Search Results (1,410)

Background: Interictal [18F]FDG-PET is commonly used for temporal lateralization in mesial temporal lobe epilepsy (mTLE). Whether atlas-based quantitative PET measures differ according to surgical outcome among otherwise concordant unilateral MRI-positive mTLE patients remains uncertain. This study compared preoperative FDG-PET ROI measures between 2-year Engel outcome groups using SPM-assisted spatial normalization followed by AAL atlas-based ROI analysis. Methods: Among 319 screened temporal lobe epilepsy surgery patients, 94 had evaluable preoperative FDG-PET images, and 62 patients with at least 2 years of postoperative follow-up were included in the total cohort. The primary quantitative analysis was restricted to 54 unilateral MRI-positive patients with hippocampal atrophy and mesial temporal sclerosis on MRI (Engel I, n = 45; Engel II–IV, n = 9). Cerebellum-normalized AAL ROI uptake ratios were compared using Mann–Whitney U tests in conventional left/right and ipsilateral/contralateral analyses. FDR-adjusted q values, effect sizes, and Hodges–Lehmann median differences with 95% confidence intervals were calculated. Reference-region and global mean normalization sensitivity analyses were also performed. Results: In the unilateral MRI-positive subgroup, 10 of 80 conventional left/right ROIs showed unadjusted differences between Engel I and Engel II–IV patients, predominantly involving left frontal-orbitofrontal, medial frontal, middle cingulate, and inferior parietal regions. After ipsilateral/contralateral transformation, eight ROIs showed unadjusted group differences, mainly in contralateral frontal-orbitofrontal regions, with additional cingulate and inferior parietal involvement. Uptake ratios were lower in Engel II–IV patients in all candidate ROIs. However, none of the ROI findings survived FDR correction. Raw cerebellar uptake did not differ between outcome groups, and global mean normalization did not yield FDR-corrected ROI findings. Conclusions: Quantitative ROI analysis identified several extratemporal metabolic differences between postoperative outcome groups; however, none remained significant after correction for multiple comparisons. These findings should therefore be considered exploratory and hypothesis-generating rather than evidence that quantitative FDG-PET can discriminate surgical outcomes. Larger, adequately powered cohorts are needed before the potential clinical utility of quantitative FDG-PET analysis in presurgical evaluation can be determined. Full article

A 64-year-old woman presented with recurrent abdominal pain and rapid weight loss of 10 kg. Five years prior, an abdominal endovascular aneurysm repair (EVAR) was performed, followed by an open repair with proximal graft interposition due to an endoleak type IA two years ago. Laboratory tests revealed only moderately elevated infection markers (CrP 66 mg/L, WBC 14 GPt/L). ¹⁸F-FDG PET/CT showed a hypermetabolic peri-aortic mass initially suspected to be inflammatory. However, the patient did not exhibit signs of fever. Because of the equivocal constellation, a fine-needle biopsy was conducted, revealing malignant cells. The patient underwent complete tumor resection including aortic replacement. Histopathology confirmed the diagnosis of an angiosarcoma. The treatment was then supplemented with chemotherapy using doxorubicin and ifosfamide. Full article

