How and when did you become involved in ultra-sound?

When I just finished the Post-graduate Doctor Course of the Tohoku University, Sendai, in 1965, I was looking for new diagnostic modality for the prostate, because only examination in our hands in those ages was very classical rectal digital palpation, which was introduced in the Greeks’ era.In the early autumn of 1967, I visited a cardiologist in the same University, Dr. Motonao Tanaka, who was a leading researcher of medical engineering. The purpose of visiting was to consult a possibility of my poor idea that some sound from urinary stream in the prostate could be detected, if an electric stethoscope was inserted into the rectal cavity. Occasionally in his laboratory, I found a strange stick. It was a special ultrasonic probe to obtain a section of the heart via the esophagus.

Were there any particular people that influenced your work?

This very new device could not, however, to be used on human subjects, because it caused too much pain to insert into the esophagus. Incidentally and luckily, I became involved in the situation. My poor idea for an intrarectal stethoscope was abandoned at once and we agreed enthusiastically to apply the new device to trying to obtain a prostatic section via the rectum.The very next day, I took a patient with benign prostatic hyperplasia to Dr. Tanaka’s laboratory. After much entreating and some threats he was laid on the bed and the probe was inserted into his rectum. The sonogram of the prostate we obtained was fantastic. This was the first section of the prostate in a living body, of which human had ever seen, because it was 10 years before the commercialization of CT and 20 years before that of MRI. The images looked to me as if it was rose colored!

We published this world’s first image modality for the prostate under the name of “transrectal ultrasonography (TRUS)” in 1968 but following near 20 years had been spent until its generalization as a routine diagnostic modality. Today, however, we can find the “TRUS machine” in any urologic clinic in the world. In October, 2017, the “50 years Memorial Symposium for TRUS” was organized in the WFUMB 2017 Congress in Taipei.

Were there any particular people that influenced your work?

As mentioned in my previous answer, Dr. Tanaka led me into the ultrasound world. At that time, he had already obtained the world’s first ultrasound tomograms of the moving human heart by means of an originally developed ECG-synchronized pulse-projecting ultrasound technique, 15 years before the appearance of real-time ultrasound. According to this technique, ultrasonograms of each phase of cardiac section were taken by a rotation of the angle of ultrasound beam little by little. Though it took more than an hour to record 20-30 sonograms of all phases, the obtained sections were far much clearer than sonograms by real-time scanner in later years. He is still active in research works even now.