Eigenimage Filtering in MR Imaging

Purpose:To investigate the comparison between diffusion-weighted imaging ͑DWI͒, T 2 -weighted imaging, ͑T 2 WI͒ and contrast T 1 -weighted imaging ͑cT 1 WI͒ in uterine leiomyoma following treatment by magnetic resonance imaging-guided, high intensity focused ultrasound surgery ͑MRg-HIFUS͒. Methods: Twenty one patients ͑45Ϯ 5 yrs͒ with clinical symptoms of uterine leiomyoma ͑fibroids͒ were treated by MRg-HIFUS using an integrated 1.5T MRI-HIFUS system. MRI parameters consisted of DWI, T 2 WI, and T 1 -weighted fast spoiled gradient echo before and after contrast. The post-MRg-HIFUS treatment volume in the fibroid was assessed by cT 1 WI and DWI. Trace apparent diffusion coefficient maps were constructed for quantitative analysis. The regions of the treated uterine tissue were defined by a semisupervised segmentation method called the "eigenimage filter," using both cT 1 WI and DWI. Signal-to-noise ratios were determined for the T 2 WI pretreatment images. Segmented regions were tested by a similarity index for congruence. Descriptive, regression, and Bland-Altman statistics were calculated. Results: All the patients exhibited heterogeneously increased DWI signal intensity localized in the treated fibroid regions and were colocalized with the cT 1 WI defined area. The mean pretreatment T 2 WI signal intensity ratios were T 2 WI/ muscle= 1.8Ϯ 0.7 and T 2 WI/ myometrium= 0.7Ϯ 0.4. The congruence between the regions was significant, with a similarity of 84% and a difference of 8% between the regions. Regression analyses of the cT 1 WI and DWI segmented treatment volumes were found to be significantly correlated ͑r 2 = 0.94, p Ͻ 0.05͒ with the linear equation, ͑cT 1 WI͒ = 1.1͑DWI͒ − 0.66. There is good agreement between the regions defined by cT1WI and DWI in most of the cases as shown from the Bland-Altman plots. Conclusions: Diffusion-weighted imaging exhibited excellent agreement, congruence, and correlation with the cT 1 WI-defined region of treatment in uterine fibroid. Therefore, DWI could be useful as an adjunct for assessing treatment of uterine fibroids by MRg-HIFUS.

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“…The volumes of treated uterine tissue were obtained by using a semisupervised segmentation method called Eigenimage ͑EI͒ filter. [32][33][34] …”

Section: Iid Image Data Analysismentioning

confidence: 99%

Comparison between diffusion‐weighted imaging, ‐weighted, and postcontrast ‐weighted imaging after MR‐guided, high intensity, focused ultrasound treatment of uterine leiomyomata: Preliminary results

2010

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“…Images were baseline corrected, Fourier transformed and formatted for display using in-house software. All postprocessing of the reconstructed images was performed using the Eigentool image analysis software package (23). Computer-generated MRI parameter maps were calculated on a pixel-by-pixel basis.…”

Section: Mri Data Analysis and The Selection Of Regions Of Interestmentioning

confidence: 99%

Acute blood–brain barrier opening in experimentally induced focal cerebral ischemia is preferentially identified by quantitative magnetization transfer imaging