Background/Objectives: Clinical outcomes in locally advanced rectal cancer (LARC) treated with total neoadjuvant therapy (TNT) remain heterogeneous, and available clinicopathological parameters provide limited prognostic accuracy. This study aimed to develop a radiomic score (RadScore) from baseline staging 18F-FDG PET/CT images using LASSO-penalized Cox regression, and to evaluate its ability to independently predict progression-free survival (PFS) in LARC patients treated with TNT followed by surgery. Methods: Eighty-five patients with LARC who underwent surgical resection after TNT between May 2018 and December 2024 were retrospectively analyzed. Primary tumor volumes were semi-automatically segmented on pretreatment FDG PET/CT images, and 140 radiomic features were extracted in accordance with Image Biomarker Standardisation Initiative (IBSI) guidelines. After correlation-based filtering, 23 non-redundant features were subjected to five-fold cross-validated LASSO-Cox regression for feature selection and RadScore construction. Internal validation used 1000-repetition bootstrap resampling. Results: Disease progression was recorded in 33 of 85 patients (mean PFS: 57.5 months). The final RadScore comprised two features—Intensity Histogram Kurtosis and GLCM Difference Entropy—and was identified as an independent prognostic factor in multivariable Cox analysis (HR = 1.81; 95% CI: 1.23–2.67; p = 0.003). The model achieved a C-index of 0.674, with a bootstrap-corrected C-index of 0.650 (95% CI: 0.568–0.741). Kaplan–Meier analysis demonstrated significantly shorter PFS in the high-risk group (log-rank p = 0.006). Conclusions: A pretreatment FDG PET-derived RadScore independently predicts PFS in LARC patients treated within a TNT framework, offering preliminary evidence for a potential imaging biomarker for preoperative risk stratification and individualized treatment planning—to our knowledge, among the first such evidence in a TNT-treated rectal cancer cohort. Full article

Background and Objectives: Accurate preoperative assessment of lymph node metastasis is essential for surgical staging and treatment planning in endometrial carcinoma. Magnetic resonance imaging (MRI) is widely used for local staging; however, its nodal performance is limited by reliance on morphologic criteria. 18F-FDG PET/CT provides whole-body functional assessment and may support decision-making when sentinel lymph node (SLN) mapping is unavailable. This study compared MRI and 18F-FDG PET/CT for preoperative detection of pelvic and paraaortic nodal metastases across pragmatic histologic risk groups. Materials and Methods: This retrospective diagnostic-accuracy study included 255 consecutive surgically treated patients with histologically confirmed endometrial carcinoma who underwent both preoperative pelvic MRI and whole-body 18F-FDG PET/CT at a tertiary gynecologic oncology center between December 2023 and December 2025. All patients underwent pelvic lymphadenectomy, 111 patients (43.5%) also underwent paraaortic lymphadenectomy, and SLN mapping was not performed. Patients were categorized as Group 1 (Grade 1–2 endometrioid adenocarcinoma) or Group 2 (Grade 3 endometrioid or non-endometrioid/aggressive histology). Diagnostic estimates were reported with 95% confidence intervals, paired comparisons were performed using exact McNemar tests, and multivariable bias-reduced logistic regression was used to assess independent imaging associations with nodal metastasis. Results: Any nodal metastasis was documented in 24 patients (9.4%). 18F-FDG PET/CT showed higher sensitivity than MRI for patient-level nodal detection (91.7%, 95% CI 74.2–97.7 vs. 37.5%, 95% CI 21.2–57.3), with similarly high specificity (97.0%, 95% CI 93.9–98.5 vs. 97.8%, 95% CI 95.0–99.1). The NPV of 18F-FDG PET/CT was 99.1% (95% CI 96.8–99.8), compared with 93.8% (95% CI 90.0–96.2) for MRI. MRI sensitivity was particularly low in Group 1 (18.2%, 95% CI 5.1–47.7), whereas PET/CT retained high sensitivity in both groups, though the perfect performance observed in Group 2 had wide confidence limits. Conclusions: 18F-FDG PET/CT demonstrated superior sensitivity and NPV compared with MRI for preoperative nodal assessment in endometrial carcinoma. These results support the selective use of PET/CT as an adjunctive staging tool in settings without SLN mapping, but they should not be interpreted as evidence that PET/CT can replace histologic nodal staging. Full article

