Three-dimensional Magnetic Resonance Angiography Research Articles

Are the anomalous vertebral arteries more hypoplastic?: retrospective linear mixed model approach

BackgroundSmall or hypoplastic vertebral artery (VA) is one of the risk factor for posterior circulation stroke. We assess whether various types of VA anomaly contribute to its diameter.MethodsWe screened 238 patients who underwent neck CT and MR angiography within 1 month. A V1 anomaly was defined as the abnormal origin of the VA on a three-dimensional MR angiography and a V2 anomaly was defined as the VA not passing through the 6th cervical transverse foramen (TF) on an axial CT image. A linear mixed model was used to evaluate the determinants of VA size.ResultsAmong participants, 24 (10.1%) subjects exhibited an anomalous VA and, of the 476 VAs examined, 11 (2.3%) had an aortic origin and 27 (5.7%) had an abnormal entrance into the C6 TF. Presence of the V1 anomaly was positively associated with the V2 anomaly (P for chi-square < 0.001) and a linear mixed model revealed that being male (0.2 mm larger, P = 0.015), having a right VA anomaly (0.3 mm smaller, P < 0.001), having a V1 anomaly (0.9 mm smaller, P < 0.001), and having a V2 anomaly (0.7 mm smaller, P < 0.001) were significant predictor of VA diameter.ConclusionThe diameters of VAs with an anomalous aortic origin or an abnormal entrance of the TF were significantly smaller than those of normal VAs. These findings suggest that anomalies of the VA detected in 3-dimensional CTA or MRA may be clues for vertebral artery hypoplasia.

Fast three-dimensional whole-body post-mortem magnetic resonance angiography

Abstract Purpose The goal of this study was to perform whole-body post-mortem magnetic resonance (PMMR) angiography with imaging quality comparable to that of post-mortem computed tomography (PMCT) angiography. Methods After contrast medium injection into the arterial and venous vascular system of seven human corpses PMMR was performed using a fast three-dimensional T1 weighted spoiled gradient-echo sequence, followed by PMCT imaging. The contrast medium volumes inside the descending aorta and inside the inferior vena cava were measured both on PMMR and on PMCT images by means of image segmentation. Visualization quality of arterial and venous vessels as a function of contrast filling was scored according to a four-point scale and compared using the paired Wilcoxon signed rank test. Results The contrast medium volume in the descending aorta decreased 12% on average from PMMR to PMCT angiography, while the contrast medium volume in the inferior vena cava increased by 11% on average. A total of 410 vessels were analyzed. Scores for all vessels were statistically significantly smaller for the PMMR angiography when compared to PMCT angiography (p = 0.01). No statistically significant differences were found for the subgroups of large vessels (p = 0.21), for the head and neck (p = 0.16) or the abdomen (p = 0.83) as well as for the thorax when the coronary arteries were left out (p = 0.23). Conclusions This study demonstrates that immediate image acquisition after contrast injection and rapid 3D whole-body image acquisition offers good image quality in PMMR angiography with a vascular contrast comparable to PMCT angiography.

Evaluation of fistulas locations of spinal dural arteriovenous fistula by three-dimensional dynamic contrast-enhanced MR angiography

Evaluation of fistulas locations of spinal dural arteriovenous fistula by three-dimensional dynamic contrast-enhanced MR angiography

Comparison of Non-Contrast Magnetic Resonance Angiography Using Inflow Inversion Recovery (Inhance) Technique and Contrast-Enhanced Magnetic Resonance Angiography in the Assessment of Renal Arteries of Patients with Hypertension

Background: Renal artery stenosis can cause renovascular hypertension manifesting clinically as high blood pressure. Objectives: In this study, we determined the efficiency of non-contrast magnetic resonance angiography (NC-MRA) using the inflow inversion recovery (inhance) method in the evaluation of renal arteries of hypertensive patients. Patients and Methods: Three-dimensional (3D) contrast-enhanced magnetic resonance angiography (CE-MRA) and NC-MRA were used to prospectively evaluate 66 patients diagnosed with hypertension. 3D CE-MRA and digital substractional angiography served as the gold standards. Image quality, number of main/accessory renal arteries, and main renal artery diameters were assessed. Statistical analyses were based on paired-t tests and intra-class correlation coefficients. Results: Of the 126 main renal and 12 accessory renal arteries reviewed in this study, NC-MRA overall image quality was good or excellent in more than 89.5%. An image quality of 94% was recorded for both left and right sides with CE-MRA. The differences between the 3D CE-MRA and NC-MRA readings for the renal artery ostium and proximal, medial, and distal segment diameters were not significant (P > 0.05). Inter-reader agreement regarding all segments was excellent. 3D CE-MRA was superior to NC-MRA in assessing accessory renal arteries (detection ratio using NC-MRA: 7/12, 58%). Conclusion: NC-MRA using the inhance method to image the anatomy of the renal artery provides an alternative to CE-MRA in patients with hypertension.

