High-resolution Computed Tomography Scans Research Articles

Performance of high-resolution CT for detection and discrimination tasks related to stenotic lesions - A phantom study using model observers.

Accurate detection and grading of atheromatous stenotic lesions within the cardiac, renal, and intracranial vasculature is imperative for early recognition of disease and guiding treatment strategies. In this work, a stenotic lesion phantom was used to compare high resolution and normal resolution modes on the same CT scanner in terms of detection and size discrimination performance. The phantom is comprised of three acrylic cylinders (each 15.0cm in diameter and 1.3cm thick) with a matching array of holes in each module. The outer two modules contain holes that are slightly larger than the corresponding hole in the central module to simulate stenotic narrowing in vasculature. The stack of modules was submerged in an iodine solution simulating contrast-enhanced stenotic lesions with a range of lumen diameters (1.32-10.08mm) and stenosis severity (0%, 50%, 60%, 70%, and 80%). The phantom was imaged on the Canon Aquilion Precision high-resolution CT scanner in high-resolution (HR) mode (0.25mm × 0.50mm detector element size) and normal-resolution (NR) mode (0.50mm × 0.50mm) using 120 kV and two dose levels (14 and 21mGy SSDE) with 30 repeat scans acquired for each combination. Filtered back-projection (FBP) and a hybrid-iterative reconstruction (AIDR) were used with the FC18 kernel, as well as a deep learning algorithm (AiCE) which is only available for HR. A non-prewhitening model observer with an eye filter was implemented to quantify performance for detection and size discrimination tasks in the axial plane. Detection performance improved with increasing diameter, dose, and for AIDR in comparison to FBP for a fixed resolution mode. Performance in the HR mode was generally higher than NR for the smaller lumen diameters (1-5mm) with decreasing differences as the diameter increased. Performance in NR mode surpassed HR mode for lumen diameters greater than ∼4mm and ∼5mm for 14mGy and 21mGy, respectively. AiCE provided consistently higher detection performance compared with AIDR-FC18 (48% higher for a 6mm lumen diameter). Discrimination performance increased with increasing nominal diameter, dose, and for larger differences in stenosis severity. When comparing discrimination performance in HR to NR modes, the largest relative differences occur at the smallest nominal diameters and smallest differences in stenosis severity. The AiCE reconstruction algorithm produced the highest overall discrimination performance values, and these were significantly higher than AIDR-FC18 for nominal diameters of 7.14 and 10.08mm. HR mode outperforms NR for detection up to a specific diameter and the results improve with AiCE and for higher dose levels. For the task of size discrimination, HR mode consistently outperforms NR if AIDR-FC18 is used for dose levels of at least 21mGy, and the results improve with AiCE and for the smallest differences in stenosis severity investigated (50% vs. 60%). High-resolution CT appears to be beneficial for detecting smaller simulated lumen diameters (<5mm) and is generally advantageous for discrimination tasks related to stenotic lesions, which inherently contain information at higher frequencies, given the right reconstruction algorithm and dose level.

Early Prediction and HRCT Evaluation of Post Covid-19 Related Lung Fibrosis.

Early detection of post-COVID-19-related lung fibrosis is very important for the early introduction of treatment and to minimize morbidity and mortality. The aim of this study is the early detection and evaluation of post-COVID-19 fibrosis by high-resolution computed tomography (HRCT). This prospective study included 115 patients irrespective of age and sex, who tested positive for the SARS-CoV-2 by nasopharyngeal swab (RT PCR), admitted to the Dhaka North City Corporation (DNCC) dedicated COVID-19 hospital, Dhaka, and discharged after recovery. Patients went through a chest HRCT scan at least once during their hospital stay and another scan during follow-up after hospital discharge and 8 to 12 weeks of negative RT-PCR report. Among 100 patients 23 patients had >50% of total lung involvement by visual assessment. Thirty-three patients had 25% to 50% of total lung volume involvement. Twenty-seven patients had less than 25% of total lung involvement, whereas 17 patients had no visual fibrotic change on the follow-up HRCT scan. A statistical association was found between age, gender, smoking, and severe form of lung fibrosis (P < .05). Patients with mild CT severity score (⩽8) had a very good prognosis. Patients who were admitted to the hospital for more than 15 days were more prone to developing moderate and severe forms of fibrosis. Patients who received at least 2 doses of the COVID-19 vaccine had less severe forms of fibrosis as well as more cases of complete radiological recovery. On the HRCT scan, most of the patients had bilateral, peripheral (68%), and predominant mid & lower lobar parenchymal involvement. Early detection and HRCT evaluation of post-COVID-19 related lung fibrosis is very crucial for early management and introduction of anti-fibrotic drugs.

