Improved Single Breath-Hold SSFSE Sequence for Liver MRI Based on Compressed Sensing: Evaluation of Image Quality Compared with Conventional T2-Weighted Sequences.

The purpose of this study was to evaluate the image quality of compressed-sensing accelerated single-shot fast spin-echo (SSFSECS) sequences acquired within a single breath-hold in comparison with conventional SSFSE (SSFSECONV) and multishot TSE (mTSE). A total of 101 patients who underwent liver MRI at 3 T, including SSFSECONV (acquisition time (TA) = 58−62 s), mTSE (TA = 108 s), and SSFSECS (TA = 18 s), were included in this retrospective study. Two radiologists assessed the three sequences with respect to artifacts, organ sharpness, small structure visibility, overall image quality, and conspicuity of main lesions of liver and pancreas using a five-point evaluation scale system. Descriptive statistics and the Wilcoxon signed-rank test were used for statistical analysis. SSFSECS was significantly better than SSFSECONV and mTSE for artifacts, small structure visibility, overall image quality, and conspicuity of main lesions (p < 0.005). Regarding organ sharpness, mTSE and SSFSECS did not significantly differ (p = 0.554). Conspicuity of liver lesion did not significantly differ between SSFSECONV and mTSE (p = 0.404). SSFSECS showed superior image quality compared with SSFSECONV and mTSE despite a more than three-fold reduction in TA, suggesting a remarkable potential for saving time in liver imaging.

Accelerated Stack-of-Spirals Free-Breathing Three-Dimensional Ultrashort Echo Time Lung Magnetic Resonance Imaging: A Feasibility Study in Patients With Breast Cancer.

PURPOSE: To investigate the clinical feasibility of accelerated free-breathing stack-of-spirals (spiral) three-dimensional (3D) ultrashort echo time (UTE) lung magnetic resonance imaging (MRI) using iterative self-consistent parallel imaging reconstruction from arbitrary k-space (SPIRiT) algorithm in patients with breast cancer. METHODS: The institutional review board approved this prospective study and patients' informed consents were obtained. Between June and August 2018, 29 female patients with breast cancer underwent 3-T MRI including accelerated free-breathing spiral 3D UTE (0.98-mm isotropic spatial resolution; echo time, 0.05 msec) of the lungs and thin-section chest computed tomography (CT). Two radiologists evaluated the image quality and pulmonary nodules on MRI were assessed and compared, CT as a reference. RESULTS: The pulmonary vessels and bronchi were visible consistently up to the sub-sub-segmental and sub-segmental branch levels, respectively, on accelerated spiral 3D UTE. The overall image quality was evaluated as good and excellent for 70.7% of accelerated spiral 3D UTE images (reviewer [R]1, 72.4% [21/29]; R2, 69.0% [20/29]) and acceptable for 20.7% (both R1 and R2, 20.7% [6/29]). Five patients on CT revealed 141 pulmonary metastatic nodules (5.3 ± 2.6 mm); the overall nodule detection rate of accelerated spiral 3D UTE was sensitivity of 90.8% (128/141), accuracy of 87.7%, and positive predictive value of 96.2%. In the Bland-Altman plot analysis comparing nodule size between CT and MRI, 132/141 nodules (93.6%) were inside the limits of agreement. CONCLUSION: Accelerated free-breathing spiral 3D UTE using the SPIRiT algorithm could be a potential alternative to CT for oncology patients.

Free-Breathing Motion-Corrected Single-Shot Phase-Sensitive Inversion Recovery Late-Gadolinium-Enhancement Imaging: A Prospective Study of Image Quality in Patients with Hypertrophic Cardiomyopathy.

