There remain large variations in cochlear implant auditory-speech perception ability, which are poorly explained by patient history factors. This study aims to better understand how combinations of speech processing limitations, identified using psychophysical and functional brain imaging measures, are associated with long-term speech understanding outcomes of new cochlear implant recipients. Forty-three cochlear implant recipients (44 ears) were recruited to participate in a longitudinal study to evaluate limitations at various locations along the auditory processing pathway. At the periphery, intra-cochlear neural health was estimated using focused psychophysical thresholds. Higher-order across-electrode intensity discrimination ability was assessed using psychophysical "spectral tilt." At the cortical level, cross-modal activation of the auditory cortex was assessed using functional near-infrared spectroscopy. Speech understanding outcomes were evaluated in competing multi-talker babble noise at 1-year post-device switch-on. We found that greater abilities to discriminate smaller across-electrode stimulation intensities (R2 = 0.138, p = 0.047) and smaller cross-modal activations of the auditory cortex (R2 = 0.216, p = 0.01) were significantly associated with better speech understanding outcomes in cochlear implant recipients. Furthermore, both measures contributed significantly to better predict speech understanding outcomes in a multiple regression model (Adj R2 = 0.312, p = 0.009). The results suggest that recipient-specific psychophysical and functional brain imaging metrics contribute significantly toward individual differences in speech understanding outcomes. Different recipients can be affected by different limitations, which can be identified using these tests, and therefore lead to potential patient-specific methods to improve their speech understanding.

General anesthesia is administered to millions of children annually, yet its long-term effects on neurodevelopment remain a concern. It was previously reported that even a single early exposure to general anesthesia for minor surgery impairs visual attention in children. This study investigates the effects of early repeated general anesthesia exposure on visual system maturation in mice and explores the role of tissue-type plasminogen activator in mediating these effects during development. Male SWISS and C57BL/6J mice (wild-type or deficient for tissue-type plasminogen activator) were exposed to general anesthesia with 1.3% isoflurane in 50% oxygen for 90 min per day from postnatal days 4 to 10. Control animals received 50% oxygen alone. Visual system integrity and inflammation were assessed at postnatal day 15 and at 6 weeks using behavioral tests, high-resolution imaging, and immunohistochemistry. In SWISS mice, circulating tissue-type plasminogen activator levels were measured using a biochemical approach, and neurovascular coupling was evaluated by functional ultrasound imaging. Early repeated general anesthesia exposure delayed eyelid opening (median postnatal day 13 [95% CI, 0.52 to 1.45] vs. postnatal day 15 [95% CI, 0.62 to 1.92]; P < 0.0001), caused lasting visual function deficits (depth perception and oculomotor reflex), and reduced retinal (0.2627 ± 0.04 mm vs. 0.1667 ± 0.03 mm; P < 0.0001) and primary visual cortex thickness (0.8000 ± 0.08 mm vs. 0.7282 ± 0.05 mm; P = 0.0235). Notably, lower circulating tissue-type plasminogen activator levels were observed in general anesthesia-exposed SWISS mice (11.580 ± 2.19 ng/ml vs. 7.654 ± 1.31 ng/ml; P = 0.0082). Tissue-type plasminogen activator-deficient mice exhibited attenuated or absent general anesthesia-induced visual alterations. These findings indicate that early repeated exposure to general anesthesia disrupts visual system maturation in mice and suggest that altered tissue-type plasminogen activator pathways may contribute to these effects, identifying tissue-type plasminogen activator as a potential marker of anesthesia-related neurodevelopmental vulnerability. Additional experimental work will be required to further support this association and clarify its underlying mechanisms.

