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In this article the technique, interpretation, and diagnostic performance of scintigraphy for the diagnosis of acute pulmonary embolism (PE) are reviewed. Lung scintigraphy has stood the test of time as a reliable and validated examination for the determination of PE. Ventilation/perfusion (V/Q) lung scintigraphy assesses the functional consequences of the clot on its downstream vascular bed in conjunction with the underlying ventilatory status of the affected lung region, in contrast to CT pulmonary angiography (CTPA), which visualizes presence of the clot within affected vessels. Most-commonly used ventilation radiopharmaceuticals are Technetium-99m labeled aerosols (such as 99m Technetium-DTPA), or ultrafine particle suspensions ( 99m Tc-Technegas) which reach the distal lung in proportion to regional distribution of ventilation. Perfusion images are obtained after intravenous administration 99m Tc-labeled macro-aggregated albumin particles which lodge in the distal pulmonary capillaries. Both planar and tomographic methods of imaging, each favored in different geographical regions, will be described. Guidelines for interpretation of scintigraphy have been issues by both the Society of Nuclear Medicine and Molecular Imaging, and by the European Association of Nuclear Medicine. Breast tissue is particularly radiosensitive during pregnancy due to its highly proliferative state and many guidelines recommend use of lung scintigraphy rather than CTPA in this population. Several maneuvers are available in order to further reduce radiation exposure including reducing radiopharmaceutical dosages or omitting ventilation altogether, functionally converting the study to a low-dose screening examination; if perfusion defects are present, further testing is necessary. Several groups have also performed perfusion-only studies during the COVID epidemic in order to reduce risk of respiratory contagion. In patients where perfusion defects are present, further testing is again necessary to avoid false-positive results. Improved availability of personal protective equipment, and reduced risk of serious infection, have rendered this maneuver moot in most practices. First introduced 60 years ago, subsequent advances in radiopharmaceutical development and imaging methods have positioned lung scintigraphy to continue to play an important clinical and research role in the diagnosis of acute PE., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Abstract: Rapidly growing lung lesions, particularly in immunocompromised patients, invoke consideration of an infectious etiology. Aspergillomas, for example, can appear as round nodules with soft tissue attenuation, often associated with cavitation, and are variably 18 F-FDG avid. In contrast, cytomegalovirus, which may also evidence 18 F-FDG uptake, typically manifests as ground-glass opacities, symmetrically distributed small pulmonary nodules, or confluent consolidations, with lower lobe predilection. We describe a patient treated for lymphoma presenting with a solitary enlarging FDG-avid lung nodule, which was determined on resection to be focal cytomegalovirus infection, a distinctly uncommon presentation of this pathogen, more typical of fungal or mycobacterial disease., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: A 47-year-old woman with invasive lobular carcinoma of the left breast underwent prophylactic double mastectomy which also incidentally revealed follicular lymphoma of the right breast. Reconstruction was achieved with bilateral silicone implants and acellular dermal matrix (ADM), a biological scaffold material providing mechanical support. Twelve days thereafter, staging PET/CT demonstrated symmetric moderate FDG uptake corresponding to location of the ADM slings, suspected to reflect cellular engraftment onto the ADM and confirmed by near-complete resolution at 3-month follow-up study. FDG uptake related to ADM should be recognized as reflecting expected cellular incorporation into the matrix, rather than recurrent tumor or infection., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Radionuclide perfusion studies have an established ancillary role in determination of death by neurologic criteria (DNC). While critically important, these examinations are not well understood by individuals outside of the imaging specialties. The purpose of this review is to clarify relevant concepts and nomenclature and provide a lexicon of relevant terminology of value to non-nuclear medicine practitioners who wish to better understand these examinations. Radionuclides were first employed to evaluate cerebral blood flow in 1969. Radionuclide DNC examinations that use lipophobic radiopharmaceuticals (RPs) entail a flow phase followed immediately by blood pool images. On flow imaging, presence of intracranial activity within the arterial vasculature is scrutinized following arrival of the RP bolus into the neck. Lipophilic RPs designed for functional brain imaging were introduced to nuclear medicine in the 1980s and were engineered to cross the blood-brain-barrier and be retained in the parenchyma. The lipophilic RP 99m Tc-hexamethylpropyleneamine oxime ( 99m Tc-HMPAO) was first used as an ancillary investigation in DNC in 1986. Examinations using lipophilic RPs entail both flow and parenchymal phase images. According to some guidelines, parenchymal phase uptake should be assessed by tomographic imaging, while other investigators consider simple planar imaging sufficient. Findings of perfusion on either the flow or parenchymal phase of the examination effectively precludes DNC. If the flow phase is omitted or somehow compromised, the parenchymal phase remains sufficient for DNC. A priori, parenchymal phase imaging is superior to flow phase imaging for several reasons and lipophilic RPs are favoured over lipophobic RPs in that both flow and parenchymal phase imaging are performed. Disadvantages of lipophilic RPs are increased cost and the need to procure them from a central laboratory, which can prove difficult, especially outside usual working hours. According to most current guidelines, both lipophilic and lipophobic RP categories are acceptable for use in ancillary investigations in DNC, with a growing overt preference for studies using the lipophilic RPs based on their ability to capture the parenchymal phase. The new adult and pediatric Canadian recommendations favour use of lipophilic RPs to variable degrees, specifically 99m Tc-HMPAO, the lipophilic moiety which has undergone the greatest validation. Although ancillary use of radiopharmaceuticals is quite settled in multiple DNC guidelines and best practices, several areas of further research remain open to investigation. Examens auxiliaires de perfusion nucléaire pour la détermination du décès selon des critères neurologiques : méthodes, interprétation et lexique-un guide de l'utilisateur à l'intention du clinicien., (© 2023. The Author(s).)

