Standardized Uptake Value Research Articles

Effects of Early and Late Cranioplasty on Neurocognitive Outcome and Cerebral Glucose Metabolism using PET Scan - A Comparative Study.

Brain protection and cosmetic aspects are the major indications of cranioplasty (CP) after decompressive craniectomy. CP can avoid the recurrence of brain damage, achieve the plastic effect, protect the patient from seizures, and relieve the syndrome of trephine. This was a prospective, observational study done over a period of 2 years from April 2017 to April 2019 in the Department of Neurosurgery at Sri Venkateswara Institute of Medical Sciences (SVIMS), Tirupati. Patients of age group 20-60 years who underwent CP after decompressive craniectomy for traumatic brain injury or cerebrovascular accidents with refractory intracranial hypertension were included. The study population was divided into two groups: early and late CP groups. Neurocognitive assessment was done 72 h before and 3 months after CP by mini-mental state examination (MMSE), Glasgow outcome score (GOS), and PGI battery of brain dysfunction (PGIBBD) scores. Cerebral glucose metabolism was assessed by 18F-FDG PET scan. In both early and late CP groups, there was a highly significant difference between the mean pre- and postoperative values of MMSE, GOS, and PGIBBD, suggesting significant improvement in neurocognitive parameters of patients postoperatively. There was no significant difference between early and late CP groups for mean standard uptake values (SUVs) on PET scan for both affected (P-value- 0.40) and nonaffected (P-value- 0.30) sides. CP improves the cerebral metabolism and neurocognitive outcome, weather it is done early or late.

Prognostic significance of diffuse increased fluorine-18-fluorodeoxyglucose (18F-FDG) uptake within the reticuloendothelial system in lymphoma patients.

As constituents of the reticuloendothelial system, the spleen and bone marrow (BM) have been recognized as integral components of the systemic inflammatory response in cancer contexts, thereby serving as predictive indicators for assessing cancer prognosis. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has attained widespread utilization for staging, assessing treatment response, and prognostication in lymphoma patients. Several investigations have proposed that focal increased 18F-FDG uptake in the BM or spleen may correlate with malignant involvement in lymphoma. However, scant data exist regarding the implications of diffuse BM and splenic uptake. This study aimed to explore the relationships between metabolic parameters of the spleen and BM on 18F-FDG PET/CT and inflammatory markers, and to assess their prognostic value in patients with lymphoma. A retrospective analysis was conducted on 118 patients newly diagnosed with malignant lymphoma, who underwent 18F-FDG PET/CT and exhibited diffuse increased splenic or BM uptake in 18F-FDG PET/CT imaging. The mean standardized uptake value (SUV) of the spleen, BM, and liver was calculated. The association between metabolic variables and systemic inflammatory markers was investigated, and the prognostic significance of clinicopathological and PET parameters was assessed using overall survival (OS) and progression-free survival (PFS). A statistically significant correlation was found between the spleen-to-liver SUV ratio (SLR) and inflammatory markers such as C-reactive protein (r=0.264, P=0.007) and platelet-to-lymphocyte ratio (r=0.227, P=0.021). No significant correlation was observed between BM-to-liver SUV ratio (BLR) and hematologic parameters, while concordance analysis revealed a fair agreement between BLR and bone marrow biopsy (BMB) (Cohen's Kappa-κ =0.271, P=0.002). In patients with aggressive non-Hodgkin lymphoma, both SLR [P=0.017, HR 2.715, 95% confidence interval (CI): 0.875-8.428] and BLR (P=0.044, HR 0.795, 95% CI: 0.348-1.813) were significantly linked to OS, while SLR (P=0.019, HR 2.223, 95% CI: 1.139-4.342) emerged as a significant prognostic factor for PFS. This study highlighted that diffuse increased splenic 18F-FDG uptake in lymphoma patients was closely associated with inflammation, whereas diffuse BM uptake was likely attributable to BM infiltration rather than inflammatory changes. Furthermore, both parameters held promise as prognostic indicators for patients with aggressive lymphoma.

Association of hemoglobin with plasma neurofilament light and white matter hyperintensities in Alzheimer's disease continuum

ObjectiveThis study aimed to investigate the association of hemoglobin (Hb) with axonal injury marker plasma neurofilament light (PNFL) and brain structure measurements in the Alzheimer's disease (AD) continuum. MethodsThe data used in this study were collected from the Alzheimer's Disease Neuroimaging Initiative database. Participants with cognitively normal, mild cognitive impairment, and mild dementia were included in the data analyses. All participants had available data on blood tests, PNFL levels, neuropsychological assessments, brain structure measurements (including volumes of white matter hyperintensities [WMH], hippocampus, gray matter, and total brain), and Aβ positron emission tomography standardized uptake value ratio (SUVR) at baseline. Aβ-positive was defined as SUVR threshold value > 1.11. Linear regression, restricted cubic spline, and causal mediation analyses were conducted to investigate the association of Hb concentration with PNFL levels and brain structure measurements. Stratified analyses were also employed to evaluate the association between Hb concentration and PNFL levels across different APOE genotypes and sex. ResultsIn the Aβ-positive group, Hb concentration was associated with PNFL levels (β = −0.022, p = 0.002). Stratified analyses suggested an association between Hb concentration and PNFL in APOE ɛ4 carriers (β = −0.031, p < 0.001) and males (β = −0.030, p < 0.001) but not in non-carriers and females (p > 0.05). Hb concentration was also associated with WMH volume (β = −0.04, p = 0.028), especially in APOE ɛ4 carriers, with mediation analysis revealing that PNFL mediated the association between Hb concentration and WMH volume. The association of Hb concentration with other brain structure measurements was minimal. ConclusionIn the AD continuum, Hb was associated with axonal injury marker PNFL and WMH volume, particularly in APOE ɛ4 carriers.

