Three-dimensional analysis leads to a novel method of predicting the characteristics of a tumour and can be directly applied to the incorporation of tactile sensing in artificial palpation, helping surgeons in non-invasive procedures.

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Purpose Tests on animals of different species with large differences in intervertebral disc size are commonly used to investigate the therapeutic efficacy of intravenously injected solutes in the disc. We hypothesize that disc size markedly affects outcome. Methods Here, using a small non-metabolized molecule, glucosamine (GL) as a model solute, we calculate the influence of disc size on transport of GL into rat, rabbit, dog and human discs for 10 h post intravenous-injection. We used transient finite element models and considered an identical GL supply for all animals. Results Huge effects of disc size on GL concentration profiles were found. Post-injection GL concentration in the rat disc reached 70 % blood concentration within 15 min but remained below 10 % in the human disc nucleus throughout. The GL rapidly penetrated post-injection into smaller discs resulting in homogeneous concentrations. In contrast, GL concentration, albeit at much lower levels, increased with time in the human disc with a small outward flux at the annulus periphery at longer periods. Conclusions Changes in the disc size hugely influenced GL concentrations throughout the disc at all regions and times. Increases in administered dose can neither remedy the very low concentration levels in the disc center in larger human disc at early post-injection hours nor alter the substantial differences in concentration profiles estimated among various species. The size effect will only be exacerbated as molecular weight of the solute increases and as the endplate calcifies. Extrapolation of findings from animal to human discs on the efficacy of intravenously administered solutes must proceed with great caution.

We proposed a method to investigate the effects of the tumor existence that appear on the surface of the tissue. Finite element analysis provided properties such as the shape, depth, and location of the tumor which are important parameters for physicians to distinguish the correct condition of the patients. Several different cases were created and solved by the ANSYS software and Tactile Images and Stress Graphs were extracted. These results clearly showed the existence of the tumor in the tissue. Having made an artificial tactile sensing system, called "Tactile Tumor Detector", which consists of three main components namely: tactile probe, tactile data processor and tactile display and having performed a number of experiments, we obtained good agreements between the numerical and experimental results. In addition to anticipating the presence of a tumor in the tissue and locating the exact place of the tumor, the experimental results help the user to predict the depth of the tumor inside the tissue

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