The Benefits of Prone SPECT Myocardial Perfusion Imaging in Reducing Both Artifact Defects and Patient Radiation Exposure / Benefício da Aquisição de Imagem na Posição Prona em Perfusão Miocárdica com SPECT para Redução de Artefatos e Exposição do Paciente à Radiação

AbstractBackground:Prone imaging has been demonstrated to minimize diaphragmatic and breast tissue attenuation.Objectives:To determine the role of prone imaging on the reduction of unnecessary rest perfusion studies and coronary angiographies performed, thus decreasing investigation time and radiation exposure.Methods:We examined 139 patients, 120 with an inferior wall and 19 with an anterior wall perfusion defect that might represented attenuation artifact. Post-stress images were acquired in both the supine and prone position. Coronary angiography was used as the “gold standard” for evaluating coronary artery patency. The study was terminated and rest imaging was obviated in the presence of complete improvement of the defect in the prone position. Quantitative interpretation was performed. Results were compared with clinical data and coronary angiographic findings.Results:Prone acquisition correctly revealed defect improvement in 89 patients (89/120) with inferior wall and 12 patients (12/19) with anterior wall attenuation artifact. Quantitative analysis demonstrated statistically significant difference in the mean summed stress scores (SSS) of supine and mean SSS of prone studies in patients with disappearing inferior wall defect in the prone position and patent right coronary artery (true negative results). The mean difference between SSS in supine and in prone position was higher with disappearing than with remaining defects.Conclusion:Technetium-99m (Tc-99m) tetrofosmin myocardial perfusion imaging with the patient in the prone position overcomes soft tissue attenuation; moreover it provides an inexpensive, accurate approach to limit the number of unnecessary rest perfusion studies and coronary angiographies performed.

ResumoFundamento:Já foi demonstrado que a imagem na posição prona minimiza a atenuação dos tecidos diafragmáticos e da mama.Objetivos:Determinar o papel da imagem na posição prona na redução de estudos de perfusão em repouso e angiografias coronárias realizadas de forma desnecessária, assim diminuindo o tempo de investigação e exposição à radiação.Métodos:Foram examinados 139 pacientes, 120 com um defeito de perfusão da parede inferior e 19 com defeito de perfusão da parede anterior que pudessem representar um artefato de atenuação. Imagens pós-estresse foram adquiridas nas posições supina e prona. A angiografia coronária foi usada como o “padrão ouro” para avaliar a patência da artéria coronária. O estudo foi encerrado e a imagem em repouso não foi necessária na presença de melhoria completa do defeito na posição prona. Uma interpretação quantitativa foi realizada. Os resultados foram comparados com os dados clínicos e achados angiográficos.Resultados:A aquisição de imagem na posição prona revelou corretamente a melhoria do defeito em 89 pacientes (89/120) com artefato de atenuação na parede inferior e 12 pacientes (19/12) na parede anterior. A análise quantitativa demonstrou diferença estatisticamente significante nas somas dos escores de estresse (SSS) médios nos estudos da posição supina e SSS médios dos estudos na posição prona em pacientes com desaparecimento do defeito da parede inferior na posição prona e artéria coronária patente (resultados negativos verdadeiros). A diferença média dos SSS nas posições supina e prona foi maior com os defeitos desaparecidos do que com os que permaneceram.Conclusão:A cintilografia de perfusão miocárdica com Tecnécio-99m (Tc-99m) tetrofosmin com o paciente na posição prona supera a atenuação de tecidos moles; Além disso, oferece uma abordagem precisa e de baixo custo para limitar o número de estudos de perfusão em repouso e realização de angiografias coronárias desnecessárias.