Abstract P374: Systolic blood pressure burden better predicts tau accumulation than a one-time measurement

In our past work, our group identified a significant relationship between uncontrolled hypertension and greater accumulations of total-tau and phospho-tau181 in cerebrospinal fluid over time. Here, we tested whether blood pressure is related to brain tau deposition assessed using MK-6240 PET. Blood pressure is dynamic in nature, making it difficult to draw conclusions about their risk from a single measurement. To address this issue, different measurement methods have surfaced to better utilize blood pressure as a predictor of disease pathology. Previous studies have found cumulative diastolic blood pressure to increase cardiovascular disease stratification beyond that of a single diastolic blood pressure measurement. In this project, we studied another method of quantifying blood pressure. We examined whether systolic blood pressure (SBP) burden was better related to tau accumulation than a one-time BP measurement taken at the time of PET scan. SBP load was defined as the percentage of SBP values &gt;=140 mmHg taken in the period spanning from 6 months before tau imaging to 6 months after. SUVR (standardized uptake value ratio) was created using the cerebellar gray matter as the reference region. We assessed SUVR in Braak regions 1-6. Pearson correlation was used to test the associations between the variables of interest. We studied cognitively healthy subjects from a brain aging research center (n=72, 40% women, 60% with hypertension). Medians of our group were 72 years of age (interquartile range (IQR) 10.6), education of 18 years (IQR 2), and 8 BP measurements (IQR 14). While one-time SBP measurements and tau were not related, SBP load was progressively correlated with SUVR across Braak stages. In the entire group, the correlations ranged from -0.18 (p = 0.133) in Braak region 1 to 0.19 (p = 0.114) in Braak region 3 to 0.24 (p = 0.042) in Braak region 6. In the hypertensive group, these correlations were stronger and ranged from -0.06 (p = 0.713) in Braak region 1 to 0.38 (p = 0.012) in Braak region 3 to 0.50 (p &lt; 0.001) in Braak region 6. We show that SBP load instead of singular SBP measurements is a stronger predictor of tau accumulation. Furthermore, stronger associations with brain regions known to be affected in more advanced stages suggest that blood pressure control is more critical to tau progression than initial deposition.

Delineating structural and metabolic abnormalities in amygdala and hippocampal subfields for different seizure-onset patterns via stereotactic electroencephalography.

We aimed to investigate mesial temporal lobe abnormalities in mesial temporal lobe epilepsy (MTLE) patients with hypersynchronous (HYP) and low-voltage fast rhythms (LVF) onset identified by stereotactic electroencephalography (SEEG) and evaluate their diagnostic and prognostic value. Fifty-one MTLE patients were categorized as HYP or LVF by SEEG. High-resolution MRI volume-based analysis and 18F-FDG-PET standard uptake values of hippocampal and amygdala subfields were quantified and compared with 57 matched controls. Further analyses were conducted to delineate the distinct pathological characteristics differentiating the two groups. Diagnostic and prognostic prediction performance of these biomarkers were assessed using receiver operating characteristic curves. LVF-onset individuals demonstrated ipsilateral amygdala enlargement (p = 0.048) and contralateral hippocampus hypermetabolism (p = 0.042), pathological results often accompany abnormalities in the temporal lobe cortex, while HYP-onset subjects had significant atrophy (p < 0.001) and hypometabolism (p = 0.013) in ipsilateral hippocampus and its subfields, as well as amygdala atrophy (p < 0.001), pathological results are highly correlated with hippocampal sclerosis. Severe fimbria atrophy was observed in cases of HYP-onset MTLE with poor prognosis (AUC = 0.874). Individuals with different seizure-onset patterns display specific morphological and metabolic abnormalities in the amygdala and hippocampus. Identifying these subfield abnormalities can improve diagnostic and prognostic precision, guiding surgical strategies for MTLE.

