Diagnostic accuracy of true fast imaging with steady-state precession, MR pulmonary angiography and volume-interpolated body examination for pulmonary embolism compared with CT pulmonary angiography.

The diagnostic performance of magnetic resonance (MR) sequences for displaying different levels of pulmonary artery involvement in pulmonary embolism (PE) has rarely been reported but is essential for critically ill and emergency patients. The aim of the present study was to analyze the diagnostic accuracy of true fast imaging with steady-state precession (true FISP), MR pulmonary angiography (MRPA) and volume-interpolated body examination (VIBE) for PE detection in comparison to CT pulmonary angiography (CTPA), which is the reference standard. A total of 21 patients with confirmed deep venous thrombosis suspected of having PE were enrolled. Emboli were evaluated on per-patient and per-vessel bases. The evidence of PE on a per-vessel basis was classified into central, lobar and segmental levels, and 27 vessel segments per patient were analyzed for a total of 567 vessel segments in all patients. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. Receiver operating characteristic curves were drawn to compare differences in sequences. A total of 158 pulmonary vessels were involved with emboli on CTPA, 58 of which were identified by true FISP, 63 by MRPA and 94 by VIBE. On per-patient and per-vessel bases, the sensitivity was 81.3 and 36.7%, respectively, for true FISP, 82.4 and 56.3%, respectively, for MRPA, and 94.4 and 68.1%, respectively, for VIBE; the specificity was 80.0 and 99.8%, respectively, for true FISP, 100 and 99.2%, respectively, for MRPA, and 100 and 99.2%, respectively, for VIBE. The respective PPV was 92.9 and 98.3% for true FISP, 100 and 95.5% for MRPA, 100 and 96.9% for VIBE. The NPV was 57.1 and 80.3%, respectively, for true FISP, 50.0 and 88.2%, respectively, for MRPA, and 75.0 and 89.8%, respectively, for VIBE. In conclusion, enhanced VIBE surpassed the other two sequences in revealing PE, particularly in segmental analysis, which is essential for emergency patients who have contraindications for receiving iodinated contrast and those who have concerns about the ionizing radiation.

Fat-suppressed magnetic resonance volume interpolated examination for deep venous thrombosis compared with duplex sonography.

The aim of the present study was to evaluate magnetic resonance venography (MRV) scanned by breath-hold volume interpolated body examination with spectral fat saturation (VIBE-fs), combined with Dixon fat-suppressed VIBE (VIBE-Dixon) by using a 1.5T MR scanner for detecting deep venous thrombosis (DVT) compared with duplex sonography. A total of 31 patients with DVT were identified using duplex sonography and were enrolled in the present study for MRV examination, from the inferior vena cava to the ankle level after injection of gadopentetate dimeglumine. Venous segment-to-segment comparison was assessed for DVT detection between MRV and duplex sonography. A total of two radiologists separately performed subjective image quality assessment using a 5-point scale. Cohen's κ coefficient, Wilcoxon rank sum test and intraclass correlation coefficient values were used for statistical analysis. Of the 303 evaluated vein segments, duplex sonography identified 119 (39.3%; 119/303) venous segments with thrombus, while MRV detected 170 (56.1%; 170/303) venous segments with thrombus. The diagnostic agreement rate of DVT between duplex sonography and MRV was poor in the deep femoral vein and anterior tibial veins, while it was excellent in the inferior vena cava (IVC), common iliac vein, external iliac vein, femoral vein, popliteal vein, posterior tibial veins and peroneal veins. In addition, poor reliability was detected in the deep femoral vein, anterior tibial veins and peroneal veins, but good to excellent reliability was observed in IVC, common iliac vein, external iliac vein, femoral vein, popliteal vein and posterior tibial veins. Furthermore, image quality scores of each venous segment between the two radiologists indicated no statistical difference. Therefore, MRV scanned using VIBE-fs for the suprainguinal and VIBE-Dixon for the infrainguinal region may be a useful method for detecting DVT compared with duplex sonography. The results of present study proved this MR protocol to be a beneficial alternative imaging modality for the detection of DVT when duplex sonography is inadequate or not able to be performed.

Comparative study of StarGVIBE and VIBE sequences in MRI of esophagus / 实用放射学杂志

Objective To explore the feasibility of the Star-VIBE sequence in esophageal MRI,and compare it with the conventional VIBE sequence.Methods Fifteen healthy volunteers underwent Star-VIBE and VIBE sequences scanning after injecting MRI contrast agent.Two groups of MR images were independently scored in the ability to display esophageal wall,respiratory motion artifacts,cardiovascular pulsation artifacts,overall motion artifacts and overall image quality by the two radiologists,respectively.SNR of esophagus,CNR between esophagus and paravertebral muscles were measured and compared.Results Star-VIBE was superior to VIBE in the ability to display esophageal wall,respiratory motion artifacts,cardiovascular pulsation artifacts,overall motion artifacts and overall image quality (the ability to display esophageal wall:Z＝－3.268,P＝0.001;respiratory motion artifacts:Z＝－3.205,P＝0.001;cardiovascular pulsation artifacts:Z＝－4.644, P＝0.000;overall motion artifacts:Z＝－3.904,P＝0.000;overall image quality:Z＝－2.808,P＝0.005),while no significant differences were found on SNR and CNR between the two sequences (SNR:t＝－1.5 3 9 ,P＝0.1 3 5 ;CNR:t＝－0.874,P＝0.3 89 ).Conclusion The Star-VIBE sequence is insensitive to the physiological motion artifacts,and it can provide better image quality than the conventional VIBE sequence in esophageal MRI.