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In the field of gynecologic oncology, the various diagnostic modalities available serve as invaluable tools in the diagnosis, management, staging, treatment, and monitoring of gynecologic malignancies. Technological advances in existing modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) have furthered their utility as diagnostic and management instruments, while the indications for newer imaging modalities such as 2-(18F)-fluoro-2-deoxy-D glucose (FDG) positron emission tomography (PET)/CT continue to expand. The use of tumor markers in identifying disease and molecular pathology in confirming which specific disease exists is presented. Because of the important role played by these diagnostic tools, the gynecologic oncologist must possess at least a passing familiarity with the basic science underlying these diagnostic instruments, as well as understand their advantages and limitations in imaging the spectrum of gynecologic cancers. Not all diagnostic modalities are useful or appropriate in evaluating the different and varied gynecologic cancers. Furthermore, the impact of diagnostic studies in the field of gynecologic oncology is ever expanding as newer technological developments become available to the clinician who must understand how to translate these advancements into improved patient care. Finally, as cost-effectiveness becomes an ever more important driver of health care decision making, it behooves the gynecologic oncologist to understand the various diagnostic tools in his armamentarium in order to use them to maximal effect.
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Diagnostic imaging is an expanding field that has replaced radiology and now encompasses numerous new and varied technologies.
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Ultrasound is the most widely used imaging modality in the field of gynecology and is often the initial radiologic study used in the evaluation of pelvic abnormalities. Ultrasound technology uses a hand-held transducer containing piezoelectric crystals capable of emitting high-frequency sound waves that are projected into the patient's body. Emitted frequencies range from 7.0 to 8.0 MHz, used in transabdominal scanning, and up to 9.0 MHz is generally used in transvaginal ultrasound (TVUS). Higher-frequency sound waves result in improved image resolution, but reduced tissue penetration. The piezoelectric crystals serve as both the emitter and receiver of the sound waves. As the wave encounters tissue surfaces, it is both reflected and transmitted. The reflected wave returns to the transducer, where it is converted into an electrical signal, which is termed an echo, and the signal is amplified and converted into different shades of gray based on the degree of amplification. Stronger echoes are perceived as whiter shades, whereas weaker echoes are assigned darker shades.
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Doppler ultrasonography can be added to basic ultrasound studies in order to evaluate vascular structures and blood flow. Doppler ultrasonography uses the principles of the Doppler Effect, which states that a moving object will emit a wavelength with differing frequencies and lengths based on whether the object is moving toward or away from the source emitting the sound wave. The sound waves emitted by the ultrasound ...