Thoracic CT Research Articles

Thoracic computed tomography in dogs with neoplasia

Computer tomography has been described for the detection and characterization of different thoracic neoplastic diseases in dogs, both primary and metastatic. Its use and availability in veterinary medicine are rapidly increasing in the clinical setting, particularly in referral practices. Due to the cross-sectional nature of this modality, CT is particularly useful in the assessment of complex anatomical regions, such as the thoracic cavity. In this review, the most common applications of thoracic CT for the diagnosis and staging of different neoplastic processes in dogs are highlighted.

P2.05-08 Immunotherapy Prognostication with Thoracic CT Contrastive Self-Supervised Learning in Patients with Non-Small Cell Lung Cancer

P2.05-08 Immunotherapy Prognostication with Thoracic CT Contrastive Self-Supervised Learning in Patients with Non-Small Cell Lung Cancer

Analysis of CT Numbers in Thoracic CT Scan Image Segmentation and Spirometry on Pulmonary Vital Capacity

This research aims to analyze the correct CT Number to calculate the capacity volume of vital lungs using process segmentation image CT Scans. Compare results from capacity volume vital lungs on segmentation with results measurement volume capacity vital from spirometry. The research method used is an applied experiment that compares the results of lung vital capacity volume in segmentation with the results of vital capacity volume measurements from spirometry. Testing is carried out by calculating each volume on the CT Number used in segmentation and then comparing it with results from spirometry. Analysis data use test Correlation Pearson And Test paired Q Test Results study show that application segmentation image CT Scans with CT Numbers -850 HU up to -950 HU is quite good in calculating the volume of vital lung capacity. There is no significant difference between the results of lung vital capacity volume in segmentation and the results of vital capacity volume measurements in spirometry with a value (p > 0.05) of 0.06. The conclusion of this research is that segmentation image CT Scans of Thorax with the use of CT Numbers -850 HU until -950 HU can considered as an alternative in calculating the volume of vital lung capacity in patients with COPD.

Relationship of Main Pulmonary Artery (Truncus Pulmonalis) Diameter With Hospital Stay and Mortality in Pulmonary Hypertension Patients Admitted to the Emergency Department.

Pulmonary hypertension (PH) is a haemodynamic and pathophysiological disease significantly associated with morbidity and mortality. The increase in pulmonary vascular resistance, high pulmonary artery pressure and wall tension that occurs in PH results in dilatation of the main pulmonary artery (truncus pulmonalis), one of the largest and most important vessels in the body. The aim of this study is to investigate the relationship between the diameter of the truncus pulmonalis and hospitalization, length of hospital stay, and mortality in patients diagnosed with PH. Demographic characteristics, number of Emergency Department (ED) admissions, post-admission status, treatment, truncus pulmonalis diameter, and mortality were evaluated statistically through the patient files of 115 PH patients who presented to the ED of Fırat University Faculty of Medicine,Elazığ, Türkiye, between January 2022 and December 2022. Of the 115 PH patients who came to the ED, 70 (60.8%) were women and 45 (39.2%) were men, with a mean age of 78.77±8.72 years. Fifty-one of these patients were discharged from the ED after treatment, and 64 were hospitalized. The mean length of hospital stay was two (min=0, max=38) days. Thoracic CT scans demonstrated that the mean diameter of the truncus pulmonalis of the patients was 34.874±3.288 mm (35.20±3.6509 mm in women, 34.367±2.5836 mm in men; p₌0.351) and there was no statistically significant relationship with mortality (p=0.496), hospitalization (p=0.806), and length of hospital stay (p=0.416). There was a statistically significant relationship between mortality rate and male gender (p=0.02) and comorbidity (p=0.001). It was determined that there was no statistically significant relationship between the truncus pulmonalis diameter and gender, comorbidity, hospitalization, length of hospital stay, and mortality in this study in which single-centre one-year admissions of PH, which differ in aetiology, epidemiology, and demographic features were examined. However, among the patient demographics, a significant relationship was determined between gender and the number of comorbidities and mortality.

