T2‐weighted MRI of post‐infarct myocardial edema in mice

T₂‐weighted, cardiac magnetic resonance imaging (T₂w CMR) can be used to noninvasively detect and quantify the edematous region that corresponds to the area at risk (AAR) following myocardial infarction (MI). Previously, CMR has been used to examine structure and function in mice, expediting the study of genetic manipulations. To date, CMR has not been applied to imaging of post‐MI AAR in mice. We developed a whole‐heart, T₂w CMR sequence to quantify the AAR in mouse models of ischemia and infarction. The ΔB₀ and ΔB₁ environment around the mouse heart at 7 T were measured, and a T₂‐preparation sequence suitable for these conditions was developed. Both in vivo T₂w and late gadolinium enhanced CMR were performed in mice after 20‐min coronary occlusions, resulting in measurements of AAR size of 32.5 ± 3.1 (mean ± SEM)% left ventricular mass, and MI size of 50.1 ± 6.4% AAR size. Excellent interobserver agreement and agreement with histology were also found. This T₂w imaging method for mice may allow for future investigations of genetic manipulations and novel therapies affecting the AAR and salvaged myocardium following reperfused MI. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

A new approach towards improved visualization of myocardial edema using T2-weighted imaging: a cardiovascular magnetic resonance (CMR) study

Purpose:

To compare T2‐weighted cardiovascular magnetic resonance (CMR) imaging with AASPIR (asymmetric adiabatic spectral inversion recovery) and STIR (short T1 inversion recovery) for myocardial signal intensity, image quality, and fat suppression.

Materials and Methods:

Forty consecutive patients (47 ± 16 years old) referred by cardiologists for CMR‐based myocardial tissue characterization were scanned with both STIR and AASPIR T2‐weighted imaging approaches. Signal intensity of left ventricular myocardium was normalized to a region of interest generating a signal‐to‐noise ratio (SNR). In six patients with regional edema on STIR the contrast‐to‐noise ratio (CNR) was assessed. Two independent observers used a scoring system to evaluate image quality and artifact suppression. Six healthy volunteers (three males, 32 ± 7 years) were recruited to compare fat suppression between AASPIR and STIR.

Results:

SNR of AASPIR was greater than STIR for basal (128 ± 44 vs. 83 ± 40, P < 0.001), mid‐ (144 ± 65 vs. 96 ± 39, P < 0.01), and apical (145 ± 59 vs. 105 ± 35, P < 0.05) myocardium. Improved image quality and greater suppression of artifacts was demonstrated with AASPIR. In patients with regional edema, CNR increased by 49% with AASPIR, while SNR of pericardial fat did not differ (44 ± 39 vs. 33 ± 30, P > 0.05).

Conclusion:

Our findings support the implementation of an AASPIR‐based approach for T2‐weighted imaging due to improved pericardial fat suppression, image quality, and artifact suppression with greater CNR and SNR. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Quantitative assessment of myocardial T2 relaxation times in cardiac amyloidosis

Purpose

To evaluate cardiac MRI (CMR) in the diagnosis of cardiac amyloidosis by comparing the T2 relaxation times of left ventricular myocardium in a pilot patient group to a normal range established in healthy controls.

Materials and Methods

Forty‐nine patients with suspected amyloidosis‐related cardiomyopathy underwent comprehensive CMR examination, which included assessment of myocardial T2 relaxation times, ventricular function, resting myocardial perfusion, and late gadolinium enhancement (LGE) imaging. T2‐weighted basal, mid, and apical left ventricular slices were acquired in each patient using a multislice T2 magnetization preparation spiral sequence. Slice averaged T2 relaxation times were subsequently calculated offline and compared to the previously established normal range.

Results

Twelve of the 49 patients were confirmed to have cardiac amyloidosis by biopsy. There was no difference in mean T2 relaxation times between the amyloid cases and normal controls (51.3 ± 8.1 vs. 52.1 ± 3.1 msec, P = 0.63). Eleven of the 12 amyloid patients had abnormal findings by CMR, eight having LGE involving either ventricles or atria and four demonstrating resting subendocardial perfusion defects.

