Non-contrast Studies Research Articles

Review/Perspective: Incidence and treatment of CSF leaks/dural tears (DT) occurring during anterior cervical surgery

Background: The incidence of cerebrospinal fluid (CSF) leaks/dural tears (DT) occurring during anterior cervical diskectomy and fusion (ACDF) are typically relatively low. However, this frequency markedly increases when anterior corpectomy and fusion (ACF) are performed to address ossification of the posterior longitudinal ligament (OPLL). Methods: The reported frequencies of CSF leaks/DT occurring during elective ACDF (i.e. exclusive of trauma), ranges from 0.24% to 1.7%. Notably, this incidence substantially rises for multilevel ACF addressing anterior OPLL, markedly varying from 3.4 - 44.7%. Results: The classical risks of anterior cervical CSF leaks/DT with anterior cervical surgery may be minimized utilizing an operating microscope. For OPLL, careful evaluation of preoperative non-contrast CT studies is critical, especially to document whether any of the 3 signs of dural penetrance is present. Here, posterior operative choices should be strongly considered in the presence of sufficient lordosis and/or a Positive K Line (+ K Line) as this will avoid an anterior cervical CSF leak/dural fistula. Alternatively, for patients with kyphosis and a Negative K Line (- K Line), preoperative anticipation and planning to treat an intraoperative anterior CSF leak/DT (i.e. direct anterior primary dural graft repair with 7-0 Gore-Tex sutures, microdural staples, microfibrillar collagen, wound-peritoneal shunt, and lumbar drain or lumboperitneal shunt) are essential in the course of performing direct anterior OPLL resection. Conclusion: The incidence of anterior cervical CSF leaks/DT is relatively low (i.e. range 0.24 - 1.7%) where ACDF is performed for disc disease/spur/spondylosis exclusive of OPLL. However, where ACF is performed for multilevel OPLL, the risk of CSF Leaks/DT is substantially higher (i.e. range 4.3-44.7%).

Left atrial volume in obesity and hypertension: an innovative "ideal human" index allows for weighing their impact - a non-contrast cardiac CT study

Abstract Left atrial (LA) enlargement is a common and early feature of cardiac involvement in the natural history of obesity and arterial hypertension (AH). Mechanisms involved in this process are cumulative, and partly shared, thus separating and balancing their contributions is challenging. In a proportion of patients referred for coronary artery calcium (CAC) scoring, these clinical entities are present. The LA volume (LAV) is relatively easy to quantify from a CT scan. Measured LAV values can be misleading unless constitutional parameters (height (h) or body size area (BSA), are considered. We introduced a new indexing parameter, consisting of height and the difference between numerical values of height and BSA. In the "ideal human", the difference is zero. Any deviation from this value determines the share of body mass regardless of height. Aim We hypothesize that a novel indexation approach allows for earlier detection of the increased LAV in normotensive and AH patients considering the body mass index. Method We retrospectively analyzed CT data from 2535 patients, 1658 w (64±10 ys), and 876 m (aged 6±11ys), with CAC scoring over the last 15 years The LAV was determined by using commercially available software. The raw and indexed (for h, BSA, and the novel parameter [h+ (h-BSA)]) LAV volumes were compared in patients with normal BMI (<25kg/msg), overweight (25-29.9), and obesity (≥30) who with normal blood pressure or with AH. Results The LAV was larger in high BMI categories than in normal BMI. In non-AH subjects, the LAV increased from an average of 71 ml (normal) to 80 ml (overweight) and 90 ml (obese). In AH, the LAV increase showed a similar trend of averages (77, 88, 94 ml, F=2.59,p<0.01). Indexing LAVs were non-concordant, as shown in Figure. Thus, one can recognize that LAV normalization for the new index has brought the differences most evident and persuasive. In normal BMI, indexation ways did not significantly affect the LAV estimation. Whilst the body weight increased, no difference could be recognized for values indexing for BSA (red). The LAV indexation for height (blue) cannot help diagnose its increase in obesity. The distinguishing strength can be seen while using the [h-(h-BSA)] denominator (green). It indicates that in any scenario, body mass gain plays a greater role in the LAV increase than AH does. Conclusions Body mass is a more important factor that is associated with LAV than AH.. Common methods of LAV indexing, especially referred to as BSA, introduce errors leading to values mimicking normality in non-healthy people and should be forbidden. The proposed indexation way can help overcome the observed discrepancies and support early recognition of the consequences of obesity and hypertension.

