F-fluorodeoxyglucose Research Articles

Intracranial Involvement of Solitary Fibrous Tumor of the Thorax as Shown by Follow-up Ga-68 DOTATATE Imaging Findings

The solitary fibrous tumor is a mesenchymal soft tissue tumor and the usual first presentation site of this tumor is the pleura. There are case reports showing extrapleural involvement as well. The solitary fibrous tumors show significantly increased F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography/computed tomography (PET/CT) according to the previous case reports. A single previous case report with significant Ga-68 DOTATATE uptake has been also shown in the literature. However this is the only report of a patient with follow up Ga-68 DOTATATE PET/CT imaging findings of disseminated involvement of the disease including intracranial involvement as far as we know in the literature.

18F fluorodeoxyglucose positron-emission tomography–computed tomography in the diagnosis of brachial plexopathy in carcinoma breast

We report the case of a 42-year-old female who had received treatment for carcinoma left breast, now presenting with pain in the left upper limb for 2 months and paraesthesia for 1 month. Magnetic resonance imaging of the brachial plexus revealed altered signal intensity involving divisions and cords of the brachial plexus on the left side. 18F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography revealed moderately increased FDG concentration in multiple ill-defined nodules, along the left brachial plexus suggestive of metastatic brachial plexopathy.

18F-FDG PET/CT and 99mTc-TRODAT Scan Findings in the Variants of Progressive Supranuclear Palsy and Correlation With Clinical Findings.

The aim of this study is to elucidate the patterns of characteristic hypometabolism on 18F-Fluoro Deoxy-glucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) in the variants of Progressive supranuclear palsy (PSP) and its correlation with their core clinical features. A retrospective analysis of 88 subjects with clinically suspected PSP was done. An institutional informed consent to participate in the study was taken from all the subjects. All the subjects had undergone a prior 99mTechnetium labeled Tropane derivative of dopamine transporter Single Photon Emission Computed Tomography (99mTc TRODAT-1 SPECT) study and had abnormal scans to confirm degenerative parkinsonism. The subjects were clinically examined by the neurologists using the Progressive Supranuclear Palsy Rating Scale proposed by the Movement Disorder Society and were further clinically segregated into eight subtypes. All the included subjects further underwent a detailed clinical analysis to obtain their individual Schwab and England activities of daily living scale and Modified Hoehn and Yahr staging by a neurologist. All the subjects underwent 18F-FDG PET/CT scan after adequate preparation. The scans were analyzed both qualitatively (visually) and quantitatively using Statistical Parametric Mapping. The frontal, limbic, and sensorimotor cortices represented the common areas of hypometabolism among all the subtypes of PSP. The subcortical regions showing the most significant hypometabolism were the thalami, mid-brain, nucleus accumbens, caudate, globus pallidus, and putamen in descending order. Multiple cortical and subcortical regions of hypometabolism were identified in different subtypes of PSP. The characteristic patterns of hypometabolism observed in the different subgroups were more apparent on quantification and based on visual analysis alone, it may not be possible to differentiate the different subtypes of PSP. A good correlation was seen between some of the core clinical features and hypometabolic clusters.

Lewy Body Dementia Associated with Anti-IgLON 5 Encephalitis Detected on 18F Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography and 99mTc-TRODAT Single-Photon Emission Computed Tomography/Computed Tomography.

We present a case of Anti-IgLON 5 encephalitis with Lewy body dementia. 18F fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scan and 99 mTc-TRODAT-1 SPECT/CT scan were done. 99 mTc-TRODAT-1 scan findings revealed severely reduced concentration of dopamine transporter in bilateral basal ganglia, suggestive of a degenerative parkinsonian disorder. 18F-FDG PET scan findings were suggestive of moderate-to-severe hypometabolism in the bilateral parieto-temporal and bilateral occipital cortices including the primary visual cortices, supporting Lewy body spectrum disease with associated hypermetabolism in the bilateral sensorimotor cortices, bilateral basal ganglia, thalami, brain stem, and bilateral cerebellar hemispheres suggestive of inflammatory pathology.

Common Skeletal Neoplasms and Nonneoplastic Lesions at 18F-FDG PET/CT.