Non-contrast enhanced navigator-gated balanced steady state free precession magnetic resonance angiography as a preferred magnetic resonance technique for assessment of the thoracic aorta

To compare the objective and subjective image quality of non-contrast three-dimensional (3D) navigator-gated balanced steady state free precession magnetic resonance angiography (NC-MRA) and contrast-enhanced magnetic resonance angiography (CE-MRA) along the entire thoracic aorta. Fifty consecutive patients with thoracic aortic disease underwent NC-MRA and CE-MRA using a 1.5T MRI system. Vessel sharpness was assessed using signal intensity profiles at five predefined levels of the thoracic aorta. Two readers scored subjective quality. Manual diameter measurements of both readers were used for calculation of interobserver variation. NC-MRA resulted in significantly sharper delineation of the aortic root, ascending aorta, and distal descending aorta compared to CE-MRA. Sharpness was comparable at the level of the arch and proximal descending aorta. NC-MRA resulted in significantly better subjective image quality. Interobserver agreement for diameter measurements was excellent for both techniques. NC-MRA resulted in superior image quality for assessment of the thoracic aorta and in better vessel sharpness for assessment of the aortic root and ascending aorta, when compared to CE-MRA. NC-MRA can be considered the MRA technique of choice for the assessment of the thoracic aorta diameters in clinical practice.

Subarachnoid Hemorrhage in Patients with Good Clinical Grade: Accuracy of 3.0-T MR Angiography for Detection and Characterization.

Purpose To evaluate the diagnostic accuracy of aneurysm detection and the fidelity of morphologic characterization of three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography at 3.0 T in patients with a Glasgow coma score of 15 and noncontrast material-enhanced computed tomography (CT) findings that showed acute nontraumatic subarachnoid hemorrhage. Materials and Methods The institutional review board approved this prospective study, and patients provided informed consent. A total of 277 patients who had not experienced trauma but in whom nonenhanced CT showed subarachnoid hemorrhage, who had a Glasgow coma score of 15, and who underwent both 3D TOF MR angiography and digital subtraction angiography (DSA) (the reference standard) were included. Three observers who were blinded to clinical and DSA results independently analyzed all 3D TOF MR angiographic data sets. The receiver operating characteristic curve was applied to analysis of the detection of aneurysms with 3D TOF MR angiography by using patient- and aneurysm-based evaluations. Multivariate logistic regression analysis was performed to identify aneurysm-specific variables, including size, shape (daughter sac/lobulation/margin), neck width (wide if > 4 mm or if fundus-to-neck ratio was < 2), and relation to adjacent artery, that significantly affected morphologic assessment with 3D TOF MR angiography. Results Aneurysms were depicted with DSA in 225 patients. In patient- and aneurysm-based evaluations, respectively, 3D TOF MR angiography yielded accuracies of 96.8% (268 of 277) and 96.6% (309 of 320), sensitivities of 98.2% (219 of 223) and 98.1% (260 of 265), specificities of 91% (49 of 54) and 89% (49 of 55), positive predictive values of 97.8% (219 of 224) and 97.7% (260 of 266), and negative predictive values of 92% (49 of 53) and 91% (49 of 54). Accuracy of display of morphologic features was 92.5% (236 of 255) for size, 86.3% (220 of 255) for neck width, 94.5% for shape (241 of 255), and 96.9% (247 of 255) for relationship to adjacent vessel. Width of aneurysm neck was the only variable that significantly affected the morphologic assessment of 3D TOF MR angiography (odds ratio, 0.378; 95% confidence interval: 0.337, 8.347; P = .004). Conclusion Three-dimensional TOF MR angiography can accurately depict cerebral aneurysms and accurately display their morphologic features in stable patients with subarachnoid hemorrhage and a Glasgow coma score of 15. © RSNA, 2017.