Post-COVID acute pulmonary nocardiosis: Another novel post-COVID infection.

Dear Editor, Treatment of COVID-19 remains challenging, especially in patients with severe disease. Immunosuppressive therapies such as steroids and cytokine blockers are beneficial to control the cytokine storm. However, these drugs increase the risk of opportunistic infections. Nocardiosis is caused by an actinomycete, which primarily affects immunocompromised patients. Here we report a patient with acute localized pulmonary nocardiosis, post severe COVID disease. A 70-year-old male patient with no addictions and comorbidities presented to the emergency room with complaints of high-grade fever, cough with copious brown sputum, left-sided pleuritic chest pain for 2 weeks, and breathlessness for 3 days. He had severe COVID-19 disease with respiratory failure 4 weeks ago for which he was treated with IV remdesivir and IV methylprednisolone 40 mg twice daily for 7 days and discharged. At presentation, he had a respiratory rate of 30 breaths/min and saturation of 60% on room air, which improved to 95% with 5 liters/minute of oxygen support. Arterial blood gases (ABG) showed type 1 respiratory failure. Chest X-ray showed a consolidation in the left lower zone. High-resolution computed tomography (HRCT) chest revealed consolidation in the left lower lobe with internal breakdown and minimal pleural effusion [Figure 1a]. Total leukocyte count and C-reactive protein (CRP) were elevated (21,700 cells/mm3 and 320 mg/L, respectively). Sputum showed gram-positive, acid-fast, branching filamentous structures, morphologically resembling Nocardia species [Figure 1b, c], and hence a diagnosis of acute pulmonary nocardiosis was made. The patient was treated with oral trimethoprim-sulfamethoxazole (TMP-SMX) and IV meropenem for 4 weeks. The patient improved with treatment and was off oxygen support after a week and hence discharged. On follow-up after 3 weeks, antibiotics were changed to oral linezolid and TMP-SMX for 5 months. After completion of therapy, the patient is asymptomatic and the HRCT chest showed near-complete resolution of the left lower lobe consolidation with residual fibrotic bands [Figure 1d].Figure 1: (a) Axial slice of a high-resolution computed tomography scan of the chest showing consolidation of the left lower lobe with internal breakdown. (b) Direct examination of sputum smear after modified acid-fast staining revealing branching filamentous acid-fast organisms (40 × magnification). (c) Positive culture of the same sputum specimen on the blood agar plate. (d) Axial slice of a high resolution computed tomography scan of chest post-treatment, showing near-complete resolution with residual fibroticNocardiosis, an opportunistic infection, has been reported rarely in post-COVID-19 patients. To the best of our knowledge, there are only three case reports to date.[1,2] Nocardia species are ubiquitous saprophytic gram-positive bacteria of the “aerobic actinomycetes” group.Click or tap here to enter text.[3] The primary route of transmission is inhalational, from environmental sources. The majority of patients with pulmonary nocardiosis are immunosuppressed or have chronic lung disease. Radiology usually demonstrates irregular nodular lesions that may have cavitation. “Halo sign,” diffuse consolidations, and pleural effusions have been reported. The definitive diagnosis of nocardiosis requires isolation of the organism. Nocardia appears as a filamentous bacterium with hyphae-like branching and a “beaded” acid-fast appearance on microscopy.[4] Sulfonamides are the treatment of choice for nocardiosis. TMP-SMX is the most widely used drug. Alternative treatment options include amikacin, imipenem, meropenem, ceftriaxone, cefotaxime, minocycline, moxifloxacin, levofloxacin, linezolid, tigecycline, and amoxicillin-clavulanic acid.[3] The duration of treatment is 6–12 months. Our patient, who was otherwise healthy and had received only a short course of corticosteroids developed pulmonary nocardiosis, which suggests that it is vital to investigate for uncommon etiologies in patients presenting with secondary infections post-COVID-19 disease. COVID-19 infection apart from the drugs used in its treatment as a cause of immune suppression needs further research. Abbreviations IV – Intravenous, ABG – Arterial blood gases, HRCT – High resolution computed tomography, CRP- C-reactive protein. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Incidentalomas Discovered during COVID- 19 Chest CT Screening: A Cross-sectional Study from Andhra Pradesh, India

