Development of the high energy engineering X-ray (HEX) superconducting wiggler, magnetic measurement, installation, and commissioning.

The High energy Engineering X-ray (HEX) diffraction beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Lab (BNL) is the first high-energy beamline capable of reaching 200 keV for a monochromatic beam. With the 3 GeV electron beam energy for the NSLS-II ring, only the superconducting wiggler (SCW) producing greater than 4 T peak field can cover these ranges with a sufficient number of photons. The 1.2 m-long HEX-SCW has a period length of 70 mm and a field strength on-axis of 4.3 T. It utilizes no liquid helium, and the vertical aperture size of the electron beam vacuum chamber is 8 mm. Unlike regular undulators/wigglers, there is no standard configuration for the magnetic measurement system for superconducting insertion devices. The NSLS-II Insertion Devices group has developed, in collaboration with the vacuum group, a novel in-vacuum Hall mapper with a 1.75 m in-vacuum linear motor and an in-vacuum flip coil system utilizing many commercial-off-the-shelf products. The measurements were conducted at the BNL, and the device was installed in the ring and commissioned. This paper provides a description of the SCW and its magnetic measurement systems, as well as a brief account of the installation and commissioning efforts.

Sensitivity of chest fluoroscopy compared with chest CT and chest radiography for diagnosing hydropneumothorax in association with percutaneous nephrostolithotomy.

OBJECTIVES: Hydropneumothorax (HPTX) is recognized as a potential complication of percutaneous nephrostolithotomy (PCNL), particularly with supracostal access. Postoperative chest radiography (CXR) is routinely used to evaluate the chest after PCNL. We prospectively compared the sensitivity of intraoperative chest fluoroscopy with immediate postoperative portable CXR and postoperative day 1 chest computed tomography (CT) for the detection of pleural fluid. METHODS: A total of 89 consecutive patients (mean age 47.9 +/- 13.3 years; 100 renal units) undergoing PCNL were prospectively evaluated with intraoperative fluoroscopy at the conclusion of the procedure and then with anteroposterior CXR in the postanesthesia care unit and postoperative day 1 noncontrast, thin-cut CT of the kidneys and lung bases. CT imaging of the lung bases comprised the reference standard for detecting pleural fluid. RESULTS: A total of 104 percutaneous renal accesses in 100 renal units, 60 above and 44 below the 12th rib, were used. In 16 cases (16%), a second-stage procedure was performed to clear residual stone fragments detected on post-PCNL CT. HPTX was detected in 1, 8, and 38 cases by initial fluoroscopy, immediate postoperative CXR, and CT scan, respectively. Intervention was necessary in 7 patients. In 2 patients with fluoroscopic evidence of pleural fluid (1 at the initial PCNL and 1 during second-look flexible nephroscopy), intraoperative pleural drainage was performed percutaneously. In the other 5 patients, intervention was determined by the size of the HPTX on chest CT scan (n = 1) or the presence of symptoms (n = 4). In no case was intervention performed on the basis of the immediate postoperative CXR findings when intraoperative chest fluoroscopy was negative. CONCLUSIONS: Intraoperative chest fluoroscopy during PCNL is sufficient to detect clinically significant HPTXs, and, therefore, routine postoperative CXRs are not necessary. However, a high index of suspicion based on clinical symptoms postoperatively should prompt chest imaging.

Radiofrequency coagulation of renal parenchyma: comparison of effects of energy generators on treatment efficacy.

