Browsing by Author "Zhao, Xuandong"

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    A Comprehensive Set of Ultrashort Echo Time Magnetic Resonance Imaging Biomarkers to Assess Cortical Bone Health: A Feasibility Study at Clinical Field Strength
    (Elsevier, 2024) Jacobson, Andrea M.; Zhao, Xuandong; Sommer, Stefan; Sadik, Farhan; Warden, Stuart J.; Newman, Christopher; Siegmund, Thomas; Allen, Matthew R.; Surowiec, Rachel K.; Radiology and Imaging Sciences, School of Medicine
    Introduction: Conventional bone imaging methods primarily use X-ray techniques to assess bone mineral density (BMD), focusing exclusively on the mineral phase. This approach lacks information about the organic phase and bone water content, resulting in an incomplete evaluation of bone health. Recent research highlights the potential of ultrashort echo time magnetic resonance imaging (UTE MRI) to measure cortical porosity and estimate BMD based on signal intensity. UTE MRI also provides insights into bone water distribution and matrix organization, enabling a comprehensive bone assessment with a single imaging technique. Our study aimed to establish quantifiable UTE MRI-based biomarkers at clinical field strength to estimate BMD and microarchitecture while quantifying bound water content and matrix organization. Methods: Femoral bones from 11 cadaveric specimens (n = 4 males 67-92 yrs of age, n = 7 females 70-95 yrs of age) underwent dual-echo UTE MRI (3.0 T, 0.45 mm resolution) with different echo times and high resolution peripheral quantitative computed tomography (HR-pQCT) imaging (60.7 μm voxel size). Following registration, a 4.5 mm HR-pQCT region of interest was divided into four quadrants and used across the multi-modal images. Statistical analysis involved Pearson correlation between UTE MRI porosity index and a signal-intensity technique used to estimate BMD with corresponding HR-pQCT measures. UTE MRI was used to calculate T1 relaxation time and a novel bound water index (BWI), compared across subregions using repeated measures ANOVA. Results: The UTE MRI-derived porosity index and signal-intensity-based estimated BMD correlated with the HR-pQCT variables (porosity: r = 0.73, p = 0.006; BMD: r = 0.79, p = 0.002). However, these correlations varied in strength when we examined each of the four quadrants (subregions, r = 0.11-0.71). T1 relaxometry and the BWI exhibited variations across the four subregions, though these differences were not statistically significant. Notably, we observed a strong negative correlation between T1 relaxation time and the BWI (r = -0.87, p = 0.0006). Conclusion: UTE MRI shows promise for being an innocuous method for estimating cortical porosity and BMD parameters while also giving insight into bone hydration and matrix organization. This method offers the potential to equip clinicians with a more comprehensive array of imaging biomarkers to assess bone health without the need for invasive or ionizing procedures.
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    Design and Rationale for the Use of Magnetic Resonance Imaging Biomarkers to Predict Diabetes After Acute Pancreatitis in the Diabetes RElated to Acute Pancreatitis and Its Mechanisms Study: From the Type 1 Diabetes in Acute Pancreatitis Consortium
    (Wolters Kluwer, 2022) Tirkes, Temel; Chinchilli, Vernon M.; Bagci, Ulas; Parker, Jason G.; Zhao, Xuandong; Dasyam, Anil K.; Feranec, Nicholas; Grajo, Joseph R.; Shah, Zarine K.; Poullos, Peter D.; Spilseth, Benjamin; Zaheer, Atif; Xie, Karen L.; Wachsman, Ashley M.; Campbell-Thompson, Martha; Conwell, Darwin L.; Fogel, Evan L.; Forsmark, Christopher E.; Hart, Phil A.; Pandol, Stephen J.; Park, Walter G.; Pratley, Richard E.; Yazici, Cemal; Laughlin, Maren R.; Andersen, Dana K.; Serrano, Jose; Bellin, Melena D.; Yadav, Dhiraj; Type 1 Diabetes in Acute Pancreatitis Consortium (T1DAPC); Radiology and Imaging Sciences, School of Medicine
    This core component of the Diabetes RElated to Acute pancreatitis and its Mechanisms (DREAM) study will examine the hypothesis that advanced magnetic resonance imaging (MRI) techniques can reflect underlying pathophysiologic changes and provide imaging biomarkers that predict diabetes mellitus (DM) following acute pancreatitis (AP). A subset of participants in the DREAM study will enroll and undergo serial MRI examinations using a specific research protocol. We aim to differentiate at-risk individuals from those who remain euglycemic by identifying parenchymal features following AP. Performing longitudinal MRI will enable us to observe and understand the natural history of post-AP DM. We will compare MRI parameters obtained by interrogating tissue properties in euglycemic, prediabetic and incident diabetes subjects and correlate them with metabolic, genetic, and immunological phenotypes. Differentiating imaging parameters will be combined to develop a quantitative composite risk score. This composite risk score will potentially have the ability to monitor the risk of DM in clinical practice or trials. We will use artificial intelligence, specifically deep learning, algorithms to optimize the predictive ability of MRI. In addition to the research MRI, the DREAM study will also correlate clinical computerized tomography and MRI scans with DM development.
