Clinical Techniques in Humans

Traditional radiology is based on differences in density of lesions compared with the surrounding normal tissue. These techniques are fast, cheap, easily performed, and available everywhere, even at the bedside. Ultrasonography has strong diagnostic accuracy when evaluating both superficial and deep structures, discriminating between solid and liquid components. Computed tomography is the current major radiological technique, with X-rays allowing three-dimensional spatial and structural analysis. Magnetic resonance imaging can produce multi-parametric images depending on the molecular context. Different tissue variables, including spin density, T1 and T2 relaxation times, flow, and spectral shifts, can be used to construct images. Nuclear medicine is a medical specialty that uses radionuclides for diagnostic and therapeutic purposes. In contrast to morphostructural techniques, where pathology is the gold standard, nuclear medicine is based on pathophysiological premises.