New method for measuring right-left shunt fraction by quantitative analysis using SPECT/CT images

Area of Science:

• Nuclear Medicine
• Radiology
• Medical Imaging

Background:

• A quantitative method for measuring right-left shunt fraction using SPECT/CT images was developed.
• Pulmonary perfusion scintigraphy is a key diagnostic tool.

Purpose of the Study:

• To devise and validate a quantitative method for measuring right-left shunt fraction using SPECT/CT.
• To compare the accuracy of the quantitative method with whole-body planar imaging.

Main Methods:

• 43 patients underwent pulmonary perfusion scintigraphy with 99mTc-macroaggregated albumin.
• Quantitative analysis calculated lung radioactivity dose and lung uptake proportion.
• Right-left shunt fraction was determined by subtracting lung uptake from total dose and compared to whole-body imaging results.

Main Results:

• No significant difference was found between methods in cases without shunts (p = 0.55).
• In cases with shunts, the quantitative method showed a significantly higher shunt fraction (29.1% ± 10.2%) compared to whole-body imaging (19.0% ± 6.0%, p < 0.05).
• The quantitative method achieved an AUC of 0.948 and 93.0% accuracy with a 19%-22% threshold.

Conclusions:

• The quantitative SPECT/CT method significantly improves shunt fraction measurement accuracy compared to whole-body imaging when shunts are present.
• An accuracy exceeding 90% is achievable with a threshold range of 19%-22%, indicating clinical utility for diagnosis.
• This method aids in assessing shunt severity, evaluating treatment, and imaging challenging cases, with expected clinical application.