Imaging of Bone Anatomical Variants Around the Foot and Ankle.

Different anatomical variants can be found in the ankle and foot, generally as occasional findings, although they can be the cause of diagnostic pitfalls and difficulties, especially in radiographic interpretation in trauma. These variants include accessory bones, supernumerary sesamoid bones, and accessory muscles. In most cases, they represent developmental anomalies found in incidental radiographic findings. This review discusses the main bony anatomical variants, including accessory and sesamoid ossicles, most commonly found in the foot and ankle that can be a cause of diagnostic challenges.

In-Office Needle Arthroscopy (IONA): may a traditionally orthopedic procedure enter the portfolio of interventional radiology?

Arthroscopy has historically proved to allow accurate evaluation of the intra-articular structures of the knee, thanks the possibility of direct vision and palpation, and reduced perioperative morbidity. Over the last decade, the diagnostic role of arthroscopy has been further increased by its quite effective use in the treatment of the lesions. The recent and important advances in the technological-instrumental field have produced a safe visualization system used to pose a diagnosis in an outpatient setting, employing reduced-diameter arthroscopes (In-Office Needle Arthroscopy, IONA). The accuracy of MRI is unanimously recognized, but it shows some weaknesses when compared to arthroscopy that is the gold standard technique in case of chondral lesions, meniscal tears, or atypical synovial pathologies. In this short report, we propose the interventional musculoskeletal radiologist as possible performer of IONA, in specific settings, providing the patient, suffering from acute and chronic knee joint diseases, with a complete diagnostic approach, when MRI is not definitive.

CT-guided cryoablation for management of bone metastases: a single center experience and review of the literature.

Thermal ablation techniques are procedures of growing interest for management of bone metastases. Among these, cryoablation is probably the most advanced. It allows treatment of large and irregular volumes of pathological tissue, real-time evaluation of the area of ablation and appears less painful than heat-based ablative techniques like radiofrequency and microwaves. Literature shows the effectiveness of cryoablation in the management of bone metastases in terms of pain palliation, but also its employment with curative intent is recommended. We reviewed the outcomes of cryoablation procedures performed in our radiology department over the last seven years, confirming the results in terms of pain palliation and local control of disease. We retrospectively evaluated results of 28 procedures of cryoablation, of which 17 treated with palliative and 11 with curative intent. In a 3-month follow-up study, we recorded an overall reduction of pain (evaluated using a VAS 0-10 scale) between pre- and post-treatment. The mean values dropped from 6.9 (SD: ± 1.3) to 3.5 (SD ± 2.6) (p < 0.0001). In the group of patients treated for local tumor control (follow-up: 22.4 months), we recorded a stability and/or reduction in volume of the lesion in 10 out 11 patients. No major complications were recorded.

Nail and enthesis assessment in patients with psoriatic disease by high frequency ultrasonography: findings from a single-centre cross-sectional study.

PURPOSE: To characterize nail and enthesis abnormalities using high frequency ultrasound (HFUS) in patients with psoriasis (PSO), psoriatic arthritis (PSA) with PSO, and PSA sine PSO. MATERIAL AND METHODS: Patients with PSO, PSA with PSO, and PSA sine PSO were evaluated and compared in a cross-sectional single centre study. Nail and enthesis abnormalities were evaluated by HFUS using high frequency probes (27 MHz). After a descriptive assessment, Brown University Nail Enthesis Scale (BUNES) and Madrid Sonography Enthesitis Index (MASEI) were used to assess nail and enthesis, respectively. RESULTS: Fifty-nine patients were enrolled (19 PSO, 22 PSA with PSO, 18 PSA sine PSO). In patients with PSO and in those with PSA and PSO, HFUS evaluation identified the following nail alterations characterised by thickened matrix, inhomogeneous echogenicity of the nail bed, and increased blood flow by power Doppler. In 38.9% patients with PSA sine PSO, a subclinical nail involvement was described. No difference was observed comparing BUNES values in three groups. In PSA patients with PSO and in those with PSA sine PSO, HFUS assessment of entheses mainly showed a hypoechoic aspect and thickness of the tendon, focal cortical erosion, and ossification. A subclinical enthesis involvement in 47.4% patients with PSO was observed. No difference was reported comparing MASEI values in three groups. CONCLUSION: Qualitative and quantitative abnormalities of nail and enthesis were demonstrated by HFUS in patients with PSO, PSA with PSO, and PSA sine PSO, suggesting a practical additional tool to be used in clinical settings. Furthermore, HFUS highlighted a subclinical nail involvement in patients with PSA sine PSO and enthesis subclinical alterations in patients with PSO.

