Gli autori desiderano ringraziare Laura Diaz, Kevin Phillips, Willa A. Hsueh, e il re C. Li per il loro sostegno utili osservazioni e tecnico per lo sviluppo di questo metodo.

1. Animal Preparazione e trattamento a freddo <ol><li> Individuare e ispezionare una stanza fredda 4 ° C, che è stato approvato per l&#39;alloggiamento di topi di laboratorio. </li><li> Pre-chill gabbie per gli animali durante la notte in cella. Le gabbie sono assemblate senza mangime e le lettiere, ma con una bottiglia d&#39;acqua. </li><li> Al mattino del giorno sperimentale, topi posto uno per uno in ciascuna delle pre-raffreddate gabbie a intervalli di 30 min. Ogni topo singolarmente in gabbia dovrebbe stare in cella per circa 4 ore prima di essere trasportato al laboratorio di imaging. Assicurarsi che i topi sono il digiuno, ma con accesso all&#39;acqua. </li><li> Alle 4 di trasporto dopo il trattamento a freddo ora un animale alla volta ogni 30 minuti al laboratorio di imaging. Questo può essere ottenuto mediante riempimento di un contenitore di polistirolo con ghiaccio e mettendo un pre-raffreddata gabbia di alloggiamento sopra il ghiaccio all&#39;interno della scatola. Liberamente posizionare il coperchio della scatola di polistirolo. </li></ol> 2. Setup Micro-PET/CT Imaging Workflow <p class=&gt; &quot;Jove_content&quot; In questo micro-PET/CT protocollo di imaging è ottenuto con il Inveon Siemens Dedicated PET (dPET) Sistema e multimodalità Inveon (MM) Sistema (CT / SPECT) nella modalità ancorata. L&#39;animale viene posto dall&#39;ingresso MM, con la prima scansione CT per riferimenti anatomici, e poi scivolare verso il centro del dPET per una statica F18 acquisizione PET. Al fine di consentire al computer host di svolgere questi compiti in sequenza automaticamente, il seguente &quot;flusso di lavoro&quot; viene programmato con il posto di lavoro Inveon Acquisition (IAW) il software prima della sessione di imaging attuale. <ol><li> Acquisizione CT: per un intero corpo TC, impostare la corrente a 500 uA, tensione a 80kV, tempo di esposizione a 200 msec, e 240 passaggi per 240 ° di rotazione. Per il rivelatore di raggi X, selezionare la risoluzione a &quot;ingrandimento di basso&quot; con il 78 mm assiale campo dell&#39;imaging e la modalità di un letto singolo. Selezionare &quot;ricostruzione in tempo reale&quot; con il &quot;Common Cone-Beam ricostruzione&quot; metodo in modo che i PC colloqui di accoglienza conun apposito reale ricostruzione al computer tempo (Cobra) per avviare l&#39;attività. </li><li> Acquisizione PET Emissione: Situato a 600 sec (10 min) per &quot;tempo di ciclo fisso&quot; in opzione &quot;acquisto dal tempo&quot;. Selezionare F-18 come &quot;isotopo studio&quot; e l&#39;uso 350-650 keV come &quot;livello di energia&quot;. </li><li> PET Istogramma Emissione: Set &quot;telaio dinamico&quot; come &quot;nero&quot; per i dati di processo come una cornice per tutta la durata per ottenere la scansione statica. Selezionare &quot;3D&quot; come tipo di istogramma e scegliere &quot;nessuna correzione dispersione&quot;. </li><li> PET Ricostruzione: Usa 2D Ordered Subset Expectation Maximization (OSEM2D) come algoritmo di ricostruzione. </li></ol> 3. L&#39;iniezione di FDG <ol><li> Ordinare un pacchetto clinico di 18 F-FDG (10 mCi) da un venditore regionale per il suo arrivo al laboratorio di imaging ~ 30 minuti prima dell&#39;iniezione programmato prima. Seguire le procedure di sicurezza dell&#39;istituto per ricevere ed esaminare il pacchetto contenente materia radioattivals (RAM). </li><li> Con la protezione fornita da un L-block scudo tavolo, l&#39;aliquota FDG e fare diluizioni con soluzione salina sterile. La concentrazione di attività diluita di FDG dovrebbe essere disponibile a 200-300 μCi/100 ul per ogni iniezione. Aspirare la soluzione FDG in una siringa da 1 ml con 26G 1/2 pollici aghi, e misurare la radioattività della siringa intera con un calibratore di dose. </li><li> Iniettare l&#39;animale che è appena trasportato dalla camera fredda (vedi punto 1.4) con 100 ml di soluzione FDG via intraperitoneale (ip) route. Registrare il tempo di iniezione. Misurare la radioattività residuo della siringa di nuovo con il calibratore dose. </li><li> Mettere l&#39;animale torna alla gabbia fredda all&#39;interno di un dispositivo di raffreddamento polistirolo mantenuto con ghiaccio. Incubare l&#39;animale in freddo (~ 4 ° C) per 1 ora per la captazione di