A Pilot Study of the Striatal Dopamine Transporter Levels in Kratom-Dependent and Normal Subjects Using 99mTc-TRODAT-1 Single Photon Emission Computed Tomography-Computed Tomography (SPECT-CT).

OBJECTIVE: The study aims to elucidate the effects of kratom addiction on dopamine transporter (DAT) using [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato(3-)-N2,N20,S2,S20]oxo-[1R-(exo-exo)]-[99mTc] technetium (99mTc-TRODAT-1) brain single photon emission computed tomography-computed tomography (SPECT-CT) in kratom-dependent and healthy subjects. MATERIALS AND METHODS: We recruited 12 kratom-dependent subjects and 13 healthy men to participate in this study. Addiction, craving, depression, and cognitive scores were assessed. All subjects received a single bolus injection of 99mTc-TRODAT-1 with 914.1 MBq ± 65.5 of activity (mean ± SD). The brain SPECT-CT images were reconstructed using 3D ordered subset expectation maximization (3D-OSEM) along with attenuation correction (AC), scatter correction (SC), and resolution recovery (RR) with an iteration number of four and a subset of 10. The Cohen's Kappa interrater-reliability between two raters, the standardized uptake value of body weight (SUVBW), and the asymmetrical index percentage (AI%) were evaluated. RESULTS: Kappa statistics showed a fine agreement of abnormal 99mTc-TRODAT-1 uptake in the striatum region for the kratom-dependent group with the κ value of 0.69 (p = 0.0001), and the percentage of agreement for rater 1 and rater 2 was 56% and 64%, respectively. There was a reduction in average SUV in kratom-dependent subjects compared to healthy control subjects in the left caudate and left striatum (0.938 vs. 1.251, p = 0.014, and 1.055 vs. 1.29, p = 0.036, respectively). There was a significant difference in the AI% of the caudate region between the kratom-dependent group and the normal group (33% vs. 14%, p = 0.019). CONCLUSION: Our findings signify that kratom addiction, may cause a change in DAT level and the results can be confirmed using 99mTc-TRODAT-1 SPECT-CT.

Experimental evaluation of absolute quantification in 99m Tc-TRODAT-1 SPECT/CT brain dopamine transporter (DAT) studies.

OBJECTIVE: To evaluate the quantitative accuracy of clinical brain dopamine transporters (DAT) investigations utilizing 99m Tc-TRODAT-1 single-photon emission computed tomography (SPECT)/computed tomography (CT) in experimental and clinical settings. MATERIALS AND METHODS: The study used an experimental phantom evaluation and a clinical dataset. Three-dimensional-ordered subsets expectation-maximization reconstructed the original and resampled datasets using attenuation correction, scatter correction, and resolution recovery. The reconstructed data were analyzed and reported as percentage difference, standardized uptake value reference (SUVr), and a coefficient of variation (CoV). The Taguchi method tested the impact of the three different parameters on signal-to-noise ratio (SNR) and SUVr, including number iteration, Poisson resampling, and phantom setup, with and without the plaster of Paris (POP). Six 99m Tc-TRODAT-1 SPECT/CT scans were acquired in healthy subjects for verification purposes. RESULTS: The percentage activity difference between the phantom with and without POP is 20% and 5%, respectively. The SUVr reveals a 10% underestimate for both with and without POP. When it comes to the influence of Poisson resampling, the SUVr value for 75% Poisson resampling indicates 10% underestimation on both sides of the caudate and putamen area, with and without POP. When 25% of Poisson resampling is applied, the SUVr value is overestimated (±35%). In the Taguchi analysis, iteration numbers were the most dominant factor with the F-value of 9.41 and the contribution rate of 52.66% (p < 0.05) for SNR. In comparison, F-value of 9.1 for Poisson resampled with contribution rate of 58.91% (p < 0.05) for SUVr. Reducing counts by 25% from the original dataset resulted in a minimal bias in SUVr, compared to 50% and 75%. CONCLUSION: The optimal absolute SPECT/CT quantification of brain DAT studies using 99m Tc-TRODAT-1 appears achievable with at least 4i10s and SUVr as the surrogate parameter. In clinical investigations, it is possible to reduce the recommended administered dose by up to 25% while maintaining accurate measurement.

Value of Baseline Post-Transplant MAG3 Renal Scintigraphy in the Evaluation of Graft Function.

INTRODUCTION: Accurate assessment of renal graft function in the early post-transplant period is crucial, as it influences clinical management and graft prognostication. However, there are limitations in current available modalities. MAG3 scintigraphy could contribute vital information on graft function. OBJECTIVES: This study aimed to determine the predictive value of parameters derived from MAG3 performed within 72 hours post transplant in detecting graft function. Delayed graft function (DGF), which is defined as dialysis requirement within the first week post transplant, is chosen as a surrogate measure of graft function. METHODOLOGY: All renal transplant recipients who underwent MAG3 within 72 hours post transplant from 2017 to 2019 were enrolled. Three MAG3 parameters, renogram grade, tubular injury severity score, and R20:3, were evaluated. RESULTS: A total of 117 patients were enrolled. The overall incidence of DGF was 16.2% with a significantly higher incidence amongst cadaveric graft recipients (53.6%) compared with living graft recipients (4.5%). Renogram grade ≥2, tubular injury severity score ≥4, and R20:3 > 1.31 significantly predicted DGF, P < .05 with high area under the curve for R20:3 of 0.97. Grafts with parameters above the cutoffs also showed significantly worse GFR at 1- and 3-months post-transplant. On multivariate analysis, prolonged cold ischemia time was associated with a higher risk of DGF, odds ratio 1.005 (95% confidence interval 1.003-1.007), P < .05. CONCLUSION: Baseline MAG3 accurately depicts early graft function and was also predictive of GFR at 1- and 3- months post-transplant. These baseline MAG3 scans could be particularly useful amongst deceased donor graft recipients owing to the higher risk of poor graft function.

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.

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 99mTc-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 99mTc-MDP was performed in 34 patients diagnosed with prostate carcinoma. SPECT/CT was performed based on our institutional standard guidelines. SUVmax 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 SUVmax 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 SUVmax was also assessed. The corrected SUVmax values were obtained based on the recovery coefficient (RC) method. RESULTS: The mean SUVmax for normal vertebrae was 7.08 ± 1.97, 12.59 ± 9.01 for DJD and 36.64 ± 24.84 for bone metastases. The SUVmax 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 SUVmax value ≥ 20 gave a sensitivity of 73.8% and specificity of 85.4% in differentiating bone metastases from DJD. The corrected SUVmax for both DJD and bone metastases was smaller with a mean of 6.82 ± 6.02 and 24.77 ± 20.61, respectively. The cutoff SUVmax value was also lower with a value of 10, which gave a sensitivity of 73.8% and specificity of 86.5%. CONCLUSION: SPECT SUVmax was significantly higher in bone metastases than DJD. Semi-quantitative assessment with SUVmax can complement qualitative analysis. A cutoff SUVmax 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.