腰椎多层螺旋CT容积扫描的临床应用

Clinical application of multi-slice helical CT volumetric scanning in lumber spine

目的探讨腰椎多层螺旋CT容积（VH）扫描的临床应用价值。方法按就诊顺序抽取1000例腰腿痛患者，腰椎VH模式扫描患者模拟重建常规单层（SS）L3～4、L4—5、L5-S1椎间盘层面。VH扫描模式参数为120kV，210mAs，螺距1．5，平均扫描范围97．5mm。SS扫描模式参数为120kV、240mAs、扫描范围为45．0mm。比较2种扫描模式对腰椎疾病征象显示的差异及辐射剂量的不同。对所获数据进行配对资料X^2检验和一致性检验分析。结果VH扫描模式比SS扫描模式显示更多的征象，骨性椎管狭窄、椎间隙变窄、椎间盘脱出、侧隐窝狭窄、椎体病变、L5横突肥大、椎小关节方向异常、椎小关节退行性变、椎弓峡部裂、椎旁软组织异常的检出率，VH分别为11．8％（118例）、38．5％（385例）、9．3％（93例）、46．8％（468例）、31．4％（314例）、5．7％（57例）、25．4％（254例）、49．7％（497例）、9．9％（99例）、0．6％（6例），ss分别为5．6％（56例）、0、0．6％（6例）、27．9％（279例）、22．4％（224例）、1．2％（12例）、16．7％（167例）、37．2％（372例）、0．5％（5例）、0．2％（2例），2种模式下对每一种测量指标比较除椎旁软组织异常两者差异无统计学意义（P〉0．05）外，其余测量指标差异均有统计学意义（P值均〈0．05）。与ss扫描模式相比，VH扫描模式下的骨性椎管狭窄、椎间隙变窄、椎间盘脱出和椎弓峡部裂的检出率分别提高6．2％（62例）、38．5％（385例）、8。7％（87例）和9．4％（94例），只能部分显示椎小关节面及方向、侧隐窝狭窄、L5横突肥大和椎旁软组织异常。46．7％（467例）（腰骶角〉35°）的患者SS扫描模式下的定位线不能与椎间盘层面一致。VH扫描模式（164．9mGy／cm）比SS扫描模式（147．0mGy／cm）辐射剂量稍有增加。结论腰椎多层螺旋CT VH扫描模式比SS扫描模式可以显示更多腰椎病变征象，且不受扫描架限制，辐射剂量增加不多。

Objective To evaluate the clinical application value of multi-slice helical CT volumetric （VH） scanning in lumber spine. Methods One thousand of patients with back and leg pain who underwent CT examinations were selected as subjects. We simulated the traditional protocol of single-slice（SS） discrete scanning for L3/4, L4/5, and LS/S1 intervertebral discs. The VH scanning mode was performed with 120 kV, 210 mAs,pitch of 1.5 and coverage of 97. 5 mm. The simulated SS scanning mode was performed with 120 kV, 240 mAs and coverage of 45.0 mm. The diagnostic outcomes and the radiation doses were compared between the two scanning modes. Two groups doctors observed ten terms, including the osseous spinal stenosis, narrowed intervertebral space and so on in two scanning modes respectively. Then consistency analysis of the data was carried out. Results The VH scanning mode showed far more features than the SS mode. The detection rates of the VH mode in the osseous spinal stenosis, narrowed intervertebral space, herniated nucleus pulposus, narrowed lateral recess, vertebral lesion, hypertrophy of L5 transverse process, abnormal direction of facet, facet degeneration, lumbar spondyloschisis, and paraspinal soft tissue were 11.8%（n=118）, 38.5%（n=385）,9.3%（n=93）,46.8%（n=468）,31.4%（n=314）,5.7%（n= 57）, 25.4% （ n = 254）, 49. 7% （ n = 497 ）, 9. 9% （ n = 99 ）, and 0. 6% （ n = 6） respectively, while the detection rates of the SS mode in ten terms were 5.6% （ n = 56）, 0, 0. 6% （ n = 6）, 27. 9% （ n = 279）,22.4% （n =224）, 1.2% （n =12）, 16.7% （n = 167）, 37.2% （n = 372）, 0.5% （n =5）, and 0.2% （n =2） respectively. The difference between the two groups had statistically significance （average P 〈 0. 05 ）, except the paraspinal soft tissue abnormal （ P 〉 0. 05 ）. The detection rates of the VH mode were higher than the SS mode in the osseous spinal stenosis, narrowed intervertebral space, herniated nucleus pulposus, lumbar spondylosehisis, being 6.2% （n = 62） ,38. 5% （n = 385 ）, 8. 7% （n = 87 ）, and 9.4% （n =94）, respectively. In addition, VH mode only partially showed the articular facets, narrowed lateral recess, hypertrophy of I5 transverse process, and paraspinal soft tissue. We could not acquire the imaging slices paralleling to intervertebral discs in SS mode in 467 patients （46.7%） with lumbosacral angle greater than 35°. The radiation dose of VH mode （164.9 mGy/cm） was slightly higher than SS mode （147.0 mGy/cm） Conclusion MSCT VH scanning mode can significantly improve the diagnostic rate of lumbar spine diseases compared with SS mode, and was not restricted by the lumbosacral angle with slightly increasing radiation dosage.