FDG. </li><li> Calcolare la dose iniettata FDG per ciascun topo con la seguente formula: Iniettata attività (uCi) = attività in siringa prima dell&#39;iniezione- Attività in siringa dopo l&#39;iniezione </li></ol> 4. Micro-PET/CT Imaging <ol><li> L&#39;imaging micro-PET/CT inizia 1 ora dopo l&#39;iniezione di FDG o 5 ore dopo il trattamento a freddo. Mettere l&#39;animale in una camera di induzione dell&#39;anestesia con il 3% isoflurano in ossigeno. </li><li> Una volta che l&#39;anestesia è indotta, l&#39;animale viene spostato su un micro-CT pellet (letto animale) con la testa appoggiata in una maschera cono che eroga in continuo isoflurano (2%) ad una portata di 2 L / min. Un pad riscaldamento elettrico (BIOVET, m2m Imaging Corp.) è posta sotto l&#39;animale per aiutare a mantenere la temperatura corporea. </li><li> Far scorrere l&#39;animale verso l&#39;ingresso dello scanner MM, attivare l&#39;icona &quot;laser&quot; dalla barra degli strumenti, e utilizzare il controllo touchpad per spostare il letto in modo che il petto dell&#39;animale è alla croce di linee laser orizzontali e verticali. Nella &quot;Laser Allinea&quot; finestra selezionare &quot;primo tipo di scansione&quot; come TAC, e &quot;Acquisizione PET incluso nel flusso di lavoro&quot; come option. </li><li> Aprire il &quot;View Scout&quot; finestra e acquisire una visione esploratore radiografia radiografia. Utilizzare IAW per regolare la posizione del letto animale in modo che il centro del campo di vista di CT si trova nel centro del corpo del mouse (fegato). Ripetere l&#39;operazione se necessario. </li><li> Avviare il &quot;flusso di lavoro&quot; stabilito al punto 2. Quando le opzioni pop-up, selezionare un appropriato 3D PET-CT trasformazione di file di matrice da utilizzare in CT ricostruzione, e scegliere un file di normalizzazione di recente creato per la ricostruzione PET senza la correzione dell&#39;attenuazione. La IAW inizierà CT e PET in sequenza come programmato. </li><li> Dopo l&#39;intero flusso di lavoro è completato, che può prendere 20-25 min, brevemente valutare la qualità delle immagini acquisite CT e PET con la VM ASIPro, un micro-PET software di analisi co-installato con IAW. Archiviare i dati di imaging di un dispositivo di memorizzazione dati o trasferire i dati attraverso la rete a una workstation analisi post di imaging (vedere il punto 5) per ulteriori analisi. </li><li> Release l&#39;animale dai sistemi di imaging e posizionarlo a una gabbia di alloggiamento pulito con cibo normale e acqua per il suo recupero a temperatura ambiente. I sistemi sono ora pronti per l&#39;animale successivo nella coda. Nota: la cura e la gestione del post-immagini animali dovrebbe seguire dell&#39;istituto norme in materia di &quot;gestione degli animali da laboratorio iniettati con RAM&quot;. Si noti inoltre che gli aghi usati / siringhe, i pad assorbenti, guanti, biancheria da letto e tutto e la materia fecale devono essere considerati come rifiuti radioattivi, e trattati secondo le norme dell&#39;istituto pertinenti RAM di smaltimento di rifiuti. </li></ol> 5. Post-analisi di imaging <ol><li> Apri ricerca Inveon Workplace (IRW) software (Siemens) e importare manualmente sia TC e dati PET set. Co-registrazione TC e immagini PET nella finestra &quot;Registrazione&quot; utilizzando gli strumenti con il &quot;generale analisi&quot; la funzione, e sotto la finestra &quot;Review&quot; assicurarsi un perfetto allineamento tra TC e immagini PET in tutte le 3 dimensioni. </li><li>Da &quot;regione di interesse (ROI) Quantificazione&quot; finestra, con i riferimenti forniti dal co-registrate le immagini TAC, identificare BAT alla regione interscapolare del collo, il più predominante freddo inducibile BAT in topi adulti, e disegnare il volume di interesse (VOI) di BAT sul set di dati PET. Selezionare &quot;Intensità Voxel&quot; come &quot;Tipo Quantificazione&quot; e registrare la radioattività media all&#39;interno del VOI come Bq / ml. Un fattore di calibrazione che converte i conteggi / sec di Bq / ml è stato precedentemente stabilito mediante la scansione di un fantasma con radioattività nota. </li><li> Captazione di FDG nel BAT è quantificato come dose percentuale iniettata per grammo di tessuto (% ID / g) con correzione decadimento. La dose iniettata è il risultato del Passaggio 3,5, tuttavia, convertito becquerel (Bq) Unità (1 uCi = 37.000 Bq); assumiamo che 1 ml di tessuto pari a 1 g. </li></ol>

