3D Contrast-enhanced MR Angiography Research Articles

Equilibrium Phase Contrast-Enhanced MR Angiography of the Thoracic Aorta and Heart using Balanced T1 Relaxation-Enhanced Steady-State (bT1RESS)

BackgroundThree-dimensional (3D) contrast-enhanced MR angiography (CEMRA) is routinely used for vascular evaluation. With existing techniques for CEMRA, diagnostic image quality is only obtained during the first pass of the contrast agent or shortly thereafter, whereas angiographic quality tends to be poor when imaging is delayed to the equilibrium phase. We hypothesized that prolonged blood pool contrast enhancement could be obtained by imaging with a balanced T1 relaxation-enhanced steady-state (bT1RESS) pulse sequence, which combines 3D balanced steady-state free precession (bSSFP) with a saturation recovery magnetization preparation to impart T1 weighting and suppress background tissues. An electrocardiographic (ECG)-gated, 2D-accelerated version with isotropic 1.1-mm spatial resolution was evaluated for breath-hold equilibrium phase CEMRA of the thoracic aorta and heart.Main bodyThe study was IRB approved. 21 subjects were imaged using unenhanced 3D bSSFP, time-resolved CEMRA, first pass gated CEMRA, followed by early and late equilibrium phase gated CEMRA and bT1RESS. 9 additional subjects were imaged using equilibrium phase 3D bSSFP and bT1RESS. Images were evaluated for image quality, aortic root sharpness, and visualization of the coronary artery origins, as well as using standard quantitative measures. ResultsEquilibrium phase bT1RESS provided better image quality, aortic root sharpness, and coronary artery origin visualization than gated CEMRA (P<0.05), and improved image quality and aortic root sharpness versus unenhanced 3D bSSFP (P<0.05). It provided significantly larger apparent signal-to-noise and apparent contrast-to-noise ratio values than gated CEMRA and unenhanced 3D bSSFP (P<0.05) and provided ninefold better fluid suppression than equilibrium phase 3D bSSFP. Aortic diameter and main pulmonary artery diameter measurements obtained with bT1RESS and first pass gated CEMRA strongly correlated (P<0.05). Discussion and ConclusionWe found that using bT1RESS greatly prolongs the useful duration of blood pool contrast enhancement while improving angiographic image quality compared with standard CEMRA techniques. Although further study is needed, potential advantages for vascular imaging include eliminating the current requirement for first pass imaging along with better reliability and accuracy for a wide range of cardiovascular applications.

Evaluating the diagnostic accuracy of 3D contrast-enhanced magnetic resonance angiography versus digital subtraction angiography in spinal dural arteriovenous fistulas.

Spinal dural arteriovenous fistulas (SDAVFs) often go undiagnosed, leading to irreversible spinal cord dysfunction. Although digital subtraction angiography (DSA) is the gold standard for diagnosing SDAVF, DSA is invasive and operator dependent, with associated risks. MR angiography (MRA) is a promising alternative. This study aimed to evaluate the performance of MRA as an equal alternative to DSA in investigating, diagnosing, and localizing SDAVF. Prospectively collected data from a single neurosurgeon at a large tertiary academic center were searched for SDAVFs. Eligibility criteria included any patient with a surgically proven SDAVF in whom preoperative DSA, MRA, or both had been obtained. The eligible patients formed a consecutive series, in which they were divided into DSA and MRA groups. DSA and MRA were the index tests that were compared to the surgical SDAVF outcome, which was the reference standard. Accurate diagnosis was considered to have occurred when the imaging report matched the operative diagnosis to the correct spinal level. Comparisons used a two-sample t-test for continuous variables and Fisher-Freeman-Halton's exact test for categorical variables, with p < 0.05 specifying significance. Univariate, bivariate, and multivariate analyses were conducted to investigate group associations with DSA and MRA accuracy. Positive predictive value, sensitivity, and accuracy were calculated. A total of 27 patients with a mean age of 63 years underwent surgery for SDAVF. There were 19 male (70.4%) and 8 female (29.6%) patients, and the mean duration of symptoms at the time of surgery was 14 months (range 2-48 months). Seventeen patients (63%) presented with bowel or bladder incontinence. Bivariate analysis of the DSA and MRA groups further revealed no significant relationships between the characteristics and accuracy of SDAVF diagnosis. MRA was found to be more sensitive and accurate (100% and 73.3%) than DSA (85.7% and 69.2%), with a subanalysis of the patients with both preoperative MRA and DSA showing that MRA had a greater positive predictive value (78.6 vs 72.7), sensitivity (100 vs 72.7), and accuracy (78.6 vs 57.1) than DSA. In surgically proven cases of SDAVFs, the authors determined that MRA was more accurate than DSA for SDAVF diagnosis and localization to the corresponding vertebral level. Incomplete catheterization at each vertebral level may result in the failure of DSA to detect SDAVF.

