Prior CT Research Articles

A 69-YEAR-OLD MAN WITH HEAVY ASBESTOS EXPOSURE, DYSPNEA, AND PLEURAL SOFT-TISSUE THICKENING

A 69-YEAR-OLD MAN WITH HEAVY ASBESTOS EXPOSURE, DYSPNEA, AND PLEURAL SOFT-TISSUE THICKENING

S2611 It Is so Complicated: Pancreatico-Spleno-Colonic Fistula Presenting as Gastrointestinal Bleeding

Introduction: Gastrointestinal bleeding is common in clinical practice with variable etiology, we present a rare case of pancreatic pseudocyst complicated by spleno-colonic fistula manifesting with brisk hematochezia. Case Description/Methods: A 50-year-old male with no significant past medical history presented with fever and acute encephalopathy. He subsequently had a prolonged and complicated hospital course with a new diagnosis of Human immunodeficiency virus/Acquired immunodeficiency syndrome, disseminated tuberculosis, and chronic pancreatitis with a pancreatic pseudocyst. During hospitalization, the patient suddenly developed passage of bright red blood per rectum over 48 hours with down-trending hemoglobin. Hemoglobin initially dropped from 9.6 g/dL to 5.0 g/dl (Normal: 12-16 g/dL) and he required multiple units of packed red cell, platelets, and fresh frozen plasma transfusion. The patient underwent a tagged Red blood cell scan with radiolabelled 28.4 mCi of Tc-99 m. Red blood cell tagged Tc 99 m gastrointestinal bleeding scan showed large brisk pooling of the radiotracer in the splenic flexure consistent with significant active hemorrhage in the region of the splenic flexure. There was a retrograde flow of the tracer into the transverse colon and antegrade flow into the descending colon. Retrospective evaluation of the prior CT tomography scans of the abdomen demonstrated possible communication between the pancreatic tail cyst, the spleen as well as the splenic flexure which was the likely source of the GI bleed. The patient had a total of 35 units of packed red blood cells transfused, 8 units of platelets, and 7 units of fresh frozen plasma during his hospital course. The patient failed multiple attempts at Interventional radiology arterial embolization and due to multiple co-morbidities, he was not a candidate for surgical intervention. He later died after 6 months of hospitalization (Figure 1). Discussion: There have been reported cases of pancreatico-colonic fistula and spleno-colonic fistula, arising from pancreatic pseudocysts and pseudoaneurysms associated with trauma, pancreatitis, and Crohn’s disease. Pancreatico-spleno-colonic fistula is a rare and complex entity usually presenting with massive gastrointestinal bleeding. The findings of acute or chronic pancreatitis and pseudocyst with gastrointestinal bleeding should raise the suspicion of possible pancreatico-colonic fistula. Prompt imaging is key to accurate diagnosis and management.Figure 1.: Tc-99 m RBC tagged showing radiotracer in the splenic flexure, transverse colon and the descending colon. Non-contrast (A) and contrast enhanced axial (B, C) and coronal (D, E) computerized tomographic scan of the abdomen showing cystic mass at the tail of pancreas (blue arrow) communicating with the spleen and splenic flexure of the colon(red arrow).

BILIPTYSIS: BRONCHOBILIARY FISTULA (BBF) RESULTING FROM RIGHT LOWER LUNG ABSCESS

BILIPTYSIS: BRONCHOBILIARY FISTULA (BBF) RESULTING FROM RIGHT LOWER LUNG ABSCESS

Histo-Pathological Evaluation of Breast Cancer after Neo-Adjuvant Chemotherapy

Background: A recent standardized therapeutic technique for the patients having advanced and large (bigger than two centimeters) breast cancer is neo-adjuvant chemotherapy. The gold standard is the histo-pathological assessment of carcinoma response. Methodology: In this research study, we performed the histo-pathologic evaluation of forty-four samples received in the pathology department over a period of one year from 1 July 2021 to 30 June 2022. Results: In this research study, we studied total forty-four patients with breast cancer. Average age of these females was fifty years. Average size prior CT was 56.140 centimeter square and post CT was 29.4 centimeter square. In this research work, complete pathologic response was shown by eighteen percent patients and incomplete response was shown by eighty-four percent patients. Conclusion: Changes in pattern of characterizations examined after the histo-pathological evaluation of tumor are dystrophic calcification, stromal hyalinization, regions of coagulated necrosis, reactive infiltration of lymphocytes, cellular fibrous tissue and hemosiderin laden macrophages. Keywords: Characterization, pathology, evaluation, neo-adjuvant chemotherapy, carcinoma, cancer, average.