Respiratory-gated PET/CT generates phase-resolved biomedical imaging data, but respiratory motion can cause spatial mismatch and lesion-level quantitative instability, especially for small thoracoabdominal lesions. This study proposes SCAR-Net, a Similarity-Constrained Adaptive Respiratory Registration Network, for retrospective phase-to-reference correction of respiratory-gated ¹⁸F-FDG PET/CT. SCAR-Net treats motion correction as a quantitative stability problem in phase-resolved PET/CT rather than only a generic registration task. It combines sampled group-aware feature encoding with adaptive group-attentive modulation to represent structured respiratory deformation and enhance motion-sensitive correspondence. The method was evaluated using controlled respiratory simulations and a retrospective two-center clinical cohort of 100 patients, jointly assessing lesion-level SUV repeatability, spatial correspondence, image similarity, deformation plausibility, center-stratified performance with B-spline FFD as a conventional reference, cross-dataset testing without target-domain fine-tuning, ablation behavior, and computational efficiency. In the independent clinical test set, lesion-level evaluation included 20 patients, 43 independent PET-avid lesions, and 245 evaluable lesion-phase pairs. In small-lesion phase pairs, SCAR-Net reduced median phase-to-reference variability to 6.45% for |ΔSUV_max| and 4.73% for |ΔSUV_mean|, and increased median lesion Dice from 0.55 to 0.72. In large-lesion phase pairs, SCAR-Net achieved a post-correction Dice of 0.89 and remained competitive for SUV repeatability. Descriptive center-stratified analysis showed a consistent lesion-level performance pattern across the two clinical acquisition settings. These findings suggest that SCAR-Net can improve phase consistency and quantitative stability in respiratory-gated PET/CT, with the clearest benefit observed in small-lesion assessment. Downstream clinical endpoints, such as diagnostic accuracy, tumor staging, PERCIST-based response assessment, and patient outcomes, were not evaluated and require future prospective validation. Full article

Background/Objectives: To evaluate whether global myocardial glucose metabolism and its regional heterogeneity, quantified using dynamic ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET), are associated with cardiovascular outcomes in patients with ischemic cardiomyopathy. Methods: The analytic cohort included 120 patients with suspected ischemic cardiomyopathy who underwent thallium-201 perfusion single photon emission tomography and dynamic FDG PET. Global myocardial metabolic rate of glucose (MRGlu) and coefficient of variation in FDG uptake were calculated from scar-excluded myocardium. Major adverse cardiac events (MACEs) were assessed over a median follow-up of 2.5 years. Public myocardial gene-expression datasets (GSE116250 and GSE135055) were analyzed to explore glucose metabolism-related transcriptional patterns relevant to the imaging findings. Results: Fifty-one patients (42.5%) experienced MACEs. Lower global MRGlu was independently associated with improved MACE-free survival (hazard ratio 0.48, 95% confidence interval 0.27–0.87). Among patients with low global MRGlu, a high coefficient of variation predicted favorable outcomes (hazard ratio 0.35, 95% confidence interval 0.18–0.68), indicating beneficial metabolic heterogeneity. Analysis of external gene-expression data demonstrated consistent downregulation of glucose-handling genes in end-stage heart failure across ischemic and dilated etiologies. A higher expression of SLC2A1, HK1, IRS1, and PKM was associated with faster progression to transplantation. Conclusions: In ischemic cardiomyopathy, dynamic FDG PET-derived quantification of myocardial glucose metabolism provides prognostic information beyond traditional viability assessment. Low global metabolism combined with preserved metabolic heterogeneity helps identify patients with favorable clinical outcomes. Full article

Vulvar cancer is a rare gynecologic malignancy with a bimodal age distribution, predominantly affecting older women while demonstrating increasing HPV-related incidence in younger populations. Accurate staging is essential for individualized treatment strategies to optimize outcomes while minimizing morbidity. Positron Emission Tomography (PET) has emerged as an important imaging modality in oncology; however, its precise role in vulvar cancer requires critical evaluation given the limited prospective evidence. This review focuses on the role of ¹⁸F-FDG PET/CT in vulvar cancer based on the literature published to date. Current evidence suggests that PET/CT provides high sensitivity for primary tumor detection and is particularly valuable for nodal and distant staging in locally advanced disease, where it may significantly influence management. However, its limited spatial resolution precludes detection of micrometastases, and it cannot replace sentinel lymph node biopsy for groin staging. PET/CT also contributes to radiotherapy planning through improved target delineation and demonstrates utility in detecting recurrence, although false positives remain a limitation. MRI remains superior for local staging, supporting a complementary multimodality imaging approach. Emerging tracers, including Fibroblast Activation Protein Inhibitor (FAPI), along with artificial intelligence-based radiomics, represent promising but still investigational directions. In conclusion, ¹⁸F-FDG PET/CT is a useful adjunct in vulvar cancer, especially for advanced disease, but its interpretation should be integrated within a multimodal framework due to limited supporting evidence. Full article

