Geometric calibration of a mobile C-arm for intraoperative cone-beam CT

A geometric calibration method that determines a complete description of source-detector geometry was adapted to a mobile C-arm for cone-beam computed tomography (CBCT). The non-iterative calibration algorithm calculates a unique solution for the positions of the source (X(s), Y(s), Z(s)), detector (X(d), Y(d), Z(d)), piercing point (U(o), V(o)), and detector rotation angles (phi, theta, eta) based on projections of a phantom consisting of two plane-parallel circles of ball bearings encased in a cylindrical acrylic tube. The prototype C-arm system was based on a Siemens PowerMobil modified to provide flat-panel CBCT for image-guided interventions. The magnitude of geometric nonidealities in the source-detector orbit was measured, and the short-term (approximately 4 h) and long-term (approximately 6 months) reproducibility of the calibration was evaluated. The C-arm exhibits large geometric nonidealities due to mechanical flex, with maximum departures from the average semicircular orbit of deltaU(o) = 15.8 mm and deltaV(o) = 9.8 mm (for the piercing point), deltaX and deltaY = 6-8 mm and deltaZ = 1 mm (for the source and detector), and deltaphi approximately 2.9 degrees, deltatheta approximately 1.9 degrees, and delta eta approximately 0.8 degrees (for the detector tilt/rotation). Despite such significant departures from a semicircular orbit, these system parameters were found to be reproducible, and therefore correctable by geometric calibration. Short-term reproducibility was < 0.16 mm (subpixel) for the piercing point coordinates, < 0.25 mm for the source-detector X and Y, < 0.035 mm for the source-detector Z, and < 0.02 degrees for the detector angles. Long-term reproducibility was similarly high, demonstrated by image quality and spatial resolution measurements over a period of 6 months. For example, the full-width at half-maximum (FWHM) in axial images of a thin steel wire increased slightly as a function of the time (delta) between calibration and image acquisition: FWHM=0.62, 0.63, 0.66, 0.71, and 0.72 mm at delta = 0 s, 1 h, 1 day, 1 month, and 6 months, respectively. For ongoing clinical trials in CBCT-guided surgery at our institution, geometric calibration is conducted monthly to provide sufficient three-dimensional (3D) image quality while managing time and workflow considerations of the calibration and quality assurance process. The sensitivity of 3D image quality to each of the system parameters was investigated, as was the tolerance to systematic and random errors in the geometric parameters, showing the most sensitive parameters to be the piercing point coordinates (U(o), V(o)) and in-plane positions of the source (X(s), Y(s)) and detector (X(d), Y(d)). Errors in the out-of-plane position of the source (Z(s)) and detector (Z(d)) and the detector angles (phi, theta, eta) were shown to have subtler effects on 3D image quality.

Characterization of a dUTPase from the hyperthermophilic archaeon Thermococcus onnurineus NA1 and its application in polymerase chain reaction amplification

Genomic analysis of the hyperthermophilic archaeon Thermococcus onnurineus NA1 (TNA1) revealed the presence of a 471-bp open reading frame with 93% similarity to the dUTPase from Pyrococcus furiosus. The dUTPase-encoding gene was cloned and expressed in Escherichia coli. The purified protein hydrolyzed dUTP at about a 10-fold higher rate than dCTP. The protein behaved as a dimer in gel filtration chromatography, even though it contains five motifs that are conserved in all homotrimeric dUTPases. The dUTPase showed optimum activity at 80 degrees C and pH 8.0, and it was highly thermostable with a half-life (t (1/2)) of 170 min at 95 degrees C. The enzymatic activity of the dUTPase was largely unaffected by variations in MgCl(2), KCl, (NH(4))(2)SO(4), and Triton X-100 concentrations, although it was reduced by bovine serum albumin. Addition of the dUTPase to polymerase chain reactions (PCRs) run with TNA1 DNA polymerase significantly increased product yield, overcoming the inhibitory effect of dUTP. Further, addition of the dUTPase allowed PCR amplification of targets up to 15 kb in length using TNA1 DNA polymerase. This enzyme also improved the PCR efficiency of other archaeal family B type DNA polymerases, including Pfu and KOD.

