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We report a case of a 59-year-old woman with right ventricular metastasis of undifferentiated endometrial cancer. Cardiac metastasis from endometrial cancer is a very rare finding. The case demonstrates that undifferentiated endometrial cancer is capable of metastasizing, presumably through a hematogenous route, to unexpected distant organs. These unexpected sites should not be undermined in the restaging and surveillance of these patients.

Objectives: This practice parameter was revised collaboratively by the American College of Radiology (ACR), the American College of Nuclear Medicine, the American Radium Society, the American Society for Radiation Oncology, and the Society of Nuclear Medicine and Molecular Imaging. The document is intended to serve as a resource for appropriately trained and licensed physicians who perform therapeutic procedures with unsealed sources, referred to in the document using the more inclusive terminology of radiopharmaceuticals, for which a written directive is required for authorized users under NRC 10 CFR 35.300., Methods: This practice parameter was developed according to the process described under the heading The Process for Developing ACR Practice Parameters and Technical Standards on the ACR website ( https://www.acr.org/Clinical-Resources/Practice-Parameters-and-Technical-Standards ) by the Committee on Practice Parameters-Radiation Oncology of the ACR Commission on Radiation Oncology in collaboration with the American Radium Society., Results: This practice parameter addresses the overall role of the applicable physician-authorized user, Qualified Medical Physicist, and other specialized personnel involved in the delivery of radiopharmaceutical therapy. Therapeutic radiopharmaceuticals include those administered as elemental radioactive isotopes (radionuclides) or the radioactive element incorporated into a targeting molecule (ligand) by one or more chemical bonds. This document provides guidance regarding general principles of radionuclide therapies and indications of various alpha, beta, gamma, and mixed emission agents with references to several recent practice parameters on new and commonly performed radiopharmaceutical therapies., Conclusion: This document addresses clinical circumstances, elements of available agents, and the qualifications and responsibilities of various members of the radiation care team, specifications of consultation and other clinical documentation, post-therapy follow-up, radiation safety precautions, elements of quality control and improvement programs, infection control, and patient education to ensure optimal patient care and safety when utilizing radiopharmaceuticals., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin receptor (SSR) analogs is now an established systemic treatment for neuroendocrine tumors (NET). However, more short- and long-term data about renal and hepatotoxicity is needed. Here we present our experience in this clinical scenario., Methods: Eighty-six patients with progressive SSR-expressing malignancies underwent PRRT with Lu-177 Dotatate and were followed up for up to 2 years. Laboratory tests were done 1 week before each cycle and every 2 months at follow-up. Hepatic and renal toxicity was determined based on NCI CTCAE V5.0., Results: 55/86 (64%) patients completed all 4 cycles of PRRT; 18/86 (20.9%) are currently being treated; 13/86 (15.1%) had to discontinue PRRT: 4/13 (31%) due to hematologic toxicity, 9/13 (69%) due to non-PRRT-related comorbidities. Out of the patients who finished treatment, only transient grade 2 toxicities were observed during PRRT: hypoalbuminemia in 5.5% (3/55), and renal toxicity (serum creatinine and estimated glomerular filtration rate) in 1.8% (1/55). No grade 3 or 4 liver and renal toxicity occurred. Patients presenting with impaired liver or renal function prior to PRRT, either improved or had stable findings. No deterioration was observed., Conclusion: Peptide receptor radionuclide therapy does not have a negative impact on liver and renal function, even in patients with pre-existing impaired parameters. No grade 3 or 4 hepatic or renal toxicity was identified. Only transient grade 2 hypoalbuminemia in 5.5% and nephrotoxicity in 1.8% of patients were seen during PRRT., (© The Author(s) 2022. Published by Oxford University Press.)