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    Diagnosis of chronic pancreatitis using semi-quantitative MRI features of the pancreatic parenchyma: results from the multi-institutional MINIMAP study Temel Tirkes1,18, Dhiraj Yadav2
    (Springer, 2023) Tirkes, Temel; Yadav, Dhiraj; Conwell, Darwin L.; Territo, Paul R.; Zhao, Xuandong; Persohn, Scott A.; Dasyam, Anil K.; Shah, Zarine K.; Venkatesh, Sudhakar K.; Takahashi, Naoki; Wachsman, Ashley; Li, Liang; Li, Yan; Pandol, Stephen J.; Park, Walter G.; Swaroop Vege, Santhi; Hart, Phil A.; Topazian, Mark; Andersen, Dana K.; Fogel, Evan L.; Consortium for the Study of Chronic Pancreatitis, Diabetes, Pancreatic Cancer (CPDPC); Radiology and Imaging Sciences, School of Medicine
    Purpose: To determine the diagnostic performance of parenchymal MRI features differentiating CP from controls. Methods: This prospective study performed abdominal MRI scans at seven institutions, using 1.5 T Siemens and GE scanners, in 50 control and 51 definite CP participants, from February 2019 to May 2021. MRI parameters included the T1-weighted signal intensity ratio of the pancreas (T1 score), arterial-to-venous enhancement ratio (AVR) during venous and delayed phases, pancreas volume, and diameter. We evaluated the diagnostic performance of these parameters individually and two semi-quantitative MRI scores derived using logistic regression: SQ-MRI Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume). Results: When compared to controls, CP participants showed a significantly lower mean T1 score (1.11 vs. 1.29), AVR venous (0.86 vs. 1.45), AVR delayed (1.07 vs. 1.57), volume (54.97 vs. 80.00 ml), and diameter of the head (2.05 vs. 2.39 cm), body (2.25 vs. 2.58 cm), and tail (1.98 vs. 2.51 cm) (p < 0.05 for all). AUCs for these individual MR parameters ranged from 0.66 to 0.79, while AUCs for the SQ-MRI scores were 0.82 and 0.81 for Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume), respectively. After propensity-matching adjustments for covariates, AUCs for Models A and B of the SQ-MRI scores increased to 0.92 and 0.93, respectively. Conclusion: Semi-quantitative parameters of the pancreatic parenchyma, including T1 score, enhancement ratio, pancreas volume, diameter and multi-parametric models combining these parameters are helpful in diagnosis of CP. Longitudinal analyses including more extensive population are warranted to develop new diagnostic criteria for CP.