Conclusion

CMR is a potentially valuable tool in the diagnosis of cardiac amyloidosis. However, calculation of myocardial T2 relaxation times does not appear useful in distinguishing areas of amyloid deposition from normal myocardium. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.     

Value of T2-weighted, first-pass and delayed enhancement, and cine CMR to differentiate between acute and chronic myocardial infarction

The aim of this study was to analyze the diagnostic accuracy of edema on T2-weighted (T2w) cardiac magnetic resonance imaging (CMR), presence of microvascular obstruction (MO) on first-pass enhancement (FPE) or on delayed enhancement (DE) CMR, and wall thinning on cine CMR to differentiate between acute (AMI) and chronic myocardial infarction (CMI) in patients with infarction on DE-CMR. Fifty patients were imaged 5 ± 3 days (baseline) and 8 ± 3 months (follow-up) after AMI at 1.5 T. Imaging findings were graded as present or absent in a blinded consensus reading. Edema was present at baseline in 48 (96%) patients and absent at follow-up in 49 (98%) patients. At baseline, MO was present in 29 (58%) patients on FPE-CMR and in 24 (48%) patients on DE-CMR (P  = ns). At follow-up, persisting hypoenhancement was observed in ten (20%) patients on FPE-CMR, whereas two (4%) patients showed persisting hypoenhancement on DE-CMR (P<0.05). Wall thinning was present in 4 (8%) patients at baseline and in 20 (40%) patients at follow-up. Edema had high sensitivity (96%), specificity (98%), and accuracy (97%) to differentiate between AMI and CMI. Accuracy of all other imaging findings was lower compared to that of edema (P<0.001). In the presence of infarction on DE-CMR, T2w-CMR reliably differentiates between AMI and CMI. This study was funded in part by the Pinguin-Stiftung, Düsseldorf, Germany and by the Schering Company, Berlin, Germany.     

Influence of myocardial fibrosis and blood oxygenation on heart T2* values in thalassemia patients

Purpose

To determine whether T2* measurements quantifying myocardial iron overload in thalassemia patients are influenced by myocardial fibrosis and blood oxygenation.

Materials and Methods

Multislice multiecho T2* was performed in 94 thalassemia patients in order to quantify myocardial iron overload. The left ventricle was automatically segmented into a 16‐segment standardized heart model, and the T2* value on each segment as well as the global T2* were calculated. Delayed enhanced cardiovascular magnetic resonance (DE‐CMR) images were obtained to detect myocardial fibrosis. The blood oxygenation was assessed by the noninvasive measurement of partial pressure of oxygen (pO2).

Results

Myocardial fibrosis was detected in 31 patients (33%). The global T2* value in patients with fibrosis was comparable with that of patients without fibrosis (P = 0.88) and T2* values in segments with fibrosis were comparable with those in segments without fibrosis (P = 0.83). The global T2* value was not correlated with the pO2 (Spearman's coefficient of correlation = 0.99).

Conclusion

Myocardial fibrosis and blood oxygenation did not significantly affect the T2* values. These data further support the use of heart T2* as equivalent of heart iron in the clinical arena. J. Magn. Reson. Imaging 2009;29:832–837. © 2009 Wiley‐Liss, Inc.     

Assessment of carotid stenosis using three-dimensional T2-weighted dark blood imaging: Initial experience

Purpose:

To evaluate the use of a T2‐weighted SPACE sequence (T2w‐SPACE) to assess carotid stenosis via several methods and compare its performance with contrast‐enhanced magnetic resonance angiography (ceMRA).

Materials and Methods:

Fifteen patients with carotid atherosclerosis underwent dark blood (DB)‐MRI using a 3D turbo spin echo with variable flip angles sequence (T2w‐SPACE) and ceMRA. Images were coregistered and evaluated by two observers. Comparisons were made for luminal diameter, luminal area, degree of luminal stenosis (NASCET: North American Symptomatic Endarterectomy Trial; ECST: European Carotid Surgery Trial, and area stenosis), and vessel wall area. Degree of NASCET stenosis was clinically classified as mild (<50%), moderate (50%–69%), or severe (>69%).

