Routine diagnostic imaging of malignant and benign masses of the liver is performed by a variety of means but to a lesser extent with which of the following?

Routine diagnostic imaging for masses of the liver is commonly performed using various modalities, each offering unique advantages. Ultrasound is often favored due to its accessibility, cost-effectiveness, and non-invasive nature, making it a first-line tool in many clinical settings. However, when considering the full spectrum of imaging techniques used to evaluate both malignant and benign liver masses, ultrasound is utilized to a lesser extent compared to other advanced imaging modalities such as CT, MRI, and PET.

CT scans provide detailed cross-sectional images and are particularly useful for evaluating liver lesions due to their rapid acquisition time and ability to characterize different types of masses. MRI offers superior soft tissue contrast and is especially effective for assessing complex liver structures and determining the nature of lesions. PET scans, while less frequently used for routine diagnostics of liver masses, play a critical role in assessing metabolic activity and detecting malignancies.

Thus, while ultrasound is an important diagnostic tool for liver masses, it is employed less extensively than the other imaging modalities mentioned, particularly in cases where detailed characterization or assessment of underlying pathology is necessary.