Dynamic contrast-enhanced MR imaging in osteoid osteoma: relationships with clinical and CT characteristics

A comparative study assessing the efficacy and safety of radiofrequency ablation versus surgical treatment for osteoid osteoma: retrospective analysis in a single institution

OBJECTIVE

We aim to evaluate the efficacy of CT-guided percutaneous radiofrequency ablation (RFA) and surgical treatment in osteoid osteoma (OO) treated at the Medical University of Graz.

MATERIALS AND METHODS

In a single-institution study, we analysed data from January 2005 to January 2021 of patients with histological/radiological diagnosis of OO. CT and MRI scans were reviewed for typical findings. Means (with SD) and medians (with IQR) were reported for normally and non-normally distributed variables. Differences between groups were assessed using chi-squared tests and t-tests.

RESULTS

One hundred nineteen patients (mean age: 21.6 ± 10.9 years; 63.9% males) with confirmed OO were retrospectively evaluated. 73 and 43 patients underwent RFA and surgery, respectively. In three cases, RFA combined with surgery was performed. Pre-intervention, 103 patients (88.8%) had undergone CT, and 101 had an MRI (87.1%). The nidus was confirmed in 82.5% of cases with CTs (85/103) and 63.4% with MRIs (64/101). The majority of nidi were located cortically (n = 96; 82.8%), most frequently in the femur (38 patients, 33.3%) with a median size of 8.0 mm (IQR: 5.0-12.0 mm). Median symptom duration before treatment was 6.0 (IQR: 4.0-13.0) months. The complication rate was 12.1% (14/116; 15.1% RFA vs. 7.0% surgery; p = 0.196). In total, 11.2% of patients had persistent symptoms after one week with clinical success rates of RFA and surgery, 86.3% and 90.7% (p = 0.647), respectively.

CONCLUSION

Compared to surgical treatment, CT-guided percutaneous RFA is a safe, minimally invasive, reliable, and efficient treatment option for OO.

CRITICAL RELEVANCE STATEMENT

This article critically assesses the diagnosis and treatment of osteoid osteoma, emphasising accurate imaging, and detailing a non-invasive option for effective management.

KEY POINTS

• This study analyses 116 cases of OO at one institution, focusing on symptom persistence, recurrence in short-term follow-up, and complications in two study groups. • Surgery showed higher, though not statistically significant, success despite comparable symptom persistence; CT displayed typical OO features more than MRI, regardless of the intramedullary, cortical and subperiosteal location as well as the site of the affected bone. • CT-guided RFA is an effective therapeutic alternative for OO compared to surgical intervention. In case of atypical OO appearance, RFA is not the first-line treatment.

In vivo depiction of cortical bone vascularization with ultra-high resolution-CT and deep learning algorithm reconstruction using osteoid osteoma as a model

PURPOSE

The purpose of this study was to evaluate the ability to depict in vivo bone vascularization using ultra-high-resolution (UHR) computed tomography (CT) with deep learning reconstruction (DLR) and hybrid iterative reconstruction algorithm, compared to simulated conventional CT, using osteoid osteoma as a model.

MATERIALS AND METHODS

Patients with histopathologically proven cortical osteoid osteoma who underwent UHR-CT between October 2019 and October 2022 were retrospectively included. Images were acquired with a 1024 × 1024 matrix and reconstructed with DLR and hybrid iterative reconstruction algorithm. To simulate conventional CT, images with a 512 × 512 matrix were also reconstructed. Two radiologists (R1, R2) independently evaluated the number of blood vessels entering the nidus and crossing the bone cortex, as well as vessel identification and image quality with a 5-point scale. Standard deviation (SD) of attenuation in the adjacent muscle and that of air were used as image noise and recorded.

