Urban B A, Fishman E K, Kuhlman J E, Kawashima A, Hennessey J G, Siegelman S S
Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore 21205.
AJR Am J Roentgenol. 1993 Apr;160(4):783-5. doi: 10.2214/ajr.160.4.8456665.
The objective of this study was to determine if spiral CT with 4-mm interscan spacing results in increased confidence in or rate of detection of focal hepatic lesions when compared with spiral CT with 8-mm interscan spacing.
Spiral CT scans of the liver of 42 consecutive patients with suspected hepatic disease were independently reviewed by three senior radiologists in two sets: one set was reconstructed with 8-mm interscan spacing and one set was reconstructed with 4-mm interscan spacing. The slice thickness was 8 mm for both data sets. The number and sizes of focal hepatic lesions were documented.
Thirty-three of the 42 patients had least one focal lesion. The lesion size varied from 2 mm to 21 cm. When 8-mm interscan spacing was used, 297 lesions were detected (212 were considered definite). When 4-mm interscan spacing was used, 318 lesions were detected (258 were considered definite). Therefore, 7% more lesions were detected with 4-mm interscan spacing than with 8-mm interscan spacing (p = .05), and 22% more were diagnosed definitively (p < .01). If lesions larger than 4 cm are excluded, 10% more lesions were detected with 4-mm interscan spacing, and 33% more were diagnosed definitively. Of the lesions detected exclusively with 4-mm interscan spacing, 69% were less than 1.0 cm in diameter.
Spiral CT with smaller interscan spacing (4 instead of 8 mm) results in increased confidence in and rate of detection of focal liver lesions. The additional benefit is most significant with smaller lesions.
本研究的目的是确定与层厚间距为8毫米的螺旋CT相比，层厚间距为4毫米的螺旋CT是否能提高对肝脏局灶性病变的诊断信心或检出率。
42例疑似肝脏疾病患者的肝脏螺旋CT扫描图像由三位资深放射科医生独立进行两组分析：一组重建层厚间距为8毫米，另一组重建层厚间距为4毫米。两组数据集的层厚均为8毫米。记录肝脏局灶性病变的数量和大小。
42例患者中有33例至少有一个局灶性病变。病变大小从2毫米到21厘米不等。使用8毫米层厚间距时，共检测到297个病变（其中212个被认为是确定性病变）。使用4毫米层厚间距时，共检测到318个病变（其中258个被认为是确定性病变）。因此，与8毫米层厚间距相比，4毫米层厚间距时多检测到7%的病变（p = 0.05），且确定性诊断的病变多22%（p < 0.01）。如果排除直径大于4厘米的病变，4毫米层厚间距时多检测到10%的病变，且确定性诊断的病变多33%。在仅用4毫米层厚间距检测到的病变中，69%的病变直径小于1.0厘米。
层厚间距较小（4毫米而非8毫米）的螺旋CT可提高对肝脏局灶性病变的诊断信心和检出率。对于较小的病变，这种额外的益处最为显著。
