Does Single Computed Tomography Attenuation Correction able to Surrogate Serial Computed Tomography Attenuation Correction in Single-Photon Emission Computed Therapy Imaging for Peptide Receptor Radionuclide Therapy Dosimetry Result?

Peptide Receptor Radionuclide Therapy (PRRT) is the administration of a radionuclide, such as the Lu-177 label, along with a pharmaceutical agent to destroy the lesion cell. The first cycle of Lu-177 DOTA-TATE is an excellent way to estimate radionuclide uptake for organs at risk. To estimate the absorbed dose for a kidney, serial SPECT-CT imaging with up to five sets is required. In general, serial CT on patients would result in additional external exposure and extra time consuming, especially for low dose CT such as cone beam CT technology. However, by introducing a new method, such as optimized single CT (24 h) to perform with serial SPECT attenuation correction, additional external exposure from serial CT exposure could be reduced. Aims: The purpose of this study is to assess the agreement between single CT scanning as CT attenuation Correction with serial CT scanning for serial SPECT imaging as well as estimated absorbed dose to the organ at risk. Settings and Design: During the first cycle of Lu177-DOTA-TATE, all patients should undergo internal dosimetry technique using SPECT-CT imaging with a PHILIP Brightview XCT gamma camera. The quantifications of SPECT images are being used to measure the uptake activity to the organ. In this investigation, Partik's categorical grading criteria are being used to convert the numeric value of Lin's concordance coefficient into an ordinal scale. Method: Total of 9 patients at our institution was administered with Lu177-DOTA-TATE enroll in this study. SPECT-CT data were acquired using automatic body contouring with a total of 48 angular views at steps of 6° (15 s/projections). The pixel size is 4.66 x 4.66 x 4.66 mm, the images size set to one, and SPECT data has been acquired for three-bed positions extending from the abdomen to the thorax region. Low-dose CT imaging performed at an X-ray tube voltage of 120 kVp. Results: Our current result demonstrated by single CT scanning for SPECT attenuation shown the excellent agreement with standard serial CT imaging for organs at risk such as kidney 0.999, spleen 0.9951, liver 0.9951 and bladder 0.9972. Conclusions: When compared to the previous method, patients benefit significantly more from this study, such as lower CT exposure.

Systematic Review on Multilevel Analysis of Radiation Effects on Bone Microarchitecture.

Introduction: Modern radiation therapy has become an effective method to treat and monitor tumour growth in cancer patients. It has proved to be a successful way to minimise mortality rates. However, the adverse effects of radiation have been historical evidence in the clinical environment involving diminishing the quality and density of bone and causing fragility fracture to the bone in the long run. This systematic review was aimed at identifying and evaluating the effects of irradiation on morphology and mechanical properties of murine model bone in previous publications. Methods: A systematic literature review was undertaken following the Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA) guidelines. A comprehensive literature search was performed using Scopus, Web of Science, and Science Direct databases (English only studies published between 2015 and 2020). The selected studies were evaluated according to three criteria: (1) criteria for study sample selection; (2) criteria for methodological procedures; and (3) criteria for detection and evaluation. Results: The initial search strategy identified 1408 related studies, 8 of were included based on inclusion and exclusion criteria. This review revealed an association between bone destruction and the magnitude of time and dose postirradiation. We agreed that the effect of radiation on bone morphology and strength primarily is a later stage event but noticeable in both low (1 Gy) and high dose (30 Gy) radiation. Trabecular and cortical bone microstructures were significantly altered at irradiation and contralateral sites. Besides, the mechanical strength was significantly impacted in both shorter and longer periods. Conclusion: Overall, the radiotherapy altered bone microstructures and substantially decreases bone mechanical properties. The alteration was related to quantity and the activity of the osteoblast and osteoclast. Early detection of those most at risk for radiation-induced bone alterations could lead to better prophylactic intervention decisions.

Mechanical and Imaging Properties of a Clinical-Grade Kidney Phantom Based on Polydimethylsiloxane and Elastomer.

Medical imaging phantoms are considered critical in mimicking the properties of human tissue for calibration, training, surgical planning, and simulation purposes. Hence, the stability and accuracy of the imaging phantom play a significant role in diagnostic imaging. This study aimed to evaluate the influence of hydrogen silicone (HS) and water (H2O) on the compression strength, radiation attenuation properties, and computed tomography (CT) number of the blended Polydimethylsiloxane (PDMS) samples, and to verify the best material to simulate kidney tissue. Four samples with different compositions were studied, including samples S1, S2, S3, and S4, which consisted of PDMS 100%, HS/PDMS 20:80, H2O/PDMS 20:80, and HS/H2O/PDMS 20:40:40, respectively. The stability of the samples was assessed using compression testing, and the attenuation properties of sample S2 were evaluated. The effective atomic number of S2 showed a similar pattern to the human kidney tissue at 1.50 × 10-1 to 1 MeV. With the use of a 120 kVp X-ray beam, the CT number quantified for S2, as well measured 40 HU, and had the highest contrast-to-noise ratio (CNR) value. Therefore, the S2 sample formulation exhibited the potential to mimic the human kidney, as it has a similar dynamic and is higher in terms of stability as a medical phantom.

18F-labeled Bisphosphonate as an Alternative Candidate to the Gold Standard[18F]sodium fluoride ([18F]NaF) for PET Bone Imaging.

