Computed Tomography Contrast Research Articles

Comparison of bone subtraction CT angiography with standard CT angiography for evaluating circle of Willis in normal dogs.

Bone subtraction computed tomography angiography (BSCTA) is a useful alternative technique for improving visualization of vessels surrounded by skull bone. However, no studies have compared computed tomography angiography (CTA) and BSCTA for improving the visibility of canine cerebral blood vessels. To evaluate the potential benefit of BSCTA for better delineation of brain arteries of the circle of Willis (CoW) in dogs by comparing BSCTA with non-subtraction computed tomography angiography (NSCTA). Brain CTA was performed for nine healthy beagle dogs using a bolus tracking method with saline flushing. A total dose of 600 mgI/kg of contrast agent with an iodine content of 370 mgI/mL was injected at a rate of 4 ml/s. Bone removal was achieved automatically by subtracting non-enhanced computed tomography (CT) data from contrast CT data. Five main intracranial arteries of the CoW were analyzed and graded on a scale of five for qualitative evaluation. Scores of basilar artery, middle cerebral artery, and rostral cerebral artery in the BSCTA group were significantly higher than those in the NSCTA group (p = 0.001, p = 0.020, and p < 0.0001, respectively). Scores of rostral cerebellar artery (RcA) and caudal cerebral artery (CCA) did not differ significantly between the two groups. However, scores of RcA and CCA in the BSCTA group were higher than those in the NSCTA group. BSCTA improved visualization of intracranial arteries of the CoW with close contact to bone. Thus, it should be recommended as a routine scan method in dogs suspected of having brain vessel disease.

Nanomaterial-based CT contrast agents and their applications in image-guided therapy.

Computed tomography (CT), a diagnostic tool with clinical application, comprehensive coverage, and low cost, is used in hospitals worldwide. However, CT imaging fails to distinguish soft tissues from normal organs and tumors because their mass attenuation coefficients are similar. Various CT contrast agents have been developed in recent years to improve the sensitivity and contrast of imaging. Here, we review the progress of nanomaterial-based CT contrast agents and their applications in image-guided therapy. The CT contrast agents are classified according to their components; gold (Au)-based, bismuth (Bi)-based, lanthanide (Ln)-based, and transition metal (TM)-based nanomaterials are discussed. CT image-guided therapy of diseases, including photothermal therapy (PPT), photodynamic therapy (PDT), chemotherapy, radiotherapy (RT), gas therapy, sonodynamic therapy (SDT), immunotherapy, starvation therapy, gene therapy (GT), and microwave thermal therapy (MWTT), are reviewed. Finally, the perspectives on the CT contrast agents and their biomedical applications are discussed.

Recent advances in PAMAM dendrimer-based CT contrast agents for molecular imaging and theranostics of cancer

Recent advances and some key developments in the construction of PAMAM dendrimer-based nanoplatforms for tumor CT imaging and theranostics have been reviewed.

Clinical indication diagnostic reference level (DRLCI) and post-optimization image quality for Adult Computed Tomography Examinations in Enugu, south eastern Nigeria

