This study aims to evaluate the changes in airway volume using MRI following orthodontic treatment with premolar extraction in Bimaxillary protrusion patients.A total of n=32 patients in the age group of 19-28 yrs with Bimaxillary protrusion indicated for fixed orthodontic treatment with extraction of all the first four premolar teeth will be recruited. Pre-treatment intra-extraoral photographs, study models, Magnetic Resonance Imaging (MRI) will be recorded. MRI will be taken in two stages using 3-Tesla Magnetom VIDA system pretreatment before bonding (T0) and immediately after debonding (T1) to assess the volumetric changes in airway and to correlate with arch perimeter. T1 weighted (T1-w) images will be acquired. The standardised procedure will be followed by stabilising head with foam pads keeping Frankfort horizontal plane (FHP) perpendicular to floor in awake patients with supine position and head in neutral anatomical position. Participants will be instructed to breathe normally through their nose, rest their tongue on the back of the front teeth with teeth lightly touching, and refrain from swallowing. Midsagittal and axial views of airway (T1-w images) will be analysed though software Syngo.via siemens (Siemens Medical Solutions USA). The landmarks identification will be done by the senior orthodontist. Extraction of all first premolars willl be done followed by placement of 0.022 ×0.028-inch slot MBT bracket for the fixed appliance therapy.  Interradicular titanium miniscrews ( 1.8x8mm) will be inserted immediately after extraction between second premolar and first molar in both the jaws to preventing mesial drift of posterior teeth during levelling and alignment. Post alignment retraction of anterior teeth will be done by enmass retraction using NiTi closed coil spring (9mm with 250 gm force) by anchorage from MS1.The force range of 250-300grams will be used during the entire course of the procedure. Finishing and detailing will be done till 0.021x0.025 TMA wire. Post-treatment MRI of patient will be recorded immediately after debonding and before placement of fixed retainers.Post-treatment records will be obtained.The data will be analyzed using SPSS v29. The inter-operator and intra-operator reliability assessment will be calculated using inter-class coefficient. Normality of data will be assessed using Shapiro-wilk test. Descriptive statistics will be calculated based on population parameters. Pre (T0) and post-treatment (T1) changes in upper airway volume will be analysed with Paired t-test (Mean + SD) and Post-hoc test will be conducted to evaluate for any co-relation with change in arch-length.