Background/Objectives: ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) reflects glucose metabolism but has limited diagnostic value for gliomas because of its high physiological uptake in the normal brain. This study visualized and characterized patterns of hypometabolism in non-contrast-enhanced gliomas using Z-score analysis and explored its potential for estimating isocitrate dehydrogenase (IDH) status. Methods: We retrospectively analyzed 116 patients with non-contrast-enhanced supratentorial gliomas, classified according to the 2021 World Health Organization classification (26 glioblastomas, IDH-wildtype; 54 astrocytomas, IDH-mutant; and 36 oligodendrogliomas, IDH-mutant and 1p/19q-codeleted). Z-score maps of FDG images were generated using a normal database. Tumor-associated hypometabolic regions (Z < −2) were analyzed, focusing on the proportion of severely hypometabolic regions (Z6–: Z < −6) and sphericity. Results: The mean Z-score differed significantly among the three subtypes, with the highest value observed in glioblastomas and the lowest in astrocytomas (p < 0.001). IDH-mutant gliomas showed a higher proportion of Z6– regions (p < 0.001) and higher sphericity (p = 0.009) than IDH-wildtype gliomas. In multivariable logistic regression, both the proportion of Z6– and sphericity were independent predictors of IDH status. Their combination demonstrated a strong discriminative performance for IDH status (area under the receiver operating characteristic curve = 0.839). On visual assessment, tumors with both small Z6– extent and low sphericity were primarily IDH-wildtype (75%), whereas the absence of both features indicated IDH-mutant status (94.8%). Conclusions: Z-score-based analysis enables the objective visualization and quantification of tumor-associated hypometabolic regions in non-contrast-enhanced gliomas, providing a potentially useful imaging biomarker for estimating IDH status. Full article

Background: The increasing use of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with breast cancer has led to a growing number of incidentally detected thyroid lesions. Thyroid incidentaloma refers to a focal area of increased metabolic activity within the thyroid gland. Up to 35% of focal thyroid incidentalomas are malignant. Early detection of thyroid carcinoma may allow less invasive surgical management and reduce the need for more extensive treatment associated with advanced disease, including total thyroidectomy, neck dissection, and radioactive iodine therapy. The objective of this study was to estimate the prevalence of focal thyroid incidentaloma and incidental thyroid carcinoma detected on PET/CT scans performed in breast cancer patients at a single tertiary medical center serving a highly ethnically diverse population. Methods: Medical records and PET/CT scans were retrospectively reviewed at a single medical center. Data collected included the presence of thyroid incidentaloma, maximum standardized uptake value (SUVmax), thyroid cytology, primary malignancy type, breast cancer status, ethnicity, and age. A total of 1233 patients with cancer who underwent PET/CT imaging and received treatment at ZIV Medical Center between August 2018 and December 2024 were included. Forty-two patients with primary thyroid carcinoma or head and neck carcinoma were excluded. Patients were categorized into breast cancer and non-breast cancer groups and compared regarding the prevalence of thyroid incidentaloma, referral rates for further evaluation by head and neck specialists, and the rate of incidental thyroid carcinoma. Results: Among 330 patients with breast cancer, 16 (4.8%) had a focal incidental thyroid finding, compared with 24 (2.8%) of 861 patients with non-breast malignancies who underwent PET/CT imaging. Among the 16 breast cancer patients with thyroid incidentaloma, thyroid carcinoma was subsequently confirmed in 4 patients (25%) who underwent further evaluation. The proportion of patients with confirmed thyroid carcinoma among those with incidentalomas was 1.2% (4/330) in the breast cancer group compared with 0.46% (4/861) in the non-breast cancer group. Approximately half of the patients in both groups were referred for further thyroid evaluation. Among breast cancer patients, non-significant trends toward higher referral rates were observed in patients with non-advanced disease, higher SUVs, and Jewish ethnicity. Nearly all patients evaluated by head and neck specialists underwent fine-needle aspiration (FNA). The mean SUV among patients diagnosed with papillary thyroid carcinoma (PTC) on FNA (n = 8; breast and non-breast cancer combined) was 15.2 (IQR: 7.3–17.0), compared with 5.2 (IQR: 5.0–6.0) among patients with benign cytology (n = 5; p = 0.011). Conclusions: Thyroid incidentalomas identified on PET/CT scans in breast cancer patients were relatively common in this cohort, and a proportion of evaluated lesions were subsequently diagnosed as thyroid carcinoma. Referral and diagnostic follow-up rates were variable, with approximately half of patients referred for further evaluation and only one-third attending a head and neck clinic. Given the retrospective design, limited number of biopsy-confirmed cases, and potential verification bias, these findings should be interpreted with caution. Nevertheless, they highlight the importance of clinical awareness and support individualized assessment of PET/CT-detected thyroid incidentalomas rather than broad management recommendations. Full article