Non-contrast free-breathing 2D CINE compressed SENSE T1-TFE cardiovascular MRI at 3T in sedated young children for assessment of congenital heart disease.

Cardiac MRI is a crucial tool for assessing congenital heart disease (CHD). However, its application remains challenging in young children when performed at 3T. The aim of this retrospective single center study was to compare a non-contrast free-breathing 2D CINE T1-weighted TFE-sequence with compressed sensing (FB 2D CINE CS T1-TFE) with 3D imaging for diagnostic accuracy of CHD, image quality, and vessel diameter measurements in sedated young children. FB 2D CINE CS T1-TFE was compared with a 3D non-contrast whole-heart sequence (3D WH) and 3D contrast-enhanced MR angiography (3D CE-MRA) at 3T in 37 CHD patients (20♂, 1.5±1.4 years). Two radiologists independently assessed image quality, type of CHD, and diagnostic confidence. Diameters and measures of contrast and sharpness of the aorta and pulmonary vessels were determined. A non-parametric multi-factorial approach was used to estimate diagnostic accuracy for the diagnosis of CHD. Linear mixed models were calculated to compare contrast and vessel sharpness. Krippendorff's alpha was determined to quantify vessel diameter agreement. FB 2D CINE CS T1-TFE was rated superior regarding image quality, diagnostic confidence, and diagnostic sensitivity for both intra- and extracardiac pathologies compared to 3D WH and 3D CE-MRA (all p<0.05). FB 2D CINE CS T1-TFE showed superior contrast and vessel sharpness (p<0.001) resulting in the highest proportion of measurable vessels (740/740; 100%), compared to 3D WH (530/620; 85.5%) and 3D CE-MRA (540/560; 96.4%). Regarding vessel diameter measurements, FB 2D CINE CS T1-TFE revealed the closest inter-reader agreement (Krippendorff's alpha: 0.94-0.96; 3D WH: 0.78-0.94; 3D CE-MRA: 0.76-0.93). FB 2D CINE CS T1-TFE demonstrates robustness at 3T and delivers high-quality diagnostic results to assess CHD in sedated young children. Its ability to function without contrast injection and respiratory compensation enhances ease of use and could encourage widespread adoption in clinical practice.

Comparison of Biplane Area-Length Method and 3D Volume Quantification by Using Cardiac MRI for Assessment of Left Atrial Volume in Atrial Fibrillation

To compare maximum left atrial (LA) volume (LAV) from the routinely used biplane area-length (BAL) method with three-dimensional (3D)-based volumetry from late gadolinium-enhanced MRI (3D LGE MRI) and contrast-enhanced MR angiography (3D CE-MRA) in patients with atrial fibrillation (AF). Sixty-four patients with AF (mean age, 63 years ± 9 [SD]; 40 male patients) were retrospectively included from a prospective cohort acquired between October 2018 and February 2021. All patients underwent a research MRI examination that included standard two- and four-chamber cine acquisitions, 3D CE-MRA, and 3D LGE MRI performed prior to the atrial kick. Contour delineation on cine imaging and LA 3D segmentations were performed by a radiologist. Maximum LAV (BALmax) was extracted from the BAL volume-time curve and compared with LAV from 3D CE-MRA and 3D LGE MRI. The Kruskal-Wallis test was performed, followed by the Dunn post hoc test and Bland-Altman analyses. Interobserver variability was assessed in 10 patients. BALmax underestimated LAV compared with 3D CE-MRA (bias: -23.5 mL ± 46.2, P < .001) and 3D LGE MRI (bias: -31.3 mL ± 58.3, P < .001), whereas 3D LGE MRI volumes showed no evidence of a difference from 3D CE-MRA (bias: 7.8 mL ± 45.7, P = .38). Interobserver variability yielded excellent agreement for each method (intraclass correlation coefficient, 0.96-0.98). BALmax underestimated LAV in patients with AF compared with 3D LGE MRI and 3D CE-MRA, suggesting that the geometric assumption of an ellipsoidal LA shape in BAL does not reflect LA geometry in patients with AF.Keywords: Left Atrial Volume, Biplane Area-Length, Late Gadolinium-enhanced 3D MRI, Contrast-enhanced 3D MR Angiography, Atrial Fibrillation Supplemental material is available for this article. © RSNA, 2023.

