THE ROLE OF COMPUTED TOMOGRAPHY IN PLANNING SURGICAL TREATMENT OF PERITONEAL DISSEMINATION FROM OVARIAN CARCINOMA

Uvod: Karcinomi jajnika pokazuju sklonost ka peritonealnoj diseminaciji čija je primarna terapija hirurska a uspešan hirurški tretman zahteva sprovođenje citoreduktivne hirurgije i citoreduktivne intraperitone­ alne hemioterapije. Preoperativna radiološka dijagnosti­ ka abdomena i karlice (CT, MR, PET­CT) je značajna u smislu detekcije peritonealne karcinomatoze i postavljan­ ja indikacije za hirurško lečenje. Cilj rada: Ukazati na značaj tehnike CT pregleda u detekciji peritonealnih implanata i određivanja PCI (peri­ tonealni kancer indeks). Materijali i metode: Istraživanjem je obuhvaće­ na 21 pacijentkinja kod kojih je histopatološki verifiko­ van karcinom ovarijuma u periodu od januara 2014. do februara 2015. Populaciju čine pacijentkinje prosečne starosti 57 godina. Svi pregledi su učinjeni na 128­sla­ jsnom Toshiba CT aparatu nakon peroralne pripreme i intravenske aplikacije kontrasta. Metodama deskriptivne statistike analizirani su stepen distenzije lumena tankog creva, veličina implanata u svim kvadrantima abdomena i na serozi tankog creva i ti nalazi su korelirani sa histopa­ tološkom vrednošću PCI. Rezultati: Svim pacijentima je preoperativno na osnovu CT pregleda merena veličina peritonealnih im­ planata i izračunat PCI (prosečna vrednost) kao i stepen distenzije 4 segmenta tankog creva i ti nalazi su korelirani sa histopatološkom vrednošću PCI. Pokazano je da dis­ tenzija lumena ima veliku ulogu jer je kompjuterizovana tomografija dala precizne podatke u pregledima u koji­ ma je ostvarena adekvatna distenzija jer su tada šanse za pogrešno dijagnostikovanje svedene na minimum. Zaključak: Radi bolje kvantifikacije peritonealne diseminacije a u cilju tačnijeg određivanja PCI potreb­ no je da tehnika CT pregleda abdomena i karlice bude prilagođena te je neophodno ostvariti dobru distenziju lumena tankog creva u cilju bolje detekcije peritonealnih implanata na serozi tankog creva. Ključne reči: peritonealna diseminacija, karcinom


Introduction
Ovarian cancer is the fifth most common malig nancy in women and the most common gynecologic ma lignancy to cause death [14].It usually affects women over the age of 60 [5].The risk of ovarian cancer is higher in women with a family history of the disease [1,5].Nine ty percent of ovarian cancers are sporadic, and 10% of it are due to hereditary syndromes such as breastovarian cancer syndrome with mutations in BRCA1 and BRCA2 genes [1, 5. 6. 7].
Ovarian cancer is usually in an advanced stage at diagnosis due to the presence of peritoneal carcinoma tosis, which develops as a result of peritoneal fluid circu lation.Peritoneal seeding is the most common pathway for the spread of ovarian cancer.Because 90% of ovarian cancers are surface epithelial carcinomas, the tumor cells are able to slough off the ovary and enter the peritoneal circulation, thereby seeding multiple sites [1].
Several methods of visualization are used as a pre operative examination of the tumor extensiveness, such as ultrasound [8], computed tomography, magnetic reso nance imaging( MRI) and F 18 FDG positron emission tomography (PET/CT) [911].Data obtained by com puted tomography and magnetic resonance imaging are similar according to previous researches, but computed tomography has the advantage of shorter protocol, lower price and it is more available in most of healtcare institu tions [9].
To achieve a detailed location, 13 abdominopelvic regions are accessed.Nine of the regions are defined by the intersection of two transverse and two sagittal planes that divide the abdomen into nine equal sized abdom inopelvic regions.The two transversal planes are the lowest aspect of the costal margin and the line that con nects the two spinae illiacae anteriores.The two sagittal planes are defined as the midclavicular lines billaterally.With this grid, nine equal sized regions are accurately de scribed.The small bowel is assessed using four additional abdominopelvic regions, designated abdominal regions 9 to 12, beginning on the upper jejunum and continuing to the lower ileum.After exploring the abdomen and pelvis for peritoneal implants the lesion size score (LS) is used to form the PCI (Table1).An LS0 score means that no malignant deposits are visualized.An LS1 score signifies that tumor nodules less than 0.5 cm in greatest dimen sion are present.An LS2 score signifies tumor nodules between 0.5 and 5.0 cm present.LS3 signifies tumor nodules greater than 5.0 cm in any dimension present.If there is a confluence of tumor, the lesion size is scored as 3 [12].
Peritoneal implants are softtissue masses that ap pear as solitary or multiple nodules.The nodules can co alesce to form plaques that coat the viscera.These plaques appear as areas of irregular softtissue thickening.Omen tal cake refers to tumor infiltration of greater omentum and is usually of soft tissue density but can also calcify.Common sites of metastases include the right hemidi aphragm, liver, right paracolic gutter, bowel, omentum, and pelvis.In the pelvis, implants can involve the supe rior surface of the sigmoid, the sigmoid mesocolon, the uterosacral ligaments lateral to the rectum, and the pelvic sidewall, bladder, rectum, and inguinal canals [1].
Treatment of peritoneal surface malignancy in volves cytoreductive surgery and intraperitoneal periop erative hyperthermic chemotherapy.Cytoreductive surgery reduces carcinomatosis to microscopic residual disease so that intraperitoneal hyperthermic chemother apy is able to eradicate cancer [1417].
Preoperative CT PCI is used to evaluate the ex tensiveness of peritoneal carcinomatosis so that optimal treatment can be conducted [18].