Mediastinal lymph node dissection in segmentectomy for peripheral c-stage IA (≤2 cm) non–small-cell lung cancer

ObjectiveAlthough recent trials on intentional segmentectomy have made mediastinal lymph node dissection (MLND) mandatory, the necessity of MLND in segmentectomy remains uncertain. We conducted a retrospective study to evaluate the necessity of MLND in segmentectomy for patients with peripheral stage IA (≤2 cm) non–small cell lung cancer. MethodsOf the 5222 surgical cases for non–small cell lung cancer from 3 institutions between 2010 and 2021, 1457 patients met the JCOG0802 trial eligibility criteria. Initially, we analyzed 574 patients who underwent lobectomy with MLND to identify preoperative risk factors for cN0-pN2 occurrence (cohort 1). Subsequently, we evaluated the relationship between these factors and the cumulative postoperative recurrence in 390 patients who underwent segmentectomy (cohort 2). ResultsIn cohort 1, risk factors for cN0-pN2 occurrence were consolidation-to-tumor ratio = 1.0 and maximum standardized uptake value ≥2.0. When classifying patients into 3 groups (group A, without any factors, group B, with either factor, and group C, with both factors), the occurrence of cN0-pN2 was significantly greater in group C than in the other groups (0.9%, 3.4%, and 8.4%, respectively, P = .005). When classifying patients in cohort 2 using the classification identified in cohort 1 (117, 131, and 142 were categorized into group A, group B, and group C, respectively), the 5-year cumulative incidence of recurrence rate was significantly greater in group C than in others (2.0%, 2.0%, and 15.9%, respectively, P < .001). ConclusionsMLND is unlikely to be beneficial in intentional segmentectomy for patients with tumors showing consolidation-to-tumor ratio <1.0 and maximum standardized uptake value <2.0.

Quantification of macrophage activity in knee synovial tissue using [18F]FEPPA positron emission tomography

ObjectiveInflammation in knee osteoarthritis (OA) is mediated primarily by synovial tissue macrophages, but non-invasive measurement of macrophage activity in vivo is a challenge. Activated macrophages markedly increase expression of the translocator protein (TSPO). In the context of other diseases TSPO-PET using the [18F]FEPPA tracer (binding to TSPO) has been reported to be an effective method for imaging macrophages in vivo. The goal of this study was to validate the use of [18F]FEPPA PET radiotracer to accurately measure macrophage activation in knee synovial tissue. DesignTen participants with late-stage OA scheduled for knee replacement surgery were recruited. Prior to surgery, 5 of the participants underwent a clinical [18F]FEPPA PET/MRI scan and the standard uptake value (SUV) in the suprapatellar synovial region was calculated. Suprapatellar synovial tissue samples were collected from all participants at the time of surgery and were imaged ex vivo with [18F]FEPPA autoradiography. Tracer uptake was compared to TSPO antibody immunostaining in serial tissue sections. The correlation between the [18F]FEPPA uptake and gold standard TSPO fluorescent intensity was measured. RESULTSThe autoradiography [18F]FEPPA signal in the synovial lining was correlated with the TSPO signal in the. lining macrophages measured by immunohistochemistry (r = 0.81, p = 0.0040, CI [0.37, 0.95]). Similarly, PET/MRI scans demonstrated similar correlation between SUV in synovial tissues in vivo and in situ TSPO signal in lining macrophages {r = 0.90, p = 0.083, CI [0.086, 0.99]) Conclusion[18F]FEPPA uptake in knee synovial tissue is strongly correlated to the expression of TSPO in synovial lining macrophages, suggesting that clinical [18F]FEPPA PET/MRI may be a valid measure of true macrophage activity in synovial tissues in knee OA. [18F]FEPPA may be an effective tool to assess macrophage activation both ex vivo and in vivo, and should be investigated further to assess its performance and measurement properties in different clinical contexts of knee OA including disease states and responses to treatment.

PSMA PET improves characterization of dural-based intracranial lesions in patients with metastatic prostate cancer

PurposeTheranostic approaches combining prostate-specific membrane antigen (PSMA)-PET/CT or PET/MRI with PSMA-targeted radionuclide therapy have improved clinical outcomes in patients with prostate cancer (PCa) especially metastatic castrate resistant prostate cancer. Dural metastases in PCa are rare but can pose a diagnostic challenge, as meningiomas, a more common dural based lesions have been shown to express PSMA. The aim of this study is to compare PSMA PET parameters between brain lesions classified as dural metastases and meningiomas in prostate cancer patients. MethodsA retrospective analysis of PSMA PET/CT scans in patients with PCa and intracranial lesions was conducted. Brain lesions were categorized as dural metastases or meningiomas based on MRI characteristics, longitudinal follow-up, and histopathological characteristics. Standardized uptake values (SUVmax) of each brain lesion were measured, along with SUV ratio referencing parotid gland (SUVR). SUVs between lesions classified as metastases and meningiomas, respectively, were compared using Mann-Whitney-test. Diagnostic accuracy was evaluated using ROC analysis. Results26 male patients (median age: 76.5 years, range: 59–96 years) met inclusion criteria. A total of 44 lesions (7 meningiomas and 37 metastases) were analyzed. Median SUVmax and SUVR were significantly lower in meningiomas compared to metastases (SUVmax: 2.7 vs. 11.5, p = 0.001; SUVR: 0.26 vs. 1.05, p < 0.001). ROC analysis demonstrated AUC 0.903; the optimal cut-off value for SUVR was 0.81 with 81.1 % sensitivity and 100 % specificity. ConclusionPSMA PET has the potential to differentiate meningiomas from dural-based metastases in patients with PCa, which can optimize clinical management and thus improve patient outcomes.