PURPOSE: We compared experimental renal lesions created with temperature-based or impedance-based radiofrequency (RF) generators using normal renal parenchyma in an animal model with protocols recommended by the manufacturer. MATERIALS AND METHODS: Bilateral renal mobilization was completed in seven farm pigs in preparation for RF ablation, and the tines of each RF probe were expanded to a 2-cm diameter. Pigs were sacrificed immediately (N = 3) or at 24 hours (N = 4) after treatment. Lesions were examined grossly and microscopically after hematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide (NADH) staining. RESULTS: Gross lesions were firm and white with a hemorrhagic border, regardless of RF generator. Staining with H&E revealed preservation of renal architecture but loss of distinct cytoplasmic features with both RF systems. Staining for NADH showed no viable cells within the lesions produced by either RF system. Immediately and after a 24-hour survival, the mean sizes of the treatment lesions were 1.6 x 1.8 x 1.3 cm and 2.0 x 1.6 x 1.9 cm, respectively, for the temperature-based RF generator and 2.7 x 2.4 x 2.5 cm and 2.2 x 2.1 x 1.8 cm, respectively, for the impedance-based RF generator. CONCLUSION: Use of a specific RF energy generator with recommended treatment protocols does not appear to affect coagulation of normal renal parenchyma in the porcine model.

Laparoscopic radical nephrectomy: prospective assessment of impact of intact versus fragmented specimen removal on postoperative quality of life.

PURPOSE: We prospectively compared postoperative recovery and quality of life for groups of patients undergoing laparoscopic radical nephrectomy with intact or fragmented specimen removal. PATIENTS AND METHODS: A prospective evaluation of 12 patients having a transperitoneal laparoscopic nephrectomy was completed. In each case, a radical dissection was performed regardless of the surgical indication. Fragmented specimens (N = 7) were extracted at the umbilical port, and intact specimens (N = 5) were extracted through an infraumbilical incision. Demographic and perioperative data including specimen removal incision, narcotic requirements, and recovery interval were recorded. Subjective pain and activity assessments were administered prospectively on postoperative days 1, 2, 7, and 14. RESULTS: The mean incision length for intact specimen removal was 7.6 cm and that for fragmented removal was 1.2 cm (P < 0.05). Pain and activity self-assessments improved over time in each group. No significant differences in pain or activity scores were noted between treatment groups at any queried interval. Time to return of normal activity was not significantly different in the two groups. CONCLUSIONS: In this pilot study, no subjective or objective advantage was demonstrated for kidney fragmentation during laparoscopic radical nephrectomy. A larger randomized study is required to better assess any clinical advantage to specimen morcellation.

Laparoscopic radiofrequency thermal ablation of renal tissue with and without hilar occlusion.

PURPOSE: Few studies have evaluated the effect of radiofrequency thermal ablation on renal tissue, although it has been used clinically to treat small renal masses. We studied the size and histology of lesions created with radiofrequency thermal ablation administered via the laparoscopic approach with and without hilar occlusion in a porcine model. MATERIALS AND METHODS: The lower pole of each kidney was exposed laparoscopically in 11 farm pigs. In each kidney a 7-electrode dry radiofrequency thermal ablation probe was inserted at an identical location and deployed to a diameter of 2 cm. Energy was applied for 8 minutes at an average temperature of 100C. The left renal hilum of each pig was clamped during radiofrequency thermal ablation. Two pigs were sacrificed immediately, and 3 each were sacrificed at 24 hours, 2 and 4 weeks. The size and shape of the lesions created were measured and examined histologically. RESULTS: There were no intraoperative or postoperative complications. Laparoscopic ultrasound confirmed probe placement but did not monitor lesion progression. Acutely lesions were firm and white with a small adjacent hemorrhagic zone. Histological evaluation revealed preserved renal architecture but the loss of distinct cytoplasmic features. Nicotinamide adenine dinucleotide staining demonstrated no viable cells within the lesions. In surviving animals pelvicaliceal integrity was preserved. In the 2 and 4-week survival groups kidneys treated with hilar occlusion had larger lesions than nonoccluded kidneys but the differences were not significant at 4 weeks (3.2 x 2.7 x 2.5 cm. and 3.5 x 1.7 x 2.0, respectively, p >0.05). Histologically untreated parenchyma of hilar occluded kidneys demonstrated changes consistent with chronic pyelonephritis. In 1 kidney radiofrequency thermal ablation with hilar occlusion resulted in complete lower pole loss at 4 weeks. CONCLUSIONS: In the porcine model renal radiofrequency thermal ablation creates rapid and completely devitalized lesions of consistent size and shape. Hilar occlusion may result in slightly larger lesions but risks damage to the whole renal unit.