Altered cerebral oxygen extraction and metabolism in preterm neonates and the relationship to anemia: A noncontrast MRI study

AbstractObjectiveThe preterm brain is susceptible to structural injuries, which may be related to an imbalance between blood supply and oxygen metabolism. However, the effect of preterm birth on cerebral oxygen metabolism and its underlying mechanism have not been fully elucidated. The present study measured cerebral oxygen extraction and metabolism using noncontrast magnetic resonance imaging (MRI) methods in preterm neonates and examined its relationship with anemia of prematurity.MethodsFifty neonates with a gestational age of 28–42 weeks were enrolled. Cerebral oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) were measured with T2‐relaxation‐under‐spin‐tagging (TRUST) MRI, together with cerebral blood flow (CBF).ResultsWe showed that CBF (p = 0.00021) and CMRO2 (p < 0.0001) increased with gestational age while OEF increased with postnatal age (p = 0.0013). Higher OEF was also associated with a higher Apgar score at birth (p = 0.039). Furthermore, hematocrit significantly mediates the increase of OEF with postnatal age (p < 0.001). Structural equation modeling analysis suggested a bidirectional relationship between CBF and CMRO2; both contributed to the changes in OEF.InterpretationThese findings demonstrated an altered cerebral oxygen metabolism in preterm brain, suggesting a potential role of MRI–based oxygenation measurement in the assessment of transfusion and intervention for preterm neonates.

Establishing Local Diagnostic Reference Levels for Head Computed Tomography Examinations

Background/Objectives: Head Computed Tomography (CT) is an essential diagnostic tool for identifying brain pathologies and visualizing blood vessels. However, CT exposes patients to ionizing radiation, making it necessary to establish local diagnostic reference levels (DRLs) to ensure patient safety. This study aimed to establish DRLs for head CT scans and assess the influence of patient characteristics on radiation dose. Methods: A retrospective analysis was conducted on 2043 non-contrast and 488 contrast-enhanced head CT scans performed between 1 July 2023 and 31 March 2024 using a SIEMENS SOMATOM Definition Edge machine. Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP) values were analyzed, with DRLs set at the 75th percentile. The influence of gender, height, and weight on radiation dose was also evaluated. Results: The DRL for both non-contrast and contrast-enhanced scans was 58.18 mGy for CTDIvol and 1018.11 mGy·cm for DLP per acquisition. Total DLP was 2046.09 mGy·cm for contrast-enhanced and 1027.99 mGy·cm for non-contrast scans. No significant correlation was found between patient characteristics and radiation dose, allowing for a uniform DRL to be established. Conclusions: Uniform DRLs were successfully established for head CT scans, ensuring safe radiation doses for both non-contrast and contrast-enhanced studies. The lack of correlation between patient-specific factors and dose supports the use of standardized DRLs, contributing to optimized radiation safety in head CT diagnostics.

Efficacy of Non-Contrast MRI Studies in Characterization of Adnexal Masses Compared to Contrast Studies

Efficacy of Non-Contrast MRI Studies in Characterization of Adnexal Masses Compared to Contrast Studies

Clinical application of convolutional neural network lung nodule detection software: An Australian quaternary hospital experience.

Early-stage lung cancer diagnosis through detection of nodules on computed tomography (CT) remains integral to patient survivorship, promoting national screening programmes and diagnostic tools using artificial intelligence (AI) convolutional neural networks (CNN); the software of AI-Rad Companion™ (AIRC), capable of self-optimising feature recognition. This study aims to demonstrate the practical value of AI-based lung nodule detection in a clinical setting; a limited body of research. One hundred and eighty-three non-contrast CT chest studies from a single centre were assessed for AIRC software analysis. Prospectively collected data from AIRC detection and characterisation of lung nodules (size: ≥3 mm) were assessed against the reference standard; reported findings of a blinded consultant radiologist. One hundred and sixty-seven CT chest studies were included; 52% indicated for nodule or lung cancer surveillance. Of 289 lung nodules, 219 (75.8%) nodules (mean size: 10.1 mm) were detected by both modalities, 28 (9.7%) were detected by AIRC alone and 42 (14.5%) by radiologist alone. Solid nodules missed by AIRC were larger than those missed by radiologist (11.5 mm vs 4.7 mm, P < 0.001). AIRC software sensitivity was 87.3%, with significant false positive and negative rates demonstrating 12.5% specificity (PPV 0.6, NPV 0.4). In a population of high nodule prevalence, AIRC lung nodule detection software demonstrates sensitivity comparable to that of consultant radiologist. The clinical significance of larger sized nodules missed by AIRC software presents a barrier to current integration in practice. We consider this research highly relevant in providing focus for ongoing software development, potentiating the future success of AI-based tools within diagnostic radiology.

