Measurement of tumor diameter-dependent mobility of lung tumors by dynamic MRI

Abstract

Background and purposeTo assess the influence of tumor diameter on tumor mobility and motion of the tumor bearing hemithorax during the whole breathing cycle in patients with stage I non-small-cell lung cancer (NSCLC) using dynamic MRI. Patients and methodsBreathing cycles of thirty-nine patients with solitary NSCLCs were examined using a trueFISP sequence (three images per second). Patients were divided into three groups according to the maximal tumor diameter in the transverse plane (<3, 3–5 and >5cm). Continuous time–distance curves and deep inspiratory and expiratory positions of the chest wall, the diaphragm and the tumor were measured in three planes. Motion of tumor-bearing and corresponding contralateral non-tumor bearing regions was compared. ResultsPatients with a tumor >3cm showed a significantly lower diaphragmatic motion of the tumor bearing compared with the non-tumor bearing hemithorax in the craniocaudal (CC) directions (tumors 3–5cm: 23.4±1.2 vs 21.1±1.5cm (P<0.05); tumors >5cm: 23.4±1.2 vs 20.1±1.6cm (P<0.01). Tumors >5cm in the lower lung region showed a significantly lower mobility compared with tumors <3cm (1.8±1.0 vs 3.8±0.7cm, P<0.01) in the CC directions. ConclusionsDynamic MRI is a simple non-invasive method to differentiate mobility of tumors with different diameters and its influence on the surrounding tissue. Tumor diameter has a significant influence on tumor mobility and this might be taken into account in future radiotherapy planning.