@article{DaViaSolimandoGaritanoTrojaolaetal.2019, author = {Da Vi{\`a}, Matteo Claudio and Solimando, Antonio Giovanni and Garitano-Trojaola, Andoni and Barrio, Santiago and Munawar, Umair and Strifler, Susanne and Haertle, Larissa and Rhodes, Nadine and Vogt, Cornelia and Lapa, Constantin and Beilhack, Andreas and Rasche, Leo and Einsele, Hermann and Kort{\"u}m, K. Martin}, title = {CIC Mutation as a Molecular Mechanism of Acquired Resistance to Combined BRAF-MEK Inhibition in Extramedullary Multiple Myeloma with Central Nervous System Involvement}, series = {The Oncologist}, volume = {25}, journal = {The Oncologist}, number = {2}, doi = {10.1634/theoncologist.2019-0356}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219549}, pages = {112-118}, year = {2019}, abstract = {Combined MEK-BRAF inhibition is a well-established treatment strategy in BRAF-mutated cancer, most prominently in malignant melanoma with durable responses being achieved through this targeted therapy. However, a subset of patients face primary unresponsiveness despite presence of the activating mutation at position V600E, and others acquire resistance under treatment. Underlying resistance mechanisms are largely unknown, and diagnostic tests to predict tumor response to BRAF-MEK inhibitor treatment are unavailable. Multiple myeloma represents the second most common hematologic malignancy, and point mutations in BRAF are detectable in about 10\% of patients. Targeted inhibition has been successfully applied, with mixed responses observed in a substantial subset of patients mirroring the widespread spatial heterogeneity in this genomically complex disease. Central nervous system (CNS) involvement is an extremely rare, extramedullary form of multiple myeloma that can be diagnosed in less than 1\% of patients. It is considered an ultimate high-risk feature, associated with unfavorable cytogenetics, and, even with intense treatment applied, survival is short, reaching less than 12 months in most cases. Here we not only describe the first patient with an extramedullary CNS relapse responding to targeted dabrafenib and trametinib treatment, we furthermore provide evidence that a point mutation within the capicua transcriptional repressor (CIC) gene mediated the acquired resistance in this patient.}, language = {en} } @article{EisslerWernerAriasLozaetal.2021, author = {Eissler, Cristoph and Werner, Rudolf A. and Arias-Loza, Paula and Nose, Naoko and Chen, Xinyu and Pomper, Martin G. and Rowe, Steven P. and Lapa, Constantin and Buck, Andreas K. and Higuchi, Takahiro}, title = {The number of frames on ECG-gated \(^{18}\)F-FDG small animal PET has a significant impact on LV systolic and diastolic functional parameters}, series = {Molecular Imaging}, volume = {2021}, journal = {Molecular Imaging}, doi = {10.1155/2021/4629459}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265778}, year = {2021}, abstract = {Objectives. This study is aimed at investigating the impact of frame numbers in preclinical electrocardiogram- (ECG-) gated \(^{18}\)F-fluorodeoxyglucose (\(^{18}\)F-FDG) positron emission tomography (PET) on systolic and diastolic left ventricular (LV) parameters in rats. Methods. \(^{18}\)F-FDG PET imaging using a dedicated small animal PET system with list mode data acquisition and continuous ECG recording was performed in diabetic and control rats. The list-mode data was sorted and reconstructed with different numbers of frames (4, 8, 12, and 16) per cardiac cycle into tomographic images. Using an automatic ventricular edge detection software, left ventricular (LV) functional parameters, including ejection fraction (EF), end-diastolic (EDV), and end-systolic volume (ESV), were calculated. Diastolic variables (time to peak filling (TPF), first third mean filling rate (1/3 FR), and peak filling rate (PFR)) were also assessed. Results. Significant differences in multiple parameters were observed among the reconstructions with different frames per cardiac cycle. EDV significantly increased by numbers of frames (353.8 \& PLUSMN; 57.7 mu l*, 380.8 \& PLUSMN; 57.2 mu l*, 398.0 \& PLUSMN; 63.1 mu l*, and 444.8 \& PLUSMN; 