This work established Clinical Diagnostic Reference levels (DRLci) for adult Computed Tomography (CT) examination and its application in the practice of medical imaging and Radiology. We also assessed post-optimization image quality as a panacea for dose optimization. The study was a prospective study conducted in five centres in Enugu, Nigeria with ethical certificate no NHREC/05/01/2008B-FWA00002485-1RB00002323. Dose values and technical parameters were obtained using International Commission on Radiological Protection (ICRP) Publication 135.Protocols were used as specified in Siemens machine for helical pre and post contrast CT examination. Scan parameters such as Field of view, pitch, rotation time, tube output, Kv, mAs and slice thickness were documented. Quality control checks were carried out on the machines. Adult patients from 18 years and above that presented to for CT investigation of the head, chest or abdomen from November 2018 to April 2021 were included in the study. A total of 2490 patients with distribution 1200 brain scans (48.2%), 420 chest scans (16.9%) and 870 abdominal scans (34.9%) were studied from the 5 participating centres (one public and four private CT centres). The distribution were as follows: Head - CVA (300), Trauma (300), Metastasis/abscess (300), Infection (180), Seizure (120). Chest - Lung disease (240), Lung cancer/mass (180). Abdomen/Pelvis - Abdominal cancer/metastasis (120), Abdominal mass (300), Liver disease (240), Urography (210). The adult patient's weight was 50 ± 10 kg. Objective image quality assessment was carried out via signal to noise ratio (SNR) analysis prior to data collection. Pearson correlation was used to compare the mean dose quantities, age and sex. Dose values for CT centres and between previous literatures were determined using student t-test at 0.05 level of significance. 476(39.7%) were females and 724(60.3%) were males. Out of the 420 patients that underwent the chest scan, 204(48.6%) were females and 216(51.4%) were males. For the Abdomen/Pelvis scan with 870 patients, 411(47.2%) were females and 459(52.8%) were males. For head CT, the CTDIvol for trauma, CVA, metastasis, infection and seizure are 43, 43, 43, 34 and 28 mGy respectively. Their corresponding DLP includes; 907, 879, 1689, 969, 995 mGy cm. In the chest, the CTDI for lung disease and mass are 13 and 13 mGy. Their corresponding DLP includes; 763 and 1531 mGy cm. In the abdomen, the CTDIvol for liver disease, malignancy, mass and urography are 16, 12, 16, and 15 mGy. Their corresponding DLP includes; 2723, 2011, 2011, 2047 mGy cm.The CTDIvol values in this study for head, chest and abdomen/pelvis region are below the European commission value (1999) with a p value of 0.024, 0.018, and 0.000 respectively All the images were accepted by the radiologist and has comparable signal to noise ratio (SNR) dose reduction from the optimization process. Almost all the centres have their dose value below the estimated DRL for Enugu and up to 50% dose reduction. Clinical indications DRL for 10 common clinical indications in CT examination were established. The study showed wide variations in patient dose between hospitals and even between identical scanners for different clinical indications. Clinical Indication DRLs developed for pre and post contrast studies are useful for dose optimization.

Immediate surgical treatment for massive extravasation of computed tomography contrast medium in the hand: a case report

There are no treatment guidelines for the extravasation of contrast medium. A 71-year-old man underwent coronary artery computed tomography. When contrast medium (iohexol) was injected through the right cephalic vein, massive leakage into the surrounding tissues occurred. A physical examination showed severe swelling of the hand and a prolonged capillary refill time. X-rays showed a massive accumulation of contrast medium in the hand. We immediately performed surgical treatment, including four skin incisions on the hand, subcutaneous dissection, and squeezing, which led to the removal of 50 mL of liquid. The immediate postoperative radiographic findings showed dramatic fading of most of the contrast medium. Four days postoperatively, radiography showed complete dissolution of all contrast medium, and a physical examination revealed full recovery of skin color and capillary refill time. We successfully managed massive extravasation of contrast medium in the hand with immediate surgical treatment. An immediate surgical approach for massive extravasation should be considered to achieve favorable outcomes.

Iohexol functionalized Si-Ag:Mn3O4 hybrid nanoparticles based contrast agent for computed tomography imaging

One of the most widely used methods for diagnosing diseases in human tissue is computed tomography (CT). Clinically, CT scans may require contrast media, such as Iohexol, to enhance images of different tissues and organs. However, these iodinized contrast agents have limitations, such as short blood duration, requirement of high-concentration injection, limited enhancement of specific tissues, nonspecific detection, and localization of the substance. Bimodal and multimodal imaging approaches have been used to develop iodinated contrast agents. In this study, silica-Ag:Mn 3 O 4 hybrid nanoparticles were synthesized and conjugated with a commercial iodine contrast agent (Iohexol). Absorption, morphology, and elemental analysis were investigated, followed by a preliminary study on CT contrast enhancement. Compared with Iohexol, the absorption intensity of Iohexol-conjugated nanoparticles (I@Si-Ag:Mn 3 O 4 ) drastically increased, although the loading capacity was estimated to be approximately 40%. The Hounsfield unit (HU) of the nanoparticles increased linearly with increasing mass concentration, exhibiting a stronger HU signal than Iohexol by at least 465 ∆HU at similar concentrations. The maximum CT enhancements were 1644 ± 14 HU for I@Si-Ag:Mn 3 O 4 and 665 ± 14 HU for Iohexol, confirming the CT contrast efficiency of I@Si-Ag:Mn 3 O 4 . These results suggest that the synergy between the nanoparticles and localized Iohexol on the surface-enhanced the performance of the contrast media.

