Conference Paper

A rebinning-type backprojection-filtration algorithm for region of interest reconstruction in fan-beam CT with improved noise properties

Dept. of Radiol., Chicago Univ., IL, USA
DOI: 10.1109/NSSMIC.2005.1596893 Conference: Nuclear Science Symposium Conference Record, 2005 IEEE, Volume: 5
Source: IEEE Xplore


We propose an alternative backprojection-filtration(BPF)-based reconstruction algorithm for fan-beam CT, which reconstructs images by first converting the fan-beam data to fan-parallel-beam data and then using a modified parallel-beam BPF algorithm to obtain the reconstruction. This proposed algorithm retains the properties of the original fan-beam BPF algorithm in that it can reconstruct exact region of interest (ROI) images from truncated data and/or super-short-scan data. The major advantage of this algorithm is its improved noise properties because of the elimination of the spatially-variant weighting factor. In addition, the proposed algorithm is computationally more efficient.

5 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: In computed tomography (CT), the fan-beam filtered backprojection (FFBP) algorithm is used widely for image reconstruction. It is known that the FFBP algorithm can significantly amplify data noise and aliasing artifacts in situations where the focal lengths are comparable to or smaller than the size of the field of measurement (FOM). In this work, we propose an algorithm that is less susceptible to data noise, aliasing, and other data inconsistencies than is the FFBP algorithm while retaining the favorable resolution properties of the FFBP algorithm. In an attempt to evaluate the noise properties in reconstructed images, we derive analytic expressions for image variances obtained by use of the FFBP algorithm and the proposed algorithm. Computer simulation studies are conducted for quantitative evaluation of the spatial resolution and noise properties of images reconstructed by use of the algorithms. Numerical results of these studies confirm the favorable spatial resolution and noise properties of the proposed algorithm and verify the validity of the theoretically predicted image variances. The proposed algorithm and the derived analytic expressions for image variances can have practical implications for both estimation and detection/classification tasks making use of CT images, and they can readily be generalized to other fan-beam geometries.
    Medical Physics 05/2003; 30(4):590-600. DOI:10.1118/1.1556608 · 2.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Whether remote ischaemic preconditioning, an intervention in which brief ischaemia of one tissue or organ protects remote organs from a sustained episode of ischaemia, is beneficial for patients undergoing coronary artery bypass graft surgery is unknown. We did a single-blinded randomised controlled study to establish whether remote ischaemic preconditioning reduces myocardial injury in these patients. 57 adult patients undergoing elective coronary artery bypass graft surgery were randomly assigned to either a remote ischaemic preconditioning group (n=27) or to a control group (n=30) after induction of anaesthesia. Remote ischaemic preconditioning consisted of three 5-min cycles of right upper limb ischaemia, induced by an automated cuff-inflator placed on the upper arm and inflated to 200 mm Hg, with an intervening 5 min of reperfusion during which the cuff was deflated. Serum troponin-T concentration was measured before surgery and at 6, 12, 24, 48, and 72 h after surgery. Analysis was by intention to treat. This trial is registered with, number NCT00397163. Remote ischaemic preconditioning significantly reduced overall serum troponin-T release at 6, 12, 24, and 48 h after surgery. The total area under the curve was reduced by 43%, from 36.12 microg/L (SD 26.08) in the control group to 20.58 microg/L (9.58) in the remote ischaemic preconditioning group (mean difference 15.55 [SD 5.32]; 95% CI 4.88-26.21; p=0.005). We have shown that adult patients undergoing elective coronary artery bypass graft surgery at a single tertiary centre could benefit from remote ischaemic preconditioning, using transient upper limb ischaemia.
    The Lancet 09/2007; 370(9587):575-9. DOI:10.1016/S0140-6736(07)61296-3 · 45.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Myocyte necrosis as a result of elective percutaneous coronary intervention (PCI) occurs in approximately one third of cases and is associated with subsequent cardiovascular events. This study assessed the ability of remote ischemic preconditioning (IPC) to attenuate cardiac troponin I (cTnI) release after elective PCI. Two hundred forty-two consecutive patients undergoing elective PCI with undetectable preprocedural cTnI were recruited. Subjects were randomized to receive remote IPC (induced by three 5-minute inflations of a blood pressure cuff to 200 mm Hg around the upper arm, followed by 5-minute intervals of reperfusion) or control (an uninflated cuff around the arm) before arrival in the catheter laboratory. The primary outcome was cTnI at 24 hours after PCI. Secondary outcomes included renal dysfunction and major adverse cardiac and cerebral event rate at 6 months. The median cTnI at 24 hours after PCI was lower in the remote IPC compared with the control group (0.06 versus 0.16 ng/mL; P=0.040). After remote IPC, cTnI was <0.04 ng/mL in 44 patients (42%) compared with 24 in the control group (24%; P=0.01). Subjects who received remote IPC experienced less chest discomfort (P=0.0006) and ECG ST-segment deviation (P=0.005) than control subjects. At 6 months, the major adverse cardiac and cerebral event rate was lower in the remote IPC group (4 versus 13 events; P=0.018). Remote IPC reduces ischemic chest discomfort during PCI, attenuates procedure-related cTnI release, and appears to reduce subsequent cardiovascular events.
    Circulation 02/2009; 119(6):820-7. DOI:10.1161/CIRCULATIONAHA.108.809723 · 14.43 Impact Factor
Show more