Ventilation perfusion functional difference images in lung SPECT: A linear and symmetrical scale as an alternative to the ventilation perfusion ratio
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Ventilation perfusion functional difference images in lung SPECT : A linear and symmetrical scale as an alternative to the ventilation perfusion ratio. / de Nijs, Robin; Berg, Ronan M.G.; Lindskov Hansen, Sofie; Mortensen, Jann.
In: Physica Medica, Vol. 119, 103306, 2024.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Ventilation perfusion functional difference images in lung SPECT
T2 - A linear and symmetrical scale as an alternative to the ventilation perfusion ratio
AU - de Nijs, Robin
AU - Berg, Ronan M.G.
AU - Lindskov Hansen, Sofie
AU - Mortensen, Jann
N1 - Publisher Copyright: © 2024 Associazione Italiana di Fisica Medica e Sanitaria
PY - 2024
Y1 - 2024
N2 - Purpose: Ventilation Perfusion SPECT is important in the diagnostics of e.g. pulmonary embolism and chronic obstructive pulmonary disease. Classical and reverse mismatched defects can be identified by utilizing the ventilation-perfusion ratio. Unfortunately, this ratio is only linear in the ventilation, the scale is not symmetrical regarding classical and reversed mismatches and small perfusion values give rise to artifacts. The ventilation-perfusion (VQ) difference is developed as an alternative. Methods: For both VQ-ratio and VQ-difference a scaling factor for the perfusion is computed, so that voxels with matched ventilation and perfusion (on average) yield zero signal. The relative VQ-difference is calculated by scaling with the summed VQ-signal in each voxel. The scaled VQ-difference is calculated by scaling with the global maximum of this sum. Results: The relative and scaled differences have a scale from −1 (perfusion only) to + 1 (ventilation only). Image quality of relative VQ-difference and VQ-ratio images is hampered by artifacts from areas with both low perfusion and low ventilation. Ratio and differences have been investigated in ten patients and are shown for three patients (one without defects). Clinical thresholds for the difference images are derived resulting in color maps of relevant (reversed) mismatches with a (reciprocal) ratio larger than two. Conclusions: The relative ventilation-perfusion difference is a methodological improvement on the ventilation-perfusion ratio, because it has a symmetrical scale and is bound on a closed domain. A better diagnostic value is expected by utilizing the scaled difference, which represents functional difference instead of relative difference.
AB - Purpose: Ventilation Perfusion SPECT is important in the diagnostics of e.g. pulmonary embolism and chronic obstructive pulmonary disease. Classical and reverse mismatched defects can be identified by utilizing the ventilation-perfusion ratio. Unfortunately, this ratio is only linear in the ventilation, the scale is not symmetrical regarding classical and reversed mismatches and small perfusion values give rise to artifacts. The ventilation-perfusion (VQ) difference is developed as an alternative. Methods: For both VQ-ratio and VQ-difference a scaling factor for the perfusion is computed, so that voxels with matched ventilation and perfusion (on average) yield zero signal. The relative VQ-difference is calculated by scaling with the summed VQ-signal in each voxel. The scaled VQ-difference is calculated by scaling with the global maximum of this sum. Results: The relative and scaled differences have a scale from −1 (perfusion only) to + 1 (ventilation only). Image quality of relative VQ-difference and VQ-ratio images is hampered by artifacts from areas with both low perfusion and low ventilation. Ratio and differences have been investigated in ten patients and are shown for three patients (one without defects). Clinical thresholds for the difference images are derived resulting in color maps of relevant (reversed) mismatches with a (reciprocal) ratio larger than two. Conclusions: The relative ventilation-perfusion difference is a methodological improvement on the ventilation-perfusion ratio, because it has a symmetrical scale and is bound on a closed domain. A better diagnostic value is expected by utilizing the scaled difference, which represents functional difference instead of relative difference.
KW - Difference
KW - Embolism
KW - Functional
KW - Krypton
KW - MAA
KW - Obstructive
KW - Perfusion
KW - Ratio
KW - SPECT
KW - Ventilation
UR - http://www.scopus.com/inward/record.url?scp=85184773558&partnerID=8YFLogxK
U2 - 10.1016/j.ejmp.2024.103306
DO - 10.1016/j.ejmp.2024.103306
M3 - Journal article
C2 - 38335743
AN - SCOPUS:85184773558
VL - 119
JO - Physica Medica
JF - Physica Medica
SN - 1120-1797
M1 - 103306
ER -
ID: 384406864