Society for Cardiovascular Magnetic Resonance 2022 Cases of SCMR case series

"Cases of SCMR" is a case series on the SCMR website (https://www.scmr.org) for the purpose of education. The cases reflect the clinical presentation, and the use of cardiovascular magnetic resonance (CMR) in the diagnosis and management of cardiovascular disease. The 2022 digital collection of cases are presented in this manuscript.

"Lung packing" in breath hold-diving: An impressive case of pulmo-cardiac interaction

There is a complex interaction between the heart and the lungs. We report on a healthy female who performs breath hold diving at a high, international level. In order to optimize pressure equalization during diving and to increase oxygen available, apneists employed a special breathing maneuver, so called “lung packing”. Based on cardiac MRI we could demonstrate impressive effects of this maneuver on left ventricular geometry and hemodynamics. Beyond the fact, that our findings support the concept of pulmonary –cardiac interrelationship, it should be emphasized, that the reported, extreme breathing maneuver could have detrimental consequences due to reduction of stroke volume and cardiac output.

Time-resolved magnetic resonance imaging of contrast kinetics to identify severe tricuspid valve regurgitation

INTRODUCTION

The gold standard for identifying and grading tricuspid valve regurgitation is transthoracic echocardiography. However, the acoustic window using transthoracic echocardiography is not always sufficient to quantify the amount of regurgitation. Time-resolved imaging of contrast kinetics (TRICKS) is a 4-dimensional magnetic resonance angiography option with high spatial and temporal resolution. The aim of the present study is to find out whether identification of patients with severe tricuspid valve regurgitation by using TRICKS angiography is feasible.

METHODS

TRICKS angiography was performed in a 3T-CMR-scanner after antecubital injection of gadolinium dimeglumine during breath hold. Retrograde appearance of contrast agent in the hepatic veins was classified as severe tricuspid regurgitation (TR). Additional semi quantification of retrograde perfusion was performed by temporal signal intensity curve (SIC) analysis in the hepatic veins close to their drainage into the inferior vena cava. Transthoracic echocardiography (TTE) using the actual European guidelines on the management of valvular heart disease served as gold standard forTR grading.

RESULTS

185 patients (57 +/- 17 years) with TR ranging from no to severe TR were analysed prospectively. 14 (7.6%) patients had severe TR, 27 (14.6%) showed moderate, 137 (74.1%) mild and 7 (3.8%) no TR. TRICKSangiography identified 13 patients with retrograde contrast appearance in the hepatic veins, of whom all had severe TR in TTE. No patient with echocardiographic mild or moderate TR was graded as severe TR using TRICKSangiography. One patient with echocardiographic severe TR showed neither in the visual analysis nor in SIC analysis retrograde appearance of contrast agent in the hepatic veins. Overall, the sensitivity for detecting severe TR using TRICKSangiography was 93% with a specificity of 100%. The positive predictive value was 100%, the negative predictive value 99%. For severe TR there was no intra- and interobserver variability.

CONCLUSION

MRTRICKSangiography is a very reliable tool to identify patients with severeTR by the imaging of retrograde appearance of contrast agent in the hepatic veins. Sensitivity and specificity of this approach is very high with no intra- and interobserver variability.

Comparison of tenocytes and mesenchymal stem cells seeded on biodegradable scaffolds in a full-size tendon defect model

In order to investigate cell-based tendon regeneration, a tendon rupture was simulated by utilizing a critical full-size model in female rat achilles tendons. For bridging the defect, polyglycol acid (PGA) and collagen type I scaffolds were used and fixed with a frame suture to ensure postoperatively a functional continuity. Scaffolds were seeded with mesenchymal stem cells (MSC) or tenocytes derived from male animals, while control groups were left without cells. After a healing period of 16 weeks, biomechanical, PCR, histologic, and electron microscopic analyses of the regenerates were performed. Genomic PCR for male-specific gene was used to detect transplanted cells in the regenerates. After 16 weeks, central ossification and tendon-like tissue in the superficial tendon layers were observed in all study groups. Biomechanical test showed that samples loaded with tenocytes had significantly better failure strength/cross-section ratio (P < 0.01) compared to MSC and the control groups whereas maximum failure strength was similar in all groups. Thus, we concluded that the application of tenocytes improves the outcome in this model concerning the grade of ossification and the mechanical properties in comparison to the use of MSC or just scaffold materials.

Tricuspid annular plane systolic excursion assessed using MRI for semi-quantification of right ventricular ejection fraction

OBJECTIVE

Accurate determination of right ventricular volume and ejection fraction (RVEF) is established using MRI. Automatic contour detection of the right ventricular endocardial border is not established in clinical practice, resulting in considerable manual efforts to quantify RVEF. Using transthoracic echocardiography (TTE), the tricuspid annular plane systolic excursion (TAPSE) has proved its worth for quantification of RVEF and risk prediction. Therefore, the aim of this study was to clarify whether TAPSE assessed with MRI as a fast and easily obtainable parameter correlated with volumetric quantification of RVEF.

METHODS

Right ventricular volumes and RVEF were measured with the standardised slice-summation method at MRI. MRI-TAPSE was defined as maximum apical excursion of lateral tricuspid annular plane and measured in a four-chamber view using steady-state free precession sequences. Additionally, MRI-TAPSE was compared with TAPSE assessed using TTE.

