Objective: To describe and evaluate a fully automated method for characterizing abdominal adipose tissue from magnetic resonance (MR) transverse body scans. Methods: Four MR pulse sequences were applied: SE, FLAIR, STIR, and FRFSE. On 39 subjects, each abdomen was traversed by 15 contiguous transaxial images. The total abdominal adipose tissue (TAAT) was calculated from thresholds obtained by slice histogram analysis. The same thresholds were also used in the manual volume calculation of TAAT, subcutaneous abdominal adipose tissue (SAAT) and visceral abdominal adipose tissue (VAAT). Image segmentation methods, including edge detection, mathematical morphology, and knowledge-based curve fitting, were used to automatically separate SAAT from VAAT in various 'nonstandard' cases such as those with heterogeneous magnetic fields and movement artefacts. Results: The percentage root mean squared errors of the method for SAAT and VAAT ranged from 1.0 to 2.7% for the four sequences. It took approximately 7 and 15 min to complete the 15-slice volume estimation of the three adipose tissue classes using automated and manual methods, respectively. Conclusion:The results demonstrate that the proposed method is robust and accurate. Although the separation of SAAT and VAAT is not always perfect, this method could be especially helpful in dealing with large amounts of data such as in epidemiological studies.

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Objectives-Real-time magnetic resonance imaging (MRI)-guided cryoablation has been investigated in open MRI systems with low magnetic fields (0.2-0.5 T). More advanced imaging techniques and faster imaging rates are possible at higher magnetic fields which often require a closed-bore magnet design. However, there is very little experience with real-time interventions in closed-bore 1.5 T MRI units. Herein, we report our initial experience with real-time MRI-guided cryoablation of small renal tumors using a prototype balanced steady-state free precession (bSSFP) imaging sequence in a closed-bore 1.5-T MRI system. Materials and Methods-FromAugust 2008 to April 2012, 18 patients underwent MRI-guided cryoablation of small renal tumors. A 1.5-T cylindrical MRI scanner with a 125 cm × 70 cm bore and a prototype bSSFP sequence (BEAT IRTTT) were used to guide the placement of 17-gauge cryoprobes in real time. Ice ball formation was monitored every 3 minutes in one or more imaging planes. Each ablation consisted of 2 freeze-thaw cycles. Contrast-enhanced MRI was performed after the second active thaw period. Follow-up consisted of clinical evaluation and renal protocol computed tomography (CT) or MRI performed at 1, 6, 12, 18, and 24 months and annually thereafter.Results-During the study period, we successfully ablated 18 tumors in 18 patients in 18 sessions. The mean tumor size was 2.2 cm (median, 2 cm; range: 1.2-4.4 cm). The number of cryoprobes used per patient was determined based on tumor size. The mean number of cryoprobes used per patient was 3 (median, 3 cryoprobes; range, 2-4 cryoprobes). Fifty-six cryoprobes, 9 biopsy needles, and 2 hydrodissection needles were successfully placed under real time MRI guidance using BEAT IRTTT sequence. Hydrodissection under MRI guidance was successfully performed in 4 patients. In each patient, contrast-enhanced MRI performed after the second active NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript thaw period revealed a sharply defined avascular zone surrounding the targeted tumor, which confirmed complete ablation of the tumor with adequate margins. Although contrast media slowly accumulated in the targeted tumor in 9 patients immediately after the procedure, follow-up imaging studies performed at a mean of 16.7 months revealed no contrast enhancement within the ablation zone in these patients. Disease-specific, metastasis-free, and local recurrence-free survival rates were all 100%.Conclusions-Real-time placement and manipulation of cryoprobes during MRI-guided cryoablation of small renal tumors in a closed-bore, high-magnetic field scanner is feasible.Technical and clinical success rates are similar to those of patients who undergo CT-guided radiofrequency ablation or cryoablation of small renal tumors. Our findings suggest that MRIguided ablation has several advantages over CT-guided ablation, including real-time guidance for probe placement, multiplanar imaging, exquisite soft tissue contrast, and lack of ionizing radiation.

In this paper, we propose a microfluidic device capable of generating a retarding flow field for the sorting and separation of human motile sperm in a high-throughput manner. The proposed sorting/separation process begins with a rapid flow field in a straight-flow zone to carry sperm into a sorting zone to maintain the sperm's mobility. The sorting zone consists of a diffuser-type sperm sorter to differentiate sperm with different motilities based on the flowing upstream nature of human sperm in a retarding flow field. The dead sperm will then be separated from the live ones by passing through a dumbbell flow field to the outlet for disposal. The proposed flowing upstream sperm sorter (FUSS) is designed to imitate the selection mechanism found in the female body when sperm swim into the uterus. The experimental results demonstrate the utility of this device with regard to throughput (approximately 200 000 sperm per minute and a maximum of 200 million cells per mL), efficiency (90% of selected sperm are mobile), and the ability to select sperm with high motility (∼20% of sperm with a velocity exceeding 120 μm s). The proposed device is suitable for intrauterine insemination as well as in vitro fertilization thanks to the highly efficient sorting process not interfering with the natural function and energy resource of human sperm.