The use of zeolites to generate PET phantoms for the validation of quantification strategies in oncology.

PURPOSE: In recent years, segmentation algorithms and activity quantification methods have been proposed for oncological (18)F-fluorodeoxyglucose (FDG) PET. A full assessment of these algorithms, necessary for a clinical transfer, requires a validation on data sets provided with a reliable ground truth as to the imaged activity distribution, which must be as realistic as possible. The aim of this work is to propose a strategy to simulate lesions of uniform uptake and irregular shape in an anthropomorphic phantom, with the possibility to easily obtain a ground truth as to lesion activity and borders. METHODS: Lesions were simulated with samples of clinoptilolite, a family of natural zeolites of irregular shape, able to absorb aqueous solutions of (18)F-FDG, available in a wide size range, and nontoxic. Zeolites were soaked in solutions of (18)F-FDG for increasing times up to 120 min and their absorptive properties were characterized as function of soaking duration, solution concentration, and zeolite dry weight. Saturated zeolites were wrapped in Parafilm, positioned inside an Alderson thorax-abdomen phantom and imaged with a PET-CT scanner. The ground truth for the activity distribution of each zeolite was obtained by segmenting high-resolution finely aligned CT images, on the basis of independently obtained volume measurements. The fine alignment between CT and PET was validated by comparing the CT-derived ground truth to a set of zeolites' PET threshold segmentations in terms of Dice index and volume error. RESULTS: The soaking time necessary to achieve saturation increases with zeolite dry weight, with a maximum of about 90 min for the largest sample. At saturation, a linear dependence of the uptake normalized to the solution concentration on zeolite dry weight (R(2) = 0.988), as well as a uniform distribution of the activity over the entire zeolite volume from PET imaging were demonstrated. These findings indicate that the (18)F-FDG solution is able to saturate the zeolite pores and that the concentration does not influence the distribution uniformity of both solution and solute, at least at the trace concentrations used for zeolite activation. An additional proof of uniformity of zeolite saturation was obtained observing a correspondence between uptake and adsorbed volume of solution, corresponding to about 27.8% of zeolite volume. As to the ground truth for zeolites positioned inside the phantom, the segmentation of finely aligned CT images provided reliable borders, as demonstrated by a mean absolute volume error of 2.8% with respect to the PET threshold segmentation corresponding to the maximum Dice. CONCLUSIONS: The proposed methodology allowed obtaining an experimental phantom data set that can be used as a feasible tool to test and validate quantification and segmentation algorithms for PET in oncology. The phantom is currently under consideration for being included in a benchmark designed by AAPM TG211, which will be available to the community to evaluate PET automatic segmentation methods.

The value of (18)F-FDG PET/CT in the assessment of active idiopathic retroperitoneal fibrosis.

PURPOSE: The different stages in idiopathic retroperitoneal fibrosis (IRF) are generally assessed by assay of inflammatory markers and analysis of contrast-enhanced CT images of the retroperitoneal mass. We investigated the potential role of (18)F-FDG PET/CT in this clinical setting. METHODS: (18)F-FDG uptake was assessed visually and semiquantitatively (using maximum standardized uptake values, SUVmax) in images of the abdominal mass in 22 patients prospectively enrolled from June 2008 to December 2010 who underwent a total of 33 PET/CT studies. The accuracy in discriminating active from inactive disease was calculated assuming as reference a biochemical instrumental evaluation of patients with IRF mostly based on the level of inflammatory indices and contrast enhancement (CE) of the mass at the time of each PET study. In particular, the relationship between SUVmax and CE, the latter calculated from the change in radiodensity (Hounsfield units) between the basal and postcontrast venous portal phases, was evaluated on a three-point scale (0 <20 HU, 1 20-30 HU, 2 ≥ 30 HU). SUVmax and CE scores were correlated with the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. The value of PET/CT in assessing the variation of disease activity over time was also investigated by analysing the changes in metabolic volume (MV) of the retroperitoneal lesion between repeat patient studies. RESULTS: PET/CT accurately discriminated (93.9 %) active from inactive disease. Significant agreement (p < 0.01) was observed between visual and semiquantitative analysis of (18)F-FDG uptake, and CE score. A significant correlation (p < 0.01) was found among SUVmax, CRP levels (rho = 0.54) and ESR (rho = 0.55). Corresponding variations in MV and CE score were observed in patients with multiple studies (p < 0.01; rho = 0.68). CONCLUSION: (18)F-FDG PET/CT may be considered an alternative imaging method for the assessment of different stages of IRF.

