There are two dosing methods for radioiodine dose administration including empirical fixed dose and calculated dose. Recent meta-analysis supported that dose calculation is better than empirical fixed dose. However, dose calculation by dosimetry or 24 hours radioiodine uptake ratio can be tedious. Pertechnetate thyroid scintigraphy is a simple nuclear imaging that can be completed on the same day and pertechnetate thyroid uptake ratio determined from the scintigraphy can be used to calculate the radioiodine dose. This research is done to measure the efficacy of the calculated dose regime. Methods: Hyperthyroidism patients referred for first radioiodine therapy were recruited. Pertechnetate thyroid scintigraphy was done and pertechnetate uptake ratio used for dose calculation. The outcome of the treatment was determined at six months. Results: A total of 95 patients were recruited. Six months after treatment, 82.1% of the calculated dose cohort achieved euthyroid or hypothyroid state. Participants with multinodular goitre had higher failure rate than those with Graves’ disease (p=0.032) although there was no difference in the median RAI dose given (p=0.866). Conclusion: This calculated dose method showed good outcome with 82.1% cure rate at six months post treatment.
Introduction: The purpose of this study was to determine the usefulness of SPECT-CT in differentiating metastatic and degenerative disease of the spine. Methods: Twenty-eight patients aged 50 years and above diagnosed with various cancers were referred for whole body (WB) planar bone scintigraphy. Those with a maximum three foci of tracer up- take in the spine were selected for the study. SPECT-CT of these areas of uptake was performed and the lesions were classified as degenerative, indeterminate or metastasis. A repeat study (WB planar bone scintigraphy and SPECT-CT) was performed between 3 to 12 months later. These areas of uptake were reassessed and compared with the first WB planar bone scintigraphy and SPECT-CT. The second SPECT-CT was used as the standard for the diagnosis. Results: Thirty-seven lesions in 28 patients were assessed. The sensitivity of the first WB planar bone scintigraphy, second WB planar bone scintigraphy and first SPECT-CT is 75%, 62.5% and 75% respectively. The specificity of the first WB planar bone scintigraphy, second WB planar bone scintigraphy and first SPECT-CT is 86%, 93%, 90% respectively. There was 2.7% of ‘indeterminate lesion’ in the first WB planar bone scintigraphy, 5.4% in the second WB planar bone scintigraphy, and 5.4% in the first SPECT-CT. The indeterminate lesions were resolved in the second SPECT-CT. Conclusion: SPECT- CT is useful in differentiating degenerative disease from metastatic lesions in the spine.
Diffusion Tensor Imaging (DTI) is an advanced magnetic resonance imaging (MRI) technique. DTI provides quantitative information at microstuructural level via its parameter indices e.g. mean diffusivity (MD) and fractional anisotropy (FA). It also allows for visualization of neuron fibres through a specific technique called fibre tractography. Leukoaraiosis is an asymptomatic pathological condition of the brain white matter which appears hyperintense on T2-weighted MRI images. Association of leukoaraiosis with age and ischemic heart disease have been previously reported. The objective of this study is to compare MD and FA values measured in various areas of the brain white matter (WM), grey matter (GM), and cerebrospinal fluid (CSF) in humans using DTI. 30 subjects with leukoaraiosis and 12 subjects without leukoaraiosis underwent brain scan using GE 1.5 Tesla MRI system. Region of interests were located in the CSF and various WM and GM areas. Comparison of MD and FA values was made between leukoaraiosis tissue (LA) and normal appearing brain tissue (NABT) measured within the same leukoaraiosis subjects, and with normal brain tissue (CONTROL) of healthy control subjects. LA demonstrated a significantly higher MD and lower FA compared to NABT and CONTROL in frontal and occipital WM areas. No differences were observed in MD in any brain region between NABT and CONTROL. Whereas no differences were observed in FA between NABT and CONTROL except in the occipital WM. Fibre tractography showed 31.7% to 56.1% lesser fibre tracts in LA subjects compared to CONTROL subjects. Significant differences were found between pathological tissue compared to normal appearing brain tissue and normal brain tissue. Fibre tractography exposed reduced number of neural fibres in leukoaraiosis subjects as compared to normal subjects.
Optimum combination of voxel size resolution and b-value for whole brain imaging has been determined. Data images
were acquired using a 1.5T magnetic resonance imaging (MRI) system (GE Signa HDxt). Diffusion tensor imaging (DTI)
scan was performed on phantom and a human volunteer. Six protocols which consist of various combination of voxel
size and b-value were evaluated. Measurement of signal-to-noise ratio (SNR) and DTI parameter indices were carried out
for both phantom and in-vivo studies. Due consideration was given to a combination of parameters yielding sufficient
SNR with DTI values comparable to those obtained from previous reported studies. For the phantom study, SNR ≥ 20 was
found in all of the protocols except for a combination of voxel size of 2.0 × 2.0 × 2.0 mm3
with b-value of 1200 s/mm2
(V2.0 B1200) and that of voxel size of 2.0 × 2.0 × 2.0 mm3
with b-value of 1000 s/mm2
(V2.0 B1000). For in-vivo study,
all protocols presented SNR > 20. It was found that a combination of voxel size of 2.5 × 2.5 × 2.5 mm3
with b-value of
1000 s/mm2
(V2.5 B1000) and that of voxel size of 2.5 × 2.5 × 2.5 mm3
with b-value of 700 s/mm2
(V2.5 B700) displayed
the most comparable ADC and FA values with references. In terms of anatomic coverage, V2.5 B700 was found better
than V2.5 B1000 as it assures coverage of the whole brain. In conclusion, a combination of voxel size of 2.5 × 2.5 × 2.5
mm3
with b-value of 700 s/mm2
was considered as optimum parameters for brain DTI.