Brain Abscess Uptake at Tl-201 Brain SPECT / 핵의학분자영상

A 22-year-old woman with a history of acute lymphoblastic leukemia was hospitalized for headache and vomiting. CT scan showed a well-defined, ring like enhancing mass in the left frontal lobe with surrounding edema and midline shift. Magnetic resonance imaging demonstrated a round homogeneous mass with a ring of enhancement in the left frontal lobe. Tl-201 brain SPECT showed increased focal uptake coinciding with the CT and MRI abnormality. Aspiration of the lesion performed through a burr hole yielded many neutrophils, a few lymphocytes and histiocytes with some strands of filamentous microorganism-like material. Modified AFB stained negative for norcardia. Gram stain showed a few white blood cells and no microorganism. Antibiotics were started and produced a good clinical response. After one month, CT scan showed markedly reduction in size and extent was observed.

In Vitro Study of Tumor Seeking Radiopharmaceutical Uptake by Human Breast Cancer Cell Line MCF-7 after Paclitaxel Treatment / 핵의학분자영상

PURPOSE: This study was designed to investigate the cellular uptake of various tumor imaging radiopharmaceuticals in human breast cancer cells before and after paclitaxel exposure considering viable cell number. MATERIALS AND METHODS: F-18-fluorodeoxyglucose, C-11-methionine, Tl-201, Tc-99m-MIBI, and Tc-99m-tetrofosmin were used to evaluate the cellular uptake in MCF-7 cells. MCF-7 cells were cultured in multi-well plates. Wells were divided into DMSO exposure control group, and paclitaxel exposure group. The exposure durations of paclitaxel with 10 nM or 100 nM were 2 h, 6 h, 12 h, 24 h, and 48 h. RESULTS: Viable cell fraction was reduced as the concentration and exposure time of paclitaxel increased. After 10 nM paclitaxel exposure, the cellular uptake of all 5 radiopharmaceuticals was not reduced significantly, irrespective of exposure time and viable cell fraction. After 100 nM paclitaxel exposure, the cellular uptake of all 5 radiopharmaceuticals was enhanced significantly irrespective of viable cell fraction. The peak uptake was observed in experimental groups with paclitaxel exposure for 6 to 48 h according the type of radiopharmaceutical. When the cellular uptake was adjusted for the viable cell fraction and cell count, the peak cellular uptake was observed in experimental groups with paclitaxel exposure for 48 h, irrespective of the type of radiopharmaceutical. CONCLUSION: The cellular uptake of F-18-fluorodeoxyglucose, C-11-methionine, Tl-201, Tc-99m-MIBI, and Tc-99m-tetrofosmin did not reflect viable cell number in MCF-7 cells after paclitaxel exposure for up to 48 h.

Myocardial Tracer Uptake in SPECT Images after Direct Intracoronary Injection Of Tl-201: Comparison with Stress-Reinjection Images / 핵의학분자영상

PURPOSE: To investigate the feasibility of Tl-201 SPECT with intracoronary injection (IC-I) in the detection of viable myocardium, we have performed SPECT imaging after direct intracoronary injection of Tl-201 and images were compared with those of stress-reinjection (Re-I) SPECT. METHODS: Fourteen coronary artery disease patients (male 11, mean age 54 years) who had myocardial infarction or demonstrated left ventricular wall motion abnormality on echocardiography were enrolled. Three mCi of Tl-201 was injected into both coronary arteries during angiography and images were acquired between 6- and 24-hour after injection. Reinjection imaging with 1 mCi of Tl-201 was performed at 4-hour after adenosine stress imaging with 3 mCi of Tl-201. Images were interpreted according to 4-grade visual scoring system (grade 0-3). Segments with mild to moderated uptake (< or=grade 1), and upgraded more than one score with reinjection, and were defined as viable myocardium. RESULTS: Image quality was poor in two cases with IC-I. Numbers of non-viable segments were 60 (23.8%) with IC-I, and 38 (15.1%) with Re-I, respectively. Overall agreement for perfusion grade per myocardial segment in each IC-I and Re-I was 76.5%. Overall agreement for viable segment between IC-I and Re-I was 90.5%. Only one out of 38 segments interpreted as non-viable with Re-I were interpretated as viable with IC-I. And 23 out of 214 segments interpreted as viable with Re-I were interpreted as non-viable with IC-I. CONCLUSION: Intracoronary Tl-201 SPECT seemed to be not advantageous over stress-rest reinjection imaging in the assessment of myocardial viability, mainly due to low count statistics at 6-hour or 24-hour delayed time points. The feasibility of intracoronary Tl-201 SPECT is considered to be limited.