Introduction: The highly contagious Coronavirus Disease 2019 (COVID-19) virus has spread across the globe. For the aberrant changes in the lung parenchyma, thin-section chest Computed Tomography (CT) is more sensitive than chest radiography and can identify early disease. Increased CT usage and resolution also lead to an increase in the discovery of "incidental" findings, creating questions about additional research, diagnosis, and follow-up with associated financial and emotional costs. Aim: To evaluate the non COVID-19 lung pathologies and other system findings in High Resolution Computed Tomography (HRCT) chest done for COVID-19 screening study. Materials and Methods: This was a cross-sectional study done in the Department of Radiodiagnosis at Dr.Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, Vijayawada, Andhra Pradesh, India, from May 2021 to December 2021. The CT scan was done in a craniocaudal direction with an average exposure time of 4-6 seconds, slice thickness of 5 mm and 1.5 mm in mediastinal and lung windows. A total of 1000 HRCT scans done were examined for covid screening. Data was entered in Microsoft Excel and analysed by using Statistical Package for Social Sciences (SPSS) software. Descriptive statistics were represented with percentages. Results: A total of 348 cases were found with various other pathologies incidentally. Lesions like infectious and inflammatory lesions, metabolic diseases, tumours, metastases of various systems and fractures were found. Among 348 total cases with incidental findings 98 cases (28.1%) showed non COVID-19 lung pathologies, 114 cases (32.7%) had findings in the upper abdomen, 30 cases (8.6%) in the thyroid, and three cases (0.8%) had other findings. Conclusion: The HRCT chest screening for COVID-19 not only provided the status of pulmonary infection but gave a broad view of many other system pathologies like in upper abdomen, musculoskeletal system, thyroid, breast which were found incidentally. Identifying those pathologies and correlating them with history will help in early detection and management.

Cough, with a sac of marbles in the chest.

A 48-year-old male patient presented with productive cough, dyspnea and abdominal pain of 2 months duration. He was diagnosed with diabetes mellitus 6 months ago and had not been regular with his medications. Clinical examination revealed a respiratory rate of 18 per min with room air saturation of 95%, and a paucity of movements with bronchial breath sounds identified on inspection and auscultation, respectively, over the right hemithorax. Chest skiagram and computed tomography images of his thorax are shown below [Figure 1].Figure 1: (a) shows chest skiagram and (b–d) shows high-resolution computed tomography images of the chest. A description of the images is in the accompanying textQuestion: What is the diagnosis? Answer: Pulmonary and hepatic hydatid disease. DISCUSSION The chest skiagram [Figure 1a] revealed a well-defined round radio-opacity in the right mid zone with a crescentic hyperlucent medial margin, called the crescent sign (white arrow). Figure 1b is a coronal view of high-resolution computed tomography (HRCT) scan of the chest lung window, which shows a large cyst in the right lung, with multiple small rounded opacities with fluid attenuation, some of which appear to be floating within it, appearing like a sac of marbles. This is consistent with a diagnosis of a hydatid cyst with multiple daughter cysts within it. There are pockets of air seen between the outer pericyst and inner endocyst, aptly named ‘air-crescent sign’ (blue arrow) and ‘signet ring sign’ (red arrow), which suggest a ruptured or complicated hydatid cyst. Figure 1c, the sagittal section of the HRCT scan of the chest lung window at the level of the aortic outflow tract, shows the ruptured hydatid cyst in the right lung. The daughter cysts have collected in the dependent area of the larger cyst, with some appearing to ‘rise’ over the rest, or the ‘rising-sun sign’ (blue arrow). Also seen is a small air pocket inferiorly (red arrow) between the pericyst and endocyst, called the ‘air-bubble sign’. The presence of air on either side of the endocyst (red arrowheads) gives the appearance of an ‘onion-peel sign’, or the ‘cumbo sign’. Figure 1d shows a large well-defined homogenous cyst in the right lobe of the liver.[1] Blood investigations revealed uncontrolled blood sugar levels. Armed with the characteristic radiology above, and supplemented by a positive serum latex agglutination test for Echinococcus antigen, he was diagnosed with pulmonary and hepatic hydatid disease. He was started on oral albendazole and subsequently underwent pericystectomy of lung cyst along with partial pericystectomy of cyst in the liver. Post-surgery, he is at present asymptomatic and is on regular follow-up. Hydatid disease is a zoonosis, commonly caused by the accidental ingestion of ova of the tapeworm Echinococcusgranulosus, which subsequently develop into larvae in the host intestine and migrate to other parts of the body where they develop into embryos, with the liver and lung being the most commonly involved organs.[1] Characteristic thoracic radiology should lead clinicians to suspect pulmonary hydatid disease, especially when dealing with patients with non-resolving pneumonia or lung mass. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Descriptive study of the role of ultrasound in the evaluation of patients with interstitial lung disease associated with autoimmune connective tissue disorders

