Xiaobing Fan

University of Chicago, Chicago, Illinois, United States

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Publications (53)147.88 Total impact

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    ABSTRACT: This pilot study compared the detectability of internal thermal marks produced with MRI-guided focused ultrasound (MRgFUS) on MRI, computed tomography (CT), ultrasonography (US), and color images from digital scanning. Internal marks made using MRgFUS could potentially guide surgical, biopsy or radiotherapy procedures. New Zealand White rabbits (n = 6) thigh muscle were marked using a Philips MRgFUS system. Before and after sonications, rabbits were imaged using T1- and T2-weighted MRI. Then rabbits were sacrificed and imaging was performed using CT and US. After surgical excision specimens were scanned for color conspicuity analysis. Images were read by a radiologist and quantitative analysis of signal intensity was calculated for marks and normal muscle. Of a total of 19 excised marks, approximately 79%, 63%, and 62% were visible on MRI, CT, and US, respectively. The average maximum temperature elevation in the marks during MRgFUS was 39.7 ± 10.1 °C, and average dose diameter (i.e., the diameter of the area that achieved a thermal dose greater than 240 cumulative equivalent minutes at 43 °C) of the mark at the focal plane was 7.3 ± 2.1 mm. On MRI the average normalized signal intensities were significantly higher in marks compared to normal muscle (p < 0.05). On CT, the marked regions were approximately 10 HU lower than normal muscle (p < 0.05). The results demonstrate that MRgFUS can be used to create internal marks that are visible on MRI, CT and US.
    05/2014;
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    ABSTRACT: This pilot study compared the detectability of internal thermal marks produced with MRI-guided focused ultrasound (MRgFUS) on MRI, computed tomography (CT), ultrasonography (US), and color images from digital scanning. Internal marks made using MRgFUS could potentially guide surgical, biopsy or radiotherapy procedures. New Zealand White rabbits (n = 6) thigh muscle were marked using a Philips MRgFUS system. Before and after sonications, rabbits were imaged using T1- and T2-weighted MRI. Then rabbits were sacrificed and imaging was performed using CT and US. After surgical excision specimens were scanned for color conspicuity analysis. Images were read by a radiologist and quantitative analysis of signal intensity was calculated for marks and normal muscle. Of a total of 19 excised marks, approximately 79%, 63%, and 62% were visible on MRI, CT, and US, respectively. The average maximum temperature elevation in the marks during MRgFUS was 39.7 ± 10.1 °C, and average dose diameter (i.e., the diameter of the area that achieved a thermal dose greater than 240 cumulative equivalent minutes at 43 °C) of the mark at the focal plane was 7.3 ± 2.1 mm. On MRI the average normalized signal intensities were significantly higher in marks compared to normal muscle (p < 0.05). On CT, the marked regions were approximately 10 HU lower than normal muscle (p < 0.05). The results demonstrate that MRgFUS can be used to create internal marks that are visible on MRI, CT and US.
    Physica Medica 01/2014; · 1.17 Impact Factor
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    ABSTRACT: Neonatal necrotizing enterocolitis (NEC) is a poorly understood life-threatening illness afflicting premature infants. Research is hampered by the absence of a suitable method to monitor disease progression noninvasively. The primary goal of this research was to test in vivo MRI methods for the noninvasive early detection and staging of inflammation in the ileum of an infant rat model of NEC. Neonatal rats were delivered by cesarean section at embryonic stage of day 20 after the beginning of pregnancy and stressed with formula feeding, hypoxia and bacterial colonization to induce NEC. Naturally born and dam-fed neonatal rats were used as healthy controls. In vivo MRI studies were performed using a Bruker 9.4-T scanner to obtain high-resolution anatomical MR images using both gradient echo and spin echo sequences, pixel-by-pixel T2 maps using a multi-slice-multi-echo sequence, and maps of the apparent diffusion coefficient (ADC) of water using a spin echo sequence, to assess the degree of ileal damage. Pups were sacrificed at the end of the MRI experiment on day 2 or 4 for histology. T2 measured by MRI was increased significantly in the ileal regions of pups with NEC by histology (106.3 ± 6.1 ms) compared with experimentally stressed pups without NEC (85.2 ± 6.8 ms) and nonstressed, control rat pups (64.9 ± 2.3 ms). ADC values measured by diffusion-weighted MRI were also increased in the ileal regions of pups with NEC by histology [(1.98 ± 0.15) × 10(-3) mm(2) /s] compared with experimentally stressed pups without NEC [(1.43 ± 0.16) × 10(-3) mm(2) /s] and nonstressed control pups [(1.10 ± 0.06) × 10(-3) mm(2) /s]. Both T2 and ADC values between these groups were found to be significantly different (p < 0.03). The correlation of MRI results with histologic images of the excised ileal tissue samples strongly suggests that MRI can noninvasively identify NEC and assess intestinal injury prior to clinical symptoms in a physiologic rat pup model of NEC. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.