RESULTS

Thirteen patients with 13 osteoid osteomas were included. There were 11 men and two women with a mean age of 21.8 ± 9.1 (SD) years. For both readers, UHR-CT with DLR depicted more nidus vessels (11.5 ± 4.3 [SD] (R1) and 11.9 ± 4.6 [SD] (R2)) and cortical vessels (4 ± 3.8 [SD] and 4.3 ± 4.1 [SD], respectively) than UHR-CT with hybrid iterative reconstruction (10.5 ± 4.3 [SD] and 10.4 ± 4.6 [SD], and 4.1 ± 3.8 [SD] and 4.3 ± 3.8 [SD], respectively) and simulated conventional CT (5.3 ± 2.2 [SD] and 6.4 ± 2.5 [SD], 2 ± 1.2 [SD] and 2.4 ± 1.6 [SD], respectively) (P < 0.05). UHR-CT with DLR provided less image noise than simulated conventional CT and UHR-CT with hybrid iterative reconstruction (P < 0.05). UHR-CT with DLR received the greatest score and simulated conventional CT the lowest score for vessel identification and image quality.

CONCLUSION

UHR-CT with DLR shows less noise than UHR-CT with hybrid iterative reconstruction and significantly improves cortical bone vascularization depiction compared to simulated conventional CT.

Osteoid osteoma of the wrist: Recent advances

Osteoid osteoma is a benign bone tumor usually arising in the diaphysis and metaphysis of the long bones, with male predominance (sex ratio, 2:1). Despite being the most common bone tumor in the wrist, it is still an atypical location for this lesion. The usual presentation is pain that is exacerbated at night and relieved by aspirin or non-steroidal anti-inflammatory drugs. This presentation is not always the case in the wrist, which leads to numerous differential diagnoses and often a delay in definitive diagnosis and treatment. Various imaging modalities can confirm the presence of the tumor and guide the surgical approach. Resection is the gold-standard, with radiofrequency gaining popularity in recent years.

Challenges in Diagnosing Juxt-Articular Osteoid Osteoma of the Talus: A Case Report

Osteoid osteomas of the talus are rarely seen. They can easily be misdiagnosed. In this case report, we present a 21-year-old man with an osteoid osteoma in the talar neck whose pain onset coincided with an ankle injury. The latter was deemed a misleading factor when making a diagnosis. Eventually, the patient was treated with surgical excision of the osteoid osteoma. The gap that resulted after the excision was filled with an autologous bone graft. A year after his operation, the patient returned to his daily activities and remained pain-free. A high index of suspicion and an appropriate imaging examination are mandated for the early diagnosis of such entities.

A Rare Presentation of Osteoid Osteoma in a 77-Year-Old Patient, Treated with Computer Tomography-Guided Percutaneous Radiofrequency Ablation

Osteoid osteoma (OO) is a benign bone forming tumor characterized by small size and a disproportionate amount of pain. They are most commonly seen between the ages of 5 and 30 years; however, they can be seen in the older patient albeit infrequently. The hands and feet are the least common site of OO among the extremity bones. We present a case of an OO in the hand of a 77-year-old man who underwent successful treatment with computed tomography–guided percutaneous radiofrequency ablation. We believe this is the oldest recorded patient in the medical literature with a histologically confirmed OO. The condition should therefore be considered in the differential diagnosis of a painful sclerotic bone lesion in this age group to avoid a delay in diagnosis and subsequent treatment.

Osteoid Osteoma: An Updated Review of Epidemiology, Pathogenesis, Clinical Presentation, Radiological Features, and Treatment Option

Osteoid osteoma, the third most common benign bone tumor, usually occurs in the cortex of long bones. It consists of a radiolucent nidus surrounded by reactive osteosclerosis. Generally, osteoid osteoma affects young males. Nocturnal pain that eases with salicylates or nonsteroidal anti-inflammatory drugs (NSAID) is the typical clinical presentation. Sometimes, it remains undiagnosed for a long time. Plain radiography and computed tomography are usually sufficient for the diagnosis of osteoid osteoma. Initial treatment includes salicylates and NSAID because the tumor often regresses spontaneously over 2-6 years. Surgical treatment is indicated in case of unresponsive pain to medical therapy, no tolerance of prolonged NSAID therapy due to side effects, and no willingness to activity limitations. Nowadays, minimally invasive techniques have replaced open surgery and are considered the gold standard of surgical treatment. Although cryoablation seems superior in terms of the nerve damage and immunotherapy effect, radiofrequency ablation is the preferred technique.