Purpose: We performed a systematic review and meta-analysis to determine the diagnostic test accuracy of ancillary investigations for declaration of death by neurologic criteria (DNC) in infants and children., Source: We searched MEDLINE, EMBASE, Web of Science, and Cochrane databases from their inception to June 2021 for relevant randomized controlled trials, observational studies, and abstracts published in the last three years. We identified relevant studies using Preferred Reporting Items for Systematic Reviews and Meta-Analysis methodology and a two-stage review. We assessed the risk of bias using the QUADAS-2 tool, and applied Grading of Recommendations Assessment, Development, and Evaluation methodology to determine the certainty of evidence. A fixed-effects model was used to meta-analyze pooled sensitivity and specificity data for each ancillary investigation with at least two studies., Principal Findings: Thirty-nine eligible manuscripts assessing 18 unique ancillary investigations (n = 866) were identified. The sensitivity and specificity ranged from 0.00 to 1.00 and 0.50 to 1.00, respectively. The quality of evidence was low to very low for all ancillary investigations, with the exception of radionuclide dynamic flow studies for which it was graded as moderate. Radionuclide scintigraphy using the lipophilic radiopharmaceutical 99m Tc-hexamethylpropyleneamine oxime (HMPAO) with or without tomographic imaging were the most accurate ancillary investigations with a combined sensitivity of 0.99 (95% highest density interval [HDI], 0.89 to 1.00) and specificity of 0.97 (95% HDI, 0.65 to 1.00)., Conclusion: The ancillary investigation for DNC in infants and children with the greatest accuracy appears to be radionuclide scintigraphy using HMPAO with or without tomographic imaging; however, the certainty of the evidence is low. Nonimaging modalities performed at the bedside require further investigation., Study Registration: PROSPERO (CRD42021278788); registered 16 October 2021., (© 2023. The Author(s).)

This 2023 Clinical Practice Guideline provides the biomedical definition of death based on permanent cessation of brain function that applies to all persons, as well as recommendations for death determination by circulatory criteria for potential organ donors and death determination by neurologic criteria for all mechanically ventilated patients regardless of organ donation potential. This Guideline is endorsed by the Canadian Critical Care Society, the Canadian Medical Association, the Canadian Association of Critical Care Nurses, Canadian Anesthesiologists' Society, the Canadian Neurological Sciences Federation (representing the Canadian Neurological Society, Canadian Neurosurgical Society, Canadian Society of Clinical Neurophysiologists, Canadian Association of Child Neurology, Canadian Society of Neuroradiology, and Canadian Stroke Consortium), Canadian Blood Services, the Canadian Donation and Transplantation Research Program, the Canadian Association of Emergency Physicians, the Nurse Practitioners Association of Canada, and the Canadian Cardiovascular Critical Care Society., (© 2023. The Author(s).)