OBJECTIVE: Motion-corrected averaging with a single-shot technique was introduced for faster acquisition of late-gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging while free-breathing. We aimed to evaluate the image quality (IQ) of free-breathing motion-corrected single-shot LGE (moco-ss-LGE) in patients with hypertrophic cardiomyopathy (HCM). MATERIALS AND METHODS: Between April and December 2019, 30 patients (23 men; median age, 48.5; interquartile range [IQR], 36.5-61.3) with HCM were prospectively enrolled. Breath-held single-shot LGE (bh-ss-LGE) and free-breathing moco-ss-LGE images were acquired in random order on a 3T MR system. Semi-quantitative IQ scores, contrast-to-noise ratios (CNRs), and quantitative size of myocardial scar were assessed on pairs of bh-ss-LGE and moco-ss-LGE. The mean ± standard deviation of the parameters was obtained. The results were compared using the Wilcoxon signed-rank test. RESULTS: The moco-ss-LGE images had better IQ scores than the bh-ss-LGE images (4.55 ± 0.55 vs. 3.68 ± 0.45, p < 0.001). The CNR of the scar to the remote myocardium (34.46 ± 11.85 vs. 26.13 ± 10.04, p < 0.001), scar to left ventricle (LV) cavity (13.09 ± 7.95 vs. 9.84 ± 6.65, p = 0.030), and LV cavity to remote myocardium (33.12 ± 15.53 vs. 22.69 ± 11.27, p < 0.001) were consistently greater for moco-ss-LGE images than for bh-ss-LGE images. Measurements of scar size did not differ significantly between LGE pairs using the following three different quantification methods: 1) full width at half-maximum method; 23.84 ± 12.88% vs. 24.05 ± 12.81% (p = 0.820), 2) 6-standard deviation method, 15.14 ± 10.78% vs. 15.99 ± 10.99% (p = 0.186), and 3) 3-standard deviation method; 36.51 ± 17.60% vs. 37.50 ± 17.90% (p = 0.785). CONCLUSION: Motion-corrected averaging may allow for superior IQ and CNRs with free-breathing in single-shot LGE imaging, with a herald of free-breathing moco-ss-LGE as the scar imaging technique of choice for clinical practice.

Optimized Breath-Hold Compressed-Sensing 3D MR Cholangiopancreatography at 3T: Image Quality Analysis and Clinical Feasibility Assessment.

Magnetic resonance cholangiopancreatography (MRCP) has been widely used in clinical practice, and recently developed compressed-sensing accelerated MRCP (CS-MRCP) has shown great potential in shortening the acquisition time. The purpose of this prospective study was to evaluate the clinical feasibility and image quality of optimized breath-hold CS-MRCP (BH-CS-MRCP) and conventional navigator-triggered MRCP. Data from 124 consecutive patients with suspected pancreaticobiliary diseases were analyzed by two radiologists using a five-point Likert-type scale. Communication between a cyst and the pancreatic duct (PD) was analyzed. Signal-to-noise ratio (SNR) of the common bile duct (CBD), contrast ratio between the CBD and periductal tissue, and contrast-to-noise ratio (CNR) of the CBD and liver were measured. Optimized BH-CS-MRCP showed significantly fewer artifacts with better background suppression and overall image quality. Optimized BH-CS-MRCP demonstrated communication between a cyst and the PD better than conventional MRCP (96.7% vs. 76.7%, p = 0.048). SNR, contrast ratio, and CNR were significantly higher with optimized BH-CS-MRCP (p < 0.001). Optimized BH-CS-MRCP showed comparable or even better image quality than conventional MRCP, with improved visualization of communication between a cyst and the PD.

Intra-individual comparison of conventional and simultaneous multislice-accelerated diffusion-weighted imaging in upper abdominal solid organs: value of ADC normalization using the spleen as a reference organ.

PURPOSE: To compare the apparent diffusion coefficient (ADC) value of conventional diffusion-weighted imaging (cDWI) to simultaneous multislice-accelerated DWI (sDWI) and to evaluate the possibility of ADC normalization using the spleen as a reference organ. METHODS: We retrospectively evaluated 92 patients (68 men, 24 women; mean age 60.0 years) who underwent liver magnetic resonance imaging (MRI) including both cDWI and sDWI. sDWI was obtained with an acceleration factor of 2. ADC values were measured from the right liver lobe, left liver lobe, spleen, pancreas, right kidney, and left kidney. ADC values of the spleen were used for normalization. Paired sample t test, Pearson's correlation coefficient, and Bland-Altman method were used for statistical analysis. RESULTS: ADC values of cDWI were significantly lower than sDWI in all six anatomic regions (p < 0.001). The mean difference in ADC value between cDWI and sDWI ranged from 0.048 to 0.125 × 10-3 mm2/s. ADC values from cDWI and sDWI showed a moderate to very high positive correlation (p < 0.001). After ADC normalization using the spleen as a reference organ, there was no significant difference between normalized ADC of cDWI and sDWI in all 5 anatomic regions (p = 0.11 - 0.74). CONCLUSIONS: Normalization of ADC using the spleen could be useful for comparing upper abdominal organs acquired with either cDWI or sDWI in longitudinal and follow-up studies.

