Final answer:
Transvaginal ultrasound is the initial imaging used to evaluate a suspected ovarian tumor due to its detailed imaging capabilities and its status as the least invasive technique. CT scans or MRIs may be used for further evaluation if needed.
Step-by-step explanation:
To evaluate a suspected ovarian tumor, the imaging of choice is D) Transvaginal ultrasound. This method is preferred because it offers detailed images of the ovaries and is the least invasive technique. Using sound waves rather than radiation, it provides a safer option, especially during pregnancy, and can be used to monitor both the development of a fetus and check for the presence of ovarian tumors. If further imaging is needed after an initial transvaginal ultrasound, additional techniques such as CT scan or MRI may be employed; however, they are usually not the first choice due to their use of radiation in the case of a CT scan, and their typically higher cost and limited availability compared to ultrasound.
It's essential to note that a CT scan, although not typically used first in evaluating ovarian tumors, utilizes X-rays to create cross-sectional images of the body and can be very detailed for detecting tumors or other abnormalities after initial screening. Meanwhile, an MRI uses a magnetic field to visualize structures inside the body without exposing the patient to radiation, making it a suitable, but more expensive, alternative as a follow-up imaging technique.