Replacement of Computer Tomography by Magnetic Resonance Imaging


The introduction of tomographic imaging revolutionized the way we look at medical images. Compared to X-ray projective image, Computer Tomography (CT) offers the possibility of analyzing anatomical structures on a three-dimensional, slice-to-slice approach. On the other hand, limitations of CT consist of poor soft tissue contrast and ionizing radiation, while the advantages are distortion-free images and fast scan times. Indeed, CT has been the modality of choice in many applications, going from diagnostic imaging to image-guided therapeutic solutions. The advent of Magnetic Resonance Imaging (MRI) represented a further quantum leap in tomographic imaging in that soft tissue contrast was dramatically superior to CT with no radiation dose.

On the other hand, MRI suffered from image distortion and long scan times, as well as limitation in scanning regions where metal implants are present. MRI offers a wide range of contrast generation, which makes it probably the modality with the highest potential in the imaging arena. This is reflected in the introduction of new MRI sequences in the range of 5-10 per year.

Historically, CT images represented the gold standard in cardiac applications, especially after the introduction of ultra-fast CT. The ability to quickly image multi-phase cardiac data with high spatial resolution together with a reduction in the dose whilst maintaining reasonably image quality has supported the use of CT in an increasing number of patients being examined with cardiac pathologies. The introduction of fast sequences, parallel imaging and iterative reconstruction methods are shifting the attention of the community to cardiac MRI, especially due to no dose, when multiple acquisitions are needed. In addition to that, new acquisition and post-processing techniques hold the potential to provide information about flow, ischemic heart disease functional information as well as morphological information of heart.

In conclusion, the aforementioned examples suggest that MRI is filling the gap compared to CT, making it potentially the future modality of choice in imaging and therapeutic applications. Also, the potential offered by functional and molecular MRI is likely to differentiate even more this modality leading to the substitution of CT with MRI in the future. 

Aaron Province
Journal of Biotechnology & Biomaterials
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