Differentiation of multiple myeloma and metastases: Use of axial diffusion-weighted MR imaging in addition to standard MR imaging at 3T.

BACKGROUND: Metastasis and multiple myeloma are common malignant bone marrow lesions which may be difficult to distinguish because of similar imaging findings. The purpose of this study was to determine the value of adding diffusion-weighted imaging (DWI) to standard MR imaging to differentiate multiple myeloma from metastasis. METHODS: 25 patients with metastasis and 18 patients with multiple myeloma underwent 3T MR imaging with DWI (b = 0, 800 s/mm2) were enrolled. They all had pathologically confirmed bone lesions and were in a treatment naïve state. Two readers who were blind of final diagnosis measured the average ADC (ADCav) and minimum ADC (ADCmin) on the DWI. They then estimated the diagnosis, based on the standard MR imaging and measured ADC values. Another reader performed histogram analysis on the whole tumor volume and obtained mean ADC (ADCvol), standard deviation (SDvol), skewness, and kurtosis. Comparison of the obtained values from DWI was performed by the t-test or Mann-Whitney U test. The receiver operating characteristic (ROC) curve with areas under the curve (AUC) was used to obtain the cut off values and to evaluate the diagnostic performance of the two readers. RESULTS: ADCav, ADCmin, and ADCvol of multiple myeloma were significantly lower than those of metastasis: ADCav, 752 µm2/sec versus 1081 µm2/sec; ADCmin, 704 µm2/sec vs 835 µm2/sec; ADCvol 761 µm2/sec vs 1184 µm2/sec (p < .001). In histogram analysis, ADC values of multiple myeloma showed narrow distribution than metastasis: SDvol, 144 vs 257 (p < .001). Areas under the receiver operating characteristic curve was significantly higher with additive DWI than standard MR alone: 0.762 vs 0.953; 0.706 vs 0.950 (p < .05) for two readers. CONCLUSIONS: This study suggested that the addition of axial DWI to standard MR imaging can be helpful to diagnose multiple myeloma from metastasis at 3T.

Free-breathing ultrashort echo time lung magnetic resonance imaging using stack-of-spirals acquisition: A feasibility study in oncology patients.

OBJECTIVES: To investigate the diagnostic accuracy of lung magnetic resonance imaging (MRI) with a free-breathing three-dimensional ultrashort echo time spoiled gradient echo sequence using a stack-of-spirals acquisition (spiral 3D UTE) for pulmonary nodule detection at 3 T in oncology patients. METHODS: The institutional review board approved this retrospective study. Between June and September of 2017, 32 oncology patients underwent both free-breathing spiral 3D UTE of the lungs and thin-section chest computed tomography (CT) for pulmonary metastasis workups. Semiquantitative analyses of the visible pulmonary vessels, bronchi, mediastinum, and overall image quality on spiral 3D UTE were assessed by two reviewers; CT was used as the reference standard. The probability of nodule presence also was assessed. RESULTS: The mean acquisition duration of the spiral 3D UTE was 327 s (range, 300-465 s). The pulmonary vessels and bronchi were visible nearly consistently up to the sub-sub-segmental branch levels on spiral 3D UTE (96.9% [31/32] and 90.6% [29/32], respectively). >90% of the spiral 3D UTE images had an acceptable or good mediastinal evaluation; >80% had good or excellent overall image quality. Fifty nodules (6.1 ±â€¯5.9 mm) were identified in 13 patients on CT; the overall nodule detection rate of spiral 3D UTE was 86% (43/50). All 20 nodules ≥ 5 mm in diameter were identified on spiral 3D UTE (100%). CONCLUSIONS: Free-breathing spiral 3D UTE had high sensitivity for the detection of pulmonary nodules, a reasonable scan duration, and acceptable image quality, which may make it a potential alternative to CT for oncology patients.