Myocardial Tracer Uptake in SPECT Images after Direct Intracoronary Injection Of Tl-201: Comparison with Stress-Reinjection Images / 핵의학분자영상

PURPOSE: To investigate the feasibility of Tl-201 SPECT with intracoronary injection (IC-I) in the detection of viable myocardium, we have performed SPECT imaging after direct intracoronary injection of Tl-201 and images were compared with those of stress-reinjection (Re-I) SPECT. METHODS: Fourteen coronary artery disease patients (male 11, mean age 54 years) who had myocardial infarction or demonstrated left ventricular wall motion abnormality on echocardiography were enrolled. Three mCi of Tl-201 was injected into both coronary arteries during angiography and images were acquired between 6- and 24-hour after injection. Reinjection imaging with 1 mCi of Tl-201 was performed at 4-hour after adenosine stress imaging with 3 mCi of Tl-201. Images were interpreted according to 4-grade visual scoring system (grade 0-3). Segments with mild to moderated uptake (< or=grade 1), and upgraded more than one score with reinjection, and were defined as viable myocardium. RESULTS: Image quality was poor in two cases with IC-I. Numbers of non-viable segments were 60 (23.8%) with IC-I, and 38 (15.1%) with Re-I, respectively. Overall agreement for perfusion grade per myocardial segment in each IC-I and Re-I was 76.5%. Overall agreement for viable segment between IC-I and Re-I was 90.5%. Only one out of 38 segments interpreted as non-viable with Re-I were interpretated as viable with IC-I. And 23 out of 214 segments interpreted as viable with Re-I were interpreted as non-viable with IC-I. CONCLUSION: Intracoronary Tl-201 SPECT seemed to be not advantageous over stress-rest reinjection imaging in the assessment of myocardial viability, mainly due to low count statistics at 6-hour or 24-hour delayed time points. The feasibility of intracoronary Tl-201 SPECT is considered to be limited.

Tl-201 Redistribution SPECT and N-13 Ammonia PET Images in Patients with Old Myocardial Infarction and Left Ventricular Dysfunction: Segmental Comparison and Discordance Analysis / 대한핵의학회잡지

We compared rest perfusion PET with redistribution perfusion SPECT to investigate the concordant rate between PET and SPECT images and analyze the discordant pattern. MATERIALS AND METHODS: Rest N-13 ammonia and F-18 FDG PET were performed on 18 patients with old myocardial infarction and left ventricular dysfunction whose dipyridamole - 4hr redistribution Tl-201 SPECT showed one or more severe fixed defects. Regional perfusion and metabolism were evaluated visually and quantitatively with 5-segment myocardial model. RESULTS: There were high concordant rate in uptake pattern (80/90 segments, 88.9%) and high correlation coefficient on quantitative analysis (R=0.81, p< 0.001) between redistrubution Tl-201 SPECT and N-13 ammonia PET images. Nine of 18 patients had SPECT-PET concordant pattern (Group I). Ten segments (9 in inferior wall, 1 in apex) from the remaining 9 patients showed SPECT-PET discordant pattern with abnormal Tl-201 defect and near normal N-13 ammonia uptake (Group II). The diastolic and systolic left ventricular dimensions were significantly increased in Group II compared to those of Group I. When attenuation uncorrected N-13 ammonia PET images were reconstructed in Group II, it resulted in PET images with severe inferior wall defects nearly identical to those seen in redistribution Tl-201 SPECT images. CONCLUSION: Redistribution Tl-201 SPECT images showed high concordant rate and correlation with rest N-13 ammonia PET images. Most of discordant segments had fixed thallium defects in inferior wall with nearly normal N-13 ammonia uptake, which may result from severe left ventricular dilatation and attenuation by the left hemidiaphragm and cardiac blood pool.

Dipyridamole Induced Transient Left Ventricular Dysfunction in the Tl-201 Gated Myocardial SPECT / 대한핵의학회잡지

