Publications by authors named "Mohamad Aminudin Said"

2 Publications

  • Page 1 of 1

The quantification of PET-CT radiotracers to determine minimal scan time using quadratic formulation.

Ann Nucl Med 2020 Dec 3;34(12):884-891. Epub 2020 Nov 3.

School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia.

Objective: F is the most extensively used radioisotope in current clinical practices of PET imaging. This selection is based on the several criteria of pure PET radioisotopes with an optimum half-life, and low positron energy that contributes to a smaller positron range. In addition to F, other radioisotopes such as Ga and I are currently gained much attention with the increase in interest in new PET tracers entering the clinical trials. This study aims to determine the minimal scan time per bed position (T) for the I and Ga based on the quantitative differences in PET imaging of Ga and I relative to F.

Methods: The European Association of Nuclear Medicine (EANM) procedure guidelines version 2.0 for FDG-PET tumor imaging has adhered for this purpose. A NEMA2012/IEC2008 phantom was filled with tumor to background ratio of 10:1 with the activity concentration of 30 kBq/ml ± 10 and 3 kBq/ml ± 10% for each radioisotope. The phantom was scanned using different acquisition times per bed position (1, 5, 7, 10 and 15 min) to determine the T. The definition of T was performed using an image coefficient of variations (COV) of 15%.

Results: T obtained for F, Ga and I were 3.08, 3.24 and 32.93 min, respectively. Quantitative analyses among F, Ga and I images were performed. Signal-to-noise ratio (SNR), contrast recovery coefficients (CRC), and visibility (V) are the image quality parameters analysed in this study. Generally, Ga and F gave better image quality as compared to I for all the parameters studied.

Conclusion: We have defined T for F, Ga and I SPECT CT imaging based on NEMA2012/IEC2008 phantom imaging. Despite the long scanning time suggested by T, improvement in the image quality is acquired especially for I. In clinical practice, the long acquisition time, nevertheless, may cause patient discomfort and motion artifact.
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December 2020

Maximum standardized uptake value from quantitative bone single-photon emission computed tomography/computed tomography in differentiating metastatic and degenerative joint disease of the spine in prostate cancer patients.

Ann Nucl Med 2020 Jan 14;34(1):39-48. Epub 2019 Oct 14.

Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Penang, Malaysia.

Objective: Qualitative interpretation in bone scan is often complicated by the presence of degenerative joint disease (DJD), especially in the elderly patient. The aim of this study is to compare objectively Tc-MDP tracer uptake between DJD and osseous metastases of the spine using semi-quantitative assessment with SPECT SUV.

Methods: Bone scan with SPECT/CT using Tc-MDP was performed in 34 patients diagnosed with prostate carcinoma. SPECT/CT was performed based on our institutional standard guidelines. SUV based on body weight in 238 normal vertebrae visualized on SPECT/CT was quantified as baseline. A total of 211 lesions in the spine were identified on bone scan. Lesions were characterized into DJD or bone metastases based on its morphology on low-dose CT. Semi-quantitative evaluation using SUV was then performed on 89 DJD and 122 metastatic bone lesions. As most of the bone lesions were small in volume, the effect of partial volume effect (PVE) on SUV was also assessed. The corrected SUV values were obtained based on the recovery coefficient (RC) method.

Results: The mean SUV for normal vertebrae was 7.08 ± 1.97, 12.59 ± 9.01 for DJD and 36.64 ± 24.84 for bone metastases. The SUV of bone metastases was significantly greater than DJD (p value < 0.05). To assess for diagnostic accuracy, receiver operating characteristic (ROC) curve was performed. The area under the curve (AUC) was found to be fairly high at 0.874 (95% CI 0.826-0.921). The cutoff SUV value ≥ 20 gave a sensitivity of 73.8% and specificity of 85.4% in differentiating bone metastases from DJD. The corrected SUV for both DJD and bone metastases was smaller with a mean of 6.82 ± 6.02 and 24.77 ± 20.61, respectively. The cutoff SUV value was also lower with a value of 10, which gave a sensitivity of 73.8% and specificity of 86.5%.

Conclusion: SPECT SUV was significantly higher in bone metastases than DJD. Semi-quantitative assessment with SUV can complement qualitative analysis. A cutoff SUV of ≥ 20 can be used to differentiate bone metastases from DJD. Partial volume effect should be taken into consideration in the quantification of small lesion size.
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January 2020