Here, we have shown that only 1 out of 102 patients resulted true positive for PC when analysed with RTE, that is, only 1 patient had an area really positive for PC in the absence of other neoplastic foci detected by systematic biopsy sampling. In the other 6 cases, RTE evidenced areas positive for PC, although additional neoplastic foci were found using systematic biopsy sampling in areas evidenced by RTE as negative.
In 22 out of 102 (21.5%) patients, RTE was falsely negative. Although RTE does not recognize suspicious areas for PC, in this subgroup of patients, it was found with systematic biopsy sampling. When we considered the subgroups of “true positives” and “false negatives” patients at RTE, any correlation between Gleason score and RTE was found, that is, high-grade lesions were not preferentially highlighted than those with low Gleason score.
In 25 out of 102 (24.5%) patients, RTE showed “false positive” areas for PC. This result suggests that RTE in about a quarter of cases detects areas that at the subsequent histological analysis resulted without neoplastic foci. These findings and the low RTE accuracy (53.92%) obtained in our study (which was expected between 65% and 80%) seem too low to substitute the actual approach based on the systematic biopsy sampling and limits the routinely application of current RTE technology into clinical practice.
Aigner et al. [18
] found that cancer detection rate per core was 4.7-fold greater for targeted than for systematic biopsy. In our study, the sensitivity was 2-fold enhanced. However, we should consider that the total detection rate in our series is 31%, and in 31/32 (96.8%) patients, the diagnosis of PC was made by systematic biopsy and not with RTE. Additionally, although different authors suggested that the higher the grade of the lesion the higher the RTE detection, our findings do not confirm this assumption, because when we analysed the Gleason score, the majority of patients were graded as 3 + 3. The only true positive detected by RTE had a Gleason score of 5 + 5. But if we analyse the high-grade group (Gleason scores: 4 + 3, 4 + 4, and 4 + 5), it appears that only two out of five patients were diagnosed with RTE.
Zhang et al. [22
] assessed the diagnostic impact of RTE on differentiating malignant from benign lesions, by analysing a series of 83 patients suspected of having PC in the prostate peripheral zones. Although they showed the significant value of RTE in the diagnosis of PC, additional studies are required to establish the full significance of their findings, as they applied RTE to patients with a PSA value >10
ng/mL and palpable or visible lesions [22
Walz et al. showed that RTE alone did not enable the identification of the PC index lesion with satisfactory reliability [7
]. In addition, they stated that RTE had a lower sensibility when compared to the systematic biopsy. Brock et al. [13
] concluded that “Further improvement is needed to achieve sensitivity values that can justify the implementation of these techniques within current clinical guideline” and that “The combination of RTE and data from randomized 12 core biopsies allows promising ability to correctly identify the PC index lesion.” Brock et al. evaluated whether RTE-guided biopsy improves PC detection compared to conventional systematic grey scale ultrasound guidance in 353 consecutive patients suspicious for prostate cancer [23
]. They concluded that sensitivity to visualize and detect PC improved using RTE in addition to grey scale ultrasound during prostate biopsy, although overall sensitivity did not reach levels to omit a systematic biopsy approach [23
]. In a previous study, Brock et al. suggested that RTE enhances grey scale ultrasound, although improvement is still needed to achieve a clinically meaningful sensitivity [13
The previous studies confirm the actual discrepancies in using RTE to detect PC. As we previously showed in the use of Colour-Doppler ultrasonography with or without contrast agents [24
], these controversies might be mainly due to (a) the reproducibility of applied methodologies that are operator-dependent, (b) the variability of the employed equipment, and (c) the criteria used to select the study population. We retain that the subjectivity of the operator in the detection of the prostate zones with higher stiffness is the primary cause for obtaining discrepant results. In this respect, it will be important to reduce the subjective interpretation and standardize as far as possible the employed method [25
]. Kapoor et al. suggested that combining RTE with trans-rectal ultrasound significantly improves the sensitivity to detect carcinoma prostate in patients with raised PSA; however, RTE is unable to differentiate PC from chronic prostatitis [9
]. One of the characteristic findings of elastography is its excellent detection of anterior tumours. The low detection rate of high-grade tumours in this analysis was likely due to the predominance of high-grade tumours in a peripheral location compared to the anterior location of the low-grade tumours [12
Finally, regarding the variability of the population enrolled in the present study, we tried to eliminate all the conditions that, to the best of our knowledge, might determine incorrect interpretations of PSA levels. It should be underlined that our population was characterized by a serum PSA value ranging from 2.5–10
ng/mL, and were excluded from the study subjects with palpable or visible lesions.
It is indubitable that additional multicentric studies using a higher number of patients are still necessary for evaluating the effectiveness of this imaging technique. To date, however, its routine application in PC detection remains unfounded.