Myocardial blood flow and infarct size after CD133+ cell injection in large myocardial infarction with good recanalization and poor reperfusion: results from a randomized controlled trial.

OBJECTIVE: Large acute ST-elevation myocardial infarction (STEMI) sometimes leaves extensive ischemic damage despite timely and successful primary angioplasty. This clinical picture of good recanalization with incomplete reperfusion represents a good model to assess the reparative potential of locally administered cell therapy. Thus, we conducted a randomized controlled trial aimed at evaluating the effect of intracoronary administration of CD133 stem cells on myocardial blood flow and function in this setting. METHODS: Fifteen patients with large anterior STEMI, myocardial blush grade 0-1 and more than 50% ST-elevation recovery after optimal coronary recanalization (TIMI 3 flow) with stenting were randomly assigned to receive CD133 cells from either bone marrow (group A) or peripheral blood (group B), or to stay on drug therapy alone (group C). The cells were intracoronary injected within 10-14 days of STEMI. Infarct-related myocardial blood flow (MBF) was evaluated by NH positron emission tomography 2-5 days before cell administration and after 1 year. RESULTS: MBF increased in the infarct area from 0.419 (0.390-0.623) to 0.544 (0.371-0.729) ml/min per g in group A, decreased from 0.547 (0.505-0.683) to 0.295 (0.237-0.472) ml/min per g in group B and only slightly changed from 0.554 (0.413-0.662) to 0.491 (0.453-0.717) ml/min per g in group C (A vs. C: P = 0.023; B vs. C: P = 0.066). Left ventricular volume tended to increase more in groups B and C than in group A, ejection fraction and wall motion score index remained stable in the three groups. CONCLUSION: These findings support the hypothesis that intracoronary administration of bone marrow-derived, but not peripheral blood-derived CD133 cells 10-14 days after STEMI may improve long-term perfusion.

The role of PET with 13N-ammonia and 18F-FDG in the assessment of myocardial perfusion and metabolism in patients with recent AMI and intracoronary stem cell injection.

UNLABELLED: Over the last decade, the effects of stem cell therapy on cardiac repair after acute myocardial infarction (AMI) have been investigated with different imaging techniques. We evaluated a new imaging approach using (13)N-ammonia and (18)F-FDG PET for a combined analysis of cardiac perfusion, metabolism, and function in patients treated with intracoronary injection of endothelial progenitors or with conventional therapy for AMI. METHODS: A total of 15 patients were randomly assigned to 3 groups based on different treatments (group A: bone marrow-derived stem cells; group B: peripheral blood-derived stem cells; group C: standard therapy alone). The number of scarred and viable segments, along with the infarct size and the extent of the viable area, were determined on a 9-segment (13)N-ammonia/(18)F-FDG PET polar map. Myocardial blood flow (MBF) was calculated for each segment on the ammonia polar map, whereas a global evaluation of left ventricular function was obtained by estimating left ventricular ejection fraction (LVEF) and end-diastolic volume, both derived from electrocardiography-gated (18)F-FDG images. Both intragroup and intergroup comparative analyses of the mean values of each parameter were performed at baseline and 3, 6, and 12 mo after AMI. During follow-up, major cardiac events were also registered. RESULTS: A significant decrease (P < 0.05) in the number of scarred segments and infarct size was observed in group A, along with an increase in MBF (P < 0.05) and a mild improvement in cardiac function. Lack of infarct size shrinkage in group B was associated with a marked impairment of MBF (P = 0.01) and cardiac dysfunction. Ambiguous changes in infarct size, MBF, and LVEF were found in group C. No differences in number of viable segments or in extent of viable area were found among the groups. At clinical follow-up, no major cardiac events occurred in group A patients, whereas 2 patients of group B experienced in-stent occlusion and one patient of group C received a transplant for heart failure. CONCLUSION: Our data suggest that a single nuclear imaging technique accurately analyzes changes in myocardial perfusion and metabolism occurring after stem cell transplantation.

