Intra-individual, randomised comparison of the MRI contrast agents gadobutrol versus gadoteridol in patients with primary and secondary brain tumours, evaluated in a blinded read.

OBJECTIVE: To prove that 1.0 M gadobutrol provides superior contrast enhancement and MRI image characteristics of primary and secondary brain tumours compared with 0.5 M gadoteridol, thereby providing superior diagnostic information. METHODS: Brain MRI was performed in two separate examinations in patients scheduled for neurosurgery. Independent injections of 1.0 M gadobutrol and 0.5 M gadoteridol at doses of 0.1 mmol Gd/kg body weight were administered per patient in randomised order. Evaluation was performed in an off-site blinded read. RESULTS: Fifty-one patients in the full analysis set (FAS) were eligible for efficacy analysis and 44 for the per-protocol analysis. For the primary efficacy variable "preference in contrast enhancement for one contrast agent or the other", the rate of "gadobutrol preferred" was estimated at 0.73 (95 % confidence interval 0.61; 0.83), showing significant superiority of gadobutrol over gadoteridol. Calculated lesion-to-brain contrast and the results of all qualitative secondary efficacy variables were also in favour of gadobutrol. Keeping a sufficient time delay after contrast application proved to be essential to get optimal image quality. CONCLUSION: Compared with 0.5 M gadoteridol, 1.0 M gadobutrol was proven to have significantly superior contrast enhancement characteristics in a routine MRI protocol of primary and secondary brain tumours.

[First clinical results in a study of contrast enhanced magnetic resonance angiography with the 1.0 molar gadobutrol in peripheral arterial occlusive disease--comparison to intraarterial DSA]. / Erste klinische Erfahrungen zur Wertigkeit der kontrastverstärkten Magnetresonanzangiographie der Becken-Bein-Strombahn mit dem 1,0 molaren Gadobutrol--Vergleich zur i. a. DSA.

PURPOSE: To assess the value of contrast enhanced (CE)-MR angiography (MRA) with 1.0 molar Gadobutrol (Schering, Germany) in comparison to intraarterial DSA in peripheral arterial occlusive disease (PAOD). MATERIALS AND METHODS: Within 48 hours, 30 symptomatic patients with PAOD were examined by CE-MRA (Gadobutrol dose 0.2-0.3 mmol/kg body weight) and DSA. For CE-MRA, a 1.5 T magnet (Vision, Siemens, Germany) was used (FA 35 degrees, TR/TE 4.6/1.8 ms, FOV 400 mm, matrix 230 x 512, total acquisition time 81 sec). Two radiologists evaluated a total of 600 vessel segments for stenotic lesions and image quality (1 = not visible to 5 = excellent). Treatment was independently planned on the basis of the MRA and DSA findings. RESULTS: The Kendall's tau-b coefficient was 0.92 for overall stenotic grading, and 0.92, 0.93 and 0.92, respectively, for the vascular flow in the iliac, femoropopliteal and crural arteries. Sensitivity, specificity, negative and positive predictive value, and accuracy were, respectively, 94, 97, 98 and 92, 96 % for > 50 % stenoses, 95, 99, 99, 95 and 99 % for iliac arteries, 96, 98, 98%, 94 and 97 % for femoropopliteal arteries, and 92, 94, 96, 89 and 94 % for crural arteries. Therapy planning by MRA and DSA coincided in 51 of 54 cases. No relevant adverse event occurred. CONCLUSION: CE-MRA with 1.0 molar Gadobutrol is highly efficient in diagnosing peripheral arterial occlusive disease and correlates excellently with DSA.

In vitro evaluation of vascular permeability to contrast media using cultured endothelial cell monolayers.

OBJECTIVE: The efficiency of contrast agents in medical imaging depends on their distribution into vascular and interstitial compartments. The aim of this study was to compare in vitro endothelial permeability to different classes of contrast agents with various vascular persistence properties: a triiodinated nonionic monomer (ioversol), an iodinated dextran polymer (P604), and an iron oxide nanoparticle (sinerem). METHODS: Permeability studies, through collagen-coated filters with or without porcine aortic endothelial cell monolayer, were carried out by placing each filter-ring (luminal chamber) into a beaker containing a culture medium (abluminal chamber). Contrast media, diluted in the culture medium, were added to the luminal chamber. Aliquots were sampled from the abluminal chamber for contrast agent determinations. The volume cleared of the compound was calculated from the luminal side to the abluminal side. Parallel permeability tests to [3H]-H2O and Evans blue albumin were performed as references. Finally, the modulatory effect of bradykinin on endothelial permeability to albumin or to contrast agents was studied. RESULTS: The volume cleared of ioversol, P604, and sinerem through membrane filters was decreased by 19.6%, 32.1%, and 52.0%, respectively, in the presence of a cell monolayer. Bradykinin (10(-6) M) significantly increased permeability to albumin, ioversol, and sinerem. Ioversol and sinerem induced a significant decrease in permeability to albumin. CONCLUSIONS: A relation between the molecular size of the contrast agents tested and their endothelial permeability can be established with this in vitro model.

