3D Inversion Recovery Research Articles

Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols

Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction. Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed. SS_SSFP had significantly better quality scores in all categories (P = 0.037, P = 0.014, P = 0.021, P = 0.03). SNR(infarct) and SNR(blood) were significantly better for IR_FGRE than for SS_SSFP (P = 0.048, P = 0.018). No significant difference was found in SNR(myocardium) and CNR. The myocardial volume was significantly larger with SS_SSFP (170.7 versus 159.2 ml, P<0.001), but no significant difference was found in infarct volume and infarct extent. SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.

Results of a tissue engineered pulmonary valve in humans assessed with CMR

Methods TEng valves had been implanted into the right ventricular outflow tract of 12 pts (age: 15 ± 8,5 yrs; Matrix-PTM n = 7; Matrix-P-PlusTM n = 5) due to pulmonary stenosis or insufficiency within a median 5 months range (2-7 months) before a comprehensive follow-up by CMR. Echocardiography was suspicious of accelerated blood flow in the main pulmonary artery in 10 of those. The severity of the pulmonary valve stenosis was assessed by gradient echo cine MRI (FOV 270 × 270 mm, voxel size 1.88 × 1.94 × 5 mm, TR/TE/α = 4.4 ms/2.7 ms/15°) and phase-contrast velocity mapping (FOV 270 × 270 mm, voxel size 1.64 × 1.4 × 7 mm, TR/TE/α = 15 ms/2.5 ms/30°, velocity encoding (VENC) = 400 cm/s) were applied. For tissue characterisation late enhancement imaging (Gd 0.1 mmol/kg) using an ECG triggered 3D inversion recovery sequence (TR/TE/α= 3.7 ms/1.8 ms/15°; voxel size 1.17 × 1.27 × 10 mm) and T1 and T2 weighted turbo spin echo sequences were utilized.

Detection and characteristics of microvascular obstruction in reperfused acute myocardial infarction using an optimized protocol for contrast-enhanced cardiovascular magnetic resonance imaging

Several cardiovascular magnetic resonance imaging (CMR) techniques are used to detect microvascular obstruction (MVO) after acute myocardial infarction (AMI). To determine the prevalence of MVO and gain more insight into the dynamic changes in appearance of MVO, we studied 84 consecutive patients with a reperfused AMI on average 5 and 104 days after admission, using an optimised single breath-hold 3D inversion recovery gradient echo pulse sequence (IR-GRE) protocol. Early MVO (2 min post-contrast) was detected in 53 patients (63%) and late MVO (10 min post-contrast) in 45 patients (54%; p = 0.008). The extent of MVO decreased from early to late imaging (4.3 ± 3.2% vs. 1.8 ± 1.8%, p < 0.001) and showed a heterogeneous pattern. At baseline, patients without MVO (early and late) had a higher left ventricular ejection fraction (LVEF) than patients with persistent late MVO (56 ± 7% vs. 48 ± 7%, p < 0.001) and LVEF was intermediate in patients with early MVO but late MVO disappearance (54 ± 6%). During follow-up, LVEF improved in all three subgroups but remained intermediate in patients with late MVO disappearance. This optimised single breath-hold 3D IR-GRE technique for imaging MVO early and late after contrast administration is fast, accurate and allows detection of patients with intermediate remodelling at follow-up.

