Crespi G, Zappasodi F, Cicio G, Martinoli C, Valle M
Cattedra R di Radiologia DICMI, Università di Genova.
Radiol Med. 2000 Jun;99(6):426-31.
To report the various US patterns of the diaphragmatic crura and the changes occurring during the different phases of respirations. The diaphragm has two US patterns: the central membranous part appears highly reflective while the posterior, upper and lateral muscular portions are hypoechoic and thick. The crura can sometimes appear quite bulky, which appearance is easy to misinterpret.
We carried out a three-stage work: first we reviewed the US examinations of 23 subjects with a nodular appearance of the posteromedial bundles and studied the changes in thickness during respiration. Second we studied the diaphragmatic crura in 30 subjects aged 18-71 years, 15 men and 15 women. We used a commercially available unit with sector and convex 3.5 MHz probes at baseline and during breath hold and acquired multiple parasagittal and transverse scans. The crura thickness was measured in all patients. Last, we studied the diaphragmatic regions of 10 patients with right pleural effusion and of 8 patients with associated ascites and pleural effusion using 2.0-5.0 MHz convex phased-array transducers.
We found focal thickening of the crura in 11 of 23 patients with US findings of diaphragmatic nodules, but only in deep inspiration. The thickening was 1.5-2.2 cm long and maximum thickness was 10 mm. In the other 12 subjects we found 9 small lobules in the right and 3 in the left crus. In the anatomic study, we observed a 3-band appearance of the diaphragmatic crura, probably referable to muscle bundles, in 30 subjects on sagittal images, in 12 on coronal images and in 28 on anterior transverse images. The diaphragmatic crura were identified in 26 subjects only. The left posterior crus was identified in 29 subjects on left coronal images and in 15 on anterior transverse images; it was demonstrated on anterior sagittal images in close proximity to the aorta in only 4 subjects. Right crus thickness, measured on sagittal scans, ranged 3-10 mm in deep inspiration and 1-4 mm in expiration while the left crus was 3-6 mm in inspiration and 1-2 mm in expiration. The length of the right crus, studied in the preaortic portion, ranged from 7 cm in deep inspiration to 9.7 cm in expiration while the left one was 6.5 to 8.8 cm. The right lateral diaphragmatic bundles were seen in 28 subjects only on repeated subcostal oblique scans and the the left ones in 11 subjects only. Finally the thin anterior bundles were shown on parasagittal images in 13 cases in the right side and in 2 in the left. A 2-band appearance of the diaphragm was seen in 10 patients with pleural effusion and in 8 patients with associated ascites. A single band was found only in the tendinous portion of the diaphragm.
US is presently considered the imaging method of choice in the assessment of changes in thickness and length of the diaphragmatic crura. These structures have different US patterns and can sometimes appear quite bulky and thus be easily mistaken for other anatomic or abnormal structures; orthogonal scans may be required for the differential diagnosis.
报告膈肌脚的各种超声表现以及呼吸不同阶段所发生的变化。膈肌有两种超声表现：中央膜性部分表现为高回声，而后部、上部及外侧肌肉部分为低回声且增厚。膈肌脚有时看起来相当粗大，这种表现容易被误解。
我们进行了三个阶段的工作：首先，我们回顾了23例后内侧束呈结节状表现的受试者的超声检查，并研究了呼吸过程中其厚度的变化。其次，我们研究了30例年龄在18 - 71岁之间的受试者的膈肌脚，其中男性15例，女性15例。我们使用一台配备扇形和凸阵3.5 MHz探头的商用设备，在基线状态及屏气时进行检查，并获取多个矢状位和横断位扫描图像。测量了所有患者的膈肌脚厚度。最后，我们使用2.0 - 5.0 MHz凸阵相控阵探头研究了10例右侧胸腔积液患者以及8例伴有腹水和胸腔积液患者的膈肌区域。
在23例超声检查发现膈肌结节的患者中，我们发现11例患者的膈肌脚有局灶性增厚，但仅在深吸气时出现。增厚长度为1.5 - 2.2 cm，最大厚度为10 mm。在其他12例受试者中，我们在右侧膈肌脚发现9个小结节，在左侧发现3个。在解剖学研究中，我们在矢状位图像上观察到30例受试者、冠状位图像上12例受试者以及前位横断位图像上28例受试者的膈肌脚呈现出3条带的表现，可能与肌束有关。仅在26例受试者中识别出了膈肌脚。在左侧冠状位图像上29例受试者以及前位横断位图像上15例受试者中识别出了左后膈肌脚；仅在4例受试者的前位矢状位图像上显示其紧邻主动脉。在矢状位扫描上，右侧膈肌脚在深吸气时厚度为3 - 10 mm，呼气时为1 - 4 mm，而左侧膈肌脚吸气时为3 - 6 mm，呼气时为1 - 2 mm。在前主动脉部分研究的右侧膈肌脚长度，深吸气时为7 cm，呼气时为9.7 cm，而左侧为6.5至8.8 cm。仅在28例受试者的反复肋下斜位扫描中看到右侧外侧膈肌束，仅在11例受试者中看到左侧外侧膈肌束。最后，在矢状位图像上，右侧13例、左侧2例显示出纤细的前膈肌束。在10例胸腔积液患者以及8例伴有腹水和胸腔积液的患者中看到膈肌呈现出2条带的表现。仅在膈肌的腱性部分发现一条带。
目前超声被认为是评估膈肌脚厚度和长度变化的首选成像方法。这些结构有不同的超声表现，有时看起来相当粗大，因此容易被误认为是其他解剖结构或异常结构；鉴别诊断可能需要进行正交扫描。