    NMR in Biomedicine 12/2013; · 3.45 Impact Factor
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    ABSTRACT: Autoimmune ablation of pancreatic β-cells and alteration of its microvasculature may be a predictor of Type I diabetes development. A dynamic manganese-enhanced MRI (MEMRI) approach and an empirical mathematical model were developed to monitor whole pancreatic β-cell function and vasculature modifications in mice. Normal and streptozotocin-induced diabetic FVB/N mice were imaged on a 9.4T MRI system using a 3D magnetization prepared rapid acquisition gradient echo pulse sequence to characterize low dose manganese kinetics in the pancreas head, body and tail. Average signal enhancement in the pancreas (head, body, and tail) as a function of time was fit by a novel empirical mathematical model characterizing contrast uptake/washout rates and yielding parameters describing peak signal, initial slope, and initial area under the curve. Signal enhancement from glucose-induced manganese uptake was fit by a linear function. The results demonstrated that the diabetic pancreatic tail had a significantly lower contrast uptake rate, smaller initial slope/initial area under the curve, and a smaller rate of Mn uptake following glucose activation (p<0.05) compared to the normal pancreatic tail. These observations parallel known patterns of β-cell loss and alteration in supportive vasculature associated with diabetes. Dynamic MEMRI is a promising technique for assessing β-cell functionality and vascular perfusion with potential applications for monitoring diabetes progression and/or therapy.
    Magnetic Resonance Imaging 10/2012; · 2.06 Impact Factor
  • NMR in Biomedicine 07/2012; · 3.45 Impact Factor
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    ABSTRACT: This pilot study investigated the feasibility of using MRI based on BOLD (blood-oxygen-level-dependent) contrast to detect physiological effects of locally induced hyperthermia in a rodent tumor model. Nude mice bearing AT6.1 rodent prostate tumors inoculated in the hind leg were imaged using a 9.4 T scanner using a multi-gradient echo pulse sequence to acquire high spectral and spatial resolution (HiSS) data. Temperature increases of approximately 6 °C were produced in tumor tissue using fiber-optic-guided light from a 250 W halogen lamp. HiSS data were acquired over three slices through the tumor and leg both prior to and during heating. Water spectra were produced from these datasets for each voxel at each time point. Time-dependent changes in water resonance peak width were measured during 15 min of localized tumor heating. The results demonstrated that hyperthermia produced both significant increases and decreases in water resonance peak width. Average decreases in peak width were significantly larger in the tumor rim than in normal muscle (p = 0.04). The effect of hyperthermia in tumor was spatially heterogeneous, i.e. the standard deviation of the change in peak width was significantly larger in the tumor rim than in normal muscle (p = 0.005). Therefore, mild hyperthermia produces spatially heterogeneous changes in water peak width in both tumor and muscle. This may reflect heterogeneous effects of hyperthermia on local oxygenation. The peak width changes in tumor and muscle were significantly different, perhaps due to abnormal tumor vasculature and metabolism. Response to hyperthermia measured by MRI may be useful for identifying and/or characterizing suspicious lesions as well as guiding the development of new hyperthermia protocols.
