Authors : F. Usman, R. Zainon, H. Mohammed, K.J. Nizam and B.W. Gbolahan
Abstract: This research is aimed at evaluating the effect of incorporating OSEM and FBP reconstructed liver SPECT/CT with a modeled CAD system in the management of liver tumors and other radiation induced liver diseases. An Anthropomorphic torso phantom with lung and liver inserts was injected with 99mTc. The liver and the background were given 0.2 and 0.07 Mbq mL–1, respectively. The lungs inserts were filled with polystyrene beads for humanisation. A mimicked 30 mL tumour (27 mm) in the liver insert was given 2 Mbq mL–1. Sequential SPECT (step and shot, 10 min over 1800 per head) and CT (120 kVp, 80 mAs) projections were acquired using dual head SPECT/16 slice CT system. The projections were reconstructed using OSEM (10 subsets for 2-10 numbers of iterations, Butterworth post filtering, 10 orders and 0.48 frequencies) and FBP (using Butterworth post filtering at 10 order and cut-off frequencies of 0.38-0.58, 0.05 gaps). Segmented and non-segmented SPECT/CT data were obtained. The image j Software made the analysis. Statistical t-test tested the mean grey values of the tumour and its background. The OSEM and FBP reconstructed images were evaluated from their Contrast to Noise Ratio (CNR). The detection ability was evaluated based on 3-5 CNR detection range set by the rose criterion. The t-test showed the background and the tumour’s mean values to be statistically significant (p[<]0.05). The CNR values for both modeled and non-modeled CAD FBP images were all under the detection range. Nevertheless, the maximum CNR value was noted at the cutoff frequency 0.48 (1.69). In OSEM reconstructed images, the peak was observed at around 3-4 numbers of iterations. In accession, its modeled CAD based evaluation gave CNR values within the detection range from 2-8 numbers of iteration with maximum value (4.89) at 4 numbers of iteration. While the detection range was unattainable for the non-modeled CAD OSEM reconstructed liver SPECT/CT. CAD improves liver tumour detection in SPECT/CT imaging. OSEM is the best for tumour detection. In addition, administered activity can be brought down at 4 OSEM’s of iterations (40 MLEM iterations) for patient safety. Ultimately, well developed CAD systems are recommended for proper management of liver and its other related abnormalities.
F. Usman, R. Zainon, H. Mohammed, K.J. Nizam and B.W. Gbolahan, 2020. CAD SPECT/CT in Managing Liver Tumours and Other Related Abnormalities. Surgery Journal, 15: 1-9.