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We recently demonstrated in a clinical trial the ability of a new protocol, IQ SPECT, to acquire myocardial perfusion imaging (MPI) studies in a quarter of the time (12 s/view) of the standard protocol, with preserved diagnostic accuracy. We now aim to establish the lower limit of radioactivity that can be administered to patients and the minimum acquisition time in SPECT MPI using an IQ SPECT protocol, while preserving diagnostic accuracy. Methods: An anthropomorphic cardiac phantom was used to acquire clinical rest scans with a simulated in vivo distribution of 99m Tc-tetrofosmin at full dose (740 MBq) and at doses equal to 50%, 25%, and 18%. For each dose, 2 sets of images were acquired, with and without a transmural defect (TD). Variable acquisition times were also used for each dose. We analyzed raw data and reconstructed images, including no correction and correction for attenuation (AC), for scatter (SC), or for both (ACSC). Images were evaluated qualitatively and quantitatively in order to assess left ventricle (LV) wall thickness (full width at half maximum of the medial sections), TD, and cavity contrast in the LV wall. Data were compared across different acquisition times within the same dose and across doses with the same acquisition time. Results: Images were visually scored as very-good quality except those acquired with 4 s/view or less at 100% dose and 6 s/view or less with 50%, 25%, or 18% dose, due to falsepositive defects. LV wall thickness was not significantly different among all acquisitions. Cavity contrast remained unchanged within the same dose for all images and tended to be higher in AC and ACSC images. TD contrast remained unchanged within the same dose for all images. In SC and no-correction images, contrast was constant for all doses. AC images had significantly higher TD contrast values, and ACSC images showed a drop in TD contrast for a 50% dose. Conclusion: IQ SPECT effectively preserved both image quality and quantitative measurements with reduced acquisition time or administered dose in a phantom study. These findings suggest that approximately one eighth of the time, compared with standard protocols with a full dose, or a lower dose at an acquisition time of 12 s/view can be applied in MPI without the loss of diagnostic accuracy.

This is the first study investigating how a heart mispositioning can affect diagnostic accuracy with IQ-SPECT system. Mild-to-moderate mispositioning (≤2.5 cm) is unlikely to significantly affect results.

Radiochromic EBT films are suitable detectors for surface dose measurements in tomotherapy treatments. Results show that TPS overestimates dose to the skin measured with EBT radiochromic films. In vivo skin measurements with EBT films are a useful tool for quality assurance of tomotherapy treatments, as the treatment planning system may not give accurate dose values at the surface.

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Monoclonal antibodies (mAbs) are produced by clones of a unique parent cell which has monovalent affinity and can bind to the same epitope. The chronological breakthrough in mAbs clinical utilization was in 1975, when it becomes possible to produce mAbs to known antigens and immortalize the cell lines. However, the clinical usefulness of mAbs was hampered for many years, basically because of their immunogenicity due to the murine origin. This situation lasted until 1988 when a technique to humanize mAbs was defined. Nuclear Medicine researchers were very quick to gathered the opportunity provided by the development of mAbs. The first papers reporting the preclinical use of radiolabelled mAbs date the early 80's soon followed by the first pivotal use in humans. However, mAbs did not gain a wide clinical use for several reasons connected to the chemistry and biochemistry of radiolabelled mAbs the emergence of clinical 18F-FDG PET. However, the "magic bullet" concept has resisted in the cultural background of Nuclear Medicine physicians for almost twenty years, and has regained importance with the development of engineered mAbs. Herein we present a selected review of preclinical and clinical studies of PET/CT with mAbs in gastrointestinal malignancies.