Search

Introduction: Multiplexed PET imaging revolutionized clinical decision-making by simultaneously capturing various radiotracer data in a single scan, enhancing diagnostic accuracy and patient comfort. Through a transformer-based deep learning, this study underscores the potential of advanced imaging techniques to streamline diagnosis and improve patient outcomes., Patients and Methods: The research cohort consisted of 120 patients spanning from cognitively unimpaired individuals to those with mild cognitive impairment, dementia, and other mental disorders. Patients underwent various imaging assessments, including 3D T1-weighted MRI, amyloid PET scans using either 18 F-florbetapir (FBP) or 18 F-flutemetamol (FMM), and 18 F-FDG PET. Summed images of FMM/FBP and FDG were used as proxy for simultaneous scanning of 2 different tracers. A SwinUNETR model, a convolution-free transformer architecture, was trained for image translation. The model was trained using mean square error loss function and 5-fold cross-validation. Visual evaluation involved assessing image similarity and amyloid status, comparing synthesized images with actual ones. Statistical analysis was conducted to determine the significance of differences., Results: Visual inspection of synthesized images revealed remarkable similarity to reference images across various clinical statuses. The mean centiloid bias for dementia, mild cognitive impairment, and healthy control subjects and for FBP tracers is 15.70 ± 29.78, 0.35 ± 33.68, and 6.52 ± 25.19, respectively, whereas for FMM, it is -6.85 ± 25.02, 4.23 ± 23.78, and 5.71 ± 21.72, respectively. Clinical evaluation by 2 readers further confirmed the model's efficiency, with 97 FBP/FMM and 63 FDG synthesized images (from 120 subjects) found similar to ground truth diagnoses (rank 3), whereas 3 FBP/FMM and 15 FDG synthesized images were considered nonsimilar (rank 1). Promising sensitivity, specificity, and accuracy were achieved in amyloid status assessment based on synthesized images, with an average sensitivity of 95 ± 2.5, specificity of 72.5 ± 12.5, and accuracy of 87.5 ± 2.5. Error distribution analyses provided valuable insights into error levels across brain regions, with most falling between -0.1 and +0.2 SUV ratio. Correlation analyses demonstrated strong associations between actual and synthesized images, particularly for FMM images (FBP: Y = 0.72X + 20.95, R2 = 0.54; FMM: Y = 0.65X + 22.77, R2 = 0.77)., Conclusions: This study demonstrated the potential of a novel convolution-free transformer architecture, SwinUNETR, for synthesizing realistic FDG and FBP/FMM images from summation scans mimicking simultaneous dual-tracer imaging., Competing Interests: Conflicts of interest and sources of funding: The authors have no relevant financial or nonfinancial interests to disclose, and the authors have no competing interests to declare that are relevant to the content of this article. V.G. received research support and speaker fees through her institution from GE Healthcare, Siemens Healthineers, Janssen, and Novo Nordisk. H.Z. received research support through his institution from GE Healthcare., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Purpose: Hybrid dynamic imaging allows not only the estimation of whole-body (WB) macroparametric maps but also the estimation of microparameters in the initial bed position targeting the blood pool region containing the pathology owing to the limited axial field of view of PET scanners. In this work, we assessed the capability of multipass WB F-FDG PET parametric imaging in terms of lesion detectability through qualitative and quantitative evaluation of simulation and clinical studies., Methods: Simulation studies were conducted by generating data incorporating 3 liver and 3 lung lesions produced by 3 noise levels and 20 noise realizations for each noise level to estimate bias and lesion detection features. The total scan time for the clinical studies of 8 patients addressed for lung and liver lesions staging, including dynamic and static WB imaging, lasted 80 minutes. An in-house-developed MATLAB code was utilized to derive the microparametric and macroparametric maps. We compared lesion detectability and different image-derived PET metrics including the SUVs, Patlak-derived influx rate constant (Ki) and distribution volume (V) and K1, k2, k3, blood volume (bv) microparameters, and Ki estimated using the generalized linear least square approach., Results: In total, 104 lesions were detected, among which 47 were located in the targeted blood pool bed position where all quantitative parameters were calculated, thus enabling comparative analysis across all parameters. The evaluation encompassed visual interpretation performed by an expert nuclear medicine specialist and quantitative analysis. High correlation coefficients were observed between SUVmax and Kimax derived from the generalized linear least square approach, as well as Ki generated by Patlak graphical analysis. Moreover, 3 contrast-enhanced CT-proven malignant lesions located in the liver and a biopsy-proven malignant liver lesion not visible on static SUV images and Patlak maps were clearly pinpointed on K1 and k2 maps., Conclusions: Our results demonstrate that full compartmental modeling for the region containing the pathology has the potential of providing complementary information and, in some cases, more accurate diagnosis than conventional static SUV imaging, favorably comparing to Patlak graphical analysis.