    Physics in Medicine and Biology 04/2012; 57(9):2653-66. · 2.70 Impact Factor
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    ABSTRACT: This study investigates the feasibility of T(2)∗ to be a diagnostic indicator of early breast cancer in a mouse model. T(2)∗ is sensitive to susceptibility effects due to local inhomogeneity of the magnetic field, e.g., caused by hemosiderin or deoxyhemoglobin. In these mouse models, unlike in patients, the characteristics of single mammary ducts containing pure intraductal cancer can be evaluated. The C3(1)SV40Tag mouse model of breast cancer (n = 11) and normal FVB∕N mice (n = 6) were used to measure T(2)∗ of normal mammary gland tissue, intraepithelial neoplasia, invasive cancers, mammary lymph nodes, and muscle. MRI experiments were performed on a 9.4T animal scanner. High resolution (117 microns) axial 2D multislice gradient echo images with fat suppression were acquired first to identify inguinal mammary gland. Then a multislice multigradient echo pulse sequence with and without fat suppression were performed over the inguinal mammary gland. The modulus of a complex double exponential decay detected by the multigradient echo sequence was used to fit the absolute proton free induction decay averaged over a region of interest to determine the T(2)∗ of water and fat signals. The measured T(2)∗ values of tumor and muscle are similar (∼15 ms), and almost twice that of lymph nodes (∼8 ms). There was a statistically significant difference (p < 0.03) between T(2)∗ in normal mammary tissue (13.7 ± 2.9 ms) and intraductal cancers (11 ± 2.0 ms) when a fat suppression pulse was applied. These are the first reported T(2)∗ measurements from single mammary ducts. The results demonstrated that T(2)∗ measurements may have utility for identifying early pre-invasive cancers in mouse models. This may inspire similar research for patients using T(2)∗ for diagnostic imaging of early breast cancer.
    Medical Physics 03/2012; 39(3):1309-13. · 2.91 Impact Factor
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    ABSTRACT: Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a noninvasive image-guided technique used to thermally ablate solid tumors. During treatment, ultrasound reflections from distal media interfaces can shift prescribed treatment locations. The purpose of this study was to investigate the effect of normal incidence reflections from air, acrylic (modeling bone), and rubber on treatment location, temperature elevation, and heating patterns by performing ultrasound exposures in a tissue-mimicking phantom and in ex vivo porcine tissue using a clinical MR-HIFU platform. The results demonstrated a shift in treatment location toward the distal interface when targeted closer than 2 cm from the interface, especially for acrylic. Our study demonstrated that the ultrasound wave reflections from a distal air interface had less effect than the acrylic interface (modeling bone) on the heating pattern and focal location. This study provides useful information to better understand the limitations and safety concerns of performing MR-HIFU treatments with commercial clinical equipment.
    Journal of Applied Clinical Medical Physics 01/2012; 13(2):3739. · 0.96 Impact Factor
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    ABSTRACT: The purpose of this research is to evaluate the potential for identifying malignant breast lesions and their margins on large specimen MRI, in comparison to specimen radiography and clinical dynamic contrast enhanced MRI (DCE-MRI). Breast specimens were imaged with an MR scanner immediately after surgery, with an IRB-approved protocol and with the patients' informed consent. Specimen sizes were at least 5 cm in diameter and approximately 1 to 4 cm thick. Coronal and axial gradient echo MR images without fat suppression were acquired over the whole specimens using a 9.4T animal scanner. Findings on specimen MRI were compared with findings on specimen radiograph, and their volumes were compared with measurements obtained from clinical DCE-MRI. The results showed that invasive ductal carcinoma (IDC) lesions were easily identified using MRI and the margins were clearly distinguishable from nearby tissue. However, ductal carcinoma in situ (DCIS) lesions were not clearly discernible and were diffused with poorly defined margins on MRI. Calcifications associated with DCIS were visualized in all specimens on specimen radiograph. There is a strong correlation between the maximum diameter of lesions as measured by radiograph and MRI (r = 0.93), as well as the maximum diameter measured by pathology and radiograph/MRI (r>0.75). The volumes of IDC measured on specimen MRI were slightly smaller than those measured on DCE-MRI. Imaging of excised human breast lumpectomy specimens with high magnetic field MRI provides promising results for improvements in lesion identification and margin localization for IDC. However, there are technical challenges in visualization of DCIS lesions. Improvements in specimen imaging are important, as they will provide additional information to standard radiographic analysis.
