**4. Discussion**

The present study analyzed several pre-operative factors, including patient characteristics and ultrasonographic, hysteroscopic, and anatomopathological features in patients pre-operatively diagnosed with AEH.

No statistically significant factor suggestive of concomitant EC could be identified regarding the anamnestic data analyzed. Obesity, diabetes, and hypertension were found to be similarly prevalent in both groups under analysis. This is in agreement with the literature, where the above risk factors are common in both diseases, and no medical comorbidities appear to be associated with concurrent EC in patients pre-operatively diagnosed with AEH [3,15].

In the present study, women with EC were on average of older age compared with real AEH, although no statistically significant difference was detected (*p* = 0.09). In the literature, older age seems predictive of concurrent EC at the time of hysterectomy for AEH [3,15]. The non-significance of the result in our study could be related to the low sample size.

Among ultrasonographic features, it appears that a thickened endometrial stripe, a greater diameter of the lesion, an interrupted endometrial–myometrial junction, and a high vascular density at CD was associated with increased odds of EC.

Results on endometrial thickness are consistent with prior data from Vetter et al. [3] on a retrospective case series of 169 patients, and from Abt et al. [16] on 378 patients. Both retrospective studies demonstrated that among patients with a preoperative diagnosis of AEH, those with preoperative endometrial stripe ≥ 20 mm were more likely to have concurrent EC. According to a prospective study on 2216 patients with AUB by the International Endometrial Tumor Analysis (IETA), endometrial thickness predictive for AEH is attested at 10.1 mm, while a mean endometrial thickness of 16 mm looks predictive for the EC [17]. The relevance and reproducibility of different studies of this finding should be applied in clinical practice by suggesting that endometrial thickness might be used as one preoperative determinant (Figure 2). *Diagnostics* **2022**, *12*, x FOR PEER REVIEW 8 of 13 AEH, those with preoperative endometrial stripe ≥ 20 mm were more likely to have con‐ current EC. According to a prospective study on 2216 patients with AUB by the Interna‐ tional Endometrial Tumor Analysis (IETA), endometrial thickness predictive for AEH is attested at 10.1 mm, while a mean endometrial thickness of 16 mm looks predictive for the EC [17]. The relevance and reproducibility of different studies of this finding should be applied in clinical practice by suggesting that endometrial thickness might be used as one preoperative determinant (Figure 2).

**Figure 2.** Transvaginal ultrasound (TVUS), endometrial thickness of two patients with a preopera‐ tive diagnosis of atypical endometrial hyperplasia (AEH). (**a**) TVUS: 7.7 mm of endometrial thick‐ ness with a posterior leiomyoma of the uterus, postoperative diagnosis of AEH. (**b**) TVUS: 22.8 mm of endometrial thickness, postoperative diagnosis of endometrial cancer pT1a G2. **Figure 2.** Transvaginal ultrasound (TVUS), endometrial thickness of two patients with a preoperative di-agnosis of atypical endometrial hyperplasia (AEH). (a) TVUS: 7.7 mm of endometrial thickness with a posterior leiomyoma of the uterus, postoperative diagnosis of AEH. (b) TVUS: 22.8 mm of en-dometrial thickness, postoperative diagnosis of endometrial cancer pT1a G2.

In our study, a greater ultrasonography diameter of the lesion appears to be strongly correlated with the presence of occult EC. This finding is not well investigated in the lit‐ erature. A retrospective study on 250 patients which analyzed the diagnostic value of en‐ dometrial volume under 3D ultrasound acquisition in endometrial lesions demonstrated that the endometrial volume was bigger in the EC group [18]. Regarding the ultrasound assessment of the vascularization of the lesion, although In our study, a greater ultrasonography diameter of the lesion appears to be strongly correlated with the presence of occult EC. This finding is not well investigated in the literature. A retrospective study on 250 patients which analyzed the diagnostic value of endometrial volume under 3D ultrasound acquisition in endometrial lesions demonstrated that the endometrial volume was bigger in the EC group [18].

this is a remarkably operator‐dependent finding, it has been reported in the literature that flow characteristics such as resistance (RI), pulsatility (PI), and peak systolic velocity (PSV) Regarding the ultrasound assessment of the vascularization of the lesion, although this is a remarkably operator-dependent finding, it has been reported in the literature that

In the present study, a significant difference was reported for the presence of in‐

In the prospective study by Van Den Bosh on 2216 patients, a regular endometrial–my‐ ometrial junction at ultrasonography is reported in 65% of AEH, very similar compared with EC in which endometrial–myometrial junction is described as irregular in 42% of cases [20]. In our study, 93.3% of AEH showed regular endometrial–myometrial junction, while only one case (6.3%) had an altered endometrial–myometrial junction. The regular endometrial–myometrial junction at ultrasonography appears in a much lower percent‐ age of EC (40%), in which altered junction was described as irregular in 60% of cases. This result can be analyzed considering the postoperative histologic results; in fact, in our case series, 83% of EC showed endometrial invasion. This data is not available in the previ‐ ously mentioned study, so we cannot assess inhomogeneity in the case series. Further‐ more, this variable is an extremely subjective, highly operator‐dependent assessment.