Non-contrast quantitative study of brain perfusion changes in multiple sclerosis

Non-contrast quantitative study of brain perfusion changes in multiple sclerosis

Comparison and Utility of Intravenous Iodinated Contrast in Chest, Abdomen, Pelvis Computerized Tomography for Trauma Patients With Blunt Mechanism of Injury Before and After the May 9, 2022 Global Contrast Shortage at a Level II Trauma Center.

Background: Intravenous (IV) contrast improves the sensitivity and specificity of injury detection in computerized tomography (CT). Its use is recommended in the workup of trauma patients by the American College of Surgeons and American College of Radiology. On May 9, 2022, the Food and Drug Administration declared a shortage of iodinated contrast due to the COVID-19 pandemic. Although the shortage has ended, the temporary lack of IV contrast forced physicians to be prudent in ordering CT scans with IV contrast. We sought to determine if there was a change in the percentage of CT contrast studies performed during the contrast shortage and if this change affected patient outcomes.Methods: Retrospective chart review was performed on all adult tier 2 trauma patients at a 619-bed community-based level II trauma center who received CT chest, abdomen, and pelvis imaging as initial workup for blunt trauma from 5/9/2021-6/30/2021 (pre-shortage) and 5/9/2022-6/30/2022 (during shortage).Results: Patients were predominantly male with median age of 31-52 and of White or Hispanic ethnicity. Before the contrast shortage, all 110 trauma patients were scanned with contrast. During the shortage, 29 of 114 patients were scanned with contrast (P < 0.001). Injuries were identified in 59% of patients scanned with contrast (P < 0.001). There were no significant differences in blood transfusion needs, repeat CT, disposition, or mortality when comparing pre-shortage to during shortage or when comparing between non-contrast and contrast studies during the shortage.Discussion: There was a decrease in the percentage of CT contrast studies performed during the shortage. A higher percentage of injuries were identified in the patients scanned with contrast. However, there were no significant differences in patient outcomes. Certain trauma patients may be safely scanned without contrast.

Development of learning-based online C-arm CT imaging technique for image-guided adaptive brachytherapy

Existing protocols for image-guided adaptive brachytherapy (BT) pose distinct limitations, which include: (1) the possible misalignment of the application position as a consequence of patient translocation between the treatment room and the computed tomography (CT)/magnetic resonance imaging (MRI) suite, (2) an inherent inability to continually monitor physiological and anatomical changes during the course of 3–10 fraction treatment regimens, and (3) insufficient tracing of the radioactive source movement within the patient's body. In response to these challenges, this study proposes an innovative deep-learning-based C-arm CT/SPECT imaging system tailored specifically for image-guided adaptive BT. This technological advancement aims to enable the execution of high-precision online adaptive BT, thereby amplifying the adaptability and effectiveness of oncological care. An image dataset of 66 non-contrast pelvic CT studies was acquired and limited-angle cone-beam CT (CBCT) images were generated by mathematically calculating sinograms for voxel phantoms based on these CT images. Using a Generative Adversarial Network (GAN), low-quality CBCT images obtained using a 110° limited-angle rotating C-arm system were transformed into high-quality diagnostic CT images. The performances of these networks were evaluated by comparing them with CBCT images reconstructed using an iterative reconstruction method and ground-truth images. Synthetic CT images were successfully transformed from low-quality CBCT images, considerably reducing streaking artifacts and preserving the anatomical structures. Our deep-learning-based image reconstruction technique could successfully improve the image quality of limited-angle CBCT, similar to the ground-truth image quality, with a faster speed than the latest iterative reconstruction algorithm. We expect that this will be effectively implemented in online image-guided adaptive BT and patient dose verification.

Random expert sampling for deep learning segmentation of acute ischemic stroke on non-contrast CT.

