Elmar Spüntrup

Cine MR imaging of heart valve dysfunction with segmented true fast imaging with steady state free precession.

To evaluate the value of cine true fast imaging with steady‐state free precession (SSFP) for semiquantitative assessment of valvular dysfunction in the heart and to compare the results to that obtained with a standard breath‐hold segmented gradient‐recalled echo‐planar imaging sequence (GE‐EPI).

Feasibility of pulmonary ventilation visualization with aerosolized magnetic resonance contrast media.

Objective:The objective of this study was to evaluate a new approach to noninvasive magnetic resonance assessment of human pulmonary ventilation with aerosolized Gd-DTPA. Materials and Methods:Fifteen experimental procedures were carried out in 15 healthy volunteers on a 1.5-T imager. For a timespan of 10 minutes, the subjects spontaneously inhaled a commercially available Gd-DTPA magnetic resonance contrast agent in aerosolized form through an inflatable facemask. Gd-DTPA was aerosolized by means of a small-particle generator with integrated heater to increase aerosol production. Respiratory gated dynamic T1-weighted turbo spin echo images were obtained before and after contrast agent aerosol administration. After nebulization, homogeneity of aerosol distribution was graded by 2 experienced readers and pulmonary signal intensity (SI) changes were measured in corresponding regions of both lungs. Results:Pulmonary ventilation visualization, and hence contrast agent delivery, was rated homogeneously distributed by both readers in 14 of 15 cases (93.3%) and slightly inhomogeneous in 1 case (6.7%). Pulmonary SI increased by an average of +37% ± 8.5 (range, 10–48%). Allergic responses were not noted. Conclusions:Human ventilation imaging with aerosolized gadolinium-chelates is viable. The presented modality might evolve as an alternative to current nuclear medicine and magnetic resonance image ventilation imaging procedures, avoiding radiation exposure while offering functional ventilation assessment with an acceptable temporal and spatial resolution. Nevertheless, further evaluation is required to define the potential of gadolinium-based ventilation magnetic resonance imaging in illustrating lung disease.

Differentiation of spontaneous canine breast tumors using dynamic magnetic resonance imaging with 24-Gadolinium-DTPA-cascade-polymer, a new blood-pool agent. Preliminary experience.

RATIONALE AND OBJECTIVES The author assess the enhancement characteristics over time of spontaneous breast tumors in dogs comparing gadopentetate dimeglumine with a new blood-pool agent (24-gadolinium [Gd]-DTPA-cascade polymer). METHODS Eighteen dogs with spontaneous breast tumors (5 carcinomas, 4 adenomas, and 9 benign mixed-tissue tumors) underwent dynamic magnetic resonance imaging after intravenous injection of gadopentetate dimeglumine and the blood-pool agent. Signal intensity time curves were followed up to 30 minutes after injection of both agents in the same animal. A nonlinear fitting routine enabled calculation of the delivery and clearance half lives of the contrast agent kinetics in each tumor. RESULTS For gadopentetate dimeglumine, a fast signal increase was found immediately after intravenous injection, with a subsequent signal decay in all tumors. No difference was observed between the enhancement kinetics of different tumor types after gadopentetate dimeglumine application. Similar kinetics were found in benign lesions after injection of the blood-pool agent. However, in carcinomas the blood-pool agent displayed a slower delivery, delayed peak enhancement, and slower tumor tissue clearance or even a signal plateau of more than 30 minutes. CONCLUSIONS Dynamic magnetic resonance imaging of breast neoplasms using a blood-pool agent may help to better differentiate between benign and malignant lesions because it demonstrates the enlarged interstitial space and increased capillary permeability in carcinomas.

Assessment of global left and right ventricular function using dual-source computed tomography (DSCT) in comparison to MRI: an experimental study in a porcine model.

Objective:We sought to evaluate the ability of retrospectively ECG-gated dual-source computed tomography (DSCT) to assess left (LV) and right ventricular (RV) functional parameters in comparison to 1.5 T magnetic resonance imaging (MRI). Materials and Methods:Ten domestic pigs (60 kg) underwent both contrast-enhanced cardiac DSCT and cardiac MRI using standardized examination protocols under general anesthesia. From manually drawn endocardial and epicardial contours, LV and RV end-systolic (ESV) and end-diastolic volume (EDV), stroke volume (SV), ejection fraction (EF), myocardial mass (MM), peak filling rate (PFR), peak ejection rate (PER), time to peak ejection (TPE), and time to peak filling (TPF) were calculated by means of dedicated analysis software. LV and RV functional parameters were analyzed using Bland-Altman plots, Student t test, and Pearsons correlation coefficient. Results:Both left and right ESV and EDV, SV and EF determined with DSCT correlated well with MR imaging results (left, r = 0.98/0.92/0.82/0.98; right, r = 0.90/0.94/0.96/0.94). PER, PFR, TPE, TPF, and MM showed only a moderate to low correlation (left, r = 0.67/0.37/0.23/0.35/0.57; right, r = 0.78/0.69/0.12/0.11/0.44). PER and PFR were significantly underestimated by DSCT when compared with MRI. Conclusions:Retrospectively ECG-gated DSCT correctly depicts end-systole and can accurately determine LV and RV volumes, SV, and EF in comparison to MRI. DSCT showed a significant underestimation of PER and PFR in comparison to MRI.

