Absolute myocardial blood flows derived by dynamic CZT scan vs invasive fractional flow reserve: Correlation and accuracy

MPI in the era of CZT cameras: Absolute numbers are still better than relative figures

“…The introduction of dedicated cardiac CZT camera has represented a technological breakthrough in the field, giving also the chance to perform dynamic cardiac acquisitions in the context of a clinically indicated myocardial perfusion scan. [11][12][13] Accordingly, initial evidence has confirmed the feasibility of MBF quantification on CZT cameras, allowing mirroring the results obtained by PET imaging and predicting the presence of flow-limiting CAD as evaluated by invasive fractional flow reserve (FFR). 12 In particular, while the evaluation of relative myocardial perfusion may still remain the cornerstone for the diagnosis of CAD in the majority of patients, absolute MBF analysis may prove particularly beneficial in patients with extensive CAD burden, in whom semi-quantitative measures may fail to unmask coronary involvement and possibly predict appropriately the risk of future cardiac events.…”

“…[11][12][13] Accordingly, initial evidence has confirmed the feasibility of MBF quantification on CZT cameras, allowing mirroring the results obtained by PET imaging and predicting the presence of flow-limiting CAD as evaluated by invasive fractional flow reserve (FFR). 12 In particular, while the evaluation of relative myocardial perfusion may still remain the cornerstone for the diagnosis of CAD in the majority of patients, absolute MBF analysis may prove particularly beneficial in patients with extensive CAD burden, in whom semi-quantitative measures may fail to unmask coronary involvement and possibly predict appropriately the risk of future cardiac events. 20 At the opposite extreme, patients with subtle myocardial perfusion abnormalities on semi-quantitative CZT analysis but preserved regional MBF and MPR could be reasonably spared from any further diagnostic test and invasive therapy, because of the superior prognostic impact of optimal medical therapy in this setting.…”

“…9,10 Moreover, CZT technology might allow investigating what is commonly regarded as the ''holy Grail'' of coronary pathophysiology, namely absolute myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). 11,12 In fact, absolute assessment of MBF is difficult with standard SPECT cameras, mainly because of the inadequate properties of the currently available flow tracers that show a non-linear extraction fraction at higher flow rates, coupled with the unfavorable physical properties of the Na-I crystals that typically saturate at higher count rates. CZT cameras allow image acquisition in a non-rotating mode and therefore acquisition of time-activity curves, which entail the computation of absolute myocardial perfusion parameters.…”

“…CZT cameras allow image acquisition in a non-rotating mode and therefore acquisition of time-activity curves, which entail the computation of absolute myocardial perfusion parameters. 12,13 As shown by a wide number of reports, the computation of myocardial perfusion parameters allows obtaining some of the most accurate predictors of CAD, possibly individuating even subtle alterations of myocardial perfusion heterogeneity-as a possible result of sub-clinical and/or diffuse CAD, endothelial/microvascular dysfunction-that would be unapparent with a qualitative evaluation. 13,14 Nevertheless, initial studies that have reported on the feasibility of absolute MBF with CZT technology have shown a systematic underestimation of flow values if compared with the available non-invasive and invasive gold standards, showing some of the possible limitations of this approach.…”

“…13,14 Nevertheless, initial studies that have reported on the feasibility of absolute MBF with CZT technology have shown a systematic underestimation of flow values if compared with the available non-invasive and invasive gold standards, showing some of the possible limitations of this approach. 12 Moreover, a direct comparison of the diagnostic capabilities of qualitative vs quantitative myocardial perfusion analysis at CZT is still lacking.…”