Extraspinal dural arteriovenous fistula in a patient with lipomyelodysplasia: value of MRI and MRA.

Spinal dural arteriovenous fistulae are extremely rare in spinal dysraphism. A fistulous malformation within a lipomyelomeningocele has not been reported previously. A 50-year-old man presented with progressive paraparesis and bladder dysfunction. MRI revealed a large lumbar lipomyelomeningocele. A vascular malformation was indicated by abnormal signal in the thoracolumbar spinal cord and dilated perimedullary veins. Phase-contrast MRA demonstrated only the slow-flow veins of the fistula and an intradural ascending vein. Contrast-enhanced ultra-fast MRA gave excellent delineation of all parts of the fistula within the dysraphic lesion.

Structure-activity relationship of macrocyclic and linear gadolinium chelates: investigation of transmetallation effect on the zinc-dependent metallopeptidase angiotensin-converting enzyme.

Transmetallation between commercially available solutions of gadolinium (Gd) chelates and the zinc (Zn)-dependent angiotensin-converting enzyme (ACE) was investigated. In vitro, the strongest inhibitions were observed for the linear Gd complexes, Gd diethylenetriamine pentaacetic acid (DTPA) bis-methylamide (BMA) (IC50 = .016 +/- .006 mmol/l) and Gd-DTPA (IC50 = .350 +/- .034 mmol/l). The two macrocycles Gd tetraazacyclododecane tetraacetic acid (DOTA) and Gd-HP-DO3A were similar and 400 times less active than Gd-DTPA-BMA. These effects were mainly due to the presence of free ligand for DTPA and calcium (Ca) chelate in the case of DTPA-BMA because the addition of Zn2+ in the same quantities suppresses their inhibitory effects. In vivo, these two solutions of linear Gd chelates significantly inhibited ACE activity (Gd-DTPA: (67 +/- 9% versus baseline; and Gd-DTPA-BMA: 73 +/- 2% versus baseline at the clinical dose of .1 mmol/kg), whereas no significant effect was observed for the two macrocyclic chelates Gd-DOTA and Gd-HP-DO3A. Formulating the Gd chelate solution with either an excess of free ligand or Ca chelate (to decrease Gd3+ release) in the case of linear Gd chelate may have deleterious biologic consequences.

Development of an endoscopic navigation system based on digital image processing.

We developed a new system to couple the endoscope to an optical position measurement system (OPMS) so that the image frames from the endoscope camera can be labeled with the accurate endoscopic position. This OPMS is part of the EasyGuide Neuro navigation system, which is used for microsurgery and neuroendoscopy. Using standard camera calibration techniques and a newly developed system calibration, any 3-dimensional (3-D) world point can be mapped onto the view from the endoscope. In particular, we can display the coordinates of any anatomical landmark of the patient as it is viewed from the current position of the camera. This and other image-processing techniques are applied to the labeled frame sequence in order to offer the neurosurgeon a variety of control modules that increase the safety and flexibility of neuroendoscopic operations. Several modules, including a new motion alarm system and the "tracking" and "virtual map" modules, were tested in a human cadaveric model using the frontal and occipital approaches. A failure rate of 8.6% was experienced during testing of the first version of the software, but the second version was 100% successful. Thus, an endoscopic navigation system based on digital image processing has been developed that could be a revolutionary advance in image-guided surgery.

[3-D-TONE magnetic resonance angiography in the detection of intracranial aneurysms compared with digital subtraction angiography. A prospective study]. / 3-D-MT-TONE-Magnetresonanzangiographie zum Nachweis intrakranieller Aneurysmen im Vergleich zur digitalen Subtraktionsangiographie--Eine prospektive Studie.

PURPOSE: To evaluate the efficiency and accuracy of the optimized 3-D-MT-TONE-magnetic resonance angiography (MRA) with that of intraarterial digital subtraction angiography (DSA) in the detection of intracranial aneurysms. MATERIAL AND METHODS: From March 1994 to March 1995 30 patients with 38 aneurysms were prospectively subjected to MRA as well as to DSA. Respiratory insufficient patients were excluded from MRA. RESULTS: The aneurysm size ranged from 3-50 mm with an average size of 9 mm. Correct diagnosis was done in 33 aneurysms (86.8%) in 26 of the patients. In 4 patients (13.3%) with 5 aneurysms, the blinded readers made an incorrect diagnosis due to degradation of image quality. One (2.6%) aneurysm was falsely described via MRA as well as via DSA. The sensitivity was 86.8%. In the control group of 30 patients three aneurysms were found, therefore the specificity was 90% and we could calculate a positive predictive value of 97.1%, a negative predictive value of 84.4% and a correct diagnosis of 90.1%. CONCLUSION: Our results show that MT-TONE-MRA is a useful non-invasive technique with improved vascular detail and vascular background for detection of intracranial aneurysm. Further technical improvements are necessary for better visualisation of pathological findings in the carotid siphon, where only 60% of the aneurysms could be clearly detected.