    Journal of Applied Clinical Medical Physics 01/2012; 13(6):3802. · 0.96 Impact Factor
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    ABSTRACT: To evaluate feasibility of high-resolution, high-field ex vivo prostate magnetic resonance imaging (MRI) as an aid to guide pathologists' examination and develop in vivo MRI methods. Unfixed excised prostatectomy specimens (n = 9) were obtained and imaged immediately after radical prostatectomy under an Institutional Review Board-approved protocol. High-resolution T2-weighted (T2W) MRI of specimens were acquired with a Bruker 9.4 T scanner to correlate with whole-mount histology. Additionally, T2 and apparent diffusion coefficient (ADC) maps were generated. By visual inspection of the nine prostate specimens imaged, high-resolution T2W MRI showed improved anatomical detail compared to published low-resolution images acquired at 4 T as published by other investigators. Benign prostatic hyperplasia, adenocarcinomas, curvilinear duct architecture distortion due to adenocarcinomas, and normal radial duct distribution were readily identified. T2 was ≈10 msec longer (P < 0.03) and the ADC was ≈1.4 times larger (P < 0.002) in the normal peripheral zone compared to the peripheral zone with prostate cancer. Differences in T2 and ADC between benign and malignant tissue are consistent with in vivo data. High-resolution, high-field MRI has the potential to improve the detection and identification of prostate structures. The protocols and techniques developed in this study could augment routine pathological analysis of surgical specimens and guide treatment of prostate cancer patients.
    Journal of Magnetic Resonance Imaging 10/2011; 34(4):956-61. · 2.57 Impact Factor
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    ABSTRACT: The aims of this study were to evaluate high spectral and spatial resolution (HiSS) magnetic resonance imaging (MRI) for the diagnosis of breast cancer without the injection of contrast media by comparing the performance of precontrast HiSS images to that of conventional contrast-enhanced, fat-suppressed, T1-weighted images on the basis of image quality and in the task of classifying benign and malignant breast lesions. Ten benign and 44 malignant lesions were imaged at 1.5 T with HiSS (precontrast administration) and conventional fat-suppressed imaging (3-10 minutes after contrast administration). This set of 108 images, after randomization, was evaluated by three experienced radiologists blinded to the imaging technique. Breast Imaging Reporting and Data System morphologic criteria (lesion shape, lesion margin, and internal signal intensity pattern) and final assessment were used to measure reader performance. Image quality was evaluated on the basis of boundary delineation and quality of fat suppression. An overall probability of malignancy was assigned to each lesion for HiSS and conventional images separately. On boundary delineation and quality of fat suppression, precontrast HiSS scored similarly to conventional postcontrast MRI. On benign versus malignant lesion separation, there was no statistically significant difference in receiver-operating characteristic performance between HiSS and conventional MRI, and HiSS met a reasonable noninferiority condition. Precontrast HiSS imaging is a promising approach for showing lesion morphology without blooming and other artifacts caused by contrast agents. HiSS images could be used to guide subsequent dynamic contrast-enhanced MRI scans to maximize spatial and temporal resolution in suspicious regions. HiSS MRI without contrast agent injection may be particularly important for patients at risk for contrast-induced nephrogenic systemic fibrosis or allergic reactions.