Planning Head and Neck radiotherapy in contrast CT: viability for AAA and AcurosXB

Background and purpose: many radiotherapy services execute two computed tomography (CT) scans for the treatment of head and neck (H&amp;N) tumors: with (contrast CT) or without contrast (non-contrast CT), for dose calculation and target volume delineation, respectively. However, performing two CT scans brings problems such as unnecessary exposure of the patient to radiation and errors in CT images fusion. Therefore, the objective of this study was to verify the possibility of performing only the contrast CT as the routine for dose calculation with AAA and AcurosXB. Materials and methods: contrast and non-contrast CT scans from 77 patients were retrospectively analyzed and the Hounsfield Unit (HU) values ​​of the target volume and some organs at risk (as well as dosimetric values ​​were evaluated and compared. Statistical analysis was performed by calculating the intraclass correlation coefficient (ICC), assuming a significance level of 5%. Results: there is a correlation between the values ​​obtained for both HU and dosimetric data between the CT scans since the ICC was close to 1 and the p-value was lower than 0.05 for all cases. Conclusion: it is possible to perform only the contrast CT in the simulation routine for the treatment of patients with head and neck tumors. &#x0D; Keywords: Radiotherapy; Computed tomography; Contrast Agent; Dose Calculation; AAA; AcurosXB; VMAT; IMRT

Acute superior mesenteric arterial thromboembolic occlusion-catheter directed thrombolysis-be on time, still be cautious!

Acute mesenteric ischemia (AMI) is one of the major life-threatening emergencies which require immediate attention and treatment. The most common cause of AMI is superior mesenteric artery (SMA) occlusion secondary to an embolic phenomenon. We present a 55-year-old gentleman with acute SMA thromboembolism, treated by catheter directed thrombolysis (CDT) that helped in avoiding a major surgery. A 55-year-old male, with known diabetes, hypertension and atrial fibrillation, presented with acute abdominal pain and found to have SMA thromboembolism on contrast computed tomography (CT) abdomen. As there were no evidences of bowel ischemia clinically and on the CT imaging, endovascular CDT was performed following which the patient improved and discharged after 10 days of hospital stay. Timely endovascular intervention in appropriate patient population with acute mesenteric arterial thromboembolic occlusion can help avoid major surgeries, reduce the extent of non-viable bowel and decrease the resultant significant morbidity.

Contrast phase recognition in liver computer tomography using deep learning

Hepatocellular carcinoma (HCC) has become the 4th leading cause of cancer-related deaths, with high social, economical and health implications. Imaging techniques such as multiphase computed tomography (CT) have been successfully used for diagnosis of liver tumors such as HCC in a feasible and accurate way and its interpretation relies mainly on comparing the appearance of the lesions in the different contrast phases of the exam. Recently, some researchers have been dedicated to the development of tools based on machine learning (ML) algorithms, especially by deep learning techniques, to improve the diagnosis of liver lesions in imaging exams. However, the lack of standardization in the naming of the CT contrast phases in the DICOM metadata is a problem for real-life deployment of machine learning tools. Therefore, it is important to correctly identify the exam phase based only on the image and not on the exam metadata, which is unreliable. Motivated by this problem, we successfully created an annotation platform and implemented a convolutional neural network (CNN) to automatically identify the CT scan phases in the HCFMUSP database in the city of São Paulo, Brazil. We improved this algorithm with hyperparameter tuning and evaluated it with cross validation methods. Comparing its predictions with the radiologists annotation, it achieved an accuracy of 94.6%, 98% and 100% in the testing dataset for the slice, volume and exam evaluation, respectively.

Radiography, CT‐angiography and post‐mortem findings in a foal with a congenital type 3 vascular ring anomaly

SummaryCongenital vascular ring anomalies (VRA) have been occasionally described in horses. To the authors' knowledge, this is the first case report providing radiographic and computed tomography (CT) findings of a congenital type 3 persistent right aortic arch (PRAA) in a foal. A 1.5 months old Franches‐Montagnes colt was presented for growth retardation with a history of mild intermittent bilateral nasal discharge occasionally containing milk and coughing since birth. Thoracic radiographs and ultrasound, oesophagoscopy, positive contrast oesophagography and CT angiography were performed. A final diagnosis of persistent right fourth aortic arch, with left ligamentum arteriosum and aberrant left subclavian artery (type 3 VRA) and subsequent aspiration pneumonia was achieved. Due to the poor physical condition, the presence of severe aspiration pneumonia and most importantly the lack of a surgical option for a type 3 VRA, the colt was euthanised and the post‐mortem examination confirmed the oesophagography and CT angiography findings.