Detection of Bone Marrow Edema in Patients with Osteoid Osteoma Using Three-Material Decomposition with Dual-Layer Spectral CT

The aim of this study is to assess whether perifocal bone marrow edema (BME) in patients with osteoid osteoma (OO) can be accurately detected on dual-layer spectral CT (DLCT) with three-material decomposition. To that end, 18 patients with OO (25.33 ± 12.44 years; 7 females) were pairwise-matched with 18 patients (26.72 ± 9.65 years; 9 females) admitted for suspected pathologies other than OO in the same anatomic location but negative imaging findings. All patients were examined with DLCT and MRI. DLCT data was decomposed into hydroxyapatite and water- and fat-equivalent volume fraction maps. Two radiologists assessed DLCT-based volume fraction maps for the presence of perifocal BME, using a Likert scale (1 = no edema; 2 = likely no edema; 3 = likely edema; 4 = edema). Accuracy, sensitivity, and specificity for the detection of BME on DLCT were analyzed using MR findings as standard of reference. For the detection of BME in patients with OO, DLCT showed a sensitivity of 0.92, a specificity of 0.94, and an accuracy of 0.92 for both radiologists. Interreader agreement for the assessment of BME with DLCT was substantial (weighted κ = 0.78; 95% CI, 0.59, 0.94). DLCT with material-specific volume fraction maps allowed accurate detection of BME in patients with OO. This may spare patients additional examinations and facilitate the diagnosis of OO.

Osteoid osteoma: which is the best mininvasive treatment option?

Osteoid osteoma is the third most common benign bone tumor, with well-known clinical presentation and radiological features. Although surgical excision has been the only therapeutic option for a long time, to date it has been replaced by minimally invasive techniques, which proved satisfactory success rates and low complication occurrence. Therefore, the purpose of this literature review was to describe the main updates of these recent procedures in the field of interventional radiology, with particular attention paid to the results of the leading studies relating to the efficacy, complications, and recurrence rate. Nevertheless, this study aimed to analyze the peculiarities of each reported technique, with specific focus on the possible improvements and pitfalls. Results proved that all mininvasive procedures boast a high success rate with slight number of complications and a low recurrence rate. Radiofrequency ablation is still considered the gold standard procedure for percutaneous treatment of osteoid osteoma, and it has the possibility to combine treatment with a biopsy. Interstitial laser ablation's advantages are the simplicity of use and a lower cost of the electrodes, while cryoablation allows real-time visualization of the ablated zone, increasing the treatment safety. Magnetic resonance-guided focused ultrasound surgery is the most innovative non-invasive procedure, with the unquestionable advantage to be radiation free.

Soft tissue recurrence of an osteoid osteoma: an exceptional observation

We report the observation of the soft tissue recurrence of an osteoid osteoma (OO) in a 26-year-old man initially complaining of post-traumatic pain and swelling of the right ankle. A first arthroscopic resection was performed after the misdiagnosis of "bone irregularities" observed on computed tomography (CT) and magnetic resonance imaging (MRI). The diagnosis of OO was made by histological analysis of the resection material. The patient became asymptomatic for 5 years until the symptoms progressively recurred. Follow-up MRI and CT studies demonstrated a nodular bony focus within the periarticular soft tissues of the ankle. The lesion was removed, and histological analysis confirmed the diagnosis of a whole viable OO. This observation likely resulted from the displacement of the initial lesion during the initial arthroscopic procedure. This case report highlights the possibility of recurrence of OO in the soft tissues.

Magnetic resonance imaging evaluation of osteoid osteoma: utility of the dark rim sign

BACKGROUND

While typical patterns of osteoid osteoma have been described on CT, MRI findings can overlap among different diseases, and atypical patterns exist. In this study, we assessed the presence of a novel dark rim sign and its utility in the MRI diagnosis of osteoid osteoma.

OBJECTIVE

The purpose of this retrospective study was to assess the utility of the dark rim sign seen on MRI in children with osteoid osteoma.

MATERIALS AND METHODS

MRI studies from 36 pediatric patients with osteoid osteoma and a control group of patients with either osteomyelitis or stress fracture were analyzed and then compared for the presence of the dark rim sign. Patients from the osteoid osteoma group were further divided based on nidus location and evaluated for the presence of the dark rim sign.