Objective This study aimed to map and synthesize the available evidence on screening tools for diabetic sarcopenia in patients with type 2 diabetes mellitus (T2DM), highlighting their characteristics, application contexts, and research gaps. Methods A comprehensive search was conducted in PubMed, Web of Science, CNKI, and Wanfang Data to identify studies published from 2010 to Deccember 2025. Studies involving adults with T2DM that evaluated screening tools for sarcopenia against established diagnostic criteria (EWGSOP, AWGS, FNIH, or IWGS) were eligible. Two reviewers independently screened studies, extracted data, and assessed methodological quality using the QUADAS-2 tool. Findings were charted and synthesized narratively, with screening tools grouped into functional assessments, anthropometric measures, biomarker-based methods, imaging approaches, and predictive models. Results A total of 24 studies with 9,469 participants were included. The most common screening tools were functional assessments, anthropometric measures, biomarkers, and muscle ultrasound. SARC-F showed moderate sensitivity (13.33%-62.63%) and high specificity (67.30%-91.67%), while SARC-CalF improved diagnostic performance. Muscle ultrasound demonstrated high accuracy, with sensitivity ranging from 71.05% to 95.00%. Predictive models with multiple variables (Age, BMI, HbA1c) showed AUC values between 0.800 and 0.932. Challenges included inconsistent cut-off values and limited validation across diverse populations. Conclusion Various screening approaches for diabetic sarcopenia have been explored, but no single tool is universally validated for T2DM. Combining functional questionnaires with objective assessments like ultrasound or biomarkers may offer a more practical solution. Future research should focus on standardizing thresholds and testing tools in diverse populations.

Lumbosacral transitional vertebrae (LSTV) are a common congenital anomaly that often manifests as chronic low back or radicular pain, a condition clinically referred to as Bertolotti syndrome. One specific cause of Bertolotti syndrome is pseudoarticulation of the L5 transverse process with the sacrum or ilium due to LSTV. Although conventional magnetic resonance imaging (MRI) and computed tomography can identify structural changes, they provide limited functional information regarding sites of active arthropathy. Single-photon emission computed tomography (SPECT-CT) enables the localization of metabolically active pseudoarthrotic joints, thereby improving patient selection and surgical planning. We present the case of a 52-year-old woman with Bertolotti syndrome who presented with severe chronic axial back pain and left-sided pain radiating along portions of the L5 and S1 dermatomes. MRI revealed no significant compression of the neural elements but did demonstrate an incidental Tarlov cyst at S1, measuring 5.7 mm × 5.7 mm. SPECT-CT demonstrated localized, abnormal uptake between an anomalous left L5 transverse process and the sacrum. The patient underwent minimally invasive, image-guided removal of the left L5 transverse process, isolating L5 vertebral motion from the iliac crest. She was discharged on postoperative day 1 with significant improvement in her pain and radiculopathy. At 6-week, 3-, and 6-month follow-up, she reported near-complete resolution of presurgical radicular pain, functional restoration, and a return to normal activities. This case highlights the utility of SPECT-CT in evaluating Bertolotti syndrome. Functional imaging enabled precise structural localization of the pain generator, while targeted minimally invasive resection provided durable symptom relief.

Marine mammals possess specialized respiratory adaptations that enable efficient gas exchange and resilience to extreme pressures during diving, yet direct observation of lung mechanics under pressure has been logistically challenging. Electrical Impedance Tomography (EIT) measures real time changes in thoracic impedance, and provides continuous, regional maps of pulmonary air distribution. We validated EIT for estimating tidal volume (VT) in bottlenose dolphins (Tursiops spp.) and Cape fur seals (Arctocephalus pusillus) both on land and in water. EIT reliably tracked VT in both genera, showing strong within trial consistency, with between trial variability attributable to belt placement, body position, and electrode contact. EIT also generated dynamic functional images of regional ventilation, revealing spatial and temporal patterns of lung filling and emptying. These results demonstrate that EIT is the first non-invasive imaging method validated for marine mammals in seawater, representing a critical step toward visualizing lung function during diving.

Arginine vasopressin (AVP) and oxytocin (OT) are peptide hormones critical for various physiological processes. Vasopressin receptor 1 A (V1aR), a primary AVP target, is promising for central nervous system (CNS) disorders therapies, yet the mechanisms of antagonism and oligomerization remain poorly understood. Here, we present structures of human V1aR in its apo state and in complexes with antagonists: atosiban, balovaptan, and SRX246. Structural analyses reveal a dimeric V1aR assembly, validated by functional assays and imaging in cells. The apo structure shows a flat extracellular loop 2 (ECL2) with unpaired cysteines, undergoing significant conformational changes upon ligand binding. Antagonist-bound structures, combined with mutagenesis and radioligand binding assays, uncover distinct binding modes and key determinants for antagonism and selectivity. These findings provide a comprehensive understanding of V1aR assembly and dynamic regulation, offering valuable insights for structure-guided development of new antagonists targeting dimeric V1aR for CNS disorders.