398 Acute Paediatric Appendicitis (AA)- Decreasing the Negative Rate of Appendicectomy in a District General Hospital

Abstract Aim Globally Acute appendicitis (AA) is the most common general surgical emergency. A recent consensus study has proposed a negative appendicectomy rate of 10%. Our aim is to monitor and reduce the negative rate of paediatric appendicectomy and optimise the acute paediatric management following the newly introduced workflow. Method Retrospective patient data collection via electronic sources (Evolve discharge summary, Operation notes) for all paediatric patients (0–16 years old) admitted with AA between March 23rd and October 31st, 2020. Results We separated our audit in three different periods of time. In the first period, 5 out 20 (25%) who underwent an appendicectomy had a normal appendix on histological analysis. In the second period (from June to August) we introduced a paediatric assessment workflow and managed to decrease the negative rate of appendicectomy from 25% to 19%. During the third period (from September to October 2020) the negative rate of appendicectomy decreased to 11%, 14% less than our initial result. More patients underwent an US prior CT as part of routine screening in order to avoid a negative appendicectomy. The initial percentage of US scanning was 72% and was increased to 90% after the end of the third period. Additionally, conservative management was 20% and was increased to 24% after the end of the third period. Conclusions Due to the results of this study, the paediatric appendicitis workflow in daily practice has resulted in more patients being treated conservatively.

Diagnostic Range Ionizing Radiation and Reactive Oxygen Species Production: an Initial Experience

Radiation is a common occurrence in our daily lives that comes from both natural and man-made sources. Ionizing Radiation (IR) causes damage either directly or indirectly through the generation of reactive oxygen species (ROS). Oxidative damage to DNA, lipids, proteins, and many metabolites occurs through a complex series of processes that are enhanced by endogenous signalling which is activated by free radicals. Though literature is abundant on ROS and antioxidants at high doses, no study to the best of our knowledge has assessed the ROS levels after Multi Detector Computed Tomography (MDCT) examination (i.e. in diagnostic range radiation). The aim of the present study was to assess the production of ROS after diagnostic level radiation by MDCT examination and at 24 hour follow up. The study involved fifty patients posted for clinically indicated MDCT which were recruited. The average radiation dose was 2-9 mGy. Three blood samples were drawn, one prior to CT (control sample), within half an hour of CT (post CT) and 24 hrs after CT. 3 ml venous blood was withdrawn in aseptic conditions and immediately serum was isolated for ROS assessment. The blood examination results were compared in immediate and post 24 hour after MDCT and both were compared with control values and correlated with radiation parameters. Our results have shown a significant increase in ROS level in immediate post CT samples compared to prior CT scan samples (control) (p value <0.0001). The ROS levels reduced at 24 hours compared to immediate post CT, however they were still higher than control values. Our findings reflect that there is a rapid increase in free radicals production in the mitochondria after diagnostic level radiation. Detection of higher ROS levels at 24 hours suggests incomplete repair with the presence of some residual oxidative species at 24 hours.

Evaluation of changes in lymph node size and metabolism by PET CT in patients with cancer who have been immunized against COVID 19: A Mexican study.

e13647 Background: The risk of developing COVID-19 in patients with cancer has increased, directly influenced by age and the magnitude of comorbidities. In this population, the estimated mortality is 10.9%. With this, the urgent need for patients with cancer to get vaccinated against SARS COV 2 has generated an international response. With the ongoing vaccination campaign, experts in nuclear medicine have observed an increment in lymph node uptake in PET CT with 18 FDG. Increased uptake in lymph nodes in patients with a neoplastic diagnosis on PET CT 18 FDG must be closely followed and well-studied to differentiate disease progression from an inflammatory, fleeting reaction. Methods: Amongst the inclusion criteria were patients over 18 years of age with solid tumors, including lymphomas, who were on active oncologic treatment with chemotherapy, immune therapy, radiotherapy or under surveillance between April 2021 and July 2021 who underwent a PET CT scan and had at least one dose of a COVID 19 vaccine, and a prior PET CT to the vaccine for comparison. Patients were excluded who showed evidence of progression or disease recurrence of the primary tumor. We evaluated lymph node size and metabolism measured by SUV max in the PET CT scan prior to being vaccinated and posterior to, as well as patients’ clinical characteristics. Results: A total of 92 patients who met inclusion criteria were included in the study. Amongst those, 54.3% were women, the median age was 68 years (27 - 95 years), the most common neoplastic diagnoses were breast cancer (19.6%), gastrointestinal tumors (17.4%), urothelial tumors (9.8%), lymphomas (9.8%) and ovarian cancer (8.7%). 52.2% of patients were under surveillance and 47.8% were under active treatment. 79% of patients had at least 2 vaccine doses. 59% had received Pfizer vaccines and the measurable adenopathies were axillary in 32.7% and mediastinal in 27%. The medium size of the measured lymph nodes prior to receiving the vaccine was 2.86 mm with an SUV max of 1.24, while after vaccination were 6.01 and 2.27 respectively. A Kruskal Wallis test was conducted to compare median results according to histopathologic reports, with no statistical difference. A Mann Whitney U test was conducted to compare breast cancer to other cancer histologies, where a statistical difference was found for SUV max, p = 0.003 and size with p = 0.033. Conclusions: This work details significant differences between lymph node size and SUV max in oncologic patients pre and post vaccination for COVID 19, showing a statistical difference in patients with breast cancer. This increment in lymph node uptake in patients with a neoplastic diagnosis PET CT 18 FDG must be closely followed and well-studied to differentiate disease progression from an inflammatory reaction.