Outlining acutely infarcted tissue on non-contrast CT is a challenging task for which human inter-reader agreement is limited. We explored two different methods for training a supervised deep learning algorithm: one that used a segmentation defined by majority vote among experts and another that trained randomly on separate individual expert segmentations. The data set consisted of 260 non-contrast CT studies in 233 patients with acute ischemic stroke recruited from the multicenter DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3) trial. Additional external validation was performed using 33 patients with matched stroke onset times from the University Hospital Lausanne. A benchmark U-Net was trained on the reference annotations of three experienced neuroradiologists to segment ischemic brain tissue using majority vote and random expert sampling training schemes. The median of volume, overlap, and distance segmentation metrics were determined for agreement in lesion segmentations between (1) three experts, (2) the majority model and each expert, and (3) the random model and each expert. The two sided Wilcoxon signed rank test was used to compare performances (1) to 2) and (1) to (3). We further compared volumes with the 24 hour follow-up diffusion weighted imaging (DWI, final infarct core) and correlations with clinical outcome (modified Rankin Scale (mRS) at 90 days) with the Spearman method. The random model outperformed the inter-expert agreement ((1) to (2)) and the majority model ((1) to (3)) (dice 0.51±0.04 vs 0.36±0.05 (P<0.0001) vs 0.45±0.05 (P<0.0001)). The random model predicted volume correlated with clinical outcome (0.19, P<0.05), whereas the median expert volume and majority model volume did not. There was no significant difference when comparing the volume correlations between random model, median expert volume, and majority model to 24 hour follow-up DWI volume (P>0.05, n=51). The random model for ischemic injury delineation on non-contrast CT surpassed the inter-expert agreement ((1) to (2)) and the performance of the majority model ((1) to (3)). We showed that the random model volumetric measures of the model were consistent with 24 hour follow-up DWI.

Automatic Protocolling of Non-contrast Musculoskeletal MRIs Does Not Result in Increase in Patient Recall Rates for Contrast-Enhanced Studies

IntroductionPhysicians spend large amounts of time on protocolling imaging studies, limiting their time spent on other essential clinical tasks. Most musculoskeletal (MSK) MRI studies are performed for the evaluation of joint pain and internal derangements and usually require no intravenous contrast. Contrast-enhanced MRI studies are performed for the evaluation of infection, suspected or established tumor, and rheumatological conditions. Protocolling all MSK MRI studies takes time away from other important tasks during the workday. Routine joint MRI scans have established set of sequences, and thus, could be scheduled and performed without special protocols by the radiologists. In a large tertiary care center like ours with multiple MRI magnets, we set up a process of automated protocoling and scheduling of non-contrast joint MRI scans ordered by referring doctors. This project's purpose was to assess the effect of this newly established process of ‘automatic protocoling and scheduling’ of MSK MRI scans on the rate of overlooked MRI exams that may have required contrast examinations, and on the patient recall-rate to obtain follow up post-contrast sequences for further diagnostic characterization. MethodsAll musculoskeletal reports of MRIs during the last two months of the years before and after the implementation of automatic protocolling (intervention) were searched for the presence of indications related to neoplasms, infections, and rheumatological conditions. For each of the three disease categories, we determined the number of MRIs obtained with and without contrast before and after the intervention. For each matching study obtained without contrast, the patient chart was reviewed for contraindications to contrast, positive final diagnosis, whether interpreting radiologist mentioned the exam being limited by lack of contrast, and recommendations for a follow-up contrast enhanced study. ResultsA total of 846 musculoskeletal MRIs were performed prior to intervention and 822 MRIs were performed afterwards. Overall, 25% of the studies were performed without contrast prior to the intervention, and 31% of studies were performed without contrast afterwards (Chi square 0.07, p-value 0.79). No report contained a recommendation for contrast enhanced follow-up study before or after the intervention. DiscussionAutomatic protocolling of routine MSK non-contrast MRI studies resulted in statistically insignificant, minimal increase in the overall number of non-contrast enhanced studies obtained for work up of neoplasms, infections, and rheumatological conditions. There was no increase in patient recall rate for additional post contrast sequences and the new process resulted in time savings to fellows and other physicians, being not distracted from other important tasks.

Can Hounsfield units on chest CT characterize breast nodules as cystic or solid?

