scholarly journals Pengaruh Jumlah Iterasi dan Nilai Parameter Relaksasi Terhadap Signal to Noise Ratio (SNR) pada Rekonstruksi Citra Metode SIRT (Halaman 13 s.d. 16)

2014 ◽  
Vol 17 (51) ◽  
Author(s):  
Choirul Anam ◽  
Catur Edi Widodo
Keyword(s):  
Iterative Reconstruction ◽  
Signal To Noise Ratio ◽  
Reconstruction Technique ◽  
Signal To Noise ◽  
Iterative Reconstruction Technique ◽  
Noise Ratio ◽  
Simultaneous Iterative Reconstruction Technique

Kualitas citra hasil rekonstruksi metode Simultaneous Iterative Reconstruction Technique (SIRT) ditentukan oleh jumlah iterasi dan nilai parameter relaksasi (λ). Nilai λ ini biasanya diperoleh secara coba-coba. Penelitian ini bertujuan mengevaluasi pengaruh jumlah iterasi dan nilai λ terhadap nilai signal to noise ratio (SNR). Rekonstruksi menggunakan obyek fantom Shepp-Logan ukuran 50x50. Proyeksi dilakukan untuk setiap sudut 100menggunakan mode berkas paralel. Pertama ditentukan pengaruh jumlah iterasi terhadap SNR. Selanjutnya dilakukan penentuan nilai SNR untuk variasi  λ  pada jumlah iterasi tertentu. Diperoleh bahwa semakin banyak iterasi dan semakin besar nilai parameter relaksasi menghasilkan nilai SNR semakin tinggi, namun setelah iterasi dan nilai λ tertentu, nilai SNR mengalami saturasi. Citra dengan kualitas optimal (kekaburan dan stripping paling kecil), diperoleh pada iterasi antara 5 hingga 10 dan nilai parameter relaksasi antara 0,5 hingga 1.

scholarly journals Pengaruh Jumlah Iterasi dan Nilai Parameter Relaksasi Terhadap Signal to Noise Ratio (SNR) pada Rekonstruksi Citra Metode SIRT (Halaman 13 s.d. 16)

2014 ◽  
Vol 17 (51) ◽  
Author(s):  
Choirul Anam ◽  
Catur Edi Widodo
Keyword(s):  
Iterative Reconstruction ◽  
Signal To Noise Ratio ◽  
Reconstruction Technique ◽  
Signal To Noise ◽  
Iterative Reconstruction Technique ◽  
Noise Ratio ◽  
Simultaneous Iterative Reconstruction Technique

Kualitas citra hasil rekonstruksi metode Simultaneous Iterative Reconstruction Technique (SIRT) ditentukan oleh jumlah iterasi dan nilai parameter relaksasi (λ). Nilai λ ini biasanya diperoleh secara coba-coba. Penelitian ini bertujuan mengevaluasi pengaruh jumlah iterasi dan nilai λ terhadap nilai signal to noise ratio (SNR). Rekonstruksi menggunakan obyek fantom Shepp-Logan ukuran 50x50. Proyeksi dilakukan untuk setiap sudut 100menggunakan mode berkas paralel. Pertama ditentukan pengaruh jumlah iterasi terhadap SNR. Selanjutnya dilakukan penentuan nilai SNR untuk variasi  λ  pada jumlah iterasi tertentu. Diperoleh bahwa semakin banyak iterasi dan semakin besar nilai parameter relaksasi menghasilkan nilai SNR semakin tinggi, namun setelah iterasi dan nilai λ tertentu, nilai SNR mengalami saturasi. Citra dengan kualitas optimal (kekaburan dan stripping paling kecil), diperoleh pada iterasi antara 5 hingga 10 dan nilai parameter relaksasi antara 0,5 hingga 1.

Model-based reconstruction algorithm in the detection of acute trauma-related lesions in brain CT examinations

2021 ◽  
pp. 197140092110087
Author(s):  
Andrea De Vito ◽  
Cesare Maino ◽  
Sophie Lombardi ◽  
Maria Ragusi ◽  
Cammillo Talei Franzesi ◽  
...  
Keyword(s):  
Image Quality ◽  
Iterative Reconstruction ◽  
Signal To Noise Ratio ◽  
Reconstruction Algorithm ◽  
Signal To Noise ◽  
Subjective Image Quality ◽  
Model Based ◽  
Hybrid Iterative Reconstruction ◽  
Noise Ratio ◽  
Enhanced Computed Tomography

Background and purpose To evaluate the added value of a model-based reconstruction algorithm in the assessment of acute traumatic brain lesions in emergency non-enhanced computed tomography, in comparison with a standard hybrid iterative reconstruction approach. Materials and methods We retrospectively evaluated a total of 350 patients who underwent a 256-row non-enhanced computed tomography scan at the emergency department for brain trauma. Images were reconstructed both with hybrid and model-based iterative algorithm. Two radiologists, blinded to clinical data, recorded the presence, nature, number, and location of acute findings. Subjective image quality was performed using a 4-point scale. Objective image quality was determined by computing the signal-to-noise ratio and contrast-to-noise ratio. The agreement between the two readers was evaluated using k-statistics. Results A subjective image quality analysis using model-based iterative reconstruction gave a higher detection rate of acute trauma-related lesions in comparison to hybrid iterative reconstruction (extradural haematomas 116 vs. 68, subdural haemorrhages 162 vs. 98, subarachnoid haemorrhages 118 vs. 78, parenchymal haemorrhages 94 vs. 64, contusive lesions 36 vs. 28, diffuse axonal injuries 75 vs. 31; all P<0.001). Inter-observer agreement was moderate to excellent in evaluating all injuries (extradural haematomas k=0.79, subdural haemorrhages k=0.82, subarachnoid haemorrhages k=0.91, parenchymal haemorrhages k=0.98, contusive lesions k=0.88, diffuse axonal injuries k=0.70). Quantitatively, the mean standard deviation of the thalamus on model-based iterative reconstruction images was lower in comparison to hybrid iterative one (2.12 ± 0.92 vsa 3.52 ± 1.10; P=0.030) while the contrast-to-noise ratio and signal-to-noise ratio were significantly higher (contrast-to-noise ratio 3.06 ± 0.55 vs. 1.55 ± 0.68, signal-to-noise ratio 14.51 ± 1.78 vs. 8.62 ± 1.88; P<0.0001). Median subjective image quality values for model-based iterative reconstruction were significantly higher ( P=0.003). Conclusion Model-based iterative reconstruction, offering a higher image quality at a thinner slice, allowed the identification of a higher number of acute traumatic lesions than hybrid iterative reconstruction, with a significant reduction of noise.

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