Osteoma, Osteoid Clinical Trial
Official title:
Treatment of Osteoid Osteoma With MR Guided High Intensity Focused Ultrasound
Non-invasive treatment of Osteoid osteoma using MRI guided high-intensity focused ultrasound. This study is designed as an intention-to-treat using a totally non-invasive approach for pain reduction, quality of life improvement and long-term bone restoration. Procedure is performed in a single session using limited amount of acoustic energy to target the osteoid nidus. Treatment will be performed under anesthesia (peripheral or general according to age and lesion position).
An osteoid osteoma is a benign, painful musculoskeletal tumor that usually occurs in young
males. The standard of care in the United States is computed tomography (CT)-guided
radiofrequency ablation, a minimally invasive percutaneous procedure, with clinical success
rates ranging between 85% and 98%.
Percutaneous or surgical therapy can lead to non-negligible side-effects and limited
efficacy for pediatric population or young adults with osteoid osteoma. We investigate
whether selective focal ablation of osteoid lesions can reduce this treatment burden without
compromising long-term clinical efficacy.
Treatments will be performed using a 3.0-T MR unit (Discovery MR 750; GE Medical Systems,
Milwaukee,Wis) featuring a Conformité Européenne-approved ExAblate MR-guided focused
ultrasound system (InSightec,Tirat-Carmel, Israel) in which the ultrasound transducer is
housed in the patient table. Alignment between the lesion and the transducer will be
obtained in each patient by using a moistened gel pad and degassed water for acoustic
coupling. This approach avoided air- skin interfaces, which can cause energy reflection and
skin burns. After patient positioning, the lesion is localized with MR for treatment by
using variably orientated non enhanced T1- and T2-weighted acquisitions. In general, an
ideal 90° incidental angle between the planned focused ultrasound path and the lesion,
relative to the bone long axis, is obtained or at least approximated. The shortest
skin-lesion distance is selected for the beam pathway. Care will be taken to avoid multiple
interfaces (skin, muscle, fasciae) as much as possible so as to minimize deflection of the
focused ultrasound beam. Each lesion will be manually segmented by the operator to precisely
delineate the nidus, skin surface, and cortical surface of the bone. Sensitive areas
surrounding the target volumes will also be drawn to limit the energy and prevent unwanted
thermal damage. The treatment plan is than calculated automatically by the ExAblate software
according to previously acquired parameters, including the energy (in joules), the interval
between two sonications, the sonication duration, and the spot size, which are modifiable by
the operator. Thereafter, a low-energy sonication test will be performed to confirm the path
and correct direction of the ultrasound beam into the target area and to confirm the planned
energy dose and the effective dose deployed to the lesion.
The increase in tissue temperature is evaluated by using real-time MR thermometry of
phase-difference fast spoiled gradient-echo sequences (proton resonant frequency shift
method). The sequences are acquired to provide temperature-dependent images and real-time
mapping of the thermal dose on a preferred imaging plane. The proton resonant frequency
shift method starts simultaneously with each sonication. Similar to other treatments of bone
lesions that use MR-guided focused ultrasound, the temperature increase is determined on the
adjacent periskeletal tissue. In fact, proton resonant frequency sequences cannot
effectively measure the temperature on the bone surface because of the absence of moving
protons in the cortical zone. Thus, MR thermometry reveals a temperature increase, which
propagates by conductive processes from the bone to the immediately adjacent soft tissues
that respond linearly to an increase in bone temperature, thereby allowing an accurate
measure of heating. Portions of periosteum and adjacent tumor that are not fully ablated can
be re-treated if deemed necessary. The critical temperature threshold for ablation is set at
65°C in the soft tissues adjacent to the targeted bone structures. Postprocedural care
includes evaluation of possible skin burns, monitoring of vital signs for 2 hours after
treatment in the MR department, and administration of analgesic and/or antiemetic drugs if
requested. Treatment-related adverse events will be recorded as minor or major on the basis
of medical severity, additional treatment, and long-term consequences for patients.
Treatment will be performed on an outpatient basis in the patients who receive only local
and peripheral anesthesia; the patient who receives general anesthesia is usually
hospitalized for 24 hours after treatment.
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Endpoint Classification: Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment