**3. Description of the procedure**

HIFU is performed through a computerized surgical device equipped with a treatment table, an ultrasound treatment system connected to an endorectal probe, a safety infrared ray detector, a refrigeration system keeping the rectal mucosa temperature below 14°C and a monitor to set and control the treatment procedure through echographic screening (Fig. 1). For anatomical reasons, the transrectal approach appears ideally suited to ablate prostatic tissue because the proximity of HIFU transducer and target tissue facilitates HIFU treatment from the technical standpoint.

After introducing the rectal probe, anatomic landmarks must be echographically set (apex, bladder neck, rectal side, prostate capsule), in order to make the computer able to determine the correct subdivision in different prostate portions (generally four).

The probe is equipped with a transducer that gives out a beam of high-focused convergent ultrasounds. The HIFU transducer has an aperture of 37 cm and a focal distance of 25.5 cm.

The focus has a -6 dB beam width of 1.6 mm and axial length of 10 mm. In the ultrasound converging point (focal point), the ultrasound beam absorption generates an immediate growth of temperature (85-100°C), destroying prostate cells in the circumscribed area.

(Ablatherm®-Edap Technomed device).

Fig. 1. Overview of HIFU procedure. The bed with the High-intensity ultrasound probe can be clearly seen. On the right, the ultrasound screen and the screen to set the machine and follow the procedure

HIFU has also been used in other clinical fields including ophthalmology (Coleman, 1985), urology (by Foster and Gelet in 1993) and oncology (Chapelon in 1992 and Prat in 1995). To date, focused ultrasound has been used successfully in the management of many tumours, including prostate cancer, in which this technique represents a good treatment option. HIFU was also used by Madersbacher and colleagues as a treatment for Benign Prostatic Hyperplasia (BPH). To date, this technique is not still used to treat BPH, because of its side

HIFU is performed through a computerized surgical device equipped with a treatment table, an ultrasound treatment system connected to an endorectal probe, a safety infrared ray detector, a refrigeration system keeping the rectal mucosa temperature below 14°C and a monitor to set and control the treatment procedure through echographic screening (Fig. 1). For anatomical reasons, the transrectal approach appears ideally suited to ablate prostatic tissue because the proximity of HIFU transducer and target tissue facilitates HIFU treatment

After introducing the rectal probe, anatomic landmarks must be echographically set (apex, bladder neck, rectal side, prostate capsule), in order to make the computer able to determine

The probe is equipped with a transducer that gives out a beam of high-focused convergent ultrasounds. The HIFU transducer has an aperture of 37 cm and a focal distance of 25.5 cm. The focus has a -6 dB beam width of 1.6 mm and axial length of 10 mm. In the ultrasound converging point (focal point), the ultrasound beam absorption generates an immediate growth of temperature (85-100°C), destroying prostate cells in the circumscribed area.

Fig. 1. Overview of HIFU procedure. The bed with the High-intensity ultrasound probe can be clearly seen. On the right, the ultrasound screen and the screen to set the machine and

the correct subdivision in different prostate portions (generally four).

effects on bladder neck function.

from the technical standpoint.

(Ablatherm®-Edap Technomed device).

follow the procedure

**3. Description of the procedure** 

Adequately translating the focal point with a robotic and automatic device, the successive ultrasound emissions may destroy all prostate cells (Fig. 2).

Fig. 2. Anatomical scheme of HIFU endorectal device

These lesions have a predictable size and shape, closely matching the focal region of the ultrasound source. As the lesion width is almost constant along their length, they can be placed side-by-side without leaving gaps (Fig. 3).

Fig. 3. HIFU mechanism scheme. On the left, ultrasound beam positioning; in the middle, the area to treat; on the right, an overall view of the sections treated by high-intensity ultrasound.

A standard procedure can be personalized in order to obtain ideal treatment settings: ultrasound frequency (standard 3 MHz), shot duration (standard 5 seconds) and waitingtime between shots (standard 5 seconds) may be modified (Fig. 4). Elementary lesion volume measures 19-24 mm and its diameter measures 1.7 mm

High-Intensity Focused Ultrasound (HIFU)

pharmacodynamic features.

**5. Mechanism** 

2. Cavitation; 3. Heat damage.

1. Coagulative necrosis;

**5.1 Coagulative necrosis** 

active nuclei, and organelles.

amount of necrotic areas.


Other benzodiazepine can be used, according with their pharmacocynetic and

Reportedly, patients have no postoperative pain, except in case of complication. Just in the first two hours after the treatment the patient might complain of confusion and dazzling,

The anaesthetist should be involved pre-operatively, intra-operatively and post-operatively, in order to manage the patient properly before and during the treatment and in order to

Conceptually, a piezoelectric transducer generates a high intensity converging ultrasound

Coagulative necrosis, is due to hyperthermia (85-100°C) generated in the focal point.

Fig. 5. On the left, pre-HIFU histology aspect; on the right, post-HIFU histology change

the HIFU technique provides a lack of function in the treated prostate.

This kind of lesion can be clearly seen on optical microscopy. Its effectiveness in cancer treatment is demonstrated by the absence of cell functional structures, such as membranes,

After the treatment, glandular structures cannot be seen any longer, thus demonstrating that

Also liquefactive necrosis and apoptotic necrosis are reported as a common consequence of HIFU treatment (see § 6.1), but these kinds of necrotic lesions do not affect the whole

Elementary lesion has ellipsoidal shape. The short length of the shot limits heat diffusion around the focal point. Shot by shot, it is possible to generate a plethora of elementary

but these are considered common consequences of the anaesthetic treatment.

relieve post-operative pain and anaesthetic side-effects and/or complications.

beam that destroys local tissues through three mechanisms:

Coagulative necrosis is a non-reversible phenomenon (Fig. 5).

These three key-points are discussed below.

lesions until all prostate tissue is destroyed.

Fig. 4. On the screen, it is possible to follow the procedure and to change settings, such as ultrasound frequency and shot duration. Thus, a safe and optimal treatment can be performed.
