Intraarticular Osteoid Osteoma: MRI Characteristics and Clinical Presentation Before and After Radiofrequency Ablation Compared to Extraarticular Osteoid Osteoma

Abstract

<jats:p> Purpose To determine MRI characteristics and the clinical presentation of intraarticular osteoid osteomas (OO) before and after treatment with CT-guided radiofrequency ablation (RFA) compared with extraarticular osteoid osteomas.</jats:p><jats:p> Materials and Methods In a retrospective study, n = 21 patients with an intraarticular OO were matched with a control group of n = 21 patients with an extraarticular OO at a comparable anatomical position. All patients underwent CT-guided RFA and preinterventional MRI. In n = 31 cases, follow-up MR imaging was available. MR images were analyzed for morphologic features: effusion and synovitis, bone marrow edema (BME), soft tissue edema, periosteal reaction as well as T1 / T2 signal and contrast enhancement of the nidus. Recorded clinical parameters included the initial diagnosis, the course of pain symptoms after RFA and the incidence of complications.</jats:p><jats:p> Results The nidus was detectable in all patients on MRI. BME had the highest sensitivity in both intra- and extraarticular OO (100 %). Effusion and synovitis were only observed in the intraarticular OO group (n = 21) with a perfect sensitivity and specificity (100 %) and a high negative predictive value (85 %). Soft tissue edema was significantly more present in patients with intraarticular OO (p = 0.0143). No significant differences were present regarding periosteal reaction, T1/T2 signal and contrast enhancement of the nidus (p &gt; 0.05). BME, contrast enhancement, soft tissue edema, periosteal reaction, effusion and synovitis, if preexisting, always decreased after RFA. In 66.7 % of patients with intraarticular OO, a false initial diagnosis was made (extraarticular: 19 %). All patients were free of pain after intervention. Complications following the RFA procedure did not occur.</jats:p><jats:p> Conclusion MRI demonstrates the nidus and thus the OO in all cases regardless of the location. The characteristic MRI morphology of an intraarticular OO includes synovitis and joint effusion, which are always present and differentiate with perfect sensitivity/specificity from an extraarticular OO. In both intra- and extraarticular OOs pathologic MRI changes at least decreased or completely normalized and the clinical results after RFA were excellent.</jats:p><jats:p> Key Points: </jats:p><jats:p> Citation Format </jats:p>

Intra-articular hip joint osteoid osteoma: Challenging diagnosis and percutaneous radiofrequency ablation treatment

“…Other possibly encountered radiological features of IAOO include chondrolysis, periarticular osteopenia, joint effusion and synovial thickening [6 , 12] . Unlike Germann et al's retrospective study on 21 IAOO cases where they observed that joint effusion and synovitis were present in all patients [21] , our patient did not have synovitis and only had trace joint effusion. Moreover, because of the lesion's small size, it radiologically mimicked an osteochondral defect, although the overlying cartilage was intact.…”

Osteoid osteoma: which is the best mininvasive treatment option?

“…Similar to RFA, ILA and MWA can also be considered as viable percutaneous treatment alternatives with good results. ILA versus RFA is less expensive [ 52 , 57 , 58 , 62 ] and presents minor technical concern [ 52 , 57 , 58 ].…”

“…Joint effusion and synovitis are two signs typically associated with intra-articular OO and their rapid regression in few weeks after RFA is easily verifiable through MRI as well [ 58 ].…”

“…Contrast-enhanced MRI plays a pivotal role, since nidus enhancement not only strongly supports the diagnosis before the procedure, aiding differential diagnosis, but is also a fundamental instrument in the early identification of possible post-treatment disease relapse [ 58 – 60 ].…”

Interventional Radiology’s Osteoid Osteoma Management: Percutaneous Thermal Ablation

“…Contrast-enhanced MRI is important in the diagnosis of OO, since enhancement of the nidus is a pathognomonic sign. MRI is also a crucial tool in the early identification of possible post-treatment disease relapses [29,30]. Some studies support this last suggestion, for example Mahnken et al studied 20 patients and demonstrated that contrast enhancement on T1-weighted MRI imaging seems to be predictive of treatment failure after radiofrequency ablation for treatment of OO [30].…”