Purpose: Dopamine transporter SPECT imaging is a valuable tool to estimate the integrity of presynaptic dopaminergic pathways in degenerative parkinsonisms. Evidence about SPECT differential pattern between parkinsonian and cerebellar forms of multiple system atrophy (MSA-P and MSA-C) is lacking. We aimed at assessing whether MSA-P and MSA-C variants have a distinct semiquantitative I-FP-CIT SPECT pattern., Methods: We studied a unicentric 13-year (2003-2016) retrospective cohort of subjects with possible or probable MSA and scanned with the same acquisition and reconstruction SPECT protocol. Age-dependent semiquantitative reference limits for striatal volumes of interest, asymmetry indices, and caudate/putamen ratio were previously established with a percentile approach on a cohort of subjects with nondegenerative conditions and normal visual scan., Results: Thirty-four subjects with clinical MSA (28 MSA-P and 6 MSA-C) were identified (mean age, 68.2 ± 10.1 years; male/female ratio 1.00; disease duration, 2.5 ± 2.2 years; Movement Disorders Society Unified Parkinson's Disease Rating Scale III score, 33.8 ± 12.4). The MSA-P subjects exhibited lower uptake values for all volumes of interest, for example, striatal uptake on the more affected side (1.10 ± 0.51) compared with MSA-C (2.30 ± 0.41, P = 0.0005), as well as significantly higher asymmetry indices % (24.7 ± 24.8 vs 6.3 ± 4.5, P = 0.028) and caudate/putamen ratio (2.26 ± 1.23 vs 1.13 ± 0.17, P = 0.00148)., Conclusions: The MSA-P and MSA-C subjects exhibited significantly distinct semiquantitative SPECT pattern with severe uptake impairment and high asymmetry for MSA-P and borderline uptake values for MSA-C. Clinical distinction of these 2 phenotypical entities is necessary in order to evaluate SPECT potential to discriminate between degenerative parkinsonisms.

Purpose: The aims of this study were to assess the intraindividual performance of F-fluorocholine (FCH) and C-acetate (ACE) PET studies for restaging of recurrent prostate cancer (PCa), to correlate PET findings with long-term clinical and imaging follow-up, and to evaluate the impact of PET results on patient management., Methods: Thirty-three PCa patients relapsing after radical prostatectomy (n = 10, prostate-specific antigen [PSA] ≤3 ng/mL), primary radiotherapy (n = 8, prostate-specific antigen ≤5 ng/mL), or radical prostatectomy + salvage radiotherapy (n = 15) underwent ACE and FCH PET-CT (n = 29) or PET-MRI (n = 4) studies in a randomized sequence 0 to 21 days apart., Results: The detection rate for ACE was 66% and for FCH was 60%. Results were concordant in 79% of the cases (26/33) and discordant in 21% (retroperitoneal, n = 5; pararectal, n = 1; and external iliac nodes, n = 1). After a median FU of 41 months (n = 32, 1 patient lost to FU), the site of relapse was correctly identified by ACE and FCH in 53% (17/32) and 47% (15/32) of the patients, respectively (2 M1a patients ACE+/FCH-), whereas in 6 of 32 patients the relapse was not localized. Treatment approach was changed in 11 (34.4%) of 32 patients and 9 (28%) of 32 patients restaged with ACE and FCH PET, respectively., Conclusions: In early recurrent PCa, ACE and FCH showed minor discrepancies, limited to nodal staging and mainly in the retroperitoneal area, with true positivity of PET findings confirmed in half of the cases during FU. Treatment approach turned out to be influenced by ACE or FCH PET studies in one third of the patients.