We report the results of our retrospective analysis of the ability of standard chest computed tomography (CT) scans to correctly differentiate cystic from solid lesions. MModal Catalyst identified 27 women who had an ultrasound of the breast that was recommended because of a chest CT finding between January 1, 2010, and December 31, 2017. All images were reviewed by a radiologist fellowship trained in both breast imaging and cardiothoracic radiology (MS). Ultrasound characterization of lesion density as cystic or solid was considered the gold standard for this study. Analysis of CT scans was performed to identify lesions of interest corresponding to ultrasound abnormality; average, minimum, and maximum Hounsfield units (HUs) were measured. If masses had any solid component, they were considered solid. Twenty masses were solid, and 7 masses were cystic on ultrasound. Thirteen studies were performed without contrast and 14 were performed with contrast. On non-contrast studies, the average HU for cystic lesions was 19 compared to 38 HU for solid (P=0.007). On contrast studies, the average HU for cystic lesions was 16 compared to 53 HU for solid (P=0.002). Cystic lesions did not change with contrast significantly. Solid lesions enhanced with contrast; average HU 38 without contrast to 53 HU with contrast. Chest CT accurately diagnosed breast masses as cystic or solid with or without contrast.

The impact of mechanical thrombectomy on the blood–brain barrier in patients with acute ischemic stroke: A non-contrast MR imaging study using DP-pCASL and NODDI

Background and purposeWhile mechanical thrombectomy (MT) achieves restoration of cerebral blood flow to the area at risk in patients with acute ischemic stroke (AIS), the influx of blood flow may exacerbate the blood–brain barrier (BBB) disruption and extravasation across the BBB, and it therefore remains unclear how reperfusion impacts the blood–brain barrier integrity. In this study, we use diffusion-prepared pseudocontinuous ASL (DP-pCASL) and Neurite Orientation Dispersion and Density Imaging (NODDI) sequence to measure the water exchange rate (kw) in patients who underwent either MT or medical management and determine its impact on the brain tissue microstructure in order to elucidate the impact of MT on BBB complex integrity. Materials and methodsWe prospectively enrolled 21 patients with AIS treated at our institution from 10/2021 to 6/2023 who underwent MR imaging at a 3.0-Tesla scanner. Patients underwent DP-pCASl and NODDI imaging in addition to the standard stroke protocol which generated cerebral blood flow (CBF), arterial transit time (ATT), water exchange rate (kw), orientation dispersion index (ODI), intracellular volume fraction (ICVF), and free water fraction (FWF) parametric maps. ResultsOf the 21 patients, 11 underwent MT and 10 were treated non-operatively. The average age and NIHSS for the MT cohort and non-MT cohorts were 69.3 ± 16.6 years old and 15.0 (12.0–20.0), and 70.2 ± 10.7 (p = 0.882) and 6.0 (3.8–9.0, p = 0.003) respectively. The average CBF, ATT, and kw in the infarcted territory of the MT cohort were 38.2 (18.4–59.6), 1347.6 (1182.5–1842.3), and 107.8 (79.2–140.1) respectively. The average CBF, ATT, and kw in the stroke ROI were 16.0 (8.8–36.6, p = 0.036), 1090.8 (937.1–1258.9, p = 0.013), 89.7 (68.0–122.7, p = 0.314) respectively. Linear regression analysis showed increasing CBF (p = 0.008) and undergoing mechanical thrombectomy (p = 0.048) were significant predictors of increased kw. ConclusionUsing our multimodal non-contrast MRI protocol, we demonstrate that increased CBF and mechanical thrombectomy increased kw, suggesting a better functioning BBB complex. Higher kw suggests less disruption of the BBB complex in the MT cohort.

Photon-counting detector CT allows significant reduction in radiation dose while maintaining image quality and noise on non-contrast chest CT

PurposeTo investigate if clinical non-contrast chest CT studies obtained with PCD CT using much lower radiation exposure can achieve the same image quality as with the currently established EID protocol. Materials/methodsA total of seventy-one patients were identified who had a non-contrast chest computed tomography (CT) done on PCD CT and EID CT scanners within a 4-month interval. Five fellowship trained chest radiologists, blinded to the scanner details were asked to review the cases side-by-side and record their preference for images from either the photon-counting-detector (PCD) CT or the energy-integrating detector (EID) CT scanner. ResultsThe median CTDIvol for PCD-CT system was 4.710 mGy and EID system was 7.80 mGy (p < 0.001). The median DLP with the PCD-CT was 182.0 mGy.cm and EID system was 262.60 mGy.cm (p < 0.001). The contrast to noise ratio (CNR) was superior on the PCD-CT system 59.2 compared to the EID-CT 53.3; (p < 0.001). Kappa-statistic showed that there was poor agreement between the readers over the image quality from the PCD and EID scanners (κ = 0.19; 95 % CI: 0.12 – 0.27; p < 0.001). Chi-square analysis revealed that 3 out of 5 readers showed a significant preference for images from the PCDCT (p ≤ 0.012). There was no significant difference in the preferences of two readers between EID-CT and PCD-CT images. ConclusionThe first clinical PCD-CT system allows a significant reduction in radiation exposure while maintaining image quality and image noise using a standardized non-contrast chest CT protocol.

