C-Arm Computed Tomography Adds Diagnostic Information in Patients with Chronic Thromboembolic Pulmonary Hypertension and a Positive V/Q SPECT

Abstract

Purpose To determine if C-Arm computed tomography (CACT) has added diagnostic value in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) with a positive mismatch pattern in ventilation/perfusion single photon emission computed tomography (V/Q SPECT).

Materials and Methods 28 patients (23 men, 5 women, 62 ± 18 years) with CTEPH who had undergone SPECT, followed by CACT and right heart catheterization (RHC) were included. Two independent readers reviewed SPECT and CACT. Findings indicating CTEPH and their location (segmental or sub-segmental) were identified (V/Q mismatch in SPECT and vascular pathologies in CACT). Inter-modality agreement was calculated (Cohen's Kappa). Findings were scored on a 3-point-scale. The sum of the score (pulmonary artery CTEPH severity score (PACSS)) was calculated for each patient and imaging modality, correlated to RHC (spearman's correlation) and compared to the final therapeutic decision of the CTEPH board (including the consensus of SPECT, selective pulmonary DSA and CACT).

Results Overall, 504 pulmonary artery segments were assessed in SPECT and CACT. SPECT had identified 266/504 (53 %) arterial segments without and 238/504 (47 %) segments with a V/Q mismatch indicating CTEPH. CACT detected 131/504 (26 %) segments without abnormal findings and 373/504 (74 %) segments with findings indicating CTEPH. Inter-modality agreement was fair (ĸ = 0.38). PACSS of CACT correlated mildly significantly with the mean pulmonary artery pressure (PAPmean; rho = 0.48, p = 0.01), while SPECT missed significance (rho = 0.32, p = 0.1). Discrepant findings were mostly attributed to a higher frequency of sub-segmental pulmonary arterial pathologies on CACT (145 sub-segmental findings indicating CTEPH) rated as normal on SPECT.

Conclusion In patients with CTEPH, contrast-enhanced CACT detects additional findings with a better correlation to the severity of PAPmean than V/Q SPECT. CACT indicates abnormalities even in segments without V/Q abnormalities.

Key points

• CACT has additional value in V/Q SPECT-positive CTEPH patients.

• SPECT may underestimate the extent of CTEPH.

• CACT indicates abnormalities even in segments without V/Q abnormalities.

Citation Format

• Hinrichs JB, Werncke T, Kaireit T et al. C-Arm Computed Tomography Adds Diagnostic Information in Patients with Chronic Thromboembolic Pulmonary Hypertension and a Positive V/Q SPECT. Fortschr Röntgenstr

Zusammenfassung

Ziele Evaluation der potentiellen diagnostischen Zusatzinformationen der pulmonalarteriellen C-Arm CT (CACT) bei Patienten mit chronisch thromboembolischer pulmonaler Hypertonie (CTEPH) und positivem Ventilations-/Perfusions-Mismatch in der Einzelphotonen-Emissionscomputertomografie (V/Q SPECT).

Material und Methoden 28 Patienten (23 Männer, 5 Frauen, 62 ± 18 Jahre) mit CTEPH wurden mittels SPECT, CACT und Rechtsherzkatheter (RHK) untersucht. Die SPECT und die CACT wurden von zwei unabhängigen Untersuchern beurteilt. Beide Untersuchungsmodalitäten wurden nach CTEPH-typischen Befunden ausgewertet, die Lokalisation der Befunde wurde bestimmt (segmental, sub-segmental) und mittels 3-Punktskala bewertet (pulmonary artery CTEPH severity score (PACSS)). Die Übereinstimmung der Modalitäten wurde berechnet (Cohen’s Kappa). Die Summe des PACSS wurde für jede Bildgebungsmodalität berechnet und mit der dem RHK korreliert (Spearman Korrelation). Außerdem wurde der PACSS mit der Therapieentscheidung des CTEPH-Boards verglichen (Grundlage: SPECT, selektive DSA und CACT).

Ergebnisse Insgesamt wurden 504 Pulmonalarteriensegmente in beiden Modalitäten untersucht. Die SPECT hat 266/504 (53 %) Segmente ohne Perfusionsausfälle und 238/504 (47 %) mit Perfusionsausfällen bewertet. Die CACT hat 131/504 (26 %) Segmente ohne CTEPH-typische Befunde bewertet, in 373/504 (74 %) Segmenten wurden CTEPH-typische Befunde erhoben. Die Übereinstimmung der Modalitäten hinsichtlich pathologischer Befunde war mäßig (ĸ = 0,38). Der PACSS_CACT korreliert signifikant mit dem mittleren pulmonalarteriellen Druck (rho = 0,48, p = 0,01), wohingegen der PACSS_SPECT keine signifikante Korrelation zeigt (rho = 0,32, p = 0,1). Die Abweichungen zwischen beiden Methoden sind hauptsächlich mit der höheren Detektionsrate der CACT von sub-segmentalen CTEPH-typischen Befunden zu erklären, diese wurden in der SPECT als normal bewertet.

Schlussfolgerung Die kontrastmittelverstärkte CACT weist im Vergleich zur SPECT zusätzliche CTEPH-typische Befunde mit einer besseren Korrelation zum pulmonalarteriellen Mitteldruck nach. Im Vergleich zur CACT unterschätzt die SPECT das Ausmaß und die Komplexität der vaskulären Befunde bei Patienten mit CTEPH.

Kernaussagen

• Die CACT hat einen zusätzlichen Nutzen bei CTEPH-Patienten mit positivem V/Q SPECT.

• Die SPECT kann das Ausmaß der CTEPH unterschätzen.

• Die CACT detektiert Befunde in Pulmonalarterien, die im V/Q SPECT keinen Befund aufweisen.

Key words

cone-beam computed tomography - chronic thromboembolic pulmonary hypertension - CTEPH - SPECT - lung perfusion - radiation exposure pulmonary CACT

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