Combined use of T2‐weighted MRI and T1‐weighted dynamic contrast–enhanced MRI in the automated analysis of breast lesions

A multiparametric computer‐aided diagnosis scheme that combines information from T₁‐weighted dynamic contrast–enhanced (DCE)‐MRI and T₂‐weighted MRI was investigated using a database of 110 malignant and 86 benign breast lesions. Automatic lesion segmentation was performed, and three categories of lesion features (geometric, T₁‐weighted DCE, and T₂‐weighted) were automatically extracted. Stepwise feature selection was performed considering only geometric features, only T₁‐weighted DCE features, only T₂‐weighted features, and all features. Features were merged with Bayesian artificial neural networks, and diagnostic performance was evaluated by ROC analysis. With leave‐one‐lesion‐out cross‐validation, an area under the ROC curve value of 0.77 ± 0.03 was achieved with T₂‐weighted‐only features, indicating high diagnostic value of information in T₂‐weighted images. Area under the ROC curve values of 0.79 ± 0.03 and 0.80 ± 0.03 were obtained for geometric‐only features and T₁‐weighted DCE‐only features, respectively. When all features were considered, an area under the ROC curve value of 0.85 ± 0.03 was achieved. We observed P values of 0.006, 0.023, and 0.0014 between the geometric‐only, T₁‐weighted DCE‐only, and T₂‐weighted‐only features and all features conditions, respectively. When ranked, the P values satisfied the Holm–Bonferroni multiple‐comparison test; thus, the improvement of multiparametric computer‐aided diagnosis was statistically significant. A computer‐aided diagnosis scheme that combines information from T₁‐weighted DCE and T₂‐weighted MRI may be advantageous over conventional T₁‐weighted DCE‐MRI computer‐aided diagnosis. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

FASCINATE: A pulse sequence for simultaneous acquisition of T2‐weighted and fluid‐attenuated images

A pulse sequence that enables simultaneous acquisition of T₂‐weighted and fluid‐attenuated images is presented. This sequence is referred to as FASCINATE (Fluid‐Attenuated Scan Combined with Interleaved Non‐ATtEnuation). In this new technique, the inversion pulse of conventional fast fluid‐attenuated inversion recovery (FLAIR) is replaced with a fast spin echo (FSE) acquisition that has an additional 180(y)–90(x) pulse train for driven inversion. By using appropriate scan parameters, the first part of the sequence provides T₂‐weighted images and the second part provides fluid‐attenuated images, thus allowing simultaneous acquisition in a single scan time comparable to that of fast FLAIR. FASCINATE was compared with conventional scanning techniques using a normal volunteer and a patient. A signal simulation was also conducted. In the human study, both T₂‐weighted and fluid‐attenuated images from FASCINATE showed the same image quality as conventional images, suggesting the potential for this technique to replace the combination of fast FLAIR and T₂‐weighted FSE for scan time reduction. Magn Reson Med 51:205–211, 2004. © 2003 Wiley‐Liss, Inc.     

Effect of hyoscine butylbromide (HBB) on the uterine corpus: Quantitative assessment with T2‐weighted (T2W) MRI in healthy volunteers

Purpose:

To investigate effects of hyoscine butylbromide (HBB) on the appearance of three zonal anatomy of the uterine corpus on T2‐weighted images (T2WI).

Materials and Methods:

Sagittal T2WI of the pelvis were acquired before and after intramuscular administration of HBB with interval of 10 minutes in 22 healthy volunteers. By drawing polygonal regions of interest (ROIs), the uterine corpus was delineated into outer myometrium (OM), junctional zone (JZ), and endometrium (EM) in 20 subjects. Areas (mm²) and relative signal intensity (rSI) of each layer were compared between pre‐HBB and post‐HBB administration images by using paired t‐tests. Histogram analysis was conducted for the uterine layers and changes were visualized.

Results:

Areas of OM were significantly increased (P = 0.014) and mean rSI of JZ and OM were significantly increased (P = 0.007 and 0.001, respectively) after administration of HBB. Histogram showed an increase in the number of pixels with higher rSI in the OM, which was considered to be caused by an increase in interstitial fluid and vascular dilatation. EM did not show significant changes.

Conclusion:

Layer‐wise ROI analyses demonstrated changes in the area and rSI in T2WI of the uterus after HBB administration. Histogram analysis contributed to the investigation of signal changes. J. Magn. Reson. Imaging 2010;32:441–445. © 2010 Wiley‐Liss, Inc.     

Diagnostic value of T2‐weighted imaging for the detection of superficial cranial artery inflammation in giant cell arteritis

Purpose:

To evaluate the diagnostic value of T2‐weighted radial MR imaging for the detection of superficial cranial arteries' inflammatory involvement in patients with giant cell arteritis (GCA).