Numerous primary and metastatic osseous lesions and incidental osseous findings are encountered at fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT. These lesions show varying degrees of FDG uptake. Malignancies are generally more FDG avid than are benign lesions, but many exceptions exist. Although aggressive lesions tend to be more FDG avid than nonaggressive lesions, this concept holds true particularly for lesions of the same histologic subtype. In addition, some benign osseous processes such as Paget disease have variable degrees of FDG avidity on the basis of disease metabolic activity. This creates a diagnostic dilemma for radiologists and clinicians, especially in patients with known malignancies, and can result in unnecessary diagnostic imaging or interventions for incidental osseous lesions. Evaluation of morphologic CT characteristics of osseous lesions at FDG PET/CT can be a valuable adjunct to metabolic analysis to further characterize lesions, enhance diagnostic and staging accuracy, and avoid unnecessary invasive biopsy procedures. The authors review the common primary and metastatic bone lesions at FDG PET/CT, with an emphasis on morphologic CT assessment of lesions to help narrow the differential diagnosis. Imaging manifestations of common incidental nonneoplastic bone lesions at FDG PET/CT are discussed to provide information on differentiation of these lesions from osseous neoplasms. The guidelines of the National Comprehensive Cancer Network (NCCN) for common primary osseous malignancies are also summarized. Online supplemental material is available for this article. ©RSNA, 2021.

Factors associated with lymph node metastasis upstage after resection for patients with micropapillary lung adenocarcinoma.

BackgroundMicropapillary adenocarcinoma has a poor prognostic histological pattern. Additionally, preoperative detection of lymph node metastases by preoperative examination is difficult in some patients with micropapillary adenocarcinoma, and postoperative upstage may occur. However, clinicopathological features of patients with micropapillary adenocarcinoma with nodal upstage have not been established, therefore this study aimed to identify the factors associated with potential lymph node metastases during preoperative examination to ensure effective surgical procedures.MethodsBetween January 2011 and December 2020, 1029 patients received complete resection for primary non‐small‐cell lung cancer by lobectomy or more extensive resection with systematic lymph node dissection at this institution. One hundred and thirty‐one patients diagnosed with adenocarcinoma with micropapillary component were included in this study. The clinicopathological features of patients with nodal upstage whose postoperative N stage was more advanced than the preoperative N stage were examined.ResultsForty patients had nodal upstage after resection. 18F‐fluorodeoxyglucose (FDG) positron emission tomography‐computed tomography (PET‐CT) revealed that a maximum standardized uptake value (SUVmax) ≥5 for the primary lesion was significantly associated with postoperative nodal upstage. There were no significant differences in terms of sex, age, smoking history, surgical procedure, and diabetes. Among 38 patients with nodal upstage, 23 patients had no significant preoperative lymphadenopathy and showed no abnormal FDG uptake in the lymph nodes on 18F‐FDG‐PET‐CT, respectively.ConclusionsLymph node metastases were suspected in patients preoperatively diagnosed with micropapillary adenocarcinoma with FDG SUVmax ≥5 for the primary tumor. Therefore, standard surgical resection and careful lymph node dissection should be performed for such patients.

Multimodal brain imaging demonstrates that both amyloid burden and glucose metabolism predict the severity of cognitive impairment in patients with Alzheimer’s disease

AbstractBackgroundThe purpose of this study is to assess brain glucose metabolism and Amyloid‐β burden in patients with Alzheimer’s disease with 3 Tesla PET/MR imaging and to seek possible relation of imaging findings with the extent of cognitive impairment.Method45 consecutive subjects with memory complaints were evaluated with a detailed neuropsychological test battery and F18‐Fluorodeoxyglucose(FDG)‐PET/MRI and F18‐Flutemetamol‐PET/MRI scans. The imaging modalities were performed with a hybrid 3T PET / MR camera at a maximum of 7 days intervals. Images were visually evaluated by two nuclear medicine experts. The centiloid scores were calculated through amyloid standardized uptake value ratios (SUVR) for all participants and regional glucose metabolism characteristics were analyzed.ResultThe study population consisted of 30 males and 15 females with a mean age of 65.9±8.2 years. Mean MMSE was 21.7±7.2 for the overall group. Five patients had imaging features suggestive of non‐AD type of dementias and were excluded from further analyses. Visual examination of F18‐Flutemetamol PET/MRI was consistent with the Alzheimer’s disease continuum in 29 cases, 9 of them demonstrated normal glucose metabolism, whereas 20 remaining cases showed F18‐FDG‐PET/MRI patterns characteristic to Alzheimer’s disease (hypometabolism in parieto‐temporal cortices and/or posterior cingulate cortex). In bivariate analysis, MMSE was positively correlated with the glucose metabolism in temporal lobe and posterior cingulate gyrus (r= 0.382, p=0.020; r=0.330, p=0.046; respectively), additionally, a significant negative correlation was observed between MMSE and amyloid burden designated by the centiloid score (r=‐0.461, p=0.004). Memory performance tested by Enhanced Cued Recall (ECR) was also positively associated with the glucose metabolism in posterior cingulate gyrus (r= 0.446, p=0.006), and negatively associated with the centiloid value (r= ‐0.458, p=0.005). The relationship between the ECR test and the centiloid value persisted when adjusted for age, gender, and year of education (β=‐0.121, p=0.021) in multivariate models.ConclusionGeneral cognitive ability and memory were predicted by imaging markers of regional glucose metabolism and amyloid deposition in this study population with early‐stage Alzheimer’s disease. Further research should investigate the predictive value of those imaging markers for the rate of cognitive decline. Acknowledgment: We acknowledge the support of GE Health Care for the [F18]flutemetamol doses.