Diagnosis of sarcopenia on thoracic computed tomography and its association with postoperative survival after anatomic lung cancer resection

Computer tomography-derived skeletal muscle index normalized for height in conjunction with muscle density enables single modality-based sarcopenia assessment that accounts for all diagnostic criteria and cutoff recommendations as per the widely accepted European consensus. Yet, the standard approach to quantify skeletal musculature at the third lumbar vertebra is limited for certain patient groups, such as lung cancer patients who receive chest CT for tumor staging that does not encompass this lumbar level. As an alternative, this retrospective study assessed sarcopenia in lung cancer patients treated with curative intent at the tenth thoracic vertebral level using appropriate cutoffs. We showed that skeletal muscle index and radiation attenuation at level T10 correlate well with those at level L3 (Pearson’s R = 0.82 and 0.66, p < 0.001). During a median follow-up period of 55.7 months, sarcopenia was independently associated with worse overall (hazard ratio (HR) = 2.11, 95%-confidence interval (95%-CI) = 1.38–3.23, p < 0.001) and cancer-specific survival (HR = 2.00, 95%-CI = 1.19–3.36, p = 0.009) of lung cancer patients following anatomic resection. This study highlights feasibility to diagnose sarcopenia solely by thoracic CT in accordance with the European consensus recommendations. The straightforward methodology offers easy translation into routine clinical care and potential to improve preoperative risk stratification of lung cancer patients scheduled for surgery.

Elastofibroma dorsi’de BT bulguları: tek merkezli bir çalışmad

Aim: Elastofibroma dorsi (ED) is a benign pseudotumor detected by CT and/or MRI due to the penetration of fibrous and fatty tissues between the muscle structures and is more common in elderly people, especially in women, with subscapular topography. This study investigated the prevalence of elastofibroma dorsi in large series and CT findings.&#x0D; Material and Methods: A total of 469 patients (212 women, 257 men) who underwent thoracic CT for various reasons were included in this study. The presence, dimensions, contour and density of ED were investigated in these patients.&#x0D; Results: The mean age of 469 patients was 54.51±17.42 (18-88 years). Elastofibroma was detected in 15.4% (n=72) of these patients. It was determined that 69.9% (n=51) of the patients with ED were female, and the mean age of these patients was 63.21±15.72. ED was usually isodense in both sexes. Again, in both sexes, ED was more regularly contoured, and the fat planes between adjacent muscle structures were usually closed.&#x0D; Conclusion: Additional studies are not required when the lesion is typical and asymptomatic on CT scans. However, surgical treatment may be recommended if the lesion is symptomatic or if doubt remains regarding the benign nature of the lesion.

Diagnostic accuracy of imaging compared to histology in congenital lung malformations

IntroductionThe aim of this study was to evaluate the accuracy of imaging tests (prenatal ultrasound [US] and postnatal computed tomography [CT]) in comparison to histology for diagnosis of congenital lung malformations (CLMs). Material and methodsRetrospective study of patients with a prenatal diagnosis of CLM whose postnatal follow-up included thoracic CT scan and histological examination of the lesion. We collected data on demographic variables, gestational age at diagnosis, US findings and the history of multiple gestation. We used the kappa coefficient to determine the level of agreement between the findings of prenatal US and postnatal tests (CT and histology).We analysed paired data on the size of the lesion, its location and the presence or absence of systemic arterial vascularization. ResultsThe sample included 56 patients with 57 lesions. The mean gestational age at diagnosis was 22.42 weeks (SD, 3.94) and 57% were male. Malformations most frequently involved the left lung and the lower lobes. The agreement between CT and histology in the detection of cystic lesions was moderate (κ = 0.55) but stronger compared to the agreement between US and histology (κ = 0.10). The agreement between CT and histology was substantial (κ = 0.66) in the detection of systemic vascularization of the lesion and stronger compared to the agreement between US and histology. Both imaging methods were highly accurate in the identification of the location of the pulmonary lesions. Conclusionspostnatal CT offers a substantial concordance with histological findings, especially in the detection of systemic vascularization, and an accurate prediction of the anatomy of the lesion.