Intravoxel incoherent motion diffusion-weighted MR imaging for differentiation of benign and malignant musculoskeletal tumours at 3 T.

OBJECTIVE: To evaluate the intravoxel incoherent motion (IVIM) diffusion-weighted (DW) MRI for differentiating between benign and malignant musculoskeletal tumours at 3 T. METHODS: 65 patients with treatment-naïve musculoskeletal tumours (47 malignant and 23 benign lesions) who underwent 3 T MRI including IVIM DW imaging were included. IVIM-derived parameters included pure diffusion coefficient (D), perfusion related incoherent microcirculation (D*, pseudodiffusion coefficient), and perfusion fraction (f). IVIM parameters and mono-exponential apparent diffusion coefficient (ADC) were retrospectively measured by two independent musculoskeletal radiologists. RESULTS: D and ADC values of malignant tumours (923 ± 360, 965 ± 353 µm2 s-1, respectively) were significantly lower than those of benign tumours (1668 ± 546, 1689 ± 526 µm2 s-1) (p < 0.001). F values of malignant tumours (9.6%) were significantly higher than those of benign tumours (7.2%) (p = 0.021), whereas D* values showed no significant difference (p > 0.05). The area under the receiver operating characteristic (ROC) curve of D, ADC and f were 0.874, 0.880 and 0.671, respectively. Using cut-off values of D and ADC of 1200 µm2 s-1, the sensitivity, specificity and accuracy were 92, 83, 89%, 92, 87 and 90%, respectively. CONCLUSION: D and ADC may be more accurate and reliable for differentiation of malignant from benign musculoskeletal tumours than f and D* at 3 T IVIM DW imaging. Advances in knowledge: Among IVIM-derived parameters, D is more accurate and reliable in differentiating malignant from benign musculoskeletal tumours than f and D* at 3.0T IVIM DW imaging. There was no significant difference in the diagnostic performance of D and ADC.

Early Detection and Serial Monitoring of Anthracycline-Induced Cardiotoxicity Using T1-mapping Cardiac Magnetic Resonance Imaging: An Animal Study.

A reliable, non-invasive diagnostic method is needed for early detection and serial monitoring of cardiotoxicity, a well-known side effect of chemotherapy. This study aimed to assess the feasibility of T1-mapping cardiac magnetic resonance imaging (CMR) for evaluating subclinical myocardial changes in a doxorubicin-induced cardiotoxicity rabbit model. Adult male New Zealand White rabbits were injected twice-weekly with doxorubicin and subjected to CMR on a clinical 3T MR system before and every 2-4 weeks post-drug administration. Native T1 and extracellular volume (ECV) values were measured at six mid-left ventricle (LV) and specific LV lesions. Histological assessments evaluated myocardial injury and fibrosis. Three pre-model and 11 post-model animals were included. Myocardial injury was observed from 3 weeks. Mean LV myocardium ECV values increased significantly from week 3 before LV ejection fraction decreases (week 6), and ECVs of the RV upper/lower insertion sites and papillary muscle exceeded those of the LV. The mean native T1 value in the mid-LV increased significantly increased from week 6, and LV myocardium ECV correlated strongly with the degree of fibrosis (r = 0.979, p < 0.001). Myocardial T1 mapping, particularly ECV values, reliably and non-invasively detected early cardiotoxicity, allowing serial monitoring of chemotherapy-induced cardiotoxicity.

Myocardial Characterization Using Dual-Energy CT in Doxorubicin-Induced DCM: Comparison With CMR T1-Mapping and Histology in a Rabbit Model.