75.3 mu l at 4, 8, 12, and 16 frames, respectively; *P < 0.0001 vs. 16 frames), while systolic (EF) and diastolic (TPF, 1/3 FR and PFR) parameters were not significantly different between 12 and 16 frames. In addition, significant differences between diabetic and control animals in 1/3 FR and PFR in 16 frames per cardiac cycle were observed (P < 0.005), but not for 4, 8, and 12 frames. Conclusions. Using ECG-gated PET in rats, measurements of cardiac function are significantly affected by the frames per cardiac cycle. Therefore, if you are going to compare those functional parameters, a consistent number of frames should be used.}, language = {en} } @article{HartrampfHeinrichSeitzetal.2020, author = {Hartrampf, Philipp E. and Heinrich, Marieke and Seitz, Anna Katharina and Brumberg, Joachim and Sokolakis, Ioannis and Kalogirou, Charis and Schirbel, Andreas and K{\"u}bler, Hubert and Buck, Andreas K. and Lapa, Constantin and Krebs, Markus}, title = {Metabolic Tumour Volume from PSMA PET/CT Scans of Prostate Cancer Patients during Chemotherapy — Do Different Software Solutions Deliver Comparable Results?}, series = {Journal of Clinical Medicine}, volume = {9}, journal = {Journal of Clinical Medicine}, number = {5}, issn = {2077-0383}, doi = {10.3390/jcm9051390}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-205893}, year = {2020}, abstract = {(1) Background: Prostate-specific membrane antigen (PSMA)-derived tumour volume (PSMA-TV) and total lesion PSMA (TL-PSMA) from PSMA PET/CT scans are promising biomarkers for assessing treatment response in prostate cancer (PCa). Currently, it is unclear whether different software tools for assessing PSMA-TV and TL-PSMA produce comparable results. (2) Methods: \(^{68}\)Ga-PSMA PET/CT scans from n = 21 patients with castration-resistant PCa (CRPC) receiving chemotherapy were identified from our single-centre database. PSMA-TV and TL-PSMA were calculated with Syngo.via (Siemens) as well as the freely available Beth Israel plugin for FIJI (Fiji Is Just ImageJ) before and after chemotherapy. While statistical comparability was illustrated and quantified via Bland-Altman diagrams, the clinical agreement was estimated by matching PSMA-TV, TL-PSMA and relative changes of both variables during chemotherapy with changes in serum PSA (ΔPSA) and PERCIST (Positron Emission Response Criteria in Solid Tumors). (3) Results: Comparing absolute PSMA-TV and TL-PSMA as well as Bland-Altman plotting revealed a good statistical comparability of both software algorithms. For clinical agreement, classifying therapy response did not differ between PSMA-TV and TL-PSMA for both software solutions and showed highly positive correlations with BR. (4) Conclusions: due to the high levels of statistical and clinical agreement in our CRPC patient cohort undergoing taxane chemotherapy, comparing PSMA-TV and TL-PSMA determined by Syngo.via and FIJI appears feasible.}, language = {en} } @article{HartrampfLapaSerflingetal.2021, author = {Hartrampf, Philipp E. and Lapa, Constantin and Serfling, Sebastian E. and Buck, Andreas K. and Seitz, Anna Katharina and Meyer, Philipp T. and Ruf, Juri and Michalski, Kerstin}, title = {Development of Discordant Hypermetabolic Prostate Cancer Lesions in the Course of [\(^{177}\)Lu]PSMA Radioligand Therapy and Their Possible Influence on Patient Outcome}, series = {Cancers}, volume = {13}, journal = {Cancers}, number = {17}, issn = {2072-6694}, doi = {10.3390/cancers13174270}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-245168}, year = {2021}, abstract = {Simple Summary Discordant FDG-positive but PSMA-negative (FDG+/PSMA-) metastases constitute a negative prognostic marker of overall survival in patients undergoing PSMA radioligand therapy (RLT). The aim of this analysis was to investigate the prognostic implications of new FDG+/PSMA- lesions, which occur during or after PSMA RLT. In a retrospective bicentric analysis of 32 patients undergoing PSMA RLT and follow-up dual tracer staging with PSMA and FDG PET/CT, FDG+/PSMA- lesions occurred in a limited number of patients. However, the presence of FDG+/PSMA- lesions appears not to have