PURPOSE: Recently the occurrence of dipyridamole stress-induced short term stunning was proven and it is reported that Bland Altman analysis by repeated acquisition Tl-201 gated myocardial SPECT (gSPECT) revealed the 95% limit of agreement for LVEF was 10.3 %. The purpose of this study was to investigate the clinical value of dipyridamole induced transient LV dysfunction on Tl-201 gSPECT. MATERIALS AND METHODS: Total 93 patients were included and coronary angiography was performed in all patients less than 2 month from gSPECT. The patients with myocardial infarction were excluded. All patients underwent both dipyridamole stress and 4-h redistribution Tl-201 gSPECT. Forty nine patients of total 93 showed normal coronary arteries (Group 1) and the remaining 44 patients had coronary artery disease (Group 2). We compared LV EF, EDV and ESV during post-stress and 4-h redistribution period calculated by gSPECT using quantitative gated SPECT software and the incidence of dipyridamole induced transient LV dysfunction between group 1 and 2. The criteria for transient LV dysfunction was defined more decrease > or =11% of LVEF during post-stress than 4-h redistribution according to previous reported Bland Altman analysis. RESULTS: During post-stress and 4-h redistribution average of 3.1% increment in LVEF, 6.6% increment in LVEDV and 0.7% decrement in LVESV were shown after stress in Group 1, whereas 4.1% decrement, 9.7% increment and 7.2% increment in Group 2 respectively. Dipyridamole induced transient LV dysfunction was only detected in group 2 (18.2%) and not in group 1. It was more frequently observed in triple vessel disease and left main disease (31.8%, N=22) than one and two vessel disease (4.5%, N=22). CONCLUSION: As with Tc-99m myocardial agent post-stress LV dysfunction was observed in dipyridamole Tl-201 gSPECT. It was only detected in CAD and more frequently occurred in multivessel disease. Thus this finding seems to provide additional information in the diagnosis of coronary artery disease and prediction of prognosis.

Nitroglycerin-Challenged Tc-99m MIBI Quantitative Gated SPECT to Predict Functional Recovery After Coronary Artery Bypass Surgery / 대한핵의학회잡지

PURPOSE: The performance of nitroglycerin-challenged Tc-99m-MIBI quantitative gated SPECT for the detection of viable myocardium was compared with rest/ 24-hour redistribution Tl-201 SPECT. MATERIALS AND METHODS: In 22 patients with coronary artery disease, rest Tl-201/ dipyridamole stress Tc-99m-MIBI gated/ 24-hour redistribution Tl-201 SPECT were performed, and gated SPECT was repeated on-site after sublingual administration of nitroglycerin (0.6 mg). Follow-up gated SPECT was done 3 months after coronary artery bypass graft surgery. For 20 segments per patient, perfusion at rest and 24-hour redistribution, and wall motion and thickening at baseline and nitroglycerin-challenged state were quantified. Quantitative viability markers were evaluated and compared; (1) rest thallium uptake, (2) thallium uptake on 24-hour redistribution SPECT, (3) systolic wall thickening at baseline, and (4) systolic wall thickening with nitroglycerin-challenge. RESULTS: Among 100 revascularized dysfunctional segments, wall motion improved in 66 segments (66%) on follow-up gated myocardial SPECT after bypass surgery. On receiver operating characteristic (ROC) curve analysis, the sensitivity and specificity of rest and 24-hour delayed redistribution Tl-201 SPECT were 79%, 44% and 82%, 44%, respectively, at the optimal cutoff value of 50% of Tl-201 uptake. The sensitivity and specificity of systolic wall thickening at baseline and nitroglycerin-challenge were 49%, 50% and 64%, 65% at the optimal cutoff value of 15% of systolic wall thickening. Area under the ROC curve of nitroglycerin-challenged systolic wall thickening was significantly larger than that of baseline systolic wall thickening (p=0.004). CONCLUSION: Nitroglycerin-challenged quantitative gated Tc-99m-MIBI SPECT was a useful method for predicting functional recovery of dysfunctional myocardium.

Tc-99m MIBI and Tl-201 Uptake in a Thymic Carcinoma / 대한핵의학회잡지

Tc-99m methoxyisobutylisonitrile (MIBI) and Tl-201/technetium subtraction scintigraphy have been used for localization of abnormal parathyroid gland. The uptake mechanism of tracers has been postulated to be increased cellular density and vascularity, or dependent on the presence of mitochondria-rich cells. However, the uptake of these tracers was not specific for abnormal parathyroid gland. The author report a case of thymic carcinoma that would have been mistaken for carcinoma of parathyroid because of Tc-99m MIBI and Tl-201 uptake.

Preoperative Localization in Primary Hyperparathyroidism: Comparison of Tc99m MIBI Scan and Tl201/Tc99m Subtraction Scan

PURPOSE: Recently Tc99m MIBI (methoxyisobutylisonitrile) has been described as an alternative to thallium for localizing parathyroid lesions. The purpose of this study was to compare the efficacy of a Tc99m MIBI scan with a Tl201/Tc99m subtraction scan for localizing parathyroid lesions in patients with primary hyperparathyroidism. METHODS: Among 31 cases of primary hyperparathyroidism operated on at the Department of Surgery, Seoul National University Hospital from January 1997 to June 2001, a Tl201/Tc99m subtraction scan was performed on 16 patients and a Tc99m MIBI scan on 22 patients. Seven patients underwent both. RESULTS: The pathology was a single adenoma in 28 patients, a hyperplasia in 1 patient and a carcinoma in 2 patients. Hypercalcemia was controlled postoperatively in all cases. The sensitivities of the Tl201/Tc99m subtraction scan and Tc99m MIBI scan were 53.3% and 86.4%, respectively. The positive predictive values were 100% of the two study groups. CONCLUSION: We concluded that the better accuracy, superior image quality and lower cost of Tc99m MIBI scan will make it the new radiopharmaceutical parathyroid scan of choice. A unilateral approach can be used with a high degree of success, as in case of a preoperatively localized single parathyroid adenoma, which was confirmed when surgical exploration identified of a normal ipsilateral gland.