In functional imaging studies, the activity and functional connectivity of regions of interest (ROIs) are two indexes to measure the importance of ROIs. This study aimed to investigate the activity-connectivity coupling relationships of ROIs during action observation-induced swallowing imagery and non-induced swallowing imagery tasks. Magnetoencephalography data were collected from fourteen healthy young participants. Time-frequency analysis of event-related spectral perturbations was conducted to assess the activity of ROIs during the tasks. Using corrected imaginary phase locking values to construct brain functional networks, network parameters are computed to assess connectivity. The correlation between activity and connectivity was evaluated using Pearson coefficients. Furthermore, the nodes were categorized into hot hubs (strong activity + strong connectivity), nonhub hotspots (strong activity + weak connectivity), cold hubs (weak activity + strong connectivity), and nonhub cold spots (weak activity + weak connectivity) for further analysis, and dark functional networks (subnetworks composed of cold hubs) were detected and analyzed. Both tasks exhibited positive activity-connectivity coupling relationships, however, the coupling strength remained below a moderate level (< 0.6). Notably, both tasks demonstrated limited activation of hot hubs. During the action observation-induced swallowing imagery task, there was a notable increase in the activation of non-hub hotspots within the visual system, extending bilaterally. Additionally, the dark functional network, composed of cold hubs, exhibited increased swallowing-related ROIs in action observation-induced swallowing imagery task. This study provides insights into the activity-connectivity coupling and dark functional network characteristics during swallowing imagery tasks. The findings contribute to our understanding of the neural mechanisms underlying swallowing imagery and may have implications for the development of therapeutic interventions for swallowing disorders.

Shared and distinct neural signatures in major depressive disorder and comorbid post-traumatic stress disorder: Insights from structural and functional imaging.

Background: Magnetic Resonance Imaging (MRI) has emerged as a quintessential tool in the assessment and control of brain tumors due to its non-invasive nature and advanced soft-tissue assessment. This evaluation examines the modern-day applications and destiny possibilities of MRI in brain tumor evaluation. Traditional structural imaging, inclusive of T1- and T2-weighted imaging, plays a critical position in figuring out tumor place, size, and related edema, at the same time as advanced strategies offer deeper insights into tumor biology. Functional imaging modalities inclusive of Diffusion-Weighted Imaging (DWI) and Perfusion-Weighted Imaging (PWI) permit differentiation of tumor grades, identity of remedy results, and evaluation of tumor cellularity and vascularity. Magnetic Resonance Spectroscopy (MRS) enables the analysis of tumor metabolism, providing treasured records on biomarkers including choline and lactate. Emerging techniques like Chemical Exchange Saturation Transfer (CEST) MRI are being advanced for extra precise molecular and metabolic characterization. Future advancements encompass the mixing of synthetic intelligence (AI) for computerized tumor detection, category, and prediction of healing responses. AI models blended with radiomic evaluation hold promise for customized treatment strategies. Intraoperative MRI has more desirable surgical effects by using allowing actual-time imaging, enhancing tumor resection accuracy, and retaining healthy tissue. Furthermore, extremely-high-area MRI (7T) gives extraordinary spatial and contrast decision, facilitating particular evaluation of tumor microenvironments. Despite its transformative effect, challenges continue to be, inclusive of excessive charges, accessibility problems, and interpretation variability. The aim of this review is to explore the current and future advancements in MRI technology for brain tumor evaluation, highlighting the integration of AI, advanced imaging techniques, and intraoperative MRI to improve tumor detection, treatment planning, and surgical outcomes. It also addresses challenges such as cost, accessibility, and interpretation variability.