Strong Contrast Stagnation of Unilateral Vertebral Artery on Three-Dimensional Black Blood-Enhanced MRI Predicts Acute Medulla Infarction.

This study aimed to evaluate angiographic and contrast enhancement (CE) patterns on three-dimensional (3D) black blood (BB) contrast-enhanced MRI in patients with acute medulla infarction. From January 2020 to August 2021, we retrospectively analyzed stroke 3D BB contrast-enhanced magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) findings of patients visiting the emergency room for symptom evaluation of acute medulla infarction. In total, 28 patients with acute medulla infarction were enrolled in this study. Four types of 3D BB contrast-enhanced MRI and MRA were classified as follows: 1=unilateral contrast-enhanced vertebral artery (VA)+no visualization of VA on MRA; 2=unilateral enhanced VA+hypoplastic VA; 3=no enhanced VA+unilateral complete occlusion of VA; 4=no enhanced VA+normal VA (including hypoplasia) on MRA. Of the 28 patients with acute medulla infarction, 7 (25.0%) showed delayed positive findings after 24 hours on diffusion-weighted imaging (DWI). Of these patients, 19 (67.9%) showed CE of the unilateral VA on 3D BB contrast-enhanced MRI (type 1 and 2). Of the 19 patients with CE of VA on 3D BB contrast-enhanced MRI, 18 showed no visualization of enhanced VA on MRA (type 1), and 1 showed hypoplastic VA. Of the 7 patients with delayed positive findings on DWI, 5 showed CE of the unilateral VA and no visualization of the enhanced VA on MRA (type 1). Symptom onset to door time or initial MR check time was significantly shorter in the groups with delayed positive findings on DWI (P<0.05). Unilateral CE on 3D BB contrast-enhanced MRI and no visualization of the VA on MRA are related to the recent occlusion of the distal VA. These findings suggest that the recent occlusion of the distal VA is related to acute medulla infarction, including delayed visualization on DWI.

Imaging of the extracranial internal carotid artery in acute ischemic stroke: assessment of stenosis, plaques, and image quality using relaxation-enhanced angiography without contrast and triggering (REACT).

In stroke magnetic resonance imaging (MRI), contrast-enhanced magnetic resonance angiography (CE-MRA) is the clinical standard to depict extracranial arteries but native MRA techniques are of increased interest to facilitate clinical practice. The purpose of this study was to assess the detection of extracranial internal carotid artery (ICA) stenosis and plaques as well as the image quality of cervical carotid arteries between a novel flow-independent relaxation-enhanced angiography without contrast and triggering (REACT) sequence and CE-MRA in acute ischemic stroke (AIS). In this retrospective, single-center study, 105 consecutive patients (65.27±18.74 years, 63 males) were included, who received a standard stroke protocol at 3T in clinical routine including Compressed SENSE (CS) accelerated (factor 4) 3D isotropic REACT (fixed scan time: 02:46 min) and CS accelerated (factor 6) 3D isotropic CE-MRA. Three radiologists independently assessed scans for the presence of extracranial ICA stenosis and plaques (including hyper-/hypointense signal) with concomitant diagnostic confidence using 3-point scales (3= excellent). Vessel quality, artifacts, and image noise of extracranial carotid arteries were subjectively scored on 5-point scales (5= excellent/none). Wilcoxon tests were used for statistical comparison. Considering CE-MRA as the standard of reference, REACT provided a sensitivity of 89.8% and specificity of 95.2% for any and of 93.5% and 95.8% for clinically relevant (≥50%) extracranial ICA stenosis and yielded a to CE-MRA comparable diagnostic confidence [mean ± standard deviation (SD), median (interquartile range): 2.8±0.5, 3 (3-3) vs. 2.7±0.5, 3 (2-3), P=0.03]. Using REACT, readers detected more plaques overall (n=57.3 vs. 47.7, P<0.001) and plaques of hyperintense signal (n=12.3 vs. 5.7, P=0.02) with higher diagnostic confidence [2.8±0.5, 3 (3-3) vs. 2.6±0.7, 3 (2-3), P<0.001] than CE-MRA. After analyzing a total of 1,260 segments, the vessel quality of all segments combined [4.61±0.66 vs. 4.58±0.68, 5 (4-5) vs. 5 (4-5), P=0.0299] and artifacts [4.51±0.70 vs. 4.44±0.73, 5 (4-5) vs. 5 (4-5), P>0.05] were comparable between the sequences with REACT showing a lower image noise [4.43±0.67 vs. 4.25±0.71, 5 (4-5) vs. 4 (4-5), P<0.001]. Without the use of gadolinium-based contrast agents or triggering, REACT provides a high sensitivity and specificity for extracranial ICA stenosis and a potential improved depiction of adjacent plaques while yielding to CE-MRA comparable vessel quality in a large patient cohort with AIS.