Baseline SUVmax is correlated with tumor hypoxia and patient outcomes in nasopharyngeal carcinoma

To evaluate the prognostic significance of the maximum standardized uptake value (SUVmax) in nasopharyngeal carcinoma (NPC), establish a gene signature that correlates with SUVmax, and explore the underlying biological behaviors associated with these correlations for the prediction of clinical outcomes. A cohort of 726 patients with NPC was examined to identify correlations between SUVmax and various clinical variables. RNA sequencing was performed to identify genes related to SUVmax, and these genes were used to develop an SUV signature. Additionally, transcriptome enrichment analysis was conducted to investigate the potential biological behaviors underlying the observed correlations. Higher SUVmax was associated with an increased tumor burden and worse prognosis. The SUV signature, which consisted of 10 genes, was positively correlated with SUVmax, and it predicted worse survival outcomes. This signature was highly expressed in malignant epithelial cells and associated with hypoxia and resistance to radiotherapy. Additionally, the signature was negatively correlated with immune function. SUVmax is a valuable prognostic indicator in NPC, with higher values predicting worse outcomes. The SUV signature offers further prognostic insights, linking glucose metabolism to tumor aggressiveness, treatment resistance, and immune function, and it could represent a potential biomarker for NPC.

Evaluation of damage discrimination in dopaminergic neurons using dopamine transporter PET tracer [18F]FECNT-d4

BackgroundParkinson’s disease (PD) is a prevalent neurodegenerative disorder worldwide, diagnosed based on classic symptoms like motor dysfunction and cognitive impairments. With the development of various radioactive ligands, positron emission tomography (PET) imaging combined with specific radiolabelling probes has proven to be effective in aiding clinical PD diagnosis. Among these probes, 2β-Carbomethoxy-3β-(4-chlorophenyl)-8-(2-[18F]-fluoroethyl) nortropane ([18F]FECNT) has been utilized as a PET tracer to image dopamine transporter (DAT) integrity in striatal presynaptic dopaminergic terminals. However, the presence of brain-penetrant radioactive metabolites produced by [18F]FECNT may impact the accuracy of PET imaging. In previous research, we developed 2β-Carbomethoxy-3β-(4-chlorophenyl)-8-(2-[18F]-fluoroethyl-1,1,2,2-d4) nortropane ([18F]FECNT-d4), a deuterated derivative with enhanced stability in plasma and the striatum, along with a slower washout rate. In this study, we further investigated the potential of [18F]FECNT-d4 to detect dopaminergic neuron degeneration in Parkinson’s disease. This involved PET imaging in unilaterally-lesioned PD model rats and in vitro autoradiography conducted on postmortem brain sections.ResultsPET images revealed reduced specific uptake in the ipsilateral striatum of rats stereotactically injected with 6-hydroxydopamine hydrochloride (6-OHDA). Compared to the sham group, the ratio of standardized uptake value (SUV) in the ipsilateral to contralateral striatum decreased by 13%, 23%, and 63% in the mild, moderate, and severe lesioned groups, respectively. Dopaminergic denervation observed in PET imaging was further supported by behavioral assessments, immunostaining, and monoamine concentration tests. Moreover, the microPET results exhibited positive correlations with these measurements, except for the apomorphine-induced rotational behavior test, which showed a negative correlation. Additionally, [18F]FECNT-d4 uptake was approximately 40% lower in the postmortem striatal sections of a PD patient compared to a healthy subject. Furthermore, estimated human dosimetry (effective dose equivalent: 5.06 E-03 mSv/MBq), extrapolated from rat biodistribution data, remained below the current Food and Drug Administration limit for radiation exposure.ConclusionOur findings demonstrate that [18F]FECNT-d4 accurately estimates levels of dopaminergic neuron degeneration in the 6-OHDA-induced PD rat model and effectively distinguishes between PD patients and healthy individuals. This highly sensitive and safe PET probe holds promising potential for clinical application in the diagnosis and monitoring of Parkinson’s disease.