Single-Center Retrospective Comparative Study Evaluating the Benefit of Computed Tomography Angiography Prior to Prostatic Artery Embolization.

To explore whether a computed tomography angiography (CTA) of the pelvis prior to prostatic artery embolization (PAE) is a beneficial preprocedural planning tool regarding the technical success. Eighty patients with lower urinary tract symptoms treated with PAE were analyzed retrospectively. Forty of these patients received a CTA of the pelvis prior to the procedure (Group A) and were compared to 40 patients who were treated with PAE without prior CT imaging (Group B). Technical success rate, rate of complications, fluoroscopy time (FT), and mean dose area product (DAP) were assessed and compared. All operators performed at least 50 PAE prior to this study. When needed, cone-beam CT (CBCT) was available during intervention. Mean age was 68.43 ± 8.30years in Group A and 70.42 ± 7.11years in Group B (p = 0.252). Mean body mass index was 26.78 ± 3.73 in Group A and 26.85 ± 3.5 in Group B (p = 0.319). Overall technical success was 96.3%. Bilateral PAE was achieved in 60 patients (75.0%) while unilateral PAE was performed in 17 patients (21.3%). Technical failure (no embolization) occurred in two patients of Group A and one patient of Group B. No statistical significance was seen between groups for technical success rate (p = 1.0). Mean DAP was 10,164 × cm2 ± 3944cGy × cm2 in Group A and 10,039 × cm2 ± 3761cGy × cm2 in Group B (p = 0.885). Mean FT was 49.27 ± 22.97min in Group A and 44.32 ± 17.82min in Group B (p = 0.285). No intervention-related complications during PAE were reported. With experienced interventionalists and CBCT available during PAE, preprocedural CTA has no additional benefit for technical outcome.

Abstract PD13-05: Alpelisib + fulvestrant in patients with PIK3CA-mutated, HR+, HER2— advanced breast cancer (ABC) who received chemotherapy or endocrine therapy (ET) as immediate prior treatment: BYLieve Cohort C primary results and exploratory biomarker analyses

Abstract Introduction: Alpelisib (ALP), an inhibitor and degrader of phosphatidylinositol-3-kinase α (PI3Kα), + fulvestrant (FUL) demonstrated efficacy in PIK3CA-mutated, HR+, HER2- ABC in the phase 3 SOLAR-1 trial, which included only 20 patients (pts) with prior CDK4/6 inhibitor (CDKi) in the PIK3CA-mutated cohort. BYLieve (NCT03056755), a phase 2, open-label, 3-cohort noncomparative study, evaluates ALP + endocrine therapy (ET; FUL or letrozole [LET]) in pts with PIK3CA-mutated, HR+, HER2- ABC, progressing on/after prior therapies, including CDKi + ET. Cohorts A and B were restricted to pts receiving CDKi + (aromatase inhibitor [AI] or FUL), respectively, as immediate prior therapy, but Cohort C included pts whose cancer progressed on/after AI (in adjuvant or metastatic setting), and who received chemotherapy (CT; any line), or ET (FUL or LET monotherapy or with targeted therapy, including CDKi + FUL, but not CDKi + AI) as immediate prior treatment. Cohorts A and B demonstrated efficacy and safety of ALP + ET after prior CDKi. Here, we report primary results and biomarker analyses from Cohort C.. Methods: Pts in Cohort C received ALP 300 mg orally QD + FUL 500 mg intramuscular Q28D + C1D15. The primary endpoint was assessed in each cohort separately and is the proportion of pts with centrally confirmed PIK3CA mutation alive and without disease progression at 6 mo per local assessment; 95% CIs are calculated using Clopper and Pearson (1934) exact method. The 95% CI lower bound of the primary endpoint >30% is clinically meaningful evidence of treatment effect. In an exploratory analysis of baseline biomarkers using ctDNA, progression-free survival (PFS) was estimated in pt subgroups per high (≥10%) or low (<10%) ctDNA fraction and ESR1 mutational status via Kaplan-Meier estimation.. Results: 127 pts were enrolled in Cohort C (1 pt discontinued prior to treatment start) with ≥6 mo follow-up by the cutoff date (14 Jun 2021); 115 had a centrally confirmed PIK3CA mutation. Median follow-up was 11.4 mo (range, 0-23 mo); 79 (62.7%) pts had ≥2 prior lines of therapy in the metastatic setting, 58 (46.0%) pts had prior CT exposure in the metastatic setting, and 41 (32.5%) pts had prior FUL exposure in the metastatic setting. The primary endpoint was met, with 48.7% (95% CI, 39.3%-58.2%) of pts alive and without disease progression at 6 mo. Median PFS (mPFS) was 5.6 mo (95% CI, 5.4-8.1 mo). The most common all-grade adverse events (AEs) by preferred term were hyperglycemia (n=82, 65.1%), diarrhea (n=66, 52.4%), nausea (n=51, 40.5%), and rash (n=49, 38.9%). Grade ≥3 AEs (≥10%) included hyperglycemia (n=30, 23.8%) and rash (n=17, 13.5%). AEs leading to discontinuation occurred in 15.1% (n=19) of pts; most frequent AEs leading to discontinuation were rash (n=5, 4.0%) and hyperglycemia (n=4, 3.2%). Exploratory biomarker analyses in 74 pts who had available baseline biomarker samples at data cutoff showed that pts with a low ctDNA fraction (n=23) had longer mPFS than pts with high ctDNA fraction (n=51; 16.7 [95% CI, 10.4-19.5] vs 5.4 [95% CI, 2.9-7.2] mo; p<0.001, HR=0.31 [95% CI, 0.2-0.6]). Efficacy was similar in pts with (n=20) and without (n=54) ESR1-mutated tumors (6.3 [95% CI, 2.8-8.3] vs 8.3 [95% CI, 5.5-16.7] mo; p=0.095, HR=0.59 [95% CI, 0.3-1.1]).. Conclusion: In Cohort A of BYLieve, efficacy of ALP + FUL suggests clinical benefit immediately after CDKi + AI; Cohort C confirms clinically relevant activity of ALP + FUL in a heterogeneous population, primarily treated in the third line or later, and potentially regardless of ESR1 status or ctDNA fraction, with no new safety signals detected. Together, these data confirm that ALP targets the effects of the PIK3CA-driver oncogene in HR+, HER2- ABC. Citation Format: Hope S Rugo, Patrick Neven, Isabel Saffie, Yeon Hee Park, Michelino De Laurentiis, Florence Lerebours, Eva Maria Ciruelos, Nicholas Turner, Dejan Juric, Ennan Gu, Christina H Arce, Mukta Joshi, Estelle Roux, Murat Akdere, Stephen Chia. Alpelisib + fulvestrant in patients with PIK3CA-mutated, HR+, HER2— advanced breast cancer (ABC) who received chemotherapy or endocrine therapy (ET) as immediate prior treatment: BYLieve Cohort C primary results and exploratory biomarker analyses [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD13-05.