Background/Objectives: Cardiac involvement in sarcoidosis necessitates meticulous management, with accurate and timely diagnosis being crucial. The hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) modality is an emerging diagnostic tool for cardiac sarcoidosis, offering potential advantages over the use of independent PET and MRI techniques for both diagnosis and prognosis. Methods: Following the PRISMA guidelines for study selection, a comprehensive search using the terms “hybrid PET/MRI” and/or “cardiac sarcoidosis” identified a total of 10 eligible studies. Results: Patients were primarily middle-aged males. Overall, hybrid PET/MR enhanced diagnostic accuracy by identifying specific subgroups, detecting active disease, enabling detailed quantitative analysis, and assessing regional involvement. Additionally, it offered valuable insights that could improve phenotyping and prognostic predictions. The primary limitation was the longer duration of a single scan; however, the total scanning time was reduced compared to conducting two separate procedures. Conclusions: Hybrid PET/MR imaging offers several significant advantages over separate imaging modalities when diagnosing cardiac sarcoidosis, including increased diagnostic accuracy and comprehensive tissue characterization. Further comparative studies are needed to fully understand its clinical impact and potential limitations. Full article

Functional imaging has become an important approach for evaluating tumor physiology in vivo beyond morphologic assessment. Radiotracers used for cancer imaging are designed to mimic endogenous substrates or substrate analogues, and their accumulation can depend on membrane transport, intracellular metabolism, and clearance from normal tissues. Specifically, SLC transporters contribute to tracer uptake and signal formation, linking transporter activity with measurable imaging signals in cancer. While [¹⁸F]FDG PET/CT remains the most widely used example of transporter-associated metabolic imaging, SLC transporter-mediated imaging strategies have been developed to assess amino acid transport, sodium-dependent glucose uptake, redox metabolism, lactate exchange, nucleoside metabolism, choline metabolism, and iodide accumulation. Herein, we provide an overview of current applications of SLC transporter-mediated functional imaging in cancer diagnosis, with an emphasis on glucose and amino acid systems. Special attention is given to the relationship between transporter physiology, tracer uptake, tumor type, and diagnostic application. Full article