Prevalence of Adrenal Incidentaloma by Chest Computed Tomography in Patients with a Preliminary Diagnosis of COVID-19 Pneumonia

Aim: Adrenal incidentalomas are typically discovered as an incidental finding during routine computed tomography (CT) or magnetic resonance imaging (MRI) scans conducted for unrelated purposes. Our objective was to examine the frequency of adrenal incidentaloma, in individuals who underwent thoracic CT scan as a result of Covid-19 infection.&#x0D; Material and Methods: In the retrospective descriptive study, 808 patients who applied to the emergency radiology department with the suspicion of covid 19 and underwent thoracic CT between March 2020 and July 2020 were included. The presence of incidentaloma in the CT images of the patients was evaluated.&#x0D; Results: Adrenal incidentaloma was detected in 78 (9.7%) of the 808 patients, and of those 78 adrenal incidentalomas, 70 (8.7%) were unilateral and 8 (1%) were bilateral. The mean diameter of the adrenal incidentaloma was 20 mm, and it was 18.5 mm in females and 21.5 mm in males. A total of 808 patients, 351 (43.4%) females and 457 (56.6%) males, were included in the study.&#x0D; Conclusion: Adrenal incidentaloma have become more common radiological findings with the recent COVID-19 pandemic due to the increased frequency of CT scans, and it is important to appropriately manage these patients.

Assessment and comparison of radiation dose and cancer risk in thoracic diagnostic and radiotherapy treatment planning CT scans

PurposeThis study intends to compare the radiation doses and cancer induction risks from thoracic diagnostic CT (DG-CT) and radiotherapy treatment planning CT (RP-CT) scans. Material and methodsA cross-sectional study on two groups of patients who underwent thoracic CT scans with RP-CT (n = 100) and DG-CT (n = 100) was conducted. The characteristics of the two groups, including age, weight, height, and body mass index were almost similar. To calculate organ and effective doses in a standard 70 kg phantom, the volume CT Dose Index (CTDIv) and dose-length product (DLP) were recorded and utilized with the ImPACT CT Patient Dosimetry Calculator. Patient-specific organ and effective doses were acquired by applying a weight-based correction factor. The lifetime attribute risk (LAR) of cancers was estimated according to the method proposed in Biological Effects of Ionizing Radiation (BEIR VII) which considers age and sex differences. ResultsThe mean ± standard deviation values of CTDIv, DLP, and effective dose were 12.19 ± 3.49 mGy, 568.68 ± 109.42 mGy cm, and 11.46 ± 2.07 mSv for RP-CT, respectively. For DG-CT, these values were 12.33 ± 3.37 mGy, 372.46 ± 99.57 mGy cm, and 7.65 ± 2.07 mSv, respectively. In males, the mean ± SD of cancer incidence risk of all cancers, all solid, and leukemia were 34.57 ± 18.91, 28.79 ± 16.74, 5.77 ± 2.28 per 100,000 individuals, respectively, for DG-CT. These values were 50.77 ± 14.53, 42.37 ± 12.81, and 9.09 ± 1.67 per 100,000 individuals, respectively, for RP-CT. In the female patients, the mean ± SD of cancer incidence risk of all cancers, all solid, and leukemia were 55.04 ± 31.64, 50.77 ± 14.53, 4.32 ± 1.26 per 100,000 individuals, respectively, for DG-CT. These values for RP-CT were 85.46 ± 30.10, 73.49 ± 26.12, and 6.97 ± 1.69 cancers per 100,000 individuals, respectively. ConclusionCancer incidence and mortality risks for RP-CT were higher than for DG-CT scans, highlighting the need for greater optimization of exposure parameters. For individuals, particularly young female patients, the advantages of CT imaging must be balanced against the risks of radiation.

Presumed residual thymic tissue is a common finding in thoracic computed tomography in adult dogs.

Residual thymic tissue is a common incidental finding in thoracic CT of human adults. To determine whether presumed residual thymic tissue is also a common incidental finding in adult dogs, a two part-study was performed. The first part was a prospective, descriptive design where CT examination was performed in six canine cadavers within 24h after death and presumed residual thymic tissue was examined pathologically. The second part of the study was a retrospective, analytical design where medical records of our institution were searched for thoracic CT scans of adult dogs performed in the year 2020. Age, sex, breed, presence of presumed thymic tissue, location, shape, attenuation, homogeneity, and width of the tissue were recorded and comparisons were performed using these data. In 4 of 6 of the prospective cases, thymic tissue was present on histology and in 2 of 6 dogs the presence of thymic tissue could not be confirmed. For the retrospective study, in 161/169 (95.3%) cases with presumed residual thymic tissue were detected. Shape and size were highly variable with either homogeneous (46.6%), heterogeneous (42.9%), or mixed (10.6%) attenuation. Dogs with presumed residual thymic tissue were significantly younger (median: 9.1 years; range: 1.2-14.3 vs. median: 10.5 years; range: 9.4-12.3) as were dogs with homogeneous attenuation of the tissue (median: 8.1 years; range: 1.2-14.3 vs. median: 9.5 years; range: 4.0-14.3). In conclusion, results indicated that presumed residual thymic tissue is a common CT findingin adult dogs and can be considered incidental.