Timing offset calibration for TOF PET using stationary line source scans at multiple positions

Background. Accurate timing offset calibration is crucial for time-of-flight (TOF) positron emission tomography (PET) to mitigate image artifacts and improve quantitative accuracy. However, existing methods are often time-consuming, complex, or costly.Objective. This paper presents a method for TOF PET timing offset calibration that eliminates the need for costly equipment, phantoms, short-half-life sources, and precise source positioning.Approach. We estimate channel timing offsets using stationary scans of a68Ge line source, typically used for routine quality control, at a minimum of three non-coplanar positions, with each position scanned for two minutes. The line source positions are accurately determined by applying a simple algorithm to their reconstructed images, allowing precise calculation of arrival time differences. Channel timing offsets are estimated by solving a least squares problem. This method is assessed through analyses of phantoms and patient images using a RAYSOLUTION DigitMI 930 scanner.Main results. The estimated timing offsets ranged from -500 ps to 500 ps across all channels. Calibration with a minimum of three scanned positions was sufficient to correct these offsets, achieving less than a 1% discrepancy across various metrics of the image quality (IQ) phantom compared to 12 positions. This calibration significantly reduced edge artifacts in TOF reconstruction of both phantoms and patients. Furthermore, the IQ phantom displayed a 14% increase in average contrast recovery, a 61% reduction in average background variability across all spheres, and a 90% reduction in average residual error. Consistent with the phantom results, patient data revealed enhancements in maximum standardized uptake values (SUVmax) from 14% to 55% for lesions measuring 6 mm to 14 mm. The calibration also improved lesion-to-background contrast and eliminated artifacts caused by the spillover effect of the kidneys and bladder.Significance. The proposed method is fast, user-friendly, and cost-effective, effectively improving lesion detection and diagnostic accuracy.

Cancer in Patients With Incidental Asymmetric Oropharynx Positron Emission Tomography Uptake

Asymmetric oropharynx uptake on positron emission tomography (PET)/computed tomography (CT) is a common incidental finding and often prompts otolaryngology referral to rule out malignancy; however, the true risk of malignancy based on this finding is unknown. To identify the incidence of oropharynx cancer in patients with incidental asymmetric oropharynx PET uptake. In this retrospective cohort study, patients 18 years and older undergoing PET/CT scans at Mayo Clinic between January 2001 and December 2018 were included. Patients with a history or pretest suspicion of oropharynx cancer were excluded. Data were analyzed from March 2021 to December 2023. Blinded radiologic review of imaging studies, including measurement of maximum standardized uptake values (SUVmax) of the ipsilateral side of concern and contralateral side. Retrospective medical record review for associated clinical data. The primary study outcome was the incidence of oropharynx cancer diagnosis in patients with asymmetric oropharynx PET uptake. The primary outcome was formulated before data collection. Of the 1854 patients identified with asymmetric oropharynx PET uptake, 327 (17.6%) met inclusion criteria. Of these, 173 (52.9%) were male, and the median (range) age was 65.0 (24.8-90.7) years. The mean (SD) follow-up interval was 52.1 (43.4) months. A total of 18 of 327 patients (5.5%) were newly diagnosed with oropharynx cancer. The most common diagnosis was squamous cell carcinoma (n = 9), followed by lymphoma (n = 8), and sarcoma (n = 1). Patients with an incidental diagnosis of oropharynx cancer had higher mean (SD) ipsilateral SUVmax (8.7 [3.7] vs 5.3 [1.9]) and SUVmax ratio (3.0 [1.6] vs 1.6 [0.6]) compared with patients with normal examination findings. SUVmax ratio and difference were found to be good discriminators of oropharynx cancer, with areas under the receiver operating characteristic curve of 86.3% (95% CI, 76.4-94.6) and 85.8% (95% CI, 74.8-94.6), respectively. Patients with a new diagnosis of oropharynx cancer were more likely to have a corresponding CT abnormality than those with normal examination findings (6 of 18 [33%] vs 24 of 295 [8.1%]). Patients with concerning lesions on oropharynx palpation by an otolaryngology health care professional were significantly more likely to be diagnosed with oropharynx cancer compared with patients with normal examination findings (odds ratio, 28.4; 95% CI, 6.6-145.8). In this cohort study, while incidental asymmetric oropharynx PET uptake was common, a new diagnosis of oropharynx cancer was not and potentially results in a large volume of unnecessary referrals and work-up. Using SUVmax ratio, SUVmax difference, and CT correlation may increase the benefit of referral. Patients with a palpable oropharynx lesion and asymmetric oropharynx PET uptake should undergo confirmatory biopsy.

Evaluation of 68Ga-FAPI PET/CT and 18F-FDG PET/CT for the diagnosis of recurrent colorectal cancers