The prognostic value of F-18 fluorodeoxyglucose bone marrow uptake in patients with recent diagnosis of multiple myeloma: a comparative study with Tc-99m sestamibi.

PURPOSE: We assessed the prognostic value of F-18 fluorodeoxyglucose (FDG) uptake in the bone marrow of patients with multiple myeloma (MM) in comparison with Tc-99m methoxy-isobutyl-isonitrile (MIBI). METHODS: The extent and intensity of FDG and MIBI uptake in the bone marrow of 18 patients with a recent diagnosis of MM were assessed by visual score and by calculating the mean SUV (mSUV) for FDG and the femora/thigh ratio (TG/BKG, [Target/Background ratio]) for MIBI images. These parameters were correlated with clinical indexes of disease using hemoglobin and beta-2-microglobulin levels and plasma cell infiltrate (PCI) percentage. The mean values of the visual score, mSUV, and TG/BKG levels were compared in patients deceased after a relatively short follow-up (n = 9; group A) and in patients with a longer survival or were alive at the end of the study (n = 9; group B). RESULTS: Significant correlations of mSUV and TG/BKG values with PCI percentages and beta-2-microglobulin were found (P < 0.05). The extent of FDG and MIBI bone marrow uptake was greater in patients of group A (P < 0.01). Higher values of mSUV (P < 0.01) and TG/BKG (P < 0.05) were also observed in patients of group A. These results were consistent with the differences (not statistically significant) in hemoglobin, albumin, beta-2-microglobulin levels, and PCI percentages observed in the 2 groups. CONCLUSION: Our study demonstrates that an increase of FDG bone marrow uptake may predict a more aggressive disease, as much as MIBI uptake. Therefore, an additional analysis of FDG bone marrow images should be performed in patients undergoing PET studies during the initial staging of MM.

Lesion quantification in oncological positron emission tomography: a maximum likelihood partial volume correction strategy.

A maximum likelihood (ML) partial volume effect correction (PVEC) strategy for the quantification of uptake and volume of oncological lesions in 18F-FDG positron emission tomography is proposed. The algorithm is based on the application of ML reconstruction on volumetric regional basis functions initially defined on a smooth standard clinical image and iteratively updated in terms of their activity and volume. The volume of interest (VOI) containing a previously detected region is segmented by a k-means algorithm in three regions: A central region surrounded by a partial volume region and a spill-out region. All volume outside the VOI (background with all other structures) is handled as a unique basis function and therefore "frozen" in the reconstruction process except for a gain coefficient. The coefficients of the regional basis functions are iteratively estimated with an attenuation-weighted ordered subset expectation maximization (AWOSEM) algorithm in which a 3D, anisotropic, space variant model of point spread function (PSF) is included for resolution recovery. The reconstruction-segmentation process is iterated until convergence; at each iteration, segmentation is performed on the reconstructed image blurred by the system PSF in order to update the partial volume and spill-out regions. The developed PVEC strategy was tested on sphere phantom studies with activity contrasts of 7.5 and 4 and compared to a conventional recovery coefficient method. Improved volume and activity estimates were obtained with low computational costs, thanks to blur recovery and to a better local approximation to ML convergence.

Optimization of automated large-scale production of [(18)F]fluoroethylcholine for PET prostate cancer imaging.