RESULTS

76 consecutive patients (aged 58±17 years) were examined. At MRI, right end-diastolic volumes were 97±36 ml, right end-systolic volumes were 57±27 ml and the mean RVEF was 42±14%. MRI-TAPSE was determined with 19±6 mm and correlated well at linear regression analysis with volumetric RVEF (r=0.72, p<0.001). Furthermore, MRI-TAPSE discriminated sufficiently between patients with impaired and normal RVEF. Multiplying MRI-TAPSE by 2.5 led to values close to the RVEF by volumetry. Additionally, MRI-TAPSE correlated well with TAPSE determined using TTE. The inter- and intra-observer variabilities of MRI-TAPSE determination were low (3.1% and 1.8%).

CONCLUSION

TAPSE assessed with MRI is a fast and easily obtainable parameter which correlates well with volumetric quantification of RVEF.

Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

OBJECTIVE

Cardiac CT allows the detection and quantification of coronary artery calcification (CAC). Electron-beam CT (EBCT) has been widely replaced by high-end CT generations in the assessment of CAC. The aim of this study was to compare the CAC scores derived from an EBCT with those from a dual-source CT (DSCT).

METHODS

We retrospectively selected 92 patients (61 males; mean age, 60.7 ± 12 years) from our database, who underwent both EBCT and DSCT. CAC was assessed using the Agatston score by two independent readers (replicates: 1, 2; 3=mean of reading 1 and 2).

RESULTS

EBCT scores were on average slightly higher than DSCT scores (281 ± 569 vs 241 ± 502; p<0.05). In regression analysis R(2)-values vary from 0.956 (1) to 0.966 (3). We calculated a correction factor as EBCT=(DSCT+1)(1.026)-1. When stratifying into CAC categories (0, 1-99, 100-399, 400-999 and ≥1000), 79 (86%) were correctly classified. From those with positive CAC scores, 7 out of 61 cases (11%, κ=0.81) were classified in different categories. Using the corrected DSCT CAC score, linear regression analysis for the comparison to the EBCT results were r=0.971 (p<0.001), with a mean difference of 6.4 ± 147.8. Five subjects (5.4%) were still classified in different categories (κ=0.84).

CONCLUSION

CAC obtained from DSCT is highly correlated with the EBCT measures. Using the calculated correction factor, agreement only marginally improved the clinical interpretation of results. Overall, for clinical purposes, face value use of DSCT-derived values appears as useful as EBCT for CAC scoring.

Free breathing 2D multi-slice real-time gradient-echo cardiovascular magnetic resonance imaging: impact on left ventricular function measurements compared with standard multi-breath hold 2D steady-state free precession imaging

OBJECTIVE

Multi-breath hold cine-imaging (standard-2D-SSFP) is the standard technique for ventricular function assessment. However, image acquisition is time-consuming and breath holding is required. Ultrafast 2D real-time imaging (2D real time-SSFP) does not require breath holding, but spatial resolution is sacrificed. The accuracy of 2D real time-SSFP free-breathing ventricular function assessment by using an automated contour detection programme has not been systematically studied.

METHODS AND RESULTS

Twenty-eight subjects (14 with impaired LV function) were investigated by 1.5 Tesla magnetic resonance imaging. Left ventricular short-axis images were acquired with multi-breath hold standard 2D-SSFP and free-breathing 2D real time-SSFP. LV-volumes (EDV, ESV), EF, and mass were determined using a semi-automated contour detection programme. EDV, ESV, EF, and mass were not significantly different between real time- and standard 2D-SSFP in subjects (absolute differences: EDV 3.2 +/- 0.7 mL, ESV 3.0 +/- 0.3 mL, EF 1.9 +/- 0.4%, mass 0.8 +/- 0.4 g; P > or = 0.78) and patients (absolute differences: EDV= 3.0 +/- 0.8 mL, ESV 3.3 +/- 1.0 mL, EF 0.9 +/- 0.5%, mass 0.9 +/- 0.5 g; P > or = 0.73). Automated contour detection required extensive manual correction for real-time imaging (< or = 86%).

CONCLUSIONS

Differences in LV function measurements between real-time and standard 2D-SSFP are small, and not significant. Real-time SSFP may be used for rapid LV function assessment when examination time is limited.

Influence of adenosine on ventricular function measurements as part of a comprehensive stress perfusion magnetic resonance imaging study

BACKGROUND

Stress-rest perfusion magnetic resonance imaging (MRI) has become one of the major indications for cardiovascular MRI. Standard multibreath hold short-axis image acquisition is the gold standard for LV function assessment and part of a comprehensive stress-rest perfusion MRI study, but takes up to 10 min. The total scan time could significantly be shortened when cine imaging would be performed between stress and rest perfusion.

PURPOSE

To systematically study whether adenosine, albeit its short half-life time, influences LV function measurements in this setting.

MATERIAL AND METHODS

Thirty-nine patients with suspected and/or known coronary artery disease underwent 3-Tesla adenosine (140 µg/min/kg) stress-rest perfusion MRI. A stack of short-axis slices covering the entire ventricles was acquired before and ≥3 min after adenosine infusion using standard multibreath-hold 2D steady-state free precession imaging. LV volumes (EDV, ESV), EF, and mass were calculated by the slice summation method, and wall motion was assessed using a 4-point scoring scale. Reproducibility was assessed by Bland-Altman statistics.

RESULTS

EDV, ESV, EF, and mass were not significantly different between the two imaging time points (before versus after adenosine administration) in all patients (P ≥ 0.346) and patients with impaired LV function (P ≥ 0.718). Wall motion scores did not differ either (P ≥ 0.124). Inter-observer variability before (P ≥ 0.468) and after (P ≥ 0.451) adenosine infusion was low.

CONCLUSION

Short-axis cine imaging for LV function assessment can accurately be performed between stress and rest imaging. These data demonstrate that potential effects of adenosine on LV function are of short duration, and propose a new time-saving imaging protocol without compromising accuracy.