Abstract TMP33: High Intensity Signal in the Plaque on 3DTOF MRA is Associated With Ischemic Stroke in the Patients With Low Grade Carotid Artery Stenosis

Background: Carotid artery stenosis is one of the major causes of ischemic strokes. However, degree of stenosis is not always correlated with frequency of ischemic strokes. Recently, it was reported that carotid intraplaque hemorrhage (IPH) was associated with accelerated plaque growth, luminal narrowing and development of symptomatic events. Maximum intensity projection (MIP) images are easily reformatted within from 5 minute, routine time-of-flight (TOF) sequences. The aim of this study was to evaluate the relationships between high intensity signal (HIS) in the carotid plaques on MIP images detected by routine three-dimensional TOF magnetic resonance angiography (3D-TOF MRA) and ischemic strokes. Materials and Methods: One hundred fifty two patients with low-grade carotid artery stenosis (North American Symptomatic Carotid Endarterectomy Trial criteria: 30% - 49%) were included. IPH was defined as the presence of HIS in the carotid plaques on MIP images of 3D-TOF MRA using the previously reported criteria. We analyzed the relationship between the presence of HIS in the plaques and prior ischemic strokes defined as ischemic lesions on diffusion weighed images of the brain. Results: HIS in the carotid plaque was present in 56 (37%) of 152 carotid arteries. Prior ipsilateral ischemic strokes were observed more frequently in HIS-positive group (12 of 56, 21.4%) than HIS-negative group (1 of 34: 2.9%) [p&lt;0.001]. In multivariate logistic regression analysis, HIS (Odds ratio: 77.7, 95%CI: 6.4 - 944.0, p&lt;0.001) and diabetes mellitus type 2 (odds ratio: 10.45, 95%CI: 1.6 - 67.9, p=0.014) were independent determinants of prior ischemic strokes after adjustment for age. Conclusions: HIS in the carotid plaques on MIP images of 3D-TOF MRA was an independent determinant of prior ischemic stroke in patients with low-grade carotid artery stenosis, and this finding may provide a reliable risk stratification of future stroke in patients with low-grade carotid artery stenosis.

Contrast-enhanced CT- and MRI-based perfusion assessment for pulmonary diseases: basics and clinical applications.

Assessment of regional pulmonary perfusion as well as nodule and tumor perfusions in various pulmonary diseases are currently performed by means of nuclear medicine studies requiring radioactive macroaggregates, dual-energy computed tomography (CT), and dynamic first-pass contrast-enhanced perfusion CT techniques and unenhanced and dynamic first-pass contrast enhanced perfusion magnetic resonance imaging (MRI), as well as time-resolved three-dimensional or four-dimensional contrast-enhanced magnetic resonance angiography (MRA). Perfusion scintigraphy, single-photon emission tomography (SPECT) and SPECT fused with CT have been established as clinically available scintigraphic methods; however, they are limited by perfusion information with poor spatial resolution and other shortcomings. Although positron emission tomography with 15O water can measure absolute pulmonary perfusion, it requires a cyclotron for generation of a tracer with an extremely short half-life (2 min), and can only be performed for academic purposes. Therefore, clinicians are concentrating their efforts on the application of CT-based and MRI-based quantitative and qualitative perfusion assessment to various pulmonary diseases. This review article covers 1) the basics of dual-energy CT and dynamic first-pass contrast-enhanced perfusion CT techniques, 2) the basics of time-resolved contrast-enhanced MRA and dynamic first-pass contrast-enhanced perfusion MRI, and 3) clinical applications of contrast-enhanced CT- and MRI-based perfusion assessment for patients with pulmonary nodule, lung cancer, and pulmonary vascular diseases. We believe that these new techniques can be useful in routine clinical practice for not only thoracic oncology patients, but also patients with different pulmonary vascular diseases.

Three-dimensional contrast-enhanced magnetic resonance angiography for anterolateral thigh flap outlining: A retrospective case series of 68 patients.