    Academic radiology 09/2011; 18(12):1467-74. · 2.09 Impact Factor
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    ABSTRACT: This study was conducted to determine the incremental value of diffusion-weighted MR imaging (DW-MRI) over T2-weighted imaging diagnosing abdominopelvic abscesses and compare apparent diffusion coefficient (ADC) values of abscesses and non-infected ascites. In this IRB-approved, HIPAA-compliant study, two radiologists retrospectively compared T2-weighted, T2-weighted + DW-MRI and T2-weighted + contrast enhanced MR images of 58 patients (29 with abscess, 29 with ascites) who underwent abdominal MRI for abscess detection. Confidence and sensitivity was compared using McNemar's test. ADC of abscesses and ascites was compared by t test, and a receiver operating characteristic (ROC) curve was constructed. Detection of abscesses and confidence improved significantly when T2-weighted images were combined with DW-MRI (sensitivity: observer 1-100%, observer 2-96.6%) or contrast enhanced images (sensitivity: both observers-100%) compared to T2-weighted images alone (sensitivity: observer 1-65.5%, observer 2-72.4%). All abscesses showed restricted diffusion. Mean ADC of abscesses (observer 1-1.17 ± 0.42 × 10(-)³ mm²/s, observer 2-1.43 ± 0.48 × 10(-3) mm²/s) was lower than ascites (observer 1-3.57 ± 0.68 × 10(-3) mm²/s, observer 2-3.42 ± 0.67 × 10(-3) mm²/s) (p < 0.01). ROC analysis showed perfect discrimination of abscess from ascites with threshold ADC of 2.0 × 10(-3) mm²/s (Az value 1.0). DW-MRI is a valuable adjunct to T2-weighted images diagnosing abdominopelvic abscesses. ADC measurements may have the potential to differentiate abdominal abscesses from ascites.
    Emergency Radiology 08/2011; 18(6):515-24.
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    ABSTRACT: To compare the pathology and kinetic characteristics of breast lesions with focus-, mass-, and nonmass-like enhancement. A total of 852 MRI detected breast lesions in 697 patients were selected for an IRB approved review. Patients underwent dynamic contrast enhanced MRI using one pre- and three to six postcontrast T(1)-weighted images. The "type" of enhancement was classified as mass, nonmass, or focus, and kinetic curves quantified by the initial enhancement percentage (E(1)), time to peak enhancement (T(peak)), and signal enhancement ratio (SER). These kinetic parameters were compared between malignant and benign lesions within each morphologic type. A total of 552 lesions were classified as mass (396 malignant, 156 benign), 261 as nonmass (212 malignant, 49 benign), and 39 as focus (9 malignant, 30 benign). The most common pathology of malignant/benign lesions by morphology: for mass, invasive ductal carcinoma/fibroadenoma; for nonmass, ductal carcinoma in situ (DCIS)/fibrocystic change(FCC); for focus, DCIS/FCC. Benign mass lesions exhibited significantly lower E(1), longer T(peak), and lower SER compared with malignant mass lesions (P < 0.0001). Benign nonmass lesions exhibited only a lower SER compared with malignant nonmass lesions (P < 0.01). By considering the diverse pathology and kinetic characteristics of different lesion morphologies, diagnostic accuracy may be improved.
    Journal of Magnetic Resonance Imaging 06/2011; 33(6):1382-9. · 2.57 Impact Factor
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    ABSTRACT: To determine relative diagnostic value of MR diffusion and perfusion parameters in detection of active small bowel inflammation in patients with Crohn's disease (CD). We reviewed 18 patients with active CD of terminal ileum (TI) who underwent MR enterography (MRE; including dynamic contrast enhanced MRI and diffusion-weighted MRI). Conventional MRI findings of TI were recorded. Regions of interest were drawn over TI and normal ileum to calculate apparent diffusion coefficient (ADC), the volume transfer constant (K(trans)) and the contrast media distribution volume (v(e)). Receiver operating characteristic analysis was used to determine their diagnostic performance. Among conventional MR findings, mural thickening and increased enhancement were present in all actively inflamed small bowel. K(trans), v(e), and ADC values differed significantly between actively inflamed TI and normal ileum (0.92 s(-1) versus 0.36 s(-1); 0.31 versus 0.15 ± 0.08; 0.00198 mm(2)/s versus 0.00311 mm(2)/s; P < 0.001). Area under the curve (AUC) for K(trans), v(e), and ADC values ranged from 0.88 to 0.92 for detection of active inflammation. Combining K(trans) and ADC data provided an AUC value of 0.95. Dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) provide quantitative measures of small bowel inflammation that can differentiate actively inflamed small bowel segments from normal small bowel in CD. DWI provides better sensitivity compared with DCE-MRI and combination of ADC and K(trans) parameters for analysis can potentially improve specificity.