Objective: The goal of this study is to demonstrate the feasibility of simultaneous [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI) for noninvasive visualization of muscular, neurovascular, and skin changes secondary to complex regional pain syndrome (CRPS)., Subjects: Seven adult patients with CRPS of the foot and seven healthy adult controls participated in our [18F]FDG PET/MRI study., Methods: All participants received whole-body PET/MRI scans 1 hour after the injection of 370MBq [18F]FDG. Resulting PET/MRI images were reviewed by two radiologists. Metabolic and anatomic abnormalities identified, were grouped into muscular, neurovascular, and skin lesions. The [18F]FDG uptake of each lesion was compared with that of corresponding areas in controls using a Mann-Whitney U-test., Results: On PET images, muscular abnormalities were found in five patients, neurovascular abnormalities in four patients, and skin abnormalities in two patients. However, on MRI images, no muscular abnormalities were detected. Neurovascular abnormalities and skin abnormalities in the affected limb were identified on MRI in one and two patients, respectively. The difference in [18F]FDG uptake between the patients and the controls was significant in muscle (P = .018) and neurovascular bundle (P = .0005)., Conclusions: The increased uptake of [18F]FDG in the symptomatic areas likely reflects the increased metabolism due to the inflammatory response causing pain. Therefore, our approach combining metabolic [18F]FDG PET and anatomic MR imaging may offer noninvasive monitoring of the distribution and progression of inflammatory changes associated with CRPS., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Academy of Pain Medicine.)

Objectives: 68 Ga-PSMA11 PET/CT is excellent for evaluating biochemically recurrent prostate cancer (BCR PC). Here, we compared the positivity rates of dual-time point imaging using a PET/CT scanner (DMI) with silicon photomultiplier (SiPM) detectors and a PET/CT scanner (D690) with photomultiplier tubes (PMT), in patients with BCR PC., Methods: Fifty-eight patients were prospectively recruited and randomized to receive scans on DMI followed by D690 or vice-versa. Images from DMI were reconstructed using the block sequential regularized expectation maximization (BSREM) algorithm and images from D690 were reconstructed using ordered subset expectation maximization (OSEM), according to the vendor's recommendations. Two readers independently reviewed all images in randomized order, recorded the number and location of lesions, as well as standardized uptake value (SUV) measurements., Results: Twenty-eight patients (group A) had DMI as first scanner followed by D690, while 30 patients (group B) underwent scans in reversed order. Mean PSA was 30±112.9 (range 0.3-600.66) ng/mL for group A and 41.5 ± 213.2 (range 0.21-1170) ng/mL for group B (P = 0.796). The positivity rate in group A was 78.6% (22/28 patients) vs. 73.3% (22/30 patients) in group B. Although the performance of the two scanners was equivalent on a per-patient basis, DMI identified 5 additional sites of suspected recurrent disease when used as first scanner. The second scan time point did not reveal additional abnormal uptake., Conclusions: The delayed time point in 68 Ga-PSMA11 PET/CT did not show a higher positivity rate. SiPM-based PET/CT identified additional lesions. Further studies with larger cohorts are needed to confirm these results., (Copyright © 2021. Published by Elsevier Inc.)

Introduction: Chronic pelvic pain is a highly prevalent pain condition among women, but identifying the exact cause of pelvic pain remains a significant diagnostic challenge. In this study, we explored a new diagnostic approach with PET/MRI of the sigma-1 receptor, a chaperone protein modulating ion channels for activating nociceptive processes. Methods: Our approach is implemented by a simultaneous PET/MRI scan with a novel radioligand [18F]FTC-146, which is highly specific to the sigma-1 receptor. We recruited 5 chronic pelvic pain patients and 5 healthy volunteers and compared our PET/MRI findings between these two groups. Results: All five patients showed abnormally increased radioligand uptake on PET compared to healthy controls at various organs, including the uterus, vagina, pelvic bowel, gluteus maximus muscle, and liver. However, on MRI, only 2 patients showed abnormalities that could be potentially associated with the pain symptoms. For a subset of patients, the association of pain and the abnormally increased radioligand uptake was further validated by successful pain relief outcomes following surgery or trigger point injections to the identified abnormalities. Conclusion: In this preliminary study, sigma-1 receptor PET/MRI demonstrated potential for identifying abnormalities associated with chronic pelvic pain. Future studies will need to correlate samples with imaging findings to further validate the correlation between S1R distribution and pathologies of chronic pelvic pain. Trial Registration: The clinical trial registration date is June 2, 2018, and the registration number of the study is NCT03195270 (https://clinicaltrials.gov/ct2/show/NCT03556137)., Competing Interests: DY, PC, and SB received research support from General Electric Healthcare. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Yoon, Fast, Cipriano, Shen, Castillo, McCurdy, Mari Aparici, Lum and Biswal.)

