Abstract
BACKGROUND: Knowledge of normal variation and measurements on a chest radiograph is essential to interpret any abnormality. There is paucity of information about normal measurement ranges and variations in young adolescents, particularly from Indian subcontinent. The aim of this study was to analyze certain normal variations on screening chest radiographs of healthy Indian adolescents and the objectives were to measure/assess (1) degree of inspiration, (2) cardiothoracic ratio (CTR), (3) presence of gastric fundic bubble, (4) fundocupolic distance, (5) presence of splenic flexure, (6) difference in height of diaphragmatic domes and (7) effect of inspiration on the CTR. METHODS: Digital chest radiographs obtained during routine medical examinations for all consecutive medical graduate aspirants in the year 2016 at a medical college, were analyzed for the above mentioned parameters using DICOM viewing software. RESULT: A total of 558 chest radiographs were analyzed. The mean age of the subjects was 18.50 (SD = 1.002) (range: 17-22 years). There were 497 (89.1%) male and 61 (10.9%) female. Degree of inspiration was at 5th, 6th, 7th and 8th ribs in 29 (5.1%), 259 (46.4%), 264 (47.3%) and 6 (1%) respectively. Mean maximum transverse cardiac diameter, internal thoracic diameter, CTR were 1153.22 ± 120.01, 2935.24 ± 224.86 and 0.39 ± 0.03 respectively. Females had slightly higher CTR (0.40 ± 0.035) as compared to the males (0.39 ± 0.032) (p = 0.009). Gastric fundic bubble was visualized in 91% subjects. Mean fundo-cupolic distance was 8.75 ± 8.00. Mean value for difference in the level of two domes of diaphragm was 15.28 ± 5.38. CONCLUSION: The study highlights normal range of inspiration, CT ratio, fundocupolic distance and diaphragmatic dome level difference on screening chest radiographs in healthy Indian adolescents.