The value of signal intensity on T1-weighted chemical shift magnetic resonance imaging combined with proton magnetic resonance spectroscopy for the diagnosis of adrenal adenomas

Abstract Objective: To investigate the advantages of using modified signal intensity measurements on chemical shift imaging alone or in conjunction with proton magnetic resonance spectroscopy in the differential diagnosis of adrenal adenomas. Materials and Methods: This was a prospective study involving 97 patients with adrenal nodules or masses. The signal intensity index (SII) was calculated as [(signal intensity on the in-phase image − signal intensity on the out-of-phase image) ∕ (signal intensity on the in-phase image)] × 100%. We determined the averages of the minimum, mean, and maximum signal intensity values measured on three consecutive images. When that was not possible (for smaller lesions), we used one or two images. We employed a region of interest that covered one half to two thirds of the mass. All indices were compared with metabolite ratios derived from spectroscopy: lactate/creatine; glutamine-glutamate/creatine; choline/creatine; choline/lipid; 4.0-4.3 ppm/Cr; and lipid/creatine. Results: Of the 97 patients evaluated, 69 were diagnosed with adenomas and 28 were diagnosed with nonadenomas. All SII measurements and spectroscopy-derived metabolite ratios were significant to the differentiation between adenomas and nonadenomas, except for the lipid/creatine and choline/lipid ratios. In 37.8% of the cases, it was not possible to perform spectroscopy. When it was possible, the lactate/creatine ratio was found to have higher accuracy than did the SII. Conclusion: Determining the SII and metabolite ratios increased the accuracy of the differential diagnosis of adrenal adenomas.

摘要
研究目的：探讨仅采用改良信号强度测量的化学位移成像（Chemical Shift Imaging），或联合质子磁共振波谱（Proton Magnetic Resonance Spectroscopy）用于肾上腺腺瘤（Adrenal Adenomas）鉴别诊断的优势。

材料与方法：本研究为前瞻性研究，纳入97例肾上腺结节或肿块患者。信号强度指数（signal intensity index，SII）计算公式为：[(同相位图像（in-phase image）信号强度 − 反相位图像（out-of-phase image）信号强度) / 同相位图像（in-phase image）信号强度] × 100%。我们对连续3幅图像上测得的最小、平均及最大信号强度值取平均值；若病灶较小无法完成此操作，则采用1幅或2幅图像进行测量。我们使用覆盖病灶1/2至2/3范围的感兴趣区（region of interest）。将所有指数与波谱衍生的代谢物比值进行对比：乳酸/肌酸、谷氨酰胺-谷氨酸/肌酸、胆碱/肌酸、胆碱/脂质、4.0-4.3ppm/肌酸及脂质/肌酸比值。

结果：纳入评估的97例患者中，69例确诊为肾上腺腺瘤，28例确诊为非腺瘤。除脂质/肌酸及胆碱/脂质比值外，所有信号强度指数测量值及波谱衍生代谢物比值均对腺瘤与非腺瘤的鉴别诊断具有显著价值。37.8%的病例无法完成波谱检查；在可行波谱检查的病例中，乳酸/肌酸比值的诊断准确度高于信号强度指数。

结论：测定信号强度指数及代谢物比值可提高肾上腺腺瘤鉴别诊断的准确度。