INTRODUCTION: PET tumor imaging is gaining importance in current clinical practice. FDG-PET is the most utilized approach but suffers from inflammation influences and is not utilizable in prostate cancer detection. Recently, (11)C-choline analogues have been employed successfully in this field of imaging, leading to a growing interest in the utilization of (18)F-labeled analogues: [(18)F]fluoroethylcholine (FEC) has been demonstrated to be promising, especially in prostate cancer imaging. In this work we report an automatic radiosynthesis of this tracer with high yields, short synthesis time and ease of performance, potentially utilizable in routine production sites. METHODS: We used a Modular Lab system to automatically perform the two-step/one-pot synthesis. In the first step, we labeled ethyleneglycolditosylate obtaining [(18)F]fluoroethyltosylate; in the second step, we performed the coupling of the latter intermediate with neat dimethylethanolamine. The final mixture was purified by means of solid phase extraction; in particular, the product was trapped into a cation-exchange resin and eluted with isotonic saline. RESULTS: The optimized procedure resulted in a non decay corrected yield of 36% and produced a range of 30-45 GBq of product already in injectable form. The product was analyzed for quality control and resulted as pure and sterile; in addition, residual solvents were under the required threshold. CONCLUSION: In this work, we present an automatic FEC radiosynthesis that has been optimized for routine production. This findings should foster the interest for a wider utilization of this radiomolecule for imaging of prostate cancer with PET, a field for which no gold-standard tracer has yet been validated.

Striatal dopamine transporter abnormalities in patients with essential tremor.

BACKGROUND AND METHODS: We used (123)I-Ioflupane SPECT to study 32 unrelated patients with essential tremor (16 with positive familial history), 47 sporadic tremor dominant patients with Parkinson's disease and 31 healthy control subjects. Discriminant analysis was used to categorize healthy subjects and patients with Parkinson's disease or essential tremor. RESULTS: Patients with essential tremor had higher uptake values (50% putamen and 21% caudate, P<0.001) compared to those with Parkinson's disease but lower than healthy subjects (15% putamen and 21% caudate, P<0.05). Discriminant analysis classified seven essential tremor patients in the healthy subjects cohort (22%) and two as Parkinson's disease (6%). CONCLUSIONS: Our results show that some essential tremor patients may present mild abnormalities of striatal dopamine transporters and a typical Parkinson's disease-like pattern of uptake loss. These findings suggest a link between the two disorders.

[123I]FP-CIT striatal binding in early Parkinson's disease patients with tremor vs. akinetic-rigid onset.

We performed [123I]FP-CIT/SPECT in 20 drug-naive Parkinson's disease (PD) patients, 10 with unilateral akinesia/rigidity at onset (arPD) and 10 with additional tremor-at-rest (tPD), to evaluate whether resting tremor at onset is associated with differences in striatal dopamine transporter binding. Patients of the two cohorts were matched for age, disease duration (<3 years) and severity of non-tremor motor symptoms; 31 healthy participants served as controls. Mean striatal dopamine transporter binding reduction in PD patients vs. controls was 42% for arPD and 50% for tPD; mean ipsilateral striatum and caudate nucleus uptake values were lower by 12 and 24%, respectively, in tPD than arPD. We conclude that widespread degeneration of the nigrostriatal dopaminergic pathway might be necessary for the development of parkinsonian tremor-at-rest.

Verification of the agreement of two dosimetric methods with radioiodine therapy in hyperthyroid patients.