Assessment of Myocardial Viability with 3D MRI at 3 T

The aim of our study was to show that spatial resolution can be improved without loss of diagnostic accuracy if a 3D inversion recovery gradient-recalled echo (GRE) sequence is used instead of a segmented inversion recovery GRE at 3 T for the assessment of myocardial infarction. Fifteen patients with myocardial infarction were examined on a 3-T MR system. A segmented breath-hold 3D inversion recovery GRE technique with a voxel size of 6.3 mm(3) was compared with a breath-hold standard 2D inversion recovery GRE technique with a voxel size of 21.3 mm(3) for the detection of delayed enhancement. Contrast-to-noise ratios (CNRs) were calculated and infarct volumes were measured. Detection and transmural extent of infarctions were evaluated using kappa statistics. Total acquisition times were measured for both sequences. The CNR in the 3D technique did not show any significant difference compared with the 2D technique. The correlation coefficients of the infarct volumes determined with the 3D and 2D inversion recovery GRE studies at 3 T were r = 0.99 (p < 0.001). The assessment of the presence of hyperenhanced myocardium in all segments and the evaluation of transmurality resulted in very good agreement (kappa = 0.98 and kappa = 0.90). Total acquisition time was significantly shorter with the 3D technique (2.4 +/- 0.9 minutes) than with the 2D technique (4.9 +/- 1.5 minutes) (p < 0.001). The use of a 3D inversion recovery GRE sequence at 3 T allows accurate assessment of myocardial infarction without loss of CNR compared with the standard 2D technique. Furthermore, data acquisition time can be significantly reduced.

Free-Breathing MRI for the Assessment of Myocardial Infarction: Clinical Validation

The objective of our study was to validate free-breathing 2D inversion recovery delayed-enhancement MRI for the assessment of myocardial infarction compared with a breath-hold 3D technique. Institutional review board approval and written informed consent were obtained. Thirty-two patients (25 men, seven women; mean age, 68 years; age range, 39-84 years) underwent breath-hold gradient-echo 3D inversion-recovery delayed-enhancement MRI and free-breathing respiratory-triggered 2D inversion-recovery delayed-enhancement MRI of the heart (scanning time, 50-80 seconds). Infarct size was quantitatively analyzed as a percentage of the left ventricle. The location and transmural extent of myocardial infarction were assessed by visual scoring. Intraclass correlation and Bland-Altman analysis were used to evaluate the agreement between the techniques for infarct quantification. Kappa statistics were used to analyze the visual score. Excellent agreement between the two techniques was observed for infarct quantification (intraclass correlation = 0.99 [p < 0.01]; mean difference +/- SD = 0.32% +/- 2.4%). The agreement in assessing transmural extent of infarction was good to excellent between the free-breathing technique and the 3D breath-hold technique (kappa varied between 0.70 and 0.96 for all segments). No regions of infarction were missed using the free-breathing approach. The free-breathing 2D delayed-enhancement MRI sequence is a fast and reliable tool for detecting myocardial infarction.

Multisequence-imaging protocols to detect cortical lesions of patients with multiple sclerosis: Observations from a post-mortem 3 Tesla imaging study

Neocortical lesions (NLs) are an important component of multiple sclerosis (MS) pathology and may account for part of the physical and cognitive disability. Visualizing NLs of patients with MS using magnetic resonance imaging (MRI) poses several significant challenges. We optimized the inversion time (TI) of T 1-based magnetization-prepared rapid acquisition gradient-echo (MPRAGE) images by suppressing the signal of the lesions and enhancing their appearance as hypointensities, on the basis of the derived quantitative T 1 measurements. The latter were achieved by the means of 2D inversion recovery fast spin echo (IR-FSE), repeated using different inversion times (TI). Comparisons of detection of NLs by MPRAGE and dual echo T 2 weighted (T 2W) and proton density (PD) W. Four coronal brain slices from a deceased MS patient and two coronal brain slices from two formerly healthy donors were imaged using a 3 Tesla magnet (3 T) equipped with a multi-channel coil. Based upon the averaged T1 values computed from the MS specimen as well as visual inspection, an optimal TI of 380 ms was selected for the MPRAGE image. No NLs were seen in the specimens of the two healthy donors. Of the 40 total NLs observed, 8 (20%) were visible in all three sequences employed. Three (7.5%) NLs were visible only in the PDW image and 5 (12.5%) were seen only in the T 2W image. Four NLs (10%) had clearly unique conspicuity in the MPRAGE image. Of those, 3 were retrospectively scored in the PDW image (1 NL) or in the T2W image (2 NLs). We conclude that for the detection of MS-related NLs, high-resolution T 1-based MPRAGE and T 2-W images offer complementary information and the combination of the two image sequences is crucial for increasing the sensitivity of detecting MS-induced NLs.

