A novel pulse sequence scheme is presented that allows the measurement and mapping of myocardial T 1 in vivo on a 1.5 Tesla MR system within a single breath-hold. Two major modifications of conventional Look-Locker (LL) imaging are introduced: 1) selective data acquisition, and 2) merging of data from multiple LL experiments into one data set. Each modified LL inversion recovery (MOLLI) study consisted of three successive LL inversion recovery (IR) experiments with different inversion times. We acquired images in late diastole using a single-shot steady-state free-precession (SSFP) technique, combined with sensitivity encoding to achieve a data acquisition window of <200 ms duration. We calculated T 1 using signal intensities from regions of interest and pixel by pixel. T 1 accuracy at different heart rates derived from simulated ECG signals was tested in phantoms. Key words: spin-lattice relaxation time; Look-Locker; heart; myocardium Despite recent technological advances, in vivo T 1 quantification of the myocardium with modern magnetic resonance (MR) systems remains a challenge because of severe time constraints due to cardiac and respiratory motion. While myocardial T 1 is shorter and therefore relatively easier to measure at low field strengths, it has a value of ϳ1000 ms at a field strength of 1.5 T, exceeding the duration of the cardiac cycle (ϳ600 -1200 ms) in most subjects (1,2). Since standard inversion recovery (IR) measurements require a relaxation period of four to five times T 1 to allow for full magnetization recovery after each 180°pulse (3), only four to five such single-point IR experiments can be performed within one breath-hold (ca. 20 s). To achieve accurate T 1 estimates from a three-parameter curve-fitting procedure, as is commonly employed, data from at least six to 10 time points should be available (4). The multipoint approach, as first described by Look and Locker (5), samples the relaxation curve multiple times after an initial preparation pulse (6). This technique has been shown theoretically to be highly efficient (7), and has been widely used for T 1 measurements of the brain (8 -11). It is not suitable for pixel-by-pixel T 1 mapping of the heart because data acquisition is performed continuously throughout the cardiac cycle without regard for cardiac motion, which means that T 1 values can only be derived for regions of interest (ROIs) that must be defined manually for every frame (1). The resultant T 1 values may consequently be subject to inaccuracy caused by misregistration effects.In this work we present a pulse sequence scheme that allows for accurate in vivo T 1 measurements and T 1 mapping of myocardium with high spatial resolution and within a single breath-hold. To overcome the limitations of the conventional LL approach for cardiac applications, we propose a modified LL IR scheme (MOLLI), which introduces two principles to the standard LL sequence: 1) selective data acquisition at a given time of the cardiac cycle over successive heartbeats, and (2) merging of image sets...

SummaryBackgroundIn patients with suspected coronary heart disease, single-photon emission computed tomography (SPECT) is the most widely used test for the assessment of myocardial ischaemia, but its diagnostic accuracy is reported to be variable and it exposes patients to ionising radiation. The aim of this study was to establish the diagnostic accuracy of a multiparametric cardiovascular magnetic resonance (CMR) protocol with x-ray coronary angiography as the reference standard, and to compare CMR with SPECT, in patients with suspected coronary heart disease.MethodsIn this prospective trial patients with suspected angina pectoris and at least one cardiovascular risk factor were scheduled for CMR, SPECT, and invasive x-ray coronary angiography. CMR consisted of rest and adenosine stress perfusion, cine imaging, late gadolinium enhancement, and MR coronary angiography. Gated adenosine stress and rest SPECT used 99mTc tetrofosmin. The primary outcome was diagnostic accuracy of CMR. This trial is registered at controlled-trials.com, number ISRCTN77246133.FindingsIn the 752 recruited patients, 39% had significant CHD as identified by x-ray angiography. For multiparametric CMR the sensitivity was 86·5% (95% CI 81·8–90·1), specificity 83·4% (79·5–86·7), positive predictive value 77·2%, (72·1–81·6) and negative predictive value 90·5% (87·1–93·0). The sensitivity of SPECT was 66·5% (95% CI 60·4–72·1), specificity 82·6% (78·5–86·1), positive predictive value 71·4% (65·3–76·9), and negative predictive value 79·1% (74·8–82·8). The sensitivity and negative predictive value of CMR and SPECT differed significantly (p<0·0001 for both) but specificity and positive predictive value did not (p=0·916 and p=0·061, respectively).InterpretationCE-MARC is the largest, prospective, real world evaluation of CMR and has established CMR's high diagnostic accuracy in coronary heart disease and CMR's superiority over SPECT. It should be adopted more widely than at present for the investigation of coronary heart disease.FundingBritish Heart Foundation.