The Added Value of a High CT Coronary Artery Calcium Score in the Management of Patients Presenting with Acute Chest Pain vs. Stable Chest Pain.

Contrast computerized tomography (CT) scan is occasionally aborted due to a high coronary artery calcium score (CACS). For the same CACS in our clinical practice, we observed a higher occurrence of severe coronary artery disease (CAD) in patients with acute chest pain (ACP) compared to patients with stable chest pain (SCP). Since it is known that ACP differs in many ways from SCP, the aim of this study was to compare the predictive value of a high CACS for the diagnosis of severe CAD between ACP and SCP patients. This single center observational retrospective study included consecutive patients who underwent cardiac CT for chest pain and were found to have a CACS of &gt;200 Agatston units. Patients were divided into two groups, ACP and SCP. Severe CAD was defined as ≥70% stenosis on coronary CT angiography or invasive coronary angiography. Baseline characteristics and final diagnosis of severe CAD were compared. The cohort included 220 patients, 106 with ACP and 114 with SCP. ACP patients had higher severe CAD rates (60.4% vs. 36.8%; p &lt; 0.001). On multivariate analysis including cardiac risk factors, CACS &gt; 400 au (OR = 2.34 95% CI [1.32-4.15]; p = 0.004) and ACP (OR = 2.54 95% CI [1.45-4.45]; p = 0.001) were independent predictors of severe CAD. The addition of the clinical setting of ACP added significant incremental predictive value for severe stenosis. A high CACS is more associated with severe CAD in patients presenting with ACP than SCP. The findings suggest that the CACS could impact the management of patients during the scan.

A radiomics nomogram analysis based on CT images and clinical features for preoperative Lauren classification in gastric cancer.

To develop a combined radiomics nomogram based on computed tomography (CT) images and clinical features to preoperatively distinguish Lauren's diffuse-type gastric cancer (GC) from intestinal-type GC. Ninety-five patients with Lauren's intestinal or diffuse-type GC confirmed by postoperative pathology had their preoperative clinical information and dynamic contrast CT images retrospectively analyzed and were subdivided into training and test groups in a 7:3 ratio. To select the optimal features and construct the radiomic signatures, we extracted, filtered, and minimized the radiomic features from arterial phase (AP) and venous phase (VP) CT images. We constructed four models (clinical model, AP radiomics model, VP radiomics model, and radiomics-clinical model) to assess and compare their predictive performance between the intestinal- and diffuse-type GC. Receiver-operating characteristic (ROC) curve, area under the ROC curve (AUC), and the DeLong test were used for assessment and comparison. In this study, radiomic nomograms integrating combined radiomic signatures and clinical characteristics were developed. Compared to the AP radiomics model, the VP radiomics model had better performance, with an AUC of 0.832 (95% confidence interval [CI], 0.735, 0.929) in the training cohort and 0.760 (95% CI 0.580, 0.940) in the test cohort. Among the combined models that assessed Lauren's type GC, the model including age and VP radiomics showed the best performance, with an AUC of 0.849 (95% CI 0.758, 0.940) in the training cohort and 0.793 (95% CI 0.629, 0.957) in the test cohort. Nomogram incorporating radiomic signatures and clinical features effectively differentiated Lauren's diffuse-type from intestinal-type GC.

Application of CT contrast medium is not associated with an increased risk for acute kidney injury in patients with decompensated cirrhosis.

Acute kidney injury (AKI) is a frequent complication in patients with decompensated cirrhosis. Studies reported conflicting results regarding the nephrotoxic potential of iodinated contrast medium (CM) for computer tomography (CT). To investigate the impact of diagnostic CM application on kidney function in patients with decompensated cirrhosis. First, we evaluated the impact of diagnostic CM-CT on AKI incidence in a cross-sectional approach. Second, we analysed 28-day AKI incidence post-CM-CT in patients with impaired kidney function (i.e., creatinine >133 μmoL/L). Third, we excluded all patients with relevant interventions besides CM-CT. All remaining patients were matched via propensity score matching (PPSM) and further analysed. Last, we validated the results in an independent dataset of prospectively collected registry data of 118 patients with decompensated cirrhosis. Here, plasma samples were analysed regarding neutrophil-gelatinase-associated-lipocalin (NGAL). Of the 611 included patients, 98 (16%) received CM-CT. CM-CT was not associated with AKI in the cross-sectional approach (CM-CT:8% vs. no CM-CT:15%; p= 0.08). Furthermore, CM-CT was not associated with higher 28-day AKI incidence among patients with impaired kidney function (HR:0.79; 95% CI 0.45-1.38; p= 0.40). The PPSM cohort revealed no association between CM-CT and AKI or severe AKI (HR:1.28, p= 0.45 and HR:1.62; p= 0.43). Moreover, CM-CT did not result in worsening of kidney function after CM application. In the validation cohort, CM-CT was also not linked to AKI (p= 0.85) and NGAL levels were not increased in those with CM-CT (CM-CT:309 ng/ml vs. No CM-CT:266 ng/ml, p= 0.35). Decompensated cirrhosis per se should not preclude diagnostic CM-CT.