Hysteroscopy is considered the gold standard to diagnose endometrial lesions that are clinically or sonographically suspected. Hysteroscopy is a sensitive and specific method to identify coexisting endometrial carcinoma in patients with an AEH diagnosis

spective study by Van Den Bosh [20] where a highly vascularized pattern of presentation with a

color score of 3 or 4 at CD has been attributed to 65% of EC.

can also help in the differential diagnosis [19].

flow characteristics such as resistance (RI), pulsatility (PI), and peak systolic velocity (PSV) can also help in the differential diagnosis [19].

In the present study, a significant difference was reported for the presence of intracavitary vascularization in the Doppler study, since 64.2% of cases of EC were described as color score 2 or higher at ultrasonography. This result is consistent with the prospective study by Van Den Bosh [20] where a highly vascularized pattern of presentation with a color score of 3 or 4 at CD has been attributed to 65% of EC.

In the prospective study by Van Den Bosh on 2216 patients, a regular endometrial– myometrial junction at ultrasonography is reported in 65% of AEH, very similar compared with EC in which endometrial–myometrial junction is described as irregular in 42% of cases [20]. In our study, 93.3% of AEH showed regular endometrial–myometrial junction, while only one case (6.3%) had an altered endometrial–myometrial junction. The regular endometrial–myometrial junction at ultrasonography appears in a much lower percentage of EC (40%), in which altered junction was described as irregular in 60% of cases. This result can be analyzed considering the postoperative histologic results; in fact, in our case series, 83% of EC showed endometrial invasion. This data is not available in the previously mentioned study, so we cannot assess inhomogeneity in the case series. Furthermore, this variable is an extremely subjective, highly operator-dependent assessment.

Hysteroscopy is considered the gold standard to diagnose endometrial lesions that are clinically or sonographically suspected. Hysteroscopy is a sensitive and specific method to identify coexisting endometrial carcinoma in patients with an AEH diagnosis [21]. Standard hysteroscopy has better results than curette for aspirated endometrial sampling, such as Vabra sampling, which often fails to correctly diagnose endometrial polyps, as the samples have often insufficient endometrial mucosa [22]. That is, the visual assessment of the endometrial cavity reduces blind sampling. Even other poor sensitivity endometrial sampling techniques, such as dilation and curettage, cannot be considered reliable. One of the main advantages of hysteroscopy is the possibility to have a subjective evaluation of the endometrial pattern [23]. It is, therefore, necessary to perform a visual hysteroscopy, as a direct view of the lesion and its relationship to the uterine cavity is necessary for proper assessment (Figure 3). *Diagnostics* **2022**, *12*, x FOR PEER REVIEW 9 of 13 [21]. Standard hysteroscopy has better results than curette for aspirated endometrial sam‐ pling, such as Vabra sampling, which often fails to correctly diagnose endometrial polyps, as the samples have often insufficient endometrial mucosa [22]. That is, the visual assess‐ ment of the endometrial cavity reduces blind sampling. Even other poor sensitivity endo‐ metrial sampling techniques, such as dilation and curettage, cannot be considered reliable. One of the main advantages of hysteroscopy is the possibility to have a subjective evalu‐ ation of the endometrial pattern [23]. It is, therefore, necessary to perform a visual hyster‐ oscopy, as a direct view of the lesion and its relationship to the uterine cavity is necessary for proper assessment (Figure 3).

**Figure 3.** Hysteroscopic image of atypical endometrial hyperplasia (AEH). **Figure 3.** Hysteroscopic image of atypical endometrial hyperplasia (AEH).

As forthe hysteroscopic phase of preoperative diagnostics in our case series, the pres‐ ence of necrosis and an atypical vascularization proved to be strongly indicative of EC. Necrosis at hysteroscopic evaluation in our study has been much more frequently As for the hysteroscopic phase of preoperative diagnostics in our case series, the presence of necrosis and an atypical vascularization proved to be strongly indicative of EC.

detected in occult EC than in AEH at postoperative assessment (44.2% vs. 4.2%). This is consistent with the literature where necrosis has been included in many hysteroscopic

the case of occult EC (70.6%) compared with AEH (33.3%). Atypical vascularization usu‐ ally includes the finding of abnormal vessel sprouts, tortuous vessels, vessel loops, branching with angles over 90°, narrowing of vessels, a disorganized network, and an overall irregular distribution with an area with dense vessels, varying with an area with‐ out vessels [23]. The abnormal vascularization has been reported to be suggestive of ma‐ lignant neoplastic lesions of the endometrium, but this finding appears to have been de‐ rived from large retrospective cohorts and not from randomized controlled trials [24]. However, a simple increased vascular density must be combined with other parameters

scores for the diagnosis of suspected EC [23].

in the diagnosis of cancer [25].