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    Evaluation of variable flip angle, MOLLI, SASHA, and IR-SNAPSHOT pulse sequences for T1 relaxometry and extracellular volume imaging of the pancreas and liver
    (Elsevier, 2019-06-04) Tirkes, Temel; Zhao, Xuandong; Lin, Chen; Stuckey, Alex Jordan; Li, Liang; Giri, Shivriman; Nickel, Dominik; Radiology and Imaging Sciences, School of Medicine
    Purpose Compare four T1 mapping pulse sequences for T1 relaxometry and extracellular volume (ECV) fraction of the pancreas and liver Materials and Methods In vitro phase of this prospective study was performed on a T1 phantom, followed by imaging twenty-two patients. Variable flip angle (VFA), modified Look-Locker inversion recovery (MOLLI), prototype saturation recovery single-shot acquisition (SASHA), and prototype inversion recovery (IR-SNAPSHOT) pulse sequences were used to obtain T1 and ECV maps on the same 1.5T MR scanner using the same imaging protocol. Results In vitro tests showed almost perfect precision of MOLLI (ρc=0.9998), SASHA (ρc=0.9985) and IR-SNAPSHOT (ρc=0.9976) while VFA showed relatively less, however substantial precision (ρc=0.9862). Results of patient scans showed similar ECV fraction of the liver (p=0.08), pancreas (p=0.43), and T1 of the liver (p=0.08) with all pulse sequences. T1 of the pancreas with MOLLI, SASHA and IR-SNAPSHOT were statistically similar (p>0.05). Conclusion MOLLI, SASHA and IR-SNAPSHOT provided almost perfect in vitro precision and similar T1 during in vivo scans. Similar ECV fractions of the liver and pancreas were obtained with all sequences. More refinement of pulse sequences to provide sufficient spatial coverage in one breath hold together with high precision would be desirable in abdominal imaging.
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    Magnetic resonance imaging as a non-invasive method for the assessment of pancreatic fibrosis (MINIMAP): a comprehensive study design from the consortium for the study of chronic pancreatitis, diabetes, and pancreatic cancer
    (Springer, 2019-05-14) Tirkes, Temel; Yadav, Dhiraj; Conwell, Darwin L.; Territo, Paul R.; Zhao, Xuandong; Venkatesh, Sudhakar K.; Kolipaka, Arunark; Li, Liang; Pisegna, Joseph R.; Pandol, Stephen J.; Park, Walter G.; Topazian, Mark; Serrano, Jose; Fogel, Evan L.; Radiology and Imaging Sciences, School of Medicine
    Characteristic features of chronic pancreatitis (CP) may be absent on standard imaging studies. Quantitative Magnetic Resonance Imaging (MRI) techniques such as T1 mapping, extracellular volume (ECV) fraction, diffusion-weighted imaging (DWI) with apparent diffusion coefficient map (ADC), MR elastography (MRE), and T1-weighted signal intensity ratio (SIR) have shown promise for the diagnosis and grading severity of CP. However, radiologists still use the Cambridge classification which is based on traditional ductal imaging alone. There is an urgent need to develop new diagnostic criteria that incorporate both parenchymal and ductal features of CP seen by MRI/MRCP. Designed to fulfill this clinical need, we present the MINIMAP study, which was funded in September 2018 by the National Institutes of Health. This is a comprehensive quantitative MR imaging study which will be performed at multiple institutions in well-phenotyped CP patient cohorts. We hypothesize that quantitative MRI/MRCP features can serve as valuable non-invasive imaging biomarkers to detect and grade CP. We will evaluate the role of T1 relaxometry, ECV, T1-weighted gradient echo SIR, MRE, arteriovenous enhancement ratio, ADC, pancreas volume/atrophy, pancreatic fat fraction, ductal features, and pancreatic exocrine output following secretin stimulation in the assessment of CP. We will attempt to generate a multi-parametric pancreatic tissue fibrosis (PTF) scoring system. We anticipate that a quantitative scoring system may serve as a biomarker of pancreatic fibrosis; hence this imaging technique can be used in clinical practice as well as clinical trials to evaluate the efficacy of agents which may slow the progression or reverse measures of CP.