ObjectiveThe present study aimed to compare the diagnostic value of gallium-68-labeled fibroblast activation protein inhibitor positron emission tomography/computed tomography (68Ga-FAPI PET/CT) and fluorine-18-labeled fluorodeoxyglucose PET/CT (18F-FDG PET/CT) for detecting recurrent colorectal cancers (CRCs). Materials and MethodsFifty-six patients (age: 18–80 years, 31 men and 25 women) with suspected recurrent CRC were enrolled and underwent 18F-FDG PET/CT and 68Ga-FAPI PET/CT sequentially within 1 week. The maximum standard uptake value (SUVmax), tumor-to-background ratio (TBR), and diagnostic accuracy were estimated and compared between the two modalities by using Student’s t-test. The Wilcoxon signed-rank test was used to compare peritoneal carcinoma index (PCI) scores between the two imaging modalities. Results68Ga-FAPI PET/CT showed higher sensitivity for detecting recurrence (93 % vs. 79 %); lymph node metastasis (89 % vs. 78 %), particularly peritoneal lymph node metastasis (92 % vs. 63 %); and metastatic implantation on the intestinal wall (100 % vs. 25 %) compared to 18F-FDG PET/CT. However, 68Ga-FAPI PET/CT showed lower sensitivity for detecting bone metastasis (67 % vs. 100 %). The mean SUVmax values of peritoneal metastases and metastatic implantation on the intestinal wall were 4.28 ± 2.70 and 7.58 ± 1.66 for 18F-FDG PET/CT and 5.66 ± 1.97 and 6.70 ± 0.25 for 68Ga-FAPI PET/CT, respectively. Furthermore, 68Ga-FAPI PET/CT showed significantly higher TBR for peritoneal metastatic lesions (4.22 ± 1.47 vs. 1.41 ± 0.89, p < 0.0001) and metastatic implantation on the intestinal wall (5.63 ± 1.24 vs. 2.20 ± 0.5, p = 0.02) compared to 18F-FDG PET/CT. For the same patient, 68Ga-FAPI PET/CT yielded a more accurate PCI score and a greater area under the curve value for the receiver operating characteristic curve (p < 0.01) than 18F-FDG PET/CT. Conclusion68Ga-FAPI PET/CT was superior to 18F-FDG PET/CT for detecting recurrence and peritoneal metastases. Hence, we propose the combination of these two modalities for better clinical diagnosis and management of patients with CRC.

Detection of cancer-associated cachexia in lung cancer patients using whole-body [18F]FDG-PET/CT imaging: A multi-centre study.

Cancer-associated cachexia (CAC) is a metabolic syndrome contributing to therapy resistance and mortality in lung cancer patients (LCP). CAC is typically defined using clinical non-imaging criteria. Given the metabolic underpinnings of CAC and the ability of [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computer tomography (CT) to provide quantitative information on glucose turnover, we evaluate the usefulness of whole-body (WB) PET/CT imaging, as part of the standard diagnostic workup of LCP, to provide additional information on the onset or presence of CAC. This multi-centre study included 345 LCP who underwent WB [18F]FDG-PET/CT imaging for initial clinical staging. A weight loss grading system (WLGS) adjusted to body mass index was used to classify LCP into 'No CAC' (WLGS-0/1 at baseline prior treatment and at first follow-up: N=158, 51F/107M), 'Dev CAC' (WLGS-0/1 at baseline and WLGS-3/4 at follow-up: N=90, 34F/56M), and 'CAC' (WLGS-3/4 at baseline: N=97, 31F/66M). For each CAC category, mean standardized uptake values (SUV) normalized to aorta uptake (<SUVaorta>) and CT-defined volumes were extracted for abdominal and visceral organs, muscles, and adipose-tissue using automated image segmentation of baseline [18F]FDG-PET/CT images. Imaging and non-imaging parameters from laboratory tests were compared statistically. A machine-learning (ML) model was then trained to classify LCP as 'No CAC', 'Dev CAC', and 'CAC' based on their imaging parameters. SHapley Additive exPlanations (SHAP) analysis was employed to identify the key factors contributing to CAC development for each patient. The three CAC categories displayed multi-organ differences in <SUVaorta>. In all target organs, <SUVaorta> was higher in the 'CAC' cohort compared with 'No CAC' (P<0.01), except for liver and kidneys, where <SUVaorta> in 'CAC' was reduced by 5%. The 'Dev CAC' cohort displayed a small but significant increase in <SUVaorta> of pancreas (+4%), skeletal-muscle (+7%), subcutaneous adipose-tissue (+11%), and visceral adipose-tissue (+15%). In 'CAC' patients, a strong negative Spearman correlation (ρ=-0.8) was identified between <SUVaorta> and volumes of adipose-tissue. The machine-learning model identified 'CAC' at baseline with 81% of accuracy, highlighting <SUVaorta> of spleen, pancreas, liver, and adipose-tissue as most relevant features. The model performance was suboptimal (54%) when classifying 'Dev CAC' versus 'No CAC'. WB [18F]FDG-PET/CT imaging reveals groupwise differences in the multi-organ metabolism of LCP with and without CAC, thus highlighting systemic metabolic aberrations symptomatic of cachectic patients. Based on a retrospective cohort, our ML model identified patients with CAC with good accuracy. However, its performance in patients developing CAC was suboptimal. A prospective, multi-centre study has been initiated to address the limitations of the present retrospective analysis.

