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Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

ABSTRACT: To identify and reduce image artifacts in non-contrast-enhanced velocity-selective (VS) magnetization-prepared peripheral MR angiography (MRA) at 3T.To avoid signal loss in the arteries, double and quadruple refocused VS excitation pulse sequences were designed that were robust to a wide range of B0 and B1 offset. To suppress stripe artifact and background signal variation, we successively applied two VS preparations with excitation profiles shifted by half the period of the stripes. VS-MRA using single, double, and quadruple refocused VS preparations was tested in healthy subjects and a patient.In the regions of large B0 and B1 offsets, arterial signal loss was yielded by single refocused VS preparation, but was avoided with double or quadruple refocused preparations. Compared with single VS preparation, the two consecutive preparations with shifted excitation profiles substantially reduced the stripe artifact and background signal variation, as demonstrated by increased mean and decreased standard deviation of relative contrast-to-noise ratio. The proposed VS-MRA identified multilevel disease in the femoral arteries of the patient, as validated by digital subtraction angiography.Two multiple refocused VS magnetization preparations with shifted excitation profiles yield artifact-free peripheral angiograms at 3T. Magn Reson Med 76:466-477, 2016. © 2015 Wiley Periodicals, Inc.

SUBMITTER: Shin T

PROVIDER: S-EPMC4769124 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

Shin Taehoon T Qin Qin Q Park Jang-Yeon JY Crawford Robert S RS Rajagopalan Sanjay S

Magnetic resonance in medicine 20150826 2

<h4>Purpose</h4>To identify and reduce image artifacts in non-contrast-enhanced velocity-selective (VS) magnetization-prepared peripheral MR angiography (MRA) at 3T.<h4>Methods</h4>To avoid signal loss in the arteries, double and quadruple refocused VS excitation pulse sequences were designed that were robust to a wide range of B0 and B1 offset. To suppress stripe artifact and background signal variation, we successively applied two VS preparations with excitation profiles shifted by half the pe ...[more]

PMID: 26308243

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Project description:The high incidence of renal insufficiency in patients with Peripheral Arterial Disease raises the concern for nephrogenic systemic fibrosis (NSF) with respect to contrast enhanced MRA. The risk of NSF is eliminated with non-contrast enhanced magnetic resonance angiography. The purpose of the current study is to compare image quality and diagnostic performance of non-contrast enhanced Quiescent Interval Single Shot (QISS) magnetic resonance angiography at 3 T versus CT angiography for evaluation of lower extremity Peripheral Arterial Disease (PAD).32 consecutive patients (23 male, 9 female, age range 40-81 years, average age 61.97 years) with clinically suspected lower extremity PAD underwent QISS MRA and CTA. 19 of 32 patients underwent Digital Subtraction Angiography (DSA). Image quality of MRA was compared with CTA by two radiologists with 10 and 8 years' experience according to a 4-point scale. The Kappa test was used to determine the intermodality agreement between MRA and CTA in stenosis assessment, and interobserver agreement with each method. Sensitivity and specificity of CTA and MRA in detecting hemodynamically significant stenosis (≥50 %) were compared, with DSA serving as reference standard when available.Image quality of QISS MRA was rated 3.70 ± 0.49 by reader 1, and 3.72 ± 0.47 by reader 2, significantly lower than that of CTA (3.80 ± 0.44 and 3.82 ± 0.42, P < 0.001 for both readers). Intermodality agreement between MRA and CTA was excellent for assessment of stenosis (Kappa = 0.923 ± 0.013 for reader 1, 0.930 ± 0.012 for reader 2). Interobserver agreement was 0.936 ± 0.012 for CTA and 0.935 ± 0.011 for MRA. For readers 1 and 2 respectively, the sensitivity of QISS was 94.25 and 93.26 % (versus 90.11 and 89.13 % for CTA, P > 0.05), and specificity of QISS was 96.70 and 97.75 % (versus 96.55 and 96.51 % for CTA, P > 0.05). For heavily calcified segments, sensitivity of QISS (95.83 and 95.83 %) was significantly higher than that of CTA (74.19 and 76.67 %, P < 0.05).QISS is a reliable alternative to CTA for evaluation of lower extremity PAD, and may be suitable as a first-line screening examination in patients with contraindications to intravenous contrast administration.