Necrosis at hysteroscopic evaluation in our study has been much more frequently detected in occult EC than in AEH at postoperative assessment (44.2% vs. 4.2%). This is consistent with the literature where necrosis has been included in many hysteroscopic scores for the diagnosis of suspected EC [23].

Atypical vascularization (Figure 4) in our case series, was more frequently found in the case of occult EC (70.6%) compared with AEH (33.3%). Atypical vascularization usually includes the finding of abnormal vessel sprouts, tortuous vessels, vessel loops, branching with angles over 90◦ , narrowing of vessels, a disorganized network, and an overall irregular distribution with an area with dense vessels, varying with an area without vessels [23]. The abnormal vascularization has been reported to be suggestive of malignant neoplastic lesions of the endometrium, but this finding appears to have been derived from large retrospective cohorts and not from randomized controlled trials [24]. However, a simple increased vascular density must be combined with other parameters in the diagnosis of cancer [25]. *Diagnostics* **2022**, *12*, x FOR PEER REVIEW 10 of 13

**Figure 4.** Atypical vascularization at hysteroscopic evaluation. **Figure 4.** Atypical vascularization at hysteroscopic evaluation.

The finding of a protruding intracavitary lesion, on the other hand, seems to be more frequent in the case of AEH. This result is consistent with evidence from the literature in which it appears that the hysteroscopic finding of a polyp only rarely correlates with the presence of hyperplasia (about 2% of the cases), and subsequently of a cancerous polyp The finding of a protruding intracavitary lesion, on the other hand, seems to be more frequent in the case of AEH. This result is consistent with evidence from the literature in which it appears that the hysteroscopic finding of a polyp only rarely correlates with the presence of hyperplasia (about 2% of the cases), and subsequently of a cancerous polyp [22].

[22]. The sensitivity and specificity of hysteroscopic subjective assessment in determining the risk of adenocarcinoma have been investigated in numerous studies. The major limi‐ tation of this parameter is that it is the result of the subjective evaluation of numerous parameters that are not strictly determined. As a result, hysteroscopic subjective assess‐ ment emerges with a wide heterogeneity among different studies. Despite this point, sub‐ jective assessment is a valuable tool in the hands of an experienced clinician [15,26,27]. In our case series, subjective assessment ensured superior performance to that found in the The sensitivity and specificity of hysteroscopic subjective assessment in determining the risk of adenocarcinoma have been investigated in numerous studies. The major limitation of this parameter is that it is the result of the subjective evaluation of numerous parameters that are not strictly determined. As a result, hysteroscopic subjective assessment emerges with a wide heterogeneity among different studies. Despite this point, subjective assessment is a valuable tool in the hands of an experienced clinician [15,26,27]. In our case series, subjective assessment ensured superior performance to that found in the literature, with 80% of EC correctly identified by the expert clinician's report as high-risk lesions.

literature, with 80% of EC correctly identified by the expert clinician's report as high‐risk lesions. To standardize the subjective assessment reports, a structured hysteroscopic score based on lesion surface, necrosis, and vessels has been suggested [23]. Considering the relevance of subjective assessment in the diagnostic procedure of AEH, the definition of To standardize the subjective assessment reports, a structured hysteroscopic score based on lesion surface, necrosis, and vessels has been suggested [23]. Considering the relevance of subjective assessment in the diagnostic procedure of AEH, the definition of standardized and shared criteria for use by experienced operators appears to be a necessary development to improve the diagnostic definition of these lesions.

standardized and shared criteria for use by experienced operators appears to be a neces‐ sary development to improve the diagnostic definition of these lesions. One of the most controversial issues in the field of endometrial carcinoma is the se‐ lection of patients for lymph node staging to avert the risk of understaging. In this regard, One of the most controversial issues in the field of endometrial carcinoma is the selection of patients for lymph node staging to avert the risk of understaging. In this regard, preoperative diagnosis of adenocarcinoma is crucial in establishing the correct diagnostic and therapeutic course. Several studies have demonstrated that routine sen-

preoperative diagnosis of adenocarcinoma is crucial in establishing the correct diagnostic and therapeutic course. Several studies have demonstrated that routine sentinel lymph

For AEH and early‐stage low‐grade EC, a comprehensive surgical staging with lymph node assessment via lymphadenectomy or SLNB would result in overtreatment [31]. Yet, 12% of patients with a pre‐operative misdiagnosis of AEH show post‐operative histology of EC at a more advanced stage or mid‐ to high grade. This latter population might benefit

In our case series, almost 34% of the EC had FIGO stage greater than or equal to IB

The histological features of EC in patients with a previous diagnosis of AEH are re‐ markably heterogeneous in the literature. Myometrial invasion varies from 30 to 90% de‐ pending on the case series, while about 10% of cases show lymphovascularinvasion [4,26].

from lymph node assessment to guide adjuvant treatment [3].

