所述AFI系统的示意图[
19]: white light emitted from a 300-W xenon lamp in the light source is separated with a rotary filter into an excitation light with a wavelength range of 390 to 470 nm and a green light of 540 to 560 nm wavelength. These fractionated lights radiate sequentially during the observation period. A barrier filter to remove reflected excitation light is set in front of a monochrome charge-coupled device. Light of 500 to 630 nm wavelength is selectively detected from both autofluorescence and reflected green light. A false color image is produced by allocating the detected and amplified autofluorescence signal to the green (G) channel and the reflected signal of green light to the red (R) and blue (B) channels in the ratio of 1 to 0.5.
基于AFE的优点,即结肠直肠病变中显示紫色,这是象在周围的正常大肠粘膜中绿色,几个随机临床试验显示在结肠镜检查筛选都集中在AFE的诊断效用“红色标志”。在使用AFI系统[一项随机对照研究
21],使用AFE和WLE改性背到背结肠镜检查是通过一个单一的,有经验的colonoscopist为167名患者在右侧结肠中进行。患者被随机或者与AFE或WLE以经历第一结肠镜检查(A组:AFE-WLE,B组:WLE-AFE)。在所有检测的息肉,肿瘤性病变的数目检测由AFE和结肠镜检查WLE分别为92和69。其中A组66个检测到的肿瘤性病变,47(71%)在第一AFE进行检测。相反,在B组95个肿瘤性病变中,只有50(53%)在第一WLE检测,并且由随后执行AFE检测45(47%)的病变。这表明显著更多的肿瘤病灶行WLE错过了与AFE(相
P
=
0.02)。
通过Ramsoekh等背到后端的比较研究。[
22]分析了AFE和WLE的用于在高风险患者的检测结直肠腺瘤的从与Lynch综合征或家族性CRC家庭的灵敏度。共有75名无症状患者要么WLE随后AFE或AFE随后WLE检查。返回到回结肠镜检查是由两个盲内镜医师进行。WLE鉴定腺瘤在28/41患者和AFE在四十一分之三十七患者中,表示检测功效的32%的差异。总共检测到95个腺瘤,65通过WLE和87由AFE,指示与WLE(92%比68%相比,AFE的显著更高的灵敏度;
P
=
0.001)。In addition, the additionally detected adenomas with AFE were significantly smaller than the adenomas detected by WLE (mean 3.0 mm versus 4.9 mm;
P
<
0.01)。
在AFE伪色范围的基础上确定的自体荧光强度和反射的绿光强度(绿色/红色,G / R比)之间的平衡的计算,并且这种平衡可以通过病变部位的厚度,血管的程度的影响,并且腺体密度。我们数值分析结直肠病变的AFE色调使用特殊的颜色分析软件[
24]。分析103个结直肠病变(22个非肿瘤性病变和81个肿瘤性病变),非肿瘤性病变的平均G/R比显著增高(1.17 (95% CI, 1.10-1.24),
ñ
=
22)中比在肿瘤性病变(0.65(95%CI,0.63-0.68),
ñ
=
81)(
P
<
0.001)。下受试者工作特征分析,用1.01 G / R比的截止值,它表明分别AFE具有98.8%和86.4%的灵敏度和特异性。该结果表明,在AFE色调可能直接可视化大肠病变的病理特征,其分析可以有助于在未来的结肠肿瘤性病变的自动光学诊断。
5.AFI系统的局限性
尽管与最新AFE技术更有优势,该系统仍具有一定的局限性需要被克服,为了实现其全部潜力。The outside diameters of the distal end and insertion tube are relatively thick (14.8 and 13.2 mm, resp.) compared to those used in conventional colonoscopy. This might limit maneuverability and, thus, hinder polyp detection, especially of those lesions harbored behind folds or flexures. Use of a transparent hood (TH) in AFE was shown to improve detection rates for colorectal neoplasms [
25]。本研究将561例患者分为四组:单纯WLE组、不含TH的WLI组;WLI + TH, WLE with TH;有孤独,就有孤独;AFI + TH, AFE with TH。AFI + TH组的肿瘤检出率(95%置信区间)显著高于单纯WLE组(1.96 [1.50-2.43]vs . 1.19 [0.93-1.44];
P
=
0.023)。