Diagnostic Role of Bronchoscopic Brush Biopsy Guided by Thin-Section Computed Tomography in Peripheral Pulmonary Lesions

Objective: The diagnosis of peripheral pulmonary lesions (PPLs) is important as they may be malignant. It is difficult to diagnose PPLs in the absence of a diagnostic guiding tool. Computed tomography (CT) thin-section multiplanar reconstruction (MPR) images have been used as an alternative guide for bronchoscopic diagnosis of PPL. In this study, we aimed to investigate the diagnostic efficacy of MPR image guidance for PPL. Methods: Patients with PPL who underwent bronchoscopic brush biopsy guided by thoracic CT thin-section MPR images at our center were retrospectively reviewed. The distance of the lesion to the distal bronchus, the presence of the CT-Bronchus sign, the location of the PPL, and the size of the PPL were recorded from the hospital image record archive. The diagnosis rate was obtained from the procedure records. Results: The study included 92 cases. The mean PPL size was 40 ± 21 mm and the mean distal bronchial lesion distance was 27 ± 19 mm. A total of 49 (53.3%) patients had a positive CT-Bronchus sign. The diagnostic yield of the method was 48.9%. The diagnosis rate was significantly higher in patients with positive CT-Bronchus sign (67.3%) compared to those without (26.7%) (P = 0.001). Factors affecting the diagnosis in the logistic regression analysis were distal bronchial lesion distance, presence of CT-Bronchus sign,and localization of the lesion. Conclusion: CT thin-section MPR images can be used for bronchoscopy guidance in cases with PPL larger than 20 mm and positive CT-Bronchus sign in centers where an interventional radiology unit and other guidance tools are not available.

Texture and Radiomics inspired Data-Driven Cancerous Lung Nodules Severity Classification

In the process of developing artificial consciousness to mimic human intelligence, situational decision making, and self realization, steadfast progress has been noted in the field of machine learning. The machine learning with its advantages of accommodating small dataset in the training of models accounts for its necessity in practical life. The inherent information deeply ingrained in the sea of data is extracted via radiomics and 2D texture analysis that constitutes the feature set to model the framework of the algorithm for classification, and is named as texture and radiomics features based severity classification (TRFSC). In the process, thoracic CT scans of 1018 patients in LIDC-IDRI dataset are considered for the classification of benign and malignant lung nodules. The image and annotated tumor mask information are used to extract volumetric and 2D weighted reconstructed image features. The estimated 71 features of each subject are utilized to construct the best classification model using SVM, LDA, linear regression, KNN, Bayes, and boosted trees classifiers. The performance of the classifiers are evaluated using accuracy, specificity, sensitivity, and AUC metrics. This work achieves accuracy of 0.913, specificity of 0.92, sensitivity of 0.90, and AUC of 0.96 for the SVM classifier when compared with other different classifiers. The application of various parametric values in the process of feature extraction and discrimination of classes, provides the flexibility to choose the best possible model for classification purposes. The proposed method is compared quantitatively with other classification algorithms on the ground of performance to showcase its applicability and relevance as a classification algorithm to discriminate the two benign and malignant categories.

