Peritoneal carcinomatosis

Greater and lesser omenta: normal anatomy and pathologic processes

The peritoneum is the largest serous membrane in the body and the one with the most complex structure. The omentum is a double-layered extension of the peritoneum that connects the stomach to adjacent organs. The peritoneal reflections form the greater and lesser omenta, and the natural flow of peritoneal fluid determines the route of spread of intraperitoneal fluid and consequently of disease processes within the abdominal cavity. The omenta serve both as boundaries for disease processes and as conduits for disease spread. The omenta are frequently involved by infectious, inflammatory, neoplastic, vascular, and traumatic processes. Computed tomography (CT) is a primary diagnostic method for evaluation of omental diseases, most of which may manifest with nonspecific clinical features. Multidetector CT with multiplanar reformation allows accurate examination of the complex anatomy of the peritoneal cavity, knowledge of which is the key to understanding the pathologic processes affecting the greater and lesser omenta.

The perihepatic space: comprehensive anatomy and CT features of pathologic conditions

The liver is covered by visceral peritoneum except at the bare area, bed of the gallbladder, and porta hepatis. The investing peritoneum becomes contiguous with the adjacent structures such as the diaphragmatic peritoneum, lesser omentum, and ligamentum teres. An inflammatory process or tumors involving the perihepatic space are usually affected by intraperitoneal flow dynamics, which depend on the anatomy of the recess as well as gravity and negative subdiaphragmatic pressure. Pathologic conditions that occur in the perihepatic space include abnormal air, fatty masses, conditions producing fluid attenuation at computed tomography (CT), and soft-tissue masses. Enhancement of the hepatic capsule indicates inflammation, as is seen in Fitz-Hugh-Curtis syndrome. The perihepatic ligaments may be invaded by various conditions by means of direct invasion, subperitoneal extension, or extension along the lymphatic vessels. Knowledge of the normal anatomy of the perihepatic space together with the clinical history and characteristic features at CT can assist the radiologist in making the correct diagnosis.

Ultrasound and color power Doppler in the detection of metastatic omentum: a prospective study

OBJECTIVES

To analyze prospectively the ability of ultrasound to detect metastatic omentum in patients with suspicious pelvic masses and to describe the sonographic features of metastatic omental disease.

METHODS

One hundred and eighty-four patients were evaluated preoperatively by ultrasound examination and of these 173 were used in the analysis. We defined as an ultrasound-positive examination one which visualized intra-abdominal aperistaltic solid tissue, located above the bowel loops and below the anterior peritoneal surface. Preoperative sonographic findings were compared with pathological results.

RESULTS

Sonographic detection of metastatic omentum was achieved in 104 of 173 patients (60.1%), appearing as either solid aperistaltic tissue (80.8% of cases), or as solid discrete nodules (19.2%). When considering the echostructure of the surrounding bowel loops, this tissue appeared hypoechoic in 46 (44.2%) cases and isoechoic or slightly hyperechoic in the other 58 (55.8%) cases. In the overall series, the negative and positive predictive values (NPV and PPV) and the accuracy of ultrasound examination were 92.7%, 91.3% and 91.9%, respectively. When considering only the group of ovarian tumors, the NPV, PPV and accuracy were 91.9%, 94.6%, and 93.8%, respectively.

CONCLUSION

Ultrasound examination is highly accurate in detecting metastatic omental involvement in cases with suspicious pelvic masses.

Preoperative computed tomography and selection of patients with colorectal peritoneal carcinomatosis for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

AIM

A survival benefit has been observed for colorectal cancer patients with peritoneal carcinomatosis treated by cytoreductive surgery with intraoperative hyperthermic intraperitoneal chemotherapy (HIPEC). However, this treatment modality is associated with a considerable morbidity and mortality and in a significant number of patients survival is not improved. We studied whether poor survivors could be identified on preoperative computed tomography (CT), in order to avoid unnecessary surgery.

PATIENTS AND METHODS

Films of abdominopelvic CT scans from 25 such patients treated by cytoreductive surgery and HIPEC were retrospectively analysed by two radiologists separately. A simplified peritoneal cancer index (SPCI) was used to determine the extent of peritoneal involvement. Correlation between the on preoperative CT based SPCI-scores as well as number of involved abdominopelvic areas (N) and survival was examined with the log-rank test. The relation between each affected region and survival was evaluated with Cox regression analysis.

RESULTS

The preoperative SPCI- and N-scores of one of the radiologists had no statistically significant prognostic value, while for the second radiologist SPCI > or = 7 and N > or = 4 were associated with particularly poor outcome. Additionally, the presence of ileocaecal region involvement and, depending on the radiologist, the occurrence of tumour deposits in the left subdiaphragmatic area on CT appeared to be unfavourable prognostic signs.

CONCLUSIONS

The prognostic value of preoperative conventional CT appeared to be radiologist dependent and may, therefore, be of limited value in selecting colorectal cancer patients with peritoneal carcinomatosis who will not benefit from extensive cytoreductive surgery followed by HIPEC.

Intra-abdominal desmoplastic small round cell tumors: CT findings and clinicopathological correlations in 13 cases

PURPOSE

We report computed tomography (CT) findings in 13 patients with a primary abdominal desmoplastic small round cell tumor.

MATERIALS AND METHODS

13 cases (12 men, 1 woman, mean age=24.8 years) were found in our hospital database between 1991 and 2003. Clinical, CT and histopathological features were studied retrospectively.

