Non-contrast magnetic resonance angiography for systemic artery evaluation in Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is a systemic vasculitis; systemic arteries other than the coronary arteries should therefore also be evaluated. This study investigated the feasibility of evaluating coronary aneurysms, systemic artery aneurysms (SAAs), and cerebrovascular diseases in patients with KD using non-contrast magnetic resonance angiography (NC-MRA). METHODS: Coronary artery protocols, including coronary magnetic resonance angiography (MRA) and vessel wall imaging, were performed in 57 examinations of 28 patients. Systemic artery protocol, including SAA scans and head MRA, along with coronary artery protocol, were performed in 42 examinations of 42 patients. The image quality of the SAAs was evaluated on a 4-point scale. Examination time and sedation dosage were compared between the protocols. The presence of SAAs and cerebrovascular disease was also evaluated. RESULTS: The image quality score of SAAs was 4 (interquartile range [IQR]: 4-4) for the aorta, 4 (IQR: 3-4) for the subclavian artery, 4 (IQR: 3-4) for the renal artery, and 3 (IQR: 3-4) for the iliac artery. No differences were found between examination time (47.0 [IQR: 43.0-61.0] min vs. 51.0 [IQR: 45.0-60.0] min, p = 0.48) and sedative dose (4.63 [IQR: 3.93-5.79] mg/kg vs. 4.21 [IQR: 3.56-5.71] mg/kg, p = 0.37) between the protocols. Systemic artery protocol detected SAAs in three patients (7.1%), and cerebrovascular disease was not detected. CONCLUSIONS: Evaluating the coronary and systemic arteries in patients with KD using NC-MRA on a single examination was possible without compromising examination time or sedation dose. The systemic artery protocol was useful in finding SAAs.

Thoracic aorta diameters in Marfan patients: Intraindividual comparison of 3D modified relaxation-enhanced angiography without contrast and triggering (REACT) with transthoracic echocardiography.

OBJECTIVE: To compare the measurement of aortic diameters using a novel flow-independent MR-Angiography (3D modified Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT)) and transthoracic echocardiography (TTE) in Marfan syndrome (MFS) patients. MATERIAL AND METHODS: This retrospective, single-center analysis included 46 examinations of 32 MFS patients (mean age 37.5 ± 11.3 years, 17 women, no prior aortic surgery) who received TTE and 3D modified REACT (ECG- and respiratory-triggering, Compressed SENSE factor 9 for acceleration of image acquisition) of the thoracic aorta. Aortic diameters (sinus of Valsalva (SV), sinotubular junction (STJ), and ascending aorta (AoA)) were independently measured by two cardiologists in TTE (leading-edge) and two radiologists in modified REACT (inner-edge, using multiplanar reconstruction). Intraclass correlation coefficient, Bland-Altman analyses, and Pearson's correlation (r) were used to assess agreement between observers and methods. RESULTS: Interobserver correlation at the SV, STJ, and AoA were excellent for both, TTE (ICC = 0.95-0.98) and modified REACT (ICC = 0.99-1.00). There was no significant difference between TTE and modified REACT for diameters measured at the SV (39.24 ± 3.24 mm vs. 39.63 ± 3.76 mm; p = 0.26; r = 0.78) and the STJ (35.16 ± 4.47 mm vs. 35.37 ± 4.74 mm; p = 0.552; r = 0.87). AoA diameters determined by TTE were larger than in modified REACT (34.29 ± 5.31 mm vs. 30.65 ± 5.64 mm; p < 0.01; r = 0.74). The mean scan time of modified REACT was 05:06 min ± 02:47 min, depending on the patient's breathing frequency and heart rate. CONCLUSIONS: Both TTE and modified REACT showed a strong correlation for all aortic levels; however, at the AoA, diameters were larger using TTE, mostly due to the limited field of view of the latter with measurements being closer to the aortic valve. Given the excellent interobserver correlation and the strong agreement with TTE, modified REACT represents an attractive method to depict the thoracic aorta in MFS patients.

External iliac artery Endofibrosis in a professional cyclist.

We present a case of a 30-year-old female professional cyclist who presented with right thigh claudication while performing high-intensity efforts. Based on the typical clinical history and the presence of a smooth long segment diffuse narrowing in the right external iliac artery on non-contrast magnetic resonance angiography, a diagnosis of external iliac artery endofibrosis or "cyclist's iliac syndrome" was made. Supplementary Information: The online version contains supplementary material available at 10.1007/s12055-022-01349-8.

Accuracy of Inflow Inversion Recovery (IFIR) for Upper Abdominal Arteries Evaluation: Comparison with Contrast-Enhanced MR and CTA.

