Transarterial radioembolization (TARE) with yttrium 90 microspheres is an increasingly popular therapy for both primary and secondary liver malignancies. TARE entails delivery of β-particle brachytherapy and embolization of the tumor vasculature. The consequent biological sequelae are distinct from those of other transarterial therapies for liver tumors, as reflected in the often baffling post-treatment imaging features. As the clinical use of TARE is increasing, more diverse post-treatment radiological findings are encountered with variable overlap among treatment response, residual disease, reactionary changes and complications. Thus, post-TARE image interpretation is challenging. This review provides a comprehensive description of the different findings seen in post-treatment scans, with the aim of facilitating appropriate radiological interpretation of post-TARE pathologic changes, notwithstanding their existing limitations.
The role of imaging in the management of rectal malignancy has progressively evolved and undergone several paradigm shifts. Unlike a few decades ago when the role of a radiologist was restricted at defining the longitudinal extent of the tumour with barium enema, recent advances in imaging techniques permit highly accurate locoregional and distant staging of the disease as well as prognostication on those who are likely to have a postoperative recurrence. Computed tomography (CT) has always been the mainstay of imaging when evaluating for distant metastasis, with the advent of positron emission tomography/CT improving its specificity. In rectal malignancy, it is the local extent of the disease that often influences the surgical decision making and need for neoadjuvant therapy. Although endoscopic ultrasound has been the traditional technique for determining the depth of tumour invasion, over the last decade magnetic resonance imaging (MRI) has emerged as a very effective tool for accurate T-staging. This review intends to address the status of various imaging modalities and their advantages and limitations in detection, pretreatment staging, and assessment of therapeutic efficacy in rectal cancer, with emphasis on MRI of high spatial resolution.
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