Bilateral contrast-enhanced MR angiography of the hand: diagnostic image quality of accelerated MRI using echo sharing with interleaved stochastic trajectories (TWIST)

Preoperative MRI Evaluation of Hand Vessels in Children With Congenital Syndactyly Malformation by a Contrast-Enhanced Three-Dimensional Water-Selective Cartilage Scan

BACKGROUND

It is crucial to preoperatively assess the arteries of the hands in congenital syndactyly malformation (CSM) patients because this information can affect the therapeutic outcome and prognosis.

OBJECTIVE

To investigate the value of a contrast-enhanced three-dimensional water-selective cartilage scan for the preoperative evaluation of CSM in children.

MATERIALS AND METHODS

Contrast-enhanced three-dimensional water-selective cartilage scan 3.0 T magnetic resonance imaging (MRI) performed in 16 clinically diagnosed CSM patients with 17 affected hands. The arteries of the hands were displayed with a focus on the bifurcation position of the common palmar digital arteries (CPDAs) and the maturity of the proper palmar digital arteries (PPDAs). The MRI results were interpreted by consensus between two experienced pediatric radiologists with 10 years of MRI experience each. The MRI findings were compared with the operation results.

RESULTS

Of 51 CPDAs in the 17 affected hands, MRI showed that 30 had an abnormal bifurcation position and 20 had a normal position, and of the 102 PPDAs, 14 were shown to have an abnormal maturity and 85 a normal state, which were confirmed by surgery. The accuracy, sensitivity and specificity for determining the bifurcation position of the CPDAs based on MR maximum intensity projection reconstructed images were 98.04% (50/51), 96.77% (30/31) and 100% (20/20), respectively. The maturity of the PPDAs was judged by MR maximum intensity projection reconstructed images with an accuracy, sensitivity and specificity of 97.06% (99/102), 82.35% (14/17) and 100% (85/85), respectively.

CONCLUSION

Contrast-enhanced three-dimensional water-selective cartilage scan has excellent performance in displaying the bifurcation position of the CPDAs and the maturity of the PPDAs and is of high value for the preoperative evaluation of CSM in children.

Feasibility of Noninvasive Diagnosis of Spinal Vascular Diseases Using Time-Resolved Angiography With Stochastic Trajectories

Background and Purpose: To determine the feasibility of time-resolved angiography with stochastic trajectories (TWIST) in the diagnosis of spinal dural arteriovenous fistula (SDAVF) and perimedullary arteriovenous fistula (PAVF).

Methods: A total of 11 negative patients with TWIST examination were retrospective analyzed and then 18 patients with suspected spinal vascular diseases underwent TWIST. For negative patients, Adamkiewicz artery (AKA), great anterior radiculomedullary vein (GARV) and anterior spinal artery (ASA) were retrospective analyzed. In patients, the results of TWIST were compared with those of DSA.

Results: The displaying rates of the ASA, AKA and GARV in 11 negative patients were 100, 90.9, and 90.9%, respectively. The AKA and GARV were separated on TWIST. Of 18 patients, 11 and three were diagnosed with SDAVF and PAVF, respectively. The spinal cord vascular malformation diagnosed on TWIST was consistent with DSA with an excellent intermodality agreement (Kappa = 0.92, p < 0.001). The feeding artery and side of all 11 SDAVF patients were displayed on TWIST and the results were consistent with DSA. For PAVF patients, the feeding artery in two patients and the sides as displayed on TWIST were consistent with DSA.

Conclusions: TWIST enables the differentiation of the spinal artery and vein and the differential diagnosis of SDAVF and PAVF.

3D MRI of the Hand and Wrist: Technical Considerations and Clinical Applications

In the last few years, major developments have been observed in the field of magnetic resonance imaging (MRI). Advances in both scanner hardware and software technologies have witnessed great leaps, enhancing the diagnostic quality and, therefore, the value of MRI. In musculoskeletal radiology, three-dimensional (3D) MRI has become an integral component of the diagnostic pathway at our institutions. This technique is particularly relevant in patients with hand and wrist symptoms, due to the intricate nature of the anatomical structures and the wide range of differential diagnoses for most presentations. We review the benefits of 3D MRI of the hand and wrist, commonly used pulse sequences, clinical applications, limitations, and future directions. We offer guidance for enhancing the image quality and tips for image interpretation of 3D MRI of the hand and wrist.

Noncontrast Magnetic Resonance Angiography in the Era of Nephrogenic Systemic Fibrosis and Gadolinium Deposition

ABSTRACT

Gadolinium-based contrast agents for clinical magnetic resonance imaging are overall safe. However, the discovery of nephrogenic systemic fibrosis in patients with severe renal impairment and gadolinium deposition in patients receiving contrast have generated developments in contrast-free imaging of the vasculature, that is, noncontrast magnetic resonance angiography. This article presents an update on noncontrast magnetic resonance angiography techniques, with comparison to other imaging alternatives. Potential benefits and challenges to implementation, and evidence to date for various clinical applications are discussed.

Techniques for Imaging Vascular Supply of Peripheral Nerves

Few studies have been developed to map the vascular structures feeding peripheral nerves, with the majority using cadaveric models and inadequate sample sizes. Preliminary evidence, while limited, indicates that the mapping of these vessels may allow or preclude certain procedures in nerve reconstruction due to the location of essential arterial inflow to the vasa nervorum. This review evaluates the evidence regarding historical, current, and emerging techniques for visualizing these vascular structures in vivo and considers their potential application in peripheral nerve vasculature.