Advanced MRI imaging of nerve roots in lumbar radiculopathy due to discoradicular conflict: DWI, DTI, and T2 mapping with clinical and neurophysiological correlations.

PURPOSE: To evaluate the lumbar nerve root alterations in patients with lumbar disc herniation sciatica using advanced multimodality MRI sequences and the correlations with clinical and neurophysiological findings. MATERIAL AND METHODS: We prospectively evaluated 45 patients suffering from unilateral lumbar radiculopathy due to disco radicular conflict. All patients underwent MRI examinations using a standard MRI protocol and additional advanced MRI sequences (DWI, DTI, and T2 mapping sequences). Relative metrics of ADC, FA, and T2 relaxation times were recorded by placing ROIs at the pre-, foraminal, and post-foraminal level, either at the affected side or the contralateral side, used as control. All patients were also submitted to electromyography testing, recording the spontaneous activity, voluntary activity, F wave amplitude, latency, and motor evoked potentials (MEP) amplitude and latency, both at the level of the tibialis anterior and the gastrocnemius. Clinical features (diseases duration, pain, sensitivity, strength, osteotendinous reflexes) were also recorded. RESULTS: Among clinical features, we found a positive correlation of pain intensity with ADC values of the lumbar nerve roots. The presence of spontaneous activity was correlated with lower ADC values of the affected lumbar nerve root. F wave and MEP latency were correlated with decreased FA values at the foraminal level and increased values at the post-foraminal level. The same neurophysiological measures correlated positively with pre-foraminal T2 mapping values and negatively with post-foraminal T2 mapping values. Increased T2 mapping values at the foraminal level were correlated with disease duration. CONCLUSIONS: Evaluation of lumbar nerve roots using advanced MRI sequences may provide useful clinical information in patients with lumbar radiculopathy, potentially indicating active inflammation/myelinic damage (DTI, T2 mapping) and axonal damage/chronicity (DWI).

A Bicentric Propensity Score Matched Study Comparing Percutaneous Computed Tomography-Guided Radiofrequency Ablation to Magnetic Resonance-Guided Focused Ultrasound for the Treatment of Osteoid Osteoma.

PURPOSE: To assess the safety and efficacy of computed tomography-guided radiofrequency (RF) ablation and magnetic resonance-guided focused ultrasound (MRgFUS) in the treatment of osteoid osteoma with a long-term follow-up study. MATERIALS AND METHODS: Database research was performed at 2 different centers with experience in musculoskeletal interventions. Both centers, one performing RF ablation and the other MRgFUS, identified 116 patients who underwent either RF ablation or MRgFUS procedures for the treatment of symptomatic osteoid osteoma and retrospectively evaluated data regarding pain scores using a visual analog scale (VAS). Complications were recorded according to the Cardiovascular and Interventional Radiological Society of Europe classification system. Propensity score matching for multiple variables was performed. Pain scores before and after therapy were compared. RESULTS: Of 116 patients treated, 61 and 55 underwent RF ablation and MRgFUS, respectively. Before treatment, the mean reported pain in the 2 groups were 9.1 ± 0.88 (RF ablation) and 8.7 ± 0.73 (MRgFUS) VAS units. After treatment, a statistically significant (P < .00001) overall reduction in pain symptomatology was recorded. No statistically significant difference was observed between the mean values of pain after treatment in both groups (P = .256). Over a mean of >2 years of follow-up, 4 cases of relapse (RF ablation, 1; MRgFUS, 3) and 1 complication (RF ablation) were observed. The analysis from propensity score matching that identified a matched cohort of 48 patients showed similar results. CONCLUSIONS: The 2 techniques for the treatment of osteoid osteoma resulted in profound and similar pain relief. The presence of thick cortical bone over the nidus can reduce the effectiveness of MRgFUS.