RESULTS

The relationship between the dark rim sign and osteoid osteoma was statistically significant (P<0.001). A dark rim sign was identified in 25 of the 36 patients with osteoid osteoma. None of the control patients had a dark rim sign. The dark rim sign had 69.4% sensitivity, 100% specificity, 100% positive predictive value and 72.5% negative predictive value for detecting osteoid osteoma. The relationship between dark rim sign and nidus location was statistically significant (P<0.001) such that endosteal and medullary osteoid osteomas were more likely to have a dark rim sign than intracortical osteoid osteomas.

CONCLUSION

When the nidus of an osteoid osteoma is in an endosteal or medullary location, the dark rim sign may aid in the diagnosis.

MR Imaging of Osteoid Osteoma: Pearls and Pitfalls

Osteoid osteoma (OO) is a benign bone neoplasm consisting of a central prostaglandin-secreting nidus surrounded by a zone of reactive sclerosis. The diagnosis is suspected in children and young adults with longstanding nighttime pain that is relieved by salicylates or nonsteroidal anti-inflammatory drugs. Early studies suggested that computed tomography had a higher sensitivity and specificity in the diagnosis of OO compared to magnetic resonance imaging (MRI). More recent literature suggests MRI done with dynamic postcontrast imaging to be equal to or slightly better at detecting the nidus of OOs, particularly the ones in atypical locations. Being able to evaluate for OO utilizing MRI is important given that the majority of these lesions occur in younger patients, in whom there is greater concern to limit ionizing radiation. Furthermore, patients with atypical OOs often receive an MRI if radiographs are not suggestive of the diagnosis. Therefore, it is important for radiologists to be aware of the imaging features that can help make the diagnosis on MRI.

Osteoid osteoma of the hip: imaging features

Osteoid osteoma (OO), a small bone tumor relatively common in young subjects, frequently involves the hip. In addition to typical findings, we emphasize unsuspected clinical and imaging features including painless OO causing limping gait, non-visibility of totally mineralized nidus, absence of hyperostosis or adjacent edema, and recurrence at distance from the initial location. We also discuss the option of medical treatment for some cases of deep hip locations.

Treatment-related alterations of imaging findings in osteoid osteoma after percutaneous radiofrequency ablation

OBJECTIVES

We aimed to report the long-term outcomes of osteoid osteoma patients and to determine CT and dynamic contrast-enhanced MR imaging characteristics of radiofrequency ablation (RFA) treatment related changes of osteoid osteoma between follow-up periods.

MATERIALS AND METHODS

Thirty patients (seven female, 23 male) who underwent CT-guided RFA of osteoid osteoma were included. Follow-up imaging examinations were divided into two subgroups; first (1-3 months) and second (> 6 months) periods. Nidus size, calcification, cortical thickening, maximum signal intensity (SImax), time of SImax (Tmax), slope of signal intensity-time (SIT) curves were noted. CT and dynamic MR imaging findings were compared between follow-up periods.

RESULTS

Clinical success rate was 100%. The mean of OO nidi size was 5.85 ± 1.98 mm before treatment. There was a significant difference for OO nidi sizes between pretreatment and second follow-up period examinations (p = 0.002). SImax and slope of SIT curves of all patients (100%) showed decrease on follow-up MRIs. There was a significant decrease for SImax values between pretreatment and second follow-up period. There was a significant decrease for slope of SIT curves between pretreatment and both follow-up periods.

CONCLUSIONS

RFA is an effective and safe treatment choice for osteoid osteomas. On follow-up imaging, slope of SIT curve and Tmax have the most important positive predictive value for long-term outcomes and single dynamic contrast-enhanced MRI within first 3 months after treatment may be sufficient for symptom-free patients.

Pitfalls in Pediatric Trauma and Microtrauma

Fractures are common in children, although accurate diagnosis is confounded by mimics of fractures some of which are unique to the pediatric population. Such fracture mimics include developmental variations of the growth plates, normal anatomic structures that simulate fracture lines, and/or metabolic disorders that alter the pattern of ossification. Although subtle clues on plain radiographs may help to discriminate between a true fracture or injury and a fracture mimic, MR imaging may be helpful to eliminate uncertainty or expedite diagnosis.