Left ventricular function assessment using a fast 3D gradient echo pulse sequence: comparison to standard multi-breath hold 2D steady state free precession imaging and accounting for papillary muscles and trabeculations

OBJECTIVE

Papillary muscles and trabeculae for ventricular function analysis are known to significantly contribute to accurate volume and mass measurements. Fast imaging techniques such as three-dimensional steady-state free precession (3D SSFP) are increasingly being used to speed up imaging time, but sacrifice spatial resolution. It is unknown whether 3D SSFP, despite its reduced spatial resolution, allows for exact delineation of papillary muscles and trabeculations. We therefore compared 3D SSFP ventricular function measurements to those measured from standard multi-breath hold two-dimensional steady-state free precession cine images (standard 2D SSFP).

METHODS AND RESULTS

14 healthy subjects and 14 patients with impaired left ventricularfunction underwent 1.5 Tesla cine imaging. A stack of short axis images covering the left ventricle was acquired with 2D SSFP and 3D SSFP. Left ventricular volumes, ejection fraction, and mass were determined. Analysis was performed by substracting papillary muscles and trabeculae from left ventricular volumes. In addition, reproducibility was assessed. EDV, ESV, EF, and mass were not significantly different between 2D SSFP and 3D SSFP (mean difference healthy subjects: -0.06 +/- 3.2 ml, 0.54 +/- 2.2 ml, -0.45 +/- 1.8%, and 1.13 +/- 0.8 g, respectively; patients: 1.36 +/- 2.8 ml, -0.15 3.5 ml, 0.86 +/- 2.5%, and 0.91 +/- 0.9 g, respectively; P > or = 0.095). Intra- and interobserver variability was not different for 2D SSFP (P > or = 0.64 and P > or = 0.397) and 3D SSFP (P > or = 0.53 and P > or = 0.47).

CONCLUSIONS

Differences in volumes, EF, and mass measurements between 3D SSFP and standard 2D SSFP are very small, and not statistically significant. 3D SSFP may be used for accurate ventricular function assessment when papillary muscles and trabeculations are to be taken into account.

Influence of the trigger technique on ventricular function measurements using 3-Tesla magnetic resonance imaging: comparison of ECG versus pulse wave triggering

BACKGROUND

Three Tesla cardiovascular magnetic resonance imaging (3T-CMR) is increasingly used in clinical practice. Despite many advantages one drawback is that ECG signal disturbances and artifacts increase with higher magnetic field strength resulting in trigger problems and false gating. This particularly affects cardiac imaging because most pulse sequences require ECG triggering. Pulse wave (PW) triggering is robust and might have advantages over ECG triggering.

PURPOSE

To evaluate differences in left ventricular (LV) function as an integral part of most CMR studies between ECG- and PW-triggered short-axis imaging using 3T-CMR.

MATERIAL AND METHODS

Forty-three patients underwent multiple short-axis cine imaging for LV-function assessment with ECG and PW triggering using standard multibreath hold steady-state free precession. LV-volumes (EDV, ESV), ejection fraction (EF), and mass were determined by slice summation. LV-wall motion was assessed by using a 4-point scoring scale. Bland Altman statistics for inter-observer variability were performed.

RESULTS

ECG triggering failed in 15 patients (34.8%). Thus, analysis was performed in 28 patients (13 with impaired LV function). Difference in volumes (EDV 0.13 ± 1.8 mL, ESV 0.59 ± 1.1 mL), EF (-0.32 ± 0.6%) and mass (0.01 ± 1.1 g) between ECG and PW triggering were very small and significant only for ESV and EF (p ≤ 0.011). In patients with impaired LV function (n = 19) differences were not significant (p ≥ 0.128). Wall motion scores did not differ between ECG and PW triggering (p ≥ 0.295). Inter-observer variability for function measurements was low.

CONCLUSION

Short-axis cine imaging for LV-function assessment can accurately be performed using PW triggering on 3T magnets, and may be used in clinical practice when ECG triggering is disturbed.

Scaffold-free 3D cellulose acetate membrane-based cultures form large cartilaginous constructs

Scaffold-free three-dimensional (3D) cultures provide clinical potential in cartilage regeneration. The purpose of this study was to characterize a scaffold-free 3D membrane-based culture system, in which human articular chondrocytes were cultivated on a cellulose acetate membrane filter, and compare it to pellet and monolayer cultures. Chondrocytes were expanded in monolayer culture for up to 5 passages, transferred to membrane-based or pellet cultures and harvested after 7 or 21 days. The chondrogenic potential was assessed by histology (toluidine blue, safranin-O), immunohistochemistry for collagen type II and quantitative analysis of collagen type II α(1) (COL2A1). Membrane-based cultures (P1) formed flexible disc-like constructs (diameter 4000 µm, thickness 150 µm) with a large smooth surface after 7 days. Positive safranin-O and collagen type II staining was found in membrane-based and pellet cultures at P1-3. Expression of COL2A1 after 7 days was increased in both culture systems compared to monolayer culture up to P3, whereas cells from monolayer > P3 did not redifferentiate. The best results for COL2A1 expression were obtained from membrane-based cultures at P1. After 21 days the membrane-based cultures did not express COL2A1. We concluded that membrane-based and pellet cultures showed the ability to promote redifferentiation of chondrocytes expanded in monolayer culture. The number of cell passages had an impact on the chondrogenic potential of cells. Membrane-based cultures provided the highest COL2A1 expression and a large, smooth and cartilage-like surface. As these are appropriate features for clinical applications, we assume that membrane-based cultures might be of use in cartilage regeneration if they displayed similar results in vivo.