Knight

Nagesh

Nagaraja³

et al. 2005

Magnetic Resonance in Med

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Pathologic changes in brain tissue during and after stroke may lead to injury of the blood-brain barrier (BBB) and subsequent hemorrhagic transformation (HT). In a rat model of HT, the apparent diffusion coefficient of water, cerebral blood flow, relaxation times, T 1 and T 2 , and magnetization transfer (MT) related parameters (T 1sat , K for and the MT ratio) were repetitively measured during 3 h of focal ischemia and 2 h of reperfusion (n ‫؍‬ 8). Areas of BBB opening were identified by sequential assay of the transcapillary influx of Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) by MRI and 14 C-␣-aminoisobutyric acid (AIB) by quantitative autoradiography. Ischemia-injured regions of interest were identified from the MRI data and divided into those with and without BBB opening. Of the several MRI parameters measured, the T 1sat in the caudate-putamen and preoptic area during ischemia and the first 2 h of reperfusion correlated best with the regional pattern of BBB opening observed thereafter. These data suggest that an ipsilateral/ contralateral T 1sat ratio > 1.6 demarcates leakage of small molecules such as Gd-DTPA and AIB across the BBB. Key words: Gd-DTPA; hemorrhagic transformation; magnetization transfer; MRI; rt-PA; stroke Thrombolysis using recombinant tissue plasminogen activator (rt-PA) has proven to be an effective intervention for the treatment of acute ischemic stroke (1), but the risk of hemorrhagic transformation (HT) following such treatment remains an obstacle to widespread usage of thrombolytic agents. To illustrate this risk, the probability of symptomatic HT increases significantly during the first 36 h after stroke onset in patients receiving rt-PA (6.4% vs. 0.6% in placebo-treated patients), and 61% of the patients with symptomatic HT die within 3 months (1). Studies performed using animal stroke models show similar findings with increased risk of HT associated with thrombolytics (2-5). In view of these complications with thrombolytic therapy, it is important to develop diagnostic imaging techniques that reliably identify tissue regions that are prone to HT and to obtain such data when deciding on a treatment protocol.One of the possible imaging techniques is computed tomography (CT). The sensitivity of CT for detection of early ischemic damage remains controversial because a significant proportion of stroke patients show negative acute CT images but go on to develop large infarcts (6). Although it is the standard diagnostic test for extant cerebral bleeding, CT has a limited capacity to predict HT in ischemic stroke (7). An early report from the NINDS rt-PA Stroke Trial showed only a 57% efficiency for the prediction of symptomatic HT based on early CT findings (1). A more recent retrospective analysis of CT films from the trial adjusted the data for group imbalances in several baseline clinical features and found that early ischemic changes were not predictive of clinical deterioration at 24 h or of symptomatic intracerebral hemorrhage (i.e., death) at 90 days (8). It may be that high...

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“…MR image analysis was performed using a SUN Ultra-SPARC60 workstation (Sun Microsystems, Mountain View, CA) and processed using the Eigentool image analysis software (Image Analysis Lab, Henry Ford Hospital, Detroit MI) (16,17). Subimaging of the breast from the background was done using thresholding and morphological operations (18).…”

Section: Mr and Spectroscopic Data Analysismentioning

confidence: 99%

Combined dynamic contrast enhanced breast MR and proton spectroscopic imaging: A feasibility study

Jacobs

Barker

Argani

et al. 2004

Magnetic Resonance Imaging

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Purpose:To investigate the feasibility of combined dynamic contrast enhanced (DCE) and magnetic resonance spectroscopy (MRS) in evaluating breast lesions. Methods:Nine patients with positive mammograms scheduled for either biopsy or mastectomy were examined on a 1.5-T MR scanner. DCE was performed with administration of gadolinium-DTPA contrast using a two-dimensional spoiled gradient recall echo (SPGR) sequence. Proton spectroscopy (TR/TE ϭ 2000/272 msec) was performed using PRESS single slice (10 mm). Lesion time intensity curves were classified as persistent (type 1), plateau (type 2), or washout (type 3) pattern enhancement. Choline (Cho) signal-to-noise ratios (SNRs) and enhancement patterns were compared between benign and malignant lesions as determined by histopathology. Results:Five patients had breast carcinoma and four had benign lesions. Type 1 enhancement was found in two benign cases, type 2 enhancement in two of four benign and four of five malignant lesions, and one malignant case exhibited a type 3 pattern. Choline SNR was significantly different (P Ͻ 0.003) between benign and malignant lesions (2.0 Ϯ 0.3 vs. 5.7 Ϯ 1.4; P Ͻ 0.003). Choline SNR was less than 4.0 in all of the benign lesions, including the two lesions with type 2 enhancement. Conclusion:Proton MRS appears to be a promising technique for classification of breast lesions when DCE results are equivocal. A combination of DCE and MRS is feasible, and may have improved specificity compared to either modality alone.

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Eigenimage Filtering in MR Imaging

Cited by 119 publications

References 0 publications

Comparison between diffusion‐weighted imaging, ‐weighted, and postcontrast ‐weighted imaging after MR‐guided, high intensity, focused ultrasound treatment of uterine leiomyomata: Preliminary results

Comparison between diffusion‐weighted imaging, ‐weighted, and postcontrast ‐weighted imaging after MR‐guided, high intensity, focused ultrasound treatment of uterine leiomyomata: Preliminary results

Acute blood–brain barrier opening in experimentally induced focal cerebral ischemia is preferentially identified by quantitative magnetization transfer imaging

Combined dynamic contrast enhanced breast MR and proton spectroscopic imaging: A feasibility study

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