Renal parenchymal injury after standard and mini percutaneous nephrostolithotomy.

PURPOSE: Mini percutaneous nephrostolithotomy was developed for use in children and in adults with a reduced renal reserve to minimize the morbidity and renal parenchymal damage presumed to occur with traditional percutaneous nephrostolithotomy. We compared the extent of renal injury incurred by different sized nephrostomy tracts in female farm pigs undergoing 11 or 30Fr percutaneous nephrostomy. MATERIALS AND METHODS: Bilateral percutaneous nephrostomy was attempted via a mid or lower pole calix under fluoroscopic guidance in 6 pigs. In 2 pigs the procedure was unsuccessful on 1 side, leaving 5 successfully established nephrostomy tracts on each side. In each pig the right percutaneous tract was dilated with a 28Fr dilating balloon and a 30Fr Amplatz working sheath (Cook Urological, Spencer, Indiana) was positioned in the collecting system. On the left side an 11Fr sheath (Cook Urological) was placed. The sheaths were removed after 1 hour and nephrostomy tubes (22Fr on the right and 8Fr on the left side) were left in place overnight and then removed. Six weeks later the pigs were sacrificed and the kidneys were harvested. The nephrostomy tracts were identified grossly and examined microscopically, and the fibrotic scar was measured using digital analysis. The volume of scar was estimated using the calculated volume of a cylinder. RESULTS: At kidney harvest all 10 kidneys appeared grossly normal. No intra-abdominal urine collection or perirenal hematoma was noted. Mean estimated scar volume of the 30 and 11Fr tracts was 0.29 and 0.40 cc, which translates into a mean fractional loss of parenchyma of 0.63% and 0.91%, respectively (p not significant). CONCLUSIONS: Renal parenchymal damage resulting from the creation of a nephrostomy tract is small compared to overall renal volume regardless of the size of the nephrostomy tract. Consequently there is no advantage to the use of a small access sheath based on renal scarring alone.

Laparoscopic gonadectomy and excision of müllerian remnant in an adult intersex patient.

Laparoscopy can assist in the diagnosis and treatment of intersex patients. We report a rare case in which laparoscopic gonadectomy and hysterosalpingectomy were performed in a phenotypically-male intersex patient first diagnosed in adulthood.

Hemostatic laparoscopic partial nephrectomy: cable-tie compression.

OBJECTIVES: Laparoscopic partial nephrectomy (LPN) has generally been reserved for small exophytic lesions because of the limited hemostatic capabilities when excising large segments of renal parenchyma. To overcome this problem, we investigated a technique of laparoscopic reversible, regional hypoperfusion using a cable-tie to minimize blood loss and optimize exposure. METHODS: Ten domestic pigs underwent LPN after securing a cable-tie around one pole of the kidney and tightening it until the distal parenchymal surface blanched completely. Eight large amputations involving the collecting system and eight smaller amputations excluding the collecting system were performed using laparoscopic scissors. Fibrin glue was applied to seal the cut surface prior to cable-tie removal. Four pigs (4 large and 4 small amputations) were killed immediately and methylene blue was injected retrograde into the ureter to identify collecting system leaks. The remaining 6 pigs (4 large and 4 small amputations) were killed 4 weeks later and retrograde urograms were performed to assess collecting system integrity. RESULTS: Median cable-tie ischemia time was 15 minutes (range 7 to 48) and median blood loss was 30 mL (range 10 to 300). In each case, hemostasis was attained with fibrin glue. In the survival group, all 4 small amputations healed with a fibrotic scar. In the large amputation group, 1 animal died from urinary extravasation on postoperative day 4. The collecting systems of the remaining 3 pigs sealed completely. CONCLUSIONS: In the porcine model, cable-tie-assisted LPN provides an almost bloodless surgical field that facilitates rapid resection of large renal segments and hemostasis during a short ischemic period. We anticipate that this technique will broaden the clinical application of LPN.