Thyroid hormone mediates otolith growth and development during flatfish metamorphosis

Flatfish begin life as bilaterally symmetrical larvae that swim up-right, then abruptly metamorphose into asymmetrically shaped juveniles with lateralized swimming postures. Flatfish metamorphosis is mediated entirely by thyroid hormone (TH). Changes in flatfish swim posture are thought to be regulated via vestibular remodeling, although the influence of TH on teleost inner ear development remains unclear. This study addresses the role of TH on the development of the three otolith end-organs (sacculus, utricle, and lagena) during southern flounder (Paralichthys lethostigma) metamorphosis. Compared with pre-metamorphosis, growth rates of the sacculus and utricle otoliths increase dramatically during metamorphosis in a manner that is uncoupled from general somatic growth. Treatment of P. lethostigma larvae with methimazol (a pharmacological inhibitor of endogenous TH production) inhibits growth of the sacculus and utricle, whereas treatment with TH dramatically accelerates their growth. In contrast with the sacculus and utricle otoliths that begin to form and mineralize during embryogenesis, a non-mineralized lagena otolith is first visible 10-12 days after hatching. The lagena grows during pre- and pro-metamorphosis, then abruptly mineralizes during metamorphic climax. Mineralization of the lagena, but not growth, can be induced with TH treatment, whereas treatment with methimazol completely inhibits lagena mineralization without inhibiting its growth. These findings suggest that during southern flounder metamorphosis TH exerts differential effects on growth and development among the three types of otolith.

Influence of design and bearing material on polyethylene wear particle generation in total knee replacement

Periprosthetic osteolysis is one of the main reasons for revision of arthroplasty. The osteolytic reaction is influenced by the dose, size and shape of the wear particles. For arthroplasty, a low number and biologically less active particles are required. This is the first study which analyzes the impact of different knee designs, combined with crosslinked polyethylenes (sequentially irradiated and annealed as well as remelted techniques), on the amount, size and shape of particles. Overall, six material combinations, four of them with crosslinked polyethylene (XPE) and two of them with ultra-high molecular weight polyethylene (UHMWPE) inserts, including fixed and mobile bearings, were tested in a knee joint simulator. After isolation nearly 100,000 particles were analyzed in size, shape and number by scanning electron microscopy and image analysis. For all the designs, the wear was predominantly smooth and granular with few fibrillar particles. The Scorpio design with the X3 insert, the Natural Knee II design with the Durasul insert and the LCS design, also combined with a crosslinked polyethylene insert, generated statistically significant (P<0.05) lower particle numbers. The particle size was independent of the radiation dose. The wear generated by the LCS knee design (XPE and UHMWPE) had a higher percentage fraction of particles >1microm in size (equivalent circle diameter). The NexGen design, tested with the Prolong insert, showed a high number of particles in the biologically active size range compared with the other crosslinked designs, which could be a predictor for higher biological reactivity.

Online PC-based integration of digital intracoronary ultrasound images into angiographic images during cardiac catheterization

In recent years, intravascular ultrasound (IVUS) has evolved as an important adjunct to angiography, providing insights that are significantly altering conventional paradigms in diagnosis and therapy. However, major drawbacks in the use of IVUS relied on the fact that a heavy console had to be moved from lab to lab, and extensive time for set up and image analysis. This additional time and the decrease in patients' through-put has not been applicable in clinical practice for many labs. Our manuscript concerns a novel PC-based platform for IVUS that enables the online intergration of digital intracoronary ultrasound images into angiographic images. This new technique offers remote operation, multiple control devices and custom viewing options. The PC-based platform enables IVUS images to be viewed simultaneously from multiple vantage points in the lab, and allows for multiple user interfaces.

[Cardiac magnetic resonance imaging in the diagnosis of acute coronary syndrome. Basics and clinical value]

In contrast to chronic myocardial infarction, data concerning the value of cardiac magnetic resonance imaging in patients with acute onset of chest pain are still rare. Even in the presence of characteristic clinical parameters, cardiac magnetic resonance imaging might provide independent evidence especially in the absence of typical ECG alterations and prior to biomarker elevation. Besides the ability to demonstrate wall motion abnormalities cardiac magnetic resonance imaging gains additional potential as to the detection of myocardial edema, microvascular obstruction (no-reflow) and myocardial necrosis. However, cardiac magnetic resonance imaging is expensive and time-consuming, and therefore may not be cost-effective. At present, a lack of sufficient diagnostic and prognostic data would make cardiac magnetic resonance imaging unsuitable for routine stratification of chest pain patients in an emergency department.

Randomized comparison of effects of suture-based and collagen-based vascular closure devices on post-procedural leg perfusion

BACKGROUND

Vascular closure devices (VCD) are well established to facilitate hemostasis after cardiac catheterization procedures. However, impairment of flow due to the reduction of femoral artery diameter remains a major concern. The present study aims to evaluate leg perfusion before and after application of collagen- and suture-based vascular closure devices.

METHODS

A total of 366 patients (age: 64.3 years+/-10.7, male: 71.3%) were randomized to receive femoral access site closure with either a collagen-based closure device (group A) (n=214) or a suture-mediated device (group B) (n=152), immediately following coronary catheterization procedures. In all patients, the ankle-brachial-index (ABI) was measured before and the day after closure device application.