The purpose of this study was to evaluate a pulmonary embolism (PE) perfusion-only screening (POS) protocol introduced during the coronavirus disease 2019 (COVID-19) pandemic surge. Subjects without dense parenchymal lung opacities were studied; those with less than 1 segmental perfusion defect were considered to have no PE, whereas those exhibiting 1 or more defects were indeterminate, mandating additional examinations to determine the final diagnosis. Methods: We analyzed demographic information, clinical data, imaging findings, and follow-up data from the electronic records of COVID-19 patients who underwent lung scintigraphy during the 60-d study period. Results: In total, 53 studies were performed on 17 COVID-19-positive and 36 COVID-19-negative patients. The POS protocol efficiently excluded PE in 79% of cases; the remaining 21%, indeterminate for PE, were generally referred for alternative testing or were directly anticoagulated. In patients with negative POS results, there was a very low mortality before hospital discharge (1/42) and normal results on follow-up studies (6/6). Conclusion: The POS protocol, implemented during the COVID-19 surge, efficiently and safely excluded PE in 79% of patients., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)

Community SARS-CoV-2 has profoundly affected traditional elements of learning and teaching in nuclear medicine and diagnostic radiology departments. The response of the nuclear medicine community to the challenges imposed by the COVID-19 pandemic can be described in 3 phases: accommodation, consolidation and optimization, and a return towards normalcy. Adoption of virtual communication platforms has emerged as the crucial interim tool for preservation of trainee supervision and diagnostic imaging education. Development of supplemental teaching materials, refocusing research interests, and relaxation of requirements have all contributed toward stabilization of the residency programs. As we embark on a gradual return to normalcy, many of the virtual solutions that were employed have gained a degree of enduring popularity and may find a place in the postpandemic period., (Copyright © 2021. Published by Elsevier Inc.)

One of the major effects of the COVID-19 pandemic within nuclear medicine was to halt performance of lung ventilation studies, due to concern regarding spread of contaminated secretions into the ambient air. A number of variant protocols for performing lung scintigraphy emerged in the medical literature which minimized or eliminated the ventilation component, due to the persistent need to provide this critical diagnostic service without compromising the safety of staff and patients. We have summarized and reviewed these protocols, many of which are based on concepts developed earlier in the history of lung scintigraphy. It is possible that some of these interim remedies may gain traction and earn a more permanent place in the ongoing practice of nuclear medicine., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Purpose: Accurate detection of cancer lesions in positron emission tomography (PET) is fundamental to achieving favorable clinical outcomes. Therefore, image reconstruction, processing, visualization, and interpretation techniques must be optimized for this task. The objective of this work was to (1) develop and validate an efficient method to generate well-characterized synthetic lesions in real patient data and (2) to apply these lesions in a human perception experiment to establish baseline measurements of the limits of lesion detection as a function of lesion size and contrast using current imaging technologies. Approach: A fully integrated software package for synthesizing well-characterized lesions in real patient PET was developed using a vendor provided PET image reconstruction toolbox (REGRECON5, General Electric Healthcare, Waukesha, Wisconsin). Lesion characteristics were validated experimentally for geometric accuracy, activity accuracy, and absence of artifacts. The Lesion Synthesis Toolbox was used to generate a library of 133 synthetic lesions of varying sizes ( n = 7 ) and contrast levels ( n = 19 ) in manually defined locations in the livers of 37 patient studies. A lesion-localization perception study was performed with seven observers to determine the limits of detection with regard to lesion size and contrast using our web-based perception study tool. Results: The Lesion Synthesis Toolbox was validated for accurate lesion placement and size. Lesion intensities were deemed accurate with slightly elevated activities (5% at 2:1 lesion-to-background contrast) in small lesions ( Ø = 15    mm spheres), and no bias in large lesions ( Ø = 22.5    mm ). Bed-stitching artifacts were not observed, and lesion attenuation correction bias was small ( - 1.6 ± 1.2 % ). The 133 liver lesions were synthesized in ∼ 50    h , and readers were able to complete the perception study of these lesions in 12 ± 3    min with consistent limits of detection amongst all readers. Conclusions: Our open-source utilities can be employed by nonexperts to generate well-characterized synthetic lesions in real patient PET images and for administering perception studies on clinical workstations without the need to install proprietary software., (© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE).)

