Lung scintigraphy has served as a cornerstone in the evaluation of pulmonary embolism for over 5 decades and currently retains an important role in the evaluation of both acute and chronic disease. This article elucidates the basic physiologic principles, choice of radiopharmaceuticals, imaging methods, and interpretation criteria used in lung scintigraphy and includes a lexicon of lung scintigraphy and nuclear medicine terminology which will be helpful to the yet uninitiated.

The concept of death by neurologic criteria (DNC), a medicolegal construct also known as "brain death", is over 50 years old. Ancillary examinations have a well-defined role in this diagnosis, principally when the clinical examination cannot be completely or safely performed. Radionuclide studies, which provide a combination of ease of performance and high accuracy, remain amongst the most recommended ancillary studies in current clinical guidelines. There are in fact 2 discrete categories of radionuclide studies, using hydrophilic or lipophilic radiopharmaceuticals (RPs), which have overlapping but discrete features, described in this review. Lipophilic RPs that provide both flow and parenchymal imaging are superior to hydrophilic RPs that provide only flow imaging. Various signs have been described in regard to interpretation of the radionuclide study and serve to encapsulate findings in a concise and clearly understood manner. The trident and empty skull signs, relevant to flow and parenchymal phases of radionuclide examinations, respectively, remain the key elements of interpretation and are both necessary and sufficient to make the diagnosis of DNC. The hot nose sign and the sagittal sinus sign are not sufficiently specific for this diagnosis, and do not have a place in the interpretation of DNC examinations. Because it operates in the medicolegal realm and requires rapid and definitive reporting, the nuclear medicine physician must be particularly familiar with methods and interpretation of scintigraphy as an ancillary examination in determination of death by neurologic criteria.

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and professional organization founded in 1954 to promote the science, technology, and practical application of nuclear medicine. Its 18,000 members are physicians, technologists, and scientists specializing

We are pleased to publish a special issue of JMIRS in tribute to Dr. Terrence Ruddy, Professor in the Divisions of Cardiology in the Department of Medicine, and Nuclear Medicine in the Department of Radiology at the University of Ottawa. This issue commemorates a special educational session of the Canadian Association of Nuclear Medicine (CANM) on nuclear cardiology, held October 2023 in recognition of Dr. Ruddy's illustrious career. Both this special issue and the CANM session were populated by contributions from of a legion of Dr. Ruddy's colleagues and admirers, a testament to the widespread appreciation and esteem to which he is held.

Since its publication in 1990 ([1][1]), the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study has played a central role in informing algorithms used to diagnose pulmonary embolism (PE). Indeed, PIOPED-based algorithms maintain a central role in current best practices and

This JAMA Arts and Medicine feature describes ways in which Fritz Kahn shared a prescient and nuanced vision of technology's role in the patient-physician interaction, a topic of continued interest and relevance today, through his illustrations.

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.

In this issue of JMIRS, we are introducing a new feature of interest to the imaging community, the publication of guidelines endorsed by the Canadian Association of Nuclear Medicine (CANM), beginning with Guidelines for Ventilation/Perfusion (V/P SPECT) in Pulmonary Embolism, which were originally approved by the CANM in November 2018. These are among several CANM guidelines that have been shared with the CANM membership but not previously published in indexed medical journals, thereby limiting their visibility and reach, a shortcoming this initiative is meant to address.

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.

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

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 99mTechnetium-DTPA), or ultrafine particle suspensions (99mTc-Technegas) which reach the distal lung in proportion to regional distribution of ventilation. Perfusion images are obtained after intravenous administration 99mTc-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.

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 18F-FDG avid. In contrast, cytomegalovirus, which may also evidence 18F-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.

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.

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.

This article does not include an abstract.

On occasion, a patient’s medical odyssey emerges from obscurity into the public domain. Jahi McMath was an unfortunate 13-y-old girl who suffered a cardiac arrest after surgery and was subsequently declared dead by neurologic criteria (hereafter referred to as brain death [BD]). Her family