Musculoskeletal Interventional Radiology in the Pediatric Population: State of the Art.

Interventional radiology procedures have been proven to be as effective as traditional surgery but usually are characterized by lower morbidity rates. In this article, the most diffuse IR treatments for pediatric lesions are reviewed with the aim of describing main advantages and drawbacks. Ablation procedures (in particular RFA and MRgFUS) are widely used for the management of osteoid osteoma and osteoblastoma whereas intracystic injection of methylprednisolone acetate is performed for simple bone cysts. Sclerosing agents and where possible, selective arterial embolization are used for treatment of aneurysmal bone cysts and other vascular malformations. In the management of malignant muscoloskeletal tumors, the role interventional radiology is mainly represented by percutaneous biopsies, and by adiuvant selective embolizations in presence of hypervascular lesions to be submitted to surgery.

MR imaging of cerebral involvement of Rosai-Dorfman disease: a single-centre experience with review of the literature.

Rosai-Dorfman disease (RDD) is a rare, benign, non-Langerhans cells histiocytosis with massive lymphadenopathy of uncertain aetiology. It is commonly characterized by massive, painless, non-tender, bilateral cervical lymphadenopathy. Extra-nodal involvement is usually seen in 50% of patients, with the brain being affected in only 5% of cases, usually as dural-based lesions. Clinical presentation is heterogeneous and strongly dependent on the localization of the lesions. Although the histopathological findings are essential for the final diagnosis, brain magnetic resonance imaging (MRI) currently represents the first-line strategy for the detection of the lesions across the central nervous system (CNS); moreover, it may provide additional elements for the differential diagnosis versus other more common lesions. We performed a case-based literature review to highlight possible aetiologic and pathogenetic theories of this disease, along with imaging features of RDD, with a particular focus on the MRI characteristics of the CNS involvement (CNS-RDD). Finally, we provided a novel insight on the current therapeutic approaches, either surgical or medical.

Real-world clinical validity of cardiac magnetic resonance tissue tracking in primitive hypertrophic cardiomyopathy.

OBJECTIVE: Cardiac magnetic resonance (CMR) is an uncontested diagnostic tool for identifying and assessing hypertrophic cardiomyopathy (HCM) patients. Concerning the necessity to identify valid prognosticators for predicting the individual risk of clinical evolution, this study aimed to evaluate the clinical validity of CMR tissue tracking (TT) analysis in patients affected by primitive HCM in a real-world setting. METHODS: This historical prospective study included 33 patients. Diagnostic validity and clinical validation were assessed for strain values. CMR-TT diagnostic validity was studied comparing HCM patients with healthy control groups and phenotypic presentation of HCM. The impact of strain values and all phenotypic disease characteristics were assessed in a long-term follow-up study. RESULTS: The inter-reading agreement was good for all strain parameters. Significant differences were observed between the control group and HCM patients. Similarly, hypertrophic and LGE + segments showed lower deformability than healthy segments. The AUC of predictive model, including conventional risk factors for MACE occurrence and all strain values, reached 98% of diagnostic concordance (95% CI .94-1; standard error: .02; p value .0001), compared to conventional risk factors only (86%; 95% CI .73-99; standard error: .07; p value .002). CONCLUSION: In patients with primitive HCM, CMR-TT strain proves high clinical validity providing independent and non-negligible prognostic advantages over clinical features and traditional CMR markers.