The aim of this study was to verify the capability of an MIRD formula-based dosimetric method to predict radioiodine kinetics (fraction of administered iodine transferred to the thyroid, U0, and effective clearance rate, lambda(eff)) and absorbed dose after oral therapeutic 131I administration. The method is based on 123I intravenous administration and five subsequent gamma camera measured uptake values determined separately on different structures within the thyroid. Another dosimetric method based on only the 123I 24-h uptake and a fixed lambda(eff) value was also considered. Eighty-nine hyperthyroid patients (10 with Graves' disease and 79 with autonomously functioning nodules) were studied and 132 thyroidal structures were evaluated. The mean time interval between dosimetry and therapy was 20 +/- 10d. Uptake values were measured at 2, 4, 24, 48, and 120 h during dosimetry and at 2, 4, 24, 48, 96, and 168 h during therapy. The value 0.125d(-1) was chosen in the fixed-lambda(eff) method. The planned doses to the target ranged from 120 to 250 Gy depending on the type and severity of hyperthyroidism. The following significant correlations between therapeutic and dosimetric parameters were found: U0(ther)=0.88U0(dos) (r=0.97,p<0.01), lambda(eff)ther = 1.01 lambda(eff)dos (r=0.85,p<0.01), and D(estimated)= 0.85D(planned) (r=0.88, p<0.01). The percent difference between U0(ther) and U0(dos) ranged from -44 to 32% and between lambda(eff)ther and lambda(eff)dos from -32 to 48%. U0(ther) was lower than U0(dos) in 74% of cases: this can be explained by the self-stunning effect of 131I therapeutic activity that produced a dose of about 20 Gy with a maximum dose rate of 0.6 Gy/h over the initial 24-48 h. The differences, deltaD, between the estimated and the planned doses ranged from -42% (-87 Gy) to 32% (59 Gy); in 73% of cases the difference was within +/- 35 Gy. Greater discrepancies were found with the fixed-lambda(eff) method, in which deltaD ranged from -69 to 95% (-202 to 88 Gy, respectively). In hyperthyroid patients, the five uptake value dosimetric method is able to predict with a good agreement the radioiodine kinetics and the dose after the therapeutic administration in about 73% of the analyzed thyroid structures. The fixed-lambda(eff) method is less reliable.

The trapping-only nodules of the thyroid gland: prevalence study.

The aim of this study was to determine the prevalence of trapping-only nodules of the thyroid gland. The study was prospectively performed in patients bearing hot or warm thyroid nodules at pertechnetate scan in the presence of circulating thyrotropin (TSH) within the normal range. The study was restricted to these patients because nodules that suppress TSH are certainly autonomous. In 140 patients showing hot or warm nodules at 30-minute pertechnetate scintigraphy, and normal TSH levels, radioiodine scintigraphy was performed at 24 hours. The trapping-only pattern, i.e., the presence of a cold nodule in late radioiodine scintigraphy was observed in seven patients (5%). Five had benign thyroid nodules, one follicular carcinoma, and one extrathyroid metastases of papillary-follicular carcinoma. Despite controversy on this issue, trapping-only nodules of thyroid should be searched because they have risk of malignancy and must be differentiated from autonomous adenomas at the compensated stage. The search may be limited to patients with normal serum TSH.

Striatal dopamine transporter binding in Parkinson's disease associated with the LRRK2 Gly2019Ser mutation.

We measured striatal dopamine transporter binding using [(123)I]ioflupane and SPECT in patients with Parkinson's disease associated with the LRRK2 (PARK8) Gly2019Ser gene mutation (LRRK2-PD) and in gene-negative patients with idiopathic Parkinson's disease (IPD) of comparable disease duration and severity. The LRRK2-PD group consisted of a total of 10 patients (3 sporadic) with mean age 62 +/- 14 years, disease duration 9 +/- 3 years, and UPDRS III motor score 21.60 +/- 6.65. The control IPD group consisted of 15 patients with mean age 59 +/- 9 years, disease duration 9 +/- 5 years, and UPDRS III motor score 23.80 +/- 8.69. [(123)I]ioflupane-specific uptake ratios were calculated for caudate nucleus and putamen using the occipital cortex as reference region. We found no differences between the LRRK2-PD group and IPD in all items studied. In particular, putamen and caudate uptake values as well as side asymmetry indexes and putamen/caudate ratios all revealed comparable between-group values. We conclude that in these patients carrying the LRRK2 Gly2019Ser mutation, the neurodegenerative process results in a pattern of nigrostriatal dopaminergic dysfunction similar to that observed in IPD.

