Bladder outlet obstruction (BOO) is a common cause of lower urinary tract symptoms (LUTS) in men. Urologists usually depend on International Continence Society (ICS) nomogram and experiences for diagnosis. However, this method requires invasive testing which is very uncomfortable and time consuming for patients. Besides, there exists equivocal zone by using ICS nomogram. The objective of the present study is to investigate the feasibility of computed tomography based non-invasive technique to diagnose bladder outlet obstruction (BOO). Based on the rapid advances in noninvasive imaging technology, the images of targeted organs are acquired using computed tomography, where the three dimensional model of the lower urinary tract system (involving the bladder and urethra) are reconstructed. The reconstructed 3D models are then analyzed with computational fluid dynamic technique, where the predicted pressure drop is used as a replacement of the invasive pressure measurements. It was found that the predicted pressure drop has a good correlation with field measured Abrams-Griffiths number. Further, a functional nomograph (similar to ICS nomogram) is developed, where healthy man pressure drop is used as threshold to distinguish patients with and without BOO.