The discipline of evidence-based medicine (EBM), though yet unnamed, was in its infancy when Seminars in Nuclear Medicine was inaugurated in 1971; commemorating the golden anniversary of this prestigious journal and the contemporaneous reign of its editors by publishing a 50-year historical consideration of EBM seems most apropos. EBM should be understood as a system of methods to eliminate partiality and improve the quality of evidence in the performance and review of data; much of EBM revolves around ensuring that conclusions are derived from rigorous research studies that protect against bias and are widely generalizable to other groups of patients. Subdomains within EBM that we will survey in this review include methods of performing and evaluating primary studies, standards of reporting of medical studies, methods of combining and aggregating data, and finally, methods of creating clinical practice guidelines. While many practitioners of nuclear medicine may not presently be familiar with the innovations of EBM, having been introduced after their formal education was completed, with the eventual arrival of more-recently trained staff, firm recommendations from our primary research journals, and with efforts to educate practicing physicians, this shortcoming is being addressed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Radium 223 Ra dichloride ( 223 RaCl 2 ) is an effective therapeutic radiopharmaceutical presently approved for the treatment of prostate cancer metastatic to bone. It is unique by virtue of being the first alpha-emitting radiopharmaceutical to achieve approval for use in the clinic, reaching this status both in the United States and Europe in 2013. In over ten years of research and approved clinical usage, the authors have encountered very few radiation-safety incidents of concern with 223 RaCl 2 ; in this review, they relate their first-hand experience with this radiopharmaceutical and share some lessons learned, including situations of bleeding, surgery and patient demise. The authors first provide a basic review of the relevant physical properties of 223 Ra and aspects of its radiobiology, followed by a discussion of the biodistribution of 223 RaCl 2 , the radiopharmaceutical presently approved for clinical use. As would be expected from a primarily alpha emitter, external exposures to staff and family members from patients administered 223 Ra are typically low in comparison with exposure from patients who have undergone other nuclear medicine procedures. There still remains potential for health care workers and family members to receive a significant internal exposure, through the ingestion of even minute amounts of activity, so proper handling practices are paramount., (Copyright © 2019. Published by Elsevier Inc.)

Purpose: Proposed mechanisms of parathyroid localization in 'dual-phase' technetium-99m-sestamibi imaging include increased presence of mitochondria leading to greater uptake and slower washout compared with thyroid tissues owing to reduced expression of P-glycoprotein. Using new techniques of quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT), we have measured MIBI uptake and washout to better understand factors related to conspicuity., Patients and Methods: We retrospectively reviewed 125 consecutive patients. Early and delayed SPECT/CT images were reconstructed using a previously validated technique. Maximum standardized uptake values of parathyroid adenomas and thyroid tissue were measured, and corresponding washout rates were calculated., Results: Of 53 patients with localization of parathyroid adenoma (42%), median maximum standardized uptake values were higher for parathyroid adenomas than for thyroid tissue on both early (6.43±3.78 vs. 4.43±1.93, P<0.001) and delayed (3.40±3.09 vs. 1.84±1.05, P<0.001) images, being true on a per-patient basis in 41 (77%) and 48 (91%) patients, respectively. Median washout rates were slower from parathyroid adenomas than from thyroid lobes (0.26±0.16 vs. 0.42±0.18 h, P<0.001), being true on a per-patient basis in 43 (81%) patients. Similar findings were observed in a subgroup of 37 patients with surgically-confirmed adenomas. Of the patients where initial parathyroid uptake did not exceed thyroid uptake, all 12 exhibited slower MIBI washout from the parathyroid adenomas than from the thyroid gland. The characteristics of the thyroid gland did not differ in 67 patients without parathyroid localization., Conclusion: Quantitative analysis of 53 patients with localization of parathyroid adenoma revealed both a generally higher initial absolute uptake and slower rate of washout of MIBI in parathyroid adenomas than in thyroid tissue. The findings may support the hypothesis that both mechanisms proposed for parathyroid conspicuity in the dual-phase examination increased mitochondrial binding and slower washout owing to reduced P-glycoprotein expression. The technique of quantitative SPECT/CT represents a powerful tool for measuring tissue uptake to elucidate the contribution of these factors to lesion conspicuity.