Results:

Excellent agreement was seen between ceMRA and T2w‐SPACE and between observers for assessment of lumen diameter, lumen area, vessel wall area, and degree of NASCET stenosis (r > 0.80, P < 0.001). ECST stenosis was consistently higher than NASCET stenosis (48 ± 14% vs. 24 ± 22%, P < 0.001). Area stenosis (72 ± 2%) was significantly higher (P < 0.001) than both ESCT and NASCET stenosis.

Conclusion:

DB‐MRI of carotid arteries using T2w‐SPACE is clinically feasible. It provides accurate measurements of lumen size and degree of stenosis in comparison with ceMRA and offers a more reproducible measure of ECST stenosis than ceMRA. J. Magn. Reson. Imaging 2012;449‐455. © 2011 Wiley Periodicals, Inc.     

T(2) -weighted STIR imaging of myocardial edema associated with ischemia-reperfusion injury: the influence of proton density effect on image contrast

Purpose

To investigate the contribution of proton density (PD) in T₂‐STIR based edema imaging in the setting of acute myocardial infarction (AMI).

Materials and Methods

Canines (n = 5), subjected to full occlusion of the left anterior descending artery for 3 hours, underwent serial magnetic resonance imaging (MRI) studies 2 hours postreperfusion (day 0) and on day 2. During each study, T₁ and T₂ maps, STIR (TE = 7.1 msec and 64 msec) and late gadolinium enhancement (LGE) images were acquired. Using T₁ and T₂ maps, relaxation and PD contributions to myocardial edema contrast (EC) in STIR images at both TEs were calculated.

Results

Edematous territories showed significant increase in PD (20.3 ± 14.3%, P < 0.05) relative to healthy territories. The contributions of T₁ changes and T₂ or PD changes toward EC were in opposite directions. One‐tailed t‐test confirmed that the mean T₂ and PD‐based EC at both TEs were greater than zero. EC from STIR images at TE = 7.1 msec was dominated by PD than T₂ effects (94.3 ± 11.3% vs. 17.6 ± 2.5%, P < 0.05), while at TE = 64 msec, T₂ effects were significantly greater than PD effects (90.8 ± 20.3% vs. 12.5 ± 11.9%, P < 0.05). The contribution from PD in standard STIR acquisitions (TE = 64 msec) was significantly higher than 0 (P < 0.05).

Conclusion

In addition to T₂‐weighting, edema detection in the setting of AMI with T₂‐weighted STIR imaging has a substantial contribution from PD changes, likely stemming from increased free‐water content within the affected tissue. This suggests that imaging approaches that take advantage of both PD as well as T₂ effects may provide the optimal sensitivity for detecting myocardial edema. J. Magn. Reson. Imaging 2011;33:962–967. © 2011 Wiley‐Liss, Inc.     

Myocardial T2 quantitation in patients with iron overload at 3 Tesla

Purpose

To investigate the feasibility of measuring myocardial T2 at 3 Tesla for assessment of tissue iron in thalassemia major and other iron overloaded patients.

Materials and Methods

A single‐breathhold electrocardiogram‐triggered black‐blood multi‐echo spin‐echo (MESE) sequence with a turbo factor of 2 was implemented at 3 Tesla (T). Myocardial and liver T2 values were measured with three repeated breathholds in 8 normal subjects and 24 patients. Their values, together with the T2* values measured using a breathhold multi‐echo gradient‐echo sequence, were compared with those at 1.5T in the same patients.

Results

At 3T, myocardial T2 was found to be 39.6 ± 7.4 ms in normal subjects. In patients, it ranged from 12.9 to 50.1 ms. T2 and T2* were observed to correlate in heart (ρ = 0.93, ρ < 0.0001) and liver (P = 0.95, P < 0.0001). Myocardial T2 and T2* at 3T were also highly correlated with the 1.5T measurements. Preliminary results indicated that myocardial T2 quantitation was relatively insensitive to B1 variation, and reproducible with 3.2% intra‐exam and 3.8% inter‐exam variations.