Detection of Myocardial Fibrosis in Systemic Sclerosis by Contrast-Enhanced Magnetic Resonance Imaging

Our study aimed to assess the prevalence and pattern of late gadolinium enhancement (LGE) as an in vivo correlate of myocardial fibrosis in cardiac asymptomatic patients with systemic sclerosis (SSc). Cardiac magnetic resonance imaging was successfully performed in 34 patients (30 female, 4 male, mean age of 54 +/- 14 years) with proven SSc and in controls with matching age, sex and cardiovascular risk factors. All examinations were performed on a 1.5 T MR system (Avanto, Siemens, Germany). 2D inversion recovery spoiled gradient echo images (TR 8.0 msec, TE 4.0 msec, TI 180 - 240 msec, FA 20 degrees, slice thickness 8 mm, in-plane resolution 1.2 x 1.2 mm (2)) were acquired 10 to 15 min after injection of 0.2 mmol Gd-DTPA per kg body weight to detect myocardial LGE. Poorly defined, patchy as well as well-defined focal areas of LGE were detected predominantly in the mid-myocardial layer of the basal left ventricular segments in 5 of 34 (15 %) SSc patients. A focal area of LGE was observed within the apical septum in one control (3 %, p > 0.05). LGE was observed in a total of 15 segments of the SSc patients and in 1 segment of the controls (p < 0.005). Our results revealed a significantly higher number of LGE positive segments in patients with SSc compared to matched controls, and demonstrate the ability of contrast-enhanced MRI to detect myocardial fibrosis, the hallmark of scleroderma heart disease, in-vivo.

1035 Value of a 2D phase-sensitive inversion recovery (PSIR) sequence in comparison to a 3D inversion recovery gradient echo sequence (IR-GRE) for the detection of myocardial scar by MRI in different myocardial diseases

ss Open Acce Meeting abstract 1035 Value of a 2D phase-sensitive inversion recovery (PSIR) sequence in comparison to a 3D inversion recovery gradient echo sequence (IR-GRE) for the detection of myocardial scar by MRI in different myocardial diseases Kathrin Schindler*1, Christian Lucke1, Alexander Kosser1, Janine Hoffmann1, Stefan Nitzsche1, Bernhard Schnackenburg2, Gerhard Schuler3, Holger Thiele3 and Matthias Gutberlet1

1027 Rapid and accurate free-breathing 3D delayed enhancement imaging for myocardial viability assessment: comparison with breath-hold 2D imaging

Introduction Delayed enhancement MRI (DE-MRI) has been established as a diagnostic imaging standard for myocardial viability assessment. The current reference standard for DE-MRI uses an inversion-recovery 2D gradient echo sequence to acquire images during repetitive breathholds. This breath-hold 2D (2DBH) technique requires significant patient cooperation and suffers from potential slice misregistration due to diaphragmatic excursions in different breath-holds. To overcome these limitations, navigator-gated 3D (3DNAV) DE-MRI has been developed using a diaphragmatic navigator to monitor respiratory motion and adjust data acquisition accordingly. Previous 3DNAV sequences employed the accept/reject gating algorithm with a fixed gating window which can lead to long imaging time in the case of a steady diaphragmatic drift.

An optimized 3D inversion recovery prepared fast spoiled gradient recalled sequence for carotid plaque hemorrhage imaging at 3.0 T

An optimized 3D inversion recovery prepared fast spoiled gradient recalled sequence (IR FSPGR) on a 3-T scanner for carotid plaque imaging is described. It offers clear blood and fat signal suppression at the carotid artery bifurcation and highlights the regions of carotid plaque affected by hemorrhage at 3 T with high contrast and contrast-to-noise ratio compared with other sequences. It can potentially be used to replace the more traditional noncontrast T(1)-weighted 2D black-blood imaging for hemorrhage detection and offers additional benefits of high-resolution 3D volumetric visualization.