Background Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for Parkinson's disease (PD) patients. However, postoperative outcomes vary with no reliable predictive method. Methods Our study involves 43 PD patients undergoing STN-DBS. Preoperative resting-state functional magnetic resonance imagings (rs-fMRI) were collected. The volume of tissue activated (VTA) was defined based on contact points and stimulation parameters. A model of the cortico-basal ganglia network was established using dynamic causal modeling. The correlation between the UPDRS-III and the network edges was determined through Pearson correlation analysis. Furthermore, a generalized linear model was employed to predict the post-DBS motor improvement. Results Individual STN-VTA intersections were found to be important to UPDRS-III improvement induced by DBS (R = 0.59, P = 0.001). STN-VTA intersections were related to the thalamic-primary motor cortex (M1) (R = 0.47, P = 0.005), and M1-STN (R = 0.40, P = 0.006) coupling strength. The coupling strength of Thal-M1 (R = 0.442, P = 0.009) and M1-STN (R = 0.481 P = 0.004) resulted in DBS-induced movement enhancement, particularly rigidity. The strength of effective connections within the STN-Thal-M1 pathway was found to predict improvements in UPDRS-III scores ( P = 0.003). Conclusion Our study confirmed the relationship between clinical improvements in STN-DBS and target location as well as the stimulation parameters. By constructing personalized cortical-basal ganglia network models based on target location as well as the stimulation parameters, we discovered that the effective connection strength in STN-THA-M1 can predict motor improvement in PD patients undergoing STN-DBS.

The kidneys play a vital role in filtration, excretion, and metabolic regulation, making accurate functional assessment essential for diagnosis, monitoring, and management of renal diseases. While conventional imaging modalities such as ultrasonography, computed tomography (CT), and multiparametric magnetic resonance imaging (MRI) provide structural and functional information, nuclear medicine techniques enable more detailed evaluation of renal physiology at the molecular level. This review provides a comprehensive overview of functional renal imaging using both conventional renal scintigraphy and emerging positron emission tomography (PET) radiopharmaceuticals. Established renal scintigraphy radiopharmaceuticals, including 99mTc-DTPA, 99mTc-DMSA, 99mTc-MAG3, and 99mTc-EC, have long been applied to assess glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). PET radiopharmaceuticals, offering higher sensitivity, superior quantification, and molecular insight, are increasingly investigated for similar purposes, with 68Ga-EDTA, 68Ga-DTPA, 68Ga-NOTA, 68Ga-DOTA, and 18F-FDS for GFR assessment and 11C-PABA, 18F-PFH, Re-(CO)3(18F-FEDA), and Al-18F-NODA-butyric acid for ERPF evaluation. Additional PET tracers, including 68Ga-IRDye800-tilmanocept, 18F-FDG, and 68Ga-PSMA-11, have been explored for glomerular mesangial function, renal tumors, and split renal function, respectively. By systematically summarizing both renal scintigraphy and PET approaches, this review highlights current and emerging PET radiopharmaceuticals for renal functional imaging and discusses their potential clinical applications and future perspectives in precision nephrology.

Objective Postherpetic neuralgia (PHN), a refractory neuropathic pain following herpes zoster reactivation, lacks clear central mechanisms for emerging therapies like short-term spinal cord stimulation (stSCS). This longitudinal study used multimodal neuroimaging to examine the effects of 14-day stSCS on brain function and white matter microstructure in PHN patients, and to identify neural correlates of clinical improvements. Methods In this longitudinal, single-arm, pre-post study, 17 PHN patients received 14 days of continuous stSCS. Clinical outcomes including pain intensity (Numeric Rating Scale, NRS), anxiety and depression (Hospital Anxiety and Depression Scale, HADS), and sleep quality (Pittsburgh Sleep Quality Index, PSQI), were assessed pre-stSCS and 3 days post-stSCS. Resting-state functional MRI (rs-fMRI) and Diffusion Tensor Imaging (DTI) data were acquired at both time points. Longitudinal changes in amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) were analyzed, alongside white matter integrity via TBSS and ROI analysis of key tracts. Results Post-stSCS, significant improvements occurred in all clinical outcomes (Wilcoxon signed-rank, all p &amp;lt; 0.001). Neuroimaging showed no DTI microstructural changes but significant fALFF increases in regions including the dorsal striatum. Notably, right medial orbitofrontal cortex (mOFC) fALFF increases correlated with NRS reductions (Spearman’s r = 0.71, FDR-corrected p = 0.036). Baseline cingulum integrity (lower FA, higher MD/RD) predicted greater striatal fALFF changes ( r = ±0.75, FDR-corrected p &amp;lt; 0.02). Conclusion These findings suggest that stSCS’s early clinical benefits in PHN are mediated by rapid functional reorganization rather than immediate microstructural changes. This reorganization appears prominent within fronto-striatal circuits: specifically, mOFC functional changes correlate with analgesia, while baseline cingulum integrity predicts subsequent striatal plasticity. This provides initial mechanistic insights into stSCS and suggest that baseline brain structure could be explored as a potential biomarker for treatment response, warranting validation in larger, controlled cohorts.