MR Imaging of the Mesenteric Vasculature

MR angiography is a flexible imaging technique enabling morphologic assessment of mesenteric arterial and venous vasculature. Conventional gadolinium-based contrast media and ferumoxytol are used as contrast agents. Ferumoxytol, an intravenous iron replacement therapy approved by the US Food and Drug Administration for iron deficiency anemia, is an effective and well tolerated blood pool contrast agent. The addition of 4D flow MR imaging enables a functional assessment of the arterial and venous vasculature; when coupled with a meal challenge, the severity of mesenteric arterial stenosis is well appreciated. Noncontrast MR angiographic techniques are useful for evaluating suspected mesenteric ischemia.

Evaluation of image quality of pituitary dynamic contrast-enhanced MRI using time-resolved angiography with interleaved stochastic trajectories (TWIST) and iterative reconstruction TWIST (IT-TWIST)

BACKGROUND

Time-resolved angiography with interleaved stochastic trajectories (TWIST) is a keyhole imaging with frequent sampling of central k-space data and view-sharing for the peripheral k-space of dynamic phases. IT-TWIST is a technique to reconstruct images with a smaller temporal footprint using the same raw data obtained with TWIST by iterative reconstruction.

PURPOSE

To compare image quality between TWIST and IT-TWIST in 3D pituitary DCE-MRI.

STUDY TYPE

Retrospective observation study.

POPULATION

Fifty-one patients (23 men, 28 women) who underwent 3D pituitary DCE-MRI using TWIST between July 2016 and April 2017.

FIELD STRENGTH/SEQUENCE

3T/TWIST and IT-TWIST.

ASSESSMENT

Visual evaluation was conducted for image quality of delineation of the pituitary stalk and posterior lobe during the early arterial phase, cerebral white matter near the sella turcica, and the mass lesion. Bolus sharpness of the pituitary stalk, posterior lobe, and bilateral cavernous sinus was evaluated on the enhancement slope map calculated from TWIST and IT-TWIST. Temporal stability of intensity of the nonenhanced area was evaluated on temporal standard deviation (SD) maps calculated from TWIST and IT-TWIST.

STATISTICAL TESTS

Paired t-test or Wilcoxon rank-sum test was used to test the differences between TWIST and IT-TWIST in both visual evaluation and region of interest evaluation.

RESULTS

Scores of visual evaluations for IT-TWIST were significantly better than those for TWIST (P < 0.001) in all items. Enhancement slope for IT-TWIST was significantly higher than that for TWIST in posterior lobe, and right and left cavernous sinus (P < 0.001). Temporal SD for IT-TWIST was significantly lower than that for TWIST in all items, with statistical significance (P < 0.001).

DATA CONCLUSION

IT-TWIST yielded better visualization, and better enhancement slope, and less temporal SD compared with TWIST in 3D pituitary DCE-MRI. Evidence Level: 4 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:1497-1506.

Recent advances in 3D time-resolved contrast-enhanced MR angiography

Contrast-enhanced magnetic resonance angiography (CE-MRA) was first introduced for clinical studies approximately 20 years ago. Early work provided 3-4 mm spatial resolution with acquisition times in the 30-second range. Since that time there has been continuing effort to provide improved spatial resolution with reduced acquisition time, allowing high resolution 3D time-resolved studies. The purpose of this work is to describe how this has been accomplished. Specific technical enablers have been: improved gradients allowing reduced repetition times, improved k-space sampling and reconstruction methods, parallel acquisition, particularly in two directions, and improved and higher count receiver coil arrays. These have collectively made high-resolution time-resolved studies readily available for many anatomic regions. Depending on the application, ∼1 mm isotropic resolution is now possible with frame times of several seconds. Clinical applications of time-resolved CE-MRA are briefly reviewed.

Dynamic MR angiography in acute aortic dissection

BACKGROUND

To evaluate the benefit (additional flow information), image quality, and diagnostic accuracy of a dynamic magnetic resonance angiography (MRA) combining high spatial and temporal resolution for the preinterventional assessment of acute aortic dissection.

METHODS

Nineteen patients (12 men, 7 women; aged 32-78 years) with acute aortic dissection underwent contrast-enhanced four-dimensional (4D) MRA and 3D conventional high-resolution MRA (3D MRA) within one examination on a 1.5 Tesla MR system. Both MRA datasets for each patient were evaluated and compared for image quality and visualization of vascular details on a 5-point scale (5 = excellent image quality, 1 = nondiagnostic image quality). In addition, presence and relevance of additional hemodynamic information (flow direction and organ perfusion delay) gained by dynamic MRA were assessed.

RESULTS

Conventional 3D MRA provided significantly higher values for image quality of the aorta and aortic side branches compared with dynamic MRA (aorta: 4.3 versus 3.3; P = 0.006 side branches: 4.2 versus 3.3; P = 0.02). However, in 10 of the 19 patients (53%) the additionally available information on flow dynamics due to dynamic MRA (e.g., delayed perfusion of parenchymal organs) led to a change in therapy planning and realization.

CONCLUSION

Dynamic MRA is a technique that combines functional flow and morphological information. Thus, the combination of 3D and dynamic MRA provides all requested information for treatment planning in patients suffering from acute aortic dissection.