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Clinical research

The differential diagnostic value of dual-phase 18F-DCFPyL PET/CT in prostate carcinoma: methodological issues

Prostate Cancer and Prostatic Diseases volume 26, page 213 (2023)Cite this article

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The Original Article was published on 14 April 2022

We have read with interest the paper authored by Tian et al. [1], published by journal of Prostate Cancer and Prostatic Diseases. The aim of the study was to assess the diagnostic value of 18F-DCFPyL dual-time imaging in patients with prostate cancer (PC). The total number of patients was 38, of these 19 patients were detected with a biochemical relapse of PC. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), total accuracy rate and Receiver Operating Characteristic (ROC) curve were used to determine the accuracy of DCFPyL. Also, inter-rater agreement was noted between two physicians in visual analysis of dual-phase images. The sensitivity of SUV ratio delay and SUV max delay was 94.7 and 86% and specificity was 74.4 and 86% respectively. As conclusion, the delay dual-phase imaging is helpful in the differential diagnosis of prostate-associated malignant lesions and benign lesions.

In our opinion; however, there are considerable methodological issues regarding assessment diagnostic value of 18DCFPyL. There are important criterions that must be considered in designing a diagnostic study. There is a difference between test research and diagnostic research. The objective of test research is to assess whether a single diagnostic test (index test) adequately can show the presence or absence of a particular disease; however, the aim of diagnostic research is that whether index test appreciably adds to the diagnostic information that is readily available in clinical care [2]. In fact, the occurrence relation of test research can be calculated as P(T) = f(D) where P(T) is the probability of the test result of the single index test T, is studied as a function of the presence or absence of the target disease D, while occurrence relation of diagnostic research is P(D) = f (T1, T2, T3, … Tn), where T1 to Tn are the consecutive multiple diagnostic index tests. Thus, the authors must include all tests that are used to detect PC, then estimate the added value of 18DCFPyL comparing to other tests. Moreover, sensitivity and specificity are not clinically useful in diagnostic study and PPV and NPV are influenced by prevalence of the outcome [3]. In addition to earlier indexes, other accuracy indexes including likelihood ratio (LR) of a positive test (the probability of a positive test in the diseased divided by the probability of a positive test in the non-diseased), the likelihood ratio of a negative test (the probability of a negative test in the diseased divided by the probability of a negative test in the non-diseased) are appropriate measures that should be calculated [4]. LR + 3.6 and 6.1 of SUV ratio delay and SUV max delay respectively demonstrate that 18DCFPyL is actually suffer the lack of accuracy to use in the real clinical situations. Finally, diagnostic research must include representatives of the relevant patient domain, that is, patients presenting with symptoms and signs suggestive of the target disease. But in this study, only group of patients with evident disease is selected [5].

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References

  1. Tian A, Lin R, Yu J, Zhang F, Zheng Q, Yuan X, et al. The differential diagnostic value of dual-phase 18F-DCFPyL PET/CT in prostate carcinoma. Prostate Cancer Prostatic Dis. 2022:1-8.

  2. Grobbee DE, Hoes AW Clinical epidemiology: principles, methods, and applications for clinical research: Jones & Bartlett Publishers; 2014.

  3. Siamak S, Hadis G. Diagnostic value of serum connective tissue growth factor in rheumatoid arthritis: methodological issues. Clin Rheumatol. 2021;40:2105–6.

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Authors and Affiliations

  1. Department of Clinical Epidemiology, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, I.R., Iran

    Siamak Sabour & Hadis Ghajari

  2. Safety Promotions and Injury Prevention Research Centre, Shahid Beheshti University of Medical Sciences, Tehran, I.R., Iran

    Siamak Sabour

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  1. Siamak Sabour
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  2. Hadis Ghajari
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HG: writing of the original draft and conceptualization. SS: writing, review and editing; methodology; and validation.

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Correspondence to Siamak Sabour or Hadis Ghajari.

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Sabour, S., Ghajari, H. The differential diagnostic value of dual-phase 18F-DCFPyL PET/CT in prostate carcinoma: methodological issues. Prostate Cancer Prostatic Dis 26, 213 (2023). https://doi.org/10.1038/s41391-022-00576-9

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