Evaluation of the supraaortic arteries using non-contrast-enhanced Velocity MR angiography "Inhance"

Non-contrast magnetic resonance venography with Inhance 3D Velocity: diagnostic performance for intracranial venous thrombosis

PURPOSE

The aim of this study was to evaluate the diagnostic performance of Inhance 3D Velocity (I3DV) in intracranial venous thrombosis and investigate the possible impact of venous sinus hypoplasia/aplasia on false thrombosis diagnosis made with I3DV.

METHODS

This study included 540 patients. Contrast-enhanced magnetic resonance venography combined with conventional sequences was considered the gold standard test (GST), while I3DV was considered as diagnostic test. We accessed the diagnostic success of I3DV for intracranial venous thrombosis detection, thrombosed vessel identification, and total/partial thrombus distinction. The possible relationship between false-positive thrombus diagnosed by I3DV and venous sinus hypoplasia or aplasia diagnosed by GST was investigated.

RESULTS

The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of I3DV in the detection of intracranial venous thrombosis were 95.7%, 92.1%, 64.1%, 99.3%, and 92.6%, respectively. A significant association was observed between I3DV and GST in terms of thrombosis detection and total/partial thrombus distinction (p < 0.001). A significant relationship was observed between false-positive thrombosis diagnosis in I3DV and hypoplasia in the left transverse sinus (p < 0.001).

CONCLUSION

Intracranial venous thrombosis may be diagnosed faster and more accurately than traditional phase contrast magnetic resonance angiography in I3DV. This technique can be used in situations where contrast medium application is contraindicated. As in other non-contrast magnetic resonance venography techniques, left transverse sinus hypoplasia can be diagnosed as a thrombosed vessel in I3DV.

Non-contrast-enhanced magnetic resonance angiography of facial arteries for pre-operative evaluation of vascularized submental lymph node flaps

Background

The aim of this study was to compare non-contrast-enhanced 3D phase contrast magnetic resonance angiography (3D PC-MRA) and conventional intravenous administration of contrast media, i.e., contrast-enhanced MRA (CE-MRA), to evaluate the courses of facial arteries for the preparation of vascularized submental lymph node flap (VSLN flap) transfer.

Methods

The head and neck regions of 20 patients with limb lymphedema were imaged using a 3 T MRI scanner. To improve the evaluation of facial artery courses, MRA was fused with anatomical structures generated by high-resolution T1-weighted imaging. The diagnostic and image qualities of facial arteries for VSLN flap planning were independently rated by two radiologists. Interobserver agreement was evaluated using Cohen’s kappa. Differences between 3D PC-MRA and CE-MRA in terms of the diagnostic quality of facial arteries were evaluated using McNemar’s test.

Results

Cohen’s kappa indicated fair to good interobserver agreement for the diagnostic and image qualities of the bilateral facial arteries. No significant difference in terms of the diagnostic quality of the left and right facial arteries between 3D PC-MRA and CE-MRA, respectively, was identified.

Conclusions

Non-contrast 3D PC-MRA is a reliable method for the evaluation of facial artery courses prior to VSLN flap transfer and could serve as an alternative to CE-MRA for patients with renal insufficiency or severe adverse reactions to contrast media.

Simultaneous Visualization of Vessels and Brain Tumor with Contrast-enhanced Three-dimensional Phase-contrast MR Imaging

The sequence for concurrently depicting engulfed vessels and a well-enhanced tumor in once-off scanning has never been reported for preoperative magnetic resonance imaging for brain tumor resection. Multimodal fusion techniques have been recently developed, but the risks of misregistration still remain. Here a case is reported where contrast-enhanced three-dimensional phase contrast sequence concurrently depicted an engulfed vessel and metastatic brain tumor in once-off scanning and related technical aspects are discussed.

Diagnosis of Transverse Sinus Hypoplasia in Magnetic Resonance Venography: New Insights Based on Magnetic Resonance Imaging in Combined Dataset of Venous Outflow Impairment Case-Control Studies: Post Hoc Case-Control Study

In previous studies of transverse sinus (TS) hypoplasia, discrepancies between TS diameter measured by magnetic resonance venography (MRV) and contrast T1-weighted magnetic resonance (contrast T1) were observed. To investigate these discrepancies, and considering that TS hypoplasia is associated with neurological disorders, we performed a post hoc analysis of prospectively collected data from 3 case-control studies on transient global amnesia (TGA), transient monocular blindness (TMB), and panic disorders while retaining the original inclusion and exclusion criteria. Magnetic resonance (MR) imaging of 131 subjects was reviewed to evaluate TS diameter and the location and degree of venous flow stenosis and obstruction.MRV without contrast revealed that TS hypoplasia was observed in 69 subjects, whom we classified into 2 subgroups according to the concordance with contrast T1 observations: concordance indicated anatomically small TS (30 subjects), and discrepancy indicated that the MRV diagnosis is in fact flow-related and that TS is not anatomically small (39 subjects). The latter subgroup was associated with at least 1 site of venous compression/stenosis in the internal jugular vein (IJV) or the left brachiocephalic vein (BCV) (P < 0.001), which was significantly larger in patients than controls. Compensatory dilatation of contralateral TS diameter was only observed with MRV, not with contrast T1 imaging.The clinical implication of these results is that using MRV only, IJV/BCV compression/stenosis may be misdiagnosed as TS hypoplasia. And contralateral TS have no compensatory dilatation in its diameter in contrast T1 imaging, just compensatory increased flow volume.

Non-ECG-gated unenhanced MRA of the carotids: optimization and clinical feasibility

OBJECTIVES

To optimise and assess the clinical feasibility of a carotid non-ECG-gated unenhanced MRA sequence.

METHODS

Sixteen healthy volunteers and 11 patients presenting with internal carotid artery (ICA) disease underwent large field-of-view balanced steady-state free precession (bSSFP) unenhanced MRA at 3T. Sampling schemes acquiring the k-space centre either early (kCE) or late (kCL) in the acquisition window were evaluated. Signal and image quality was scored in comparison to ECG-gated kCE unenhanced MRA and TOF. For patients, computed tomography angiography was used as the reference.

RESULTS

In volunteers, kCE sampling yielded higher image quality than kCL and TOF, with fewer flow artefacts and improved signal homogeneity. kCE unenhanced MRA image quality was higher without ECG-gating. Arterial signal and artery/vein contrast were higher with both bSSFP sampling schemes than with TOF. The kCE sequence allowed correct quantification of ten significant stenoses, and it facilitated the identification of an infrapetrous dysplasia, which was outside of the TOF imaging coverage.

CONCLUSIONS

Non-ECG-gated bSSFP carotid imaging offers high-quality images and is a promising sequence for carotid disease diagnosis in a short acquisition time with high spatial resolution and a large field of view.

KEY POINTS

• Non-ECG-gated unenhanced bSSFP MRA offers high-quality imaging of the carotid arteries. • Sequences using early acquisition of the k-space centre achieve higher image quality. • Non-ECG-gated unenhanced bSSFP MRA allows quantification of significant carotid stenosis. • Short MR acquisition times and ungated sequences are helpful in clinical practice. • High 3D spatial resolution and a large field of view improve diagnostic performance.