Progressive massive fibrosis in patients with pneumoconiosis: utility of MRI in differentiating from lung cancer.

Background It is occasionally difficult to distinguish progressive massive fibrosis (PMF) from lung cancer on computed tomography (CT) in patients with pneumoconiosis. Purpose To evaluate the magnetic resonance imaging (MRI) features of PMF and to assess its ability to differentiate PMF from lung cancer. Material and Methods Between 2000 and 2014, 40 pulmonary lesions suspected to be lung cancer on the basis of CT in 28 patients with known pneumoconiosis were evaluated. Twenty-four of the 40 lesions were pathologically or clinically diagnosed as PMF. The signal pattern on T2-weighted (T2W) images, post-contrast enhancement pattern on T1-weighted (T1W) images, and the pattern of the time intensity curve (TIC) on contrast-enhanced dynamic studies were evaluated. All images were analyzed independently by two chest radiologists. Results All 24 PMF lesions showed low signal intensity (SI) on T2W images (sensitivity, 100%), while 15 of 16 lung cancer lesions showed intermediate or high SI on T2W images (specificity, 94%) when PMF was regarded as a positive result. Six of 17 PMF lesions showed a homogeneous enhancement pattern (sensitivity, 35%), and 4/9 lung cancer lesions showed an inhomogeneous or a ring-like enhancement pattern (specificity, 44%). Six of 16 PMF lesions showed a gradually increasing enhancement pattern (sensitivity, 38%), and 7/9 lung cancer lesions showed rapid enhancement pattern (specificity, 78%). Conclusion When differentiation between PMF and lung cancer in patients with pneumoconiosis is difficult on CT, an additional MRI study, particularly the T2W imaging sequence, may help differentiate between the two.

Comparison between solid component size on thin-section CT and pathologic lymph node metastasis and local invasion in T1 lung adenocarcinoma.

OBJECTIVES: To correlate the tumor size and solid component size on thin-section CT (TS-CT) with pathological findings including lymph node (LN) metastasis and local invasion in T1 lung adenocarcinoma. METHODS: 188 patients with surgically resected T1 lung adenocarcinoma were retrospectively analyzed. Two chest radiologists measured the long-axis and short-axis dimensions of nodules and solid components with a lung and/or a mediastinal window setting (WS) on TS-CT. After analyzing interobserver agreement, average long-axis dimensions of the measured tumors and solid components were correlated with pathological findings. RESULTS: Seven of 188 patients (3.7%) had pathologic LN-positive metastasis. In patients in whom the long axis of the solid component was <5 mm with a mediastinal WS or <8 mm with a lung WS on TS-CT, no LN metastases were observed, resulting in a positive predictive value (PPV) for predicting a pathologic LN-negative status of 100% with each WS. Based on the same diagnostic criteria, the PPVs for a pathological local invasion (LI)-negative status were 91 (40/44) and 90% (55/61), respectively. CONCLUSION: Solid component size on TS-CT may have the potential to predict LN-negative or LI-negative status.

The phrenic nerve with accompanying vessels: a silent cause of cardiovascular border obliteration on chest radiography.

PURPOSE: Our aim was to clarify the frequency of cardiovascular border obliteration on frontal chest radiography and to prove that the phrenic nerve with accompanying vessels can be considered as a cause of obliteration of cardiovascular border on an otherwise normal chest radiography. MATERIALS AND METHODS: Two radiologists reviewed chest radiographs and computed tomography (CT) images of 100 individuals. CT confirmed the absence of intrapulmonary or extrapulmonary abnormalities in all of them. We examined the frequency of cardiovascular border obliteration on frontal chest radiography and summarized the causes of obliteration as pericardial fat pad, phrenic nerve, intrafissure fat, pulmonary vessels, and others, comparing them with CT in each case. RESULTS: Cardiovascular border was obliterated on frontal chest radiography in 46 cases on the right and in 61 on the left. The phrenic nerve with accompanying vessels was found to be a cause of obliteration in 34 of 46 cases (74%) on the right and 29 of 61 (48%) cases on the left. The phrenic nerve was the most frequent cause of cardiovascular border obliteration on both sides. CONCLUSION: The phrenic nerve with accompanying vessels, forming a prominent fold of parietal pleura, can be attributed as a cause of cardiovascular border obliteration on frontal chest radiography.