Use of the abdominal aorta for arterial input function determination in hepatic and renal PET studies.

A method using the activity in the abdominal aorta of human and animal subjects to noninvasively estimate blood-pool input function in dynamic, abdominal PET scans is proposed and validated in this paper. Partial volume effects due to the aorta's dimensions are corrected by a semi-automated algorithm based on the transaxial resolution in the reconstructed images. The technique was validated by comparing PET measurements of abdominal aortic activity to well counter measurements of arterial blood samples (eight canine renal studies) and to PET measurements of left ventricular cavity activity (eight human hepatic studies). In renal studies, correlation analysis of the areas subtended by the two input functions yielded an essentially unitary slope (1.03 +/- 0.09), with high correlation (R2 greater than 0.95, p less than 0.001). In hepatic studies, similar values (0.99 +/- 0.03 and R2 greater than 0.85, p less than 0.001) were found. Correlation of the blood flow estimates based on the two input functions and a two-compartment model produced slopes of 1.07 +/- 0.16 and 1.03 +/- 0.07, and correlations of (R2 greater than 0.98, p less than 0.001) and (R2 greater than 0.97, p less than 0.001) for the renal and hepatic studies, respectively. We conclude that noninvasive, accurate measurements of the arterial input function by dynamic PET imaging are possible and represent a clinically viable alternative to arterial blood sampling.     

Leukocyte chemoattraction by 1,2-diacylglycerol.

Previous reports have demonstrated the hydrolysis of inositol phospholipids in polymorphonuclear leukocytes (PMN) in response to chemoattractants and in lymphocytes in response to the mitogen phytohemagglutinin. We investigated the role of 1,2-diacylglycerol, one of the products of receptor-linked phosphatidylinositol hydrolysis, in mediating the migratory response of leukocytes. In an under-agarose migration system, we found 1,2-dioctanoylglycerol to be a strong chemoattractant for human PMN, 6C3HED (a mouse thymic lymphoma), and Jurkat (a human T-cell leukemia). By using a modified Boyden chamber assay, the migratory response of PMN to 1,2-dioctanoylglycerol was determined to be primarily chemotactic. Analysis of structural analogs indicated that both the position and number of acyl chains are important in determining chemoattractant activity. These studies demonstrate that exogenous 1,2-diacylglycerol can stimulate the directed migration of leukocytes. They further suggest that the formation of 1,2-diacylglycerol following receptor-mediated stimulation may represent a common step in the migratory responses of myeloid and lymphoid cells.     

Robot-assisted thoracoscopic brachytherapy for lung cancer: comparison of the ZEUS robot, VATS, and manual seed implantation.

OBJECTIVE: Interstitial brachytherapy is becoming an accepted treatment option for lung cancer patients for whom surgery poses a high risk. Robotic surgery has the potential to deliver brachytherapy seeds into tumors while keeping surgeons at a safe distance from the radioactive source. Our aim was to compare the accuracy, number of attempts, and time needed to place seeds next to a target when using a manual technique, video-assisted thoracoscopic surgery (VATS), and the ZEUS robot for minimally invasive surgery (MIS). METHODS: A brachytherapy seed injector was developed and attached to one of the ZEUS robotic arms. Four subjects each inserted inactive dummy brachytherapy seeds into clear agar-gelatin cubes containing a 1.6-mm stainless steel ball target. Two orthogonal radiographs were taken of each agar cube, and the corresponding distances were measured in triplicate using ImageJ processing software. The mean distance between the center of each seed and the corresponding target was calculated using the Pythagorean theorem. Comparisons were made using analysis of variance, t-tests, and Kruskal-Wallis tests, as appropriate. RESULTS: A total of 384 tests (128 for each technique) were performed. The median accuracies for the manual technique, VATS, and ZEUS were 1.8 mm (range: 0.9-6.7 mm), 2.4 mm (range: 1.0-11.3 mm), and 3.6 mm (range: 1.3-16.7 mm), respectively (p < 0.01). The median numbers of attempts for the manual technique, VATS, and ZEUS were 1 (range: 1-5), 4 (range: 1-14), and 3 (range: 1-20), respectively (p < 0.01). The median times for the manual technique, VATS, and ZEUS were 3.0 s (range: 1-43 s), 86.5 s (range: 6-372 s), and 64.5 s (range: 5-356 s), respectively (p < 0.01). CONCLUSIONS: The manual technique is the most accurate, least traumatic, and fastest method of inserting seeds into tumors. The ZEUS robotic platform was able to place seeds beside a target within a clinically acceptable distance, with an acceptable amount of trauma and time required. It achieved results equal to or better than those obtained with VATS.     

Comparison of airway diameter measurements from an anthropomorphic airway tree phantom using hyperpolarized 3He MRI and high-resolution computed tomography.

An anthropomorphic airway tree phantom was imaged with both hyperpolarized (HP) 3He MRI using a dynamic projection scan and computed tomography (CT). Airway diameter measurements from the HP 3He MR images obtained using a newly developed model-based algorithm were compared against their corresponding CT values quantified with a well-established method. Of the 45 airway segments that could be evaluated with CT, only 14 airway segments (31%) could be evaluated using HP 3He MRI. No airway segments smaller than approximately 4 mm in diameter and distal to the fourth generation were adequate for analysis in MRI. For the 14 airway segments measured, only two airway segments yielded a non-equivalent comparison between the two imaging modalities, while eight more had inconclusive comparison results, leaving only four airway segments (29%) that satisfied the designed equivalence criteria. Some of the potential problems in airway diameter quantification described in the formulation of the model-based algorithm were observed in this study. These results suggest that dynamic projection HP 3He MRI may have limited utility for measuring airway segment diameters, particularly those of the central airways.     

Hip fractures: failure of fixation and outcome of salvage arthroplasty

Between 1999 and 2005, we treated 41 patients with a total hip arthroplasty for failed fixation of a hip fracture. This study had three purposes: (1) to determine the reason/s for fixation failure (2) to record difficulties/complications encountered in converting to a salvage arthroplasty and (3) to compare the outcome of these patients (Group 1) with a matched group of patients who underwent a primary hip arthroplasty (Group 2). Failure to achieve a good reduction and optimal screw placement was evident in 80% of cases of failed fixation. A high incidence of complications was recorded in the perioperative period during conversion to a salvage arthroplasty. Functional outcome was statistically inferior in Group1; this group also had a higher incidence of complications. Radiographs at 2 years postoperatively showed evidence of femoral stem loosening in 16% of the salvage group compared with 3% in the primary hip arthroplasty group.     

Predictors of employment in substance-using male and female welfare recipients

This study examined predictors of employment among substance-using men and women enrolled in welfare-to-work programs. Participants were 394 welfare applicants assigned to either coordinated care management or usual care for treatment services and job training and followed up for 1 year to track employment outcomes. Common barriers to work were assessed at baseline in four key domains: disabilities, situational barriers, labor capital, and motivation. Results indicated substantial gender differences in the number and profile of work barriers. Among men, work experience and job motivation were the only significant predictors of employment; among women, multiple factors from each barrier domain predicted job acquisition even when controlling for all other significant predictors. Findings suggest that welfare-to-work programs should emphasize job training and job seeking during the early stages of welfare interventions for men and for many women.