Combination chemotherapy with irinotecan and cisplatin in elderly patients (≥65 years) with extensive-disease small-cell lung cancer

18135

Background: Combination chemotherapy with irinotecan and cisplatin is one of the standard treatments for patients with small-cell lung cancer (SCLC). In elderly patients, however, its efficacy and toxicity has not been well documented. In this Phase II study, we assessed the efficacy and toxicity of combination chemotherapy with irinotecan and cisplatin and examined whether advanced age compromises it in elderly patients with previously untreated extensive-disease small-cell lung cancer (ED-SCLC). Methods: In this study, 43 previously untreated elderly patients (65 years or older) with ED-SCLC were given combination chemotherapy consisting of irinotecan 60mg/m2 on days 1, 8 and 15 and cisplatin 60mg/m2 on days 1. The treatment was repeated every four weeks until patients completed the maximum six cycles. Results: Patients consisted of 34 men and 9 women, whose median age was 70 years (range 65 - 81 years). A complete response and a partial response were observed in 23.3% (10/43) and 58.1% (25/43), respectively. The overall response rate was 81.4% (95% C.I; 69.7 - 93.0%). The overall median survival was 10.3 months (range 7.8 - 12.7 months). The 1-year and 2- year survival rates were 31.8% and 3.4%, respectively. The median progression-free survival was 8.32 months (range 6.8 - 9.8 months). Major toxicities included neutropenia (grade 3 to 4, 55.9%), leukopenia (grade 3 to 4, 46.5%), infection (grade 3 to 4, 37.3%) and diarrhea (grade 3 to 4, 30.3%). Incidence of febrile neutropenia was significantly higher in patients with ECOG performance status 2 compared with ECOG performance 1 (70.7% vs. 5.2%; p < 0.001). There were two treatment related deaths in patients ECOG performance status 2. Conclusions: Our results indicate that combination chemotherapy with irinotecan and cisplatin is an effective treatment for elderly patients with ED-SCLC. However, physicians should be aware of the mortality and morbidity due to myelosuppression following this treatment in elderly ED-SCLC patients with ECOG performance status 2.

No significant financial relationships to disclose.

Vascular endothelial growth factor gene polymorphisms and risk of colorectal cancer

4123

Background: Angiogenesis is closely related to the development, growth, and metastasis of solid tumors, including colorectal cancer (CRC), and the vascular endothelial growth factor (VEGF) is known to be a potent pro-angiogenic factor. Accordingly, the present study was conducted to evaluate the potential association between two VEGF polymorphisms (+405G > C, and 936C > T) and the risk of CRC. Methods: The VEGF genotypes were determined using fresh colorectal tumor tissue from 477 patients with CRC who underwent surgical resection and peripheral blood lymphocytes from 413 healthy controls based on a polymerase chain reaction/denaturing high-performance liquid chromatography (PCR/DHPLC) assay. The incidence of genotypes and haplotypes of two VEGF polymorphisms was compared between the patients with CRC and the controls. Results: The distribution of genotypes and allele frequencies of the 936C > T polymorphism in the CRC group did not differ from those in the control group. However, compared with the combined GC and CC genotype, the GG genotype of +405G > C polymorphism was significantly associated with an increased risk of CRC [odds ratio (OR), 1.575; 95% confidence interval (CI), 1.178–2.104; P = 0.002]. In the haplotype analyses, haplotype +405G / 936C was also associated with a significantly increased risk of CRC (OR, 1.264; 95% CI, 1.043–1.531; P = 0.017), whereas haplotype +405C / 936C was associated with a decreased risk of CRC (OR, 0.818; 95% CI, 0.677–0.989; P = 0.038). None of the VEGF polymorphisms studied significantly influenced the clinical or pathologic features of CRC. Conclusions: These findings suggest that the VEGF +405G > C polymorphism may be associated with the risk of CRC in the Korean population.

No significant financial relationships to disclose.

Cervix cancer regression measured using weekly MR imaging during fractionated radiotherapy: Radiobiologic modeling and correlation with tumor hypoxia

5547

Background: To utilize cervix cancer volumetry, as measured with MR imaging during definitive chemoirradiation (RT-CT), to derive radiobiological parameters using a mathematical model of tumor regression, and compare them to pre-treatment measurements of tumor hypoxia. Methods: Twenty-eight patients receiving RT-CT for cervix cancer underwent weekly magnetic resonance imaging (MRI) scans. Tumor volume was assessed on each of these scans and the rate of regression plotted. A mathematical model of tumor regression was formulated to simulate the relationship between three independent radiobiological parameters, 1) surviving fraction of cells after 2 Gy, SF2, 2) the cell clearance constant Tc, and 3) the cellular proliferation constant Tp. Non-linear regression analysis was applied to fit the MR-derived tumor volumes to the mathematical model and to derive SF2 and Tc values for each patient. These were compared to pre-treatment hypoxia measurements. Results: Initial tumor volume ranged between 8 and 209 cm3. Relative reduction in volume during treatment was 0.02 to 0.79. Simulations using representative values of the independent biologic variables derived from the literature showed SF2 and Tc to strongly influence the shape of the volume response curves. Non-linear regression analysis yielded a median SF2 of 0.71 and median Tc of 10 days. Radioresistant tumors (SF2 >0.71) were significantly more hypoxic at diagnosis (p=0.02). Conclusion: Based on serial MR imaging during treatment, a marked variation in cervix tumor regression is seen from patient to patient. Through our radiobiological model, tumors can be classified as radioresistant or radiosensitive, which correlates with hypoxia

[Table: see text]

No significant financial relationships to disclose.