Background and Aim: High-resolution computed tomography (HRCT) of the chest has been the conventionally accepted modality of radiological investigation utilized in the evaluation and management of interstitial lung diseases (ILDs). The aim of this study was to compare the utilization of lung ultrasound (LUS) as a radiological modality versus HRCT scan of the chest, in the diagnosis of cases of ILD in autoimmune connective tissue disease (AICTD) patients at a tertiary care center in Northern India. Methods: In this descriptive study, 42 consecutive diagnosed cases of AICTD with clinical risk of ILD were included, between July 2016 and March 2019, attending the rheumatology outpatient department of CH WC. They were assessed with lung ultrasonography and HRCT chest. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of LUS were estimated considering HRCT as the reference method. Results: Of these 42 patients, 30 (71.4%) had abnormal LUS findings. HRCT findings suggestive of ILD were seen in 31 (73.8%). Considering HRCT as gold standard, LUS resulted in 01 false-positive and 02 false-negative results. Sensitivity and specificity of LUS with respect to HRCT were 93.55% and 90.91%, respectively. Positive predictive value (PPV) and negative predictive value (NPV) of LUS were calculated at 89.38% and 94.51%, respectively. In 91.6% (11/12) patients with nonspecific interstitial pneumonitis pattern on HRCT, B-lines were found to be numerous and compact (<3 mm distance between B lines). On the other hand, compact B lines were seen in only 21.1% (4/19) cases showing HRCT patterns suggestive of usual interstitial pneumonitis (UIP)/likely UIP, with a significant difference between the two (P = 0.0002). Conclusions: LUS is as nearly sensitive and specific as HRCT chest in the detection of ILD and has the distinct advantage of being without radiation exposure.

Application of finite element model of middle ear in the study of the middle ear biomechanics in normal and diseased states

Aim: The aim of this study was to create a three-dimensional model of the middle ear by finite element (FE) analysis, using measurements performed on human and cadaveric high-resolution computed tomography (HRCT) temporal bone, and to study the biomechanics in diseased conditions. Materials and Methods: This observational, cross-sectional study was conducted in Acharya Vinoba Bhave Rural Hospital, Sawangi, Meghe, Maharashtra, in the Department of Otorhinolaryngology. The first step of FE modeling approach comprised computer-aided geometric model incorporating the static dimensions from human and cadaveric temporal bones and dynamic dimensions from prepublished data. HRCT Scans of both sets of temporal bones were performed with 0.5 mm cuts, and measurements of the ossicles, middle ear, and tympanic membrane were taken. The cadaveric temporal bones were drilled, the ossicles dissected out and measured using HRCT as well as vernier calipers. This was followed by construction of the working FE model and application of this FE model for studying middle ear biomechanics in normal and diseased states. Results: The mean measurements of ossicles were calculated, and the movement of tympanic membrane was maximum at the site of umbo and stapes footplate, whereas minimum movement was within the ossicles. Larger peak-to-peak displacement was seen at 1000 Hz to 3000 Hz frequency. Our results suggest that FE model can prove beneficial in the study of middle ear biomechanics. Conclusion: The changes in the tympanic membrane movement in diseased state have been compared to normal ear and can be applied to reconstructed ears. FE analysis can be used to study the effect of material properties of various graft materials used in tympanomastoidectomy.

Salt-and-Pepper Dyspigmentation with Groove Sign in Erasmus Syndrome: A Double Jeopardy.

Salt-and-Pepper Dyspigmentation with Groove Sign in Erasmus Syndrome: A Double Jeopardy.

Thalidomide for the Treatment of COVID-19 Pneumonia: A Randomized Controlled Clinical Trial.

Coronavirus disease 2019 has become a public health concern with a high number of fatalities. Thalidomide can target inflammatory mediators and decrease inflammation in SARS-CoV-2. An open-label, randomized controlled trial was conducted on patients with compatible lung high-resolution computed tomography scan for COVID-19 pneumonia and moderate involvement. Childbearing-age women were excluded. A total of 20 patients in the control group receiving usual treatment were compared with 26 patients in the case group who in addition to the same regimen also received thalidomide. The primary outcome was time for clinical recovery (TTCR) and intensive-care unit (ICU) admission. From April 25 to August 8, 2020, based on the inclusion criteria, 47 patients were assigned to the study. Patients receiving thalidomide had a mean TTCR of days 5.5 (95% confidence interval [CI], 0.7-10.3), as compared with days 5.3 (95% CI, 1.7-8.9) with control (odds ratio 0.01; 95% CI, -1.58-1.59, P = 0.807). The incidence of ICU admission was 27% in the thalidomide group compared with 20% in the control group (odds ratio 3.89; 95% CI, 0.55-27.4, P = 0.425). The mean length of stay in hospital in both groups was 10 days. Progressive improvement in respiratory rate, fever, and O2 saturation during the study was seen in both groups without a significant difference between the thalidomide and control group (P > 0.05). This study investigated the effects of thalidomide to treat moderate COVID-19 clinical outcomes. The results established that this drug regimen did not add more effect to usual treatment for moderate COVID-19 pneumonia.