Usefulness of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography combined with the platelet-lymphocyte ratio in predicting the prognosis of nasopharyngeal carcinoma.

To investigate the value of 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET)/computed tomography (CT) combined with the platelet-lymphocyte ratio (PLR) in predicting the prognosis of nasopharyngeal carcinoma (NPC). This was a retrospective analysis of the data of 73 patients with NPC who underwent 18F-FDG PET/CT before treatment from January 2010 to December 2014. The maximum standard uptake value (SUVmax) of NPC and the PLR within 1 week before treatment were both measured. The Mann-Whitney U-test was used to compare the differences between the SUVmax and PLR among the different clinical characteristics of patients with NPC and the 5-year progression-free survival (PFS) rate; according to the receiver operating characteristic (ROC) curve, the best cutoff values of the SUVmax and PLR were obtained and used to group patients. The Kaplan-Meier method and Log-rank test were used to conduct univariate analysis of 5-year PFS in patients with NPC, and Cox regression was used to conduct multivariate analysis; differences in the 5-year PFS of patients with different SUVmax values combined with the PLR were compared. The SUVmax and PLR of patients with disease progression within 5 years were higher than those of patients without disease progression (p = 0.006 and p = 0.026). SUVmax = 9.7 and PLR = 132.98 had the best prognostic diagnostic efficiency for patients. Cox multivariate analysis showed that the SUVmax and PLR are independent factors affecting the prognosis of NPC. The 5-year PFS of patients with SUVmax <9.7 was significantly higher than that of patients with SUVmax ≥9.7 in the high PLR group (PLR ≥132.98) and in the low PLR group (PLR <132.98) (59.3% vs 29.4%, p = 0.033 and 90.9% vs 42.9%, p = 0.006, respectively). For patients with SUVmax <9.7, the 5-year PFS of the high PLR group was significantly lower than the low PLR group (59.3% vs 90.9%, p = 0.016); for patients with SUVmax ≥9.7, there was no significant difference in 5-year PFS between the high PLR group and the low PLR group (29.4% vs 42.9%, p = 0.406). Both the SUVmax of the primary tumor and the PLR before treatment have an important influence on the prognosis of NPC. Combining the SUVmax and the PLR can more accurately predict the prognosis of patients with NPC. In this study, we evaluated the prognostic value of combining pretreatment tumor 18F-FDG uptake on PET/CT imaging and PLR in NPC patients. We found that both SUVmax and PLR are independent factors for the PFS of NPC patients, and a low SUVmax (SUVmax <9.7) combined with a low PLR (PLR <132.98) revealed significant PFS benefit.

Abstract 9057: Anti-inflammatory Effect of Biologic Therapy in Patients With Psoriatic Disease: A Prospective Cohort Fdg-pet Study