FRI248 A Case of Cyclic Cushing’s Disease With No Peripheral ACTH Response But A Marked Inferior Petrosal Sinus ACTH Response After Desmopressin Administration

Abstract Disclosure: M. Guay-Gagnon: None. R. Cheng: None. N. Younes: None. A. La Fontaine: None. S. Larose: None. É. Thérasse: None. C. Beauregard: None. A. Lacroix: None. Background: Desmopressin is commonly used for the diagnosis of Cushing’s disease (CD) especially when CRH is unavailable. We report a case of CD with no peripheral ACTH response but with an unexpectedly marked ACTH and prolactin (PRL) response in inferior petrosal sinus sampling (IPSS) performed with desmopressin. Following failure of pituitary surgery, cabergoline was introduced, which rapidly induced central adrenal insufficiency (AI). Case Report: A 32-y.o. man was referred to our center for Cushing’s syndrome (CS). Over the last years he had developed diabetes, hypertension, hypokalemia, osteoporosis, obesity, and an overt Cushingoid appearance. Morning cortisol was variable with values up to 8065 nmol/L (292 μg/dL) with elevated ACTH of 63 pmol/L (285 pg/mL). The 1 mg dexamethasone suppression test (DST), 24-hour urinary free cortisol (up to 422 x ULN) and bedtime salivary cortisol (up to 74 x ULN) were elevated. The 4 mg IV DST showed partial cortisol suppression, but a very elevated value of 3750 nmol/L (136 μg/dL) the following morning. Desmopressin (10 mcg IV) stimulation test showed no response: ACTH went from 3.8 pmol/L (17.3 pg/mL) to 3.9 pmol/L, and cortisol, from 688 nmol/L (25 μg/dL) to 622 nmol/L. Pituitary MRI, thoracic CT and DOTATATE PET/CT identified no lesion; abdominal CT showed bilateral adrenal hyperplasia. IPSS with desmopressin stimulation identified a pituitary origin with central/peripheral (C/P) ACTH ratios that rose from 7.1 to 34.2 on the left. PRL increased by 83% in left IPSS after desmopressin, while peripheral ACTH and PRL remained stable. During pituitary exploration, the surgeon suspected a tumor on the left, but pathology showed normal pituitary tissue. Hypercortisolism persisted with partial DI requiring oral desmopressin, and cabergoline 0.5 mg twice weekly was initiated. Two weeks later, he was admitted with nausea, vomiting, lethargy, hypotension, hyponatremia, hyperkalemia and a negative septic evaluation. Morning cortisol was 233 nmol/L (8.4 μg/dL), abnormally low in this context. His condition resolved with IV hydrocortisone and fluid resuscitation. ACTH was not measured initially but was 2 x ULN a few weeks later and 4 mg IV DST showed an early cortisol and ACTH rebound. In view of recurrent hypercortisolism, the patient underwent bilateral adrenalectomy resulting in rapid clinical remission. Under hydrocortisone replacement, his most recent ACTH was 21 pmol/L. Conclusions: This is the first report of a petrosal sinus ACTH response to desmopressin without any peripheral response, suggesting a central source of ACTH. Thus, the use of desmopressin during IPSS should still be attempted in patients with no prior peripheral response. It is unclear whether the acute AI episode was due to a combination of nadir of cyclic CD or partial apoplexy and response to cabergoline of a residual corticotroph tumor with desmopressin induced prolactin co-secretion. Presentation: Friday, June 16, 2023

Cavitary pulmonary lesion wall thickness, presence of additional nodules, and intralesional contrast enhancement are associated with malignancy in dogs and cats.

To investigate the CT features of cavitary pulmonary lesions and determine their utility to differentiate malignant from benign lesions. This retrospective study included cases from 5 veterinary medical centers between January 1 2010, and December 31, 2020. Inclusion criteria included having a gas-filled cavitary pulmonary lesion on thoracic CT and definitive diagnosis by either cytology or histopathology. Forty-two animals (27 dogs and 15 cats) were included in this study. Medical records systems/imaging databases were searched, and cases meeting inclusion criteria were selected. The CT studies were interpreted by a third-year radiology resident, and findings were reviewed by a board-certified veterinary radiologist. 7 of the 13 lesion characteristics investigated were not statistically associated with the final diagnosis of the lesion, whereas 6 were statistically associated. Those that were associated included the presence of intralesional contrast enhancement, type of intralesional contrast enhancement (heterogenous and homogenous analyzed separately), presence of additional nodules, wall thickness of the lesion at its thickest point, and wall thickness at the thinnest point. Results from the present study showed that thoracic CT imaging of cavitary pulmonary lesions can be used to further refine the list of differential diagnoses. Based on this data set, in lesions that have heterogenous contrast enhancement, additional pulmonary nodules, and wall thickness > 40 mm at their thickest point, it would be reasonable to consider malignant neoplastic disease higher on the list of differentials than other causes.