Fast three-dimensional contrast-enhanced magnetic resonance angiography of the canine lumbar spinal cord vascular supply: A feasibility study.

Magnetic resonance angiography (MRA) is the noninvasive spinal cord vascular imaging modality of choice in human medicine. The aim of this exploratory, prospective, descriptive study was to assess the feasibility of fast three-dimensional (3D) contrast-enhanced (CE) MRA for visualization of spinal vascular structures in the canine lumbar region. Fourteen canine patients weighing>5kg were included. The lumbar arteries were consistently visualized (14/14;100%). Spinal arteries, radicular branches, great radicular artery (of Adamkiewicz), ventral spinal artery, and dorsal spinal arteries were not visualized (0/14;0%). The internal vertebral venous plexus was visualized in 11 of 14 (79%) dogs. Overall, the results of this study show that fast 3D CE-MRA of the lumbar region in dogs is feasible. However, the smaller arteries responsible for the spinal cord vascular supply were not visualized in this study.

Usefulness of contrast-enhanced 3D MR angiography and contrast-enhanced 3D T1 sequence for detecting intracranial infectious aneurysms in infectious endocarditis

ObjectivesTo assess the diagnostic value of contrast-enhanced MRA (CE MRA) and CE 3D-T1 for identifying intracranial infectious aneurysms (IIAs) in infective endocarditis (IE) with digital substraction angiography (DSA) as reference. MethodsTwenty-one IE patients (14 males; mean age: 53 years) with 30 IIAs, diameter ranging 1.5–15 mm (<3mm, n = 14, 46.7%; 3–5 mm, n = 12,40%), underwent CE MRA and CE 3D-T1 at 1.5 T. Two readers evaluated images for aneurysm detection, characterization, quality of visualization. DSA was obtained at a median of 3 days (range 1–15) after MRI. ResultsThe sensitivity, specificity, positive and negative predictive values and accuracy of IIA detection were respectively: 80%, 100%, 100%, 82.3%, 90% for CE MRA and 86.7%, 100%, 100%, 88.2%, 93.3% for CE 3D T1 compared to DSA.No significant difference was observed between CE MRA and CE 3D-T1 for accuracy and quality of visualization. All IIAs of ≥3 mm in diameter (16/30; 53.%) were identified by both sequences, which were also able to detect IIAs ≤ 3 mm (n = 14/30, 46.7%). False negatives were observed with both sequences for 4 IIAs of <2 mm, 3 being compressed by hemorrhagic lesions. Two other IIAs of <2 mm were overlooked by CE MRA. CE 3D-T1 overestimated IIAs luminal diameter by 8% relatively to DSA (P = NS).Intra and inter-observer agreement were good and similar with both methods. ConclusionBoth CE MRA and CE 3D-T1 have good accuracy compared to DSA detection and characterization of IIAs. CE 3D-T1 also evaluates anatomical relationships of IIAs, which could help DSA location and endovascular treatment.

The role of CE-MRA of the supraortic vessels in the detection of associated intracranial pathology.

Contrast-enhanced magnetic resonance angiography (CE-MRA) has become a very popular imaging technique in the evaluation of the extracranial vessels pathology, while it is not commonly used to rule out intracranial vascular pathology. On the contrary, 3D time of flight MRA (TOF-MRA) has a solid role in the study of intracranial arterial vessels disease. One hundred and eight patients were consecutively included in the study. All patients were submitted to a 3 Tesla 3D CE-MRA imaging to rule out extracranial vessels pathology. A comparison was made with a 3D-TOF sequence acquired at the same time in the assessment of intracranial vessels diseases such as steno-occlusion, dissection, and aneurysms. With regard to steno-occlusive disease, Spearman's rank correlation coefficient was of 0.56 for stenosis detection and of 0.57 for occlusive disease detection. The two techniques shared similar results in the evaluation of anterior circulation, while 3D-TOF found higher grades of stenosis for posterior circulation. With regard to dissection, Spearman's rank correlation coefficient was of 0.7. 3D-TOF depicted more intramural hematoma (Spearman's rank = 0.46), while CE-MRA showed more pseudo-aneurysms (Spearman's rank = 0.56). Both the technique equally evaluated the presence of intracranial aneurysms (Spearman's rank = 1). CE-MRA can be considered a reliable tool to rule out intracranial pathology associated to supraortic steno-occlusive disease, also allowing time reduction. In the suspicion of dissection a T1-weighted sequence has to be added to detect the presence of a subacute vessel wall hematoma.