OBJECTIVES: This study sought to evaluate whether patterns of myocardial change in doxorubicin-induced dilated cardiomyopathy determined using dual-energy computed tomography (CT) were similar to characterization by extracellular volume fraction (ECV) using cardiac magnetic resonance (CMR) T1-mapping and collagen volume fraction (CVF) measured using histology. BACKGROUND: Anthracycline chemoagents are effective against a wide range of malignant conditions. However, cardiotoxicity is a well-known adverse effect of these drugs. Dual-energy CT could be as useful as magnetic resonance (MR) to evaluate myocardial change in anthracycline-induced cardiotoxicity. METHODS: A dilated cardiomyopathy rabbit model was generated by injecting 11 adult New Zealand rabbits with 1.0 mg/kg of doxorubicin twice weekly for 16 weeks. Contrast-enhanced dual-energy CT and pre-contrast and post-contrast T1-mapping CMR using a prototype modified Look-Locker inversion recovery on a clinical 3-T scanner were performed on 15 rabbits, including 4 control animals, to calculate ECV at baseline, and at 6, 12, and 16 weeks after doxorubicin administration. RESULTS: The mean ECV values (%) on CT and CMR at 6, 12, and 16 weeks after modeling were significantly higher than those measured at baseline (CT ECV: 35.3%, 41.9%, 42.1% vs. 28.5%; MR ECV: 32.6%, 35.8%, 41.3% vs. 28.8%, respectively; all p < 0.001). CT ECV and MR ECV values were well correlated (r = 0.888; p < 0.001). Both were well correlated with CVF on histology (CT ECV vs. CVF, r = 0.925, p < 0.001 and MR ECV vs. CVF, r = 0.961, p < 0.001, respectively). CONCLUSIONS: Dual-energy CT ECV correlated well with CMR and histology. Dual-energy CT is useful for characterizing doxorubicin-induced cardiomyopathy by measuring ECV fraction; however, further technical improvements are desirable to lower motion artifact and improve image quality of the iodine map.

Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle.

OBJECTIVE: To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. MATERIALS AND METHODS: Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. RESULTS: A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. CONCLUSION: T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.

Quantitative T2 mapping after reperfusion therapy in patients with acute myocardial infarction: A comparison with late gadolinium enhancement and cine MR imaging.

PURPOSE: This study evaluates myocardial edema by quantitative T2 mapping in patients with acute myocardial infarction (AMI) and compares the lateral extent of myocardial edema with those of infarcted and dysfunctional myocardium. MATERIALS AND METHODS: Cardiac magnetic resonance images (MRIs) of 31 patients (M:F=29:2, mean age: 52.5±10.8years) with AMI were reviewed. On cine-MRI, all short axis images of the left ventricle (LV) were divided into 60 sectors. The regional wall motion of each sector was calculated as follows: systolic wall thickening (SWT, %)=[(LV wall thicknessES-LV wall thicknessED)/LV wall thicknessED]*100. Dysfunctional myocardium was defined as sectors with decreased SWT lower than 40%. On LGE-images, myocardial infarction was defined as an area of hyper-enhancement more than 5 SDs from the remote myocardium. On T2 map, myocardial edema was defined as an area in which T2 values were at least 2 SDs higher than those from remote myocardium. The lateral extents of infarcted myocardium, myocardial edema, and dysfunctional myocardium were calculated as the percentage of central angles ((central angle of the involved myocardium/360)*100 (%)) and then compared. RESULTS: The lateral extent of myocardial edema was slightly larger than that of infarcted myocardium (37.4±13.3% vs. 35±12.9%, p<0.01). The lateral extent of dysfunctional myocardium (50.6±15.3%) was significantly larger than that of infarcted myocardium or myocardial edema (p<0.001). CONCLUSIONS: The lateral extent of myocardial edema beyond the infarcted myocardium might be narrow, but the dysfunctional myocardium could be significantly larger than myocardial edema, suggesting stunned myocardium without edema.

Extracellular volume fraction in dilated cardiomyopathy patients without obvious late gadolinium enhancement: comparison with healthy control subjects.