Establishment of Radiation Dose Reduction Criteria for Thoracic and Abdominal CT via Systematic Spatial Resolution Evaluation

With the development of various reconstruction algorithms for CT imaging, it has become possible to perform low-dose CT examinations without compromising image quality. However, quantitative evaluation such as image noise, signal-to-noise ratio (SNR), and contrast-tonoise ratio (CNR) have been mainly used yet, while the spatial resolution and overall image quality rely on subjective assessment. Therefore, this study aimed to propose a quantitative method for evaluating spatial resolution in chest and abdominal CT scans, in order to facilitate dose reduction. For this study, a phantom was fabricated using 3D printing and scanned under chest and abdominal imaging conditions, with additional scans performed under low-dose conditions. The peak, bottom, FWHM, DFWHM, and peak-bottom were compared and analyzed. The results showed no statistically significant differences in spatial resolution parameters between all chest and abdominal protocol, with FWHM and DFWHM indicating the same distance. Even if the dose is reduced to 30 mAs in the chest CT condition and to 50 mAs in the abdominal CT condition, there will not be a big problem in terms of spatial resolution. Lastly, the indices from this study demonstrate potential as objective measures of spatial resolution when applying low-dose CT protocols.

Use of ionizing radiation in a Norwegian cohort of children with congenital heart disease: imaging frequency and radiation dose for the Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) study

BackgroundThe European-funded Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) project is a multicenter cohort study assessing the long-term effects of ionizing radiation in patients with congenital heart disease. Knowledge is lacking regarding the use of ionizing radiation from sources other than cardiac catheterization in this cohort.ObjectiveThis study aims to assess imaging frequency and radiation dose (excluding cardiac catheterization) to patients from a single center participating in the Norwegian HARMONIC project.Materials and methodsBetween 2000 and 2020, we recruited 3,609 patients treated for congenital heart disease (age < 18 years), with 33,768 examinations categorized by modality and body region. Data were retrieved from the radiology information system. Effective doses were estimated using International Commission on Radiological Protection Publication 60 conversion factors, and the analysis was stratified into six age categories: newborn; 1 year, 5 years, 10 years, 15 years, and late adolescence.ResultsThe examination distribution was as follows: 91.0% conventional radiography, 4.0% computed tomography (CT), 3.6% diagnostic fluoroscopy, 1.2% nuclear medicine, and 0.3% noncardiac intervention. In the newborn to 15 years age categories, 4–12% had ≥ ten conventional radiography studies, 1–8% underwent CT, and 0.3–2.5% received nuclear medicine examinations. The median effective dose ranged from 0.008–0.02 mSv and from 0.76–3.47 mSv for thoracic conventional radiography and thoracic CT, respectively. The total effective dose burden from thoracic conventional radiography ranged between 28–65% of the dose burden from thoracic CT in various age categories (40% for all ages combined). The median effective dose for nuclear medicine lung perfusion was 0.6–0.86 mSv and for gastrointestinal fluoroscopy 0.17–0.27 mSv. Because of their low frequency, these procedures contributed less to the total effective dose than thoracic radiography.ConclusionThis study shows that CT made the largest contribution to the radiation dose from imaging (excluding cardiac intervention). However, although the dose per conventional radiograph was low, the large number of examinations resulted in a substantial total effective dose. Therefore, it is important to consider the frequency of conventional radiography while calculating cumulative dose for individuals. The findings of this study will help the HARMONIC project to improve risk assessment by minimizing the uncertainty associated with cumulative dose calculations.Graphical

Clinical Outcomes of Synchronous Lung Stereotactic Body Radiation Therapy Lesions via Single-Isocenter/Multi-Lesion Treatments