Separate visualization of endolymphatic space, perilymphatic space and bone by a single pulse sequence; 3D-inversion recovery imaging utilizing real reconstruction after intratympanic Gd-DTPA administration at 3 Tesla

Twenty-four hours after intratympanic administration of gadolinium contrast material (Gd), the Gd was distributed mainly in the perilymphatic space. Three-dimensional FLAIR can differentiate endolymphatic space from perilymphatic space, but not from surrounding bone. The purpose of this study was to evaluate whether 3D inversion-recovery turbo spin echo (3D-IR TSE) with real reconstruction could separate the signals of perilymphatic space (positive value), endolymphatic space (negative value) and bone (near zero) by setting the inversion time between the null point of Gd-containing perilymph fluid and that of the endolymph fluid without Gd. Thirteen patients with clinically suspected endolymphatic hydrops underwent intratympanic Gd injection and were scanned at 3 T. A 3D FLAIR and 3D-IR TSE with real reconstruction were obtained. In all patients, low signal of endolymphatic space in the labyrinth on 3D FLAIR was observed in the anatomically appropriate position, and it showed negative signal on 3D-IR TSE. The low signal area of surrounding bone on 3D FLAIR showed near zero signal on 3D-IR TSE. Gd-containing perilymphatic space showed high signal on 3D-IR TSE. In conclusion, by optimizing the inversion time, endolymphatic space, perilymphatic space and surrounding bone can be separately visualized on a single image using a 3D-IR TSE with real reconstruction.

３．０Ｔ ＭＲＩにおける３Ｄ心臓遅延造影ＭＲＩの検討

Cardiac late Gadolinium enhancement MR imaging has been shown to allow assessment of myocardial viability in patients with ischemic heart disease. The current standard approach is a 3D inversion recovery sequence at 1.5 Tesla. The aims of this study were to evaluate the technique feasibility and clinical utility of MR viability imaging at 3.0 Tesla in patients with myocardial infarction and cardiomyopathy. In phantom and volunteer studies, the inversion time required to suppress the signal of interests and tissues was prolonged at 3.0 Tesla. In the clinical study, the average inversion time to suppress the signal of myocardium at 3.0 Tesla with respect to MR viability imaging at 1.5 Tesla was at 15 min after the administration of contrast agent (304.0+/-29.2 at 3.0 Tesla vs. 283.9+/-20.9 at 1.5 Tesla). The contrast between infarction and viable myocardium was equal at both field strengths (4.06+/-1.30 at 3.0 Tesla vs. 4.42+/-1.85 at 1.5 Tesla). Even at this early stage, MR viability imaging at 3.0 Tesla provides high quality images in patients with myocardial infarction. The inversion time is significantly prolonged at 3.0 Tesla. The contrast between infarction and viable myocardium at 3.0 Tesla are equal to 1.5 Tesla. Further investigation is needed for this technical improvement, for clinical evaluation, and for limitations.

Molecular Coronary MR Imaging of Human Thrombi using EP-2104R, a Fibrin-Targeted Contrast Agent: Experimental Study in a Swine Model

The aim of this study was to investigate the use of a fibrin-specific contrast agent (EP-2104R, EPIX Pharmaceuticals, Lexington, Massachusetts, USA) for targeted molecular magnetic resonance (MR) imaging of human clot material removed from patients in a model of coronary thrombosis in swine. Freshly ex vivo engineered clots from human blood and human in situ developed clots removed from patients were delivered into the coronary arteries of nine domestic swine. For MR imaging a navigator-gated, free-breathing, cardiac-triggered 3D inversion recovery black-blood gradient echo sequence was performed prior to clot delivery (baseline), after clot delivery but prior to contrast media administration, and two hours after systemic (i.v.) injection of 4 micromol/kg EP-2104R. MR images were analyzed by two investigators and the contrast-to-noise ratio and Gadolinium (Gd) concentration in the clots were assessed. On baseline images and prior to contrast media application no thrombi were visible. Post contrast administration all 10 coronary emboli (five ex vivo engineered clots and five human clots removed from patients) were selectively visualized as white spots with a mean contrast-to-noise ratio to the blood pool and the surrounding tissue of >12 and a mean Gd concentration of >100 microM. Molecular MR imaging using the fibrin-targeted contrast agent EP-2104R allows selective visualization of human clot material in a model of coronary thrombosis in swine.

