Abstract
ObjectiveThis study aimed to evaluate the visibility of different subgroups of lung nodules of <3 cm using the pointwise encoding time reduction with radial acquisition (PETRA) sequence on 3T magnetic resonance imaging (MRI) in comparison with that obtained using low-dose computed tomography (LDCT).MethodsThe appropriate detection rate was calculated for each of the different subgroups of lung nodules of <3 cm. The mean diameter of each detected nodule was determined. The detection rates and diameters of the lung nodules detected by MRI with the PETRA sequence were compared with those detected by computed tomography (CT). The sensitivity of detection for the different subgroups of pulmonary nodules was determined based on the location, size, type of nodules and morphologic characteristics. Agreement of nodule characteristics between CT and MRI were assessed by intraclass correlation coefficient (ICC) and Kappa test.ResultsThe CT scans detected 256 lung nodules, comprising 99 solid nodules (SNs) and 157 subsolid nodules with a mean nodule diameter of 8.3 mm. For the SNs, the MRI detected 30/47 nodules of <6 mm in diameter and 52/52 nodules of ≥6 mm in diameter. For the subsolid nodules, the MRI detected 30/51 nodules of <6 mm in diameter and 102/106 nodules of ≥6 mm in diameter. The PETRA sequence returned a high detection rate (84%). The detection rates of SN, ground glass nodules, and PSN were 82%, 72%, and 94%, respectively. For nodules with a diameter of >6 mm, the sensitivity of the PETRA sequence reached 97%, with a higher rate for nodules located in the upper lung fields than those in the middle and lower lung fields. Strong agreement was found between the CT and PETRA results (correlation coefficients = 0.97).ConclusionThe PETRA technique had high sensitivity for different type of nodule detection and enabled accurate assessment of their diameter and morphologic characteristics. It may be an effective alternative to CT as a tool for screening and follow up pulmonary nodules.
Highlights
Pulmonary nodules are common findings in individuals with an elevated risk for lung cancer
The capability of the pointwise encoding time reduction with radial acquisition (PETRA) sequence in nodule detection was as effective as computed tomography (CT), and the PETRA sequence achieved high sensitivity (84%) for nodule detection
PETRA sequence in detecting ground glass nodules (GGNs), which is similar to the results reported by Ohno et al [35]
Summary
Pulmonary nodules are common findings in individuals with an elevated risk for lung cancer. The National Lung Screening Trial demonstrated the benefits of using multislice computed tomography (CT) for lung cancer screening in a high-risk population. This approach was shown to reduce lung cancer-associated mortality by up to 20% [3, 4]. Results of NELSON trial showed that lung-cancer mortality was significantly lower among those who underwent volume CT screening than among those who underwent no screening [5] This technique has high spatial resolution and good contrast between air and lung tissues, repetitive use of CT increases the risk of developing cancer due to ionizing radiation exposure, in patients who require reviews on multiple occasions over a prolonged period [6, 7]
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