CASE 12262 Published on 31.03.2015

18F-FDG PET-CT to evaluate immediate response after radiofrequency ablation of lung tumours

Section

Interventional radiology

Case Type

Clinical Cases

Authors

Eyheremendy E, Mendez P, Montano Y, Demichele E, Casalini E, Sierre S.

Hospital Alemán
Interventional Radiology
Av. Pueyrredon 1640
Buenos Aires, Argentina
Mail: jolemontd@hotmail.com

Patient

35 years, female

Categories

Area of Interest Lung ; Imaging Technique PET-CT, CT, Percutaneous

Procedure Diagnostic procedure ; Special Focus Metastases ;

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Clinical History

A 35-year-old female patient with a history of synovial sarcoma resection of the lower left limb. Follow-up CT showed a lung nodule. During follow-up, an increase in size of the lung lesion was observed. Radiofrequency ablation of the pulmonary lesion was performed under CT guidance.

Imaging Findings

Follow-up chest CT demonstrated a 6.6 mm nodule in the anterior segment of the right upper lobule, with progressive growth in time, reaching 27 mm. (Fig. 1)
PET-CT demonstrated metabolic activity of the pulmonary nodule. (Fig. 2)
CT-guided pulmonary RFA was performed. (Fig. 3)
A total 8 mCi of FDG was administered immediately after the procedure. Sixty minutes later PET-CT was performed and demonstrated no metabolic activity of the treated lung nodule. (Fig. 4) Follow-up CT at 3 and 6 months showed cavitary sequelae and no evidence of the lesion. (Fig. 5)

Discussion

Lung radiofrequency ablation (RFA) is a minimally invasive technique used to treat pulmonary malignancies as an alternative to surgery and radiotherapy, with minimal procedure-related complications. [1]
RFA is indicated in patients with early stage non-small cell lung cancer (NSCLC) who are not eligible for surgery, in patients with end stage NSCLC, cases with tumour recurrence and in metastatic lung disease. In a curative intent, RFA success depends on anatomical criteria, such as nodule size and location. Lesions larger than 5 cm should be excluded from RFA, whereas lesions from 3 to 5 cm should be considered with caution because of the high incidence of recurrence. [2]

The most common CT findings during lung RFA are: a cone-shaped sectorial hyperaemia or hyperaemia rim, characterized by ground-glass opacity, which may circumferentially or partially envelop the target lesion and intralesional bubbles. [3]
These findings might be related to reported appreciable rates of recurrence, varying from 7% to 55% between 1 and 3 years of follow-up. [4] Considering this, PET-CT realization immediately after ablation could help to decrease the recurrence rate.
PET/CT imaging allows immediate analysis of the lesion’s metabolic activity and is accurate for staging, surveillance and therapeutic response evaluation. [5, 6] It has become a useful tool for assessing treatment response during and after RFA; and a reliable predictor of local recurrence. [7] During ablation the lesion presents a peripheral ring-shaped area of hypermetabolic activity surrounding the ablated tumour. [8]

In this reported case, performing PET/CT immediately after the procedure was a useful technical tool, assessing ablation and allowing the possibility to continue the procedure if hyperactivity remained, aiming to decrease the chance of tumour recurrence. Further larger studies are needed in order to consider this modified algorithm, as a step forward for improving ablation procedures success rates. [9]

Differential Diagnosis List

Lung metastasis

Lung tumour

Final Diagnosis

Lung metastasis

References

[1] Radvany MG, Allan PF, Frey WC, Banks KP, Malave D. (2005) Pulmonary Radiofrequency Ablation Complicated by Subcutaneous Emphysema and Pneumomediastinum Treated with Fibrin Sealant Injection. American journal of roentgenology 185:894-8. (PMID: 16177407)

[2] Bargellini I, Bozzi E, Cioni R, Parentini B, Bartolozzi C. (2011) Radiofrequency ablation of lung tumours. Insights Imaging 2(5): 567–576. (PMID: 22347976)

[3] Abtin FG, Eradat J, Gutierrez AJ, Lee C, Fishbein MC, Suh RD. (2012) Rodiofrecuency Ablation of Lung Tumors: Imaging Features of the Post-ablation Zone. Radiographics 32(4):947-69. (PMID: 22786987)

[4] Lee JM, Jin GY, Goldberg SN, Lee YC, Chung GH, Han YM, Lee SY, Kim CS. (2004) Percutaneous radiofrequency ablation for inoperable non-small cell lung cancer and metastases: preliminary report. Radiology 230(1):125-34 (PMID: 14645875)

[5] Goldberg SN, Gazelle GS, Compton CC, McLoud TC. (1995) Radiofrequency tissue ablation in the rabbit lung: efficacy and complications. Academic Radiology 2(9):776-84 (PMID: 9419639)

[6] Kostakoglu L, Goldsmith SJ. (2003) 18F-FDG PET evaluation of the response to therapy for lymphoma and for breast, lung, and colorectal carcinoma. Journal of Nuclear Medicine 44(2):224-39 (PMID: 12571214)

[7] Singnurkar A, Solomon SB, Gönen M, Larson SM, Schöder H. (2010) 18F-FDG PET/CT for the prediction and detection of local recurrence after radiofrequency ablation of malignant lung lesions. Journal of Nuclear Medicine 52(1):106. (PMID: 21078787)

[8] Venkatesan AM, Kadoury S, Abi-Jaoudeh N, Levy EB, Maass-Moreno R, Krücker J, Dalal S, Xu S, Glossop N, Wood BJ. (2011) Real-time FDG PET guidance during biopsies and radiofrequency ablation using multimodality fusion with electromagnetic navigation. Radiology 260(3):848-56 (PMID: 21734159)

[9] Ryan ER1, Sofocleous CT, Schöder H, Carrasquillo JA, Nehmeh S, Larson SM, Thornton R, Siegelbaum RH, Erinjeri JP, Solomon SB. (2013) Split-dose technique for FDG PET/CT-guided percutaneous ablation: a method to facilitate lesion targeting and to provide immediate assessment of treatment effectiveness. Radiology 268(1):288-95 (PMID: 23564714)

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