Strong enhancement on three-dimensional black-blood enhanced magnetic resonance imaging: Comparison intracranial stenosis and complete occlusion

PurposeThe purpose of this study was to evaluate contrast enhancement patterns on three-dimensional (3D) black blood (BB) contrast-enhanced magnetic resonance (MR) imaging in patients with occlusion or stenosis of the anterior intracranial artery. Materials and methodsFrom January 2018 to January 2020 we retrospectively reviewed stroke 3D BB contrast-enhanced MR imaging and MR angiography findings of patients visiting the emergency room for evaluation of non-traumatic brain lesions. In total, 92 patients with positive findings on 3D BB contrast-enhanced MR imaging were enrolled in this study. We divided the enrolled group according to whether MR angiography findings suggested complete occlusion, high-grade stenosis (51–99 %), or low-grade stenosis (10–50 %). ResultsOf 92 patients, 33 had complete occlusion in the anterior intracranial artery, 36 had high-grade stenosis, and 23 had low-grade stenosis. The complete occlusion group showed concentric and segmental enhancement on 3D BB enhanced MR imaging. The high-grade stenosis group frequently showed concentric and focal enhancement. The high signal vessel sign in the complete occlusion group was significantly higher compared to the stenosis group (p < 0.001). The contrast ratio between the lesion and pituitary gland in the occlusion group was significantly lower than that of the stenosis group (p < 0.05). ConclusionBright contrast enhancement and high signal vessel sign on 3D BB contrast enhanced MR imaging are related to contrast stagnation of the occlusion site and slow flow of a distal portion of the occlusion site.

ECG-gated MR angiography provides better reproducibility for standard aortic measurements.

Cardiac motion and aortic pulsatility can affect the image quality of 3D contrast-enhanced MR angiography (CE-MRA). The addition of ECG gating improves image quality; however, no studies have directly linked image quality improvements to clinically used measures. In this study, we directly compared diameter measurements in the same patient from ECG-gated to non-gated CE-MRA to evaluate the impact of ECG gating upon measurement reproducibility. Fifty-three patients, referred for thoracic aortic angiography, were enrolled and underwent both non-gated and ECG-gated CE-MRA. Two readers independently measured vessel diameter, image quality, and vessel sharpness at the sinus of Valsalva (SOV), sinotubular junction (STJX), ascending aorta (AAO), distal aortic arch (DLSA), and descending aorta (DAO). Measurement reliability and reproducibility were compared between methods. Image quality with ECG gating was rated significantly higher at the SOV (3.2 ± 0.9 vs 1.2 ± 1.0, p < 0.0001), STJX (3.4 ± 0.7 vs 1.8 ± 1.0, p < 0.0001), AAO (3.5 ± 0.6 vs 1.7 ± 1.1 p < 0.0001), DLSA (4.0 ± 0.1 vs 3.6 ± 0.7, p = 0.006), and DAO (4.0 ± 0.1 vs 3.4 ± 0.9 p < 0.0001) than for non-gated studies. Bland-Altman analyses demonstrated that inter- and intra-observer variability was significantly smaller for ECG-gated MRA at the SOV and AAO. For the non-gated images at the SOV, the 95% limits of agreement for both inter- and intra-observer variability exceeded the growth-rate cutoff for surgical repair (0.5 cm). At the DAO, variability was similar between the two techniques. ECG-gated CE-MRA resulted in improved reproducibility in aortic root and ascending aortic measurements. These data suggest that ECG-gated CE-MRA should be used for the serial assessment of the ascending thoracic aorta. • ECG-gated CE-MRA improves the reproducibility and repeatability of measurements of the ascending aorta. • With non-gated CE-MRA, pulsatile motion in the proximal aorta results in significant variability in measurement reproducibility.