IntroductionWell-differentiated metastatic functioning neuroendocrine tumors (NETs), particularly of gastrointestinal origin, pose diagnostic and therapeutic challenges. Although often slow growing, they may follow an unpredictable course. Somatostatin analogues (SSAs) are the first-line therapy, while peptide receptor radionuclide therapy (PRRT) with Lu-177-DOTATATE has become an established second-line option in progressive disease. Here, we present a case of functioning NET with liver, mesenteric and bone involvement, showing favorable long-term response to initial PRRT and later re-treatment upon biochemical progression.Clinical CaseA 2019 initial evaluation revealed multiple hepatic metastases, mesenteric nodules and bone lesions. Octreoscan confirmed somatostatin receptor expression. Diagnosis: functioning NET, likely gastrointestinal origin, stage IV. The patient was started on lanreotide 120 mg/month. In 2020, PET-Ga68 demonstrated progressive disease; liver biopsy confirmed well-differentiated G1 NET (low Ki-67). The NET tumor board recommended PRRT with Lu-177-DOTATATE. Post-therapy follow-up showed biochemical improvement and radiologic stabilization. PET-Ga68 in 2022 and CT in 2023 confirmed partial tumor shrinkage with stable disease.In April 2024, PET-Ga68 revealed persistent somatostatin-avid metastases with minor radiologic progression. Despite this, the patient remained asymptomatic, with preserved renal and bone marrow functions. In early 2025, the multidisciplinary team proposed PRRT re-treatment due to favorable profile: G1 tumor, strong receptor expression, no clinical deterioration and a progression-free interval >3 years. A dosimetric evaluation was performed, and a new Lu-177 cycle was scheduled. This decision was supported by international guidance and by increasing real-world experience suggesting that PRRT re-treatment may be a safe and effective option in selected patients.ConclusionThis case underscores the importance of multidisciplinary management in advanced NETs and highlights the potential of PRRT not only in initial treatment but also as re-treatment in selected patients. Key criteria for re-treatment include sustained receptor expression, clinical stability, organ function preservation, and significant time since first PRRT. Re-treatment with Lu-177 should be considered a valuable tool in the therapeutic arsenal for NETs, especially when tumor biology and patient profile remain favorable over time. This case also illustrates the relevance of integrating functional imaging and dosimetric evaluation into personalized decision-making pathways. Individualized assessment and adherence to updated guidelines are essential for optimizing outcomes.

ObjectivesTo assess the correlation between the functional liver imaging score (FLIS) and FibroScan®-derived fibrosis stage, and to determine whether incorporating parenchymal heterogeneity (FLIS-H) improves its association with fibrosis and clinical scores.Materials and methodsThis retrospective single-centre study included 113 patients who underwent FibroScan® and hepatocyte-specific contrast-enhanced MRI within a median interval of 4 days. FLIS was calculated, and the parenchymal heterogeneity score was added to FLIS (FLIS-H; range 0–8). Inter-reader agreement was evaluated using a two-way random-effects intraclass correlation coefficient (ICC). Correlations between FLIS/FLIS-H and fibrosis stage/clinical scores (Child–Pugh, MELD, ALBI) were assessed using Spearman’s rank correlation. Steiger’s z-test and Zou’s method were used to compare correlations.ResultsA total of 113 patients (67 men; mean age 56.6 ± 13.5 years) were evaluated. Inter-reader agreement was excellent for FLIS (ICC 0.994; 95% CI: 0.975–1.000), heterogeneity (ICC 0.949; 95% CI: 0.901–0.984), and FLIS-H (ICC 0.974; 95% CI: 0.957–0.989). FLIS showed significant negative correlations with Child–Pugh (ρ = −0.2664, p = 0.0087), ALBI (ρ = −0.3076, p = 0.0022), and fibrosis stage (ρ = −0.3207, p < 0.001). FLIS-H demonstrated stronger correlations with Child–Pugh (ρ = −0.4167, p < 0.001), ALBI (ρ = −0.5243, p < 0.001), MELD (ρ = −0.2360, p = 0.020), and fibrosis stage (ρ = −0.5270, p < 0.001). Steiger’s z-test confirmed that correlations were significantly improved with FLIS-H for ALBI (z = −3.03, p = 0.0025), Child–Pugh (z = −2.01, p = 0.045), and fibrosis stage (z = −2.90, p = 0.0038).ConclusionFLIS correlates significantly with fibrosis stage and clinical scores. Incorporating parenchymal heterogeneity into FLIS enhances these associations and may provide a superior method for liver assessment.Critical relevanceThis study introduces a modified FLIS version (FLIS-H) that integrates parenchymal heterogeneity and demonstrates superior correlation with elastography-derived fibrosis stages and clinical scoring systems, offering a practical improvement for non-invasive assessment in routine practice.Key PointsFLIS has no reported correlation with elastography-based liver fibrosis staging.Parenchymal heterogeneity is not included as a parameter in the standard FLIS.Integrating heterogeneity improves correlation with fibrosis stage and clinical scores.FLIS-H enables fast, reliable, structure-function liver assessment in clinical radiology.Graphical

