A technical approach for transfemoral managing of hostile angulated pelvic vessel access in abdominal endovascular aneurysm repair: a new technique for establishing a buddy wire

PURPOSE

Endovascular aneurysm repair (EVAR) can be challenging in angulated access vessels. The aim of this study was to evaluate a new wire technique for installing a buddy wire in the event of failure of simple advancing of a super stiff guide.

MATERIALS AND METHOD

We investigated 8 patients eligible for EVAR. All patients presented with heavily kinked pelvic access and failure of primary advancing of a stiff guide wire through a placed catheter. A double wire technique with a combination of soft and stiff wires was applied to place a super stiff buddy wire. Cumulative angulation quantified by the sum of angles of the tortuous pelvic access vessels was measured in pre- and post-interventional CT as well as in angiographic studies of the EVAR procedure. Patients were followed up on by CT in the first 6 months.

RESULTS

A buddy wire could be installed in all patients (100%) with significant straightening of the access vessel from a median cumulative angulation of 252.4±38.1° before intervention to 159.4±44.6° after placement of the buddy wire (p<0.001). There was no technical failure of device passage and all stent-grafts could be deployed safely. Three cases of stenosis caused by torsion distal to the aortic stent-graft were seen after stent-graft delivery. One case of stenosis was hemodynamically relevant and was successfully stented. No major adverse events occurred within the first 6 months of follow-up. 

CONCLUSION

The new step-by-step wire technique is feasible and safe in the case of hostile pelvic vessel access, and facilitates the advancement of aortic stent-grafts in off-label patients.

Endovascular Aneurysm Management of a Gastroduodenal Artery Aneurysm in a Multipara Pregnant Woman

The authors describe a case of an intrapancreatic gastroduodenal artery aneurysm in a pregnant woman. Successful endovascular therapy was performed for the first time in a visceral artery aneurysm during pregnancy as a bailout solution. The attributive risk to the fetus from scattered radiation during endovascular treatment did not exceed a critical level.

[Advanced interventional techniques and therapies in the treatment of peripheral artery disease below the knee]

In patients with peripheral artery disease, the options for interventional therapy of critical limb ischemia have increased within the last few years. Different antegrade and retrograde techniques for vascular recanalization are used to pass even complex and long stenoses or occlusions below the knee (BTK). A variety of diverse wires, catheters and stent types allows arterial recanalization of the lower leg and increases the impact of therapeutic efforts. This review article describes indications, advanced techniques as well as materials in BTK interventions and summarizes current evidence-based study results.

Iterative reconstruction in head CT: image quality of routine and low-dose protocols in comparison with standard filtered back-projection

BACKGROUND AND PURPOSE

IR has recently demonstrated its capacity to reduce noise and permit dose reduction in abdominal and thoracic CT applications. The purpose of our study was to assess the potential benefit of IR in head CT by comparing objective and subjective image quality with standard FBP at various dose levels.

MATERIALS AND METHODS

Ninety consecutive patients were randomly assigned to undergo nonenhanced and contrast-enhanced head CT at a standard dose (320 mAs; CTDI, 60.1) or 15% (275 mAs; CTDI, 51.8) and 30% (225 mAs; CTDI, 42.3) dose reduction. All acquisitions were reconstructed with IR in image space, and FBP and images were assessed in terms of quantitative and qualitative IQ.

RESULTS

Compared with FBP, IR resulted in lower image noise (P ≤ .02), higher CNR (P ≤ .03), and improved subjective image quality (P ≤ .002) at all dose levels. While degradation of objective and subjective IQ at 15% dose reduction was fully compensated by IR (CNR, 1.98 ± 0.4 at 320 mAs with FBP versus 2.05 ± 0.4 at 275 mAs with IR; IQ, 1.8 versus 1.7), IQ was considerably poorer at 70% standard dose despite using the iterative approach (CNR, 1.98 ± 0.3 at 320 mAs with FBP versus 1.85 ± 0.4 at 225 mAs with IR, P = .18; IQ, 1.8 versus 2.2, P = .03). Linear regression analysis of CNR against tube current suggests that standard CNR may be obtained until approximately 20.4% dose reduction when IR is used.

CONCLUSIONS

Compared with conventional FBP, IR of head CT is associated with significant improvement of objective and subjective IQ and may allow dose reductions in the range of 20% without compromising standard image quality.

P3-16-04: A Novel Monoclonal Antibody to Secreted Frizzled Related Protein 2 Inhibits Triple Negative Breast Carcinoma Growth Rate In Vivo

Background: Secreted frizzled related protein 2 (SFRP2) is a novel angiogenesis factor expressed in the endothelium of a wide variety of human tumors including triple negative breast cancer and angiosarcoma. We previously reported generating a monoclonal antibody against SFRP2 that inhibits endothelial cell and angiosarcoma tube formation in vitro, and decreased tumor volume of the SVR angiosarcoma in vivo. The objectives of these studies were to determine pharmacokinetic (PK) and pharmacodynamic (PD) parameters of the SFRP2 MAb, and evaluate its efficacy in a triple negative breast cancer xenograft.

Methods: 125 I-SFRP2 MAb was administered to nude mice i.v. via tail vein injections at 0.4 mg/kg, 4 mg/kg, or 10 mg/kg in mice with or without tumor. Blood organ, and tumor samples were collected at various time points from 5 min to 21 days. Radiolabeled SFRP2 MAb in serum and tissues was determined using a gamma counter. PK parameters were determined based on mean concentration values for 3–5 animals per time point. In vivo efficacy study: MDA-MB-231 human breast cancer xenografts were established in 6-week-old female nude mice. Mice were inoculated with 1 × 106 cells s.c.. Treatment began on day 16 after tumor inoculation when average tumor size was 200 mm3. Animals were randomly assigned (n = 12 per group) to buffer control, SFRP2 MAb 4 mg/kg iv twice weekly; Avastin (Roch) 5 mg/kg iv twice weekly, or IGg control 4 mg/kg iv twice weekly. Tumors were harvested when the tumor diameter reached 2 cm or at 28 days. Tumor volumes were measured with a caliper. Growth rates (percent change per day) were compared with the formula ((Final volume- initial volume)/ initial volume) x 100 / number of days. Differences in growth rate between treated and control were analyzed with a two-tailed t-test.

