Myocardial extravascular extracellular volume fraction measurement by gadolinium cardiovascular magnetic resonance in humans: slow infusion versus bolus

Abstract

BackgroundMyocardial extravascular extracellular volume fraction (Ve) measures quantify diffuse fibrosis not readily detectable by conventional late gadolinium (Gd) enhancement (LGE). Ve measurement requires steady state equilibrium between plasma and interstitial Gd contrast. While a constant infusion produces steady state, it is unclear whether a simple bolus can do the same. Given the relatively slow clearance of Gd, we hypothesized that a bolus technique accurately measures Ve, thus facilitating integration of myocardial fibrosis quantification into cardiovascular magnetic resonance (CMR) workflow routines. Assuming equivalence between techniques, we further hypothesized that Ve measures would be reproducible across scans.MethodsIn 10 volunteers (ages 20-81, median 33 yr, 3 females), we compared serial Ve measures from a single short axis slice from two scans: first, during a constant infusion, and second, 12-50 min after a bolus (0.2 mmol/kg gadoteridol) on another day. Steady state during infusion was defined when serial blood and myocardial T1 data varied <5%. We measured T1 on a 1.5 T Siemens scanner using a single-shot modified Look Locker inversion recovery sequence (MOLLI) with balanced SSFP. To shorten breath hold times, T1 values were measured with a shorter sampling scheme that was validated with spin echo relaxometry (TR = 15 sec) in CuSO4-Agar phantoms. Serial infusion vs. bolus Ve measures (n = 205) from the 10 subjects were compared with generalized estimating equations (GEE) with exchangeable correlation matrices. LGE images were also acquired 12-30 minutes after the bolus.ResultsNo subject exhibited LGE near the short axis slices where Ve was measured. The Ve range was 19.3-29.2% and 18.4-29.1% by constant infusion and bolus, respectively. In GEE models, serial Ve measures by constant infusion and bolus did not differ significantly (difference = 0.1%, p = 0.38). For both techniques, Ve was strongly related to age (p < 0.01 for both) in GEE models, even after adjusting for heart rate. Both techniques identically sorted older individuals with higher mean Ve values.ConclusionMyocardial Ve can be measured reliably and accurately 12-50 minutes after a simple bolus. Ve measures are also reproducible across CMR scans. Ve estimation can be integrated into CMR workflow easily, which may simplify research applications involving the quantification of myocardial fibrosis.

Quantification of Left Ventricular Interstitial Fibrosis in Asymptomatic Chronic Primary Degenerative Mitral Regurgitation

“…17 A steady-state free precession, single breath hold modified Look-Locker inversion recovery sequence was used for T1 mapping in the LV base and mid-ventricular short axis levels before and between 15 and 20 minutes after contrast administration (11 phases [3, 3, 5 scheme], total breath hold 17 R-R intervals). 18 Late enhancement imaging was performed 7 to 10 minutes after 0.15 mmol/kg of gadolinium contrast bolus (Gadovist Bayer Healthcare).…”

Synthetic late gadolinium enhancement cardiac magnetic resonance for diagnosing myocardial scar

“…The imaging parameters for the LGE were as follows: field of view 340 Â 276 mm, slice thickness 8 mm, image matrix 256 Â 156, voxel size 1.3 Â 1.3 Â 8 mm 3 , time to repetition (TR) 8.25 ms, time to echo (TE) 3.2 ms and flip angle 25 . Post contrast T1 maps were acquired using breath-hold ECG triggered Modified Look Locker Inversion Recovery (MOLLI) sequence using a shorter protocol of 4(1)3(1)2 [9] and motion correction [10]. The CMR parameters included: steady-state free precession single shot read out in end-diastole, field of view 360 Â 270 mm 2 , slice thickness 6 mm, flip angle 35…”

[No Title Available]

“…Many precise software tools are available for the assessment of ventricular function using tagging (1) and diffuse or focal fibrosis with modified Lock-Locker inversion recovery (MOLLI) (13)(14)(15) imaging.…”

“…The T1 mapping technique has already been validated by means of myocardial biopsies in the clinical context of patients with nonischemic fibrosis who were referred for cardiac transplant (16) . Myocardial extracellular volume measurements quantify diffuse fibrosis not readily detectable by conventional late gadolinium enhancement (13,14) . In the present case, we could differentiate the fibrosis detected by late enhancement on the apex of the left ventricle (high extracellular volume -ECV, 57%) from the fibrosis present on the bottom of the left ventricle (high ECV, 32%) in comparison with healthy hearts (ECV = 27%).…”