Optimal occlusion pattern for minimally invasive staged segmental artery coil embolization in a chronic porcine model.

OBJECTIVES: Minimally invasive staged segmental artery coil- and plug embolization (MIS2ACE) has been introduced for spinal cord injury prevention prior to open or endovascular thoraco-abdominal aortic aneurysm repair. To date, no optimal pattern has been developed. The aim of this study was to identify the optimal MIS2ACE occlusion pattern. METHODS: Twenty-five juvenile pigs were randomly assigned to 3 MIS2ACE occlusion patterns (2 stages) and a control group [single-stage segmental artery (SA) occlusion, N = 7]. The first pattern started with occlusion of all lumbar segmental arteries in the first stage and the remaining thoracic arteries in the second stage (regional pattern, N = 6). In group 2, an alternating approach with occlusion of every other SA in the first stage and the remainder in the second stage was used (alternating pattern, N = 6). The third pattern started with occluding the watershed area between thoracic level 12 and lumbar level 2 in the first stage and the remaining arteries in the second stage (watershed pattern, N = 6). Neurological assessment at 6-h intervals and spinal cord tissue perfusion measurements via microspheres at 6 time points were performed. At the end of the experiments, the spinal cord was histopathologically examined. RESULTS: An average of 6 ± 2 coils were used per SA. In the control group a total of 57% (N = 4) of animals experienced permanent paraplegia, 1 animal (16%) of the alternating and watershed intervention group suffered from permanent paraplegia. Animals from the staged regional pattern did not experience permanent paraplegia. Furthermore, no evidence of significant tissue damage was observed (P < 0.05 vs control). Tissue perfusion of the lumbar spinal cord in the regional pattern group recovered within 3 days after the second stage to 89.2 ± 47 percent-of-baseline (P = 0.393), whereas mean perfusion of the other 2 intervention groups and the control remained significantly lower compared to the baseline (35.7 ± 16%, 30.2 ± 11% and 63.2 ± 19, P < 0.05). CONCLUSIONS: This study provides evidence that MIS2ACE (minimally invasive staging) may result in less ischaemic spinal cord injury and favourable neurological outcomes compared to complete (1 stage) SA occlusion. A regional-based occlusion pattern (starting with the lumbar segmental arteries) seems to be the best 2-stage approach.

UMMPerfusion: an open source software tool towards quantitative MRI perfusion analysis in clinical routine.

To develop a generic Open Source MRI perfusion analysis tool for quantitative parameter mapping to be used in a clinical workflow and methods for quality management of perfusion data. We implemented a classic, pixel-by-pixel deconvolution approach to quantify T1-weighted contrast-enhanced dynamic MR imaging (DCE-MRI) perfusion data as an OsiriX plug-in. It features parallel computing capabilities and an automated reporting scheme for quality management. Furthermore, by our implementation design, it could be easily extendable to other perfusion algorithms. Obtained results are saved as DICOM objects and directly added to the patient study. The plug-in was evaluated on ten MR perfusion data sets of the prostate and a calibration data set by comparing obtained parametric maps (plasma flow, volume of distribution, and mean transit time) to a widely used reference implementation in IDL. For all data, parametric maps could be calculated and the plug-in worked correctly and stable. On average, a deviation of 0.032 ± 0.02 ml/100 ml/min for the plasma flow, 0.004 ± 0.0007 ml/100 ml for the volume of distribution, and 0.037 ± 0.03 s for the mean transit time between our implementation and a reference implementation was observed. By using computer hardware with eight CPU cores, calculation time could be reduced by a factor of 2.5. We developed successfully an Open Source OsiriX plug-in for T1-DCE-MRI perfusion analysis in a routine quality managed clinical environment. Using model-free deconvolution, it allows for perfusion analysis in various clinical applications. By our plug-in, information about measured physiological processes can be obtained and transferred into clinical practice.