RESULTS

In group A, mean ABI at baseline was 1.09+/-0.2, in group B 1.11+/-0.2. In both groups, there was a significant, albeit clinically not relevant, reduction in post-procedural ABI (group A: 1.04+/-0.2, p<0.01 vs baseline, group B: 1.06+/-0.2, p<0.01 vs baseline). DeltaABI was not different between both VCD groups (p=0.55). In patients with peripheral vascular disease (PVD), neither the Angioseal device (mean ABI at baseline 0.76+/-0.1) nor the Perclose-device (mean ABI at baseline 0.79+/-0.1) induced a remarkable impairment of leg perfusion (Angioseal: 0.77+/-0.1, p=0.9 vs baseline, Perclose: 0.78+/-0.1, p=1.0 vs baseline). Clinically, no aggravation of claudication was observed in the PVD patient group.

CONCLUSION

Both vascular closure devices are not associated with clinically relevant reduction in ABI. There was no difference between the two groups with respect to the level of flow impairment. Both devices may be safely used in patients with reduced ABI.

Reference Right Atrial Function Determined by Steady-State Free Precession Cardiovascular Magnetic Resonance

BACKGROUND

There is agreement that measurements of atrial volumes and ejection fraction (EF) are superior to atrial diameters for accurate determination of atrial size, follow up studies and prognosis. However, reference values for right atrial volumes and EF for cardiovascular magnetic resonance (CMR) have not been established but are crucial to identify patients with impaired right atrial function.

METHODS AND RESULTS

Atrial function was studied in 70 healthy subjects (52+/-16 years, 38 male) with both the standard short axis method (SA) and the area-length method (AL) using steady-state free precession gradient-echo cine imaging (SSFP). Intraobserver, interobserver (n=70) and interstudy (n=10) variability was assessed for both methods. Maximal volumes, minimal volumes and EF for SA and AL were 101.0+/-30.2 mL, 50.3+/-19 mL and 47.2+/-8.3%, and 103.2+/-32.6 mL, 50.8+/-20.2 mL and 51.4+/-9.2%, respectively. Maximal volumes, minimal volumes and EF were higher with AL than with SA (mean difference: 2.2+/-4.6 mL, 3.5+/-3.5 mL and 2.8+/-2.8%, respectively). Atrial function measurements were not related to gender (p>or=0.387) and age (rho<or=0.16) with either method. Intraobserver, interobserver and interstudy variability for volumes and EF was lower for SA compared to AL, with narrower limits of agreement. Analysis was faster with AL than with SA (62+/-18 s versus 7+/-2 minutes).

CONCLUSION

Normal ranges for right atrial function vary significantly between methods. AL is faster, but less reproducible than SA. Appropriate reference ranges should be used to differentiate normal from abnormal right atrial function.

Combining spin echoes with gradient echoes in the context of the global coherent free precession pulse sequence

To extend the signal longevity of magnetically excited spins in flowing fluids while in a state of global coherent free precession (GCFP), a refocusing radiofrequency (RF) pulse and bipolar gradient waveforms were combined with the GCFP sequence. The data demonstrate that RF refocusing in the presence of flowing blood is possible, but the improvement in signal amplitude depends on the static magnetic field homogeneity along the direction of motion and the displacement of the spins between the excitation and the RF refocusing pulse, as well as displacement during subsequent RF refocusing pulses. The least amount of phase dispersion and thus the longest lasting signal is obtained with the shortest echo spacing where only one line of data is recorded between two RF refocusing pulses. This approach was successfully used in a phantom and in vivo to image fast and slow blood flow. Depending on the experimental conditions, signal persistence is improved significantly compared to playing the same sequence without RF refocusing, but the improvement is limited by the product of blood flow velocity and the time between RF refocusing pulses.

Cardiovascular MRI: its current and future use in clinical practice

Cardiovascular magnetic resonance (CMR) imaging is a comprehensive clinical tool for assessing a large variety of cardiovascular diseases. Using the clinical service of the Duke Cardiovascular Magnetic Resonance Center as an example, we describe how to perform image contractile function, myocardial perfusion at stress and rest, myocardial viability, cardiovascular morphology, vascular anatomy and blood flow tests. The emergence of successful dedicated CMR services presents an opportunity to optimize patient throughput by streamlining the user interface of CMR scanners, standardizing the viewing format and reporting software, and customizing training programs to focus on the standardized CMR approaches. Accordingly, we discuss potential pathways to create these standards. Finally, we discuss several promising new CMR techniques we expect will complement existing clinical procedures.

Rapid Detection of Myocardial Infarction by Subsecond, Free-Breathing Delayed Contrast-Enhancement Cardiovascular Magnetic Resonance

Background— An ultrafast, delayed contrast-enhancement cardiovascular magnetic resonance technique that can acquire subsecond, “snapshot” images during free breathing (subsecond) is becoming widely available. This technique provides myocardial infarction (MI) imaging with complete left ventricular coverage in <30 seconds. However, the accuracy of this technique is unknown.

Methods and Results— We prospectively compared subsecond imaging with routine breath-hold delayed contrast-enhancement cardiovascular magnetic resonance (standard) in consecutive patients. Two cohorts with unambiguous standards of truth were prespecified: (1) patients with documented prior MI (n=135) and (2) patients without MI and with low likelihood of coronary disease (lowest Framingham risk category; n=103). Scans were scored masked to identity and clinical information. Sensitivity, specificity, and accuracy of subsecond imaging for MI diagnosis were 87%, 96%, and 91%, respectively. Compared with the standard technique (98%, 100%, 99%), the subsecond technique had modestly reduced sensitivity ( P =0.0001), but specificity was excellent. Missed infarcts were generally small or subendocardial (87%). Overall, regional transmural extent of infarction scores were highly concordant (2083/2294; 91%); however, 51 of 337 regions (15%) considered predominantly infarcted (>50% transmural extent of infarction) by the standard technique were considered viable (≤25% transmural extent of infarction) by the subsecond technique. Quantitative analysis demonstrated moderately reduced contrast-to-noise ratios for subsecond imaging between infarct and remote myocardium (12.0±7.2 versus 20.1±6.6; P <0.0001) and infarct and left ventricular cavity (−2.5±2.7 versus 3.6±3.7; P <0.0001).

