Left ventricular infarct size,peri‐infarct zone,and papillary scar measurements: A comparison of high‐resolution 3D and conventional 2D late gadolinium enhancement cardiac MR

Purpose

To compare higher spatial resolution 3D late gadolinium enhancement (LGE) cardiovascular magnetic resonance (Cardiac MR) with 2D LGE in patients with prior myocardial infarction.

Materials and Methods

Fourteen patients were studied using high spatial resolution 3D LGE (1.3 × 1.3 × 5.0 mm³) and conventional 2D LGE (2 × 2 × 8 mm³) scans. The signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) were measured. Total infarct volume, peri‐infarct volume measured in a limited slab, and papillary muscle scar volume were compared using Bland–Altman analysis. Image quality was graded.

Results

3D LGE had higher scar SNR (P < 0.001), higher myocardial SNR (P = 0.001), higher papillary scar‐blood CNR (P = 0.01), and greater sharpness (P = 0.01). The scar volumes agreed (14.5 ± 8.2 for 2D, vs. 13.2 ± 8.8 for 3D), with bias ± 2 standard deviations (SDs) of 0.5 ± 6.8 mL, P = 0.59 R = 0.91. The peri‐infarct volumes correlated but less strongly than scar (P = 0.40, R = 0.77). For patients with more heterogeneous scar, larger peri‐infarct volumes were measured by 3D (1.9 ± 1.1 mL for 2D vs. 2.4 ± 1.6 mL for 3D, P = 0.15, in the matched region). Papillary scar, present in 6/14 (42%) patients, was more confidently identified on 3D LGE.

Conclusion

Higher spatial resolution 3D LGE provides sharper images and higher SNR, but less myocardial nulling. Scar volumes agree well, with peri‐infarct volumes correlating less well. 3D LGE may be superior in visualization of papillary muscle scar. J. Magn. Reson. Imaging 2009;30:794–800. © 2009 Wiley‐Liss, Inc.     

Improved delayed enhanced myocardial imaging with T2-Prep inversion recovery magnetization preparation

Purpose

To develop a magnetization preparation method that improves the differentiation of enhancing subendocardial infarction (MI) from ventricular blood for myocardial delayed‐enhancement (DE) magnetic resonance imaging (MRI).

Materials and Methods

T₂Prep‐IR is a magnetization preparation pulse that consists of a T₂ preparation (T₂Prep) followed immediately by a nonselective inversion recovery (IR) pulse. The first imaging excitation is then delayed an inversion time (TI) to allow nulling of normal myocardium in DE study. The amount of T₂ contrast is determined by the effective echo time of the T₂Prep pulse, TE_eff. TE_eff is selected to differentiate MI and blood that share similar T₁ values but have different T₂ values. The T₂Prep‐IR preparation was incorporated into a fast gradient echo sequence to produce an image with both T₁ and T₂ weighting. Simulations predict that this method will generate improved contrast between MI and chamber blood compared to conventional IR methods.

Results

Comparisons between images acquired using conventional IR and T₂Prep‐IR in patients with MI indicate that this new approach significantly improves the blood‐MI contrast (122 ± 32% higher than that of IR with P < 0.05).

Conclusion

Our preliminary patient studies confirm that this preparation is helpful for improved delineation of subendocardial infarction. J. Magn. Reson. Imaging 2008;28:1280–1286. © 2008 Wiley‐Liss, Inc.     

Ultra low-dose of gadobenate dimeglumine for late gadolinium enhancement (LGE) imaging in acute myocardial infarction: A feasibility study

