Yanqiu Feng

Publications (9)26.94 Total impact

• Article: In vivo comparison of myocardial T1 with T2 and T2* in thalassaemia major.

  Yanqiu Feng, Taigang He, John-Paul Carpenter, Andrew Jabbour, Mohammed Harith Alam, Peter D Gatehouse, Andreas Greiser, Daniel Messroghli, David N Firmin, Dudley J Pennell
  [show abstract] [hide abstract]
  ABSTRACT: PURPOSE: To compare myocardial T1 against T2 and T2* in patients with thalassemia major (TM) for myocardial iron characterization. MATERIALS AND METHODS: A total of 106 TM patients (29 ± 10 years; 58 males) were studied on a 1.5 Tesla scanner using dedicated T1, T2*, and T2 relaxometry sequences. A single mid-ventricular short axis slice was acquired within a breath-hold. RESULTS: In patients with myocardial iron overload (T2* < 20 ms; n = 52), there were linear correlations between T2 and T2* (r = 0.82; P = 0.0), and between T1 and T2* (r = 0.83; P = 0.0). In patients with no myocardial iron (n = 54), T2* values were scattered with no significant correlation against T2 or T1. For all patients (n = 106) there was a strong linear correlation (r = 0.93; P = 0.0) between myocardial T1 and T2. CONCLUSION: In patients with iron overload, myocardial T2 and T1 are correlated with T2*. In patients with low or normal myocardial iron concentration, other factors become dominant in affecting T2* values as shown by scattered T2* data. Myocardial T1 correlates linearly with T2 measurements in all patients suggesting that these two relaxation parameters avoid extrinsic magnetic field inhomogeneity effects and may potentially provide improved myocardial tissue characterization. J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
  Journal of Magnetic Resonance Imaging 01/2013; · 2.70 Impact Factor
• Article: Improved MRI R(2) * relaxometry of iron-loaded liver with noise correction.

  Yanqiu Feng, Taigang He, Peter D Gatehouse, Xinzhong Li, Mohammed Harith Alam, Dudley J Pennell, Wufan Chen, David N Firmin
  [show abstract] [hide abstract]
  ABSTRACT: Accurate and reproducible MRI R(2) * relaxometry for tissue iron quantification is important in managing transfusion-dependent patients. MRI data are often acquired using array coils and reconstructed by the root-sum-square algorithm, and as such, measured signals follow the noncentral chi distribution. In this study, two noise-corrected models were proposed for the liver R(2) * quantification: fitting the signal to the first moment and fitting the squared signal to the second moment in the presence of the noncentral chi noise. These two models were compared with the widely implemented offset and truncation models on both simulation and in vivo data. The results demonstrated that the "slow decay component" of the liver R(2) * was mainly caused by the noise. The offset model considerably overestimated R(2) * values by incorrectly adding a constant to account for the slow decay component. The truncation model generally produced accurate R(2) * measurements by only fitting the initial data well above the noise level to remove the major source of errors, but underestimated very high R(2) * values due to the sequence limit of obtaining very short echo time images. Both the first and second-moment noise-corrected models constantly produced accurate and precise R(2) * measurements by correctly addressing the noise problem. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
  Magnetic Resonance in Medicine 01/2013; · 2.96 Impact Factor
• Article: Automated truncation method for myocardial T2* measurement in thalassemia.

  Taigang He, Jun Zhang, John-Paul Carpenter, Yanqiu Feng, Gillian C Smith, Dudley J Pennell, David N Firmin
  [show abstract] [hide abstract]
  ABSTRACT: PURPOSE: To propose an automated truncation method for myocardial T2* measurement and evaluate this method on a large population of patients with iron loading in the heart and scanned at multiple magnetic resonance imaging (MRI) centers. MATERIALS AND METHODS: A total of 550 thalassemia patients were scanned at 20 international centers using a variety of MR scanners (Siemens, Philips, or GE). A single mid-ventricular short axis slice was imaged. All patient data were anonymized before the T2* were measured by expert observers using standard techniques. These same datasets were then retrospectively processed using the proposed automated truncation method by another independent observer and the resulting T2* measurements were compared with those of expert readings. RESULTS: The T2* measurements using the automated method showed good agreement with those measured by expert observers using standard techniques (P = 0.95) with a low coefficient of variation (1.6%). CONCLUSION: This study demonstrates feasibility and good reproducibility of a new automated truncation method for myocardial T2* measurement. This approach simplifies the overall analysis and can be easily incorporated into T2* analysis software to facilitate further development of a fully automated myocardial tissue iron quantification. J. Magn. Reson. Imaging 2012;. © 2012 Wiley Periodicals, Inc.
  Journal of Magnetic Resonance Imaging 08/2012; · 2.70 Impact Factor
• Article: Cardiovascular magnetic resonance T2 mapping detects myocardial edema in patients with chronic dilated cardiomyopathy.