Conclusions— MI can be rapidly detected by subsecond delayed contrast-enhancement cardiovascular magnetic resonance during free breathing with high accuracy. This technique could be considered the preferred approach in patients who are more acutely ill or unable to hold their breath. However, compared with standard imaging, sensitivity is mildly reduced, and the transmural extent of infarction may be underestimated.

Determination of normal gender-specific left atrial dimensions by cardiovascular magnetic resonance imaging

BACKGROUND

Because cardiovascular magnetic resonance imaging (CMR) is becoming increasingly available in clinical practice, there is a need to establish normal values for left atrial dimensions as determined by this method to allow accurate assessment of cardiac dimensions and to provide standardization for follow up studies. For clinical purpose measurements of the left atrial end diastolic diameter (LAEDD) are most appropriate to assess left atrial size. We aimed to establish normal values for LAEDD using CMR and a fast gradient-echo sequence with steady-state free precession (SSFP).

METHODS

A total of 111 healthy subjects (52 women and 59 men, mean age 51.5 +/- 14.5 years) were examined by CMR. Images were acquired using SSFP in the horizontal (HLA) and vertical (VLA) long axis planes and the left ventricular outflow tract plane (LVOT) to measure the LAEDD.

RESULTS

Age between men and women was not different (p = 0.7050). CMR yielded the following normal ranges for LAEDD: HLA 4.5 +/- 0.4 cm for men and 4.2 +/- 0.5 for women, VLA 4.5 +/- 0.5 cm for men and 4.2 +/- 0.4 for women, and LVOT 2.8 +/- 0.3 cm for men and 2.8 +/- 0.4 for women. LAEDD were significantly larger in HLA and VLA than in LVOT (p < or = 0.0001). There was no significant difference in the measurements between HLA and VLA (p = 0.4617). Gender-related differences for LAEDD were found in HLA (p = 0.0087) and VLA (p = 0.0015) but not in LVOT (p = 0.5281). LAEDD were not found to be age-related (p > or = 0.0994).

CONCLUSIONS

LAEDD differ significantly according to the image plane. We provide reference values for CMR using prospective triggering in the evaluation of left atrial diameters to identify patients with enlarged left atria and for follow-up studies.

Assessment of left atrial volumes in sinus rhythm and atrial fibrillation using the biplane area-length method and cardiovascular magnetic resonance imaging with TrueFISP

OBJECTIVES

To determine whether the biplane area-length method can be used for the evaluation of left atrial volumes and ejection fraction with cardiovascular magnetic resonance imaging (CMR) by TrueFISP in normal subjects and patients with atrial fibrillation.

BACKGROUND

Atrial fibrillation is the most common arrhythmia in elderly patients. Left atrial size and volumes play an important role in predicting short and long-term success after cardioversion.

METHODS

Fifteen healthy subjects (mean age 65.6+/-6.4 years) and 18 patients (mean age 67.2+/-8.8 years) with atrial fibrillation were examined by CMR (Magnetom, Siemens, Erlangen, Germany). Images were acquired by TrueFISP using the horizontal and vertical long-axis plane to measure left atrial end-diastolic and end-systolic areas and longitudinal dimensions. Volumes were determined with commercially available software. Left atrial end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were determined by the biplane area-length method and compared to findings obtained by the standard short-axis method. Images were acquired and analyzed a second time in the patients with atrial fibrillation.

RESULTS

There was no difference in age between men and women (p=0.147) and healthy subjects and patients (p=0.128) included in the study. EDV and ESV were significantly higher and SV and EF significantly lower in patients with atrial fibrillation than in healthy subjects (p < or = 0.009), regardless of the method used. The values obtained for EDV and ESV by the biplane area-length method were significantly higher in both healthy subjects (p<0.001) and patients with atrial fibrillation (p<0.001) than those obtained by the standard short-axis approach, whereas SV (p> or = 0.057) and EF (p> or = 0.118) did not differ significantly. In the second investigation in patients with atrial fibrillation, ESV, SV, and EF did not differ significantly between the two methods (p> or =0.481). Assessment of interobserver variability revealed good agreement in the findings of the two observers, both in normal sinus rhythm and atrial fibrillation (overall variability 0.8+/-6.5%).

CONCLUSIONS

The biplane area-length method can be used in CMR images obtained by TrueFISP to assess left atrial volumes and ejection fraction in normal subjects and patients with varying cardiac cycle length, as in atrial fibrillation.

How much are atrial volumes and ejection fractions assessed by cardiac magnetic resonance imaging influenced by the ECG gating method?

PURPOSE

Most magnetic resonance imaging (MRI) centers currently use prospective electrocardiographic (ECG) triggering for image acquisition. Retrospectively gated sequences allow the coverage of the entire cardiac cycle. It has been recently shown that ventricular volumes and ejection fraction (EF) differ according to the gating method used for image acquisition. The authors sought to evaluate how much measurements of atrial volumes and EF differ depending on the gating method.

