Cut-off value for normal versus abnormal right-to-left shunt percentages using 99mTc-macroaggregated albumin

Ito, Kimiteru; Kurihara, Kyoko; Ishibashi, Akihiko; Morooka, Miyako; Mitsumoto, Takuya; Minamimoto, Ryogo; Kubota, Keiichi

doi:10.1097/mnm.0b013e32834a123f

Cited by 15 publications

(5 citation statements)

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“…However, in our case, they were all normal. Only the 99m Tc-MAA pulmonary perfusion scintigraphy revealed right-to-left shunt 19,20 ; in our case, it prompted subsequent genetic analysis and lead to the final diagnosis of HHT. True-positive results on nuclear medicine scan without abnormal morphological findings have been reported many times before.…”

Section: Figurementioning

confidence: 59%

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

Yang

Yuan²,

Ma³

et al. 2016

Clinical Nuclear Medicine

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A 5-year-old boy was admitted due to shortness of breath. Blood gas analysis showed hypoxemia. However, thoracic and abdominal CT, brain MRI, and MR angiography were all normal. A Tc-MAA pulmonary scintigraphy revealed right-to-left shunting of the blood. Further genetic analysis showed the mutations in the activin receptor-like kinase 1 gene, and a diagnosis of hereditary hemorrhagic telangiectasia was made.

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Section: Figurementioning

confidence: 59%

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

Yang

Yuan²,

Ma³

et al. 2016

Clinical Nuclear Medicine

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“…Additional sources of error not accounted for include non-correction for out-of-field-of-view scatter, and variation in the radiochemical purity of [ 99m Tc]Tc-MAA between 95 and 100% (which may have contributed slightly to error in PCR norm ). Another, inherent limitation in predicting PCR is presented by variability in right-left shunting (including physiological shunting) which could not be accounted or corrected for [26]. Finally, it is also important to acknowledge that these results are specific for the energy window settings used on systems with an ~ 10% energy resolution, and using [ 99m Tc]Tc-Technegas, which has minimal early clearance after ventilation [27].…”

Section: Discussionmentioning

confidence: 99%

Dual energy window imaging for optimisation of P/V ratios in VP SPECT

Doruyter

Holness

2021

EJNMMI Phys

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Purpose Ventilation–perfusion single-photon emission computed tomography (VP SPECT) plays an important role in pulmonary embolism diagnosis. Rapid results may be obtained using same-day ventilation followed by perfusion imaging, but generally requires careful attention to achieving an optimal count rate ratio (P/V ratio) of ≥ 3:1. This study investigated whether the ratio of counts simultaneously acquired in adjacent primary and Compton scatter energy windows (Eratio) on V SPECT was predictive of final normalised perfusion count rate (PCRnorm) on P SPECT using [99mTc]Tc-macroaggregated albumin (MAA), thus allowing for optimisation of P/V ratios. Methods Same-day VP SPECT studies acquired using standard protocols in adult patients during a 2-year period (training dataset) were assessed. Studies were included provided they were acquired with correct imaging parameters, and injection site imaging and laboratory records were available for quality control and normalised count rate corrections. Extraction of DICOM information, and linear regression were performed using custom Python and R scripts. A predictive tool was developed in Microsoft Excel. This tool was then validated using a second (validation) dataset of same-day studies acquired over a subsequent 7-month period. Accuracy of the prediction tool was assessed by calculating the mean absolute percentage error (MAPE). Results Of 643 studies performed, the scans of 342 participants (median age 30.4 years, 318 female) were included in the training dataset, the analysis of which yielded a significant regression equation (F(1,340) = 1057.3, p < 0.0001), with an adjusted R2 of 0.756 and MSE of 0.001089. A prediction tool designed for routine clinical use was developed for predicting final P/V ratio. Of an additional 285 studies, 198 were included in the second (validation) dataset (median age 29.7 years, 188 female). The Excel-based tool was shown to be 91% accurate (MAPE: 9%) in predicting P/V ratio. Conclusion The relationship between the ratio of simultaneously acquired counts in adjacent energy windows on V SPECT and perfusion count rate after administration of a known activity of [99mTc]Tc-MAA can be linearly approximated. A predictive tool based on this work may assist in optimising the dose and timing of [99mTc]Tc-MAA administration in same-day studies to the benefit of patients and workflows.

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“…Fourthly, although radiochemical purity of [ 99m Tc]Tc-MAA was routinely above 95%, variation above this threshold was not accounted for, which may have contributed slightly to error in PCR norm . Finally, an inherent limitation in predicting PCRs is presented by variability in right-left shunting (including physiological shunting) which could not be accounted or corrected for [23].…”

Section: Discussionmentioning

confidence: 99%

Dual Energy Imaging for Optimisation of P/V Ratios in VP SPECT

Doruyter¹,

Holness²

2021

Preprint

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PurposeVentilation-perfusion single photon emission computed tomography (VP SPECT) plays an important role in pulmonary embolism diagnosis. Rapid results may be obtained using same-day ventilation followed by perfusion imaging, but generally requires careful attention to achieving an optimal count rate ratio (P/V ratio) of ~3:1. This study investigated whether the ratio of counts simultaneously acquired in adjacent primary and Compton-scatter energy windows (E_ratio) on V SPECT was predictive of final normalised perfusion count rate (PCRnorm) on P SPECT using [99mTc]Tc-macroaggregated albumin (MAA), allowing optimisation of P/V ratio. MethodsSame-day VP SPECT studies acquired using standard protocols in adult patients during a 2-year period were assessed. Studies were included provided they were acquired with correct imaging parameters, and injection site imaging and laboratory records were available for quality control and normalised count rate corrections. Extraction of DICOM information, and linear regression were performed using custom Python and R scripts. A predictive tool was developed in Microsoft Excel.ResultsOf 643 studies performed, the scans of 343 participants (median age 30.4 years, 318 female) met inclusion criteria. A single outlier with high influence was excluded after an obvious cause was identified. Final analysis of the remaining 342 scans yielded a significant regression equation (F(1,340) = 1057.3, p <.000), with an adjusted R2 of .756 and MSE of 0.001089. A prediction tool designed for routine clinic use was developed for predicting final P/V ratio.ConclusionThe ratio of simultaneously acquired counts in adjacent energy windows on V SPECT is linearly related to perfusion count rate after administration of a known activity of [99mTc]Tc- MAA. A predictive tool based on this work may assist in optimising the dose and timing of [99mTc]Tc-MAA administration in same-day studies to the benefit of patients and workflows.

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Cut-off value for normal versus abnormal right-to-left shunt percentages using 99mTc-macroaggregated albumin

Abstract: The normal range (mean±2 SD) was 6.64±1.88%. The cut-off value for the normal right-to-left shunt percentage in MAA scintigraphy was 10%.

Cited by 15 publications

References 0 publications

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

Dual energy window imaging for optimisation of P/V ratios in VP SPECT

Dual Energy Imaging for Optimisation of P/V Ratios in VP SPECT

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Cut-off value for normal versus abnormal right-to-left shunt percentages using 99mTc-macroaggregated albumin

Abstract: The normal range (mean±2 SD) was 6.64±1.88%. The cut-off value for the normal right-to-left shunt percentage in MAA scintigraphy was 10%.

Cited by 15 publications

References 0 publications

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

99mTc-MAA Pulmonary Scintigraphy in Hereditary Hemorrhagic Telangiectasia

Dual energy window imaging for optimisation of P/V ratios in VP SPECT

Dual Energy Imaging for Optimisation of P/V Ratios in&nbsp;VP SPECT

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Dual Energy Imaging for Optimisation of P/V Ratios in VP SPECT