False-negative frozen section of sentinel lymph node biopsy for breast cancer

A prospective study is presented of frozen section examinations (FS) performed in parallel with 265 consecutive sentinel lymph node procedures (SLNP) over a 20-month period. The final pathological study included immunohistochemistry (IHC) for keratin if the haematoxylin-eosin (HE)-stained section was tumour free. FS correctly identified node-positive or node-negative axillae in 235 cases. In 28 SLNPs the final examination gave a positive result not detected in the FS, resulting in reoperation. In 21 of these false-negative (FN) cases micrometastases (MIM) were present. There were no false-positive cases, but in two cases of lobular carcinoma the findings in the FS were equivocal, the final reports recording metastases in one but not in the other. Lobular carcinoma and other less common subtypes of carcinoma were overrepresented, ductal carcinoma not otherwise specified (NOS) being less likely to affect the FN findings.

Bilddatengestützte Navigation zur Steuerung der interstitiellen Lasertherapie von vaskulären Malformationen im Kopf- und Halsbereich / Image-guided Interstitial Laser Treatment of Vascular Malformations in the Head and Neck

Laser-induced interstitial thermal therapy (LITT) is a proven minimally invasive surgical technique for the treatment of haemangiomas and vascular malformations, and various tumours. The intra-lesion application of thermal energy destroys regional tissue. The percutaneous placement of the laser fibre for photocoagulation is done without the benefit of direct visual control. Image-data-based LITT was performed in patients (five procedures) with extensive venous malformations in the maxillofacial area. The system comprised a specially developed Nd:YAG laser fibre introducer set used in conjunction with fused high-resolution computed tomography, and magnetic resonance image-data--based surgical navigation. In all cases, follow-up examination clearly showed a diminishment in tumour volume, and all patients reported significant subjective improvement. The results suggest that navigation-guided LITT can be performed safely, preserving vital structures from collateral thermal damage.

The Metric-FF Planning System: Translating ``Ignoring Delete Lists'' to Numeric State Variables

Planning with numeric state variables has been a challenge for many years, and was a part of the 3rd International Planning Competition (IPC-3). Currently one of the most popular and successful algorithmic techniques in STRIPS planning is to guide search by a heuristic function, where the heuristic is based on relaxing the planning task by ignoring the delete lists of the available actions. We present a natural extension of ``ignoring delete lists'' to numeric state variables, preserving the relevant theoretical properties of the STRIPS relaxation under the condition that the numeric task at hand is ``monotonic''. We then identify a subset of the numeric IPC-3 competition language, ``linear tasks'', where monotonicity can be achieved by pre-processing. Based on that, we extend the algorithms used in the heuristic planning system FF to linear tasks. The resulting system Metric-FF is, according to the IPC-3 results which we discuss, one of the two currently most efficient numeric planners.

H�mangiome und vaskul�re Malformationen im Kopf- und Halsbereich

The treatment of paediatric patients with extended vascular anomalies in the head and neck requires a multidisciplinary approach involving paediatricians, maxillofacial surgeons, dermatologists and radiologists. Therapeutic strategies are based on an internationally accepted classification of vascular anomalies, which distinguishes haemangiomas and vascular malformations. Whereas haemangiomas are endothelial proliferations, vascular malformations are considered to be developmental anomalies which are classified into high-flow or low-flow lesions and, according to their vascular channels, into capillary, lymphatic or venous malformations. In this review we present guidelines for the diagnostic assessment of paediatric patients with vascular anomalies in the head and neck region. The indications for treatment are discussed and therapeutic options are outlined.

A new electrochemically graded hydroxyapatite coating for osteosynthetic implants promotes implant osteointegration in a rat model

Hydroxyapatite (HAP) is widely used as an osteoconductive coating for orthopedic implants. So far standard coating methods like plasma spraying produce a relatively thick coating layer (>30 microm). In addition, the chemical structure of the HAP may be altered because of the heating throughout the coating process. This may have negative effects on the coating stability, implant fixation, and induction of bone formation. The relatively thick layer may detach from the implant with the risk of wear debris. In the present study the potential of a newly developed HAP coating of implants on osteointegration was investigated in a rat model. The coating method, based on an electrochemical process, is applied in a graded manner and results in a biodegradable HAP coating with a thickness of approximately 2 mum. Coated versus uncoated titanium Kirschner wires (1.4-mm diameter) were inserted into the medullary cavity of the right femora of 5-month old female Sprague Dawley rats (n=36) in a retrograde fashion. Throughout an experimental period of 2 months the osteointegration was traced radiologically. After this time the animals were sacrificed and the implant integration was tested biomechanically with the use of a push-out test. To analyze the bone-implant interface, histological sections (80 mum) were investigated with an image analyzing system. The biomechanical testing revealed a significantly higher implant fixation in the group treated with the HAP-coated implant (shear strength: 27.8 +/- 6.7 MPa) compared to control (shear strength: 8.08 +/- 3.4 MPa). The histological analyses demonstrated a better ingrowth of the implants in the HAP group with significantly more direct bone-implant contacts compared to the control group. The results demonstrate that the HAP coating promotes implant osteointegration in a rat model.