Non-contrast MR angiography versus contrast enhanced MR angiography for detection of renal artery stenosis: a comparative analysis in 400 renal arteries.

In this study, we compared non-contrast MR angiography (NC-MRA) with conventional 3D contrast-enhanced MRA (CE-MRA) in patients suspected to have renal artery stenosis (RAS). From March 2014 to March 2020, patients who were evaluated for RAS and had a glomerular filtration rate > 30ml/min/1.73 m2 underwent MR imaging on a 3T MR Scanner (Signa Hdxt General Electrics, Milwaukee, USA) using a Torso PA coil. The NC-MRA sequence was performed using a 3D fat-suppressed inflow inversion recovery balanced steady state free precession (SSFP) sequence (Inhance 3D Inflow IR, GE Medical) whereas the CE-MRA sequence was a 3D fast spoiled gradient echo (FSPGR). Overall quality of images was rated 1 to 4. Stenosis was reported as grade 1 (Normal), 2 (< 50% narrowing), 3 (> 50% narrowing) and 4 (Total occlusion). Grade 3 and 4 were considered haemodynamically significant. During the study period, 201 patients were enrolled (400 renal arteries). For hemodynamically significant (grade 3/4) stenosis, NC-MRA correctly diagnosed 72 patients (95 arteries) while in 2 patients (2 arteries), NC-MRA underdiagnosed the stenosis as grade 2 (these were found to have grade 3 stenosis on CE-MRA). The kappa value of agreement between NC-MRA and CE-MRA for detection of RAS showing excellent agreement (p < 0.001). In one of the largest series of patients so far, we found that NC-MRA is a viable alternative to CE-MRA for detection of RAS, highly correlating with CE-MRA for grade of stenosis and with additional advantage of lack of gadolinium based contrast agents toxicity.

Comparison of a novel Compressed SENSE accelerated 3D modified relaxation-enhanced angiography without contrast and triggering with CE-MRA in imaging of the thoracic aorta

To compare a novel Compressed SENSE accelerated ECG- and respiratory-triggered flow-independent 3D isotropic Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT) with standard non-ECG-triggered 3D contrast-enhanced magnetic resonance angiography (CE-MRA) for imaging of the thoracic aorta in patients with connective tissue diseases (CTD) or other aortic diseases using manual and semiautomatic measurement approaches. This retrospective, single-center analysis of 30 patients (June–December 2018) was conducted by two radiologists, who independently measured aortic diameters on modified REACT and CE-MRA using manual (Multiplanar-Reconstruction) and semiautomatic (Advanced Vessel Analysis) measurement tools on seven levels (inner edge): Aortic annulus and sinus, sinotubular junction, mid- and high-ascending aorta, aortic isthmus, and descending aorta. Bland–Altman analysis was conducted to evaluate differences between the mean values of aortic width and ICCs were calculated to assess interobserver agreement. For each level, image quality was evaluated on a four-point scale in consensus with Wilcoxon matched-pair test used to evaluate for differences between both MRA techniques. Additionally, evaluation time for each measurement technique was noted, which was compared applying one-way ANOVA. When comparing both imaging and measurement methods, CE-MRA (mean difference 0.24 ± 0.27 mm) and the AVA-tool (− 0.21 ± 0.15 mm) yielded higher differences compared to modified REACT (− 0.11 ± 0.11 mm) and the MPR-tool (0.07 ± 0.21 mm) for all measurement levels combined without yielding clinical significance. There was an excellent interobserver agreement between modified REACT and CE-MRA using both tools of measurement (ICC > 0.9). Modified REACT (average acquisition time 06:34 ± 01:36 min) provided better image quality from aortic annulus to mid-ascending aorta (p < 0.05), whereas at distal measurement levels, no significant differences were noted. Regarding time requirement, no statistical significance was found between both measurement techniques (p = 0.08). As a novel non-CE-MRA technique, modified REACT allows for fast imaging of the thoracic aorta with higher image quality in the proximal aorta than CE-MRA enabling a reliable measurement of vessel dimensions without the need for contrast agent. Thus, it represents a clinically suitable alternative for patients requiring repetitive imaging. Manual and semiautomatic measurement approaches provided comparable results without significant difference in time need.

Peri-thrombus vascular hyperintensity sign: detection of intracranial thrombus location and length in acute ischemic stroke.