Targeted radionuclide therapies (TRT) using 131 I-metaiodobenzylguanidine ( 131 I-MIBG) and peptide receptor radionuclide therapy ( 177 Lu or 90 Y) represent several of the therapeutic options in the management of metastatic/inoperable pheochromocytoma/paraganglioma. Recently, high-specific-activity- 131 I-MIBG therapy was approved by the FDA and both 177 Lu-DOTATATE and 131 I-MIBG therapy were recommended by the National Comprehensive Cancer Network guidelines for the treatment of metastatic pheochromocytoma/paraganglioma. However, a clinical dilemma often arises in the selection of TRT, especially when a patient can be treated with either type of therapy based on eligibility by MIBG and somatostatin receptor imaging. To address this problem, we assembled a group of international experts, including oncologists, endocrinologists, and nuclear medicine physicians, with substantial experience in treating neuroendocrine tumors with TRTs to develop consensus and provide expert recommendations and perspectives on how to select between these two therapeutic options for metastatic/inoperable pheochromocytoma/paraganglioma. This article aims to summarize the survival outcomes of the available TRTs; discuss personalized treatment strategies based on functional imaging scans; address practical issues, including regulatory approvals; and compare toxicities and risk factors across treatments. Furthermore, it discusses the emerging TRTs., (©2021 American Association for Cancer Research.)

Purpose: We investigated the ability of baseline 2-deoxy-2-[ 18 F]fluoro-D-glucose PET/CT parameters, acquired before the start of immunotherapy, to predict development of hyperprogressive disease (HPD) in melanoma patients. We also evaluated the diagnostic performances of ratios of baseline and first restaging PET/CT parameters to diagnose HPD without information of the tumor growth kinetic ratio (TGKR) that requires pre-baseline imaging before baseline imaging (3 timepoint imaging)., Procedures: Seventy-six patients who underwent PET/CT before and approximately 3 months following initiation of immunotherapy were included. PET/CT parameters, including metabolic tumor volume (MTV) for all melanoma lesions and total measured tumor burden (TMTB) based on irRECIST, were measured from baseline PET/CT (MTV base and TMTB base ) and first restaging PET/CT (MTV post and TMTB post ). The ratios of MTV (MTV post /MTV base , MTVr) and TMTB (TMTB post /TMTB base , TMTBr) were calculated., Results: MTV base of HPD patients (n = 9, TGKR ≥ 2) was larger than that of non-HPD (n = 67, TGKR < 2) patients (P < 0.05), and HPD patients demonstrated shorter median overall survival (7 vs. more than 60 months, P < 0.05). The area under the curve (AUC) of MTV base (≥ 155.5 ml) to predict the risk of HPD was 0.703, with a sensitivity of 66.7 % and specificity of 81.2 %. The AUCs of MTVr (≥ 1.25) and TMTBr (≥ 1.27) to diagnose HPD without information of TGKR were 0.875 and 0.977 with both sensitivities of 100 %, and specificities of 79 % and 83.9 %, respectively., Conclusions: Patients at high risk of developing HPD could not be accurately identified based on baseline PET/CT parameters. The ratios of baseline and first restaging PET/CT parameters may be helpful to diagnose HPD, when patients do not undergo pre-baseline imaging.