Utility of Gadolinium-Based Contrast in Initial Evaluation of Seizures in Children Presenting Emergently.

The frequency and utility of gadolinium in evaluation of acute pediatric seizure presentation is not well known. The purpose of this study was to assess the utility of gadolinium-based contrast agents in MR imaging performed for the evaluation of acute pediatric seizure presentation. We identified consecutive pediatric patients with new-onset seizures from October 1, 2016, to September 30, 2021, who presented to the emergency department and/or were admitted to the inpatient unit and had an MR imaging of the brain for the evaluation of seizures. The clinical and imaging data were recorded, including the patient's age and sex, the use of IV gadolinium, and the underlying cause of epilepsy when available. A total of 1884 patients were identified for inclusion. Five hundred twenty-four (28%) patients had potential epileptogenic findings on brain MR imaging, while 1153 (61%) patients had studies with normal findings and 207 (11%) patients had nonspecific signal changes. Epileptogenic findings were subclassified as the following: neurodevelopmental lesions, 142 (27%); intracranial hemorrhage (traumatic or germinal matrix), 89 (17%); ischemic/hypoxic, 62 (12%); hippocampal sclerosis, 44 (8%); neoplastic, 38 (7%); immune/infectious, 20 (4%); phakomatoses, 19 (4%); vascular anomalies, 17 (3%); metabolic, 3 (<1%); and other, 90 (17%). Eight hundred seventy-four (46%) patients received IV gadolinium. Of those, only 48 (5%) cases were retrospectively deemed to have necessitated the use of IV gadolinium: Fifteen of 48 (31%) cases were subclassified as immune/infectious, while 33 (69%) were neoplastic. Of the 1010 patients with an initial noncontrast study, 15 (1.5%) required repeat MR imaging with IV contrast to further evaluate the findings. Gadolinium contrast is of limited additive benefit in the imaging of patients with an acute onset of pediatric seizures in most instances.

A Teleradiology System for Early Ischemic and Hemorrhagic Stroke Evaluation and Management

Abstract Purpose Stroke is a cardinal cause of death and disability globally. It is an emergency condition where the rapidity of diagnosis is directly linked to the outcome. “Imaging is Brain” is, therefore, an important concept. The early diagnosis of stroke is crucial not only in guiding its effective treatment but also in estimating prognosis. This study aims to provide perspective on the implementation of international teleradiology in stroke evaluation, management, and care. Methods A dedicated international teleradiology stroke network has been evaluated in our study between March 2019 and July 2022 where the interpretation and analysis of the computed tomography (CT) scans of the patients from distant hospitals in United States were performed by teleradiologists via high-quality Digital Imaging and Communications in Medicine (DICOM)-image transfer through a cloud-based radiology information system/picture archival and communication system platform RADspa. Results Over a period of three and a half years, starting from March 2019, a total of 30,406 CT scans of 19,342 patients from 96 hospitals of 15 states in the United States were interpreted and reported by board-certified radiologists empaneled by Teleradiology Solutions. The mean report turnaround time for all noncontrast CT studies was 9.97 minutes at 95% confidence interval (CI: 9.89–10.05); for CT angiogram studies, it was 20.57 minutes 95% CI (20.38–20.77); and for CT perfusion studies, it was 13.72 minutes 95% CI (13.42–14.03). Conclusion A dedicated international teleradiology stroke network designed in our study allowed for transmission, prioritization, evaluation, and management of CT cases performed in the setting of acute stroke in the study population. The results of our investigation indicate that teleradiology provides an effective solution for early diagnosis/interpretation of CT examinations performed internationally in the setting of acute stroke. This may further be used as a model or template for the development of a nationwide stroke network within our own country.

Correlation Between Renal Calculus Disease and Iliac Bone Thickness on a Single Non-contrast CT Scan.

