical suspicion index was 0.93 for COVID-RADS and 0.94 for CO-RADS. A very high to excellent agreement between the three observers for COVID-RADS/CO-RADS preference was concluded (Fleiss Kappa = 0.80 to 0.94). These results were statistically significant (p < 0.001). Conclusion Both lexicon scores (CO-RADS and COVID-RADS) were found to be applicable in the COVID-19 structured report with the preference of COVID-RADS in more than 50% of cases. The diagnostic accuracy of COVID-RADS against RT-PCR was higher than that of CO-RADS.

For 99mTc-sestamibi parathyroid single photon emission computed tomography/computed tomography (SPECT/CT), the traditional full-arc 360° acquisition technique has been suggested but not the theoretically low tissue-attenuated anterior 180° method. We aimed to compare the diagnostic performances and target-to-background ratios of anterior 180° and 360° SPECT/CT imaging. Ninety-nine patients who underwent 99mTc-sestamibi scintigraphy and received a surgical–pathological diagnosis of parathyroid adenoma or hyperplasia were enrolled. The SPECT/CT reconstructed images with anterior 180° and full-arc 360° data were interpreted by two physicians using a scoring scale, and the lesions were semi-quantified using target-to-background ratios for both image sets. In total, 113 abnormal parathyroid lesions were identified on the SPECT/CT images. The agreements of interpretation between the two image sets and readers were very good (κ value: 0.83–1.00). The accuracies of summative interpretation for the anterior 180° and full-arc 360° SPECT/CT were 83.04% and 82.46%, respectively. The target-to-background ratios were significantly higher for the anterior 180° than the full-arc 360° images (P

Introduction SARS-CoV-2, the virus responsible for the current pandemic, predominantly affects the respiratory tract, and a growing number of publications report the predisposition of patients with COVID-19 to develop thrombotic phenomena. Objective To determine the prevalence of pulmonary embolism in patients with COVID-19; to determine the possible relationship between the severity of pulmonary involvement and d-dimer levels; to analyze the location of pulmonary embolisms in patients with COVID-19 and to compare it with the location in patients without COVID-19. Methods This retrospective study analyzed all CT angiograms of the pulmonary arteries done in patients with suspected pulmonary embolisms between March 15 and April 30, 2020 and compared them with studies done in the same period one year earlier. Results We included 492 pulmonary CT angiograms (342 (69.9%) in patients with COVID-19 and 147 (30.1%) in patients without COVID-19). The prevalence of pulmonary embolisms was higher in patients with COVID-19 (26% vs. 16.3% in patients without COVID-19, p = 0.0197; relative risk = 1.6). The prevalence of pulmonary embolisms in the same period in 2019 was 13.2%, similar to that of the group of COVID-19-negative patients in 2020 (p = 0.43). There were no significant differences in d-dimer levels or the location of pulmonary embolisms between the two groups. CT showed moderate or severe pulmonary involvement in 78.7% of the patients with COVID-19. Conclusions Patients with COVID-19 have an increased prevalence of pulmonary embolisms (26%), and most (78.7%) have moderate or severe lung involvement on CT studies. The location of pulmonary embolisms and the degree of elevation of d-dimer levels does not differ between patients with COVID-19 and those without.

The pandemia caused by the SARS-CoV-2 virus has triggered an unprecedented health and economic crisis. Although the diagnosis of infection with SARS-CoV-2 is microbiological, imaging techniques play an important role in supporting the diagnosis, grading the severity of disease, guiding treatment, detecting complications, and evaluating the response to treatment. The lungs are the main organ involved, and chest X-rays, whether obtained in conventional X-ray suites or with portable units, are the first-line imaging test because they are widely available and economical. Chest CT is more sensitive than plain chest X-rays, and CT studies make it possible to identify complications in addition to pulmonary involvement, as well as to suggestive alternative diagnoses. The most common radiologic findings in COVID-19 are airspace opacities (consolidations and/or ground-glass opacities), which are typically bilateral, peripheral, and located primarily in the lower fields.