Lung cancer patients with synchronous primary or oligometastatic (< 5 lesions) with associated co-morbidities may not retain their treatment position for the extended stereotactic body radiotherapy (SBRT) treatment times with individual isocenter plans for each lesion due to discomfort or shortness of breath. SBRT using a single-isocenter/multi-lesion (SIML) volumetric arc therapy (VMAT) plan with flattening filter free (FFF) beam could significantly shorten overall treatment time, improve patient comfort and compliance and clinic efficiency. We report clinical results of treating multiple lung metastases or synchronous primary lung cancers with SIML lung SBRT. Eighty patients with synchronous primary lung cancers or oligometastatic lung tumors (two, n = 61; three, n = 10; four, n = 4; five n = 5; total treated lesions, n = 193) were simulated with abdominal compression and/or 4D-CT MIP images and treated with a highly-conformal SIML VMAT lung SBRT plans via 3-4 non-coplanar arcs. Common prescriptions were 50-55 Gy/5 fractions and 54 Gy/3 fractions prescribed 70-80% isodose line to the each PTV. Acuros dose calculation for 6MV-FFF beam was used for tissue heterogeneity corrections. RTOG-0618/0813 criteria were used to dose constraints to organs at risk (OAR) and target conformality. Treatment was delivered every other day or twice weekly with CBCT-guidance, adjustments made with 6DOF couch corrections on a medical linear accelerator, and treatment delivery time within 15 minutes. Local control rates and toxicity profile was evaluated using CTCAE v. 5.0 grading for pneumonitis, rib fracture and chest wall pain. All plans met RTOG-0618/0813 requirements for each tumor coverage, dose to OAR including normal lung and ribs. Mean follow up after last fraction of treatment was 16.9 months (range, 1.0-54.2 months). PTV volume ranged from 2.17 to 167.8 cc with mean volume of 16.1 cc. Of the 80 patients treated, 71 had adequate post-treatment thoracic CT imaging to assess local control. Local control was achieved in 167/175 (95.4%) of treated and followed lesions. CTCAE grade 1 asymptomatic pneumonitis was noted on thoracic CT scans in 42/71 (59.2%) of patients and occurred, on average 4.8 months after SBRT. Symptomatic pneumonitis and rib fracture did not occur in any patient. CTCAE grade 2 chest wall pain occurred in 4/80 (5.0%) treated patients and was managed conservatively with over-the-counter NSAIDS or acetaminophen. SIML lung SBRT for synchronous primary lung cancers or multiple lung metastases can be used as a variant to traditional multiple isocenter SBRT or chronologically separate treatment courses, and has excellent local control rates and low toxicity profile in our patient population. It can help improve comfort and compliance of the patients who have difficulty lying still for an extended treatment course, and significantly reduces treatment time via isocenter shifts/repeated CBCTs for image guidance, thus improving clinic efficiency.

B-245 Applicability of metagenomic Next-Generation Sequencing (mNGS) in challenging infectious diseases in a tertiary hospital

Abstract Background Infectious diseases caused by rare pathogens or with unusual presentations pose a diagnostic challenge. Traditional microbiologic tests can be time-consuming, labor-intensive and have limited sensitivity for some organisms. Plasma metagenomic Next-Generation Sequencing (mNGS) detects whole microbial genetic material and detects even unsuspected organisms. We present three cases of challenging infectious diseases and discuss the applicability of mNGS in different scenarios. Methods Plasma NGS was performed at Karius, Inc. (Redwood City, CA, USA). Patient data was collected from hospital and laboratory electronic records. Results Case 1: An 8-year-old female with sickle-cell anemia developed a persistent daily fever two weeks after recovery from sepsis due to Streptococcus pyogenes. Clinical exam was normal and investigation was negative (blood cultures, echocardiogram, thoracic and abdominal CT scans and bone scintigraphy). Two weeks later mNGS was performed, which came out positive for Cytomegalovirus. As patient became afebrile in 48 h and the viral burden was low, she could be safely discharged. Case 2: A 43-year-old male with prosthetic aortic valve and an intraluminal aortic ring had a year-long history of fatigue, weight loss and hypoalbuminemia. CT scans showed ground-glass infiltrates and enlarged mediastinal lymph nodes. Empirical treatment for tuberculosis was ineffective. A year later, he developed hepatosplenomegaly, fever and pancytopenia. Blood cultures, bone marrow biopsy and serologies (HIV, hepatitis B/C, syphilis, brucellosis, bartonellosis, leishmaniasis) were negative. Cardiac surgery found no apparent signs of endocarditis and the prosthetic aortic valve biopsy revealed only an inflammatory infiltrate. A new CT scan showed thickened intraluminal aortic ring with aortic pseudoaneurysms and splenomegaly with splenic infarction. A blood sample was then collected for mNGS and liver biopsy and splenectomy were performed. However, surgery complicated with hemodynamic instability, renal and liver failure and the patient died in less than 24 h. Two days later, mNGS came out positive for Coxiella burnetti. Case 3: A 45-year-old female with relapsed AML treating a chronic disseminated candidiasis with micafungin for 3 months had persistent liver and splenic nodules and new pulmonary nodules on the CT scan. In the following three months after chemotherapy (Gilteritinib), she developed multiple episodes of febrile neutropenia, some without microbiological documentation, leading to multiple courses of antibiotic treatment and a shift to liposomal amphotericin B. After clinical improvement and bone marrow recovery, liposomal amphotericin B was replaced by isavuconazole. A negative mNGS result allowed antifungal treatment to be safely discontinued, avoiding six months of unnecessary antifungal treatment. Conclusion We summarize three different scenarios of mNGS applications. In common, patients were submitted to multiple laboratory and image testing and received large doses of empirical antimicrobials due to lack of a precise diagnosis. In two cases, mNGS was diagnostic, shortened hospital stay and reduced overall costs. In case 2, the patient’s death might have been prevented if mNGS had been performed earlier. Vulnerable hospitalized patients with a broad spectrum of diagnostic possibilities, in whom sequential diagnostic tests could delay adequate therapy and cause significant adverse effects, could greatly benefit from mNGS when performed in a timely manner.