Imaging bone turnover assessment through volumetric density-adjusted standardized uptake value using quantitative bone SPECT/CT in osteoporosis

BackgroundSerum bone turnover markers offer limited insight into metabolic activity at the individual vertebra level in osteoporosis. This study introduces a novel image-derived bone turnover marker for individual vertebrae to address this limitation, utilizing volumetric density-adjusted quantitative bone single-photon emission computed tomography/computed tomography (SPECT/CT) with [99mTc]Tc-DPD. This retrospective study included 177 lumbar vertebrae from 55 postmenopausal South Korean women. The mean standardized uptake value (SUVmean, g/cm3) and volumetric bone mineral density (vBMD, mg/cm3) were determined within a 2-cm³ volume of interest in the trabecular portion of each vertebra using quantitative SPECT and CT. The density-adjusted mean standardized uptake value (dSUVmean) was calculated by dividing the SUVmean by the vBMD and multiplying by 1,000.ResultsSUVmean correlated positively with vBMD (r = 0.60, p < 0.001). Conversely, dSUVmean correlated negatively with vBMD (ρ = −0.66, p < 0.001), highlighting the inverse relationship between bone mass and turnover after density adjustment of SUVmean. Patients with major osteoporotic fractures had lower vBMD (62.5 ± 29.4 vs. 92.3 ± 27.4 mg/cm³, p = 0.001) but higher dSUVmean (100.8 ± 60.7 vs. 62.6 ± 17.5, p = 0.001) compared to those without fractures, reinforcing the association between fracture prevalence, low bone mass, and high bone turnover.ConclusionVolumetric density-adjusted quantitative bone SPECT/CT offers a novel image-derived bone turnover marker for assessing bone turnover in osteoporosis. This method provides a precise assessment of fragility at the individual vertebra level, which may enhance personalized osteoporosis management.

Poor sleep quality is associated with decreased regional brain glucose metabolism in healthy middle-aged adults

Sleep disturbance is associated with the development of neurodegenerative disease. We aimed to address the effects of sleep quality on brain glucose metabolism measured by 18F-Fl uorodeoxyglucose (18F-FDG) positron emission tomography (PET) in healthy middle-aged adults. A total of 378 healthy men (mean age: 42.8±3.6 years) were included in this study. Participants underwent brain 18F-FDG PET and completed the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K). Additionally, anthropometric measurements were obtained. PETs were spatially normalized to MNI space using PET templates from SPM5 with PMOD. The Automated Anatomical Labeling 2 atlas was used to define regions of interest (ROIs). The mean uptake of each ROI was scaled to the mean of the global cortical uptake of each individual and defined as the standardized uptake value ratio (SUVR). After the logarithmic transformation of the regional SUVR, the effects of the PSQI-K on the regional SUVR were investigated using Bayesian hierarchical modeling. Brain glucose metabolism of the posterior cingulate, precuneus, and thalamus showed a negative association with total PSQI-K scores in the Bayesian model ROI-based analysis. Voxel-based analysis using statistical parametric mapping revealed a negative association between the total PSQI-K scores and brain glucose metabolism of the precuneus, postcentral gyrus, posterior cingulate, and thalamus. Poor sleep quality is negatively associated with brain glucose metabolism in the precuneus, posterior cingulate, and thalamus. Therefore, the importance of sleep should not be overlooked, even in healthy middle-aged adults.

Preliminary clinical practice of radical prostatectomy without preoperative biopsy.

At present, biopsy is essential for the diagnosis of prostate cancer (PCa) before radical prostatectomy (RP). However, with the development of prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) and multiparametric magnetic resonance imaging (mpMRI), it might be feasible to avoid biopsy before RP. Herein, we aimed to explore the feasibility of avoiding biopsy before RP in patients highly suspected of having PCa after assessment of PSMA PET/CT and mpMRI. Between December 2017 and April 2022, 56 patients with maximum standardized uptake value (SUVmax) of ≥4 and Prostate Imaging Reporting and Data System (PI-RADS) ≥4 lesions who received RP without preoperative biopsy were enrolled from two tertiary hospitals. The consistency between clinical and pathological diagnoses was evaluated. Preoperative characteristics were compared among patients with different pathological types, T stages, International Society of Urological Pathology (ISUP) grades, and European Association of Urology (EAU) risk groups. Fifty-five (98%) patients were confirmed with PCa by pathology, including 49 (89%) with clinically significant prostate cancer (csPCa, defined as ISUP grade ≥2 malignancy). One patient was diagnosed with high-grade prostatic intraepithelial neoplasia (HGPIN). CsPCa patients, compared with clinically insignificant prostate cancer (cisPCa)andHGPIN patients, were associated with a higher level of prostate-specific antigen (22.9ng/mL vs. 10.0ng/mL, P=0.032), a lower median prostate volume (32.2mL vs. 65.0mL, P=0.001), and a higher median SUVmax (13.3 vs. 5.6, P<0.001). It might be feasible to avoid biopsy before RP for patients with a high probability of PCa based on PSMA PET/CT and mpMRI. However, the diagnostic efficacy of csPCa with PI-RADS ≥4 and SUVmax of ≥4 is inadequate for performing a procedure such as RP. Further prospective multicenter studies with larger sample sizes are necessary to confirm our perspectives and establish predictive models with PSMA PET/CT and mpMRI.

Simultaneous 18F-FDG PET/MRI predicting favourable surgical outcome in refractory epilepsy patients.