Lung cancer is a major disease that seriously threatens human life and health. As one of the main treatment methods for lung cancer, radiotherapy (RT), while combating cancer cells, inevitably causes damage to the surrounding normal lung tissues. Radiation-induced lung injury (RILI) is a common and serious complication of RT that can seriously affect the treatment process of patients, reducing their quality of life (QOL) and survival time. Conventional RT aims to reduce the incidence of RILI in patients by limiting the radiation dose to normal lung tissue. This approach assumes that lung function is uniformly distributed. However, there is heterogeneity in human lung function. To address this challenge, functional lung imaging (FLI) has emerged and become a research focus. In the field of medical imaging technology, Single-Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), CT, and other technologies can all obtain FLI. Whatever imaging modality is used, lung perfusion (Q) on imaging serves as a surrogate for RILI. Furthermore, the combination of FLI and RT has given rise to functional lung avoidance RT (FLART), which can precisely reduce radiation exposure to functional lung (FL) regions by adjusting the radiation dose distribution, thereby effectively reducing the incidence of RILI. This narrative review comprehensively explores several key aspects, including FLI modalities, the definition of FL, the clinical applications of FLART, the impact of FLART on QOL, and the limitations of FLART. These discussions provide a good basis and guidance for the follow-up clinical work.

Functional imaging reveals cerebral microvascular dysfunction in primary antiphospholipid syndrome: Pathophysiologic insights and translational implications.

Neuromodulatory effects of dual-site repetitive transcranial magnetic stimulation targeting frontal and temporal cortices in subjective tinnitus: A functional magneti resonance imaging study.

Coronary anatomy detects, ischemia predicts: Real-world insights from the Nancy ischemia registry

Differential synaptic signaling responses in human cortical organoids after photon and proton irradiation.

Regional lung ventilation imaging using xenon-enhanced dual-energy CT (Xe-DECT) offers valuable insight into obstructive pulmonary diseases but remains limited in clinical use due to technical and logistical constraints. In this study, a multi-task conditional generative adversarial network (GAN) was developed to generate deep learning-generated ventilation images (DL-Vent) from virtual non-contrast (VNC) images. A total of 269 scans from 177 patients with COPD or asthma-COPD overlap syndrome (ACOS) were used to train, validate, and test the model. The architecture was designed to simultaneously predict ventilation images and emphysema masks using paired inspiratory and expiratory VNC input images. DL-Vent demonstrated strong similarity to measured Xe-DECT ventilation images (Xe-Vent), with dice similarity coefficients of 0.56 for ventilation defects and 0.88 for ventilation regions. The ventilation defect percentages (VDP) of DL-Vent and Xe-Vent showed a high correlation (rs = 0.82), and both were similarly correlated with pulmonary function test results, including FEV1 (p = 0.71). Radiologists rated DL-Vent images as "fair to good" (mean score 3.9/5) and reliably differentiated defect patterns between COPD and ACOS (Cramer's V = 0.41, p = 0.03). The proposed model provides a promising alternative for functional lung imaging without requiring xenon administration.