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123I-2-iodo-tyrosine (123I-2IT) has been identified as a promising new amino acid tracer in animals. Uptake is mediated by LAT1 transport, which is increased in tumour cells. In this study we present the human biodistribution and first clinical results in glioma patients. For the biodistribution study, six male volunteers received 60–95 MBq 123I-2IT. Whole-body scans and blood and urine samples were obtained up to 24 h after injection; dosimetry was calculated using OLINDA 1.0 software. Initial clinical evaluation of 123I-2IT SPECT was performed in 35 patients with suspected or known glioma, either as primary diagnosis or for detection of recurrence. Tumour-to-background (T/B) ratios were calculated for semi-quantitative analysis. The results were correlated with clinical and MRI follow-up data or histology. 123I-2IT showed both renal and intestinal clearance. Bladder (0.12 mGy/MBq) and small intestine (0.03 mGy/MBq) received the highest absorbed doses. The effective dose equivalent and effective dose were estimated at 0.020 and 0.016 mSv/MBq, respectively. In patients, 123I-2IT SPECT did not differentiate between neoplastic and non-neoplastic lesions after an indeterminate MRI. In follow-up of known glioma, 13/15 patients with disease recurrence had increased T/B values (range 1.39–3.91). Out of seven recurrence-negative patients, two showed an important increase in T/B, in one case due to radionecrosis (T/B 1.59) and in the other probably due to residual but stable disease (T/B 2.07). 123I-2IT has a favourable biodistribution for a tumour imaging agent. It shows increased uptake in central nervous system glioma and is potentially useful in the follow-up of glioma patients. [ABSTRACT FROM AUTHOR]

Unlabelled: Cell therapy-induced changes in the perfusion of areas of myocardial infarction (MI) remain unclear. This study investigated whether an original pinhole SPECT technique could be applied to a rat MI model to analyze local improvement in myocardial perfusion relating to engraftment sites of bone marrow-derived stem cells (BMSCs)., Methods: Four-month-old MI rats were either untreated (n = 8) or treated (n = 10) by intramyocardial injection of (111)In-labeled BMSCs. Early distribution of (111)In-BMSCs within the MI target was evidenced by dual (111)In/(99m)Tc pinhole SPECT 48 h later. Myocardial perfusion was serially monitored by (99m)Tc-sestamibi pinhole gated SPECT up to 3 mo after transplantation., Results: Forty-eight hours after transplantation, (111)In-BMSCs were observed in all treated rats and in 18 of their 32 underperfused MI segments (<70% sestamibi uptake before transplantation). During the subsequent 3-mo follow-up, the perfusion of MI segments worsened in untreated rats (absolute change in sestamibi uptake, -3% +/- 3%; P < 0.05) but improved in treated rats (+4% +/- 7%; P < 0.05). This perfusion improvement was unrelated to the initial detection of (111)In-BMSCs (+2% +/- 6% in segments with (111)In-BMSCs vs. +5% +/- 7% in those without; not statistically significant) but was strongly associated with less severe perfusion defects before transplantation (+6% +/- 6% in segments with 60%-70% sestamibi uptake [n = 19] vs. -1% +/- 6% in those with <60% uptake [n = 13]; P = 0.003)., Conclusion: When BMSCs are injected within chronic MI, perfusion enhancement predominates in the MI areas showing a high enough residual perfusion before treatment but not in those of the initial cell engraftment, giving evidence of dependency on the perfusion and metabolic environment at implantation sites.

Unlabelled: Gated SPECT recorded with 16 intervals determines left ventricular (LV) ejection fraction more accurately than does gated SPECT recorded with 8 intervals but produces higher image noise. This study aimed to assess the results from sestamibi and (201)Tl 16-interval gated SPECT when both signal-to-noise ratio and spatial resolution were enhanced with an original method of reconstruction., Methods: Forty patients with coronary artery disease underwent (201)Tl and sestamibi 16-interval gated SPECT and, to be used as a reference, cardiac MRI. Assessments of global and regional LV function provided by ordered-subsets expectation maximization (OSEM) with depth-dependant resolution recovery and temporal Fourier filtering were compared with those from conventional filtered backprojection (FBP) previously optimized by screening various filter frequencies and various temporal smoothing levels., Results: For both tracers, LV ejection fraction was determined best when the association of OSEM with depth-dependant resolution recovery was used alone, with temporal Fourier filtering, or with a slight 2-frame temporal smoothing: Mean absolute values of relative errors ranged from 3.2% to 3.6% (4.0%-7.9% for FBP), and coefficient correlation ranged from 0.91 to 0.93 (0.70-0.91 for FBP). Among these 3 reconstruction methods, the association of OSEM with depth-dependant resolution recovery with temporal Fourier filtering provided the highest signal-to-noise ratio, with mean increases of 54% for sestamibi and 80% for (201)Tl when compared with FBP, and the best analysis of segmental contractility, with exact agreement rates with MRI being 73% for (201)Tl and 79% for sestamibi., Conclusion: OSEM associated with temporal Fourier filtering and depth-dependant resolution recovery filtering enhances the LV function assessment provided by sestamibi and (201)Tl 16-interval gated SPECT and dramatically reduces image noise, a property that enhances and facilitates image interpretation.