Purpose To develop and validate a deep learning algorithm that predicts the final diagnosis of Alzheimer disease (AD), mild cognitive impairment, or neither at fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) PET of the brain and compare its performance to that of radiologic readers. Materials and Methods Prospective 18 F-FDG PET brain images from the Alzheimer's Disease Neuroimaging Initiative (ADNI) (2109 imaging studies from 2005 to 2017, 1002 patients) and retrospective independent test set (40 imaging studies from 2006 to 2016, 40 patients) were collected. Final clinical diagnosis at follow-up was recorded. Convolutional neural network of InceptionV3 architecture was trained on 90% of ADNI data set and tested on the remaining 10%, as well as the independent test set, with performance compared to radiologic readers. Model was analyzed with sensitivity, specificity, receiver operating characteristic (ROC), saliency map, and t-distributed stochastic neighbor embedding. Results The algorithm achieved area under the ROC curve of 0.98 (95% confidence interval: 0.94, 1.00) when evaluated on predicting the final clinical diagnosis of AD in the independent test set (82% specificity at 100% sensitivity), an average of 75.8 months prior to the final diagnosis, which in ROC space outperformed reader performance (57% [four of seven] sensitivity, 91% [30 of 33] specificity; P < .05). Saliency map demonstrated attention to known areas of interest but with focus on the entire brain. Conclusion By using fluorine 18 fluorodeoxyglucose PET of the brain, a deep learning algorithm developed for early prediction of Alzheimer disease achieved 82% specificity at 100% sensitivity, an average of 75.8 months prior to the final diagnosis. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Larvie in this issue.

Objective: The objective of this study was to determine if clinical dynamic PET/CT imaging with 11 C-L-methyl-methionine ( 11 C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring 13 C 6 ] phenylalanine ( 13 C 6 -Phe)., Methods: Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with 11 C-MET and a stable isotope infusion of 13 C 6 -Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient K i from analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle., Results: Post-prandial values [mean ± standard error of the mean (SEM)] were higher than post-absorptive values for both K i (0.0095 ± 0.001 vs. 0.00785 ± 0.001 min -1 , p < 0.05) and FSR (0.083 ± 0.008 vs. 0.049 ± 0.006%/h, p < 0.001) in response to the whey protein supplement. The percent increase in K i and FSR in response to the whey protein supplement was significantly correlated (r = 0.79, p = 0.015)., Conclusions: Dynamic PET/CT imaging with 11 C-MET provides an estimate of the post-prandial anabolic response that is consistent with a traditional, invasive stable isotope, and muscle biopsy approach. These results support the potential future use of 11 C-MET imaging as a non-invasive method for assessing conditions affecting skeletal muscle protein synthesis.

While cross-sectional imaging with computed tomography (CT) and magnetic resonance imaging is the primary method for diagnosing hepatocellular carcinoma (HCC), they provide little biological insight into this molecularly heterogeneous disease. Nuclear imaging tools that can detect molecular subsets of tumors could greatly improve diagnosis and management of HCC. To this end, we conducted a patient study to determine whether HCC can be resolved using 68 Ga-citrate positron emission tomography (PET). One patient with recurrent HCC was injected with 300 MBq of 68 Ga-citrate and imaged with PET/CT 249 minutes post injection. Four (28%) of 14 hepatic lesions were avid for 68 Ga-citrate. One extrahepatic lesion was not PET avid. The average maximum standardized uptake value (SUV max ) for the lesions was 7.2 (range: 6.2-8.4), while the SUV max of the normal liver parenchyma was 4.7 and blood pool was 5.7. The avid lesions were not significantly larger than the quiescent lesions, and a prior contrast CT showed uniform enhancement among the lesions, suggesting that tumor signals are due to specific binding of the radiotracer to the transferrin receptor, rather than enhanced vascularity in the tumor microenvironment. Further studies are required in a larger patient cohort to verify the molecular basis of radiotracer uptake and the clinical utility of this tool.

Background: No standardized field of view (FOV) currently exists for whole-body (WB) positron emission tomography/computed tomography (PET/CT). Limited WB PET/CT FOV can exclude portions of the head, upper, and lower extremities, because there is little perceived clinical benefit to be gained from imaging these areas., Purpose: To determine how often utilizing WB PET/CT changes the clinical stage and management compared to each of the limited WB FOVs used for PET/CT., Material and Methods: We retrospectively identified 556 oncologic patients (804 PET/CT studies) who underwent staging or restaging PET/CT between November 2010 and November 2011. Abnormal hypermetabolic areas that were suspicious for malignancy in areas that are outside of some of the limited fields of view including in the brain, scalp, and calvarium (above the orbital ridge), in the proximal upper extremity (distal to the humeral neck), distal upper extremity (beyond the elbow), proximal lower extremity (distal to the lesser trochanter), and distal lower extremity (beyond the knees) were recorded., Results: A total of 8.5% (47/556) of patients had abnormal findings outside the most limited FOV (skull base to upper thighs) used in PET/CT. More patients had abnormal hypermetabolic lesions in the lower extremity (5.9%) than in the upper extremity (2.3%). Similarly, more patients had abnormal lesions in the proximal (6.5%) compared to the distal (1.4%) upper and lower extremities. The stage was only changed in one patient (0.2%), however new lesions noted in the brain changed management in six patients (1.1%). Melanoma, lymphoma, multiple myeloma, sarcomas and stage IV lung, breast, prostate, bladder, testicular, and renal cancer were more likely to have findings outside the most limited FOV (skull base to upper thighs)., Conclusion: WB FOV detects additional sites of disease compared to the limited WB FOV, and although these lesions rarely change stage, some of these lesions may change clinical management., (© 2013 The Foundation Acta Radiologica.)