18F-FDG PET/CT is the most widely used diagnostic modality for detection of malignant disease. Beside the visual insight of FDG pathways into the human body, PET/CT can give valuable information based on the SUV values. The SUV is a quantitative parameter of metabolic activity. FDG application has 2 major impacts on PET/CT: qualitative aspect (visual insight of FDG in the body) and quantitative aspect (degradation of the SUV values). Based on the literature, FDG extravasation incidence is 31% for all PET/CT studies and in 8% of all cases extravasation has been visually confirmed since the application place has been in the field of view. By constantly developing the technique, work methodology and increasing the quality control of the staff in the PET/CT department, the incidence of extravasation can be significantly reduced based on the results from the literature. In the case when paravenous injection is present on PET/CT images we can use certain software procedures to improve image quality and SUV quanitification.

Variation of visual selective attention through the day has been demonstrated in several arenas of human performance, including radiology. It is uncertain whether this variation translates to an identifiable diurnal pattern of error rates for radiology interpretation. The purpose of this study was to attempt to identify particular days of the week and times of the day when radiologists might be most prone to error. Abdomen/pelvis CT studies containing at least one major error were collected from a 10-year period from the quality assurance (QA) database at our institution. A major error was defined as a missed finding that had altered management in a way potentially detrimental to the patient. The identified studies were categorized by the day of the week and hour of the day that the study was interpreted. Study volume data over this same period was also obtained by day of the week and time of day, so to normalize the data based on case volume. Standard errors of the volume-adjusted error rates were obtained based on the binomial distribution. The null hypothesis of constant error rates over time was tested using a weighted logistic regression model with linear time as predictor. A total of 252 major errors were identified. More errors were made on Monday than on any other day of the week (n = 58). Major error rates increased through the mid to late morning (9 am to 12 pm), and then decreased progressively through the afternoon until 4 pm, when a rise in the error rate was seen. This pattern persisted when error rates were normalized by study volume within each hour. Overall tests of time-constancy of error rates by day and hour were statistically significant (both p-values

OBJECTIVE. We reviewed a retrospective series of 126 18F-fluciclovine PET/CT studies of patients with biochemically recurrent prostate cancer at low (< 1 ng/mL) and very low (< 0.3 ng/mL) prostate-specific antigen (PSA) levels. CONCLUSION. The rate of PET/CT positivity was 33% (15/46) in patients with low PSA levels and 0% (0/17) in patients with very low PSA levels. Our results suggest that 18F-fluciclovine PET/CT can be helpful for localizing recurrence in patients with PSA levels between 0.3 and 1 ng/mL and that 18F-fluciclovine PET/CT is not recommended in patients with PSA levels less than 0.3 ng/mL.

The gold standard for diagnosing injuries in polytrauma is computed tomography (CT) of the whole body. This method of radiation diagnostics allows to quickly and non-invasively obtain high-resolution images for an accurate assessment of all trauma-related injuries. To date, there are different opinions on the optimal algorithm for conducting and evaluating CT in patients with polytrauma, but a unified standard of research methods for this category of patients has not been developed. This article presents the experience of various domestic and foreign hospitals providing medical care to patients with various types of combined and multiple injuries, as well as describes methodological recommendations for performing and analyzing CT of the whole body in patients with polytrauma, obtained on the basis of our own practical experience. In the article, we also reflected the peculiarities of the interpretation of the resulting traumatic injuries in the native, arterial, venous and delayed phases of scanning; clinical examples of CT studies in patients with polytrauma are given. We noted the particular importance of postprocessing processing of images obtained during CT examination. Here, we recommend performing CT of the whole body in polytrauma with the use of multiphase intravenous bolus contrasting, which allows a more detailed assessment of the changes in internal organs and soft tissues and diagnoses the presence and nature of bleeding. Comprehensive and detailed evaluation of CT images obtained in patients with polytrauma is aimed at helping clinical specialists choose the best treatment method, prioritizing and predicting patient management in each case.