MATERIALS AND METHODS

Eighteen subjects with no cardiovascular disease were investigated by MRI using a 1.5 Tesla scanner. Images were acquired with a gradient-echo sequence with steady-state free precession (SSFP) using the standard short-axis method for volume and EF measurements. Images were acquired with 6 mm thick slices using both prospective triggering and retrospective gating. Left and right atrial volumes (end diastolic volume [EDV]; end systolic volume [ESV]; stroke volume [SV]) and EF were determined with a commercially available software package.

RESULTS

ESV was significantly smaller with the retrospectively gated SSFP sequence than with the prospectively triggered sequence (mean difference: ESV left 3.97 +/- 1.3 ml, p < 0.0001; ESV right 4.34 +/- 1.8 ml, p < 0.0001). EF and SV were significantly smaller with prospective triggering (mean difference: EF left -5.94 +/- 0.9%, p < 0.0001; EF right -5.52 +/- 1.3 %, p < 0.0001; SV left -3.99 +/- 1.3 ml, p < 0.0001; SV right -4.32 +/- 1.9 ml, p < 0.0001). EDV remained unchanged (mean difference: EDV left -0.03 +/- 0.8 ml, p = 0.902; right EDV 0.04 +/- 0.7 ml, p = 0.882).

CONCLUSION

The gating method has a significant impact on atrial volume and EF measurements. Atrial EF is underestimated by using the prospective triggering technique.

Visual estimation versus quantitative assessment of left ventricular ejection fraction: a comparison by cardiovascular magnetic resonance imaging

PURPOSE

The aim of this study was to compare the visual and quantitative assessment for left ventricular ejection fraction (LVEF) in normal subjects and patients with impaired LV function.

METHODS

One hundred subjects (40 normal subjects, 40 patients with ischemic cardiomyopathy, and 20 patients with nonischemic cardiomyopathy) were investigated using a 1.5-T cardiovascular magnetic resonance imager. Images were acquired by a fast gradient-echo sequence with steady-state free precession using the standard short-axis method. Left ventricular EF was calculated from the sums of the outlined areas using the Simpson rule. Interobserver variability between the calculated and the visual EF was assessed. Analyses were performed randomly and blinded by 2 independent observers.

RESULTS

Left ventricular EF was significantly underestimated by the visual read in all 3 groups (mean difference: normal subjects -2.6% +/- 2.6%, ischemic cardiomyopathy -1.7% +/- 2.1%, and nonischemic cardiomyopathy -1.2% +/- 2.1%; P < or = .02). The difference was larger in normal subjects than in patients with cardiomyopathy (P = .04). The interobserver variability was smaller for the quantitative assessment than for the visual estimation.

CONCLUSION

Left ventricular EF is underestimated by visual estimation compared with the quantitative assessment. The visual approach for EF assessment may be used for rapid assessment of left ventricular function in clinical practice where accuracy is of less concern. For most accurate analysis, the quantitative standard short axis approach is required.

Impact of the ECG Gating Method on Ventricular Volumes and Ejection Fractions Assessed By Cardiovascular Magnetic Resonance Imaging

PURPOSE

Most MRI centers currently use prospective ECG triggering and fast gradient-echo sequences for image acquisition. Retrospectively gated sequences allow the coverage of the entire cardiac cycle. There is concern about whether ventricular volumes and ejection fraction (EF) differ according to the gating method used for image acquisition. We sought to evaluate the impact of the gating method on measurements of right and left ventricular volumes and EF in normal subjects.

MATERIALS AND METHODS

Fifteen subjects with no cardiovascular disease were investigated by MRI using a 1.5 Tesla scanner. Images were acquired with a gradient-echo sequence with steady-state free precession (SSFP) using the standard short-axis method for volume and EF measurements. Images were acquired with 6-mn-thick slices using both prospective triggering and retrospective gating. Left and right ventricular volumes (EDV, ESV, SV) and EF were determined with a commercially available software package (Argus, Siemens).

RESULTS

EDV and SV calculated from short-axis images were significantly smaller with the prospectively triggered SSFP sequence (mean difference: EDV left: 13.9 +/- 4.4 mL, p < 0.0001; SV left: 13.5 +/- 4.8 mL, p < 0.0001; EDV right: 14.2 +/- 3.9 mL, p < 0.0001; SV right: 14.7 +/- 5.9 mL, p < 0.0001). EF was significantly smaller for the right ventricle (mean difference -3.6 +/- 3.3%, p = 0.0008) and the left ventricle (mean difference -2.3 +/- 3.3%, p = 0.02). ESV remained unchanged (mean difference: ESV left: 0.47 +/- 3.5 mL, p = 0.6179; right ESV: 0.5 +/- 3.7 mL, p = 0.6083).

CONCLUSION

The gating method has a significant impact on volume and EF measurements. The global ventricular EF is underestimated by using the prospective triggering technique. However, the difference in the left ventricle is small and might not be of clinical relevance.

Right ventricular wall motion abnormalities found in healthy subjects by cardiovascular magnetic resonance imaging and characterized with a new segmental model

AIM

To evaluate right ventricular wall motion abnormalities in healthy subjects using a new segmental model for the right ventricle.

METHODS AND RESULTS

29 healthy subjects (9 female, 20 male, mean age 48.9+/-15 years) underwent cardiovascular magnetic resonance imaging (CMR; 1.5-Tesla Sonata, Siemens, Erlangen, Germany) for the evaluation of cardiac function and right ventricular wall motion. A steady-state free precession gradient-echo sequence (TrueFISP) was used. Right ventricular wall motion was analyzed, and the site of areas of disordered motion was classified according to the new segmental model. Such areas were seen in 27 (93.1%) of the 29 subjects. Dyskinesia was found in 22 subjects (75.9%), hypokinesia in 11 (37.9%), and bulging in 8 (27.6%). The number of wall motion abnormalities diagnosed was significantly higher in the transverse plane (86.2%) than in the short-axis plane (13.8%) and the horizontal longitudinal plane (41.4%; p = 0.000).

