全身MRI与PET/CT在淋巴瘤骨髓浸润诊断及预后中的作用

淋巴瘤是一种血液系统恶性肿瘤。淋巴瘤骨髓浸润(BMI)使疾病分期上升至IV期, 是疾病进展、预后较差的标志。常规部位的骨髓活检(BMB)具有创伤性, 且检出率低。PET/CT与全身MRI的出现, 丰富了BMI的检测手段。PET/CT与全身MRI对于淋巴瘤, 尤其是侵袭性淋巴瘤BMI均具有较高的检出率, 二者孰高孰低, 尚未定论。对于红骨髓、良性骨髓病变(炎症等)、淋巴瘤BMI病灶以及肿瘤治疗后骨髓的变化与骨髓残留或复发病灶, 全身MRI很难区分, 而PET/CT却可以很好地鉴别这些病灶。但是, PET/CT存在电离辐射; 对于惰性淋巴瘤的BMI, 超出PET/CT分辨率的病灶, 可能出现假阴性; 某些情况会限制PET/CT的使用, 包括18F-FDG生理性摄取量可能发生改变的正常组织、18F-FDG摄取相关性炎症、高血糖或高胰岛素血症导致的18F-FDG分布的改变、肿瘤患者治疗后出现的骨髓活化等。然而, 这些情况可以使用全身MRI。因此, 全身MRI和PET/CT相辅相成, 优势互补, 但二者均不能代替BMB。对于常规BMB阴性, 但影像学提示阳性的患者, 在影像学引导下进行BMB, 可以提高BMI的检出率。另外, 全身MRI阳性的淋巴瘤BMI患者与全身MRI阴性的淋巴瘤BMI患者相比, 前者预后可能较差。

Function of whole-body MRI and PET/CT in the diagnosis and prognosis of lymphoma with bone marrow infiltration

Lymphoma is a malignant tumor of the blood system.Bone marrow infiltration (BMI) advances the disease to stage IV and is a marker of disease progression and poor prognosis.Conventional bone marrow biopsy is a traumatic detection, and the rate is low.The emergence of PET/CT and wholebody MRI supplements the means of BMI detection.PET/CT and whole-body MRI both exhibit a high detection rate for lymphoma BMI, particularly for aggressive lymphoma BMI.However, both approaches to determine high and low is inconclusive, For red bone marrow, benign bone marrow lesions (inflammation and others), lymphoma BMI lesions, as well as bone marrow changes after tumor therapy and bone marrow residual or recurrent lesions, whole body MRI is difficult to distinguish.PET/CT can excellently identify these lesions.However, PET/CT uses ionizing radiation : false negative results can be present for inert lymphoma BMI lesions and lesions beyond the PET/CT resolution.Certain circumstances may limit the use of PET/CT, including normal tissue, whose 18F-FDG physiological uptake may change;inflammation, which is related to 18F-FDG uptake, changes in the distribution of 18F-FDG caused by high blood glucose or high blood insulin, bone marrow activation in tumor patients after treatment, and so on.In these cases, we can use whole-body MRI.Therefore, the two approaches are complementary.Neither PET/CT nor whole body MRI can replace BMB.BMB under the guidance of PET/CT or whole-body MRI considerably improves the detection rate of BMI for patients with negative BMB findings, but imaging findings are positive.In addition, whole-body MRI-positive patients may present poorer prognosis than whole-body MRI-negative patients.