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Abstract Background Most of the carotid plaque MR studies have been performed using black-blood protocols at 1.5 T without parallel imaging techniques. The purpose of this study was to evaluate a multi-sequence, black-blood MR protocol using parallel imaging and a dedicated 4-channel surface coil for vessel wall imaging of the carotid arteries at 3 T. Materials and methods 14 healthy volunteers and 14 patients with intimal thickening as proven by duplex ultrasound had their carotid arteries imaged at 3 T using a multi-sequence protocol (time-of-flight MR angiography, pre-contrast T1w-, PDw- and T2w sequences in the volunteers, additional post-contrast T1w- and dynamic contrast enhanced sequences in patients). To assess intrascan reproducibility, 10 volunteers were scanned twice within 2 weeks. Results Intrascan reproducibility for quantitative measurements of lumen, wall and outer wall areas was excellent with Intraclass Correlation Coefficients >0.98 and measurement errors of 1.5%, 4.5% and 1.9%, respectively. Patients had larger wall areas than volunteers in both common carotid and internal carotid arteries and smaller lumen areas in internal carotid arteries (p < 0.001). Positive correlations were found between wall area and cardiovascular risk factors such as age, hypertension, coronary heart disease and hypercholesterolemia (Spearman's r = 0.45-0.76, p < 0.05). No significant correlations were found between wall area and body mass index, gender, diabetes or a family history of cardiovascular disease. Conclusion The findings of this study indicate that high resolution carotid black-blood 3 T MR with parallel imaging is a fast, reproducible and robust method to assess carotid atherosclerotic plaque in vivo and this method is ready to be used in clinical practice.

An innovative treatment modality for brain tumors is interstitial photodynamic therapy [1,2]. The analysis of patients undergoing iPDT contain the assessment of the outcome, and qualitative changes in the MRI due to iPDT have already been reported [1,3]. Patients with newly diagnosed malignant gliomas treated with 5-aminolevulinic acid mediated iPDT were retrospectively analyzed for PDT-induced effects. For this MRI Sequences (T1-weighted with/without contrast agent, T2-weighted, Diffusion-weighted) before iPDT, within 24h after iPDT, and follow up images were quantitatively analyzed concerning changes. Furthermore, observed conspicuities were analyzed in the temporal course after iPDT and spatially compared. Postoperative MRI after therapy showed, in most cases, a circumscribed heterogeneous region, which was best visible in the T2-weighted image. This region usually shows a larger extent than the treated contrast agent accumulating tumor volume in the T1-weighted MRI. MRI regions with restricted diffusion showed high overlap with this circumscribed region visible in T2-MRI. Overall, increased edema volumes were observed after treatment, which shrank in the temporal course during follow-up. The tumor contrast enhancement was only residually visible or in unspecific areas after iPDT that could not be associated with the contrast-enhanced volume before iPDT. Similar to a pseudoprogression, the contrast-enhanced volume increased again at the first follow-up but then shrank again in the temporal course. These analyses give insight into iPDT effects visible in MRI and, with further analysis, may also provide indications for direct treatment effect. [ABSTRACT FROM AUTHOR]

Applications of photodynamic therapy and diagnosis are widely spread over many medical disciplines [1]. Optical dosimetry calculations that include the estimation of thermal effects [2-3] are inevitable to guarantee a sufficient disease control while at the same time preserving tissue at risk [4]. Optical monitoring in an interstitial setting has turned out to be very elucidating, both regarding the initial state of the tissue to be treated, and regarding therapy-induced changes of the optical properties of the tissue [5-7], beyond the assessment of photobleaching. This information can be utilized immediately in the surgery room, to individualize, monitor and optimize the therapy session, as well as to warrant and optimize patient safety. Furthermore, by combining all available information around a PDT intervention, further insight about the involved processes and mechanisms can be gained [5-6], which can be utilized to develop the therapeutic approach further as a whole. As an example, the quite promising clinical outcome of iPDT treatments on malignant brain tumors will be summarized [7-8] and evaluation concepts based on spectral online monitoring and medical imaging [5-7], before and after the intervention, will be illustrated. iPDT-induced effects, including conversion of hemoglobin, will be discussed in relation to tumor coverage by the illumination volume and the location of recurrences. [ABSTRACT FROM AUTHOR]