Comparison of Ga-67, Tl-201 and Tc-99m MIBI Imaging in Lymphoma Patients / 영남의대학술지

PURPOSE: Ga-67 scintigraphy has been used for the evaluation of tumors, especially lymphoma. Recently, Tl-201 and Tc-99m MIBI were also used to tumor imaging. Tl-201 and Tc-99m MIBI had better physiologic characteristics than Ga-67, so we studied 32 biopsy proven lymphoma patients (male 24, female 8, mean age 46 years) with Ga-67, Tl-201 or Tc-99m MIBI and compared the scan findings. MATERIALS AND METHODS: Twenty-three of 32 patients were injected 74-111 MBq (2-3 mCi) of Tl-201, before chemotherapy and imaged with dual-headed SPECT (Prism 2000, Picker, USA) at 30 minutes after injection. Delayed images were obtained after 3 hr in 8 patients. Twenty seven of 32 patients were injected 740 MBq (20 mCi) of Tc-99m MIBI and imaged at 30 minutes after injection. 111-185 MBq (3-5 mCi) of Ga-67 was injected in 12 patients and imaged at 48 and 72 hours after injection. Twenty eight patients were diagnosed as non-Hodgkin's lymphoma and others were Hodgkin's lymphoma. RESULTS: Twenty patients were positive on Tl-201 scan and 3 patients showed negative findings. One of these 3 patients, Tc-99m MIBI and Ga-67 scan were positive. Twenty two patients were positive on Tc-99m MIBI scan and 5 patients showed negative findings. One of these 5 patients, Tl-201 was positive and 2 were positive on Ga-67 scan. Ten of 12 patients showed positive findings on Ga-67 scan. The sensitivity of these agents were 83.3%, 87.0% and 81.5% for Ga-67, Tl-201 and Tc-99m MIBI, respectively. The sensitivity was highest in Tl-201 scan, but there were no significant differences among three tests. In this study, there was no significant difference of uptake ratios between early and delayed images of Tl-201. CONCLUSION: Scintigraphy with Tl-201 and Tc-99m MIBI in lymphoma patients have similar sensitivity with Ga-67.

Evaluation of Treatment Response & Recurrence in Childhood Solid Tumor with Thallium Scan / 대한소아혈액종양학회지

PURPOSE: During the follow-up period of the patient who was diagnosed as rhabdomyosarcoma and treated between 1991 and 1992 in Kyungpook National University Hospital (KNUH), the residual mass lesion on computerizing tomography (CT) was suspected as tumor progress. But, it was diagnosed as necrotic tissue by excisional biopsy and he has survived without recurrence until now. So, we have the necessity of the method that is able to differentiate the remnant tumor with necrotic tissue during or after treatment. The objective of this study was to evaluate prospectively the effectiveness of thallium (Tl-201) scan in detecting the bioavailability of tumor at diagnosis and after treatment. METHODS: CT and/or magnetic resonance imaging (MRI) and Tl-201 scan at diagnosis, during the treatment and after treatment were conducted in 19 solid tumor patients treated for their diseases from December 1996 to June 1998, in Pediatric Department of KNUH. And we evaluated the recurrence of solid tumors following them up to March 2001. RESULTS: In the cases of the presence of solid tumor in CT or MRI at diagnosis, we could also find them on Tl-201 scan in all of them. During the treatment, PNET patient had the mass lesion on MRI and Tl-201 scan, we kept going on the chemotherapy and radiotherapy. And retinoblastoma patient also had continued chemotherapy after confirming the mass lesion on MRI, not Tl-201 scan. Six cases (alveolar soft part sarcoma, medulloblastoma, Ewing sarcoma, Non-Hodgkin's lymphoma, rhabdomyosarcoma, neuroblastoma) in which no mass lesion were found in CT or MRI and Tl-201 scan had their final therapy. After finishing the treatment, high-grade anaplastic astrocytoma patient confirmed the mass lesion on MRI and Tl-201 scan and expired irrespective of retreatment after 19 months of diagnosis. In 2 cases of solid tumor on CT scan, not on Tl-201 scan, germ cell tumor patient has been followed up until now without recurrence with normal alpha-FP level, and NHL patient has survived without recurrence. Four cases (Non-Hodgkin's lymphoma; 2 cases, medulloblastoma; 1 case, ependymoma; 1 case) with negative finding on CT or MRI and Tl-201 scan also has survived without recurrence. CONCLUSION: Although CT or MRI is used commonly in the follow-up period of childhood solid tumor, Tl-201 scan can be the useful method of differentiating viable tumor with necrotic tissue in the view of cost-effectiveness and availability.