Background: Inflow-sensitive inversion recovery (IFIR) is a recently introduced technique to perform unenhanced magnetic resonance angiography (MRA). The purpose of our study is to determine the accuracy of IFIR-MRA in the evaluation of upper abdominal arteries, compared to standard MRA and computed tomography angiography (CTA). Materials and Methods: Seventy patients undergoing upper abdomen Magnetic Resonance Imaging (MRI) in different clinical settings were enrolled. The MRI protocol included an IFIR-MRA sequence that was intra-individually compared by using a qualitative 4-point scale in the same patients who underwent concomitant or close MRA (n = 65) and/or CTA (n = 44). Celiac trunk (CA), common-proper-left-right hepatic artery (C-P-L-R-HA), left gastric artery (LGA), gastroduodenal artery (GDA), splenic artery (SA), renal arteries (RA) and superior mesenteric artery (SMA) were assessed. Results: IFIR-MRA images were better rated in comparison with MRA. Particularly, all arteries obtained a statistically significant higher qualitative rating value (all p < 0.05). IFIR-MRA and MRA exhibited acceptable intraclass correlation coefficients (ICC) values for CA, C-L-R-HA, and SMA (ICC 0.507, 0.591, 0.615, 0.570, 0.525). IFIR-MRA and CTA showed significant correlations in C-P-L-R-HA (τ = 0.362, 0.261, 0.308, 0.307, respectively; p < 0.05), and in RA (τ = 0.279, p < 0.05). Conclusions: Compared to MRA, IFIR-MRA demonstrated a higher image quality in the majority of upper abdomen arterial vessels assessment. LHA and RHA branches could be better visualized with IFIR sequences, when visualizable. Based on these findings, we suggest to routinely integrate IFIR sequences in upper abdomen MRI studies.

Pitfall for systemic artery aneurysms evaluation using electrocardiogram-gated subtracted three-dimensional fast spin echo sequence of magnetic resonance imaging in patients with Kawasaki disease.

Kawasaki disease (KD) is described as a syndrome that causes both coronary and systemic artery aneurysms (SAAs). This report describes the pitfall for SAAs' evaluation when using electrocardiogram (ECG)-gated subtracted three-dimensional fast spin echo (3D FSE) sequence of magnetic resonance imaging in KD patients. A 12-year-old male was diagnosed with KD at 3 months of age. We acquired ECG-gated 3D FSE images in the diastole and systole phases with coronal sections. Subtraction was then performed from diastolic phase imaging to systolic phase imaging. A 15.5 mm right axillary artery aneurysm and an 8.0 mm left axillary artery aneurysm were identified with ECG-gated 3D FSE in the diastolic phase. However, we observed signal loss in the right axillary artery aneurysm when subtraction was performed to selectively detect arteries; further, the brachial artery was poorly detected. ECG-gated subtracted 3D FSE sequence of magnetic resonance imaging can compromise the image quality of both aneurysm and peripheral artery images when detecting SAAs.

The diagnostic value of non-contrast magnetic resonance coronary angiography in the assessment of coronary artery disease: A systematic review and meta-analysis.

PURPOSE: The current literature reports a wide range of diagnostic accuracy of non-contrast magnetic resonance coronary angiography (NC-MRCA) for the assessment of coronary artery disease (CAD). We aimed to compare the clinical effectiveness of NC-MRCA with that of invasive coronary angiography (ICA) in patients with suspected CAD using a systematic review and meta-analysis. METHODS: Two investigators independently extracted 36 published manuscripts between 2010 and 2019. Databases including Medline, Web of Knowledge, Google Scholar, Scopus, and Cochrane were searched using pre-established keywords. Analysis of the data followed the PRISMA statement for reporting systematic reviews and meta-analyses and primary analysis followed the Mantel-Hansel methodology. Correctness of classification for detecting coronary artery stenosis ≥50% (CAS) was measured using ICA as the gold standard. RESULTS: A total of five studies met inclusion criteria, with a total of 417 patients and 2883 coronary segments. The pooled per patient sensitivity and specificity of NC-MRCA for CAS in suspected patients was 90.3% (95% CI 85.6-95.1%) and 77.9% (95% CI 69.5-86.3%). Pooled per vessel assessment of NC- MRCA revealed a sensitivity of 83.7% (95%CI 79.7-87.8%) and specificity of 90.0% (95%CI 86.7-93.4%). Per-segment assessment of NC-MRCA showed a pooled sensitivity of 81.6% (95% CI 76.8-86.4) and specificity of 97.0% (95% CI 95.5-98.5). Mild to moderate heterogeneity was noted in most diagnostic parameters with larger heterogeneity noted in the per-segment analyses. There was less heterogeneity in sensitivity and NPV than specificity and PPV. CONCLUSION: According to this meta-analysis, non-contrast coronary MRA resulted in adequate screening in patients with suspected CAD with high sensitivity and specificity. This result was true for per-patient, per-vessel, and per-segment assessment.