<ol>
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Nessun conflitto di interessi dichiarati.

In questo studio un metodo di imaging micro-PET/CT-based è stato sviluppato per rilevare attività BAT in topi adulti che richiede soltanto un trattamento a freddo e una iniezione di commercialmente disponibile 18 F-FDG. L&#39;intera procedura può essere fatto in un giorno dopo un trattamento e sequenza di immagini che parte ogni 30 minuti fino a quando tutti gli animali vengono trattati e ripreso. Nelle condizioni sperimentali descritte, un totale di 10 topi (o due gruppi di 5 topi) possono essere testati ...

<table border="1"><tbody><tr><td> Nome del reagente </td><td> Azienda </td><td> Numero di catalogo </td><td> Commenti (opzionale) </td></tr><tr><td> Micro-PET/CT Imaging System </td><td> Siemens Medical Solutions USA, Inc. </td><td> Inveon dedicato PET e di sistema Inveon multimodalità CT / SPECT del sistema (inserito) </td><td></td></tr><tr><td> Propranolol </td><td> Sigma </td><td> P0884 </td><td></td></tr><tr><td> BRL 37344 </td><td> Sigma </td><td> B169 </td><td></td></tr><tr><td> 18 F-FDG </td><td> Cyclotope Inc. </td><td></td><td></td></tr><tr><td> Mice C57BL/6J Maschio </td><td> Jackson Laboratory </td><td> 000664 </td><td> 3-4 mesi vecchio </td></tr></tbody></table>

