Scintigraphy and angiography in pulmonary embolism

Area of Science:

• Radiology
• Nuclear Medicine
• Cardiovascular Imaging

Background:

• Acute pulmonary embolism (PE) is a critical condition requiring accurate diagnostic assessment.
• Evaluating the extent of embolization is crucial for patient management and prognosis.
• Ventilation-perfusion (V/Q) scintigraphy and pulmonary angiography are imaging modalities used to diagnose PE.

Purpose of the Study:

• To compare the accuracy of V/Q scintigraphy and pulmonary angiography in quantifying the extent of acute pulmonary embolism.
• To investigate potential discrepancies between the two methods, particularly in cases with non-obstructing central emboli.

Main Methods:

• Pulmonary artery angiography was performed within 6 hours of V/Q scintigraphy in 14 patients with acute PE.
• An embolic scoring system (maximum 20) was used to quantify the extent of embolization by both methods.
• Correlation and agreement between scintigraphic and angiographic embolic scores were analyzed.

Main Results:

• A moderate correlation (r=0.47) was observed between V/Q scintigraphy and pulmonary angiography embolic scores, with significant differences (p<0.05).
• Excluding cases with non-complete obstructing central emboli improved the correlation (r=0.79) and rendered score differences non-significant (mean scores: V/Q=9.7, Angio=10.1).
• In cases with non-complete obstructing central emboli, V/Q scintigraphy significantly underestimated the embolic burden compared to angiography (mean scores: V/Q=9.0, Angio=16.2, p<0.01).

Conclusions:

• V/Q scintigraphy and pulmonary angiography show correlation in assessing PE extent.
• V/Q scintigraphy may underestimate the severity of PE, especially when central pulmonary arteries have non-complete obstructing emboli.
• Pulmonary angiography provides a more accurate assessment in complex cases of central embolization.