Change in diaphragmatic morphology in single-lung transplant recipients: a computed tomographic study.

Introduction: The influence of lung disease on the diaphragm has been poorly studied. The study aimed to evaluate the diaphragm morphology (height and thickness) in single-lung transplantation (SLTx), using computed tomography (CT), by assessing the evolution of the hemidiaphragm of the transplanted and the native side. Methods: Patients who underwent single lung transplantation in our center (Marseille, France) between January 2009 and January 2022 were retrospectively included. Thoracic or abdominal CT scans performed before and the closest to and at least 3months after the surgery were used to measure the diaphragm crus thickness and the diaphragm dome height. Results: 31 patients mainly transplanted for emphysema or pulmonary fibrosis were included. We demonstrated a significant increase in diaphragm crus thickness on the side of the transplanted lung, with an estimated difference of + 1.25mm, p = <0.001, at the level of the celiac artery, and + 0.90mm, p < 0.001, at the level of the L1 vertebra while no significant difference was observed on the side of the native lung. We showed a significant reduction in the diaphragm height after SLTx on the transplanted side (-1.20cm, p = 0.05), while no change on the native side (+0.02cm, p = 0.88). Conclusion: After a SLTx, diaphragmatic morphology significantly changed on the transplanted lung, while remaining altered on the native lung. These results highlights that an impaired lung may have a negative impact on its diaphragm. Replacement with a healthy lung can promote the recovery of the diaphragm to its anatomical morphology, reinforcing the close relationship between these two organs.

Long-Term Radiological Pulmonary Changes in Mechanically Ventilated Patients with Respiratory Failure due to SARS-CoV-2 Infection.

From the first reports of SARS-CoV-2, at the end of 2019 to the present, the global mortality associated with COVID-19 has reached 6,952,522 deaths as reported by the World Health Organization (WHO). Early intubation and mechanical ventilation can increase the survival rate of critically ill patients. This prospective study was carried out on 885 patients in the ICU of Mureș County Clinical Hospital, Romania. After applying inclusion and exclusion criteria, a total of 54 patients were included. Patients were monitored during hospitalization and at 6-month follow-up. We analyzed the relationship between invasive mechanical ventilation (IMV) and non-invasive mechanical ventilation (NIMV) and radiological changes on thoracic CT scans performed at 6-month follow-up and found no significant association. Regarding paraclinical analysis, there was a statistically significant association between patients grouped by IMV and ferritin level on day 1 of admission (p = 0.034), and between patients grouped by PaO2/FiO2 ratio with metabolic syndrome (p = 0.03) and the level of procalcitonin (p = 0.01). A significant proportion of patients with COVID-19 admitted to the ICU developed pulmonary fibrosis as observed at a 6-month evaluation. Patients with oxygen supplementation or mechanical ventilation require dynamic monitoring and radiological investigations, as there is a possibility of long-term pulmonary fibrosis that requires pharmacological interventions and finding new therapeutic alternatives.