T2-mapping MRI evaluation of patellofemoral cartilage in patients submitted to intra-articular platelet-rich plasma (PRP) injections.

This study evaluated the ability of T2 mapping magnetic resonance imaging at 3 T, in addition to morphological sequences, to assess efficacy of platelet-rich plasma (PRP) injections, characterizing qualitatively and quantitatively the grade of knee cartilage repair in patients with patellofemoral chondropathy. We retrospectively studied 34 patients (22 men, 12 women, mean age 41.8 years, including 22 men) with patellofemoral knee chondropathy, who underwent intra-articular PRP injections and completed a clinical and instrumental follow-up. As control group, we evaluated 34 patients who underwent non-operative therapy. All patients were submitted to clinical (using VAS and WOMAC index) and imaging studies with 3 T magnetic resonance with cartilage analysis with T2 mapping sequences for cartilage analysis before and after treatment. In the study group, mean pre-treatment T2 relaxation time values were 44.2 ± 2.5 ms, considering all articular cartilage compartments, with significant reduction at the follow-up (p < 0.001). At the index compartment, mean pre-treatment T2 relaxation times values were 47.8 ± 3.6 ms, with statistically significant reduction at the follow-up (p < 0.001). Evaluation of focal cartilage lesions reported pre-treatment mean T2 value of 70.1 ± 13.0 ms and post-treatment mean value of 59.9 ± 4.6 ms (p < 0.001). From a clinical point of view, the pre-treatment WOMAC and VAS scores were 18.3 ± 4.5 and 7 (IQR:6-7.2), respectively; the post-treatment values were 7.3 ± 3.2 and 2 (IQR: 1.7-3.0), respectively (p < 0.001). In the control group, despite clinical improvement, we didn't find significant T2 values change during the follow-up period. In conclusion, T2 mapping is a valuable indicator for chondropathy and treatment-related changes over time.

Lung involvement in macrophage activation syndrome and severe COVID-19: results from a cross-sectional study to assess clinical, laboratory and artificial intelligence-radiological differences.

OBJECTIVES: To evaluate the clinical pictures, laboratory tests and imaging of patients with lung involvement, either from severe COVID-19 or macrophage activation syndrome (MAS), in order to assess how similar these two diseases are. METHODS: The present work has been designed as a cross-sectional single-centre study to compare characteristics of patients with lung involvement either from MAS or severe COVID-19. Chest CT scans were assessed by using an artificial intelligence (AI)-based software. RESULTS: Ten patients with MAS and 47 patients with severe COVID-19 with lung involvement were assessed. Although all patients showed fever and dyspnoea, patients with MAS were characterised by thrombocytopaenia, whereas patients with severe COVID-19 were characterised by lymphopaenia and neutrophilia. Higher values of H-score characterised patients with MAS when compared with severe COVID-19. AI-reconstructed images of chest CT scan showed that apical, basal, peripheral and bilateral distributions of ground-glass opacities (GGOs), as well as apical consolidations, were more represented in severe COVID-19 than in MAS. C reactive protein directly correlated with GGOs extension in both diseases. Furthermore, lymphopaenia inversely correlated with GGOs extension in severe COVID-19. CONCLUSIONS: Our data could suggest laboratory and radiological differences between MAS and severe COVID-19, paving the way for further hypotheses to be investigated in future confirmatory studies.

Evaluation of intervertebral disc using T2 mapping sequences in patients undergoing O2-O3 chemiodiscolysis: an instrumental study with clinical correlation.