functional imaging of brown fat in mice with 18f-fdg micro-pet/ct

Tessuto adiposo bruno (BAT) si differenzia dal tessuto adiposo bianco (WAT) per la sua posizione discreta e un colore marrone-rosso a causa della vascolarizzazione ricca e alta densità di mitocondri. BAT svolge un ruolo importante nel dispendio energetico e non brividi termogenesi nei mammiferi neonati e gli adulti 1. BAT-mediata termogenesi è altamente regolata dal sistema nervoso simpatico, prevalentemente attraverso i recettori adrenergici β 2, 3. Recenti studi hanno dimostrato che le attività BAT negli adulti umani sono negativamente correlati con l&#39;indice di massa corporea (BMI) e altri parametri diabetici 4-6. BAT è stato quindi proposto come un potenziale bersaglio per la terapia anti-obesity/anti-diabetes focalizzazione sulla modulazione di bilancio energetico 6-8. Mentre diverse freddi sfida basati tomografia a emissione di positroni (PET) sono stabiliti metodi per rilevare BAT 9-13 umana, non vi è essenzialmente alcun protocollo standard per l&#39;imaging e quantificazione delle BAT in modelli animali di piccole dimensioni come i topi. Qui descriviamo un robusto PET / CT metodo di imaging per la valutazione funzionale della BAT nei topi. In breve, i topi adulti C57BL/6J sono stati trattati a freddo in condizioni di digiuno per una durata di 4 ore prima di aver ricevuto una dose di 18 F-Fluorodeoxyglucose (FDG). I topi sono stati rimasta al freddo per una ulteriore ora dopo l&#39;iniezione FDG, e poi scansionato con un piccolo animale sistema dedicato micro-PET/CT. Le immagini PET acquisite erano co-registrate con le immagini TC per i riferimenti anatomici e analizzati per la captazione di FDG nella zona BAT interscapolare per presentare l&#39;attività BAT. Questo trattamento standardizzato freddo e protocollo di imaging è stato convalidato attraverso attività BAT test durante interventi farmacologici, per esempio, l&#39;attivazione BAT soppressa dal trattamento di β-adrenergico antagonista propranololo 14, 15, o l&#39;attivazione BAT potenziata β3 agonisti BRL37344 16. Il metodo described qui può essere applicato per lo screening per i farmaci / composti che modulano l&#39;attività BAT, o per identificare i geni / pathways che sono coinvolti nello sviluppo BAT e regolazione in vari studi preclinici e di base.

Un esempio di imaging micro-PET/CT di BAT mouse viene mostrato in Figura 1. Mentre l&#39;imaging CT fornisce informazioni anatomiche, il PET codifica la distribuzione e la quantità di 18 F-FDG tutto il corpo. Questi dati di imaging possono essere visualizzati separatamente (1A e 1B), fusa (1C), o risultare in una funzione 3D come proiezione massima intensità (MIP, 1D). Con l&#39;aiuto di uno strumento di imaging 3D, un volume di interesse (VOI), qui la regione interscapolare BAT (indicato d...

Watch this Scientific Journal Video about Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT at JoVE.com

Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT

Un metodo di imaging funzionale di tessuto adiposo bruno topo (BAT) è descritto in cui freddo stimolato l&#39;assorbimento di 18F-fluorodesossiglucosio (FDG) in BAT è non invasivo valutata con un protocollo standardizzato micro-PET/CT. Questo metodo è robusto e sensibile per rilevare le differenze nelle attività BAT in modelli murini.

Imaging funzionale del grasso bruno nei topi con FDG micro-PET/CT

Brown adipose tissue (BAT) differs from white adipose  tissue (WAT) by its discrete location and a brown-red color due to rich  vascularization and high ...

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Biology

Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT

19.0K Views.  The Methodist Hospital Research Institute, Houston. Un metodo di imaging funzionale di tessuto adiposo bruno topo (BAT) è descritto in cui freddo stimolato l'assorbimento di 18F-fluorodesossiglucosio (FDG) in BAT è non invasivo valutata con un protocollo standardizzato micro-PET/CT. Questo metodo è robusto e sensibile per rilevare le differenze nelle attività BAT in modelli murini.

Video: Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT

Utilizing 18F-FDG PET/CT Imaging and Quantitative Histology to Measure Dynamic Changes in the Glucose Metabolism in Mouse Models of Lung Cancer

A hallmark of advanced tumors is a switch to aerobic glycolysis that is readily measured by [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) imaging. Co-mutations in the KRAS proto-oncogene and the LKB1 tumor suppressor gene are frequent events in lung cancer that drive hypermetabolic, glycolytic tumor growth. A critical pathway regulating the growth and metabolism of these tumors is the mechanistic target of the rapamycin (mTOR) pathway, which can be effectively targeted using selective catalytic mTOR kinase inhibitors. The mTOR inhibitor MLN0128 suppresses glycolysis in mice bearing tumors with Kras and Lkb1 co-mutations, referred to as KL mice. The therapy response in KL mice is first measured by 18F-FDG PET and computed tomography (CT) imaging before and after the delivery of MLN0128. By utilizing 18F-FDG PET/CT, researchers are able to measure dynamic changes in the glucose metabolism in genetically engineered mouse models (GEMMs) of lung cancer following a therapeutic intervention with targeted therapies. This is followed by ex vivo autoradiography and a quantitative immunohistochemical (qIHC) analysis using morphometric software. The use of qIHC enables the detection and quantification of distinct changes in the biomarker profiles following treatment as well as the characterization of distinct tumor pathologies. The coupling of PET imaging to quantitative histology is an effective strategy to identify metabolic and therapeutic responses in vivo in mouse models of disease.