Cancer Risk in Nodules Detected at Follow-Up Lung Cancer Screening CT.

BACKGROUND. Nodules may have different lung cancer risks when new on follow-up CT versus when present on previously performed CT (i.e., existing nodules). Diameter-based Lung-RADS and volume-based NELSON (Nederlands-Leuvens Longkanker Screenings ONderzoek trial) categories have shown variable performance in nodule risk assessment. OBJECTIVE. The purpose of this study was to assess Lung-RADS and NELSON classifications of nodules detected on follow-up lung cancer screening CT examinations. METHODS. This retrospective study included 185 patients (100 women and 85 men; median age, 66 years) who underwent a lung cancer screening CT examination for which a prior CT examination was available. Stratified random sampling was performed to enrich the sample with suspicious nodules, yielding 50, 45, 47, 30, and 13 nodules with Lung-RADS categories 2, 3, 4A, 4B, and 4X, respectively. Lung-RADS categories were recorded from clinical reports. The linear measurements of the nodules were extracted from clinical reports to generate Lung-RADS categories by use of strict criteria from Lung-RADS version 1.1. Two radiologists used a semiautomated tool to obtain nodule volumes, which were used to generate NELSON categories. Lung cancer risk was assessed. ROC analysis was performed. Percentages and AUCs were weighted on the basis of Lung-RADS category frequencies in the underlying screening cohort. RESULTS. Twenty-nine cancers were diagnosed. The weighted cancer risk was 5% for new nodules, 1% for stable existing nodules, and 44% for growing existing nodules. None of the clinical Lung-RADS category 2 nodules were cancer. With use of strict Lung-RADS version 1.1 criteria, 34 nodules, including seven cancers, were downgraded to category 2. The AUC for cancer was 0.96 for clinical Lung-RADS, 0.81 for strict Lung-RADS, 0.71-0.84 for the NELSON algorithm (two readers), and 0.89 for nodule diameter measurement. Clinical Lung-RADS achieved weighted sensitivity and specificity, respectively, of 100% and 85% for the entire sample, 100% and 41% for new nodules, and 100% and 94% for existing nodules. The optimal diameter threshold was 8 mm for existing nodules versus 6 mm for new nodules. CONCLUSION. Lung-RADS, as applied by radiologists in clinical practice, achieved excellent performance on follow-up screening examinations. Strict Lung-RADS resulted in the downgrading of some cancers to category 2. Volumetric assessments had weaker performance than clinical Lung-RADS. New nodules warrant smaller size thresholds than existing nodules. CLINICAL IMPACT. The findings of the present study provide insight into radiologists' management of nodules detected on follow-up screening examinations.