Background Renal calculi remain a major economic and health burden worldwideand are considered a systemic disorder associated with multiple other diseases. Several studies have observed that patients with idiopathic calcium renal stonesshow areduction in bone mass. This study aimed to evaluate bone mass reduction on a non-contrast CT scan study in a group of idiopathic calcium-containing renal calculus disease patients in comparison with subjects without renal calculus disease. Methodology This non-interventional, cross-sectional study included a total of 300 patients with 150 cases (with renal calculi) and 150 controls (without renal calculi). Patients were divided according to age groups of 18-40, 40-60, and more than 60 years. The renal calculus size and the mean iliac bone thickness were calculated, and Spearman's correlation test was used to determine the correlation between them. Results The mean iliac bone thickness was significantly lower in the cases (3.29 mm) compared to the controls (9.73 mm with a standard deviation of 1.341 mm). There was a statistically significant negative correlation between the size of the renal calculus and the mean iliac bone thickness. Conclusions Renal calculus disease associated with hypercalciuria caused by increased bone resorption is reflected by the decreased iliac bone thickness on CT scans. Our study used the iliac bone (cancellous bone) in predicting bone mass reduction which shows changes early in the course of the disease compared to the neck of the femur and lumbar vertebrae (compact bones). It helps in predicting osteoporosis early and prevents the progression of the disease through early and appropriate clinical and urological intervention.

#5095 THE CURIOUS CASE OF GAS IN THE GRAFT KIDNEY

Abstract Background and Aims Emphysematous pyelonephritis (EPN) denotes a severe infection of renal parenchyma resulting in necrosis and gas accumulation in the renal and perirenal tissue. Risk factors for urinary tract infections in renal transplant recipients include advanced age, female gender, reflux nephropathy prior to transplantation, diabetes mellitus, deceased donor kidney, kidney–pancreas transplant, retransplantation, antibody induction for immunosuppression, urinary bladder catheterisation, history of allograft rejection with subsequent escalation of immunosuppressive therapy and use of ureteral stents. There are no definite guidelines for management of EPN in renal allografts. If unstable and deteriorating, graft nephrectomy should be undertaken as soon as possible. Any delay in surgical intervention, be it percutaneous drainage or nephrectomy may result in death. Method A 25-year old male, diagnosed with IgA Nephropathy (IgAN) received a living donor renal transplant from his mother in 2013 after a dialysis vintage of 3 years. He received Basiliximab induction followed by maintenance immunosuppression with Tacrolimus, Mycophenolate mofetil and Prednisolone. He had no history of UTI in the immediate post-transplant period. His blood glucose levels were within normal limits and he had not had any urological intervention. In 2019, patient was diagnosed with IgAN recurrence as a cause of chronic renal allograft injury. His Creatinine at last follow up in July 2022 was 4.1 mg/dL. He presented in September 2022 with fever, chills, vomiting, pain in the right iliac fossa and inability to extend his right leg. At presentation, his BP was 86/60mmHg, with pyrexia and tachycardia. Ultrasonography revealed an ill-defined collection superomedial to the graft kidney with doubtful posterior extension and air foci. Non-contrast CT study revealed a large subcapsular collection, extending posteriorly into the right iliac fossa involving the right psoas major and inferiorly into the pelvis, with air foci and no evidence of any urinary tract obstruction suggestive of Acute Emphysematous pyelonephritis with ruptured abscess. He was started on broad-spectrum iv antibiotics- Meropenem and Levofloxacin. Immunosuppression was reduced. Laboratory investigations revealed total leucocyte count of 37,000 cells/mm3, Creatinine of 11 mg/dL, urine routine microscopy revealed field full of pus cells. Blood and urine cultures grew ESBL Escherichia coli. He was taken up for urgent urological intervention in the form of percutaneous drain insertion. Frank pus was aspirated and 200mL drained instantaneously, cultures of which demonstrated the same organism. Within 24 hours of pus drainage, patient became afebrile and had pain relief. He was given 3 weeks of culture-appropriate iv antibiotics, to continue another 3 weeks of oral Carbapenem. However, his graft dysfunction persisted, with no recovery and he became dialysis-dependent. Discussion EPN of the renal allograft is a rare occurrence. A study of EPN in renal transplant recipients by Alexander et al from 2012 revealed 18 out of 22 patients were diabetics, 9 necessitated graft nephrectomy and 7 required percutaneous drainage in addition to antibiotics4. Till date, up to 30 cases of graft EPN have been reported in English literature. The striking feature is that more than 90% of these cases were diabetic. Conclusion The complete pathogenesis of renal allograft EPN, especially in patients with no apparent traditionally described risk factors remains yet to be understood. A high degree of suspicion and early intervention may help to save the allograft.

