Abstract：
BACKGROUND: We sought to determine the utility of PET-MRI in diagnosing Idiopathic Inflammatory Myositis (IIM), and look for association between FDG uptake and clinical, pathological and laboratory parameters.
METHODS: A retrospective, observational study was conducted on IIM patients having positive serum autoantibodies and who underwent PET-MRI (3-Tesla SIEMENS Biograph MR scanner) between 2017 and 2021. Thirty patients who underwent PET-MRI to detect systemic metastasis without muscle involvement formed the control group.
RESULTS: In the IIM cohort, female: male sex ratio was 1.73, mean age at diagnosis was 40.33 years, and the mean duration of illness was 7 months. 33.33% of patients had severe limb weakness. Mi2B (43.33%), Mi2A (43.33%), PL-7(10%), PL-12(6.67%), SRP (16.67%), Tif1gamma (3.33%), NxP2 (3.33%), Ro-52(40%), PM-Scl, U1-RNP, ANA (26.67%) were the serum autoantibodies identified. Using SUV max Ratio to quantify FDG uptake, PET-MRI showed a sensitivity of 100% with 93.3% specificity in diagnosing IIM.FDG uptake was maximum in proximal lower limb region followed by proximal upper limb. Multivariate regression analysis showed that the severity of muscle weakness, serum Mi2B antibody positivity and serum creatinine kinase levels had a significant positive correlation with FDG uptake (value of 0.005, 0.043, 0.042, respectively for whole-body FDG uptake). FDG uptake also showed good correlation with histopathological features and muscle MRI, but there was no significant association with treatment response. Three female patients in our cohort had primary malignancy involving the breast, uterus, and cervix.
CONCLUSIONS: PET-MRI is a promising diagnostic modality for IIM. PET-MRI reflects the severity of muscle inflammation, showing good association with various clinical/laboratory parameters, histopathology, and muscle MRI. Parameters associated with severe muscle inflammation in PET-MRI-clinical severity of muscle weakness, Mi2B positivity, and serum creatine kinase levels-may be used as clinical/laboratory markers of disease severity in IIM. PET-MRI has the added advantage of detection of systemic malignancy.
METHODS: A retrospective, observational study was conducted on IIM patients having positive serum autoantibodies and who underwent PET-MRI (3-Tesla SIEMENS Biograph MR scanner) between 2017 and 2021. Thirty patients who underwent PET-MRI to detect systemic metastasis without muscle involvement formed the control group.
RESULTS: In the IIM cohort, female: male sex ratio was 1.73, mean age at diagnosis was 40.33 years, and the mean duration of illness was 7 months. 33.33% of patients had severe limb weakness. Mi2B (43.33%), Mi2A (43.33%), PL-7(10%), PL-12(6.67%), SRP (16.67%), Tif1gamma (3.33%), NxP2 (3.33%), Ro-52(40%), PM-Scl, U1-RNP, ANA (26.67%) were the serum autoantibodies identified. Using SUV max Ratio to quantify FDG uptake, PET-MRI showed a sensitivity of 100% with 93.3% specificity in diagnosing IIM.FDG uptake was maximum in proximal lower limb region followed by proximal upper limb. Multivariate regression analysis showed that the severity of muscle weakness, serum Mi2B antibody positivity and serum creatinine kinase levels had a significant positive correlation with FDG uptake (value of 0.005, 0.043, 0.042, respectively for whole-body FDG uptake). FDG uptake also showed good correlation with histopathological features and muscle MRI, but there was no significant association with treatment response. Three female patients in our cohort had primary malignancy involving the breast, uterus, and cervix.
CONCLUSIONS: PET-MRI is a promising diagnostic modality for IIM. PET-MRI reflects the severity of muscle inflammation, showing good association with various clinical/laboratory parameters, histopathology, and muscle MRI. Parameters associated with severe muscle inflammation in PET-MRI-clinical severity of muscle weakness, Mi2B positivity, and serum creatine kinase levels-may be used as clinical/laboratory markers of disease severity in IIM. PET-MRI has the added advantage of detection of systemic malignancy.