The aim of the study was to investigate the diagnostic accuracy of peri-thrombus vascular hyperintensity sign (PVHS) on three-dimensional (3D) black-blood (BB) contrast-enhanced MRI for the detection of intracranial thrombus location and length in acute ischemic stroke (AIS) patients. Consecutive AIS patients who underwent MRI including 3D BB contrast-enhanced MRI sequence within 8h of clinical onset were prospectively evaluated. Two readers independently reviewed the 3D BB contrast-enhanced MRI data to assess the presence and location of PVHS. Findings were compared with those of contrast-enhanced MR angiography (CE-MRA) as the reference standard. The PVHS was identified in 49% (63/129) of AIS patients with good agreement. The PVHS had 100% specificity, 88% negative predictive value, 89% sensitivity, and 100% positive predictive value for detection of acute arterial occlusions. Eight patients showed discordant thrombus locations between 3D BB contrast-enhanced MRI and CE-MRA. Median thrombus length in patients with complete occlusion was 9.61mm. The PVHS on 3D BB contrast-enhanced MRI is a highly specific tool for evaluating the location and length of a thrombus in AIS patients.

Cost and Utility of Routine Contrast-Enhanced Neck MRA in a Pediatric MRI Stroke Evaluation Protocol.

Cervical arterial dissection is one of the frequent causes of pediatric arterial ischemic stroke. Out of concern for missing cervical arterial dissection in patients in whom pediatric stroke is suspected, our tertiary children's hospital added contrast-enhanced 3D neck MR angiography to every pediatric stoke work-up. This research investigated whether the routine use of contrast-enhanced neck MRA in our MR imaging stroke protocol ever detected a cervical arterial abnormality when the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings from the brain MR imaging were reported as normal. The institutional PACS data base was searched for stroke protocol MRIs that included DWI, gradient recalled-echo or SWI, circle of Willis MRA, and 3D contrast-enhanced neck MRA in patients younger than 18 years of age with examinations performed between September 2010 and June 2017. In only a single case (0.15%) were the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings all separately reported as normal and the contrast-enhanced neck MRA findings reported as abnormal. To reach these findings, we screened 681 patients, which would have resulted in an estimated >$200,000 in Medicare charges and $80,000 in of out-of-pocket cost to patients. In our large series, the addition of a routine contrast-enhanced neck MRA to our pediatric stroke MR imaging protocol was of extremely low yield. We believe the use of neck MRA should reasonably be limited to cases in which abnormalities are initially detected on standard brain sequences or to patients with atypical presentation or recurrent pathology.

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

BackgroundThe 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.MethodsThe 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.ResultsCohen’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.ConclusionsNon-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.

Depiction of the Superior Petrosal Vein Complex by 3D Contrast-Enhanced MR Angiography.

Intraoperative obliteration of the superior petrosal vein complex has a relevant risk of postoperative complications. A large venous diameter and the absence of anastomoses have been previously suggested as possible risk factors. 3D contrast-enhanced MRA was evaluated for the identification of superior petrosal vein anatomy. Twenty-five patients (10 men; age, 20-77 years) with a 3D-MRA (voxel size, 0.4 × 0.4 × 0.5 mm3) at 3T, including the posterior fossa, were retrospectively identified. Image evaluation was performed independently by 2 neuroradiologists with respect to overall image quality and the presence, location, size, tributaries, and anastomotic veins of the superior petrosal vein complex. Additionally, 8 neurosurgical cases with intraoperative validation of the venous anatomy were examined. All studies were of diagnostic image quality. Interobserver agreement was excellent for image-quality measurements (r = 0.751-0.982) and good for measured vessel size (r = 0.563-0.828). A total of 83 superior petrosal veins were identified. The distribution of drainage locations and identification of tributaries and anastomotic veins were consistent with previous anatomic studies. The results showed that 4.8% of superior petrosal veins had a diameter of >2 mm and lacked a visible anastomosis. All surgical cases showed excellent agreement between the MRA and the intraoperative observations. 3D-MRA with high resolution is appropriate for analyzing the size, course, tributaries, and anastomoses of the superior petrosal vein. A total of 4.8% of the identified superior petrosal veins had to be classified as potential high-risk veins. The measurements correlated with the intraoperative findings.

Contrast-Enhanced Magnetic Resonance Angiography Using a Novel Elastin-Specific Molecular Probe in an Experimental Animal Model.