a significant impact on the OS, but further studies are needed to establish the clinical relevance of such lesions. Abstract Introduction: Positron emission tomography/computer tomography (PET/CT) targeting the prostate-specific membrane antigen (PSMA) is crucial for the assessment of adequate PSMA expression in patients with metastatic castration-resistant prostate cancer (mCRPC) prior to PSMA radioligand therapy (PSMA RLT). Moreover, initial dual tracer staging using combined PSMA and [\(^{18}\)F]fluorodeoxyglucose (FDG) PET/CT provides relevant information, since discordant FDG-positive but PSMA-negative (FDG+/PSMA-) lesions constitute a negative prognostic marker of overall survival (OS) after PSMA RLT. However, little is known about the prognostic implications of dual tracer imaging for restaging at follow-up. The aim of this analysis was to investigate the prognostic implications of new FDG+/PSMA- lesions during or after PSMA RLT. Methods: This bicentric analysis included 32 patients with mCRPC who underwent both FDG and PSMA PET/CT imaging after two or four cycles of PSMA RLT. Patients with FDG+/PSMA- lesions prior to PSMA RLT were not considered. The presence of FDG+/PSMA- lesions was assessed with follow-up dual tracer imaging of patients after two or four cycles of PSMA RLT. Patients with at least one new FDG+/PSMA- lesion were compared to patients without any FDG+/PSMA- lesions at the respective time points. A log-rank analysis was used to assess the difference in OS between subgroups. Results: After two cycles of PSMA RLT, four of 32 patients (13\%) had FDG+/PSMA- metastases. No significant difference in OS was observed (p = 0.807), as compared to patients without FDG+/PSMA- lesions. Follow-up dual tracer imaging after the 4th cycle of PSMA RLT was available in 18 patients. Of these, four patients presented with FDG+/PSMA- findings (n = 2 already after two cycles). After the fourth cycle of PSMA RLT, no significant difference in OS was observed between patients with and without FDG+/PSMA- lesions (p = 0.442). Conclusion: This study shows that FDG+/PSMA- lesions develop in a limited number of patients undergoing PSMA RLT. Further studies are needed to establish the clinical relevance of such lesions.}, language = {en} } @article{HoffmannJanssenKannoetal.2020, author = {Hoffmann, Jan V. and Janssen, Jan P. and Kanno, Takayuki and Shibutani, Takayuki and Onoguchi, Masahisa and Lapa, Constantin and Grunz, Jan-Peter and Buck, Andreas K. and Higuchi, Takahiro}, title = {Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging}, series = {EJNMMI Physics}, volume = {7}, journal = {EJNMMI Physics}, doi = {10.1186/s40658-020-00335-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230361}, year = {2020}, abstract = {Background Small-animal single-photon emission computed tomography (SPECT) systems with multi-pinhole collimation and large stationary detectors have advantages compared to systems with moving small detectors. These systems benefit from less labour-intensive maintenance and quality control as fewer prone parts are moving, higher accuracy for focused scans and maintaining high resolution with increased sensitivity due to focused pinholes on the field of view. This study aims to investigate the performance of a novel ultra-high-resolution scanner with two-detector configuration (U-SPECT5-E) and to compare its image quality to a conventional micro-SPECT system with three stationary detectors (U-SPECT\(^+\)). Methods The new U-SPECT5-E with two stationary detectors was used for acquiring data with \(^{99m}\)Tc-filled point source, hot-rod and uniformity phantoms to analyse sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR). Three dedicated multi-pinhole mouse collimators with 75 pinholes each and 0.25-, 0.60- and 1.00-mm pinholes for extra ultra-high resolution (XUHR-M), general-purpose (GP-M) and ultra-high sensitivity (UHS-M) imaging were examined. For CNR analysis, four different activity ranges representing low- and high-count settings were investigated for all three collimators. The experiments for the performance assessment were repeated with the same GP-M