Solitary Pulmonary Nodules: Dynamic Contrast-enhanced MR Imaging—Perfusion Differences in Malignant and Benign Lesions

Abstract

Dynamic MR imaging delineates significant kinetic and morphologic differences in vascularity and perfusion between malignant and benign solitary pulmonary nodules. Washout seems to be highly specific for malignancy.

Evaluation of Indeterminate Pulmonary Nodules with Dynamic MR Imaging

“…Granuloma and tuberculoma are considered to be less active in‰ammatory nodules, 3,4 and in our study, granuloma and tuberculoma were the primary constituents of benign pulmonary nodules,ˆndings similar to those of other reports. 2,3,6,8,10 Several recent dynamic MR imaging studies have examined early enhancement followed by washout in pulmonary nodules 5,8,9 and focused only secondarily on washout after contrast enhancement. They …”

“…Every measurement required a short inspiration breath hold of 4 s. In contrast to transverse images, sagittal images can depict nodules with all breath holds, even for slightly diŠerent inspiration levels, because the lateral to medial positional change of the nodules is minor. 5 A bolus injection lasting 4 s of gadodiamide (Daiichi Sankyo Co., Ltd., Tokyo, Japan; before June 2007) or gadoteridol (Eisai Co., Ltd., Tokyo, Japan; after July 2007) at a dose of 0.1 mmol per kilogram of body weight was administered through an antecubital vein followed by administration of 20 mL of 0.9z saline at the same rate through an automatic infusion system (Nemoto Kyorindo Co. Ltd., Tokyo, Japan). All 51 dynamic MR imaging studies were completed successfully without adverse eŠects.…”

“…reported the high speciˆcity of washout for malignancy 5 and the possibility that no washout might suggest benignancy. 8,9 In our study, however, washout characteristics indicated neither malignancy nor active in‰ammation, and the case of no washout showed no characteristics of benignancy.…”

“…1 Although the presence of intranodular fat or calciˆcation, lack of growth for at least 2 years, and disappearance or signiˆcant regression of nodules after initiation of antibacterial or steroid therapy are generally accepted as reliable signs of benignancy, otherˆnd-ings have not proven very useful in diŠerentiating malignant and benign nodules. 1 Dynamic evaluation with CT or magnetic resonance (MR) imaging has demonstrated stronger enhancement of malignant neoplasms than benign nodules, [2][3][4][5] and the overlap of early enhancement characteristics between malignant neoplasms and active in‰ammatory nodules by dynamic MR imaging or CT is recently reported. [6][7][8] More recently, researchers using MR imaging reported the absence of washout in most active in‰ammatory and benign nodules at the second or fourth minute from initiation of contrast injection.…”

The Effect of Lung Volume on Nodule Size on CT

“…In clinical practice, chest CT scans are routinely performed at suspended maximal inspiration, although expiratory breathholds are considered more reproducible (16). However, inspiratory volumes provide greater contrast between focal opacities and aerated lung, thus ensuring optimal delineation of pathology.…”