Purpose of the Report: To assess the validity of a semi-quantitative I-FP-CIT SPECT method, compared to the commonly used visual analysis, in patients with probable dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). We also studied DLB specific uptake impairment pattern and correlation of uptake in the presence or absence of parkinsonism., Materials and Methods: Among 1202 scans performed at our center from 2003 to 2015, we identified 93 subjects with probable DLB (mean age 76.9 ± 6.8 years, 37% women) and 18 with AD (mean age 76.9 ± 8.1 years, 50% women). Independent visual and semi-quantitative assessments based on previously established on-site reference values (including volumes-of-interest uptake, caudate-to-putamen ratio and striatal asymmetry index) were performed and compared between both groups., Results: Visual staging was considered abnormal in 96.8% of DLB patients, whereas 97.8% of subjects had an abnormal semi-quantitative assessment. Combining both methods yielded a 100% sensitivity. Patients with DLB exhibited a more pronounced impairment of putaminal uptake when associated with parkinsonism, whereas a more diffuse pattern and significantly higher uptake values were observed in the subgroup of DLB patients without parkinsonism (resp. striatal uptake 1.61 ± 0.66 vs. 2.28 ± 0.52, P = 0.01). A minority of AD subjects show minimal alterations of presynaptic dopaminergic transport (striatal uptake 3.07 ± 0.41), values being always significantly higher than those from DLB patients, irrespective of the presence of parkinsonism (P < 0.0001) or not (P = 0.002)., Conclusions: Additional use of semi-quantitative analysis allows a higher discrimination of DLB from AD and demonstrates a specific pattern of degeneration in DLB patients according to their motor phenotype.

A 46-year-old female patient with a mediastinal neuroendocrine carcinoma complicated by superior vena cava syndrome was referred for a bone metastatic workup. Bone scan with SPECT/CT showed several vertebral fixations without alterations on the unenhanced CT, but a CT scan with injection of contrast media showed vertebral densities matched to the lesions described on the SPECT/CT. This pattern confirmed presence of collateral paths through vertebral veins due to superior vena cava syndrome. Lack of metastases was confirmed by MRI.

Purpose: Neuroimaging is increasingly used to support the clinical diagnosis of patients with cognitive impairment. Dopamine transporter (DAT) imaging, such as DaTSCAN SPECT, tests the integrity of the nigrostriatal pathway, whereas FDG-PET identifies typical patterns of cortical and subcortical hypometabolism. The aim of this study was to assess the relative contribution of DAT and regional glucose metabolism imaging to the differential diagnosis., Patients and Methods: Twenty-seven subjects were investigated for neurodegenerative dementia associated with parkinsonism of variable severity by FDG-PET and DaTSCAN SPECT. They were grouped according to the clinically established diagnosis, including probable Alzheimer disease (5 subjects), corticobasal degeneration (6 subjects), Lewy body dementia (8 subjects), frontotemporal dementia (4 subjects), and Parkinson disease with dementia (4 subjects). Normalized FDG uptake and DAT uptake ratios were obtained by the BRASS software. We used a discriminant analysis with a stepwise method and a leave-one-out cross-validation., Results: With the use of regional values of normalized FDG uptake, 85.2% and 55.6% of the patients were correctly classified by the discriminant analysis and the cross-validation, respectively. When DAT alone was considered, the results were 59.3% and 51.9%, whereas the combination of both DAT and normalized FDG uptake yielded 100% and 88.9% of accurate classifications., Conclusions: This automated analysis approach shows that the information provided by normalized FDG uptake and DAT is not redundant for the differential diagnosis of dementia and that taking into account both normalized FDG uptake and DAT uptake allows a better classification of individual patients. These results further support the usefulness of both modalities in the clinical workup of dementia.