Due to the widespread introduction of CT in clinical practice, the issue of reducing the radiation dose remains one of the most urgent. One of the ways to reduce radiation exposure is to improve the reconstruction algorithms of CT images. When using model interactive reconstruction, images are repeatedly processed to maximize the elimination of digital noise, which allows lowdose studies to be performed without compromising visual quality. The literature review presents the possibilities of applying model iterative reconstruction in CT studies of various organs and systems, including low-dose studies with a radiation exposure of less than 1 mSv, assessment the quality of studies and visualization of the pathology of various organs and systems. The most popular new technique is for screening studies, for example, for LDCT screening of lung cancer, and studies that require high resolution, for example, for CT-coronarography.

OBJECTIVE. The purpose of this study was to determine whether contrast medium volume and method of administration and baseline estimated glomerular filtration rate influence the efficacy of prophylactic hydration for prevention of acute kidney injury after contrast administration. MATERIALS AND METHODS. An online search of PubMed conducted on August 25, 2017, produced a total of 697 studies. After the reports were reviewed, nine were included in this study. The extracted data on all patients in these studies were separated into a group that received prophylactic hydration and a group that did not. The following three parameters were used for subgroup analysis: contrast medium volume, contrast administration method, and baseline estimated glomerular filtration rate. The t test was performed, and study-level odds ratios with 95% CIs and p values were calculated. Tests of heterogeneity were conducted. RESULTS. When the volume of contrast agent administered exceeded 100 mL, hydration was beneficial in the prevention of contrast-induced acute kidney injury (odds ratio, 0.546). If the volume was less than 100 mL, hydration had no efficacy in preventing contrast-induced acute kidney injury (odds ratio, 0.917). Administration route and baseline estimated glomerular filtration rate exerted no effect on the efficacy of prophylactic hydration. CONCLUSION. For patients who receive less than 100 mL of contrast medium, the prevalent practice for contrast-enhanced CT studies, prophylactic hydration may not be necessary, regardless of the estimated glomerular filtration rate or route of contrast administration. For patients undergoing procedures requiring administration of large volumes of contrast medium, however, hydration is recommended to prevent contrast-induced acute kidney injury.

The aim of this study was to investigate the value of multiple parameters retrieved from the FDG PET/CT studies, including SUVmax, SUVmean, SUVpeak, MTV, TLG, tumour size in differentiating retroperitoneal paragangliomas from UCD. 28 patients with solitary retroperitoneal masses who had undergone preoperative 18F-FDG PET/CT were retrospectively evaluated. Histopathology by surgical resection confirmed 17 paragangliomas and 11 UCDs. SUVmax, SUVmean, SUVpeak, MTV, TLG, and tumour size of 18F-FDG PET/CT were measured for each patient. Mann–Whitney U-test was used to assess differences in multiple parameters between paragangliomas and UCDs. The ROC curve analysis was performed to determine the differential diagnostic value of these parameters. Paragangliomas presented significantly higher SUVmax (P P = 0.001), SUVpeak (P P = 0.024) than UCDs, whereas no significant difference was observed in MTV. The AUCs for differentiating paragangliomas and UCDs were 0.920, 0.888, 0.909, and 0.765 for SUVmax, SUVmean, SUVpeak, and TLG, respectively. The SUVmax cut-off of 7.75 yielded 82.4% sensitivity and 100% specificity for predicting paragangliomas. This study indicated that 18F FDG PET/CT-derived multiple metabolic parameters are useful in distinguishing between paragangliomas and UCDs. SUVmax showed the best result for the differential diagnosis of these two diseases among multiple metabolic parameters.

Purpose: The radiographic diagnosis of lung nodules is associated with low sensitivity and specificity. Computer-aided detection (CAD) system has been shown to have higher accuracy in the detection of lung nodules. The purpose of this study is to assess the effect on sensitivity and specificity when a CAD system is used to review chest radiographs in real-time setting. Methods: Sixty-three patients, including 24 controls, who had chest radiographs and CT within three months were included in this study. Three radiologists were presented chest radiographs without CAD and were asked to mark all lung nodules. Then the radiologists were allowed to see the CAD region-of-interest (ROI) marks and were asked to agree or disagree with the marks. All marks were correlated with CT studies. Results: The mean sensitivity of the three radiologists without CAD was 16.1%, which showed a statistically significant improvement to 22.5% with CAD. The mean specificity of the three radiologists was 52.5% without CAD and decreased to 48.1% with CAD. There was no significant change in the positive predictive value or negative predictive value. Conclusion: The addition of a CAD system to chest radiography interpretation statistically improves the detection of lung nodules without affecting its specificity. Thus suggesting CAD would improve overall detection of lung nodules.