Materials and Methods:

Forty‐three patients with suspected giant cell arteritis underwent 3 Tesla (T) high‐field MRI. T2‐weighted inversion recovery (IR) fast spin echo images with radial sampling (BLADE‐technique) were acquired and compared with postcontrast T1‐weighted spin echo images.

Results:

T2‐weighted images revealed mural edema in the superficial cranial arteries in 11 patients in concordance with severe inflammatory contrast enhancement in T1‐weighted images (grade 4 in a 4‐point ranking scale). Excellent correlation (r = 0.82; P < 0.001) of measured wall thickness in T1‐ and T2‐weighted images was achieved.

Conclusion:

The results of this study indicate the potential of radial T2 weighted imaging for a first detection of inflammatory changes in the small superficial cranial arteries without the need for contrast medium. Future studies are needed to evaluate the influence of spatial resolution of the T2 images and to improve the detection of moderate GCA related changes in vessel inflammation. J. Magn. Reson. Imaging 2010; 31: 470–474. © 2010 Wiley‐Liss, Inc.     

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.     

Magnetic resonance imaging of the upper abdomen using a free-breathing T2-weighted turbo spin echo sequence with navigator triggered prospective acquisition correction

PURPOSE: To evaluate a free-breathing navigator triggered T2-weighted turbo spin-echo sequence with prospective acquisition correction (T2w-PACE-TSE) for MRI of the upper abdomen in comparison to a conventional T2-weighted TSE (T2w-CTSE), a single-shot TSE (T2w-HASTE), and a T1-weighted gradient-echo sequence (T1w-FLASH). MATERIALS AND METHODS: A total of 40 consecutive patients were examined at 1.5 T using free-breathing T2w-PACE-TSE, free-breathing T2w-CTSE, and breath-hold T2w-HASTE and T1w-FLASH acquisition. Images were evaluated qualitatively by three radiologists regarding motion artifacts, liver-spleen contrast, depiction of intrahepatic vessels, the pancreas and the adrenal glands, and overall image quality on a four-point scale. Quantitative analysis of the liver-spleen contrast was performed. RESULTS: Depiction and sharpness of intrahepatic vessels were rated significantly better (P < 0.01) using T2w-PACE-TSE compared to T2w-CTSE and T2w-HASTE sequences. Significantly higher contrast values were measured for T2w-PACE-TSE images compared to T2w-CTSE, T2w-HASTE, and T1w-FLASH images (P < 0.01). Mean examination time of the T2w-PACE-TSE was 7.91 minutes, acquisition time of the T2w-CTSE sequence was 4.52 minutes. CONCLUSION: Prospective acquisition correction is an efficient method for reducing respiratory movement artifacts in T2w-TSE imaging of the upper abdomen. Compared to T2w-CTSE and T2w-HASTE sequences recognition of anatomical details and contrast can be significantly improved.     

Prostate cancer detection with 3 T MRI: Comparison of diffusion‐weighted imaging and dynamic contrast‐enhanced MRI in combination with T2‐weighted imaging

Purpose:

To evaluate the diagnostic ability of diffusion‐weighted imaging (DWI) and dynamic contrast‐enhanced imaging (DCEI) in combination with T2‐weighted imaging (T2WI) for the detection of prostate cancer using 3 T magnetic resonance imaging (MRI) with a phased‐array body coil.

Materials and Methods:

Fifty‐three patients with elevated serum levels of prostate‐specific antigen (PSA) were evaluated by T2WI, DWI, and DCEI prior to needle biopsy. The obtained data from T2WI alone (protocol A), a combination of T2WI and DWI (protocol B), a combination T2WI and DCEI (protocol C), and a combination of T2WI plus DWI and DCEI (protocol D) were subjected to receiver operating characteristic (ROC) curve analysis.

Results:

The sensitivity, specificity, accuracy, and area under the ROC curve (Az) for region‐based analysis were: 61%, 91%, 84%, and 0.8415, respectively, in protocol A; 76%, 94%, 90%, and 0.8931, respectively, in protocol B; 77%, 93%, 89%, and 0.8655, respectively, in protocol C; and 81%, 96%, 92%, and 0.8968, respectively in protocol D. ROC analysis revealed significant differences between protocols A and B (P = 0.0008) and between protocols A and D (P = 0.0004).

Conclusion:

In patients with elevated PSA levels the combination of T2WI, DWI, DCEI using 3 T MRI may be a reasonable approach for the detection of prostate cancer. J. Magn. Reson. Imaging 2010;31:625–631. © 2010 Wiley‐Liss, Inc.     

