Evaluation of computer-assisted image enhancement in minimal invasive endoscopic surgery.

OBJECTIVES: This paper focuses on the evaluation of the usage of computer-aided image processing methods for minimal invasive surgery. During video endoscopy of visceral cavities the images are displayed directly on the monitor without further processing. In the course of the operation the former good quality of the images decreases due to typical disturbances like bleeding, smoke or flying particles. These disturbances can be reduced by using image processing methods like color normalization, temporal filtering or equalization. METHODS: In this double-blinded analysis, 14 surgeons with different levels of experience evaluated 120 image pairs and 5 image sequences, directly comparing original and processed images or movies. RESULTS: Color normalization and equalization proved to significantly enhance video endoscopic images. With regard to temporal filtering, an improvement could be seen in the image sequences with filter size 5 being a greater enhancement than filter size 3. Comparing the state of experience and its influence on the results, it occurred that the experienced surgeons preferred the original color while altogether agreeing that the color-normalized images were better. CONCLUSIONS: The results obtained in the present evaluation show that the image processing methods which were used can significantly improve the quality of video endoscopic images. As a result of this, necessary lavages of the operated area are reduced and a better overview and orientation for the surgeon can be reached.

Light fields for minimal invasive surgery using an endoscope positioning robot.

OBJECTIVES: To generate a fast and robust 3-D visualization of the operation site during minimal invasive surgery. METHODS: Light fields are used to model and visualize the 3-D operation site during minimal invasive surgery. An endoscope positioning robot provides the position and orientation of the endoscope. The a priori un-known transformation from the endoscope plug to the endoscope tip (hand-eye transformation) can either be determined by a three-step algorithm, which includes measuring the endoscope length by hand or by using an automatic hand-eye calibration algorithm. Both methods are described in this paper and their respective computation times and accuracies are compared. RESULTS: Light fields were generated during real operations and in the laboratory. The comparison of the two methods to determine the unknown hand-eye transformation was done in the laboratory. The results which are being presented in this paper are: rendered images from the generated light fields, the calculated extrinsic camera parameters and their accuracies with respect to the applied hand-eye calibration method, and computation times. CONCLUSION: Using an endoscope positioning robot and knowing the hand-eye transformation, the fast and robust generation of light fields for minimal invasive surgery is possible.

[Generalized compartment syndrome after excessive drinking. A rare complication of psychological disorders?]. / Das generalisierte Kompartmentsyndrom nach exzessivem Trinken. Seltene Komplikation psychischer Erkrankungen?

Psychogenic polydipsia can lead to compartment syndromes, which is too infrequently considered in psychiatric patients who binge-drink on hypotonic fluids. If masked by the leading clinical presentation of cerebral edema, compartment syndromes of the extremities may be diagnosed too late or remain undetected. Based on a literature review and case report, we discuss additional factors and the specific features of diagnosis and treatment.

Studies on the reduction of aortic calcification by alkali citrates in an ex vivo tissue preparation in the rat.

The effect of orally administered alkali citrates on the calcification of arterial vessel was studied in the rat. Freshly dissected aortic segments were placed in Millipore diffusion chambers and grafted intraperitoneally. Within 21 days calcification of the media had developed. Under treatment with 2.1 mmol citrate per animal and day a significant decrease in histologically detectable calcification areas occurred, as assessed by greatest thickness and longitudinal expansion. This effect was more pronounced with potassium citrate and potassium sodium citrate, and less marked with sodium citrate. The calcium and phosphorus content of aortic tissue remained unchanged, but magnesium increased significantly. The spheroid particles deposited in the media were characterized in more detail by electron microscopy and elemental microanalysis, X-ray diffraction, and determination of the molar calcium-phosphorus ratio. The combined data suggest that in the model selected for studying biocalcification not mature hydroxyapatite but some precursor of this substance is deposited, and that in animals receiving alkali citrate treatment deposition of amorphous calcium phosphate is likely. It is concluded that in the ex vivo aortic wall preparation oral alkali citrates a) bring about a reduction in calcification areas in the media layer, b) impair the maturation of hydroxyapatite and its deposition in the arterial tissue; c) promote the accumulation of magnesium. Whether these results are of significance for the calcification of arteries in situ and treatment regimens is unknown.