February 2022 Medical Image of the Month: Multifocal Micronodular Pneumocyte Hyperplasia in the Setting of Tuberous Sclerosis

No abstract available. Article truncated at 150 words. A 22-year-old man with a known diagnosis of Tuberous Sclerosis Complex (TSC) presents for a follow-up unenhanced chest CT to re-evaluate pulmonary nodules seen in the lung bases on a prior abdominal CT. The patient also has a history of multiple renal lesions consistent with lipid-poor angiomyolipomas based on previous abdominal MRI findings. The chest CT demonstrated multiple scattered, randomly distributed sub-centimeter pulmonary nodules of solid or subsolid morphology [Figure 1A]. Those nodules visible in the lung bases on the prior abdominal CT had remined stable over the 12-month interval consistent with multifocal microscopic pneumocyte hyperplasia (MMPH)[Figure 1B,C]. Myocardial fatty foci (MFF) were visualized in the heart on soft tissue window display settings [Figure 2A] as were multiple scattered sclerotic bone lesions on bone window display settings [Figure 2B,C]. No pulmonary cysts were seen to suggest lymphangioleiomyomatosis (LAM) and there were no thoracic lymphangiomas. MMPH represents a benign hamartomatous proliferation …

Feasibility of a prototype carbon nanotube enabled stationary digital chest tomosynthesis system for identification of pulmonary nodules by pulmonologists.

BackgroundScreen detected and incidental pulmonary nodules are increasingly common. Current guidelines recommend tissue sampling of solid nodules >8 mm. Bronchoscopic biopsy poses the lowest risk but is paired with the lowest diagnostic yield when compared to CT-guided biopsy or surgery. A need exists for a safe, mobile, low radiation dose, intra-procedural method to localize biopsy instruments within target nodules. This retrospective cross sectional reader feasibility study evaluates the ability of clinicians to identify pulmonary nodules using a prototype carbon nanotube radiation enabled stationary digital chest tomosynthesis system.MethodsPatients with pulmonary nodules on prior CT imaging were recruited and consented for imaging with stationary digital chest tomosynthesis. Five pulmonologists of varying training levels participated as readers. Following review of patient CT and a thoracic radiologist’s interpretation of nodule size and location the readers were tasked with interpreting the corresponding tomosynthesis scan to identify the same nodule found on CT.ResultsFifty-five patients were scanned with stationary digital chest tomosynthesis. The median nodule size was 6 mm (IQR =4–13 mm). Twenty nodules (37%) were greater than 8 mm. The radiation entrance dose for s-DCT was 0.6 mGy. A significant difference in identification of nodules using s-DCT was seen for nodules <8 vs. ≥8 mm in size (57.7% vs. 90.9%, CI: −0.375, −0.024; P<0.001). Inter-reader agreement was fair, and better for nodules ≥8 mm [0.278 (SE =0.043)].ConclusionsWith system and carbon nanotube array optimization, we hypothesize the detection rate for nodules will improve. Additional study is needed to evaluate its use in target and tool co-localization and target biopsy.

Case 300

A 40-year-old woman presented to the outpatient department of our hospital with a 2-year history of abdominal pain, which had worsened in the past few days. There were no other constitutional symptoms; in particular, there was no weight loss or loss of appetite. The serum amylase and serum lipase levels were always within normal limits, even during the current episode. There was no history of pancreatitis, alcohol abuse, drug use, or trauma. The patient was evaluated at an outside clinic 2 years ago and underwent imaging, including US and dedicated pancreatic CT, which revealed a complex multiseptated noncalcified pancreatic cystic lesion. After CT, the patient underwent endoscopic US, which showed the lesion was suspected to be an infected parasitic cyst; fine-needle aspiration and cytology were not attempted due to the risk of iatrogenic rupture. The patient was advised to undergo surgical resection but declined the procedure and was lost to follow-up for 2 years before her current visit to our facility. On clinical examination, there were no clinically important findings, aside from mild to moderate pain on deep palpation and some shifting dullness that was suggestive of ascites. The patient always remained hemodynamically stable. US-guided ascitic fluid analysis was performed, which revealed amylase levels of 869 IU/L (normal range, 4-234 IU/L). Considering prior CT and endoscopic US reports, the patient was further evaluated with a pancreatic MRI protocol for lesion characterization and to explain the new-onset abdominal pain (Figs 1, 2).

Economic impact of spectral body imaging in diagnosis of patients suspected for occult cancer

BackgroundBased on prior studies spectral CT has shown a higher sensitivity for malignant lesions than conventional CT at the cost of lower specificity. For the radiologists, it also offers a higher degree of certainty in the diagnosis of benign lesions. The objective of this study was to evaluate the economic impact of spectral CT in patients suspected of occult cancer in a medical center in Denmark.MethodsThis study was a secondary analysis using de-identified data from a prospective study of patients receiving a contrast-enhanced spectral CT scan. Based on suggested follow-up examinations on both spectral CT and contrast-enhanced CT, costs from a payer’s perspective were determined using unit costs obtained from national databases.ResultsThe dataset contained 400 patients. Overall, 203 follow-up procedures were eliminated based on spectral data reading. The largest reduction in suggested follow-up procedures was found for the kidney (83%), followed by the liver (66%), adrenal glands (60%), and pancreas (42%). The total estimated costs for suggested follow-up procedures based on spectral data reading were €155,219, 25.2% (€52,384) less than that of conventional CT reading.ConclusionOur results provide support for spectral body imaging as an advanced imaging modality for suspected occult cancer. A substantial number of follow-up diagnostic procedures could be eliminated based on spectral data reading, which would result in significant cost savings.