collimator in the three-detector U-SPECT\(^+\) for comparison. Results Peak sensitivity was 237 cps/MBq (XUHR-M), 847 cps/MBq (GP-M), 2054 cps/MBq (UHS-M) for U-SPECT5-E and 1710 cps/MBq (GP-M) for U-SPECT\(^+\). In the visually analysed sections of the reconstructed mini Derenzo phantoms, rods as small as 0.35 mm (XUHR-M), 0.50 mm (GP-M) for the two-detector as well as the three-detector SPECT and 0.75 mm (UHS-M) were resolved. Uniformity for maximum resolution recorded 40.7\% (XUHR-M), 29.1\% (GP-M, U-SPECT5-E), 16.3\% (GP-M, U-SPECT\(^+\)) and 23.0\% (UHS-M), respectively. UHS-M reached highest CNR values for low-count images; for rods smaller than 0.45 mm, acceptable CNR was only achieved by XUHR-M. GP-M was superior for imaging rods sized from 0.60 to 1.50 mm for intermediate activity concentrations. U-SPECT5-E and U-SPECT+ both provided comparable CNR. Conclusions While uniformity and sensitivity are negatively affected by the absence of a third detector, the investigated U-SPECT5-E system with two stationary detectors delivers excellent spatial resolution and CNR comparable to the performance of an established three-detector-setup.}, language = {en} } @article{HaenscheidHartrampfSchirbeletal.2021, author = {H{\"a}nscheid, Heribert and Hartrampf, Philipp E. and Schirbel, Andreas and Buck, Andreas K. and Lapa, Constantin}, title = {Intraindividual comparison of [\(^{177}\)Lu]Lu-DOTA-EB-TATE and [\(^{177}\)Lu]Lu-DOTA-TOC}, series = {European Journal of Nuclear Medicine and Molecular Imaging}, volume = {48}, journal = {European Journal of Nuclear Medicine and Molecular Imaging}, number = {8}, issn = {1619-7089}, doi = {10.1007/s00259-020-05177-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265470}, pages = {2566-2572}, year = {2021}, abstract = {Purpose The radiolabelled somatostatin analogue [\(^{177}\)Lu]Lu-DOTA-EB-TATE binds to albumin via Evans blue, thereby increasing the residence time in the blood and potentially allowing more therapeutic agent to be absorbed into the target tissue during peptide receptor radionuclide therapy. It was tested in selected patients whether the substance is superior to [\(^{177}\)Lu]Lu-DOTA-TOC. Methods Activity kinetics in organs and tumours after [\(^{177}\)Lu]Lu-DOTA-EB-TATE and [\(^{177}\)Lu]Lu-DOTA-TOC were compared intraindividually in five patients with progressive somatostatin receptor-positive disease scheduled for radionuclide therapy. Resuluts In comparison to [\(^{177}\)Lu]Lu-DOTA-TOC, tumour doses per administered activity were higher for [\(^{177}\)Lu]Lu-DOTA-EB-TATE in 4 of 5 patients (median ratio: 1.7; range: 0.9 to 3.9), kidney doses (median ratio: 3.2; range: 1.6 to 9.8) as well as spleen doses (median ratio: 4.7; range 1.2 to 6.2) in all patients, and liver doses in 3 of 4 evaluable patients (median ratio: 4.0; range: 0.7 to 4.9). The tumour to critical organs absorbed dose ratios were higher after [\(^{177}\)Lu]Lu-DOTA-TOC in 4 of 5 patients. Conclusions Prior to a treatment with [\(^{177}\)Lu]Lu-DOTA-EB-TATE, it should be assessed individually whether the compound is superior to established substances.}, language = {en} } @article{JanssenHoffmannKannoetal.2020, author = {Janssen, Jan P. and Hoffmann, Jan V. and Kanno, Takayuki and Nose, Naoko and Grunz, Jan-Peter and Onoguchi, Masahisa and Chen, Xinyu and Lapa, Constantin and Buck, Andreas K. and Higuchi, Takahiro}, title = {Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, doi = {10.1038/s41598-020-75696-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230616}, year = {2020}, abstract = {We aimed to investigate the image quality of the U-SPECT5/CT E-Class a micro single-photon emission computed tomography (SPECT) system with two large stationary detectors for visualization of rat hearts and bones using clinically available \(^{99m}\)Tc-labelled tracers. Sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR) of the small-animal SPECT scanner were investigated in phantom studies using an ultra-high-resolution rat and mouse multi-pinhole collimator (UHR-RM). Point source, hot-rod, and uniform phantoms with \(^{99m}\)Tc-solution were scanned for high-count