Purpose To assess the impact of the Covid-19 pandemic on FDG-PET/CT work volume and to evaluate the occurrence of abnormal imaging findings suspicious or potentially diagnostic for interstitial pneumonia by Covid-19 infection in south Italy. Methods We retrospectively reviewed the number and the findings of FDG-PET/CT studies acquired between February and April 2020 during the Covid-19 pandemic at the University of Napoli Federico II. The number and the findings of FDG-PET/CT studies acquired in the corresponding period of 2019 were also assessed for direct comparison. Results The number of FDG-PET/CT studies performed during the pandemic (n = 299) and in the corresponding period of 2019 (n = 335) were comparable. The percentage of abnormal FDG-PET/CT findings, suspicious for interstitial pneumonia by Covid-19 infection, was significantly higher during the pandemic (9%) compared with that found in the corresponding period of 2019 (4%) (χ2 5.45, P = 0.02). No significant differences were observed in the distribution of Covid-19 reporting and data system (CO-RADS) classification and in the maximum standardized uptake value between the pandemic (2.6 ± 2.2) and the corresponding period of 2019 (3.2 ± 1.4). Of note, patients with abnormal imaging findings during the pandemic time had clinical data and/or laboratory tests negative for Covid-19 infection. Conclusion Despite the restrictive medical measures for the emergency, the number of FDG-PET/CT studies was unchanged during the pandemic compared with the previous year. Our findings also indicate that Covid-19 infection was contained in our series of patients from southern Italy.

We aimed to determine at what size melanoma metastases become detectable by PET/CT. We reviewed a total of 293 whole-body PET/CT studies performed on 212 patients for staging of melanoma where there was an MRI within a month of the PET/CT. MR and PET/CT were reviewed independently by separate readers. PET/CT revealed an overall incidental true-positive rate of 1% on a per-patient basis, consistent with other studies, with ‘hot’ lesions (more avid than brain parenchyma) visible at smaller sizes than ‘cold’ lesions. PET/CT can detect metastatic melanoma lesions over about 2 cm in size, with hot lesions generally visible at smaller sizes.

Purpose The risk of malpositioning of the syndesmotic screws is very high. A lack of standard radiological or physical references for accurate syndesmotic screw placement is a potential contributing factor in syndesmotic screw malpositioning. Malleolar tips are clinically as well as radiologically appreciable bony references. The purpose of this preliminary CT based study was to investigate the axial relations of the central syndesmotic axis with the malleolar tips. Methods CT based studies of uninjured adult ankle joints with intact syndesmosis, conducted over a six months period were analysed. The axial differences between the coronal plane along the malleolar tips and that along the central syndesmotic axis in the axial plane were measured. Gender-based variations were also analyzed. Results A total of 70 CT studies were analyzed, and the axial difference between the malleolar tips based coronal plane and that along the central syndesmotic axis was observed to be 3.70 ± 5.61°. The male and female measurements were comparable. Conclusion Being in a static relation to the syndesmosis independent of the foot position and the limb rotation, the malleolar tips can be reliably used as references for directing syndesmotic screw in the axial plane. A knowledge of this axial difference between malleolar tips and central syndesmotic axis can help surgeons in an accurate syndesmotic screw placement.