Flap transfer is increasingly used for repairing limb defects secondary to trauma or tumor, and appropriate preoperative planning plays a critical role. The present study aimed to examine the use of three-dimensional (3D) contrast-enhanced magnetic resonance angiography (CE-MRA) in evaluating the blood supply distribution and perforating branch pattern of anterolateral thigh (ALT) flaps. Bilateral donor lower limbs were scanned in 68 patients (136 limbs) using a Siemens Avanto 1.5 T magnetic resonance imaging scanner with a 3D fast low-angle shot sequence, following the thin-slab maximum intensity projection (TS-MIP) technique. The lateral femoral circumflex artery (LFCA) was visualized in all patients: 101 limbs (101/136, 74.3%) were type I; 20 limbs (20/136, 14.7%) were type II; 3 limbs (3/136, 2.2%) were type III; and 12 limbs (12/136, 8.8%) were type IV. Tertiary branches were identified in 94 limbs (94/136, 69.1%). Donor flaps were outlined according to MRA TS-MIP findings in 4 patients. All flaps survived uneventfully following the transfer. In donor flap outlining, 3D CE-MRA with the TS-MIP technique allowed an accurate, direct visualization of the branching pattern and distribution profile of the LFCA supplying the ALT flap.

High-resolution dynamic CE-MRA of the thorax enabled by iterative TWIST reconstruction.

To evaluate the clinical benefit of using a new iterative reconstruction technique fully integrated on a standard clinical scanner and reconstruction system using a TWIST acquisition for high-resolution dynamic three-dimensional contrast-enhanced MR angiography (CE-MRA). Low-dose, high-resolution TWIST datasets of 11 patients were reconstructed using both standard GRAPPA-based reconstruction for reference and iterative reconstruction, which reduces the temporal footprint of reconstructed images. Image quality of both techniques was assessed by two experienced readers, as well as quantitatively evaluated using a time-signal curve analysis. Image quality scores consistently and significantly improved by using iterative reconstruction compared with the standard approach. Most notably, the delineation of small to mid-size vasculature improved from a mean Likert score between "nondiagnostic" and "poor" for standard to between "good" and "excellent" for iterative reconstruction. The full width at half maximum of the contrast agent bolus computed from the time-signal curve was also reduced by iterative reconstruction, allowing for more precise bolus timing. Iterative reconstruction can substantially improve high-resolution dynamic CE-MRA image quality, most notably in small to mid-size vasculature. Dynamic CE-MRA with iterative reconstruction could become an alternative to conventional static 3D CE-MRA, thus simplifying the clinical workflow. Magn Reson Med 77:833-840, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture.

Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described.

Feasibility of Three-Dimensional MR Angiography Image Fusion Guidance for Endovascular Abdominal Aortic Aneurysm Repair

Magnetic resonance (MR) angiography image fusion (IF) with live fluoroscopy guidance was used while performing endovascular repair of abdominal aortic aneurysm (EVAR) in five patients with a history of chronic renal disease or severe contrast allergy. Intraprocedural technical success was 100%. Median procedure time was 120 minutes (range, 60–180 min), fluoroscopy time was 40 minutes (range, 17–65 min), dose-area product was 245,867 mGy × cm2 (range, 68,435–690,053 mGy × cm2), and iodinated contrast volume injected was 15 mL (range, 0–40 mL). Technical success was achieved in four of five patients (80%); one case was complicated by a type 1 endoleak on follow-up MR angiography, which was successfully treated. EVAR with MR angiography IF guidance was technically feasible and safe in five patients and reduced or eliminated the use of iodinated contrast media.

Anomaly of the inferior vena cava and lactose malabsorption

SummaryPatients with anomalies of the inferior vena cava (IVC) are rare, are usually asymptomatic and this developmental anomaly is detected during radiologic evaluation of deep vein thrombosis or incidentally during abdominal radiologic evaluation. We report on time resolved three-dimensional magnetic resonance angiography (4D MRA) in a patient with congenital anomaly of the IVC and nonspecific abdominal complaints. 4D MRA is shown for evaluation and detailed diagnosis in vascular venous anatomy. However, due to continuing bloating and irregular bowel movements we investigated carbohydrate malabsorption and a lactose malabsorption was diagnosed. The nonspecific abdominal complaints in this patient with IVC anomaly were due to lactose malabsorption and were treated successfully with a lactose-free diet.@Supplementary material online: www.phlebologieonline.de: http://dx.doi.org/10.12687/phleb2285-1-2016

Conventional T2-Weighted Imaging to Detect High-Grade Stenosis and Occlusion of Internal Carotid Artery, Vertebral Artery, and Basilar Artery