Self-navigated 3D whole-heart MRA for non-enhanced surveillance of thoracic aortic dilation: A comparison to CTA.

PURPOSE: To prospectively compare image quality and reliability of a non-contrast, self-navigated 3D whole-heart magnetic resonance angiography (MRA) sequence with contrast-enhanced computed tomography angiography (CTA) for sizing of thoracic aortic aneurysm (TAA). METHODS: Self-navigated 3D whole-heart 1.5 T MRA was performed in 20 patients (aged 67 ± 9 years, 75% male) for sizing of TAA; a subgroup of 18 (90%) patients underwent additional contrast-enhanced CTA on the same day. Subjective image quality was scored according to a 4-point Likert scale and ratings between observers were compared by Cohen's Kappa statistics. For MRA, subjective motion blurring and signal inhomogeneity was rated according to a 3-point scale, respectively. Objective signal inhomogeneity of MRA was quantified as standard deviation of the voxel intensities in a circular region of interest (ROI) placed in the ascending aorta divided by their mean value. Continuous MRA and CTA measurements were analyzed with regression and Bland-Altman analysis. RESULTS: Overall subjective image quality as rated by two observers was 1 [interquartile range (IQR) 1-2] for self-navigated MRA and 1.5 [IQR 1-2] for CTA (p = 0.717). For MRA, perfect inter-observer agreement was found regarding presence of artefacts and subjective image sharpness (κ = 1). Subjective signal inhomogeneity agreed moderately between the observers (κ = 0.58, p = 0.007), however, it correlated strongly with objectively quantified inhomogeneity of the blood pool signal (r = 0.78, p < 0.0001). Maximum diameters of TAA as measured by self-navigated MRA and CTA showed very strong correlation (r = 0.99, p < 0.0001) without significant inter-method bias (bias -0.03 mm, lower and upper limit of agreement -0.74 and 0.68 mm, p = 0.749). Inter-observer correlation of aortic aneurysm as measured by MRA was very strong (r = 0.96) without significant bias (p = 0.695). CONCLUSION: Self-navigated 3D whole-heart MRA enables reliable contrast- and radiation free aortic dilation surveillance without significant difference to standardized CTA while providing predictable acquisition time and offering excellent image quality.

Diagnostic accuracy of non-contrast quiescent-interval slice-selective (QISS) MRA combined with MRI-based vascular calcification visualization for the assessment of arterial stenosis in patients with lower extremity peripheral artery disease.

OBJECTIVES: The proton density-weighted, in-phase stack-of-stars (PDIP-SOS) MRI technique provides calcification visualization in peripheral artery disease (PAD). This study sought to investigate the diagnostic accuracy of a combined non-contrast quiescent-interval slice-selective (QISS) MRA and PDIP-SOS MRI protocol for the detection of PAD, in comparison with CTA and digital subtraction angiography (DSA). METHODS: Twenty-six prospectively enrolled PAD patients (70 ± 8 years) underwent lower extremity CTA and 1.5-T or 3-T PDIP-SOS/QISS MRI prior to DSA. Two readers rated image quality and graded stenosis (≥ 50%) on QISS MRA without/with calcification visualization. Sensitivity, specificity, and area under the curve (AUC) were calculated against DSA. Calcification was quantified and compared between MRI and non-contrast CT (NCCT) using paired t test, Pearson's correlation, and Bland-Altman analysis. RESULTS: Image quality ratings were significantly higher for CTA compared to those for MRA (4.0 [3.0-4.0] and 3.0 [3.0-4.0]; p = 0.0369). The sensitivity and specificity of QISS MRA, QISS MRA with PDIP-SOS, and CTA for ≥ 50% stenosis detection were 85.4%, 92.2%, and 90.2%, and 90.3%, 93.2%, and 94.2%, respectively, while AUCs were 0.879, 0.928, and 0.923, respectively. A significant increase in AUC was observed when PDIP-SOS was added to the MRA protocol (p = 0.0266). Quantification of calcification showed significant differences between PDIP-SOS and NCCT (80.6 ± 31.2 mm3 vs. 88.0 ± 29.8 mm3; p = 0.0002) with high correlation (r = 0.77, p < 0.0001) and moderate mean of differences (- 7.4 mm3). CONCLUSION: QISS MRA combined with PDIP-SOS MRI provides improved, CTA equivalent, accuracy for the detection of PAD, although its image quality remains inferior to CTA. KEY POINTS: • Agreement in stenosis detection rate using non-contrast quiescent-interval slice-selective MRA compared to DSA improved when calcification visualization was provided to the readers. • An increase was observed in both sensitivity and specificity for the detection of ≥ 50% stenosis when MRI-based calcification assessment was added to the protocol, resulting in a diagnostic accuracy more comparable to CTA. • Quantification of calcification showed statistical difference between MRI and non-contrast CT; however, a high correlation was observed between the techniques.