Bone metastases are a common source of malignancy in the skeleton and occur much more often than primary bone cancer. Several works were being performed to identify early markers for bone metastasis and novel drug targets to improve patients' quality of life. As some concerns exist with the [18F]sodiumfluoridein positron emission tomography (PET) bone imaging, there has been an increase in the number of targeted radiopharmaceutical markers for bone metastases imaging in its competitor, 68Ga. Since 18F properties are superior to those of 68Ga, there is a distinct motivation for developing 18F radiopharmaceuticals for bone metastases imaging.

Effect of reconstruction parameters on cone beam CT trabecular bone microstructure quantification in sheep.

BACKGROUND: Cone Beam Computed Tomography (CBCT) is a reliable radiographic modality to assess trabecular bone microarchitecture. The aim of this study was to determine the effect of CBCT image reconstruction parameters, namely, the threshold value and reconstruction voxel size, on trabecular bone microstructure assessment. METHODS: Five sectioned maxilla of adult Dorper male sheep were scanned using a CBCT system with a resolution of 76 µm3 (Kodak 9000). The CBCT images were reconstructed using different reconstruction parameters and analysed. The effect of reconstruction voxel size (76, 100 and 200 µm3) and threshold values (±15% from the global threshold value) on trabecular bone microstructure measurement was assessed using image analysis software (CT analyser version 1.15). RESULTS: There was no significant difference in trabecular bone microstructure measurement between the reconstruction voxel sizes, but a significant difference (Tb.N = 0.03, Tb.Sp = 0.04, Tb.Th = 0.01, BV/TV = 0.00) was apparent when the global threshold value was decreased by 15%. CONCLUSIONS: Trabecular bone microstructure measurements are not compromised by changing the CBCT reconstruction voxel size. However, measurements can be affected when applying a threshold value of less than 15% of the recommended global value.

18F[AlF]-radiolabelled Peptides on the Automated Synthesis Platform: Translating the Laboratory Bench Work to Bedside.

Using radiolabelled peptides that bind, with high affinity and specificity, to receptors on tumour cells is one of the most promising fields in modern molecular imaging and targeted radionuclide therapy (1). In the emergence of molecular imaging and nuclear medicine diagnosis and therapy, albeit theranostic, radiolabelled peptides have become vital tools for in vivo visualisation and monitoring physiological and biochemical processes on molecular and cellular levels (2). This approach may benefit patients in the era of personalised medicine.

Supplementation of 100% Flesh Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] Juice Improves Swimming Performance in Rats.

Nutritional intervention of fruit juice supplementation is able to maximize exercise performance. Watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] contains high L-citrulline content and consumption of watermelon juice may promote ergogenic effects. The aim of the present study was to investigate the role of 100% flesh watermelon juice and 100% rind watermelon juice supplementation for 14 days on swimming performance in rats. Twenty four male Sprague-Dawley rats were randomly divided into four groups: Cx group of rats supplemented with filtered tap water (negative control), L-cit group of rats supplemented with L-citrulline (positive control), FR group of rats supplemented with 100% flesh watermelon juice, and RR group of rats supplemented with 100% rind watermelon juice. Each group was supplemented for 14 days ad libitum prior to swimming exercise protocol. The rats were performed swimming exercise for 3 days and swimming time until exhaustion was measured. Plasma samples were collected to measure lactate concentration, ammonia concentration, and nitric oxide production. Rats supplemented with 100% flesh watermelon juice demonstrated significantly prolonged of swimming time until exhaustion, reduction of lactate and ammonia concentrations, and increased of nitric oxide production compared to Cx and L-cit groups (P<0.05). These findings postulate that supplementation with 100% flesh watermelon juice improves endurance in swimming performance.

Imaging characteristics of extrapulmonary tuberculosis lesions on dual time point imaging (DTPI) of FDG PET/CT.

INTRODUCTION: This study aimed to evaluate the diagnostic value of dual time point imaging (DTPI) of 18F-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) for detecting the infective lesions in patients with extrapulmonary tuberculosis (EPTB). METHODS: Eleven patients were consecutively recruited and evaluated. After the intravenous injection of 369 ± 153 MBq of FDG, all patients underwent FDG PET/CT imaging at two different time points: early scan at 57 ± 23 min and delayed scan at 136 ± 42 min. The maximum standardized uptake values (SUVmax) were recorded for both time points (early scan: SUVmax1 and delayed scan: SUVmax2). RESULTS: In total, 30 lesions were detected. The SUVmax2 in 22 of the lesions in confirmed EPTB patients were significantly higher than the SUVmax1 (7.9 ± 3.2 vs. 6.8 ± 2.5; P = 0.001). The SUVmax for another eight non-EPTB lesions also showed a significant increasing pattern of change (6.2 ± 2.6 vs. 6.5 ± 2.8; P = 0.044). However, there was insignificant difference between the mean percentage difference of SUVmax (%ΔSUVmax) of EPTB and non-EPTB lesions (P = 0.06). CONCLUSION: Our study demonstrates that early whole body PET/CT imaging may be sufficient for the detection of the EPTB lesions and DTPI of PET/CT may also not be a useful technique in differentiating between EPTB and non-EPTB lesions. However, our findings are based on a limited number of patients, and therefore, further investigations in larger series of patients are warranted.