PURPOSE: To assess the MRI modifications of the intervertebral disc (IVD) treated by chemiodiscolysis using T2 mapping sequences. METHODS: Thirty sciatica patients (17 males, 13 females, mean age 47.52 years) were enrolled for percutaneous CT-guided O2-O3 chemiodiscolysis treatment. As a control group, we enrolled 30 patients who were treated by CT-guided periradicular injections. All patients were submitted to clinical (using VAS and Oswestry Disability index (ODI)) and imaging studies to evaluate the intervertebral disc area (IDA) and T2 mapping values of the IVD before and at 1-month follow-up. RESULTS: In the study group, pre-treatment IDA mean values were 20.47 ± 1.62 cm2, with significant reduction at the follow-up (P < 0.05). Mean pre-treatment T2 relaxation time values were 38.80 ± 4.51 ms, 44.05 ± 0.91 ms, and 45.45 ± 14.11 ms for anterior annulus fibrosus, nucleus pulposus (NP), and posterior annulus fibrosus, respectively, with significant increase at the level of the NP (P < 0.05) at the follow-up. Mean pre-treatment ODI and VAS scores were 21.5 ± 10.6 and 8.5 ± 0.57, with significant improvement at the post-treatment follow-up (P < 0.05). In the control group, despite clinical improvement, we did not find significant IVA reduction nor significant T2 values change after treatment. Correlation analysis of T2 mapping relaxation time values showed significant correlation of NP T2 mapping value with both the reduction of IDA (0.81, P < 0.001) and the improvement of VAS and ODI scores (0.86, P < 0.001) at 1 month. In the control group, we did not find any statistically significant correlation. CONCLUSIONS: T2 mapping may be a useful indicator to predict disc shrinkage and the clinical response to CT-guided O2-O3 injection.

Evolution of the imaging features of osteoid osteoma treated with RFA or MRgFUS during a long-term follow-up: a pictorial review with clinical correlations.

Interventional radiology is today considered the first-line treatment for osteoid osteoma both in the form of needle-guided technique of ablation (Radiofrequency) and of needleless technique (magnetic resonance-guided focused ultrasound surgery). The follow-up study of the procedures is mainly clinical, since the disappearance of pain is consistent with the success of the procedure. However, due to the minimally invasive and innovative nature of the approach, interpretation of the follow-up imaging could be ambiguous and misleading. Aim of our review was to define the main findings on the imaging that can best describe the regular evolution of these types of treatment. In particular, four findings were considered: (1) bone marrow oedema; (2) reactive phenomena (perilesional inflammatory reaction for extra-articular lesions or synovial reaction for intra-articular lesions); (3) bone remodelling (disappearance of the nidus and bone healing); (4) ring sign (considered as the granulation tissue around the nidus treated). These findings were evaluated using MRI and CT with a follow-up study that lasted up to 24 months.

An experience-based review of HIFU in functional interventional neuroradiology: transcranial MRgFUS thalamotomy for treatment of tremor.

Tremor is a common and very disabling symptom in patients with essential tremor and Parkinson's disease. In the recent years, transcranial ablation of thalamic nuclei using magnetic resonance guided high-intensity focused ultrasound has emerged as a minimally invasive treatment for tremor. The aim of this review is to discuss, in the light of our single-center experience, the technique, current applications, results, and future perspectives of this novel technology.

Cardiac magnetic resonance in arrhythmogenic cardiomyopathies.

Over the past few years, the approach to the 'arrhythmic patient' has profoundly changed. An early clinical presentation of arrhythmia is often accompanied by non-specific symptoms and followed by inconclusive electrocardiographic findings. In this scenario, cardiac magnetic resonance (CMR) has been established as a clinical tool of fundamental importance for a correct prognostic stratification of the arrhythmic patient. This technique provides a high-spatial-resolution tomographic evaluation of the heart, which allows studying accurately the ventricular volumes, identifying even segmental kinetic anomalies and properly detecting diffuse or focal tissue alterations through an excellent tissue characterization, while depicting different patterns of fibrosis distribution, myocardial edema or fatty substitution. Through these capabilities, CMR has a pivotal role for the adequate management of the arrhythmic patient, allowing the identification of those phenotypic manifestations characteristic of structural heart diseases. Therefore, CMR provides valuable information to reclassify the patient within the wide spectrum of potentially arrhythmogenic heart diseases, the definition of which remains the major determinants for both an adequate treatment and a poor prognosis. The purpose of this review study was to focus on the role of CMR in the evaluation of the main cardiac clinical entities associated with arrhythmogenic phenomena and to present a brief debate on the main pathophysiological mechanisms involved in the arrhythmogenesis process.