To evaluate whether the extracellular volume fraction (ECV) measured using cardiac magnetic resonance (CMR) imaging can detect myocardial tissue changes in dilated cardiomyopathy (DCM) without late gadolinium enhancement (LGE). Forty-one DCM patients and 10 healthy volunteers underwent pre- and post-T1 mapping using a modified Look-Locker Inversion recovery sequence, LGE, and cine MRI on a 3-T CMR system. LGE-MR findings were used to divide DCM patients into two groups: Group A had no apparent LGE, and Group B had LGE apparent in at least one segment. The ECV of the left ventricle (LV) myocardium (16 segments) was calculated in the short-axis view as follows: ECV = [(ΔR1 of myocardium/ΔR1 of LV blood pool)] × (1 - hematocrit), where R1 = 1/T1, ΔR1 = post-contrast R1 - pre-contrast R1. The LV ejection fraction (LVEF) was obtained from cine MRI images. The mean myocardial ECV in LGE (-) segments in Group A + B was compared to that of controls. The mean myocardial ECV in Group A was compared to that of LGE (-) segments in Group B. The correlation between LV systolic function and the mean myocardial ECV of the whole myocardium was evaluated in all groups. Among the 41 DCM patients, 22 were in Group A, and 19 were in Group B. The mean ECV of DCM patents (n = 41, 568 segments, 30.7 % ± 5.9) was significantly higher (P < 0.001) than that of the control group (n = 10, 157 segments, 25.6 % ± 3.2). The ECV was inversely related to LVEF in Group A (r = -0.551, P = 0.008), Group B (r = -0.525, P = 0.021), and Group A + B (r = -0.550, P < 0.001). The ECV measured by MRI could be a useful parameter in evaluating diffuse myocardial changes in DCM patients.

Differentiation between focal malignant marrow-replacing lesions and benign red marrow deposition of the spine with T2*-corrected fat-signal fraction map using a three-echo volume interpolated breath-hold gradient echo Dixon sequence.

OBJECTIVE: To assess the feasibility of T2*-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. MATERIALS AND METHODS: We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. RESULTS: The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. CONCLUSION: Fat-signal fraction measurement using T2*-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.

Evaluation of extracellular volume fraction thresholds corresponding to myocardial late-gadolinium enhancement using cardiac magnetic resonance.

To establish extracellular volume fraction (ECV) thresholds corresponding to myocardial lesion detected by late-gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging. Fifty-six patients with myocardial infarction or hypertrophic cardiomyopathy underwent LGE, pre- and post-contrast modified Look-Locker inversion recovery (MOLLI) sequences on a 3-T CMR system. Short-axis MOLLI images generated ECV maps of left ventricular (LV) walls. The LGE areas were semi-automatically determined by different signal threshold techniques. The areas of elevated ECV were measured using ECV thresholds of 28-48%. The LGE areas were compared with the areas of elevated ECV at the corresponding LV levels. The myocardial areas of LGE and elevated ECVs showed a strong and positive correlation (P < 0.01). The LGE threshold, set at two standard deviations above the mean signal from the remote myocardium, corresponded well with the area of ECV >32%. When using the full width at half-maximum (FWHM) technique, the LGE area corresponded well with the area of ECV >42 or 44%. By applying particular ECV thresholds, myocardial ECV maps can define myocardial status equivalent to LGE, and definite ECV thresholds may be useful for the straightforward evaluation of myocardial phenotypes.

Diagnosis of acute global myocarditis using cardiac MRI with quantitative t1 and t2 mapping: case report and literature review.

The diagnosis of myocarditis can be challenging given that symptoms, clinical exam findings, electrocardiogram results, biomarkers, and echocardiogram results are often non-specific. Endocardial biopsy is an established method for diagnosing myocarditis, but carries the risk of complications and false negative results. Cardiac magnetic resonance imaging (MRI) has become the primary non-invasive imaging tool in patients with suspected myocarditis. Myocarditis can be diagnosed by using three tissue markers including edema, hyperemia/capillary leak, and necrosis/fibrosis. The interpretation of cardiac MR findings can be confusing, especially when the myocardium is diffusely involved. Using T1 and T2 maps, the diagnosis of myocarditis can be made even in cases of global myocarditis with the help of quantitative analysis. We herein describe a case of acute global myocarditis which was diagnosed by using quantitative T1 and T2 mapping.