Clinical Significance of Reverse Redistribution Phenomenon on Delayed Tc-99m Tetrofosmin Myocardial Perfusion Imaging in Patients with Acute Myocardial Infarction / 핵의학분자영상

PURPOSE: This study was performed to investigate the clinical significance of reverse redistribution (RR) phenomenon detected on delayed Tc-99m tetrofosmin myocardial single photon emission computed tomography (SPECT) in patients with acute myocardial infarction after revascularization. MATERIALS AND METHODS: A Tc-99m tetrofrosmin myocardial SPECT was performed in 67 consecutive patients after revascularization for acute myocardial infarction. Myocardial SPECT imaging was performed for early imaging at 40 min and for delayed imaging at 180 min after reinjection at myocardial stress. Regional myocardial uptakes were scored by 4-point scoring in the left ventricular wall divided into 17 segments. Reverse redistribution was defined as an increase of more than 2 point in the activity score on the delayed image. Follow-up myocardial SPECT and coronary angiography (CAG) were performed 9 months later. RESULTS: On myocardial SPECT performed following revascularization, RR was observed in 100 of all 319 segments (31%) and in 43 patients (64%). The abnormalities of perfusion and regional wall motion were more severe in the patients with RR compared to those without RR (p<0.05). On follow-up myocardial SPECT, the myocardial perfusion, regional wall motion, and myocardial thickness were significantly improved in the patients with RR (p<0.05) however, these changes were not significant in those without RR. There was no significant difference between the patients with RR and those without RR in the occurrence of restenosis on CAG. CONCLUSIONS: In patients with acute myocardial infarction, the regions showing the RR phenomenon on delayed Tc-99m tetrofosmin SPECT may reflect viable myocardium and indicate recovery of salvaged myocardium.

The Clinical Efficacy of Lung to Heart Ratio in 1 Hour Delayed Tc-99m Tetrofosmin Gated Myocardial SPECT after Adenosine Stress: Comparison with Coronary Angiography / 핵의학분자영상

PURPOSE: It is well known that lung to heart ratio (LHR) is one of the high risk findings in Tl-201 myocardial perfusion SPECT. We evaluated the clinical efficacy of LHR to identify severe coronary artery disease in adenosine stress Tc-99m tetrofosmin gated myocardial perfusion SPECT (gSPECT). MATERIALS AND METHODS: The study population was 157 patients who underwent both adenosine stress Tc-99m gSPECT and coronary angiography (CAG) within one month. According to the results of CAG and gSPECT LHR and the incidence of increased LHR were compared. RESULTS: Among 53 patients with normal coronary arteries increased LHR was found in 2 patients (3.8%) and 0 in 44 patients (0%) with one vessel disease, 2 in 27 with two vessel disease (7.4%) and 8 in 33 with triple vessel disease (24.2%). Significant differences were found in LHR between subgroups of summed stress score, summed rest score and LV ejection fraction (LVEF). There were weak negative correlation between LHR and LVEF and weak positive correlation between LHR and SSS and SRS. CONCLUSION: Increased LHR had higher incidence in patients with triple vessel disease, severe LV dysfunction and/or extensive perfusion defect than those of normal group. Although its sensitivity might be low to identify severe coronary artery disease, LHR could be helpful in abnormal myocardial perfusion SPECT to stratify risk and prognosis.

Analysis of Myocardial Function Using Gated Myocardial SPECT : Comparison of QGS, 4D-MSPECT Software and Echocardiography / 핵의학분자영상

