Morphological Predictors of Primary Lung Cancer among Part-Solid Ground-Grass Nodules on High-Resolution CT

Morphological Predictors of Primary Lung Cancer among Part-Solid Ground-Grass Nodules on High-Resolution CT

Hirotsugu Notsuda,¹ Hiroki Oshio,² Ken Onodera,¹ Takashi Hirama,¹ Yui Watanabe,¹ Tatsuaki Watanabe,¹ Takaya Suzuki,¹ Hisashi Oishi,¹ Hiromichi Niikawa,¹ Ryoko Saito-Koyama,³ Masafumi Noda,¹ Junya Tominaga⁴ and Yoshinori Okada¹

¹Department of Thoracic Surgery, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Miyagi, Japan
²Department of Thoracic Surgery, Isawa Hospital, Mizusawa, Iwate, Japan
³Department of Pathology, National Hospital Organization, Sendai Medical Center, Sendai, Miyagi, Japan
⁴Department of Diagnostic Radiology, Tohoku University Hospital, Sendai, Miyagi, Japan

Recent advancements in computed tomography (CT) scanning have improved the detection rates of peripheral pulmonary nodules, including those with ground-glass opacities (GGOs). This study focuses on part-solid pure ground-glass nodules (GGNs) and aims to identify imaging predictors that can reliably differentiate primary lung cancer from nodules with other diagnoses among part-solid GGNs on high-resolution CT (HRCT). A retrospective study was conducted on 609 patients who underwent surgical treatment or observation for lung nodules. Radiological findings from pre-operative HRCT scans were reviewed and several CT imaging features of part-solid GGNs were examined for their positive predictive value to identify primary lung cancer. The proportions of the nodules with a final diagnosis of primary lung cancer were significantly higher in part-solid GGNs (91.9%) compared with solid nodules (70.3%) or pure GGNs (66.7%). Among CT imaging features of part-solid GGNs that were evaluated, consolidation-to-tumor ratio (CTR) < 0.5 (98.1%), pleural indentation (96.4%), and clear tumor border (96.7%) had high positive predictive value to identify primary lung cancer. When two imaging features were combined, the combination of CTR < 0.5 and a clear tumor border was identified to have 100% positive predictive values with a sensitivity of 40.8%. Thus we conclude that part-solid GGNs with a CTR < 0.5 accompanied by a clear tumor border evaluated by HRCT are very likely to be primary lung cancers with an acceptable sensitivity. Preoperative diagnostic procedures to obtain a pathological diagnosis may potentially be omitted in patients harboring such part-solid GGNs.

Key words —— computed tomography; consolidation-to-tumor ratio; ground-glass nodule; high-resolution CT; lung cancer

===============================

Tohoku J. Exp. Med., 2024 May, 263(1), 35-42.

*These two authors contributed equally to this work.

Correspondence: Hirotsugu Notsuda, Department of Thoracic Surgery, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.

e-mail: hirotsugu.notsuda.c4@tohoku.ac.jp