RESULTS

Peritoneal involvement was the most common feature. In 10 cases, several lobulated peritoneal soft tissue masses (with a mean of four masses per patient) were seen. Two patients had diffused irregular peritoneal carcinomatosis without any distinct peritoneal masses. One patient had a solitary mass in the pelvic space. The main sites of peritoneal involvement were the pelvic space (n=7), omentum (n=5), retroperitoneal space (n=4), small bowel mesentery (n=3), paracolic gutter (n=2 on the right and n=1 on the left), transverse colon mesentery (n=1), peri-splenic space (n=1), peri-hepatic space (n=1). The soft tissue masses were often bulky (mean 6cm, range 1-28cm), lobulated and heterogeneous with hypodense areas (in 73% of cases). In six cases, moderate ascites was seen. In one case of pelvic involvement, unilateral hydronephrosis was seen. Adenopathies were present in seven cases at the time of the diagnosis (at intraperitoneal, retroperitoneal and pelvic sites in six patients and in the groin in one patient). Five patients had liver metastases (four lesions per case excepted one patient with 30 metastases). Associated thoracic metastases were seen in three patients. The diagnosis was confirmed with four CT-guided percutaneous biopsies.

CONCLUSION

Although CT features are nonspecific, the diagnosis of desmoplastic small round cell tumor may be suspected in young men with multiple bulky heterogeneous peritoneal soft tissue masses. Imaging is useful for staging and also to guide biopsies.

Computed tomography manifestations of peritoneal diseases

The peritoneal cavity is a potential space that is divided by the peritoneal reflections into various complex subspaces. It can be involved in many disease processes including developmental, inflammatory, neoplastic and traumatic conditions. Computed tomography is highly sensitive and consistent in detecting peritoneal pathology. This pictorial essay aims to emphasize and illustrate the CT features of the spectrum of peritoneal diseases.

A RETROSPECTIVE STUDY ON THE SONOGRAPHIC FINDINGS OF ABDOMINAL CARCINOMATOSIS IN 14 CATS

A retrospective review was performed on 14 cats with histology- or cytology-proven carcinomatosis. The mean age was 12.7 years with a median of 11 years. The diagnosis of carcinomatosis was made by histology in 11 cats and cytology in three cats. Twelve cats had cytologic examination of the peritoneal free fluid and seven cats (58.3%) had evidence of malignant cells. The primary tumor site was determined in 13 cats. The most common organ locations for the primary tumor were the liver (n = 5), pancreas (n = 3), and small intestine (n = 3). Other sites were stomach and spleen in one cat each. Epithelial cell neoplasia was the primary tumor type in 11 cats. Two cats had abdominal lymphomatosis and one cat had abdominal sarcomatosis secondary to metastatic hemangiosarcoma. Free peritoneal fluid and masses in the connecting peritoneum were found in all cats (100%). Additional findings included primary or metastatic masses in abdominal organs in 10 cats (71.4%), lymph node enlargement in five cats (35.7%), pleural effusion in three cats (21.4%), parietal peritoneal masses in two cats (14.3%), and visceral peritoneal masses in one cat (7.1%). Masses in the connecting peritoneal may be a very specific finding for carcinomatosis in cats, especially with a concurrent abdominal neoplastic mass. Parietal and visceral peritoneal masses, while uncommon in this series of cats, have not been reported for other diseases and seem to strongly support a diagnosis of carcinomatosis.

Peritoneal carcinomatosis from colorectal or appendiceal origin: correlation of preoperative CT with intraoperative findings and evaluation of interobserver agreement

BACKGROUND AND OBJECTIVES

In patients with colorectal cancer, it is important to diagnose peritoneal carcinomatosis as well as to detect location and size of peritoneal tumor dissemination in view of treatment planning. The aim of this study was to investigate the detection accuracy of computed tomography (CT).

METHODS

Preoperative CT-scans from 25 consecutive patients with peritoneal carcinomatosis from colorectal or appendiceal origin were independently blindly reviewed by 2 radiologists. The presence and diameter of tumor deposits were noted in seven abdominopelvic areas. Intraoperative findings were regarded as the gold standard. Agreement was assessed using the Kappa index and the chi-square test.

RESULTS

The presence of peritoneal carcinomatosis was detected in 60 and 76% of those patients by each of the radiologist. Detection of individual peritoneal implants was poor (kappa = 0.11/0.23) and varied from 9.1%/24.3% for tumor size <1 cm to 59.3%/66.7% for tumor size >5 cm. Overall sensitivity, specificity, accuracy, positive (PPV) and negative predictive value (NPV) for tumor involvement per area were 24.5%/37.3%, 94.5%/90.4%, 53.0%/60.0%, 86.2%/84.4%, and 47.3%/50.8%, respectively. Accuracy of tumor detection varied widely per anatomic site. Statistically significant interobserver differences were noted, specifically for tumor size of 1-5 cm (P = 0.007) and localization on mesentery and small bowel (kappa = 0.30, P = 0.04).

CONCLUSIONS

In colorectal cancer, CT detection of peritoneal carcinomatosis is moderate and of individual peritoneal tumor deposits poor. Interobserver differences are statistically significant. Therefore, preoperative CT seems not to be a reliable tool for detection of presence, size, and location of peritoneal tumor implants in view of treatment planning in patients with colorectal cancer.

Le péritoine « témoin » de la pathologie abdomino-pelvienne

Most inflammatory, infectious or tumoral diseases of the bowel and abdominal organs may secondarily involve the peritoneum which acts as a mirror of the diseases. Multidetector CT allows breathhold acquisitions through the abdomen and pelvis providing high spatial and contrast resolution imaging at all phases of contrast distribution as well as MPR and 3D capabilities.