To evaluate the reliability of conventional T2-weighted imaging (WI) for detecting high-grade stenosis and occlusion of cerebral arteries by disappearance of artery flow void signals. Our hospital's neuroimaging data on patients with ischemic stroke or transient ischemic attack were collected, including only those from patients who underwent both conventional brain T2WI and three-dimensional time-of flight magnetic resonance angiography (3D-TOF MRA). Flow void signals of conventional axial T2WI were analyzed by 2 young neurologists and compared with 3D-TOF MRA as the gold standard to determine the specificity for detection of high-grade stenosis and occlusion of cerebral arteries. Interobserver agreement was evaluated by calculating kappa (κ) coefficients. Of the 1765 patients included, disappearance of flow void signals was detected in 445 major cerebral arteries in 320 patients on conventional axial T2WI. The specificity of disappearance of flow void signal for the diagnosis of high-grade stenosis and occlusion was 94% for internal carotid arteries, 96.2% for vertebral arteries, and 92% for basilar arteries. K coefficients were greater than .94 for all arteries. Disappearance of flow void signal on conventional axial T2WI is a reliable indicator of high-grade stenosis or occlusion of major cerebral arteries. Conventional axial T2WI is a useful tool in the diagnosis of cerebral artery steno-occlusive disease.

Diagnostic accuracy of three-dimensional contrast-enhanced automatic moving-table MR angiography in patients with peripheral arterial occlusive disease in comparison with digital subtraction angiography

ObjectiveThe aim of this study was to compare the diagnostic accuracy of contrast-enhanced (CE) three-dimensional (3D) moving-table magnetic resonance (MR) angiography with that of selective digital subtraction angiography (DSA) for routine clinical investigation in patients with peripheral arterial occlusive disease. MethodsBetween April 2012 and May 2013, the lower extremities of 30 patients with suspected peripheral vascular disease performed both conventional digital subtraction angiography and three-dimensional contrast-enhanced MR angiography MRA with the automatic table movement technique (MoBI-trak). DSA and MR angiographic images were interpreted prospectively, one vascular radiologist interpreted the digital subtraction angiographic images and the second vascular radiologist interpreted the MR angiographic images; both interpreters were unaware of the clinical history and the results of the other examination. ResultsThe MRA and DSA studies in the 30 study patients produced 870 arterial segments for interpretation. The sensitivity of MRA for the detection of mild stenotic, hemodynamically severe stenotic and occlusions were 86.1%, 90.5% and 93.9%, respectively. Corresponding specificity was 90.1%, 96.1% and 97.5%, respectively. ConclusionOur prospective comparison shows that three-dimensional contrast-enhanced automatic moving-table MRA is a noninvasive imaging modality that has a diagnostic accuracy comparable to DSA for the assessment of peripheral arterial occlusive disease.

Retrobulbar magnetic resonance angiography using binomial off-resonant rectangular (BORR) pulse.

Applying a newly developed binomial off-resonant rectangular (BORR) pulse method for high resolution three-dimensional MR angiography (MRA) on retrobulbar ocular vessels, which has not been possible with routine MRA due to background fatty tissues. BORR pulse was implemented in a gradient echo sequence by replacing the original excitation pulse, and were optimized for robust orbital fat suppression. Several other MRA methods, with or without fat suppression, were also compared, including time-of-flight, contrast enhanced MRA, and hybrid of opposite-contrast MRA. Nine healthy subjects participated with written informed consents. To reduce eye motion, the subjects were instructed to casually stare at a projected cross during each MRA scan. Major vessels were evaluated by three independent radiologists using a 4-point scale. The BORR method yielded the best MRA results for retrobulbar vessels without contrast enhancement, significantly superior than other MRA methods. BORR results had significantly higher visibility scores than all other methods for small vessels. We have successfully revealed orbital vessels in retrobulbar space for the first time using MRA, by using the BORR pulse method. With a clear depiction of the vasculature without the need for contrast enhancement, our method has the potential to provide important diagnostic information for ocular vascular diseases.

Reducing view-sharing using compressed sensing in time-resolved contrast-enhanced magnetic resonance angiography.