Purpose To compare tumor motion amplitudes measured with 2D fluoroscopic images (FI) and with an inhale/exhale CT (IECT) technique Materials and methods Tumor motion of 52 patients (39 lung patients and 13 liver patients) was obtained with both FI and IECT. For FI, tumor detection and tracking was performed by means of a software developed by the authors. Motion amplitude and, thus, internal target volume (ITV), were defined to cover the positions where the tumor spends 95% of the time. The algorithm was validated against two different respiratory motion phantoms. Motion amplitude in IECT was defined as the difference in the position of the centroid of the gross tumor volume in the image sets of both treatments. Results Important differences exist when defining ITVs with FI and IECT. Overall, differences larger than 5 mm were obtained for 49%, 31%, and 9.6% of the patients in Superior‐Inferior (SI), Anterior‐Posterior (AP), and Lateral (LAT) directions, respectively. For tumor location, larger differences were found for tumors in the liver (73.6% SI, 27.3% AP, and 6.7% in LAT had differences larger than 5 mm), while tumors in the upper lobe benefitted less using FI (differences larger than 5 mm were only present in 27.6% (SI), 36.7% (AP), and 0% (LAT) of the patients). Conclusions Use of FI with the linac built‐in CBCT system is feasible for ITV definition. Large differences between motion amplitudes detected with FI and IECT methods were found. The method presented in this work based on FI could represent an improvement in ITV definition compared to the method based on IECT due to FI permits tumor motion acquisition in a more realistic situation than IECT.

Introduction: Adequate suppression of physiologic myocardial glucose uptake is important to ensure the interpretability and diagnostic reliability of [18F]fluorodeoxyglucose (FDG) PET/CT studies performed in the context of cardiac inflammation and infection. This study describes our experience with 4 preparatory protocols used in our institution. Methods: FDG PET/CT scans were performed according to 4 preparatory protocols (716 scans total), i.e. 6-h fast (group 1), low-carbohydrate diet plus 12-h fast (group 2), low-carbohydrate diet plus 12-h fast plus intravenous heparin pre-administration (15 IU/kg) (group 3), and low-carbohydrate diet plus 12-h fast plus intravenous heparin pre-administration (50 IU/kg) (group 4). Consecutive scans were retrospectively included from time frames during which the particular protocol was used. FDG uptake in normal myocardium was scored on a scale ranging from 0 (uptake less than that in the left ventricular blood pool) to 4 (diffuse uptake greater than that in the liver). Complete suppression was defined as uptake less than or equal to the blood pool (scores 0–1). Results: Complete suppression was accomplished in 27% in group 1, 68% in group 2, 69% in group 3 and 81% in group 4. Complete suppression was significantly lower in group 1 compared with all other groups (P < 0.0001 for all comparisons) and significantly higher in group 4 compared with group 2 (P = 0.005) and group 3 (P = 0.007). Groups 2 and 3 did not differ significantly (P = 0.92). Conclusion: A total of 50 IU/kg single-dose heparin administration before FDG PET/CT in addition to a low-carbohydrate diet and prolonged fast significantly outperformed protocols with no or lower dose (15 IU/kg) heparin in completely suppressing myocardial glucose metabolism.

Mimo ograniczeń techniki pozytonowej tomografii emisyjnej/tomografii komputerowej z użyciem radiofarmaceutyku 18F-Fluorodeoksyglukozy (18F-FDG PET/CT), wśród których wyróżniamy m.in. nieswoisty charakter radiofarmaceutyku 18F-FDG oraz niewielką dostępność, czy w końcu - wysokie koszty badania, liczni autorzy wskazują badanie 18F-FDG PET/CT jako najbardziej użyteczną metodę w procesie wykrywania, oceny stopnia zaawansowania i planowania leczenia nowotworu złośliwego przełyku.

Purpose To evaluate the correlation between trochlear dysplasia and acetabular coverage. Materials and methods 109 retrospective CT studies referred from the young adult knee clinic were independently reviewed by two observers. Anterior acetabular (AASA) and posterior acetabular (PASA) sector angles were calculated bilaterally on axial CT. Trochlear dysplasia was graded using the Dejour classification (A-D). ANOVA test was used. Results Dejour types A, B and D trochlear dysplasia were associated with a significantly increased AASA (P value = 0.0011). Conclusion Our results demonstrate a significant relationship between trochlear dysplasia and anterior acetabular coverage, as measured by AASA.

