Contribution of CAD to the Sensitivity for Detecting Lung Metastases on Thin-Section CT – A Prospective Study with Surgical and Histopathological Correlation

Abstract

Purpose To assess the sensitivity of radiologists and a CAD system for the detection of lung metastases on thin-section computed tomographic (CT) scans prior to pulmonary metastasectomy.

Materials and Methods All patients scheduled for resection of lung metastases were eligible for this prospective single-center trial. 95 patients with 115 surgical procedures (pulmonary metastasectomy using thoracotomy) were included. An experienced radiologist examined the CT scans for pulmonary metastases and documented his findings. A commercial CAD system was used as a second reader; additional CAD findings were recorded. A comparison of the sensitivity of the radiologist alone and with CAD was performed. Intraoperatively surgeons tried to identify the documented lesions and resected them as well as additionally palpable lesions. The standard of reference consisted of surgery and histopathology. Follow-up information for radiologically detected lesions missed during surgery was sought.

Results 693 lesions (262 metastases) were detected radiologically or surgically, 646 of them were resected. The sensitivity of radiologists without CAD was 67.5 % for all lesions (87.4 % for metastases). CAD highly significantly (p < 0.001) increased the sensitivity to 77.9 % (92.7 %). During surgery, 143 additional lesions (19 metastases) were detected. 49 radiologically detected lesions were not palpable during surgery: 4 metastases, 5 benign lesions, and 40 lesions of an unknown nature.

Conclusion CAD provides significant additional sensitivity for detecting lung metastases using MDCT compared to the performance of a radiologist alone. CT reveals a relevant number of non-palpable pulmonary lesions.

Key Points: 

• CAD significantly increased the sensitivity for the detection of lung metastases on CT.

• Surgical palpation of the lungs missed 8.5 % of all radiologically detected lesions.

• CT with CAD may increase the chance for complete metastasectomy.

Citation Format

• Meybaum C, Graff M, Fallenberg EM et al. Contribution of CAD to the Sensitivity for Detecting Lung Metastases on Thin-Section CT – A Prospective Study with Surgical and Histopathological Correlation. Fortschr Röntgenstr 2020; 192: 65 – 73

Zusammenfassung

Ziel Bestimmung der Sensitivität von Radiologen und eines CAD-Systems für die Detektion von Lungenmetastasen im Dünnschicht-CT vor geplanter pulmonaler Metastasenresektion.

Material und Methoden Für diese monozentrische prospektive Studie waren alle für eine pulmonale Metastasenresektion vorgesehenen Patienten geeignet. 95 Patienten mit 115 via Thorakotomie durchgeführten Operationen wurden eingeschlossen. Ein erfahrener Radiologe dokumentierte alle von ihm im CT detektierten metastasensuspekten Herde. Ein kommerzielles CAD-System wurde als second reader eingesetzt, und zusätzliche Befunde wurden ebenfalls aufgezeichnet. Die Sensitivität des Radiologen ohne und mit CAD wurde verglichen. Während der Operation wurde versucht, die präoperativ dokumentierten Befunde zu lokalisieren, und sie wurden inklusive der zusätzlich palpierten Herde reseziert. Der Referenzstandard für die Auswertung bestand in den histopathologischen Befunden der resezierten Herde. Informationen über den weiteren Verlauf radiologisch detektierter, aber chirurgisch nicht gefundener Läsionen wurden beschafft, wo immer das möglich war.

Ergebnisse 693 Herde (262 Metastasen) wurden radiologisch oder chirurgisch detektiert, 646 von ihnen wurden reseziert. Die Sensitivität der Radiologen ohne CAD war 67,5 % für alle Herde (87,4 % für Metastasen). CAD verbesserte die Sensitivität hochsignifikant auf 77,9 % (92,7 %). Intraoperativ wurden 143 zusätzliche Herde detektiert (19 Metastasen). 49 radiologisch detektierte Läsionen wurden intraoperativ nicht gefunden: 4 Metastasen, 5 benigne Herde, das biologische Verhalten der übrigen 40 Herde ist unbekannt.

Schlussfolgerung CAD erhöht die Sensitivität der Detektion von Lungenmetastasen signifikant im Vergleich zum Radiologen ohne CAD. Die CT detektiert eine relevante Zahl nicht palpabler pulmonaler Herde.

Kernaussagen: 

• CAD verbessert die Sensitivität der Detektion von Lungenmetastasen im CT signifikant.

• Intraoperativ konnten 8,5 % aller radiologisch detektierten Lungenherde nicht palpiert werden.

• Die intraoperative Verwendung von CT + CAD erhöht die Chance auf eine komplette Metastasenresektion.

Key words

thorax - CT - metastases - neoplasms - observer performance

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