Development of a navigation system for minimally invasive esophagectomy

BACKGROUND

A major challenge of minimally invasive esophagectomy is the uncertainty about the exact location of the tumor and associated lymph nodes. This study aimed to develop a navigation system for visualizing surgical instruments in relation to the tumor and anatomic structures in the chest.

METHODS

An immobilization device consisting of a vacuum mattress fixed to a stretcher was built to decrease patient movement and organ deformation. Computer tomography (CT) markers were embedded in the stretcher at a defined distance to a detachable plate with optical markers on the side of the stretcher. A second plate of optical markers was fixed to the operating instrument. These two optical marker plates were tracked with an optical tracking system. Their positions were then registered in a preoperative CT data set using the authors' navigation software. This allowed a real-time visualization of the instrument and target structures. To assess the accuracy of the system, the authors designed a phantom consisting of a box containing small spheres in a specific three-dimensional layout. The positions of the spheres were first measured with the navigation system and then compared with the known real positions to determine the accuracy of the system.

RESULTS

In the accuracy assessment, the navigation system showed a precision of 0.95 +/- 0.78 mm. In a test data set, the instrument could be successfully navigated to the tumor and target structures.

CONCLUSION

The described navigation system provided real-time information about the position and orientation of the working instrument in relation to the tumor in an experimental setup. Consequently, it might improve minimally invasive esophagectomy and allow for surgical dissection in an adequate distance to the tumor margin and ease the location of affected lymph nodes.

Alpha-fetoprotein promoter-targeted sodium iodide symporter gene therapy of hepatocellular carcinoma

Due to limited treatment options the prognosis of patients with advanced hepatocellular cancer (HCC) has remained poor. To investigate an alternative therapeutic approach, we examined the feasibility of radioiodine therapy of HCC following human sodium iodide symporter (NIS) gene transfer using a mouse alpha-fetoprotein (AFP) promoter construct to target NIS expression to HCC cells. For this purpose, the murine Hepa 1-6 and the human HepG2 hepatoma cell lines were stably transfected with NIS cDNA under the control of the tumor-specific AFP promoter. The stably transfected Hepa 1-6 cell line showed a 10-fold increase in iodide accumulation, while HepG2 cells accumulated (125)I approximately 60-fold. Tumor-specific NIS expression was confirmed on mRNA level by northern blot analysis, and on protein level by immunostaining, that revealed primarily membrane-associated NIS-specific immunoreactivity. In an in vitro clonogenic assay up to 78% of NIS-transfected Hepa 1-6 and 93% of HepG2 cells were killed by (131)I exposure, while up to 96% of control cells survived. In vivo NIS-transfected HepG2 xenografts accumulated 15% of the total (123)I administered per gram tumor with a biological half-life of 8.38 h, resulting in a tumor absorbed dose of 171 mGy MBq(-1) (131)I. After administration of a therapeutic (131)I dose (55.5 MBq) tumor growth of NIS expressing HepG2 xenografts was significantly inhibited. In conclusion, tumor-specific iodide accumulation was induced in HCC cells by AFP promoter-directed NIS expression in vitro and in vivo, which was sufficiently high to allow a therapeutic effect of (131)I. This study demonstrates the potential of tumor-specific NIS gene therapy as an innovative treatment strategy for HCC.

Automatic generation of 3D statistical shape models with optimal landmark distributions

OBJECTIVES

To point out the problem of non-uniform landmark placement in statistical shape modeling, to present an improved method for generating landmarks in the 3D case and to propose an unbiased evaluation metric to determine model quality.

METHODS

Our approach minimizes a cost function based on the minimum description length (MDL) of the shape model to optimize landmark correspondences over the training set. In addition to the standard technique, we employ an extended remeshing method to change the landmark distribution without losing correspondences, thus ensuring a uniform distribution over all training samples. To break the dependency of the established evaluation measures generalization and specificity from the landmark distribution, we change the internal metric from landmark distance to volumetric overlap.

RESULTS

Redistributing landmarks to an equally spaced distribution during the model construction phase improves the quality of the resulting models significantly if the shapes feature prominent bulges or other complex geometry.

CONCLUSIONS

The distribution of landmarks on the training shapes is -- beyond the correspondence issue -- a crucial point in model construction.

Association between standard clinical and pathological breast cancer characteristics and the 21-gene recurrence score: A population-based study