Introduction: Psoriatic arthritis (PsA) and cutaneous psoriasis (PsO) are linked with an increased risk of adverse cardiovascular events. Hypothesis: Central vascular inflammation (VI) as measured on F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the ascending aorta will improve in patients following therapy with biologic agents compared to PsO patients receiving non-biologic therapy and controls. We also postulate that in patients responding to biologics, there will be an improvement in coronary microvascular dysfunction as measured by myocardial blood flow reserve (MFR) determined by rubidium-82 (82Rb) PET. Methods: We studied 3 patient cohorts (patients with PsA and/or PsO started on biologic agents, patients with PsO managed on non-biologic therapy, and patients with non-inflammatory arthritis). The primary outcome of our study was the change in VI, estimated as the target-to-background ratio by FDG PET in the most diseased segment of the ascending aorta at baseline compared to 6-month follow-up (TBRmax). We also performed 82Rb PET studies at baseline and 6-month follow-up to determine any changes on left ventricular MFR. Results: 34 participants were enrolled in the study (11 PsA and/or PsO patients on biologic agents, 13 patients in PsO group managed on non-biologic therapy, and 10 in the non-inflammatory control group). A significant drop in the thoracic aorta uptake was observed in the biologic-treated group (change in TBRmax: -0.46±0.55) when compared to the the PsO group treated with non-biologic therapy (change in TBRmax: 0.23±0.67). The group with imaging evidence of a response to biologic agents (i.e. TBRmax drop greater than median value) maintained MFR (change in MFR of 0.05±0.19) when compared to the group with a response on TBRmax that was below the median, which had a drop in MFR (-2.9±0.8) (P=0.03). Conclusions: VI in the thoracic aorta decreased compared to psoriasis patients treated with non-systemic therapies and controls. Psoriasis patients treated with biologics who demonstrated a significant response on FDG PET imaging, maintained their MFR compared to non-responders. There is a positive impact of immune therapies on VI and microvascular disease in patients with chronic inflammation.

Tumor Glucose Metabolism and Its Heterogeneity on F-18 FDG PET/CT Provide Better Prognostication in Nonmetastatic Human Papillomavirus-Related Oropharyngeal Squamous Cell Carcinoma.

Simple SummaryHuman papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) emerged as a distinct disease with a favorable prognosis, and a separate staging system was introduced. However, a subset of patients harbor a poor prognosis. We aimed to evaluate the prognostic role of metabolic parameters on baseline F-18 FDG PET/CT in patients with HPV-related OPSCC. We retrospectively reviewed patients who were diagnosed with stage I, II, and III HPV-related OPSCC using the 8th TNM staging. Metabolic features on baseline F-18 FDG PET/CT, such as higher tumor glucose metabolism derived from tumor SUVmax to liver SUVmean ratio, and increased intratumoral heterogeneity inferred from coefficient of variation were associated with poorer progression-free survival and overall survival. Further study is warranted to address the possible implications of F-18 FDG PET/CT on treatment de-intensification in these patients.Background: We aimed to evaluate the prognostic role of metabolic parameters on baseline F-18 fluorodeoxyglucose (FDG) PET/CT in patients with human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC). Methods: We retrospectively reviewed patients who were diagnosed with nonmetastatic HPV-related OPSCC using the 8th TNM staging system from 2010 to 2015 and underwent baseline F-18 FDG PET/CT. Tumor SUVmax to liver SUVmean ratio (SUVmax-TLR), metabolic tumor volume (MTV), tumor total lesion glycolysis to liver SUVmean ratio (TLG-TLR), and coefficient of variation (CV) of the primary tumor were measured. Patients were primarily treated with surgery or radiotherapy. Endpoints were progression-free survival (PFS) and overall survival (OS). Results: Ninety consecutive patients (male, 72; female, 18) were enrolled. They were followed up for a median of 77.4 months (interquartile range, 48.4–106.4). Sixteen patients progressed, and 13 died. Multivariate analysis revealed that patients with advanced age, overall stage, and higher SUVmax-TLR or CV had poorer PFS and OS. Conclusion: Higher SUVmax-TLR and CV of the primary tumor on baseline F-18 FDG PET/CT were associated with poorer PFS and OS in patients with nonmetastatic HPV-related OPSCC. Further study is warranted to address the possible implications of F-18 FDG PET/CT on treatment de-intensification in these patients.

PET-Based Quantification of Baseline Metabolic Tumor Burden Improves Risk Stratification in High-Risk Hodgkin Lymphoma: A Children's Oncology Group Study