PURPOSE: Gated myocardial perfusion SPECT provides not only myocardial perfusion status but also various functional parameters of left ventricle. We compared left ventricular ejection fraction, end-diastolic volume, LV mass by cardiac SPECT using Quantitative Gated SPECT (QGS), 4D-MSPECT software and standard 2D-echocardiography. MATERIALS AND METHODS: One hundred fourteen patients (male 51, female 63; 29-85 years old, mean 61.3+/-13.3 years old) with normal perfusion status on Tc-99m tetrofosmin gated myocardial perfusion SPECT were analyzed retrospectively. Ejection fraction (LVEF), End-diastolic volume (LVED), LV mass (LVM) were calculated using QGS, 4D-MSPECT, and LVEF, LVM using 2D-echocardiography. Statistical analysis including Bland-Altman plot was performed using MedCalc(R) (MedCalc software, Mariakerke, Belgium). RESULTS: The correlation of LVEF between methods was good: 0.95/0.96 (stress/rest) between QGS and 4D-MSPECT, 0.79 between QGS and echocardiography, 0.79 between 4D-MSPECT and echocardiography (p<0.001). Using Bland-Altman plot, the 95% confidence interval of agreement between QGS and 4D-MSPECT ranged from -12.7% to 7.3% / from -12.2% to 6.5% (stress/rest). The agreement between QGS and echocardiography, 4D-MSPECT and echocardiography ranged from -17.4% to 24.0%, and -14.8% to 27.0% respectively. The correlation of LVM between methods was also good: 0.95 between QGS and 4D-MSPECT, 0.76 between QGS and echocardiography, 0.73 between 4D-MSPECT and echocardiography (p<0.001). The 95% confidence interval of agreement between QGS and 4D-MSPECT ranged from -33.8 g to 14.1 g (stress/rest). The 95% confidence interval of agreement between QGS and echocardiography, 4D-MSPECT and echocardiography ranged from -148.7 g to 21.8. g, and -142.8 g to 35.5 g, respectively. CONCLUSION: There was a good correlation for LVEF, LVED, LVM among methods (QGS, 4D-MSPECT, echocardiography), but the variance between methods was big. Therefore, the functional parameters by each method cannot be used interchangeably.

Detection of Occult Thymoma Using Tc-99m tetrofosmin Scintigraphy / 핵의학분자영상

Tetrofosmin is a ligand that forms a lipophilic, cationic complex with Tc-99m.1) Tc-99m tetrofosmin was developed as a myocardial perfusion imaging agent and also used to depict tumors.1-3) Mediastinal tumors is also detected by Tc-99m tetrofosmin.2-5) We report a case of extracardiac mediastinal activity detected by Tc-99m tetrofosmin scintigraphy, which revealed thymoma.

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.

Diagnostic Accuracy of Quantitative Scintimammography Using Tc-99m Tetrofosmin according to ROC Curve Analysis for Breast Cancer / 한국유방암학회지

PURPOSE: Tc-99m Tetrofosmin is a new alternative to Tc- 99m MIBI for nuclear breast imaging. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the feasibility of Tc-99m Tetrofosmin quantitative scintimammography (SMM) (qSMM) and to compare with previously reported Tc-99m MIBI qSMM data [J Kor Surg 1999;57(5):638-644)]. METHODS: Prone anterior, lateral planar and supine SPECT images were taken from 135 cases in 131 female patients (mean ages=44 yr) with breast mass (size> or =0.2 cm) after 30mCi intravenous injection of Tc-99m Tetrofosmin. 70 malignant and 65 benign lesions were histologically proven. Three regions of interest (ROIs) were drawn over designated areas: the Lesion (L), the Normal breast opposite the lesion (NL) and the right Chest wall (CW). L/NL and L/CW ratios on both the SPECT and the planar images were analyzed. RESULTS: ROC curve analysis revealed that the planar L/NL ratio and the SPECT L/NL and L/CW ratios had higher diagnostic accuracy for detecting breast cancer than he planar L/CW ratio did (P<0.05). The qSMM (mean), which is an arithmetic mean of the planar L/NL ratio, the SPECT L/NL ratio and the SPECT L/CW ratio, the sensitivity, the specificity, accuracy and area under curve (AUC) were 82.9%, 81.5%, 82.2% and 0.879 respectively. Presence of axillary lymph node metastasis showed a slightly higher qSMM (mean) value (2.79 {n=23} vs 2.75 {n=27} P=0.06). These are comparable with previously reported Tc-99m MIBI qSMM data of 84.4%, 76.6%, 81.0% and 0.847 respectively, and the presence of axillary lymph node metastasis showed a higher qSMM(mean) value (4.09 {n=17} vs 3.09 {n=28}, P=0.06) [J Kor Surg 1999; 57(5):638-644)]. CONCLUSION: Tc-99m Tetrofosmin qSMM (mean) is a useful and objective method for differentiating malignant from benign breast lesion and has the comparable diagnostic accuracies of Tc-99m MIBI qSMM.

