Diagnosis of Cardiac Sarcoidosis: Materials and Methods
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. canadian family pharmacy online
Clinical Study
Subjects: This study was approved by the Ethics Committee of our hospital, and informed consent was obtained from all subjects prior to the commencement of the study. Between 1996 and 2001, sarcoidosis was diagnosed by the biopsy of noncardiac tissue in 14 patients (mean [± SD] age, 52 ± 16 years; 5 men and 9 women) at the Toyokawa City Hospital (Table 1). In 7 of these 14 patients, cardiac involvement of sarcoidosis had been suspected on the basis of clinical findings (not including dual SPECT scan findings) before their enrollment in this study (Table 2). Four of these seven patients had been receiving steroid therapy. The remaining seven patients in whom cardiac sarcoidosis had not been previously suspected had not been receiving steroids. Patients with inflammatory disease other than sarcoidosis, ischemic heart disease (old or acute myocardial infarction or angina pectoris), myocarditis, cardiomyopathy, or malignant tumors were excluded from the present study on the basis of the careful evaluation of clinical history, physical examination findings, laboratory and radiologic findings, and ECG, ultrasound cardiogram, and exercise test findings.
Table 1—Background Variables and Results of Dual SPECT Scanning
Case/Age,
yr/Sex |
Duration,
yr |
Suspected
Cardiac Lesiont |
Steroidj | Dual SPECT Scan | |
Ga
Uptake |
Tc
Defect |
||||
1/28/M | 4 | – | – | A, In | A, In |
2/68/F | 7 | + | + | A | A |
3/48/F | 3 | + | + | A, P | |
4/76/M | 4 | – | – | P | P |
5/40/M | 8 | + | + | ||
6/62/F | 8 | + | + | In, Ap | |
7/76/F | 2 | – | – | ||
8/39/F | 8 | – | – | In | In |
9/44/F | 5 | + | – | A | A |
10/51/F | 3 | – | – | A, S | A, S |
11/56/F | 7 | + | + | A | A |
12/64/F | 3 | – | – | ||
13/29/M | 1 | – | – | Ap | |
14/49/M | 6 | + | – | A | La |
Table 2—Criteria for the Suspicion of Cardiac Sarcoidosis at Our Hospital (Before the Introduction of Dual SPECT Scanning)
Criterion | Description |
A | At least one of right bundle-branch block, left-axis deviation, atrioventricular block, ventricular tachycardia, ventricular extrasystole (Lown degree 2 or higher), abnormal Q wave, and changes in ST-T is present on an echocardiogram or Holter echocardiogram. |
B | Abnormal left-wall motion, local thinning or thickening of the wall, or left ventricular dilation are evident on an ECG. |
C | Abnormal findings (perfusion defect on T1 scintigram, abnormal uptake on Ga or Tc scintigram) are found in nuclear medicine investigations of the heart. |
D | Cardiac catheterization reveals abnormal pressure within the heart or reduced cardiac output, or left ventriculography radiography discloses abnormal wall motion or reduced ejection fraction. |