Objectives The aim of this study was to test the potential of a new elastin-specific molecular agent for the performance of contrast-enhanced first-pass and 3D magnetic resonance angiography (MRA), compared to a clinically used extravascular contrast agent (gadobutrol) and based on clinical MR sequences. Materials and Methods Eight C57BL/6J mice (BL6, male, aged 10 weeks) underwent a contrast-enhanced first-pass and 3D MR angiography (MRA) of the aorta and its main branches. All examinations were on a clinical 3 Tesla MR system (Siemens Healthcare, Erlangen, Germany). The clinical dose of 0.1 mmol/kg was administered in both probes. First, a time-resolved MRA (TWIST) was acquired during the first-pass to assess the arrival and washout of the contrast agent bolus. Subsequently, a high-resolution 3D MRA sequence (3D T1 FLASH) was acquired. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated for all sequences. Results The elastin-specific MR probe and the extravascular imaging agent (gadobutrol) enable high-quality MR angiograms in all animals. During the first-pass, the probes demonstrated a comparable peak enhancement (300.6 ± 32.9 vs. 288.5 ± 33.1, p > 0.05). Following the bolus phase, both agents showed a comparable intravascular enhancement (SNR: 106.7 ± 11 vs. 102.3 ± 5.3; CNR 64.5 ± 7.4 vs. 61.1 ± 7.2, p > 0.05). Both agents resulted in a high image quality with no statistical difference (p > 0.05). Conclusion The novel elastin-specific molecular probe enables the performance of first-pass and late 3D MR angiography with an intravascular contrast enhancement and image quality comparable to a clinically used extravascular contrast agent.

PULMONARY ARTERY MORPHOLOGY AS A BIOMARKER OF PULMONARY HYPERTENSION

As pulmonary hypertension (PH) is associated with poor prognostic and survival outcomes, an early PH diagnosis is crucial for optimal patient care. In this study, we aimed to demonstrate PH induces pulmonary artery (PA) remodeling and alterations in right cardiac function. In this study, 36 PH patients and eight healthy controls were retrospectively assessed for PA remodeling using a 3T MRI scanner standard cardiac imaging protocol including 3D contrast-enhanced magnetic resonance angiography (CE-MRA). Data analysis was performed with CVI42 software (Circle Cardiovascular Imaging Inc., Calgary, Canada) to measure heart function from bi-planar analysis, and PA remodeling via diameter, bifurcation distances, and bifurcation angles (Figure 1). Analysis of bifurcation angles and distances were performed in 20 patients. PH patients demonstrate differences in right ventricular function (Table 1). In addition, PH patients display greater diameters relative to controls in the LPA (AP: p = 0.002, CC: p < 0.001), MPA (AP: p = 0.003, CC: p = 0.001), and RPA (AP: p = 0.001, CC: p < 0.001). PH patients also demonstrated greater bifurcation distances in the MPA (p = 0.027), RPA (p = 0.001), and LPA (p = 0.009). Each AP-CC diameter (p < 0.001 for all), and the RPA bifurcation distance (p = 0.005) demonstrate correlations to the RVEF. This study suggests PA remodeling (PA diameters, bifurcation angles, bifurcation distances) can be used as biomarkers of PH by characterizing disease severity.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Non contrast versus contrast enhanced MRI of the great thoracic vessels in pediatric congenital heart disease: A quantitative and qualitative analysis

AimTo compare 3D steady-state free-precession (SSFP) non-contrast magnetic resonance angiography (NC-MRA) with contrast-enhanced MRA (CE-MRA) for quantitative and qualitative analysis of thoracic arteries in pediatric patients with congenital heart disease. MethodologyForty patients with thoracic vascular anomalies (22 boys & 18 girls) ranging in age between 6 months and 14 years (mean age 4.58 ± 4.5) were included in this prospective study. Measurements of the thoracic arteries were taken by 3D SSFP NC-MRA & CE-MRA. Image quality was assessed using a four-point score. Pearson's and Spearman's Correlation Coefficients were calculated for correlation analysis while Student's t and Mann-Whitney U tests were used for comparative analysis, Bland-Altman plots were employed to demonstrate the level of agreement between the 2 techniques. ResultsMeasurements from NC-CMRA images were comparable to those from CE-MRA. All measures highly correlated (r > 0.9), 3D SSFP NC-MRA exhibited a significantly higher image quality score than contrast- enhanced MRA, the mean difference was significantly lower than that of the 3D SSFP; (p-value <0.0001). ConclusionNC-MRA produced similar and comparable measurements of the thoracic arteries with superior image quality when compared to contrast- enhanced MRA in pediatric congenital heart defects.