CONCLUSION

Right ventricular wall motion abnormalities are one of the criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy. However, our findings indicate that they may also be seen around the insertion of the moderator band in healthy subjects, so that the significance of their presence at this site in patients undergoing diagnostic investigations for this disease should be interpreted with caution.

Single and biplane TrueFISP cardiovascular magnetic resonance for rapid evaluation of left ventricular volumes and ejection fraction

INTRODUCTION

Cardiovascular magnetic resonance (CMR) allows very accurate, but time-consuming, volume assessment by the short-axis slice summation technique. The single and biplane methods of volume assessment are used less, partly because FLASH cine imaging provides poor blood-myocardium contrast in long-axis views. TrueFISP gives excellent blood-myocardium contrast, even in patients with heart failure. We hypothesized that the single plane and biplane methods of volume assessment in TrueFISP images might provide an acceptable degree of accuracy and be quicker than the short axis method, and that single and biplane left ventricular volume assessment would be more accurate with TrueFISP than with FLASH in patients with impaired ventricular function.

METHODS

Short- and long-axis CMR images were obtained by FLASH and TrueFISP with a 1.5-T scanner. We determined the accuracy of both single and biplane long-axis methods for left ventricular volume and ejection fraction (EF) measurements compared with the conventional short-axis method in 10 heart failure patients using both FLASH and TrueFISP and in 9 healthy subjects using TrueFISP.

RESULTS

No difference in volumes and EF was found between the single plane method, the biplane method, and the short-axis method using TrueFISP for image acquisition, in both patients and healthy subjects. The same was true of the results obtained by FLASH in the patients with heart failure.

CONCLUSIONS

The single and biplane methods, regardless of whether TrueFISP or FLASH is used, are a reasonable and rapid alternative to the conventional short-axis approach for left ventricular volume and EF assessment in patients with heart failure and impaired ventricular function.

How reliable is electrocardiography in differentiating transmural from non-transmural myocardial infarction? A study with contrast magnetic resonance imaging as gold standard

Cardiovascular magnetic resonance (CMR) using contrast enhancement allows exact determination of the site and transmural extent of myocardial infarction (MI). We evaluated whether 12-lead electrocardiography can differentiate transmural from non-transmural MI or determine the site of MI by comparing the findings with those of contrast-enhanced CMR. A total of 27 patients (59.5+/-12.9 years) with a history of MI (6.4+/-2.9 months) underwent CMR (Magnetom, Siemens, Erlangen, Germany). Cine images were acquired in the horizontal and vertical long axes and short axis by TrueFISP. Contrast-enhanced CMR images were acquired in the same axes by segmented FLASH 15 min after administration of gadolinium-DTPA (0.15 mmol/kg). This showed the MI to be transmural in 11 patients and non-transmural in 16. An electrocardiogram (ECG) was recorded in all patients before CMR. T-wave alterations, descending ST-depression, pathological Q-waves and absent R waves were more frequent in non-transmural MI than transmural MI, as defined by contrast-enhanced CMR (p> or =0.618). However, none of the differences were statistically significant. R-wave reduction, q waves and horizontal ST-depression were more frequent in transmural than in non-transmural MI (p> or =0.157). Again, the differences were not significant. The sensitivity of the ECG for MI localization was highest in inferior infarctions (85.71%), the specificity was highest in anterior infarctions (100%), the best positive predictive value (80%) was achieved for anterolateral infarctions, and the best negative predictive value for lateral infarctions (95.83%). Transmural and non-transmural MI cannot be differentiated by ECG. The ECG is most accurate in detecting anterolateral MI.

Impact of papillary muscles in ventricular volume and ejection fraction assessment by cardiovascular magnetic resonance

Cardiovascular magnetic resonance (CMR) is an accurate tool for the determination of right and left ventricular volumes and ejection fractions. However, the current standard short-axis technique is time-consuming and thus, often not practicable for routine daily use, because papillary muscles and trabeculations have to be marked and their volumes subtracted from the total ventricular volume. To reduce calculation time we evaluated the volumetric data that included papillary muscle and trabecular volumes and compared the outcome with the results of the standard technique. Thirty patients (17 healthy, 13 with coronary heart disease) were examined by CMR using TrueFISP (Magnetom, Siemens, Erlangen, Germany). Right and left ventricular volumes and ejection fractions were calculated using the standard short-axis technique and then again without subtracting papillary and trabecular volumes. The two methods were compared by determining the differences in results for ventricular volumes and ejection fractions. Statistically significant differences were found between the two methods for right and left ventricular stroke volumes and end-systolic volumes, and left ventricular end-diastolic volumes (EDV) (p < or = 0.011). No significant difference was found for right ventricular end-diastolic volumes (p > or = 0.149) or left or right ventricular ejection fraction (p > or = 0.130). Except in the case of left ventricular EDV, the deviations in the results of method 1 and method 2 did not vary significantly with the presence or absence of heart disease. Measurements were obtained considerably more quickly with the modified method than with the standard short-axis method (25 +/- 4 min vs. 13 +/- 3 min, p = 0.000). Although systematic differences were found when papillary and trabecular volumes were not subtracted, these differences are small and may not be of clinical relevance in healthy subjects or patients with coronary heart disease. Not subtracting the volumes of these structures enables faster determination of right and left ventricular volumes and ejection fractions without loss of the accuracy associated with the standard short-axis technique.