Abstract 1835: Magnetic Resonance Imaging Detects Chronic Left Atrial Wall Injury Post Ablation of Atrial Fibrillation

Radiofrequency (RF) based ablation of atrial fibrillation (AF) through pulmonary vein antrum isolation (PVAI) is a promising treatment for this arrhythmia. Success of the procedure relies in part on the transmural extent of the RF lesions delivered to the left atrium (LA). We describe a novel technique using a 3D MRI to assess sites and extent of LA injury resulting from RF lesions after PVAI. Twelve patients (7 men, mean age 56±11 years) undergoing PVAI for AF were imaged pre and three months post procedure to detect LA scarring with delayed contrast-enhanced MRI using a 3D inversion recovery, navigated, gradient echo pulse sequence. LA injury post procedure was seen in all patients on MRI as areas of bright, signal enhancement, which correlated with the RF energy delivery map during PVAI (figure 1 ). Conclusion: This is the first study to show LA wall injury post PVAI using 3D MRI. These findings may prove important for tracking and monitoring outcomes of AF ablation. Figure 1. Posterior views of the left atrial wall in a patient one day pre (left) and three months post (right) ablation by delayed contrast-enhanced, navigated, 3D MRI. Regions of bright signal show injury resulting from RF ablation.

Assessment of Late Gadolinium Enhancement in Nonischemic Cardiomyopathy

Reliable detection of myocardial scarring in nonischemic cardiomyopathy is time-consuming using techniques that require determination of optimal inversion time. Therefore we evaluated an inversion-time-insensitive approach using a fast phase-sensitive inversion recovery (PSIR) sequence to detect and quantify late gadolinium enhancement (LGE). Twenty patients (mean age 40 years, 9 females) with nonischemic cardiomyopathy and evidence of LGE were evaluated. After administration of 0.2 mmol/kg gadolinium diethylene triamine pentaacetic acid, a segmented 2D inversion recovery turbo fast low-angle shot gradient echo recall (GRE) sequence [echo time (TE) 4.3 milliseconds, repetition time (TR) 750 milliseconds, alpha 30 degrees , voxel size 1.7 x 1.3 x 8-10 mm] was obtained and served as the standard of reference. Second, a fast multislice single-shot 2D PSIR sequence (TE 1.1 millisecond, TR 700 milliseconds, alpha 40 degrees , voxel size 2.5 x 1.7 x 8-10 mm) was acquired in the same slice positions. The PSIR(IR) images were used to analyze LGE. Altogether 53 short-axis slices with LGE were evaluated. Contrast-to-noise ratio and area of LGE were calculated and compared by 2 experienced readers. Image quality and confidence level for identification of LGE were rated on 5-point scales. Interobserver variability was evaluated in 10 patients. All images were interpretable. Imaging time was reduced from 385 +/- 127 seconds to 20 +/- 3 seconds (P < 0.001). Contrast-to-noise ratio was 8.29 for PSIRmag and 12.07 for the conventional GRE images (P < 0.001). The mean area of LGE was 1.01 +/- 0.62 cm(2) for the GRE sequence and 1.10 +/- 0.62 cm(2) for PSIR(IR) (P = NS). The general linear model showed no interaction between the results and no significant difference of the mean (r = 0.09, mean difference 0.09 cm(2)). The overall interobserver variability of PSIR(IR) and GRE was excellent, with Pearson's correlation coefficients of r = 0.96 for PSIR(IR) and r = 0.98 for GRE. PSIR(IR) and conventional GRE were comparable in terms of image quality and confidence level (image quality: 1.6 +/- 0.67 vs. 1.5 +/- 0.93, P = NS; confidence level: 1.4 +/- 0.84 vs. 1.3 +/- 0.5; P = NS). Fast PSIR sequences enable accurate detection and quantification of LGE in nonischemic cardiomyopathies. The examination time can be significantly shortened using the single-shot approach of the PSIR technique.