Coronary artery disease (CAD) extension-derived risk stratification for asymptomatic diabetic patients: usefulness of low-dose coronary computed tomography angiography (CCTA) in detecting high-risk profile patients.

BACKGROUND: As one of the most frequent risk factors for cardiovascular disease, type 2 diabetes mellitus (T2DM) is one of the largest causes of death. However, an acute cardiac presentation is not uncommon in diabetic patients, and the current investigative approach remains often inadequate. The aim of our study was to retrospectively stratify the risk of asymptomatic T2DM patients using low-dose 640-slice coronary computed tomography angiography (CCTA). MATERIALS AND METHODS: CCTA examinations of 62 patients (mean age, 65 years) with previous diagnosis of type 2 diabetes and without cardiac symptoms were analyzed. Image acquisition was performed using a 640-slice CT. Per-patient, per-vessel and per-plaque analyses were performed. Stratification risk was evaluated according to the ESC guidelines. The patients were followed up after 2.21 ± 0.56 years from CCTA examination. RESULTS: Coronary artery disease (CAD) was found in 58 patients (93.55%) presenting 290 plaques. Analysis of all samples showed severe-to-occlusive atherosclerosis in 24 patients (38.7% of cases). However, over the degree of stenosis, 23 patients were evaluated at high risk considering the extension of CAD. Good agreement was shown by the correlation of CAD extension/risk estimation and MACE incidence, according to a Kaplan-Meier survival analysis (p value = 0.001), with a 7.25-fold increased risk (HR 7.25 CI 2.13-24.7; p value = 0.002). CONCLUSION: Our study confirms the high capability of CCTA to properly stratify the CV risk of asymptomatic T2DM patients. Its use could be recommended if we consider how current investigative strategies to correctly assess these patients often seem inadequate.

Magnetic resonance-guided focused ultrasound surgery treatment of non-spinal intra-articular osteoblastoma: feasibility, safety, and outcomes in a single-center retrospective analysis.

Background: Interventional radiology, thanks to its low invasiveness and possibility to reduce the average time for the patients to come back to their normal activity, is becoming more and more promising and diffused in multiple fields. Employed without needles, MRgFUS is probably the less invasive techniques among the ones belonging to the field of interventional radiology. Purpose: To evaluate safety and effectiveness of MRgFUS in the treatment of a rare and benign, though disabling, bone lesion: intra-articular osteoblastoma. Materials and methods: A retrospective study was carried out on 6 patients (mean, 21 years) treated in the last 2 years with MRgFUS for symptomatic, histologically proved intra-articular osteoblastoma. The main inclusion criterion was the presence of a good acoustic window. The procedures consisted in MR-guided ablation, using high intensity ultrasound beams focused on the target lesion. Spinal anesthesia or peripheral nerve block was used. Clinical (based on pain and functional scales) and imaging follow-up studies were performed up to 1 year after treatment. Complications were recorded. Multiple linear regression and analysis of variance were used to assess correlations. Results: All the procedures were technically successful; no complications were observed. Painful symptomatology decreased of 88% at 6 months and 98% at 12 months (p < 0.0001), and was associated to functional improvement (p = 0.002). MRI and CT controls showed disappearance of all signs of disease and bone inflammation with a marked tendency to bone healing. Conclusion: This study shows the safety and effectiveness of MRgFUS in the treatment of intra-articular osteoblastoma with a good acoustic window.

Weight-bearing MR Imaging of Knee, Ankle and Foot.