Fast acceleration of ASL-based time-resolved magnetic resonance angiography by acquisition of control and labeled images in the same shot (fast ACTRESS): An optimization study.

PURPOSE: To establish an optimized sequence design for fast acceleration of arterial spin labeling (ASL)-based time-resolved magnetic resonance angiography (MRA) by acquisition of control and labeled images in the same shot (fast ACTRESS) and a scan time of <1min, for the evaluation of intracranial vessels. MATERIALS AND METHODS: Ten healthy volunteers with no unilateral symptomatic arterial stenosis, who underwent 3-tesla MRI, were investigated. Imaging parameters for the fast ACTRESS sequence were set with an acquisition time of 45s. During post-processing, the first phase in the multi-phase readout, which was defined as the control image, was subtracted from each of the other phases. Thus, four-dimensional (4D)-MRA images of each phase were obtained. The maximum intensity projection was used for the reconstruction of 4D-MRA images and time-to-signal intensity curves (TIC) obtained for each vessel. The area under the curve (AUC), peak time, and maximum signal intensity were obtained from TIC. The different labeling types were broadly divided into six groups: L1, L2, L3, L4, L5, and L6 according to the actual number of labeling pulse. RESULTS: A total of 5040 regions of interest were evaluated. The peak SI of L3, except for those in the A2 segment of the anterior cerebral artery, was significantly higher than that of L5. However, there were no significant differences between L4 and L5. Although the AUCs of L3 and L4 for anterior circulation were relatively higher than that of the other subgroups, the AUC of L3 was significantly higher than that of L4. CONCLUSION: The fast ACTRESS was optimized and indicated that the labeling type of L3 was the most appropriate for the well visualization of intracranial arteries. The fast ACTRESS sequence was useful to acquire well-delineated images of intracranial vessels in ˂1min.

Unenhanced renal magnetic resonance angiography in patients with chronic kidney disease & suspected renovascular hypertension: Can it affect patient management?

BACKGROUND & OBJECTIVES: Renal artery stenosis (RAS) is an important cause of severe hypertension in patients with chronic kidney disease (CKD). It is important to detect RAS early as it can reverse hypertension and stop rapid deterioration of renal function. The potential drawbacks of various imaging modalities used to detect RAS including contrast-related adverse effects associated with diagnostic angiography have led to increasing interest in unenhanced magnetic resonance (MR) renal angiography. The aim of this study was to detect and grade RAS in patients with CKD and suspected renovascular hypertension using unenhanced MR angiography (UMRA) and to identify patients with significant RAS (>70%) who would subsequently require further investigation and revascularization. METHODS: Thirty five CKD patients with suspected RAS were subjected to UMRA using non-contrast MR angiography of ArTery and VEins 3D True fast imaging with steady state precession technique over a three year period. Patients with RAS >70 per cent on UMRA were subjected to digital subtraction angiography (DSA) with intervention if indicated. RESULTS: In all, 76 renal arteries were evaluated using UMRA in 35 patients, of which 18 arteries showed stenosis and 11 were haemodynamically significant (eight patients). Seven patients (10 renal arteries) underwent DSA. INTERPRETATION & CONCLUSIONS: An association between UMRA and DSA findings was obtained in six patients (nine renal arteries), and these patients were stented. Post-procedure follow up showed good improvement in blood pressure and renal function. UMRA was found to be a useful non-invasive imaging modality to detect RAS in CKD patients. It can identify patients who require further invasive angiography and revascularization.

Magnetic resonance angiography of fetal vasculature at 3.0 T.