To study temporal and spatial blurring artifacts from k-space view-sharing in time-resolved MR angiography (MRA) and to propose a technique for reducing these artifacts. We acquired k-space data sets using a three-dimensional time-resolved MRA view-sharing sequence and retrospectively reformatted them into two reconstruction frameworks: full view-sharing via time-resolved imaging with stochastic trajectories (TWIST) and minimal k-space view-sharing and compressed sensing (CS-TWIST). The two imaging series differed in temporal footprint but not in temporal frame rate. The artifacts from view-sharing were compared qualitatively and quantitatively in nine patients in addition to a phantom experiment. CS-TWIST was able to reduce the imaging temporal footprint by two- to three-fold compared with TWIST, and the overall subjective image quality of CS-TWIST was higher than that for TWIST (P < 0.05). View sharing caused a delay in the visualization of small blood vessels, and the mean transit time of the carotid artery calculated based on TWIST reconstruction was 0.6 s longer than that for CS-TWIST (P < 0.01). In thoracic MRA, the shorter temporal footprint decreased the sensitivity to physiological motion blurring, and vessel sharpness was improved by 8.8% ± 6.0% using CS-TWIST (P < 0.05). In time-resolved MRA, the longer temporal footprint due to view-sharing causes spatial and temporal artifacts. CS-TWIST is a promising method for reducing these artifacts.

Haemoptysis due to pulmonary venous stenosis.

Haemoptysis is a potentially life-threatening condition with the need for prompt diagnosis. In about 10-20% of all cases the bleeding source remains unexplained with the standard diagnostic approach. The aim of this article is to show the necessity of widening the diagnostic approach to haemoptysis with consideration of pulmonary venous stenosis as a possible cause of even severe haemoptysis and haemoptoe. A review of the literature was performed using the Medline/PubMed database with the terms: "pulmonary venous stenosis", "pulmonary venous infarction" and "haemoptysis". Further references from the case reports were considered. 58 case reports and case collections about patients with haemoptysis due to pulmonary venous stenosis were detected. This review gives an overview about the case reports and discusses the underlying pathophysiology and the pros and cons of different imaging techniques for the detection of pulmonary venous stenosis. Several conditions predispose to the obstruction of the mediastinal pulmonary veins. Clinical findings are unspecific and may be misleading. Pulmonary venous stenosis can be detected using several imaging techniques, yet three-dimensional magnetic resonance-angiography and three-dimensional contrast-enhanced computed tomography are the most appropriate. Pulmonary venous stenosis should be considered in patients with haemoptysis.

The detection of coronary stiffness in cardiac allografts using MR imaging

ObjectiveTo test the hypothesis that biomechanical changes are quantitatively related to morphological features of coronary arteries in heart transplant (HTx) recipients. Materials and methodsWith IRB approval, three-dimensional (3D) magnetic resonance (MR) angiography and two-dimensional (2D) black-blood stead-state free precession (SSFP) MR imaging were performed to image coronary arteries of 36 HTx patients. Contours of coronary wall were manually drawn. For each coronary segment, coronary wall thickness, wall area, lumen area (in systole and diastole) were acquired. Coronary distensibility index (CDI) and the percent of the coronary wall occupying the vessel area (PWOV) were calculated. ResultsThere are totally 98 coronary segments eligible for quantitative analysis from 27 HTx patients. The CDI is 4.90±2.44mmHg−1. The mean wall thickness is 1.49±0.24mm and the PWOV is 74.6%±7.5%. CDI has moderate correlations with wall thickness (r=−0.531, P<0.001) and with PWOV (R=−0.435, P<0.001). ConclusionsDetected with coronary MR imaging, CDI is quantitatively correlated with the morphological features of the coronary artery in HTx patients. Coronary stiffness has the potential to become an alternative imaging biomarker for the quantitative assessment of the status of cardiac allografts.

Sliding time of flight: sliding time of flight MR angiography using a dynamic image reconstruction method.

To obtain three-dimensional (3D) MR angiography having high contrast between vessel and stationary background tissue, a novel technique called sliding time of flight (TOF) is proposed. The proposed method relies on the property that flow-related enhancement (FRE) is maximized at the blood-entering slice in an imaging slab. For the proposed sliding TOF, a sliding stack-of-stars sampling and a dynamic MR image reconstruction algorithm were developed. To verify the performance of the proposed method, in vivo study was performed and the results were compared with multiple overlapping thin 3D slab acquisition (MOTSA) and sliding interleaved ky (SLINKY). In MOTSA and SLINKY, the variation of FRE resulted in severe venetian blind (MOTSA) or ghost (SLINKY) artifacts, while the vessel-contrast increased as the flip angle of radiofrequency (RF) pulses increased. On the other hand, the proposed method could provide high-contrast angiograms with reduced FRE-related artifacts. The sliding TOF can provide 3D angiography without image artifacts even if high flip angle RF pulses with thick slab excitation are used. Although remains of subsampling artifacts can be present in the reconstructed images, they can be reduced by MIP operation and resolved further by regularization techniques.