To evaluate the (1) successful surgery proportion in patients with clear structural lesions on MRI and single abnormality on 18F-fluorodeoxyglucose positron emission tomography/Magnetic resonance imaging (18F-FDG PET/MRI); (2) predictive value of 18F-FDG PET/MRI for postsurgical outcome in refractory epilepsy patients. A retrospective study was conducted on 123 patients diagnosed with refractory epilepsy who underwent presurgical evaluation involving 18F-FDG PET/MRI and were followed for one-year post-surgery. Two neuroradiologists interpreted the PET/MRI images using visual analysis and an asymmetry index based on the standard uptake value. The Engel classification was used to assess surgical outcomes one-year post-surgery. Prognostic factors predicting post-surgical seizure outcomes were explored using univariate and binary logistic regression. Definitely single lesion abnormality was observed in 35.0% (43/123) of the patients on the MRI portion of PET/MRI. The proportion increased to 74.0% (91/123) when 18F-FDG PET portion was added. About 75% (69/91) of patients displaying a clear-cut lesion on 18F-FDG PET/MRI were classified as Engel Class I one-year post-surgery. The proportion of Engel Class I patients was not significantly different when comparing MRI-single lesion patients with MRI-negative, PET-single lesion patients one year after surgery (81.4% vs. 70.0%, P = 0.24). Binary logistic regression analysis revealed that the detection of a clear single lesion on 18F-FDG PET/MRI was a strong positive predictor of a favorable surgical outcome (OR 3.518, 95% CI 1.363-9.077, p = 0.009). Single lesion detected on 18F-FDG PET/MRI is useful to predict good surgical outcome for refractory epilepsy patients; Those patients should be considered as candidates for surgery.

Effects of Glucose Intolerance on Physiological Accumulation in Salivary Glands and Palatine Tonsils During 18F-Fluorodeoxyglucose Positron Emission Tomography.

We evaluated the effects of chronic hyperglycemia on physiological accumulation in salivary glands and tonsils during18F-fluorodeoxyglucose positron emission tomography (FDG-PET/CT). 12,738 patients underwent whole-body FDG-PET/CT in our institute during the study period. Of these, the case group comprised 777 patients with a blood glucose (BG) level >140 mg/dL; the control group comprised an equal number of randomly selected age- and sex-matched individuals with a BG level <110 mg/dL. Within the case group, the diabetic subgroup was defined as individuals with a BG level >200 mg/dL. Visual assessment and accumulation intensity among tissues were compared between the case and control groups, including (1) the mean difference in maximum standardized uptake value (SUVmax), (2) the difference in the proportion of patients with visible tissues on maximum intensity projection images, and (3) differences between the diabetic subgroup and the control group. Parotid, submandibular, sublingual, and tonsillar tissues all showed significantly lower SUVmax in the case group than in the control group. The proportions of individuals with visible uptake in the parotid and tonsillar tissues and in the sublingual gland were significantly smaller in the case group than in the control group. Tonsillar uptake was observed in more than 90% of individuals in the control group but in two-thirds of patients in the diabetic subgroup. Accumulation in the parotid and submandibular glands was visible in approximately 80% of individuals in the control groupbut only half of patients in the diabetic subgroup. Physiological accumulation in salivary glands and tonsils is significantly reduced among individuals with hyperglycemia or diabetes.

A report on five cases of cholesterol granulomas in the thymus

BackgroundCholesterol granuloma (CG) is a benign entity characterized by the presence of cholesterol crystals and foreign body giant cells. This condition can be attributed to cholesterol crystals that are deposited in the tissues and react with foreign body giant cells, resulting in granuloma formation. Lesions commonly develop in the otolaryngeal region, such as the middle ear. However, crystals rarely form in the thymus, accounting for 1% of all mediastinal tumors. Herein, we present five cases of mediastinal CG.Case presentationThe patients were aged 49–61 (mean, 55.4) years. Among them, three were men and two women. One patient had fever, and four patients were asymptomatic. The patients’ lesions were detected during follow-up of other diseases or medical examinations showing the presence of abnormal chest shadows. The patients did not have a history of trauma or surgery. All lesions were located within the thymus gland. Three patients presented with multifocal lesions and two with a single lesion. Four patients had contrast effect on computed tomography scan. Four patients had abnormal fluorodeoxyglucose accumulation (mean maximum standardized uptake value, 4.67) on positron emission tomography-computed tomography. Four patients underwent complete surgical resection. The size of the resected lesions ranged from 1.8 to 5.1 (mean, 3.24) cm. Histologically, all patients presented with small nodules with cholesterol clefts and foreign body giant cells and histiocyte infiltration within the thymic tissue. The postoperative course was excellent. None of the patients who underwent complete resection presented with recurrence. Moreover, the patient who underwent partial resection did not have lesion enlargement.ConclusionsCG in the thymus is clinically challenging to differentiate from malignant lesions, and histologic diagnosis via surgical resection is required.