Comparison of the Uptakes of Tc-99m MIBI and Tc-99m Tetrofosmin in A549, an MRP-expressing Cancer Cell, In Vitro and In Vivo / 대한핵의학회잡지

PURPOSE: Uptakes of Tc-99m MIBI (MIBI) and Tc-99m tetrofosmin (tetrofosmin) in human non-small cell lung cancer A549, multidrug-resistance associated protein (MRP) expressing cell, were investigated in vitro and in vivo. MATERIALS AND METHODS: Western blot analysis and immunohistochemistry were used for detection of MRP in A549 cells with anti-MRPr1 antibody. Cellular uptakes of two tracers were evaluated at 100 umM of verapamil (Vrp), 50 umM of cyclosporin A (CsA) and 25 umM of butoxysulfoximide (BSO) after incubation with MIBI and tetrofosmin for 30 and 60 min at 37degrees C, using single cell suspensions at 1x10 (6) cells/ml. Radioactivities in supernatants and pellets were measured with gamma well counter. A549 cells were inoculated in each flanks of 24 nude mice. Group 1 (Gr1) and Gr3 mice were treated with only MIBI or tetrofosmin, and Gr2 and Gr4 mice were treated with 70mg/kg of CsA i.p. for 1 hour before injection of 370KBq of MIBI or tetrofosmin. Mice were sacrificed at 10, 60 and 240 min. Radioactivities of organs and tumors were expressed as percentage injected dose per gram of tissue (%ID/gm). RESULTS: Western blot analysis of the A549 cells detected expression of MRPr1 (190 kDa) and immunohistochemical staining of tumor tissue for MRPr1 revealed brownish staining in cell membrane but not P-gp. Upon incubating A549 cells for 60 min with MIBI and tetrofosmin, cellular uptake of MIBI was higher than that of tetrofosmin. Coincubation with modulators resulted in an increase in cellular uptakes of MIBI and tetrofosmin. Percentage increase of MIBI was higher than that of tetrofosmin with Vrp by 623% and 427%, CsA by 753% and 629% and BSO by 219% and 140%, respectively. There was no significant difference in tumoral uptakes of MIBI and tetrofosmin between Gr1 and Gr3. Percentage increases in MIBI (114% at 10 min, 257% at 60 min, 396% at 240 min) and tetrofosmin uptake (110% at 10 min, 205% at 60 min, 410% at 240 min) were progressively higher by the time up to 240 min with CsA. CONCLUSION: These results indicate that MIBI and tetrofosmin are suitable tracers for imaging MRP-mediated drug resistance in A549 tumors. MIBI may be a better tracer than tetrofosmin for evaluating MRP reversal effect of modulators.

Comparison of Tc-99m-Tetrofosmin and Tc-99m-MIBI Scintimammography in Differential Diagnosis of Breast Mass / 대한핵의학회잡지