Purpose:To establish normal ranges of left ventricular (LV) and right ventricular (RV) dimensions as determined by the current pulse sequences in cardiac magnetic resonance imaging (MRI). Materials and Methods:Sixty normal subjects (30 male and 30 female; age range, 20 -65) were examined; both turbo gradient echo (TGE) and steady-state free precession (SSFP) pulse sequences were used to obtain contiguous short-axis cine data sets from the ventricular apex to the base of the heart. The LV and RV volumes and LV mass were calculated by modified Simpson's rule.Results: Normal ranges were established and indexed to both body surface area (BSA) and height. There were statistically significant differences in the measurements between the genders and between TGE and SSFP pulse sequences. For TGE the LV end-diastolic volume (EDV)/BSA (mL/m 2 ) in males was 74.4 Ϯ 14.6 and in females was 70.9 Ϯ 11.7, while in SSFP in males it was 82.3 Ϯ 14.7 and in females it was 77.7 Ϯ 10.8. For the TGE the LV mass/ BSA (g/m 2 ) in males was 77.8 Ϯ 9.1 and in females it was 61.5 Ϯ 7.5, while in SSFP in males it was 64.7 Ϯ 9.3 and in females it was 52.0 Ϯ 7.4. For TGE the RV EDV/BSA (mL/ m 2 ) in males was 78.4 Ϯ 14.0 and in females it was 67.5 Ϯ 12.7, while in SSFP in males it was 86.2 Ϯ 14.1 and in females it was 75.2 Ϯ 13.8. Conclusion:We have provided normal ranges that are gender specific as well as data that can be used for age-specific normal ranges for both SSFP and TGE pulse sequences. CARDIAC MAGNETIC RESONANCE IMAGING (MRI) has been shown to be an accurate and reproducible tool for the estimation of both left ventricular (LV) and right ventricular (RV) measurements (1-8). Currently, the two pulse sequences, which are in common clinical and research use for acquisition of volumes data sets, are segmented k-space turbo gradient echo (TGE) and the more recent steady-state free precession (SSFP) technique. The latter sequence has been validated in animal studies (9). TGE acquisition has been compared to previously validated sequences with excellent correlation (7).Lorenz et al published the first normal range for cardiac MRI LV mass (g) and volumes, utilizing a conventional cine gradient echo sequence performed with free breathing (10). Another normal range for TGE with breath holding was developed by Marcus et al (11). There is a difference between the values obtained by the two groups. Lorenz et al report a mean LV mass of 178 Ϯ 31 for men (N ϭ 47) and of 125 Ϯ 26 for women (N ϭ 28), while Marcus et al report a mean LV mass of 142 Ϯ 20 for men (N ϭ 32) and 102 Ϯ 15.9 for women (N ϭ 29). These differences remained after indexation to body surface area (BSA). Therefore, there is a need for further work to establish a normal range for the TGE pulse sequence, which remains in common use. Furthermore, because of improved delineation of the endocardial borders and faster acquisition time, it is anticipated that SSFP pulse sequences will be the most frequently used technique in the future. Comparative values for ventricular volumes based...

A prospective study approved by the local ethics committee was performed to establish the normal range and reproducibility of myocardial T1 values as assessed with single-breath-hold T1 mapping with high spatial resolution. With a 1.5-T magnetic resonance (MR) imaging system, baseline and contrast material-enhanced modified Look-Locker inversion recovery, or MOLLI, imaging was performed in 15 healthy volunteers who had given written informed consent. Image quality scores and myocardial T1 values were derived for standard short-axis segments and sections. Results were compared with those from a second MR imaging study performed on the same day (baseline only) and those from a third study performed on a different day (baseline and contrast enhanced; eight volunteers). Intra- and interobserver agreement were determined. Myocardial T1 maps were obtained rapidly in a reproducible fashion. A normal range for baseline and postcontrast myocardial T1 was established (baseline mean T1 in short-axis sections, 980 msec +/- 53 [standard deviation]; 95% confidence interval: 964, 997; number of sections, 43). This technique could enable direct quantification of changes in tissue characteristics in ischemic and inflammatory myocardial diseases.

Stepping-table digital subtraction contrast material-enhanced MR angiography has high accuracy compared with catheter angiography in patients with arterio-occlusive disease of the aorta and outflow vessels. These preliminary study results suggest that this technique may ultimately provide a safe, noninvasive, and cost-effective alternative to catheter angiography.