11002

Background: The 21-gene recurrence score (RS) aims to quantify chemotherapy benefit in lymph node-negative, estrogen receptor (ER)-positive breast cancer (BC) patients. We aimed to elucidate the association between the RS and clinical-pathological features in a population-based Israeli cohort. Methods: Study population included all Israeli BC female patients referred to the RS assay from October 2004 until October 2006. Clinical and pathology data were collected upon referral, RS risk was categorized as previously defined (low < 18, intermediate 18–30, high = 31) and chemotherapy benefit was also assessed for each patient using NCCN guidelines, St. Gallen recommendations and Adjuvant! Online. Results: 300 patients were referred to the assay by 70 physicians from 16 institutions. Low, intermediate and high RS were noted in 109 (36 %), 134 (45 %) and 57 (19%) of the patients respectively, compared to 54%, 21% and 25% respectively, in the validation study (JCO;24:3726). Median age was 54 and median tumor size was 1.6 cm. Similar age distribution, tumor size and ER staining intensity were noted in all risk categories. Interestingly, no association has been identified between the RS and the presence of lymph nodes micrometastases. High tumor grade was noted in 15%, 20% and 56%; progesterone expression in 88% 72% 43%; non-infiltrative ductal carcinoma (IDC) 24%, 12% and 6%; and Her2 expression in 2%, 3% and 19% of the low, intermediate and high risk categories respectively (p<0.0001 for all variables). Risk assessment according to clinical guidelines or Adjuvant! Online correlated poorly with the RS. Conclusions: Risk stratification of referred Israeli patients differs from that of the validation study population. Moreover, the RS did not correlate with age, tumor size and ER intensity. The RS correlated with histology, grade, PR and Her2 expression and may be predicted, in specific subsets of patients, using these features. However, RS categorization cannot be predicted by commonly-used clinical predicting tools.

No significant financial relationships to disclose.

[Three-dimensional echocardiography in cardiac surgery. Current status and perspectives]

Three-dimensional (3D) echocardiography is a new imaging technique that can provide useful information about cardiovascular morphology, pathology, and function. Recent refinements in instrumentation, data acquisition, post-processing, and computation speed allow 3D echocardiography to play an important role in cardiac imaging. These modalities provide comprehensive information on ventricular and valve morphology and function. Combined with 3D color Doppler sonography, further assessment of valvular function and determination of flow in the left ventricular outflow tract and cross-septal defects are now possible. Three-dimensional color flow imaging also makes echocardiography accurate for assessing the severity of mitral regurgitation. The purpose of this review is to describe technical developments in 3D echocardiography and its clinical application in cardiac surgery. Moreover, based on clinical studies at our centre, we describe the morphology of the mitral valve, its flow pattern, and function of the mitral annulus.

Stereolithographic reproduction of complex cardiac morphology based on high spatial resolution imaging

BACKGROUND

Precise knowledge of cardiac anatomy is mandatory for diagnosis and treatment of congenital heart disease. Modern imaging techniques allow high resolution three-dimensional (3D) imaging of the heart and great vessels. In this study stereolithography was evaluated for 3D reconstructions of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) data.

METHODS

A plastinated heart specimen was scanned with MDCT and after segmentation a stereolithographic (STL) model was produced with laser sinter technique. After scanning the STL model with MDCT these data were compared with those of the original specimen after rigid registration using the iterative closest points algorithm (ICP). The two surfaces of the original specimen and STL model were matched and the symmetric mean distance was calculated. Additionally, the heart and great vessels of patients (age range 41 days-21 years) with congenital heart anomalies were imaged with MDCT (n=2) or free breathing steady, state free-precession MRI (n=3). STL models were produced from these datasets and the cardiac segments were analyzed by two independent observers.

RESULTS

All cardiac structures of the heart specimen were reconstructed as a STL model within sub-millimeter resolution (mean surface distance 0.27+/-0.76 mm). Cardiac segments of the STL patient models were correctly analyzed by two independent observers compared to the original 3D datasets, echocardiography (n=5), x-ray angiography (n=5), and surgery (n=4).

CONCLUSIONS

High resolution MDCT or MRI 3D datasets can be accurately reconstructed using laser sinter technique. Teaching, research and preoperative planning may be facilitated in the future using this technique.

Precision targeting of liver lesions with a needle-based soft tissue navigation system

In this study, we assessed the targeting precision of a previously reported needle-based soft tissue navigation system. For this purpose, we implanted 10 2-ml agar nodules into three pig livers as tumor models, and two of the authors used the navigation system to target the center of gravity of each nodule. In order to obtain a realistic setting, we mounted the livers onto a respiratory liver motion simulator that models the human body. For each targeting procedure, we simulated the liver biopsy workflow, consisting of four steps: preparation, trajectory planning, registration, and navigation. The lesions were successfully hit in all 20 trials. The final distance between the applicator tip and the center of gravity of the lesion was determined from control computed tomography (CT) scans and was 3.5 +/- 1.1 mm on average. Robust targeting precision of this order of magnitude would significantly improve the clinical treatment standard for various CT-guided minimally invasive interventions in the liver.

Three-Dimensional Assessment of Left Ventricular Geometry and Annular Dilatation Provides New Mechanistic Insights into the Surgical Correction of Ischemic Mitral Regurgitation

BACKGROUND

The aim of this study was to investigate the relationship between LV geometry, annular shape and the amount of regurgitation in patients with ischemic mitral regurgitation (group 1, n = 30) compared to patients with primary mitral valve lesions (group 2, n = 30).

METHODS

LV geometry was assessed by the sphericity index, i.e., LV volume divided by the volume of a sphere with a diameter equal to the longest axis. Annular geometry was evaluated by diameters, areas and their percentual shortening. The degree of mitral regurgitation was assessed as jet volumes by 3D-echocardiography.