<h3>Purpose/Objective(s)</h3> COG AHOD0831 was a multi-center, prospective study that used a response-adapted approach for patients < 22-years-old with high-risk Hodgkin lymphoma. After 2 cycles of chemotherapy, response evaluation was performed by ¹⁸F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) scan. Rapid early responders (RERs) received less intensive therapy than slow early responders (SERs). In this study, both 1^st & 2^nd event-free survival (EFS) rates were below the pre-specified targets. We explored if measures of baseline tumor burden improve risk stratification. <h3>Materials/Methods</h3> Patients from AHOD0831 were identified who had baseline PET scans that were amenable to quantitative analyses. For each patient, metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum standardized uptake value (SUVmax), and peak SUV (SUVpeak) were obtained for mediastinal (m) and total body (t) disease. MTV was defined based on thresholds of SUV > 2.5 or > 40% SUVmax. TLG was defined as MTV * tumor SUVmean. EFS was assessed by Kaplan-Meier analyses. 2^nd EFS was defined as the time to a second event, reflecting rates of successful salvage after a 1^st relapse. Receiver operating characteristic analyses estimated the ability of PET parameters to predict EFS; optimized cutoff values were identified using a Youden index. <h3>Results</h3> Of 166 patients enrolled on AHOD0831, 94 (57%) had PET scans evaluable for quantitative analysis. For this subset: median age 15.5 years; 62% male; 67% white; 45% stage III, 55% stage IV; 86% bulk; 60% nodular sclerosis histology; 54% RER, 46% SER. These characteristics did not differ significantly from the complete AHOD0831 cohort. At a median follow-up of 49 months, 4-year EFS was 76% for the complete cohort (76% RERs, 75% SERs). Patients with high tMTVs and tTLGs, based on each threshold, were significantly more likely to be SERs (all <i>P</i> < 0.02). tTLG_2.5 was significantly associated with EFS, with an optimal cutoff value of 1841 to distinguish low- and high-risk groups (<i>P</i> = 0.04). tTLG_2.5 was significantly associated with EFS in RERs (<i>P</i> = 0.01) but not in SERs (<i>P</i> = 0.8). Patients were stratified by RER vs. SER and high vs. low tTLG_2.5. The best EFS was associated with RER & low tTLG_2.5, the worst EFS with RER & high tTLG_2.5, and intermediate EFS with SER regardless of tTLG_2.5 (4-year EFS: 92%, n = 25; 60%, n = 26; 79%, n = 14; 74%, n = 29, respectively). EFS was superior in patients with tTLG_2.5 ≤1841 & RER when compared to the rest of the cohort (94% vs. 71%, <i>P</i> = 0.02). For this favorable subgroup, 2^nd EFS was 100%. <h3>Conclusion</h3> RERs with a low baseline metabolic tumor burden experienced excellent EFS with less intensive therapy. Conversely, RERs with a high baseline tumor burden experienced poor EFS that was even worse than that of SERs. Thus, patients with a high metabolic tumor burden upfront may benefit from intensified therapy, even if they achieve a RER. PET-based measures of initial disease burden may contribute to risk-based treatment algorithms and improve outcomes in HL.

Clinical Significance of Peritumoral Adipose Tissue PET/CT Imaging Features for Predicting Axillary Lymph Node Metastasis in Patients with Breast Cancer.

We investigated whether textural parameters of peritumoral breast adipose tissue (AT) based on F-18 fluorodeoxyglucose (FDG) PET/CT could predict axillary lymph node metastasis in patients with breast cancer. A total of 326 breast cancer patients with preoperative FDG PET/CT were retrospectively enrolled. PET/CT images were visually assessed and the maximum FDG uptake of axillary lymph nodes (LN SUVmax) was measured. From peritumoral breast AT, 38 textural features of PET imaging were extracted. The diagnostic ability of PET based on visual analysis, LN SUVmax, and textural features of peritumoral breast AT for predicting axillary lymph node metastasis were assessed using the area under the receiver operating characteristic curve (AUC) values. Among the 38 peritumoral breast AT textural features, grey-level co-occurrence matrix (GLCM) entropy showed the highest AUC value (0.830) for predicting axillary lymph node metastasis. The value of GLCM entropy was higher than that of visual analysis (0.739; p < 0.05) and the AUC value was comparable to that of LN SUVmax (0.793; p > 0.05). In the subgroup analysis of patients with negative findings on visual analysis, GLCM entropy still showed a high diagnostic ability (AUC: 0.759) in predicting lymph node metastasis. The findings suggest a potential diagnostic role of PET/CT imaging features of peritumoral breast AT in predicting axillary lymph node metastasis in patients with breast cancer.

Clinical and metabolic parameters for predicting disease progression of gallbladder adenocarcinoma.

