Advances in SPECT and PET Hardware

Imaging Cardiovascular Calcification

“…However, Dweck et al64 have reported that the spatial resolution of 18 F‐NaF PET was sufficient to allow location of culprit lesions in coronary territories, and continuous cardiac movement can be addressed by using gating. Furthermore, even if the small size of the coronary arteries may fall below the resolution of most PET scanners117 and leads to underestimation of the PET signal because of a partial volume effect, Beheshti et al102 proposed that 18 F‐NaF deposition could be measured throughout the entire myocardium, including a semiquantitative analysis of the contribution from both the major vessels and the microvasculature, in order to limit the impact of smear artifacts caused by the cardiac motion and small vessel diameter. They also emphasized excluding the aortic valve from the region of interest to avoid contamination by the aortic wall or calcified aortic valve leaflets.…”

Ready, shoot, aim? Summary justice for small hearts in nuclear cardiology

“…Even in cardiac PET, resolution recovery methods combined with time-of-flight (TOF) acquisition are now implemented by all vendors, allowing improved contrast, enhanced image resolution, and reduced image noise. 15 Perhaps the definitive demonstration that standard quantitative cardiac software can do an excellent job even in the smallest hearts, if applied to images acquired with appropriate spatial resolution, can be found in the study by Constantinesco et al, who measured cardiac function in mice using pinhole-gated SPECT and a dedicated smallanimal system. 13 As evidenced in Figure 2, the exact same clinical quantitative cardiac software, found by Yoneyama to underestimate LV volumes and overestimate LVEFs in pediatric patients, was able to accurately measure reference volumes ranging from 0.01 to 0.1 mL!…”

“…Clearly, using a dedicated, small field-of-view machine for pediatric patients is likely impossible or impractical for most clinics-but employing a higher zoom that makes better use of the image matrix by filling it up with more of the actual heart is eminently feasible, and indeed newer SPECT cameras feature more ''cardiocentric'' acquisition strategies aimed at exactly that goal. 15 The fact that zooming in on the heart may truncate thorax contributions at certain angles can be compensated for and is anyway a relatively minor concern when assessing LVEF and myocardial function in general, both of which are less affected by attenuation than perfusion.…”

Validation of 18F–FDG-PET Single-Subject Optimized SPM Procedure with Different PET Scanners

“…This is beyond doubt a compelling issue, since in the last two decades PET tomographs have undergone important changes both in the hardware and in the software. Currently, almost all the scanners available on the market, with the only exception of the High-Resolution Research Tomograph (HRRT) scanner (Eriksson et al 2002), have crystals with side lengths of 4-6 mm (Slomka et al 2015). No other attempts towards increased resolution were performed, due to the increased noise and complexity of such a system (Slomka et al 2015).…”

“…Currently, almost all the scanners available on the market, with the only exception of the High-Resolution Research Tomograph (HRRT) scanner (Eriksson et al 2002), have crystals with side lengths of 4-6 mm (Slomka et al 2015). No other attempts towards increased resolution were performed, due to the increased noise and complexity of such a system (Slomka et al 2015). A technical innovation regards the introduction of faster scintillating crystals (lutetium orthosilicate (LSO) and lutetium-yttrium orthosilicate (LYSO)), which allow Time of Flight measurements and high count-rate capabilities.…”