Background: Circulating tumor HPV DNA (ctHPV DNA) has shown clinical value in HPV-positive oropharyngeal squamous cell carcinoma (OPSCC), but its relationship with tumor burden and its role in prognosis, especially when combined with clinicoradiological factors, remain to be further defined. Methods: We analyzed 103 patients with HPV-positive OPSCC enrolled in an observational biomarker study, most of whom received induction chemotherapy or chemoimmunotherapy followed by definitive radiotherapy. Blood samples were collected at pretreatment, post-radiotherapy, and follow-up time points, and ctHPV DNA levels were quantified using droplet digital PCR. Baseline clinicoradiological parameters from contrast-enhanced MR or CT and ¹⁸F-FDG PET/CT were analyzed for their association with ctHPV DNA levels and clinical outcomes. Results: Baseline ctHPV DNA correlated with primary tumor volume (V_T), nodal volume (V_N), total tumor volume (V_T+N), and the number of involved primary tumor sites and lymph node regions, particularly LN-related features. V_T and maximum LN diameter were independent predictors of baseline ctHPV DNA. Detectable follow-up ctHPV DNA was associated with inferior progression-free survival but showed low sensitivity and positive predictive value for relapse detection. Integrative stratification using baseline ctHPV DNA and V_T+N identified a potential high-risk subgroup with high tumor volume but paradoxically low ctHPV DNA (VOL^highDNA^low). Exploratory RNA-seq analysis was performed to investigate potential biological features underlying this discordance, and a seven-gene signature associated with PFS was identified. Conclusions: These findings suggest that baseline ctHPV DNA reflects tumor burden and may provide additional information for upfront risk stratification in HPV-positive OPSCC, warranting further validation in larger prospective cohorts. Full article

Background/Objectives: Multiple myeloma (MM) is a complex hematologic malignancy characterized by abnormal plasma cell proliferation in the bone marrow. [¹⁸F]FDG PET/CT has emerged as a key imaging modality, demonstrating high sensitivity and specificity for the detection of metabolically active disease compared with conventional imaging techniques. This review examines the role of PET/CT imaging in evaluating therapeutic response in symptomatic myeloma, including minimal residual disease (MRD) assessment. Methods: We surveyed the literature published between 2014 and 2024 across PubMed, Scopus, Web of Science, and the Cochrane Library for peer-reviewed articles evaluating PET imaging in the assessment of treatment response in multiple myeloma. Results: [¹⁸F]FDG PET/CT provides a whole-body assessment of disease burden, extramedullary involvement detection, and early metabolic response evaluation. Standardized response assessment criteria (Deauville, IMPeTUs, IMWG) have enhanced the reproducibility and accuracy of treatment monitoring. Semiquantitative parameters including SUVmax and metabolic tumor volume (MTV) provide useful prognostic information with PET negativity correlating with improved progression-free and overall survival. The integration of PET/CT with bone marrow assessment techniques (next-generation flow cytometry and sequencing) optimizes MRD evaluation and patient stratification. Conclusions: PET/CT represents a valuable imaging tool for improving therapeutic decision making and risk stratification in MM management. Emerging radiotracers beyond FDG, including [¹¹C]choline, [¹¹C]methionine, and targeted agents like [⁶⁸Ga]pentixafor and CD38-targeted immunoPET tracers, hold promise for enhanced diagnostic capabilities in specific clinical contexts. Full article