Conclusion

Myocardial T2 quantitation is feasible at 3T. Given the substantially decreased T2* and increased B0 inhomogeneity, the rapid myocardial T2 measurement protocol demonstrated here may present a robust alternative to study cardiac iron overload at 3T. J. Magn. Reson. Imaging 2009;30:394–400. © 2009 Wiley‐Liss, Inc.     

New look at renal vasculature: 7 tesla nonenhanced T1-weighted FLASH imaging

Purpose:

To investigate the feasibility of 7 Tesla (T) nonenhanced high field MR imaging of the renal vasculature and to evaluate the diagnostic potential of various nonenhanced T1‐weighted (T1w) sequences.

Materials and Methods:

Twelve healthy volunteers were examined on a 7T whole‐body MR system (Magnetom 7T, Siemens Healthcare Sector) using a custom‐built eight‐channel radiofrequency (RF) transmit/receive body coil. Subsequent to RF shimming, the following sequences were acquired (i) fat‐saturated two‐dimensional (2D) FLASH, (ii) fat‐saturated 3D FLASH, and a (iii) fat‐saturated 2D time‐of‐flight MR angiography (TOF MRA). SNR and CNR were measured in the aorta and both renal arteries. Qualitative analysis was performed with regard to vessel delineation (5‐point scale: 5 = excellent to 1 = nondiagnostic) and presence of artifacts (5‐point scale: 5 = no artifact present to 1 = strong impairment).

Results:

The inherently high signal intensity of the renal arterial vasculature in T1w imaging enabled moderate to excellent vessel delineation in all sequences. Qualitative (mean, 4.7) and quantitative analysis (SNR_mean: 53.9; CNR_mean: 28.0) demonstrated the superiority of TOF MRA, whereas 2D FLASH imaging provided poorest vessel delineation and was most strongly impaired by artifacts (overall impairment 3.7). The 3D FLASH MRI demonstrated its potential for fast high quality imaging of the nonenhanced arterial vasculature, providing homogeneous hyperintense vessel signal.

Conclusion:

Nonenhanced T1w imaging in general and, TOF MRA in particular, appear to be promising techniques for good quality nonenhanced renal artery assessment at 7 Tesla. J. Magn. Reson. Imaging 2012;36:714–721. © 2012 Wiley Periodicals, Inc.     

Fast T2*-weighted MRI of the prostate at 3 Tesla

Purpose:

To describe a rapid T2*‐weighted (T2*W), three‐dimensional (3D) echo planar imaging (EPI) sequence and its application in mapping local magnetic susceptibility variations in 3 Tesla (T) prostate MRI. To compare the sensitivity of T2*W EPI with routinely used T1‐weighted turbo‐spin echo sequence (T1W TSE) in detecting hemorrhage and the implications on sequences sensitive to field inhomogeneities such as MR spectroscopy (MRS).

Materials and Methods:

B₀ susceptibility weighted mapping was performed using a 3D EPI sequence featuring a 2D spatial excitation pulse with gradients of spiral k‐space trajectory. A series of 11 subjects were imaged using 3T MRI and combination endorectal (ER) and six‐channel phased array cardiac coils. T1W TSE and T2*W EPI sequences were analyzed quantitatively for hemorrhage contrast. Point resolved spectroscopy (PRESS MRS) was performed and data quality was analyzed.

Results:

Two types of susceptibility variation were identified: hemorrhagic and nonhemorrhagic T2*W‐positive areas. Post‐biopsy hemorrhage lesions showed on average five times greater contrast on the T2*W images than T1W TSE images. Six nonhemorrhage regions of severe susceptibility artifact were apparent on the T2*W images that were not seen on standard T1W or T2W images. All nonhemorrhagic susceptibility artifact regions demonstrated compromised spectral quality on 3D MRS.

Conclusion:

The fast T2*W EPI sequence identifies hemorrhagic and nonhemorrhagic areas of susceptibility variation that may be helpful in prostate MRI planning at 3.0T. J. Magn. Reson. Imaging 2011;33:902–907. © 2011 Wiley‐Liss, Inc.     

