A diagnostic catheter and method of use for analyzing tissue is provided. A method for analyzing tissue in accordance with one embodiment of the present invention includes inserting a catheter having a sensor at its distal end into the body of a patient, applying suction through the catheter to secure the tissue to the catheter and then analyzing the tissue with the sensor. An apparatus for analyzing tissue within the body of a patient in accordance with an alternative embodiment of the present invention is also provided. This alternative embodiment includes a catheter having a first end and a second end, the first end having an orifice and a sensor, the catheter also having a lumen.