performance assessment and count levels equal to animal scans, respectively. Reconstruction was performed using the similarity-regulated ordered-subsets expectation maximization (SROSEM) algorithm with Gaussian smoothing. Rats were injected with similar to 100 MBq [\(^{99m}\)TcTc-MIBI or similar to 150 MBq [\(^{99m}\)Tc]Tc-HMDP and received multi-frame micro-SPECT imaging after tracer distribution. Animal scans were reconstructed for three different acquisition times and post-processed with different sized Gaussian filters. Following reconstruction, CNR was calculated and image quality evaluated by three independent readers on a five-point scale from 1="very poor" to 5="very good". Point source sensitivity was 567 cps/MBq and radioactive rods as small as 1.2 mm were resolved with the UHR-RM collimator. Collimator-dependent uniformity was 55.5\%. Phantom CNR improved with increasing rod size, filter size and activity concentration. Left ventricle and bone structures were successfully visualized in rat experiments. Image quality was strongly affected by the extent of post-filtering, whereas scan time did not have substantial influence on visual assessment. Good image quality was achieved for resolution range greater than 1.8 mm in bone and 2.8 mm in heart. The recently introduced small animal SPECT system with two stationary detectors and UHR-RM collimator is capable to provide excellent image quality in heart and bone scans in a rat using standardized reconstruction parameters and appropriate post-filtering. However, there are still challenges in achieving maximum system resolution in the sub-millimeter range with in vivo settings under limited injection dose and acquisition time.}, language = {en} } @article{KlaesnerBuchmannGemptetal.2015, author = {Kl{\"a}sner, Benjamin and Buchmann, Niels and Gempt, Jens and Ringel, Florian and Lapa, Constantin and Krause, Bernd Joachim}, title = {Early [\(^{18}\)F]FET-PET in Gliomas after Surgical Resection: Comparison with MRI and Histopathology}, series = {PLoS One}, volume = {10}, journal = {PLoS One}, number = {10}, doi = {10.1371/journal.pone.0141153}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139549}, pages = {e0141153}, year = {2015}, abstract = {Background The precise definition of the post-operative resection status in high-grade gliomas (HGG) is crucial for further management. We aimed to assess the feasibility of assessment of the resection status with early post-operative positron emission tomography (PET) using [\(^{18}\)F]O-(2-[\(^{18}\)F]-fluoroethyl)-L-tyrosine ([\(^{18}\)F]FET). Methods 25 patients with the suspicion of primary HGG were enrolled. All patients underwent preoperative [\(^{18}\)F]FET-PET and magnetic resonance imaging (MRI). Intra-operatively, resection status was assessed using 5-aminolevulinic acid (5-ALA). Imaging was repeated within 72h after neurosurgery. Post-operative [\(^{18}\)F]FET-PET was compared with MRI, intra-operative assessment and clinical follow-up. Results [\(^{18}\)F]FET-PET, MRI and intra-operative assessment consistently revealed complete resection in 12/25 (48\%) patients and incomplete resection in 6/25 cases (24\%). In 7 patients, PET revealed discordant findings. One patient was re-resected. 3/7 experienced tumor recurrence, 3/7 died shortly after brain surgery. Conclusion Early assessment of the resection status in HGG with [\(^{18}\)F]FET-PET seems to be feasible.}, language = {en} } @article{KosmalaSerflingDreheretal.2022, author = {Kosmala, Aleksander and Serfling, Sebastian E. and Dreher, Niklas and Lindner, Thomas and Schirbel, Andreas and Lapa, Constantin and Higuchi, Takahiro and Buck, Andreas K. and Weich, Alexander and Werner, Rudolf A.