T1 and T2 mapping in the identification of acute myocardial injury in patients with NSTEMI

Aims

To test T1 and T2 mapping in the assessment of acute myocardial injury in patients with non-ST-segment elevation myocardial infarction (NSTEMI), evaluated before revascularization.

Methods

Forty-seven patients with acute NSTEMI underwent cardiac magnetic resonance (CMR) at 1.5 T, including T1 and T2 mapping.

Results

Coronary angiography (CA) evidenced an obstructive coronary artery disease (CAD) in 36 patients (80%) and a non-obstructive CAD in 11 patients (20%). Edema was detected in 51.1/65.9% of patients in T1/T2 maps, respectively. This difference was due to artifacts in T1 maps. T1/T2 values were significantly higher in the infarcted myocardium (IM) compared with the remote myocardium (RM) (in T1: 1151.6?±?53.5 ms vs. 958.2?±?38.6 ms, respectively; in T2: 69?±?6 ms vs. 51.9?±?2.9 ms, respectively; p?<?0.0001 for both). We found both an obstructive CAD at CA and myocardial edema at CMR in 53.2% of patients, while 8.5% of patients had a non-obstructive CAD and no edema. However, 25.5% of patients had an obstructive CAD without edema, while 12.8% of patients showed edema despite a non-obstructive CAD. Furthermore, in 6 of the edema-positive patients with multi-vessels obstructive CAD, CMR identified myocardial edema in a vascular territory different from that of the lesion supposed to be the culprit at CA.

Conclusions

In a non-negligible percentage of NSTEMI patients, T1 and T2 mapping detect myocardial edema without significant stenosis at CA and vice versa. Therefore, CA and CMR edema imaging might provide complementary information in the evaluation of NSTEMI.

     

Left ventricular diastolic function in type 2 diabetes mellitus is associated with myocardial triglyceride content but not with impaired myocardial perfusion reserve

Purpose:

To study myocardial perfusion reserve and myocellular metabolic alterations indicated by triglyceride content as possible causes of diastolic dysfunction in patients with type 2 diabetes mellitus, preserved systolic function, and without clinically evident coronary artery disease.

Materials and Methods:

Patients with type 2 diabetes mellitus (n = 42) underwent cardiac magnetic resonance (CMR) for quantification of 1) myocardial contractility by strain‐encoded MR (SENC); 2) myocardial triglyceride content by proton magnetic resonance spectroscopy (¹H‐MRS); and 3) myocardial perfusion reserve during pharmacologic hyperemia. Age‐matched healthy volunteers (n = 16) also underwent CMR to acquire normal values for myocardial strain and perfusion reserve.

Results:

Stress CMR procedures were successfully performed in all subjects, and no regional inducible perfusion defects were observed in type 2 diabetes mellitus patients. Diastolic strain rate and myocardial perfusion reserve were significantly impaired in patients with type 2 diabetes mellitus compared to control subjects (P < 0.001 for both). Interestingly, impaired diastolic function in type 2 diabetes mellitus was not associated with impaired myocardial perfusion reserve (r = 0.12, P = NS). Conversely a significant association was observed between diastolic dysfunction and myocardial triglyceride content (r = ?0.71, P < 0.001), which proved to be independent of age, gender, diabetes duration, blood pressure, and fasting blood glucose.

Conclusion:

Myocardial steatosis may represent an early marker of diabetic heart disease, triggering subclinical myocardial dysfunction irrespective of myocardial perfusion reserve. J. Magn. Reson. Imaging 2012;35:804–811. © 2011 Wiley Periodicals, Inc.

     

Cardiac troponin T and creatine kinase predict mid-term infarct size and left ventricular function after acute myocardial infarction: a cardiac MR study

Purpose:

To assess the relation of cardiac troponin T (cTnT) and creatine kinase (CK) release with infarct size and left ventricular function evaluated during the subacute phase as well as four months after acute myocardial infarction (AMI) by contrast‐enhanced MRI (CE‐MRI).

Materials and Methods:

CMR of 80 patients (68 male, mean age 54.2 ± 11.7 years) was performed within 8 days and 4 months after first acute ST‐elevation AMI with successful primary angioplasty. CK and cTnT concentrations were determined serially from admission to day 4 after symptom onset.