Better specificity and less ischemia: three-dimensional reconstruction is superior to routine computed tomography angiography in navigation of super-selective clamping robot-assisted laparoscopic partial nephrectomy.

Available technologies could be used to guide surgeons in controlling highly selective tumor-bearing arteries robot-assisted laparoscopic partial nephrectomy (RALPN). Patients undergoing RALPN (from September 2018 to January 2020) for intermediate-high complex renal tumor (R.E.N.A.L. score ≥7) who underwent abdominal computed tomography (CT) scan with angiography and hyper-accuracy 3-dimensional reconstruction (H3DR). All patients underwent high-resolution CT scan with angiography and H3DR with special software, based on which two kinds of highly selective arterial clamp protocols were made for each patient and analyzed independently by two urologists and two radiologists to confirm which renal arterial branch was supplying the tumor. We chose the optimized clamping protocol with the principle of the minimized ischemic regions. During the operation, meticulous microdissection and clip ligation of the specific vascular branch was guided by optimized protocol [H3DR or computed tomography angiography (CTA) reconstruction], according to the in vivo anatomy (identified by intraoperative ultrasound). Of 82 patients, the minimum-ischemic regions planning completed rate (MIRPCR) of preoperative planning with H3DR (90.2%) was higher than that with CTA (34.1%) (P<0.01). H3DR identified 78 high-order arteries (70.3%), whereas CTA identified 33 (29.7%) high-order arteries (P<0.001). H3DR detected a more optimal blocking option in 51 cases that were either missed (n=13) or misclassified by CTA (n=38). A total of 18 cases (56.3%) were converted to H3DR-guided occurred in CTA-guided surgery [5 (10.0%) occurred in group H3DR to CTA, P<0.01]. Moreover, in the CTA-guided group, the separation of renal hilum was avoided in 14 of 19 (73.7%) cases, whereas in the H3DR-guided group, it was avoided in 60 of 63 (95.3%) cases. For patients undergoing RALPN, H3DR-guided surgery compared with standard CTA-guided surgery has higher accuracy and feasibility in controlling arterial branches supplying the tumor and intraoperative surgical navigation. Additionally, it reduces the ischemic lesion area and simplifies vascular isolation steps, thus decreasing procedural difficulty.

Quality of Thorax CT Scan Images among Covid-19 Cases using Variations of Filter

A typical image of the Thorax CT Scan as a sign of the early stages and development of Covid-19 is the finding of Ground Glass Opacities (GGO). GGO is an insignificant increase in the density of the lungs without occlusion of blood vessels and bronchi. In mild cases, GGO tends to be difficult to identify and requires high-resolution CT scanning. In this study, we intend to improve the resolution of the Thorax CT Scan image through filter settings, to analyze the difference in the variations of filters B50s, B70s, and B90s towards the quality of the CT Scan image and obtain the optimal use of filter in the Thorax CT Scan examination among Covid-19 cases. This was a quantitative analytical study conducted at one of the Regional General Hospital in Jakarta on March-April 2022. The samples were secondary data derived from 10 patients by using MSCT Siemens Somatom Perspective 128 slices. Data were collected through observation and experiment. The images collected were further analyzed using Image j software to find values of Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR). Furthermore, the values were compared by assessing the anatomical image information through various filters. The results of this study indicated that there were differences in the SNR and CNR values of the three filters. The higher resolution of the filter used, the more capable it was to sharper and more detailed the image but the noise level was also higher. Thorax CT Scan examination should be carried out using the B70s very sharp filter that was able to produce images with the optimal information and fairly low noise level. A very thin GGO image in the early stage of the manifestation of Covid-19 could be identified in the Thorax CT Scan examinations for diagnosis of Covid-19 case.

Role of CT Imaging for the Management of COVID-19

Aim: To evaluate the role of high-resolution Computer tomography imaging in the management of COVID-19. Study design: Prospective study Place and duration of study: Jinnah Postgraduate Medical Centre Karachi from 1st December 2021 to 31st May 2022. Methodology: One hundred patients suspected to be suffering from COVID-19 were enrolled. All patients underwent Reverse transcriptase-based polymerase chain reaction tests (RT-PCR). The patients were divided into positive or negative depending upon their test results. A high-resolution computed tomography scan was followed in every patient and the results were compared with the reverse transcriptase-based polymerase chain reaction tests findings. The sensitivity and Specificity of the CT scan test were assessed. Results: The mean age of the patients was 59±6.5 years. There were 60 (60%) male and 40 (40%) female patients. Around 58% of the patients were found as positive on PCR while 42% were negative. There 75% of the cases were positive for novel coronavirus on high-resolution computed tomography scan while only 25% were negative. Conclusion: Chest HRCT-scan proved to be a better and more sensitive tool for the diagnosis of novel coronavirus and can be considered as an alternative screening tool for COVID-19 confirmation. Keywords: SARS-CoV-2, Severity, Pulmonary, CT-scan, Serotype

