Issues in Imaging-Guided Tumor Ablation in Children Versus Adults

Percutaneous ablation of malignant and locally aggressive solid tumors in pediatric patients

Image-guided percutaneous ablation is an accepted treatment modality for common adult cancers. Unfortunately, its use in patients younger than 18 years is rare. This retrospective review presents our series of pediatric patients treated with ablation at our institution. From January 2002 to December 2021, a total of 14 patients (17 lesions) younger than 18 years were treated with percutaneous image-guided ablation. Estimated overall survival at 5 years was 58%; median survival of this group was not reached. Estimated local tumor progression-free survival at 5 years was 62%. One major complication was recorded.

Cone beam computed tomography (CBCT) guidance is helpful in reducing dose exposure to pediatric patients undergoing radiofrequency ablation of osteoid osteoma

Purpose

To assess efficacy and safety of cone beam computed tomography (CBCT) in the radiofrequency ablation (RFA) of osteoid osteoma (OO) in children and adolescents, and to compare technical success, clinical success, radiation dose and procedure duration time of CBCT guidance to conventional computed tomography (CT) guidance.

Materials and methods

Between 2015 and 2019, 53 consecutive percutaneous RFA were performed on pediatric patients with CBCT or conventional CT guidance, respectively, in 24 and 29 children and adolescents with 24-month follow-up. Dose area product (DAP) and dose length product (DLP) were recorded, respectively, for CBCT and conventional CT and converted to effective doses (ED).

Results

CBCT and conventional CT groups were similar in terms of patient age and weight, tumor size and tumor location. Technical success was achieved in all cases. Primary clinical success was 91.67% (22/24) for the CBCT group and 89.66% (26/29) for the conventional CT group. Mean DAP was 64.75Gycm2 (range 6.0–266.7). Mean DLP was 972.62mGycm (range 337–2344). ED was significantly lower in the CBCT group compared to the conventional CT group (0.34 mSv vs. 5.53 mSv, p = 0.0119). Procedure duration time was not significantly longer in the CBCT group (102.25 min vs. 92.34 min, p = 0.065). No major complication was registered. Minor complications were observed in 4 patients (2 in CBCT; 2 in conventional CT).

Conclusions

Compared to conventional CT guidance, CBCT guidance for percutaneous OO ablation shows similar technical and clinical success rates, with reduced radiation dose and equivalent procedure duration time. This technique helps sparing dose exposure to pediatric patients.

Microwave ablation of osteoid osteoma: initial experience and efficacy

BACKGROUND

Image-guided percutaneous microwave ablation has been used to treat adult osteoid osteomas but has not been thoroughly evaluated in the pediatric population.

OBJECTIVE

To evaluate the technical feasibility and clinical efficacy of microwave ablation to treat osteoid osteomas in pediatric patients.

MATERIALS AND METHODS

The electronic medical record and imaging archive were reviewed for 24 consecutive patients who had undergone microwave ablation of osteoid osteomas between January 1, 2015, and May 31, 2018, at a single tertiary care pediatric hospital. All patients were diagnosed by clinical and imaging criteria, and referred by a pediatric orthopedic surgeon after failing conservative management with pain medication. The average age of the patients was 13.3 years (range: 3-18 years), and the average size of the osteoid osteoma nidus was 8.8 mm (range: 5-22 mm). Technical success was defined as placement of the microwave antenna at the distal margin of the lesion nidus and achievement of the target ablation temperature. Clinical findings were assessed pre- and post-ablation and clinical success was defined as complete relief of pain without pain medication at 1-month follow-up. The number and severity of complications were also documented.

RESULTS

Clinical success was achieved in 100% of patients (24/24), with all reporting complete cessation of pain medication use 1 week after treatment and 0/10 pain at 1 month. There were 4 minor complications (17%) including access site numbness and a minor soft-tissue infection. There were no major complications.

CONCLUSION

Microwave ablation is a technically feasible and clinically effective treatment for pediatric osteoid osteomas.

Osteoid osteoma of the hand and foot in children successfully treated with radiofrequency neurotomy probes

Osteoid osteoma is a common benign tumor that is typically found in young adults and children, usually in the long bones of the lower extremity. Radiofrequency ablation (RFA) under computed tomography guidance is the standard of care for symptomatic osteoid osteomas. However, patients with osteoid osteoma of the hand or foot are often treated with open surgery because of the risk of injury to vascular and neural structures from RFA. This risk is more pronounced in pediatric patients because of the small lesion size and proximity of lesions to important neurovascular structures. Here, we present 2 pediatric patients, one with an osteoid osteoma in the hand and the other with an osteoid osteoma in the foot. In both patients, a 22-gauge, 2.5-mm active tip ablation probe was used. The smaller ablation volume achieved with this probe protected neighboring neurovascular structures while effectively ablating the osteoid osteoma nidus. Based on our success in these cases, we recommend the application of this method for cases in which neurovascular proximity to the osteoid osteoma lesion makes ablation challenging.

Riddles in the diagnosis and treatment of osteoid osteoma in child foot: A concisive study

BACKGROUND

Osteoid osteoma in child foot is very unusual. We investigate its polymorphism and difficulties in approach.

METHODS

We retrospectively studied 12 children (7 girls, 5 boys) treated in our department from February 1995 until February 2010. Mean age was 12 years (range 8-16 years) and average follow up time 5 years (3-8 years). The lesion affected mostly the talus (8 cases), calcaneus in 3 and once the fourth metatarsal. En bloc excision of lesion was the surgical method of choice.

RESULTS

Children's symptoms lasted average 2 years (14 months to even 4 years). Nocturnal pain and relief with NSAIDs occurred only in half cases. Atypical symptoms were hip referring pain, tenosynovitis of foot extensors and achilles' tendon atrophy. Complete cure and no recurrencies were noted.

CONCLUSIONS

Diversity of symptoms and delay in diagnosis still remain troublesome and the absolute modality of treatment for child foot osteoid osteomas urges further investigation. Minimally invasive surgical techniques have recently emerged but orthopaedic surgeons must not forget that open excision remains the most safe and documented method for pediatric foot osteoid osteomas.

CT-guided radiofrequency tumor ablation in children

BACKGROUND

Image-guided radiofrequency ablation is a well-accepted technique of interventional oncology in adults.

OBJECTIVE

To evaluate the efficacy and safety of CT-guided radiofrequency ablation as a minimally invasive treatment for metastatic neoplasms in children.

MATERIALS AND METHODS

A total of 15 radiofrequency ablation sessions were performed in 12 children and young adults (median age 9.5; range 5-18 years) with metastatic malignancies. Seven children and young adults had secondary hepatic lesions, three had pulmonary and two had bone lesions. Radiofrequency ablation was performed under conscious sedation.

RESULTS

The median lesion size was 1.7 cm (range 1.3-2.8 cm). The median time for ablation was 8 min (range 7-10 min). Radiofrequency procedures were technically successful in all tumors. Postablation imaging immediately after, and 1 month and 3 months after radiofrequency ablation showed total necrosis in all patients. At 6-month follow-up, three patients (all with lesion size >2 cm) had local recurrence and underwent a second radiofrequency ablation session. At 2-year follow-up no patient had recurrence of the treated tumor. Post-ablation syndrome occurred in four children. No major complication occurred.

CONCLUSION

CT-guided radiofrequency tumor ablation was safe and efficient for palliative treatment in our cohort of patients.