Results:

All single time‐points, estimated average release and peak concentrations of CK and cTnT markers correlated significantly with acute and mid‐term infarct size (r = 0.43 to 0.79, all P < 0.001), ejection fraction (EF%) (r = ?0.42 to ?0.58, all P < 0.002) as well as with end‐systolic volume (ESV) (r = 0.32 to 0.57, all P < 0.002) at all times of assessment. Patients with cTnT concentrations below the cutoff value of 3.26 μg/L measured 48 h after AMI‐related symptom onset had a significant improvement in global (EF: P < 0.0001) myocardial function during the study period, whereas in those with cTnT ≥ 3.26 μg/L, functional recovery did not occur (P = 0.09).

Conclusion:

All single, mean and maximum concentrations of cTnT and CK measured within the first 4 days after AMI permit an accurate prediction of infarct size and left ventricular function as determined in the acute phase as well as four months after AMI by CE‐MRI. J. Magn. Reson. Imaging 2011;33:847–854. © 2011 Wiley‐Liss, Inc.

     

Quantification of regional functional improvement of infarcted myocardium after primary PTCA by contrast‐enhanced magnetic resonance imaging

Purpose

To assess with cardiac magnetic resonance imaging (CMR) the relationship between treatment delay and improvement of regional left ventricular function after primary percutaneous transluminal coronary angioplasty (p‐PTCA) for acute myocardial infarction (AMI).

Materials and Methods

We performed cine‐ and late‐enhancement (LE) CMR in 40 patients with first AMI after restoring TIMI 3 flow with p‐PTCA and at a follow‐up 4 months later. Infarcted segments were determined from LE images. Regional left ventricular function was quantified from cine‐CMR images. Segmentation followed the American Heart Association 17‐segments model. Patients were divided into groups with delay <3 hours, 3–6 hours, 6–12 hours, and a delay >12 hours.

Results

Segmental wall thickening (SWT) significantly iproved only in segments reperfused within 6 hours (P < 0.001). Follow‐up SWT was significantly higher if segments were reperfused early (<3 hours: 74 ± 4%, 3–6 hours: 57 ± 4%, 6–12 hours: 48 ± 7%, <3 to 3–6: P < 0.003, and <3 to 6–12 hours: P < 0.001). The extent of improvement was greater if delay was <3 hours compared to segments with a delay of >3 hours (<3 hours: +21 ± 3%, 3–6 hours: +8 ± 4%, 6–12 hours: +6 ± 3%; <3 hours to 3–6 hours, and 6–12 h, P < 0.02).

Conclusion

We quantitatively demonstrated that time to p‐PTCA treatment significantly influences regional functional recovery of infarcted myocardium at a 4‐month follow‐up. J. Magn. Reson. Imaging 2009;29:298–304. © 2009 Wiley‐Liss, Inc.     

T2-weighted and diffusion-weighted MRI for discriminating benign from malignant focal liver lesions: diagnostic abilities of single versus combined interpretations

Purpose:

To compare the diagnostic accuracies of diffusion‐weighted imaging (DWI), T2‐weighted imaging (T2WI), and the combination of both sequences in discriminating benign from malignant focal liver lesions (FLLs).

Materials and Methods:

In all, 166 patients with 269 FLLs (153 benign and 116 malignant) were retrospectively evaluated. Two abdominal readers visually assessed the DWI, T2WI, and the combined (DWI+T2WI) image sets in an independent and blinded manner. The diagnostic abilities of each image set in discriminating the benign from the malignant FLLs set were compared using a binary logistic regression model. Pathologic results, consensus reading, and follow‐up imaging were used as the reference standard.

Results:

The overall characterization accuracy in all lesions of the combined set (80.3%) was significantly higher than those of the T2WI set (68.8%) and DWI set (73.2%) (combined vs. T2WI, P < 0.001; combined vs. DWI, P = 0.001), while there was no significant difference between the T2WI and DWI sets (P = 0.058). All image sets were more accurate in the characterization of malignant FLLs than of benign FLLs (P < 0.001).