Functional radionuclide imaging modalities, now commonly combined with anatomical imaging modalities computed tomography (CT) or magnetic resonance imaging (single photon emission computed tomography [SPECT]/CT, positron emission tomography [PET]/CT, and PET/magnetic resonance imaging), are promising tools for the management of prostate cancer, particularly for therapeutic implications. Sensitive detection capability of prostate cancer using these imaging modalities is one issue; however, the treatment of prostate cancer using the information that can be obtained from functional radionuclide imaging techniques is another challenging area. There are not many SPECT or PET radiotracers that can cover the full spectrum of the management of prostate cancer from initial detection to staging, prognosis predictor, and all the way to treatment response assessment. However, when used appropriately, the information from functional radionuclide imaging improves, and sometimes significantly changes, the whole course of the cancer management. The limitations of using SPECT and PET radiotracers with regard to therapeutic implications are not so much different from their limitations solely for the task of detecting prostate cancer; however, the specific imaging target and how this target is reliably imaged by SPECT and PET can potentially make significant impact in the treatment of prostate cancer. Finally, although the localized prostate cancer is considered manageable, there is still significant need for improvement in noninvasive imaging of metastatic prostate cancer, in treatment guidance, and in response assessment from functional imaging, including radionuclide-based techniques. In this review article, we present the rationale of using functional radionuclide imaging and the therapeutic implications for each of radionuclide imaging agent that have been studied in human subjects., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The invasive nature of endomyocardial biopsy has led to a search for alternative diagnostic modalities for the detection of cardiac allograft rejection. To date, no non-invasive test meets all the requirements for the detection of acute and chronic rejection. The rejection process usually presents with lymphocyte infiltration with or without myocyte necrosis, which indicates the severity of cardiac allograft rejection and the necessity of treatment. Activated lymphocytes express somatostatin receptors; thus somatostatin receptor imaging could be used to target them. The aim of this study was to assess the feasibility of using somatostatin receptor imaging to target activated lymphocytes in the process of cardiac allograft rejection. Thirteen somatostatin receptor imaging studies were performed on ten cardiac allograft recipients 12-4,745 days after transplantation, simultaneously with endomyocardial biopsy, to assess the imaging of activated lymphocytes in comparison with histological findings. Somatostatin receptor imaging was performed 4 h after the injection of 110 MBq of the somatostatin analogue indium-111 pentetreotide. 111In-pentetreotide uptake was visually scored and semi-quantitatively estimated by the calculation of a heart-to-lung ratio (HLR). The visual score correlated with the HLR. Intense/moderate uptake on visual assessment and an HLR >1.6 was observed in eight studies. In three of these studies there was significant rejection in the simultaneous endomyocardial biopsy [International Society of Heart and Lung Transplantation (ISHLT) rejection grade 3A/4]. Intense/moderate uptake was associated with mild or no rejection in the remaining five patients, and in four of them the next endomyocardial biopsy performed 1 week later demonstrated significant rejection requiring treatment. Two patients with low uptake and an HLR <1.6 had no evidence of rejection either in the simultaneous endomyocardial biopsy or in the endomyocardial biopsy performed the following week. These preliminary results indicate the feasibility of targeting activated lymphocytes with somatostatin receptor imaging in the detection of cardiac allograft rejection. Somatostatin receptor imaging may predict impending rejection at least 1 week before the endomyocardial biopsy becomes positive. The late appearance of diagnostic endomyocardial biopsy probably reflects a lag-time between lymphocytic activation and induction of myocyte damage. Furthermore, somatostatin receptor imaging at 4 h may in any case allow earlier intervention in the event of rejection, given the time required for histological processing of endomyocardial biopsy.

