Validation and Clinical Utility of the Lung Sliding Index (LSI) for Differentiating Pulmonary Diseases

* The study will enroll adults with various pulmonary pathologies and healthy controls. Lung ultrasound will be performed on all subjects using a standardized 12-zone protocol; each zone will be scored for pleural sliding using the LSI (0-3 per zone; total 0-36). Operator training and calibration will precede enrollment to ensure scoring consistency. * A subset of patients will undergo repeat assessments to evaluate intra- and interobserver reliability, using independent, blinded raters. * For correlation with LSI, we will collect clinical data, including spirometry, blood gases, symptom scores, and 6-minute walk tests. Diagnostic utility will be evaluated using ROC curves. Satisfaction and feasibility will be assessed via Likert questionnaires, with validation analyses (internal consistency, test-retest reliability). * All data will be de-identified and securely stored. Written informed consent will be obtained from all participants. * The study groups will include: 1- Pneumothorax 2. Interstitial lung disease (ILD/IPF) 3. COPD/emphysema 4. Bronchiectasis 5. Community-acquired pneumonia 6. Pulmonary edema 7- Pleural effusion 8. Healthy controls * Data Collection Methods: * Standardized data entry forms for clinical, imaging, and outcome data. * Centralized digital storage with access limited to study personnel. Statistical Methods: \- Descriptive statistics for baseline data ANOVA or Kruskal-Wallis for group comparisons; post hoc testing as appropriate ROC analysis for diagnostic cut-offs Pearson/Spearman correlation for clinical associations Intraclass correlation coefficients (ICC) for reliability Cronbach's alpha for Likert scale validation Multivariable regression for confounder adjustment