Semi-automated Analysis of Ventilation-Perfusion Single-Photon Emission Tomography in the Diagnosis of Pulmonary Embolism – Does it add extra value?

Abstract

Aim Diagnosis of pulmonary embolism using V/P-SPECT may include the application of advanced image-processing techniques to identify V/P-mismatches. Aim of this study was to evaluate the benefit in clinical decision making in the diagnosis of pulmonary embolism.by whether adding to conventional reading a software that automatically calculates and visualizes the ventilation/perfusion-quotient pixel by pixel.

Methods 63 consecutive patients with a clinical suspicion of PE who underwent V/P-SPECT were included in this retrospective study. Images were randomly ordered both for standard as well as for software-assisted reading using V/P-quotients. Studies were read independently by 2 experienced and 2 inexperienced raters. Diagnostic performance and observer agreement of all readers and both reading methods were determined.

Results Expert observers consistently achieved a high diagnostic accuracy both in conventional as well as in software-assisted reporting (sensitivity: 0.94 vs. 0.94, specificity: 0.96 vs. 0.97, LR⁺: 17.32 vs. 28.86, LR^– stayed constant at 0.06). For inexperienced readers, diagnostic performance improved: sensitivity raised from 0.74 to 0.85 and specificity from 0.86 to 0.95, LR⁺ raised from 5.20 to 15.69, LR^– decreased from 0.31 to 0.16. Inter-rater reliability (Fleiss’ κ) improved from 0.63 to 0.86 by using V/P quotient.

Conclusion Benefit from a software-tool that calculates V/P-ratio automatically is only small when used by experienced physicians If inexperienced readers use the software, the diagnostic accuracy increases. Images generated by automated calculation of V/P-mismatches are easy to read and their use might help to standardize and objectify interpretation of V/P-SPECT in the diagnosis of PE.

Zusammenfassung

Ziel Die Diagnostik der Lungenembolie mittels V/P-SPECT kann durch bildverarbeitende Techniken zur Identifizierung von V/P-Mismatches unterstützt werden. Ziel dieser Studie war es zu beurteilen, ob die Nutzung einer semiautomatisierten Software, die den Ventilations-/Perfusions-Quotienten berechnet und visualisiert, einen Zusatznutzen hinsichtlich der diagnostischen Genauigkeit bringt.

Methodik 63 konsekutive Patienten, die eine V/P-SPECT wegen des klinischen Verdachts einer PE erhielten, wurden in die retrospektive Studie eingeschlossen. Die Datensätze wurden randomisiert und von je 2 erfahrenen und unerfahrenen Befundern nach konventioneller Methode sowie unter zusätzlicher Anwendung des V/P-Quotienten befundet. Die diagnostische Performance und das Maß der Übereinstimmung aller 4 Befunder wurde für beide Befundungsmethoden verglichen.

Ergebnisse Erfahrene Befunder erreichten eine hohe Genauigkeit in der Befundung, sowohl mittels der konventionellen Methode als auch unter zusätzlicher Nutzung des V/P-Quotienten (Sensitivität: 0,94 vs. 0,94; Spezifität: 0,96 vs. 0,97; LR⁺ 17,32 vs. 28,86; die LR^– blieb konstant bei 0,06). In der Gruppe der unerfahrenen Befunder zeigte sich hingegen eine deutliche Verbesserung der diagnostischen Genauigkeit (Sensitivität 0,74 vs. 0,85; Spezifität 0,86 vs. 0,95; LR⁺ 5,20 vs. 15,69; LR^– 0,31 vs. 0,16) und das Maß der Übereinstimmung aller Befunder (Fleiss‘ κ) verbesserte sich von 0,63 auf 0,86, wenn der V/P-Quotient hinzugezogen wurde.

Schlussfolgerung Erfahrene Ärzte profitieren nicht von der zusätzlichen Nutzung des V/P-Quotienten. Angewendet durch unerfahrene Befunder erhöht sich hingegen die diagnostische Genauigkeit. Die Bilder des V/P-Quotienten sind einfach zu interpretieren und können helfen, die Interpretation der V/P-SPECT bei der Diagnose der PE zu standardisieren und zu objektivieren.

Key words

pulmonary embolism - V/P SPECT - image processing - software-assisted - V/P quotient

Schlüsselwörter

Lungenarterienembolie - V/P-SPECT - Bildverarbeitung - Softwareunterstützt - V/P-Quotient

Publication History

Article published online:
29 September 2020

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