Background: Routine use of the chorioallantoic membrane (CAM) tumor model in nuclear imaging studies is hampered by small tumors, embryonic movements and laborious volume-restricted intravenous tracer/drug administration. We sought a workaround by using fast-growing tumors, high-resolution autoradiography and non-intravenous tracer administration. Methods: Dekalb White chicken eggs were grafted with C3H mammary carcinoma fragments or MOC2 oral squamous cell carcinoma fragments from donor mice. The tumor uptake of ¹⁸F-fluorodeoxyglucose (FDG) following in-yolk-sac injection, dripping after CAM scoring or allantoic cavity injection was evaluated using positron emission tomography (PET) and autoradiography. Using in-yolk-sac injection, eggs were administered different tracer mixtures, namely (1) pimonidazole (hypoxia-marker), FDG and ¹⁴C-2-deoxyglucose (¹⁴C-2DG), (2) pimonidazole, FDG and ¹⁴C-acetate or (3) pimonidazole, the hypoxia-selective tracer ¹⁸F-fluoroazomycin-arabinoside (FAZA) and ¹⁴C-2DG. For comparison, tumor-bearing mice were administered FDG/¹⁴C-acetate/pimonidazole. Gross tumor uptake was evaluated using PET. Tumor cryosections were analyzed using dual-tracer autoradiography. Complementary autoradiograms were co-registered, covered by a square grid (0.5 × 0.5 mm). Pearson correlation coefficients (PCC) were calculated from scatterplots. Results: C3H tumors reached a mean weight (with 95% confidence interval) of 0.32 g (0.28–0.37 g), while for MOC2, it was 0.19 g (0.09–0.29 g). In-yolk-sac tracer injection was simple and effective, producing high tracer uptake and contrast 3 h post-administration. Spatial tracer overlap (PCC) was: FDG vs. ¹⁴C-2DG, 0.95–0.97; FAZA vs. ¹⁴C-2DG, 0.71–0.79 and FDG vs. ¹⁴C-acetate, 0.26–0.84 (0.15–0.76 in mice). Pimonidazole revealed tumor hypoxia. Conclusions: Direct-grafting from donor mice generated larger tumors than previously reported. In-yolk-sac tracer administration was practical and allowed larger injected volumes. Autoradiography revealed that: (1) FDG and ¹⁴C-2DG can be used interchangeably, (2) ¹⁴C-2DG was elevated in FAZA-positive areas, suggesting that in some tumors FDG-PET may provide information on the intratumoral distribution of hypoxic areas, and (3) FDG and ¹⁴C-acetate showed variable overlap. We conclude that in-yolk-sac tracer injection and autoradiography simplify and optimize CAM-based nuclear imaging research. Full article

Background/Objectives: The use of quantitative neuroimaging to establish objective biomarkers in neurodegenerative diseases (NDD) has attracted increasing interest over the last decade. Advanced magnetic resonance imaging (MRI) such as arterial spin labeling (ASL) and diffusion tensor imaging (DTI), as well as [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography (PET), could provide clinically meaningful biomarkers and may support differential diagnosis. The aim of this investigator-initiated, single-center, retrospective comparative study was to implement a framework for multimodal neuroimaging to evaluate cases with rare NDD, using a methodological approach that integrates metabolic, perfusion, and microstructural parameters from simultaneous FDG-PET/MRI, and to investigate its potential to facilitate diagnosis. Methods: Three patients with pathological motor signs (1f/2m; 63, 73, and 52 years) and 19 control subjects with subjective cognitive deficits (SCDs) underwent combined FDG-PET/MRI with pseudo-continuous ASL and DTI. Standardized uptake values (SUVs), relative cerebral blood flow (rCBF), and fractional anisotropy (FA) were calculated to identify pattern alterations in individual patients based on parameterization mapping. The final diagnosis was corticobasal degeneration (CBD, n = 1) or primary lateral sclerosis (PLS, n = 2). Results: At the individual patient level, disease-specific changes in defined brain regions could be demonstrated and quantified compared to control subjects. All three patients showed significantly decreased FA, primarily along parts of the course of the corticospinal tract (CST). In the patient with CBD, asymmetric SUVR and rCBF decreases were observed, mostly overlapping with motor regions. In the two patients with PLS, SUVR revealed mostly unspecific findings (hypothetically due to a slow progression rate or due to potentially early disease stages), while ASL indicated decreased rCBF primarily overlapping within the motor cortex. Changes at the gray matter level were primarily located adjacent to changes in white matter, as indicated by the multimodal analysis approach using simultaneously acquired FDG-PET/MRI data. Conclusions: According to this proof-of-concept study, multimodal neuroimaging by the combination of quantitative MRI and FDG-PET has the potential to guide differential diagnosis in rare NDDs, especially if clinical diagnosis is not straightforward to achieve. Since particularly early diagnosis remains essential for patient counseling, effective treatment, and clinical management, the present framework appears helpful to be developed further until it aligns and integrates with clinical routine. Full article