Cesarani F, Isolato G, Capello S, Bianchi S D
Dipartimento di Discipline Medico Chiruriche, Università degli Studi, Torino.
Radiol Med. 1999 Apr;97(4):256-64.
We report our preliminary clinical experience with three-dimensional ultrasound (3D US) in abdominal and small parts imaging, comparing the yield of 3D versus 2D US and through a literature review.
We used a Tomtec Echo-Scan 3.1 connected to a Philips P 700 unit with a 3.5 MHz convex probe and to a Toshiba SSA-340 A (equipped with power Doppler) with a 3.5 MHz convex and a 7.5 MHz linear probes. The system consists of: a) a workstation (166 MHz Intel Pentium, 128 Mbytes RAM, 520 Mbytes hard disk, 1.3 Gbyte Magneto-Optical drive); b) a spatial location system (3D Freehand Scanning) whose sensor, attached to the probe, provides spatial coordinates for each US scan in an electromagnetic field created by a transmitter; the software can thus correctly stack 2D US images to make 3D reconstructions of anatomical structures. The technical steps are: 1) setting; 2) image acquisition; 3) image processing and 3D rendering using surface or volume modes; 4) image archiving. 2D US was performed on 50 subjects, namely 20 volunteers and 30 patients with different pathologic conditions and 3D reconstructions were obtained from the best US images. We evaluated which anatomical structures and pathologic conditions are best suited for 3D rendering.
The best 3D images were obtained from anatomical structures and pathologic conditions with a liquid content (i.e., bladder and gallbladder; cysts), or those adjacent to them (i.e., uterus and prostate). Major limitations were encountered in the assessment of the parenchyma of liver, kidneys, pancreas, thyroid, testis and breast, due to intrinsic texture low contrast, while intraparenchymal liquid structures (i.e., vessels, urinary cavities) and structures surrounded by liquid (i.e., hydrocele, ascites) were better demonstrated.
The system permits accurate spatial location, and therefore stacking, of each US scan; this provides good-quality 3D images with fewer artifacts. The system can be connected to any existing US unit and to many kinds of probes. Incorrect processing or rendering may worsen 3D image quality and thus anatomical reconstructions; other drawbacks may come from difficult stacking of reconstructed images or limited field of view. Our personal experience and the review of 3D US literature indicate that the system may be used for the following clinical applications: anatomical assessment of lesions for minimally invasive treatment; targeting areas of interest and adjacent structures during radiotherapy; lesion volume studies during therapy; 3D vascular mapping with power Doppler; 3D reconstructions by intraluminal approach; real-time 3D scanning for US guidance during minimally invasive procedures.
Our preliminary experience suggests that technological progress will soon lead to a widespread use of 3D US and its applications.
我们报告三维超声（3D US）在腹部及小器官成像方面的初步临床经验，通过比较3D US与二维超声（2D US）的成像效果并进行文献综述。
我们使用连接到飞利浦P 700超声仪的Tomtec Echo-Scan 3.1，配备3.5 MHz凸阵探头，以及连接到东芝SSA-340 A（配备能量多普勒）的Tomtec Echo-Scan 3.1，配备3.5 MHz凸阵探头和7.5 MHz线阵探头。该系统包括：a）一个工作站（166 MHz英特尔奔腾处理器，128 M字节随机存取存储器，520 M字节硬盘，1.3 G字节磁光盘驱动器）；b）一个空间定位系统（3D自由臂扫描），其传感器连接到探头上，在由发射器产生的电磁场中为每次超声扫描提供空间坐标；软件因此可以正确叠加2D US图像以进行解剖结构的3D重建。技术步骤为：1）设置；2）图像采集；3）使用表面或容积模式进行图像处理和3D渲染；4）图像存档。对50名受试者进行了2D US检查，即20名志愿者和30名患有不同病理状况的患者，并从最佳超声图像中获得3D重建图像。我们评估了哪些解剖结构和病理状况最适合3D渲染。
最佳的3D图像是从含有液体的解剖结构和病理状况（即膀胱和胆囊；囊肿）或与其相邻的结构（即子宫和前列腺）获得的。在评估肝脏、肾脏、胰腺、甲状腺、睾丸和乳腺的实质时遇到了主要限制，这是由于其内在纹理对比度低，而实质内液体结构（即血管、肾盂）和被液体包围的结构（即鞘膜积液、腹水）显示得更好。
该系统允许对每次超声扫描进行精确的空间定位，从而进行叠加；这提供了具有较少伪像的高质量3D图像。该系统可以连接到任何现有的超声设备和多种探头。不正确的处理或渲染可能会使3D图像质量变差，从而影响解剖结构重建；其他缺点可能来自重建图像叠加困难或视野有限。我们的个人经验和对3D US文献的综述表明，该系统可用于以下临床应用：对病变进行解剖评估以进行微创治疗；在放射治疗期间确定感兴趣区域和相邻结构；治疗期间的病变体积研究；使用能量多普勒进行3D血管造影；通过腔内途径进行3D重建；在微创操作期间进行实时3D扫描以获得超声引导。
我们的初步经验表明，技术进步将很快导致3D US及其应用的广泛使用。