(20.4% of all lesions), and 23% showed lymphovascular invasion.

tinel lymph node biopsy (SLNB) in all patients with AEH has limited benefit and is not cost-effective [28–30] given the high prevalence of low-grade and early-stage disease in this category. For AEH and early-stage low-grade EC, a comprehensive surgical staging with lymph node assessment via lymphadenectomy or SLNB would result in overtreatment [31]. Yet, 12% of patients with a pre-operative misdiagnosis of AEH show post-operative histology of EC at a more advanced stage or mid- to high grade. This latter population might benefit from lymph node assessment to guide adjuvant treatment [3].

In our case series, almost 34% of the EC had FIGO stage greater than or equal to IB (20.4% of all lesions), and 23% showed lymphovascular invasion.

The histological features of EC in patients with a previous diagnosis of AEH are remarkably heterogeneous in the literature. Myometrial invasion varies from 30 to 90% depending on the case series, while about 10% of cases show lymphovascular invasion [4,26].

This finding underscores the complexity of the histologic evaluation of hysteroscopic biopsy specimens and the need for accurate ultrasound examination by an experienced operator.

A strength of this study is the fact that demographic, anamnestic, hysteroscopic, and ultrasonographic parameters were evaluated in the same group of patients. Furthermore, the case series presented in our study is one of the largest in the literature to date analyzing all of the above parameters together in a single case series.

The major limitations of this study are the pure retrospective design, which makes it impossible to exclude possible confounding factors, and the fact that some of the variables are strongly based on subjective assessment. Subjective assessment is by its nature operatordependent and directly influenced by the experience and skills of the operator. As a result, the ultrasound and hysteroscopic evidence of the present study may not widely apply to all centers and may not be universally generalizable. In addition to this, the small sample size may not have allowed additional potentially clinically relevant differences to be identified. Statistical power was not calculated.

Some future insights for improving the preoperative diagnostic definition of AEH can be identified. In any patient with preoperatively diagnosed AEH, the diagnostic evaluation should include both ultrasound and visual hysteroscopy performed by experienced clinicians. To make hysteroscopic parameters more reproducible and reduce the subjectivity of the assessment as much as possible, a consensus between expert operators to define high-risk hysteroscopic characteristics would be necessary. Integration into the diagnostic pathway of a comprehensive score, including both hysteroscopic and sonographic features, may be evaluated in the future. Ultimately, to ensure the best clinical management for high-risk patients with EC-suggestive criteria despite a preoperative diagnosis of AEH, centralized management to specialized EC centers might be suggested.


*3.3. Signal Visualization*

Performing experiments with EEG can be very complex due to the difficulty of creating high-quality recordings. One of the main issues, apart from the design of the experiment itself, is measuring how well the data were captured. Electrodes inside devices are very sensitive to electromagnetic noise, so ensuring good skin contact is critical to avoid inconsistent results across recordings. For this reason, the library includes the necessary features to enable researchers to watch the signals of several devices in real time.

Sometimes, experiments are not run by medical experts, which is especially the case for low-cost devices. Therefore, we ensured that anyone can have access to the data while participants are being evaluated. The web server is started from the machine to which the devices are connected and returns to the console the internal IP address, together with the associated port. The process was simplified as two methods:

#### start\_streaming(search\_streams(), debug=True)

There are two different ways of visualizing the signals, compressed and expanded. In Figure 3, the overall compressed view of the website is shown with two devices at the same time. The latter is shown in Figure 4. Additionally, there are controls for the update interval (from 200 ms to 5 s), the channels to watch, the zoom level, and the possibility to play and pause the live view. For anyone without deep knowledge about performing experiments, we included a marker to know if a particular electrode had good skin contact. This helps to keep noise sufficiently low to retain a high probability of success. Lastly, the library automatically detects how many Muses are connected to the computer and adapts the interface to show those.

In Figure 5, we show our solution for experiments with multiple devices connected at the same time, while watching the streams. Additionally, the data file structure exported using the BIDS format is presented.

**Figure 5.** Solution designed for experiments.