PURPOSE: Tc-99m-MIBI (MIBI) and Tc-99m-Tetrofosmin (TF) are commonly used for scintimammography (SMM). We compared the diagnostic ability of SMM using Tc-99m-MIBI and Tc-99m-TF for the differential diagnosis of breast mass. MATERIALS AND METHODS: The study subjects were comprised of 123 breast lesions and 86 normal breasts of 114 patients who underwent SMM. Bilateral prone images and anterior supine images were obtained at 5 minutes and 1 or 3 hours after intravenous injection of 740 MBq of either MIBI or TF. Sizes of tumors were not significantly different between the MIBI and TF groups. First, two observers independently read the SMM without clinical information (1st interpretation), then read again with information about mass location (2nd interpretation). Sensitivity and specificity of each radiopharmaceutical for the diagnosis of breast cancer were evaluated in terms of image acquisition time, tumor size, and location. RESULTS: The SMM showed a good agreement between two observers for 1st and 2nd interpretation, except for TF SMM at 3 hr. For the first interpretation, the sensitivities at 5 min, 1 hr, and 3 hr were not significantly different between MIBI and TF SMM (81.6%, 80.0%, 60.9% in MIBI vs. 88.9%, 80.6%, 42.9% in TF), although the senstivities of 3 hr images were significantly lower than 5 min images in both MIBI and TF SMM. The specificity of TF at 5 min was superior to that of MIBI (81.5%, 90.0%, 82.9% in MIBI vs. 96.7%, 100%, 90.0% in TF, p<0.01 MIBI vs. TF at 5 min). For the second interpretation with information of mass location, the sensitivities at 3 hr images were significantly lower than 5 min images (86.8%, 86.7%, 78.3% in MIBI vs. 88.9%, 93.5%, 57.1% in TF) between MIBI and TF SMM. However, there was no significant difference in the specificity (60.0%, 53.8%, 75.0% for MIBI vs. 86.7%, 100%, 100% for TF). MIBI and TF SMM showed lower sensitivities for the tumors with less than 1 cm than tumors with more than 1 cm. However, the location of tumors did not influence the sensitivity and specificity between MIBI and TF SMM. CONCLUSION: The ability for the differential diagnosis of breast tumor is similar between MIBI and TF SMM, and delayed image is not necessary. TF may be better than MIBI considering the specificity of SMM without clinical information and labeling convenience.

Diagnostic Usefulness of Tc-99m Tetrofosmin Scintimammography in Patients with Primary Breast Cancer / 대한핵의학회잡지

PURPOSE: The purpose of this study was to evaluate the diagnostic usefulness of scintimammography performed with Tc-99m tetrofosmin in the detection of primary breast cancer. MATERIALS AND METHODS: Sixty-one patients underwent Tc-99m tetrofosmin scintimammography, plain-filrn mammography and ultrasonography. After intravenous injection of Tc-99m tetrofosmin (740 MBq), prone lateral and anterior scintimammograms were obtained. Scintimammogram was visually interpreted as positive, probably positive, probably negative and negative for malignancy. The tumor to background count ratio (T/B) was measured at 5 minutes and 1 hour. Plain-film mammogram was interprcted as one of 5 categories. Final diagnosis was achieved by surgical histology (58/61) or fine needle aspiration (3/61). Of 61 patients, 44 had cancer and 17 had benign lesion. Tumor size of malignant and benign lesions on ultrasonogram were 2.51+/-1.30 cm (range 1-8 cm), 2.50+/-1.35 cm (range 0.96-6 cm), respectively. RESULTS: The sensitivity of plain-film mammography was 88.6%, specificity 58.8%, positive predictive value 84.7%, and negative predictive value 66.7%. The sensitivity of Tc-99m tetrofosmin scintimammography was 90.9%; specificity, 88.2%; positive predictive value, 94.9%; negative predictive value, 78.9%. Of 25 patients with indeterminate degree of suspicion for malignancy on plain-film mammogram, 23 were correctly diagnosed by scintimamography. The T/B at 5 minutes and 1 hour were 3.78+/-2.21, 3.25+/-1.80 respectively. The T/B was decreased significantly at 1 hour (p<0.001). CONCLUSION: Tc-99rn tetrofosrnin scintimammography was useful diagnostic procedure in the detection of primary breast cancer, especially in patients with indeterminate degree of suspicion for malignancy on plain-film mammogram.