Introduction and Objectives: Metaiodobenzylguanidine (MIBG) is an analogue of norepinephrine and its cardiac uptake shows sympathetic innervation. During the heart transplantation the allograft becomes completely denervated. The present study was conducted to assess the evolution of sympathetic re-innervation after transplantation, and to related re-innervation with functional status., Patients and Methods: We studied 31 patients from 6 months to 12 years after transplantation by 123I-MIBG studies to evaluate re-innervation and by rest/exercise radionuclide ventriculography to evaluate cardiac function. Myocardial MIBG uptake was quantified by calculating a heart-to-mediastinum ratio (HMR). An HMR > 1.8 was considered normal, moderate between 1.8 and 1.6, mild between 1.6 and 1.3, and absent < 1.3., Results: HMR correlated with time after transplantation (r = 0.607; p < 0.001). HMR of patients studied after 2 years of transplantation was significantly higher (1.62 +/- 0.2 vs 1.34 +/- 0.2; p < 0.05). MIBG uptake was in the anterior region in 3 patients, in the antero-lateral region in 25, and in the antero-lateral and septal regions in 3. From a functional point of view, peak filling rate at exercise was higher in patients studied 2 years after the transplantation (2.7 +/- 0.8 edv/s vs 2.16 +/- 0.5 edv/s; p = 0.02). These patients also showed a higher increase of heart rate with exercise (p < 0.005 vs p < 0.01)., Conclusions: Sympathetic re-innervation increase with time after heart transplantation, and is more frequently seen 2 years after transplantation. Sympathetic re-innervation first appears in the anterior or the antero-lateral regions. A complete re-innervation of the transplanted heart does not occur 12 years after transplantation.

Introduction and Objectives: It has been demonstrated that nitrate administration enhances the detection of myocardial viability in thallium-201 and technetium-99m sestamibi myocardial perfusion studies. The aim of this study was to assess the influence of nitrate administration on technetium-99m tetrofosmin myocardial uptake in patients with coronary artery disease and left ventricular dysfunction., Patients and Methods: Twenty eight patients with coronary artery disease, previous myocardial infarction and left ventricular ejection fraction < 40% underwent, within 48 hours, rest/postnitroglycerin (0.4 mg sublingually) technetium-99m tetrofosmin single photon emission tomography (SPET), comparing these results with that of thallium-201 rest/redistribution SPET in 13 patients (first group) and with that of thallium-201 rest/reinjection SPET in the other 15 patients (second group). Tomograms based on the 3 spatial planes were divided into 15 segments and regional tracer uptake was quantitatively analysed. Viability was defined as presence of tracer uptake > or = 50% of peak activity., Results: The percentage of peak activity at rest or after nitrate administration of technetium-99m tetrofosmin correlated, with that of thallium-201, at rest and after redistribution or reinjection (r = 0.8; p < 0.001). On resting technetium-99m tetrofosmin studies 167 of the 420 segments that were analysed had < 50% of peak activity. 14.5% of these segments showed reversibility after nitrate administration, with an increase in 99mTc-tetrofosmin uptake from 45 +/- 5% to 55 +/- 4% of peak activity (p = 0.001), in the first group, and from 40 +/- 9% to 57 +/- 9% of peak activity (p = 0.003), in the second group. Overall agreement between rest/postnitroglycerin technetium-99m tetrofosmin SPET studies and rest/redistribution or rest/reinjection thallium-201 SPET studies, regarding the presence of myocardial viability, was 87% and 90%, respectively. All except one reversible segments on tetrofosmin studies after nitrates had viability criteria on thallium studies., Conclusions: Nitrate administration at rest enhances the detection of myocardial viability using technetium-99m tetrofosmin SPET, correlating with viability criteria observed on thallium studies. It represents a simple and useful technique in the assessment of myocardial viability.