MR Imaging of Pulmonary Nodules: Detection Rate and Accuracy of Size Estimation in Comparison to Computed Tomography

<div><p>Objective</p><p>The aims of this study were to assess the sensitivity of various magnetic resonance imaging (MRI) sequences for the diagnosis of pulmonary nodules and to estimate the accuracy of MRI for the measurement of lesion size, as compared to computed tomography (CT).</p><p>Methods</p><p>Fifty patients with 113 pulmonary nodules diagnosed by CT underwent lung MRI and CT. MRI studies were performed on 1.5T scanner using the following sequences: T2-TSE, T2-SPIR, T2-STIR, T2-HASTE, T1-VIBE, and T1-out-of-phase. CT and MRI data were analyzed independently by two radiologists.</p><p>Results</p><p>The overall sensitivity of MRI for the detection of pulmonary nodules was 80.5% and according to nodule size: 57.1% for nodules ≤4mm, 75% for nodules >4-6mm, 87.5% for nodules >6-8mm and 100% for nodules >8mm. MRI sequences yielded following sensitivities: 69% (T1-VIBE), 54.9% (T2-SPIR), 48.7% (T2-TSE), 48.7% (T1-out-of-phase), 45.1% (T2-STIR), 25.7% (T2-HASTE), respectively. There was very strong agreement between the maximum diameter of pulmonary nodules measured by CT and MRI (mean difference -0.02 mm; 95% CI –1.6–1.57 mm; Bland-Altman analysis).</p><p>Conclusions</p><p>MRI yielded high sensitivity for the detection of pulmonary nodules and enabled accurate assessment of their diameter. Therefore it may be considered an alternative to CT for follow-up of some lung lesions. However, due to significant number of false positive diagnoses, it is not ready to replace CT as a tool for lung nodule detection.</p></div

Parameters of the applied MRI sequences.

<p>Parameters of the applied MRI sequences.</p

The Bland-Altman plot showing the agreement between the maximum diameter of 91 pulmonary nodules measured by both CT and MRI.

<p>The Bland-Altman plot showing the agreement between the maximum diameter of 91 pulmonary nodules measured by both CT and MRI.</p

A 71-year-old man with 11.3 mm pulmonary nodule in the right lower lobe (arrow).

<p>The nodule is well visualized on CT (A) as well as on all MR images: T1 VIBE (B), T1 out-of-phase (C), T2 TSE (D), T2 HASTE (E), T2 SPIR (F), T2 STIR (G).</p

The sensitivity of MRI for the detection of different subgroups of pulmonary nodules (according to the Fleischner Society nodule size category).

<p>The sensitivity of MRI for the detection of different subgroups of pulmonary nodules (according to the Fleischner Society nodule size category).</p

A 77-year-old woman with 2.8 mm pulmonary nodule (arrow) in the left upper lobe (lingula).

<p>The nodule is well depicted on MDCT image (A), however it was not identified on corresponding MR images: T1 VIBE (B), T1 out-of-phase (C), T2 TSE (D), T2 HASTE (E), T2 SPIR (F), T2 STIR (G).</p

A 71-year-old woman with 7 mm pulmonary nodule in the right upper lobe (arrow).

<p>The nodule is demonstrated on CT (A) and on most of T2-weighted sequences, including: T2 TSE (D), T2 SPIR (F) and T2 STIR (G). The readers did not identify this lesion on T1 VIBE (B), T1 out-of-phase (C) and T2 HASTE (E) images.</p