Bismuth nanomaterials as contrast agents for radiography and computed tomography imaging and their quality/safety considerations.

Contrast agents for radiography and computed tomography (CT) scans are substances that can enhance the contrast of blood vessels and soft tissue with detailed imaging information of the diseased sites. However, the large doses, short circulation time and adverse effects are the intrinsic limitations of CT contrast agents, preventing their extended and safe use in the clinical setting. Bismuth nanoparticles (NPs) have gained attention for the high X-ray absorption of bismuth elements with acceptable biocompatibility, showing their potential to be translated into commercialized CT contrast agents. Compared with traditional iodine contrast agents, bismuth NPs are characterized by prolonged circulation time and enhanced contrast, largely due to the surface modification and enhanced permeability and retention effect of NPs. Bismuth NPs can also be flexibly upgraded into sophisticated nanoagents for multimodal imaging and therapeutic purposes by complexation with supporting chemicals, small molecule drugs, fluorescence labels, and other functional agents. Additionally, the affinity and retention of the bismuth NPs in the diseased sites can be further improved by modification of the targeting moiety on the NPs surface. However, a simple synthetic process and low complexity of bismuth NPs are highly recommended for scaling out and quality control of nanoagents with commercialization potential. Since product safety is a prerequisite for the translation of bismuth NPs from bench to the clinic, we focus on recent advances in the distribution, elimination, and toxicity of bismuth NPs previously reported. Finally, we delineate the associated mechanisms for nephrotoxicity and the strategy to reduce the toxicity of bismuth NPs. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

A Mysterious Case of Abdominal Pain

A Mysterious Case of Abdominal Pain

A case of pathological complete response with liposomal irinotecan + 5-FU/LV for unresectable locally advanced pancreatic cancer

BackgroundPancreatic cancer has one of the worst prognoses of any all cancers. 5-FU/leucovorin + irinotecan + oxaliplatin (FOLFIRINOX), gemcitabine (GEM) plus nab-paclitaxel regimens have been recognized as global-standard, first-line treatments for patients with advanced pancreatic cancer. The liposomal irinotecan (nal-IRI) + 5-FU/LV regimen is now included in treatment guidelines as a recommended and approved option for use in patients with metastatic pancreatic cancer that has progressed after GEM-based therapy and who have a suitable performance status and comorbidity profile. There is no report that nal-IRI + 5-FU/LV regimen was significantly effective, and we will report it because we experienced this time.Case presentationA 69-year-old man presented with epigastric pain, and a contrast computed tomography (CT) revealed an enhanced mass lesion measuring 33 × 27 mm on the pancreatic body with encasement of the common hepatic artery (CHA) and the splenic vein. An endoscopic ultrasound-guided fine needle aspiration was performed and demonstrated cytology consistent with adenocarcinoma. Therefore, we diagnosed the patient with unresectable locally advanced pancreatic cancer. The patient received the GEM and S-1 regimen; however, the adverse event was relatively severe. Then, 11 cycles of nal-IRI + 5-FU/LV regimen were administered. A CT scan revealed that the tumor had shrunk to 18 × 7 mm in diameter with encasement of the CHA. The encasement of the splenic vein had disappeared, without any distant metastases. From this post-chemotherapy evaluation and intraoperative frozen section of around the celiac artery, gastroduodenal artery and pancreas stump confirmed absence of tumor cells, we performed distal pancreatectomy with celiac axis resection. A histological examination of the surgical specimen revealed no evidence of residual adenocarcinoma, consistent with a pathological complete response to treatment.ConclusionsWe present the first case of a pathological complete response with nal-IRI + 5-FU/LV for unresectable, locally advanced pancreatic cancer. In the future, nal-IRI may become a key drug for pancreatic cancer treatment.