Background Low tube potential-high tube current computed tomography (CT) imaging allows reduction in iodine-based contrast dose and may extend the benefit of routine contrast-enhanced CT exams to patients at risk of nephrotoxicity. Purpose To determine the ability of an iodine contrast reduction algorithm to maintain diagnostic image quality for contrast-enhanced abdominal CT. Material and Methods CT exams with iodine contrast reduction were prescribed for patients at risk for renal dysfunction. The iodine contrast reduction algorithm combines weight-based contrast volume reduction with patient width-based low tube potential selection and bolus-tracking. Control exams with routine iodine dose were selected based on weight, width, and scan protocol. Three radiologists evaluated image quality and diagnostic confidence using a 4-point scale (Results Forty-six contrast reduction algorithm and control exams were compared (mean creatinine 1.6 vs. 1.2 mg/dL, P ≤ 0.0001). Thirty-nine contrast reduction patients had an eGFR 2 and 15 had single or transplanted kidney. Mean iodine contrast dose was lower in the contrast reduction group (20.9 vs. 39.4 g/mL, P < 0.0001). Diagnostic confidence was rated as acceptable in 95% (131/138) of contrast reduction and 100% of control exams (1.18–1.28 vs. 1.02–1.13, respectively; P > 0.06). Liver attenuation and contrast-to-noise ratio (CNR) were similar ( P = 0.08), but portal vein attenuation and CNR were lower with contrast-reduction (mean 176 vs. 198 HU, P = 0.02; 13 vs. 16, P = 0.0002). Conclusion This size-based contrast reduction algorithm using low kV and bolus tracking reduced iodine contrast dose by 50%, while achieving acceptable image quality in 95% of exams.

Pseudolipomas of Glisson's capsule are rare benign subcapsular liver lesions that typically affect older men. They are composed of degenerating fat that is thought to originate from a detached epiploic appendage. On Computed Tomographic (CT) imaging, pseudolipomas of Glisson's capsule are well-circumscribed and hypoattenuating compared to the hepatic parenchyma. This case report examines three consecutive CT studies in the same patient that show the pseudolipoma migrating to a hepatic subcapsular location over a period of 4.5 months. To our knowledge, this is the first documented case of a pseudolipoma migrating over time and it supports the hypothesis of a migrating epiploic appendage forming a pseudolipoma of Glisson's capsule. A comprehensive review of relevant literature and a discussion of the presented case are provided.

The total volume of Epicardial Adipose Tissue (EAT) is a well-known independent early marker of coronary heart disease. Though several deep learning methods were proposed for CT-based EAT volume estimation with promising results recently, automatic EAT quantification on screening Low-Dose CT (LDCT) has not been studied. We first systematically investigate a deep-learning-based approach for EAT quantification on challenging noisy LDCT images using a large dataset consisting of 493 LDCT and 154 CT studies from 569 subjects. Our results demonstrate that (1) 3D U-net precisely segment the pericardium interior region (Dice score \(0.95\pm 0.00\)); (2) postprocessing based on narrow 1-mm Gaussian filter does not require adjustments of EAT Hounsfield interval and leads to accurate estimation of EAT volume (Pearson’s R \(0.96\, {\pm }\, 0.01\)) comparing to CT-based manual EAT assessment for the same subjects.

Dynamic contrast CT with Patlak plot analysis can be used to determine the glomerular filtration rate (GFR). However, several studies have shown different GFR values and they are most likely less than the values by the standard techniques. The purpose of this prospective, experimental, and method comparison study was to evaluate the GFR using a CT technique (CT-GFR) in 12 healthy dogs compared to serum iohexol clearance (SIC-GFR). All dogs were anesthetized and placed in the right lateral recumbency position and the caudal part was lifted inside the CT gantry. A single-slice dynamic CT of the aorta and both kidneys was scanned sequentially every 2 s for 2 min after a bolus injection (3 mL/s) of iohexol (300 mg/kg). Time attenuation curves (TAC) were constructed and the GFR per volume of kidney was calculated using the Patlak plot analysis method based on 30-120 s time intervals, and results were compared to global GFR from SIC that was determined with eight blood samples for up to 240 min. The CT-GFR value (1.85 ± 0.48 mL/min/kg) was significantly less than the SIC-GFR value (3.40 ± 0.80 mL/min/kg; P