Purpose: We tested the performance and clinical applicability of combined protocols for brain imaging studies acquired on a new whole-body hybrid PET/MR scanner., Patients and Methods: Fifteen patients [6 male and 9 female patients; mean (SD) age, 51 (30) y; range, 6-89 y] were scanned on a Philips Ingenuity TF PET/MR. Standard imaging protocols of both modalities were combined, using a "head coil" and contrast-enhanced fully diagnostic MR protocols. Attenuation correction of the PET images was performed using tissue segmentation of the MR image and incorporation of attenuation templates measured for coils and table.The clinical indications evaluated are as follows: patients with cognitive disturbance of suspected neurodegenerative origin, presurgical evaluation of drug-refractory epilepsy, and brain tumor staging. For the first 2 indications, FDG PET imaging was performed, whereas for the last, fluoroethyltyrosine, an amino acid tracer, was used., Results: In all cases (4 patients with neurodegenerative disease, 6 patients with epilepsy, and 5 patients with high-grade tumor), we obtained full diagnostic quality of both modalities and the total duration of the examination remained within a tolerable range (<2 hours). Twelve subjects had pathological findings: 11 of which were confirmed by clinical follow-up as true positive and 1 was confirmed as a false-positive result. For the 3 normal studies, the clinical follow-up confirmed the imaging findings as true-negative., Conclusions: Acquiring both PET and MR in a single session on a hybrid system minimized patient discomfort while maximizing clinical information and optimizing registration of both modalities. In addition, in comparison to PET/CT, the effective dose (related to CT) was reduced, and this is particularly beneficial in the pediatric population.

The study of peripheral nerves (PN) is a challenge because of the orientation, size, and also because of the fact that these pathologies are not well known. The diagnosis of PN damage was based exclusively on clinical examination and electrophysiologic testing until few years ago. MRI is the examination of choice for studying peripheral nerves; recently, magnetic resonance neurography has been added as a part of clinical routine. However, the analysis of PN after surgical treatment remains difficult. This clinical case of a sarcoma of the right brachial plexus illustrates how hybrid PET-MRI in postsurgical evaluation will clearly improve the exact delimitation of residual metabolically active tumor after surgery.

Purpose: Effective management of patients affected by retroperitoneal fibrosis (RPF) is an important issue because of lack of relevant parameters to objectively assess the degree of inflammation. We evaluated added value of contrast-enhanced computed tomography (CE-CT) combined with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) as a one-stop diagnostic procedure for the assessment and follow-up of patients with RPF., Materials and Methods: (18)F-FDG PET and CE-CT findings were reviewed in 10 patients suffering from RPF. Maximum standard uptake values (on native and contrast-enhanced [ESUV(max)] CT) were calculated. Dimensions of periaortitis were measured on CT scans. Observed clinical changes between baseline PET scan (T0) and at 6 months follow-up (T6) were analyzed regarding differences of initial values for clinic and paraclinic parameters., Results: Patients still suffering from pain 6 months after baseline PET scan had initially higher FDG uptake (ESUV(max): 5.7 ± 0.9 vs. 2.4 ± 0.9, P < 0.01). Unlike biologic and CT parameters, FDG uptake was the most relevant parameter to measure severity of inflammation (ESUV(max) threshold: 4.3; Se = Sp = 1.0). CE-CT exclusively allowed better delineation and more accurate assessment of FDG uptake of periaortitis and its extension to adjacent structures., Conclusions: Our results clearly show the usefulness of PET/CT for better evaluation and management of patients with fibroblast proliferation disease. Accurate determination of inflammation level is significantly improved when PET/CT and CE-CT are performed in the same study and used for better delineation of areas of residual inflammation.