Contrast Medium Use in Computed Tomography for Patients Presenting with Headache: 4-year Retrospective Two-Center Study in Central and Western Regions of Ghana.

Background Contrast medium (CM) administration during computed tomography (CT) enhances the accuracy in the detection and interpretation of abnormalities. Evidence from literature also validate the essence of CM in imaging studies. CT, by virtue of its ubiquity, ease of use, speed, and lower financial footprint, is usually the first investigation in cases of headache. Through a multicenter retrospective analysis, we compared findings of contrast-enhanced CT (CECT) to noncontrast-enhanced CT (NCECT) head examinations among patients presenting with headache. Methods A multicenter retrospective analysis of four years' CT head examination data at two radiology centers located in Central and Western Regions of Ghana were reviewed. Records of patients who presented with headache as principal complaint between January 2017 and December 2020 were reviewed. A total of 477 records of patients with headache were identified, retrieved and evaluated. A Chi-square test and Fisher exact test were used to compare the CECT and NCECT groups. Binary logistic regression analysis was computed to assess association between CECT and each CT findings. Statistical significance was considered at p < 0.05 with a 95% confidence interval. Results A significant proportion of the patients was females (51.8% in CECT and 60% in NCECT). The NCECT group (40.06 ± 14.76 years) was relatively older than the CECT group (38.43 ± 17.64 years). There was a significant difference between the CECT and NCECT in terms of age (p=0.002) and facility CT was performed (p < 0.0001). The rate of abnormalities was higher in CECT (43.5%, 166/382) compared NCECT (37.9%, 36/95). There was no significant association between CT head findings and contrast enhancement. Conclusion CECT examination accounted for 5.6% increase in the detection of head abnormalities. Efforts required to establish local standard operation procedures (SOPs) for contrast medium use especially in CT head examinations. Further studies to improve the knowledge of agents, mechanism of action, and safety of contrast media used among practitioners in Ghana is recommended.

Novel contrast-computed tomography method based on a Gaussian Mixture Model for assessment of fibrocalcific volume in aortic valve stenosis

Abstract Background Discordant echocardiography is observed in up to one third of patients with aortic stenosis (AS), in whom computed tomography (CT) derived aortic valve calcium scoring is now recommended. However, CT calcium scoring only assesses calcific valve thickening and ignores non-calcific fibrotic thickening, which could be an important contributor of AS. Purpose To generate a quick and robust contrast-CT method based on a gaussian mixture model (GMM) for assessment of fibro-calcific aortic valve thickening in patients with AS, and to investigate its reproducibility and associations with echo parameters of AS severity and disease progression. Methods A post-hoc analysis of 136 patients with calcific AS (24 with severe, 81 moderate and 31 mild AS) enrolled in the SALTIRE2 trial (NCT-02132026) was performed. Aortic valve fibrocalcific volume was calculated using a GMM applied on contrast-CT at baseline and at 1-year follow up. The software estimated the Hounsfield Units (HU) distribution of 3 compartments (blood pool, non-calcific and calcific tissue) within the aortic valve volume of interest, automatically generating thresholds for non-calcific and calcific tissue, respectively computed as the lower 99.7 and the upper 99.7 percentile of the blood pool HU distribution (Figure 1). Fibrocalcific volume was measured as the sum of calcific and non-calcific volumes, indexed for CT annulus area and compared to echo parameters of AS severity. Evaluation of scan-rescan reproducibility and AS progression were also assessed. Results Image analysis took 5.8±1.0 minutes per scan and showed excellent scan-rescan reproducibility (mean difference −1%, limits of agreement −9% to 7%). Indexed-fibrocalcific volume correlated well with echocardiographic aortic peak velocity (rho=0.70, p&amp;lt;0.0001), better than non-calcific and calcific volumes alone (rho=0.30 and rho=0.61 respectively, both p&amp;lt;0.0001) and Agatston calcium score (rho=0.63, p&amp;lt;0.0001). Baseline indexed-fibrocalcific volume was also the strongest predictor of subsequent AS progression in terms of change in aortic valve peak velocity (rho=0.29, p=0.006) and mean gradient (rho=0.39, p&amp;lt;0.0001). Progression-to-noise ratio for fibrocalcific volume was favourable (Cohen's statistic d=0.62), indicating that groups sizes of 21, 46 and 170 participants would be required to demonstrate 30%, 20% and 10% reductions in fibro-calcific volume progression with a novel drug respectively (alpha=0.05, power=80%). Conclusions This novel contrast CT-based approach can provide robust and rapid assessment of fibrocalcific thickening in AS patients. Fibrocalcific volume measured using this technique, correlates well with other markers of AS severity, predicts disease progression and holds promise in tracking disease progression and response to novel therapies. Funding Acknowledgement Type of funding sources: None.