Background: The anterior atlantodental interval (AADI) and posterior atlantodental interval (PADI) on X-ray and computed tomography (CT) studies can both be used to gauge the risk and/or presence of neurological compression. Methods: This retrospective observational study was conducted at a tertiary care center in 116 patients with head injuries additionally warranting routine cervical X-ray and CT examinations. Results: The AADI averaged 1.36 ± 0.45 mm (X-ray) and 1.393 ± 0.47 mm (CT), while the mean PADI was 18.04 ± 2.44 mm (X-ray), and 18.07 ± 2.43 mm (CT). Notably, 93.96% of the total subjects had AADI below 2 mm. Further, 6.8% of patients with PADI =/ Conclusion: No significant differences were observed for X-ray versus CT studies, measuring AADI and PADI. Therefore, X-rays should continue to prove reliable for assessing craniovertebral junction anatomy in emergency settings. Of interest, the normal upper limit of AADI on sagittal CT reconstructions should now be changed to 2 mm from the previously accepted upper limit of 3 mm.

Objective: An arteriovenous graft (AVG) is indicated in hemodialysis patients with failed arteriovenous access. Early treatment of AVG infection is important because an advanced prosthetic infection leads to the removal of the prosthesis. The aim of this study was to evaluate the benefits of 18F-FDG PET/CT and 99mTc-HMPAO-WBC SPECT/CT in early detection of AVG infections. Subjects and Methods: Fifty-one AVGs were evaluated. 18F-FDG PET/CT and 99mTc-HMPAO-WBC SPECT/CT studies were performed at intervals of 10, 20-30, and 40-50 weeks after AVG insertion. Agreement between the imaging methods and reference parameters (i.e. clinical presentation, C-reactive protein and microbiological findings on the hemodialysis cannula extracted after hemodialysis from AVG) was evaluated. Results: The study results showed that focal accumulation of the radiopharmaceuticals can be considered a sign of AVG infection. At 10 weeks after AVG implantation, the focal 18F-FDG findings showed the best agreement with the reference parameters (agreement coefficients AC1 - clinical status: 0.693, CRP: 0.605, cannula microbiology: 0.518, respectively). At 20 to 30 weeks after AVG implantation, the diagnostic value of focal 99mTc-HMPAO-WBC accumulation increased (AC1 coefficients: 0.658, 0.658, 0.408) and was similar to that of focal 18F-FDG uptake (AC1s: 0.656, 0.570, 0.409). Between 40 and 50 weeks since AVG implantation, the diagnostic significance of focal 99mTc-HMPAO-WBC accumulation (AC1 coefficients: 0.771, 0.811, 0.611) slightly exceeded the diagnostic value of focal 18F-FDG accumulation (AC1 coefficients: 0.524, 0.456, 0.569). Conclusion: 18F-FDG PET/CT and 99mTc-HMPAO-WBC SPECT/CT can both serve as important tools contributing to early diagnosis of AVG infection.

OBJECTIVE. This study aims to compare the diagnostic accuracy of virtual unenhanced CT images derived from dual-source dual-energy contrast-enhanced CT with that of standard unenhanced CT images for evaluation of sialolithiasis. MATERIALS AND METHODS. All dual-energy CT studies of the neck performed during the preceding 5 years were reviewed for submandibular gland calculi. Only patients who had unenhanced CT and contrast-enhanced CT performed as part of the same evaluation were included in this study. This review yielded 30 patients. Virtual unenhanced CT images were derived from the dual-energy dataset and compared with the true unenhanced CT images by two separate radiologists who assessed the total number of calculi encountered, their location, the largest dimension, and the attenuation of the calculi. The radiation burden incurred for true unenhanced CT and virtual unenhanced CT and the total radiation burden were calculated. RESULTS. Our analysis revealed that measurements of stone size showed good interobserver agreement. The mean stone size was 7.9 ± 5.9 (SD) mm on virtual unenhanced CT and 8.4 ± 5.9 mm on true unenhanced CT (range, 2.0-31.8 mm); the difference was statistically insignificant. The mean stone attenuation differed considerably (p < 0.01) between the virtual and true unenhanced CT images (494.8 ± 187.5 HU and 924.4 ± 374.9 HU, respectively), but correlated well. The mean radiation dose for a dual-phase IV contrast-enhanced CT study was 23.13 mGy (volume CT dose index). The mean dose was 10.93 mGy for the true unenhanced CT phase, thereby suggesting a 47.25% reduction in administered radiation dose when a single-phase contrast-enhanced CT study with virtual unenhanced image reconstructions is performed. CONCLUSION. Virtual unenhanced CT images derived from dual-source dual-energy CT scans of the neck provide accurate assessment of sialolithiasis akin to that provided by conventional CT protocols but at only a fraction of the radiation dosage.