Gadolinium containing contrast agents for pulmonary ventilation magnetic resonance imaging: preliminary results.

Haage P, Karaagac S, Adam G, et al. Gadolinium containing contrast agents for pulmonary ventilation magnetic resonance imaging: preliminary results. Invest Radiol 2002;37:120-125. rationale and objectives. Five gadolinium containing contrast media (gadopentetate dimeglumine [Magnevist; Berlex Imaging, Montville, NJ, USA], gadobutrol [Gadovist; Schering, Järfälla, Sweden], gadoteridol [ProHance; Bracco-Byk Gulden, Konstanz, Germany], gadobenate dimeglumine [MultiHance; Bracco-Byk Gulden, Konstanz, Germany], and gadopentetate dimeglumine added with mannitol and a surface active detergent) were evaluated for their efficacy in magnetic resonance depiction of lung ventilation. methods. All contrast agent aerosols were generated by a jet nebulizer. Twelve intubated domestic pigs were mechanically ventilated with the respective aerosolized contrast agent and studied on a 1.5 T MR imager. T1-weighted TSE images using respiratory gating were obtained before and after a 10-minute ventilation period. Pulmonary signal intensity (SI) and signal-to-noise (SNR) changes were measured for both lungs. results. Mean SI increases ranged between 13.5% and 45.8% (right lung) and 14% and 39.8% (left lung). SNR changes ranged from +14.7% to +46.8% and from +13.1% to +40.5% for the right and left lung, respectively. The highest SI and SNR increases were observed in the gadoteridol group. conclusions. The use of gadolinium for MR ventilation imaging is primarily hindered by its viscosity properties and thus, its capability of aerosolization. Of the five agents tested, the medium with the lowest viscosity at room temperature (gadoteridol) showed the most promising enhancement results. The results reaffirm the potential of gadolinium-based contrast agents as a pulmonary imaging alternative. With a reduction of ventilation duration down to ten minutes, the method appears tolerable in a clinical setting.

[Renovascular hypertension--diagnosis and therapy].

ZusammenfassungDie atherosklerotische Nierenarterienstenose ist die häufigste Ursache der renovaskulären Hypertonie (RVH). Klinische Merkmale lenken den Verdacht auf das Vorliegen einer RVH. Bei betroffenen Patienten können durch eine nichtinvasive Diagnostik mit Duplexsonographie, CT- oder MR-Angiographie Hinweise auf eine Nierenarterienstenose gefunden werden. Durch die intraarterielle Angiographie erfolgt dann die endgültige morphologische Sicherung der Stenose. Bisher gelingt es mit diesen Methoden jedoch nicht, die Auswirkungen revaskularisierender Maßnahmen auf den postinterventionellen Verlauf der Hypertonie zu prognostizieren. Hypertensive Patienten mit signifikanter Nierenarterienstenose können medikamentös und/oder durch interventionelle Maßnahmen behandelt werden (Angioplastie der Nierenarterie mit/ohne Stentimplantation; chirurgische Revaskularisation). Randomisierte Studien, die eine invasive oder medikamentöse Therapie vergleichen, belegen keine Überlegenheit eines der Therapieverfahren zur Behandlung von Hypertonie oder renalem Funktionsverlust. Die Indikation zum invasiven Vorgehen muss daher sehr kritisch gestellt werden.AbstractAtherosclerotic renal artery stenosis accounts for most cases of renovascular hypertension (RVH). Hypertensive patients with clinical features suggesting RVH should be submitted to further noninvasive evaluation including duplex Doppler ultrasonography, CT- or MR angiography. Invasive evaluation by contrast-enhanced angiography confirms the diagnosis of renal artery stenosis. However, neither diagnostic test reliably predicts the course of hypertension after revascularisation. The therapeutic approach in hypertensive patients with hemodynamically important renal artery stenosis includes medical or invasive therapy (renal percutaneous transluminal angioplasty, PTRA; renal arterial stent placement, PTRAS; surgical revascularisation). Randomized trials comparing invasive and conservative approaches demonstrated no differences in blood pressure control or renal function. Only patients with clear clinical indications should be submitted to interventional procedures as PTRA, PTRAS and surgical vascular intervention.