Inversion recovery prepared turbo spin echo sequences with reduced SAR using smooth transitions between pseudo steady states

This study investigates the contrast behavior of 2D inversion recovery (IR) prepared turbo spin echo (TSE) sequences that use RF pulse schemes with variable low flip angles (hyperTSE) to reduce RF power deposition. A framework of equations and calculations for adapting the sequence parameters is presented by which equivalent image contrast is achieved compared to conventional IR-TSE imaging. Although the inversion time (TI) and repetition time (TR) do not need to be changed, the echo time (TE) has to be prolonged such that the effective TE (TE(eff)) is preserved. Measurements in healthy volunteers confirmed this finding for IR-TSE sequences using different TIs: fluid attenuated inversion recovery (FLAIR), gray matter (GM)-white matter (WM)-IR, and short tau IR (STIR). The results demonstrate that hyperTSE sequences enable high-quality IR-prepared imaging with a considerably reduced specific absorption rate (SAR).

Optimized System Design and Construction of a Compact Whole-hand Scanner for Diagnosis of Rheumatoid Arthritis

We have developed a compact magnetic resonance (MR) imaging scanner with permanent magnet, gradient coil set, and radiofrequency (RF) coils optimized for whole-hand examination for the diagnosis of rheumatoid arthritis (RA). The system weighs about 600 kg, and installation space is 2 m(2), excluding the shield room. Hand examinations of normal volunteers and patients with RA were performed using a 3D T(1)-weighted gradient-echo (GRE) sequence and short T(I) inversion recovery 3D fast spin-echo (STIR-3DFSE) sequence, and anatomical structures and various lesions of the hand caused by RA were clearly visualized in a 16-min examination. It was concluded that the system could be used for diagnosis of RA in even a small clinic.

Comparison between intravenous and intraarterial contrast injections for dynamic 3D MRI of liver tumors in the VX2 rabbit model

To test the hypothesis that catheter-directed intraarterial (IA) contrast agent injection increases tumor enhancement and conspicuity compared to intravenous (IV) injection. Eight VX2 liver tumors were grown in five rabbits. After positioning a catheter in the hepatic artery, we performed 3D inversion recovery GRE MRI after IA and IV gadopentetate-dimeglumine contrast injections at doses of 0.04 and 0.1 mmol/kg, respectively. Peak enhancement (signal-to-noise ratio (SNR)) and conspicuity (contrast-to-noise ratio (CNR)) were measured for each acquisition. The peak SNR and CNR were 21.7 +/- 5.8 and 17.0 +/- 4.8 (mean +/- SD) after IA injection, and 16.9 +/- 10.2 and 6.2 +/- 2.6 after IV injection. The IA CNR was significantly greater than the IV CNR (P < 0.05), with a >60% increase in CNR for each tumor. For six of the eight tumors the IA SNR was greater than the IV SNR, but statistical significance was not achieved due to the small sample size of the study (P = 0.07). We demonstrated the feasibility of using IA injection techniques to improve tumor conspicuity. This strategy could be employed to enhance the detection of small liver tumors or to conserve contrast agent in future MRI-guided transcatheter liver therapies.

