ABSTRACT
BACKGROUND AND PURPOSE: Long acquisition times limit the feasibility of established non-contrast-enhanced MRA (non-CE-MRA) techniques. The purpose of this study was to evaluate a highly accelerated flow-independent sequence (Relaxation-Enhanced Angiography without Contrast and Triggering [REACT]) for imaging of the extracranial arteries in acute ischemic stroke (AIS). MATERIALS AND METHODS: Compressed SENSE (CS) accelerated (factor 7) 3D isotropic REACT (fixed scan time: 01:22 min, reconstructed voxel size 0.625 × 0.625 × 0.75 mm3) and CE-MRA (CS factor 6, scan time: 1:08 min, reconstructed voxel size 0.5 mm3) were acquired in 76 AIS patients (69.4 ± 14.3 years, 33 females) at 3 Tesla. Two radiologists assessed scans for the presence of internal carotid artery (ICA) stenosis and stated their diagnostic confidence using a 5-point scale (5 = excellent). Vessel quality of cervical arteries as well as the impact of artifacts and image noise were scored on 5-point scales (5 = excellent/none). Apparent signal- and contrast-to-noise ratios (aSNR/aCNR) were measured for the common carotid artery (CCA) and ICA (C1-segment). RESULTS: REACT provided a sensitivity of 88.5% and specificity of 100% for clinically relevant (≥50%) ICA stenosis with substantial concordance to CE-MRA regarding stenosis grading (Cohen's kappa 0.778) and similar diagnostic confidence (REACT: mean 4.5 ± 0.4 vs. CE-MRA: 4.5 ± 0.6; P = 0.674). Presence of artifacts (3.6 ± 0.5 vs. 3.5 ± 0.7; P = 0.985) and vessel quality (all segments: 3.6 ± 0.7 vs. 3.8 ± 0.7; P = 0.004) were comparable between both techniques with REACT showing higher scores at the CCA (4.3 ± 0.6 vs. 3.8 ± 0.9; P < 0.001) and CE-MRA at V2- (3.3 ± 0.5 vs. 3.9 ± 0.8; P < 0.001) and V3-segments (3.3 ± 0.5 vs. 4.0 ± 0.8; P < 0.001). For all vessels, REACT showed a lower impact of image noise (3.8 ± 0.6 vs. 3.6 ± 0.7; P = 0.024) while yielding higher aSNR (52.5 ± 15.1 vs. 37.9 ± 12.5; P < 0.001) and aCNR (49.4 ± 15.0 vs. 34.7 ± 12.3; P < 0.001) for all vessels combined. CONCLUSIONS: In patients with acute ischemic stroke, highly accelerated REACT provides an accurate detection of ICA stenosis with vessel quality and scan time comparable to CE-MRA.
Subject(s)
Ischemic Stroke , Magnetic Resonance Angiography , Humans , Female , Male , Magnetic Resonance Angiography/methods , Aged , Ischemic Stroke/diagnostic imaging , Middle Aged , Neck/diagnostic imaging , Neck/blood supply , Contrast Media , Aged, 80 and over , Signal-To-Noise Ratio , Image Processing, Computer-Assisted/methods , Artifacts , Imaging, Three-Dimensional/methods , Reproducibility of Results , Image Enhancement/methods , Image Interpretation, Computer-Assisted/methodsABSTRACT
Pathological fractures of long tubular bones are stabilized with conventional implants. Essentially, plates and intramedullary nails are used for stabilization and are two different techniques, which compete with each other with respect to the surgical treatment. A large number of such means of osteosynthesis are commercially available but are primarily focused on acute fractures in otherwise biologically healthy bones. The pathological fracture or the treatment of impending pathological fractures due to metastatic osteolysis differs from the treatment of healthy bones in some fundamental aspects. The characteristics of pathological fractures make the development of new technologies that meet the specific needs of both the patient and the surgeon desirable. A new approach in treatment is stabilization of internal long bone fractures by the use of a cylindrical balloon implant, which is introduced into the bone via a small proximal or distal hole and then filled and expanded to a much larger diameter with a liquid monomer. The curing process is initiated with the application of blue light forming a rigid implant by polymerization (IlluminOss™). Many of the well-known disadvantages of conventional implants can be eliminated with this technology. Specifically, with respect to the irregular shape of the natural medullary canal it is possible to completely fill the medullary canal of the tubular bone. The filling of the canal provides torsional stability without the use of interlocking screws. Similarly, the use of the balloon technique enables minimally invasive surgery and furthermore permits the additive use of conventional metallic plates whenever necessary. The new balloon techniques show high primary stability in the treatment of pathological shaft fractures. In particular cases, the addition of a supplemental plate osteosynthesis is recommended.