Estimation of Tumor Interstitial Fluid Pressure (TIFP) Noninvasively.

Tumor interstitial fluid pressure (TIFP), is a physiological parameter with demonstrated predictive value for a tumor's aggressiveness, drug delivery, as well as response to treatments such as radiotherapy and chemotherapy. Despite its utility, measurement of TIFP has been limited by the need for invasive procedures. In this work, the theoretical basis for approaching the absolute value of TIFP and the experimental method for noninvasively measuring TIFP are presented. Given specific boundary and continuity conditions, we convert theoretical variables into measurable variables by applying MRI technology. The work shows that TIFP in the central region of the tumor can be estimated by an analysis of the variation of tissue fluid motion in the tumor rim and surrounding tissue. It is determined from three noninvasive measurable parameters: i) an estimate of the velocity of the tumor interstitial fluid at the tumor surface, which is maximal, ii) a measurement of the distance from the tumor surface to where the tumor exudates are absorbed (or normalized), and iii) an estimate of the hydraulic conductivity of the interstitium through which the tumor exudate travels. We experimentally show that the fluid flow within the tumor rim is not uniform, even for a round shaped tumor, and demonstrate the procedures for the noninvasive measurement of TIFP.

The next generation HydroCoil: initial clinical experience with the HydroFill embolic coil.

BACKGROUND: Complete packing of intracranial aneurysms has demonstrated a significant decrease in aneurysm recurrence rates with increased volumetric filling. The HydroCoil Embolization System (HES) was developed to increase volumetric filling within the aneurysm sac to maintain long term occlusion. To further enhance ease of HES deployment, a new next generation embolic coil, the HydroFill coil, was developed. OBJECTIVE: To report the first clinical experience with the HydroFill coil, focusing on safety and effectiveness, with immediate and long term follow-up on cases performed at a single institution by a single operator. METHODS: Retrospective angiographic and clinical analysis was performed on a non-randomized single arm registry of the first consecutive 11 patients with 14 intracranial saccular aneurysms treated during a 9 month period. RESULTS: The immediate angiographic occlusion rate according to the Raymond scale was 100%. Overall packing density of all coils used was 13-135% (mean 64%). The immediate complication rate was 9% (1/11 patients), secondary to a parent vessel occlusion which resolved after intravenous administration of eptifibatide (Integrilin) without neurological sequelae. The angiographic/MR angiography follow-up period for this series was 13-30 months, with an overall complete occlusion rate of 86% (12/14 aneurysms). 2/14 aneurysms (14%) converted from complete occlusion to filling of small neck remnants. Of the two, one (7%) was a cavernous aneurysm that was retreated. CONCLUSIONS: Although this initial case series is small, this study demonstrates safe deployment of the HydroFill coil in ruptured and unruptured aneurysms without major complications, and with a high rate of occlusion on long term follow-up.