Trimodality PET/CT/MRI and Radiotherapy: A Mini-Review

Abstract

Computed tomography (CT) has revolutionized external radiotherapy by making it possible to visualize and segment the tumors and the organs at risk in a three-dimensional way. However, if CT is a now a standard, it presents some limitations, notably concerning tumor characterization and delineation. Its association with functional and anatomical images, that are positron emission tomography (PET) and magnetic resonance imaging (MRI), surpasses its limits. This association can be in the form of a trimodality PET/CT/MRI. The objective of this mini-review is to describe the process of performing this PET/CT/MRI trimodality for radiotherapy and its potential clinical applications. Trimodality can be performed in two ways, either a PET/MRI fused to a planning CT (possibly with a pseudo-CT generated from the MRI for the planning), or a PET/CT fused to an MRI and then registered to a planning CT (possibly the CT of PET/CT if calibrated for radiotherapy). These examinations should be performed in the treatment position, and in the second case, a patient transfer system can be used between the PET/CT and MRI to limit movement. If trimodality requires adapted equipment, notably compatible MRI equipment with high-performance dedicated coils, it allows the advantages of the three techniques to be combined with a synergistic effect while limiting their disadvantages when carried out separately. Trimodality is already possible in clinical routine and can have a high clinical impact and good inter-observer agreement, notably for head and neck cancers, brain tumor, prostate cancer, cervical cancer.

A review of the research progress of interventional medical equipment and methods for prostate cancer

“…110 Thus, CT can be used to locate the seed position and detect the dose after implantation. 111,112 TRUS uses the difference in acoustic impedance and attenuation characteristics of different tissues and organs. uncontrollable situations and improve safety.…”

Triple-combination therapy assisted with ultrasound-active gold nanoparticles and ultrasound therapy against 3D cisplatin-resistant ovarian cancer model

“…In the presence of US therapy, the porosity of the cell membrane increases due to the mechanical effect [8] . It also has advantages over other clinical treatments used in cancer therapy such as photothermal therapy [9] and radiation therapy [10] since it is non-invasive, has high tissue penetration, and the acoustic wave does not cause systemic toxicity [11] . In addition to these advantages of US therapy, it offers a definite innovative and important new perspectives in cancer treatment such as an increased therapeutic concentration in the tumor [12] , immunomodulating effects [13] , and different focused ultrasound therapy modalities [14] , [15] .…”

Clinical value of MRI, serum SCCA, and CA125 levels in the diagnosis of lymph node metastasis and para-uterine infiltration in cervical cancer

“…MRI not only clearly identifies para-uterine infiltration and LNM in cervical cancer, but also has high resolution to soft tissues of the uterus and cervix. It is able to accurately determine tumor volume, para-uterine infiltration, and LNM because of no ionizing radiation [15,16], which, thus, can be taken as one of the most respected imaging technologies in cervical cancer [17,18]. Although these imaging methods have potential in predicting LNM, they are not ideal due to morphological indexes such as size and shape with low sensitivity (38-56%) [19,20], which may be due to micrometastatic lymph nodes.…”