Distribution of 99mTc-labeled lymphocytes in control and inflamed rats.

We studied the in vivo fate of CD8(+) lymphocytes, of naive (CD8(+)CD45RC(bright)) or memory (CD8(+)CD45RC(dim)) phenotype, injected in syngeneic rats, after their sorting and labeling with [(99m)Tc] HM-PAO. By using the scintigrafic method we showed that memory CD8(+) lymphocytes were able to recirculate into liver and lungs. The same method was also successfully used to in vivo study the homing of total blood lymphocytes obtained from inflamed rats.

Potential third-party radiation exposure from outpatients treated with 131I for hyperthyroidism.

Thirty-three hyperthyroid patients treated with radioiodine (mean administered activity 414 MBq, range 163-555) were studied to determine if pretreatment dosimetry could be used to give radiation protection advice that could assure compliance with the effective dose constraints suggested by the European Commission. Effective doses to travelers, co-workers, and sleeping partners were estimated by integrating the effective dose rate-versus-time curve obtained by fitting the dose rates measured several times after radioiodine administration to a biexponential function. The mean estimated effective doses to travelers, co-workers, and sleeping partners were 0.11 mSv (0.05-0.24), 0.24 mSv (0.07-0.52), and 1.8 mSv (0.6-4.1), respectively. The best correlation was found between effective dose (D) in mSv and maximum activity (AUmax) in MBq taken up in the thyroid: Dtraveler=0.0005 * (AUmax) +0.04 (r=0.88,p< 0.01); Dco-worker=0.0013 * (A Umax) +0.03 (r=0.89,p < 0.01); Dsleeping partners=0.0105 * (AUmax)+0.16 (r=0.93,p < 0.01). Private/public transports are always allowed. For the co-workers the effective dose constraint of 0.3 mSv is met without restrictions and with 3 days off work if AUmax is lower or higher than 185 MBq, respectively. For the sleeping partners the effective dose constraint of 3 mSv is met without restriction and with 4 nights separate sleeping arrangements if AUmax is lower or higher than 185 MBq, respectively. The potential for contamination by the patients was determined from perspiration samples taken from the patient's hands, forehead, and neck and in saliva at 4, 24, and 48 h after radioiodine treatment. The mean highest 131I activity levels for hands, forehead, neck, and saliva were 4.1 Bq/cm2, 1.9 Bq/cm2, 0.9 Bq/cm2, and 796 kBq/g, respectively. The results indicate that there is minimal risk of contamination from these patients.

Technetium-99m scintigraphy to visualize T-cell homing in vivo: a preclinical study.

The knowledge of lymphocyte distribution is very usefulness in monitoring therapeutic treatments. We present here a method employed in clinical practice, the scintigraphy, to study in the rat the physiologic lymphocyte traffic. Rat T cells labeled with 99mTc were injected in syngeneic animals, and their fate was studied by serial scintigraphic scanning. Sorted naïve CD4+ CD45RC(bright) T cells homed to lymphoid organs and accumulated in spleen. CD4+ CD45RC(dim) memory lymphocytes first reached the liver and the lungs and recirculated. The results obtained by using the scintigraphic method to in vivo study the lymphocyte homing in rats are comparable to those obtained with previously used experimental methods. We consider the scintigraphic method a useful tool to in vivo track lymphocytes and to address therapeutic treatment in men.

Tissue-specific dosimetry for radioiodine therapy of the autonomous thyroid nodule.