    Journal of Magnetic Resonance Imaging 03/2011; 33(3):615-24. · 2.57 Impact Factor
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    ABSTRACT: High spectral and spatial resolution (HiSS) data, acquired with echo-planar spectroscopic imaging (EPSI), can be used to acquire water spectra from each small image voxel. These images are sensitive to changes in local susceptibility caused by superparamagnetic iron oxide particles (SPIO); therefore, we hypothesized that images derived from HiSS data are very sensitive to tumor neovasculature following injection of SPIO. Accurate image registration was used to validate HiSS detection of neovasculature with histology and micro-computed tomographic (microCT) angiography. Athymic nude mice and Copenhagen rats were inoculated with Dunning AT6.1 prostate tumor cells in the right hind limb. The tumor region was imaged pre- and post-intravenous injection of SPIO. Three-dimensional assemblies of the CD31-stained histologic slices of the mouse legs and the microCT images of the rat vascular casts were registered with EPSI. The average distance between HiSS-predicted regions of high vascular density on magnetic resonance imaging and CD31-stained regions on histology was 200 μm. Similarly, vessels identified by HiSS in the rat images coincided with vasculature in the registered microCT image. The data demonstrate a strong correlation between tumor vasculature identified using HiSS and two gold standards: histology and microCT angiography.
    Molecular Imaging 03/2011; 10(3):187-96. · 3.41 Impact Factor
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    ABSTRACT: Since the advent of screening mammography, approximately one-quarter of newly diagnosed breast cancers are at the earliest preinvasive stage of ductal carcinoma in situ (DCIS). Concomitant with this improvement in early detection has been a growing clinical concern that distinguishing aggressive from indolent DCIS is necessary to optimize patient management. Genetically engineered mouse models offer an appealing experimental framework in which to investigate factors that influence and predict progression of preinvasive neoplasias. Because of the small size of early stage carcinomas in mice, high-resolution imaging techniques are required to effectively observe longitudinal progression. The purpose of the present study was to evaluate the feasibility of MRI for assessment of in situ mammary neoplasias and early invasive mammary cancers that stochastically arise in mammary glands of C3(1) SV40 Tag transgenic mice. Additionally, images of normal mammary glands from wild-type FVB/N mice were acquired and compared with those from transgenic mice. Sixteen mice underwent MR examinations employing axial two-dimensional multi-slice gradient recalled echo scans (TR/TE =∼1000/5.5 ms) with fat suppression in a two-step process targeting both the upper and lower mammary glands. MRI successfully detected in situ and early invasive neoplasias in transgenic mice with high sensitivity and specificity. The average signal-to-noise ratio (SNR) of in situ lesions on fat-suppressed high-resolution T(1) -weighted images was 22.9, which was lower than that of invasive tumors, lymph nodes and muscle (average SNR of 29.5-34.9, p < 0.0001) but significantly higher than that of normal mammary tissue (average SNR = 5.5, p < 0.0001). Evaluation of wild-type mammary glands revealed no cancerous or benign lesions, and comparable image contrast characteristics (average SNR = 5.2) as compared with normal tissue areas of transgenic mice. This present study demonstrates that MRI is an excellent candidate for performing longitudinal assessment of early stage mammary cancer disease progression and response to therapy in the transgenic model system.
    NMR in Biomedicine 01/2011; 24(7):880-7. · 3.45 Impact Factor
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    ABSTRACT: Accurate measurement of the arterial input function is critical for quantitative evaluation of dynamic contrast enhanced magnetic resonance imaging data. Use of the reference tissue method to derive a local arterial input function avoided large errors associated with direct arterial measurements, but relied on literature values for K(trans) and v(e). We demonstrate that accurate values of K(trans) and v(e) in a reference tissue can be measured by comparing contrast media concentration in a reference tissue to plasma concentrations measured directly in a local artery after the 1-2 passes of the contrast media bolus-when plasma concentration is low and can be measured accurately. The values of K(trans) and v(e) calculated for the reference tissue can then be used to derive a more complete arterial input function including the first pass of the contrast bolus. This new approach was demonstrated using dynamic contrast enhanced magnetic resonance imaging data from rodent hind limb. Values obtained for K(trans) and v(e) in muscle, and the shape and amplitude of the derived arterial input function are consistent with published results.