Rapid quantification of COVID-19 pneumonia burden from computed tomography with convolutional long short-term memory networks.

.Purpose: Quantitative lung measures derived from computed tomography (CT) have been demonstrated to improve prognostication in coronavirus disease 2019 (COVID-19) patients but are not part of clinical routine because the required manual segmentation of lung lesions is prohibitively time consuming. We aim to automatically segment ground-glass opacities and high opacities (comprising consolidation and pleural effusion).Approach: We propose a new fully automated deep-learning framework for fast multi-class segmentation of lung lesions in COVID-19 pneumonia from both contrast and non-contrast CT images using convolutional long short-term memory (ConvLSTM) networks. Utilizing the expert annotations, model training was performed using five-fold cross-validation to segment COVID-19 lesions. The performance of the method was evaluated on CT datasets from 197 patients with a positive reverse transcription polymerase chain reaction test result for SARS-CoV-2, 68 unseen test cases, and 695 independent controls.Results: Strong agreement between expert manual and automatic segmentation was obtained for lung lesions with a Dice score of ; excellent correlations of 0.93 and 0.98 for ground-glass opacity (GGO) and high opacity volumes, respectively, were obtained. In the external testing set of 68 patients, we observed a Dice score of as well as excellent correlations of 0.99 and 0.98 for GGO and high opacity volumes, respectively. Computations for a CT scan comprising 120 slices were performed under 3 s on a computer equipped with an NVIDIA TITAN RTX GPU. Diagnostically, the automated quantification of the lung burden % discriminate COVID-19 patients from controls with an area under the receiver operating curve of 0.96 (0.95–0.98).Conclusions: Our method allows for the rapid fully automated quantitative measurement of the pneumonia burden from CT, which can be used to rapidly assess the severity of COVID-19 pneumonia on chest CT.

POS-034 MICROBIOLOGICAL PROFILE OF CYST INFECTION IN AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE IN NORTH INDIA

Autosomal dominant polycystic kidney disease (ADPKD) is most common inherited kidney disorder. Cyst infection is common in ADPKD and could be fatal in some cases. There is limited evidence on management of these case and most cases are treated with empirical antibiotics. We conducted this study to identify the causative microorganisms and determine antibiotic susceptibility to these organisms in our region. This study was conducted between May 2015 to January 2022 at a tertiary care center in Rajasthan. Suwabe criteria was applied to diagnose cyst infection. Abdominal computed tomography (CT) was done in all ADPKD patients with clinical and laboratory features suggestive of cyst infection. Non contrast CT was performed in cases with renal dysfunction. Ultrasound guided percutaneous needle aspiration of infected renal cyst was performed in cases with persistent fever for more than 1 week despite empirical antibiotic therapy. Cyst aspirate was subjected to culture and sensitivity to conventional lipid soluble antibiotics (Fluoroquinolones/ trimethoprim-sulfamethoxazole) using BD BACTEC™ automated blood culture systems (Figure 1). Twenty-seven patients with features suggestive of cyst infection on CT abdomen were subjected to ultrasound guided cyst aspiration. Clinical characteristics of the patients has been depicted in Figure 2. Simultaneous pyuria was present in five (18.5%) cases while urine culture was positive only in two (7.4%) cases. Cyst aspirate culture was positive in eighteen (66.7%) cases. Microbiological profile has been depicted in Figure 3. Escherichia coli was the most common isolated organism. There was low sensitivity to conventional lipid soluble antibiotics with 38.9% (7/18) patients sensitive to fluoroquinolones (Ciprofloxacin/ Levofloxacin) and 50% (9/18) patients sensitive to trimethoprim-sulfamethoxazole. Gram negative bacteria are the most common cause of cyst infection in ADPKD patients. There is high resistance to conventional lipid soluble antibiotics in our region and we should reconsider their empirical use in these patients. We also want to reiterate that cyst aspiration should be considered early as diagnostic modality to find out the causative organisms and their drug sensitivity.