ObjectiveThis study aimed to identify reliable predictors of disease progression in patients with gallbladder (GB) adenocarcinoma.Patients and methodsA total of 54 patients with GB adenocarcinoma underwent preoperative F-18 fluorodeoxyglucose (FDG) PET/CT. Age, sex, clinical stage, and pathologic differentiation were collected. Tumor size and PET parameters such as SUVmax, SUVmean, SUVpeak, metabolic tumor volume (MTV), and total lesion glycolysis were measured. Univariate and multivariate logistic regression analyses were performed to determine the utility of clinical values and PET parameters. Pearson bivariate correlation was used to evaluate the association between progression-free survival (PFS) and various parameters.ResultsNo recurrence was found in 15 of 54 patients, while six showed recurrence and another 33 manifested disease progression. There were significant differences in size, stage, pathologic differentiation, and PET parameters between the groups with and without recurrence/progression. However, there was no difference in those parameters between the groups with recurrence and progression. The average PFS of the groups with no recurrence, recurrence, and progression groups was 33.1, 17.1, and 5.0 months, respectively. In univariate analysis, age, sex, clinical stage, pathologic differentiation, size, and PET parameters were correlated with PFS. In multivariate analysis, only clinical stage and MTV were statistically significant and MTV showed the highest odds ratio. Pearson correlation coefficients showed moderate negative correlations between PFS and clinical stage or MTV.ConclusionIn GB adenocarcinoma, clinical stage and MTV are the most powerful parameters for predicting recurrence and disease progression. Based on clinical stage, MTV will represent a strong prognostic predictor.

Simultaneous FAPI PET/MRI Targeting the Fibroblast-Activation Protein for Breast Cancer.

Background Integrated PET/MRI is a promising modality for breast assessment. The most frequently used tracer, fluorine 18 (18F) fluorodeoxyglucose (FDG), is applied for whole-body staging in advanced breast cancer but has limited accuracy in evaluating primary breast lesions. The fibroblast-activation protein (FAP) is abundantly expressed in invasive breast cancer. FAP-directed PET tracers have recently become available, but results in primary breast tumors remain lacking. Purpose To evaluate the use of FAP inhibitor (FAPI) breast PET/MRI in assessing breast lesions and of FAPI whole-body scanning for lymph node (LN) and distant staging using the ligand gallium 68 (68Ga)-FAPI-46. Materials and Methods In women with histologically confirmed invasive breast cancer, all primary 68Ga-FAPI-46 breast and whole-body PET/MRI and PET/CT examinations conducted at the authors' center between October 2019 and December 2020 were retrospectively analyzed. MRI lesion characteristics and standardized uptake values (SUVs) were quantified with dedicated software. Mann-Whitney U tests were used to compare tumor SUVs across different tumor types. The Pearson correlation coefficient was calculated between SUV and measures of MRI morphologic characteristics. Results Nineteen women (mean age, 49 years ± 9 [standard deviation]) were evaluated-18 to complement initial staging and one for restaging after therapy for distant metastases. Strong tracer accumulation was observed in all 18 untreated primary breast malignancies (mean maximum SUV [SUVmax] = 13.9 [range, 7.9-29.9]; median lesion diameter = 26 mm [range, 9-155 mm]), resulting in clear tumor delineation across different gradings, receptors, and histologic types. All preoperatively verified LN metastases in 13 women showed strong tracer accumulation (mean SUVmax= 12.2 [range, 3.3-22.4]; mean diameter = 21 mm [range, 14-35 mm]). Tracer uptake established or supported extra-axillary LN involvement in seven women and affected therapy decisions in three women. Conclusion This retrospective analysis indicates use of 68Ga fibroblast-activation protein inhibitor tracers for breast cancer diagnosis and staging. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Mankoff and Sellmyer in this issue.

Validation of Deep Learning-based Augmentation for Reduced 18F-FDG Dose for PET/MRI in Children and Young Adults with Lymphoma.