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    Multiparametric MRI Scoring System of the Pancreas for the Diagnosis of Chronic Pancreatitis
    (Wiley, 2025) Tirkes, Temel; Yadav, Dhiraj; Conwell, Darwin L.; Zhao, Xuandong; Dasyam, Anil K.; Halappa, Vivek Gowdra; Patel, Aashish; Shah, Zarine K.; Swensson, Jordan; Takahashi, Naoki; Venkatesh, Sudhakar; Wachsman, Ashley; Li, Liang; Jennings, Kristofer; Yang, Yunlong; Hart, Phil A.; Pandol, Stephen J.; Park, Walter G.; Vege, Santhi Swaroop; Topazian, Mark; Territo, Paul R.; Persohn, Scott A.; Andersen, Dana K.; Fogel, Evan L.; Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC); Radiology and Imaging Sciences, School of Medicine
    Background: Ductal features alone may not offer high diagnostic sensitivity or most accurate disease severity of chronic pancreatitis (CP). Purpose: Diagnose CP based on multiparametric MRI and MRCP features. Study type: Prospective. Population: Between February 2019 and May 2021, 46 control (23 males, 49.3 ± 14.1 years), 45 suspected (20 males, 48.7 ± 12.5 years), and 46 definite (20 males, 53.7 ± 14.6 years) CP patients were enrolled at seven hospitals enrolled in the MINIMAP study. CP classification was based on imaging findings and clinical presentation. Field strength and sequences: 1.5 T. T1-weighted (T1W) spoiled gradient echo, T1 map with variable flip angle, dual-echo Dixon, secretin-enhanced MRCP before and after secretin infusion. Assessment: Dual-echo fat fraction (FF), T1 relaxation time, extracellular volume (ECV), T1 signal intensity ratio of the pancreas to the spleen (T1 score), arterial-to-venous enhancement ratio (AVR), pancreatic tail diameter (PTD), pancreas volume, late gadolinium enhancement, pancreatic ductal elasticity (PDE), and duodenal filling grade of secretin-enhanced MRCP were measured. Statistical tests: Logistic regression analysis generated CP-MRI and secretin-enhanced CP-SMRI scores. Receiver operating characteristics analysis was used to differentiate definite CP from control. Interobserver agreement was assessed using Lin's concordance correlation coefficient. Results: Compared to control, definite CP cohort showed significantly higher dual-echo FF (7% vs. 11%), lower AVR (1.35 vs. 0.85), smaller PTD (2.5 cm vs. 1.95 cm), higher ECV (28% vs. 38%), and higher incidence of PDE loss (6.5% vs. 50%). With the cut-off of >2.5 CP-MRI score (dual-echo FF, AVR, and PTD) and CP-SMRI score (dual-echo FF, AVR, PTD, and PDE) had cross-validated area under the curves of 0.84 (sensitivity 87%, specificity 68%) and 0.86 (sensitivity 89%, specificity 67%), respectively. Interobserver agreement for both CP-MRI and CP-SMRI scores was 0.74. Conclusion: The CP-MRI and CP-SMRI scores yielded acceptable performance and interobserver agreement for the diagnosis of CP.
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    Normal T1 relaxometry and extracellular volume of the pancreas in subjects with no pancreas disease: correlation with age and gender
    (Springer, 2019-05-28) Tirkes, Temel; Mitchell, Jacob R.; Li, Liang; Zhao, Xuandong; Lin, Chen; Radiology and Imaging Sciences, School of Medicine
    OBJECTIVE Determine normal T1 and extracellular volume (ECV) of the pancreas in subjects with no pancreas disease and correlate with age and gender SUBJECTS AND METHODS We imaged 120 healthy subjects (age range: 20-78 years) who are on annual screening with MRI/MRCP for the possibility of pancreatic cancer. Subjects had a predisposition to develop pancreatic cancer, but no history of pancreas disease or acute symptoms. Equal number (n=60) of subjects were scanned on either 1.5 T or 3 T scanner using dual flip angle spoiled gradient echo technique incorporating fat suppression and correction for B1 field inhomogeneity. Optimization of imaging parameters were performed using a T1 phantom. ECV was calculated using pre- and post-contrast T1 of the pancreas and plasma. Regression analysis and Mann-Whitney tests were used for statistical analysis. RESULTS Median T1 on 1.5 T was 654 ms (IQR: 608-700); median T1 on 3 T was 717 ms (IQR: 582-850); median ECV on 1.5 T was 0.28 (IQR: 0.21-0.33) and median ECV on 3 T was 0.25 (IQR: 0.19-0.28). Age had a mild positive correlation with T1 (r= 0.24, p= 0.009), but not with ECV (r= 0.06, p=0.54). T1 and ECV were similar in both genders (p >0.05). CONCLUSION This study measured the median T1 and ECV of the pancreas in subjects with no pancreas disease. Pancreas shows longer T1 relaxation times in older population, whereas extracellular fraction remains unchanged. Median T1 values were different between two magnet strengths; however, no difference was seen between genders and ECV fractions.
