Tetrofosmin 230microgram kit for radiopharmaceutical preparation

Based on superior image quality, more accurate gated images, and lower radiation exposure to patients, Technetium-99m (Tc-99m) based tracers are preferred over Thallium-201 for SPECT myocardial perfusion imaging. The two Tc-99m tracers, sestamibi and tetrofosmin, have many similar characteristics but there are differences in blood and liver clearance rates, as well as the recommended time after injection for imaging to achieve optimal image quality. Because published peer-reviewed studies examining optimal times between injection and imaging are limited, it can be difficult to identify evidence-based opportunities to optimize imaging protocols. Using systematic literature review methods, this study was designed to identify and consolidate the available evidence on the use of sestamibi compared to tetrofosmin for variable injection to imaging times in regard to test efficiency, including test length and re-scan rates, and image quality, including overall quality and cardiac to extra-cardiac ratios. The composite of this data shows that earlier imaging with tetrofosmin is equivalent to later imaging with sestamibi when assessing subjective image quality or when quantifying heart-to-extra-cardiac ratios. Image quality and heart-to-extra-cardiac ratios comparing early versus later imaging with tetrofosmin were comparable if not equivalent to each other. The equivalency of the imaging quality occurs with 15 minutes (on average) earlier imaging compared to sestamibi and 30 minutes compared to standard time tetrofosmin. The subjective findings of equivalent image quality are also shown with objective measurements of heart-to-extra-cardiac ratios. In this review, the significantly shorter injection-to-acquisition times with tetrofosmin compared to sestamibi resulted in better efficiency and less waiting times for patients; in addition, significantly higher re-scan rates with sestamibi compared to tetrofosmin due to hepatic activity contributed to better throughput with tetrofosmin.

Abstract licence: CC BY

In this prospective study we compared the accuracy of 18F-fluorocholine PET/CT with that of 99mTc-MIBI or99mTc-tetrofosmin SPECT/CT in the preoperative detection of parathyroid adenoma in patients with primary hyperparathyroidism. We also assessed the value of semiquantitative parameters in differentiating between parathyroid hyperplasia and adenoma. Both 18F-fluorocholine PET/CT and 99mTc-MIBI/tetrofosmin SPECT/CT were performed in 100 consecutive patients with biochemical evidence of primary hyperparathyroidism. At least one abnormal focus on either 18F-fluorocholine or 99mTc-MIBI/tetrofosmin corresponding to a parathyroid gland or ectopic parathyroid tissue was considered as a positive finding. In 76 patients with positive findings on at least one imaging modality, surgical exploration was performed within 6 months, and the results were related to histopathological findings and clinical and laboratory findings at 3–6 months as the standard of truth. In 24 patients, no surgery was performed: in 18 patients with positive imaging findings surgery was refused or considered risky, and in 6 patients imaging was negative. Therefore, data from 82 patients (76 undergoing surgery, 6 without surgery) in whom the standard of truth criteria were met, were used in the final analysis. All patients showed biochemical evidence of primary hyperparathyroidism with a mean serum calcium level of 2.78 ± 0.34 mmol/l and parathormone (PTH) level of 196.5 ± 236.4 pg/ml. The study results in 76 patients with verified histopathology and 3 patients with negative imaging findings were analysed. Three of six patients with negative imaging showed normalized serum PTH and calcium levels on laboratory follow-up at 3 and 6 months, and the results were considered true negative. In a patient-based analysis, the detection rate with 18F-fluorocholine PET/CT was 93% (76/82), but was only 61% (50/82) with 99mTc-MIBI/tetrofosmin SPECT/CT. In a lesion-based analysis, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of 18F-fluorocholine PET/CT in the detection of parathyroid adenoma were 93.7%, 96.0%, 90.2%, 97.4% and 95.3%, respectively, and of 99mTc-MIBI/tetrofosmin SPECT/CT were 60.8%, 98.5%, 94.1%, 86.3% and 87.7%, respectively. Although 18F-fluorocholine PET-positive adenomatous lesions showed higher SUVmax values than the hyperplastic glands (6.80 ± 3.78 vs. 4.53 ± 0.40) in the semiquantitative analysis, the difference was not significant (p = 0.236). The mean size (measured as the length of the greatest dimension) and weight of adenomas were 15.9 ± 7.6 mm (median 15 mm, range 1–40 mm) and 1.71 ± 1.86 g (median 1 g, range: 0.25–9 g), respectively. Among the analysed parameters including serum calcium and PTH and the size and weight of parathyroid adenomas, size was significantly different between patients with negative 99mTc-MIBI/tetrofosmin SPECT/CT and those with positive 99mTc-MIBI/tetrofosmin SPECT/CT (mean size 13.4 ± 7.6 mm vs. 16.9 ± 7.4 mm, respectively; p = 0.042). In this prospective study, 18F-fluorocholine PET/CT showed promise as a functional imaging modality, being clearly superior to 99mTc-MIBI/tetrofosmin SPECT/CT, especially in the detection and localization of small parathyroid adenomas in patients with primary hyperparathyroidism. SUVmax was higher in parathyroid adenomas than in hyperplasia. However, further evaluation of this modality is needed.