Background: Critical clinical decisions are made on the basis of the glomerular filtration rate (GFR) measured using technetium-99m-diethylenetriaminepentaacetic acid (DTPA) administration, followed by multiple time-point plasma sampling. As GFR studies rely on few data points and produce a single result, they are prone to technical errors that may remain inconspicuous., Objective: We describe a data analysis worksheet that provides real-time quality control (QC) indicators and evaluate our initial clinical experience., Methods: Two hundred and forty-six consecutive GFR studies carried out at our clinics were included. Our protocol used plasma samples at 2, 3, and 4 h after injection of technetium-99m-DTPA. Duplicate plasma samples, background samples, and aliquots of an activity dilution standard were counted. Times were logged for injection and dilution standard preparation, blood sampling, and counting. Data were entered into a custom GFR analysis spreadsheet that flagged QC in real time at warning and error levels, including QC of the expected ratio between dilution standard counts-activity ratio (CARs) measurements, which was newly introduced to our clinic. The prevalence of QC events was analyzed in three phases: baseline, training, and evaluation (n=31, 69, and 146, respectively)., Results: From the baseline and training phases (n=100), CAR reference values were determined for each of two sites. In the absence of the CAR QC indicator, errors were present in 5/31 (16%) examinations, but with QC indication decreased to 7/146 (5%) (P<0.05), suggesting that the real-time QC information guided the technologists to ensure proper standard preparation and sample handling, as intended. Improvements in other QC measures were also noted, resulting in an overall error rate reduction from 23 to 8%., Conclusion: Real-time analysis of redundant information as a component of the GFR worksheet ensures quality results, but training of technologists and interpreting physicians is essential for optimal utilization of these QC indicators.

Background: Infective endocarditis (IE) is a serious, potentially life-threatening condition. Currently, the modified Duke criteria is used to assist with the diagnosis of IE, but it can still remain difficult. Growing data supports the potential use of molecular imaging to assist in the diagnosis of IE. Our objective was to understand the potential utility of 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography-computed tomography (PET-CT), 67 Ga citrate and radiolabeled white blood cell (WBC) scintigraphy in the diagnosis of IE., Methods and Results: A systematic review of the literature and meta-analysis on the use of all 3 modalities in IE was conducted. The literature search identified 2753 articles. A total of 14 studies met the inclusion criteria (10 for 18 F-FDG, 3 for WBC and 1 for both modalities). No 67 Ga citrate study met the inclusion criteria. Pooled sensitivity of 18 F-FDG studies with adequate cardiac preparation for the diagnosis of IE was 81% (95% CI, 73%-86%) and pooled specificity was 85% (95% CI, 78%-91%). There was good overall accuracy with an area under the curve (AUC) of 0.897. Pooled sensitivity of WBC for the diagnosis of IE was 86% (95% CI, 77%-92%) and pooled specificity was 97% (95% CI, 92%-99%). The overall accuracy of WBC was excellent with an AUC of 0.957., Conclusions: Both 18 F-FDG and WBC have good sensitivity, specificity and accuracy for the diagnosis of IE. Both modalities are useful in the investigation of IE, and should be considered in cases where the diagnosis is uncertain., (Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.)

Background: Measurement of radioactive iodine uptake (RAIU) is an important aspect of the assessment and treatment of patients with hyperthyroidism. Its uncertainty affects how much of a true change in RAIU can be detected as well as appropriateness of the therapy dosage upon which it is based. In this study, a method of estimating the reproducibility and least significant change (LSC) values for RAIU measurements, and the implications of the values observed are discussed, with emphasis on application to quality assurance initiatives., Methods: We prospectively studied 36 consecutive patients referred for RAIU measurements. Twenty-four hours after oral administration of 370 kBq of 131 I-NaI in capsule form, RAIU measurements were obtained in duplicate using a thyroid probe uptake system. Assessment of reproducibility was performed using root-mean-square standard deviation., Results: Average difference between duplicated RAIU measurements in our study cohort was -0.1 ± 1.6% and ranged from -4.8% to 3.1%. Reproducibility of probe-based RAIU measurement was calculated to be 1.1% and 95% LSC was 3.2%., Conclusion: In our clinic, probe-based RAIU is a reproducible and relatively precise measurement. Using the method we have outlined, each institution can perform reproducibility assessment and compute the LSC of RAIU measurements based on its own staff, iodine isotope, equipment, protocols, and patient population. These values are useful in the assessment of serial change in RAIU, and as more experience is accumulated, can serve as benchmarks to be used in quality assurance initiatives., (© 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

In our practice, FDG PET-CT studies are frequently performed within days of transthoracic needle biopsy, often revealing presence of pneumothorax (PTX), a "critical finding" that should be reported expeditiously. In our experience, prevalence of PTX at PET-CT performed 1 day following biopsy is greater than 40%. Of these, approximately a third are not visible on the postprocedure chest radiography, as in a case we describe. A high level of vigilance is therefore recommended to identify PTX in patients who have undergone recent transthoracic needle biopsy, even when no PTX is present immediately following the biopsy procedure.

