New imaging techniques, promise or passe
I read with great interest, the article by Egger et al.  evaluating laser-induced fluorescence endoscopy (LIFE) and methylene blue (MB) directed biopsies for detection of dysplasia in Barrett's esophagus.
As the authors point out, there have be no fully published studies to date on this much talked about procedure. The authors found that LIFE and MB had limited accuracy, as did standard random biopsy. Although LIFE and MB detected a total of 5 cases of high grade dyplasia and 11 cases of low grade not seen on 4 quadrant random biopsy (4QB), they concluded that these methods we "not capable of increasing the diagnostic accuracy or replacing standard four quadrant biopsies."
How could these data lead to this conclusion? The authors discount all but 1 high grade, and 7 low grade lesions detected by LIFE or MB, because they were "within the 4QB protocol." It was assumed by the authors that these sites would have been biopsied by random techniques had it not already been sampled with AF or MB. Given that the biopsies were standard 7mm forceps, that dysplasia can be very focally distributed, and the area included within the 4QB covers 2 linear centimeters, it is difficult to assume that this exact site would have been biopsied with a random technique. This assumption, if incorrect, would result in underestimation of the value of LIFE or MB.
In addition, the authors further discounted the 1 remaining high grade dysplasia site, and 4 more low grade sites because they occured in patients with known cancer who presumably would be treated for the cancer regardless. There is little doubt that detection of low or even high grade dysplasia has little relevance if a cancer is already know. The main group of patients where LIFE, MB and other advanced techniques should be applied are those without macroscopically evident tumors and cancer. Discounting LIFE and MB for this reason may further underestimate its value.
If we do not discount these cases, then LIFE and MB appear to compliment 4QB for the detection of dysplasia, with each technique independantly detecting dysplastic sites that the other missed.
I agree that LIFE and MB remain contraversial and applaud the authors for publication of this first LIFE trial. Given the constraints of the study however, it may be premature to proclaim these techniques incapable. More, well conducted studies are clearly needed. The field of imaging technologies is also evolving rapidly and new, better techniques are constantly on the near horizon.
(1) K Egger, M Werner, A Meining, R Ott, H-D Allescher, H Höfler, M Classen, and T Rösch. Biopsy surveillance is still necessary in patients with Barrett’s oesophagus despite new endoscopic imaging techniques. Gut 2003; 52: 18-23
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