Yoshikawa Takeshi, Kawamitsu Hideaki, Mitchell Donald G, Ohno Yoshiharu, Ku Yonson, Seo Yasushi, Fujii Masahiko, Sugimura Kazuro
Department of Radiology, Division of Magnetic Resonance Imaging, Thomas Jefferson University, 132 S 10th St., Suite 1096, Philadelphia, PA 19107, USA.
AJR Am J Roentgenol. 2006 Dec;187(6):1521-30. doi: 10.2214/AJR.05.0778.
The purpose of our study was to assess the reliability and usefulness of parallel imaging for apparent diffusion coefficient (ADC) measurement of abdominal organs and lesions.
Single-shot spin-echo echo-planar diffusion-weighted MRI (TE = 66, b = 0, 600 s/mm2) was performed in phantom and clinical studies. The b value was set to minimize the effects of perfusion in tissue and to maintain signal-to-noise ratio. Bottle phantoms were scanned with and without parallel imaging and with various parallel imaging factors and at various positions to evaluate the effects of parallel imaging on ADCs. In 200 consecutive clinical patients (122 men and 78 women: mean age, 61.9 years), ADCs were calculated for liver (four segments), spleen, pancreas (head, body, tail), gallbladder, renal parenchyma, and back muscle, and then compared to evaluate the reliability of clinical ADC measurements with parallel imaging. ADCs were also calculated for diffuse diseases and focal lesions (94 malignant and 93 benign) of abdominal organs to evaluate the clinical usefulness of ADC.
Location-dependent changes in water ADCs were minimal with parallel imaging factors first of 3, then of 4, and were small except for measurements at the image periphery. Acetone ADCs were saturated at 4.00 x 10(-3) mm2/s. Degraded image quality prevented ADC measurement of the left hepatic lobe and pancreas in 7-18 patients. There was no significant difference among ADCs of four liver segments (1.50 +/- 0.24 [SD] x 10(-3) mm2/s - 1.56 +/- 0.31 x 10(-3) mm2/s) and between ADCs of the right and left kidneys (2.65 +/- 0.30 x 10(-3) mm2/s, 2.59 +/- 0.33 x 10(-3) mm2/s). ADC of the pancreas tail (1.65 +/- 0.37 x 10(-3) mm2/s) was significantly lower than those of the head (1.81 +/- 0.40 x 10(-3) mm2/s) and body (1.81 +/- 0.41 x 10(-3) mm2/s) (p < 0.005). Renal ADCs were significantly lower in patients with renal failure (right: 2.15 +/- 0.30 x 10(-3) mm2/s; left: 2.11 +/- 0.25 x 10(-3) mm2/s) than in those without disease (right: 2.67 +/- 0.29 x 10(-3) mm2/s; left: 2.60 +/- 0.32 x 10(-3) mm2/s) (p < 0.005). ADC of pancreatic cancer was significantly higher than that of healthy pancreas (p < 0.05). ADC of renal angiomyolipoma was significantly lower than those of renal cell carcinoma and healthy renal parenchyma (p < 0.0005).
Clinical ADC measurements of abdominal organs and lesions using parallel imaging appear to be reliable and useful, and the effect of parallel imaging on calculated values is considered to be minimal.
本研究的目的是评估并行成像在腹部器官和病变表观扩散系数（ADC）测量中的可靠性和实用性。
在体模和临床研究中进行单次激发自旋回波平面扩散加权磁共振成像（TE = 66，b = 0，600 s/mm²）。设置b值以最小化组织灌注的影响并维持信噪比。对瓶状体模进行扫描，有无并行成像、不同并行成像因子以及在不同位置进行扫描，以评估并行成像对ADC值的影响。在200例连续临床患者（122例男性和78例女性：平均年龄61.9岁）中，计算肝脏（四个节段）、脾脏、胰腺（头部、体部、尾部）、胆囊、肾实质和背部肌肉的ADC值，然后进行比较以评估并行成像临床ADC测量的可靠性。还计算腹部器官弥漫性疾病和局灶性病变（94例恶性和93例良性）的ADC值，以评估ADC的临床实用性。
并行成像因子为3和4时，水ADC值的位置依赖性变化最小，除图像周边测量外变化较小。丙酮ADC值在4.00×10⁻³ mm²/s时饱和。图像质量下降导致7 - 18例患者无法测量左肝叶和胰腺的ADC值。四个肝段的ADC值（1.50±0.24[标准差]×10⁻³ mm²/s - 1.56±0.31×10⁻³ mm²/s）之间以及右肾和左肾的ADC值（2.65±0.30×10⁻³ mm²/s，2.59±0.33×10⁻³ mm²/s）之间无显著差异。胰腺尾部的ADC值（1.65±0.37×10⁻³ mm²/s）显著低于头部（1.81±0.40×10⁻³ mm²/s）和体部（1.81±0.41×10⁻³ mm²/s）（p < 0.005）。肾衰竭患者的肾ADC值（右侧：2.15±0.30×10⁻³ mm²/s；左侧：2.11±0.25×10⁻³ mm²/s）显著低于无疾病患者（右侧：2.67±0.29×10⁻³ mm²/s；左侧：2.60±0.32×10⁻³ mm²/s）（p < 0.005）。胰腺癌的ADC值显著高于健康胰腺（p <
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