Prior image-guided cone-beam computed tomography augmentation from under-sampled projections using a convolutional neural network.

Acquiring sparse-view cone-beam computed tomography (CBCT) is an effective way to reduce the imaging dose. However, images reconstructed by the conventional filtered back-projection method suffer from severe streak artifacts due to the projection under-sampling. Existing deep learning models have demonstrated feasibilities in restoring volumetric structures from the highly under-sampled images. However, because of the inter-patient variabilities, they failed to restore the patient-specific details with the common restoring pattern learned from the group data. Although the patient-specific models have been developed by training models using the intra-patient data and have shown effectiveness in restoring the patient-specific details, the models have to be retrained to be exclusive for each patient. It is highly desirable to develop a generalized model that can utilize the patient-specific information for the under-sampled image augmentation. In this study, we proposed a merging-encoder convolutional neural network (MeCNN) to realize the prior image-guided under-sampled CBCT augmentation. Instead of learning the patient-specific structures, the proposed model learns a generalized pattern of utilizing the patient-specific information in the prior images to facilitate the under-sampled image enhancement. Specifically, the MeCNN consists of a merging-encoder and a decoder. The merging-encoder extracts image features from both the prior CT images and the under-sampled CBCT images, and merges the features at multi-scale levels via deep convolutions. The merged features are then connected to the decoders via shortcuts to yield high-quality CBCT images. The proposed model was tested on both the simulated CBCTs and the clinical CBCTs. The predicted CBCT images were evaluated qualitatively and quantitatively in terms of image quality and tumor localization accuracy. Mann-Whitney U test was conducted for the statistical analysis. P<0.05 was considered statistically significant. The proposed model yields CT-like high-quality CBCT images from only 36 half-fan projections. Compared to other methods, CBCT images augmented by the proposed model have significantly lower intensity errors, significantly higher peak signal-to-noise ratio, and significantly higher structural similarity with respect to the ground truth images. Besides, the proposed method significantly reduced the 3D distance of the CBCT-based tumor localization errors. In addition, the CBCT augmentation is nearly real-time. With the prior-image guidance, the proposed method is effective in reconstructing high-quality CBCT images from the highly under-sampled projections, considerably reducing the imaging dose and improving the clinical utility of the CBCT.

A Transfer Learning Approach for Improving OAR Segmentation in the Adaptive Therapy or Retreatment of Head and Neck Cancer

<h3>Purpose/Objective(s)</h3> Deep learning-based segmentation has achieved great progress compared with traditional method. However, the generalizability is still an unsolved problem, leading to suboptimal contours for some cases that requires manual editing. A big source of error lies in the abnormal patient anatomy that was not well covered by the training data. In adaptive or retreatment settings, a well-contoured CT is available. However, the current DLSEG algorithm does not allow such information to be utilized. Our proposed solution is to use transfer learning method to tune a trained DLSEG model toward individual patient using the prior segmented scans. <h3>Materials/Methods</h3> A HN DLSEG model was trained on 2015 MICCAI Head and Neck dataset. The model was applied on HNSCC-3DCT-RT dataset from TCIA which contains 3 CT scans at pre-, mid-, and end- treatment course. The DLSEG result was compared with the ground truth contour in the study. Dice similarity coefficient (DSC), 95% Hausdorff distance (HD95), and mean surface distance (MSD) were computed for BrainStem, Mandible, Parotid, SpinalCord and OpticNerve. The standard deviations of these metrics were computed, both within the same patient (IntraPatient variation) and across patients (InterPatient variation). Then, the DLSEG was re-tuned using transfer learning on the pre- treatment CT scan of each individual patient. The re-tuned model was applied to the mid- and end- treatment CT. The segmentation accuracy was evaluated. <h3>Results</h3> All structures showed a much larger InterPatient variation than IntraPatient variation, indicating that patient specific anatomical feature is one of the main contributors to segmentation accuracy. When transfer learning is applied. Nearly all patients saw improvement in contouring accuracy. Statistically significant improvement was observed for BrainStem, Mandible, Parotid and Parotid_L. <h3>Conclusion</h3> Transfer learning is a promising approach to incorporate the existing segmentation on prior CT to improve the segmentation accuracy in the adaptive or re-treatment settings.

