Comparison of Gadolinium-BOPTA and Ferucarbotran-enhanced three-dimensional T1-weighted dynamic liver magnetic resonance imaging in the same patient.

OBJECTIVES: We sought to compare signal changes using Ferucarbotran and gadobenate dimeglumine (Gd-BOPTA) in dynamic 3D T1-weighted (T1w) GRE imaging of the liver. MATERIAL AND METHODS: Thirty patients were prospectively included in the study. All patients underwent 2 high-field magnetic resonance (MR) examinations: first with Gd-BOPTA (Gd) and then after a mean interval of 4 days with ferucarbotran (Feru). Dynamic MRI was obtained with a 3D T1w GRE sequence (TR 6.33, TE 2.31, flip angle 20 degrees ). Contrast enhanced scans were assessed before intravenous injection of the contrast agent (precontrast), and postcontrast during the arterial phase (30 seconds), portal venous phase (60 seconds), and equilibrium phase (120 seconds). The signal intensities (SIs) of liver, spleen, aorta, and portal vein were defined by region of interest measurements. Signal intensity changes (SICs) and percentage signal intensity change (PSIC) were calculated using the formulas SIC=(SI pre - SI post)/SI pre and PSIC=SIC x 100%. RESULTS: Positive signal enhancement was observed after intravenous injection of Feru during all dynamic measurements, whereas the mean SI values were lower compared with Gd. During the portal venous phase the mean SI of Gd was up to a factor of 2.1 higher (portal vein). The widest difference of SIC was observed during the equilibrium phase for liver parenchyma (Gd, 1.03; Feru, 0.24). The dynamic signal courses were similar for liver, portal vein and aorta. Different signal courses were obtained for the spleen. CONCLUSIONS: Feru-enhanced T1w dynamic images demonstrated significant signal increases for liver, vessels, and spleen but overall lower signal intensities than Gd-BOPTA. The dynamic signal courses of ferucarbotran were similar to that of Gd-BOPTA during ll perfusion phases except in the spleen. Thus, it may be possible to detect typical enhancement pattern of focal liver lesions with Feru-enhanced dynamic T1w MRI.

The effects of paclitaxel on the three phases of restenosis: smooth muscle cell proliferation, migration, and matrix formation: an in vitro study.

PURPOSE: We sought to evaluate the growth-modulating potential of paclitaxel on cultured human arterial smooth muscle cells depending on the administered dose. MATERIAL AND METHODS: For all experiments human arterial smooth muscle cells (SMCs) were used. SMCs were either cultured for 5 days or for 20 days with paclitaxel (doses: 10(-7) M, 10(-8) M, 10(-9) M). For a total period of 20 days, proliferation kinetics of the SMC were analyzed. To assess the clonogenic activity of the SMC colony-forming assays were performed. Drug- and dose-dependent cell cycle changes were analyzed by flow cytometry. The effect on cell migration was examined in a 2-chamber migration system. The effects of paclitaxel on the synthesis of tenascin were examined via immunofluorescence. RESULTS: Depending on the dose administered, paclitaxel proved to inhibit SMC proliferation effectively when administered during the total period of 20 days. When incubated for 5 days with doses of paclitaxel ranging between 10(-8) M and 10(-9) M, SMCs showed clear signs of regeneration. When being incubated with 10(-7) M of paclitaxel, however, SMCs reacted with a reduction in cell proliferation, a reduced clonogenic activity, and a drug-induced G2/M phase block. SMC migration was inhibited effectively as well as extracellular matrix formation. CONCLUSION: Paclitaxel is a potent inhibitor of SMC proliferation, SMC migration, and extracellular matrix formation in vitro, with all three phases of the restenosis process inhibited effectively.

Radiopacity of current endovascular stents: evaluation in a multiple reader phantom study.

PURPOSE: To evaluate the radiopacity of endovascular stents based on the fluoroscopy mode in a phantom of the human pelvis. MATERIALS AND METHODS: The following stents were included in this study: Medtronic AVE Bridge, Medtronic AVE Bridge X, Cordis Covered Nitinol (Covent), Guidant Dynalink, Luminexx, Guidant Megalink, Memotherm Flexx, Palmaz Medium, Palmaz-Schatz Long-Medium, Palmaz Corinthian PQ394Q and PQ294Q, SelfX, SMART without markers, SMART with radiopaque markers, Easy Wallstent. To evaluate radiopacity, images of the stents placed in four different positions (lumbosacral junction left and right, iliosacral joint left and right) of a pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, 15 pulses per second, 7.5 pulses per second, and 3 pulses per second. Images were presented at random to four independent readers and radiopacity scores were assessed: 0 = not visible, 1 = poor visibility, 2 = average visibility, 3 = good visibility, and 4 = very good visibility. RESULTS: The Covent stent had the highest overall radiopacity score (3.25), followed by the Luminexx (3.04) and the Medtronic AVE Bridge X (2.74) stents. At the spotfilm mode, the best visible stents were the Medtronic AVE Bridge X, the Covent and the Easy Wallstent stents and at the continuous fluoroscopy mode, the Covent, the Luminexx, and the Medtronic AVE Bridge X stents. Decreasing the fluoroscopy mode went hand in hand with a reduction of the radiopacity scores of all stents. At the standard fluoroscopy mode of 7.5 pulses per second, the Covent stent was seen well or very well in 96.9%, followed by the Luminexx (76.9%), and the Medtronic AVE Bridge X (41.25%) stents. CONCLUSIONS: Stent radiopacity directly depends on the fluoroscopy mode; if the pulse frequency decreased, detecting the stents became more difficult. Stent mass correlates with stent radiopacity (e.g., Cordis Covered Nitinol, Bridge X). Radiopaque markers may improve stent radiopacity dramatically (e.g., Luminexx vs Memotherm Flexx).

Diagnostic potential of targeted electrical impedance scanning in classifying suspicious breast lesions.

RATIONALE AND OBJECTIVE: To evaluate the potential of targeted electrical impedance scanning (EIS) for classifying suspicious breast lesions. METHODS: EIS was performed in full knowledge of mammographic findings and findings of clinical breast examination. One hundred seventeen patients with a total of 129 breast lesions were examined with EIS before breast biopsy (surgical excision or vacuum core biopsy). Diagnostic indexes of targeted EIS were calculated depending on major lesion characteristics. Capacitance and conductivity of all positive spots (S) and the surrounding normal breast tissue (NBT) were quantified using ROI measurements. The ratio S/NBT was calculated to compare true positive (n = 44) and false positive (n = 18) spots. RESULTS: With respect to histology, of the 129 lesions 71 were malignant and 58 lesions were benign. Overall sensitivity of targeted EIS was 62%, specificity 69%, PPV 71%, and NPV 60%. Sensitivity of EIS varied depending on the tumor size, which was between 48% (> 20 mm) and 71% (11-20 mm). Highest specificity (86%) was observed for large lesions (> 20 mm); however, the NPV was only 35% for lesions of that size. NPV was higher for nonpalpable lesions (74%) and clusters of microcalcifications (85.7%) compared with palpable lesions (39%) and solid lesions (44%). There was no statistical difference of S/NBT ratio neither for conductivity nor capacitance of true and false positive spots. Compared with true positive spots a trend of a higher conductivity ratio at 100 Hz and 200 Hz was seen for false positive spots. CONCLUSION: EIS showed mediocre overall diagnostic accuracy for classifying suspicious breast lesions. Quantitative analysis of positive EIS findings did not help to differentiate between false and true positive spots.