Project description:OBJECTIVE:To analyze quality and frequency of OCTA artifacts and to evaluate their impact on the interpretability of OCTA images. DESIGN:75 patients with diabetic retinopathy (DR), retinal artery occlusion (RAO), retinal vein occlusion (RVO), or neovascular age-related macular degeneration (nAMD) and healthy controls were enrolled in this cross-sectional study in the outpatient department of a tertiary eye care center. METHODS:All participants underwent an OCTA examination (spectral domain OCT Cirrus 5000 equipped with the AngioPlex module). OCTA scans were analyzed independently by two experienced ophthalmologists. Frequency of various artifacts for the entire OCTA scan and for different segmentation layers and the grading of OCTA interpretability were investigated. RESULTS:The analysis of 75 eyes of 38 women and 37 men between 24 and 94 years were included. Six eyes had no retinal disease, 19 eyes had nAMD, 16 had DR, 19 eyes had RVO, and 15 eyes showed RAO. A macular edema (ME) was present in 40 of the diseased eyes. Projection artifacts occurred in all eyes in any structure below the superficial retinal vessel layer, segmentation and motion artifacts were found in 55% (41/75) and 49% (37/75) of eyes, respectively. Other artifacts occurred less frequently. Segmentation artifacts were significantly more frequent in diseased than in healthy eyes (p<0.01). Qualitative assessment of OCTA images was graded as excellent in 65% and sufficient in 25% of cases, adding up to 91% images deemed acceptable for examination. Presence of ME was associated with a significantly poorer interpretability (p<0.01). CONCLUSION AND RELEVANCE:Various artifacts appear at different frequencies in OCTA images. Nevertheless, a qualitative assessment of the OCTA images is almost always possible. Good knowledge of possible artifacts and critical analysis of the complete OCTA dataset are essential for correct clinical interpretation and determining a precise clinical diagnosis.

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Project description:BackgroundContrast-associated acute kidney injury (CA-AKI) is an important adverse effect associated with injecting iodinated intra-arterial contrast media (CM) during coronary angiography. The DyeVert™ Contrast Reduction System is a medical device intended to reduce the intra-arterial CM volume (CMV) administered. The aim of this study was to assess DyeVert System clinical effectiveness and safety by implementing a systematic review and meta-analysis of existing evidence.MethodsSystematic electronic literature searches were conducted in MEDLINE, Embase, the Cochrane Database of Systematic Reviews, ClinicalTrials.gov, and the International Clinical Trials Registry Platform database. Relevant data were extracted from included studies and meta-analyses were performed to synthesize evidence across studies.ResultsThe review included 17 eligible studies involving 1,731 DyeVert System cases and 1,387 control cases (without the use of DyeVert). Meta-analyses demonstrated use of the DyeVert System reduced CMV delivered to the patient by 39.27% (95% CI, 36.10-42.48%, P < 0.001), reduced CMV/baseline renal function ratios (Hedges's g, -0.56; 95% CI, -0.70 to -0.42, P < 0.001) and percentage of cases exceeding the maximum CMV threshold (risk difference -0.31, 95% CI, -0.48 to -0.13, P < 0.001) while maintaining adequate image quality in 98% of cases. DyeVert System cases demonstrated lower CA-AKI incidence vs. controls (absolute risk reduction 5.00% (95% CI, 0.40-9.80%; P = 0.03), relative risk 0.60 (95% CI, 0.40-0.90; P = 0.01) with a pooled estimate of the number needed to treat with the DyeVert System to avoid 1 CA-AKI event of 20.ConclusionDyeVert System use significantly reduces CMV delivered to the patient, CMV/baseline renal function ratios, and CA-AKI incidence while maintaining image quality. Accordingly, the device may serve as an adjunctive, procedure-based strategy to prevent CA-AKI. Future multi-center studies are needed to further assess effects of minimizing CMV on endpoints such as CA-AKI prevention, incidence of adverse cardiac and renal events, and health care costs.

Project description:Background and purposeThe diagnosis of spinal vascular malformations may be challenging on conventional MR imaging because neither the location of the signal abnormality in the spinal cord nor the level of the abnormal flow voids correlates with the level of the fistula. We conducted a retrospective evaluation of the utility of using a time-resolved imaging of contrast kinetics sequence in the diagnosis, characterization, and localization of spinal vascular malformations, comparing it with the criterion standard of spinal DSA.Materials and methodsFifty-five consecutive patients with a suspected diagnosis of spinal vascular malformation underwent time-resolved imaging of contrast kinetics followed by spinal DSA. All scans were performed on a 1.5T scanner by using a standard 8-channel spine coil and were reported by a neuroradiologist before the DSA was performed.ResultsForty-seven lesions were confirmed on time-resolved imaging of contrast kinetics and classified as spinal dural arteriovenous fistulas (n = 33, with 1 patient having a type Ib fistula), perimedullary spinal cord arteriovenous fistulas (n = 10), and intramedullary arteriovenous malformations (n = 3). One patient had an extradural spinal vascular malformation. Time-resolved imaging of contrast kinetics identified the location of the arterial feeder to within 1 vertebral level in 27/33 patients (81.8%) with spinal dural arteriovenous fistulas and correctly predicted the side in 22/33 (66.6%) patients. Perimedullary spinal cord arteriovenous fistulas were erroneously considered to represent spinal dural arteriovenous fistulas before spinal DSA. The anatomy of the arterial supply to intramedullary arteriovenous malformations was also poorly characterized on time-resolved contrast-enhanced MR angiography.ConclusionsIt has been our experience that time-resolved imaging of contrast kinetics is a useful confirmatory tool when a spinal vascular malformation is suspected on the basis of clinical and conventional MR imaging findings. As experience with the technique grows and sequences are refined, it may be possible to rely on time-resolved imaging of contrast kinetics as a screening tool for the diagnosis of spinal vascular malformations.

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Dataset Information

Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

Publications

Identification and reduction of image artifacts in non-contrast-enhanced velocity-selective peripheral angiography at 3T.

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