Materials and methods
Abdominal and pelvic computed tomography were perfomed and evaluated retrospectively in patients with peritoneal carcinomatosis in whom the primary tumor was ovarian carcinoma.The study group formed 21 fe male patients with histopathologically confimed ovarian carcinoma in period starting from January 2014 to Feb ruary 2015.Age of population is from 40 to 85 (table2).

Treatment cytoreductive surgery, intraperitoneal chemotherapy
Preoperative scanning was conducted on these patients at Rendgen department of First surgical clin ic of Clinical Centre of Serbia.All were examined with 128slice Toshiba CT scan after peroral preparation and intravenous application of contrast.Peroral preparation included 1500ml of water one hour earlier plus 500 ml water immediately before the scanning.Optiray 350 con trast agent was injected in a dose of 1ml/kg body weight.Scanning was performed in portalvein fase with scan de lay of 60 seconds.Reconstruction included 1mm thick slices in axial, coronal and sagittal plane.The criteria for the identification of a peritoneal metastasis was presence of a nodular, plaquelike, or infiltrative softtissue lesion in the peritoneal fat or on the peritoneal surface later com pared with histopathological PCI.We classified these val ues into three categories: low (PCI 010), moderate (PCI 1120) and high (PCI >21).
For the analysis of primary data descriptive sta tistical methods and the methods for dependency were used.Descriptive statistical methods included measures of central tendency (mean), measures of variability (stan dard deviation) and the relative numbers (structure indi cators).The method used for analysis of dependance is the Spearman rank correlation coefficient.The statistical hy potheses were tested at the level of statistical significance (alpha level) of 0.05.

Results
Histopathological PCI had the following results: 1 value of low PCI, 8 values of moderate PCI and 12 high PCI score.This study gave the next results: 4 cases with low PCI, 11 with moderate and 6 results of high PCI.Of these 21 cases, 13 cases (62%) were accurately classified

Medical Youth
Original articles into the categories by the CT PCI when compared with histopathological PCI (Chart 1).According to Spearman rank correlation, there is statistically moderategood significance of hpPCI and ctPCI correlation (rs = 0,543; p = 0,011).Average age of our patients is 57,6±10,1.Fig ures 1, 2 and 3 are demonstrating varying peritoneal im plants we found in this study.

Discussion
There is no universally accepted reference stan dard for imaging of peritoneal carcinomatosis [19].Pre operative CT of the abdomen and pelvis play an integral role in determining the extent of peritoneal and visceral disease in patients being considered for cytoreductive surgery and intraperitoneal chemotherapy for appen diceal, ovarian, colorectal, primary peritoneal, gastric, mesothelioma, and other rare types of gastrointestinal disease involving the peritoneum.Careful patient selec tion based on preoperative imaging may prevent unnec essary surgeries in patients whose tumors are too exten sive and cannot be adequately cytoreduced [20].Of these 21 cases, 13 cases (62%) were accurately classified into the categories by the CT PCI when compared with his topathological PCI in our study.According to studies we analized, classifying was more accurate but still poor.In their research concordance was found in 34(65%) cases of 52 [21].These authors state that the sensitivity of CT in detecting peritoneal implants was influenced by le sion size and that CT PCI significantly underestimates the intraoperative PCI.In the next study the observ er independently determined the PCI for MR and CT.Compared with surgical PCI, MRI correctly categorized tumor volume in 20 (91%) of 22 patients.CT correctly categorized tumor volume in 11 of 22 (50%) patients.Ac cording to authors, CT is characterized by its limited soft tissue contrast.On all imaging studies, softtissue con trast allows one to distinguish between tumors from ad jacent and the normal tissues.With CT, small peritoneal tumors may be indistinguishable from the surrounding tissues, resulting in reduced sensitivity for peritoneal car cinomatosis.MR imaging uses different types of image contrast to produce images that are more sensitive for showing peritoneal tumors [20].
Although computed tomography does not always give full precise results its purpose is still useful in pa tient evaluation with the suspicion of peritoneal dissem ination especially in the absence of other more sensitive and accurate imaging modalities.

LS 0
No tumor seen LS 1 Tumor up to 0.5cm LS 2 Tumor up to 5.0cm LS 3 Tumor > 5.0cm or confluence

Figure 1 .
Figure 1.CT scan of a 54yearold patient shows metastatic implants and nodules (arrow).

Figure 2 .
Figure 2. CT image of a 49yearold patient with a complete concordance about the PCI values between CT and histopathologic data (PCI value = 21).The CT examination shows peritoneal implant on serosa of distal jejunum.

Figure 3 .
Figure 3. CT image of a 57yearold pa tient with high PCI score, (CT value = 22, HP value = 25).The CT examination shows abnormal thickening of the great er omentum, which appears as omental cake (arrow).

Table 2 .
Patient characteristics

Table 1 .
PCI system based on lesion size score