Utilizing 18F-FDG PET/CT Imaging and Quantitative Histology to Measure Dynamic Changes in the Glucose Metabolism in Mouse Models of Lung Cancer

In this protocol, we describe how to utilize [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (18F-FDG PET/CT) imaging to measure the tumor metabolic response to the targeted therapy MLN0128 in a Kras/Lkb1 mutant mouse model of lung cancer and coupled imaging with high resolution ex vivo autoradiography and quantitative histology.

Utilizzando 18F-FDG PET/CT Imaging e l'istologia quantitativa per misurare i cambiamenti dinamici nel metabolismo del glucosio in modelli murini di cancro ai polmoni

A hallmark of advanced tumors is a switch to aerobic glycolysis that is readily measured by [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography ...

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Non-Invasive PET/MR Imaging in an Orthotopic Mouse Model of Hepatocellular Carcinoma

Preclinical experimental models of hepatocellular carcinoma (HCC) that recapitulate human disease represent an important tool to study tumorigenesis and evaluate novel therapeutic approaches. Non-invasive whole-body imaging using positron emission tomography (PET) provides critical insights into the in vivo characteristics of tissues at the molecular level in real-time. We present here a protocol for orthotopic HCC xenograft creation with and without hepatic artery ligation (HAL) to induce tumor hypoxia and the assessment of their tumor metabolism in vivo using [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluorodeoxyglucose ([18F]FDG) PET/magnetic resonance (MR) imaging. Tumor hypoxia could be readily visualized using the hypoxia marker [18F]FMISO, and it was found that the [18F]FMISO uptake was higher in HCC mice that underwent HAL than in the non-HAL group, whereas [18F]FDG could not distinguish tumor hypoxia between the two groups. HAL tumors also displayed a higher level of hypoxia-inducible factor (HIF)-1&#945; expression in response to hypoxia. Quantification of HAL tumors showed a 2.3-fold increase in [18F]FMISO uptake based on the standardized value uptake (SUV) approach.

Here, we present a protocol to create orthotopic hepatocellular carcinoma xenografts with and without hepatic artery ligation and perform non-invasive positron emission tomography (PET) imaging of tumor hypoxia using [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluorodeoxyglucose ([18F]FDG).

Imaging PET/RM non invasivo in un modello murino ortotopico di carcinoma epatocellulare

Preclinical experimental models of hepatocellular carcinoma (HCC) that recapitulate human disease represent an important tool to study tumorigenesis and ...

Cerenkov Luminescence Imaging of Interscapular Brown Adipose Tissue

Brown adipose tissue (BAT), widely known as a &#8220;good fat&#8221; plays pivotal roles for thermogenesis in mammals. This special tissue is closely related to metabolism and energy expenditure, and its dysfunction is one important contributor for obesity and diabetes. Contrary to previous belief, recent PET/CT imaging studies indicated the BAT depots are still present in human adults. PET imaging clearly shows that BAT has considerably high uptake of 18F-FDG under certain conditions. In this video report, we demonstrate that Cerenkov luminescence imaging (CLI) with 18F-FDG can be used to optically image BAT in small animals. BAT activation is observed after intraperitoneal injection of norepinephrine (NE) and cold treatment, and depression of BAT is induced by long anesthesia. Using multiple-filter Cerenkov luminescence imaging, spectral unmixing and 3D imaging reconstruction are demonstrated. Our results suggest that CLI with 18F-FDG is a practical technique for imaging BAT in small animals, and this technique can be used as a cheap, fast, and alternative imaging tool for BAT research.

In this video report, we show the application of Cerenkov Luminescence Imaging (CLI) for interscapular brown adipose tissue in mice under activated and depressed conditions.