A tissue-specific dosimetric method based on gamma camera acquisitions was developed to determine the 131I activity to administer to patients with autonomous thyroid nodules (ATN) to deliver 200 Gy to the nodule and to evaluate the correspondent dose to extranodular tissue. Twenty patients with ATN were given 111 MBq of 123I i.v. and their neck was imaged 2, 4, 24, 48, and 120 hours after administration to evaluate separate iodine kinetics for nodule and contralateral lobe. The volumes of nodule and lobe were measured on the 4 hour scintigraphic image, after optimization of the method on a thyroid phantom. Three simplified dosimetric methods were then considered and compared to the reference method in terms of 131I activity: (a) three point method, based on 4, 24, and 120 h acquisitions, (b) fixed T1/2 method, that measures only the 24 h uptake and assumes an effective half-life of 5 days for the nodule, (c) fixed activity method, based on the administration of 413 MBq of 131I. The mean 131I activity to administer to the 20 patients was 413 MBq (range 65-1327) and the mean dose to the contralateral lobe was 43 Gy (range 11-121). The percentage differences in 131I activity between the reference method and the simplified methods were in the ranges: (a) -14%, 13%, (b) -42%, 74%, (c) -69%, 533%. The relevant dose to extranodular tissue and the great interpatient variability of the radioiodine activity required to give a predetermined dose to ATN suggest that a tissue specific dosimetric approach based on gamma camera acquisitions is fundamental. A simple method based on only three uptake measurements is a reliable alternative to the five point method when the clinical workload of a Nuclear Medicine department is particularly heavy.

PET instrumentation and reconstruction algorithms in whole-body applications.

The aim of this work is the presentation and comparison of state-of-the-art dedicated PET systems actually available on the market, in terms of physical performance and technical features. Particular attention has been given to evaluate the whole-body performance by sensitivity, spatial resolution, dead time, noise equivalent counting rate (NECR), and scatter fraction. PET/CT systems were also included as new proposals to improve diagnostic accuracy of PET, allowing effective anatomic integration to functional data. An overview of actually implemented reconstruction algorithms is also reported to fully understand all of the factors that contribute to image quality.

Tetrofosmin imaging in the detection of myocardial viability in patients with previous myocardial infarction: comparison with sestamibi and Tl-201 scintigraphy.

BACKGROUND: Technetium 99m tetrofosmin has been introduced as a myocardial perfusion agent, providing similar results to those of thallium 201 and sestamibi in the identification of patients with coronary artery disease. No data are available comparing tetrofosmin and sestamibi imaging in the identification of reversible left ventricular (LV) dysfunction in the same patients. This study compared the results of tetrofosmin, thallium, and sestamibi single photon emission computed tomography at rest in detection of myocardial viability in patients with previous myocardial infarction. METHODS AND RESULTS: Seventeen patients with previous myocardial infarction who were undergoing coronary revascularization were studied. Echocardiography was performed at baseline and 3 months after revascularization to evaluate recovery of LV function. The optimal threshold cutoffs to separate reversible from irreversible dysfunction, as determined by receiver operating characteristic analysis, were 55% of peak activity for both tetrofosmin and sestamibi and 60% for thallium. In all asynergic segments (n = 77) analyzed, tetrofosmin uptake correlated with both sestamibi (r = 0.90, P <.0001) and thallium (r = 0.85, P <.0001) activity. The sensitivity and specificity for reversible dysfunction were, respectively, 70% and 70% for tetrofosmin, 70% and 66% for sestamibi, and 60% and 68% for thallium imaging (all P = not significant). The areas under the receiver operating characteristic curves constructed for tetrofosmin, thallium, and sestamibi activity were 0.74 +/- 0.06 (mean +/- SD), 0.75 +/- 0.06, and 0.74 +/- 0.06, respectively (all P = not significant). Concordance for detecting myocardial viability between tetrofosmin and thallium imaging was found in 67 regions (87%) (kappa = 0.74), and concordance between tetrofosmin and sestamibi imaging was found in 69 regions (90%) (kappa = 0.79). CONCLUSIONS: The diagnostic performance of quantitative rest tetrofosmin single photon emission computed tomography in predicting functional recovery after revascularization is comparable to that of both thallium and sestamibi scintigraphy in patients with myocardial infarction and chronic LV dysfunction.