Effects of Pinacidil, a Potassium-Channel Opener, on Biodistribution of Thallium-201 in Tumor-Bearing Mice / 대한핵의학회잡지

PURPOSE: Thallium behaves similarly to potassium in vivo. Potassium channel opener (K-opener) opens ATP-sensitive K+/-channel located at cell membrane, resulting in potassium efflux from cytosol. We have previously reported that K-opener can alter biokinetics of Tl-201 in cultured cells and in vivo. Malignant tumor cells have high Na-K ATPase activity due to increased metabolic activities and dedifferentiation, and differential delineation of malignant tumor can be possible with Tl-201 imaging. K-opener may affect tumoral uptake of Tl-201 in vivo. To investigate the effects of pinacidil (one of the potent K-openers) on the localization of the tumor with Tl-201 chloride, we evaluated the changes in biodistribution of Tl-201 with pinacidil treatment in tumor-bearing mice. MATERAL AND METHODS: Balb/c mice received subcutaneous implantation of murine breast cancer cells in the thigh and were used for biodistribution study 3 weeks later. 100 microgram of pinacidil dissolved in 200 microliter DMSO/PBS solution was injected intravenously via tail vein at 10 min after 185 KBq (5 microcurie) Tl-201 injection. Percentage organ uptake and whole body retention ratio of Tl-201 were measured at various periods after injection, and values were compared between control and pinacidil-treated mice. RESULTS: Pinacidil treatment resulted in mild decrease in blood levels of Tl-201, but renal uptakes were markedly decreased at 30-min, 1- and 2-hour, compared to control group. Hepatic, intestinal and muscular uptake were not different. Absolute percentage uptake and tumor to blood ratios of Tl-201 were lower in pinacidil treated mice than in the control group at all time points measured. Whole body retention ratio of Tl-201 was lower in pinacidil treated mice (58+/-4%), than in the control group (67+/-3%) at 24 hours after with injection of 100 microgram pinacidil. CONCLUSION: K-opener did not enhance, but rather decreased absolute tumoral uptake and tumor-to-blood ratios of Tl-201. Decreased whole body retention ratio and renal uptake were observed with pinacidil treatment in tumor-bearing mice.

Decreased QTc dispersion after coronary revascularization: relationships with the quantitative degree of improvement in myocardial ischemia

OBJECT & METHOD: Thirty-four patients (mean age: 58.1+/-8.3 years, M:F=1:13) with angina in the absence of previous myocardial infarction, who underwent percutaneous coronary intervention (stenting and/or balloon PTCA, n=5) or coronary arterial bypass grafting (CABG, n=) were evaluated to assess the relationships between the degree of improvement in myocardial dipyridamole Tl-201 SPECT and the degree of decrease in QTc dispersion after coronary revascularization. QTc dispersions were measured manually using digitizer by a single observer from ECGs printed at 25mm/sec, 1 day before, immediately, 1 day, and 1 month after the revascularization procedure. Myocardial Tl-201 SPECTs were performed before and 1 month after the revascularization and ischemic indices were measured in all cases. RESULTS: Mean QTc dispersion was 51.4+/-17.0msec before revascularization, 42.6+/-15.1msec immediately after, 45.6+/-19.3msec 1 day after and 37.4+/-11.6msec 1 month after revascularization. The decrease of QTc dispersion immediate (p=.001) and 1 month (p<0.001) after revascularization, were statistically significant. Mean Tl-201 SPECT ischemic index measured before the revascularization (7.8+/-5.9) was significantly higher (p<0.001) than the one measured 1 month after the revascularization (1.5+/-2.8). But, in deltaischemic index (ischemic index before revascularization-ischemic index 1 month afer revascularization), there was no significant difference between the patients with decrease in QTc dispersion after revascularization(6.2+/-6.3, n=7) and the patients without decrease in QTc dispersion (6.6+/-5.2, n=). There was no statistically significant correlation between deltaQTc (QTc dispersion before revascularization-QTc dispersion 1 month afer revascularization) and delta ischemic index in total subjects. CONCLUSION: QTc dispersions decrease after successful coronary revascularizations in patients with angina, but considering the relationships between the changes of QTc dispersions and ischemic indices in myocardial dipyridamole Tl-201 SPECT, the degree of decrease in QTc dispersion after coronary revascularization does not have the relationships with the quantitative degree of improvement in myocardial ischemia.

