MRI may be used to define the origin and tissue characteristics of an adnexal mass. It may discriminate between benign and malignant pelvic tumors [22]. Generally, after gadolinium administration, ovarian cancer enhances earlier, more rapidly, and more avidly than benign lesions. Moreover, delayed images help in abdominal staging of ovarian cancer, increasing the detection of small peritoneal implants and omental infiltration, reaching an accuracy rate of 100 % in the correct malignant lesions characterization and of 75 % in staging [23].

Nowadays, a growing attention has been paid to the addition of diffusion-weighted imaging (DWI) supplemented with dynamic contrast-enhanced MR (DCE-MR) to morphologic imaging that improves tumor characterization, as well as peritoneal and lymph node staging [24–27]. DWI is based on the detection of higher cellular density and reduced extracellular space in malignant tumors than benign lesions. Therefore, the characterization of tissues by means of DCE-MR and DWI enables a move from morphologic assessment to characterization of tumor vascularity and cellularity [28].

Standard MRI sensitivity is considerably lower than DWI in the detection of abdominal implants, especially for those smaller than 1 cm and in anatomic areas where small tumor implants are adjacent to tissues with similar signal intensity, such as the right subdiaphragmatic space, omentum, root of the mesentery, and visceral peritoneum of the small bowel and bladder [29]. The combination of functional information with conventional anatomical visualization (DCE-MR) holds promise to characterize peritoneal disease accurately [30] showing a high per-lesion sensitivity (95 %) and specificity (80 %) in the description of peritoneal dissemination [29]. Recent studies have shown a better accuracy (91 %) for the abdominal staging in patients with ovarian cancer when DWI is performed, and the addition of DWI to conventional MRI increases the number of detected peritoneal lesions by 21–29 % [24, 25].

The DWI technique also provides more information about lymph node characterization. MRI lymphonodal status evaluation, based on simple dimensional parameter, has a sensitivity of 64.3 % and specificity of 75 % [29], while the addiction of DWI increases sensitivity up to 77 % and specificity to 91 % [24].

For this reason, the addition of DWI to an MRI protocol could help to reduce inter-center difference in ovarian cancer staging, leading to a good interobserver agreement for primary tumor characterization, and peritoneal and distant staging [24].

The possibility to achieve optimal/complete cytoreduction (RT = 0/<1 cm) is related to the extent of disease before surgery [53]. Unfortunately, there is no perfect tool to preoperatively determine whether patients can be optimally debulked or should be proposed for neoadjuvant chemotherapy. To quantify with more precision the intra-abdominal extent of the disease, a number of numerical ranking systems based on the intraoperative tumor assessment have been proposed. The first was PCI (peritoneal cancer index) [54] used to describe peritoneal spread in different malignant tumors. Subsequently, other scores have been proposed by Eisenkop et al. [55], Aletti et al. [4], and Fagotti et al. [56].

Tentes et al. [57] evaluated the role of PCI in ovarian cancer, combining the distribution of the tumor throughout 13 abdominopelvic regions with a lesion size score. Mean survival and 5-year survival rates for patients with a PCI <10 were 80 ± 12 months and 65 %, respectively, while mean survival and 5-year survival rates for patients with a PCI >10 were 38 ± 7 months and 29 %, respectively. Similarly, Eisenkop ranking system reflects the continuum of progressively extensive tumor involvement by ovarian cancer for five anatomic regions [55].

Aletti et al. [4] provided a validated system to track surgical outcomes in gynecologic cancer in order to improve overall patient care. Analyzing 564 patients with stage IIIC and IV epithelial ovarian cancer enrolled by three different US gynecological oncologic centers, they demonstrated that surgical complexity score, based upon complexity and number of surgical procedures performed, primarily influences morbidity and postoperative outcomes in ovarian cancer patients, including the ability to receive chemotherapy.

These systems have some limits: (a) they were actually based on the classical laparotomic approach (all); (b) they were designed for different pathologies [54]; and (c) they were calculated after completing surgery for a different purpose [4].

Another emerging surgical scoring system is based on the use of laparoscopy. Recently, different carcinomatosis scores have been compared to assess their relevance to predict resectability, morbidity, and outcome in 61 patients who had surgical treatment for AEOC. The authors found that the most relevant scoring system to predict postoperative complications was the Aletti score, but PCI and Eisenkop scores were also relevant. The best predictors of chances to achieve complete resection were the Fagotti-modified score and the PCI score [58].

The rationale for a laparoscopic evaluation prior to cytoreductive surgery includes (1) intraperitoneal diffusion of disease can be easily assessed by laparoscopy, and the surgeon may be more confident with a direct visualization of the cancer spread; (2) this approach could spare patients an unnecessary laparotomy resulting in suboptimal cytoreduction; (3) patients deemed not to be candidates for cytoreduction could proceed immediately to neoadjuvant chemotherapy without having to recover from laparotomy-related complications (incisional hernia); and (4) laparoscopy allows collection of tissue for definitive diagnosis and for molecular analyses.

Vergote et al. in 1998 [59] published the first study evaluating laparoscopy prior to cytoreduction in a retrospective analysis of 285 patients with advanced ovarian carcinoma. Then, two Italian studies were published in 2005 and 2006 [60, 61], suggesting a role of laparoscopy in detecting patients with advanced ovarian cancer suitable for NACT versus PDS.

Fagotti et al. [60] reported on the ability to assess by laparoscopy simple parameters in 65 AEOC patients: ovarian masses (unilateral or bilateral), omental cake or nodules, peritoneal and diaphragmatic carcinomatosis, mesenteric retraction, bowel and stomach infiltration, liver metastases, and bulky lymph nodes. Each variable was widely assessed by laparoscopy. The overall accuracy rate of laparoscopy in predicting optimal cytoreduction was 90 %. The NPV of clinical–radiological evaluation was 73 %, whereas the NPV of laparoscopy was 100 % (i.e., in no case when disease was judged incompletely resectable on the basis of laparoscopy findings was disease judged completely resectable at laparotomy). The PPVs of clinical–radiological evaluation and laparoscopy were both 87 %. This work was updated in 2006, when the authors [56] proposed a simple laparoscopy-based scoring system (PIV) to estimate the chances of achieving optimal cytoreduction based on the presence of an omental cake, peritoneal carcinosis, diaphragmatic carcinosis, mesenteric retraction, bowel infiltration, stomach infiltration, and liver metastases. Each parameter was assigned 2 points, if present. A score of greater than eight predicted a suboptimal surgery with a specificity of 100 %, a positive predictive value of 100 %, and a negative predictive value of 70 %. This score was validated in an external cohort of 55 French patients with stage III–IV ovarian cancer [62], showing that a simplified score (excluding omental cake and peritoneal carcinomatosis) could also be used. This represents the first study which supports the ability of an objective quantitative score based on laparoscopy more that on radiologic characteristics to foresee optimal cytoreduction chances for a single patient with advanced ovarian cancer. In 2008, Fagotti et al. [63] reported prospective data on 113 patients who underwent laparoscopy and had the likelihood of optimal cytoreduction evaluated using the PIV score [15]. The results confirmed that at a PIV of ≥8, the probability of optimal cytoreduction (residual tumor ≤1 cm) at laparotomy was 0; 40.5 % of the patients had a PIV of ≥8 and avoided unnecessary exploratory laparotomy. In 2011, the same group of investigators [64] prospectively estimated the learning curve for determining the PIV. The authors compared the scores for each laparoscopic parameter assigned by fellows and senior surgeons showing that fellows in gynecologic oncology with at least 12 months’ experience assigned laparoscopy-based scores similar to those of senior surgeons.