Cerenkov Luminescenza Imaging di interscapolare Brown Tessuto adiposo

Brown adipose tissue (BAT), widely known as a &#8220;good fat&#8221; plays pivotal roles for thermogenesis in mammals. This special tissue is closely ...

Medicina

Human Brown Adipose Tissue Depots Automatically Segmented by Positron Emission Tomography/Computed Tomography and Registered Magnetic Resonance Images

Reliably differentiating brown adipose tissue (BAT) from other tissues using a non-invasive imaging method is an important step toward studying BAT in humans. Detecting BAT is typically confirmed by the uptake of the injected radioactive tracer 18F-Fluorodeoxyglucose (18F-FDG) into adipose tissue depots, as measured by positron emission tomography/computed tomography (PET-CT) scans after exposing the subject to cold stimulus. Fat-water separated magnetic resonance imaging (MRI) has the ability to distinguish BAT without the use of a radioactive tracer. To date, MRI of BAT in adult humans has not been co-registered with cold-activated PET-CT. Therefore, this protocol uses 18F-FDG PET-CT scans to automatically generate a BAT mask, which is then applied to co-registered MRI scans of the same subject. This approach enables measurement of quantitative MRI properties of BAT without manual segmentation. BAT masks are created from two PET-CT scans: after exposure for 2 hr to either thermoneutral (TN) (24 &#176;C) or cold-activated (CA) (17 &#176;C) conditions. The TN and CA PET-CT scans are registered, and the PET standardized uptake and CT Hounsfield values are used to create a mask containing only BAT. CA and TN MRI scans are also acquired on the same subject and registered to the PET-CT scans in order to establish quantitative MRI properties within the automatically defined BAT mask. An advantage of this approach is that the segmentation is completely automated and is based on widely accepted methods for identification of activated BAT (PET-CT). The quantitative MRI properties of BAT established using this protocol can serve as the basis for an MRI-only BAT examination that avoids the radiation associated with PET-CT.

The method presented here uses 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET-CT) and fat-water separated magnetic resonance imaging (MRI), each scanned following 2 hr exposure to thermoneutral (24 &#176;C) and cold conditions (17 &#176;C) in order to map brown adipose tissue (BAT) in adult human subjects.

Umano Brown adipose Depositi tessuti segmentato automaticamente da Positron Emission Tomography / tomografia computerizzata e registrati Risonanza Magnetica Images

Reliably differentiating brown adipose tissue (BAT) from other tissues using a non-invasive imaging method is an important step toward studying BAT in ...

Determining Glucose Metabolism Kinetics Using 18F-FDG Micro-PET/CT

This paper describes the use of 18F-FDG and micro-PET/CT imaging to determine in vivo glucose metabolism kinetics in mice (and is transferable to rats). Impaired uptake and metabolism of glucose in multiple organ systems due to insulin resistance is a hallmark of type 2 diabetes. The ability of this technique to extract an image-derived input function from the vena cava using an iterative deconvolution method eliminates the requirement of the collection of arterial blood samples. Fitting of tissue and vena cava time activity curves to a two-tissue, three compartment model permits the estimation of kinetic micro-parameters related to the 18F-FDG uptake from the plasma to the intracellular space, the rate of transport from intracellular space to plasma and the rate of 18F-FDG phosphorylation. This methodology allows for multiple measures of glucose uptake and metabolism kinetics in the context of longitudinal studies and also provides insights into the efficacy of therapeutic interventions.

Determining Glucose Metabolism Kinetics Using 18F-FDG Micro-PET/CT

This study describes a protocol that uses 18F-FDG and positron emission tomography/computed tomography (PET/CT) imaging, together with kinetic modelling, to quantify the in vivo, real-time uptake of 18F-FDG into tissues.

Determinazione metabolismo del glucosio Cinetica Utilizzando<sup&gt; 18</sup&gt; F-FDG micro-PET / TC

This paper describes the use of 18F-FDG and micro-PET/CT imaging to determine in vivo glucose metabolism kinetics in mice (and is transferable to rats). ...

