Noritaka Yamamoto

Thallium-201 myocardial SPECT findings at rest in sarcoidosis

In 41 patients with sarcoidosis (diagnosed according to criteria recommended by the Committee on Diffuse Pulmonary Disease, Ministry of Health and Welfare, Japan 1988), thallium-201 (201Tl) myocardial SPECT was performed to investigate: (1) the ability of201Tl SPECT to detect cardiac involvement of sarcoidosis with images recorded at rest and 2 hours later, and (2) the relationships between201Tl myocardial SPECT findings and the activity of sarcoidosis or endomyocardial biopsy findings. As to the abnormal findings in201Tl myocardial SPECT, (1) a low density area was seen in 13 of 41 cases (31.7%) and non-uniform uptake was found in 17 cases (41.5%), (2) the mean washout ratio (n=39) was 16.5±7.4%, which is significantly (p < 0.05) lower than that found in normal subjects, 23.9±7.5 % (n=10). Of the 19 patients judged visually to be normal, 5 patients had a reduced mean washout ratio less than 12%. Thus, the incidence of abnormal findings including all types of abnormality, on201Tl myocardial SPECT in sarcoidosis was 63.4% (26/41 cases). In studying the relationship between201Tl myocardial SPECT findings and the activity of sarcoidosis (as measured by the serum ACE (angiotensin converting enzyme) or lysozyme level, or the presence of more than 30% symphocyte fraction in BALF (broncho-alveolar lavage fluid)), 20 (80%) of 25 cases with201Tl abnormality were judged to be active sarcoidosis, while only 6 (37.5%) of 16 cases with normal findings on201Tl SPECT were judged to be active. This suggests that there is a significant (p < 0.01) relationship between the presence or absence of an abnormal finding on201Tl myocardial SPECT and the activity of sarcoidosis. Among 13 patients examined by endomyocardial biopsy, 10 patients had abnormal findings on201Tl myocardial SPECT and 7 of these 10 patients had no histological evidence of cardiac sarcoidosis. In all of these 7 patients, however, sarcoidosis was judged to be active. This suggest that endomyocardial biopsy is of limited value in the diagnosis of cardiac sarcoidosis.

Usefulness of resting thallium-201 delayed imaging for detecting myocardial viability in patients with previous myocardial infarction

To test the feasibility of resting thallium-201 (201Tl) initial and delayed scintigraphy for detecting the area of viable myocardium, we performed single photon emission computed tomography (SPECT) in 57 patients with previous myocardial infarction (MI). All had received coronary arteriography (CAG) and left ventriculography (LVG). Initial and delayed myocardial imagings were carried out 10 min and 2 hours, respectively, after the injection of201Tl at rest. Redistribution was judged by visual interpretation and/or the circumferential profile curve, and found in the infarcted or its adjacent area in 40 of the 57 cases (70.2%). A negative washout (net increase of201Tl uptake in delayed image) was detected in 17 of these 40 cases. In 10 of the 57 patients, both exercise and rest-injected201Tl myocardial images were obtained at exercise and rest, and compared visually. The areas of abnormal perfusion were smaller in the resting delayed images than those seen after exercise in 9 of the 10 cases, and were equal in one case. Thus, resting201Tl delayed myocardial scintigraphy appears to reduce the underestimation of the size of the viable myocardium by the usual201Tl images obtained after exercise or by single initial images obtained at rest in patients with previous MI.

Extravascular lung water measured with99mTc-RBC and99mTc-DTPA is increased in left-sided heart failure

Extravascular lung water (EVLW) was quantitatively measured in 81 patients consisting of 10 subjects with normal cardiac function and 71 patients with left-sided heart diseases, using99mTc-RBC as a non-diffusible indicator and99mTc-DTPA as a diffusible indicator in the equilibrium phase. EVLW averaged 3.0±1.4 (ml/kg, mean±SD) in subjects with normal cardiac function (n=10), 4.3±1.7 in New York Heart Association functional class I patients (n=30), 4.8±2.4 in NYHA functional class II patients (n=33) and 9.4±5.4 in NYHA functional class III (n=8) patients. EVLW was greater in NYHA class III than in normal controls or NYHA classes I or II (p < 0.01).Lung thermal volume (LTV) was also measured in 31 of the 81 patients using a double indicator dilution technique with sodium and heat. LTV averaged 6.0±1.2 (ml/kg) in normal subjects (n=4), 8.6±2.0 in NYHA functional class I patients (n=11), 9.7±3.0 in NYHA functional class II patients (n=13), and 15.9±8.2 in NYHA functional class III patients (n=3). The correlation between EVLW and LTV was significant (EVLW=0.79×LTV-72.8, r=0.80, p < 0.01). There were significant differences in EVLW/LTV ratio between NYHA class III (0.93±0.16) and NYHA class I (0.62±0.22) or class II (0.60±0.23). Thus, it was shown that EVLW was increased in left-sided heart failure and that LTV overestimated the EVLW.