Decreased QTc dispersion after coronary revascularization: relationships with the quantitative degree of improvement in myocardial ischemia

OBJECT & METHOD: Thirty-four patients (mean age: 58.1+/-8.3 years, M:F=1:13) with angina in the absence of previous myocardial infarction, who underwent percutaneous coronary intervention (stenting and/or balloon PTCA, n=5) or coronary arterial bypass grafting (CABG, n=) were evaluated to assess the relationships between the degree of improvement in myocardial dipyridamole Tl-201 SPECT and the degree of decrease in QTc dispersion after coronary revascularization. QTc dispersions were measured manually using digitizer by a single observer from ECGs printed at 25mm/sec, 1 day before, immediately, 1 day, and 1 month after the revascularization procedure. Myocardial Tl-201 SPECTs were performed before and 1 month after the revascularization and ischemic indices were measured in all cases. RESULTS: Mean QTc dispersion was 51.4+/-17.0msec before revascularization, 42.6+/-15.1msec immediately after, 45.6+/-19.3msec 1 day after and 37.4+/-11.6msec 1 month after revascularization. The decrease of QTc dispersion immediate (p=.001) and 1 month (p<0.001) after revascularization, were statistically significant. Mean Tl-201 SPECT ischemic index measured before the revascularization (7.8+/-5.9) was significantly higher (p<0.001) than the one measured 1 month after the revascularization (1.5+/-2.8). But, in deltaischemic index (ischemic index before revascularization-ischemic index 1 month afer revascularization), there was no significant difference between the patients with decrease in QTc dispersion after revascularization(6.2+/-6.3, n=7) and the patients without decrease in QTc dispersion (6.6+/-5.2, n=). There was no statistically significant correlation between deltaQTc (QTc dispersion before revascularization-QTc dispersion 1 month afer revascularization) and delta ischemic index in total subjects. CONCLUSION: QTc dispersions decrease after successful coronary revascularizations in patients with angina, but considering the relationships between the changes of QTc dispersions and ischemic indices in myocardial dipyridamole Tl-201 SPECT, the degree of decrease in QTc dispersion after coronary revascularization does not have the relationships with the quantitative degree of improvement in myocardial ischemia.

Usefulness of 201Tl Myocardial Perfusion SPECT in Prediction of Left Ventricular Remodeling following an Acute Myocardial Infarction / 대한핵의학회잡지

PURPOSE: We investigated the role of myocardial perfusion SPECT in prediction of ventricular dilatation and the role of revascularization including thrombolytic therapy and PTCA in prevention of ventricular dilatation after an acute myocardial infarction (AMI). MATERIALS AND METHODS: We performed dipyridamole stress, 4 hour redistribution, and 24 hour reinjection Tl-201 SPECT in 16 patients with AMI two to nine days after attack. Perfusion and wall motion abnormalities were quantified by perfusion index (PI) and wall motion index (WMI). Left ventricular ejection fraction (LVEF), WMI and ventricular volume were measured within 1 week of AMI and after average of 6 months. According to serial changes of left ventricular end-diastolic volume (LVEDV), patients were divided into two groups. We compared WMI, PI and LVEF between the two groups. Relationships among degree of volume, stress-rest PI, WMI, CKMB, Q wave, LVEF and revascularization were analysed using multivariate analysis. RESULTS: Only initial rest perfusion index was significantly different between the two groups (p<0.05). While initial LVEF, stress PI, CKMB, trial of revascularization procedure, presence of Q wave and WMI were not significantly different between the two groups. Eight of 16 patients (50%) showed LV dilatation on follow-up echocardiography. Three of 3 patients (100%) who did not undergo revascualrization procedure documented LV dilatation. And only 5 (38%) of the remaining 13 patients who underwent revascularization revealed LV dilatation. There was no difference in infarct location between the two groups. By multivariate linear regression analysis in patients only undergoing revascularization, rest perfusion index was the only significant factor. CONCLUSION: Myocardial perfusion SPECT performed prior to revascularization was useful in prediction of LV dilatation after an AMI. Rest perfusion index on myocardial perfusion plays as a significant predictor of left ventricular dilatation after AMI. And revascularization appears to be a valuable procedure in alleviating LV dilatation after AMI with or without viable myocardium in a limited number of patients studied retrospectively.

