MRI STUDY OF THE LIGAMENTUM ARTERIOSUM AN D OF THE LEFT PULMONARY-ARTERY IN PREOPERATIVE STAGING OF LEFT UPPER LOBE BRONCHIAL CANCERS

Purpose: to demonstrate that the ligamentum arteriosum is visible by p recisely-oriented MRI. To demonstrate the predictive value of the liga ment involvement for left upper robe cancer surgery. Material and meth ods: fifteen controls, age-matched with bronchial cancer patients, wer e studied to establish how the ligamentum arteriosum could best be vis ualized on MRI. Visibility was optimal on RASE T1-weighted sequences o n the frontal and sagittal oblique planes (aorto-pulmonary window). Ac quisitions were performed with a body coil, 7 mm slices, 480 mm Fov, o n a Magnetom Expert, 1T Siemens machine. Forty five patients with left upper lobe cancer underwent MRI investigation after CT had shown medi astinal proximity of the left pulmonary artery and the tumor. They und erwent surgery with manual localization of the ligament at the beginni ng of the procedure. Findings and operative decisions were compared wi th those of MRI, establishing its predictive value. MRI defined the tu mor-ligament and tumor first centimeters of the left pulmonary artery (LPA) relationships. Results: MRI ligamentum visibility was about 87 % . Ligament non-involvement on MRI (n = 23) was confirmed at surgery in all cases (100 % concordance). Involvement suggested on MRI was confi rmed in 18 cases and surgery was impossible or unsatisfactory. There w ere four false-positives with successful surgery (8 % false positives) . Conclusion: when CT shows left lobe cancers extending in the mediast inum towards the LPA, precisely-oriented MRI assesses surgical difficu lty and resectability by demonstration involvement of the ligamentum a nd the first two centimeters of the LPA.