Characteristics and clinical value of 3D MR imaging in the diagnosis of pulmonary embolism

The Role of Whole-Body Magnetic Resonance Imaging (WB-MRI) in Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH)

In PNH thromboembolic events (TEs) represent the leading cause of morbidity and mortality. Between Dec 2013 and Jan 2016 37 PNH patients (pts) (23 PNH, 14 AA/PNH; 51% (19/37) females; median age 44 years, median D-dimer levels 0.22 mg/l) were examined with a whole-body magnetic resonance imaging (WB-MRI) scan at 1.5 T to detect TEs. Pts were treated according to German PNH guidelines, including eculizumab therapy. 64% (24/37) of the pts had no documented TEs prior to observation. Two pts had suspected TEs in their clinical history. 29% of the pts (11/37) had a known history of venous thromboses (deep venous thrombosis (DVT) (5/11), portal venous thrombosis (PVT) (4/11), vena caval thrombosis (VCT) (2/11). A myocardial infarction was reported in one pt, and two had a cerebral venous sinus thrombosis (CVST) or a thalamic infarction. Six pts (16%) had at least two prior TEs. In pts with prior TEs no progression of the existing TEs was observed. In pts on eculizumab and prior TEs as well as treatment-naïve pts silent bone and renal infarctions were detected. Furthermore, a clinically non-critical arterial occlusion was identified. WB-MRI scans present a novel, non-invasive method to assess the complete vascular status of PNH pts and allow the detection of previously undiagnosed vascular complications, affecting treatment indications and regimens.

Comparison between CT and MRI in the assessment of pulmonary embolism: A meta-analysis

OBJECTIVE

Besides pulmonary arteriography, a number of imaging techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT), were adopted in the detection of identifying pulmonary embolism (PE). However, the contrast of sensitivity and specificity in these methods was studied little in a statistical way. To compare the effects of MRI and CT, this study used a series of methods to analyze data in included researches.

METHODS

A comprehensive computer search was conducted through internet up to July 2016. The quality assessment was performed by the Quality Assessment Tool for Diagnostic Accuracy Studies, version 2 tool. The diagnostic value of comparison between MRI and CT was evaluated by using the pooled estimate of sensitivity, specificity, and summary receiver operating characteristic (SROC) curve. In addition, sensitivity analysis and bias analysis were applied to ensure the accuracy of the results.

RESULTS

Ten studies with 590 cases were involved in the study. Only 2 trials had high risk regarding bias while other trials were supposed to be at low risk of applicability. Heterogeneity existed in analysis of both CT and MRI. The pooled sensitivity of CT was 0.90 (95% CI: 0.85-0.93), pooled specificity was 0.88 (95% CI: 0.77 to 0.95), the pooled sensitivity of MRI was 0.92 (95% CI: 0.89-0.94), and pooled specificity was 0.91 (95% CI: 0.77-0.97). The Q index of sensitivity and specificity for CT and MRI were 71.38, 19.67, 47.14, and 12.35, respectively. The SROC curve area under the curve of CT and MRI were 0.94 (95% CI: 0.91-0.96) and 0.93 (95% CI: 0.91-0.95), respectively.

CONCLUSION

This meta-analysis demonstrates that MRI has better sensitivity and specificity in detecting subsegmental artery PE. MRI is a relatively better detection technique for PE. This conclusion is consistent with many published researches.

Differential Diagnosis of Pulmonary Artery Sarcoma and Central Chronic Pulmonary Thromboembolism Using CT and MR Images

BACKGROUND

Clinical and imaging manifestations are similar in pulmonary artery sarcomas (PAS) and thromboembolic diseases, especially central chronic pulmonary thromboembolism (CPTE). The feasibility of utilising clinical imaging tools such as computed tomography (CT) and magnetic resonance imaging (MRI) for differential diagnosis of PAS and CPTE has not been fully explored, especially MRI.

METHODS

Patients with PAS (n=18) and central CPTE (n=20) treated at our hospital between January 2013 and September 2016 were identified retrospectively. Computed tomography and MRI findings of pulmonary artery (PA) filling defects including the location, the involvement of pulmonary artery, morphology, signal intensities and enhancement in MRI, calcification, sizes of right atrium and ventricle, inner diameters of the pulmonary artery trunk and branches, and mediastinal collateral circulation in both groups were examined, and differences were analysed by Fisher exact test and independent sample t-test.

RESULTS

Compared to those of central CPTE, PAS lesions were in full shape or expansive growth (p<0.001), and the proximal end of the tumours was often bulging or lobulated (p<0.001). These lesions were aneurysm- or grape-like distally (p<0.01) with inhomogeneous enhancement (p<0.001). The MRI contrast enhancement pattern of PAS lesions were cloudy with inhomogeneous delayed enhancement and the time-density curves for some of the lesions increased gradually.

CONCLUSION

Computed tomographic and MR imaging manifestations may resemble PAS and central CPTE; however, some manifestations still have great value for the differential diagnosis of these two conditions, specifically the morphology and MRI enhancement patterns.