RESULTS

Group 1 showed significantly larger longitudinal (54.3 +/- 3.1 vs. 40.9 +/- 2.6 mm) and antero-posterior (32.2 +/- 3.3 vs. 27.1 +/- 2.9 mm) annulus diameters and areas (993.3 +/- 66.6 vs. 702.1 +/- 47.9 mm (2)) than group 2. No asymmetric annular enlargement was found in either group. Annular enlargement correlated to the degree of mitral regurgitation in group 1 but not in group 2. Annular area shortening was significantly impaired in group 2 and the sphericity index was larger in group 1 than in group 2. In group 1, the sphericity index was significantly correlated to the degree of mitral regurgitation (r = 0.87; P < 0.001).

CONCLUSIONS

These findings suggest that ischemic mitral regurgitation was mostly associated with a global left ventricular enlargement, in which annulus dilatation and its reduced contraction play a significant role.

15-Hydroxyprostaglandin dehydrogenase (PGDH) is an aberrant tumor suppressor in human breast cancer

10550

Background: Prostaglandin E2 plays a growth stimulatory role in breast cancer; and the rate-limiting enzyme in its synthesis, cyclooxygenase-2 (COX-2), is over-expressed in breast cancers. However, little is known about the expression pattern and activities of the key prostaglandin catabolic enzyme PGDH, in breast cancer pathogenesis. Methods: 5-aza-2’-deoxycytidine and suberoyl anilide bishydroxamide (SAHA) were used to unmask epigenetically silenced genes. DNA and RNA were extracted from tumors and cell lines using standard methods, and bisulfite sequencing was used for methylation analysis. Western blotting and real time PCR were used for expression analysis, and PGDH expression vector and PGDH-directed siRNA were used for overexpression and downregulation of PGDH, respectively. Athymic mice were utilized for xenograft models. Results: Using a pharmacologically based, genome-wide screen for epigenetically silenced genes, we found low levels of PGDH in MDA-MB-231 cells (estrogen receptor- (ER) and HER2-negative), but high levels in MCF-7 cells (ER-positive, HER2-negative), and observed upregulation of this enzyme following demethylation treatment. Methylation analysis revealed methylation of the PGDH promoter in one breast cancer cell line and in 3 of 10 primary tumors. Analysis of PGDH expression demonstrated low levels in 40% of primary breast tumors and identified a correlation between PGDH and ER expression. Upregulation of PGDH levels in MDA-MB-231 cells decreased their clonal growth and reduced their ability to form tumors in athymic mice. In contrast, silencing of PGDH in MCF-7 cells increased proliferation and enhanced in-vivo tumorigenicity. Further analysis revealed upregulation of aromatase following silencing of PGDH and inhibition of the ER pathway by forced expression of the enzyme. PGDH levels were downregulated by estrogen but upregulated by the tumor suppressor gene C/EBPα. Conclusions: Our results identify for the first time, that PGDH, the COX-2 antagonist, is aberrantly silenced in breast cancer. Activation of this enzyme, particularly in ER- and HER2-negative tumors, now becomes an interesting target for clinical studies.

No significant financial relationships to disclose.

BRCA1 and FOXA1 proteins coregulate the expression of the cell cycle-dependent kinase inhibitor p27(Kip1)

We have previously shown that the breast cancer susceptibility gene, BRCA1, can transcriptionally activate the p27(Kip1) promoter. The BRCA1-responsive element was defined as a 35 bp region from position -545 to -511. We next determined that within this region is also a potential binding site for the transcription factor Forkhead box (FOX)A1. RNA and protein analysis as well as immunohistochemistry showed that expression of FOXA1 correlated with the expression of the estrogen receptor in a panel of breast cancer cell lines and tissues. In transient transfection reporter assays, FOXA1 could activate the p27(Kip1) promoter. Cotransfection of BRCA1 and FOXA1 resulted in a synergistic activation of the p27(Kip1) promoter. Mutation of the FOXA1 DNA-binding site in the p27(Kip1) promoter-luciferase construct significantly diminished the activity of FOXA1 alone or in combination with BRCA1. Cotransfection of FOXA1 and BRCA1 resulted in a greater amount of each protein compared to transfection of each expression vector alone. The half-life of FOXA1 was increased when coexpressed with BRCA1. Electrophoretic mobility shift assay analysis demonstrated that FOXA1 could bind to a wild-type oligonucleotide containing the FOXA1 binding site in the p27(Kip1) promoter, but this binding was lost upon mutation of this FOXA1 binding site. The protein-DNA binding complex could be supershifted with an antibody directed against FOXA1. The activity of the p27(Kip1) promoter as well as FOXA1 expression was reduced in cells treated with BRCA1 siRNA, thus silencing the expression of BRCA1 protein. In summary, we identified a FOXA1 binding site within the BRCA1-responsive element of the p27(Kip1) promoter and showed that FOXA1 activated the promoter alone and in conjunction with BRCA1. Furthermore, we identified high expression of FOXA1 in breast cancer cell lines and tissues, discovered a role for BRCA1 in the regulation of p27(Kip1) transcription and a possible interaction with BRCA1.