Whole Body and Regional Quantification of Active Human Brown Adipose Tissue Using 18F-FDG PET/CT

In endothermic animals, brown adipose tissue (BAT) is activated to produce heat for defending body temperature in response to cold. BAT&#39;s ability to expend energy has made it a potential target for novel therapies to ameliorate obesity and associated metabolic disorders in humans. Though this tissue has been well studied in small animals, BAT&#39;s thermogenic capacity in humans remains largely unknown due to the difficulties of measuring its volume, activity, and distribution. Identifying and quantifying active human BAT is commonly performed using 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET/CT) scans following cold-exposure or pharmacological activation. Here we describe a detailed image-analysis approach to quantify total-body human BAT from 18F-FDG PET/CT scans using an open-source software. We demonstrate the drawing of user-specified regions of interest to identify metabolically active adipose tissue while avoiding common non-BAT tissues, to measure BAT volume and activity, and to further characterize its anatomical distribution. Although this rigorous approach is time-consuming, we believe it will ultimately provide a foundation to develop future automated BAT quantification algorithms.

Whole Body and Regional Quantification of Active Human Brown Adipose Tissue Using 18F-FDG PET/CT

Using free, open-source software, we have developed an analytical approach to quantify total and regional brown adipose tissue (BAT) volume and metabolic activity of BAT using 18F-FDG PET/CT.

Tutto il corpo e quantificazione regionale dell'essere umano attivo marrone tessuto adiposo con 18F-FDG PET/CT

In endothermic animals, brown adipose tissue (BAT) is activated to produce heat for defending body temperature in response to cold. BAT&#39;s ability to ...

Infrared Thermography for the Detection of Changes in Brown Adipose Tissue Activity

Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of 18F-fluorodeoxyglucose (FDG) after a meal or in obese or diabetic patients fails as the method of choice. The main reason is that 18F-FDG competes with the postprandial high glucose plasma concentration for the same glucose transporter on the membrane of BAT cells. In addition, BAT uses fatty acids as a source of energy as well, which is not visible with PET-CT and could be changed along with glucose concentration in obese and diabetic patients. Therefore, to estimate the physiological importance of BAT in animals and humans, a new infrared thermography method used in recent publications is applied.
After overnight fasting, BAT activity was measured by infrared thermography before and after a meal in human volunteers and&#160;female wild-type mice. The camera software calculates the object&#39;s temperature using distance from the object, skin emissivity, reflected room temperature, air temperature, and relative humidity. In mice, the shaved area above the BAT was a region of interest for which average and maximal temperatures were measured. The phase of the estrous cycle in female mice was determined after an experiment by vaginal smears stained with cresyl violet (0.1%) stain solution. In healthy volunteers, two skin areas of the neck were selected: the supraclavicular area (above the collarbone, where BAT cells are present) and the interclavicular area (between the collarbones, where there is no BAT tissue detected). BAT activity is determined by the subtraction of those two values. Also, the average and maximal temperatures of skin areas could be determined in animals and human participants.
Changes in BAT activity after a meal measured by infrared thermography, a non-invasive and more sensitive method, were shown to be sex, age, and phase of the estrous cycle dependent in laboratory animals. As part of diet-induced thermogenesis, BAT activation in humans was also proven to be sex, age, and body mass index dependent. Further determining the pathophysiological changes in BAT activity after a meal will be of great importance for participants with high glucose plasma concentrations (obesity and diabetes mellitus type 2), as well as in different laboratory animals (knock-out mice). This method is also a variable tool for determining possible activating drugs that could rejuvenate BAT activity.

Here, we present a protocol for measuring brown adipose tissue activity after a meal in humans and laboratory animals.

Termografia a infrarossi per la rilevazione di cambiamenti nell'attività del tessuto adiposo bruno

Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of 18F-fluorodeoxyglucose ...

