Background The sacroiliac joint is one of the sources of chronic lower back pain. Intra-articular injections of anesthetic drugs and/or steroids are currently used in these cases for diagnostic and therapeutic purposes. However, given the anatomic and functional complexity of the joint, imaging guidance is mandatory during such procedures. In this context, the technique of fusing images obtained with two different modalities can often overcome the limitations and enhance the advantages of single-modality guidance. Aim The aim of this study was to evaluate the technique of ultrasound (US)-magnetic resonance (MR) image fusion to guide intra-articular injections of drugs into the sacroiliac joint. Materials and methods We evaluated seven sacroiliac joints in six patients with sacroiliac pain syndrome (four females, two males; mean age 59 years; range 46-76 years). Five were candidates for radiofrequency thermolysis, and a therapeutic nerve block was performed in the sixth. Using the volume navigation system, we fused three-dimensional MR images with simultaneously acquired real-time ultrasound images and used them to guide the intra-articular injections. Results In all patients, spatial accuracy was considered excellent, with definition of registration errors of less than 3 mm. The diagnostic blocks produced positive results in all patients with 80 % reductions in pain (measured with a Numerical Rating Scale, NRS) relative to baseline. The patient who underwent the therapeutic nerve block experienced complete resolution of symptoms that has been maintained over time. There were no complications. Conclusions US-MR imaging fusion guidance of sacroiliac joint injections is feasible and effective, in accordance with the data in the literature. The use of the MR for threedimensional imaging eliminates the risk of radiation exposure.
Keywords Image fusion technique Á Sacroiliac joints Á Ultrasound
RiassuntoBackground il dolore sacro-iliaco è una delle cause di dolore lombare cronico. L'infiltrazione intra-articolare di farmaci anestetici e/o steroidi, costituisce uno strumento correntemente utilizzato a scopo diagnostico e terapeutico. Tuttavia, la complessità anatomo-funzionale dell'articolazione impone l'utilizzo della guida imaging all'infiltrazione. La fusion imaging si pone in questo contesto come strumento che risolve i limiti delle singole metodiche e ne amplifica i vantaggi. Scopo l'obiettivo del nostro lavoro è valutare la fusion imaging come strumento per la guida della somministrazione farmacologica intra-articolare dell'articolazione sacro-iliaca, utilizzando la co-registrazione di immagini ecografiche e di risonanza magnetica. Materiali e Metodi sono state valutate 7 articolazioni sacro-iliache in 6 pazienti (4 femmine, 2 maschi; età media 59 anni; range 46-76 anni) con sindrome dolorosa sacroiliaca; 5 candidati al trattamento di termolesione, 1 sottoposto a blocco terapeutico. L'iniezione intra-articolare è stata condotta con la guida della fusion imaging ottenuta con i dati tridimensionali RM visua...