Reply to the Letter to the Editor: “Efficacy of contrast-enhanced FDG PET/CT in patients awaiting liver transplantation with rising alpha-fetoprotein after bridge therapy of hepatocellular carcinoma”

by Rania Refaat, Mohammad Abd Alkhalik Basha, Mohammed Sobhi Hassan, Rasha S. Hussein, Ahmed A. El Sammak, Dena Abd El Aziz El Sammak, Mohamed Hesham Saleh Radwan, Nahla M. Awad, Somaia A. Saad El-Din, Engi Elkholy, Dina R. D. Ibrahim, Shereen A. Saleh, Iman F. Montasser and Hany Said (Mohammad_basha76@yahoo.com)

Efficacy of contrast-enhanced FDG PET/CT in patients awaiting liver transplantation with rising alpha-fetoprotein after bridge therapy of hepatocellular carcinoma

Dear Editor,

We thank the colleagues Sami Akbulut and Tevfik Tolga Sahin for their letter regarding our paper entitled “Efficacy of contrast-enhanced FDG PET/CT in patients awaiting liver transplantation with rising alpha-fetoprotein after bridge therapy of hepatocellular carcinoma” recently published in European Radiology [1].

However, although we really value their comments, we find them not much related to our paper. In detail:

i. The primary aim of our study was to assess the diagnostic accuracy and illustrate positive findings of contrast-enhanced 18F-FDG PET/CT in re-elevated serum alpha-fetoprotein (AFP) levels after efficient bridge therapy forgoing liver transplantation (LT).
ii. Although it was not the main aim of our study, we found some significant correlations and reported it. We reported a significant correlation between the alpha-fetoprotein level and maximum standardized uptake value (SUVmax) ratio. Our words were about the significant and not the strength of the correlation.
iii. We agree with you as the correlation coefficient (r = 0.2283) would be described as a “weak” positive correlation, but the association is clearly statistically significant (p = 0.0224).
iv. Any relationship should be assessed for its significance as well as its strength. The relationship can be strong and yet not significant. Conversely, a relationship can be weak but significant. The key factor is the size of the sample. Increase in sample size affects only significance, not strength of relationship. In other words, with a substantially large sample, every relationship can be statistically significant [2].
v. It is interesting to note that with a larger sample, low strength of correlation (r = 0.22), can be statistically significant (p < 0.02). However, this was an indication of a meaningful strength of association.

Regards,

Refaat R, Basha MAA, Hassan MS, et al.