Results: PK and PD: SFRP2 MAb was long circulating in the blood with an average t1/2 in the range of 53–89 hr. In addition, the SFPR2 MAb was found to preferentially target the tumors versus all other organs except for the liver. For example, in tumor bearing mice, the blood/tissue ratio on day 14 was smallest in the liver (15:1) and tumor (16:1) as compared to all other organs (range: 39:1 to 255:1) proving that the tumor was a prime organ for accumulation of the SFRP2 MAb. The SFPRP2 MAb in tumor bearing and non-tumor bearing mice exhibited dose-independent kinetics as a one-way ANOVA analysis comparing t1/2 at different dose levels was not statistically significant (p=0.2847 and 0.1204, respectively). However, there was statistically significant difference in t1/2 of the SFPR2 MAb in tumor-bearing and non-tumor bearing mice (p=0.0386). Efficacy in triple negative breast cancer: There was a 40% decrease in growth rate between SFRP2 MAb and control (p=0.03) and a 20% inhibition of growth rate between Avastin and control (p=0.40). The IgG negative control had no effect on tumor growth.

Conclusion: The SFRP2 MAb was long circulating and the tumor was a prime organ for accumulation of the SFRP2 MAb. SFRP2 MAb slowed the growth of a human triple negative breast cancer xenograft in a tumor model that was not sensitive to Avastin. We conclude that SFRP2 is a novel therapeutic target for breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-16-04.

Magnetization transfer in human Achilles tendon assessed by a 3D ultrashort echo time sequence: quantitative examinations in healthy volunteers at 3T

PURPOSE

Magnetization transfer contrast (MTC) imaging provides insight into interactions between free and bounded water. Newly developed ultrashort echo time (UTE) sequences implemented on whole-body magnetic resonance (MR) scanners allow MTC imaging in tissues with extremely fast signal decay such as tendons. The aim of this study was to develop a technique for the quantification of the MT effect in healthy Achilles tendons in-vivo at 3 Tesla.

MATERIALS AND METHODS

16 normal tendons of volunteers with no history of tendinopathy were examined using a 3D-UTE sequence with a rectangular on-resonant excitation pulse and a Fermi-shaped off-resonant MT preparation pulse. The frequency of the MT pulse was varied from 1 to 5 kHz. MT effects were calculated in terms of the MT ratio (MTR) between measurements without and with MT preparation. Direct saturation effects of MT preparation on the signal intensity were evaluated using numerical simulation of Bloch equations. One patient with tendinopathy was examined to exemplarily show changes of MTR under pathologic conditions.

RESULTS

Calculation of MTR data was feasible in all examined tendons and showed a decrease from 0.53 ± 0.05 to 0.25 ± 0.03 (1 kHz to 5 kHz) for healthy volunteers. Evaluation of variation with gender and dominance of ankle revealed no significant differences (p > 0.05). In contrast, the patient with confirmed tendinopathy showed MTR values between 0.36 (1 kHz) and 0.19 (5 kHz).

CONCLUSION

MT effects in human Achilles tendons can be reliably assessed in-vivo using a 3D UTE sequence at 3 T. All healthy tendons showed similar MTR values (coefficient of variation 10.0 ± 1.2 %). The examined patient showed a clearly different MT effect revealing a changed microstructure in the case of tendinopathy.

Carotid artery stenosis: performance of advanced vessel analysis software in evaluating CTA

OBJECTIVES

The aim of this study was to evaluate time efficiency and diagnostic reproducibility of an advanced vessel analysis software for diagnosis of carotid artery stenosis.

MATERIAL AND METHODS

40 patients with suspected carotid artery stenosis received head and neck DE-CTA as part of their pre-interventional workup. Acquired data were evaluated by 2 independent radiologists. Stenosis grading was performed by MPR eyeballing with freely adjustable MPRs and with a preliminary prototype of the meanwhile available client-server and advanced visualization software syngo.via CT Vascular (Siemens Healthcare, Erlangen, Germany). Stenoses were graded according to the following 5 categories: I: 0%, II: 1-50%, III: 51-69%, IV: 70-99% and V: total occlusion. Furthermore, time to diagnosis for each carotid artery was recorded.

RESULTS

Both readers achieved very good specificity values and good respectively very good sensitivity values without significant differences between both reading methods. Furthermore, there was a very good correlation between both readers for both reading methods without significant differences (kappa value: standard image interpretation k=0.809; advanced vessel analysis software k=0.863). Using advanced vessel analysis software resulted in a significant time saving (p<0.0001) for both readers. Time to diagnosis could be decreased by approximately 55%.

CONCLUSIONS

Advanced vessel analysis application CT Vascular of the new imaging software syngo.via (Siemens Healthcare, Forchheim, Germany) provides a high rate of reproducibility in assessment of carotid artery stenosis. Furthermore a significant time saving in comparison to standard image interpretation is achievable.

Estimation of radiation exposure of retrospective gated and prospective triggered 128-slice triple-rule-out CT angiography

BACKGROUND

CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible.

PURPOSE

To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA).

MATERIAL AND METHODS

An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm).

RESULTS

The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% ± 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% ± 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001).

CONCLUSION

Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner.