Fritz Kahn and the Centenary of The Doctor of the Future.

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.

Enlarging 18 F-FDG-Avid Solitary Pulmonary Nodule: A Distinctly Unusual Presentation of Cytomegalovirus Infection in a Patient Receiving Chemotherapy.

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.

FDG Localization in Acellular Dermal Matrix, a Potential Cause of Nonpernicious Uptake Following Breast Reconstruction Surgery.

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.

Ancillary radionuclide perfusion studies in the determination of death by neurologic criteria: methods, interpretation, and lexicon-a user guide for the clinician.

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 99mTc-hexamethylpropyleneamine oxime (99mTc-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 99mTc-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.

RéSUMé: Les examens de la perfusion nucléaire jouent un rôle auxiliaire bien établi dans la détermination du décès selon des critères neurologiques (DCN). Bien qu'ils soient d'une importance cruciale, ces examens ne sont pas bien compris par les personnes en dehors des spécialités d'imagerie. Le but de cette revue est de clarifier les concepts et la nomenclature pertinents et de fournir un lexique de terminologie pertinente utile aux praticiens non spécialisés en médecine nucléaire qui souhaitent mieux comprendre ces examens. Les radionucléides ont été utilisés pour la première fois pour évaluer la circulation sanguine cérébrale en 1969. Les examens de DCN par radionucléides qui utilisent des produits radiopharmaceutiques (RP) lipophobes impliquent une phase de circulation suivie immédiatement d'images de pool sanguin. Sur l'imagerie en circulation, la présence d'une activité intracrânienne dans le système vasculaire artériel est examinée après l'arrivée du bolus de RP dans le cou. Les RP lipophiles conçus pour l'imagerie cérébrale fonctionnelle ont été introduits en médecine nucléaire dans les années 1980 et ont été conçus pour franchir la barrière hémato-encéphalique et être retenus dans le parenchyme. Le RP lipophile 99mTc-hexaméthylpropylèneamine-oxime (99mTc-HMPAO) a été utilisé pour la première fois comme examen auxiliaire pour le DCN en 1986. Les examens utilisant des RP lipophiles impliquent à la fois des images de circulation et de phase parenchymateuse. Selon certaines lignes directrices, l'absorption durant la phase parenchymateuse devrait être évaluée par imagerie tomographique, tandis que d'autres chercheurs considèrent qu'une imagerie planaire simple suffit. Les résultats de perfusion sur la phase de circulation ou la phase parenchymateuse de l'examen excluent effectivement un DCN. Si la phase de circulation est omise ou compromise d'une manière ou d'une autre, la phase parenchymateuse reste suffisante pour établir un DCN. A priori, l'imagerie en phase parenchymateuse est supérieure à l'imagerie en phase de circulation pour plusieurs raisons et les RP lipophiles sont privilégiés par rapport aux RP lipophobes parce que l'imagerie en circulation et en phase parenchymateuse sont toutes deux réalisées. Les inconvénients des RP lipophiles sont l'augmentation des coûts et la nécessité de les obtenir auprès d'un laboratoire central, ce qui peut s'avérer difficile, surtout en dehors des heures de travail habituelles. Selon la plupart des lignes directrices actuelles, les catégories de RP lipophiles et lipophobes sont toutes deux acceptables pour une utilisation dans les examens auxiliaires pour un DCN, avec une préférence manifeste croissante pour les études utilisant les RP lipophiles en fonction de leur capacité à capturer la phase parenchymateuse. Les nouvelles recommandations canadiennes pour adultes et enfants privilégient l'utilisation de RP lipophiles à des degrés variables, en particulier le 99mTc-HMPAO, le fragment lipophile qui a subi la plus grande validation. Bien que l'utilisation auxiliaire des produits radiopharmaceutiques soit tout à fait établie dans de multiples lignes directrices et meilleures pratiques de DCN, plusieurs domaines de recherche supplémentaires restent ouverts à l'étude.

Ancillary investigations for death determination in infants and children: a systematic review and meta-analysis.

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 99mTc-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.

RéSUMé: OBJECTIF: Nous avons réalisé une revue systématique et une méta-analyse pour déterminer la précision des tests diagnostiques des examens auxiliaires pour la déclaration du décès selon des critères neurologiques (DCN) chez les nourrissons et les enfants. SOURCES: Nous avons effectué des recherches dans les bases de données MEDLINE, EMBASE, Web of Science et Cochrane de leur création jusqu'en juin 2021 pour trouver des études randomisées contrôlées, des études observationnelles et des résumés pertinents publiés au cours des trois dernières années. Nous avons identifié les études pertinentes utilisant la méthodologie PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) et une revue en deux étapes. Nous avons évalué le risque de biais en utilisant l'outil QUADAS-2 et appliqué la méthodologie GRADE (Grading of Recommendations Assessment, Development and Evaluation) afin d'évaluer la certitude des données probantes. Un modèle à effets fixes a été utilisé pour méta-analyser les données de sensibilité et de spécificité regroupées pour chaque examen auxiliaire avec au moins deux études. CONSTATATIONS PRINCIPALES: Trente-neuf manuscrits admissibles évaluant 18 examens auxiliaires uniques (n = 866) ont été identifiés. La sensibilité et la spécificité variaient de 0,00 à 1,00 et de 0,50 à 1,00, respectivement. La qualité des données probantes était faible à très faible pour tous les examens auxiliaires, à l'exception des études de circulation nucléaire dynamique, pour lesquelles elle a été classée comme modérée. La scintigraphie nucléaire à l'aide du produit radiopharmaceutique lipophile 99mTc- hexa-méthyl-propylène amine oxime (HMPAO) avec ou sans imagerie tomographique était à la base des examens auxiliaires les plus précis, avec une sensibilité combinée de 0,99 (intervalle de densité le plus élevé [IDE] à 95 %, 0,89 à 1,00) et une spécificité de 0,97 (IDE à 95 %, 0,65 à 1,00). CONCLUSION: L'examen auxiliaire pour un DCN chez les nourrissons et les enfants offrant la plus grande précision semble être la scintigraphie nucléaire utilisant le HMPAO avec ou sans imagerie tomographique; cependant, la certitude des données probantes est faible. Les modalités sans imagerie réalisées au chevet du patient nécessitent un examen plus approfondi. Enregistrement de l'étude: PROSPERO (CRD42021278788); enregistrée le 16 octobre 2021.

Scintigraphic Diagnosis of Acute Pulmonary Embolism: From Basics to Best Practices.

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.

Experience with a Perfusion-Only Screening Protocol for Evaluation of Pulmonary Embolism During the COVID-19 Pandemic Surge.

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.

Safe Pulmonary Scintigraphy in the Era of COVID-19.

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.

Remote Reading and Teaching of Nuclear Medicine in the Era of COVID-19.

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.