The efficacy and safety of systemic corticosteroids as first line treatment for granulomatous lymphocytic interstitial lung disease

Granulomatous and lymphocytic interstitial lung disease (gl-ILD) is a major cause of morbidity and mortality among patients with common variable immunodeficiency. Corticosteroids are recommended as first-line treatment for gl-ILD, but evidence for their efficacy is lacking. This study analyzed the effect of high-dose corticosteroids (≥0.3 mg/kg prednisone equivalent) on gl-ILD, measured by high-resolution computed tomography (HRCT) scans, and pulmonary function test (PFT) results. Patients who had received high-dose corticosteroids but no other immunosuppressive therapy at the time (n= 56) and who underwent repeated HRCT scanning or PFT (n = 39) during the retrospective and/or prospective phase of the Study of Interstitial Lung Disease in Primary Antibody Deficiency (STILPAD) were included in the analysis. Patients without any immunosuppressive treatment were selected as controls (n= 23). HRCT scans were blinded, randomized, and scored using the Hartman score. Differences between the baseline and follow-up HRCT scans and PFT were analyzed. Treatment with high-dose corticosteroids significantly improved HRCT scores and forced vital capacity. Carbon monoxide diffusion capacity significantly improved in both groups. Of 18 patients, for whom extended follow-up data was available, 13 achieved a long-term, maintenance therapy independent remission. All patients with relapse were retreated with corticosteroids, but only one-fifth of them responded. Two opportunistic infections were found in the corticosteroid treatment group, while overall infection rate was similar between cohorts. Induction therapy with high-dose corticosteroids improved HRCT scans and PFT results of patients with gl-ILD and achieved long-term remission in 42% of patients. It was not associated with major side effects. Low-dose maintenance therapy provided no benefit and efficacy was poor in relapsing disease.

Pattern of Lung Involvement in Predicting Severity and Sequelae in Patients With COVID-19.

Background During the COVID pandemic, high-resolution CT scan has played a pivotal role in detecting lung involvement and severity based on the segments of the lung involved. The pattern of involvement was not considered, and our aim is to observe the pattern of lung involvement in predicting severity and guiding management protocol in patients with COVID-19. Methodology It was a prospective observational study conducted with 151 patients admitted with COVID-19with a positive reverse transcriptase polymerase chain reaction test (RT-PCR)in a single tertiary care hospital in south India. Patients with pre-existing lung pathologies were excluded from the study. Eligible patients were then divided into mild, moderate, and severe categories based on Indian Council of Medical Research (ICMR) guidelines, and high-resolution computed tomography (HRCT) chest was done, findings of which were then categorized based on lung involvement; into ground glass opacities (GGO), interstitial involvement and mixture of both. These were then analyzed to determine their importance with respect to the duration of stay and severity of the disease. Results The data collected was analyzed by IBM SPSS software version 23.0 (IBM Corp., Armonk, NY, USA). The study population included 114 males (75.5%) and 37 females (24.5%). HRCT chest was done which showed 62.3% of patients had GGO, 14.6% had interstitial lung involvement, 18.5% had a mixture of both and 4.6% had normal lung findings. These findings, when compared to clinical categories of severity, showed a significant co-relation between pattern of involvement of the lung and the severity of the disease. It also showed significant co-relation with the duration of stay. Conclusion HRCT chest has proven to be useful in the determination of patient's severity and can guide with management. We suggest earlier initiation of steroids and anticoagulants in patients with interstitial involvement even for the patients not on oxygen therapy yet. It can be used as a triage modality for screening due to the advantage of presenting with immediate results as opposed to RT-PCR which might take hours and can delay treatment which can prevent worsening.

