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Diagnosis of Cardiac Sarcoidosis: Materials and Methods

Published in Sarcoidosis

Preliminary Experiment
A cylindrical source (diameter, 24 mm) containing Ga (67 MBq per 2 mL) and Tc (67 MBq per 2 mL) was placed on the collimator plane to collect information on the two nuclides simultaneously. An acryl plate with a thickness of 0, 3, or 6 cm was interposed between the collimator and the source. To calculate the scatter ratio, the scatter levels for Ga (collected with an energy of 93 keV) and Tc (collected with an energy of 140 keV) were measured. The influence of the scatter from each nuclide on images was evaluated using a heart phantom (RH-2; Kyoto Kagaku; Kyoto, Japan). First, Ga (15 MBq per 20 mL) was infused into the anterolateral wall and the inferolateral wall, and Ga SPECT scanning was performed. Tc then was infused into the anterior wall, anterior septum, inferior septum, inferior wall, and inferolateral wall at different concentrations (ie, 0, 5, 15, or 30 MBq per 20 mL), with the Tc/Ga concentration ratio therefore ranging from 0 to 2. Dual SPECT scanning was thus performed (Starcam 3000XR/T combined with a Medium Parallel Collimator; GE Medical Systems; Milwaukee, WI). Energy levels of 93, 184, and 296 keV were used for Ga SPECT scanning. For dual SPECT scanning, the energy was 93 keV for Ga and 140 keV for Tc. The window width was set at 20% in all procedures. The data were collected on a 64 X 64 matrix and at a magnification of 2.00. The circular orbit was 180° (32 directions; 60 s per direction). Image reconstruction was performed with a Butterworth prefilter and a ramp backprojection filter, without correction for attenuation. The Ga image was superimposed on the TcROI (TcROI + Ga) in our attempt to locate abnormal Ga uptake in the myocardium. Continue reading this post…

Diagnosis of Cardiac Sarcoidosis

Published in Sarcoidosis

Diagnosis of Cardiac SarcoidosisSarcoidosis is a chronic systemic granulomatous disease ^ of unknown origin. Most deaths from sarcoidosis are attributable to involvement of the heart, making the early diagnosis and treatment of cardiac sarcoidosis essential. However, cardiac sarcoidosis shows no specific clinical symptoms or specific features on ECGs or echocardiograms, making it difficult to diagnose this condition. A definite diagnosis of this condition can be made when testing of an endomyocardial biopsy specimen is positive, but the rate of such biopsy results is low (around 20%).
Nuclear medicine is becoming increasingly important in the diagnosis of cardiac sarcoidosis. The development of single-photon emission CT (SPECT) scanning using I-metaiodobenzylguanidine, Tl (Tl), and 99mTc-sesta-mibi (Tc), has increased the diagnostic sensitivity of nuclear medicine. However, these modalities are not satisfactorily specific to cardiac sarcoidosis. Furthermore, the relationship between positive findings and the activity of the disease remains unclear when these SPECT scanning techniques are used for the diagnosis of cardiac sarcoidosis. Ga (Ga), on the other hand, is highly specific to cardiac sarcoidosis, since it is accumulated in inflamed areas and is expected to be useful in judging the responses of the disease to steroid therapy. Continue reading this post…