Tuberculosis (TB) remains a major health problem, affecting approximately one-third of the world׳s population. The tubercle bacillus can affect virtually any organ of the human body and if left untreated can lead to severe morbidity and death. Diagnosis of active TB is challenging, especially in children. As a "great imitator," the disease can mimic numerous other pathologies, both clinically and at imaging. Although recognition of active TB is crucial to initiate adequate treatment in a timely fashion, thereby preventing transmission of disease, differentiation of active and quiescent disease is not always straightforward. Since the first reports more than 20 years ago, FDG-PET/CT imaging has been shown to detect active disease with accuracy equal or superior to other conventional imaging modalities. The role of FDG-PET in evaluating patients with TB is rapidly expanding. FDG-PET/CT can effectively identify foci of intrathoracic and extrathoracic TB, assess disease activity, differentiate between active and latent disease, monitor response to therapy, identify potential biopsy targets, and serve as a surrogate end point for new drug trials. Efficacy of FDG-PET/CT in the especially challenging pediatric population will be the focus of this review., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The use of cardiac implantable electronic devices (CIED) is increasing, and their associated infections result in significant morbidity and mortality. The introduction of better cardiac imaging techniques could be useful for diagnosing this condition and guiding therapy. Our objective was to systematically assess the diagnostic accuracy of Fluor-18-fluorodeoxyglucose positron emission tomography and computed tomography, labeled leukocyte scintigraphy (LS), and Gallium-67 citrate scintigraphy for the diagnosis of CIED infection., Methods and Results: A systematic review of the literature and meta-analysis on the use of all 3 modalities in CIED infection were conducted. Pooled sensitivity, specificity, and summary receiver operating characteristic curves of each imaging modalities were determined. The literature search identified 2493 articles. A total of 13 articles (11 studies for 18 F-FDG PET-CT and 2 for LS), met the inclusion criteria. No studies for 67 Ga citrate scintigraphy met the inclusion criteria. The pooled sensitivity of 18 F-FDG PET-CT for the diagnosis of CIED infection was 87% (95% CI, 82%-91%) and pooled specificity was 94% (95% CI, 88%-98%). The summary receiver operating characteristic curve analysis demonstrated good overall accuracy, with an area under the curve of 0.935. There were insufficient data to do a meta-analysis for LS, but both studies reported sensitivity above 90% and specificity of 100%., Conclusions: Both 18 F-FDG PET-CT and LS yield high sensitivity, specificity, and accuracy, and thus seem to be useful for the diagnosis of CIED infection, based on robust data for 18 F-FDG PET-CT but limited data for LS. When available, 18 F-FDG PET-CT may be preferred., (© 2017 American Heart Association, Inc.)

Introduction . The purpose of this study is to assess referral patterns and the yield of ventilation-perfusion (V/Q) scintigraphy in patients referred for acute pulmonary embolism (PE). Methods . We retrospectively reviewed the charts of all patients who underwent V/Q studies between April 1, 2008, and March 31, 2010. Patients were subdivided into 4 groups based on their referral source: emergency department (ED), hospital inpatient ward, outpatient thrombosis clinic, and all other outpatient sources. Results . A total of 1008 patients underwent V/Q scintigraphy to exclude acute PE. The number of ED, inpatient, thrombosis clinic, and outpatient studies was 43 (4.3%), 288 (28.6%), 351 (34.8%), and 326 (32.3%). Proportion of patients with contrast contraindication varied significantly among the different groups. Of the 1,008 studies, 331 (32.8%) were interpreted as normal, 408 (40.5%) as low, 158 (15.7%) as intermediate, and 111 (11.0%) as high probability for PE. 68 (6.7%) patients underwent CTPA within 2 weeks following V/Q. Conclusion . The rate of nondiagnostic studies is lower than that reported in previously published data, with a relatively low rate of intermediate probability studies. Only a small fraction of patients undergoing a V/Q scan will require a CTPA.

