Noninvasive Differential Diagnosis Between Chronic Pulmonary Thromboembolism and Primary Pulmonary Hypertension by Means of Doppler Ultrasound Measurement 11This study was supported by Grant-in-Aid 09770527 for General Scientific Research from the Ministry of Education, Science and Culture of Japan; by a research grant for Cardiovascular Diseases (6A-4, 7C-2) from the Ministry of Health and Welfare of Japan; and by a grant from the Science and Technology Agency, Encourage System of Center of Excellence, Tokyo.