Table 2 Derived image measures

E_ratio (arb. unit)*

\(E_{\mathrm {ratio}} = {{\sum \nolimits_{{i = 1}}^{{120}} v1_{i} } \mathord{\left/ {\vphantom {{\sum \nolimits_{{i = 1}}^{{120}} v1_{i} } {\sum \nolimits_{{i = 1}}^{{120}} v2_{i} }}} \right. \kern-\nulldelimiterspace} {\sum \nolimits_{{i = 1}}^{{120}} v2_{i} }}\)

E_ratio was calculated by summing the counts of all projections in the primary energy window of the raw ventilation SPECT data (\(v1\)), and then dividing the result by the summed counts of all projections in the Compton scatter energy window of the raw ventilation SPECT data (\(v2\))

VCR (cps)

\({\text{VCR}} = {{\sum\nolimits_{{i = 1}}^{{120}} {v1_{i} } } \mathord{\left/ {\vphantom {{\sum\nolimits_{{i = 1}}^{{120}} {v1_{i} } } {t1}}} \right. \kern-\nulldelimiterspace} {t1}}\)

The ventilation count rate (VCR) was calculated by summing the counts of all projections in the primary energy window of the raw ventilation SPECT data (\(v1\)), and then dividing the result by the ventilation SPECT acquisition duration (\(t1\))

PVCR (cps)

\({\text{PVCR}} = {{\sum\nolimits_{{i = 1}}^{{120}} {p1_{i} } } \mathord{\left/ {\vphantom {{\sum\nolimits_{{i = 1}}^{{120}} {p1_{i} } } {t2}}} \right. \kern-\nulldelimiterspace} {t2}}\)

The perfusion + ventilation count rate (PVCR) was calculated by summing the counts of all projections in the primary energy window of the raw perfusion SPECT data (\(p1\)), and then dividing the result by the perfusion SPECT acquisition duration (\(t2\))

PCR (cps)

\({\text{PCR}} = {\text{PVCR}} - {\text{DF}} \cdot {\text{VCR}}\)

The perfusion count rate (PCR) was calculated by first correcting VCR by the relevant decay factor [\({\mathrm{DF}}\)] to account for the interval between ventilation and perfusion SPECTs, and then subtracting the result from PVCR

P/V ratio (arb. unit)*

\(\frac{P}{V}=\frac{{\mathrm{PCR}}}{{\mathrm{VCR}}}\)

The P/V ratio was calculated by dividing PCR by VCR

A_inj (MBq)

\(A_{{{\text{inj}}}} = {\text{DF}} \cdot {\text{ICR}}/S\)

The activity of [^99mTc]Tc-MAA present at the injection site at time of P SPECT (A_inj) was calculated by taking the count rate on the injection site planar static image (ICR), correcting this value by the relevant decay factor [\({\mathrm{DF}}\)] to account for the interval between perfusion SPECT and injection site imaging, and then dividing the result by camera-collimator sensitivity (\(S\))

A_sys (MBq)

\(A_{{{\text{sys}}}} = {\text{DF}} \cdot A_{{{\text{disp}}}} - A_{{{\text{inj}}}}\)

The activity of [^99mTc]Tc-MAA administered systemically at the time of the perfusion SPECT (A_sys) was calculated by first correcting the amount of activity at time of dispensing (A_disp) by the relevant decay factor [DF] to account for the interval between dispensing and perfusion SPECT, and then subtracting A_inj

PCR_norm (arb. unit)*

\({p}_{\mathrm{rate}}=\frac{{\mathrm{PCR}}}{{A}_{{\mathrm{sys}}}}/S\)

The normalised perfusion count rate (PCR_norm) was calculated by dividing PCR by A_sys, and then dividing the result by the camera-collimator sensitivity (S)