The pronouncement of death is a determination of paramount social, legal, and ethical import. The novel construct of "brain death" was introduced 50 years ago, yet there persist gaps in understanding regarding this diagnosis on the part of medical caregivers and families. The tragic, much-publicized case of Jahi McMath typifies potential problems that can be encountered with this diagnosis and serves as an effective point of departure for discussion. This article recapitulates the historical development of brain death and the evolution of scintigraphic examinations as ancillary or confirmatory studies, emphasizing updated clinical and imaging practice guidelines and the current role of scintigraphy. The limitations of clinical and radionuclide studies are then reviewed. Finally, the article examines whether radionuclide examinations might be able to play an expanded role in the determination of brain death by improving accuracy and facilitating effective communication with family members., (© 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Bone mineral densitometry (BMD) using dual-energy x-ray absorptiometry (DEXA) has been widely adopted as the standard method of assessing bone density. Although not intended to be a primary imaging modality, the technique generates attenuation map images that are used to guide region-of-interest placement. Artifacts and incidental findings are frequently encountered on the DEXA images, some of which directly affect BMD values and others that are only of incidental importance to clinical practice. We systematically review a variety of artifacts and incidental findings that may be encountered on DEXA, illustrated by a collection of findings from our own practice. Being cognizant of these unexpected abnormalities, and understanding their etiology, will prepare the reader to more readily appreciate significance of these findings when seen in clinical practice., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Unlabelled: There are currently no data published regarding the proportion of nuclear medicine centers using SPECT or SPECT/CT rather than planar ventilation/perfusion (V/Q) imaging in patients with suspected acute pulmonary embolism (PE). Furthermore, the reporting criteria used for interpretation of both planar and SPECT V/Q scans are variable and data are lacking regarding which criteria are commonly used in various centers. The aim of this study was to assess current practices regarding the performance and interpretation of lung scintigraphy across 3 different countries., Methods: A short online survey composed of simple multiple-choice questions was distributed to nuclear medicine departments in Australia, Canada, and France during the period April to December 2014. The survey covered image acquisition, interpretation criteria for SPECT and planar images, and use of pseudoplanar images and radiopharmaceuticals. Information was initially solicited by 2 sets of e-mails, which pointed to the survey internet link. Departments were subsequently contacted by telephone. A single response per department was consolidated., Results: Three hundred thirty-one responses were collected (Australia, 74; Canada, 48; and France, 209). Twenty-eight percent of centers indicated use of V/Q planar imaging alone whereas 72% of centers included some form of SPECT in their acquisition protocol for evaluation of PE, specifically V/Q SPECT in 36%, V/Q SPECT/CT in 29%, Q SPECT/CT in 2%, and both V/Q planar and SPECT in 5%, with a strong variability among countries. The most commonly used criteria for SPECT interpretation were the those of the European Association of Nuclear Medicine (60%). Criteria used for planar interpretation were heterogeneous (European Association of Nuclear Medicine criteria, 35%; Prospective Investigation of Pulmonary Embolism Diagnosis study, 29%; no standardized criteria, 21%). Sixty-three percent of departments used pseudoplanar images in addition to SPECT images., Conclusion: In the 3 countries surveyed, SPECT has largely replaced planar imaging for evaluation of PE, with almost half of the SPECT studies incorporating a CT acquisition. Criteria used for interpretation are inconsistent, especially for planar imaging., (© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Unlabelled: Gastric emptying scintigraphy is considered to be the gold standard for detection of gastroparesis and other disorders of gastric motility; Society of Nuclear Medicine and Molecular Imaging guidelines are predicated on imaging over a period of 4 h, which is inconvenient for patients. Bonta et al. introduced 2-h criteria, which served to shorten the protocol in most patients, with negligible loss of accuracy. We have evaluated the Bonta criteria in a larger multicenter trial encompassing 4 academic institutions., Methods: Retrospective data from 4 academic medical centers were aggregated; 431 patients were included, 105 (24.4%) of whom demonstrated delayed gastric emptying defined by 4-h gastric retention of more than 10%. Bonta criteria (retention > 65% is considered abnormal and < 45% normal; otherwise, proceed to complete examination) were applied to the 2-h data. Sensitivity, specificity, accuracy, and resource use for the Bonta method were calculated. Results based on standard 4-h solid gastric emptying, performed according to current Society of Nuclear Medicine and Molecular Imaging guidelines, served as the gold standard., Results: Retention of 10% or less was achieved by 6, 77, 215, and 326 patients at 1, 2, 3, and 4 h, respectively. At 2 h, 261 of 431 patients (60.6%) had gastric retention of less than 45%, which according to Bonta would be classified as normal; 62 (14.4%) had gastric retention of more than 65%, which would be classified as delayed emptying; and 108 (25.1%) had intermediate values requiring further imaging through 4 h. The Bonta criteria yielded a sensitivity, specificity, and accuracy of 92.4%, 96.9%, and 95.8%, respectively, superior to any single cutoff point applied to the 2-h values. The criteria resulted in false-negative results in 8 (1.9%) patients, 6 of whom were borderline-positive at 4 h (gastric retention of 11%-14%). Using the Bonta criteria, 74.9% of studies would be terminated by 2 h, decreasing total camera use by 15.7%, from 1,768 to 1,490 images, and the average study duration would be reduced by 20.6%, from 3.1 to 2.5 h., Conclusion: In a multicenter cohort, use of the Bonta criteria shortened the duration of studies in most patients, resulting in an effective compromise between reduced resource use, improved patient convenience, and preserved accuracy., (© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Bone scintigraphy has remained a mainstay of clinical nuclear medicine for more than 4 decades. Extensive medical literature has developed surrounding the etiology and significance of alterations in distribution of bone radiopharmaceuticals. Altered biodistribution may be of a global nature, reflecting altered partition of radiopharmaceutical between bone and soft tissues, or more focal, reflecting regional abnormalities, including those related to bone or soft tissues. A third category of alterations in the distribution of bone radiopharmaceuticals is those due to errors and blunders, colloquially termed "artifactual" in the medical imaging literature. Being cognizant of these unexpected abnormalities, and understanding their etiology, will prepare the reader to more readily appreciate the significance of these findings when encountered in clinical practice., (Copyright © 2015 Elsevier Inc. All rights reserved.)