PurposeTo assess the feasibility of using an ultra-low dose (0.05 mmol/kg of body weight [BW]) of high relaxivity contrast agent for late gadolinium enhancement (LGE) imaging in patients with acute myocardial infarction (AMI).Materials and methods17 consecutive patients (mean age, 60.1 ± 10.3 years) with ST-segment elevation AMI underwent two randomized cardiac magnetic resonance studies (exam intervals between 24 and 48 h) on a 1.5 T unit during the first week after the event using gadobenate dimeglumine (Gd-BOPTA) at the dose of 0.1 mmol/kg BW (standard dose or SD group) and 0.05 mmol/kg BW (half dose or HD group). Image quality was qualitatively assessed. Quantitative analysis of LGE were performed by measuring signal intensity (SI), signal-to-noise ratio (SNR) in the infarcted myocardium (IM), non-infarcted myocardium (N-IM) and left ventricular cavity (LVC) in images acquired at 1, 3, 5, 10, 15 and 20 min after administration of Gd-BOPTA using both contrast media protocol. Contrast-to-noise ratio (CNR) between IM and N-IM (CNR IM/N-IM) and between IM and LVC (CNR IM/LVC) were also quantified for each time point. Moreover the extent of infarcted myocardium was measured.Results102 LGE images were evaluated for each dose group. Quality score was significantly higher for SD at 1, 15 and 20 min (0.002 < p < 0.046) and for HD at 5 min (p = 0.013). SNR has been higher in the SD group compared to the HD group even though not statistically significant at any time-point for both IM (SD vs. HD: 87.7 ± 73 vs. 65 ± 66; 0.15 < p < 0.38) and N-IM (SD vs. HD: 22 ± 61 vs. 9.9 ± 6.5; 0.09 < p < 0.43). LVC SNR was significantly higher with SD at 10 min (p = 0.03), 15 min (p = 0.001) and 20 min (p = 0.004). CNR between the IM and N-IM was significantly higher using SD compared to HD (1382.24 ± 1049 vs. 695.4 ± 500; 0.000 < p < 0.028) at 10, 15 and 20 min. No significant differences in CNR IM/LVC were noted for HD acquired 5 min after CM administration compared to SD acquired at 10 (p = 0.34), 15 (p = 0.96) and 20 (p = 0.41) min, and between HD at 10 min compared to SD acquired at 15 min (p = 0.78) and 20 min (p = 0.32). Good correlation between SD and HD (0.56 < r² < 0.85, p < 0.024) was found at all time-points in the measuring of IA.ConclusionThe use of a 0.05 mmol/kg dose of gadobenate dimeglumine is feasible for LGE imaging of acute MI and the best image quality is obtained at 5 min after contrast administration. It could be beneficial in patient with renal failure and a solution to improve the identification of subendocardial infarction reducing examination time, costs and total gadolinium load. However, the standard dose of 0.1 mmol/kg provides overall better image quality, with the best performance obtained at the delay of 10 min or more after Gd-BOPTA administration, and it should be routinely preferred.     

Pulmonary vein inflow artifact reduction for free‐breathing left atrium late gadolinium enhancement

Two‐dimensional “pencil‐beam” navigator, placed on the right hemidiaphragm, is used for free‐breathing late gadolinium enhancement of the left atrium in patients with atrial fibrillation. The pencil‐beam navigator creates an inflow artifact in the right pulmonary veins and atrial wall that may obscure local pulmonary vein and left atrium scars. To reduce this artifact, we propose a large slab right hemidiaphragm projection navigator that measures the respiratory motion while reducing the associated inflow artifact. Eighteen subjects underwent pulmonary vein late gadolinium enhancement using the pencil‐beam and projection navigator. Subjective inflow and respiratory motion artifact scores (1 = severe, 2 = moderate, 3 = mild, and 4 = none) from two blinded readers were compared. The artifact scores were 3.8 ± 0.4 and 2.1 ± 0.7 for the projection and pencil‐beam navigators, respectively (P < 0.001). Respiratory motion artifact scores were similar between the two techniques (3.0 ± 0.5 vs. 3.1 ± 0.5 for projection vs. pencil‐beam navigator). The proposed method greatly reduces the inflow artifact in free‐breathing pulmonary vein late gadolinium enhancement while allowing adequate respiratory motion compensation. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Dynamic late gadolinium enhancement simply quantified using myocardium to lumen signal ratio: normal range of ratio and diffuse abnormal enhancement of cardiac amyloidosis

Purpose:

To detect abnormal myocardial tissue in patients with diffuse myocardial disease, we propose a simple technique of late gadolinium enhancement (LGE) using routine myocardial imaging modalities.

