Transient Prolonged Stunning by Dipyridamole Stress Proved by Post-stress ( 1 hour ) and 24 hour Tc-99m-MIBI Gated SPECT / 대한핵의학회잡지

We performed 1st day Tc-99m-sestamibi gated SPECT with dipyridamole/rest T1-201 SPECT and 2nd day 24 hour delay T1-201 SPECT/rest Tc-99m-sestamibi gated SPECT in 27 patients with coronary artery disease(24) or having chest pain(3). Stress and rest Tc-99m- sestamibi gated SPECT was acquired at 60min post-injection. A 4-point scoring system(0 to 3 for normal to absent tracer uptake) for 17 segments was used. Wall motion was scored on another 4 point scale(0 to 3 for normal to dyskinesia) in the lst day post-stress gated and the 2nd day rest gated SPECT. Post-stress gated SPECT showed wall motion abnormality in 94 segments(20%). Fifty-five segments among these 94 showed the same wall motion between post-stress and rest gated SPECT:i.e. 1-1: 23 segments, 2-2: 29 segments, 3-3: 3 segments. Re-maining 39 segments (41.5%) showed different wall motion between post-stress and rest Tc-99m-sestamibi gated SFECT. Twenty one segments with wall motion abnormality had normal perfusion(rest:15 segments, 24 hour delay: 6 segments) at either rest or 24 hour delay. Fifteen among these 21 segments showed persistent post-stress and the 2nd day rest wall motion abnormality(persistent stunning). However, in 6 segments with prolonged (1 hour after stress) stunning, abnormal wall motion did improve in the 2nd day rest Tc-99m-sestamibi gated SPECT(transient prolonged stunning). These 6 segments had normal perfusion at rest(n=4) or at 24 hour delay(n=2). Post stress wall motions showed significantly higher scores in persistent stunning than in prolonged transient stunning(P value<0.05). It was concluded that we could find stunned myocardium with gated Tc-99m-sestamibi SPECT at either post-stress or rest and that some myocardial walls of post-stress 1 hour gated SPECT did not show truly rest wall motion. So, we should be cautious if we use post-stress Tc-99m-sestamibi wall motion to assess rest wall motion.

Optimization of Subtraction Brain Perfusion SPECT with Basal / Acetazolamide Consecutive Acquisition / 대한핵의학회잡지

This study investigated the method to adjust acquisition time(a) and injection dose(i) to make the best basal and subtraction images in consecutive SPECT. Image quality was assumed to be mainly affected by signal to noise ratio(S/N). Basal image was subtracted from the second image consecutively acquired at the same position. We calculated S/N ratio in basal SPECT images(S1/N1) and subtraction SPECT images(Ss/Ns) to find a(time) and i(dose) to maximize S/N of both images at the same time. From phantom images, we drew the relation of image counts and a(time) and i(dose) in our system using fanbeam-high-resolution collimated triple head SPECT. Noise by imaging process depended on Poisson distribution. We took maximum tolerable duration of consecutive acquisition as 30 minutes and maximum injectible dose as 1,850MBq(50 mCi)(sum of two injections) per study. Counts of second-acquired image(S2), counts(Ss) and noise(Ns) of subtraction SPECT were as follows. C1 was the coefficient of measurement with our system.

Ablation of Remnant Thyroid Tissue with I-131 in Well Differentiated Thyroid Cancer After Surgery / 대한핵의학회잡지

To evaluate the effectiveness of I-131 in ablation of residual thyroid tissue, we analyzed 350 patients with thyroid cancer who were treated with various doses of I-131 after surgery for thyroid cancer. Two hundred fifty five patients were treated with l.lGBq(30mCi) of I-131 for ablation of remnant thyroid and one hundred seventeen patients received more than 2.8GBq(75mCi) of I-131. We determined the effectiveness of ablation by following I-131 whole body scan. Absent visible uptake or minimal uptake in thyroid tissue were considered as successful ablation. Of 255 patients who received doses of 30mCi I-131 therapy, 131 patients(51%) showed successful ablation of residual thyroid tissue with 2.6+/-1.7 times of I-131 therapy. Of 117 patients who received doses of the more than 75mCi I-131, 84 patients(72%) had successful remnant thyroid ablation with 1.6+/-1.1 times of I-131 therapy. According to the extent of surgery, successful ablation rates were 78%, 62%, 54%, 33% in patients who underwent total thyroidectomy, subtotal thyroidectomy, lobectomy and isthmectomy, lobectomy or tumorectomy, respectively. This study showed that ablation of remnant thyroid after surgery with 30mCi I-131 was successful only in 50%. Therefore, in cases of patients with high risk for recurrence, we recommend high dose I-131 for ablation of remnant after total thyroidectomy.

Comparison of diagnostic accuracy for detecting coronary artery disease of dipyridamole Tc-MIBI myocardial SPECT and it's defect map between men and women / 대한핵의학회잡지

No abstract available.

A preliminary quantification of Tc-HMPAO brain SPECT images for assessment of volumetric regional cerebral blood flow / 대한핵의학회잡지

No abstract available.

A Study on the Clinical Feasibility of Split Dose Thallium-201 Dipyridamole Scan in the Diagnosis of Angina Pectoris

A technique for Thallium-201 imaging after two separate injections of the tracer, which took less than I hour, was performed to evaluate if this technique could be used clinically as a noninvasive screening test of angina pectoris. 29 patients who complained of chest pain were included in this study: 18 patients were proven to have coronary artery disease by coronary angiography and 11 patients had normal coronary arteries. With the patient supine at rest, 1.0 mCi of Thallium was injected intravenously and imaging was performed in the anterior and 50degrees left anterior oblique projections for a preset time according to Okada's protocol. Immediately after acquisition of the rest images, without moving the camera head, an infusion of dipyridamole was done at the rate of 0.14 mg/Kg/min for 4 minutes. Two minutes after stopping the infusion, 1.0 mCi of Thallium was injected intravenously and 50degrees left anterior oblique and anterior projection images were acquired. Images of the same projection were realigned using computer image registration approach (PDP-11/34 computer of DEC company). The rest image was then subtracted from the realigned dipyridamole image to produce an image representing perfusion during dipyridamole induced hyperemia (subtraction image). The results were as follows; 1) All of the subtraction images were of adequate quality for interpretation. 2) 16 cases in 18 patients of angina pectoris and 1 case in 11 normal control showed perfusion defects, so the over all sensitivity and specificity of the subtraction versus rest Thallium image technique for diagnosis of angina pectoris were 89% and 91%, respectively. 3) All patients (8 cases) whose left ventriculography revealed abnormality of regional wall motion showed perfusion defects in corresponding segments. But qualitative analysis of Thallium image could not predict if the patient whose Thallium image revealed perfusion defect has abnormality of regional wall motion. 4) segmental analysis was performed to know the association between the site of coronary artery stenosis and the perfusion defects in Thallium scan, which revealed the sensitivities for detecting stenosis of LCX, LAD & RCA were 50-60% in range and the range of specificities were 89-92%. 5) Adverse effects of dipyridamole were headache (2 cases) and chest pain (4 cases) but aminophylline was not needed in any case. In conclusion, split dose Thallium dipyridamole scan can be used as a noninvasive screening test of angina pectoris reducing the total duration of imaging to less than one hour. Futher applications of this technique may include the assessment of myocardial perfusion before and immediately after coronary angioplasty and coronary artery bypass graft and the evaluation of the impact of pharmacotheraphy on regional myocardial perfusion.