}, title = {Associations between normal organs and tumor burden in patients imaged with fibroblast activation protein inhibitor-directed positron emission tomography}, series = {Cancers}, volume = {14}, journal = {Cancers}, number = {11}, issn = {2072-6694}, doi = {10.3390/cancers14112609}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-275154}, year = {2022}, abstract = {(1) Background: We aimed to quantitatively investigate [\(^{68}\)Ga]Ga-FAPI-04 uptake in normal organs and to assess a relationship with the extent of FAPI-avid tumor burden. (2) Methods: In this single-center retrospective analysis, thirty-four patients with solid cancers underwent a total of 40 [\(^{68}\)Ga]Ga-FAPI-04 PET/CT scans. Mean standardized uptake values (SUV\(_{mean}\)) for normal organs were established by placing volumes of interest (VOIs) in the heart, liver, spleen, pancreas, kidneys, and bone marrow. Total tumor burden was determined by manual segmentation of tumor lesions with increased uptake. For tumor burden, quantitative assessment included maximum SUV (SUV\(_{max}\)), tumor volume (TV), and fractional tumor activity (FTA = TV × SUV\(_{mean}\)). Associations between uptake in normal organs and tumor burden were investigated by applying Spearman's rank correlation coefficient. (3) Results: Median SUV\(_{mean}\) values were 2.15 in the pancreas (range, 1.05-9.91), 1.42 in the right (range, 0.57-3.06) and 1.41 in the left kidney (range, 0.73-2.97), 1.2 in the heart (range, 0.46-2.59), 0.86 in the spleen (range, 0.55-1.58), 0.65 in the liver (range, 0.31-2.11), and 0.57 in the bone marrow (range, 0.26-0.94). We observed a trend towards significance for uptake in the myocardium and tumor-derived SUV\(_{max}\) (ρ = 0.29, p = 0.07) and TV (ρ = -0.30, p = 0.06). No significant correlation was achieved for any of the other organs: SUV\(_{max}\) (ρ ≤ 0.1, p ≥ 0.42), TV (ρ ≤ 0.11, p ≥ 0.43), and FTA (ρ ≤ 0.14, p ≥ 0.38). In a sub-analysis exclusively investigating patients with high tumor burden, significant correlations of myocardial uptake with tumor SUV\(_{max}\) (ρ = 0.44; p = 0.03) and tumor-derived FTA with liver uptake (ρ = 0.47; p = 0.02) were recorded. (4) Conclusions: In this proof-of-concept study, quantification of [\(^{68}\)Ga]Ga-FAPI-04 PET showed no significant correlation between normal organs and tumor burden, except for a trend in the myocardium. Those preliminary findings may trigger future studies to determine possible implications for treatment with radioactive FAP-targeted drugs, as higher tumor load or uptake may not lead to decreased doses in the majority of normal organs.}, language = {en} } @article{LapaAriasLozaHayakawaetal.2017, author = {Lapa, Constantin and Arias-Loza, Paula and Hayakawa, Nobuyuki and Wakabayashi, Hiroshi and Werner, Rudolf A. and Chen, Xinyu and Shinaji, Tetsuya and Herrmann, Ken and Pelzer, Theo and Higuchi, Takahiro}, title = {Whitening and impaired glucose utilization of brown adipose tissue in a rat model of type 2 diabetes mellitus}, series = {Scientific Reports}, volume = {7}, journal = {Scientific Reports}, doi = {10.1038/s41598-017-17148-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159066}, pages = {16795}, year = {2017}, abstract = {Brown adipose tissue (BAT) is an attractive therapeutic target to combat diabetes and obesity due to its ability to increase glucose expenditure. In a genetic rat model (ZDF fa/fa) of type-2 diabetes and obesity, we aimed to investigate glucose utilization of BAT by \(^{18}\)F-FDG PET imaging. Male Zucker diabetic fatty (ZDF) and Male Zucker lean (ZL) control rats were studied at 13 weeks. Three weeks prior to imaging, ZDF rats were randomized into a no-restriction (ZDF-ND) and a mild calorie restriction (ZDF-CR) group. Dynamic \(^{18}\)F-FDG PET using a dedicated small animal PET system was performed under hyperinsulinemic-euglycemic clamp. \(^{18}\)F-FDG PET identified intense inter-scapular BAT glucose uptake in all ZL control rats, while no focally increased \(^{18}\)F-FDG uptake was detected in all ZDF-ND rats. Mild but significant improved BAT tracer uptake was identified after calorie restriction in diabetic rats (ZDF-CR). The weight of BAT tissue and fat deposits were significantly increased in ZDF-CR and ZDF-ND rats as compared to ZL controls, while UCP-1 and mitochondrial concentrations were significantly decreased. Whitening and severely impaired insulin-stimulated glucose uptake in BAT was confirmed in a rat model of type-2 diabetes. Additionally, calorie restriction partially restored the impaired BAT glucose uptake.}, language = {en} }