Materials and Methods:

We retrospectively reviewed LGE images from 51 patients with normal myocardium and 10 patients with pathologically proven cardiac amyloidosis (CA). We obtained sequential LGE images from patients at 2, 5, 10, and 20 minutes after injection of Gd‐DTPA (0.15 mmol/kg) with a fixed inversion time of 300 msec. We evaluated the signal intensity ratio of the myocardium to the left ventricular lumen (M/L) in one long and two short axial sections within 463 and 120 segments of normal myocardium and CA, respectively. Visually unenhanced and enhanced regions of myocardium were evaluated in each segment of patients with CA.

Results:

Among normal myocardium, M/L (means ± standard deviation; SD) was stable with time (2, 5, 10, and 20 min: 0.34 ± 0.03, 0.31 ± 0.05, 0.34 ± 0.07, and 0.42 ± 0.11, respectively). The calculated M/L of unenhanced (0.60 ± 0.20, 0.68 ± 0.19, 0.76 ± 0.20, and 1.09 ± 0.25, respectively) and enhanced myocardium (0.77 ± 0.27, 0.99 ± 0.29, 1.20 ± 0.40, and 1.45 ± 0.54, respectively) in patients with CA was significantly greater than that seen for the normal myocardium at each time and increased over time.

Conclusion:

In patients with CA, diffuse myocardial abnormalities can be demonstrated using M/L, and this technique may be useful for the characterization of other myocardial diseases. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

T1‐weighted–SPACE dark blood whole body magnetic resonance angiography (DB‐WBMRA): Initial experience

Purpose:

To evaluate the feasibility of the dark blood fast spin echo (FSE) T1‐weighted–Sampling Perfection with Application of optimized Contrasts using different flip angle Evolution (T1w‐SPACE) sequence in assessing whole body arterial wall information from the extracranial carotids to the popliteal artery.

Materials and Methods:

Twenty‐eight subjects were subjected to noncontrast, dark blood whole body magnetic resonance angiography (DB‐WBMRA) using a T1w‐SPACE sequence optimized for each of the individual stations: carotid artery, thoracic aorta, abdominal aorta, and thigh/superficial femoral artery (SFA). Image quality/vessel wall visualization and the time required to image the four stations were evaluated. Two observers checked the reproducibility of vessel wall depiction by performing quantitative measurements in registered initial and repeat studies (six subjects) of vessel wall and lumen area at 17 locations along the arterial tree.

Results:

In 25 of the 28 scanned subjects, dark blood arterial images acquired in approximately 1 hour total imaging time allowed whole body arterial vessel wall visualization. Quantitative measurements showed high correlation between the initial and repeat studies for each of the observers as well as high interobserver reproducibility (r > 0.95; P < 0.01).

Conclusion:

DB‐WBMRA using T1w‐SPACE is feasible and can be performed with a high degree of reliability. J. Magn. Reson. Imaging 2010; 31: 502–509. © 2010 Wiley‐Liss, Inc.     

Multicontrast late gadolinium enhancement imaging enables viability and wall motion assessment in a single acquisition with reduced scan times

Purpose

To determine the accuracy of multicontrast late enhancement imaging (MCLE) in the assessment of myocardial viability and wall motion compared to the conventional wall motion and viability cardiac magnetic resonance imaging (MRI) pulse sequences.

Materials and Methods

Forty‐one patients with suspected myocardial infarction were studied. Patients underwent assessment of cardiac function with cine steady‐state free‐precession (SSFP), followed by late gadolinium enhancement (LGE) imaging using inversion recovery gradient echo scanning (IR‐GRE) sequence and MCLE. MCLE was compared to cine SSFP in the assessment of wall motion, ejection fraction (EF), left ventricular (LV) mass, LV end‐diastolic volume (EDV), and to IR‐GRE for measuring infarct size.

Results

MCLE, IR‐GRE, and SSFP imaging demonstrated excellent agreement in the assessment of EF, LV infarct size, and LV mass (r > 0.95, P < 0.001 for all measures), as well as in the assessment of wall motion (κ statistic 0.75).

Conclusion

MCLE provided coregistered images for the assessment of viability and wall motion without loss of accuracy in the assessment of quantitative cardiac parameters. MCLE provides accurate quantitative cardiac assessment with reduced scan times compared to the conventional sequences and thus may be used as an alternative to conventional cine SSFP and IR‐GRE imaging. J. Magn. Reson. Imaging 2009;30:771–777. © 2009 Wiley‐Liss, Inc.