Magnetic resonance angiography has not been used much previously for visualizing fetal vessels in utero for reasons that include a contraindication for the use of exogenous contrast agents, maternal respiratory motion and fetal motion. In this work, we report the feasibility of using an appropriately modified clinical time-of-flight magnetic resonance imaging sequence for non-contrast angiography of human fetal and placental vessels at 3.0 T. Using this 2D angiography technique, it is possible to visualize fetal vascular networks in late pregnancy. KEY POINTS: • 3D-visualization of fetal vasculature is feasible using non-contrast MRA at 3.0 T. • Visualization of placental vasculature is also possible with this method. • Fetal MRA can serve as a vascular localizer for quantitative MRI studies. • This method can be extended to 1.5 T.

Non-contrast-enhanced MRA of renal artery stenosis: validation against DSA in a porcine model.

OBJECTIVES: To compare 3D-inversion-recovery balanced steady-state free precession (IR-bSSFP) non-contrast-enhanced magnetic resonance angiography (MRA) with 3D-contrast-enhanced MRA (CE-MRA) for assessment of renal artery stenosis (RAS) using digital subtraction angiography (DSA) as the reference standard. METHODS: Bilateral RAS were surgically created in 12 swine. IR-bSSFP and CE-MRA were acquired at 1.5 T and compared to rotational DSA. Three experienced cardiovascular radiologists evaluated the IR-bSSFP and CE-MRA studies independently. Linear regression models were used to calibrate and assess the accuracy of IR-bSSFP and CE-MRA, separately, against DSA. The coefficient of determination and Cohen's kappa coefficient were also generated. RESULTS: Calibration of the three readers' RAS grading revealed R(2) values of 0.52, 0.37 and 0.59 for NCE-MRA and 0.48, 0.53 and 0.71 for CE-MRA. Inter-rater agreement demonstrated Cohen's kappa values ranging from 0.25 to 0.65. Distal renal artery branch vessels were visible to a significantly higher degree with NCE-MRA compared to CE-MRA (p < 0.001). Image quality was rated excellent for both sequences, although image noise was higher with CE-MRA (p < 0.05). In no cases did noise interfere with image interpretation. CONCLUSIONS: In a well-controlled animal model of surgically induced RAS, IR-bSSFP based NCE-MRA and CE-MRA accurately graded RAS with a tendency for stenosis overestimation, compared to DSA. KEY POINTS: • IR-bSSFP and CE-MRA are accurate methods for diagnosis of renal artery stenosis • IR-bSSFP and CE-MRA demonstrate excellent agreement with DSA • Both IR-bSSFP and CE-MRA have a tendency to overestimate renal artery stenosis.

Non-contrast enhanced 3D SSFP MRA of the renal allograft vasculature: a comparison between radial linear combination and Cartesian inflow-weighted acquisitions.

Renal transplant patients often require imaging to ensure appropriate graft placement, to assess integrity of transplant vessel anastomosis and to evaluate for stenosis that can be a cause of graft failure. Because there is risk for nephrogenic systemic fibrosis in the setting of renal insufficiency, the use of non-contrast MRA in these patients is helpful. In this study, the ability of two non-contrast MRA methods - 3D radial linear combination balanced SSFP (VIPR-SSFP) and inflow-weighted Cartesian SSFP (IFIR) - to visualize the transplant renal vessels is compared. Twenty-one renal transplant patients were scanned using the VIPR-SSFP and IFIR sequences. Diagnostic efficacy of the sequences was scored using a four point Likert scale according to the following criteria: overall image quality, fat suppression, and arterial/venous visualization quality. Average scores for each criterion were compared using the Wilcoxon signed-rank test. In addition to significantly improved venous visualization, the VIPR-SSFP sequence provided significantly improved fat suppression quality (p<0.03) compared to IFIR. VIPR-SSFP also identified several pathologies such as renal arterial pseudoaneurysm that were not visible on the IFIR images. However, IFIR afforded superior quality of arterial visualization (p<0.005). These two methods of non-contrast MR imaging each have significant strengths and are complementary to each other in evaluating the vasculature of renal allografts.

Time spatial labeling inversion pulse magnetic resonance angiography in pregnancy with adenomyosis.

Time spatial labeling inversion pulse (Time-SLIP) is a non-contrast magnetic resonance angiography (MRA) technique. No cases in which this technique was used during pregnancy have been reported. We report herein two cases with adenomyosis of the same size and location that underwent Time-SLIP MRA during pregnancy. In case 1, the blood flow within the adenomyosis was poor, and the uterine blood flow toward the placenta was normal, resulting in no fetal growth restriction (FGR). In case 2, the blood flow within the adenomyosis was quite rich, and placental blood flow seemed decreased, resulting in severe FGR. As well as the Doppler ultrasonography, Time-SLIP MRA was useful for evaluating uterine blood flow during pregnancy. This is the first report of the use of Time-SLIP MRA during pregnancy.