Quantitative T2 mapping for detecting myocardial edema after reperfusion of myocardial infarction: validation and comparison with T2-weighted images.

This study evaluates the clinical usefulness of T2 mapping for the detection of myocardial edema in the re-perfused acute myocardial infarction (MI). Cardiac MRIs were reviewed in 20 patients who had acute MI after reperfusion therapy. The regional T2 values and T2-weighted image (T2WI) signal intensities (SI) were measured in the infarcted and remote zones of the myocardium. Patients were divided into three groups according to the signal patterns of the infarcted myocardium on the T2WIs. The T2 values of the infarcted zones were compared on the T2 maps among the three groups. Validation of the T2 values was performed in the normal myocardium of seven healthy volunteers. There were no significant differences in mean T2WI-SI or T2 values in the normal myocardium of healthy volunteers compared to the remote myocardium of acute MI patients (p > 0.05). Mean SI on the T2WIs was significantly higher in the infarcted myocardium (81.3 ± 37.6) than in the remote myocardium (63.8 ± 18.1) (p < 0.05). The T2WIs showed high SI in ten patients (group 1), iso-SI in seven (group 2), and low SI in three (group 3) in the infarcted myocardium, compared to the remote myocardium. The T2 maps showed that T2 values in the infarcted myocardium had mostly increased, regardless of group, with values of 71 ± 9 ms in group 1, 64.9 ± 7.4 ms in group 2, and 61.4 ± 8.5 ms in group 3. T2 mapping is superior to T2WI for detecting areas of high SI in the infarcted myocardium. Therefore, quantitative T2 mapping sequences may be more useful and reliable in identifying myocardial edema in the infarcted myocardium than T2WI.

Correction with blood T1 is essential when measuring post-contrast myocardial T1 value in patients with acute myocardial infarction.

BACKGROUND: Post-contrast T1 mapping by modified Look-Locker inversion recovery (MOLLI) sequence has been introduced as a promising means to assess an expansion of the extra-cellular space. However, T1 value in the myocardium can be affected by scanning time after bolus contrast injection. In this study, we investigated the changes of the T1 values according to multiple slicing over scanning time at 15 minutes after contrast injection and usefulness of blood T1 correction. METHODS: Eighteen reperfused acute myocardial infarction (AMI) patients, 13 cardiomyopathy patients and 8 healthy volunteers underwent cardiovascular magnetic resonance with 15 minute-post contrast MOLLI to generate T1 maps. In 10 cardiomyopathy cases, pre- and post-contrast MOLLI techniques were performed to generate extracellular volume fraction (Ve). Six slices of T1 maps according to the left ventricular (LV) short axis, from apex to base, were consecutively obtained. Each T1 value was measured in the whole myocardium, infarcted myocardium, non-infarcted myocardium and LV blood cavity. RESULTS: The mean T1 value of infarcted myocardium was significantly lower than that of non-infarcted myocardium (425.4 ± 68.1 ms vs. 540.5 ± 88.0 ms, respectively, p < 0.001). T1 values of non-infarcted myocardium increased significantly from apex to base (from 523.1 ± 99.5 ms to 561.1 ± 81.1 ms, p = 0.001), and were accompanied by a similar increase in blood T1 value in LV cavity (from 442.1 ± 120.7 ms to 456.8 ± 97.5 ms, p < 0.001) over time. This phenomenon was applied to both left anterior descending (LAD) territory (from 545.1 ± 74.5 ms to 575.7 ± 84.0 ms, p < 0.001) and non-LAD territory AMI cases (from 501.2 ± 124.5 ms to 549.5 ± 81.3 ms, p < 0.001). It was similarly applied to cardiomyopathy patients and healthy volunteers. After the myocardial T1 values, however, were adjusted by the blood T1 values, they were consistent throughout the slices from apex to base (from 1.17 ± 0.18 to 1.25 ± 0.13, p > 0.05). The Ve did not show significant differences from apical to basal slices. CONCLUSION: Post-contrast myocardial T1 corrected by blood T1 or Ve, provide more stable measurement of degree of fibrosis in non-infarcted myocardium in short- axis multiple slicing.