A prospective randomized trial comparing 5-fluorouracil (5-FU), mitomycin-C (MMC), and polysaccharide-K (PSK) versus UFT and PSK as adjuvant chemoimmunotherapy (CITX) for patients with locally advanced gastric cancer with curative resection

15074

Background: Adjuvant chemotherapy has demonstrated small but significant survival benefit in locally advanced gastric cancer in several meta-analyses, while adjuvant CITX showed improved outcome of patients (pts) compared to chemotherapy alone in a few trials. However, optimal chemotherapy regimen remains to be determined. We conducted a randomized trial comparing oral (PO) CITX with intravenous (IV) CITX in gastric cancer pts with curative resection. Methods: All enrolled pts underwent radical surgery with at least D2 dissection. After stratification for pathologic stage (IB or II vs. III) and primary tumor size (=5 cm vs. >5 cm), pts were randomized to IV CITX (5-FU 500 mg/m2 weekly for 24 weeks, MMC 8 mg/m2 every 6 weeks x 4) or PO CITX (UFT 400–600 mg/day for 12 months). Pts in both arms received PSK 3 g/day PO for 4 months. The planned target number of pts was 368 to prove the non-inferiority of PO CITX compared to IV CITX in overall survival. Results: A total of 82 pts (stage IB: 6, II: 29, IIIA: 30, IIIB: 17; 44 in IV arm, 38 in PO arm) were enrolled between May 2002 and October 2005, when the trial was closed due to poor accrual. Pts characteristics were well balanced. With a median follow-up of 39 months (14–55 months) in survivors, there were no significant differences in 3-year disease-free survival (82% vs. 61%, p=0.302) and overall survival (84% vs. 79%, p=0.838) between IV and PO arms. No grade 4 toxicity was observed in both arms. IV arm demonstrated higher incidence of grade 2 or 3 neutropenia (79% vs. 52%, p=0.025), thrombocytopenia (19% vs. 0%, p=0.008), and vomiting (36% vs. 9%, p=0.013). Conclusions: Although accrual was well below that planned, the results of this trial suggest that PO CITX with UFT might have similar efficacy with lower toxicity profile compared with 5-FU and MMC CITX in adjuvant treatment for gastric cancer.

No significant financial relationships to disclose.

Vascular endothelial growth factor (VEGF) gene polymorphisms associated with prognosis for patients with colorectal cancer

4125

Background: Vascular endothelial growth factor (VEGF) or its family may be considered to play an important role in lymphangiogenesis and lymphatic tumor spread, thereby affecting prognosis of colorectal cancer. Accordingly, the present study analyzed VEGF gene polymorphisms and their impact on the prognosis for patients with colorectal cancer. Patients and Methods: Four hundred and sixty-five consecutive patients with surgically treated colorectal adenocarcinoma were enrolled in the present study. The genomic DNA was extracted from fresh colorectal tumor tissue and 3 VEGF (-2578C > A, -634G > C, and +936C > T) gene polymorphisms determined using a PCR/DHPLC (Polymerase chain reaction/Denaturing high-performance liquid chromatography) assay. Results: The median age of the patients was 64 years (range, 21–89), and 264 (56.7%) patients had colon cancer and 201 (48.2%) patients rectal cancer. Pathologic stages evaluable (n=464) after surgery were as follows: stage I (n=79, 17.0%), stage II (n=157, 33.8%), stage III (n=157, 33.8%), and stage IV (n=71, 15.3%). Multivariate survival analysis including stage, differentiation, and CEA level showed that survival for patients with the -634CC (overall survival [OS]: hazard ratio [HR]=0.175, P<0.001; progression-free survival [PFS]: HR=0.554, P=0.040) or GC genotype (OS: HR=0.158, P<0.001; PFS: HR=0.630, P=0.044) were better than for patients with the -634GG genotype, whereas the +936TT (OS: HR=65.959, P<0.001; PFS: HR=2.823, P=0.016) or CT genotype (OS: HR=16.116, P<0.001; PFS: HR=3.507, P<0.001) were associated with a worse survival compared to the CC genotype. In haplotype analysis, the -2578A/-634G/+936T haplotype exhibited a significantly worse survival when compared to the wild -2578C/-634G/+936C haplotype (OS: HR=4.670, P<0.001; PFS: HR=3.624, P<0.001). Conclusions: VEGF gene polymorphisms were found to be an independent prognostic marker for patients with colorectal cancer. Accordingly, the analysis of VEGF gene polymorphisms can help identify patient subgroups at high risk of a poor disease outcome.

No significant financial relationships to disclose.