Dual-Isotope SPECT Imaging with Thallium-201 and Technetium-99m MIBI in Detecting Coronary Artery Disease / 영남의대학술지

We evaluated the results of sequential SPECT dual-isotope imaging with Tl-201 and Tc-99m MIBI in 24 patients, all of whom also had coronary angiography within the past one month. Coronary angiography showed that 12 patients had no CAD, 4 patients had one-vessel CAD, 7 patients had two-vessel CAD and 1 patient had three-vessel CAD. Serial studies of resting Tl-201 and dipyridamole stress Tc-99m MIBI were completed within 2 hours. When more then 50% of coronary artery narrowing was considered significant. The overall sensitivity and specification of CAD detection were 91.7%. The sensitivity of CAD detection in patients with one-vessel and multi-vessel diseases was 75% and 100%, respectively. Therefore, sequential dual-isotope SPECT demonstrated high sensitivity and specificity of CAD detection. In conclusion, sequential dual-isotope imaging is feasible and can be completed in a short time and may therefore enhance laboratory throughput and patient convenience.

Dipyridamole Tl-201 SPECT in Hypertrophic Cardiomyopathy with Asymmetric Septal Hypertrophy:Characteristics of Perfusion Abnormality and Correlation with Clinical Parameters

BACKGROUND AND OBJECTIVES: Exercise myocardial perfusion scans in patients with hypertrophic cardiomyopa-thy have shown reversible perfusion abnormalities with unknown clinical significance. We performed this study to characterize dipyridamole Tl-201 SPECT imaging and correlate with clinical findings in patients with hyper-trophic cardiomyopathy. METHODS: Tl-201 SPECT was performed in 25 patients of hypertrophic cardiomyopa-thy with asymmetric septal hypertrophy and 20 normal controls after dipyridamole infusion (0.56 mg/kg). Myocardial wall was divided into 8 segments. Tl-201 uptake and relative washout rate were calculated. RESULTS: Tl-201 SPECT showed significantly lower Tl-201 uptake in basal septal (81.3+/-3.4% vs 78.2+/-6.4%, p<0.05) and apical septal wall on stress (88.2+/-4.7% vs 83.9+/-6.5%, p<0.05) and higher apical septal (86.6+/-5.2% vs 89.2+/-3.1%, p<0.05) and apical anterior wall uptake (88.7%+/-4.0% vs 91.4+/-4.9%, p<0.05) on redistribution images in patients with hypertrophic cardiomyopathy. Basal lateral wall uptake of hypertrophic cardiomyopathy was significantly lower than normal control on both stress (84.7+/-3.5% vs 81.2+/-7.3%, p<0.05) and redistribution images (85.0+/-5.8% vs 76.8+/-7.2%, p<0.0001). The septum/lateral uptake ratio of patients on rest image was significantly higher than that of normal controls (0.98+/-0.07 vs 1.07+/-0.10, p<0.001). There was no difference in age, sex, symptom, cardiac medication and the parameters of 2D-echo including left ven-tricular outflow obstruction between subgroups of normal vs abnormal washout in patients with hypertrophic cardiomyopathy. CONCLUSION: Dipyridamole Tl-201 myocardial SPECT shows reduced coronary vasodilatory capacity of myocardium, especially septum in patients with hypertrophic cardiomyopathy. High septal/lateral uptake ratio on redistribution image may be a characteristic finding. However, no correlation between abnorm-al Tl-201 washout and clinical findings was observed.

Comparison of Thallium-201, Tc-99m MIBI and I-131 Scan in the Follow-up Assessment after I-131 Ablative Therapy in Differentiated Thyroid Cancer / 대한핵의학회잡지

PURPOSE: We conducted a comparative study to evaluate the diagnostic values of Tl-201, Tc-99m MIBI and I-131 scans in the follow-up assessment after ablative I-131 therapy in differentiated thyroid cancer. MATERIALS AND METHODS: The study population consisted of 20 patients who underwent surgical removal of thyroid cancer and ablative radioactive iodine therapy, and followed by one or more times of I-131 retreatments (33 cases). In all patients, Tl-201, Tc-99m MIBI, diagnostic and therapeutic I-131 scans were performed and the RESULTS were analyzed retrospectively. Also serum thyroglobulin levels were measured in all patients. The final diagnosis of recurrent or metastatic thyroid cancer was determined by clinical, biochemical, radiologic and/or biopsy findings. RESULTS: Positive rates (PR) of Tc-99m MIBI, Tl-201, diagnostic and therapeutic I-131 scans in detecting malignant thyroid tissue lesions were 70% (19/27), 54% (15/28), 35% (17/48) and 63% (30/48), respectively. The PR in the group of 20 cases (28 lesions) who underwent concomitant Tl-201 and I-131 scans were in the order of therapeutic 131 scan 71%, Tl-201 scan 54% and diagnostic I-131 scan 36%. There was no statistically significant difference between Tl-201 and diagnostic I-131 scans (p>0.05). In the group of 20 cases (27 lesions) who underwent concomitant Tc-99m MIBI and I-131 scans, the PR were in the order of Tc-99m MIBI scan 70%, I-131 therapeutic scan 52% and I-131 diagnostic scan 33%. The PR of Tc-99m MIBI was significantly higher than that of diagnostic I-131 scan (p<0.05). CONCLUSION: Tc-99m MIBI scan is superior to diagnostic I-131 scan in detecting recurrent or metastatic thyroid cancer following ablation therapy in patients with differentiated thyroid cancer. Tl-201 scan did not showed significantly higher positive rate than diagnostic I-131 scan. Instead of diagnostic I-131 scan before the I-131 retreatment, Tc-99m MIBI scan without discontinuing thyroid hormone replacement would be a prudent and effective approach in the management of these patients.