[Registration using three-dimensional laser surface scanning for navigation in oral and craniomaxillofacial surgery]

INTRODUCTION

Recent innovations in laser scanning technology provide a potentially useful tool for three-dimensional surface registration for image-guided surgery. The purpose of this study is to evaluate the clinical reliability of this technique in oral and maxillofacial surgical procedures using image-guided navigation.

METHODS

In an experimental step, a stable anthropomorphic skull model with prelabeled markers was scanned and registered with laser surface scanning (z-touch, BrainLAB) and marker- based algorithms. The registration protocol was then repeated 25-times. Root mean square error (RMSE) and target difference values were compared for their suitability for this application. Twelve patients with different indications for oral and maxillofacial surgery were planned for image-guided surgery using a passive infrared surgical navigation system (VectorVision, BrainLAB). Preoperative computed tomography (CT) scans were carried out with newest 16-line multisclice CT-scanner (Siemens Somatom Sensation 16). The new markerless laser surface scanning technique was applied in all intraoperative patient registrations. Registration error was noted. The clinical application accuracy was determined for anatomical landmark localization deviation.

RESULTS

In the experimental protocol a mean registration error (RMSE) or target difference of 1.3 (0.14) or 2.08 (0.49) mm for laser scanning and 0.38 (0.01) or 0.99 (0.15) mm for marker registration was found. The differences for RMSE and target localization were statistically significant (p < 0.005). Furthermore, a strong correlation between RMSE and target difference was found for laser scanning (r = 0.96) and marker registration (r = 0.95). During various clinical procedures involving oral and maxillofacial surgery, the overall error of the registration procedure determined as RMSE was 1.21 (0.34) mm. Intraoperatively, the mean clinical application accuracy was found to be 1.8 (0.5) mm.

CONCLUSION

Three-dimensional laser surface scanning technique may be a interesting and useful approach to register the patient for image-guided procedures, particularly during oral and craniomaxillofacial surgery.

Cytokine gene expression in monocytes of patients undergoing cardiopulmonary bypass surgery evaluated by real-time PCR

Cardiopulmonary bypass (CPB) surgery induces systemic release of proinflammatory cytokines causing unspecific inflammatory reactions. This study deals with the development of a sensitive technique for detecting changes at the mRNA level in monocytes of patients undergoing CPB surgery, by using real-time PCR. Blood samples from patients undergoing elective coronary artery bypass grafting were obtained at six different time points. RNA was extracted from isolated monocytes and cDNA was synthesized by reverse transcriptase. CPB surgery induced gene expression of IL-1beta, IL-6, IL-8, and TNF-alpha, followed by a decrease below the preoperative expression values 6 h post CPB. High significant increases in gene expression for IL-8 at the end of surgery (p = 0.001) were detected. Real-time PCR is a powerful tool for getting simultaneously numerous sensitive, accurate, and reliable results from small amounts of biological material. This method avoids time-consuming and hazardous post-PCR manipulations and decreases the potential risk of PCR contamination.

Image-guided navigation for minimal invasive approaches in craniomaxillofacial surgery

The use of minimally invasive procedures in maxillofacial surgery will require new technologies involving surgical navigation and techniques. The aim of our studies is to improve the efficacy of image-guided navigation in combination with endoscopically assisted techniques for minimally invasive craniomaxillofacial procedures. Prospective evaluation was made of all patients who underwent surgical procedures using image-guided navigation. The most common type of operations performed were endoscopically assisted interventions within the paranasal sinuses, fracture treatment, the resection of bone lesions and further miscellaneous interventions. Our experience to date suggest that image-data based techniques are eminently applicable, providing a feasible alternative to conventional surgical treatment.

Significance of biodegradable implants in case of midfacial fractures

The purpose of this prospective clinical study was to evaluate new resorbable implants for bone fixation. The plates and screws are made of poly (D, L)lactide (PDLLA). Bioresorbable osteosynthesis and fixation (ResorbX) has been applied in 22 patients. Indications for operations were craniofacial trauma (malar, orbital-floor or frontal bone fractures) or orthognathic procedures (Le Fort-I-osteotomies) as well as the surgical correction in case of craniofacial syndromes. In the initial follow up, the first patients showed clinically and radiologically uneventful fixation and healing of the bone. There were no implant material related complications. Overall, the advantages of PDLLA-implants appear to be their ease of use, radiolucency and resorption, although further experience is needed to determine the longterm benefits of biodegradable implants.