Conclusion:

T2WI and DWI are complementary in discriminating benign from malignant FLLs; their combination improves diagnostic confidence. J. Magn. Reson. Imaging 2012;35:1388–1396. © 2012 Wiley Periodicals Inc.     

Development of a novel optimized breathhold technique for myocardial T2 measurement in thalassemia

Purpose

To develop a reproducible fast spin‐echo (FSE) technique for accurate myocardial T2 measurement with application to iron overload assessment in thalassemia.

Materials and Methods

An FSE sequence was developed to permit acquisition of multiple TE images in one breathhold (BH‐FSE). A dynamic black‐blood scheme was introduced to better cancel blood signal. A nonselective refocusing train was also adopted to suppress stimulated echoes. The optimized technique was tested on phantoms and then applied to 10 normal volunteers and 10 thalassemia patients. Interstudy reproducibility was measured on all the 20 subjects.

Results

The mean difference in T2 values was 1.7% from phantom experiments between BH‐FSE and the conventional spin‐echo (SE) technique. High contrast BH‐FSE images were acquired from human subjects, with minimal stimulated echoes and effective blood suppression (P = 0.0005). The coefficient of variation for interstudy reproducibility was 4.3%. T2 values from thalassemia patients were substantially lower than those from the normal subjects (45.2 ± 26.1 msec vs. 56.9 ± 8.4ms, P = 0.02).

Conclusion

The dynamic black‐blood T2 sequence is a fast reproducible acquisition that compares favorably with conventional techniques, is robust to motion artifacts, and yields high blood‐myocardium contrast. This technique may provide a useful tool in thalassemia and other scenarios requiring myocardial T2 quantification. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.

     

Automated truncation method for myocardial T2* measurement in thalassemia

Purpose:

To propose an automated truncation method for myocardial T2* measurement and evaluate this method on a large population of patients with iron loading in the heart and scanned at multiple magnetic resonance imaging (MRI) centers.

Materials and Methods:

A total of 550 thalassemia patients were scanned at 20 international centers using a variety of MR scanners (Siemens, Philips, or GE). A single mid‐ventricular short axis slice was imaged. All patient data were anonymized before the T2* were measured by expert observers using standard techniques. These same datasets were then retrospectively processed using the proposed automated truncation method by another independent observer and the resulting T2* measurements were compared with those of expert readings.

Results:

The T2* measurements using the automated method showed good agreement with those measured by expert observers using standard techniques (P = 0.95) with a low coefficient of variation (1.6%).

Conclusion:

This study demonstrates feasibility and good reproducibility of a new automated truncation method for myocardial T2* measurement. This approach simplifies the overall analysis and can be easily incorporated into T2* analysis software to facilitate further development of a fully automated myocardial tissue iron quantification. J. Magn. Reson. Imaging 2013;37:479–483. © 2012 Wiley Periodicals, Inc.     

Diagnostic performance of heavily T2-weighted techniques in obstructive hydrocephalus: comparison study of two different 3D heavily T2-weighted and conventional T2-weighted sequences

Purpose

To evaluate efficacy of three-dimensional (3D) heavily T2-weighted (W) MRI sequences in assessment of cerebrospinal fluid (CSF) pathways and to compare two different types of 3D heavily T2W MRI sequences (CISS and SPACE) with two-dimensional (2D) T2W turbo spin echo (TSE) sequences for hydrocephalus with intraventricular obstruction.

Materials and methods

Sixty-two patients who were diagnosed with intraventricular obstructive hydrocephalus, according to clinical and radiological findings, were included in this retrospective study. 2D-TSE-T2, 3D-CISS, and 3D-SPACE, which are part of the protocol, were analyzed quantitatively by measuring ventricle-to-parenchyma contrast-to-noise ratio (CNR), and qualitatively by evaluating the capabilities of visualization of the obstructive pathology, overall image quality, severity of artifacts, and delineation of the CSF pathways. One-way ANOVA and Friedman’s test were used for statistical analysis.