Mesorectal lymph node dissection: is it beneficial?

Locoregional recurrences and distant metastases are the determinants of the long-term prognosis following curative resection of rectal carcinoma. While distant metastases cannot be affected by the surgical treatment of the primary tumor, avoidance of local recurrence by the surgeon is of special significance as the predominant prognostic factor. Analysis of the long-term results achieved by various surgeons led to the concept of mesorectal excision - the removal of the rectum together with all additional tissue invested by the adjacent visceral fascia, that is, fatty tissue, lymph nodes, and lymphatic vessels, by sharp dissection of the appropriate anatomical plane. In our own patient material the 5-year survival rate following R0 resection was 85% for all stages, provided no local recurrence developed. This contrasts with a figure of only 23% in those who did develop local recurrence. The local recurrence rate decreased from 39.4%, with a 50% 5-year survival rate in 1974, to 9.8% and a 71% survival rate in 1991, although the rate of distant metastases remained constant. Among the patients treated between 1988 and 1994 the local recurrence rate was determined by depth of infiltration (1987 UICC classification: pT1 0%, pT2 10%, pT3 14%, pT4 28%), extent of lymph node infiltration (pN0 6%, pN1 15%, pN2 26%, pN3 25%), grading (G1 9%, G2 12%, G3 21%), and location within the rectum (upper third 13%, middle third 8%, lower third 17%), with combinations of unfavorable initial factors leading to higher local recurrence rates. The elevated local recurrence rates seen in the 1970s, in particular in the case of tumors of the lower third, were traced retrospectively to incomplete mesorectal excision, the implementation of which reduced the local recurrence rate initially to less than 10%, and then to the current 4.1%. From the oncological point of view, mesorectal excision must be considered to confer considerable benefit. In the case of carcinomas of the upper third of the rectum, mesorectal resection carried out to just 5 cm below the lower tumor edge is sufficient, however, without coning, while deeper carcinomas mandate total mesorectal excision.

[Possibilities for early ambulation and long-term outcome of treatment of trochanteric fractures with the dynamic hip screw and gamma nail]. / Frühmobilisationsmöglichkeiten und Langzeitergebnisse der Behandlung trochanterer Frakturen mit der Dynamischen Hüftschraube und dem Gamma-Nagel.

We studied early mobilisation and long-term results in patients treated with the dynamic hip screw (DHS) or gamma nail after trochanteric fractures. Both implants showed good results in stable fractures; patients with unstable fractures were able to walk with full load earlier when treated with the gamma nail. We recommend the DHS for stable and the gamma nail for unstable trochanteric fractures.

Differential effects of surgical sympathetic block on sudomotor and vasoconstrictor function.

OBJECTIVE: To assess the effects of a surgical block of the sympathetic chain at the T2 level on vasoconstriction and palmar sweating in patients with palmar hyperhidrosis. METHODS: In a prospective study, sympathetic vasoconstriction was measured by laser-Doppler imaging and by computer-assisted infrared thermography (rewarming kinetics following immersion of both hands in ice water [4 degrees C, 30 seconds]) in 61 patients with hyperhidrosis preoperatively and 2 days and 3 months postoperatively. In addition, palmar sweating preoperatively and 3 months postoperatively was assessed by quantitative sudometry. RESULTS: Before surgery, rewarming kinetics was significantly slower in the patients (n = 61) than in the healthy control subjects (n = 28). Two days after the block, baseline skin temperature increased by about 5 degrees C, and rewarming was massively accelerated in each of the patients. Three months postoperatively, rewarming kinetics was still accelerated in 36 hands, was unchanged from the preoperative condition in 42, and had worsened in 12. These changes were accompanied by parallel alterations of laser-Doppler flux. However, palmar sweating was massively reduced in all but one patient, irrespective of the different rewarming kinetics. CONCLUSIONS: T2 sympathectomy leads to long-lasting inhibition of palmar sweating, which does not correlate to loss of vasoconstriction. Recurrent and enhanced vasoconstrictor function 3 months following endoscopic sympathetic block has major implications for its use to treat enhanced vasoconstriction.