Xiaobing Fan

University of Chicago, Chicago, Illinois, United States

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Publications (65)147.88 Total impact

  • [Show abstract] [Hide abstract]
    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: The purpose of this study was to use high resolution 3D MRI to study mouse mammary gland ductal architecture based on intra-ductal injection of contrast agents. Female FVB/N mice age 12–20 weeks (n = 12), were used in this study. A 34G, 45° tip Hamilton needle with a 25uL Hamilton syringe was inserted into the tip of the nipple. Approximately 20–25uL of a Gadodiamide/Trypan blue/saline solution was injected slowly over one minute into the nipple and duct. To prevent washout of contrast media from ducts due to perfusion, and maximize the conspicuity of ducts on MRI, mice were sacrificed one minute after injection. High resolution 3D T1-weighted images were acquired on a 9.4 T Bruker scanner after sacrifice to eliminate motion artifacts and reduce contrast media leakage from ducts. Trypan blue staining was well distributed throughout the ductal tree. MRI showed the mammary gland ductal structure clearly. In spoiled gradient echo T1-weighted images, the signal-to-noise ratio of regions identified as enhancing mammary ducts following contrast injection was significantly higher than that of muscle (p < 0.02) and significantly higher than that of contralateral mammary ducts that were not injected with contrast media (p < 0.0001). The methods described here could be adapted for injection of specialized contrast agents to measure metabolism or target receptors in normal ducts and ducts with in situ cancers.
    Magnetic Resonance Imaging. 01/2014;
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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: PURPOSE Colon cancer is a leading cause of cancer-deaths in the US. Ulcerative colitis is causally linked to colitis-associated neoplastic progression but is difficult to detect and monitor non-invasively. Goals of this study were to determine MRI characteristics of early colitis-associated colon cancer and to assess vitamin D chemopreventive efficacy. METHOD AND MATERIALS This study included CF1 female control mice (n=12), and mice treated with azoxymethane i.p. and dextran sulfate sodium in the drinking water (n=25) to induce colitis and colon cancer. Mice were fed a Western diet or Western diet supplemented with vitamin D (500 µg/kg chow). Western diets are relatively deficient in vitamin D and calcium. Mice were studied serially using anatomic and dynamic contrast enhanced MRI (DCEMRI) with a Gd-based contrast agent. In vivo MR and ex vivo histological images were co-registered using an agar based color-coded phantom in a flexible tube (2 mm o. d.) that was inserted via the rectum to the cecum. The phantom provided visual and MRI-detectable reference markers to co-register in vivo and ex vivo images. RESULTS We demonstrated that: 1) a visible reference marker could be used to successfully co-register MRI abnormalities with histological features identified in H&E stained sections; 2) T2 values distinguished normal colon from colitis, and from focal neoplastic lesions (p<0.005); 3) Ktrans values assessed by DCEMRI (a measure of perfusion/capillary permeability) reliably distinguished normal colon from tumor (0.12±0.01 min-1 vs. 0.61±0.05 min-1, respectively, p<0.001); 4) blood vessel diameters were >3-fold larger adjacent to early colonic tumors compared to vessels in control mice, suggesting that MRI might be used to detect dilated blood vessels as biomarkers of early colorectal cancer; 5) Vitamin D reduced the number of colonic tumors and degree of inflammation detected by MRI (p<0.001). CONCLUSION A novel technique was successfully developed to co-register MR and histological images. Several reliable image-based markers for colitis and colon cancer were identified. These MRI methods could monitor the chemopreventive efficacy of vitamin D in this model in real time and without sacrifice. CLINICAL RELEVANCE/APPLICATION Non-invasive MRI/DCEMRI studies of colitis and colon cancer in mice will improve understanding of these diseases, produce new MRI markers to improve diagnosis, and guide development of new therapies.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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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: PURPOSE To evaluate the visibility of breast tumors on large specimen MRI, in comparison to specimen radiography and clinical dynamic contrast enhanced MRI (DCE-MRI). METHOD AND MATERIALS Breast specimens (n=15) were imaged with a MR scanner immediately after surgery, with an IRB approved protocol and with the patient’s informed consent. Specimen sizes were at least 5 cm in diameter and about 1 to 4 cm thick. Coronal and axial gradient echo MRI with and/or without fat suppression were acquired over the whole specimen using a 9.4T animal scanner with 72 mm birdcage volume coil. The lesions detected on MRI were compared with specimen radiograph and their volumes were compared with measurements obtained from clinical DCE-MRI. RESULTS Invasive ductal carcinoma (IDC) lesions were easily identified using MRI and the margins were clearly distinguishable from adjacent tissue. However, ductal carcinoma in situ (DCIS) lesions were not clearly discernible and were diffused with poorly defined margins on MRI. All calcifications associated with DCIS were visualized on specimen radiograph. The calcifications are only visible on MRI when the DCIS component is surrounded by an IDC lesion. The volumes of IDC measured on specimen MRI were not significantly different from those measured on DCE-MRI. CONCLUSION 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 is a technical challenge in visualization of DCIS lesions. Further improvement is necessary in visualization of DCIS lesions in order to aid pathologists in routine assessment of specimens, thus contributing to better treatment of breast cancer patients. CLINICAL RELEVANCE/APPLICATION High magnetic field specimen MRI provides better visualization of IDC lesions than radiography. Protocols and techniques developed in this study could be used to aid pathologists in routine analysis.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