1426. Characterization of Patients with Iatrogenic Mycobacterial Infections: A Hospital-Based Survey

Abstract Background Tuberculosis (TB) is a chronic granulomatous inflammation usually involving the lung parenchyma and hilar lymph nodes. Extra-pulmonary involvement is seen in ∼20% of all TB cases. Developing tuberculosis following treatment for another primary medical condition is a rare occurrence. Iatrogenic literally means illness caused by medical examination or treatment. Mycobacteria have been used to treat a few medical conditions and the therapeutic use has been validated extensively in literature. The mycobacteria used for therapeutic purposes are supposed to be either attenuated or non pathogenic strains. Growth and dissemination of this mycobacterium is a rare but serious possibility. Reactivation of latent mycobacterial infection following therapy is also a part of iatrogenic mycobacterial infection. Methods We report a retrospective study investigating adverse events manifesting with development of iatrogenic tuberculosis. The data was obtained from a tertiary care centre over a period of 2 years. Diagnosis of tuberculosis was established based on clinical, radiological(chest X-Ray and High resolution CT scan), sputum smear microscopy and skin/tissue biopsy and Xpert MTB/RIF. Tuberculin skin test(TST) and Interferon gamma release assay (IGRA) were used as additional diagnostic tests. Results The search yielded 26 cases of iatrogenic tuberculosis, with a median age of 56.5 years. Most common cause was reactivation of latent tuberculosis due to use of anti-TNF alpha biologic agents(53.8%). Development of Tuberculosis verrucosa cutis following BCG inoculation for verruca vulgaris was noted in about 19.2% of cases and Tubercular abscess due to Mycobacterium w or BCG inoculation for Covid-19 was noted in 11.5% cases. Bacillus Calmette Guérin(BCG) induced balanitis secondary to therapy for Carcinoma urinary bladder was noted in 7.69%of cases. Bacillus Calmette-Guerin or BCG induced balanitis following use of intravesical immunotherapy for treating early-stage urinary bladder cancer and successful clearance of lesions post therapy Tuberculosis Verrucosa Cutis following Immunotherapy for plantar warts Conclusion All patients were managed successfully with anti tubercular therapy. These observations indicate that tuberculosis infection can develop in previously healthy individuals in endemic zones following biologic therapy of use of mycobacterial agents for other therapeutic indications. Disclosures All Authors: No reported disclosures.

A Precise Method to Detect Post-COVID-19 Pulmonary Fibrosis Through Extreme Gradient Boosting.

The association of pulmonary fibrosis with COVID-19 patients has now been adequately acknowledged and caused a significant number of mortalities around the world. As automatic disease detection has now become a crucial assistant to clinicians to obtain fast and precise results, this study proposes an architecture based on an ensemble machine learning approach to detect COVID-19-associated pulmonary fibrosis. The paper discusses Extreme Gradient Boosting (XGBoost) and its tuned hyper-parameters to optimize the performance for the prediction of severe COVID-19 patients who developed pulmonary fibrosis after 90days of hospital discharge. A dataset comprising Electronic Health Record (EHR) and corresponding High-resolution computed tomography (HRCT) images of chest of 1175 COVID-19 patients has been considered, which involves 725 pulmonary fibrosis cases and 450 normal lung cases. The experimental results achieved an accuracy of 98%, precision of 99% and sensitivity of 99%. The proposed model is the first in literature to help clinicians in keeping a record of severe COVID-19 cases for analyzing the risk of pulmonary fibrosis through EHRs and HRCT scans, leading to less chance of life-threatening conditions.

Clinical and functional characteristics of the post-COVID period (6-month follow-up)

Respiratory symptoms and functional disorders are registered in patients who suffered from COVID-19 (COronaVIrus Disease 2019). Aim. Clinical and functional evaluation of the respiratory system during 6-month follow-up in patients who had moderate and severe COVID-19. Methods. 80 patients were included in the cohort observational prospective study. Patients were examined in 46 (36 - 60) days from the onset of symptoms of COVID-19 and in 93 (89 - 103) and 180 (135 - 196) days at the 2nd and 3rd stages respectively. At all stages, symptoms, dyspnea level, and quality of life were analyzed using validated questionnaires, and a 6-minute step test was performed. At the 2nd and 3rd stages, we assessed spirometric parameters, total lung capacity, carbon monoxide diffusing capacity (DLCO), and high resolution computed tomography scans of chest organs. Results. At the 1st stage of the study, 62% of patients complained of fatigue, muscle weakness, 61% of patients had dyspnea of variable severity. At the 3rd stage of the study, 43% and 42% of patients had the same complaints respectively. The prevalence of moderate COVID-19 form in patients with 35 (25 - 45)% lung damage and severe COVID-19 form with 75 (62 - 75)% of lung damage was established. At the 2nd stage, a DLCO &lt; 80% level was recorded in 46% of patients with 35 (25 - 45)% lung damage and in 54% of patients with 75 (62 - 75)%. At the 3rd stage, DLCO &lt; 80% was diagnosed in 51.9% and 48.1% of patients with of 35 (25 - 45)% and 75 (62 - 75)% lung damage respectively. The level of DLCO &lt; 60% was found in 38,5% and 35,5% of patients with moderate and severe lung damage at the 2nd and 3rd stages of the study respectively. Conclusion. The symptoms were reported less frequently during the 6-month follow-up after COVID-19. 77% and 87% of patients had DLCO &lt; 80% in 93 (89 - 103) and 180 (135 - 196) days after the disease onset, respectively. 38.5% and 35.5% of those patients, predominantly having suffered COVID-19 in severe form, had DLCO &lt; 60% at 93 (89 - 103) and 180 (135 - 196) days, respectively. This calls for a continuous observation and regular examinations after COVID-19.