  Taigang He, Ankur Gulati, Andrew Jabbour, Tevfik F Ismail, Yanqiu Feng, Nizar Ismail, Carla Gonçalves, Tristan Brown, David N Firmin, Sanjay K Prasad, Dudley J Pennell
  Journal of Cardiovascular Magnetic Resonance 02/2012; 14 Suppl 1:O29. · 3.72 Impact Factor
• Article: Potential of pre-contrast T1 mapping as a marker of interstitial fibrosis in severe aortic stenosis.

  Andrew Jabbour, Tevfik F Ismail, Callum Ettles, Carl Shakespeare, Sameer Zaman, Oluwatosin Sotubo, Saman S Zaman, Benjamin Hewins, Rick Wage, Ankur Gulati, Pedro F Ferreira, Pierre Croisille, Yanqiu Feng, Raad H Mohiaddin, Taigang He, John Pepper, David N Firmin, Dudley J Pennell, Mario Petrou, Sanjay K Prasad
  Journal of Cardiovascular Magnetic Resonance 02/2012; 14 Suppl 1:O72. · 3.72 Impact Factor
• Article: Non-invasive assessment of interstitial myocardial fibrosis in pressure-overload left ventricular hypertrophy.

  Andrew Jabbour, Tevfik F Ismail, Sofia V De Noronha, Carl Shakespeare, Sameer Zaman, Oluwatosin Sotubo, Saman S Zaman, Callum Ettles, Benjamin Hewins, Rick Wage, [......], Yanqiu Feng, Katsuya Norita, Raad H Mohiaddin, Taigang He, John Pepper, David N Firmin, Mary Sheppard, Dudley J Pennell, Mario Petrou, Sanjay K Prasad
  Journal of Cardiovascular Magnetic Resonance 02/2012; 14 Suppl 1:O5. · 3.72 Impact Factor
• Article: On optimal liver T2* measurement: region of interest or pixel-wise?

  Yanqiu Feng, Peter D Gatehouse, Peiguo Liu, John-Paul Carpenter, Dudley J Pennell, David N Firmin, Wufan Chen, Taigang He
  Journal of Cardiovascular Magnetic Resonance 02/2012; 14 Suppl 1:P293. · 3.72 Impact Factor
• Article: Determine the myocardial T2* cut-off value in thalassemia using gaussian mixtures models.

  Taigang He, Rong R Liu, Yanqiu Feng, John-Paul Carpenter, Yongrong Lai, Dudley J Pennell, David N Firmin
  Journal of Cardiovascular Magnetic Resonance 02/2012; 14 Suppl 1:O77. · 3.72 Impact Factor
• Article: [Low-dose CT perfusion imaging based on pre-scan regulation and on reconstruction with sparsity constraints].

  Jijiang Mo, Aizhen Zhou, Cong Wang, Yingjie Mei, Yanqiu Feng
  [show abstract] [hide abstract]
  ABSTRACT: The long-period CT perfusion imaging leads to an excess amount of radiation dose to the patient. However, the radiation dose could be significantly reduced if a previous normal-dose image is acquired before a set of low-dose scans of perfusion, and a filtering processing is performed on the differences between the current low-dose images and the previous normal-dose image, then the results are added to the previous image. But the selection of plenty of parameters makes the algorithm complicated. This paper proposes an innovative approach performed in sinogram domain instead of in image domain. First a normal-dose image and a set of low-dose projection data are acquired before the perfusion. Second the perfusion information is commendably reconstructed with sparsity constraints of the differences between current low-dose perfusion sinograms and previous low-dose sinogram. Finally, the reconstructed perfusion information is added to the previous normal-dose image. The proposed method was validated by simulated experiments with a set of brain CT perfusion images, which showed that the new method provided more accurate perfusion information; the time-attenuation curve was more close to that for normal-dose scan and the mean transit time more repeatable.
  Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi 02/2012; 29(1):12-7.