The use of hybrid stereolithographic models for the planning of complex craniofacial procedures

Preoperative planning of orthognathic surgery is usually based on plaster cast models. Those are integrated in an articulator, simulating the movement of the jaws. We present a new procedure to combine the individual jaw anatomy by stereolithographical models with dental plaster casts, which are more accurately reproducing dental and bony anatomy. For image fusion the patient and the individual plaster casts are scanned by computed tomography, the occlusal planes being covered by a splint with radioopaque makers. After threshold segmentation of both, the plaster cast and the patients skull images are fused. The plaster cast volume is then subtracted from the patients upper and lower jaw, thus sparing out the place for later fusion of stereolithographic model and plaster cast.

Initial experience with intraoperative computed tomography in maxillofacial surgery

With respect to the complex anatomy in the head and neck region, computed tomography has been established as a routine method for preoperative evaluation. Whereas in neurosurgery intraoperative tomographic image data acquisition (CT, MR) serves for control of therapeutic effects on a routine base, maxillofacial surgeons aren't accustomed to use the method in this way. Using a mobile Philips Tomoscan M scanner, we examined the clinical significance and especially the ergonomy of intraoperative CT scans in maxillofacial traumatology.

Phase transitions and quantum effects in pore condensates: a path integral Monte Carlo study

Lennard-Jones condensates in cylindrical pores are studied by path integral Monte Carlo simulations with particular emphasis on phase transitions and quantum effects. The pore diameter effect and the influence of the interaction strength between the cylinder wall and the adsorbate particles on the structures and the location of the phase boundaries is studied and the quantum effect on the phase diagram is quantified by path integral Monte Carlo simulations. In case of strong wall-particle interactions good qualitative agreement with recent experimental results for the freezing of Ar-pore condensates is found. Meniscus structures in the solid phase are obtained as well as unexpected condensate structures for the system with the lighter Ne-particles due to quantum delocalization effects. The quantum effect on the freezing temperature can be as large as 10% in these systems.

[Interdisciplinary concept for classification and treatment of vascular anomalies in the head and neck]

PURPOSE

In patients with extended vascular anomalies in the head and neck, therapeutic decisions may pose a challenge to maxillofacial surgeons, dermatologists, and interventional radiologists. We analyzed the value of an interdisciplinary classification and treatment concept.

PATIENTS AND METHODS

The classification distinguishes hemangiomas and vascular malformations. Whereas hemangiomas are endothelial proliferations, vascular malformations are considered to be developmental anomalies, which are further classified into high-flow or low-flow lesions and according to the vascular channels into capillary, venous, or lymphatic malformations. Since 2000 we have provided interdisciplinary consultation for patients with vascular anomalies. In patients with hemangiomas and venous malformations, the clinical diagnosis is confirmed by color-coded duplex sonography and magnetic resonance imaging; angiography is performed as part of the treatment planning for patients with arteriovenous malformations. Patients with hemangiomas are treated surgically by cryosurgery or laser surgery or conservatively according to lesion size and behavior. In patients with venous malformations, percutaneous sclerotherapy is combined with surgical reduction; patients with arteriovenous malformations undergo transarterial embolization prior to surgical excision of the nidus.

RESULTS

A total of 73 patients attended the interdisciplinary consultation. This group included 53 patients with facial hemangiomas, 7 with venous malformations, 2 with capillary malformations, 5 with lymphatic malformations, and 6 with high-flow arteriovenous malformations.

CONCLUSIONS

The interdisciplinary protocol increases diagnostic accuracy and helps to establish individual treatment plans for patients with extended vascular anomalies.

[Feasibility of intraoperative diagnosis with a mobile computed tomography scanner]

AIMS

The possibility of performing intraoperative computed tomography may add to the safety and efficiency of some maxillofacial procedures. It would be preferable for intraoperative image data acquisition to be available to a surgeon on demand for immediate control of therapy results.

METHODS

In a pilot study, the use of a mobile computed tomographic scanner (Philips Tomoscan M, Philips Medical Systems, Eindhoven, Netherlands) was evaluated in our unit. The scanner is equipped with wheels, draws power from wall outlets in combination with batteries, and has a translating gantry.

RESULTS

Experience to date with six patients has confirmed the feasibility of intraoperative CT. All patients operated on were treated for craniofacial trauma. The CT images showed good spatial resolution. In all cases, visualization of the correct fragment position was excellent without causing significant delay of the operative procedure.

CONCLUSIONS

Intraoperative computed tomography could be the new state-of-the-art method for direct control of treatment results in maxillofacial traumatology. Nevertheless, the high expenses for installation of such technical infrastructure has to be pointed out; therefore, the routine use of this technique might be questioned.