(TVS) The transvaginal sonography (transvaginal echography or endovaginal ultrasound), uses a small vaginal transducer (5-7.5 MHz) that is inserted into the vagina to depict the inner female organs (uterus, ovaries, vessels). As a general rule, ultrasound works better when the probe is close to the area being examined. Compared with a sonogram through the abdominal wall, the transvaginal technique produces a sharper image, not only because of the close proximity to the uterus, but also because the better signal to noise ratio of the used transducer.

Indications:

The advantage of transvaginal sonography is being able to get very close to the structures of the pelvis, and thus get better images and a more reliable diagnosis.

See also Pelvic Ultrasound, Hysterosalpingo Contrast Sonography.

Transurethral echography or sonography is used to detect small tumors of the urinary bladder or to visualize the urethra and surrounding muscles with special transducers. The bladder neck can be visualized using a transrectal probe.
In addition, high intensity focused ultrasound provides treatment of benign prostatic hyperplasia and adenocarcinoma of the prostate. Small catheter-based sectored tubular or planar transducers with highly directional energy deposition and rotational control are used for precise treatment. Regions of the prostate can be selective coagulatet while monitoring and controlling the treatment with MRI.

See also Urologic Ultrasound, Lithotripsy, Reflux Sonography, Ultrasound Therapy, Interventional Ultrasound and Thermotherapy.

Cerebrovascular ultrasonography is the best screening tool for the detection of carotid artery stenosis. Transcranial sonography is used in the evaluation of patients with suspected cerebrovascular disease, but a common problem is the attenuation of the ultrasound signal by the skull.
Contrast enhanced ultrasound play a particularly important role in the visualization of the intracranial vessels, and thus improves the accuracy of transcranial Doppler and increases the potential of this technique. The use of microbubbles is helpful for classification of stenosis and for plaque evaluation in patients with poor initial examination. Ultrasound contrast agents avoid misdiagnosing a subtotal stenosis, which is a very important clinical issue.

See also Adventitia, Intima, Periorbital Doppler, and Acoustic Window.

(HyCoSy) Hysterosalpingo contrast sonography is used for evaluation of fallopian tube patency in patients with fertility problems who underwent transvaginal sonography. HyCoSy compared to more invasive techniques such as chromo-laparoscopy is rapidly becoming the screening test of choice to determine tubal patency.
Any body cavity that can be accessed can, in principle, be injected with vascular contrast. The contrast agent is instilled into the uterine cavity via a small Foley type catheter and, using transvaginal echography, the passage of the echogenic contrast along the tubes and into the adnexal peritoneum is tracked.
Hysterosalpingo contrast sonography does not offer the same anatomical and false negative results, e.g., because of tubal spasm, are possible so conventional X-ray salpingography is needed when tubal surgery is an option.

See also Endocavitary Echography, Transvaginal Sonography.

(TCCS) Transcranial color coded sonography is a combination of B-mode and pulsed wave Doppler. TCCS is used to study morphological and functional assessment of the circle of Willis, intracranial hemodynamics caused by extracranial artery stenosis, collateral flow and the vascular supply of intracranial lesion. Color imaging of the intracranial vessels allows placing the spectral Doppler volume correctly. This modality has encouraged the widespread use.
Contrast enhanced TCCS analysis of cerebral arteriovenous transit time (cTT) is used as a measure of cerebral microcirculation.
The windows that are used for transcranial Doppler examinations include regions where the skull bones are relatively thin or where naturally occurring gaps allow proper penetration of the sound beam.

See also A-Mode, Cranial Bone Thermal Index, Transcranial Doppler and Transcranial Window.