Abstract licence: CC BY

Microcirculation focused evaluations may provide physiological insights that complement those of the established clinical criteria for patients with chronic limb threatening ischaemia (CLTI) since complex treatments are needed in this high risk population. However, current methods for quantitatively assessing foot microcirculation are limited. Thus, in this study, the aim was to aimed to demonstrate a proof of concept non-invasive method with novel parameters for assessing foot microcirculation. This was a single centre prospective cohort pilot study. The lower limbs of 13 patients diagnosed with CLTI were evaluated by radionuclide (RN) angiography with 99m Tc-tetrofosmin two weeks after revascularisation or non-revascularisation procedures. Novel parameters (pedal transit time and peak pedal count) were derived by processing the time–activity curves of the detected tracers in each region of interest in the limbs. The Mann‒Whitney test was used for the analysis of associations between these two parameters and limb fate at one year, and Pearson and Spearman tests were used to analyse associations with transcutaneous partial oxygen pressure (TcPO 2 ), a conventional perfusion test result. The mean pedal transit time of the affected limbs in the non-healing group was longer than that in the healing group (19.1 ± 18.6 vs . 2.9 ±2.1 seconds, p = .001). The mean peak petal count of nucleotides in the non-healing group was lower than that in the healing group (24.4 ±19.0 vs . 72.0 ±36.1 counts/sec/GBq, p = .008). The pedal transit time and peak pedal count showed little to no correlation with the conventional TcPO 2 at the mid-foot ( r = 0.26 for pedal transit time; r = –0.11 for peak pedal count). Two novel microcirculation parameters derived from RN angiography were associated with one year limb outcomes in patients with CLTI. Non-invasive radiotracer imaging derived parameters may provide an additional dimension to indices of pathophysiologic microcirculation in CLTI. • RN angiography provides novel indices for quantifying foot microcirculation in CLTI patients. • Pedal transit time and peak pedal count reflect efficiency and magnitude of foot microcirculation. • Novel metrics associates with limb fate after one year in our prospective cohort. • Microcirculation assessment may help improve the treatment strategies of CLTI.

Abstract licence: CC BY-NC-ND

BACKGROUND: Colchicine reduces sympathetic denervation after acute myocardial infarction (AMI), yet the COLD-MI trial found no change in myocardial perfusion scintigraphy (MPS). MPS-detected necrotic lesions were limited by early management, and MPS may therefore have lacked the sensitivity to capture subtle colchicine-induced variations in minimal necrosis during the immediate post-stenting period. Myocardial perfusion reserve (MPR), a quantitative indicator of global microvascular function, may overcome these limitations. This ancillary analysis of the COLD-MI trial evaluated whether colchicine improves MPR six months after AMI. METHODS: Forty-five post-AMI patients randomized to colchicine for 30 days or no colchicine underwent quantitative dynamic [99mTc]Tc-tetrofosmin SPECT and [123I]-mIBG imaging at 6 months. MPR was quantified using CZT-SPECT as the stress-to-rest uptake ratio. Secondary endpoints included MPS scoring (SRS, SSS, SDS) and sympathetic innervation assessed by normalized mean segmental activity. Analyses were blinded. RESULTS: Colchicine-treated patients showed significantly higher MPR in remote myocardium than controls (2.37 ± 0.61 vs. 1.92 ± 0.53; P = 0.01). Denervated myocardial surface area in remote regions was also lower with colchicine (43% [29-50] vs. 50% [38-64]; P = 0.04). In infarcted myocardium, MPR did not differ (1.79 ± 0.61 vs. 1.60 ± 0.63; P = 0.35). A non-significant trend toward better preserved innervation was observed (denervation: 46% [35-50] vs. 50% [45-69]; P = 0.09). SRS, SSS, and SDS were similar between groups. CONCLUSIONS: Colchicine significantly increases MPR in remote myocardium six months after AMI, consistent with reduced sympathetic denervation and supporting a microvascular benefit of colchicine post-AMI.

Abstract licence: CC BY-NC-ND

Abstract Mitochondrial transplantation is a promising but still experimental strategy for treating ischemic and metabolic disorders. A key barrier to its advancement is the lack of scalable, non-invasive methods for tracking transplanted extracellular mitochondria in vivo. Technetium-99m (Tc-99m) radiopharmaceuticals, widely used in SPECT imaging, may offer a clinically compatible solution. Cryopreserved mitochondria derived from HEK-293 cells were incubated with Tc-99m sestamibi, tetrofosmin, pertechnetate, or control solutions. After brief incubation and washing, mitochondrial pellets were analyzed for retained radioactivity. ATP content was measured to assess metabolic function, and electron microscopy was used to evaluate ultrastructural integrity. Tc-99m sestamibi and tetrofosmin showed labeling efficiencies of 2.74% and 2.68%, respectively. Pertechnetate demonstrated minimal uptake (0.34%). Radiolabeled mitochondria retained ATP production comparable to controls. Electron microscopy showed preserved double membranes and cristae. Controls confirmed assay specificity and viability. To our knowledge, this is the first report of radiolabeling isolated mitochondria with clinically approved Tc-99m agents. This platform supports the development of SPECT-compatible protocols for visualizing viable transplanted mitochondria in recipient tissues.

Abstract licence: CC BY-NC