DIFFERENTIAL THI Dr. Miriam M. Shanaman VMD, MS, DACVR Veterinary Specialty Hospital, San Diego, CA

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DIFFERENTIAL THI

As the use of diagnostic ultrasound becomes more widespread in the veterinary

profession, veterinary professionals (both in general and specialty practice) expect

continued advancements in ultrasound imaging technology so that they may best

serve their small and large animal patients. Toshiba recognizes the clinical necessity

of remaining at the forefront of ultrasound imaging technology as improved technology

relates directly to providing the very best medical care. Differential THI is an example of

this advanced technology.

Differential THI relies on the simultaneous transmission of 2 pulses at different frequencies. Signals are

received both at harmonic and differential frequencies with cancellation of fundamental signals using

pulse subtraction. The result is excellent spatial and contrast resolution that is not compromised with

increased penetration.

In clinical practice, Differential THI is the mainstay in all ultrasound examinations while fundamental

B-mode imaging is relatively obsolete. The preservation of spatial and contrast resolution at increasing

imaging depths is paramount in the evaluation of large viscera (particularly the liver and spleen) and

larger veterinary patients. Figure 1 demonstrates the differences between fundamental and Differential

THI imaging in a healthy dog’s liver.

DIFFERENTIAL THI

Figure 1

Images A and B include the liver and a portion of the stomach. Note that Differential THI improves

definition of the intra-hepatic vasculature and gastric wall layering. Images C and D include a portion of

the right liver and gallbladder with Differential THI resulting in similar improvements in spatial and contrast

resolution; particularly at greater depths.

Image A: Fundemental Imaging Image B: Differential THI

Image C: Fundemental Imaging Image D: Differential THI

Ultimately, Differential THI has allowed the veterinary sonographer to confidently scan patients that vary

greatly in size by using a limited number of transducers without compromising diagnostic quality.