Diagnostic Value of Dipyridamole Tc-99m Tetrofosmin SPECT for Detection of Coronary Artery Disease

Background and Objects: Tc-99m tetrofomsin is a recently developed myocardial perfusion agent. We examined the diagnostic accuracy of dipyridamole Tc-99m tetrofosmin SPECT. MATERIALS AND METHOD: 61 patients underwent one-day rest/dipyridamole Tc-99m tetrofosmin SPECT. 26 patients had history of myocardial infarction. Coronary angiography, performed within 1 week after SPECT study, revealed normal coronary arteries or insignificant coronary artery stenosis in 19 and 22 patients (when considering > or = 50% or > or = 70% reduction of luminal diameter as significant stenosis). RESULTS: Number of male was 39 (63.9%) and mean age was 59 (range 32 - 84). The diagnostic accuracy of dipyridamole Tc-99m tetrofosmin SPECT for detection of coronary artery disease (> or = 50% and > or = 70% coronary artery stenosis, respectively) was as follows: sensitivity 90.5%, 90.0%, specificity 73.7%, 66.7%, positive predictive value 88.4%, 83.7%, negative predictive value 77.8%, 77.8% and predictive accuracy was 85.2%, 81.9% respectively. The overall sensitivity and specificity of dipyridamole Tc-99m tetrofosmin SPECT for detection of individual coronary stenosis (> or = 50% and > or = 70% coronary stenosis by coronary angiography) were 64.6%, 64.1% and 86.4%, 85.7% respectively. In patients without myocardial infarction, sensitivity 76.5%, specificity 76.5%, positive predictive value 83.3%, negative predictive value 76.5% and predictive accuracy was 80.0%. CONCLUSION: One-day rest/stress dipyridamole Tc-99m tetrofosmin myocardial SPECT is a useful noninvasive method for detection of coronary artery disease.

Evaluation of Coronary Artery Disease with Tc-99m Tetrofosmin SPECT in Conjuction with Intravenous Adenosine

BACKGROUND: Tc-99m tetrofosmin is a recently developed myocardial perfusion agent that has shown promising characteristics, displaying rapid accumulation in and slow clearance from the myocardium with rapid clearance from background organs. Adenosine is relatively safe, direct and potent coronary vasodilator and has been used as a stress agent in myocardial perfusion scintigraphy. We have performed tetrofosmin single photon emisson computed tomography(SPECT) in patients suspected of coronary artery disease. This study was aimed to assess the safety profile and diagnostic accuracy of adenosine Tc-99m tetrofosmin SPECT. METHOD: One hundred forth six patients underwent Tc-99m tetrofosmin SPECT with intravenous adenosine. Four hours after resting Tc-99m tetrofosmin SPECT imaging, adenosine was infused intravenously at a dose of 0.14 mg/kg of body weight per minute for 6 min and Tc-99m tetrofosmin was injected at 3 min after start of infusion. Blood pressure, heart rate and side effects was recorded during and after four minites of adenosine infusion. Forty seven of patients underwent coronary angiography within 2 weeks. RESULTS: Adenosine induced a significant and mild decrease in systolic and diastolic blood pressure at 2 min after start of adenosine infusion and a significant and mild increase in heart were observed in 70% of 146 patients. Chest discomfort(30%), mild dyspea(25%), chest pain(19%), and headach(12%) were common. No serious side effects were observed despite of continuation chest pain and restlessness, respectively. The diagnostic sensitivity for detection of CAD(>/=50% and >/=70% coronary stenosis by coronary angiography) by adenosine Tc-99m tetrofosmin SPECT were sensitivity 92%, 97%, and specificity) were 76%, 79% for LAD, 67%, 67% for LCX, and 73%, 82% for RCA, respectively. Specificities were 92%, 89% for LAD, 100%, 100% for LCX, 92%, and 87% for RCA. CONCLUSION: Adenosine Tc-99m tetrofosmin SPECT appears to be a feasible, safe, highly sensitive and specific test for the diagnosis of coronary artery disease.