Patients presenting with acute coronary syndromes have unreported coronary artery calcium on historical CT imaging

Abstract Introduction Ischaemic heart disease (IHD) remains the leading cause of mortality globally1. The presence and extent of coronary artery calcification (CAC) is a strong predictor of cardiovascular events, and CAC scoring has been shown to be more predictive of cardiovascular events than other traditional risk assessment scores2. Incidental coronary calcification can be detected and quantified on non-gated CT chest scans covering the heart in the field of view3. This finding is typically not reported4 and hence an opportunity to optimise cardiovascular risk assessment and treatment is missed. Purpose We sought to investigate whether patients presenting to our centre with an acute coronary syndrome (ACS) event had historical CT imaging demonstrating coronary artery calcification. Methods We retrospectively reviewed case records for all patients referred to our centre for an invasive coronary angiogram following their first known admission with an ACS event. ACS were defined according to contemporary guidelines from the European Society of Cardiology. We reviewed a 3 month period prior to the COVID-19 pandemic (01/01/2019–31/03/2019). The national imaging database was interrogated to identify previous CT imaging that includes the heart in the field of view. The presence of coronary calcification was confirmed and quantified using an ordinal scoring method previously described3. The clinical radiology reports for the scans were reviewed to determine the frequency of CAC being reported. Demographic information was collected from our electronic patient record including the presence of risk factors for IHD. Prescribed medication prior to admission was also recorded using the on-admission medicines reconciliation documented in the electronic patient record. Results 385 patients with first presentation of ACS were identified. 75 (19%) had a prior non-gated CT chest imaging. The most common indication for CT was for investigation of possible malignancy. The mean interval from CT imaging to ACS admission was 36 months. CAC was present on 67 (89%) scans. The mean ordinal score was 4.04, corresponding to moderate CAC. The distribution of CAC by coronary artery revealed the majority of disease to involve the left anterior descending artery (Table 1). Only 12/67 (18%) of clinical radiology reports mentioned coronary calcification (Figure 1). Patients with CAC frequently had additional risk factors for IHD. Despite this only 42% were prescribed antiplatelet therapy, and only 45% prescribed a statin. Conclusions A significant proportion of ACS admissions have evidence of CAC on historical CT scans. This finding is often not reported and the majority of patients with demonstrated coronary artery disease are not prescribed appropriate preventative therapies. Systematic reporting of this finding may have a significant impact on the prevention of acute cardiovascular events. Funding Acknowledgement Type of funding sources: None. Table 1

S2747 Hereditary Hemorrhagic Telangiectasia: A Rare Disease Diagnosed From Incidental Liver Lesions

Introduction: Hereditary hemorrhagic telangiectasia (HHT) is a rare, autosomal dominant syndrome characterized by mucocutaneous telangiectasias and AVMs. Epistaxis and GI bleeding are the most common presenting features. HHT-related visceral AVMs have also been well-described and when identified without a prior diagnosis of HHT can present a significant diagnostic challenge. Case Description/Methods: A 60-year-old male with prior history of prior tobacco and alcohol use was referred to GI clinic for two years of chronic diarrhea and dyspepsia. No unintentional weight loss although he reported intermittent episodes of epistaxis every 2-3 months for past 40 years. Physical examination and family history was unremarkable. CT A/P showed a heterogeneous liver with innumerable liver lesions. (Figure 1) An EGD was performed for dyspepsia which revealed an 8mm gastric body ulcer and biopsy negative for H.pylori. The patient’s diarrhea resolved with probiotics and changes to diet. Hepatology recommended a liver biopsy which was suggestive of an arteriovenous or vascular malformation with scarring. Follow up EGD revealed a healed stomach ulcer and a 5mm gastric AVM. Chart review revealed a prior CT chest with a small pulmonary vascular malformation. The patient was referred to genetics for evaluation of HHT. A HHT genetic panel was positive for a pathogenic heterozygous variant in the ACVRL1 gene and the diagnosis of HHT was confirmed. Discussion: HHT is a clinically heterogenous disorder and diagnosis requires at least three of the following Curaçao criteria: epistaxis, mucocutaneous telangiectasias, visceral AVMs and family history of HHT. HHT-related AVMs can involve the brain, lung or liver. Hepatic involvement is common ranging from 32% up to 95%. Hepatic AVMs, are rarely symptomatic and routine screening is not recommended. Symptomatic hepatic AVMs can present with three distinct clinical presentations – high output heart failure from AV shunting, portal hypertension from arterioportal shunting and biliary disease from chronic ischemia. In the absence of routine screening, follow-up of these patients requires close attention to the development of these complications. In these cases, multi-phasic CT may be the preferred imaging modality. In conclusion, hepatic AVMs should be included in the differential for hepatic lesions and genetic evaluation should be considered with concomitant history of epistaxis, GI bleeding and/or evidence of other visceral AVMs.Figure 1.: CT abdomen and pelvis without contrast revealed several liver lesions, largest lesion 3.3cm in diameter.