摘要：
背景：我们试图确定PET-MRI在诊断特发性炎性肌炎（IIM）中的实用性，寻找FDG摄取和临床之间的关联，病理和实验室参数。
方法：回顾性研究，我们对血清自身抗体阳性并在2017年至2021年间接受PET-MRI(3-TeslaSIEMENSBiographMR扫描仪)的IIM患者进行了观察性研究.30例接受PET-MRI检查以检测全身转移而无肌肉受累的患者为对照组。
结果：在IIM队列中，女性：男性性别比为1.73，诊断时平均年龄为40.33岁，平均病程为7个月。33.33%的患者存在严重的肢体无力。Mi2B（43.33%），Mi2A（43.33%），PL-7（10%），PL-12（6.67%），SRP（16.67%），Tif1gamma（3.33%），NxP2（3.33%），Ro-52(40%),PM-Scl,U1-RNP,ANA(26.67%)是鉴定的血清自身抗体。使用SUV最大比率来量化FDG摄取，PET-MRI显示诊断IIM的敏感性为100％，特异性为93.3％。FDG摄取在近端下肢区域最大，其次是近端上肢。多因素回归分析显示肌无力的严重程度,血清Mi2B抗体阳性和血清肌酐激酶水平与FDG摄取呈显著正相关(全身FDG摄取的值分别为0.005、0.043、0.042)。FDG摄取与组织病理学特征和肌肉MRI也显示出良好的相关性，但与治疗反应无显著关联.我们队列中的三名女性患者患有累及乳腺的原发性恶性肿瘤，子宫,还有子宫颈.
结论：PET-MRI是一种有前途的诊断IIM的方法。PET-MRI反映了肌肉炎症的严重程度，显示与各种临床/实验室参数的良好关联，组织病理学,肌肉MRIPET-MRI中与严重肌肉炎症相关的参数-肌肉无力的临床严重程度，Mi2B阳性，和血清肌酸激酶水平-可用作IIM疾病严重程度的临床/实验室标志物。PET-MRI具有检测全身性恶性肿瘤的额外优势。
方法：回顾性研究，我们对血清自身抗体阳性并在2017年至2021年间接受PET-MRI(3-TeslaSIEMENSBiographMR扫描仪)的IIM患者进行了观察性研究.30例接受PET-MRI检查以检测全身转移而无肌肉受累的患者为对照组。
结果：在IIM队列中，女性：男性性别比为1.73，诊断时平均年龄为40.33岁，平均病程为7个月。33.33%的患者存在严重的肢体无力。Mi2B（43.33%），Mi2A（43.33%），PL-7（10%），PL-12（6.67%），SRP（16.67%），Tif1gamma（3.33%），NxP2（3.33%），Ro-52(40%),PM-Scl,U1-RNP,ANA(26.67%)是鉴定的血清自身抗体。使用SUV最大比率来量化FDG摄取，PET-MRI显示诊断IIM的敏感性为100％，特异性为93.3％。FDG摄取在近端下肢区域最大，其次是近端上肢。多因素回归分析显示肌无力的严重程度,血清Mi2B抗体阳性和血清肌酐激酶水平与FDG摄取呈显著正相关(全身FDG摄取的值分别为0.005、0.043、0.042)。FDG摄取与组织病理学特征和肌肉MRI也显示出良好的相关性，但与治疗反应无显著关联.我们队列中的三名女性患者患有累及乳腺的原发性恶性肿瘤，子宫,还有子宫颈.
结论：PET-MRI是一种有前途的诊断IIM的方法。PET-MRI反映了肌肉炎症的严重程度，显示与各种临床/实验室参数的良好关联，组织病理学,肌肉MRIPET-MRI中与严重肌肉炎症相关的参数-肌肉无力的临床严重程度，Mi2B阳性，和血清肌酸激酶水平-可用作IIM疾病严重程度的临床/实验室标志物。PET-MRI具有检测全身性恶性肿瘤的额外优势。
