双能量CT虚拟去钙成像评估腰椎间盘退变

Feasibility of dual energy CT virtual non-calcium imaging for evaluation on lumbar intervertebral disc degeneration

目的分析双能量CT(DECT)虚拟去钙(VNCa)成像评估腰椎间盘退变(IDD)的可行性。方法回顾性分析37例接受腰椎DECT和MR检查的慢性腰痛患者,根据改良Pfirrmann分级(mPG)标准对MRI所示椎间盘进行分级,评估IDD程度;对DECT数据行后处理,获得线性融合CT图像(相当于常规CT)和VNCa灰度图及彩色编码图。于常规CT和VNCa灰度图上测量腰椎间盘髓核的CT值,分析其与mPG的相关性。根据VNCa彩色编码图中椎间盘髓核和纤维环衰减程度对椎间盘进行视觉分型,比较不同分型间mPG差异,并分析VNCa视觉分型与mPG的关系。结果共纳入168个腰椎间盘,包括12个mPG 1级、39个2级、47个3级、50个4级和20个5级及以上,51个VNCa视觉分型Ⅰ型、51个Ⅱ型和66个Ⅲ型。在VNCa灰度图上,各mPG分级髓核CT值差异均有统计学意义(P均<0.001)。常规CT上,mPG 2级与3级、4级与5级及以上之间髓核CT值差异均无统计学意义(P=0.173、0.083),其余各mPG分级间髓核CT值差异均有统计学意义(P均<0.05)。常规CT和VNCa灰度图中,髓核CT值与mPG分级均呈正相关(r=0.504、0.745,P均<0.001)。VNCa视觉分型与mPG分级呈正相关(r=0.900,P<0.001),不同VNCa分型间mPG分级差异有统计学意义(H=82.610,P<0.001)。结论DECT-VNCa成像可用于评估腰椎间盘IDD。

Objective To evaluate the feasibility of dual energy CT(DECT)virtual non-calcium(VNCa)imaging for evaluation on lumbar intervertebral disc degeneration(IDD).Methods Data of 37 chronic low back pain patients who underwent both lumbar DECT and MR scanning were retrospectively analyzed.All discs on MRI were classified according to modified Pfirrmann grade(mPG).Data of DECT were postprocessed to obtain linear mixed CT(equivalent to conventional CT),VNCa grayscale and color-coded maps.CT values of lumbar disc nucleus pulposus were measured on conventional CT and VNCa grayscale maps,and the correlations of CT values and mPG grades were analyzed,respectively.Visual classification of lumbar discs was performed according to the attenuation degree of nucleus pulposus and annulus fibrosus on color-coded VNCa maps,and the mPG grades were compared among different VNCa types,and the relationship between the visual categories and mPG was analyzed.Results A total of 168 lumbar intervertebral discs were enrolled,including 12 mPG grade 1,39 mPG grade 2,47 mPG grade 3,50 mPG grade 4 and 20 mPG grade 5 and higher than 5.For VNCa visual classification,there were 51 typeⅠ,51 typeⅡand 66 typeⅢlumbar intervertebral discs.CT values of pulposus were significantly different among mPG grades on VNCa grayscale maps(all P<0.001).On conventional CT,there was no statistical difference of CT values of nucleus pulporeus between mPG 2 and 3 grade(P=0.173),mPG 4 and 5 and higher than 5 grade(P=0.083),while there were significant differences of CT values among other mPG grades(all P<0.05).Positive correlations were found between CT values of pulposus and mPG grades both on conventional CT and VNCa grayscale maps(r=0.504,0.745,both P<0.001),as well as VNCa types and mPG grades(r=0.900,P<0.001).Significant differences of mPG grades were found among different VNCa types(H=82.610,P<0.001).Conclusion DECT-VNCa imaging could be used to evaluate lumbar intervertebral disc degeneration.