Harutoshi Koide

Detection of coronary artery disease with 13N-ammonia and high-resolution positron-emission computed tomography

In order to evaluate the detectability of coronary artery disease (CAD) with positron-emission computed tomography (PET), we performed 13N-ammonia myocardial PET scanning at rest and with exercise loading in 20 normal subjects and 40 patients with CAD, by means of a high-resolution, multi-slice, whole-body PET scanner. Myocardial PET scanning was performed 3 minutes after injection of 13N-ammonia at rest and during exercise. The circumferential profile analysis of resting PET images revealed regional hypoperfusion in 96% of CAD patients with previous myocardial infarction and in 29% of those without infarction. Exercise PET studies showed high sensitivity (93%) in detecting CAD without myocardial infarction, whereas no abnormal hypoperfusion was detected in normal subjects. Segmental analysis of regional myocardial perfusion with exercise stress identified 67 of 75 stenosed vessels (89%). We conclude that 13N-ammonia myocardial PET with exercise loading provides high-quality tomographic images of regional myocardial perfusion and is a valuable technique for detecting CAD.

Multidetector SPECT scanner for brain and body: system performance and applications.

A multidetector whole-body single photon emission computed tomography (SPECT) scanner has been developed for high-resolution dynamic SPECT imaging. The scanner consists of three detector rings with 128 NaI crystals (14 x 26 x 30 mm) in each ring, providing three tomographic images at 30 mm intervals. This system uses a rotation of collimator around the patient combined with the detector rotation for fine data sampling. The in-plane spatial resolution is 14.2 mm (full width of half maximum) with high-resolution (HR) collimator, 22.0 mm with high-sensitivity (HS) collimator, and 10.6 mm with high-resolution brain (HRB) collimator. The axial resolution is 24.0, 34.0, and 23.5 mm with HR, HS, and HRB collimator, respectively. The sensitivity measured with a 20% energy window for 99mTc in a 20 cm diameter phantom is 5.7, 17.0 and 6.6 kcps/muCi/ml with HR, HS, and HRB collimator, respectively. This scanner allows dynamic SPECT imaging both for brain and body organs with good spatial resolution.