Clinical management of several pathologies of the lower extremity joint relies on instrumental imaging evaluation. The assessment of joint changes with physiologic load requires studies using positions with the patient standing. Weight-bearing radiographs are the mainstay for the evaluation of several conditions such as knee osteoarthritis, pes planus, and hallux valgus, in particular to obtain measurements of articular parameters, especially for presurgical studies. In the last few years, dedicated magnetic resonance imaging and computed tomography scanners have also been developed to obtain high-resolution, multiplanar, and sectional images of the lower extremity joints during weight-bearing. These techniques provide detailed information on joint structure modifications under load in both physiologic and pathologic conditions to improve the diagnostic accuracy of weight-bearing studies.

Modic I changes size increase from supine to standing MRI correlates with increase in pain intensity in standing position: uncovering the "biomechanical stress" and "active discopathy" theories in low back pain.

PURPOSE: To evaluate the relationship between degenerative disc, endplate Modic changes (MC) type I, and pain during upright weight-bearing MRI scan of the lumbar spine in a cohort of patients with non-specific low back pain. MATERIALS AND METHODS: We evaluated 38 patients with non-specific low back pain and MRI evidence of Modic I vertebral changes. The patients were evaluated in a standard and upright weight-bearing position using a dedicated MR unit. The extent of endplate MC type I, intervertebral disc height at the involved level, and degree of degeneration in the same intervertebral disc were compared. Pain was assessed through the VAS questionnaire. RESULTS: In the upright position, the area of Modic I changes increased in 26 patients (68.4%, p ≤ 0.001) compared to the supine position. In the upright position, reduction in the disc height was found in 35 patients (92.1%). Correlation analysis showed moderate negative correlation (ρ = - 0.45) between intervertebral disc height and increase in the area of Modic I changes, and weak positive correlation (ρ = 0.12) between Pfirrmann grade and increase in the area of Modic I changes. At clinical evaluation, 30 patients (78.9%) reported worsening of low back pain standing in the upright position. Increase in VAS values on the upright position correlated significantly (ρ = 0.34) with an increase in the area of Modic I changes. CONCLUSIONS: Our results showed the modifications of Modic I changes under loading, with MRI evidence of increased MC area extent in the upright position and correlation between Modic changes extension increase and increase in pain in the standing position. Weight-bearing MRI scans represent a valuable complement to standard sequences since they provide the radiologist with additional diagnostic information about low back pain. These slides can be retrieved from Electronic Supplementary Material.

Magnetic-resonance-guided focused ultrasound treatment of non-spinal osteoid osteoma in children: multicentre experience.

BACKGROUND: Osteoid osteoma is a benign and painful musculoskeletal tumour that usually affects children. Current standard treatment is CT-guided radiofrequency ablation, a minimally invasive percutaneous procedure, with clinical success rates ranging between 85% and 98%. Though minimally invasive, however, this type of procedure is not free from complications. OBJECTIVE: To investigate the efficacy and safety of magnetic resonance (MR)-guided focused ultrasound (MRgFUS), a needleless procedure of thermal ablation employed in the treatment of non-spinal osteoid osteoma in paediatric patients. MATERIALS AND METHODS: We report the results of 33 procedures of ablation of osteoid osteoma performed with MRgFUS in three university hospitals. To ablate a lesion on the bone surface, MRgFUS employs the ultrasound energy transduced along the soft tissue. The follow-up studies lasted 24 months and were performed combining clinical and imaging data. RESULTS: Mean age of the children was 13.8 years. The clinical outcome showed a primary success of 97%. One case alone was submitted to repeat treatment because the first one failed (secondary success). No major or minor complications were recorded. During the investigation time, no relapse of symptomatology or delayed complications were observed. CONCLUSION: Although our study is preliminary and limited by a low number of patients, our data show that MRgFUS is effective. This suggests that it might be useful as the first-line treatment in paediatric patients with osteoid osteoma.