To investigate if a deep learning convolutional neural network (CNN) could enable low-dose fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/MRI for correct treatment response assessment of children and young adults with lymphoma. In this secondary analysis of prospectively collected data (ClinicalTrials.gov identifier: NCT01542879), 20 patients with lymphoma (mean age, 16.4 years ± 6.4 [standard deviation]) underwent 18F-FDG PET/MRI between July 2015 and August 2019 at baseline and after induction chemotherapy. Full-dose 18F-FDG PET data (3 MBq/kg) were simulated to lower 18F-FDG doses based on the percentage of coincidence events (representing simulated 75%, 50%, 25%, 12.5%, and 6.25% 18F-FDG dose [hereafter referred to as 75%Sim, 50%Sim, 25%Sim, 12.5%Sim, and 6.25%Sim, respectively]). A U.S. Food and Drug Administration-approved CNN was used to augment input simulated low-dose scans to full-dose scans. For each follow-up scan after induction chemotherapy, the standardized uptake value (SUV) response score was calculated as the maximum SUV (SUVmax) of the tumor normalized to the mean liver SUV; tumor response was classified as adequate or inadequate. Sensitivity and specificity in the detection of correct response status were computed using full-dose PET as the reference standard. With decreasing simulated radiotracer doses, tumor SUVmax increased. A dose below 75%Sim of the full dose led to erroneous upstaging of adequate responders to inadequate responders (43% [six of 14 patients] for 75%Sim; 93% [13 of 14 patients] for 50%Sim; and 100% [14 of 14 patients] below 50%Sim; P < .05 for all). CNN-enhanced low-dose PET/MRI scans at 75%Sim and 50%Sim enabled correct response assessments for all patients. Use of the CNN augmentation for assessing adequate and inadequate responses resulted in identical sensitivities (100%) and specificities (100%) between the assessment of 100% full-dose PET, augmented 75%Sim, and augmented 50%Sim images. CNN enhancement of PET/MRI scans may enable 50% 18F-FDG dose reduction with correct treatment response assessment of children and young adults with lymphoma.Keywords: Pediatrics, PET/MRI, Computer Applications Detection/Diagnosis, Lymphoma, Tumor Response, Whole-Body Imaging, Technology AssessmentClinical trial registration no: NCT01542879 Supplemental material is available for this article. © RSNA, 2021.

ANTI-INFLAMMATORY EFFECT OF BIOLOGIC THERAPY IN PATIENTS WITH PSORIATIC DISEASE COMPARED WITH TREATMENT WITH NON-BIOLOGIC DMARDS: A PROSPECTIVE COHORT FDG-PET STUDY

<h3>BACKGROUND</h3> Psoriatic arthritis (PsA) and cutaneous psoriasis (PsO) are linked with an increased risk of adverse cardiovascular events. We hypothesized that central vascular inflammation on F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the ascending aorta would improve in these patients following therapy with biologic agents compared to PsO patients receiving non-biologic therapy and non-inflammatory control patients. We also postulated that in patients responding to biologics, there would an improvement in coronary microvascular dysfunction as measured by myocardial blood flow reserve (MFR) determined by rubidium-82 (82Rb) PET. <h3>METHODS AND RESULTS</h3> We studied 3 patient cohorts (patients with PsA and/or PsO started on biologic agents, patients with PsO managed on non-biologic therapy, and control patients with non-inflammatory arthritis). The primary outcome of our study was the change in vascular inflammation, estimated as the target-to-background ratio (TBR) by FDG PET in the most diseased segment of the ascending aorta at baseline compared to 6-month follow-up (TBRmax). We also performed 82Rb PET studies at baseline and 6-month follow-up to determine any changes on left ventricular MFR. A total of 34 participants were enrolled in the study (11 PsA and/or PsO patients on biologic agents, 13 patients in PsO group managed on non-biologic therapy, and 10 in the non-inflammatory control group). The majority (64.7%) of participants were men and the median age was 62 years (IQR: 48, 69). A significant drop in the thoracic aorta uptake was observed in the biologic-treated group (thoracic aorta change in TBRmax: -0.46±0.55) when compared to the change in the thoracic aorta FDG uptake of the PsO group treated with non-biologic therapy (thoracic aorta change in TBRmax: 0.23±0.67). Furthermore, the group with imaging evidence of a response to biologic agents (i.e. TBRmax drop > median value of 7%) maintained MFR (3.40±1.23 MFR to 3.5±1.2 MFR over 6 months) when compared to the group with a below median response on TBRmax which had a drop in MFR (2.9±0.8 MFR to 2.2±0.6 over 6 months) (P=0.03). <h3>CONCLUSION</h3> In a cohort of psoriasis patients treated with biologics, the FDG uptake in the thoracic aorta decreased over the study period compared to psoriasis patients treated with non-systemic therapies as well as controls. Additionally, psoriasis patients treated with biologics who demonstrated a significant anti-inflammatory response on FDG PET imaging, maintained their MFR compared to non-responders. This study supports the notion that there is a positive impact of immune therapies on vascular inflammation and microvascular disease in patients with chronic inflammation.

Granulomatous Lung Nodule Mimicking as Metastasis on F18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in a Case of Adrenocortical Carcinoma.

A variety of fungal pulmonary infections can produce radiologic findings that mimic malignancy. Distinguishing these infectious lesions from malignancy remains challenging for physicians. We describe one such case where fungal lung nodule mimicked metastasis on fluorodeoxyglucose positron emission tomography/computed tomography scan.