769 In Vivo Evaluation of Spinal Cord Perfusion Using Contrast-Enhanced Transcutaneous Ultrasound

INTRODUCTION: Ultrasound (US) imaging is cheap, portable, and widely available. It has been used in multiple medical disciplines, both as a means of diagnosis and therapy. Developing US as a platform for spinal cord perfusion monitoring in patients with spinal cord injury (SCI) would provide a cheap, accessible, and real-time platform for managing spinal cord perfusion in the acute setting. METHODS: Four patients with previous cervical decompression and instrumentation were evaluated at a single center with transcutaneous US. We included adult patients with at least 2 levels of continuous cervical laminectomies greater than 3 months prior to US and no history of SCI. The first two patients underwent US imaging without contrast and the second two patients underwent contrast-enhanced US imaging with Lumason, a microbubble agent. Imaging was performed by a board-certified radiologist with US expertise using a General Electric (GE) Logiq E10 ultrasound scanner ans a high frequency linear transducer. The study was approved by the institutional ethics committee. RESULTS: In the non-contrast study (n = 2), the dura, spinal cord, and vertebral body were apparent on US. Application of Doppler was insufficient to discern intramedullary perfusion, so contrast-enhanced ultrasound was pursued (n = 2). With contrast, anatomic structures were again visible, and we were able to quantify differential spinal cord perfusion within and between cross-sectional sections of the cord. We demonstrated spinal cord hemodynamic perfusion by measuring peak signal intensity and the time to peak signal intensity after microbubble contrast injection. Then, a time-intensity curve was created and the area under the curve was calculated as a surrogate of spinal cord perfusion. CONCLUSIONS: Contrast-enhanced US is a viable platform for monitoring spinal cord perfusion in patients who have undergone prior cervical laminectomies.

Opportunistic screening for low bone density using abdominopelvic computed tomography scans.

While low bone density is a major burden on US health system, current osteoporosis screening guidelines by the US Preventive Services Task Force are limited to women aged ≥65 and all postmenopausal women with certain risk factors. Even within recommended screening groups, actual screening rates are low (<26%) and vary across socioeconomic groups. The proposed model can opportunistically screen patients using abdominal CT studies for low bone density who may otherwise go undiagnosed. To develop an artificial intelligence (AI) model for opportunistic screening of low bone density using both contrast and non-contrast abdominopelvic computed tomography (CT) exams, for the purpose of referral to traditional bone health management, which typically begins with dual energy X-ray absorptiometry (DXA). We collected 6083 contrast-enhanced CT imaging exams paired with DXA exams within ±6 months documented between May 2015 and August 2021 in a single institution with four major healthcare practice regions. Our fusion AI pipeline receives the coronal and axial plane images of a contrast enhanced abdominopelvic CT exam and basic patient demographics (age, gender, body cross section lengths) to predict risk of low bone mass. The models were trained on lumbar spine T-scores from DXA exams and tested on multi-site imaging exams. The model was again tested in a prospective group (N=344) contrast-enhanced and non-contrast-enhanced studies. The models were evaluated on the same test set (1208 exams)-(1) Baseline model using demographic factors from electronic medical records (EMR) - 0.7 area under the curve of receiver operator characteristic (AUROC); Imaging based models: (2) axial view - 0.83 AUROC; (3) coronal view- 0.83 AUROC; (4) Fusion model-Imaging + demographic factors - 0.86 AUROC. The prospective test yielded one missed positive DXA case with a hip prosthesis among 23 positive contrast-enhanced CT exams and 0% false positive rate for non-contrast studies. Both positive cases among non-contrast enhanced CT exams were successfully detected. While only about 8% patients from prospective study received a DXA exam within 2 years, about 30% were detected with low bone mass by the fusion model, highlighting the need for opportunistic screening. The fusion model, which combines two planes of CT images and EMRs data, outperformed individual models and provided a high, robust diagnostic performance for opportunistic screening of low bone density using contrast and non-contrast CT exams. This model could potentially improve bone health risk assessment with no additional cost. The model's handling of metal implants is an ongoing effort.