Features of the hypointense solid lesions in the female pelvis on T2‐weighted MRI

Most solid lesions in the female pelvis appearing hyperintense on T2‐weighted images should be interpreted as malignant. In contrast, if the solid lesions in the female pelvis appear hypointense on T2‐weighted images they may be benign. The characteristic imaging features of hyperintense solid lesions in the female pelvis on T2‐weighted images are well known, but various unusual causes and imaging features of hypointense solid lesions in the female pelvis on T2‐weighted images can be particularly misleading. Therefore, careful assessment of hypointense solid lesions in the female pelvis on T2‐weighted images is warranted. In this article, we demonstrate a variety of hypointense solid lesions in the female pelvis on T2‐weighted images. Familiarity with the clinical setting and imaging features of hypointense solid lesions in the female pelvis on T2‐weighted images will facilitate prompt, accurate diagnosis and treatment. J. Magn. Reson. Imaging 2014;39:493–503 . © 2014 Wiley Periodicals, Inc .     

Prostate cancer vs. post‐biopsy hemorrhage: Diagnosis with T2‐ and diffusion‐weighted imaging

Purpose:

To assess the value of quantitative T2 signal intensity (SI) and apparent diffusion coefficient (ADC) to differentiate prostate cancer from post‐biopsy hemorrhage, using prostatectomy as the reference.

Materials and Methods:

Forty‐five men with prostate cancer underwent prostate magnetic resonance imaging (MRI), including axial T1‐weighted imaging (T1WI), T2WI, and single‐shot echo‐planar image (SS EPI) diffusion‐weighted imaging. Two observers measured, in consensus, normalized T2 signal intensity (SI) (nT2, relative to muscle T2 SI), ADC, and normalized ADC (nADC, relative to urine ADC) on peripheral zone (PZ) tumors, benign PZ hemorrhage, and non‐hemorrhagic benign PZ. Tumor maps from prostatectomy were used as the reference. Mixed model analysis of variance was performed to compare parameters among the three tissue classes, and Pearson's correlation coefficient was utilized to assess correlation between parameters and tumor size and Gleason score. Receiver‐operating characteristic (ROC)‐curve analysis was used to determine the performance of nT2, ADC, and nADC for diagnosis of prostate cancer.

Results:

nT2, ADC, and nADC were significantly lower in tumor compared with hemorrhagic and non‐hemorrhagic benign PZ (P < 0.0001). There was a weak but significant correlation between ADC and Gleason score (r = ?0.30, P = 0.0119), and between ADC and tumor size (r = ?0.40, P = 0.0027), whereas there was no correlation between nT2 and Gleason score and tumor size. The areas under the curve to distinguish tumor from benign hemorrhagic and non‐hemorrhagic PZ were 0.97, 0.96, and 0.933 for nT2, ADC, and nADC, respectively.

Conclusion:

Quantitative T2 SI and ADC/nADC values may be used to reliably distinguish prostate cancer from post‐biopsy hemorrhage. J. Magn. Reson. Imaging 2010;31:1387–1394. © 2010 Wiley‐Liss, Inc.

     

T2‐weighted 3D fast spin echo imaging with water–fat separation in a single acquisition

Purpose:

To develop a robust 3D fast spin echo (FSE) T₂‐weighted imaging method with uniform water and fat separation in a single acquisition, amenable to high‐quality multiplanar reformations.

Materials and Methods:

The Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation (IDEAL) method was integrated with modulated refocusing flip angle 3D‐FSE. Echoes required for IDEAL processing were acquired by shifting the readout gradient with respect to the Carr‐Purcell‐Meiboom‐Gill echo. To reduce the scan time, an alternative data acquisition using two gradient echoes per repetition was implemented. Using the latter approach, a total of four gradient echoes were acquired in two repetitions and used in the modified IDEAL reconstruction.

Results:

3D‐FSE T₂‐weighted images with uniform water–fat separation were successfully acquired in various anatomies including breast, abdomen, knee, and ankle in clinically feasible scan times, ranging from 5:30–8:30 minutes. Using water‐only and fat‐only images, in‐phase and out‐of‐phase images were reconstructed.

Conclusion:

3D‐FSE‐IDEAL provides volumetric T₂‐weighted images with uniform water and fat separation in a single acquisition. High‐resolution images with multiple contrasts can be reformatted to any orientation from a single acquisition. This could potentially replace 2D‐FSE acquisitions with and without fat suppression and in multiple planes, thus improving overall imaging efficiency. J. Magn. Reson. Imaging 2010;32:745–751. © 2010 Wiley‐Liss, Inc.