Clinical Significance of 18F-fluorodeoxyglucose and Glucose Transporter 1 mRNA in Clear Cell Renal Cell Carcinoma.

18F-fluorodeoxyglucose (FDG) uptake measurement on positron emission tomography/computed tomography (PET/CT) is difficult in renal tumors because of the nearby renal parenchyma and urinary tract, which excrete FDG. We carefully examined the maximum standardized uptake value (SUVmax) on FDG-PET/CT and investigated the relationship between major glucose transporters in the kidney and clear cell renal cell carcinoma (ccRCC) progression. Forty-five patients with ccRCC underwent FDG-PET/CT for staging and nephrectomy. Glucose transporter mRNA expression was examined in the removed kidney. SUVmax was increased in high-stage and high-grade tumors. Glucose transporter 1 (GLUT1) mRNA expression was higher in tumor tissues, in contrast to other glucose transporters. SUVmax was not correlated with GLUT1 mRNA expression. Kaplan-Meier analysis showed reduced overall and recurrence-free survival in the high SUVmax group. Primary ccRCC lesions show a high SUVmax and GLUT1 mRNA over-expression. SUVmax increases with tumor upstaging and upgrading.

Testicular FDG Uptake on PET/CT in Patients with Lymphoma: Correlation with Age

The purpose of this observational study was to investigate whether the standard uptake value (SUV) measurement has practical utility in distinguishing secondary testicular involvement from physiologic uptake in patients with lymphoma. A Radiology Information System (RIS) search was conducted for all PET/CT studies performed from 2010-2016 on adult male patients with a diagnosis of lymphoma. Patients with clinical or pathologic diagnosis of testicular lymphoma were excluded to undergo a separate analysis. PET/CT images of 606 patients with 1087 scans, in which 2045 testes were included in the field of view, were reviewed and measurements were performed for standardized uptake values of both testicles (SUVmax) as well as of the liver (SUVmax and SUVmean). The mean SUVmax of the testicles was 3.75 ± 0.90 (range 1.16-8.38). The mean ratio of testis SUVmax / liver SUVmean (T/L) was 1.78 ± 0.43. Trends in SUVmax and age were significant for a negative correlation by a small magnitude of 0.066 per 10 years (P < 0.001). T/L had similar changes with significant low magnitude decrease with increasing age (0.059 per 10-year increase, P < 0.001). In our separate analysis of 3 patients with clinical or pathology proven testicular lymphoma, the average pathologic SUVmax was 13.47 (range 11.39-15.97). This study has the largest known sample size for quantifying physiologic uptake in the testes. SUV measurements to quantify F-18 Fluorodeoxyglucose (FDG) uptake on PET/CT likely have practical utility in discriminating between physiologic and pathologic uptake of FDG in cases of secondary testicular lymphoma.

Hypermetabolic Axillary Lymphadenopathy on FDG PET/CT Due to COVID-19 Vaccination

Aim: This study aimed to evaluate the incidence of hypermetabolic axillary lymph nodes due to COVID-19 vaccines and the factors affecting hypermetabolic axillary lymph nodes in F18-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in on cology patients. Patients and Methods: Among the patients who underwent FDG PET/CT in our institution between January 15, 2021, and June 15, 2021, those who received one or two doses of COVID-19 vaccine (CoronaVac or Biontech) were included in the study. Presence and number of ipsilateral hypermetabolic axillary lymph nodes, FDG uptake, and whether there was a difference between these data after the 1st and 2nd vaccination were investigated. Results: Unilateral hypermetabolic axillary lymph nodes was observed in 9.9% (18/182) of the patients [9.6% (9/94) after 1st dose, 10.2% (9/88) after 2nd dose] vaccinated with CoronaVac; It was detected in 37.5% (9/24) of the patients [35% (7/20) after 1st dose, 50% (2/4) after 2nd dose] who vaccinated with Biontech. A negative correlation was found between the presence of hypermetabolic axillary lymph nodes and age in patients who vaccinated with CoronaV ac. Conclusion: The frequency of hipermetabolik aksiller lenf nodu after CoronaVac was lower than that observed after mRNA vaccines, a small group of patients in our study, and lower than reported in the literature. However, the statistical difference could not be evaluated due to the insufficient number of patients in the Biontech group. A brief history of vaccination is recommended before FDG PET/CT to reduce false positives. The potential role of FDG PET/CT in comparing the efficacy of vaccines produced with dif ferent biotechnologies should be searched in studies with large r patient populations.