Fusulinids are larger benthic foraminifera of late Paleozoic and index fossils for Permo-Carboniferous strata. The traditional methods to examine their internal structures are through ground thin sections, which however caused lots of ambiguities regarding the morphological diagnostics and taxonomic identification. In recent years, new technique of high resolution X-ray computed tomography sheds light on the microfossil examination and we had fusulinid individuals successfully processed with this innovative approach. Here we present the results of 19 Pseudofusulina specimens, including high resolution images and rendered three-dimensional (3D) visuals of the important internal structures, to unwrap more details of fusulinid morphology. This is the first time the full 3D visuals of fusulinid interiors were constructed and exhibited. Previous understandings on fusulinid basic morphology, such as proloculus, chamber development, are precisely described with 3D illustration; cuniculi and phrenotheca are discovered regularly among the specimens and therefore are not suggested to be diagnostic features of taxonomic splitting; test and proloculus morphology divergences caused by section orientation are captured. With assistance of high resolution CT technique, fusulinid morphology, especially internal structures, is much easier to acquire, understand, and exhibit, despite the critical limitation that only the fusulinid samples buried with terrigenous clasts, such as those from calcareous mudstone or argillaceous limestone, could be successfully scanned.

Background Chronic subdural hematoma (CSH) is still an important neurosurgical problem and the number of patients increases despite the progress in early diagnosis of cerebral lesions. Methodology We analyzed a group of 700 consecutive patients treated in neurosurgical departments for CSH. Clinical state on admission was evaluated according to the Markwalder scale, all patients had CT studies and were operated using craniotomy or burr holes with closed system drainage techniques. Results More than 50% had extensive intracranial bleeding, almost half of the patients were treated with oral anticoagulants. The patients with extensive fresh bleeding were in significantly worse states on admission and were treated by craniotomy and external capsulectomy (42%). All the others had burr holes and closed system drainage of the subdural space. Results of treatment were acceptable, 2% died, and 1.5% remained vegetative, due to massive hemorrhage and severe neurological deficits on admission. Conclusions Despite a progress in diagnosis, CSH still remains an often cause of severe intracranial complications. The rising number of occurrences of this lesion is strictly connected with a wide use of oral anticoagulants. Surgical removal of CSH still remains the best type of treatment for such lesions.

PURPOSE The objective of this study was to evaluate the accuracy of using CT attenuation and SUVs to differentiate enostoses from untreated and treated osteoblastic metastases on the attenuation-correction CT component of F-FDG PET/CTs. METHODS We retrospectively reviewed F-FDG PET/CT studies of 117 patients (169 lesions), of which 65 had imaging of enostoses, and 52 had imaging showing the transition of lesions from untreated to treated osteoblastic metastases. We measured the mean CT attenuations and the SUVmax and SUVmean of each lesion. Receiver operating characteristic curve analyses were used to evaluate the accuracy of each metric in distinguishing enostoses from untreated and treated osteoblastic metastases. RESULTS For differentiating enostoses from untreated osteoblastic metastases, mean CT attenuation achieved an area under the receiver operating characteristic curve (AUC) of 90.8%, with an optimized threshold of 795 HU. SUVmax achieved an AUC of 94.9%, with an optimized threshold of 2.2. For differentiating enostoses from treated osteoblastic metastases, the AUCs for every metric decreased, with mean CT attenuation being the best at 82.7%. A joint predictive model combining both CT attenuation and SUV increased the AUC to 88.3%, and performance was significantly better than SUVmax or SUVmean alone (P = 0.029 and P = 0.049, respectively). CONCLUSIONS CT attenuation and SUV can reliably distinguish between enostoses and metastases on F-FDG PET/CT. However, the accuracy of these metrics decreases when used to differentiate enostoses from treated metastases. A joint prediction model combining CT attenuation with SUV can improve accuracy.