A Study of Round Window and its Adjacent Anatomy to Guide the Cochlear Implant Electrode Insertion.

Residual hearing preservation has gained attention now which has brought round window membrane into the light, as a port for cochlear implantation. Atraumatic insertion of electrodes can be achieved by study of anatomical variations of round window and its forms which can guide the surgeon. This study was undertaken to examine the anatomical variations of round window and its adjacent structures and their impact on surgical approach during cochlear implantation. A series of 40 adult human temporal bones underwent high-resolution CT scanning and were further dissected for microscopic study of the round window. The antero posterior dimensions of RW ranged from 1.22 to 2.51mm on radiology and on dissection 1.76mm +/- 0.3mm. Shape of round window in 72.5% of bones was oval, and in 27.5% bones it was round shaped. As per Saint Thomas hospital classification for Round window visualization we found 82.5% bones had type I RW visualization and 17.5% had type IIa RW visualization. Area of crista fenestra on dissection was ranging from 0.41 to 0.69 mm2. Residual hearing preservation has become a new motto for surgeons. Therefore thorough anatomic knowledge of round window is must for careful insertion, as round window is closely related to the sensitive inner ear structures.

Toward the determination of sensitive and reliable whole-lung computed tomography features for robust standard radiomics and delta-radiomics analysis in a nonhuman primate model of coronavirus disease 2019.

We propose a method to identify sensitive and reliable whole-lung radiomic features from computed tomography (CT) images in a nonhuman primate model of coronavirus disease 2019 (COVID-19). Criteria used for feature selection in this method may improve the performance and robustness of predictive models. Fourteen crab-eating macaques were assigned to two experimental groups and exposed to either severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or a mock inoculum. High-resolution CT scans were acquired before exposure and on several post-exposure days. Lung volumes were segmented using a deep-learning methodology, and radiomic features were extracted from the original image. The reliability of each feature was assessed by the intraclass correlation coefficient (ICC) using the mock-exposed group data. The sensitivity of each feature was assessed using the virus-exposed group data by defining a factor R that estimates the excess of variation above the maximum normal variation computed in the mock-exposed group. R and ICC were used to rank features and identify non-sensitive and unstable features. Out of 111 radiomic features, 43% had excellent reliability ( ), and 55% had either good ( ) or moderate ( ) reliability. Nineteen features were not sensitive to the radiological manifestations of SARS-CoV-2 exposure. The sensitivity of features showed patterns that suggested a correlation with the radiological manifestations. Features were quantified and ranked based on their sensitivity and reliability. Features to be excluded to create more robust models were identified. Applicability to similar viral pneumonia studies is also possible.

CO2-Water-Rock Interaction and Pore Structure Evolution of the Tight Sandstones of the Quantou Formation, Songliao Basin

As an important part of carbon dioxide capture, utilization and storage (CCUS), the progress of injecting CO2 into oil reservoirs could increase the recovery rate and achieve large-scale carbon storage. It has become one of the most important carbon storage methods around the world. This paper selected the tight sandstone of the fourth member of the Quantou Formation in the southern Songliao Basin to carry out a CO2 storage physical simulation experiment. Representative samples were collected at 24 h, 72 h, 192 h and 432 h to study the CO2 water-rock interaction and to analyze the mineral composition, pore structure and the evolutionary characteristics of physical reservoir properties over time. Physical property analysis, Ion analysis, X-ray diffraction mineral analysis, QEMSCAN mineral analysis, scanning electron microscopy and high-resolution CT scanning techniques were adopted. The main points of understanding were: (i) It shows a differential evolution of different minerals following the storage time of CO2, and carbonate minerals are mainly dissolved with ankerite as a typical representation; a small amount of calcite is formed in 24 h, and dissolved in the later period; feldspar and quartz were partially dissolved; clay mineral precipitation blocked the pores and gaps; (ii) The evolution in mineral variation leads to the complexity of pore structure evolution, following a trend of “small pores decreasing and large pores increasing” with extending storage time. The final porosity and permeability ratios gradually increase from 4.07% to 21.31% and from 2.97% to 70.06% respectively; (iii) There is a negative correlation between the increasing ratio and the original physical properties of the tight stones due to the dissolution of ankerite. Relevant research could provide scientific guidance and technical support for the geological storage of CO2 in lacustrine tight continental sandstones and the development of CCUS technology.