High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals

Positron emission tomography (PET) and computed tomography (CT) are among the most employed diagnostic imaging techniques, and both serve in understanding cardiac function and metabolism. In preclinical research, dedicated scanners with high sensitivity and high spatio-temporal resolution are employed, designed to cope with the demanding technological requirements posed by the small heart size and very high heart rates of mice and rats. In this paper, a bimodal cardiac PET/CT imaging protocol for experimental mouse and/or rat models of cardiac diseases is described, from animal preparation and image acquisition and reconstruction to image processing and visualization.
In particular, the 18F-labeled fluorodeoxyglucose ([18F]FDG)-PET scan allows for the measurement and visualization of glucose metabolism in the different segments of the left ventricle (LV). Polar maps are convenient tools to display this information. The CT part consists of a time-resolved 3D reconstruction of the entire heart (4D-CT) using retrospective gating without electrocardiography (ECG) leads, allowing the morphofunctional evaluation of the LV and the subsequent quantification of the most important cardiac function parameters, such as ejection fraction (EF) and stroke volume (SV). Using an integrated PET/CT scanner, this protocol can be executed within the same anesthesia induction without the need to reposition the animal between different scanners. Hence, PET/CT can be seen as a comprehensive tool for the morphofunctional and metabolic evaluation of the heart in several small animal models of cardiac diseases.

Here, we present an experimental imaging protocol for the quantification of cardiac function and morphology using high-resolution positron emission tomography/computed tomography for small animals. Both mice and rats are considered, discussing the different requirements of computed tomography contrast agents for the two species.

Tomografia cardiaca ad emissione di positroni ad alta risoluzione/tomografia computerizzata per piccoli animali

Positron emission tomography (PET) and computed tomography (CT) are among the most employed diagnostic imaging techniques, and both serve in understanding ...

Visualization and Quantification of Brown and Beige Adipose Tissues in Mice using [18F]FDG Micro-PET/MR Imaging

Brown and beige adipocytes are now recognized as potential therapeutic targets for obesity and metabolic syndromes. Non-invasive molecular imaging methods are essential to provide critical insights into these thermogenic adipose depots. Here, the protocol presents a PET/MR imaging-based method to evaluate the activity of brown and beige adipocytes in mouse interscapular brown adipose tissue (iBAT) and inguinal subcutaneous white adipose tissue (iWAT). Visualization and quantification of the thermogenic adipose depots were achieved using [18F]FDG, the non-metabolizable glucose analog, as the radiotracer, when combined with the precise anatomical information provided by MR imaging. The PET/MR imaging was conducted 7 days after cold acclimation and quantitation of [18F]FDG signal in different adipose depots was conducted to assess the relative mobilization of thermogenic adipose tissues. Removal of iBAT substantially increased cold-evoked [18F]FDG uptake in iWAT of the mice.

Visualization and Quantification of Brown and Beige Adipose Tissues in Mice using [18F]FDG Micro-PET/MR Imaging

Functional imaging and quantitation of thermogenic adipose depots in mice using a micro-PET/MR imaging-based approach.

Visualizzazione e quantificazione dei tessuti adiposi marroni e beige nei topi utilizzando [18F]FDG Micro-PET/MR Imaging

Brown and beige adipocytes are now recognized as potential therapeutic targets for obesity and metabolic syndromes. Non-invasive molecular imaging methods ...

Biologia

FDG Based PET/CT Scan: A Method of Using Radiotracer for Non-invasive Imaging of Tumor Metabolism

Source: Momcilovic M. et al., <a href="https://www.jove.com/v/57167/utilizing-18f-fdg-petct-imaging-quantitative-histology-to-measure">Utilizing&#160;18F-FDG PET/CT Imaging and Quantitative Histology to Measure Dynamic Changes in the Glucose Metabolism in Mouse Models of Lung Cancer.</a> J. Vis. Exp. (2018)
This article describes multimodality imaging of cancerous tissues with PET and CT diagnostic imaging by using a radiotracer 18F-FDG. Cancerous tissue with high glycolytic activity uptakes more 18F-FDG.

Scansione PET/TC basata su FDG: un metodo per l'utilizzo del radiotracciante per l'imaging non invasivo del metabolismo tumorale

Source: Momcilovic M. et al., Utilizing&#160;18F-FDG PET/CT Imaging and Quantitative Histology to Measure Dynamic Changes in the Glucose Metabolism in ...

Imaging funzionale del grasso bruno nei topi con FDG micro-PET/CT

Riepilogo

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