Single-Shot Inversion Recovery TrueFISP for Assessment of Myocardial Infarction

The aim of the study was to assess the diagnostic accuracy of imaging the myocardium with a fast multislice inversion recovery 2D single-shot true fast imaging with steady-state precession (trueFISP) sequence during a single breath-hold in comparison with an established segmented inversion recovery turbo fast low-angle shot (turboFLASH) sequence. Forty-three patients with myocardial infarction were examined on a 1.5-T MR system 10 min after administration of contrast material (gadodiamide, 0.2 mmol/kg) with a single-shot 2D multislice technique (single-shot inversion recovery trueFISP) that allows one to image the entire short axis during one breath-hold (18 heartbeats) and with a segmented 2D single-slice technique (inversion recovery turboFLASH) that requires one breath-hold per slice (12 heartbeats). Signal intensity was determined in normal myocardium, in infarcted myocardium, and in the left ventricle. The contrast-to-noise ratio (CNR) of normal and infarcted myocardium was determined. The areas of hyperintense infarctions on selected slices and the entire volumes were compared for both sequence techniques. The inversion recovery trueFISP sequence has a lower CNR than the inversion recovery turboFLASH sequence (mean values, 10.0 vs 12.9, respectively; p = 0.005) for differentiation of viable from nonviable myocardium. The CNR of injured myocardium and blood in the left ventricular cavity also has a lower value for the multislice technique compared with the single-slice technique (0.6 vs 1.2, respectively; p = 0.045). Assessment of the area of infarction within one slice (r = 0.97, p < 0.002) and of the volume of the entire infarction (r = 0.96, p < 0.003) is possible with excellent correlation of both techniques. Despite having a lower CNR, the inversion recovery 2D single-shot trueFISP sequence allows fast and accurate identification of the area and volume of infarction with high spatial resolution within a single breath-hold.

MR-Koronarangiographie mit MS-325, einem Blood-Pool-Kontrastmittel: Vergleich einer Inversion Recovery Steady-State Free Precession und einer Inversion Recovery Fast Low Angle Shot Sequenz in Probanden

To compare the signal-to-noise and contrast-to-noise ratio as well as the image quality of 3D inversion recovery steady-state free precession (IR-SSFP) and 3D inversion recovery fast low angle shot (IR-FLASH) sequences for contrast-enhanced breath-hold MRCA. 24 healthy volunteers (10 female, 14 male, mean age 29.8 +/- 6.1 years) were involved in this study. All examinations were performed on a 1.5 T MR scanner (Magnetom Sonata, Siemens, Germany) after injection of 0.05 mmol/kg body weight MS-325 (EPIX Pharmaceuticals, Cambridge, MA and Schering AG, Berlin, Germany). MRCA was performed using IR-SSFP (TR 3.8 ms, TE 1.6 ms, FA 65 degrees , 35 phase encoded steps, bandwidth 540 Hz/pixel, slice thickness 1.5 mm, in-plane resolution 1.2 x 0.9 - 1.4 x 1.0 mm) and IR-FLASH (TR 3.8 ms, TE 1.6 ms, FA 25 degrees , bandwidth 490 Hz/pixel, slice thickness 1.5 mm, in-plane resolution 1.2 x 0.9 - 1.4 x 1.0 mm) sequences. For all scans the inversion time was set to null the signal intensity of the myocardium. Signal-to-noise ratio (SNR) as well as contrast-to-noise ratio (CNR) measurements (blood versus myocardium) were performed. The image quality was assessed based on a 5-point scale ranging from 1 (excellent) to 5 (non-diagnostic) by two radiologists in consensus. The mean signal-to-noise ratio of blood (27.7 +/- 4.7 vs. 22.6 +/- 4.9, P < 0.0001) and the contrast-to-noise ratio (21.0 +/- 4.3 vs. 15.8 +/- 4.3, P < 0.0001) showed significantly higher values for IR-SSFP sequences. The mean image quality scores were significantly higher for SSFP (3.6 +/- 0.7) than FLASH (2.8 +/- 0.9) sequences (P < 0.05). IR-SSFP sequences show a considerable overall improvement in image quality compared to IR-FLASH sequences for MRCA after injection of a gadolinium-based blood pool contrast agent.