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    ABSTRACT: PURPOSE To monitor and evaluate pancreatic β-cell activity in the normal and diabetic pancreas using manganese enhanced MRI (MEMRI). METHOD AND MATERIALS Five normal and six diabetic adult Lewis rats were imaged on a 9.4T scanner. Diabetes was induced by streptozotocin treatment (60mg/kg body wt). Mn enhanced axial imaging was acquired on 16 slices through the pancreas using a Magnetization Prepared Rapid Acquisition Gradient Echo pulse sequence pre-contrast and during an IV Mn bolus (3.4g/kg body wt) and an IP glucose bolus (0.75g/kg body wt) at ~30 and ~60 min, respectively. Pancreatic regions of interest (ROIs) were drawn and average signal intensities were calculated. Then, the signal enhancement due to Mn (ΔSm = (Sm-Spre)/Spre) and glucose ( ΔSg = (Sg-Sm)/Spre) were calculated, where Spre, Sm, Sg are pre-contrast, post-Mn, and post-glucose signals, respectively. Finally, a weighted average of the signal enhancement in a volumetric ROI was calculated for each rat. In addition, serum insulin and tissue Mn concentration were measured via ELISA and atomic absorption, respectively. RESULTS Post-Mn relative signal enhancement in diabetic rats (2.7±1.2) was significantly lower than normal rats (5.6±1.5) (p<0.005). Similar results were observed in normal versus diabetic rats (0.93±0.44 vs 0.16±0.43) post-glucose administration (p<0.02). Atomic absorption data revealed that Mn concentrations in the body and tail of pancreas were ~2x greater post-glucose than baseline. Insulin concentration was significantly increased following glucose administration in normal but not in diabetic animals. CONCLUSION Elevated MEMRI contrast in the normal pancreas compared to the diabetic was supported by increased Mn content via atomic absorption. β-cell functionality was not affected by Mn as measured by glucose responsive insulin levels. MRI monitoring of β-cell mass and function is likely to detect a therapeutic window resulting in efficient pharmaceutical response and clinical benefit. CLINICAL RELEVANCE/APPLICATION Functional imaging of the pancreas would be instrumental in the development of novel therapies aimed at maintaining or increasing pancreatic function.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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    ABSTRACT: PURPOSE To use an MR-guided FUS system to create internal fiducial tattoo marks that are detectable visually and by MRI, CT, and ultrasound using a live rabbit model. METHOD AND MATERIALS New Zealand rabbits were anesthetized, their hind limb placed in a degassed water bath. An integrated MRgFUS platform (Sonalleve 1.5T, Philips Healthcare) was used for sonications and MR guidance. Images were acquired using a 3D T2-w Turbo spin echo sequence (TR/TE =1000/130 msec, voxel size=1.2 mm). Dynamic temperature monitoring was performed using 2D fast field echo EPI (slice thickness 7mm, in plane resolution 1.25mm, temporal resolution 2.9 s). A variety of ultrasound powers (50-140 W), durations (5-120 sec), delays (time between sonications varies from 15-90 sec) and combinations were tested. After sonication, rabbits were sacrificed and imaging was performed using a Siemens 15L8w-S ultrasound and Philips Brilliance Big Bore CT. Surgical excision of the lesions was performed and documented photographically. RESULTS Using a combination of pulsed and continuous wave focused ultrasound, internal marks were created that could be detected on MRI, US, CT and with visual inspection at the time of surgical excision. MRI shows distinct and isolated tattoo marks generally presenting as a contiguous oval involving multiple muscle bundles. US shows a focal ovoid area of increased echogeneity that suggests focal hemorrhage. CT shows an abnormal oval structure in the rabbit thigh muscles that is consistent with marks detected by US. Visual inspection allows clear recognition of white and red tissue changes. CONCLUSION We have developed a method for marking in vivo animal muscle tissues. MRgFUS-generated tattoos are conspicuous on clinical ultrasound, CT and MRI. These marks or internal tattoos can guide surgical procedures. They can also provide fiducials for deformable registration of on-board cone-beam CT to planning images and can assist in treatment planning and real-time adjustments during radiotherapy. CLINICAL RELEVANCE/APPLICATION Successful development of a conspicuous FUS tattoo will provide new internal landmarks to guide surgeons and radiation oncologists.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 11/2011
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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

Publication Stats

543 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