Usefulness of -FDG PET/CT in Locoregional Recurrence of Differentiated Thyroid Cancer: Comparison PET/CT to PET and Neck Ultrasonography for Biopsy-proven Lesions

Purpose: The aim of this study was to investigate the usefulness of $^{18}F$-FDG PET/CT with neck ultrasonography (neck US) in patients with recurrent, papillary thyroid cancer. Material and methods: This retrospective study (December 2006 to April 2008) enrolled sixty-one patients (ninety-one lesions) who underwent high-dose $^{131}I$-ablation therapy after total thyroidectomy, and evaluated recurred papillary thyroid cancer. All lesions were confirmed by histopathology and compared histopathologic findings to PET, PET/CT, and neck US findings. Results: In sixty-one patients (57 women, 4 men; age range, 24-81 years, mean 49 years; 61 papillary carcinomas), the sensitivity, specificity, accuracy of $^{18}F$-FDG PET/CT was 87.2%, 64.0%, 78.1% on a patient basis and 92.3%, 66.7%, 80.9% on a lesion basis, respectively. The sensitivity, specificity, accuracy of $^{18}F$-FDG PET was 71.8% (p=0.03), 59.0% (p=1.00), 67.2% (p=0.03) on a patient basis and 78.8% (p<0.01), 64.1% (p=1.00), 72.5% (p=0.02) on a lesion basis, respectively. The sensitivity, specificity, accuracy of neck US was 71.1% (p=0.07), 52.2% (p=0.75), 63.9% (p=0.05) on a patient basis and 71.2% (p<0.01), 61.5% (p=1.00), 67.0% (p=0.06) on a lesion basis, respectively. Combined $^{18}F$-FDG PET/CT with neck US improved the sensitivity, specificity, accuracy to 94.7% (p=0.50), 82.6% (p=0.13), 90.2% (p=0.03) on a patient basis and 96.2% (p=0.50), 89.7% (p<0.01), 93.4% (p<0.01) on a lesion basis, respectively. Conclusion: $^{18}F$-FDG PET/CT demonstrated significantly higher sensitivity than neck US for the detection of recurred papillary thyroid cancer lesions. Furthermore, combined $^{18}F$-FDG PET/CT with neck US showed more improved sensitivity, specificity, accuracy for diagnosis of recurrent papillary thyroid cancer.

갑상선유두암 재발 진단에서 -FDG PET/CT와 경부초음파검사 병용의 유용성: PET, 경부초음파검사 그리고 혈청 티로글로불린 (thyroglobulin)의 비교

목적: 이 연구의 목적은 갑상선유두암 환자를 대상으로 재발의 진단에서 $^{18}F$-FDG PET/CT와 경부초음파검사를 함께 시행하는 것에 대한 유용성을 평가하고자 한다. 대상 및 방법: 2006년 12월부터 2008년 4월까지 갑상선유두암으로 갑상선 전절제술 및 고용량의 방사성옥소 치료를 시행 받은 환자 중에서 재발이 의심되어 $^{18}F$-FDG PET/CT를 시행한 51명(91건)을 대상으로 후향적으로 연구를 진행하였다. 의심되는 병소는 조직검사를 시행하였고, 조직 검사 결과와 PET 검사결과. PET/CT 검사결과, 경부초음파검사 결과를 비교하였다. 결과: $^{18}F$-FDG PET/CT (여자 57명, 남자 4명; 연령 범위, 24-81세, 평균 49세; 유두암 61개)의 민감도, 특이도, 정확도는 각각 환자 기준으로 87.2%, 59.0%, 77.0%였고, 병소 기준으로 92.3%, 64.1%, 80.2% 였다. $^{18}F$-FDG PET의 민감도, 특이도, 정확도는 각각 환자 기준으로 71.8% (P=0.03), 59.0% (p=1.00), 67.2% (p=0.03)였고, 병소 기준으로 78.8% (p=0.01), 64.1% (p=1.00), 72.5% (p=0.02)였다. 경부초음파검사의 경우 민감도, 특이도, 정확도는 각각 환자 기준으로 71.1% (p=0.07), 52.2% (p=0.75), 63.9% (p=0.08)였고, 병소 기준으로 71.2% (P<0.01), 61.5% (P=1.00), 67.0% (P=0.06)였다. $^{18}F$-FDG PET/CT 와 경부초음파검사를 함께 판독한 경우 민감도, 특이도, 정확도는 각각 환자 기준으로 94.7% (p=0.50), 82.6% (p=0.13), 90.2% (p=0.03)였고, 병소 기준으로 96.2% (p=0.50), 89.7% (p<0.01), 93.4% (p<0.01)였다. 결론: $^{18}F$-FDG PET/CT는 갑상선유두암의 재발 진단에서)$^{18}F$-FDG PET와 경부초음파검사와 비교하여 높은 민감도, 특이도, 정확도를 보였다. 게다가 $^{18}F$-FDG PET와 경부 초음파를 함께 시행한 경우 갑상선유두암의 재발 진단에 있어서 더욱 향상된 민감도, 특이도, 정확도를 보였다.