 Blood pressure will be checked and intravenous adenosine infusion will begin with continuous heart rate and rhythm monitoring. After 5 minutes of adenosine infusion, contrast-enhanced CT perfusion imaging will be performed during a 4-5 mlsec intravenous iodinated contrast ISOVUE-370 infusion. The stress dynamic CTP images will be started using a test bolus acquisition and accurate quantification of optimum timing for dynamic CTP and boost CTA acquisition and will continue for 20-30 sec using a ECG triggering method to allow acquiring the images only within 70-80 of the R-R interval, but not continuously. The parameters for the stress dynamic CTP image acquisition are the followings: For the heart rate of 80 bpm the tube voltage will be 80 kV and the tube current will be 100mA. Other parameters are: gantry rotation0.275, range120mm. The stress static CTP imaging will be performed as a boost scan during the stress dynamic CTP with the same tube voltage 80kV but the tube current of 600mA within 70-80 of R-R interval. The boost timing will be quantified from test bolus acquisition. The average radiation dose for stress dynamic and static CTP acquisition is 5.17mSv. The scan parameters are summarized in the table below: 