Contrast sensitivity norms for the Mentor B-VAT II-SG video acuity tester.

The Mentor B-VAT II-SG video acuity tester is a high-resolution video system designed to present many of the targets used in standard vision examinations (Snellen optotypes, clock charts, etc.). The SG model also presents sinusoidal gratings at various spatial frequencies and contrasts, making it possible to measure contrast sensitivity functions (CSF's). Using this system, we measured CSF's in a group of 69 young observers with well corrected vision. Contrast sensitivity scores were obtained at each of five spatial frequencies. A total of 5710 trials was presented. The mean contrast sensitivity scores of our group agree well with norms of other available CSF measurement systems, provided that the low spatial frequency truncation effects of each system are taken into account. A random subset of the group was retested 1 month later; no significant differences were found, demonstrating the reliability of the measurements. The data of this study should aid the clinician in identifying visual disorders. The data may be used to determine quantitative deviations from the norms or as a rapid screening test.

Effect of luminance level on contrast sensitivity in myopia.

High myopia results in stretching of the retina. We expected this stretching to impair visual function. Accordingly, we tested static and dynamic spatial contrast sensitivity and temporal modulation sensitivity at photopic, mesopic, and scotopic luminance levels. None of these functions differed significantly for high myopes (6 to 10 D) relative to age-matched normals. We conclude that retinal stretching need not induce visual deficits.

The shape of the high frequency flicker sensitivity curve.

For a light flickering with a modulation amplitude delta L, there is a single frequency f above which the light appears steady (fused). The relationship between delta L and f has been measured often under a variety of conditions, but its mathematical form is disputed. Three candidate functions have been proposed: (1) log delta L alpha f [Ferry-Porter law], (2) log delta L alpha f1/2 [diffusion model], and (3) log delta L alpha log f [cascaded integrator model]. Although all three functions roughly fit flicker fusion data (after appropriate linear transformation), they differ in curvature. We compared these functions using the general expression (4) log delta L alpha f lambda, where lambda denotes a curvature parameter. Functions (1)-(3) are special cases of (4) with lambda = 1, 0.5, and 0 respectively. When applied to 35 sets of flicker fusion data, the mean values of the best fitting lambda for each data-set was 0.919 (95% confidence interval 1.027 to 0.812). We conclude that the Ferry-Porter law describes most data better than a diffusion model, and that an integrator model deviates consistently in every case.

High myopia does not affect contrast sensitivity.

The axial elongation of high myopia is known to induce tangential stretching forces on the retina. Such forces might be expected to compromise retinal circuitry and thus affect the temporal and spatial contrast sensitivity function. In fact, we find that simple high myopes have normal contrast sensitivity for stationary gratings, moving gratings, and uniform field flicker. This suggests that, unlike many other retinal disease processes, the high myope's retina retains its normal integrity until the outer retina is compromised.

Three clinical tests of the spatial contrast sensitivity function: a comparison.

The purpose of this study was to establish a practical basis of comparison among three clinical tests designed to measure an observer's spatial contrast sensitivity function (CSF): the AO contrast sensitivity test plates (Arden grating test), the Vistech VCTS 6500 chart, and the Nicolet CS-2000 contrast sensitivity testing system (Optronics system). Each test was administered under standard conditions to a randomly selected subset of 71 normal observers. Scores were converted to absolute contrast and spatial frequency units for comparison. Results were similar for all three tests at intermediate and high spatial frequencies, but at low spatial frequencies the Vistech and Optronics tests yielded significantly lower sensitivity scores than the AO plates. This discrepancy is probably due to area truncation.

The aesthetics of the preauricular graft in facial reconstruction.

In the past six years we have used 55 preauricular full-thickness skin grafts to reconstruct defects of the nose, medial canthal area, forehead, and lip. Results have been good to excellent in all cases. The donor incision is the same one used for a rhytidectomy in which the sole reason for operation is cosmetic. Hence the donor scar in this area must certainly be considered cosmetically acceptable.