Magnetic resonance temperature imaging for guidance of thermotherapy

Imaging of nuclear magnetic resonance spin-lattice relaxation activation energy in cartilage

Samples of human and bovine cartilage have been examined using magnetic resonance imaging to determine the proton nuclear magnetic resonance spin-lattice relaxation time, T₁, as a function of depth within through the cartilage tissue. T₁ was measured at five to seven temperatures between 8 and 38°C. From this, it is shown that the T₁ relaxation time is well described by Arrhenius-type behaviour and the activation energy of the relaxation process is quantified. The activation energy within the cartilage is approximately 11 ± 2 kJ mol^-1 with this notably being less than that for both pure water (16.6 ± 0.4 kJ mol^-1) and the phosphate-buffered solution in which the cartilage was immersed (14.7 ± 1.0 kJ mol^-1). It is shown that this activation energy increases as a function of depth in the cartilage. It is known that cartilage composition varies with depth, and hence, these results have been interpreted in terms of the structure within the cartilage tissue and the association of the water with the macromolecular constituents of the cartilage.

Emerging technologies for image guidance and device navigation in interventional radiology

Recent developments in image-guidance and device navigation, along with emerging robotic technologies, are rapidly transforming the landscape of interventional radiology (IR). Future state-of-the-art IR procedures may include real-time three-dimensional imaging that is capable of visualizing the target organ, interventional tools, and surrounding anatomy with high spatial and temporal resolution. Remote device actuation is becoming a reality with the introduction of novel magnetic-field enabled instruments and remote robotic steering systems. Robots offer several degrees of freedom and unprecedented accuracy, stability, and dexterity during device navigation, propulsion, and actuation. Optimization of tracking and navigation of interventional tools inside the human body will be critical in converting IR suites into the minimally invasive operating theaters of the future with increased safety and unsurpassed therapeutic efficacy. In the not too distant future, individual image guidance modalities and device tracking methods could merge into autonomous, multimodality, multiparametric platforms that offer real-time data of anatomy, morphology, function, and metabolism along with on-the-fly computational modeling and remote robotic actuation. The authors provide a concise overview of the latest developments in image guidance and device navigation, while critically envisioning what the future might hold for 2020 IR procedures.