Abstract
Purpose: As PET-MRI which has excellent soft tissue contrast is developed as integration system, many researches about clinical application are being conducted by comparing with existing display equipments. Because PET-MRI is actively used for head and neck cancer diagnosis in our hospital, lymph node metastasis before the patient's surgery was diagnosed and clinical usefulness of head and neck cancer PET-MRI scan was evaluated using pathological opinions and idiopathy surrounding tissue metastasis evaluation method. Materials and Methods: Targeting 100 head and neck cancer patients in SNUH from January to August in 2013. $^{18}F-FDG$ (5.18 MBq/kg) was intravenous injected and after 60 min of rest, torso (body TIM coil, Vibe-Dixon) and dedication (head-neck TIM coil, UTE, Dotarem injection) scans were conducted using $Bio-graph^{TM}$ mMR 3T (SIEMENS, Munich). Data were reorganized using iterative reconstruction and lymph node metastasis was read with Syngo.Via workstation. Subsequently, pathological observations and diagnosis before-and-after surgery were examined with integrated medical information system (EMR, best-care) in SNUH. Patient's diagnostic information was entered in each category of $2{\times}2$ decision matrix and was classified into true positive (TP), true negative (TN), false positive (FP) and false negative (FN). Based on these classified test results, sensitivity, specificity, accuracy, false negative and false positive rate were calculated. Results: In PET-MRI scan results of head and neck cancer patients, positive and negative cases of lymph node metastasis were 49 and 51 cases respectively and positive and negative lymph node metastasis through before-and-after surgery pathological results were 46 and 54 cases respectively. In both tests, TP which received positive lymph node metastasis were analyzed as 34 cases, FP which received positive lymph node metastasis in PET-MRI scan but received negative lymph node metastasis in pathological test were 4 cases, FN which received negative lymph node metastasis but received positive lymph node metastasis in pathological test was 1 case, and TN which received negative lymph node metastasis in both two tests were 50 cases. Based on these data, sensitivity in PET-MRI scan of head and neck cancer patient was identified to be 97.8%, specificity was 92.5%, accuracy was 95%, FN rate was 2.1% and FP rate was 7.00% respectively. Conclusion: PET-MRI which can apply the acquired functional information using high tissue contrast and various sequences was considered to be useful in determining the weapons before-and-after surgery in head and neck cancer diagnosis or in the evaluation of recurrence and remote detection of metastasis and uncertain idiopathy cervical lymph node metastasis. Additionally, clinical usefulness of PET-MRI through pathological test and integrated diagnosis and follow-up scan was considered to be sufficient as a standard diagnosis scan of head and neck cancer, and additional researches about the development of optimum MR sequence and clinical application are required.
수술 전 림프절 전이 여부를 진단하고 병리학적 소견 및 원발 주위조직 전이 평가법을 이용하여 두경부암 PET-MRI 검사의 임상적 유용성을 평가하였다. 두경부암 환자 100명을 대상으로 $^{18}F-FDG$ (5.18 MBq/kg)를 정맥주사하고 60분 안정을 취한 후, BiographTM mMR 3T를 사용하여 torso(body tim coil, Vibe-Dixon)와 dedication (head/neck tim coil, UTE, Dotarem injection) 검사를 시행하였다. 반복계산법을 적용하여 데이터를 재구성한 후 workstation으로 림프절 전이 여부를 판독하고, 본원 종합의료정보시스템으로 수술 전/후 병리학적 검사 소견을 조사하였다. 환자의 진단 정보를 $2{\times}2$ 판정행렬의 각 항목에 기입하여 진양성, 진음성, 위양성, 위음성으로 구분하고 이렇게 구분된 검사결과를 토대로 예민도, 특이도, 정확도, 위음성률, 위양성률을 산출하였다. 두경부암 환자의 PET-MRI 검사 결과에서 림프절 전이 양성 및 음성 판정을 받은 경우는 각 49건, 51건이었으며 수술 전-후 병리학적 결과를 통해 림프절 전이 양성 및 음성 판정을 받은 경우는 각 46건, 54건으로 나타났다. 이 중 두 검사 모두 림프절 전이 양성 판정을 받은 진양성은 45건, PET-MRI 검사에서는 림프절 전이 양성이지만 병리학적 검사에서 림프절 전이 음성 판정을 받은 위양성은 4건, PET-MRI 검사에서 림프절 전이 음성이지만 병리학적 검사에서 양성 판정을 받은 위음성은 1건, 두 검사 모두 림프절 전이 음성 판정을 받은 진음성은 50건으로 분석되었다. 따라서 두경부암 환자의 PET-MRI 검사의 예민도는 97.8%, 특이도는 92.5%, 정확도는 95%, 위음성률은 2.1%, 위양성률은 7.0%로 나타났다. 따라서 PET-MRI는 두경부암의 진단에 있어 수술 전 병기 결정이나 치료 후 재발 및 원격전이의 발견, 불분명한 원발 경부 림프절 전이 등의 평가에 유용할 것으로 판단된다.
(Department of Nuclear Medicine, Seoul National University Hospital)
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