    Magnetic Resonance in Medicine 12/2010; 64(6):1821-6. · 3.27 Impact Factor
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    ABSTRACT: Magnetic resonance (MR) imaging has been increasingly used in the evaluation of prostate cancer. As studies have suggested that the majority of cancers arise from the peripheral zone (PZ), MR imaging has focused on the PZ of the prostate gland thus far. However, a considerable number of cancers (up to 30%) originate in the transition zone (TZ), substantially contributing to morbidity and mortality. Therefore, research is needed on the TZ of the prostate gland. Recently, MR imaging and advanced MR techniques have been gaining acceptance in evaluation of the TZ. In this article, the MR imaging features of TZ prostate cancers, the role of MR imaging in TZ cancer detection and staging, and recent advanced MR techniques will be discussed in light of the literature.
    World journal of radiology. 05/2010; 2(5):180-7.
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    ABSTRACT: Inflammatory bowel disease, including ulcerative colitis, is characterized by persistent or recurrent inflammation and can progress to colon cancer. Colitis is difficult to detect and monitor noninvasively. The goal of this work was to develop a preclinical imaging method for evaluating colitis. Herein, we report improved MRI methods for detecting and characterizing colitis noninvasively in mice, using high-resolution in vivo MR images and dynamic contrast-enhanced MRI studies, which were confirmed by histologic studies in a murine model of colitis. C57Bl6/J male mice were treated with 2.5% dextran sulfate sodium in their drinking water for 5 days to induce colitis. MR images were acquired using a 9.4-T Bruker scanner from 5-25 days following dextran sulfate sodium treatment. In dynamic contrast-enhanced MRI studies, Gd uptake (K(trans)) and its distribution (v(e)) were measured in muscle and normal and inflamed colons after administering Gd-diethyltriaminepentaacetic acid (Gd-DTPA). T(2)-weighted MR images distinguished normal colon from diffusely thickened colonic wall occurring in colitis (P <0.0005) and correlated with histologic features. Values of K(trans) and v(e) obtained from dynamic contrast-enhanced MRI were also significantly different in inflamed colons compared to normal colon (P < 0.0005). The results demonstrate that both T(2)-weighted anatomic imaging and quantitative analysis of dynamic contrast-enhanced MRI data can successfully distinguish colitis from normal colon in mice.
    Magnetic Resonance in Medicine 04/2010; 63(4):922-9. · 3.27 Impact Factor
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    ABSTRACT: We investigated the influence of the temporal resolution of dynamic contrast-enhanced MRI data on pharmacokinetic parameter estimation. Dynamic Gd-DTPA (Gadolinium-diethylene triamine pentaacetic acid) enhanced MRI data of implanted prostate tumors on rat hind limb were acquired at 4.7 T, with a temporal resolution of approximately 5 sec. The data were subsequently downsampled to temporal resolutions in the range of 15 sec to 85 sec, using a strategy that involves a recombination of k-space data. A basic two-compartment model was fit to the contrast agent uptake curves. The results demonstrated that as temporal resolution decreases, the volume transfer constant (K(trans)) is progressively underestimated (approximately 4% to approximately 25%), and the fractional extravascular extracellular space (v(e)) is progressively overestimated (approximately 1% to approximately 10%). The proposed downsampling strategy simulates the influence of temporal resolution more realistically than simply downsampling by removing samples.
    Magnetic Resonance in Medicine 02/2010; 63(3):811-6. · 3.27 Impact Factor

Publication Stats

519 Citations
147.88 Total Impact Points

Institutions

  • 2000–2014
    • University of Chicago
      • Department of Radiology
      Chicago, Illinois, United States
  • 2003–2008
    • University of Illinois at Chicago
      • Department of Radiology (Chicago)
      Chicago, Illinois, United States