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    Performance evaluation of two interventional fluoroscope suites for cardiovascular imaging
    (Wiley, 2022) Anthony, Gregory; Liang, Yun; Zhao, Xuandong; Radiology and Imaging Sciences, School of Medicine
    Interventional cardiology involves catheter-based treatment of heart disease, generally through fluoroscopically guided interventional procedures. Patients can be subject to considerable radiation dose due to prolonged fluoroscopy time and radiographic exposure, and therefore efforts to minimize patient dose should always be undertaken. Developing standardized, effective quality control programs for these systems is a difficult task owing to cross-vendor differences and automated control of imaging protocols. Furthermore, analyses of radiation dose should be performed in the context of its associated effects on image quality. The aim of the study is to investigate radiation dose and image quality in two fluoroscopic systems used for interventional cardiology procedures. Image quality was assessed in terms of spatial resolution and modulation transfer function, signal-to-noise and contrast-to-noise ratios, and spatial-temporal resolution of fluoroscopy and cineradiography images with phantoms simulating various patient thicknesses under routine cardiology protocols. The entrance air kerma (or air kerma rate) was measured and used to estimate entrance surface dose (or dose rate) in the phantoms.
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    Quantitative MRI of chronic pancreatitis: results from a multi-institutional prospective study, magnetic resonance imaging as a non-invasive method for assessment of pancreatic fibrosis (MINIMAP)
    (Springer Nature, 2022) Tirkes, Temel; Yadav, Dhiraj; Conwell, Darwin L.; Territo, Paul R.; Zhao, Xuandong; Persohn, Scott A.; Dasyam, Anil K.; Shah, Zarine K.; Venkatesh, Sudhakar K.; Takahashi, Naoki; Wachsman, Ashley; Li, Liang; Li, Yan; Pandol, Stephen J.; Park, Walter G.; Vege, Santhi S.; Hart, Phil A.; Topazian, Mark; Andersen, Dana K.; Fogel, Evan L.; Consortium for the Study of Chronic Pancreatitis, Diabetes, Pancreatic Cancer (CPDPC); Radiology and Imaging Sciences, School of Medicine
    Purpose: To determine if quantitative MRI techniques can be helpful to evaluate chronic pancreatitis (CP) in a setting of multi-institutional study. Methods: This study included a subgroup of participants (n = 101) enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study (NCT03099850) from February 2019 to May 2021. MRI was performed on 1.5 T using Siemens and GE scanners at seven clinical centers across the USA. Quantitative MRI parameters of the pancreas included T1 relaxation time, extracellular volume (ECV) fraction, apparent diffusion coefficient (ADC), and fat signal fraction. We report the diagnostic performance and mean values within the control (n = 50) and CP (n = 51) groups. The T1, ECV and fat signal fraction were combined to generate the quantitative MRI score (Q-MRI). Results: There was significantly higher T1 relaxation time; mean 669 ms (± 171) vs. 593 ms (± 82) (p = 0.006), ECV fraction; 40.2% (± 14.7) vs. 30.3% (± 11.9) (p < 0.001), and pancreatic fat signal fraction; 12.2% (± 5.5) vs. 8.2% (± 4.4) (p < 0.001) in the CP group compared to controls. The ADC was similar between groups (p = 0.45). The AUCs for the T1, ECV, and pancreatic fat signal fraction were 0.62, 0.72, and 0.73, respectively. The composite Q-MRI score improved the diagnostic performance (cross-validated AUC: 0.76). Conclusion: Quantitative MR parameters evaluating the pancreatic parenchyma (T1, ECV fraction, and fat signal fraction) are helpful in the diagnosis of CP. A Q-MRI score that combines these three MR parameters improves diagnostic performance. Further studies are warranted with larger study populations including patients with acute and recurrent acute pancreatitis and longitudinal follow-ups.