A 60-year-old man with history of metastatic renal cell carcinoma and atypical chest pain was referred for dipyridamole Tc-tetrofosmin perfusion scintigraphy (MPS). Two years earlier, the patient was noted to have myocardial metastases on cardiac MRI. On the MPS, perfusion defects were present at stress in multiple vascular territories; resting myocardial uptake was homogeneous. These findings suggested multivessel atherosclerotic heart disease. In fact, retrospective rigid fusion with prior chest CT and cardiac MRI demonstrated that the reversible perfusion defects corresponded to metastatic deposits in the myocardium. This unusual case illustrates how myocardial metastases can mimic ischemia on MPS.

Gated equilibrium radionuclide ventriculography is frequently used to measure the left ventricular ejection fraction. We report a case of unilateral breast activity resulting in significant underestimation of the left ventricular ejection fraction, which mimicked a left ventricular aneurysm, pseudoaneurysm, or an intrathoracic vascular mass. Unilateral breast uptake, in the absence of gastric activity, was presumed because of increased blood pool in the lactating breast, a finding not previously reported in the literature. This case is also presented to emphasize the importance of localizing abnormalities based on a review of tomographic images or images taken in at least 2 orthogonal projections.

Purpose: To investigate whether lacrimal gland uptake on (67)Ga-gallium citrate scintigraphy correlates with histopathologic evidence of sarcoidosis., Methods: A retrospective, pilot study of 31 patients with suspected sarcoidosis who underwent gallium scintigraphy and lacrimal gland biopsy. Lacrimal gland gallium uptake was assessed by subjective visual scoring (SVS) and lacrimal uptake ratio (LUR)., Results: Eleven (36%) patients had lacrimal gland biopsies containing noncaseating granulomas. A statistically significant correlation was found between lacrimal gland gallium uptake and biopsy positivity using SVS (p = 0.03) or LUR (p = 0.01). Using SVS, biopsy positivity rate increased from 0 to 50% in patients with mild to intense uptake. Using LUR, biopsy positivity rate increased linearly as the ratio increased from 13% (LUR < 4) to 100% (LUR > 8)., Conclusions: Lacrimal biopsy positivity rate significantly correlated with gallium uptake on scintigraphy. Both SVS and LUR methods appear to correlate with histologic results and may potentially aid in patient selection for biopsy.