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Author(s): O'Bryant, Sid E; Johnson, Leigh A; Barber, Robert C; Braskie, Meredith N; Christian, Bradley; Hall, James R; Hazra, Nalini; King, Kevin; Kothapalli, Deydeep; Large, Stephanie; Mason, David; Matsiyevskiy, Elizabeth; McColl, Roderick; Nandy, Rajesh; Palmer, Raymond; Petersen, Melissa; Philips, Nicole; Rissman, Robert A; Shi, Yonggang; Toga, Arthur W; Vintimilla, Raul; Vig, Rocky; Zhang, Fan; Yaffe, Kristine; HABLE Study Team | Abstract: IntroductionMexican Americans remain severely underrepresented in Alzheimer's disease (AD) research. The Health a Aging Brain among Latino Elders (HABLE) study was created to fill important gaps in the existing literature.MethodsCommunity-dwelling Mexican Americans and non-Hispanic White adults and elders (age 50 and above) were recruited. All participants underwent comprehensive assessments including an interview, functional exam, clinical labs, informant interview, neuropsychological testing, and 3T magnetic resonance imaging (MRI) of the brain. Amyloid and tau positron emission tomography (PET) scans were added at visit 2. Blood samples were stored in the Biorepository.ResultsData was examined from nn=n1705 participants. Significant group differences were found in medical, demographic, and sociocultural factors. Cerebral amyloid and neurodegeneration imaging markers were significantly different between Mexican Americans and non-Hispanic Whites.DiscussionThe current data provide strong support for continued investigations that examine the risk factors for and biomarkers of AD among diverse populations.

PURPOSE We summarize the AAPM TG248 Task Group report on interoperability assessment for the commissioning of medical imaging acquisition systems in order to bring needed attention to the value and role of quality assurance testing throughout the imaging chain. METHODS To guide the clinical physicist involved in commissioning of imaging systems, we describe a framework and tools for incorporating interoperability assessment into imaging equipment commissioning. RESULTS While equipment commissioning may coincide with equipment acceptance testing, its scope may extend beyond validation of product or purchase specifications. Equipment commissioning is meant to provide assurance that a system is ready for clinical use, and system interoperability plays an essential role in the clinical use of an imaging system. CONCLUSION The functionality of a diagnostic imaging system extends beyond the acquisition console and depends on interoperability with a host of other systems such as the Radiology Information System, a Picture Archive and Communication System, post-processing software, treatment planning software, and clinical viewers.

Purpose To assess if fully automated localization of the aorta can be achieved using phase contrast (PC) MR images. Materials and Methods PC cardiac-gated MR images were obtained as part of a large population-based study. A fully automated process using the Hough transform was developed to localize the ascending aorta (AAo) and descending aorta (DAo). The study was designed to validate this technique by determining: (i) its performance in localizing the AAo and DAo; (ii) its accuracy in generating AAo flow volume and DAo flow volume; and (iii) its robustness on studies with pathological abnormalities or imaging artifacts. Results The algorithm was applied successfully on 1884 participants. In the randomly selected 50-study validation set, linear regression shows an excellent correlation between the automated (A) and manual (M) methods for AAo flow (r = 0.99) and DAo flow (r = 0.99). Bland-Altman difference analysis demonstrates strong agreement with minimal bias for: AAo flow (mean difference [A-M] = 0.47 ± 2.53 mL), and DAo flow (mean difference [A-M] = 1.74 ± 2.47 mL). Conclusion A robust fully automated tool to localize the aorta and provide flow volume measurements on phase contrast MRI was validated on a large population-based study. J. Magn. Reson. Imaging 2014;40:221–228. © 2013 Wiley Periodicals, Inc.

Purpose To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1- and -maps serially during a single dynamic MRI scan in response to an oxygen challenge. Materials and Methods The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge. Results Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs. Conclusion The free-breathing respiratory-triggered interleaved T1 and sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and data within the abdomen. J. Magn. Reson. Imaging 2013;38:1230–1236. © 2013 Wiley Periodicals, Inc.

Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T₂*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R₂* measurements. The baseline T₂*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R₂* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined.

Purpose To introduce and evaluate the performance of an automated fat quantification method for water-saturated magnetic resonance images. Materials and Methods A fat distribution model is proposed for fat quantification on water saturated magnetic resonance images. Fat from both full- and partial-volume voxels are accounted for in this model based on image intensity histogram analysis. An automated threshold method is therefore proposed to accurately quantify total fat. This method is compared to a traditional full-volume-fat-only method in phantom and human studies. In the phantom study, fat quantification was performed on MR images obtained from a human abdomen oil phantom and was compared with the true oil volumes. In the human study, results of the two fat quantification methods of six subjects were compared on abdominal images with different spatial resolutions. Results In the phantom study, the proposed method provided significantly more accurate estimations of true oil volumes compared to the reference method (P < 0.0001). In human studies, fat quantification using the proposed method gave much more consistent results on images with different spatial resolutions, and on regions with different degrees of partial volume averaging. Conclusion The proposed automated method is simple, rapid, and accurate for fat quantification on water-saturated MR images. J. Magn. Reson. Imaging 2007;26:738–746. © 2007 Wiley-Liss, Inc.

Purpose To compare the performance of a novel water-saturated b-SSFP sequence with that of a conventional T1-weighted turbo spin echo (T1W TSE) sequence for abdominal fat quantification. Materials and Methods A water-saturated, segmented, three-dimensional balanced steady-state free precession (b-SSFP) sequence and a traditional T1W TSE sequence were both employed on phantom and human studies. For phantom studies, a dual-layered phantom with known internal/external oil volumes was imaged using the two sequences. Images obtained by the two sequences were both processed using a computer-aided semiautomatic program for oil volume quantification. For human studies, six volunteers were scanned axially, centered at L2–L3 levels. Signal-to-noise ratio (SNR)fat, contrast-to-noise ratio (CNR)fat-muscle, CNRfat-large bowel, and CNRfat-small bowel were calculated on hand-drawn regions of interest (ROIs), and averaged over all six slices for each subject. Statistical analyses were then performed to determine the SNR and CNR differences between images obtained by the two techniques. Results The phantom studies show that water-saturated b-SSFP offers a significantly closer estimation of true oil volumes compared with that of T1W TSE (P < 0.0001), as well as a more accurate internal/external volume ratio (P = 0.0001). In human studies, three-dimensional water-saturated b-SSFP images demonstrated higher CNR than that of T1W TSE (P < 0.0005), and very close SNRfat (P = 0.045). Conclusion The proposed three-dimensional water-saturated b-SSFP sequence can generate high quality fat-only abdominal images with high CNR and SNR in shorter scan duration than the conventional T1W TSE approach. As images generated by this sequence suffer from no flow artifacts, and are less sensitive to bulk, respiratory, and bowel motion, three-dimensional water-saturated b-SSFP is a faster and more robust method for improving abdominal fat quantification using MRI. J. Magn. Reson. Imaging 2005;21:263–271. © 2005 Wiley-Liss, Inc.