The Usefulness of Myocardial SPECT for the Preoperative Cardiac Risk Evaluation in Noncardiac Surgery / 대한핵의학회잡지

PURPOSE: We investigated whether myocardial SPECT had additional usefulness to clinical, functional or surgical indices for the preoperative evaluation of cardiac risks in noncardiac surgery. MATERIALS AND METHODS: 118 patients (M: F=66:52, 62.7+/-10.5 years) were studied retrospectively. Eighteen underwent vascular surgeries and 100 nonvascular surgeries. Rest T1-201/stress Tc-99m-MIBI SPECT was performed before operation and cardiac events (hard event: cardiac death and myocardial infarction; soft event: ischemic ECG change, congestive heart failure and unstable angina) were surveyed through perioperative periods (14.6+/-5.6 days). Clinical risk indices, functional capacity, surgery procedures and SPECT findings were tested for their predictive values of perioperative cardiac events. RESULTS: Peri-operative cardiac events occurred in 25 patients (3 hard events and 22 soft events). Clinical risk indices, surgical procedure risks and SPECT findings but functional capacity were predictive of cardiac events. Reversible perfusion decrease was a better predictor than persistent decrease. Multivariate analysis sorted` out surgical procedure risk (p=0.0018) and SPECT findings (p=0.0001) as significant risk factors. SPECT could re-stratify perioperative cardiac risks in patients ranked with surgical procedures. CONCLUSION:: We conclude that myocardial SPECT provides additional predictive value to surgical type risks as well as clinical indexes or functional capacity for the prediction of preoperative cardiac events in noncardiac surgery.

Predictive Values of Early Rest / 24 Hour Delay Perfusion SPECT for Wall Motion Improvement in Patients with Acute Myocardial Infarction After Reperfusion / 대한핵의학회잡지

PURPOSE: We studied early rest/24 hour delay Tl-201 perfusion SPECT for prediction of wall motion improvement after reperfusion in patients with acute myocardial infarction. MATERIALS AND METHODS: Among 17 patients (male/female ll/6, age: 59+13) with acute myocardial infarction, 15 patients were treated with percutaneous transcoronary angioplasty (direct:2, delay:11) and intravenous urokinase (2). Spontaneous resolution occurred in infarct-related arteries of 2 patients. We confirmed TIMI 3 flow of infarct-related artery after reperfusion in all patients with coronary angiography. We performed rest Tl-201 perfusion SPECT less then 6 hours after reperfusion and delay Tl-201 perfusion SPECT next day. Tl-201 uptake was visually graded as 4 point score from norrnal (0) to severe defect (3). Rest Tl-201 uptake 1 grade in follow up echo compared with the baseline values. RESULTS: Among 98 segments with wall rnotion abnormality, the severity of myocardial wall motion decrease was as follow: mild hypokinesia: 18/98 (18%), severe hypokinesia: 28/98 (29%), akinesia: 5l/98 (52%), dyskinesia: 1/98 (1%), The wall rnotion improved in 85%. Redistribution (13%), and reverse redistribution (4%) were observed in 24 hour delay SPECT. Positive predictive value (PPV) and negative predictive value (NPV) of combination of late reversibility and rest Tl-201 uptake were 99%, and 54%. PPV and NPV of rest T1-201 uptake were 100% and 52% respectively. Predictive values of combination of rest Tl-201 uptake and late reversibility were not significantly different compared with predictive values of rest Tl-201 uptake only. CONCLUSION: We conclude that early Tl-201 perfusion SPECT predict myocardial wall motion improvement with excellent positive but relatively low negative predictive values in patients with acute myocardial infarction after reperfusion.