SUSPECTED PHEOCHROMOCYTOMA PRECIPITATING TAKOTSUBO CARDIOMYOPATHY

TOPIC: Cardiovascular Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: Takotsubo cardiomyopathy (TCM) is characterized by transient systolic dysfunction resulting in hallmark apical ballooning/hypokinesis without the presence of coronary artery disease.1 The pathophysiology entails extreme stress, which generates a sudden and massive surge of catecholamines which then markedly deranges cardiac contractility.1 One source of the catecholamine surge is pheochromocytoma: a catecholamine secreting tumor of the chromaffin cells.2 We present the case of patient who presents with both TCM and a suspected pheochromocytoma. CASE PRESENTATION: A 56-year-old female with history of both STEMI and NSTEMI presented with chest pain, nausea, vomiting, and lightheadedness. Blood pressure was 197/119 mmHg on admission. Cardiac enzymes were normal, however ECG demonstrated new lateral ST elevations in V4-V6. TTE showed apical and anterolateral akinesis with a markedly reduced EF of 18%. Nitroglycerin infusion was initiated, and patient was transferred emergently for cardiac catheterization. Patent coronary vessels were found, no intervention was performed, and medical management was pursued. Echocardiographic and catheterization findings were consistent with TCM. Further chart review showed multiple similar prior episodes plus a prior CT scan which demonstrated a 2 cm adrenal mass. Given clinical suspicion, workup for pheochromocytoma was initiated. Plasma and spot-urine metanephrines, plus spot-urine normetanephrines and 24-hour urine metanephrines were within normal limits. Plasma normetanephrines, 24-hour urine normetanephrines, epinephrine, norepinephrine, and dopamine were elevated at 731.7 pg/mL, 1538 ug/24 hours, 83 pg/mL, 4213 pg/mL, and 1020 pg/mL respectively.The patient's blood pressure was eventually controlled with oral medications. She was initiated on goal-directed medical therapy for her newly reduced EF and discharged home with endocrinology follow-up. DISCUSSION: Detection of pheochromocytoma is elusive and largely depends on elevated catecholamines in urine or blood samples via 24-hour collection. The difficulty lies in the fact that the secretion is intermittent. Measurement of VMA in urine can be done yet despite a high specificity (95%) there is a low sensitivity (64%).3 Pheochromocytoma can result in mass catecholamine release with systemic manifestations, affecting cardiac contractility. CONCLUSIONS: Our patient presented with TCM from a suspected pheochromocytoma. This diagnosis was reached via a combination of echocardiographic imaging showing apical and anterolateral akinesis, not consistent with any single coronary distribution, a clean coronary catheterization, and several lab panels demonstrating elevated levels of catecholamines/metanephrines in both the blood and urine. REFERENCE #1: Ahmad SA, Brito D, Khalid N, Ibrahim MA. Takotsubo Cardiomyopathy. In: StatPearls. StatPearls Publishing; 2020. Accessed November 13, 2020. http://www.ncbi.nlm.nih.gov/books/NBK430798/ REFERENCE #2: Y-Hassan S. Recurrent takotsubo syndrome triggered by undiagnosed pheochromocytoma. International Journal of Cardiology. 2015;187:369-371. doi:10.1016/j.ijcard.2015.03.220 REFERENCE #3: Vora KS, Shah VR. Diagnosis of pheochromocytoma. J Anaesthesiol Clin Pharmacol. 2012;28(2):274-276. doi:10.4103/0970-9185.94931 DISCLOSURES: No relevant relationships by James Gubitosa, source=Web Response No relevant relationships by Shivam Kaushik, source=Web Response

Iodine concentration and tissue attenuation in dual-energy contrast-enhanced CT as a potential quantitative parameter in early detection of local pancreatic carcinoma recurrence after surgical resection

PurposeDue to the difficult differentiation from non-specific postoperative soft tissue formation (PSF), early diagnosis of pancreatic carcinoma recurrence remains challenging. Thus, we investigated the diagnostic potential of dual-energy (DE) contrast-enhanced CT. MethodAfter potentially curative pancreatic carcinoma resection, 31 consecutive patients with PSF were examined via DE perfusion CT, acquiring 34 images (80 kVp/140 kVp) every 1.5 s, as the initial purpose of this study was evaluating CT-Perfusion. Corresponding time points of arterial, pancreatic, and early venous phase were calculated from bolus trigger times in prior conventional CT. Iodine and 120 kVp-equivalent images were calculated. Regions of interest were placed in each soft tissue formation. Diagnosis of local recurrence was confirmed by regular follow-up or histopathology. ResultsFinal diagnosis was local recurrence in 17 patients and non-specific PSF in 14 patients. Iodine concentrations in early venous phase were significantly higher in recurrent carcinoma than in non-specific PSF (1.47 mg/ml vs. 0.96 mg/ml, p = 0.007). In earlier contrast phases iodine concentrations tended to be higher, but not significantly. CT numbers in recurrent carcinoma in 120 kVp-equivalent images in venous phase were significantly higher, too (74HU vs 47HU, p = 0.002). ROC-curve analysis for iodine concentrations in early venous phase suggests a cut-off value of ≥ 1.55 mg/ml for local recurrence (AUC = 0.78, specificity = 1.0, sensitivity = 0.53) and for CT numbers in 120kVp-equivalent images a cut-off value of ≥ 57HU (AUC = 0.82, specificity = 0.82, sensitivity = 0.71). ConclusionIn difficult cases, measuring iodine concentrations or CT numbers in PSF in (early) venous phase DECT could be a valuable additional parameter for differentiating local recurrence from non-specific PSF.