Results

CNR between CSF and brain parenchyma was significantly higher using 3D-SPACE sequences compared with 3D-CISS and 2D-TSE-T2 sequences. The qualitative findings showed that 3D heavily T2W sequences were superior to 2D-TSE-T2 sequences. 3D-SPACE sequences showed fewer artifacts than 3D-CISS or 2D-TSE-T2 sequences.

Conclusion

3D heavily T2W sequences are necessary tools for assessment of CSF pathways in patients with intraventricular obstructive hydrocephalus. 3D-SPACE sequences allowed heavy T2W, which is necessary for CSF flow imaging and provided significantly fewer image artifacts and improved CNR in comparison with 3D-CISS sequences.

     

Characterization of the peri-infarction zone using T2-weighted MRI and delayed-enhancement MRI in patients with acute myocardial infarction

To characterize the peri-infarction zone using T2-weighted (T2w) magnetic resonance imaging (MRI) and infarct size on delayed enhancement (DE) MRI in patients with acute myocardial infarction (AMI). In 65 patients, short-axis T2w and DE MRI images were acquired 5 ± 3 d after AMI. The MRI was analyzed using a threshold method defining infarct size on DE MRI and edema on T2w MRI as areas with signal intensity larger than +2 SD above remote normal myocardium. The peri-infarction zone was calculated as the difference between the size of edema and the infarct size. The size of edema on T2w MRI (31.3 ± 13.4% of LV area) was larger than the infarct size on DE MRI (20.3 ± 10.4% of LV area, p< 0.0001). The size of the peri-infarction zone was 11.0 ± 10.0% of the LV area. Good correlation was found between infarct size on DE MRI and peak creatine kinase (CK) isoenzyme MB (r = 0.65, p< 0.0001), but there was no correlation between the size of the peri-infarction zone and CK MB (r = 0.05, p = 0.67). The peri-infarction zone was larger in patients with an infarct size <28% of the LV area (12.6 ± 10.0% LV area) compared with patients with an infarct size ≥28% of the LV area (6.7 ± 9.0% of the LV area, p< 0.05). The peri-infarction zone does not correlate with enzymatic parameters of infarct size and is substantially larger in small infarcts, indicating viable myocardium.This study was funded in part by Pinguin-Stiftung, Duesseldorf, Germany and by Schering Company, Berlin, Germany.     

Measuring aortic diameter with different MR techniques: Comparison of three‐dimensional (3D) navigated steady‐state free‐precession (SSFP), 3D contrast‐enhanced magnetic resonance angiography (CE‐MRA), 2D T2 black blood,and 2D cine SSFP

Purpose:

To compare nongated three‐dimensional (3D) contrast‐enhanced magnetic resonance angiography (CE‐MRA) with 3D‐navigated cardiac‐gated steady‐state free‐precession bright blood (3D‐nav SSFP) and noncontrast 2D techniques for ascending aorta dimension measurements.

Materials and Methods:

Twenty‐five clinical exams were reviewed to evaluate the ascending aorta at 1.5T using: breathhold cine bright blood (SSFP), cardiac‐triggered T2 black blood (T2 BB), axial 3D‐nav SSFP, and nongated 3D CE‐MRA. Three radiologists independently measured aortic size at three specified locations for each sequence. Means, SDs, interobserver correlation, and vessel edge sharpness were statistically evaluated.

Results:

Measurements were greatest for 3D‐nav SSFP and 3D CE‐MRA and smallest for T2 BB. There was no significant difference between 3D‐nav SSFP and 3D CE‐MRA (P = 0.43–0.86), but significance was observed comparing T2 BB to all sequences. Interobserver agreement was uniformly >0.9, with T2 BB best, followed closely by 3D‐nav SSFP and 2D cine SSFP, and 3D CE‐MRA being the worst. Edge sharpness was significantly poorer for 3D CE‐MRA compared to the other sequences (P < 0.001).

Conclusion:

If diameter measurements are the main clinical concern, 3D‐nav SSFP appears to be the best choice, as it has a sharp edge profile, is easy to acquire and postprocess, and shows very good interobserver correlation. J. Magn. Reson. Imaging 2010;31:177–184. © 2009 Wiley‐Liss, Inc.